Effects of the length and timing of nighttime naps on task performance and physiological function Hidemaro Takeyama I ; Shun Matsumoto II ; Kensaburo Murata I ; Takeshi Ebara I ; Tomohide Kubo I ; Norihide Tachi I ; Toru Itani I I Health Sciences of Life , Work and Environment . Department of Environmental Health Science and Health Promotion . Nagoya City University Graduate School of Medical Sciences . Nagoya , Japan II The Institute for Science of Labor . Kawasaki , Japan Correspondence ABSTRACT OBJECTIVE : To examine the effects of the length and timing of nighttime naps on performance and physiological functions , an experimental study was carried out under simulated night shift schedules . METHODS : Six students were recruited for this study that was composed of 5 experiments . Each experiment involved 3 consecutive days with one night shift ( 22 : 00 - 8 : 00 ) followed by daytime sleep and night sleep . The experiments had 5 conditions in which the length and timing of naps were manipulated : 0 : 00 - 1 : 00 ( E60 ) , 0 : 00 - 2 : 00 ( E120 ) , 4 : 00 - 5 : 00 ( L60 ) , 4 : 00 - 6 : 00 ( L120 ) , and no nap ( No - nap ) . During the night shifts , participants underwent performance tests . A questionnaire on subjective fatigue and a critical flicker fusion frequency test were administered after the performance tests . Heart rate variability and rectal temperature were recorded continuously during the experiments . Polysomnography was also recorded during the nap . RESULTS : Sleep latency was shorter and sleep efficiency was higher in the nap in L60 and L120 than that in E60 and E120 . Slow wave sleep in the naps in E120 and L120 was longer than that in E60 and L60 . The mean reaction time in L60 became longer after the nap , and faster in E60 and E120 . Earlier naps serve to counteract the decrement in performance and physiological functions during night shifts . Performance was somewhat improved by taking a 2 - hour nap later in the shift , but deteriorated after a one - hour nap . CONCLUSIONS : Naps in the latter half of the night shift were superior to earlier naps in terms of sleep quality . However performance declined after a 1 - hour nap taken later in the night shift due to sleep inertia . This study suggests that appropriate timing of a short nap must be carefully considered , such as a 60 - min nap during the night shift . Keywords : Night work . Shift work . Sleep , physiology . Students . Questionnaires . RESUMO OBJETIVO : Para investigar os efeitos da duração e horário de cochilos noturnos sobre o desempenho e as funções fisiológicas foi realizado um estudo experimental por meio do trabalho noturno simulado . MÉTODOS : Seis estudantes foram recrutados para o estudo que consistiu de cinco experimentos . Cada experimento consistia de três dias consecutivos com um turno noturno ( 22 : 00 - 8 : 00h ) seguido por um período de sono diurno e noturno . Os experimentos compreendiam cinco condições em que a duração e o horário dos cochilos eram manipulados : 0 : 00 - 1 : 00 ( E60 ) , 0 : 00 - 2 : 00 ( E120 ) , 4 : 00 - 5 : 00 ( L60 ) , 4 : 00 - 6 : 00 ( L120 ) e sem cochilo ( N - nap ) . Durante os turnos noturnos , os participantes foram submetidos a testes de desempenho . Um questionário sobre cansaço subjetivo e um teste de freqüência crítica de luz foram aplicados depois dos testes de desempenho . A variabilidade da freqüência cardíaca e a temperatura retal foram registrados continuamente durante os experimentos . Polissonografia também foi realizada durante o cochilo . RESULTADOS : A latência de sono foi menor e a eficiência do sono maior no cochilo em L60 e L120 que em E60 e E120 . O sono de ondas lentas nos cochilos em E120 e L120 foi mais longo que em E60 e L60 . O tempo médio de reação em L60 ficou mais longo depois do cochilo e mais rápido em E60 e E120 . Os cochilos em horário mais cedo serviram para neutralizar a queda no desempenho e funções fisiológicas durante o turno noturno . Houve uma ligeira melhora do desempenho ao se tirar um cochilo de duas horas num horário mais tarde durante o turno , mas houve piora depois de um cochilo de uma hora . CONCLUSÕES : Os cochilos na última metade do turno noturno foram melhores em termos de qualidade de sono do que os cochilos em um horário mais cedo . O desempenho , no entanto , piorou depois de um cochilo de uma hora em um horário mais tarde durante o turno por causa da inércia do sono . O estudo indica que o horário adequado de um cochilo curto deve ser cuidadosamente considerado , tal como um cochilo de 60 minutos durante o turno noturno . Descritores : Trabalho noturno . Trabalho em turnos . Sono , fisiologia . Estudantes . Questionários . INTRODUCTION Shift workers tend to suffer from a chronic lack of sleep or cumulative fatigue from being compelled to follow a wake - sleep cycle not conforming to their innate biological rhythms . 6 Sleepiness and fatigue among shift workers are known as potential risks for occupational safety and health in many industries . 1 , 4 Taking a nap during the night shift has been suggested as an effective way to prevent fatigue or other complaints related to shiftwork . 8 On the other hand , nighttime naps have a transient negative effect on performance immediately after awakening . This effect is known as " sleep inertia " . Previous studies have reported that the severity of sleep inertia depends on the timing of the nap taken and the sleep stage just before awakening . 7 , 9 Therefore , it is necessary to consider the effect of nap length and timing on performance and alertness . It is suggested that an approximately two - hour nap is an appropriate length , because the first cycle of nocturnal sleep in adults usually lasts approximately two hours including the duration of both Slow Wave Sleep and REM sleep . However , some studies indicate a similar effect on alertness after less than a 2 - hour nap compared with a 2 - hour nap . 11 , 14 Regarding the timing of the nap , Gillberg 5 indicated that performance in the early morning after a 1 - hour nap in the later half of the night shift was superior to that during the first half of the night shift . Sallinen et al 15 reported that a nap shorter than 1 - hour starting at 1 : 00 or 3 : 50 improved alertness in the early morning . However , there are few studies that focus on the timing and length of nighttime naps . In the present study , the effects of the length and timing of nighttime naps on changes in task performance and physiological functions were investigated by an experimental study carried out under simulated night shift schedules . METHODS Participants and design Six students voluntarily participated in this study . All participants were healthy males , aged 19 - 22 yrs , non - smokers and not taking medications continuously . Participants were given a detailed description of the study , and their informed consent was obtained in writing . The study was composed of 5 experiments , each lasting 3 consecutive days with one night shift ( 22 : 00 - 8 : 00 ) , followed by day sleep ( 11 : 30 - 17 : 00 ) and night sleep ( 0 : 00 - 7 : 00 ) . The experiments had 5 different conditions in which the length and timing of naps were manipulated : 0 : 00 - 1 : 00 ( E60 ) , 0 : 00 - 2 : 00 ( E120 ) , 4 : 00 - 5 : 00 ( L60 ) , 4 : 00 - 6 : 00 ( L120 ) and no nap ( No - nap ) . All participants underwent the five experiments in a counterbalanced order . In order to minimize carry - over effects , there were at least five days between the experiments . The participants were instructed to do their usual daily activities and sleep between the experiments . Their sleep and awake between the experiments were measured by an actigraph . None of the participants appeared chronic or acute sleep deprivation before the experiment . On the day before the beginning of the first series of experiments the participants visited the laboratory to practice the performance tests and also slept overnight in the laboratory for adaptation to experimental environment . During the night shifts , the participants were requested to do a set of task and performance tests every hour except when they were taking a nap . The task consisted of typing documents into a computer for 30 minutes . Performance tests were composed of a choice reaction time test ( CRT ) , a logical reasoning test ( LRT ) , a vigilance test ( VT ) , and a critical flicker fusion frequency test ( CFF ) . After the performance tests , the participants filled out a questionnaire on subjective fatigue . It took about 20 minutes to finish the 4 performance tests and the questionnaire . Therefore , the participants were able to take a break of at least 5 minutes before moving to the next set . The participants were served two biscuits and 60 ml of mineral water every break time during the night shifts . In this study , the total number of task and performance tests differed among nap conditions . The number of the task and the performance tests during night shift was 10 for N - nap , 8 for E60 and L60 , and 7 for E120 and L120 . Electroencephalography ( EEG ) , electrooculography ( EOG ) , and electromyography ( EMG ) were recorded during adaptation to night sleep , nighttime naps , daytime sleep and night sleep . During all experiments , heart rate variability was continuously recorded except while taking a bath . Measurements A computerized test battery , including a CRT , a VT , and a LRT , was used . In the CRT , the participants were asked to press keys as quickly as possible with a finger of the dominant hand when a figure appeared randomly in the center of the displays . The test procedure for VT was similar to CRT , but the intervals for presenting the numbers on the display were arranged randomly between 1 and 10 sec . The LRT was performed as described by Baddeley . 2 " AB " , or " BA " , were randomly shown , followed below by " A is ahead of B , " " A is not preceded by B , " " B follows A , " and so on . Participants were requested to answer true or false by pressing the appropriate key as quickly as possible . Critical flicker fusion frequencies were examined by recognizing a blinking light using the Roken Digital Flicker ( model RDF - 1 ; Shibata Co . , Ltd . , Tokyo , Japan ) . The participants gazed at a red light placed in the middle of a slightly illuminated screen . The red light was presented automatically with flicker frequencies ranging from 60 Hz to 25 Hz in descending order . Participants were requested to press a button when they perceived flickering . The measurements were performed five times . EEG , EOG , and EMG were recorded with Poltmate AP1124 ( TEAC Instruments Co . , Ltd , Japan ) . Sleep stages were analyzed according to Rechtschffen and Kales . 13 The EEG and EOG were recorded from the C4 - A1 , C3 - A2 , E1 - A1 , and E2 - A1 using silver - silver chloride electrodes . The EMG was recorded with disposable electrodes . The questionnaire consisted of 25 questions with regard to subjective fatigue feeling established by the Research Group for Occupational Fatigue of Japan Society for Occupational Health . 15 Heart rate variability was recorded with a Holter type ECG recorder ( Active Tracer AC301 , GMS Inc . , Tokyo , Japan ) during all experiments . The data were entered in a computer after measurement . Then the frequency analysis of R - R intervals by the Memcalc system ( Suwa Trust Co . , Ltd . , Japan ) , and high frequency power ( HF ; 0 . 15 - 0 . 4 Hz ) and low frequency power ( LF ; 0 . 04 - 0 . 15 Hz ) were calculated . The component of high frequency power and LF / HF were taken as the index of parasympathetic and sympathetic nerve activity , respectively . 10 Mean values of power components were calculated every hour during the night shift . The results were the values in relation to the mean values during the entire night shift . Data analysis Each item on the questionnaire was scored on a 1 to 5 points scale . The average rates of complaints regarding 5 factors ( feeling of drowsiness , instability , uneasiness , local pain or dullness , and eyestrain ) were calculated . The sleep physiology data were analyzed by factorial two - way ANOVA by " timing of naps " and " length of naps " as factors . Fatigue , CFF and performance data from all nap conditions ( 22 : 30 , 23 : 30 , 2 : 30 , 3 : 30 , 6 : 30 , 7 : 30 ) were analyzed by two - way , repeated measures ANOVA with " time " and " nap condition " as factors . Our main interest was in the interaction effect . However , no significant interactions were observed . Therefore , the results for fatigue , CFF and performance tests during the night shift were indicated as relative changes in relation to the values just before beginning of night shift ( 21 : 30 ) . Comparisons between the 5 nap conditions at the same measurement points were performed using one - way ANOVA . Post - hoc analysis was done using Scheffe ' s method . Statistical analyses were performed using SPSS version 10 . 0 . RESULTS Sleep latency for the nap in L60 and L120 was significantly shorter than for the nap in E60 and E120 ( Table ) . Total sleep time was significantly longer and sleep efficiency was also higher in the nap in L60 and L120 than in the nap in E60 and E120 . On the other hand , Slow Wave Sleep and its percent of total sleep in the nap in E120 and L120 was significantly longer than in the nap in E60 and L60 . There were no significant interactions between time and length of naps on any of the sleep parameters . There was no significant difference in the HF component of heart rate variability ( an index of parasympathetic nerve activity ) between the naps taken in the second half of the night shift and those in the first half of the night shift . Mean reaction times of VT and RT in the N - nap condition deteriorated as the night work progressed . Although the mean reaction times in VT and RT tended to be faster after the nap in E60 and E120 compared to N - nap condition , there was no significant deference ( Figure 1 and 2 ) . However , significant delay in mean reaction time at 8 : 00 was observed in the E120 condition . There were no positive effects of L60 and L120 on mean reaction times after the naps . On the contrary , in L60 significant delays in mean reaction time were observed after nap compared to N - nap . The CFF values tended to improve after the nap in E60 and E120 compared with No - nap ( Figure 3 ) . The CFF values after the nap in L60 had an apparent tendency to deteriorate but the differences were not significant . Drowsiness score increased as night work progressed in the No - nap condition ( Figure 4 ) . In the four experimental conditions , drowsiness tended appeared to be suppressed after the nap compared with the No - nap but there were no significant differences . The scores for local pain or dullness in L60 and L120 tended to decrease after the nap . Feelings of instability , uneasiness , and eyestrain showed fewer differences between nap conditions . DISCUSSION The sleep efficiency of 120 - and 60 - min naps in the latter half of the night shift was higher than in the earlier two naps , and slow wave sleep in the two 120 - min naps was longer than in the two 60 - min naps . Therefore , a 120 - min nap in the latter half of the night shift was superior to other nap conditions in terms of sleep quality . These findings were consistent with previous studies indicating the superiority of naps taken near the circadian nadir . 5 , 14 The data on higher parasympathetic nerve activity during the 120 - min and 60 - min naps in the latter half of the night shift compared with the 120 - min and 60 - min naps in the former half is consistent with the sleep quality data . Task performance after 120 - min and 60 min naps in the first half of the night shift tended to be improved for a while after awakening . Task performances following the later two naps showed no clear improvements after awakening regardless of the superior sleep quality achieved . On the contrary , performance deteriorated after awakening for the later 60 - min nap . Lubin et al 7 reported that performance decreased immediately after taking a nap and the effect of this " sleep inertia " continued for 5 - 15 minutes after waking . Previous studies have indicated that both duration and intensity vary . Dinges et al 3 reported that deeper sleep just before awakening leads to more severe sleep inertia . Naitoh 9 suggested that sleep inertia might be more severe around the circadian nadir than at other times of the day . In the present study the relations between degrees of sleep inertia and sleep stage upon awakening were not consistent between participants . In addition , the slower reaction time continued until the end of the night shift . Sallinen et al 14 examined the effects of 50 - min and 30 - min naps on three - shift workers with timing similar to that in our study . However , their results indicated no serious sleep inertia and no difference between earlier and later naps . Our findings were not consistent with previous studies regarding the severity and duration of sleep inertia . We have identified no convincing explanations for this difference so far . It might be due to slight differences in nap length and timing or different experimental conditions . In VT , the reaction times between the No - nap condition and L120 were already different at the beginning of the night shift . In this study , the participants were informed which nap condition they had to perform at beginning the experiments . It was presumed that some psychological factors partly caused the differences between the No - nap condition and L120 . Subjective feelings of sleepiness in this study were not clearly reduced by the naps . Saito & Sasaki 13 reported that subjective fatigue was clearly decreased by both a 1 - and 2 - hour nap . Our results were not consistent with their study . The score for local pain or dullness in L60 and L120 tended to decrease after a nap regardless of significant sleep inertia . Further studies with larger sample sizes are necessary to resolve such discrepancies . In summary , naps in the second half of the night shift were superior to earlier naps in terms of sleep quality . However performance declined after a 1 - hour nap taken later in the night shift due to sleep inertia . It was suggested from this study a short ( 60 minute ) nap must be carefully timed to gain optimum benefit . The number of participants in this study was low ( n = 6 ) , producing low statistical power . Therefore , further investigations using larger sample sizes are necessary . ACKNOWLEDGEMENT The authors express their appreciation to the Tokyo Electric Power Company for leasing the electroencephalograph and performance test battery for this study . REFERENCES 1 . Akerstedt T . Psychological and psychophysiological effects of shift work . Scand J Work Environ Health 1990 ; 16 : 67 - 73 . 2 . Baddeley AD . A 3 - min reasoning task based on grammatical transformation . Psychonom Sci 1968 : 10 : 341 - 2 . 3 . Dinges DF , Orne MT , Orne EC . Assessing performance upon abrupt awakening from naps during quasi - continuous operations . Behav Res Methods Instrum Comput 1985 ; 17 : 37 - 45 . 4 . Dinges DF . An overview of sleepiness and accidents . J Sleep Res 1995 ; 4 : 4 - 14 . 5 . Gillberg M . The effects of two alternative timings of a one - hour nap on early morning performance . Biol Psychol 1984 ; 19 : 45 - 54 . [ Medline ] 6 . Kogi K . Sleep problems in night and shiftwork . J Hum Ergol ( Tokyo ) 1982 ; 11 : 217 - 31 . 7 . Lubin A , Hord D , Tracy M , Johnson LC . Effects of exercise , bedrest and napping on performance decrement during 40 hours . Psychophysiology 1987 ; 13 : 334 - 9 . 8 . Matsumoto K . Effects of nighttime naps on body temperature changes sleep patterns , and self - evaluation of sleep . J Hum Ergol ( Tokyo ) 1981 ; 10 : 173 - 84 . [ Medline ] 9 . Naitoh P , Angus RG . Napping and human functioning during prolonged work . In : Dinges DF , Broughton RJ , editors . Sleep and alertness : chronobiological , behavioral and medical aspects of napping . New York : Raven Press ; 1989 . p . 221 - 46 . 10 . Ohtomo N , Tanaka Y . New method of time series analysis and ' MemCalc ' . In : Saito K , editor . A recent advance in time - series analysis by maximum entropy method . Hokkaido : Hokkaido University Press ; 1994 . p . 11 - 29 . 11 . Purnell MT , Feyer AM , Herbison P . The impact of a nap opportunity during the night shift on the performance and alertness of 12 - h shift workers . J Sleep Res 2002 ; 11 : 219 - 27 . [ Medline ] 12 . Rechtschaffen A , Kales A . A manual of standardization terminology , techniques and scoring systems for sleep stages of human subjects . Washington ( DC ) : US Government Printing Office ; 1968 . 13 . Saito Y , Sasaki T . The effect of length of a nocturnal nap on fatigue feeling during subsequent early morning hours . J Sci Labour 1996 ; 72 : 15 - 23 . 14 . Sallinen M , Harma M , Akerstedt T , Rosa R , Liiqvist O . Promoting alertness with a short nap during a night shift . J Sleep Res 1998 ; 7 : 240 - 7 . [ Medline ] 15 . Tachi N , Itani T , Sakai K , Kondo Y , Seo A , Sasaki T et al . Validity of a newly developed questionnaire for evaluating work - related fatigue feeling . 27 th International Congress on Occupational Health . Correspondence to Hidemaro Takeyama Health Sciences of Life , Work and Environment Nagoya City University Graduate School of Medical Sciences Kawasumi 1 , Mizuho - ku , Nagoya 467 - 8601 , Japan E - mail : hidemaro @ med . nagoya - cu . ac . jp Presented at the XVI International Symposium on Night and Shiftwork , November 2003 . Santos , SP , Brazil . This work was supported in part by a Grant - in - Aid for Scientific Research ( B ) 14370142 from the Ministry of Education , Culture , Sports , Science and Technology , Japan . Received on 15 / 3 / 2004 . Approved on 27 / 9 / 2004 © 2006 Faculdade de Saúde Pública da Universidade de São Paulo Avenida Dr . Arnaldo , 715 01246 - 904 São Paulo SP Brazil Tel . / Fax : + 55 11 3068 - 0539

Evaluation of the factors interfering with drug treatment compliance among Brazilian patients with schizophrenia Avaliação dos fatores de aderência ao tratamento medicamentoso entre pacientes brasileiros com esquizofrenia Moacyr Alexandro Rosa ; Marco Antônio Marcolin ; Hélio Elkis Psychiatry Unit , Universidade de São Paulo ( USP ) , São Paulo ( SP ) , Brazil Correspondence ABSTRACT BACKGROUND : Treatment noncompliance among schizophrenic patients is as high as 50 % . In order to rate compliance and assess the most significant differences between compliant and noncompliant patients , a Brazilian population of schizophrenic outpatients was followed for one year . METHODS : Fifty outpatients were selected . Clinical interview , the Brief Psychiatric Rating Scale - Anchored version ( BPRS - A ) and an expanded version of the Rating of Medical Influences ( ROMI ) scale ( used to rate patient attitudes toward compliance ) were applied at baseline . The BPRS - A was used in the follow - up visits ( approximately once a month ) . Missing two consecutive appointments without explanation or taking less than 75 % of the medication ( by written family report ) was considered noncompliance . RESULTS : Noncompliance was 48 % over one year . Patients in the noncompliant group presented initial worsening of psychotic symptoms ( p < 0 . 05 ) and had been treated for a shorter length of time ( p = 0 . 007 ) . The ROMI scale showed that " perceived day - to - day benefit " was most strongly correlated with compliance , and feeling " distressed by side effects " was most strongly correlated with noncompliance . DISCUSSON : This study evaluates the frequency of noncompliance and the main reasons for complying in a population of schizophrenic outpatients . CONCLUSIONS : Severity of psychopathology was found to correlate with noncompliance ( although not necessarily as its cause ) , as well as with duration of treatment . Noncompliance rates are high and must be taken into account in any treatment program . Keywords : Schizophrenia / therapy ; Patient compliance ; Antipsychotic agents / therapeutic use ; Patient acceptance of health care ; Treatment refusal RESUMO INTRODUÇÃO : A não aderência ao tratamento em pacientes com esquizofrenia chega a 50 % . Com a finalidade de avaliar a taxa de aderência e as principais diferenças entre pacientes aderentes e não aderentes , uma população de pacientes esquizofrênicos em tratamento ambulatorial foi acompanhada por um ano . MÉTODOS : Cinqüenta pacientes foram selecionados . Foi realizada uma entrevista clínica e aplicadas as escalas BPRS - A ( Escala Breve de Avaliação Psiquiátrica - Versão Ancorada ) e uma versão expandida da ROMI ( Escala de Influências Medicamentosas ) na avaliação basal . A BPRS - A foi utilizada nas visitas seguintes ( cerca de uma vez por mês ) . A falta consecutiva a duas consultas sem explicação ou a ingestão de menos de 75 % ( segundo relato familiar escrito ) da medicação foram consideradas não aderência ao tratamento . RESULTADOS : A taxa de não aderência encontrada foi de 48 % em um ano . O grupo não aderente teve uma piora na sintomatologia psicótica inicial ( p < 0 , 05 ) e havia estado em tratamento por um tempo mais curto ( p = 0 , 007 ) . A escala ROMI mostrou que a " percepção de benefício diário " foi o fator mais associado à aderência e o sentimento de " desconforto por efeitos colaterais " estava mais associado à não aderência . DISCUSSÃO : Este estudo avalia a freqüência de não aderência e as principais razões para aderir ao tratamento numa população de pacientes esquizofrênicos . CONCLUSÕES : A gravidade da sintomatologia pode ser um fator relacionado com a aderência , mas não necessariamente sua causa , bem como o tempo de duração do tratamento . As taxas de não aderência são altas e devem ser consideradas em qualquer programa de tratamento . Descritores : Esquizofrenia / terapia ; Cooperação do paciente ; Antipsicóticos / uso terapêutico ; Aceitação do paciente de cuidados de saúde ; Recusa do paciente ao tratamento Introduction Treatment noncompliance is one of the main obstacles to controlling schizophrenia . 1 Noncompliance significantly increases the rate of relapse ( a worsening of symptoms , not necessarily leading to hospitalization ) , 2 as well as the rate of rehospitalization 3 and the length of readmissions . 4 There is also a strong correlation between compliance and risk of future hospitalization . 3 The need for maintenance therapies with antipsychotics in schizophrenia is currently acknowledged unanimously . Although antipsychotics are not perfect , most can control the disorder , leading to relief from the so - called positive symptoms . Socioeconomic factors are also important . In the USA , the annual cost of hospital admissions due to schizophrenia relapse is approximately US $ 2 . 3 billion . The accumulated cost for readmission within two years after discharge is approximately US $ 2 billion . 5 Noncompliance to antipsychotic therapy accounts for approximately 37 % of these costs . 5 It has been reported that one - year rates of noncompliance are 41 % ( range , 10 to 76 % ) when oral antipsychotics are used and 25 % ( range , 14 to 36 % ) when deposit antipsychotics are used . 6 For the two methods of administration , a mean rate of 55 % ( range , 24 to 88 % ) has been reported . 7 Determining the magnitude of each of the factors that influence compliance is not an easy task . There are at least three scales currently available to carry out this task . These scales assess patient attitude toward treatment compliance . They are the Van Putten & May Scale 8 ( for measuring neuroleptic dysphoria ) , the Drug Attitude Inventory 9 ( a widely used scale that has even been translated into several languages ) 10 - 14 and the Rating of Medication Influences ( ROMI ) scale 15 ( also widely used ) . 16 - 17 The last is the most comprehensive , especially for rating compliance in outpatient clinics . A Portuguese translation of the ROMI scale is currently available . 18 In Brazil , there have been few studies of treatment compliance in schizophrenia . The present study was carried out in order to rate compliance among schizophrenic outpatients at two public health clinics in the city of São Paulo over a one - year period . Methods 1 . Subjects Fifty outpatients from two public health clinics in the city of São Paulo ( Hospital das Clínicas , n = 23 , and Santa Casa de Misericórdia de São Paulo , n = 27 ) , diagnosed with schizophrenia according to the DSM - IV , 19 were randomly selected to be monitored regarding treatment compliance for a period of one year . Patients were selected by inviting the first patient to be treated on each Tuesday from January to June of 1996 . The Hospital das Clínicas ( HC ) has a specific day ( Tuesdays ) for treating patients diagnosed with schizophrenia , whereas the Santa Casa ( SC ) does not . Tuesdays were chosen because that was the day that the assessor could be present at both clinics . This was not considered a source of error . Patients could be either starting treatment or returning for a regularly scheduled appointment . Patients who were using clozapine were excluded due to their unique profile . First of all , they tend to be more refractory patients . In addition , since they require weekly blood tests over a period of 18 weeks , they present a different pattern of compliance . After a full explanation of the study design , patients were invited to participate and written informed consent was obtained . Since the study was relatively simple and interfered very little with the follow - up treatment , all invited patients agreed to participate . 2 . Instruments Psychopathology was quantified at baseline using the Brief Psychiatric Rating Scale - Anchored version ( BPRS - A ) . 20 A Brazilian ( Portuguese ) translation of this scale is now available . 21 It is important to mention that this version , in order to avoid misidentification of the psychopathology , adopts a rating scale ranging from 0 to 6 points , which is different from the traditional 1 to 7 - point scale . 22 Therefore , the degrees of psychopathological severity tend to be lower . The main reasons for compliance and noncompliance were evaluated using the ROMI ( we used a slightly expanded version of the scale , which was provided by the author himself , Peter Weiden , but that essentially contains the same structure as the original scale ) . The existing version of the scale in Portuguese 18 is a simple translation , which has not been validated but helped us interpret the version we used . The ROMI consists of two parts . The first part is semi - structured , comprising questions regarding lifestyle status ( e . g . supervised or unsupervised , alone or with family , homeless or not ) , locale of treatment , medication regimen prescribed ( specific antipsychotic , medication other than antipsychotics , oral or intramuscular administration , dosage , frequency , duration of treatment ) , overall patient attitude toward treatment and medication ( positive or negative , voluntary or forced compliance ) and overall attitude of the family , as well as of the caregiver , toward treatment and medication . The second part of the scale is divided into two sections : reasons for compliance and reasons for noncompliance . In each section , there is an initial open question ( " What is your primary motivation for taking the medication ? " and " What is your primary motivation for not taking the medication ? " ) . Subsequently , the sections present " closed questions " regarding the main reasons for wanting or not wanting to take the medication . In this part of the scale , the patient is asked to indicate the degree of influence of each item of the scale ( reasons for compliance and reasons for noncompliance ) . The graduated responses to each are " no influence " , " mild influence " and " strong influence " ( 1 , 2 and 3 , respectively , or 9 when it is impossible to evaluate the degree of influence ) . 15 The assessor was one of the authors and was blinded as to the compliance status of the patients . Demographic data were also collected , and a clinical interview , concerning the total length of time in psychiatric treatment , duration of treatment at the current institution , number of previous hospitalizations , the schizophrenia subtype ( according to the DSM - IV ) , the daily dose of antipsychotics in chlorpromazine equivalents 23 - 24 and the method of administration , was conducted at baseline . 3 . Follow - up assessment In the following interviews ( in general , one per month , according to the appointments scheduled for each patient by the attending psychiatrist ) , the BPRS - A was used in order to assess the symptoms of the disorder . Compliance was assessed through the use of a report written by a family member ( who was instructed to mark with an X the pills that had not been taken since the previous appointment ) . For each patient , a family member was designated as responsible for this task . When this member ( always the same one ) had to miss the appointments , the signed report was brought by the patient . Noncompliance was defined as taking less than 75 % of the prescribed dose within the preceding 30 days ( adapted from Buchanan , 1992 25 ) . If the patient missed two consecutive appointments without explanation , the family was contacted in order to inquire about the degree of compliance . In order to avoid deviations , patients continued to be seen by their own psychiatrists , without assessor intervention in the treatment regimen . Patients were monitored for a period of one year unless they were noncompliant , in which case the follow - up assessment was discontinued . After one year , the two groups ( compliant and noncompliant patients ) were compared . 4 . Statistical analysis The general patient profile was analyzed using the t - test , the chi - square test or Fisher ' s exact test . The means of each ROMI item were analyzed using the Student ' s t - test . Since the follow - up assessment was discontinued in noncompliant patients , the last observation carried forward ( LOCF ) 26 method was used in order to analyze their BPRS - A scores . Mean BPRS - A values ( from the baseline to the end of the follow - up assessment ) for each group were compared using analysis of variance for repeated measurements . Results 1 . Patient Sample The sample comprised 20 men ( 40 % ) and 30 women ( 60 % ) . The mean age was 36 ± 6 . 82 years ( range , 18 to 45 years ) . Forty ( 80 % ) were Caucasian , 5 ( 10 % ) were Black , and 5 ( 10 % ) were Asian . Thirty - nine ( 78 % ) were single , 10 ( 20 % ) were married and 1 ( 2 % ) was divorced . The mean length of psychiatric treatment was 6 . 94 ± 6 . 32 years ( range , 0 to 22 years ) . The length of treatment at the current institution was 30 . 54 months ( SD : 33 . 42 , variation 1 - 175 ) . The mean number of previous hospitalizations was 1 . 56 ± 1 . 73 ( range , 0 to 5 ) . The schizophrenia subtype was found to be paranoid in 39 patients ( 78 % ) , disorganized in 7 ( 14 % ) and residual in 4 ( 8 % ) . The mean dose of antipsychotic ( in chlorpromazine equivalents ) was 264 ± 165 . 07 mg ( range , 50 to 850 mg ) . All patients were using typical antipsychotic agents or risperidone , and the method of administration was oral . None had a history of abuse of , or dependence upon , drugs or alcohol or both . 2 . Comparison of the groups The rate of noncompliance over a one - year period was 48 % ( n = 24 ) . Figure 1 shows compliance over time ( in months ) . Comparing both groups , there were no differences in the demographic variables ( Table 1 ) , including the mean ages ( 33 . 57 ± 7 . 08 for compliant patients and 32 . 50 ± 6 . 62 for noncompliant patients , p = 0 . 581 ) . There were no differences in the total length of psychiatric treatment , in the number of previous hospitalizations , in the subtype of schizophrenia or in the mean daily dose of the antipsychotic . There was a significant difference in the length of treatment at the current institution ( t = - 2 . 82 , df = 48 , p = 0 . 007 ) . Mean length was 17 . 54 ± 11 . 59 months in the noncompliant group and 42 . 53 ± 41 . 87 months in the compliant group . Table 2 shows the BPRS - A values for both groups . Although not significant , there was a tendency toward a worse evolution in the psychopathology of the patients of the noncompliant group . 3 . Comparison between the institutions The institutions were homogeneous regarding mean age ( HC : 33 . 6 ± 5 . 8 years ; SC : 32 . 55 ± 7 . 5 years ; p = 0 . 576 ) and the other demographic characteristics ( Table 3 ) . There was a significant difference ( p = 0 . 004 ) in compliance between the two institutions . Compliance was higher among HC patients ( 34 % , n = 17 ) than among SC patients ( 18 % , n = 9 ) . With regard to psychopathology , there was no difference between the groups from the two institutions ( Table 4 ) . There was a significant difference ( p = 0 . 001 ) in the item " length of treatment at the institution " , which was , on average , 46 . 52 ± 42 . 92 months at the HC and 16 . 92 ± 11 . 27 months at the SC . The " length of treatment at the institution " was also compared between the subgroups of compliant and noncompliant patients at the two institutions . Among the compliant patients , the length of treatment was significantly higher ( p = 0 . 005 ) at the HC ( 55 . 58 ± 45 . 97 months ) than at the SC ( 17 . 88 ± 14 . 2 months ) . No such difference was observed among the noncompliant patients ( HC : 20 . 83 ± 16 . 27 months ; SC : 16 . 44 ± 9 . 93 months , p = 0 . 434 ) . Comparison of the data regarding the disease revealed a significant difference ( p = 0 . 0342 ) in the number of hospitalizations between the noncompliant patients at the HC and those at the SC ( Table 5 ) but not between the compliant patients at the two . 4 . Comparison between the groups using the ROMI scale None of the items of the ROMI scale differed significantly between the compliant and the noncompliant group . 5 . Reasons for compliance The responses to the ROMI open question ( " What is your main motivation for taking the medication ? " ) were grouped into four main reasons , based on the items addressed in the closed questions : " perceived day - to - day benefit " , " relapse prevention " , " respect for authority " and " fear of hospitalization " . " Perceived day - to - day benefit " ( e . g . improved sleep , tranquility , fewer voices , organization of thoughts , etc . ) was the main reason for wanting to take the medication ( 88 % , n = 44 ) , followed by " relapse prevention " ( ¨ 6 % , n = 6 ) , " respect for authority " ( 4 % , n = 2 ) and " fear of hospitalization " ( 2 % , n = 1 ) . With regard to the ROMI " closed questions " , the item " perceived day - to - day benefit " was most often given as the main reason for compliance . Table 6 shows the degree of influence of each of the other items . 6 . Reasons for noncompliance In the ROMI open question ( " What is your main motivation for not taking the medication ? " ) , most of the patients denied that there were any reasons for noncompliance ( 40 % , n = 20 ) . The responses to this question were also grouped based on the items addressed in the closed questions ( Table 7 ) . Two of the responses given could not be categorized in any of the " closed " items . One patient reported " forgetfulness " and five mentioned " a desire to be normal " ( 10 % ) . In the " closed questions " ( Table 8 ) , the item " distressed by side effects " was the main reason given for noncompliance . Discussion Compliance may be defined as to what degree the behavior of a person is in agreement with the counsel offered by the physician or health clinic professional . 27 For various reasons , it is a theme that is difficult to study . First , there are different ways to rate compliance , and there is little concordance among the different measurements . 7 Second , compliance is rarely an all - or - nothing proposition and may include omission errors , errors in dosage or administration of medications , as well as the influence of factors such as the use of medications that were not prescribed . 28 In the psychiatric literature , demographic variables have not been consistently correlated with compliance in schizophrenia . 29 - 32 The severity of the disorder , however , has been found to correlate with such compliance , 33 which is understandable since patients presenting more severe psychopathology would be expected to be less compliant . Poor insight ( in the sense of not believing that one is sick 34 ) has also been correlated with noncompliance . 35 The perception of benefit and a subjective sensation of well - being seem to have been more consistently correlated with compliance . 36 - 37 Comorbidity with alcohol abuse or abuse of other substances is a strong predictor of noncompliance . 38 In one study , one - fourth to two - thirds of the patients who discontinued the use of antipsychotics reported side effects as the main reason for noncompliance . 39 Among outpatients , reporting side effects has been correlated with , or found to be predictive of , noncompliance . 25 In the literature , patients who use depot preparations present a lower rate of noncompliance than do those who use oral medications . 5 Little or no correlation has been found between complexity of the administration of medication and compliance in schizophrenia . 9 , 25 Supervision of the intake of medications by family or friends seems to be correlated with higher rates of compliance . 37 Practical difficulties , such as financial inability to purchase the medicine or pay for transportation ( homelessness , for example ) , may be important factors . 40 Finally , the literature shows that , although the process of interaction between physicians and patients has yet to be fully investigated , a positive therapeutic alliance seems to be crucial for compliance . However , there are important methodological problems that make it difficult of draw conclusions regarding this issue . 41 The rate of noncompliance found in our sample over a one - year period ( 48 % ) is in agreement with those found in the literature ( approximately 50 % 6 , 9 , 25 ) . The method used to rate compliance ( written family report ) has many limitations when compared to other methods such as pill counting , screening blood or urine for drugs , etc . However , Park & Lipman 42 showed that it is a reliable method for detecting gross errors in compliance . In addition , one must take into account the fact that any method used may lead to false perception of compliance ( since patients may , for example , want to know the reason for such measures or modify their compliance when under study ) . Nevertheless , the length of follow - up assessment was prolonged , and different antipsychotics were used , which would have made it difficult to count pills or screen for medications . Although there are undoubtedly errors , this method seems to be the means of determining compliance that is most commonly used by physicians in their daily clinical practice . The duration of treatment at the institution in question was also an important point . We found that patients who had been undergoing treatment for a longer length of time were more compliant . This difference might be seen as a consequence rather than as a cause since more compliant patients tend to stay longer at the institution . In addition , it is possible that the initial phase of treatment in a psychiatric institution can determine future compliance . With regard to abuse of , or dependence on , drugs or alcohol or both , the results of the present study do not confirm the data in the literature . It was intriguing that there was no such report among the patients in the sample . We believe that this is due to a bias related to the patient belief that the medications should not be taken concomitantly with alcohol or other drugs and patients might be afraid of being " caught " by the assessor , who could tell their family or their physician about it . In addition , the use / abuse was not investigated in depth in the present study ( using specific scales or analysis of blood and urine , for example ) . Another possible source of error may have been the greater number of women in the sample since women tend to present lower rates of such use / abuse . An important point was the severity of the psychopathology among the compliant and noncompliant groups . We observed an initial worsening , which tended to remain constant during the follow - up period in the noncompliant group . This initial worsening may have been related to noncompliance , but this is difficult to analyze . In this case , as in the case of treatment duration at the institution , it is difficult to establish a causal direction since noncompliance naturally leads to a worsening of symptoms , and vice - versa . The differences found between the institutions cannot be explained by the demographic characteristics since the group was demographically homogeneous . Longer treatment duration at the institution seems to have been the reason for greater compliance . However , this difference was observed only among compliant patients and not among noncompliant patients in follow - up treatment for the same ( shorter ) length of time at both institutions . The ROMI scale did not accurately predict patient behavior toward compliance since there was a concordance in the responses given by both groups . It is unlikely that this failure was related to the use of an expanded version since the version used contains all of the items of the original scale . The main motivation for compliance was the perception of a potential benefit in daily life . Patients need to feel better regarding something that disturbs them ( e . g . sleep disturbance , anxiety , hearing voices , disorganized thoughts , etc ) . It is well known that improvement takes time , and patients must be aware of that . The influence of the family manifested itself in the closed questions ( " positive family belief " and " supervision " ) . Another interesting point is that there was a gradation of only 28 % , with a strong degree of influence , in the positive relationship with the physician . In a more careful analysis , however , this item presented the lowest percentage of " no influence " responses ( 18 % ) . In fact , the overall degree of influence was 82 % ( " mild " or " strong " influence ) . This item was considered somehow important for compliance . It is intriguing to see that , on the open question , 40 % of the patients stated that there was no excuse for noncompliance ( Table 7 ) , despite the fact that half of them would become noncompliant during the follow - up assessment . Fenton 7 drew attention to this dichotomy ( a disjunction between belief and behavior , very likely to be found in schizophrenia ) . On the open question , 36 % of the patients reported that the side effects ( especially anticholinergic and extrapyramidal ) were the main reason for noncompliance . Taking into consideration the fact that approximately 40 % denied having any reason for noncompliance , of those who had a reason , 60 % said that the reason was the distress caused by side effects . The same was seen on the closed questions . We found a rate of 39 % for " strong degree of influence " and 22 % for " mild degree of influence " . Finally , two items appeared in the open questions and were not considered by the ROMI closed questions . The first was " a desire to be normal " , which is different from " denial of the disease " or " lack of insight " . The other was " forgetfulness " , which , despite having been reported by only one patient , shows the importance of practical tips to help patients to remember to take the medications . 7 Conclusions In the present study , we found a high rate of noncompliance during the one - year follow - up of patients with schizophrenia . This has important consequences for the patients , for their families and for society . Demographic variables were not found to be correlated with compliance in this study . The initiation of treatment at an institution seems to be the period in which the patient is most vulnerable to noncompliance . Therefore , it may be crucial to give special attention to compliance during this period . We found the severity of the psychopathology to be greater in the noncompliant group . Although severity was not necessarily a cause for noncompliance , it may act in a bidirectional fashion ( noncompliance causing worsening of symptoms and worsening leading to lower compliance ) . In the present study , it was not possible to predict the behavior toward compliance using a scale at the beginning of the assessment period . This method was useful , however , for learning what patients think about the factors that influence their compliance . In their opinion , the factor that is most important for compliance is the perception of a day - to - day benefit , and the factor that is most important for noncompliance is the inconvenience caused by side effects . Noncompliance has multiple causes , and the most important ones , alone or in combination , can and should be identified in the individual cases , thereby facilitating the prevention of such noncompliance . In order to manage noncompliance , a broad understanding of the factors involved , including the patient , the disease , the treatment and environmental factors , is required . Further studies should be carried out in our milieu in order to assess the possible inherent characteristics of treatment compliance in Brazilian patients . References 1 . Weiden PJ , Dixon L , Frances A , Appelbaum P , Haas G , Rapkin B . Neuroleptic noncompliance in schizophrenia . In : Tamminga CA , Schulz SC . Schizophrenia research . New York : Raven Press ; c1991 . v . 1 . [ Advances in neuropsychiatry and psychopharmacology ] . 2 . Linn MW , Klett CJ , Caffey EM Jr . Relapse of psychiatric patients in foster care . Am J Psychiatry . 1982 ; 139 ( 6 ) : 778 - 83 . [ Medline ] 3 . Green JH . Frequent rehospitalization and noncompliance with treatment . Hosp Community Psychiatry . 1988 ; 39 ( 9 ) : 963 - 6 . [ Medline ] 4 . Caton CL , Koh SP , Fleiss JL , Barrow S , Goldstein JM . Rehospitalization in chronic schizophrenia . J Nerv Ment Dis . 1985 ; 173 ( 3 ) : 139 - 48 . [ Medline ] 5 . Weiden PJ , Olfson M . Cost of relapse in schizophrenia . Schizophr Bull . 1995 ; 21 ( 3 ) : 419 - 29 . [ Medline ] 6 . Young JL , Zonana HV , Shepler L . Medication noncompliance in schizophrenia : codification and update . Bull Am Acad Psychiatry Law . 1986 ; 14 ( 2 ) : 105 - 22 . Review . [ Medline ] 7 . Fenton WS , Blyler CR , Heinssen RK . Determinants of medication compliance in schizophrenia : empirical and clinical findings . Schizophr Bull . 1997 ; 23 ( 4 ) : 637 - 51 . [ Medline ] 8 . Van Putten T , May PR . Subjective response as a predictor of outcome in pharmacotherapy . Arch Gen Psychiatry . 1978 ; 35 ( 4 ) : 477 - 80 . [ Medline ] 9 . Hogan TP , Awad AG , Eastwood R . A self - report scale predictive of drug compliance in schizophrenics : reliability and discriminative validity . Psychol Med . 1983 ; 13 ( 1 ) : 177 - 83 . [ Medline ] 10 . Droulout T , Liraud F , Verdoux H . [ Relationships between insight and medication adherence in subjects with psychosis ] . Encephale . 2003 ; 29 ( 5 ) : 430 - 7 . French . [ Medline ] 11 . Hummer M , Holzmeister R , Kemmler G , Eder U , Hofer A , Kurzthaler I , et al . Attitudes of patients with schizophrenia toward placebo - controlled clinical trials . J Clin Psychiatry . 2003 ; 64 ( 3 ) : 277 - 81 . [ Medline ] 12 . Rossi A , Arduini L , De Cataldo S , Stratta P . [ Subjective response to neuroleptic medication : a validation study of the Italian version of the Drug Attitude Inventory ( DAI ) ] . Epidemiol Psichiatr Soc . 2001 ; 10 ( 2 ) : 107 - 14 . Italian . [ Medline ] 13 . Garcia Cabeza I , Sanchez Diaz EI , Sanz Amador M , Gutierrez Rodriguez M , Gonzalez de Chavez M . [ Factors related to treatment adherence in schizophrenic patients ] . Actas Esp Psiquiatr . 1999 ; 27 ( 4 ) : 211 - 6 . Spanish . 14 . Cheng HL , Yu YW . [ Validation of the Chinese version of " the Drug Attitude Inventory " ] . Kaohsiung J Med Sci . 1997 ; 13 ( 6 ) : 370 - 7 . Chinese . 15 . Weiden P , Rapkin B , Mott T , Zygmunt A , Goldman D , Horvitz - Lennon M , et al . Rating of medication influences ( ROMI ) scale in schizophrenia . Schizophr Bull . 1994 ; 20 ( 2 ) : 297 - 310 . [ Medline ] 16 . Loffler W , Kilian R , Toumi M , Angermeyer MC . Schizophrenic patients ' subjective reasons for compliance and noncompliance with neuroleptic treatment . Pharmacopsychiatry . 2003 ; 36 ( 3 ) : 105 - 12 . 17 . Vauth R , Loschmann C , Rusch N , Corrigan PW . Understanding adherence to neuroleptic treatment in schizophreniai . Psychiatry Res . 2004 ; 126 ( 1 ) : 43 - 9 . [ Medline ] 18 . Rosa MA , Marcolin MA . Tradução e adaptação da Escala de Influências Medicamentosas ( ROMI ) : um instrumento para avaliar a aderência ao tratamento . J Bras Psiquiatr . 2000 ; 49 ( 10 - 12 ) : 405 - 12 . 19 . American Psychiatric Association . Diagnostic and statistical manual of mental disorders : DSM - IV . 4th ed . Washington DC : APA ; 1994 . 20 . Woerner MG , Mannuzza S , Kane JM . Anchoring the BPRS : an aid to improved reliability . Psychopharmacol Bull . 1988 ; 24 ( 1 ) : 112 - 7 . 21 . Elkis E , Alves TM , Eizenman IB . Reliability of the Brazilian version of the BPRS anchored [ abstract ] . Schizophr Res . 1999 ; 36 ( 1 - 3 ) : 7 - 8 . 22 . Thompson PA , Buckley PF , Meltzer HY . The brief psychiatric rating scale : effect of scaling system on clinical response assessment . J Clin Psychopharmacol . 1994 ; 14 ( 5 ) : 344 - 6 . [ Medline ] 23 . Rijcken CA , Monster TB , Brouwers JR , de Jong - van den Berg LT . Chlorpromazine equivalents versus defined daily doses : how to compare antipsychotic drug doses ? J Clin Psychopharmacol . 2003 ; 23 ( 6 ) : 657 - 9 . [ Medline ] 24 . Woods SW . Chlorpromazine equivalent doses for the newer atypical antipsychotics . J Clin Psychiatry . 2003 ; 64 ( 6 ) : 663 - 7 . Review . [ Medline ] 25 . Buchanan A . A two - year prospective study of treatment compliance in patients with schizophrenia . Psychol Med . 1992 ; 22 ( 3 ) : 787 - 97 . [ Medline ] 26 . Mazumdar S , Liu KS , Houck PR , Reynolds CF 3rd . Intent - to - treat analysis for longitudinal clinical trials : coping with the challenge of missing values . J Psychiatr Res . 1999 ; 33 ( 2 ) : 87 - 95 . [ Medline ] 27 . Haynes RB , Taylor DW , Sackett DL . Compliance in health care . Baltimore : Johns Hopkins University Press ; c1979 . p . 1 - 10 . 28 . Blackwell B . Treatment adherence . Br J Psychiatry . 1976 ; 129 : 513 - 31 . Review . [ Medline ] 29 . Haynes RB . A critical review of the " determinants " of patient compliance with therapeutic regimens . In : Sacket DL , Haynes RB , editors . Compliance with therapeutic regimens . Baltimore , MD : Johns Hopkins University Press ; 1976 . p . 26 - 39 . 30 . Lacro JP , Dunn LB , Dolder CR , Leckband SG , Jeste DV . Prevalence of and risk factors for medication nonadherence in patients with schizophrenia : a comprehensive review of recent literature . J Clin Psychiatry . 2002 ; 63 ( 10 ) : 892 - 909 . Review . [ Medline ] 31 . Weiss KA , Smith TE , Hull JW , Piper AC , Huppert JD . Predictors of risk of nonadherence in outpatients with schizophrenia and other psychotic disorders . Schizophr Bull . 2002 ; 28 ( 2 ) : 341 - 9 . [ Medline ] 32 . Hudson TJ , Owen RR , Thrush CR , Han X , Pyne JM , Thapa P , Sullivan G . A pilot study of barriers to medication adherence in schizophrenia . J Clin Psychiatry . 2004 ; 65 ( 2 ) : 211 - 6 . [ Medline ] 33 . Bartko G , Herczeg I , Zador G . Clinical symptomatology and drug compliance in schizophrenic patients . Acta Psychiatr Scand . 1988 ; 77 ( 1 ) : 74 - 6 . [ Medline ] 34 . David AS . Insight and psychosis . Br J Psychiatry . 1990 ; 156 : 798 - 808 . Review . [ Medline ] 35 . McEvoy JP , Apperson LJ , Appelbaum PS , Ortlip P , Brecosky J , Hammil K , et al . Insight in schizophrenia : Its relationships to acute psychopathology . J Nerv Ment Dis . 1989 ; 177 ( 1 ) : 43 - 7 . 36 . Marder SR , Mebane A , Chien CP , Winslade WJ , Swann E , Van Putten T . A comparison of patients who refuse and consent to neuroleptic treatment . Am J Psychiatry . 1983 ; 140 ( 4 ) : 470 - 2 . [ Medline ] 37 . Razali MS , Yahya H . Compliance with treatment in schizophrenia : a drug intervention program in a developing country . Acta Psychiatr Scand . 1995 ; 91 ( 5 ) : 331 - 5 . [ Medline ] 38 . Regier DA , Farmer ME , Rae DS , Locke BZ , Keith SJ , Judd LL , Goodwin FK . Comorbidity of mental disorders with alcohol and other drug abuse . Results from the Epidemiologic Catchment Area ( ECA ) Study . JAMA . 1990 ; 264 ( 19 ) : 2511 - 8 . [ Medline ] 39 . del Campo EJ , Carr CF , Correa E . Rehospitalized schizophrenics . What they report about illness , treatment and compliance . J Psychosoc Nurs Ment Health Serv . 1983 ; 21 ( 6 ) : 29 - 33 . [ Medline ] 40 . Sullivan G , Wells KB , Morgenstern H , Leake B . Identifying modifiable risk factors for rehospitalization : a case - control study of seriously mentally ill persons in Mississippi . Am J Psychiatry . 1995 ; 152 ( 12 ) : 1749 - 56 . [ Medline ] 41 . Bebbington PE . The content and context of compliance . Int Clin Psychopharmacol . 1995 ; 9 ( Suppl 5 ) : 41 - 50 . Review . 42 . Park LC , Lipman RS . A comparison of patient dosage deviation reports with pill counts . Psychopharmacologia . 1964 ; 6 ( 4 ) : 299 - 302 . Correspondence to Moacyr A Rosa Instituto de Psiquiatria do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo Rua Ovídio Pires de Campos , s / n 05403 - 010 São Paulo , SP , Brazil Phone / Fax : ( 5511 ) 3069 - 6971 E - mail : moarosa @ yahoo . com Financing : None Conflicts of interests : None Submitted : 21 December 2003 Accepted : 3 November 2004 Psychiatry Unit , Universidade de São Paulo ( USP ) , São Paulo ( SP ) , Brazil ; Department of Psychiatry and Medical Psychology , Santa Casa de Misericórdia de São Paulo ( SP ) , Brazil . Study carried out in order to obtain an academic degree ( MS in Medicine ) in 1998 . Presented as a poster at the 1999 APA Annual Meeting in Washington DC , USA . © 2006 Associação Brasileira de Psiquiatria ( ABP ) Rua Pedro de Toledo , 967 - casa 1 04039 - 032 São Paulo SP Brazil Tel . : + 55 11 5081 - 6799 Fax : + 55 11 5579 - 6210

Scheduling Tasks Very often , we have ` housekeeping ' tasks which have to be done at a certain time , or every so often . If the task is to be done by a process , we do it by putting it in the crontab file . If the task is to be done by a kernel module , we have two possibilities . The first is to put a process in the crontab file which will wake up the module by a system call when necessary , for example by opening a file . This is terribly inefficient , however -- we run a new process off of crontab , read a new executable to memory , and all this just to wake up a kernel module which is in memory anyway . Instead of doing that , we can create a function that will be called once for every timer interrupt . The way we do this is we create a task , held in a struct tq_struct , which will hold a pointer to the function . Then , we use queue_task to put that task on a task list called tq_timer , which is the list of tasks to be executed on the next timer interrupt . Because we want the function to keep on being executed , we need to put it back on tq_timer whenever it is called , for the next timer interrupt . There ' s one more point we need to remember here . When a module is removed by rmmod , first its reference count is checked . If it is zero , module_cleanup is called . Then , the module is removed from memory with all its functions . Nobody checks to see if the timer ' s task list happens to contain a pointer to one of those functions , which will no longer be available . Ages later ( from the computer ' s perspective , from a human perspective it ' s nothing , less than a hundredth of a second ) , the kernel has a timer interrupt and tries to call the function on the task list . Unfortunately , the function is no longer there . In most cases , the memory page where it sat is unused , and you get an ugly error message . But if some other code is now sitting at the same memory location , things could get very ugly . Unfortunately , we don ' t have an easy way to unregister a task from a task list . Since cleanup_module can ' t return with an error code ( it ' s a void function ) , the solution is to not let it return at all . Instead , it calls sleep_on or module_sleep_on 10 . 1 to put the rmmod process to sleep . Before that , it informs the function called on the timer interrupt to stop attaching itself by setting a global variable . Then , on the next timer interrupt , the rmmod process will be woken up , when our function is no longer in the queue and it ' s safe to remove the module . ex sched . c / * sched . c - scheduale a function to be called on * every timer interrupt . * / / * Copyright ( C ) 1998 by Ori Pomerantz * / / * The necessary header files * / / * Standard in kernel modules * / # include < linux / kernel . h > / * We ' re doing kernel work * / # include < linux / module . h > / * Specifically , a module * / / * Deal with CONFIG_MODVERSIONS * / # if CONFIG_MODVERSIONS == 1 # define MODVERSIONS # include < linux / modversions . h > # endif / * Necessary because we use the proc fs * / # include < linux / proc_fs . h > / * We scheduale tasks here * / # include < linux / tqueue . h > / * We also need the ability to put ourselves to sleep * and wake up later * / # include < linux / sched . h > / * In 2 . 2 . 3 / usr / include / linux / version . h includes a * macro for this , but 2 . 0 . 35 doesn ' t - so I add it * here if necessary . * / # ifndef KERNEL_VERSION # define KERNEL_VERSION ( a , b , c ) (( a ) * 65536 + ( b ) * 256 + ( c )) # endif / * The number of times the timer interrupt has been * called so far * / static int TimerIntrpt = 0 ; / * This is used by cleanup , to prevent the module from * being unloaded while intrpt_routine is still in * the task queue * / static struct wait_queue * WaitQ = NULL ; static void intrpt_routine ( void * ) ; / * The task queue structure for this task , from tqueue . h * / static struct tq_struct Task = { NULL , / * Next item in list - queue_task will do * this for us * / 0 , / * A flag meaning we haven ' t been inserted * into a task queue yet * / intrpt_routine , / * The function to run * / NULL / * The void * parameter for that function * / } ; / * This function will be called on every timer * interrupt . Notice the void * pointer - task functions * can be used for more than one purpose , each time * getting a different parameter . * / static void intrpt_routine ( void * irrelevant ) { / * Increment the counter * / TimerIntrpt ++ ; / * If cleanup wants us to die * / if ( WaitQ ! = NULL ) wake_up ( & WaitQ ) ; / * Now cleanup_module can return * / else / * Put ourselves back in the task queue * / queue_task ( & Task , & tq_timer ) ; } / * Put data into the proc fs file . * / int procfile_read ( char * buffer , char ** buffer_location , off_t offset , int buffer_length , int zero ) { int len ; / * The number of bytes actually used * / / * This is static so it will still be in memory * when we leave this function * / static char my_buffer [ 80 ] ; static int count = 1 ; / * We give all of our information in one go , so if * the anybody asks us if we have more information * the answer should always be no . * / if ( offset > 0 ) return 0 ; / * Fill the buffer and get its length * / len = sprintf ( my_buffer , " Timer was called % d times so far \ n " , TimerIntrpt ) ; count ++ ; / * Tell the function which called us where the * buffer is * / * buffer_location = my_buffer ; / * Return the length * / return len ; } struct proc_dir_entry Our_Proc_File = { 0 , / * Inode number - ignore , it will be filled by * proc_register_dynamic * / 5 , / * Length of the file name * / " sched " , / * The file name * / S_IFREG | S_IRUGO , / * File mode - this is a regular file which can * be read by its owner , its group , and everybody * else * / 1 , / * Number of links ( directories where * the file is referenced ) * / 0 , 0 , / * The uid and gid for the file - we give * it to root * / 80 , / * The size of the file reported by ls . * / NULL , / * functions which can be done on the * inode ( linking , removing , etc . ) - we don ' t * support any . * / procfile_read , / * The read function for this file , the function called * when somebody tries to read something from it . * / NULL / * We could have here a function to fill the * file ' s inode , to enable us to play with * permissions , ownership , etc . * / } ; / * Initialize the module - register the proc file * / int init_module ( ) { / * Put the task in the tq_timer task queue , so it * will be executed at next timer interrupt * / queue_task ( & Task , & tq_timer ) ; / * Success if proc_register_dynamic is a success , * failure otherwise * / # if LINUX_VERSION_CODE > KERNEL_VERSION ( 2 , 2 , 0 ) return proc_register ( & proc_root , & Our_Proc_File ) ; # else return proc_register_dynamic ( & proc_root , & Our_Proc_File ) ; # endif } / * Cleanup * / void cleanup_module ( ) { / * Unregister our / proc file * / proc_unregister ( & proc_root , Our_Proc_File . low_ino ) ; / * Sleep until intrpt_routine is called one last * time . This is necessary , because otherwise we ' ll * deallocate the memory holding intrpt_routine and * Task while tq_timer still references them . * Notice that here we don ' t allow signals to * interrupt us . * * Since WaitQ is now not NULL , this automatically * tells the interrupt routine it ' s time to die . * / sleep_on ( & WaitQ ) ; }

There are a few routine maintenance chores that must be performed on a regular basis to keep a PostgreSQL server running smoothly . The tasks discussed here are repetitive in nature and can easily be automated using standard Unix tools such as cron scripts . But it is the database administrator ' s responsibility to set up appropriate scripts , and to check that they execute successfully . One obvious maintenance task is creation of backup copies of the data on a regular schedule . Without a recent backup , you have no chance of recovery after a catastrophe ( disk failure , fire , mistakenly dropping a critical table , etc . ) . The backup and recovery mechanisms available in PostgreSQL are discussed at length in Chapter 23 . The other main category of maintenance task is periodic " vacuuming " of the database . This activity is discussed in Section 22 . 1 . Something else that might need periodic attention is log file management . This is discussed in Section 22 . 3 . PostgreSQL is low - maintenance compared to some other database management systems . Nonetheless , appropriate attention to these tasks will go far towards ensuring a pleasant and productive experience with the system . 22 . 1 . Routine Vacuuming PostgreSQL ' s VACUUM command must be run on a regular basis for several reasons : To recover disk space occupied by updated or deleted rows . To update data statistics used by the PostgreSQL query planner . To protect against loss of very old data due to transaction ID wraparound . The frequency and scope of the VACUUM operations performed for each of these reasons will vary depending on the needs of each site . Therefore , database administrators must understand these issues and develop an appropriate maintenance strategy . This section concentrates on explaining the high - level issues ; for details about command syntax and so on , see the VACUUM reference page . Beginning in PostgreSQL 7 . 2 , the standard form of VACUUM can run in parallel with normal database operations ( selects , inserts , updates , deletes , but not changes to table definitions ) . Routine vacuuming is therefore not nearly as intrusive as it was in prior releases , and it is not as critical to try to schedule it at low - usage times of day . Beginning in PostgreSQL 8 . 0 , there are configuration parameters that can be adjusted to further reduce the performance impact of background vacuuming . See Section 17 . 4 . 4 . An automated mechanism for performing the necessary VACUUM operations has been added in PostgreSQL 8 . 1 . See Section 22 . 1 . 4 . 22 . 1 . 1 . Recovering disk space In normal PostgreSQL operation , an UPDATE or DELETE of a row does not immediately remove the old version of the row . This approach is necessary to gain the benefits of multiversion concurrency control ( see Chapter 12 ) : the row version must not be deleted while it is still potentially visible to other transactions . But eventually , an outdated or deleted row version is no longer of interest to any transaction . The space it occupies must be reclaimed for reuse by new rows , to avoid infinite growth of disk space requirements . This is done by running VACUUM . Clearly , a table that receives frequent updates or deletes will need to be vacuumed more often than tables that are seldom updated . It may be useful to set up periodic cron tasks that VACUUM only selected tables , skipping tables that are known not to change often . This is only likely to be helpful if you have both large heavily - updated tables and large seldom - updated tables — the extra cost of vacuuming a small table isn ' t enough to be worth worrying about . There are two variants of the VACUUM command . The first form , known as " lazy vacuum " or just VACUUM , marks expired data in tables and indexes for future reuse ; it does not attempt to reclaim the space used by this expired data unless the space is at the end of the table and an exclusive table lock can be easily obtained . Unused space at the start or middle of the file does not result in the file being shortened and space returned to the operating system . This variant of VACUUM can be run concurrently with normal database operations . The second form is the VACUUM FULL command . This uses a more aggressive algorithm for reclaiming the space consumed by expired row versions . Any space that is freed by VACUUM FULL is immediately returned to the operating system . Unfortunately , this variant of the VACUUM command acquires an exclusive lock on each table while VACUUM FULL is processing it . Therefore , frequently using VACUUM FULL can have an extremely negative effect on the performance of concurrent database queries . The standard form of VACUUM is best used with the goal of maintaining a fairly level steady - state usage of disk space . If you need to return disk space to the operating system you can use VACUUM FULL — but what ' s the point of releasing disk space that will only have to be allocated again soon ? Moderately frequent standard VACUUM runs are a better approach than infrequent VACUUM FULL runs for maintaining heavily - updated tables . Recommended practice for most sites is to schedule a database - wide VACUUM once a day at a low - usage time of day , supplemented by more frequent vacuuming of heavily - updated tables if necessary . ( Some installations with an extremely high rate of data modification VACUUM busy tables as often as once every few minutes . ) If you have multiple databases in a cluster , don ' t forget to VACUUM each one ; the program vacuumdb may be helpful . VACUUM FULL is recommended for cases where you know you have deleted the majority of rows in a table , so that the steady - state size of the table can be shrunk substantially with VACUUM FULL ' s more aggressive approach . Use plain VACUUM , not VACUUM FULL , for routine vacuuming for space recovery . If you have a table whose contents are deleted on a periodic basis , consider doing it with TRUNCATE rather than using DELETE followed by VACUUM . TRUNCATE removes the entire content of the table immediately , without requiring a subsequent VACUUM or VACUUM FULL to reclaim the now - unused disk space . 22 . 1 . 2 . Updating planner statistics The PostgreSQL query planner relies on statistical information about the contents of tables in order to generate good plans for queries . These statistics are gathered by the ANALYZE command , which can be invoked by itself or as an optional step in VACUUM . It is important to have reasonably accurate statistics , otherwise poor choices of plans may degrade database performance . As with vacuuming for space recovery , frequent updates of statistics are more useful for heavily - updated tables than for seldom - updated ones . But even for a heavily - updated table , there may be no need for statistics updates if the statistical distribution of the data is not changing much . A simple rule of thumb is to think about how much the minimum and maximum values of the columns in the table change . For example , a timestamp column that contains the time of row update will have a constantly - increasing maximum value as rows are added and updated ; such a column will probably need more frequent statistics updates than , say , a column containing URLs for pages accessed on a website . The URL column may receive changes just as often , but the statistical distribution of its values probably changes relatively slowly . It is possible to run ANALYZE on specific tables and even just specific columns of a table , so the flexibility exists to update some statistics more frequently than others if your application requires it . In practice , however , the usefulness of this feature is doubtful . Beginning in PostgreSQL 7 . 2 , ANALYZE is a fairly fast operation even on large tables , because it uses a statistical random sampling of the rows of a table rather than reading every single row . So it ' s probably much simpler to just run it over the whole database every so often . Tip : Although per - column tweaking of ANALYZE frequency may not be very productive , you may well find it worthwhile to do per - column adjustment of the level of detail of the statistics collected by ANALYZE . Columns that are heavily used in WHERE clauses and have highly irregular data distributions may require a finer - grain data histogram than other columns . See ALTER TABLE SET STATISTICS . Recommended practice for most sites is to schedule a database - wide ANALYZE once a day at a low - usage time of day ; this can usefully be combined with a nightly VACUUM . However , sites with relatively slowly changing table statistics may find that this is overkill , and that less - frequent ANALYZE runs are sufficient . 22 . 1 . 3 . Preventing transaction ID wraparound failures PostgreSQL ' s MVCC transaction semantics depend on being able to compare transaction ID ( XID ) numbers : a row version with an insertion XID greater than the current transaction ' s XID is " in the future " and should not be visible to the current transaction . But since transaction IDs have limited size ( 32 bits at this writing ) a cluster that runs for a long time ( more than 4 billion transactions ) would suffer transaction ID wraparound : the XID counter wraps around to zero , and all of a sudden transactions that were in the past appear to be in the future — which means their outputs become invisible . In short , catastrophic data loss . ( Actually the data is still there , but that ' s cold comfort if you can ' t get at it . ) Prior to PostgreSQL 7 . 2 , the only defense against XID wraparound was to re - initdb at least every 4 billion transactions . This of course was not very satisfactory for high - traffic sites , so a better solution has been devised . The new approach allows a server to remain up indefinitely , without initdb or any sort of restart . The price is this maintenance requirement : every table in the database must be vacuumed at least once every billion transactions . In practice this isn ' t an onerous requirement , but since the consequences of failing to meet it can be complete data loss ( not just wasted disk space or slow performance ) , some special provisions have been made to help database administrators avoid disaster . For each database in the cluster , PostgreSQL keeps track of the time of the last database - wide VACUUM . When any database approaches the billion - transaction danger level , the system begins to emit warning messages . If nothing is done , it will eventually shut down normal operations until appropriate manual maintenance is done . The remainder of this section gives the details . The new approach to XID comparison distinguishes two special XIDs , numbers 1 and 2 ( BootstrapXID and FrozenXID ) . These two XIDs are always considered older than every normal XID . Normal XIDs ( those greater than 2 ) are compared using modulo - 2 31 arithmetic . This means that for every normal XID , there are two billion XIDs that are " older " and two billion that are " newer " ; another way to say it is that the normal XID space is circular with no endpoint . Therefore , once a row version has been created with a particular normal XID , the row version will appear to be " in the past " for the next two billion transactions , no matter which normal XID we are talking about . If the row version still exists after more than two billion transactions , it will suddenly appear to be in the future . To prevent data loss , old row versions must be reassigned the XID FrozenXID sometime before they reach the two - billion - transactions - old mark . Once they are assigned this special XID , they will appear to be " in the past " to all normal transactions regardless of wraparound issues , and so such row versions will be good until deleted , no matter how long that is . This reassignment of XID is handled by VACUUM . VACUUM ' s normal policy is to reassign FrozenXID to any row version with a normal XID more than one billion transactions in the past . This policy preserves the original insertion XID until it is not likely to be of interest anymore . ( In fact , most row versions will probably live and die without ever being " frozen " . ) With this policy , the maximum safe interval between VACUUM runs on any table is exactly one billion transactions : if you wait longer , it ' s possible that a row version that was not quite old enough to be reassigned last time is now more than two billion transactions old and has wrapped around into the future — i . e . , is lost to you . ( Of course , it ' ll reappear after another two billion transactions , but that ' s no help . ) Since periodic VACUUM runs are needed anyway for the reasons described earlier , it ' s unlikely that any table would not be vacuumed for as long as a billion transactions . But to help administrators ensure this constraint is met , VACUUM stores transaction ID statistics in the system table pg_database . In particular , the datfrozenxid column of a database ' s pg_database row is updated at the completion of any database - wide VACUUM operation ( i . e . , VACUUM that does not name a specific table ) . The value stored in this field is the freeze cutoff XID that was used by that VACUUM command . All normal XIDs older than this cutoff XID are guaranteed to have been replaced by FrozenXID within that database . A convenient way to examine this information is to execute the query SELECT datname , age ( datfrozenxid ) FROM pg_database ; The age column measures the number of transactions from the cutoff XID to the current transaction ' s XID . With the standard freezing policy , the age column will start at one billion for a freshly - vacuumed database . When the age approaches two billion , the database must be vacuumed again to avoid risk of wraparound failures . Recommended practice is to VACUUM each database at least once every half - a - billion ( 500 million ) transactions , so as to provide plenty of safety margin . To help meet this rule , each database - wide VACUUM automatically delivers a warning if there are any pg_database entries showing an age of more than 1 . 5 billion transactions , for example : play = # VACUUM ; WARNING : database " mydb " must be vacuumed within 177009986 transactions HINT : To avoid a database shutdown , execute a full - database VACUUM in " mydb " . VACUUM If the warnings emitted by VACUUM go ignored , then PostgreSQL will begin to emit a warning like the above on every transaction start once there are fewer than 10 million transactions left until wraparound . If those warnings also are ignored , the system will shut down and refuse to execute any new transactions once there are fewer than 1 million transactions left until wraparound : play = # select 2 + 2 ; ERROR : database is shut down to avoid wraparound data loss in database " mydb " HINT : Stop the postmaster and use a standalone backend to VACUUM in " mydb " . The 1 - million - transaction safety margin exists to let the administrator recover without data loss , by manually executing the required VACUUM commands . However , since the system will not execute commands once it has gone into the safety shutdown mode , the only way to do this is to stop the postmaster and use a standalone backend to execute VACUUM . The shutdown mode is not enforced by a standalone backend . See the postgres reference page for details about using a standalone backend . VACUUM with the FREEZE option uses a more aggressive freezing policy : row versions are frozen if they are old enough to be considered good by all open transactions . In particular , if a VACUUM FREEZE is performed in an otherwise - idle database , it is guaranteed that all row versions in that database will be frozen . Hence , as long as the database is not modified in any way , it will not need subsequent vacuuming to avoid transaction ID wraparound problems . This technique is used by initdb to prepare the template0 database . It should also be used to prepare any user - created databases that are to be marked datallowconn = false in pg_database , since there isn ' t any convenient way to VACUUM a database that you can ' t connect to . Warning A database that is marked datallowconn = false in pg_database is assumed to be properly frozen ; the automatic warnings and wraparound protection shutdown do not take such databases into account . Therefore it ' s up to you to ensure you ' ve correctly frozen a database before you mark it with datallowconn = false . 22 . 1 . 4 . The auto - vacuum daemon Beginning in PostgreSQL 8 . 1 , there is a separate optional server process called the autovacuum daemon , whose purpose is to automate the execution of VACUUM and ANALYZE commands . When enabled , the autovacuum daemon runs periodically and checks for tables that have had a large number of inserted , updated or deleted tuples . These checks use the row - level statistics collection facility ; therefore , the autovacuum daemon cannot be used unless stats_start_collector and stats_row_level are set to true . Also , it ' s important to allow a slot for the autovacuum process when choosing the value of superuser_reserved_connections . The autovacuum daemon , when enabled , runs every autovacuum_naptime seconds and determines which database to process . Any database which is close to transaction ID wraparound is immediately processed . In this case , autovacuum issues a database - wide VACUUM call , or VACUUM FREEZE if it ' s a template database , and then terminates . If no database fulfills this criterion , the one that was least recently processed by autovacuum is chosen . In this case each table in the selected database is checked , and individual VACUUM or ANALYZE commands are issued as needed . For each table , two conditions are used to determine which operation ( s ) to apply . If the number of obsolete tuples since the last VACUUM exceeds the " vacuum threshold " , the table is vacuumed . The vacuum threshold is defined as : vacuum threshold = vacuum base threshold + vacuum scale factor * number of tuples where the vacuum base threshold is autovacuum_vacuum_threshold , the vacuum scale factor is autovacuum_vacuum_scale_factor , and the number of tuples is pg_class . reltuples . The number of obsolete tuples is obtained from the statistics collector ; it is a semi - accurate count updated by each UPDATE and DELETE operation . ( It is only semi - accurate because some information may be lost under heavy load . ) For analyze , a similar condition is used : the threshold , defined as analyze threshold = analyze base threshold + analyze scale factor * number of tuples is compared to the total number of tuples inserted , updated , or deleted since the last ANALYZE . The default thresholds and scale factors are taken from postgresql . conf , but it is possible to override them on a table - by - table basis by making entries in the system catalog pg_autovacuum . If a pg_autovacuum row exists for a particular table , the settings it specifies are applied ; otherwise the global settings are used . See Section 17 . 9 for more details on the global settings . Besides the base threshold values and scale factors , there are three more parameters that can be set for each table in pg_autovacuum . The first , pg_autovacuum . enabled , can be set to false to instruct the autovacuum daemon to skip that particular table entirely . In this case autovacuum will only touch the table when it vacuums the entire database to prevent transaction ID wraparound . The other two parameters , the vacuum cost delay ( pg_autovacuum . vac_cost_delay ) and the vacuum cost limit ( pg_autovacuum . vac_cost_limit ) , are used to set table - specific values for the Cost - Based Vacuum Delay feature . If any of the values in pg_autovacuum are set to a negative number , or if a row is not present at all in pg_autovacuum for any particular table , the corresponding values from postgresql . conf are used . There is not currently any support for making pg_autovacuum entries , except by doing manual INSERT s into the catalog . This feature will be improved in future releases , and it is likely that the catalog definition will change . Caution The contents of the pg_autovacuum system catalog are currently not saved in database dumps created by the tools pg_dump and pg_dumpall . If you want to preserve them across a dump / reload cycle , make sure you dump the catalog manually .

Young Adult Outcome of Hyperactive Children : Adaptive Functioning in Major Life Activities Barkley , Russell A Ph . D . ; Fischer , Mariellen Ph . D . ; Smallish , Lori M . A . ; Fletcher , Kenneth Ph . D . Journal of the American Academy of Child & Adolescent Psychiatry . 45 ( 2 ) : 192 - 202 , February 2006 . Abstract : Objective : The authors report the adaptive functioning of hyperactive and control children in southeastern Wisconsin ( Milwaukee ) followed to young adulthood . Method : Interviews with participants concerning major life activities were collected between 1992 and 1996 and used along with employer ratings and high school records at the young adult follow - up ( mean = 20 years , range 19 - 25 ) for this large sample of hyperactive ( H ; n = 149 ) and community control ( CC ; n = 72 ) children initially seen in 1978 - 1980 and studied for at least 13 years . Age , duration of follow - up , and IQ were statistically controlled as needed . Results : The H group had significantly lower educational performance and attainment , with 32 % failing to complete high school . H group members had been fired from more jobs and manifested greater employer - rated attention - deficit / hyperactivity disorder and oppositional defiant disorder symptoms and lower job performance than the CC group . Socially , the H group had fewer close friends , more trouble keeping friends , and more social problems as rated by parents . Far more H than CC group members had become parents ( 38 % versus 4 % ) and had been treated for sexually transmitted disease ( 16 % versus 4 % ) . Severity of lifetime conduct disorder was predictive of several of the most salient outcomes ( failure to graduate , earlier sexual intercourse , early parenthood ) whereas attention - deficit / hyperactivity disorder and oppositional defiant disorder at work were predictive of job performance and risk of being fired . Conclusions : These findings corroborate prior research and go further in identifying sexual activity and early parenthood as additional problematic domains of adaptive functioning at adulthood . Worse Quality of Life for Children With Newly Diagnosed Attention - Deficit / Hyperactivity Disorder , Compared With Asthmatic and Healthy Children Rodrigo Escobar , Cesar A . Soutullo , Amaia Hervas , Xavier Gastaminza , Pepa Polavieja , and Inmaculada Gilaberte PEDIATRICS Vol . 116 No . 3 September 2005 , pp . e364 - e369 Objective . To evaluate the quality of life ( QOL ) of untreated children with newly diagnosed attention - deficit / hyperactivity disorder ( ADHD ) , compared with asthmatic and healthy children . Methods . This prospective , case - control study included a group of 120 children , 6 to 12 years of age , with newly diagnosed ADHD according to the Diagnostic and Statistical Manual of Mental Disorders , Fourth Edition . Subjects were matched according to age , gender , and health care area with 2 control groups , ie , 93 asthmatic children and 120 healthy children . Sociodemographic characteristics and Child Health Questionnaire scores were collected . Results . The QOL of children with ADHD was rated worse than that of asthmatic or healthy children for most Child Health Questionnaire domains . The greatest differences were found in behavior , social limitations attributable to physical problems , emotional impact on parents , and family activities . Almost every psychosocial domain was more affected in comparison with asthmatic children and both psychosocial and physical domains in comparison with healthy children . Conclusions . ADHD interferes with the daily lives of children , parents , and families even more than asthma , primarily in areas related to psychosocial functioning , although evidence of impaired physical functioning also emerged . Delays in recognition , assessment , and management of ADHD may affect negatively the QOL of those children . What is the prevalence of adult ADHD ? Results of a population screen of 966 adults Faraone SV , Biederman J . State University of New York Upstate Medical University . faraones @ upstate . edu . J Atten Disord . 2005 Nov ; 9 ( 2 ) : 384 - 91 . To provide a better estimate of the prevalence of ADHD in adulthood , the authors complete a telephone survey of 966 randomly selected adults . They compute two diagnoses from the survey data . Participants meeting Diagnostic and Statistical Manual of Mental Disorders ( 4th ed . ) criteria for both childhood and adulthood are defined as narrow ADHD . Broad ADHD adds to that definition those meeting subthreshold criteria . Cronbach ' s alpha is . 90 for the 18 DSM - IV symptoms in childhood and . 88 when rated for current symptoms in adulthood . No one item unduly influences the reliability of the total score . The authors find similar results in separate analysesof hyperactive - impulsive and inattentive symptoms . They estimate prevalences of 2 . 9 % for Narrow ADHD and 16 . 4 % for Broad ADHD . Having ADHD is associated with lower levels of education and employment status . These findings suggest that adult ADHD is a common disorder associated with impaired functioning . Tourette syndrome and other tic disorders in a total population of children : Clinical assessment and background . Khalifa N , von Knorring AL . Department of Neuroscience , Child and Adolescent Psychiatry , University Hospital , Uppsala , Sweden . Acta Paediatr . 2005 Nov ; 94 ( 11 ) : 1608 - 14 . Aim : To describe the symptoms , onset , heredity , pre - / perinatal events and socio - economic status in Tourette syndrome ( TS ) and other tic disorders . Methods : From a total population of 4479 children , 25 ( 0 . 6 % ) with TS , 58 ( 1 . 3 % ) with chronic motor / vocal tics ( CMVT ) and 214 ( 4 . 8 % ) with transient tics ( TT ) in the last year were found . A three - stage procedure was used : tic screening , telephone interview and clinical assessment . The TS group was compared with 25 children with TT and 25 controls without tics . Results : The mean age of the first symptoms of TS was significantly lower than the onset of CMVT . All except one with TS had contact with medical services . The tics of children with TS were significantly more severe than the tics of others . Younger age of onset of TS indicated more severe tics . Parents and siblings of children with TS had an increased prevalence of tic disorders , obsessive - compulsive behaviour ( OCD ) , attention - deficit / hyperactivity disorder ( ADHD ) and depression . Eighty per cent had a first - degree relative with a psychiatric disorder . A non - significant increase with regards to reduced optimality score in the pre - , peri - or neonatal periods was found in children with TS compared to controls . No differences were found concerning socio - economic status . Conclusion : Almost all children from a total population with TS have sought help from medical services . An increased prevalence of tics , OCD , depression or ADHD was found in the parents / siblings of children with TS , which draws attention to the importance of thorough investigation of family members . Time perception : modality and duration effects in attention - deficit / hyperactivity disorder ( ADHD ) Toplak ME , Tannock R . Brain and Behaviour Research Program , Research Institute of The Hospital for Sick Children , Ontario , Canada . J Abnorm Child Psychol . 2005 Oct ; 33 ( 5 ) : 639 - 54 . Time perception performance was systematically investigated in adolescents with and without attention - deficit / hyperactivity disorder ( ADHD ) . Specifically , the effects of manipulating modality ( auditory and visual ) and length of duration ( 200 and 1000 ms ) were examined . Forty - six adolescents with ADHD and 44 controls were administered four duration discrimination tasks and two control tasks , and a set of standardized measures . Participants with ADHD had higher thresholds than controls on all of the duration discrimination tasks , with the largest effect size obtained on the visual 1000 ms duration discrimination task . No group differences were observed on the control tasks . Visual - spatial memory was found to be a significant predictor of visual and auditory duration discrimination at longer intervals ( 1000 ms ) in the ADHD sample , whereas auditory verbal working memory predicted auditory discrimination at longer intervals ( 1000 ms ) in the control sample . These group differences suggest impairments in basic timing mechanisms in ADHD . Outros textos : • Atualização de outubro de 2006 • Atualização de setembro de 2006 - Parte 2 • Atualização de setembro de 2006 • Atualização de agosto de 2006 - Parte 1 • Atualização de julho de 2006 • Atualização de maio de 2006 • Atualização de novembro de 2005 • Atualização de outubro de 2005

Laparoscopic nephrectomy : assessment of morcellation versus intact specimen extraction on postoperative status Hernandez F , Rha KH , Pinto PA , Kim FJ , Klicos N , Chan TY , Kavoussi LR , Jarrett TW From the Departments of Urology and Pathology , The Johns Hopkins Medical Institutions , Baltimore , Maryland , USA J Urol . 2003 ; 170 : 412 - 5 PURPOSE : We compared pathological evaluation and postoperative recovery in patients undergoing transperitoneal laparoscopic nephrectomy at our institution with morcellated vs intact specimen extraction . MATERIALS AND METHODS : A prospective evaluation of 57 consecutive patients undergoing radical and simple transperitoneal laparoscopic nephrectomy was reviewed . One patient was excluded from study due to transitional cell carcinoma , which was detected intraoperatively . The 33 morcellated specimens were extracted at the umbilical port and the 23 intact specimens were extracted through a midline infraumbilical incision . Data were obtained on narcotic requirements , hospital stay , complications , estimated blood loss , mass size based on preoperative imaging , specimen weight and extraction incision length . RESULTS : Mean incision length in the morcellated and intact specimen removal groups was 1 . 2 and 7 . 1 cm , respectively ( p < 0 . 001 ) . No significant differences in pain or recovery were noted between the 2 groups . Two cases of microscopic invasion of the perinephric adipose tissue in the intact specimen group were up staged from clinical T1 to pT3a disease . No change in patient treatment was made based on this information . CONCLUSIONS : We did not find a significant difference in surgical time , pain or hospital stay . Only incision length was statistically significant . Postoperative recovery appeared to be similar in these 2 groups . With modern imaging modalities information on pathological stage did not alter patient treatment . Editorial Comment Although prospective , this study was non - randomized . The authors report that " the decision to morcellate or perform intact extraction was based solely on patient preference " . There were some differences between the groups , including patients that were older ( mean age of 54 . 6 vs . 61 . 5 years , p = 0 . 03 ) and larger ( BMI of 31 . 7 vs . 27 . 9 ) in the morcellated group . The mean operative time was only 11 minutes longer in the morcellated group . Unfortunately , the authors did not report the operative time for extraction separately . It would have been informative to compare the operative time after complete dissection of the kidney , to determine if the longer extraction time in the morcellated group was outweighed by the longer time to close the incision in the intact extraction group . Entrapping a specimen in the Cook LapSac is a challenging task , which the authors appropriately bemoan in their discussion section , and I would think that in most surgeon ' s hands it would take longer to entrap and morcellate a specimen than to close the 7 . 1 cm average incision for intact extraction . That the authors of this study managed to perform morecellation in only 11 minutes longer than they took to perform intact extraction , especially given the greater BMI in the morcellated group , is a testament to their skill . The major finding of this study is the lack of benefit in terms of patient convalescence in the morcellation group , despite the smaller incision . This leaves cosmetics as being the only advantage of morcellation . There are a number of potential advantages to intact extraction . With intact extraction , pathological staging is possible . There is a growing body of evidence , however , that there is little prognostic difference between clinical T1 renal cancers that are confirmed as pT1 and those that are upstaged to pT3a . In addition , there is concern that morcellation might increase the risk of port implantation . Fortunately , there have been only 3 reported cases of port site implantation of renal cell carcinoma , and 2 of them occurred after inappropriate blind morcellation in a plastic bag . My conclusion is that port site implantation is not a significant concern with renal cell carcinoma and that there is minimal benefit to the pathological staging provided by intact extraction . Given this , and the findings of this study , the only difference between intact extraction and morcellation is improved cosmetics in the last . As such , I prefer morcellation unless the specimen is very large ( > 750 grams ) , in which cases I use hand - assistance ( and therefore intact extraction ) to simplify dissection and entrapment . Dr . J . Stuart Wolf Jr . Associate Professor of Urology University of Michigan Ann Arbor , Michigan , USA Prospective randomized comparative study of the effectiveness and safety of electrohydraulic and electromagnetic extracorporeal shock wave lithotriptors Sheir KZ , Madbouly K , Elsobky E From the Urology and Nephrology Center , Mansoura University , Mansoura , Egypt J Urol . 2003 ; 170 : 389 - 92 PURPOSE : We compared the efficacy of 2 shock wave energy sources , electrohydraulic ( Dornier MFL 5000 , Dornier MedTech , Wessling , Germany ) and electromagnetic ( DLS , Dornier Lithotriptor S , Dornier MedTech ) , for the treatment of urinary calculi . MATERIALS AND METHODS : A prospective randomized study of 694 patients with urinary stones was conducted during 12 months to compare the efficacy of the 2 machines . Entrance criteria were radiopaque single or multiple stones at any location within the kidney or the ureter , 25 mm or smaller that had not previously been treated by any means . Patients with congenital anomalies were excluded from this study with all other contraindications for extracorporeal shock wave lithotripsy . Following lithotripsy a plain abdominal film and tomograms were done 1 week after each session to determine if there were residual stones and assess the need for re - treatment . Patients were evaluated 4 weeks after lithotripsy by plane abdominal x - ray and spiral computerized tomography . Success was defined as no residual stones . Univariate and multivariate statistical analyses were performed for different variables that may have an impact on the success rate , including the type of lithotriptor . Comparisons of treatment parameters , complications and success rate for both lithotriptors were done . RESULTS : Of 9 variables examined with univariate analysis 6 had a significant impact on the success rate . Of these 4 maintained their statistical impact on multivariate analysis . These were side , site of the stones , renal morphology and type of lithotriptor . Treatment time was significantly shortened for DLS ( 54 ± 32 . 9 minutes compared to 65 . 7 ± 44 . 7 for MFL , p < 0 . 001 ) . The re - treatment rate was lower for DLS at 34 % versus 51 . 6 % for the MFL ( p < 0 . 001 ) . The overall success rate was 85 . 4 % . It was 88 . 5 % for DLS compared to 82 . 4 % for MFL ( p = 0 . 03 ) . No statistically significant difference between the lithotriptors was noted for ureteral calculi ( p > 0 . 05 ) . The success rate was higher in the DLS group for renal stones especially lower caliceal and pyelic stones ( p < 0 . 05 ) . The success rate was higher in DLS group for stones 10 mm or smaller , 92 . 8 % versus 85 . 3 % for MFL ( p = 0 . 03 ) . The success rate was comparable in both groups for stones larger than 10 mm ( 81 . 8 % for DLS versus 77 . 9 % for MFL , p > 0 . 05 ) . No statistically significant difference was found in the complication rate for the groups . Steinstrasse were noted in 4 % of patients treated with MFL and 3 % of those treated with DLS . Subcapsular hematomas were noted in 2 patients in each group . No procedures after extracorporeal shock wave lithotripsy were needed in either group . CONCLUSIONS : The electromagnetic lithotriptor ( Dornier lithotriptor S ) has significant clinical advantages over the electrohydraulic lithotriptor ( Dornier MFL 5000 ) in terms of treatment time , re - treatment rate and success rate , although there is no difference in the complication rate . Editorial Comment As nice as it would be to conclude that this study provides definitive evidence with regards to one energy source over another , as the authors would like us to believe as suggested by their stress on the energy source rather than the particular lithotriptor throughout the text , it does not do that . Other differences between the lithotriptors make this conclusion invalid . The focal zone is 224 mm 2 in the MFL and 175 mm 2 in the DLS . The number of shock wave delivered was not provided . One might conclude reasonably , however , that indeed the DLS is a better machine than the MFL - primarily owing to the lower retreatment rate . Since the MFL is no longer in production , this information is not all that useful . One finding in the study that is very useful , however , is the minimal ( 0 . 6 % ) rate of hematoma formation overall , despite the use of sensitive CT scans for surveillance . Other studies have suggested that hematoma formation might be more frequent with either machine , and given the sensitive radiographic assessment in this study I find this reassuring . Dr . J . Stuart Wolf Jr . Associate Professor of Urology University of Michigan Ann Arbor , Michigan , USA © 2006 Sociedade Brasileira de Urologia Rua Bambina , 153 22251 - 050 Rio de Janeiro RJ Brazil Tel . + 55 21 2539 - 6787 Fax : + 55 21 2246 - 4088

Saccadic movements using eye - tracking technology in individuals with autism spectrum disorders : pilot study Movimentos sacádicos de indivíduos do espectro autista por varredura visual : estudo piloto Marcos T . Mercadante ; Elizeu C . Macedo ; Patrícia M . Baptista ; Cristiane S . Paula ; José S . Schwartzman Pervasive Developmental Disorder Program , Mackenzie Presbyterian University , São Paulo SP , Brazil ABSTRACT OBJECTIVE : To verify differences in the visual scanning strategies between pervasive developmental disorders ( PDD ) and controls when they are observing social and non - social pictures . METHOD : PDD group ( PDDG ) comprised by 10 non - retarded subjects ( age from 4 to 41 ) and age - matched control group ( CG ) . Nine social pictures with human beings ( including two pictures of cat mask ) , and 3 nonsocial pictures of objects were presented for 5 seconds . Saccadic movements and fixation were recorded with equipment EyeGaze ® ( LC Technologies Inc . ) . RESULTS : PDDG ( mean = 292 . 73 , SE = 67 . 62 ) presented longer duration of saccadic movements for social pictures compared to CG ( mean = 136 . 06 , SE = 14 . 01 ) ( p = 0 . 04 ) . The CG showed a higher number of fixations in the picture 7 ( a women using a cat mask , with the eyes erased ) ( CG : mean = 3 . 40 ; PDDG : mean = 1 . 80 ; p = 0 . 007 ) . CONCLUSION : The results suggest differences in strategies that PDD explore human picture . Moreover , these strategies seem not to be affected by the lack of expected part of the face ( the eyes ) . Key words : autism , Aspergers syndrome , pervasive development disorder , eye movement . RESUMO OBJETIVO : Verificar diferenças nas estratégias de varredura visual de indivíduos com transtorno invasivo do desenvolvimento ( TID ) comparados a controles normais na observação de figuras sociais e não sociais . MÉTODO : Estudo caso - controle . Grupo TID : dez sujeitos com TID , inteligência normal e idade entre 4 e 41 anos ; Grupo Controle : dez sujeitos pareados por idade . Os sujeitos observaram por 5 segundos 9 figuras de seres humanos e 3 figuras de objetos . Os movimentos sacádicos e o número de fixações foram gravados em equipamento EyeGaze ® ( LC Technologies Inc . ) . RESULTADOS : O grupo TID apresentou maior duração dos movimentos sacádicos na observação de figuras humanas [ TID = 292 , 73 ( EP = 67 , 62 ) ; controle = 136 , 06 ( EP = 14 , 01 ) ; p = 0 , 04 ] . O grupo controle apresentou maior número de fixações na figura 7 ( mulher com máscara de gato sem os olhos ) ( TID = 1 , 8 ; controle = 3 , 4 ; p = 0 , 007 ) . CONCLUSÃO : Indivíduos com TID parecem utilizar estratégias diferentes para explorar figura humana . Além disso , o padrão de investigação deles não se modifica quando observam uma figura que rompe com o esperado ( a falta dos olhos ) . Palavras - chave : autismo , síndrome de Asperger , transtornos globais do desenvolvimento infantil , movimento ocular . Autism is a complex neurodevelopmental disorder affecting social , communication and behavior domains 1 . Today , the researches have shown that more than a unique entity , autism is a segment of a broad spectrum , comprising by different pervasive developmental disorders ( PDD ) 2 . At least , two major issues might be underlying this field ; the search for earlier diagnoses and better endophenotypes characterization 3 , 4 . Several studies , based on eye tracking devices techniques , have explored the differences between PDD and normal controls gaze strategies in observing human faces 5 - 12 . The majority of the face perceptions studies have been focused on visual fixation patterns . These researches have opened new pathways in developing new diagnostic instruments and in increasing the comprehension of neurobiological bases of PDD 13 , 14 . In this study we introduce a new paradigm showing social ( human face , as well altered face stimuli - we deleted the eyes in a picture of a women using a cat mask ) and non - social ( objects ) stimulus . The goal is to verify differences in the visual scanning strategies , measured by the amount of time spent doing saccadic movements , and the number of fixations , between PDD and controls when they are observing freely ( no - rules , no task oriented ) social and non - social pictures . We hypothesize that PDD group present more saccadic movement than controls , and this difference is increased by the observation of unexpected pictures . METHOD Sample - A PDD group ( PDDG ) comprised by 10 non - mental retardation males who met DSM - IV criteria for PDD ( age range from 4 to 41 years - old ) , and an age - matched control group ( CG ) comprised by 10 males without any psychiatric disorder . All participants were drug free . The PDD diagnoses were done by two psychiatrists with expertise in the field . In addition , the Autism Screening Questionnaire 15 was applied to all studied cases . Twelve large pictures were showed ( full 15 " computer screen ) for 5 seconds to all participants ( pictures available at request to the correspondent author ) . Six were pictures from human being ( close of the face or social situations ) , two are pictures of a women using a cat mask , but in one of them the eyes were deleted , one is a picture of four masks sculptures , and the last three are pictures of draws ( a door , a salt cellar , and a dish with a set of cutlery ) . The pictures were analyzed considering two groups , the group of pictures with a human image stimulus , comprised by the first nine pictures ( social pictures ) , and the group of pictures without human stimulus , comprised by the last three pictures ( non - social pictures ) . The study was approved by the ethics committee of Mackenzie Presbyterian University . All the subjects or their parent were informed about the procedures read and signed the informed consent . Procedure - The subjects were sited in front of a computer ( 50 cm from the screen ) with an eye - tracking device , and asked to watch . They already knew that no questions would be done , and the only task was to watch some pictures . In addition , they were informed that there were no rules , neither right nor wrong ways to do the task . The eye movements were recorded with equipment EyeGaze ® ( LC Technologies Inc . ) that allows analysis of saccadic movements ( mean length and duration ) and fixation ( localization and duration ) . Statistical analysis - Four parameters ( mean length of saccadic movement , duration of the saccadic movement , fixation point time , and number of fixations ) were analyzed . We also analyzed these variables according five specific regions ( eyes region , mouth region , face , out - side of the face and nose ) . The non - social pictures were only analized as the whole picture . Logarithmic correction was applied to normalize data distribution . The analysis of variance for repetitive measurements were applied . The comparisons were done by Walds test . A significance of . 05 was considered . RESULTS The PDDG was comprised by 10 non - mental retardation males , mean age of 15 . 9 ( SD = 10 . 6 ) ( ages = 4 , 8 , 8 , 13 , 13 , 11 , 19 , 19 , 23 , 41 years old ) . The CG was comprised by 10 males without psychiatric disorders , mean age of 16 . 1 ( SD = 10 . 3 ) ( p = 0 . 97 ) . Considering the nine first pictures ( social pictures ) , the amount of time spent ( in milliseconds ) by PDDG doing saccadic movements was greater than the amount of time spent by CG [ PDDG mean = 292 . 73 ms ( SE = 67 . 62 ) , CG mean = 136 . 06 ms ( SE = 14 . 01 ) ; p = 0 . 04 ] . No difference was observed between groups in the last three pictures ( non - social pictures ) [ PDDG mean = 309 . 56 ms ( SE = 122 . 19 ) , CG mean = 247 . 38 ms ( SE = 70 . 51 ) ; p = 0 . 76 ] . The PDDG did not show any difference in the amount of time spent doing saccadic movement ( p = 0 . 54 ) when it was compared the nine first pictures ( social pictures ) with the last three ( non - social pictures ) . On the other hand , the CG showed a higher amount of time doing saccadic movements observing the non - social pictures than they did with the social pictures ( p = 0 . 02 ) ( Figure ) . The mean length of saccadic movement , the fixation point time , and the number of fixations did not show any difference between groups . Analyzing picture 6 ( a woman with a cat mask ) and 7 ( the same picture with the eyes deleted ) the PDDG showed greater amount of time spent doing saccadic movements in both pictures compared to CG [ picture 6 : PDDG mean = 320 . 06 ms ( SE = 94 . 52 ) , CG mean = 100 . 02 ms ( SE = 27 . 17 ) ; picture 7 : PDDG mean = 283 . 39 ms ( SE = 82 . 68 ) , CG mean = 141 . 69 ms ( SE = 49 . 18 ) ( p = 0 . 01 ) ] . The amount of number of fixations did not show any difference comparing the both groups observing the region of the eyes in the picture 6 [ PDDG mean = 1 . 60 ( SE = 0 . 34 ) , CG mean = 2 . 40 ( SE = 0 . 37 ) ; p = 0 . 18 ] , but the CG presented a greater number of fixations in this region in the picture 7 [ PDDG mean = 1 . 80 ( SE = 0 . 49 ) , CG mean = 3 . 40 ( SE = 0 . 52 ) ; p = 0 . 007 ] . When it was compared the number of fixations between picture 6 and 7 , the PDDG did not show any difference ( p = 0 . 6538 ) , but the CG tended to have more fixations in this region in the picture 7 ( p = 0 . 077 ) . DISCUSSION Our study showed that PDD patients spend more time doing saccadic movements than controls when observing freely human pictures ; at the same time , the controls spent more time doing saccadic movements observing the non - social pictures than they do when they observe social pictures . In addition , the PDD patients do not show any difference in the amount of time spent doing saccadic movements when they observe human pictures or non human pictures ( Figure ) . These results suggest that the major difference between groups is determined by the way of the controls explore human pictures . This study also pointed that only the CG presented a difference in the number of fixations in observing the picture in which the eyes were removed , showing that the controls present more fixations than the PDD group . In normal controls , the lack of something expected ( the eyes ) seems to induce longer investigations , suggesting that the fail in what should be watched , changes the eye tracking strategies . To understand this result we might admit that normal controls would have some presuppositions underlying their gaze pattern , implying in complex cerebral circuitries activations . If these data were replicated in larger sample size , there is a clinical relevance for these findings , since we might have the eye - tracking technique as an auxiliary diagnostic instrument . In addition , based on these results we can explore some neurobiological hypotheses that have been proposed for autism It has been discussed the different neuronal circuitry pathways involved in the reflexive and volitional saccades 16 . It seems that a group of specialized neurons named V4 neurons , present pre - saccadic activation . These neurons , and their projections to the parietal cortex , the frontal eyes fields and the superior collicullus , the areas would be involved in the oculomotor programming would be regulating the visual scanning 17 . Focusing on autism , it is important to explore if the saccade abnormality are related to an endogenous pathway dysfunction , or due to the impairment in the executive functions described in this disorder 18 . In this study , we proposed a free ( no rules , no structure , no questions ) situation , in which individuals had only to watch some pictures . Within this paradigm we decreased the dependence of the volitional saccades ( in terms of task - oriented tests of complex spatial working memory and executive control ) 16 . Based on this , our data would be suggesting that PDD present impairment in the endogenous pathway , since they do more saccadic movements than the controls . However , one can argue that the difference observed between two groups might be due to different strategies in visual scanning , meaning different executive functions patterns . This rationale seems to be reinforcing by the results obtained from the exploration of the picture without the eyes , when the controls did more fixations , suggesting more complex circuitries involvement . If this is the sense , it is possible to consider that even in freely observations normal controls apply visual scanning strategies based on presuppositions . On the other hand , it seems that PDD do not work under the same rules , allow us to formulate a metaphor , in which , the normal control tend to see the world by the brain , instead PDD patients tend to see the world by the retina . Finally , the current hypotheses of the cerebellar and neocortical systems regarding the neural origin and cognitive basis of behavioral abnormalities in autism can highlighted some etiopathological models 19 . One , tempting to hypothesize would be that due to the lesser amount of time spent in scanning human face , the PDD subjects might have caused impairment in the circuitries that would be responsible in regulating the capture of human images , the association with the social meaning of these images , through the circuitries oculomotor , cerebellum and amygdale projections neurons 20 . The limitations of this study is the small sample size , the large range of subjects age , as well as the lack of more complete neuropsychological evaluations . Interestingly , the older PDD subjects were those who closer to normal controls performed the eye gaze . Based on these data , more studies with larger samples are required in order to explore the eye gaze technique in detecting earlier PDD diagnoses . Acknowledgement - The authors thank Dr . Ami Klin for his suggestions . REFERÊNCIAS 1 . Volkmar FR , Klin A , Siegel B , et al . Field trial for autistic disorder in DSM - IV . Am J Psychiatry 1994 ; 151 : 1361 - 1367 . [ Medline ] 2 . Volkmar FR , Lord C , Bailey A , Schultz RT , Klin A . Autism and pervasive developmental disorders . J Child Psychol Psychiatry 2004 ; 45 : 135 - 170 . [ Medline ] 3 . Klin A , Jones W , Schultz R , Volkmar F , Cohen D . Defining and quantifying the social phenotype in autism . Am J Psychiatry 2002 ; 159 : 895 - 908 . [ Medline ] 4 . Dawson G , Webb S , Schellenberg GD , et al . Defining the broader phenotype of autism : genetic , brain , and behavioral perspectives . Dev Psychopathol 2002 ; 14 : 581 - 611 . [ Medline ] 5 . Boucher J , Lewis V . Unfamiliar face recognition in relatively able autistic children . J Child Psychol Psychiatry 1992 ; 33 : 843 - 859 . [ Medline ] 6 . Klin A , Sparrow SS , Bildt A , Cicchetti DV , Cohen DJ , Volkmar FR . A normed study of face recognition in autism and related disorders . J Autism Dev Disord 1999 ; 29 : 497 - 507 . 7 . Schultz RT , Gauthier I , Klin A , et al . Abnormal ventral temporal cortical activity among individuals with autism and Asperger syndrome during face discrimination . Arch Gen Psychiatry 2000 ; 57 : 331 - 340 . [ Medline ] 8 . Klin A , Jones W , Schultz R , Volkmar F , Cohen D . Visual fixation patterns during viewing of naturalistic social situations as predictors of social competence in individuals with autism . Arch Gen Psychiatry 2002 ; 59 : 809 - 816 . [ Medline ] 9 . Pelphrey KA , Sasson NJ , Reznick JS , Paul G , Goldman BD , Piven J . Visual scanning of faces in autism . J Autism Dev Disord 2002 ; 32 : 249 - 261 [ Medline ] 10 . van der Geest JN , Kemner C , Verbaten MN , van Engeland H . Gaze behavior of children with pervasive developmental disorder toward human faces : a fixation time study . J Child Psychol Psychiatry 2002 ; 43 : 669 - 678 . [ Medline ] 11 . Trepagnier C , Sebrechts MM , Peterson R . Atypical face gaze in autism . CyberPsychol Behavior 2002 ; 5 : 213 - 217 . 12 . Dalton KM , Nacewicz BM , Johnstone T , et al . Gaze fixation and the neural circuitry of face processing in autism . Nature Neurosci 2005 ; 8 : 519 - 526 13 . Dawson G , Webb SJ , McPartland J . Understanding the nature of face processing impairment in autism : insights from behavioral and electrophysiological studies . Develop Neuropsychol 2005 ; 27 : 403 - 424 . 14 . Stokstad E . New hints into the biological basis of autism . Science 2001 ; 294 : 34 - 37 . [ Medline ] 15 . Berument SK , Rutter M , Lord C , Pickles A , Bailey A . Autism screening questionnaire : diagnostic validity . Br J Psychiatry 1999 ; 175 : 444 - 451 . [ Medline ] 16 . Minshew NJ , Luna B , Sweeney JA . Oculomotor evidence for neocortical systems but not cerebellar dysfunction in autism . Neurology 1999 ; 52 : 917 - 922 . [ Medline ] 17 . Moore T . Shape representations and visual guidance of saccadic eye movements . Science 1999 ; 285 : 1914 - 1917 . [ Medline ] 18 . Hill EL , Frith U . Understanding autism : insights from mind and brain . PhilosPhilosophical Transactions of the Royal Society of London . Series B , Biological Sciences 2003 ; 358 : 281 - 289 . 19 . Courchesne E , Pierce K . Why the frontal cortex in autism might be talking only to itself : local over - connectivity but long - distance disconnection . Cur Op Neurobiol 2005 ; 15 : 225 - 230 . 20 . Wang X , Jin J , Jabri M . Neural network models for the gaze shift system in the superior collicullus and cerebellum . Neural Networks 2002 ; 15 : 811 - 832 . [ Medline ] Received 9 December 2005 , received in final form 9 March 2006 . Accepted 26 April 2006 . This study was in part supported by MackPesquisa . Dr . Marcos T . Mercadante - Rua da Consolação 896 / 62 - 01302 - 907 São Paulo SP - Brasil . E - mail : mercadante @ mackenzie . br © 2006 Associação Arquivos de Neuro - Psiquiatria Pça . Amadeu Amaral , 47 cj . 33 01327 - 010 São Paulo SP Brazil Tel . : + 55 11 287 - 6600 Fax : + 55 11 289 - 8879

Videoendoscopic surgery by extraperitoneal access : technical aspects and indication M . Tobias - Machado ; Roberto V . Juliano ; Heloisa A . Gaspar ; Ricardo P . Rocha ; Milton Borrelli ; Eric R . Wroclawski Discipline of Urology , ABC School of Medicine ( FMABC ) , Santo André , São Paulo , Brazil Correspondence ABSTRACT Laparoscopic surgery in urology is definitely incorporated to the techniques of minimally invasive treatment for urogenital diseases . Though the classic access to organs in the urinary tract is extraperitoneal , this access has not been prioritized when the videoendoscopic technique is used . In Brazil , few groups use this approach and little has been discussed about its true practical applicability . The authors intended to discuss the main technical aspects and criteria for indication , reported though the improvement achieved in a 5 - year period with 150 operated cases . A review of the literature shows that the worldly acceptance of the extraperitoneal endoscopic approach is increasing . Nevertheless , there are no evidences that the extraperitoneal access is superior to the transperitoneal route . Thus , the choice depends basically on the surgeon ' s preference . Major advantages are the immediate access to the renal hilum and isolation of peritoneal structures . Employing this access is useful when one suspects that significant peritoneal adherences could prevent the surgical act or when one wishes to preserve the integrity of the peritoneal cavity . Key words : video - assisted surgery ; laparoscopic surgery ; retroperitoneal space INTRODUCTION Ablative laparoscopic surgery in urology is widely accepted in selected situations because it presents well defined advantages in relation to open surgery , such as earlier return to routine activities , reduction in the hospitalization , decreased blood loss and reduction in analgesic use post - operatively , in addition to superior esthetic result ( 1 , 2 ) . Extraperitoneal access is the preferential route in cases of open urologic surgery because it provides a direct approach to the organs of the urinary system , without the need of manipulating the bowel , with a lower possibility of paralytic ileus and with drainage of the open urinary tract without contact with the peritoneal cavity . Despite these features , few specialized centers have prioritized the retroperitoneal approach when videoendoscopic access is employed . Most authors give preference to the transperitoneal route due to the " larger working space " and greater facility in viewing anatomical structures , what would result in a lower learning curve , especially for those who are initiating in laparoscopy ( 1 , 3 ) . The first report of therapeutic retroperitoneoscopic access in urology dates from 1978 , when Wickham ( 4 ) performed the extraction of a proximal ureteral stone . However , proper standardization and popularization of the technique were established by Gaur in 1992 , with the development of the atraumatic balloon for retroperitoneum expansion ( 5 ) . Since then , some groups in the United States , France , Germany and Japan have published their results relative to this technique ( 6 - 8 ) . In our setting , we have used , preferably , this access , since 1997 , in the treatment of several urologic diseases ( 3 ) . We intended to describe the technical aspects and main advantages and disadvantages of this minimally invasive access , comparing them to data in the literature . SURGICAL TECHNIQUE AND STRATEGY General Checking of Material — The material required for surgery is the same used for conventional laparoscopic surgery , added by some details that are inherent to each particular surgical procedure . Disposition in the Surgical Room — In lumbar access , the surgeon operates the patient in a position similar to open surgery , that is , posterior . Due to the lateral position of the patient in the surgical table and the long length of the laparoscopic material , we recommend that the surgeon , for better comfort , be positioned over an estrade . The camera stands beside the surgeon with the assistant and the instrumental table , at the contralateral side ( Figure - 1 ) . The positioning of the surgical team for pelvic surgery is the same described for transperitoneal laparoscopic surgery ( Figure - 2 ) . Lumbar Surgery Position of the Patient — The patient is placed in lateral decubitus , opposed to the side intended for surgery , the table is flexed in order to raise the flank area and to enlarge the space between the iliac crest and the costal border . The patient is fixed in this position and the extremities are arranged in order to avoid or minimize neuromuscular sequelae . Access to the Retroperitoneum - The retroperitoneal cavity must to be created in order to position the trocars and develop the surgical procedure . Initially a transverse incision is performed by 1 . 5 cm planes , below the extremity of the 12 th rib the thoracolumbalis fascia is opened , reaching the retroperitoneal space . A careful digital dissection is performed in the anterior , postero - superior and inferior directions , promoting the separation between the psoas muscle posteriorly and the Gerota ' s fascia anteriorly ( 9 ) . It is important to ensure that all entrance ports are largely free of adherences , so that punctures can be performed under direct viewing , without lesion of adjacent organs . Introduction of the Atraumatic Balloon — There is some controversy in the literature relative to the need of using a balloon for retroperitoneum dilatation . There are commercially available products , such as the balloon trocar , that make this access easier , where the space can be created under optical viewing inside the balloon , monitoring the dissection . In order to optimize costs , some authors have adapted expansion systems with lower cost materials ( 8 , 10 - 12 ) . We have used a balloon made through a double glove finger ( placing one finger inside the other so to obtain greater resistance against rupture ) , tied with a cotton thread to a 18F urethral catheter , where we inject physiologic saline solution . This device allows a 500 - 1000 mL capacity , depending on the procedure to be performed ( Figure - 3 ) . In procedures where we intend to approach the middle / distal ureter ( especially nephroureterectomies ) , we use the 2 balloons technique previously described by Gill et al . ( 13 ) . Initially , as preconized by Gaur , we left the balloon inflated for 10 minutes , with the objective of performing the hemostasis of small vessels . Based on the experience of certain groups that perform only the digital technique , we started to remove the balloon immediately after its expansion and we did not observe bleeding or any difference in the quality of the images obtained . Creation of Pneumoretroperitoneum - A Hasson trocar ( 10 - 12 mm ) is introduced under direct viewing into the incision and fixed with 2 - 0 cotton sutures , in order to avoid escape of air ( Figure - 4 ) . There are special devices such as the threaded trocar ( Figure - 4B ) or with inflatable balloon ( Figure - 5 ) that allow an excellent sealing , however with higher costs . When a Hasson trocar is not available , it is possible to employ muscular purse - string suture and a common trocar for such function . The retroperitoneum is insufflated with carbon dioxide through this trocar until a pressure of 15 mmHg is reached . A laparoscope of 0 ° or 30 ° is introduced into this port , enabling the viewing of the musculature posteriorly , and the Gerota ' s fascia and peritoneum anteriorly ( Figure - 6 ) . We have worked with a 0 ° optics . The 30 ° optics can be especially useful during the dissection of the kidney ' s superior pole and adrenal glands , which are places located deeper and with difficult access under linear viewing . Secondary Ports — All of them are introduced under direct viewing with the aid of optics . The second port ( 10 mm ) is positioned 2 cm above the iliac crest , through the floor of the inferior lumbar triangle ( Petit ) . Some authors prefer to start the retroperitoneal access at this point . Next , the optics is transferred to this port . The third port ( 5 mm ) is placed 1 . 5 cm inferior and lateral to the angle formed between the lower edge of the 12 th rib and the paravertebral muscles , making sure that it penetrates above the subcostal nerve . This port and the access port are used by the surgeon . The fourth port ( 5 mm ) is manipulated by the assistant in order to separate the structures and must be introduced below the extremity of the 11 th rib or in medial position in the anterior axillary line so that it does nor perforate the peritoneum ( Figure - 7 ) ( 14 ) . Slight variations are required according to the procedure . For adrenal surgery , punctures are made at a 1 - 2 cm more anterior position , to make the access to the gland easier , especially the most posterior trocar , which could present difficulty during the approach in a conventional position due to the distance and the limitation in the forceps length . The same access is useful when one intends to perform sutures , allowing a better approach angle to the renal pelvis ( pyeloplasty and pyelolithotomy ) . In such cases a slight lateral decubitus to the surgeon side is necessary in order to promote better comfort . Still on access variations , it can be useful to replace the assistant ' s 5 mm trocar by a 10 mm trocar in cases there it is necessary to separate more widely the peritoneum ( giving access to a liver retractor ) , such as in adrenal surgeries or when a peritoneal perforation occurs , rendering the procedure difficult . When the surgeon intends to perform a nephroureterectomy , the port of the Petit ' s triangle is placed in a more anterior position , so that it enables a better distal view of the ureter , and the surgeon can perform urethral dissection moving to the other side and using a more medial and more inferior puncture , with the optics being transferred to superior median puncture . In this situation , the change in the spatial orientation requires the monitor to be transferred to the patient ' s lower region . Pelvic Surgery Position of the Patient — The patient is placed in semi - gynecologic position with a Foley ' s catheter draining the bladder . We prefer using a wooden plate in the shape of an inverted " Y " , but it is possible to adapt the position in a table with stirrups . When the approach over the bladder or the urethra is nor necessary ( lymphadenectomy ) , the patient can be placed in supine position . Approach to the Pre - Peritoneal Region — A 1 . 5 cm arcuate incision in the umbilicus or a vertical intra - umbilical incision is made . The dissection is performed in the subcutaneous tissue and the aponeurosis , promoting its transverse opening , close to the linea alba . It is possible to view the Douglas ' arcuate line posteriorly and the borders of the abdominal rectus muscle laterally . The medial region of the abdominal rectus muscle is digitally dissected towards the Retzius ' space and until the pubic symphysis , moving the peritoneum posteriorly . Similar to the lumbar access , all the potential entrance sites for the trocar must be released from the peritoneum , in order to avoid its perforation . Sites that are more difficult to dissect are the lateral regions of hypogastrium ( lateral insertion of the Douglas ' ligament ) . Differently from the transperitoneal access , a largely exaggerated Trendelemburg position is not necessary , since the intact peritoneum provides support to the bowel , a fact that can promote anesthetic advantages resulting from a smaller cephalic slope . Introduction of the Atraumatic Balloon — The dilating balloon is positioned in the Retzius ' space and insufflated with 800 - 1000 mL of saline solution distending the extraperitoneal region . For procedures where we don not need a larger dissection of the median plane ( lymphadenectomy or Burch surgery ) , we idealized a balloon with 2 simultaneous glove fingers that would have the advantage of expanding more efficaciously the lateral regions ( sites with a more difficult access to digital dissection ) ( Figure - 4 ) . Creation of Pneumoretroperitoneum — Performed similarly to the lumbar access . Upon verifying the created space , it is possible to view the bladder , the pubic symphysis and eventually the iliac vessels ( Figure - 8 ) . Secondary Ports — The number and position of ports depend on the surgical procedure to be performed ( Figure - 9 ) . A 10 mm trocar positioned on the median line 2 cm above the pubic symphysis can be used for the surgeon ' s work , jointly with a forceps that is introduced in the 5 mm trocar , 2 cm superior and medial to the antero - superior iliac spine , opposite to the side that will be approached . We prefer this conformation for pelvic lymphadenectomy . Some procedures can be performed with only 3 ports ( 2 in iliac fossae for the surgeon ) , as in Burch ' s surgery . Complex procedures such as radical prostatectomy require 5 ports , 2 of them placed between the optics and the punctures in iliac fossa ( suited for dissection and sutures ) . COMMENTS Extraperitoneal access represents the preferential approach in conventional urologic surgeries ( 13 , 15 , 16 ) . However , the initial application of extraperitoneal videoendoscopic surgery presents greater technical difficulty , mainly due to a smaller working space , lower lightning and the spatial orientation , which are responsible for a larger learning curve ( 6 - 8 ) . The issue of working space is relative and directly associated with a good peritoneal detachment and proper installation of the ports , being feasible even in children ( 17 , 18 ) . Concerning the spatial orientation , the optics must be always kept in a position where it is possible to observe the posterior muscles in horizontal position , thus allowing anatomical parameters to be identified . In our Service , where 150 retroperitoneoscopic procedures were performed up to now , we did not observe a greater difference in the technical adaptation for this approach , when compared with the transperitoneal route . We believe that the expansion of the extraperitoneal space with the aid of the atraumatic balloon — either hand - made , industrialized , direct viewing - guided or not — is recommendable since it enlarges the surgical field in areas that cannot be reached by the finger , reducing the need of forceps dissection ( 3 , 14 , 17 ) . The use of the balloon trocar has the advantage of allowing the visualization of structures , especially the renal pedicle , during the expansion . Most authors do not believe that the location of the dilating balloon inside Gerota ' s fascia is essential , as it was originally described by Gaur ( 5 ) . The creation of the pneumoretroperitoneum is similar to the one performed in the transperitoneal access , including the recommended pressure of 15 mmHg . There is controversy about the repercussions caused by the pneumoretroperitoneum when compared with pneumoperitoneum . Some works initially proposed the occurrence of a higher absorption of CO 2 in pneumoretroperitoneum . Currently , it is believed that hypercapnia produced by CO 2 insufflation does not differ between transperitoneal and retroperitoneal accesses , with rates around 5 - 10 % , and rarely with the appearance of clinical manifestations ( 8 , 19 ) . There are also reports of a higher index of pneumothorax with the extraperitoneal lumbar access resulting of pleural perforations promoted by dissection close to the pleura or by the higher diffusion of gas to the pleural space . Wolf et al . documented an incidence of pneumothorax / pneumomediastinum of 41 % with no clinical repercussions , in patients submitted to extraperitoneal laparoscopy ( 19 ) . Gill et al . observed the occurrence of pneumothorax and pneumomediastinum in 0 . 6 % and 0 . 4 % , respectively . Nevertheless , they stress that the post - operative radiological control was not routinely performed in all patients , and those values could be underestimated due to undiagnosed subclinical cases ( 8 ) . The permanent surgical material used in retroperitoneoscopy is similar to that used in conventional laparoscopy , except for the Hasson trocar , which eventually can be replaced by a common 10 mm trocar fixed to the aponeurosis by a " purse - string " suture . Excess or improper location of trocars can promote a collision between the forceps , a fact known as " trocars conflict " , responsible also for a greater difficulty in suture . Due to these issues , few series report reconstructive procedures through extraperitoneal access ( 3 , 7 , 20 ) . Inadvertent peritoneal opening , with resulting pneumoperitoneum , can increase the grade of technical difficulty . It is more pronounced during pelvic surgeries , since in lumbar surgeries the lateral position displaces the bowel medially ( 8 ) . When it is not possible to proceed with the surgery , a transperitoneal puncture can be made for escape of air , as well as the conversion to transperitoneal laparoscopic technique or , as the last option , conversion to open technique . The bagging of organs in the extraperitoneal space can also be more laborious , especially when industrialized bags with a rigid entrance hole are not available . Some authors , in more difficult cases , suggest the opening of the peritoneum at the end of the procedure in order to increase the space , making the maneuver easier ( 6 ) . We have not used this maneuver routinely , since it is usually possible to handle the specimen in the retroperitoneal space . When the specimen is too large and requires the enlargement of one of the ports , we enlarge the incision and introduce the bag in the retroperitoneum under viewing , favoring the introduction of the specimen in the surgical bag as well . There are some factors that can hamper or prevent the use of extraperitoneal access . The presence of obesity , which results in a higher amount of retroperitoneal fat , is a factor of increasing difficulty for identifying structures of the renal pedicle and adrenal gland . Despite the surgical time getting longer and the surgery being a lot more laborious , the benefits for this group of patients are indisputable . Conditions where there is no capacity for creating a space between the kidney and the abdominal musculature , such as previous retroperitoneal surgery , severe renal inflammation and the presence of very large kidneys , are relative contra - indications . In such situations it is possible to try to create the space and , in case of impossibility , the access port is used as an adjunct in the transperitoneal approach . We must also remind that in such cases , surgical difficulties will be found in the transperitoneal access as well , however with a larger space for work . Hemal et al . ( 12 ) reported the use of laparoscopic nephrectomy in 18 patients with large hydronephrosis ( over 1 , 000 mL in volume , which surpassed the middle line or extended themselves by more than five vertebral spaces ) , being 12 by retroperitoneal route . Hobart et al . also presented their favorable experience with bilateral extraperitoneal nephrectomy for polycystic kidneys ( 21 ) . Contrary to most laparoscopists , both works preconize the extraperitoneal access as a choice in the management of kidneys with large dimensions . Hemal et al . showed also a large experience in the treatment of renal inflammatory pathologies ( including pyonephrosis and tuberculosis ) , demonstrating that it is possible to use the extraperitoneal approach even when local inflammation is predicted ( 11 ) . CONCLUSION The choice of access is fundamentally based in the surgeon ' s preference and in particularities in each case . The assumed difficulties that occur with the extraperitoneal access can be resolved if a rigorous technical standardization is achieved . Considering the advantages and limitations previously discussed , we use the extraperitoneal approach as the choice access in the majority of laparoscopic procedures in urology . We believe that even for surgeons who prefer the transperitoneal access , knowing the extraperitoneal access is useful , since it can be needed in patients with antecedents of major abdominal surgery or previous peritonitis , situations where intraperitoneal adhesions can hinder the transperitoneal surgery . REFERENCES 1 . Abbou CC , Cicco A , Gaswan D : Retroperitoneal laparoscopic versus open radical nephrectomy . J Urol . 1999 ; 161 : 1776 - 80 . 2 . Winfield HN , Hamilton BD , Bravo EL , Novick AC : Laparoscopic adrenalectomy : the preferred choice ? A comparison to open adrenalectomy . J Urol . 1998 ; 160 : 325 - 9 . 3 . Tobias - Machado M , Pinto MA , Juliano RV , Borrelli M , Wroclawski ER : Extraperitoneal laparoscopic access : experience in 72 cases . Int Braz J Urol . 2001 ; 27 ( suppl 2 ) : 121 - 122 [ in Portuguese ] . 4 . Wichkam JEA : The Surgical Treatment of Renal Lithiasis . In : Wickham JEA , ( ed . ) , Urinary Calculous Disease . New York , Churchill Livingstone . 1979 ; pp . 145 - 198 . 5 . Gaur DD : Laparoscopic operative retroperitoneoscopy : use of a new device . J Urol . 1992 ; 148 : 1137 - 9 . 6 . Gill IS , Schweizer D , Hobart MG , Sung GT , Klein EA , Novick AC : Retroperitoneal laparoscopic radical nephrectomy : the Cleveland Clinic experience . J Urol . 2000 ; 163 : 1665 - 70 . 7 . Gill IS , Rassweiler JJ : Retroperitoneoscopic renal surgery : our approach . Urology . 1999 ; 54 : 734 - 8 . 8 . Gill IS , Clayman RV , Albala DM , Aso Y , Chiu AW , Das S , et al . : Retroperitoneal and pelvic extraperitoneal laparoscopy : an international perspective . Urology . 1998 ; 52 : 566 - 71 . 9 . Tobias - Machado M , Pinto MA , Juliano RV , Cintra CC , Wroclawski ER : Retroperitoneoscopic renal biopsy . Int Braz J Urol . 2002 ; 28 : 192 - 6 . 10 . Suzuki K : Laparoscopic adrenalectomy : retroperitoneal approach . Urol Clin North Am . 2001 ; 28 : 85 - 95 . 11 . Hemal AK , Gupta NP , Wadhwa AG , Kumar R : Retroperitoneoscopic nephrectomy and nephroureterectomy for benign nonfunctioning kidneys : a single - center experience . Urology . 2001 ; 57 : 644 - 9 . 12 . Hemal AK , Wadhwa SN , Kumar M , Gupta NP : Transperitoneal and retroperitoneal laparoscopic nephrectomy for giant hydronephrosis . J Urol . 1999 ; 162 : 35 - 9 . 13 . Gill IS , Munch LC , Lucas BA : Initial experience with retroperitoneoscopic nephroureterctomy : use of a double - ballon technique . Urology . 1995 ; 46 : 747 - 50 . 14 . Tobias - Machado M , Pinto MA , Juliano RV , Mattos MHE , Wroclawski ER : Alternatives for distal ureter resection in laparoscopic nephroureterectomy . Int Braz J Urol . 2002 ; 28 : 109 - 15 . 15 . Gill IS , Grune MT , Munch LC : Access technique for retroperitoneoscopy . J Urol . 1996 ; 156 : 1120 - 4 . 16 . Tobias - Machado M , Pinto MA , Juliano RV , Borrelli M , Wroclawski ER : Preliminary results of ureteral intussuception in exclusive retroperitoneoscopic nephroureterectomy . Acta Esp Urol . 2002 ; 55 : 582 - 6 . 17 . Tobias - Machado M , Cartum J , Santos - Machado TM , Gaspar HA , Simões AS , Cruz R : Retroperitoneoscopic adrenalectomy in an infant with adrenocortical virilizing tumor . São Paulo Med J . 2002 ; 120 : 87 - 9 . 18 . Matin SF , Gill IS : Laparoscopic radical nephrectomy : retroperitoneal versus transperitoneal approach . Curr Urol Rep . 2002 ; 3 : 164 - 71 . 19 . Wolf JS Jr , Monk TG , McDougall EM , McClennan BL , Clayman RV : The extraperitoneal approach and subcutaneous emphysema are associated with greater absorption of carbon dioxide during laparoscopic renal surgery . J Urol . 1995 ; 154 : 959 - 63 . 20 . Janetsckek G , Peschel R , Franscher F : Laparoscopic pyeloplasty . Urol Clin North Am . 2000 ; 27 : 695 - 704 . 21 . Hobart MG , Schweizer D , Gill IS : Bilateral retroperitoneal laparoscopic nephrectomy for adult polycistic kidney disease . J Endourol . 1999 ; 13 ( suppl 1 ) : 90 - 1 . Correspondence to Dr . Marcos Tobias - Machado Rua Oscar Freire , 1546 / 53 São Paulo , SP , 05409 - 010 , Brazil Fax : + 55 11 3887 - 3363 E - mail : telmamsm @ icrhcnet . usp . br Received : April 14 , 2003 Accepted after revision : August 26 , 2003 © 2006 Sociedade Brasileira de Urologia Rua Bambina , 153 22251 - 050 Rio de Janeiro RJ Brazil Tel . + 55 21 2539 - 6787 Fax : + 55 21 2246 - 4088

Introduction to the Post - Human Genome Project era , a target for interactions between polygenic and / or multiphenotypical components in cancer control in South America Introducción a la post era del Proyeto Genoma Humano : la interrelación entre componentes multi - genéticos y multi - fenotípicos en el control del cáncer en América Latina como una meta 1 International Institute of Fertility . 142 / 4 Achuza Ra ' anana , 43300 , Israel . 2 Division of Environmental and Occupational Health , Department of Life Sciences , Bar - Ilan University . Ramat Gan , Israel . Abstract Epidemiological studies have suggested that the propensity to develop malignancy involves a complex mix of genetic and environmental determinants , however both older and innovative techniques display unresolved questions regarding etiology . Current barriers to achieving the potential benefit from this understanding are : 1 ) incomplete background on the various environmental and genetic factors involved in the carcinogenesis mechanism ; 2 ) difficulties in accurately differentiating specific molecular subtypes and measuring the effective cellular exposure dose ; and 3 ) difficulties in determining the multifactorial interaction between genetic and environmental factors . To extrapolate Human Genome Project research findings to the Post - Human Genome Project era , South America provides a large population and large - pedigree families , thus including genetically heterogeneous and less heterogeneous groups . An initial strategy might be to trace high risk populations and the respective exposures to which they are susceptible , such as : 1 ) migration , identifying rural migrant populations ; 2 ) inherent susceptibility , studying " long term homogeneous populations " or large families living in similar rural environments ; and 3 ) dissection of gene - environmental interaction . Key words Neoplasms ; Population Genetics ; Human Genome Resumen Estudios epidemiológicos han demonstrado que la susceptibilidad de la población a las enfermedades malignas está basada en interrelaciones genéticas hereditarias y no hereditarias . Las técnicas epidemiológicas tradicionales no han resuelto los problemas básicos de los mecanismos etiológicos . Las barreras existentes son : 1 ) el conocimiento incompleto de las etapas del mecanismo de la carcinogénesis accionada por factores genéticos y ambientales ; 2 ) la dificultad en delimitar subtipos específicos de neoplasmas basados en mecanismos moleculares definidos , y las dosis efectivas de exposición celular ; y 3 ) la capacidad en determinar la interrelación en el mecanismo genético - ambiental . Anticipandose al futuro , América Latina presenta la oportunidad para capitalizar los recientes avanzos en el conocimiento molecular , aplicando técnicas epidemiológicas y biológicas . La primera estrategia es la delimitación de poblaciones de alto riesgo o que vengan a representar alto riesgo en el futuro . Las estrategias deberian identificar : 1 ) poblaciones de migración reciente a areas urbanas com antecedentes genéticos homogéneos ; 2 ) susceptibilidad genética en familias numerosas residentes en zonas rurales com antecedentes genéticos homogéneos y menos homogéneos ; y 3 ) estudios biológicos específicos de la interrelación genética ambiental en distintas situaciones multi - genéticas y multi - fenotípicas entre sus componentes . Palabras clave Neoplasias ; Genética Poblacional ; Genoma Humano One chapter , one challenge The primary prevention of human cancer relies on the idea that reducing a population ' s exposure to a causal risk factor will result in decreased cancer incidence . Given that organisms are adversely affected by hazardous environments , susceptible individuals are by definition affected more severely or more quickly under hostile surroundings . Hence , primary prevention is reaching new areas in the interrelationship between polygenic ( multiple genes ) and multifactorial ( genetic and environmental ) events . Owing to the rapid development in the fields of molecular biology and molecular epidemiology since the late 1980s , scientists have expanded the capacity of epidemiological techniques to identify the biologically effective dose at tissue targets ( for example , DNA ) , early biological effects ( for example , DNA alterations ) , and variations in individual susceptibility . The goals are a chain of accurate steps from host - biological subtypes , determining exposure , and genetic - multifactorial interrelations ( Table 1 ) . Available biologic evidence shows the strengths and limitations of these types of associations , particularly in susceptibility to chemically - induced cancers in the micro - environmental field ( read specific occupational environments ) and the extent to which genetic heterogeneity and other factors play a role in the process . A typical example from traditional epidemiological research on potential cancer - causing exposures with successful application in the occupational and para - occupational areas of preventive interventions is that of asbestos - related malignancies . However , not all associations are causal and not all exposure - cancer associations ( with perhaps a thousand associations inferred ) are biologically plausible . More recent epidemiological studies suggest that the propensity to develop a malignancy involves a complex mix of genetic and environmental determinants and therefore shows patterns of inheritance that do not follow simple Mendelian transmission ( Lander & Schork , 1994 ) . However , both older and innovative techniques still face unresolved fundamental questions regarding etiology , susceptibility , and environmental carcinogenesis . As mentioned above , epidemiological studies have used measurement in hazardous environments , where individuals are affected more severely or more quickly under hostile surroundings . Two examples lead to different approaches to the dilemma of this gene - environmental interrelationship . As a first example , case - control epidemiological studies of female breast cancer , describing an association between genetic deficiency in isoforms of the detoxification enzyme glutathione S - transferase ( GST , mainly class mu in post - menopausal women ) have conflicting results ( Kelsey et al . , 1997 ; Helzsouer et al . , 1998 ) . Could differences in the environmental component of the putative gene - environmental interaction be responsible for dissimilar results such as geographic distribution , exposure , and / or ethnicity ( Laden et al . , 1997 ; Hartmann et al . , 1997 ) ? If so , these lines point to a diversity of mutational exposures in breast cancer , where environmental studies should be guided by a classification into genetically homogeneous populations to show sufficient evidence of biological plausibility . The second example is from the study of the so - called " A - bomb survivors " , focusing on the quantified leukemia relative risk of 75 , 991 Japanese survivors for whom radiation exposure levels were available ( Shimizu et al . , 1990 ) . Two hundred and two survivors developed leukemia between 1950 and 1985 , but the relative risk declined from 11 . 7 to 1 . 8 over time . The exposed Japanese population is genetically less heterogeneous than other populations in the cancer surveillance network , but even in this example , distinctive mutational patterns were able to differentiate the highly susceptible population with a short exposure - to - diagnosis interval . In terms of similar evidence of environmental - gene interaction , it is reasonable to cite the example of the differential risk of workers exposed to benzene in the development of leukemia and bone marrow aplasia ( Aksoy , 1985 ; Linet et al . , 1996 ) . Far from being fully clarified , this genetically complex disease involving traditional exposure - related association ( environmental or occupational ) with cancer has produced novel approaches to define the role of genetic susceptibility in epidemiological studies of cancer etiology . Individual genetic susceptibility is a major etiologic factor of cancer . While there has been impressive progress in understanding monogenetic diseases prone to cancer risk , for example ataxia - teleangiectasia ( Gilad et al . , 1998 ) , or which are associated with an inherent dominant gene such as bilateral retinoblastoma ( Sippel et al . , 1998 ) , such studies have had relatively little impact on prevention , implications in cancer control , and public health perspectives , due to the low incidence of most of these diseases . In contrast , as was pointed out , more important traits related to the propensity to develop neoplasms follow more complex polygenetic and multifactorial patterns ( Weeks & Lathrop , 1995 ; Risch & Merikangas , 1996 ) . Such complexity makes it difficult to characterize and identify each and every factor contributing to cancer etiology in a given individual or in the population at large . The following are some of the current barriers to achieving the potential benefit from this understanding : 1 ) Incomplete understanding of the various environmental and genetic factors involved in the carcinogenesis mechanism and difficulties in their assessment . 2 ) Difficulties in accurately differentiating specific molecular mechanisms . 3 ) Limitations in measuring the effective cellular exposure dose and it interrelationship with the polygenetic etiology and the effective individual exposure . 4 ) Limited ability to determine the multiple interaction between genetic and environmental factors . This interaction gene / mutation specific creates " the phenomenon of differential genetic susceptibility to certain environmental influences " ( Xu & Schork , 1997 : 521 ) . Another barrier to identifying environmental factor ( s ) for neoplasms is the paucity of appropriate epidemiological studies conducted in the field , for example , individual developmental and differential phenotypical modes of transmission , genetic heterogeneity , incomplete genetic penetrance , and delayed age of onset . Of course , a potential effect of the use of molecular epidemiology is that it will increase the number of subsets in each traditionally defined neoplasm type , and as molecular assays become more sensitive , the probability of false - positive findings increases and diagnostic specificity is reduced . By the years 2003 - 2005 it is expected that the 3 billion base - pairs human genome will have been completely explored and its 50 , 000 - 100 , 000 genes deciphered ( Boguski , 1995 ; Schuler et al . , 1996 ) . As a result , it will become possible to identify mutant genes and polymorphic alleles associated with the development of most neoplasms . In addition , the ability to accurately measure molecular markers of exposure ( for example , DNA protein adduct , see Table 1 ) will help in the analysis of the differential contribution of each environmental carcinogen to the development of malignancies ( Perera , 1996 , 1997 ) . To date , the most common use of biomarkers in cancer research is in analyzing the complex interplay of various molecular determinants in the initiation of neoplasms . Illustrating this situation of the conjunction of molecular epidemiology techniques and the information to come from the Human Genome Project , some potential future issues will be the solution to small sample sizes in study populations , inappropriate selection of controls , subclassification of neoplasms , and difficulties in identifying multifactorial interactions between polygenic and / or multiphenotypical components . This situation is currently unsatisfactory using traditional epidemiological methods and will continue to pose problems if the Human Genome Project potential is not applied to develop an understanding of novel gene - environmental interaction in an area like Latin America with a broad socioeconomic transition . These new aspects point to a diversity of challenges in cancer research and may be critical for future studies of genes related to environmental susceptibility to incorporate larger scale studies with more sophisticated methods of neoplasm subclassification into etiologically more homogeneous groups . The critical element , at least up to now , has been the potential public impact and potential benefits associated with interventions based on common genetic risks . A full understanding of the mechanism involved in gene - environmental mechanisms could lead to preventive measures , including the management of high - risk groups carrying inherent germ - line genes . In the face of inconsistent population studies and elusive environmental risk factors related to the environmental - genetic complex which begins to emerge in specific cancer sites for example in ductal breast cancer , understanding the role of GSTs in the glutathione conjugation of estrogens and lipid metabolism in different germ - line mutation carrier populations ( Zhu & Conney , 1998 ) one would ask what might be the appropriate critical approach to evaluating this threshold of evidence for accepting putative etiology associated with potential public health impact . To extrapolate the Human Genome Project research findings to the Post - Human Genome Project era in order to the study cancer in human population , three important concepts could apply : a ) the sample size must be large ; b ) large study should cover both , long - term isolated populations and those having migrated recently from remote to more urban and industrial areas ; and c ) and the markers must be informative ( Ishibe & Kelsey , 1997 ) . An initial strategy could be to trace high - risk populations and the respective exposures to which they are susceptible . The following approach would facilitate this strategy : a ) Migration study by identifying rural migrant populations living in urban areas . By identifying the rural areas from which the population came and comparing cancer burden between the urban ( host ) and rural ( origin ) areas , it is possible to estimate the attributable fraction of neoplasm associated with the urban environment without confounding from genetic factors . Rural migrants may be moving on a large scale from the same region , and they may be genetically homogeneous , thus facilitating gene - mapping studies ( Khoury et al . , 1998 ) from China . The following is an example from two parallel studies conducted in Los Angeles ( Douer et al . , 1996 ) . Acute promyelocytic leukemia ( or acute myeolocytic leukemia FAB - M3 ) was found to be significantly higher in Hispanics than in non - Hispanics ( proportions : 37 . % and 6 . 5 % , respectively , p < 0 . 00001 ) in a hospital - based study on recent migrant groups . A similar trend , although to a lesser but still significant degree , was found in a population - based epidemiological study at age 30 - 69 years in the same area , for at least 15 years prior to the diagnosis of acute promyelocytic leukemia in the migrant Hispanic population as compared to the non - Hispanic population ( proportion 24 . 3 . % and 8 . 3 % , respectively , p < 0 . 0075 ) . The difference in estimated risks of acute promyelocytic leukemia in the two studies , performed in the same study area , may reflect different environmental exposures , as the authors point out , due to the migration effect . The rate in the population - based study is much closer to the non - Hispanic population , but still significantly higher , probably as a result not only of differences in genetic susceptibility , but also of long - term residence in Los Angeles ( at least 15 years ) , compared with the hospital series chapter of the study . b ) Inherent susceptibility by studying large families or " long - term homogeneous populations " living in similar rural environments and in the native population . In South America , there are still isolated populations that are ideal for researching linkage disequilibrium mapping ( Jorge , 1995 ) . Studying disequilibrium mapping in this population in large - pedigree families with high birth rates and a younger population could prove useful for valuable segregation for narrowing chromosomal regions . Searching large - pedigree families could facilitate the study , of discordant sib - pairs in gene mapping , useful to identify new environmental risk factors , controlling for genetic heterogeneity . c ) Dissection of gene - environmental interaction . Differential genetic susceptibility to specific environmental exposures is an essential part to elucidate the pathogenesis of neoplasms . By identifying large non - hereditary neoplasms in high - risk populations and new disease - susceptibility genes ( after the Human Genome Project ) , it will facilitate identification of the precise pathogenesis mechanisms . One barrier in traditional epidemiological research is the apparent lack of success in identifying the environmental risk factor ( s ) which can contribute to the paucity of controlling environmental exposure misclassification . The potential advantage in these studies using gene - environmental dissection is that occupational and environmental exposures to risk factors are determined within the disease group and compared between those who carry a specific gene - susceptibility and those who do not ( Dorman et al . , 1988 ) . Comparison analysis of the genotypical determinant of the disease and its associated absolute risk across the population ( migrants , rural / urban , industrialized / primary economy ) may provide clues as to specific mechanisms of pathogenesis and etiology , in addition to new therapeutic and specific preventive interventions . Few epidemiological studies have been conducted that analyze the interplay between environmental factors and DNA or cytogenetic changes ; most of them were retrospective and focused on this association , without adjusting for genetic factors ( see Table 1 ) . An example was an epidemiological study on women working in agriculture , the textile industry , and housewives using a mailing survey through the Swedish Environmental Cancer registry , in which emphasis was given to ascertaining past exposure , showing increased risk in specific hematopoietic neoplasms ( i . e . , adjusted standardized incidence ratio of 3 . 6 for multiple myeloma in textile workers ) ( Linnet et al . , 1994 ) . Moreover , as the author mentioned , the study lacked detailed information on specific exposure types and duration of exposure , and occupational data were compared with compiled groups of neoplasms rather than with dissected gene - environmental components . Conduction of comprehensive data - bases that are informative ( including incidence and an occupational - environmental matrix ) , representative ( population - based , large - pedigree families , and isolated populations ) , and with reliable biological samples in South America should allow for testing innovative hypotheses in the post - Human Genome Project era . Traditionally , an ecological study examines the relationship between the disease and the direct event , such as environmental exposure across various populations . In addition , the use of large numbers of cells across regions will somehow ensure random cross - regional relation between the disease , the exposure , and their covariates ( Cohen , 1990 ) . Furthermore , it is sometimes assumed that for spatial correlation to be compared , region itself must be a confounder on the individual level after other factors are controlled . There are already a number of descriptive epidemiological reviews that have accurately illustrated cross - sectional estimates and trends in cancer incidence and mortality by region ( Coleman et al . , 1993 ; Parkin et al . , 1997 ; Pisani et al . , 1997 ) , and it is not intended to replicate them here . Instead , focus will be on recent data and the potential of increasing informative sources for interaction between polygenic and / or multiphenotypical components . It is beyond the purpose of these comments to fully explore cancer registration in South America . Data presented here , comprise more or less 5 - 6 % of the population living in the region , which apart from statistical variation , remain low and randomly representative of demographic and environmental components of the continent . Given this limitation , Table 2 shows cancer burden from recently published incidence data by population - based registries across regions compared to South America as a population reference . There is a substantial variation in the incidence of these selected cancer sites . Briefly , all neoplasms in both sexes are lower compared with others regions . Moreover , the esophagus , stomach , and uterine cervix showed higher incidence rates . In a more detailed analysis based on the same cancer registration network ( Table 3 ) , a heterogeneity of incidence rates could shed light on the selected cancer sites . It is likely that the information processes among the various registries and diagnostic criteria tend to explains the heterogeneity of incidence rates , yet clear patterns emerge from the network information . Prostate and uterine cervical cancer varied inversely across South America . Incidence of esophagus , colon , and breast cancers in both gender differs significantly between the highest southern and lowest northern areas . These results from the two areas indicate clear patterns which may suggest different environmental factors and / or demographic components . 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The International Mathematical Union ( IMU ) created the International Commission on Mathematical Education ( ICMI ) . This Commission sponsored the Interamerican Conferences on Mathematics Education , summoned for the purpose of discussing the problems posed by Mathematics teaching in the various countries of the Americas . The first two conferences were of extraordinary importance and greatly influenced the teaching of Mathematics in participating countries . This influence was a consequence of the clear definition of the main goal of both events : to introduce into the curricula ( especially in secondary schools ) the subjects , language and methods of " Modern Mathematics " . THE FIRST CONFERENCE The First Interamerican Conference on Mathematics Education was held in Bogotá , Colombia , on December 4 - 9 , 1961 . It was sponsored by the International Commission on Mathematical Instruction and the Organization of American States ( OAS ) , and was attended by mathematicians and Mathematics teachers , as representatives or guests , from 23 American countries . Some of these professionals , as well as distinguished European mathematicians , were invited to lecture on Modern Math and also on how to teach it and promote its acceptance . The main purpose of this Conference was to explore the methods of teaching Mathematics at the secondary school level and also in colleges and universities , and to pass resolutions with a view to future cooperation . More specifically , the intention was to introduce in Latin America the reform of Mathematics teaching ( at the secondary level ) that was going on in many countries , especially in Europe and the United States . As explained in the preceding chapter , this reform was a worldwide movement that began in the 1950 ' s , whose purpose was to reform Mathematics syllabi and curricula that were in force at the secondary level . The reform was initiated in the developed countries , especially the United States and France , and was born as a response to a problem that , at that time , was considered to be critical : the need to bridge the gap between Mathematics as practiced by researchers and professionals in the field , on the one hand , and , on the other , the type of Mathematics then taught in secondary schools . The concepts that were to be introduced in elementary and secondary schools were not precisely the connections between Mathematics and the natural sciences , nor Discrete Math , but set theory , abstract algebraic structures , and unifying and universal concepts . The purpose was to give unity to Mathematics , using sets , relations , functions and operations as basic concepts , as well as fundamental structures of groups , rings , fields , and vector spaces . The need to adopt modern symbolism was also established . Thus , the main objective of this Conference was to foster these approaches among the delegates and to reach a commitment from them , asking that they promote curricular changes in their respective countries . The opening address was given by Dr . Marshall Stone , President of the International Commission on Mathematical Instruction , who gave a brief summary of the process of implementing Modern Math in European and U . S . secondary schools . THE IDEAS The main ideas brought forward in this Conference were the following : ( a ) The need to change the way of teaching Geometry in Secondary Schools : to teach Geometry from the perspective of Linear Algebra , forsaking Euclidean Geometry . ( b ) The need to teach Mathematics , in general , through the study of the fundamental structures , with the purpose of underscoring their unity . In this area , the teaching of Modern Algebra became of paramount importance . ( c ) The above goals could only be achieved if , at the same time , a well - organized plan was carried out that was oriented to the in - service training of teachers , thus preparing new mathematics teaching professionals with the ideas of the reform , as well as improving research in mathematics ( d ) The above goals could not be achieved without a parallel plan , very well organized and aimed the training of professors who were currently teaching . The aim was to instill these ideas in new teachers of Math , and also to upgrade Mathematics research . As far as the first of the above points is concerned , Professor Howard Fehr , from the United States ( who had represented his country at the 1958 Edinburgh Conference ) , set forth the major ideas with his contribution : " Reforming the Teaching of Geometry " . He gave a brief account of the development of Geometry , emphasizing that , in spite of the new developments that took place at the turn of the century , which indicated new directions , Euclidean Geometry still begin taught in secondary schools . Fehr was very much against this state of affairs , up to the point of stating that " Euclidean Geometry ( ... ) has nothing to do with these subjects ; nowadays it is sterile , outside the main course of mathematical advancement , and it can be filed in the archives , without any fear , for the benefit of future historians " [ i ] . Fehr , in his address to the Conference , critically questioned the teaching of Euclidean Geometry in secondary schools , and strongly supported the thesis advanced by Dieudonné in Royaumont . Moreover , Fehr proposed a program for teaching geometry in secondary schools . He said that it was possible to teach the essentials of Euclidean Geometry in two or three months . Thereafter , additional deductive work in Algebra should be given to the students , including new number systems and algebraic structures ; finally , a combination of Algebra and Geometry through the study of affine plane Geometry . All of this was in line with the ideas proposed in Royaumont by Dieudonné and Choquet , and with the viewpoints expressed by Henri Cartan at the Bologna meeting . In other words , the purpose was to guide the students , as rapidly as possible , towards the study of vector spaces . However , in spite of all this , Fehr himself cautioned that , at this level , axiomatic knowledge should not be given too much emphasis . Challenging this position , in the debate following Fehr ' s presentation , the delegates from several countries voiced their doubts . For instance , Professor Catunda ( Brazil ) disagreed with Fehr ' s vision and asked if in his country it would not be convenient " at least Euclidean Geometry " , and Coleman ( Canada ) explained that , in his own country , the reason to teach Euclidean Geometry was that " whoever has developed an interest in Mathematics found in Euclid his or her first incentive " . In general terms , however , the discussion evidenced a certain degree of agreement ( arising mainly from the European guests ) with the ideas advanced by Fehr . Choquet agreed with Fehr , although favoring the introduction of axioms , and Pauli ( Switzerland ) said that the ideas advocated by Fehr had been implemented in his country for the last ten years . Fehr ' s presentation along with the debate that we have summarized is very illustrative of the objectives of this First Conference and the doubts that were still present in that moment . As can be observed , the ideas of both Choquet and Pauli contributed to develop the criterion for change in the teaching of Geometry , despite the resistance of some of the participants such as Catunda and Coleman who expressed their doubts with at least this aspect of the reform . The second of the ideas indicated in ( b ) above , was present throughout the conference , especially in the presentations of those invited from France and the United States . This can be seen as much in their presentations as in their interventions in the debates . In this regard two of the presentations were very significant . That of Choquet ( France ) entitled " The New Math and its Teaching " and that of Marshall Stone called " Some Characteristic Tendencies in Modern Mathematics " . In the first of those presentations , Choquet began by giving a quick overview of modern Mathematics and then his view of what mathematics should be included in secondary education . His opinion was that teaching at all levels should be revised to reflect the discovery of the fundamental structures , given that as we move toward an increasingly greater unity of mathematics we should also move to a unity in its teaching at all levels . He said : " Our lemma will be : algebra and the fundamental structures from the School to the University " [ ii ] . An interesting detail : Choquet added that all teaching based on the historical method had become inconceivable . His entire discourse pointed out the need to put the student in contact as soon as possible with the unifying concepts and fundamental structures . He noted the need for the mathematician , giving little importance to psychopedagogical considerations . For example , he expounded the following principles : " 1 . We should accustom our students to think in terms of set and operations as early as possible . It will be necessary to teach the simple , universal , and precise language of sets . At the same time we should teach them the rudiments of logic in its relation to the grammatical study of their language ( to negate a proposition , to understand the force of the words and , o r , for all , there exists ) . 2 . At a very early age , our students should have a clear understanding of the concept of function . They should be able to construct various examples of functions in arithmetic , algebra , physics , and to produce the composition of two functions , to take the inverse function of a biunique function , to recognize a group of transformations . 3 . The students should be able to recognize at an early age the relation of equivalence ( numerous examples ; quotient - sets ) , relations of order , and they should study some concepts of topology . 4 . In all fields , it will be necessary to get directly at the essential tools that have numerous and immediate applications " [ iii ] Marshall Stone complemented these ideas by proposing , as something of great importance , the development of the basic elements of Modern Algebra in secondary teaching . He indicated that it seemed possible to teach Modern Algebra at the secondary level up to the point of treating polynomial rings in a field . Nevertheless , in the debate that followed , doubts were expressed . Professor Laguardia pointed out a fundamental aspect that had not been taken into consideration : How to take into account the psychological development of youth ? There was no adequate response to his question . Thus , there remained a doubt with respect to the relevance of the reform , at least in the form in which it was being suggested . It can be said that those two presentations are a reliable representation of the ideas that the organizers of the Conference had in mind . However , many of the other presentations were along the same lines , although , perhaps , not with the same clarity in their thinking . Among them were the presentations of the Latin American educators . The first of those was from Professor Alberto González Domínguez of Argentina entitled " Mathematics and our Technological Society " . Professor González expressed some ideas about the relations mathematics - physics , mathematics - automatization , and the importance of mathematics reasoning for approaching many technological and scientific problems . His interest was in making that point , but he did not propose any initiatives for the teaching of mathematics . Another presentation along the same lines was given by Professor Enrique Cansado of Chile and was called " Modern Applications of Mathematics " . He mentioned some of the applications of mathematics such as operations research , linear programming , the simplex method , nonlinear programming , dynamic programming , game theory , etc . His thesis was that these theories , at least in their elemental level , should be introduced into secondary teaching . However , in the debate that followed , some of the participants , especially the Europeans Choquet ( France ) and Bungaard ( Denmark ) , suggested that there were more interesting and important topics for secondary mathematics , namely , those topics mentioned above . It should be said that not everyone was in agreement with the main ideas being presented ; at least as they were conceived . In general , some presentations implied the need for change , but for many of the participants it appeared that the changes being proposed were too radical . For example , in his talk on " Some Ideas about the Teaching of Mathematics in the University " , Professor Guillermo Torres ( Mexico ) expressed his doubts about what should be taught and how it should be taught . His thesis was that you could not just abandon entire topics from classical mathematics , as it would then be possible to fall into formal definitions and concepts that would communicate absolutely nothing to students , given that they would not be familiar with specific cases that are more concrete . He indicated that the new ideas that students acquire should be accepted by them as something natural . He further suggested that mathematics should be taught by more or less following its historical development . This was a focus in opposition to that expressed by Choquet ( who said that teaching based on the historical method was inconceivable ) . Countering that , Torres claimed that the presentation of mathematics in its exclusively formal aspect " makes it appear to be an inhuman activity and with no sense at all , " even though that was the style that was being imposed more and more . The last of the main ideas of the Conference was of a more operational nature . It is obvious that no reform can be carried out without adequate preparation of personnel that are in direct contact with the students and are putting into practice the teaching of so many new concepts ( and old ones too but with a new language and organized differently ) . Therefore the professional development of teachers who would carry out the reform was very important . Thus , two of the presentations were on the preparation of mathematic teachers and were given by Latin American professors : A . Valeiras and Luis Santaló ( Argentina ) [ iv ] , " The Formation of Mathematics Teachers " , and Omar Catunda of ( Brazil ) , " The Preparation of Mathematics Teachers " . These presentations and the debate that followed were very important because they made clear a situation with respect to teaching mathematics in Latin American countries ( which is very similar to what happens still ) : a lack of fully - trained teachers , inadequate preparation , difficulties of support and professional development , etc . In this respect the statement of Prof . Catunda is very illustrative : " the formula that I would shout for Brazil is not ' Down with Euclid ' , but ' At least Euclid ' [ v ] " . There were also presentations that offered information on and analyzed mathematics programs in countries where reform efforts were already underway . They served to support the ideas presented in the talks in favor of the reform . Among them were the following : " New Tendencies in the Teaching of Mathematics in Colleges in the United States " , Professor E . J . McShane ( USA ) ; " The Mathematics Programs in Swiss Secondary Schools , Professor Laurent Pauli ( Switzerland ) ; and " The Mathematics Program in Denmark " , Professor Sven Bungaard ( Denmark ) . They presented experiences on the teaching of mathematics in their countries . The address of Professor E . G . Begle ( USA ) , " The Reform of Mathematics Education in the United States " , indicated how reform of mathematics teaching was being carried out in that country . He explained the predominant role of the School Mathematics Study Group ( SMSG ) in its efforts for improving the school program by providing materials and guidelines for the preparation and in - service training of teachers , as well as the strong financial support provided by the National Science Foundation ( NSF ) . The last address was given by Professor Schwartz ( France ) on " The Role of Mathematics in Physics from the Point of View of Scientific Education " . RECOMMENDATIONS The crystallization of the main ideas expressed and discussed was presented in the resolutions of the Conference . They were divided into three areas : I . Preparation of Teachers . II . In - Service Teachers . III . Improving teaching . To better understand the scope of that first conference it is necessary to consider some of those resolutions . " I . In connection with training of teachers , 1 . That centers for the training of high school mathematics teachers should offer scholarships and other facilities to those students who choose this career and that high school students should be informed , by means of conferences and publications , of the existence of a career as teachers and researchers in this field , and of the social importance and of the possibilities offered to those who follow it . 2 . That the training of teachers of mathematics should be the sole responsibility of the university and under the influence of the most competent mathematicians , to avoid the cleavage between the teaching of mathematics and progress in science and technology . In the meantime , where this training is carried out in special institutions , mathematics courses should be of a university level . 3 . That in the training of teachers of mathematics in the secondary schools , the courses should be modernize and those of a pedagogical character should be limited to proper proportions . II . In connection with teachers in active service , 4 . That regular contact be maintained between high school teachers and university professors , encouraging the former periodically to attend courses for improvement ( regular or special ) , and that the means to achieve this end , such as scholarships at home or abroad , be increased . 5 . That steps be taken to raise the socioeconomic level of the secondary school teacher holding a regular certificate , such as : ( a ) Guarantee tenure . ( b ) Establish basic salaries equal to those of other professions requiring similar or equivalent academic preparation . ( c ) Establish a system of promotions with its corresponding implications ( increase in salary , reduction of working hours , etc . ) automatically based on the number of years of service , considering supplementary advantages and taking into account publications and activities aimed at self - improvement . ( d ) Establish the sabbatical year . ( e ) Offer the teacher the possiblity of a regimen of complete dedication , as a favorable condition necessary to his progress . 6 . That a maximum of incentives be assigned ( scholarships , compensation , etc . ) so that the teachers of the secondary school who are without certificate but are in active service can obtain one , and therefore can be covered by the system established in article 5 either by completing their university studies or by taking special courses created for this purpose . III . In connection with the improvement of teaching , 7 . That the realization of courses and the creation of institutes of an experimental character , for trying out new texts and new methods of teaching mathematics , be encouraged . 8 . To suggest to the International Union of Mathematicians , UNESCO , and the Organization of American States , to take under consideration the following steps : ( a ) The intensification of programs for the training of secondary school teachers of mathematics . ( b ) The dispersion of activities , projects , and publications which have to do with the improvement and modernization of the teaching of mathematics . ( c ) The publication and distribution of reports , new texts , and translations written for teachers of the secondary schools for their use in teaching and in self - improvement . ( d ) The encouragment of research as an avenue for scientific and technological progress and as a factor in motivating teaching . ( e ) The creation of an international center for the purpose of collecting and disseminating information that is relative to new experiments and new ideas in mathematics education . 9 . To promote a wide exchange of information on new ideas in the teaching of mathematics in all countries through national meetings and other international conferences such as the present one . " THE FIRST COMMITTEE The most important of the resolutions for our purposes in this book were the resolution that proposed : " The creation of an Inter - American Commission on Mathematics Education , of a permanent character , for the purpose of providing continuity to the projects and ideas discussed in this Conference and to promote action calculated to raise the level and efficiency of secondary school and university teaching of mathematics . " It was also recommended that : " That delegates and participant establish and maintain contact with the authorities of their respective countries , so that effective measure can be taken to put into practice these recommendations . " The Conference , in one of its resolutions , designated the following individuals to act as a pro tempore committee until the Interamerican Mathematics Education Commission was established , according to recommendations in the document : Marshall Stone ( USA ) President , Alberto González ( Argentina ) , Bernardo Alfaro ( Costa Rica ) , Alfredo Pereira ( Brazil ) , and José Tola ( Peru ) . As can be observed , the recommendations of this Conference were of great importance because they committed the delegates from each country to the process of reform . They would be promoted on two fronts : on the one hand , the delegates would try to get their governments to reform the mathematics programs at the secondary level to carry the stamp of modern mathematics . On the other hand , they committed themselves to trying to influence universities and teacher training institutes to do in - service training and to prepare new mathematics educators with the ideas of the reform . The resolutions adopted indicated the success obtained by the organizers of the Conference , at least in the aspect of starting a machine for reform in Latin American countries . Apparently the reluctance shown in some cases was smoothed over . From another perspective , as can be seen in the list presented below of sponsors of the event , that Conference had the support of international and other organizations , especially from the United States , which were interested in having the ideas of reform in mathematics teaching realized in all the countries of the continent . This is evidence of the great concern in this matter from the highest levels , and the pressure that possibly was brought to bear so that the recommendations were approved in the way they were presented . THE SECOND CONFERENCE The Second Interamerican Conference on Mathematics Education was held in Lima , Peru , December 5 - 12 , 1966 . That is , five years after the First Conference was held in Bogotá . If the First Conference served to promote the introduction of the teaching of modern mathematics in American countries , the second one had as its main axis the analysis of the progress of reform . That focus was declared in the opening address by Marshall Stone . Besides the invited speakers who presented general topics related to mathematics teaching , the Organizing Committee of that Conference asked the delegates from each of the participating countries to present a report in which they summarized the efforts realized in their countries during the period between the two Conferences towards the objectives outlined in the First Conference . In his opening address , Dr . Stone recognized the scope of the problem of teaching mathematics , as well as the difficulty of solving it in a practical manner . However , at the same time , he indicated that the Organizing Committee selected a restricted number of topics so that they could be discussed throughout all the activities . THE MAIN TOPICS The theme to be studied in the Conference was posed in the following form : " In the first place , it is natural that we wish to review what has taken place in the hemisphere since the first Inter - American Conference on Mathematical Education , held almost exactly five years ago , in Bogota , Colombia . We must now ask : " What had the report of that conference to do with what has taken place in the last five years ? Have its recommendations had any influence at all ? Have some of them proved to be less practical than we had supposed at the time when we formulated them ? In which countries has progress been most marked ? In which countries have especially difficult problems been conquered ? " So we should now look back on these five years and , through the medium of a number of reports , and the discussion of them , try to see what the impact of the first conference has been and what we have succeeded in accomplishing all over the hemisphere during that time " [ vi ] . Two topics of great importance were also proposed : in the first place , the problem that students face in moving from secondary schools to the universities , and , secondly , the preparation of teachers for the primary and secondary levels . In the first of these topics , the difficulties that students face when going to a higher level of education were recognized . Generally deficient preparation causes many difficulties in adapting to the new styles of teaching that are present in higher education . The second topic was recognized to be of great importance in order to have success in any attempt to reform the teaching of mathematics . Thus , the tasks of the Second Conference were dedicated to the following three topics : 1 . To review what has taken place in the hemisphere since the first Inter - American Conference on Mathematics Education . 2 . The problem posed by the students ’ passage from the secondary school into the university . 3 . Preparation of teachers for service in the primary and secondary schools . The presentations were on those topics , and , also , on the problems that were arising in the implementation of the reform of mathematics teaching in the various countries of Latin America . The presentations were divided into four blocks : A . On Problems in Mathematical Education in Latin America . B . On Mathematics Improvement . C . On Curriculum and Transition . D . On Teacher Education . Within the topic dealt with in Block A , various problems were indicated . Some of them were related to the sociocultural and economic characteristics of the Latin American countries . Others were more specific to bringing about a reform . Professor Rafael Laguardia of Uruguay made several observations about the first type of problems in his address . His conclusions indicated the existence of several obstacles that impeded the development of mathematics and other basic sciences in Latin America . In particular , he highlighted two elements : the illiteracy that existed in almost all Latin American countries , and the rapid population growth that obliged the use of teachers without the necessary preparation in the teaching of mathematics . Thus , he proposed that the reform should be initiated , at least in his country , only in the higher levels of secondary education and that the universities should actively participate in the reform process . He added that not only was the participation of educational researchers necessary , but also that of mathematics researchers . To all of that Laguardia added the need for centers of scientific research and higher education to collaborate closely with the reform in mathematics teaching . With respect to the progress of the reform in mathematics teaching and possible solutions , Professor Luis Santaló referred to some of the problems that the reform had encountered in Latin America , specifically with teachers and programs . He identified a series of problems that had occurred during the reform process , some of which he said had been foreseeable and others , perhaps unexpected , that had arisen during the process . Given the historical importance of Professor Santaló in mathematics in the Americas , it is interesting to mention with some detail the problems he referred to : - Difficulties in convincing teachers of the need and possibility of reform . To overcome that difficulty he proposed some measures such as : convincing teachers about the recommendations of the meeting and congresses that had been held on the matter , the extensive use of modern mathematics in university level texts , the temporary displacement of the classic programs of mathematics , a great part of the mathematics being taught should be taken out of official programs . On the other hand , he proposed that teachers do a survey that would let them know that many of the topics that they had been teaching were never used , thus there was no practical argument to retain those topics . To determine the formative value of such topics , they should be analyzed in terms of reasoning as opposed to routine , and then compared with modern topics . - A second problem was convincing parents , i . e . the problem of convincing public opinion . Here Santaló proposed that applications of mathematics not be lost from view , but used to motivate some of the modern topics in connection with science . - Another problem was the preparation of teachers and student textbooks . He proposed the introduction of modern mathematics into teacher training institutes so that their graduates would be able to teach reform - based programs . He also proposed in - service teacher training . With respect to textbooks he considered that the only way to resolve the situation was to publish student textbooks with a modern mathematics focus . - The last of the problems identified by Santaló referred to the difficulty of changing Ministry of Public Education regulations in the Latin American countries . That increased the difficulty of having experiences with the new programs . He pointed out , as his last point , an aspect to which he did not give much importance : teachers who did not understand very well what was intended by the reform and , with enthusiasm , taught their courses " full of trivialities , and conceptual errors , sowing general confusion " . The address of the Peruvian professor , José Tola , considered the problem of the development of mathematical research in Latin America . He felt that much had been done in the area since 1961 and therefore mathematicians were busy with research and were not available to work on carrying out the reform . He concluded by calling for the creation of the conditions necessary for the preparation of mathematicians and mathematics researchers who could serve as support for the reform in mathematics teaching . In that respect he recommended : increasing the number of candidates and improving selection procedures ; strengthening schools of mathematics in the universities , sending many students abroad for study ; and insuring adequate conditions when graduates of foreign universities returned to their countries of origin . In relation to the topic of the progress in Mathematics Teaching , four addresses were given . Three of them reported on the progress made in the reform of mathematics teaching in a few countries ( Spain , Chile and Brazil ) , and the fourth discussed activities of the OAS with respect to Mathematics . Professor Pedro Abellanas presented some of the progress in the reform of mathematics teaching in Spain . He mentioned holding annual meetings , since 1960 , with secondary school teachers and university professors , in which there were discussions on teaching modern mathematics . As a result , various studies were carried out and thus the program in the Licenciatura in Mathematics had been modified . He reflected on the importance of the teaching of secondary mathematics , especially in its formative aspects . He indicated that several courses had been organized for mathematics teachers which treated topics such as proportions , similarity , measurement , natural numbers , whole numbers , rational numbers , polynomials , irrational expressions , etc . Later he proposed a mathematics program for each year of secondary education . In his address , Professor César Abuauad presented some of the progress in mathematics in Chile . He mentioned some positive aspects such as : the wide diffusion of the recommendations from the Conference in Bogotá , the work of the SMSG group , and the close contacts with the " spirit of renewal in Europe " . He also provided a list of the steps that had been taken since 1962 [ vii ] . Professor Osvaldo Sangiorgi gave information on some of the progress in mathematics teaching in Brazil : more unity among the universities , institutes and other groups ; increased cooperation among university mathematicians and secondary school teachers ; creation of new mathematics departments in various universities ; increase in the number of teacher training centers ; extraordinary increase in the number of teachers taking in - service courses in mathematics ; increase in the number of secondary teachers with university degrees ; realization of congresses , colloquia , and other activities dedicated to the teaching of mathematics . In conclusion he presented the new program that was being developed for secondary schools in Brazil . Andrés Valeiras , representative from the OAS , presented the contributions of the OAS in improving the teaching of mathematics . The Department of Scientific Affairs increased its technical assistance activities to achieve the following objectives : a . Aid to Ministries of Education in their tasks of modernizing the curriculum . b . Aid to Ministries of Education and schools in offering training for in - service teachers and in modernizing the teacher training curriculum . c . Aid to encourage research [ viii ] . That report made it very clear that the OAS had participated significantly in the reform of mathematics in Latin America . Among the activities were the establishment of summer institutes , interchange of scientists , meetings , scholarships , studies on the teaching of science and engineering , and various publications . It is worthwhile to gave some details on what was developed : Scholarship Program . Scholarships for citizens of member nations for high level studies in other American nations . Programs of Direct Technical Assistance . Visits from expert consultants . Exchange Programs . Financing of visiting professors in universities in the member nations . Program of Integrated Projects . Initiatives planned to give training , technical assistance , equipment , etc . to institutions , universities , etc . in Latin America . Technical Cooperation Program . Training of personnel . Special Programs : Annual summer institutes in the USA . Summer institutes in Latin America . Regional meetings . The Study on the Teaching of Science and Engineering in Latin America . A Guide to Scientists and Scientific Institutions . Publications . In Block C , new curricula , as well as an analysis of the state of reform in each country were presented . In this context the following individuals related their experiences : Howard Fehr ( USA ) , Carlos Imaz ( Mexico ) , Erik Kristensen ( Denmark ) , Eugene Northrup of the Ford Foundation ( Turkey ) , Georges Papy ( Belgium ) , Andrés Revus ( France ) and Eduardo Suger Cofiño ( Guatemala ) . In each case there was talk about the way in which proposals for the implementation of modern mathematics at both the pre - university and university levels were being carried out . The diversity of the countries represented in the presentations denoted the interest in propagandizing the worldwide nature of such reform and the need to know how it was being carried out in other latitudes . In Block D , dedicated to the preparation of teachers ( achievements and difficulties in various countries ) , there was participation from Mariano García ( Puerto Rico ) , Martha María de Souza Dantas ( Brazil ) , Hans - Georg Steiner ( Germany ) , and Luis Santaló and Renato Völker ( Argentina ) . Here the particular experiences of each country were presented . NATIONAL REPORTS A second part of the Conference , which was very important to its objectives , was dedicated to reports from the various participating countries concerning the progress of reform . A total of 22 delegations presented their reports : Argentina , Bolivia , Brazil , Canada , Chile , Colombia , Costa Rica , Dominican Republic , Ecuador , El Salvador , Haiti , Jamaica , Mexico , Nicaragua , Panama , Paraguay , Peru , Puerto Rico , Trinidad and Tobago , United States , Uruguay , and Venezuela . It is interested to point out that a caution was given that the reports were " informal " in the sense that they were not given by officials from the governments , but were simply the appraisals of the participants of each country . Some countries showed more progress in the process than others . For example , from the reports of Argentina , Brazil , Canada , and the USA it is obvious that the process began with various aspects of reform , including profound changes in the contents of secondary and university mathematics programs , using new approaches to the pre - service and in - service teacher education . In other countries , such as Chile and Costa Rica , new mathematics programs were promoted in all secondary schools . In some other countries such programs were beginning to be used in just a few institutions as a pilot project , such as was the case in Ecuador . Thus , the majority of the countries reported making at least some attempts to introduce changes . Nevertheless , there were some countries , such as Bolivia , in which it had not been possible to implement any changes . In general , partial or total changes were carried out at the secondary level ; in some cases there were changes in teacher preparation programs ; and in many there had been training sessions for teachers . Something important : there was an effort in most countries to produce their own textbooks , following the guidelines for teaching modern mathematics in accordance with the directives of the First Conference . It should be mentioned , however , that the majority of the delegates talked about the problems that they had encountered . In general , those problems were common in most countries , such as the difficulty in pre - service and in - service teacher training , and the slight possibilities to carry out the reform with success ( at least in the short term ) in every country , because of a shortage of both human and economic resources . In many of the countries teacher preparation was deficient . The expansion of the educational system was such that in many of the countries many of the teachers that taught mathematics had an inadequate preparation , or , in many cases , none at all . It can be said that this was perhaps the main problem encountered in the reform process . THE CONCLUSIONS OF THE CONFERENCE One of the important parts of the conference was a section of conclusions in which goals were proposed for continuing the reform of mathematics teaching in the American countries . During the period from 1961 to 1966 the pro tempore committee that had been elected in the Bogotá Conference functioned as the executive committee of the Interamerican Committee on Mathematics Education ( IACME ) . That committee had some difficulties , mainly economic , in functioning efficiently . Those difficulties permitted the committee to meet only occasionally . Therefore in the Lima Conference some basic norms were proposed that would permit the Committee to function more efficiently . The norms that were approved in the closing session on the 12th of December of 1966 were : " A . The Inter - American Committee on Mathematical Education ( IACME ) originitating in the First Inter - American Conference on Mathematical Education , December 4 - 9 , 1961 , is a non - govenmental body affiliated with the International Union of Mathematicians through the International Commission on Mathematical Instruction . The purposes of the Committee are to serve as a technical organ in the sense of , and the scope of , the recommendations made at the Conference cited above and at the Second Inter - American Conference on Mathematical Education held at Lima , December 4 - 12 , 1966 . B . In accordance with the decisions of the Lima Conference , the composition of the Committee , until the next conference is held , shall be : Marshall H . Stone , U . S . A . , President Cesar Abuauad , Chile Ricardo Losada , Colombia Manuel Meda , Mexico Leopoldo Nachbin , Brazil Luis A . Santalo , Argentina Juan Jorge Schaffer , Uruguay Egardo Sevilla , Honduras Jose Tola A . , Peru The Committee will assign to its members the duties of vice president , secretary , and such other offices that are deemed necessary . Likewise it is given authority to designate replacements in cases of retirement . C . Committee membership will require annual minimum dues of $ 100 per country , paid by a body or organization which ( in the judgment of the Committee ) would be representative of the activities which they promote in the respective countries . D . The Committee will solicit the support of organizations and bodies , which by their character and goals , correspond to the objectives of the Committee and the activities which it advocates " [ ix ] . The recommendations were sent to the Ministries of Education , universities , and educational institutions in each country , as well as international organizations such as the OAS and UNESCO other institutions related to mathematics teaching and research . The recommendations were divided into five parts which are summarized below : I . Secondary school curriculum . Here topics were proposed globally for the curriculum . They are outlined below : For youths 12 to 15 years old : Sets , relations , whole numbers , binary operations , introduction of the axioms of geometry , introduction to rational and real numbers , vector space of the plane , coordinates , ways of representing functions , metric geometry of the plane , scalar product , analytic geometry in orthogonal bases , systems of linear equations . For youths 15 to 18 years old : study of real numbers , Euclidean space , orthogonal bases , Cauchy - Schwartz inequality , linear transformations of the plane , complex numbers , trigonometry , combinatoric analysis , the Euclidean algorithm , polynomials , some topological concepts , continuous functions , limits , sequences , derivatives , integration , special elementary functions , determinants , three - dimensional geometry , elementary probability and statistics . Also , the following observations were added about the programs : a ) Advisability of first experimenting in pilot courses . b ) Put the topics in an appropriate order . c ) The program was an academic secondary education and should be modified for technical and commercial schools . d ) It is necessary for primary schools to prepare students for this program . It was also proposed that studies be carried out in various countries to try to determine the results obtained in trials of the program , and that the programs be adapted for engineers and other applied fields . Other resolutions . II . The preparation of mathematics teachers for secondary schools and the first years of university . It was most important to solicit the collaboration of the universities in this process . Also it was requested that formal agreements of collaboration be arranged among universities and that there be efforts to prepare more and better teachers . III . In - service training of teachers . Courses and other professional development activities should be intensified and , to the extent possible , permanent teacher training centers should be established . IV . Preparation of textbooks and other bibliographic materials . Great efforts should be made to try to publish monographs , student textbooks , public information pamphlets , pedagogical bulletins , a Latin American journal . V . Various matters . IACME was charged with aiding in the formation of local committees in each country ; developing and disseminating a guide to Latin American institutions that offered high level programs in the field of mathematics ; organizing periodic national meetings ; organizing periodically national and regional colloquia to provide intensive courses on special topics ; convening seminars on mathematical topics and on problems with teaching , and in which short communications on research projects could be presented and discussed . National societies of mathematics , in which secondary and university teachers take part , should be organized in order to promote the development of mathematics . As can be deduced from the above summary , there was still interest in continuing to reform the teaching of mathematics in the American countries . There was also interest in continuing that reform along the same lines , that is , introducing " modern mathematics " into secondary education and teacher preparation programs . The recommendations are very clear in that sense . They are even more specific than the recommendations of the Bogotá Conference given that in this meeting there was even given , with a certain amount of detail , the topics that were to be taught in secondary schools . This Conference exhibited a fundamental difference with respect to the First . In the Bogotá Conference general ideas about modern mathematics were expressed , with an explanation of why it was important to introduce it into secondary schools and stressing the importance of involving all countries in the change . In some way modern mathematics was defined , its main topics were mentioned , as well as an explanation of the new topics were related . Finally , there was an attempt to convince the participants of the advantages of carrying out the reform . On the other hand , in the Lima Conference it was assumed that countries were already involved , in one way or another , in the reform and therefore reports were solicited . The addresses were on topics of a more operational nature , and not so much about the great ideas of the reform , but instead how certain processes were being carried out in places that had been able to advance the most , especially in that particularly difficult topic : the pre - service and in - service development of teachers . These differences , however , are quite logical if we keep in mind that they represent parts of the same process . MARSHALL STONE This brief description would not be complete without emphasizing the figure of Marshall Stone , the driving force behind the creation of IACME . Marshall Harvey Stone was born in New York on the 8th of April of 1903 . He was 16 when he entered Harvard and graduated summa cum laude in 1922 . Before being a professor at Harvard from 1933 to 1946 , he was a professor at Columbia ( 1925 - 1927 ) , Harvard ( 1929 - 1931 ) , Yale ( 1931 - 1933 ) and Stanford in the summer of 1933 . Although a Harvard graduate and professor , he is best known for having converted the Mathematics Department of the University of Chicago , as its Chair , into one of the main mathematical centers in the world . He achieved that by contracting famous mathematicians , such as Andre Weil , S . S . Chern , Antoni Zygmond , Saunders MacLane , and Adrian Albert [ x ] . Paul Halmos , Irving Seal , and Edwin Spanier [ xi ] were also contracted during the same period . According to Saunders MacLane , the Mathematics Department that Stone created was at that time " without a doubt the leading Mathematics Department in the country " [ xii ] , and probably , we should add , in the world . The scientific achievements of Stone were many . When he arrived in Chicago in 1946 , upon recommendation to the President of the University of Chicago by John von Neumann , he had already completed important works in various areas of mathematics : the spectral theory of adjoint operators in Hilbert space , and on the algebraic properties of boolean algebras in the study of rings of continuous functions . He is known for the famous Stone - Weierstrass Theorem , as well as for the Stone - Cech compactification . His most influential book was Linear Transformations in Hilbert Space and their Applications to Analysis . He was elected member of the National Academy of Sciences of the USA in 1938 , at the age of only 35 . He was President of the American Mathematical Society from 1943 - 1944 . Although an International Mathematical Union ( IMU ) had formally existed since the turn of the century , Stone renewed it , actually recreating it in the Rome Assembly in 1952 . Stone was the first President of the new Union from 1952 to 1954 . He was a member of the International Commission on Mathematical Instruction ( ICMI ) from 1959 to 1962 and of the International Council of Scientific Unions ( ICSU ) . Stone had a strong personality and exhibited an extraordinary charisma that permitted him to achieve his objectives in the University of Chicago , and , also exercise a powerful influence over the international mathematics community . It should be mentioned , especially , that Stone had a great liking for Latin America . Many students from Latin America directly benefitted from him ( among them , Prof . José Joaquin Trejos Fernández , who was President of Costa Rica from 1966 to 1970 ) [ xiii ] . The best indication of his appreciation of the region was , nevertheless , his decisive involvement in building and sustaining IACME during so many years ( as its President from 1961 to 1972 ) . Finally , it should be mentioned that Prof . Stone was very much influenced by the ideas in the research and teaching of the Bourbaki group [ xiv ] . He adopted many of the orientations of that group with respect to the axiomatic and abstract foundations of Mathematics and Mathematics Education . One indication of the close relationship between Stone and the Bourbaki group was the presence of in Chicago of Andre Weil , who was for many years the dominant figure of the group and one of the most brilliant mathematics researchers at the time . Weil was in Chicago from 1947 to 1958 . The strong reputation of Dr . Stone in the world mathematics community explains the international support that IACME had in its beginnings . In 1983 President Reagan presented Professor Stone with the most prestigious scientific award in that country : the National Medal of Science for his synthesis of analysis , algebra and topology . Professor Stone died on the 8th of January of 1989 in Madras , India . His imprint on the world of mathematics was profound and lasting , but , we should also emphasize that he had a very special impact in Latin America . IACME and the mathematics teachers of this region can never forget nor fail to recognize the invaluable support , so frank and unselfish , that Professor Stone gave us for the development of our discipline . DATA FROM THE FIRST CONFERENCE Given the importance of the first conference , it is interesting to take a look at some of the details of the program , the organization , and the sponsorship of the event .

Interview given by Zé Celso Martinez Correa Media : Rádio Cultura AM Reporter : Marilú Cabañas Date : January 24th , 2005 PRESENT SITUATION OF THE STADIUM THEATRE PROJECT Marilú : Zé Celso , we have been following the trajectory of your struggle with the Silvio Santos Group , and it has been - as far as I ' ve been able to see - a very exciting struggle , which have shown that you are a very persistent person , that you have guts , that you are fully committed in defending the Oficina Theatre . What has happened now - we have read something in the newspapers , what are the facts ? Have you already come to a satisfactory agreement , or is there still a way to go ? What is the situation today ? : It ' s a struggle on behalf of the Oficina and the Bixiga district , and it ' s also a fight against the thirst of property speculation which devastates the cities , above all a city like São Paulo , which is perhaps the city most severely devastated by property speculation . So it ' s a fight on behalf of the district and of the theatre which has an universal character . And this fight - with the visit of Silvio Santos , we could see that a big change has happened after 25 years , because now Silvio Santos was able to perceive things which the Group Silvio Santos has not been able to see for many years , even in audiences at courts on environmental issues . Silvio Santos was here and he saw the grandiosity of the theatre . He said he had never entered this space because he thought it was very small , and he was surprised to see how big it is , its height , its mobile roof . And he was surprised by the way he was welcomed . He showed an extraordinary interest . I couldexplain the project in clear terms to him and I feel he has understood its dimensions , not only regarding the district , but also the international dimensions of the project . After that they hired these architects , who are very good indeed , they have worked with Lina [ Lina Bo Bardi she was an internationally famous architect and died a few years ago ] . One of them is Marcelo Suzuki , who had made the first drawings of the stadium theatre together with Lina , before Silvio Santos even began to think of buying the Oficina . Well , they started to set up the project . They are working together with the Silvio Santos Group and obviously now there is the strong pressure of speculation , because each millimetre and each centimetre has to be discussed in terms of profitability , a short - term profitability . I think this project will become either a rather conventional project or a project of great importance for the whole world . It not only will be a postal card for the city , but also a place in the world which will prove that it ' s possible to overcome determinations and fatalities imposed on big cities by property speculation . And it could really become an example of beauty , a point of attraction in the world . But considering the first meeting I had last week , it may also remain a mediocre thing . This meeting has been recorded and we will put it in our Web site . And we want to open up our Web site to discussions . It was a meeting of heated discussions , and right from the beginning there were many things I didn t agree with , and others I did agree with . And it ended with the unanimous decision to set up a kind of council . We gathered people like Modesto Carvalhosa , our lawyer , and Contardo Calligaris , and the whole Oficina ensemble , including Bete Milan . The other day we hadthe participation of Eduardo Suplicy [ Senator of the Brazilian Republic ] . All these people are following up our project , and in the end it was unanimously decided to submit the project to the municipality for approval on January 31th . But it s going to be only an approval of the volumetric analysis , not a definitive approval . I decided to agree based on trust - trust in two things : first , in the feeling of mutual confidence which Silvio Santos has transmitted to me and the understanding I think he now has got for the project , and second , in the support the project has gained from a good part of the public opinion . THE STRUGGLE WITH THE LOGIC OF THE CAPITAL THE CREATION OF A NEW CAPITAL Presently there are discussions going on within the public opinion . First , there were some news in the press , one article in the Estado de São Paulo and two articles in the Folha de São Paulo . At Folha , the subject was published on the cover , together with a drawing , and this has led to a huge polemic . In a sense I find this polemic very interesting . There is something ingenuous about it , on the part of those who are not in midst of the fire , who are not involved in the fighting . It s a harsher fight than if you were in Israel or in Palestine . The fight with the capital is very difficult not in regard to the people , to the capitalists , but in regard to the own logic of the capital . It s very hard for you to convince others that the capital is not so important from the economic point of view and in terms of immediate profitability important is what the capital will mean in the long run . I have the impression that if things turn out the way I intend , as the Oficina intends , as Lina intended , this will have an importance as great as the Uffizi museum of Florence had the Uffizi museum , which means the museum of the oficina [ workshop in Portuguese ] and which was given to Prince Cosimo by a grand - grand - grand - grand - mother of Silvio Santos , from the Abravanel family , and which is considered to be one of the most importantmuseums of the world . This means capital , tourism , profitability , knowledge . It s a form of capital that is less immediate , but which in the end produces a much bigger profit . Here lies the problem we are dealing with . Evidently it was extraordinary for me to see the absolute change of quality after 25 years , that is , during all these years the Silvio Santos Group presented a series of projects , one of them transferring parts of the land plot to the Oficina . But those were projects to which I could not give way to . Even if sometimes the architects would tell me : you should give way to it because they are giving you two times the space of the theatre , but I did not agree to it because it didn t correspond to the stadium theatre idea . CHARACTERISTICS OF THE PRESENT PROJECT This project has an interesting feature . A stone will be cast in the middle , so that the theatre will no longer look like a shopping centre stand ; rather , it will become the centre , the square , the Mecca , where the architectural happening takes place . This stone is still being shaped by Marcelo Suzuki . And Lina always talked of terreiro soil [ terreiro is an outdoor place where rituals of candomblé or umbanda are practised ] , she talked of a street , of a Milan theatre gallery leading to Silvio Santos catacomb . Even with this idea of a Silvio Santos catacomb she imagined a stadium full of holes , just as the Coliseum , because she liked holes , as for example the holes of the SESC [ theatre owned by the Social Service for Trade ] , which she nicknamed Beirut and which today she would call the holes of Falluja , Iraq . I want it to be a completely holed stone . The stone is being made of cement , clay , earth , but it gives the idea of a stone , which I am very fond of because it makes me think ofthe Greek theatre and the first theatre stadiums , where the grandstands were carved from stone . The Greek theatre was carved in stone and this accounted for the good sound quality . That is more or less what will happen . However , for the time being there are no holes in the drawing . For the time being - and that is something I think is even worse and which was rightly noted by Mariana well , a stadium theatre has to be open to the four corners of the city , because it is a crossroads . It has to have an opening to the Santo Amaro street , another one to the Abolição street , one to the Jaceguai street and the other to the Japurá street , because it s a public monument after all . This project has also something of an Italian stage , of a church saint with no back . I think that such a monument has to have buttocks , it has to have a whole body , it must be visible from the four corners , it cannot be something opened up to just one side . So I fight for this , I fight for the shopping centre itself to be opened to the four corners of the city . And foremost I fight for this theatre to have its breath open to the four corners of the city . We didn t conquered the Abolição street yet , that means , in the present project of the shopping centre there is no access to the theatre trough the Abolição street . As a matter of fact , I consider this stadium theatre as the DNA of other stadium theatres which will be build . And the DNA of the stadium theatre is always very important , because it has to contain the qualities of all which will come in future . In reality , I wanted a stadium of 15 thousand seats , but this one will have thousand seats . This doesn ' t really upset me , because I know it s a process , something that needs a practical exercise and has to be improved to go on growing . I hope this idea willexpand with the expansion of the theatre itself , in proportion to its relationship to music , to dance , and to the digital revolution , and with the ascent of the Brazilian people , of this culture , which is a world - wide culture , the culture of race mixture . This kind of theatre will expand not only in Brazil , but in the world . So much that we want to see here a place where a world - wide biennial festival - at least - will be performed . But the theatre isn ' t ready yet . They had a difficult fight to achieve this space , so that the theatre for example would have its own sky , that it would not be an insertion in the body of a shopping centre . Well , the architects came along , exhausted by this fight , and presented that , but I still feel the whole shopping centre isgiving a too tight embrace . There has to be more room . Another thing is that they think that we are still in discussions . So I want that the West side wall of the theatre , which has a big window , opens up through doors . That it opens up directly to the stadium , and that the Oficina theatre becomes what the Greek would call " skene " , which is the stage place in the Greek theatre , where the gods and the protagonists appeared . And then there is a circle , which is the orchestra , where the choir is located . I want this theatre as a Greek theatre , with level curves , I want it swinging - a swaying theatre , as if it were a bass - drum - drome [ joke with the word sambódromo , where the samba schools parade during Carnival ] , because we are going to use both the spaces ofthe orchestra as well as of the scene to make the productions . It will be a theatre to act on through and through , as if it had many hills , many segments . That is why I first thought of calling Oscar Niemeyer . I wanted Niemeyer because of the curves , because I wanted a swaying Greek theatre . We haven t come to that yet . This all Marcelo Suzuki will put in detail . Another aspect is : in the first version , there were two domes , one located just right above the stage , which gave not the idea of a stadium , because if you walk in a stadium , the first thing you see is the vastness , you see the roundness , you see everybody , you see the open sky . Sure , if it ' s raining , you ll close it . Today there is a beautiful highly advanced technology - because of the Olympic Games - and I want the theatre that way . In this drawing there is still a small dome and another one , which in reality is designed for a small theatre of 100 seats , quite nice , with a view to all of the city . But I think this can be done covering a part of the stadium - as there are those places which are more expensive , which stay protected from the sun . The best is really the visibility , the open sky . With a dome which opens and closes and which at the same time is a projection screen , which may be used with all the inventions provided by the digital revolution . A dome which even on sunny days may be easily closed , as does the mobile roof here at the stage of the Oficina , so that one can make projections on it . THE MANAGEMENT - A QUESTION TO BE DEFINED SOONEST A question I think is of foremost importance and in a way is not mentioned , but which has to be made explicit as soon as possible is the management . I want this theatre to be managed by us from the Uzyna Uzona , with the advice of the whole Braziliantheatre . A council with the major names of the Brazilian theatre and with the objective to serve all Brazilian ensembles who want to make stadium theatre at this place . That means , it s not a place to make shows as you have in the Moema district . It s a place for a theatre which has developed a lot in the sixties but which has suffered a very strong repression and could not follow its natural way . This all we would already have in Brazil if it weren ' t for the AI - 5 [ Institutional Act No . 5 which revoked civil and political rights during the military dictatorship ] . So it s necessary to recover the space which belongs to the theatre . Not a place for a boring big theatre , but for a theatre which works with music , dance , with all the space , with the circus , withanimals , with the trapeze , with the movies and with the theatre . I think this is the tendency of the total theatre . OK , the shopping centre is managed by the Silvio Santos Group , it has a commercial character . But the stadium theatre has to be managed bythe Uzyna Uzona , with a council of the most expressive names of the Brazilian theatre and culture , and it should be used by all Brazilian and international ensembles who wish to make stadium theatre . It has to be a place that privileges the theatre . Occasionally you may stage a show or something similar . But it s not a place to stage a SBT [ Sistema Brasileiro de Televisão ] show . It s not a place for sales , it s a place for creation , which I believe will have a great economic value , and a great financial value as well . But it s not a place for business to business . At least , it has to be a place for show - business . That means , the show , the theatre , the spectacle is more important than the business . It ' s it which will make the business . I think we are doing such a precious thing with " Os Sertões " that I believe in an absolutely crazy thing : I begin to see that it ' s possible for us to make a revolution , and that someday - I don ' t know , I think first the Bush government has to fall - we will be presenting it on Broadway . I have the impression that we are creating a Brazilian musical which is completely different from the American musical but very strong and of great interest for the world . And this place here will contribute a lot for the growing of this Brazilianmusical . You know that when a musical succeeds in the United States it ' s an investment . Fortunes are invested in it and it has an enormous economic value . I believe that theatre produces this economic value . You just need to have the conditions . Therefore , this place has to be managed in an unconventional way . There has to be a management where the cultural aspect is above the immediate profit concern . This is something I have to seriously discuss with Silvio Santos . Because if this doesn ' t happen , it s going to be terrible . There will be shows all the time . Certainly we will work for a strong acoustic isolation between one stage and the other , so that sometimes we may perform on the two places simultaneously . But at the place they have put a series of trees in the middle . Only then the stadium begins . There is a separation . They say that we are still in discussions , but in my opinion this is a piece of work which cannot be build on talks , it has to be build on a common desire to do something really strong . Beginning by the name , stadium theatre - which was created by Oswald de Andrade and which was rediscovered by the Teatro Oficina - clearly the concept has always been an extension of the Oficina . A history of 25 years is there to prove this . You can ' t isolate one thing from the other . I don ' t agree with this . So much that on Sunday , which is my day off , I will stay home writing a text about the elements which I don ' t agree with and about the elements which I have to fight for . THE SPECIFIC CULTURES OF THE BIXIGA DISTRICT AND BRAZIL ITS IMPORTANCE FOR THE GLOBALIZED WORLD OF TODAY Marilú : You mean it ' s a process which still continues ? Zé Celso : It ' s a process , but I believe it has already been achieved . I think this has not yet been understood by the financial executives , who have understanding difficulties . But I ' m absolutely sure that it has been understood by Silvio Santos , and that ' s why I make a point of meeting Silvio Santos again , so that we may talk about the management question . And that he comes forward to his executive team and declares : Be informed that the management belongs to Uzyna Uzona . This is for the Brazilian theatre , it ' s for the international theatre . It ' s only for the theatre . Sometimes it will have an utilization which you executives won ' t understand from the economic point of view , as if this were about a factory . It ' s not . It ' s about something different , it ' s about creation . It ' s about another way of thinking . Otherwise it has no value , it won ' t mean a damn thing . Otherwise you won ' t have there , in that centre , a liberty of another quality than that which exists in the commerce surrounding it . And this liberty there in the centre will communicate - through the streets - with the other liberties for which I continue fighting for , the liberties of the small businesses of the Bixiga district . It ' s OK that there are the big businesses , but these mustn ' t necessarily liquidate the small ones . The street vendors are there to prove this , and not only them - you can seeit all over the world , the bakeries , the bistros in Paris , the specific charm of each place . For example here , right ahead , there is a marvellous Italian restaurant owned by Concheta , who is a beautiful woman , daughter of the founder of the Bixiga districtand who has two daughters who work in theatre - she has a very cosy and delicious restaurant . The shopping centre will bring along those franchised restaurants , those chain businesses of everything - there is a consumer public interested in this . But in our globalized world there is a growing interest for specific things , for the possibility to go to that one place which has a particular smell , a particular taste , the possibility to eat that particular delicious food ; to go and fetch that clothing which that particular dressmaker knows how to make . All this should not get lost . This theatre represents this all . This theatre is to be as if it were an assembly . By the way , it may have this use . It may be used for assemblies by the inhabitants of Bixiga who want to work on behalf of their district in fact this will be inevitable , it ' s an agorá [ the marketplace of ancient Greek cities ] . This is of utmost importance . And it has to be understood as follows : in the midst of the shopping centre , there is an islandwhich communicates - through various bridges - with this flourishing Bixiga , with all this wonderful people who mustn ' t be expelled from here . It s obvious that the people who live in the street have to occupy houses and buildings which exist here . They have to lead a decent life , there is no sense in having these people living in the street . There aren ' t too many of them , this problem is perfectly soluble . It ' s a problem which the occupation movement can solve , together with the municipality administration , to find an occupation for these people . It ' s absurd to see the Bixiga as a district with people living in the streets , because it s a historical district with traditions , a bohemian district with a cultural life , where you can live an artists life . This district doesn t have to bear this . There are very few street people , they could perfectly be given a home , and it ' s also possible to give them the opportunity to learning . THE POPULAR UNIVERSITY OF BRAZILIAN ORGIASTIC CULTURE One of the big losses wasthat of the synagogue . I wanted very much to make an university of the synagogue , but they have made an exchange with the Jewish people to move the synagogue to another place , and they are going to take the stained glass windows with them , which in my opinion are an important part the axé of the synagogue [ axé designates the magical foundation and the sacred objects of candomblé sanctuaries ] . Sure , the axé of the place will continue to exist and I would love to make an university at this place , but there is this decision of the Jewish community itself . Therefore I want Silvio Santos to build a bridge to another building he s got he owns a lot of buildings there in order to install a school , a popular university of arts . An university of the Brazilian popular culture of mixed race . They tell me not to say this word , but I will do it : orgiastic . Because I use the word orgiastic not only in the sense of free sexuality , of free love , but also in the sense of mixing virtual technology with the worldtechnology which is the theatre , the mixing of everything with everything . In this sense I employ orgy . But that doesn t mean that I don t employ it in the other sense , because the Oficina theatre has a great importance in the fight for sexual liberty , which today has turned into a political phenomenon in the world after the polemic created by gay marriage . Bush has gained a victory , and the world continues to struggle . In the Big Brother show there was that moment in which the guy assumed he was gay , and people demanded him to stay in the programme . So he continues in the show . It s a political subject . The erotic liberty of each person is not only to be respected , it s also to be encouraged . Because these people have grown up in a repressive society , so this work towards an erotic promotion in life is a political task of relevance . It s embedded in this mixed race culture and may lead to a revolution all over the world . It s not embedded in the capitalist culture , which culturally is very fragile ; it s moralist , it s puritan , it s excluding . What I mean is that the culture , the cinema , the literature of capitalism above all that of the North American capitalism - is made of nice heroes and bad characters , and there are always the chosen ones . It s an uncouth culture compared to this mixed race culture , for example the world music , which is known all over the world , and which in fact is an anthropophagic [ cannibal - like ] culture , it s a culture of mixture , of liberty . All in all , it s the total liberty of the people worldwide . A liberty that begins with the individual . Well , what we want to teach in this university has its origin in love , in the libido , beginning with the vowels , from a , e , i , u , óoooo because ó is more open , and the purpose of life is pleasure . So it will be an university which will teach all techniques necessary to the art of theatre . It s an university for the creation of a civilisation , a contribution to create a civilisation . Because the stadium can t be understood if there isn t a school to prepare people to exercise it , above all the common people , who are more close to the languages of the stadium theatre . People who are more likely to develop themselves in the circus , in dance , in the rituals of popular religions , as " umbanda and candomblé , and also carnival . That is to say , the music of it all . So I want a popular university , because I believe the strength both of the Oficina theatre as well as of its projection upon the stadium theatre are moments of the foremost importance . THE IMPORTANCE OF PUBLIC OPINION FOR THE IMPLEMENTATION OF THE PROJECT That s why I defend this project , because this is the moment of change , the moment to go out on the streets and to come to the apotheosis , to come to the circle , to the place where you can really found again the Brazilian popular theatre , a theatre that s musical , danceable , erotic , visual , plastic , funny , circus - like , and which will attract huge multitudes . These all are things which have been very clearly in my mind for 25 years now and which - as I see - the architects , urged by financial speculations , still weren ' t able to solve . I see the need for pressure on the part of public opinion . This is why we ll open our Web site for debate . This is not really a means of pressure , rather it ' s an ideological contribution , a creative and inventive contribution . That ' s something which never existed before . It ' s nice , because people have ideas , people know about things , people want things . For example this girl , she expressed herself - Ihave been receiving news through Orkut that people are gossiping a lot , saying that I ' m a traitor , that I ' ve given up everything and so forth . But it ' s nothing of that kind , it ' s a process , in which we have already had a big victory with this visit of Silvio Santos . I wouldn ' t have achieved anything if I had dealt only with the people of the capital , because I think what changes things are the people . The structures are there to be changed by people , they are not there to enslave people . So the man who already is above , who has his neck outside the structure , as Silvio Santos does , has given the order to demolish a building because this would look better . I found this attitude just wonderful . The group was scandalised . I believe in him , I trust he will understand all the significance of this , all the international grandiosity which will last for ever and which we are capable to give . THE PEOPLE OF THE BIXIGA DISTRICT This place mustn ' t become a mediocre place . The calculation has to have some more " reais " , some more dollars . The reward will come later , in form of many more dollars , many more euros . It may become an international shopping centre of international interest , because such a popular district begins to have an international interest , as it becomesan island which will serve as orientation for the whole world , which will allow it to expand itself in this sea which is the common people . And this people of the Bixiga district is a great people , it ' s a wholly mixed people . To have the [ samba school ] Vai - Vai is a luxury , that African mix , all these people drinking , sniffing , smoking , talking , singing , dancing . I mean , it ' s an ecological thing ; humanity needs such a kind of space . For millenniums humanity has been celebrating itself in liberty . So this joyful thing which exists in the Vai - Vai and in this district , this people that is a mixture of Italian and black people with everything and with the people from the Northeast region results in people you can talk to and who go to this theatre . The Bixigão project was a revolution in this district and has put us in direct contact with these wonderful people . They are not of the kind of the medium class " paulista " , of the inhabitant of São Paulo who is framed in the machine , who closes the windows of his car , who doesn ' t want to talk to anybody , who thinks the poor have to be massacred , who thinks the poor are no issue . They are not like the imbecile paulistas , these poker face people . They are people who are a heritage of mankind . So this is a thing which has to be understood and which is linked with the whole . RE - DESIGNATION OF THE MINHOCÃO VIADUCT There is still another issue to be added , regarding the Minhocão viaduct . There is a possibility , which has already been planned in the project of Paulo Mendesda Rocha and which Marcelo Ferraz will be able to adapt and which is a very good idea , that is to cover the Minhocão viaduct with earth and to build a small amphitheatre under the Minhocão . This place could simultaneously be the dressing room for animals , for horses and elephants . I have seen a photograph of Elvira Pagã on the back of an elephant . So it would be possible for an elephant to cross this place and enter the stadium theatre ; therefore there must be a dressing room for it . INFORMATION TOWER AND PRODUCTION TOWER And on the two pieces of land which belong to the municipality there should be a production house with a bar , where you can find pingas [ white rum ] from all places in the world , and on the neighbouring piece of landan archive . I am very engaged in the struggle for the creation of an archive , I am looking for subsidies to begin immediately to set up a data bank , to make available what the Oficina has in store and which is of universal interest . It s a crime to have everything so locked up . There is not an easy access to it because the material is not organised . I m trying to raise funds for this , but we need to define the place and I want it to be in one of the towers Paulo Mendes da Rocha has visualised and Marcelo Ferraz could adapt and which Silvio Santos could sponsor as a whole , so that it becomes a really strong thing . REVOLUTION INSIDE THE CAPITALISM GILBERTO GIL , BRAZIL S MOST IMPORTANT MINISTER If it is to become a mediocre thing , I don t want it . I have agreed to this bureaucratic thing because I believe in the very good relationship with Silvio Santos . There is also a very good relationship with the architects , and the relationship with the people of the financial group has been good and is still improving . Nevertheless they still believe that they have to think according to the immediate profit machinery . It is as if they had a helmet , a Matrix over their heads . But even this people may do without this Matrix and begin to think in longer terms , because Brazil is growing and it will be a rich nation . And it won t grow with a mentality of excessive and stingy exploration . It s necessary to have another kind of capitalism here in Brazil : a revolution within capitalism itself . The other day , a friend of mine , Monique , said that everybody should become rich in order to put an end to capitalism . Everybody wants to get rich , but the logic of capitalism allows this to happen only to a few . And those who get rich become captives . I heard that those big bankers in Switzerland who own huge fortunes don t know what to do with their money ; they dress in blue jeans and do nothing , they sit together looking at each other because they don t have anything to do with their money . Well , they invest it in the structure , while we are living in an era in which humanity could be much more happier . It s not an utopia ; humanity doesn t need wars , doesn t has to be hungry . But it s a question of change in mentality . I think we are in a special moment , because of the culture , because of this stadium theatre , because of the man Silvio Santos , because of what Oficina is and because of the public which Oficina has and who is discussing the subject . We are living a special moment , having Gilberto Gil as Culture Minister , who I believe is the best Culture Minister of the world I doubt there is another culture minister with such a high cultural level as Gilberto Gil has , be it in the USA , in France , in Israel , in Japan . I m sure there isn t . Well , this all is being wonderful for Brazil . Just yesterday he was saying in an interview that 10 % of the Brazilian GNP comes from the cultural sector . That culture is already a wealth factor and is a creative industry . I think this is very good . There has to be a great investment in creative industries . We presently have as Culture Minister an Oswaldian [ Oswald de Andrade ( 1890 - 1954 ) , author of the Anthropophagist Manifesto of 1928 ] , a tropicalist [ Gilberto Gil is one of the founders of the cultural and musical movement Tropicalismo from the late sixties and seventies ] who is the most important minister of the Lula government ; then comes Celso Amorim [ Foreign Minister ] , but the foremost minister is Gilberto Gil . Brazil is now living a very important moment of cultural awakening . And this cultural and economic awakening of the Brazilian culture will allow a change in the vision of the capitalist mind conditioned to pay debts , to profit , to enslave . I think the major form of slavery is if you have to live to pay debts and interest . I think it s a shame for humanity . Also the impediment to the liberation of drugs is a shame , as is the trade with slaves . And culture emerges as an enormous power to make a revolution in society . I believe that only this can stop the wars in Iraq , in Afghanistan , and now in Iran . That man wants to invade Iran . It s just crazy . And only through a total cultural experience , not only cerebral , but through the experience of the body , the own experiences , the experience of another dimension of the individual human body and ofthe collective human body , - all of which will be made possible by the stadium - this revolution can be achieved . THE OFICINA WEB SITE Marilú : How about the Web site ? Zé : We have a Web site which is not spectacularly beautiful because we are learning how to make a Web site . Incidentally the guy which is the best Web site designer in the USA and who makes a Web site on movies has said that his Web site is not fabulous or ostentatious because it s a site of content . So that s what we are working for . Our Web site is always updated , it brings the news of the day , the reports on the rehearsals and musical scenes ; it has a kind of TV and radio - the Uzyna Uzona which will soon show a report of the day on which the model of the project has been presented - this report is still being edited . The Web site will be open to everyone who wants to contribute to the discussions . We ll open the site very soon , I don t know very much about Web sites , but I will ask them to open the site today because of the discussions which are being made at Orkut . This is of big relevance to us , to the Silvio Santos Group and to Silvio Santos himself . Because it s an opinion poll , and the discussions about the stadium theatre arouse big interest . And it s a new thing , it s a first voyage , there has never been something like it in the contemporary world . There has been something like it in ancient history , and it has to be thought of in a collective way . Please note , it s teatroficina with only one o , dot com . dot br . Kisses to everybody . Translated by Angelika Kohnke

Journal of Health , Population and Nutrition , Vol . 23 , No . 3 , Sept , 2005 , pp . 207 - 214 Perceptions of Growth Monitoring and Promotion among an International Panel of District Medical Officers Dominique Roberfroid ; Pierre Lefèvre ; Tom Hoerée ; Patrick Kolsteren ; Department of Public Health , Nutrition Unit , Institute of Tropical Medicine , 2000 Antwerp , Belgium Correspondence and reprint requests should be addressed to : Dr . D . Roberfroid , Nutrition Unit , Institute of Tropical Medicine , Nationalestraat 155 , 2000 Antwerp , Belgium , Email : droberfroid @ itg . be Fax : 32 - 3 - 247 . 65 . 43 Code Number : hn05026 ABSTRACT The growth chart has been proposed as an educational tool to make the child ' s growth visible to both health workers and caregivers and to enhance communication between them . In the case of growth faltering , this would trigger timely corrective measures . Although the relevance of growth monitoring and promotion ( GMP ) has often been questioned in the literature , opinions of District Medical Officers responsible for local implementation of GMP are unknown . The aim of this qualitative research was to explore the perceptions and difficulties of an international panel of District Medical Officers regarding GMP . As an exploratory study , in - depth interviews of an international panel of District Medical Officers ( n = 19 ) were conducted . Data were coded using the QSR Nudist 5 . 0 software . A discrepancy between intended purposes and practice of GMP was detected at two levels . First , lack of participation of care - givers was reported . Second , the District Medical Officers expressed a restrictive interpretation of the concept of growth monitoring . The communication with parents was never reported as a means or a result of GMP , neither as an evaluation criterion of programme efficiency . The growth chart was mainly considered a tool intended to be used by health services for the purpose of diagnosis . This two - fold discrepancy between the intention of international policy - planners and practice of local programme implementers could be a crucial factor affecting the performance of GMP . More emphasis should be put on social communication and involvement of caregivers . Key words : Child growth ; Growth charts ; Child nutritional status ; Perceptions ; Developing countries Introduction The World Health Organization ( WHO ) defines growth monitoring and promotion ( GMP ) as a nutrition intervention that measures and charts the weight of children and uses this information to counsel parents so that they take actions to improve child growth ( 1 ) . The growth chart is , thus , an educational tool that helps both health workers and mothers to visualize child growth ( 2 ) . When growth is adequate , parents should be encouraged and advised on how to preserve that pattern . In the reverse situation , growth faltering can be detected long before any easily - observable sign or symptom of malnutrition becomes evident . This should then trigger a reaction from health workers and caregivers to take corrective measures so that the child recovers . This recovery is visualized by an upward growth trajectory ( 3 - 5 ) . Central to all this is that parents are expected to appropriate the chart as a tool to evaluate and understand the growth and development of their children . Malnutrition is , in part , responsible for high rates of mortality of children , aged less than five years , as observed in developing countries ( 6 , 7 ) . GMP programmes have , therefore , the potential to contribute to achieving the goals of the child survival and development revolution ( 2 , 8 ) . Several authors have pointed out that , despite important international efforts , there is little evidence that these goals are being achieved ( 3 , 9 - 11 ) . Explanations put forward relate to the poor performance of the growth chart as a measurement tool , the insufficient or inadequate training and supervision of basic health workers ( 12 ) , and the poor understanding of the chart by parents , particularly those with low school achievement ( 13 - 16 ) . In the whole debate on growth monitoring , the way mothers understand and use the growth chart has received much attention . However , how health managers , such as District Medical Officers who organize and supervise the health - system activities , view and appreciate growth monitoring has , to our knowledge , never been addressed . The aim of this qualitative exploratory study was , therefore , to document the perceptions of these professionals on GMP , their expectations of the programme , and the difficulties they face in its implementation . Materials and Methods During October - December 2000 , an anthropologist with a medical background interviewed 19 District Medical Officers from South America , Europe , Africa , and Asia ( Table 1 ) . They were randomly selected from a class beginning a masters programme in public health in Antwerp , Belgium . All the interviewees had several years of experience as District Medical Officers . In - depth interviews were held in French and English and lasted 45 - 75 minutes . A series of structured prompting questions was used ( Table 2 ) . All interviews were tape - recorded with permission of respondents and fully transcribed . A secretary made transcripts , and the interviewer checked against the recordings to ensure ac - curacy . Data were coded using the QSR Nudist 5 . 0 software ( QSR International Pty . Ltd . , Melbourne , Australia . 2000 ) to facilitate cross - indexing . Codes were derived from the research themes ( or research questions ) and from themes emerging from data . The interviewer analyzed the data and a sociologist cross - checked to ensure their reliability ( 17 , 18 ) . The data provided by the interviewees were treated as social constructs , i . e . as displays of perceptions , belief systems , or assumptions , not as presentation of versions of ' reality ' . The transcripts were analyzed for the constructs the participants referred to , to articulate their understanding and experience of GMP . Results The mean age of the 19 interviewees was 37 years . Males ( 16 of 19 ) and sub - Saharan Africans ( 10 of 19 ) were over - represented , but those proportions corresponded with the student population of that year . A large variety of experiences and opinions , reflecting the international pattern of the panel , were collected . The interviewees originated from settings where nutritional issues , malnutrition rates , literacy rates , health policy , organization , and resources of health services differed considerably ( Table 1 ) . They also had very different personal and professional histories , although all had been serving , or had served , as District Medical Officers for several years . Despite this variety of backgrounds , the interviewees were quite homogeneous in appreciating the poor effectiveness of growth monitoring . The majority expressed the opinion that , in their experience , GMP did not work the way it ought to . The interviewees emphasized a gap between intended purposes and practice . An interviewee argued , " In theory , it is a good tool , it is very interesting , but , in practice , it is different . It is , maybe , more a tool for me than for the mother to do evaluations , statistics . " ( 15 : 168 - 70 * [ * indicate transcript no . and lines respectively ] ) . Another one added : " Of course , we did it [ GMP ] . There are many things done only by routine . It was there , so we kept it on , maybe , due to the lack of time to find a new strategy . " ( 6 : 140 - 1 ) . One even said , " That is nearly utopian ! " ( 5 : 293 ) . This discrepancy between purpose and practice of GMP was identified at two levels in the narrative of the participants : first , in their personal experiences and , second , in the expression of their understandings and perceptions of GMP . Personal experiences The interviewees evoked operational difficulties in the implementation of GMP . The most consistently - reported reason was irregular attendance of mothers at weighing sessions after completion of the vaccination schedule . The participants explained this by a lack of interest of mothers in programmes which do not display technical acts and visible effects . Mothers were said to use their own criteria to evaluate the growth and health of their children and to visit health services only for obvious ill - ness of their children . " Because , in general , mothers when they think that their children are in good health , they run , they gambol , they [ mothers ] do not see the necessity to bring the children only for parameter measurements . " ( 5 : 30 - 2 ) . " Ideally , it is an objective of prevention . But , in practice , it is as I told you . For health agents as for beneficiaries , it is rather when there is a problem . " ( 1 : 622 - 3 ) . The weak capacity of awareness campaigns for motivating parents to adhere to the programme was also underlined . The District Medical Officers attributed this failure partly to the low motivation of health workers for performing GMP activities . Low competence and heavy workload of field staff were presented as obstacles to GMP [ This was particularly mentioned in sub - Saharan countries where the responsibility of GMP is most of the time taken by basic health workers ] , although it was not clear why these two limitations should have affected GMP more particularly than other health activities . Other limitations of the highlighted growth monitoring related to the capacity of response of parents to the information provided . The District Medical Officers frequently stated that parents failed to understand the growth chart , mainly because they are illiterate or not educated . One interviewee explained : " Because , in our country , they are illiterate . They do not understand too much what is written on it [ the growth chart ] , it is not too much their concern . " ( 1 : 341 ) . Other interviewees were more subtle in their explanations : " They [ health agents ] also think that it is not that important that mothers understand , because the understanding point is quite low , you see . " ( 16 : 58 - 61 ) . " But I am wondering if she [ the mother ] really understands . Because it is simple , but sometimes nurses also have difficulties to fill in the growth chart . " ( 15 : 209 - 10 ) . The District Medical Officers also related the lack of response to the messages to low food accessibility and , thus , limited applicability of nutrition advice in some contexts , as reported in the following quote : " But they know it , they know that the child does not eat very well because it is the same meal every day . What are you going to propose ? You are not going to propose anything because she won ' t have the capacity to apply it . This is a problem . Thus , I think that they are right not to come to be repeated the same thing again and again . " ( 7 : 515 - 19 ) . Understanding and perceptions of GMP The above results show that the explanations provided for the perceived malfunction of GMP relate much to operational problems and to the demand of the population for curative and technical , but not promotional , ser - vices . The same opposition between technical ( visible , curative ) and intuitive ( invisible , preventive , or promotional ) aspects of care can be found in the narrative of the interviewees . Actually , the District Medical Officers endorsed consciously or implicitly the primacy of technical aspects over promotion of health and growth . One interviewee gave this revealing pun : " A malnourished one is not going to contaminate somebody else . He does not carry much weight in the society . " ( 9 : 389 ) . Another interviewee added : " Yes , I always said that the mother has not come to learn that her child gained weight or not . She has come for you to do something else . You do the vaccinations . " ( 18 : 201 - 3 ) . About criteria used by mothers to evaluate the growth of their children , the District Medical Officers consistently considered them subjective , approximate , and intuitive . However , most District Medical Officers were unable to describe what these criteria consisted of . One interviewee , for instance , said , " Their criteria give an idea but this is not something that is very acute . We are giving GMP criteria in a scientific way , they [ the parents ] are not up to that point , they have a very general idea . " ( 17 : 356 - 7 ) . The ambiguity is obvious in this interviewee : " Thus , I think that mother ' s perception is a criterion that cannot be really defined , but I believe it is important even if it is intuitive . " ( 5 : 176 - 77 ) . Thus , mothers are said to come mainly for vaccinations because this is part of the technical sphere under the responsibility of health services . For the majority of District Medical Officers , communication was not a primary objective . Some interviewees even tended to consider communication as a ' no - act ' , while weighing was considered as the technical justification of their presence in GMP . As summarized by one interviewee : " Finally , to weigh , as I said previously , demonstrates to the mother that an act is done . Second , it is also an act , not a medical one , but an act made by the health agents that can encourage the mother to come back the next time . " ( 5 : 132 - 5 ) . The same interviewee went on talking about village volunteers : " Their task is much more to gather mothers and to be willing to listen to them but they do not act . " ( 5 : 344 - 5 ) . From this perspective , communication with parents using the growth curve is secondary . It was never either reported as an objective of GMP , or as a criterion to evaluate the programme efficiency . The growth chart was considered to have mainly diagnostic purposes and used for the health information system . For most interviewees , the growth chart was given to caregivers for preservation and transfer of information on vaccinations and diseases , not for motivating parents to monitor the child ' s growth : " I find it useful to not lose information . But if there were another means , better to get the information , I think we can let it [ the health card ] down . " ( 12 : 225 - 7 ) . The following quote is even more direct : " The objective is not to discuss with parents , to educate them but to determine if the child is malnourished or not . I think that , with that objective , we do not have to discuss with the mother to know if the child gained weight or not . " ( 9 : 295 - 7 ) . When growth faltering is detected , the focus is on unilateral transmission of information and recommendations rather than on genuine communication with care - givers . The interviewees rarely described balanced and specific exchange of information between caregivers and health workers . One of them did mention a satisfactory ability of his staff to interact with caregivers but perceived an imbalance in the communication process : " This is my feeling , my understanding : health agents , nurses , and doctors can speak well but often cannot listen . Maybe , those messages and advice will work much better if one can develop the capacity to listen . " ( 2 : 207 - 10 ) . Some interviewees acknowledged the dichotomy . They justified it as the result of their professional training and its focus on curative care , but also because health professionals tended to give more value to technical acts : " Yes , you are health agents . Yes , you are here to fight against diseases , to heal people . It is how it is said during your training or even on several occasions . " ( 1 : 644 - 5 ) . " The health workers are more concerned by immunization because each single case is checked by us , and this is transmitted at the district level . Much emphasis is given nationally on immunization . " ( 17 : 260 - 2 ) . Finally , the gap between what should be done and what is actually implemented gave the feeling to some medical officers that GMP was a frustrating but compulsory routine prescribed by national and international agencies : " This is an activity of the Ministry of Health , thus we cannot forget it because of the risk of being reprimanded . It is the WHO , the UNICEF which advised to do so " , commented this interviewee . ( 13 : 363 - 71 ) . Another interviewee confirmed it : " I would say that most of the time we do it because we were told to do so . " " The WHO told us that it was useful , important , it was interesting , but I think that , in every - day practice , with some experience , you can manage without the growth chart . " ( 15 : 66 - 9 ) . Others dealt with the contradiction by considering that the programme had still a role to play because there was no relevant alternative or the growth chart was useful to health services : " But even so , it is a tool for the management of activities that we can maintain . " ( 19 : 154 - 7 ) . " And before abolishing , you need something to replace it , a valid alternative , and we do not have it . " ( 16 : 143 - 4 ) . Discussion This study was exposed to two potential biases . First , the interviewed District Medical Officers constitute a particular group , which might limit external validity . They were all starting a masters programme in public health in a European country . Their representativeness is , therefore , limited . The relatively high degree of coherence among the interviewees , despite the variety in backgrounds , could be explained by an affiliation to a common professional sub - culture , the field of international health . Second , the content of the interviews could have been influenced by the fact that the interviews took place in the institutions where the interviewees were studying . Each interview was led by an anthropologist employed by the same institution ( 19 ) . Since the course programme puts emphasis on participatory processes and the provision of healthcare in a process of communication with the population , some answers , considered more acceptable , could have been forwarded . However , if these elements would have played a role , we would have expected more answers mentioning health service activities committed to communication and empowerment of caregivers . Although all the interviewed health professionals agreed on the sub - optimal functioning of GMP , they have a rather limited understanding of the determinants for this failure . The quoted operational difficulties are very consistent with previous studies . The drop - in compliance after the immunization schedule is completed has often been mentioned and raised questions about the real acceptability of GMP by caregivers ( 20 ) . Although studies re - port mitigating results on the understanding of the chart by caregivers , overall scores are low ( 13 , 21 - 25 ) , and the association with literacy is quite consistently reported ( 13 ) . Determinants relating to the understanding of the growth chart and of GMP by health workers themselves were never mentioned , although it has been cited as a potential crucial element ( 26 - 29 ) . For instance , it was shown that when health workers had a correct know - ledge of GMP , a substantially higher proportion of growth charts was maintained ( 24 ) . One potential explanation for low rates of comprehension reported in mothers , as mentioned by some interviewees , could be due to low comprehension of the objectives of GMP by health workers , resulting in a limited communication ( 20 , 21 , 25 , 26 ) . A study in India reported that there was a gap between knowledge and skill for interpretation of growth - chart data among the assessed Child Development Project Officers ( 30 ) . Twenty - four District Medical Officers working in the same setting had a sub - optimal know - ledge about GMP ( 31 ) . Some authors have proposed that nutrition education could be more effective by making it more specific , action - oriented , individualized , and relevant ( 10 , 32 , 33 ) . This can only be achieved if clear algorithms for decision - making are available , and if health workers are trained in social communication ( 32 ) . Unfortunately , these conditions appear to be rarely fulfilled under field conditions ( 14 , 15 , 20 , 26 - 28 , 34 , 35 ) . Our study also revealed that most interviewed medical officers , by lack of understanding or conviction , did not attach great importance to the communication process theoretically underlying GMP . This is a striking finding as communication is central in the concept of GMP and as District Medical Officers bear the responsibility of implementing GMP programmes at the local level . We propose two main hypotheses to explain the poor results of GMP worldwide : irrelevancy of the concept or poor programme implementation ( 36 ) . Our study widens this second hypothesis . If caregivers poorly understand the growth chart , this might be the final con - sequence of a misunderstanding between international policy - makers and local implementers . Indeed , in the interviews , GMP appeared quite secondary in primary healthcare and communication quite secondary in GMP . It might be as well that the two hypotheses are strongly interrelated : to translate one concept ( GMP ) into universal practice with one same tool ( graphical representation of the growth ) in various cultural contexts and nutritional situations / settings could be considered a priori irrelevant . The question can be raised : is this conceptual and technical dominance compatible with the idea of communication imbedded in GMP ? What constitutes adequate growth does not necessarily overlap among lay people and health professionals ( 37 , 38 ) . This point has too often been overlooked . In Ghana , for instance , weight variation is only one indicator among many others traditionally used by caregivers to assess the nutritional status of their children ( 39 ) . In promotion as in evaluation of GMP , the significance of lay perceptions and behaviours concerning child development has seldom been recognized within the context of more ' modern ' approaches based on western concepts of health and disease . The important international promotion of the growth chart might not have taken various cultural definitions of adequate growth enough into account so far ( 40 - 43 ) . The attribution of growth faltering to a lack of information leading to inappropriate behaviours is a linear and simplistic paradigm still too often met in GMP practice . This approach does not recognize the complex interplay of the factors behind child growth and development . To have a future , GMP practice needs to re - focus on the child as a whole taking into account his / her health , growth , and development , and his / her family and socio - economic environment . Caregivers should , therefore , be involved in the process to bring together the observations and measurements made by both mothers and health workers ( 21 , 33 , 41 , 44 , 45 ) . Developing and implementing such an approach is challenging . It requires new ways of working in health services , reviewed training curricula of health personnels to help them centre on the child and improve their attitudes and communication skills ( 46 ) . In that process , it will be particularly crucial to convince medical officers that communication with families represents a major skill for health workers . Acknowledgements The authors would like to thank the students of the Inter - national Course in Health Development 2000 for their participation in the study . References World Health Organization . The growth chart . A tool for use in infant and child health care . Geneva : World Health Organization , 1986 . 33 p . Nabarro D , Chinnock P . Growth monitoring - inap - propriate promotion of an appropriate technology . Soc Sci Med 1988 ; 26 : 941 - 8 . Garner P , Panpanich R , Logan S . Is routine growth monitoring effective ? A systematic review of trials . Arch Dis Child 2000 ; 82 : 197 - 201 . Thaver IH , Husein K , Cara NB . The " P " in GMP - a major shift in growth monitoring program of a primary health care project . Southeast Asian J Trop Med Public Health 1993 ; 24 : 23 - 7 . Henry F , Briend A , Cooper ES . Targeting nutritional interventions : is there a role for growth monitoring ? Health Policy Plan 1989 ; 4 : 295 - 300 . Schroeder DG , Brown KH . Nutritional status as a predictor of child survival : summarizing the association and quantifying its global impact . Bull World Health O rgan 1994 ; 72 : 569 - 79 . Pelletier DL . The relationship between child anthropometry and mortality in developing countries : implications for policy , programs and future research . J Nutr 1994 ; 124 : 2047S - 81S . Cervinskas J , Gerein NM , George S . Growth promotion for child development ; proceedings of a colloquium held in Nyeri , Kenya , 12 - 13 May 1992 . Ottawa : International Development Research Centre , 1993 . 270 p . Dixon RA . Cost - effectiveness of growth monitoring and promotion . Lancet 1993 ; 342 : 317 . Lotfi M . Growth monitoring : a brief literature review of current knowledge . Food Nutr Bull 1997 ; 10 : 3 - 10 . Kolsteren P , Hoerée T , Perez - Cueto A . Promoting growth and development of under fives : proceedings of the International Colloquium , Antwerp , 28 - 30 November 2001 . Antwerp : ITG Press , 2002 . 375 p . Gopalan C , Chatterjee M . Use of growth charts for promoting child nutrition : a review of global experience . New Delhi : Nutrition Foundation of India , 1989 . 120 p . ( Special publication no . 2 ) . Grant K , Stone T . Maternal comprehension of a home - based growth chart and its effect on growth . J Trop Pediatr 1986 ; 32 : 255 - 7 . Ndao I . Evaluation du fonctionnement du suivi de la croissance dans les centres SMI du Congo . Alexandria : Université Senghor , 1992 . 60 p . ( Thesis ) . Gerein N , Ross DA . Is growth monitoring worth - while ? An evaluation of its use in three child health programmes in Zaire . Soc Sci Med 1991 ; 32 : 667 - 75 . Anonymous . Growth monitoring - a way to help improve the growth of young children and reduce chronic child malnutrition that deserves more attention in East Africa ( editorial ) . East Afr Med J 1987 ; 64 : 793 - 94 . Patton MQ . Qualitative evaluation and research methods . 2d ed . Newbury Park , CA : Sage Publications , 1990 . 532 p . Miles MB , Huberman MA . Qualitative data analysis : an expanded sourcebook . 2d ed . Thousand Oaks : Sage Publications , 1994 . 338 p . Richards H , Emslie C . The ' doctor ' or the ' girl from the university ' ? Considering the influence of professional roles on qualitative interviewing . Fam Pr act 2000 ; 17 : 71 - 5 . Mapatano MA , Lusamba D , Banea M . Evaluation of growth monitoring programme in children in Kinshasa . East Afr Med J 1997 ; 74 : 96 - 9 . Fagbule DO , Olaosebikan A , Parakoyi DB . Community awareness and utilization of growth chart in a semi - urban Nigerian community . East Afr Med J 1990 ; 67 : 69 - 74 . Aden AS , Brännström I , Mohamud KA , Persson LA , Wall S . The growth chart - a road to health chart ? Maternal comprehension of the growth chart in two Somali villages . Paediatr Perinat Epidemiol 1990 ; 4 : 340 - 50 . Karim F , Huq N , Brown L , Chowdhury AM . Growth monitoring in the context of a primary health care programme . Food Nutr Bull 1994 ; 15 : 192 - 9 . Gopaldas T , Christian PS , Abbi RD , Gujral S . Does growth monitoring work as it ought to in countries of low literacy ? J Trop Pediatr 1990 ; 36 : 322 - 7 . Rasheed P , Sunbul TJ , Ahmed BE , Al - Saleh AM . The growth chart - its use and perception among mothers visiting primary health care centers of Al Khobar , Saudi Arabia . Saudi Med J 1996 ; 17 : 195 - 204 . Lalitha NV , Standley J . Training workers and supervisors in growth monitoring : looking at ICDS . Indian J Pediatr 1988 ; 55 ( Suppl 1 ) : S44 - S54 . Gopaldas T . Field level health worker ' s skill in detection of growth retardation and faltering in young children . Indian J Pediatr 1988 ; 55 ( Suppl 1 ) : S55 - 8 . Reid J . The role of maternal and child health clinics in education and prevention : a case study from Papua New Guinea . Soc Sci Med 1984 ; 19 : 291 - 303 . Kapil U , Sood AK , Gaur DR , Bhasin S . Assessment of knowledge and skills about growth monitoring amongst multipurpose workers in an ICDS project . Indian Pediatr 1991 ; 28 : 895 - 9 . Kapil U , Paul D , Manocha S , Sood AK . Assessment of knowledge and skills about growth monitoring amongst child development project officers . Indian Pediatr 1991 ; 28 : 641 - 4 . Kapil U , Sood AK , Nayar D , Gaur DR , Paul D , Chaturvedi S et al . Assessment of knowledge and skills about growth monitoring amongst medical officers , child development project officers and multi purpose workers . Indian Pediatr 1994 ; 31 : 43 - 6 . Griffiths M , Dickin K , Favin M . Promoting the growth of children : what works . Rationale and guidance for programs . Washington , DC : Manoff Group , 1996 . 101 p . Griffiths M . Growth monitoring - making it a tool for education . Indian J Pediatr 1988 ; 55 ( Suppl 1 ) : S59 - S66 . Behague D . Growth monitoring and the promotion of breastfeeding . Soc Sci Med 1993 ; 37 : 1565 - 78 . Msefula D . How can growth monitoring and special care of underweight children be improved in Zambia ? Trop Doct 1993 ; 23 : 107 - 12 . World Health Organization . Department of Child and Adolescent Health and Development . A critical link : interventions for physical growth and psycho - logical development ; a review . Geneva : World Health Organization , 1999 . 79 p . ( WHO / CHS / CAH / 99 . 3 ) . Kolsteren PW , Lefèvre P , Lerude M - P . Nutrition rehabilitation and the importance of the perception of malnutrition in the follow - up of rehabilitated children . Asia Pacific J Clin Nutr 1997 ; 6 : 106 - 10 . Launer LJ , Habicht JP . Concepts about infant health , growth , and weaning : a comparison between nutritional scientists and Madurese mothers . Soc Sci Med 1989 ; 29 : 13 - 22 . Lovel H , Graaf JD , Gordon G . How mothers measure growth . Community dimensions for expanded growth monitoring in Ghana . Assignment Children 1984 ; 65 - 68 : 275 - 90 . Tonglet R , Lembo EM , Zihindula PM , Wodon A , Dramaix M , Hennart P . How useful are anthropometric , clinical and dietary measurements of nutritional status as predictors of morbidity of young children in central Africa ? Trop Med Int Health 1999 ; 4 : 120 - 30 . Cape N . Growth charts : help or hindrance ? Health Policy Plan 1988 ; 3 : 167 - 70 . Fagbule DO , Olaosebikan A , Jolayemi ET . Mothers as agents of growth monitoring : implications for widespread community growth monitoring . Afr J Med Med S ci 1991 ; 20 : 41 - 7 . de Suremain CE . " El buen cuidado " . Representa - ciones y prácticas de cuidado del niño en Bolivia . In : de Suremain CE , Lefèvre P , Ruben de Celis E , Sejas E , editors . Miradas cruzadas en el niño . Un enfoque interdisciplinario para la salud , el crecimiento y el desarrollo del niño en Bolivia y Perú . La Paz : Plural Editores , 2003 : 189 - 270 . Tchibindat F , Martin - Prevel Y , Kolsteren P , Maire B , Delpeuch F . Bringing together viewpoints of mothers and health workers to enhance monitoring and promotion of growth and development of children : a case study from the Republic of Congo . J Health Popul N utr 2004 ; 22 : 59 - 67 . Lansdown RG , Goldstein H , Shah PM , Orley JH , Di G , Kaul KK et al . Culturally appropriate measures for monitoring child development at family and community level : a WHO collaborative study . Bull World Health Organ 1996 ; 74 : 283 - 90 . George SM , Latham MC , Abel R , Ethirajan N , Frongillo EA , Jr . Evaluation of effectiveness of good growth monitoring in south Indian villages . Lancet 1993 ; 342 : 348 - 52 . © 2005 ICDDR , B : Centre for Health and Population Research The following images related to this document are available : Photo images [ hn05026t1 . jpg ] [

Hellstrom technique revisited : laparoscopic management of ureteropelvic junction obstruction Meng MV , Stoller ML From the Department of Urology , University of California , San Francisco , School of Medicine , San Francisco , California , USA Urology . 2003 ; 62 : 404 - 9 OBJECTIVES : To present our experience with the treatment of adult ureteropelvic junction ( UPJ ) obstruction using a laparoscopic Hellstrom vascular relocation technique . METHODS : Transperitoneal laparoscopy was performed in 35 patients for the management of UPJ obstruction . In 9 cases , we identified crossing lower pole vessels and performed the Hellstrom technique . We discuss our indications , intraoperative techniques , and outcomes when performing only vascular relocation in these patients . RESULTS : All 9 patients presented with long - standing flank pain and were identified as having UPJ obstruction ( 7 primary , 2 secondary ) on radiographic imaging . The intraoperative decision to perform the Hellstrom technique was based on the presence of the crossing vessels , a grossly normal appearance of the ureter and UPJ , and a small renal pelvis . The crossing vessels were completely mobilized , displaced cephalad , and fixed using intracorporeal sutures . The mean operative time and blood loss was 164 minutes and 15 mL , respectively . At a mean follow - up of 19 months ( range 14 to 31 ) , the patients were asymptomatic with no evidence of obstruction on Lasix nuclear renography . CONCLUSIONS : Traditional treatment of UPJ obstruction , with or without crossing vessels , has been accomplished by pyeloplasty . Dismembered pyeloplasty is a standard method in cases of associated crossing vessels ; however , we propose that the Hellstrom technique be considered in cases in which the ureter appears normal and the pelvic anatomy is unfavorable for transection and anterior reanastomosis of the ureter and pelvis . These considerations are particularly relevant during the laparoscopic approach in which intracorporeal suturing and knot tying are technically challenging . Editorial Comment This article describes the laparoscopic version of an infrequently used option for repair of ureteropelvic junction obstruction . In the Hellstrom approach to ureteropelvic junction obstruction , pyeloplasty is not performed and instead the anterior crossing vessels are relocated cephalad ( a mean of 2 . 3 cm in this series ) . Proponents of this technique argue that if there is no intrinsic ureteral obstruction , and the problem is simply anterior crossing vessels that allow the renal pelvis to herniate forward and kink off the ureteropelvic junction , then this " vasculopexy " will solve the problem with less surgical intervention . In an editorial following the article , Dr . Stephen Nakada expressed concern that cases of intrinsic ureteral abnormality might easily be missed with the subjective assessment of the intra - operative appearance of the ureter , and that performing vasculopexy rather than formal dismembered pyeloplasty with anterior relocation of the ureter might risk failure of the procedure . Indeed , the ( open surgical ) Hellstrom procedure fell out of favor years ago probably because of exactly this problem — it was applied in situations where there was in fact an intrinsic ureteral abnormality . That the authors ' intra - operative assessment was accurate enough that their procedure was successful in all nine patients is impressive . Even with my own fairly large experience with laparoscopic pyeloplasty , I would be concerned that I would be unable to make this assessment with a high degree of accuracy in the operating room . The authors cover themselves well in this regard , stating " If one is not completely convinced that the UPJ itself is normal , dismembered pyeloplasty should be performed . " A laparoscopic Hellstrom procedure appears to provide a good outcome in properly selected patients — I would just caution the reader that this selection might be very difficult and that the price of incorrect selection ( a failed procedure ) must be considered very carefully . Dr . J . Stuart Wolf Jr . Associate Professor of Urology University of Michigan Ann Arbor , Michigan , USA Evaluation of overall costs of currently available small flexible ureteroscopes Landman J , Lee DI , Lee C , Monga M From the Division of Urology , Washington University School of Medicine , St . Louis , Missouri ; and Department of Urology , University of Minnesota School of Medicine , Minneapolis , Minnesota , USA Urology . 2003 ; 62 : 218 - 22 OBJECTIVES : To perform a meta - analysis of the currently available data regarding the durability of flexible ureteroscopes to establish cost estimates for the purchase and use of five currently available , smaller than 9F , ureteroscopes . Healthcare costs have become increasingly germane to the determination of disease management strategies . Improved ureteroscope technology has expanded the role of these instruments . However , the initial purchase costs and high maintenance costs have become problematic with these fragile instruments . METHODS : Ureteroscope durability data on the Storz 11274AA , Olympus URF - P3 , Wolf 7325 . 172 , ACMI AUR - 7 , and ACMI DUR - 8 were collected from three prior studies . Combining the durability data and cost data regarding the initial purchase price and maintenance costs of these instruments , we calculated the overall costs associated with the use of each of the ureteroscopes for 25 , 50 , 75 , and 100 cases during the first year ( warranties included ) and with subsequent use . RESULTS : The variability in the costs associated with the use of the currently available smaller than 9F ureteroscopes was significant . The initial instrument purchase price , durability , repair costs , and associated warranties all contributed to large discrepancies in the cost of performing ureteroscopy . In this model , during the first year of ownership , the projected cost of performing 100 ureteroscopic cases varied by a difference of 95 % depending on the ureteroscope used . CONCLUSIONS . Physicians and institutions that perform ureteroscopy should strongly consider the purchase price , durability , repair cost , and associated warranties before the purchase of small flexible ureteroscopes . Editorial Comment The most impressive advances in the surgical treatment of urolithiasis over the past decade have been in ureteroscopy . The holmium : YAG laser is a significantly superior flexible lithotrite , and ancillary instruments such as tip less nitinol baskets and improved ureteral access sheaths have contributed greatly as well . Certainly , however , the most prominent improvements have been with regards to the size and capabilities of flexible ureteroscopes . The 7 to 8F flexible ureteroscopes , with working channels in excess of 3F , allow routine access to all portions of the upper urinary tract . As pointed out in this article , these instruments come at a considerable price . Although the initial purchase price of these ureteroscopes are similar , ranging from $ 11 , 995 to $ 15 , 000 ( USD ) , there is greater variability in the cost of major repairs , the degree of damage covered by the warranties , and — most importantly — the durability of the scopes . With the exception of the ACMI DUR - 8 ( the new Storz ureteroscope was not included in this analysis ) , the other four ureteroscopes have been shown in a previous study to last only 9 . 4 to 14 . 5 cases before repair is required . These figures were drawn from a head - to - head comparison of these ureteroscopes published previously , while the durability of the ACMI DUR - 8 ( 25 cases before repair ) was obtained from a meeting abstract that examined only that instrument . As such , the markedly improved figure for the DUR - 8 could be due in part to other factors , but the concept that durability ( as well as repair cost and warranty coverage ) makes a large difference in the overall cost of using a small - caliber ureteroscope is valid . The authors give us the very interesting figure " on the basis of consistent data provided by all four manufacturers " that 70 % of ureteroscopes sent in for repair have been damaged by user error - usually holmium : YAG laser damage to the working channel . The take - home message is : if you want to minimize the cost of flexible ureteroscopy , then determine the repair cost and warranty coverage of a ureteroscope , consider its reported durability , and be careful with the lithotrite . Dr . J . Stuart Wolf Jr . Associate Professor of Urology University of Michigan Ann Arbor , Michigan , USA © 2006 Sociedade Brasileira de Urologia Rua Bambina , 153 22251 - 050 Rio de Janeiro RJ Brazil Tel . + 55 21 2539 - 6787 Fax : + 55 21 2246 - 4088

The rate and morphology of collagen degradation were comparatively analyzed in rats with " early " and " late " carbon tetrachloride - induced hepatic fibrosis , during three different periods after discontinuation of the drug . Treatment with CCl 4 lasted for eight weeks for the group of early fibrosis and 12 weeks for the late fibrosis group . Fibrosis gradually disappeared , but when quantitative methods were applied , the amount of collagen degradation and removal in early and late fibrosis did not reach statistical significance . The light microscope and ultrastructural changes were also qualitatively similar in both cases . Probably some long - lasting effects to the liver , induced by the drug , prevented early hepatic fibrosis from undergoing the characteristic ultrastructural changes seen during " acute " collagen degradation , as compared to other experimental models of hepatic fibrosis , after the causal agent is totally removed . Present findings suggest that not only the age of fibrosis but also the overall damage inflicted to the organ are limiting factors in the process of collagen degradation and removal . unitermos Degradação do colágeno Fibrose hepática induzida por CCl 4 Cirrose hepática resumo O grau e a morfologia da degradação do colágeno foram comparativamente analisados em ratos com fibrose hepática recente ( tratamento de oito semanas com tetracloreto de carbono ) e tardia ( igual tratamento por 12 semanas ) , e acompanhados após a suspensão da administração da droga . O desaparecimento da fibrose ( quando quantitativamente avaliada ) foi gradual e semelhante para ambos os grupos . As modificações vistas à microscopia de luz e ao microscópio eletrônico foram também semelhantes . Estes resultados inesperadamente negativos diferem de outros modelos de fibrose hepática e sugerem que o grau de agressão ao parênquima hepático seja um fator limitante da degradação da fibrose que se segue à remoção do agente causal . Assim sendo , não apenas a idade da fibrose , mas o estado geral de alteração do órgão atingido influenciam a degradação e remoção do colágeno . Introduction Acute collagen degradation is said to occur when the cause of a recently installed fibrosis is removed . Fibrosis is then usually resorbed in less than a month , presenting an ultrastructural picture dominated by two main changes : extra - cellular collagen breakdown and internalization of collagen fragments , with strong evidences of metalloproteinase activity ( 3 , 11 , 13 , 16 ) . On the other hand , chronic collagen degradation occurs in long - standing fibrosis , takes months or years to be noticeable and exhibits two different ultrastructural features : focal lytic and focal electron - dense collagen changes ( 1 , 4 , 5 ) , with the expression of metalloproteinases and TIMP being not histochemically demonstrable ( 12 ) . Progressive removal of excess fibrous tissue , revealed by morphologic and / or biochemical evidences of collagen degradation , has long been recognized to occur in both physiological and pathological conditions ( 15 , 17 ) . The morphology of collagen degradation markedly differs when recent and old fibroses are in the process of being removed , as observed in experimental hepatic schistosomiasis of mice ( 3 , 4 ) and during the involution of the Seyle ' s inflammatory pouch in rats ( 11 ) . These differences , also observed on hepatosplenic schistosomiasis of man ( 1 , 5 , 12 ) , have led to the suggestion that the mechanisms operating in acute and chronic collagen degradation may also differ , since morphology and function are closely related . Most experimental models used for the study of extra - cellular matrix degradation ( metamorphosis of the tadpole tail , the carrageenin granuloma , involution of the pregnant rat uterus , treated acute schistosomiasis , etc ) are representatives of the acute type of degradation . They reveal the main differential ultrastructural features mentioned above as typical of acute degradation ( 16 , 13 ) . To further explore on the correlation between time of fibrosis installation and rapidity of fibrosis degradation on one side , and morphological findings on another , an investigation was made on early and late stages of the carbon tetrachloride - induced hepatic fibrosis in rats , after two different periods of drug administration , followed by three periods of observation after drug withdrawal . This study was also considered to , by exploring the subject of acute versus chronic collagen degradation in a well known experimental model of hepatic fibrosis , contribute to the model itself , and stimulate further research on one important topic of hepatic pathology . Materials and method Forty Wistar rats of both sexes , weighing from 150g to 300g , were treated with carbon tetrachloride ( CCl 4 ) , administered by a gastric tube , according to a standardized protocol ( 19 ) during eight weeks . After that period of treatment , the animals were separated into two groups of 20 animals each . The administration of the drug was stopped for the first group and continued during four more weeks for the second group . Upon discontinuation of CCl 4 administration , in both groups , the animals were submitted to partial hepatectomy ( surgical biopsies ) 72 hours and two weeks afterwards . Twelve weeks after drug withdrawal , all surviving animals were sacrificed . For the surgical procedures , the animals were anesthetized with ether , the abdomen was shaved and cleaned . Under sterile conditions , the abdomen was opened at the midline and a small portion of the liver ( approximately 250mg ) was removed and the surgical wound sutured . The fragments of the liver , obtained either after surgical biopsy or at necropsy , were submitted to the following procedures : Histology Portions of the liver were fixed in 10 % phosphate buffered formalin and routinely embedded in paraffin . The 5m - thick - sections were stained with hematoxylin and eosin and the picro - sirius red method for collagen . For semi - quantitative evaluation of fibrosis , the Sirius - red stained slides were examined under coding by two independent observers . Fibrosis was registered as mild , ( multifocal thin septal and perisinusoidal fibrosis ) , moderate ( disseminated distribution of septae and bands of fibrous tissue ) and severe , when cirrhosis was present . Each category was sub - divided into three numerical grades according to its intensity , to facilitate statistical analysis . Hydroxyproline measurements Fragments of the liver , weighing 0 . 100mg - 0 . 200mg , were submitted to the Bergman & Loxley ( 6 ) colorimetric method for the determination of hydroxyprolin content . Electron microscopy Tiny fragments of the liver were immediately fixed in 4 % glutaraldehyde in 0 . 2M sodium cacodilate buffer during one hour and post fixed in 2 % osmium tetroxide . After washing and dehydration , the pieces were embedded in Polybed resin . Ultra - thin sections were made with a diamond knife from selected blocks , mounted on copper grids , contrasted with uranyl acetate and lead citrate , and examined in a Zeiss EM - 109 electron microscope , under 50Kv . Morphometry The quantitative estimation of fibrous tissue was made on histological liver sections stained with Sirius red . The methodology used was similar to that previously described ( 7 , 8 ) . Briefly , the Leica Quantimet Q500MC ( Leica Cambridge , Cambridge , UK ) Imaging Workstation was used for measuring the fractional surface occupied by fibrosis in a total liver sectional area of 17 x 10 6 mm 2 for each of the three biological points of every animal from the two groups . Statistical analysis Variance analysis ( Anova ) and linear regression ( Graphpad Instat ) were used to test the differences between the means . Results Animals treated for eight or 12 weeks presented variable degrees of hepatic fibrosis , which tended to gradually disappear following discontinuation of treatment , as can be observed in the Table . In both cases a progressive decrease of fibrosis was noted following drug withdrawal . Such progressive reduction was noted at the different points of observation for each group , being statistically significant by the methods used . Morphometric and biochemical measurements of fibrosis coincided throughout , but semi - quantitative evaluation differed for Group I , by not showing significant differences between the means . Morphometric , semi - quantitative and biochemical estimation of fibrosis failed to demonstrate statistically significant differences between the groups . Histological and ultrastructural findings were similar for the two groups , and will be described together . Histologically , hepatic fibrosis accompanied by several degrees of liver - cell changes was present in all treated animals . It varied from thin septa to large bands of Sirius - red stained fibrous tissue , connecting central canals and portal spaces in various combinations , delimiting hepatocellular nodules of different sizes , frequently exhibiting the complete morphological picture of cirrhosis , as illustrated in Figure 1 , which is representative of the main type of evolution in both Groups . Fibrosis seen 72 hours after discontinuation of CCl 4 treatment appeared more compact and apparently augmented two weeks later , but definitively became less evident later on . Portal enlargement due to edema , infiltration by mononuclear cells and proliferation of ductal and ductular cells were remarkable 72 hours after treatment , but almost disappeared subsequently . Also , hepatocellular ballooning , macro and micro - vacuolar steatosis and lympho - macrophagic infiltration , especially evident at the centro - acinar zone III , 72 hours after treatment , tended to disappear two weeks later . Perisinusoidal fibrosis was frequently found , sometimes forming thin septa along the parenchymal acinar zone III . Such fibrosis was no longer observed in the material from the second biopsy , after discontinuation of the drug . However , some degree of hepatic fibrosis remained in all cases up to the end of experiment . Electron microscopic changes affecting the interstitial tissues were dominated by focal collagen alterations . In areas where the collagen fibers appeared parallel and packed , focal zones of clarification were noted . In them the fibers and fibrils were fragmented into tiny portions of variable sizes and calibers ( Figure 2 ) . Frequently empty circular areas were noted in zones of collagen breakdown . In spite of thorough search , no evidences of internalization or phagocytosis of collagen fragments were detected . Focal electron - dense deposits of a granular or filamentous material were seen replacing collagen fibers ( Figure 2B ) . Sometimes it simulated elastic fibers , but differed from them for being finely granular instead of homogeneous and compact . That change was more frequently seen in animals treated for 12 weeks , especially when examined 12 weeks after CCl 4 treatment . Degenerative changes also appeared in areas containing densely packed collagen fibrils ( Figure 3A ) . Quiescent fibroblasts and myofibroblasts were seen in close proximity to areas of collagen degradation , without a clear relationship other than spatial to the areas of focal collagen degradation ( Figure 3B ) . However , a clear empty space or halo was noted around some connective tissue cells located away from the areas showing focal degradative changes ( Figure 3B ) , suggesting pericellular lysis of the stroma . Morphometric analysis showed no significant differences between the groups ( Table ) . However , it did demonstrate a progressive decrease in the amount of fibrosis , statistically significant , after discontinuation of CCl 4 administration , when the interval points of both groups were considered . Discussion In the present experiment an attempt was made to produce early and late hepatic fibrosis by means of CCl 4 intoxication to rats , in order to comparatively follow its progressive degradation after drug discontinuation . Although the degree of fibrosis , morphologically evaluated by the extension and density of collagen deposition , were higher in rats treated for 12 weeks in comparison to those treated for eight weeks , and more evident the signs of collagen removal in the latter , these differences did not reach statistical significance when quantitative methods were applied . The three methods used for evaluation of fibrosis are adequate and usually yield concordant results . The little discrepancy seen with the semi - quantitative method as compared to the other methods , by showing no statistically significant differences between the examination points in Group I , is to be expected within the limitations of such methodology . Previously , our group obtained concordant results with the three methods ( 8 , 20 ) . Ultrastructural findings were , likewise , essentially similar in both groups and at their point intervals . The overall picture was consistent with the process of chronic collagen degradation , as seen in other experimental models ( 4 , 11 ) and in long standing fibrosis of man ( 1 , 5 , 12 ) . The reasons why no essential differences were found in the quantitative and qualitative features of collagen degradation in the present experiments were rather unexpected . Probably the CCl 4 - induced hepatic fibrosis in the rat model , especially because of its association with cirrhosis , is not adequate for the study of early collagen degradation . The effects of CCl 4 administration upon the liver is long lasting after drug removal , probably inhibiting the immediate action of the factors responsible for a more rapid collagen resorption , when the causal agent is suddenly removed . Persistence of collagen in tissue favors the process of intra molecular and inter molecular crossing link , turning the fibers more resistant to enzymatic digestion ( 10 ) . In models showing acute collagen degradation , it appears that the stimulus for fibrogenesis ceases rather suddenly , given rise to the characteristic degradative changes ( 3 , 11 , 13 , 16 ) . That did not seem to occur in CCl 4 - treated animals . The change in hepatic structure during cirrhosis is a point of considerable importance . Further studies may be necessary to evaluate how chronic damage to an organ or structure may interfere with collagen degradation , even when the cause of fibrosis was completely removed . Cirrhosis is accompanied by marked subversion of the hepatic structure , especially of its vascular component ( 18 ) . In this regard it differs from advanced hepatic schistosomiasis , which presents marked portal fibrosis , but maintains normal parenchymal structure . It is interesting to note that clinical , ultrasonographic and pathological studies have demonstrated almost total reversal of the liver pathology in hepatosplenic schistosomiasis patients following specific treatment of the parasitosis ( 2 , 9 , 14 ) . On the other hand , hepatic cirrhosis has for long time been considered irreversible , although some data on the contrary are now on record . Recently , Wanless et al . ( 21 ) made a detailed description of the histological changes indicative of regression of human cirrhosis . They called attention to a series of findings comprising the " hepatic repair complex " observed in a series of 52 livers removed at transplantation . The majority of the morphological parameters they considered as representative of hepatic repair could also be identified in the present material , confirming that the model of CCl 4 - induced hepatic fibrosis , so largely used to study fibrogenesis , can with advantage be utilized to investigate the evolution and morphology of fibrolysis . References 1 . Andrade , Z . A . Morphological features of collagen degradation in advanced hepatic schistosomiasis of man . Mem . Inst . Oswaldo Cruz , 87 ( Suppl . IV ) : 129 - 38 , 1992 . 2 . Andrade , Z . A . Extracellular matrix degradation in parasitic diseases . Braz . J . Med . Biol . Res . , 27 : 2273 - 81 , 1994 . [ Medline ] [ Lilacs ] 3 . Andrade , Z . A & Grimaud , J . A . Evolution of the schistosomal hepatic lesions in mice after curative chemotherapy . Am . J . Pathol . , 124 : 59 - 65 , 1986 . [ Medline ] 4 . Andrade , Z . A . & Grimaud , J . A . Morphology of chronic collagen resorption . ( A study on the late stages of schistosomal granuloma involution ) . Am . J . Pathol . , 132 : 389 - 99 , 1988 . [ Medline ] 5 . Andrade , Z . A . et al . Hepatic connective tissue changes in hepatosplenic schistosomiasis . Hum . Pathol . , 23 : 566 - 73 , 1992 . 6 . Bergman , I . & Loxley , R . Improved and simplified methods for the spectrophotometric determination of hydroxyproline . Annals of Chemistry , 35 : 1961 - 65 , 1963 . 7 . Barbosa Jr , A . A . Morphological computer - assisted quantitative estimation of stained fibrous tissue in liver sections : applications in diagnosis and experimental research . J . Bras . Patol . , 37 : 197 - 200 , 2001 . 8 . Coutinho , E . M , et al . Pathogenesis of schistosomal " pipestem " fibrosis ( A Low - protein diet inhibits the development of " pipestem " fibrosis in mice ) . Internat . I . Exp . Patho . , 78 : 337 - 42 , 1997 . 9 . Dietze , R . S . & Prata , A . Rate of reversion of hepatosplenic schistosomiasis after specific chemotherapy . Rev . Soc . Brás , Méd . Trop . , 19 : 69 - 73 . 1986 . 10 . Emonard , H . & Grimaud , J . A . Active and latent collagenase activity during reversal of hepatic fibrosis in murine schistosomiasis . Hepatology , 10 : 77 - 83 , 1989 . 11 . Freitas , L . A . R . et al . Morphological aspects of early and late collagen degradation in granulation tissue . Exper . Toxicol . Pathol . , 44 : 128 - 33 , 1992 . 12 . Gomez , D . E . et al . Expression of metalloproteinases ( MMP - 1 and MMP - 2 ) and their inhibitors ( TIMP - 1 and TIMP - 2 ) in schistosomal portal fibrosis . Am . J . Trop . Med . & Hyg . , 61 : 9 - 13 , 1999 . 13 . Henell , F . ; Bricsson , J . L . E . & Glaumann , H . An electron microscopic study of the post partum involution of the rat uterus : with a note on apparent crinophagy of collagen . Virch . Arch . B . Cell Pathol . , 42 : 271 - 87 , 1983 . 14 . Homeida , M . A . et al . Morbidity associated with Schistosoma mansoni infection as determined by ultrasound : a study in Gezira , Sudan . Am . J . Trop . Med . & Hyg . , 39 : 196 - 201 , 1988 . 15 . Murphy , G . & Reynolds , J . J . Extra cellular matrix degradation . In : Boyce P . M . & Steinmann , B . ( eds . ) Connective tissue and its heritable disorders . New York : Wiley - Liss Inc . , 1993 , p . 287 - 316 . 16 . Perez - Tamayo , R . Collagen resorption in carrageenin granulomas . II . Ultrastructure of collagen resorption . Lab . Invest . , 22 : 142 - 57 , 1970 . [ Medline ] 17 . Perez - Tamayo , R . Pathology of collagen degradation : a review . Am . J . Pathol . , 92 : 509 - 66 , 1978 . 18 . Popper , H . Pathologic aspects of cirrhosis . Am . J . Pathol . , 87 : 228 - 58 , 1977 . [ Medline ] 19 . Rosa , H . et al . Controlled production of cirrhosis in the rats liver . Arq . Gastroenterol . , 28 : 39 , 1991 . 20 . Souza , M . M . et al . Hepatic capillariasis in rats : a new model for testing anti - fibrosis drugs . Braz . J . Med . & Biol . Res . , 33 : 1329 - 34 , 2000 . 21 . Wanless , I . R . ; Nakashima , E . & Sherman , M . Regression of human cirrhosis . Morphologic features and the genesis of incomplete septal cirrhosis . Arch . Pathol . & Lab . Med . , 124 : 1599 - 607 , 2000 . Correspondence to Zilton A . Andrade Laboratório de Patologia Experimental Centro de Pesquisas Gonçalo Moniz Fiocruz Rua Valdemar Falcão 121 CEP 40295 - 001 - Salvador - BA - Brasil Fax : ( 55 ) ( 71 ) 356 - 4155 e - mail : zilton @ cpqgm . fiocruz . br Curso de pós - graduação em Medicina Interna - Universidade Federal da Bahia ; Centro de Pesquisas Gonçalo Moniz ( Fiocruz ) , Salvador ( BA ) , Brasil . © 2006 SBPC , SBP , SBC Rua Dois de Dezembro , 78 / 909 - Catete CEP : 22220 - 040v - Rio de Janeiro - RJ Tel . : + 55 21 - 3077 - 1400 / 3077 - 1408 Fax . : + 55 21 - 2205 - 3386

Journal of Postgraduate Medicine , Vol . 46 , No . 4 , October - December , 2000 , pp . 265 - 267 Modified Mesh Rectopexy : A Study Bakshi G , Ranka S , Agrawal S , Shetty SV Surgery Department , Seth G . S . Medical College and Dr R . N . Cooper Hospital , Vile Parle , Mumbai . Address for Correspondence : Sadanand V Shetty , MS , A - 103 , Rahul Apartments , Opp . Shoppers Stop , Mumbai - 400 058 , India . Code Number : jp00089 Abstract : AIM : To evaluate the efficacy of modified mesh rectopexy for complete rectal prolapse . SUBJECT AND METHODS : In a prospective study between 1989 - 1998 , 47 patients ( 25 males and 22 females ) underwent modified mesh rectopexy using a " Cross - shaped " knitted monofilament polypropylene . They were followed up for a period of four years postoperatively . RESULTS : Anatomical repair was achieved in all patients . Preoperative constipation , a complaint in 22 patients , was relieved in 13 patients and need for laxatives decreased in another four . There were no new cases of constipation . Sexual functions were not hampered irrespective of gender . The complications included prolonged ileus ( 4 patients ) , faecal impaction ( 1 ) , partial mucosal prolapse ( 2 ) and post - operative obstruction ( 2 ) . There was no recurrence . CONCLUSION : This technique aligns the rectum , avoids excessive mobilisation and division of lateral ligaments thus preventing constipation and preserving potency . We recommend this technique for patients with complete rectal prolapse with up to grade 1 , 2 and 3 incontinence based on Browning and Parks classification . ( J Postgrad Med 2000 ; 46 : 265 - 267 ) Key Words : Prolapse , Polypropylene , Incontinence , Constipation . Rectal prolapse is a distressing condition especially when associated with faecal incontinence and constipation . It usually occurs in children or elderly . Presently laparoscopic approach is favoured as it has better results especially in terms of less post - operative pain , shorter hospital stay and lower cost . 1 , 2 . This facility is not available universally , nor the expertise needed for it . Abdominal approach is still favoured by the conventional colo - rectal surgeon who is well versed with the technique and its outcome . 3 A 10 - year experience with modified mesh rectopexy ( MMR ) has been reviewed . Subjects and Methods This is a prospective , single centre , open study carried out in 47 consecutive patients with reducible complete rectal prolapse , from 1989 to 1998 , to evaluate the efficacy of Modified Mesh Rectopexy . Permission of ethics committee of the hospital was taken . Complete rectal prolapse was defined as per Goligher ' s criteria . 4 Of the 47 patients 25 were males and 22 females . Patients with grade 4 of Browning and Parks classification 5 of incontinence ( Table 1 ) and ASA grade IV and V were excluded . There was no history suggestive of underlying neuro - muscular abnormality in any patient and no history of obstetric trauma in females . Sexual function in males was assessed in terms of maintenance of erection , flaccidity , premature ejaculation and retrograde ejaculation postoperatively . Conception was assessed in females as six females were in reproductive age group in the study . Sexual function was not assessed in the rest 16 female patients . Four patients had a history of surgical intervention in past . Thiersch stitch was performed in three patients and in one patient abdominal approach was performed , details of which were unavailable . Constipation was the commonest complaint ( 22 patients ) followed by incontinence ( four patients ) other than rectal prolapse itself . All patients underwent MMR trans - abdominally . Preoperative preparation : Patient is given soft diet two days prior to the surgery . Metronidazole is given for bowel preparation , simple enema on night before and day of surgery . At induction , intravenous antibiotic i . e . third generation cephalosporin with aminoglycoside and metronidazole were administered and continued for 48 hours later . Technique : The patient was placed in moderate Trendenlenberg position after catheterisation . The rectum was mobilised by dividing the peritoneal reflection on either side . Pre - sacral space was entered and rectum mobilised up to the coccyx . Presacral nerves and ureters were routinely identified and safeguarded . Lateral ligaments were preserved in all cases . A monofilament knitted polypropylene mesh of size 15x15 cms cut in the shape of the cross as per individual requirement was placed in presacral space ( Figure 1 ) . The centre of the mesh was anchored the rectum to the sacral promontory with few 2 - 0 prolene sutures . The side arms of the cross encircles three - fourth the circumference of the rectum and upper and lower arms are sutured to posterior one - fourth of the rectum with the sacrum ( Figure 2 ) . Haemostasis was achieved and suction drains were kept on either side of rectum , which were removed after 48 - 72 hours . Mesh was extraperitonilised by resuturing back the divided peritoneal folds . Abdominal cavity was not drained . Laxatives were given routinely to all patients for a period of 3 - 4 weeks postoperatively . No colonic resection was performed . Pre and postoperative courses of patients were determined with particular interest in terms of constipation , continence , sexual function and recurrence determined . Follow up was obtained in terms of physical examination and symptoms on OPD basis for a mean period of four years . Results The age range was between 21 to 77 years ( mean 33 years ) . Only nine patients were more than 60 year of age . The procedure initially took a longer time with experience it could be completed within 90 minutes . Anatomical control of prolapse was obtained in all patients . Overall results are depicted in Table 2 . There was no mortality . Four patients had prolonged ileus . Two patients presented with adhesion - obstruction within six months of surgery , and were explored . In these patients the omentum and the small bowel were adherent to the peritoneal suture line which had given away in pararectal region . These sutures were taken to extraperitonealise the mesh . One patient developed faecal impaction which was removed manually . He was also given a stool softener for a few days later . Excision of prolapsed mucosa was undertaken in the two patients under local anaesthesia . No patient developed a leak or intra - abdominal sepsis indicative of mesh infection or rejection . Partial mucosal prolapse was encountered in two patients on straining postoperatively . Incontinence was present in three of four patients , who gave history of incontinence preoperatively . There were no new cases of incontinence . Postoperatively constipation markedly decreased in 13 patient and need for laxatives went down in another four , in the group of 22 patients who presented with constipation . Sexual function was preserved in all . There was no evidence of premature or retrograde ejaculation and patients were able to maintain erection with out any flaccidity . Six female patients in reproductive group conceived within four years after the operation . Seven patients lost to follow up ; in the remaining there was no recurrent rectal prolapse . Discussion In this study most of the patients were below the age of 60 years , in contrast to other series . 6 , 7 Complete rectal prolapse is thought to be due to circumferrential intussesception of the upper rectum and the recto sigmoid 8 or a sliding hernia according . 9 , 10 Placing a rectangular mesh requires extensive infero - lateral dissection and division of lateral ligaments . The cross shape of the mesh , as per the space available in para and retrorectal region corrects the defect anatomically by anchoring the rectum to the sacral promontory thus elevating , straightening and refastening it . It avoids sigmoid resection as in Frykman repair , 11 division of lateral ligaments and extensive dissection infero - laterally as in Ripstein repair 12 and Ivalon sponge rectopexy . 13 This prevents constipation 14 and sexual dysfunction in males . 15 In this study incontinence persisted in three patient of four postoperatively . They were young ; with a long - standing prolapse with damage to the sphincters probably . 6 Even if there was some colonic dismotility preoperatively , 16 constipation improved significantly in 13 of 22 patients who were constipated preoperatively . Constipation did not develop in the rest 25 patients due to preservation of lateral ligaments , division of which may interfere with colonic motility and the anchorage provided by lower limb of the cross , thus preventing an acute angulation of the rectum . 14 There was no recurrence upto a follow up of four years . We did not include the partial mucosal prolapse under recurrence as reported by Boccasanta et al . 17 Patients with chronic prolapse have excoriation of perianal skin , proctitis and are more liable to infection due to transmigration of microorganisms especially anaerobic and gram negative ones . Mesh , a foreign body is prone to this infection . Hence , pre - operative and post - operative antibiotics coverage is required . In conclusion , MMR is a safe and effective technique as it does not involve division of lateral ligaments , sigmoid resection and suture lines . Also need of sophisticated instruments and expertise of laparoscopy are avoided . The only drawback is the learning curve which once mastered can be performed as an effective alternative to the standard mesh rectopexy with comparable results . This procedure will add another shot to the colo - rectal surgeons armamentarium to deal with this condition . It gives results better then to other studies who have reported a recurrence of 3 - 8 % . 17 , 18 It restores the prolapse to its normal position preventing neurological damage and obliterating the deep pouch . It however does not repair the lax levators which is not always necessary and also do not strengthen the patulous anal orifice . We recommend plastic repair of these cases along with MMR . References Boccasanta P , Venturi M , Reitano MC , Salamina G , Rosati R , Montorsi M , et al . Laparotomic vs . laparoscopic rectopexy in complete rectal prolapse . Dig Surg 1999 ; 16 : 415 - 419 . Himpens J , Calliere GB , Bruyns J , Vertruyen M . Laparoscopic rectopexy according to Wells . Surgical Endoscopy 1999 ; 13 : 139 - 141 . Aitola PT , Hiltunen KM , Matikainen MJ . Functional results of operative treatment of rectal prolapse over an 11 - year period : emphasis on transabdominal approach . Dis Colon Rectum 1999 ; 42 : 655 - 660 . Goligher J , Duthie H , Nixon H . Surgery of the Anus , Rectum and Colon . 5 th Edition . London : Bailliere Tindall ; 1992 . Browning GG , Parks AG . Postanal repair for neuropathic faecal incontinence : Correlation of clinical result and anal canal pressures . Br J Surg 1983 ; 70 : 101 - 104 . Keighley MR , Fielding JW , Alexander - Williams J . Results of Marlex mesh abdominal rectopexy for rectal prolapse in 100 consecutive patients . Br J Surg 1983 ; 70 : 229 - 232 . Morgan CN , Porter NH , Klugman DJ . Ivalon ( polyvinyl alcohol ) sponge in the repair of complete rectal prolapse . Br J Surg 1972 ; 59 : 841 - 846 . Broden B , Snellman B . Procedentia of the rectum studied with cineradiography . A contribution to the discussion of causative mechanism . Dis Colon Rectum 1968 ; 11 : 330 - 347 . Devadhar , DSC . A new concept of mechanism and treatment of rectal procidentia . Diseases of the Colon and Rectum 1965 ; 8 : 75 - 78 . Moschocowitz AV . The cure of prolapse of the rectum - the pathogenesis , anatomy and cure of prolapse of the rectum . Surg Gynecol Obstet 1912 ; 15 : 7 . Frykman H M . Abdominal rectopexy and primary sigmoid resection for rectal procidentia . Am J Surg 1955 ; 19 : 780 - 784 . Ripstein CB , Canter B . Etiology and Surgical therapy of massive prolapse of the rectum . Ann Surg 1963 ; 157 : 259 - 263 . Wells C . New operation for rectal prolapse . Proc R Soc Med 1959 ; 52 : 602 - 607 . Sayfan J , Pinho M , Alexander - Williams J , Keighley MR . Sutured posterior abdominal rectopexy with sigmoidectomy compared with Marlex rectopexy for rectal prolapse . Br J Surg 1990 ; 77 : 143 - 145 . Yakut M , Kaymakcioglu N , Sinsek A , Tan A , Sen D . Surgical treatment of rectal prolapse . A retrospective analysis of 94 cases . Int Surg 1998 ; 83 : 53 - 55 . Brown AJ , Horgan AF , Anderson JH , Mckee RF , Finlay IG . Colonic motility is abnormal before surgery for rectal prolapse . Br J Surg 1999 ; 86 : 263 - 266 . Boccazsanta P , Rosati R , Venturi M , Cioffi U , De Simone M , Montorsi M . Surgical treatment of complete rectal prolapse : results of abdominal and perineal approaches . J Laparoendosc Adv Surg Tech A 1999 ; 9 : 235 — 238 . Novell JR , Osborne MJ , Winslet MC . Prospective randomised trial of ivalon sponge versus sutured rectopexy for full thickness rectal prolapse . Br J Surg 1994 ; 81 : 904 - 906 . This article is also available in full - text from http : // www . jpgmonline . com / Copyright 2000 - Journal of Postgradate Medicine The following images related to this document are available : Photo images [ jp00089t2 . jpg ] [ jp00089f2 . jpg ] [ jp00089t1 . jpg ] [

African Crop Science Journal , Vol . 9 . No . 2 , pp . 411 - 419 THE EFFECT OF MAIZE STOVER USED AS MULCH ON TERMITE DAMAGE TO MAIZE AND ACTIVITY OF PREDATORY ANTS M . B . SEKAMATTE , M . W . OGENGA - LATIGO 1 and A . RUSSELL - SMITH 2 Namulonge Agricultural and Animal Production Research Institute , P . O . Box 7084 , Kampala , Uganda 1 Department of Crop Science , Makerere University , P . O . Box 7062 , Kampala , Uganda 2 Natural Resources Institute , University of Greenwich , Central Avenue , Chatham Maritime , Kent ME4 4TB , U . K . 1 ( Received 30 August , 2000 ; accepted 9 November , 2000 ) Code Number : CS01023 INTRODUCTION Cultural control of termites in agriculture and forestry is attracting renewed interest following the ban on use of persistent organochlorine ( cyclodiene ) insecticides ( Logan et al . , 1990 ) . Non - chemical control involves methods which attempt , without the use of commercial pesticides , to ( i ) prevent termite access to plants , ( ii ) reduce termite numbers in the vicinity of plants , or ( iii ) reduce susceptibility / increase resistance of the plants themselves ( Logan et al . , 1990 ) . Published research on any of these methods is scarce , although numerous cultural procedures have been suggested , including measures to enhance plant vigour and to manipulate termite numbers and behaviour . The benefits of application of mulch to the soil surface are widely appreciated in tropical agriculture ( Schroth et al . , 1992 ) but the possibility of protecting crops against termite damage by use of mulches has remained controversial . Logan et al . ( 1990 ) reviewed the conflicting evidence for the use of crop residues and other organic mulches to control termites . Two conflicting theories have been advanced ; ( i ) that removal of residues and other debris from the field will reduce potential food supplies and hence lead to a reduction in termite numbers and subsequent attack ; and ( ii ) that leaving the residues in the field or adding further organic matter will provide alternative food to which the termites will be attracted , thereby reducing levels of attack on crops . Gold et al . ( 1991 ) tested mulches of plants with insect repellent properties ( Neem and Ipomea fistulosa ) and observed significant protection to groundnuts ( Arachis hypogaea ( L . ) ) . This study and other earlier experiments did not relate the quantity of mulch used with the levels of termite attack on groundnuts . In general , however , published studies reporting the significance of non – insecticidal mulches such as maize stover on termite attack on crops are lacking . The significance of crop residues on termite activity in field crops is also poorly understood . Dawkins ( 1949 ) gathered empirical evidence in Uganda that repeated mulching of tree nurseries with grass , over a period of one year , greatly reduced termite foraging . Although not strictly applied as mulch , tree trunks , branches and woody remnants are used in the Philippines and Sierra Leone to reduce termite attack in rice fields ( Litsinger et al . , 1978 ; Raymundo , 1986 ) . Leaves of the savanna tree Vitex doniana buried alongside cassava cuttings in Uganda , attracted termites away from cassava , reduced termite damage and led to increased sprouting ( Epila and Ruyooka , 1988 ) . The use of wooden logs in the Philippines aside , none of the published works directly deals with non - insecticidal mulches and levels of termite damage to crops . On the basis of the published literature and the authors ’ observations in recent field surveys in Uganda ( Sekamatte et al . - unpublished data ) , the present study was instituted with two objectives . First to determine the impact of different quantities of mulch on termite damage to maize and second , to assess the impact of mulching on relative incidence of predatory ant species and their role in regulation of termite activity in the maize cropping system . MATERIALS AND METHODS Study site . Field experiments were conducted at Namulonge Agricultural and Animal Production Research Institute ( NAARI ) , near Kampala at latitude 32 ° 27 ’ E and longitude 0 ° 32 ’ N , and a mean elevation of about 1200 m above sea level . There are two planting seasons ; the first , and normally more reliable one , occurs from March to June and the second from September to November , with mean annual level of 1300 mm . Maximum temperatures are in the range of 25 - 30 ° C and minimum temperatures range between 13 - 17 ° C . Effect of mulching on termite damage to maize . Five levels of maize stover mulch were used as treatments . These were : 0 kg ( control ) , 10 kg , 20 kg , 30 kg and 40 kg per plot . The stover amounts were used to provide a surface coverage of 0 % , 10 % , 40 % , 60 % and 80 % , respectively , in five 8 m x 8 m plots . Maize ( var . Longe - 1 ) was planted in the plots at a spacing of 75 cm between plant rows and 30 cm between plants within rows . Two maize seeds were planted per hill but thinned to one plant per hill 14 days after crop emergence . The experiments were planted 28 April 1998 and 17 October 1999 . Two weeks after seedling emergence the number of standing plants per plot was determined on the middle five rows of each plot . The maize stover treatments were applied 3 weeks after seedling emergence to cover the middle five rows in the respective plots . The treatments were laid out in a completely randomised block design replicated three and four times in the 1998 and 1999 cropping seasons respectively . Assessment of termite damage and ant activity . To termite damage on maize in different plots , both destructive and non - destructive sampling methods were used . Destructive sampling was carried out by randomly uprooting ten maize plants using a hand hoe from each plot . This type of sampling was done once at seedling , silking , green cob , and dry plant stages . The first destructive sampling was done at 4 weeks after crop emergence . Caution was taken not to destroy the root system while uprooting the plants . Presence or absence of termites attacking roots in the different treatments was recorded on each sampling occasion . In the case of non - destructive sampling 40 plants , randomly selected from within the middle 10 rows of each plot were carefully examined and scored for termite damage once every two weeks till dry cob stage . Termite damage to roots , stems , leaves and cob was scored using a scale of 1 - 5 , where 1 = no damage , 2 = 1 - 25 % , 3 = 26 - 50 % , 4 = 51 - 75 % and 5 = 76 - 100 % . A damage rating of 5 in most cases caused plants to lodge . During non - destructive sampling for termites , maize plants with evidently established colonies of Lepisiota or Myrmicaria or more than three ants nesting or foraging within 15 cm diameter around a sampled maize plant stem base were recorded in - situ . Ant activity was then expressed as the percentage of maize plants with ant nests out of 40 sampled plants per plot . Statistical analysis . Treatment effects , percentage of attacked plants and damage scores on roots and stem base were determined by ANOVA procedures . Data were subjected to square root transformation and conformed to assumptions of ANOVA as dictated by tests of normality ( PROC . GENSTAT 4 . 1 ) and tests of homogeneity of variance . Data for compound damage indices were analysed for individual sample dates . Other data were summarised as seasonal means , which were tested for normality and constant variance as above and subjected to ANOVA using procedures for completely randomised block design using the MSTATC software . To further test for the effects of mulching , orthogonal comparisons were made and regression analysis ( GENSTAT ) used to test for linear relationships of mulch quantity on the response variables . The means were separated by Fisher ’ s Least Significant Difference test at P = 0 . 05 . RESULTS Above ground termite damage on maize . The extent of termite damage to maize was significantly ( P Table 1 . Average percentages of plants with damage caused by termites in plots of maize affected by mulching with different quantities of maize stover at Namulonge , first cropping season in 1998 and second cropping season in 1999 Mulch quantity ( kg ha - 1 ) Compound damage index Plants with cut stems Plants lodged Root damage score First cropping season 1998 0 42 . 29 ± 10 . 2a 27 . 70 ± 2 . 3a 3 . 46 ± 0 . 9 1 . 94 ± 0 . 02a 10 42 . 50 ± 8 . 9a 18 . 27 ± 2 . 3a 4 . 22 ± 0 . 9 1 . 80 ± 0 . 19a 20 32 . 42 ± 6 . 8a 10 . 55 ± 2 . 3b 3 . 11 ± 0 . 9 1 . 86 ± 0 . 19a 30 17 . 30 ± 4 . 3b 9 . 54 ± 2 . 7b 3 . 00 ± 0 . 9 1 . 25 ± 0 . 05b 40 13 . 13 ± 4 . 3b 4 . 34 ± 2 . 1c 2 . 17 ± 0 . 9 1 . 17 ± 0 . 05b Second cropping season 1999 0 82 . 60 ± 8 . 9a 70 . 23 ± 7 . 7a 18 . 50 ± 2 . 1a 2 . 18 ± 0 . 06a 10 77 . 68 ± 9 . 2a 57 . 60 ± 5 . 2b 13 . 3 ± 1 . 9a 2 . 21 ± 0 . 06a 20 54 . 80 ± 5 . 4b 23 . 33 ± 2 . 6c 4 . 60 ± 1 . 3b 1 . 98 ± 0 . 06a 30 29 . 66 ± 3 . 2c 21 . 10 ± 2 . 6c 4 . 33 ± 1 . 3b 1 . 24 ± 0 . 06b 40 27 . 46 ± 3 . 2c 18 . 32 ± 2 . 6c 3 . 19 ± 1 . 9b 1 . 02 ± 0 . 06b For each cropping season means within a column followed by the same letter ( s ) are not significantly different at P = 0 . 05 ; LSD In the second cropping season , a similar pattern was observed in termite damage to plants under different levels of mulch . However , the effect of mulching was more pronounced than in the first cropping season possibly because of a higher termite infestation in the experimental field . All levels of mulch led to significantly lower termite damage on maize compared to unmulched plots . The reduction in compound index during this season in mulched plots ( compared to unmulched plots ) ranged between 6 . 5 and 100 % . Reduction in percentage of plants with cut stems ranged between 21 . 6 % and 100 % . For both parameters , however , only the 30 kg and 40 kg mulch per plot caused significantly ( P In both cropping seasons , no significant ( P = 0 . 05 ) differences in scores of root damage were observed between unmulched plots and plots with 10 kg and 20 kg amount of mulch . Root damage scores in plots with 10 kg and 20 kg mulch levels were , however , significantly higher than scores in plots with 30 kg and 40 kg mulch cover . Root damage in the 40 kg mulch level plots in the two cropping seasons was 77 % and 53 % lower than in the unmulched plots , respectively . There were no significant differences between plant lodging among treatments in the first cropping season . In the second cropping season , however , percentages of lodged maize plants were significantly ( P = 0 . 05 ) lower in plots with 30 kg , and 40 kg mulch cover than in the other treatments . A significant negative relationship between compound damage index and amount of mulch was observed in the two cropping seasons . The relationship between quantity of mulch and compound damage in the first cropping season was given by 36 . 85 – 0 . 1804x ( r = 0 . 69 ) and by 15 . 95 – 0 . 0265x ( r = 0 . 95 ) in the second cropping season . Below - ground termite infestation of maize . The main termite species infesting maize were Microtermes for most of the season with minor incidences of species from other genera in the post silking stages of the maize crop . Mean rates of infestation on roots of maize under different mulch treatments were relatively low and ranged from 16 . 5 to 23 . 5 % and 8 . 3 to 17 . 8 % in 1998 and 1999 cropping seasons , respectively ( Fig 1 ) . The differences were , however , not statistically significant . Effect of mulching maize on incidence of predatory ants . Ant species encountered in the experimental plots at Namulonge were mainly Myrmicaria sp . , and Lepisiota sp . Mean incidence of predatory ants at different crop growth stages in mulched and unmulched maize plots over the two cropping seasons are presented in Figure 2 . In the first cropping season , percentage of plants with nesting ants on the first two sampling occasions at 28 and 42 days after crop emergence ( DAE ) was low but higher in mulched than in unmulched plots ( Fig . 2 ) . The effects of mulching during this season began to show after 42 DAE . Eight weeks after planting ( 56 DAE ) , mulched plots had comparatively higher numbers of maize plants with ant nests compared to unmulched plots ( Fig . 2 ) . On subsequent sampling dates at 70 , 84 , 98 and 102 DAE , wide differences were observed among the levels of mulch . On most of sampling dates , the percentage of plants with nesting ants in plots with 10 kg per plot mulch cover was closer to that in unmulched plots . On the other hand , a higher percentage of plants with ant nests were consistently recorded in plots with higher quantities of mulch ( 20 , 30 and 40 kg per plot ) than in plots with 10 kg or without mulch cover although the differences between the 30 and 40 kg treatments was not that great ( Fig . 2 ) . No clear distinctions were observed between the 20 kg and 30 kg levels of mulch cover in percentage plants with nesting ants over the four sample dates . A sharp decline in ant nesting was observed between 84 DAE at which peak ant nesting was recorded and 98 DAE but the trend among treatments maintained the same pattern . ( Fig . 2 ) Despite the missing data at 42 and 102 DAE , during the second cropping season , a similar trend in ant nesting near maize plants was observed . Overall , however , the nesting of ants was lower compared to the previous season ( Fig . 2 ) . Peak incidence of ant nests in maize plots during the second cropping season was recorded at 98 DAE and plots with higher quantities of mulch had significantly ( P Analysis of variance of the percentage of plants with ant nests at peak incidence indicated highly significant ( P 2 = 0 . 8723 ) and y = 0 . 0283x – 0 . 133 ( r 2 = 0 . 911 ) in the 1998 and 1999 cropping seasons , respectively . A highly significant negative relationship was also obtained between percentage ant nesting and damage parameters of termites on maize . The relationship between percentage of damaged plants and ant count was expressed as y = 16 . 87 – 0 . 361x ( r = 0 . 88 ) and y = 23 . 33 – 0 . 426x ( r = 0 . 92 ) in the two cropping seasons , respectively . Table 2 . Average percentage of plants hosting ant nests at peak incidence in maize plots mulched with different quantities of stover during the first rainy season in 1998 and second rainy season in 1999 Quantity of mulch ( kg ha - 1 ) Cropping season First rains 1998 Second rains 1999 0 0 . 00 ± 0 . 0c 1 . 23 ± 0 . 2c 0 2 . 00 ± 0 . 3c 1 . 34 ± 0 . 1c 20 11 . 3 ± 3 . 7b 9 . 40 ± 2 . 3ab 30 23 . 02 ± 4 . 2a 10 . 85 ± 1 . 9ab 40 23 . 77 ± 5 . 5a 13 . 30 ± 1 . 7a C . V ( % ) 16 . 81 23 . 11 Means within a column followed by the same letter ( s ) are not significantly different at P = 0 . 05 LSD Maize grain yield . Maize grain yields in the two cropping seasons are presented in Figure 3 . In the first cropping season , maize grain yield in unmulched plots was not significantly lower than yield in plots mulched with 10 and 20 kg per plot . Plots with 30 kg and 40 kg per plot of mulch yielded significantly ( P = 0 . 05 ) better than the other treatments but did not differ significantly between themselves ( Fig . 3 ) . An almost similar pattern was obtained in yields during the second cropping season but no significant differences were obtained ( Fig . 3 ) . The yield gain ( above yields from unmulched plots ) caused by the 30 kg and 40 kg mulch cover during the first cropping season were 34 . 4 % and 35 . 7 % , respectively . DISCUSSION In the present study , provision of maize stover as mulches above 4 . 7 t . ha - 1 significantly reduced Macrotermes and Pseudacanthotermes ( Macrotermitinae ) attack on maize . Coaton ( 1950 ) also observed that mulching crops with various items such as hay , manure , wood shavings or threshed maize cobs dramatically reduced attack by termites . Wardell ( 1987 ) makes a similar observations in forestry and plantations systems and recommended leaving as much debris as possible on the site after clearing , to ring weed rather than clean - weed young stands and to use dried out stoloniferous and rhizomatous material from planting holes as mulch . Although Microtermes species were more abundant in mulched than unmulched plots , the differences were not significant . By contrast , Macrotermes and Pseudacanthotermes species were significantly less abundant in mulched than in unmulched plots . Two factors are presumed to be responsible for the observed responses : ( 1 ) the higher concentration of food resource for the termites , and ( 2 ) enhanced predation by ants within the microhabitat created by mulches . In Table 1 the level of termite attack on maize was shown to be lower in plots with higher quantities of mulch . The significant negative relationship between proportions of damaged plants and amount of mulch indicated that the two were inversely related . This supports the long established view that leaving crop residues in the field or adding further organic matter will provide alternative food to which the termites will be attracted thereby reducing levels of attack ( Logan et al . , 1990 ) . Further support for this view is provided by the results in Table 1 which indicate no or slight differences in termite attack to plants between plots without mulch and plots with low levels of mulch . The reduced termite damage on the other hand , could have been a result of enhanced predation of termites by ants beneath mulch . The results in Figure 2 indicated a steady progression of predatory ant activity across the season with significantly higher ant abundance in mulched plots compared to unmulched plots at peak incidence . The significant positive relationship obtained between quantity of mulch and mean number of plants with ant nests provided clear support for increased predation while that between quantity of mulch and termite attack indicated the positive effect of predation on termites . While it is also possible that both improved food sources for termites and enhanced predation termites accounted for our observations in this experiment , it is difficult to distinguish the effects of the two mechanisms . Our results on termite predation by ants in mulched plots provide evidence on the importance of natural control by the local predators Lepisiota sp . and Myrmicaria species . The results further suggest that the benefits of the enemies hypothesis ( Root , 1973 ) widely acknowledged in mixed cropping ( Altieri and Letourneau , 1984 ; Andow , 1991 ) could be applied to termites in maize monoculture through mulching . The higher abundance of ant predators in mulched plots observed in this study could be attributed to an improved micro - climate for the ants under mulch , presumably associated with increased humidity and shade near the soil . On the other hand , it could be the higher numbers of termite prey under mulch , which attracted ants in mulched plots . It is highly possible that interplay of the two mechanisms occurred although on basis of the present data , a distinction between them cannot be clearly demonstrated . These results suggest that it is the relationship between quantity of mulch available in the field and the duration of mulch material in relation to maturity period of the crop that might be important . On basis of the present results , a theoretical distinction emerges on the effect of non - insecticidal mulches between perennial crops and annual crops . Reasonable proportions of the 30 kg and 40 kg of maize stover used as treatments in both cropping seasons of this study , were still available in the respective plots at crop maturity . This suggested that the maize plants in these plots were constantly mulched all through the stages susceptible to termite attack . Reports of maize residue effects as reservoirs of lepidopteran stem borer larvae have been published ( Macharia , 1989 ; Saxena et al . , 1989 ) . On the other hand , a range of benefits of applying organic material as mulch to the soil has also been reported ( Webster and Wilson , 1966 )) . They include the reduction of soil erosion hazards , better infiltration of rain water and less evaporation , lower soil temperatures , supply of organic matter and nutrients , higher biological activity , better root growth and suppression of weeds ( Schroth et al . , 1992 ) . Adetola et al . ( 1995 ) also reported higher densities of detrivore and phytophage micro arthropods in maize plots mulched with stover compared to those in bare fallow and unmulched control plots . Undoubtedly , a combination of a range of factors could have been responsible for the significantly greater yields of maize in plots with high amounts of mulch in the first cropping season . In recent studies involving ant baits , Sekamatte et al . ( unpubl . ) , recorded significant increase in maize yields due to improvement in termite predation by Lepisiota and Myrmicaria species . The results suggested the important role of predators in reducing maize yield loss by termites . Under the smallholder conditions in Uganda , maize stover is available and , considering the effort needed to mulch the relatively small hectarage compared to the benefits ( mulching ) could be viewed as a justifiable practice for subsistence farmers . However , until more critical experiments are conducted in which the effect of mulching is isolated from effects due to predation and also to altered soil environments such as moisture and nutrients , the importance of mulch as alternative food for termites remains anecdotal . ACKNOWLEDGEMENTS We would like to thank our colleagues Jimmy Akono , James Kayongo and Solomon Kaboyo for their assistance with the field work . This publication is an output from a research project funded by the United Kingdom Department of International Development ( DFID ) for the benefit of developing countries . Project R6653 , Crop Protection Research Programme . The views expressed are not necessarily those of DFID . REFERENCES Adetola Badejo , M . , Guangton , T . and Brussaard , L . 1995 . Effect of various mulches on soil micro arthropods under a maize crop . Biology and Fertility of Soils 20 : 294 - 298 . Altieri , M . A . and Letourneau , D . K . 1984 . Vegetational diversity and insect pest outbreaks . CRC Critical Reviews in Plant Sciences 2 : 131 - 169 . Andow , D . A . 1991 . Vegetational diversity and arthropod population response . Annual Review of Entomology 36 : 561 - 586 . Bigger , M . 1966 . The biology and control of termites damaging field crops in Tanganyika . Bulletin of Entomological Research 56 : 417 - 444 . Brown , K . W . 1962 . Termite Control Research in Uganda with particular reference to control of attacks in Eucalyptus plantations . Eighth British Commonwealth Forestry Conference . Entebbe , Government publication , Uganda Protectorate . 9 pp . Coaton , W . G . H . 1950 . Termites and their control in cultivated areas in South Africa . U . S Africa Department of Agriculture and Forestry Bulletin 305 : 1 - 28 . Dawkins , H . C . 1949 . Timber planting in the Termitanaria wood - land of northern Uganda . Empire Forestry Review 28 : 226 - 247 . Epilla , J . S . O . and Ruyooka , D . B . A . 1988 . Cultural methods of controlling termite attacks on cassava ( Manihot esculanta ) with Vitex doniana : a preliminary study . Sociobiology 14 : 291 - 297 . Gold , C . S . , Wrightman , J . A . and Pimbert , P . 1989 . Mulching effects on termite scarification on drying groundnut pods . International Arachis Newsletter 6 : 22 - 23 . Logan , J . M . W . , Cowie , R . H . and Wood , T . G . 1990 . Termite ( Isoptera ) control in agriculture and forestry by non - chemical methods : a review . Bulletin of Entomological Research 80 : 309 - 330 . Lal , R . 1987 . Tropical Ecology and Physical Edaphology . Chichester , Wiley . 732 pp . Listinger , J . A , Price , E . C . and Herrera , R . T . 1978 . Filipino farmer use of plant parts to control rice insect pests . International Rice Research Newsletter 3 : 15 - 16 . Macharia , M . 1989 . Yield losses in maize due to Buseola fusca and its survival in crop residues . Annual Report , International Centre of Insect Physiology and Ecology 1985 . 5 pp . Pearson , E . O . 1958 . The insect pests of cotton in tropical Africa . London , Empire Cotton Growing Coorporation and Commonwealth Institute of Entomology . 335 pp . Raymundo , S . A . 1986 . Traditional pest control practices in West Africa . International Research Institute Newsletter 11 : 24 . Root , R . B . 1973 . Organisation of a plant - arthropod association in simple and diverse habitats : The fauna of collards ( Brassica oleracea ) . Ecological Monograph 43 : 95 - 124 . Saxena , K . N . , Reddy , K . V . S . , Omolo , E . O . , Pala - Okeyo , A . and Ngode , L . 1989 . Integrated pest management , Pilot trials . Annual Report International Centre of Insect Physiology and Ecology . pp . 20 - 21 . Schroth , G . , Zech , W . and Heinmann , G . 1992 . Mulch decomposition under agroforestry conditions in a sub - humid tropical savanna processes and influence of perennial plants . Plant and Soil 147 : 1 - 11 . Wardell , D . A . 1987 . Control of termites in nurseries and young plantations in Africa : established practices and alternative courses of action . Commonwealth Forestry Review 66 : 77 - 89 . Webster , C . C . and Wilson , P . N . 1966 . Agriculture in the Tropics . Longmans , London . The following images related to this document are available : Line drawing images [ cs01023b . gif ] [ cs01023a . gif ] [

I Hahn - Meitner - Institut Berlin , Glienicker Str . 100 D - 14109 Berlin , Germany II Inst . of Advanced Studies , Australian National University , Canberra , Australia ABSTRACT The past half century has seen an explosive growth of the discipline that is characterized by the deposition of localized high energy densities in solid matter , by means of energetic ions produced e . g . in particle accelerators . First the fundamentals of Ion - Solid Interaction are outlined . A brief overview is given about the basic energy transfer mechanisms and the consequences of ion impact into solids , such as scattering , sputtering and radiation damage . The latter gives rise to numerous changes in the material ' s physical and chemical properties , part of which has proven to be detrimental , and part of which is beneficial for technological applications . Though meanwhile a good general understanding of this discipline has been obtained , there are still plenty of lacks of details in our knowledge . Some representative examples are given . As a conclusion of all these points , one may say that , in spite of its age , Ion - Solid Interaction is still a challenging scientifical field , and it still offers lots of promising applications . I . INTRODUCTION More than half a century has passed already since the advancement of the field of ion - solid interaction to the state - of art that we know today . A fully developed science has emerged since then , and many effects which were just considered as objects of pioneering research just a few decades ago , now belong to the well - established academic material upon which many preparatory or analytic techniques in material ' s science are based , or which are even used for commercial applications . Nevertheless , in spite of all these achievements , there are still astonishingly large gaps to be found in many areas , if one only scratches a little bit deeper below the well - established surface . This represents a challenge as well for those colleagues working already since long in this area , as for newcomers in this field . In this paper , a short overview is given about this field and its applications ( with some special emphasis on ion - polymer interactions and electronic applications ) , and thereafter some open questions are posed which still deserve an answer by future researchers . II . FUNDAMENTALS OF ION - SOLID INTERACTIONS Sources of Energetic Ions . The basic requirement for performing any study in this field are , of course , energetic ions . They can be obtained in many ways , e . g . by making use of radioactive sources such as a particle or fission product emitters , or by exploiting nuclear reactions e . g . with neutrons from a reactor , that result in the emission of protons , tritons , a particles or fission products , depending on the type of irradiated material . Other particle ions become available by bombardment of swift heavy ions ( SHI ) onto appropriate target materials , via various types of nuclear reactions such as fusion reactions , spallation reactions , etc . Finally , for obtaining particles with the highest energies , one even can make use of the sporadically arriving cosmic rays . The easiest way nowadays , however , to obtain particles with sufficient fluence in a " convenient " energy range of , let us say , some keV to some GeV , is to produce them in an appropriate particle accelerator . There are hundreds of smaller accelerators available in the keV to lower MeV energy range , and nearly a dozen accelerators which provide ionic particles with upper energies of several hundred MeV to a few GeV . A typical example of the latter ones is the heavy ion accelerator " ISL " of the HMI Berlin which produces beams of ions ranging from hydrogen to gold , with maximum energies of ~ 70 MeV for hydrogen and ~ 400 MeV for gold . The maximum charge of the ions is in the order of 26 + , and the typical fluences that can be provided with these ions are in the order of 10 9 to 10 10 ions / cm 2 s . In one of the irradiation facilities , the particle beam can be scanned over a maximum area of 3 cm x 3 cm , and targets can be moved across this spot as well horizontally as vertically , thus covering maximum target areas of 30 cm x 30 cm in situ . In another facility , which is devoted to the irradiation of polymer foils , the particle beam can even be scanned horizontally up to ± 15 cm , whereas the target foil is fed vertically through the scanned beam . In this way , foils of lengths of hundreds of meters can be irradiated in one run . To obtain a good homogeneity of the irradiation , the particle current can be stabilized within ± 1 % . Stopping Power [ 1 ] . Once an energetic particle beam hits matter , it transfers energy to the latter . In contrast to the interaction of , e . g . energetic electrons or photons with matter , the main peculiarity of energetic ion impact is the extremely high localized density of the energy transferred to the target by the particles . In this way , solids may receive for a very short time ( ~ 10 - 17 to 10 - 15 s ) within a very tiny volume ( ~ 10 - 17 to 10 - 16 cm 3 ) the same energy density which else is only found in the vicinity of an exploding hydrogen bomb , by the impact of just one energetic heavy ion . The energy deposition is commonly described by the ,, stopping power " dE / dx which gives the energy transfer per pathlength of a particle along its trajectory . It has been found convenient to split up the particle stopping into two basic energy transfer mechanisms , that are dominated by atomic collisions with the target atoms ( ,, nuclear " energy transfer ) , and by excitation and ionization of the target electrons ( ,, electronic " energy transfer ) . The total stopping power is the sum of both components . Its reciprocal integral defines the projectile ' s total range . Both stopping powers increase with increasing energy until they reach a maximum value , and thereafter decrease . The electronic energy transfer reaches its peak value at energies which are orders of magnitude higher than the nuclear stopping maximum is . Light ions at any energy , and energetic heavy ions ( with stopping powers in the keV / Å range ) deliver much more energy via electronic excitation than by nuclear collisions ; for low energy heavy ions ( with stopping powers in the eV / Å range ) the nuclear energy transfer dominates . The nuclear interactions lead to transfer of kinetic energy to the knock - on target atoms which might be displaced from their original positions ( if the transferred energy exceeds the displacement energy ) , and thus might initiate structural defects ( e . g . vacancies and interstitials in crystalline materials ) or , in the case of molecular targets , their radiochemical destruction , if the transferred energy exceeds the displacement energy . Only upon very high electronic energy transfer by heavy ions , metallic targets exhibit structural changes due to phase transitions . Electronic energy transfer , if sufficiently small , does not show here any remarkable effect but often plays a dominant role in insulators , where it may lead to the formation of structural defects ( e . g . of F centers ) , to radical formation , to bond breaking , or to the formation of novel bonds . This constitutes the base of radiochemistry with energetic ions . Since ~ 20 years there exist well - established computer codes for the simulation of range and damage distributions in solids even in 3 dimensions , the most known one among them being the ,, TRIM " code by Biersack ( " TRIM " = Transport and Range of Ions in Matter ) [ 2 ] . In many circumstances these codes have an accuracy of a few percent and therefore will always be of general guidance use - particularly in determining approximate ranges and stopping powers . However , with TRIM for example , many and sometimes dominant secondary effects are not accounted for , including damage annealing , radiochemical changes , diffusion , etc . In particular there is no crystallinity , no real point defects , and no free surface , so that a good deal of caution and understanding is called for in more complex projectile / target interactions . Specifically two mechanisms , particle activated prompt anneal ( " PAPA " ) and diffusion assisted delayed anneal ( " DADA " ) [ 3 ] , should always be taken into account upon the impact of energetic ions onto matter , as they are good to explain many seeming disagreements between simple predictions and observations , e . g . in minerals . Whereas the individual nuclear collisions lead to a deviation of the projectile ' s flight direction from its original one , this is not the case for electronic energy transfer . Hence , for projectiles with dominant nuclear energy transfer , the particles will follow a zig - zag movement until they come to rest . This gives rise to a spatially extended damage distribution . For contrast , projectiles with dominant electronic energy transfer ( light ions at any energy , or very swift heavy ions ) follow a straight flight path . The damaged zone around that ion trajectory is called the " latent ion track " . Typical track lengths of SHIs are in the order of 30 to 130 µm ; the zone of maximum damage along this track , the so - called " ion track core " , has a typical radius of 3 to 8 nm . The latter is surrounded by a radial zone of greatly reduced damage of up to ~ ½ µm radius , the so - called " penumbra " . Ion Radiochemistry of Organic Matter . It appears that different transferred electronic energy densities lead to different types of defects , those ones formed after low energy ion impact being less stable than those ones initiated by more energetic ions . Consequently a great part of the electronic damage induced by low energy projectiles at ambient temperature often anneals after the irradiation , so that eventually the more stable but originally much less abundant nuclear defects finally dominate , in spite of 10 to 1000 - fold more overall energy spent for the electronic energy transfer . This effect vanishes , however , for more energetic projectiles , apparently due to more stable types of electronic defects dominating . Specifically for polymeric targets , the bond breaking and bond formation effects are known as " chain scissioning " and " cross - linking " . Of special importance is the fact that ion - induced chain scissioning of polymers upon energetic ion impact leads to an enhanced etchability of many ion - irradiated synthetic polymers . In other words , etchant attack of such an irradiated polymer foil leads to the formation of nano - or micropores , the so - called " etched tracks " . These pores can have different shapes ( cylindrical , conical , hyperboloidal , funnel - like etc . ) , which can be tailored to some extent by the proper choice of the corresponding parameters such as the projectile ' s energy transfer , the type of polymer , the type of etchant , etc . It must be mentioned at this occasion that etched tracks can also be formed in silicon oxides and - oxynitrides , and many minerals such as mica . Polymers that respond with cross - linking onto ion impact will show a reduced etching rate so that etching leads here to a gradual protrusion of the ion track out of the receeding sample surface . There are other peculiar effects to report , e . g . the ion irradiation of organometals which releases a narrow trail of metal atoms ( or oxides , sulfides , etc . , depending on the type of material irradiated ) along their tracks , which eventually are electrically conducting . This means , ion irradiation imposes an anisotropy onto the electric properties of such materials . SHI irradiation of polysilanes leads to the formation of SiC rods along the tracks , and SHI irradiation of diamond or fullerite leads to the formation of conducting carbonaceous nanotracks . III . APPLICATIONS OF LOW ENERGY ION IMPACT ONTO SOLIDS Technological applications [ 4 ] . Low energy ion beams were used in electronics for semiconductor doping through polymeric photoresist masks already since the 50th of the past century . Both negative resists ( where the solubility of the exposed resist decreases after ion exposure due to ion - induced cross - linking ) and positive resist ( where the solubility of the exposed resist increases after exposure due to ion - induced chain scissioning ) were employed . Ion irradiation enhances the resist ' s thermal stability and oxidation resistance considerably , which else withstands only about 150 to 200 C . ( The same method is also applied to make polymer films in space more radiation resistant . ) Since recently also the possibility to produce the lithographic masks by ion beams came into the focus of interest , as in this way the typical line - widths of the patterns can be reduced from ~ 0 . 4 µm for deep UV or ~ 0 . 25 µm for electron or X - ray lithography to about ~ 0 . 10 µm , due to the negligible lateral scattering of energetic ions . Here , focussed ion beams with computer - controlled positioning may gain an important role , as they also become a favoured tool for the production of novel Micro - ElectroMechanical Systems ( " MEMS " ) . For example , cogs , gears and other structures with typical lateral dimensions of a few µm have been produced by proton beams of a few MeV energy and currents in the order of 1 to 100 pA . It was found that corrosion protection of metals is possible by means of high fluence irradiation with , e . g . nitrogen ions , thus forming highly resistive surface nitride layers that also withstand tribological load much longer . Also the adhesion of immiscible layers of , e . g . metals and polymers could be increased considerably , by thorough ion beam mixing , or reactive ion implantation , substrate pre - sputtering , or ion - beam assisted deposition ( " IBAD " ) of materials . Furthermore optical applications of low energy ion beams , essentially for waveguide production , have become familiar . Surface Effects . Both the projectiles and the knock - on target atoms give rise to a number of effects in the surface region of an irradiated target , which are exploited in material analysis . If a projectile ion entering a solid is backscattered from a near - surface atom by a large angle collision , its ( direction - dependent ) energy loss sensitively depends on both the depth of the collision and the target atom mass . Therefore , the so - called " Rutherford Back Scattering " ( RBS ) technique has become one of the favoured analytical methods for determining the composition of solid target and their depth distributions . This technique holds , however , only for heavy target atoms . If instead , the depth distribution of light atoms is of interest , then it is preferable to knock - on these atoms in such a way that they escape from the target through the surface in forward direction ( which implies that the projectiles must hit the target surface under a non - normal direction ) . This gives rise to the so - called " Elastic Recoil Detection " ( ERD ) analysis . The release of surface atoms by the impact of an energetic ion is called " sputtering " . One has to distinguish between nuclear sputtering , that scales with the nuclear energy transfer for any target , and electronic sputtering , which takes place above some threshold energy upon the impact of very energetic heavy ions onto e . g . metallic targets , or upon the impact of an ion of any energy onto insulators . The recording of the mass distribution of sputtered atoms in dependence of the amount of removed surface material and of the position on the sample surface is used in the so - called " Secondary Ion Mass Spectrometry " ( SIMS ) for the determination of the 3D sample composition . As the impact of highly energetic ions onto molecular insulators does not only release small fragments from the very point of impact in a jet - like manner , but also larger fragments and even intact molecules from points more far away via shock - wave mechanisms , this sputter technique has become a well - established method to analyze complex organic matter ( Plasma Desorption Mass Spectrometry , " PDMS " ) . An effect frequently associated with high energy sputtering is " cratering " , i . e . the formation of a surface depletion in the region of ion impact . Due to a highly complex interaction with the material ' s elastic and plastic properties , craters often coexist with nearby hillocks , and sometimes hillocks have even been observed alone [ 4 ] . As the material ' s elastic and plastic properties are correlated with the final nanotopological structures in a well - defined way , it has been proposed to establish on this basis a technique to probe the material ' s mechanical surface properties in the nanometric scale [ 4 ] . Ion beam modification of polymeric surfaces for medical applications has gained importance for various reasons . On the one hand , the material ' s biocompatibility can be improved ; and on the other hand the irradiation of materials can enhance the bioadhesion , by enriching their surfaces with polar moieties , especially carboxyl groups , which seem capable of bonding most strongly to living biomass . Anticoagulant drugs such as heparin can be ion - grafted on the surface of protheses of all kinds inserted in the human organism , to avoid clotting of blood on their surfaces . Finally , material surfaces can also be sterilized by ion irradiation . Applications of high energy ion impact onto solids Applications of Latent Tracks in Solids [ 4 , 5 ] . Latent tracks in solids are not yet applied commercially , however three major possibilities show up for their future use : the exploitation of the material ' s radiochemical changes , of structural changes along latent tracks , and the use of ion - induced phase transitions . Radiochemical changes along the ion tracks in , e . g . polycarbonate lead to an increase of - OH and other groups to which protons from the ambient readily bond transiently , thus giving rise to a slightly enhanced conductivity . This signifies that such a material acts like a hydrogen sensor . SHI irradiation of polysilanes leads , after post - annealing , to the formation of long crystalline silicon carbide needles , which might be used for AFM cantilevers or , after appropriate doping , as field emitters . SHI irradiation of organometals produces narrow extended zones of metal ( or metal oxide , sulfide , etc . , depending on the type of organometal ) precipitates , thus giving rise to ( semi ) conducting tracks . The latter ones , if produced on top of a silicon wafer , form the so - called " TEMIMOS " ( = tunable electronic material with irradiated organo - metal on semiconductor ) structures , the peculiar electronic effects of which our group is just examining and is presented in Fig . 4 . Ion - induced structural changes modify the transport and trapping properties of diffusing impurities along the latent ion tracks , hence also their solubility and diffusitivity . This can be exploited e . g . in filtering and separation technology . Doping of latent tracks with electronically active materials ( or with their precursors , if some subsequent in - situ chemical reaction follows ) would also lead to novel electronic devices . Though this has been suggested already a decade ago [ 6 ] , it has , however , not yet been realized . Ion - induced phase transitions , which are suitable for technological applications are known for the carbon allotropes fullerite and diamond . Their irradiation yielding a non - graphitic , sp2 - rich conducting phase , one might construct field emission displays , FETs , or novel types of electronic devices ( " TEAMS " structures = tunable electronically anisotropic materials on semiconductors ) with them . Applications of Etched Tracks in Solids [ 3 , 4 ] . Since it was discovered that fossil tracks become visible in rocks after polishing and etching , much use has been made of this by geoscientists in applications to geochronology - - the determination of mineral and therefore rock ages from the chemical etching behaviour , particular the lengths of both spontaneous and induced fission fragment tracks . There are also applications in prospecting work for uranium , and for hydrocarbon deposits in sedimentary basins . More recently so - called T ( t ) models for track formation and annealing have been used in an attractive effort to extract information on the geothermometric history of the lithosphere . Unfortunately it has now been shown , and independently confirmed , that there is a very real influence of an ignored and basic physical feature , namely ambient pressure , on track length shrinkage during annealing - the so - called WVC ( Wendt - Vidal - Chadderton ) effect [ 7 ] . It appears that a fundamental reconsideration of this application must now be carried out . Another major breakthrough was obtained when it was found that most synthetic polymer foils are excellent carrier materials for etched tracks [ 8 ] . This inexpensive and simple method for the detection of energetic particles allowed many poorer fellow scientists from developing countries and their students to contribute with important work to the progress of various disciplines . For example , in dosimetry etched tracks have become important probes . From the observed track parameters , one can largely deduce the track - forming ion specie and its energy ; observed track distributions in , e . g . autoradiographic images allow one to determine the direction and the strength of particle radiation sources . Therefore track recording has also become commonplace in radioprotection , medicine , and biology . Apart from this , many ion track - etched membranes are used in filtration , which is needed for clean rooms , medicine and pharmaceutics , separation technology , and respiration protection . They are also used as inexpensive low - background catcher foils for ecological studies . Furthermore , micro - or nanoporous foils are successfully used for hospital treatment of burns and wounds , for gas pervaporation , and in analytical sciences . Ion track - etched membranes are often preferred to simpler and cheaper filter foils , due to their uniform thickness , inertness to toxic environments , a high tensile strength , large porosity , nearly unit tortuosity ( ratio of the pore length to membrane thickness ) , and very large sizes . Only with the onset of interest in nanoscience one started to incorporate matter in etched tracks , to form in this easy way nanowires , nanofibrilles , or nanotubules , shown in Fig . 1 . Depending on the incorporated material , various applications can be obtained . For example , by the grafting of thermoresponsive gels onto the walls of etched tracks one obtains nanovalves that open or close at a preset temperature . This can be used for intelligent in - vivo drug delivery . By addition of , e . g . anatase ( a TiO 2 phase ) nanoparticles to the track walls , the tracks develop photosterilizing properties which can be used for wound treatment , water purification or packing of food and flowers . Also the deposition of dispersed ( semi ) conducting nanoclusters onto the walls of etched tracks make sense , as the choice of the cluster - to - cluster distance determines the layer resistivity within many orders of magnitude from insulating to conducting , and it also allows for various current / voltage and current / temperature correlations of that track - based nanoresistor , due to the different conductivity mechanisms involved [ 9 ] . The incorporation of nanoclusters ( of Ag , Au , CdS , ... ) in etched tracks has been widely applied in the novel " TEMIPOS " ( = tunable electronic material with pores in oxide on semiconductor ) and " TEMIPOS " ( = tunable electronic material with irradiated polymers on semiconductor ) structures which stand in their behaviour somewhat in between tunable resistors , capacitors , conventional and Esaki diodes , field effect , bipolar , and unijunction transistors , and sensors , depending on their production and operation parameters , as shown in Figs . 2 - 4 . Various materials have already been - or still will be - embedded in etched tracks that act as nano - sensors for physical ( e . g . temperature , pressure , light intensity , magnetic field intensity , ... ) , chemical ( e . g . moisture , alcohol , acetone , sugar , ... ) , or biological ( germs , viruses , hormons , enzymes , ... ) parameters . Checkerboard - like contacting on both sides of such a suitably treated microporous foil will enable one in future to perform 2D mapping of the required sensor signals . By sandwiching the track - forming material with layers of other materials ( e . g . producing a Si - polymer bilayer structure ) , by multiple sequential axial or radial material deposition into etched tracks , and by combination with other well - known procedures such as metal evaporation onto the surfaces of these microporous foils , one can produce highly complex structures which may serve as micro - or nanocondensors , micromagnets , GMR structures , diodes , FETs , LEDs , TEMPOS structures , nanosensors that discriminate several species simultaneously , optical filters , etc . IV . PERSPECTIVES OF ION - SOLID INTERACTION Within the past half century the field of ion / solid interaction has been pretty well developed , and quite a number of applications has been found . But even now many details are still lacking , which is considered as a challenge for the scientists of the next 50 years . Below there are given just a few examples . There exist elaborate theories on the electronic stopping power [ 1 , 3 ] . However , more complicated cases , involving e . g . the collision parameter dependence and channelling effects , have not yet been treated analytically [ 11 ] . Though Bragg ' s rule is well - established for low energy ion impact even onto targets as complex as polymers [ 9 ] , it is not necessarily satisfied in such targets for highly energetic projectiles with their dominating electronic energy transfer . The reason for this is that the energy transfer sensitively depends on the electron / phonon coupling , which itself is determined by the type and structure of the atomic sublattices . For example , in ionic crystals such as CaF 2 or LiF , the phonons are strongly bunched along the < 100 > axes , so that the cation sublattice is almost totally protected against energy transfer . Hence the anionic sublattice accepts nearly all the electronically transferred energy , and consequently all the radiation damage [ 7 ] . In such cases , specifically in alkali and alkali earth halides , the Bragg Rule is completely violated , even with the advanced " CAB " model [ 10 ] incorporated . Finally , there have hardly ever been performed detailed measurements on the influence of directional effects in crystals on the electronic stopping power of SHIs . What happens upon ion / solid interaction , when the target size approaches zero ? Collision cascades in small targets , such as free - standing or embedded nanoparticles , will behave completely different from cascades in semi - infinite matter for which well - established computer codes exist since long [ 2 ] . Surface effects will dominate and probably lead to enhanced sputtering . The increased phonon scattering at the particle boundaries should give rise to higher damage , but , on the other hand , the larger and close surface area of such particles should act as a sink for defects that will anneal easier . Diffusing species should readily be trapped at the particle surface so that one should expect a gettering effect of the particle environment . Pronounced and beautiful craters have been observed after swift heavy ion impact onto insulators . It is , however , not yet known whether also keV particle impact onto insulating surfaces ( e . g . of polymers ) results in cratering . Impedance Spectroscopy is a well - established field in electrical engineering . It is convenient to depict both the frequency dependent resistance R ( w ) and the capacitance C ( w ) of a material in the complex plane via : Z = R ( w ) - i X ( w ) , with X ( w ) = [ w C ( w ) ] - 1 . ( Specifically for the complex dielectricity coefficient e = e ' - i e " of dielectric materials , one obtains in this way the famous " Cole - Cole plot " . ) Usually one finds semicircles or straight lines in these diagrams which can be modelled with corresponding equivalent circuits . Never such a Cole - Cole plot has been determined for ion - irradiated matter . Only little is known about the details of the clustering process of non - soluble high - dose implants , e . g . of metals in a polymer . Also the subsequent radiation - induced cluster redistribution has hardly been observed . Radiobiological questions become only now of interest , such as the adsorption and desorption of biological species on ion - irradiated surfaces . Also there is a lack of good information on the sterilizing properties of ion - irradiated surfaces . Radiochemical mechanisms after ion impact have been worked out only for the most common synthetic polymers . Nearly nothing is known , however , about corresponding reactions in e . g . elastomers , biodegradable synthetic polymers , " living " polymers , and organometals . Ion - induced polymerization and depolymerization processes in both solids and liquids have hardly been treated . The very promising development of ion - track - based sensors has only now just begun . There is a great demand for household , cars , ecology , chemical industry , medicine , and ABC antiterror protection . The same holds for actuators , to create self - regulating intelligent systems in the above - mentioned fields . As a conclusion , one might say that the field of ion - solid interaction , a former spin - off from nuclear science , is now a well established science with good fundaments and useful applications emerging . However , due to the relatively short life time of that science , many details are still unknown . Therefore , ion - solid interaction is still now regarded as a challenging scientific field that offers still lots of promising applications , and it justifies especially the invitation to interested scientists from other fields to contribute to this discipline with their great specific expertise . Acknowledgments We are especially indebted to our friends J . P . Biersack , A . Berdinsky , M . Behar , V . Hnatowicz , J . Vacik , M . Müller , and K . K . Dviwedi , for their expertise and continuous help and assictance in our work in the field of ion / solid interaction . We also want to extend our thanks to our dear colleagues R . M . Papaleo , W . R . Fahrner , K . Hoppe , and A . Chandra who contributed to many of the results reported here . Warm thanks also to our former PhD students and PostDocs T . Kie , L . Wang , R . Klett , P . Goppelt - Langer , A . Petrov , P . Fichtner , P . Grande , R . Kaschny , P . Alegaonkar and D . Sinha , and to many other helpful colleagues , unfortunately remaining unnamed here for the lack of space . This work was enabled by the kind assistance of M . Tabacniks and J . Chubaci , and by funds of the Sociedade Brasileira de Física , Sao Paulo , Brazil for D . F . REFERENCES [ 1 ] U . Littmark , J . F . Ziegler , " Handbook of Range Distributions for Energetic Ions in All Elements " , Vol . 6 , Pergamon Press , New York ( 1980 ) , and : J . F . Ziegler , " Handbook of Stopping Cross Sections for Energetic Ions in All Elements " , Pergamon Press , 1980 , and : J . F . Ziegler , J . P . Biersack , U . Littmark , Proceedings of the USJapan Seminar on Charged Particle Penetration Phenomena , ORNL report CONF820131 ( 1982 ) , p . 88 [ 2 ] J . P . Biersack , L . G . Haggmark , The Transport and Ranges in Matter . Nucl Instr Meth 174 , 257 ( 1980 ) . [ 4 ] L . T . Chadderton and D . Fink , Fullerene Genesis by Ion Beams III . On the Absence of Latent Tracks in GeV Ion Irradiated Graphite . Rad Effects Def . Solids 152 , 87 ( 2000 ) . [ 4 ] for more details , the reader is referred to modern textbooks , e . g . to : Transport Processes in Ion Irradiated Polymers and Applications , Vols . 1 and 2 , D . Fink ( ed . ) , Springer - Verlag ( 2004 ) [ 5 ] D . Fink , P . S . Alegaonkar , A . V . Petrov , A . S . Berdinsky , A . V . Rao , M . Müller , K . K . Dwivedi , L . T . Chadderton , The Emergence of New Ion Track Applications , Radiat . Meas . 36 , 605 ( 2003 ) . [ 6 ] D . Fink , R . Klett , Latent Tracks in polymers for future use in nanoelectronics , an overview about the present state - of - the - art . Braz . J . Phys . 25 , 54 ( 1995 ) . [ 7 ] A . S . Wendt , O . Vidal , and L . T . Chadderton , Earth and Planet Sci Lett . , 201 , 593 ( 2002 ) . [ 8 ] R . L . Fleischer , P . B . Price , R . M . Walker , Nuclear Tracks in Solids : Principles and applications . University of California , Berkeley , 1975 [ 9 ] S . M . Sze , Physics of Semiconductor Devices . J . Wiley Sons , New York , 2 nd ed . ( 1981 ) [ 10 ] J . F . Ziegler , J . Manoyan , The stopping of ions in compounds . Nucl . Instr . Meth B35 , 215 - 228 ( 1988 ) [ 11 ] Such a study is in progress now ( J . P . Biersack , pers . Communication 2004 ) Received on 3 November , 2004 © 2006 Sociedade Brasileira de Física Caixa Postal 66328 05315 - 970 São Paulo SP - Brazil Tel . : + 55 11 3091 - 6922 Fax : ( 55 11 ) 3816 - 2063

On October 1 , 1999 , Albertina Ximenes placed her son , Damião Ximenes Lopes , in the care of the Casa de Repouso Guarapes , the only psychiatric clinic in the Sobral region . Three days later on October 4 , Albertina returned to the clinic to visit Damião , who was suffering from a psychiatric disorder , but was informed that he " was not in a state to receive visits . " Dissatisfied , Albertina entered the clinic shouting Damião ' s name . Damião came to meet her , but was in a deplorable state , bleeding , with various wounds , hematomas and his hands tied . She asked a staff person at the clinic to take him for a bath , and afterwards sought the doctor in charge , Dr . Francisco Ivo de Vasconcelos , Clinical Director of the Casa de Repouso Guararapes , and forensic medical examiner in Sobral . The doctor merely prescribed some medicines , without examining Damião . When Albertina returned to look for her son again , a cleaner at the clinic told her that a fight had taken place between Damião and the nurses , and as a result of this Damião ended up badly hurt . Albertina found him beside a bed , completely naked with his hands tied . Unable to take Damião away , Albertina returned home . By the time she had returned home , the Casa de Repouso Guararapes had already rung informing her of the death of her son . The medical report , signed by Dr . Francisco Ivo de Vasconcelos and released on the same day , certified Damião ' s cause of death as " cardio - respiratory arrest . " Due to the circumstances surrounding his death , and the fact that the forensic medical examiner in Sobral also held the position of director at the clinic where Damião had died , Damião ' s relatives took his body for a post - mortem examination ( necropsy ) in the State capital , Fortaleza . The Forensics department in Fortaleza certified that Damião ' s cause of death was ' unknown , ' despite evidence that he suffered violent attacks . From this moment forward , Damião ' s sister , Irene Ximenes Miranda , began her search for justice , denouncing the events to all the responsible authorities , including the Civil Police , the Federal Prosecution service and the Ceará Legislative Assembly Human Rights Commission . Irene also denounced the difficulty she faced providing evidence of her brother ' s death following torture . In a statement sent to the Ceará Legislative Assembly Human Rights Commission on January 31 , 2000 , Irene noted that in the report sent by the police station to the Public Prosecutor , important statements were missing that placed responsibility with the clinic . 1 The police chief , after some questioning , suggested that the documents could be at his home . Soon afterwards , the police chief went home and returned to the station with the missing documents . It is important to underline that Irene was told she would not have acc ess to the clinic audit proceedings , nor even to the report . Irene was also told that the documents would be handed over to the mayor , whose family owned the Casa de Repouso Guararapes . Disappointed by the inertia and inefficiency of the Brazilian authorities responsible , Irene sent the denunciation to the Inter - American Commission on Human Rights ( IACHR ) , an organ of the Organization of American States ( OAS ) . Subsequently the non - governmental organization Justiça Global teamed up as co - petitioner with Irene Ximenes on the case before the Inter - American System . The Casa de Repouso Guararapes Founded in 1974 , the Casa de Repouso Guararapes was part of a network of private institutions affiliated with Unified Health System ( Sistema Único de Saúde , SUS ) to provide care for people with psychiatric disorders . It was the only institution of its kind in the Sobral region , as there were not even any emergency clinics . On July 10 , 2000 , following the repercussions of Damião Ximenes Lopes ' death , the intervention of the clinic was finalized and its registration as a psychiatric institution with the SUS System was cancelled . Failure to inspect and monitor the Casa de Repouso Guararapes by municipal , state and federal authorities Despite the municipality ' s obligation to " honor contracts and agreements with groups providing private health services , as well as controlling and monitoring the rendering of these services , " 2 no detailed contract was ever provided by the municipality of Sobral - not even following the denunciations relating to the death of Damião Ximenes - confirming the relationship between the Casa de Repouso Guararapes and the municipality . Only one inspection of the Casa de Repouso Guararapes took place in the years preceding Damião ' s death , in May 1996 by the Grupo de Acompanhamento de Assistência Psiquiátrica ( GAP ) . The inspection concluded that the institution was overcrowded , had precarious physical and structural problems , and presented various other irregularities in the running of the institution . Although these observations were duly reported to the governmental bodies in charge of the inspection and running of health facilities , 3 the Casa de Repouso Guararapes continued to function normally until July 10 , 2000 . The Brazilian State ' s responsibility Under the Brazilian Constitution and specific legislation on the subject , private institutions are authorized to assist with the fulfillment of the State ' s duty to provide medical care through public institutions . When the State confers authority directly or indirectly to an individual or organization , an extension of public authority power is created . The Brazilian State was thus responsible for the actions of the Casa de Repouso Guararapes employees , since it delegated the provision of health care in the Sobral region - a public , State function protected by the constitution - to the Casa de Repouso Guararapes , and allowed the clinic to operate in the name of a public authority . International Tribunals have determined that no State is exempt from responsibility for the actions of private groups carrying out public functions . The Casa de Repouso Guararapes was de facto an agent of the Brazilian State . International jurisprudence and customary international law also come to the conclusion that the Casa de Repouso Guararapes acted as an agent of the Brazilian State . The investigations and punishment of those responsible Damião Ximenes ' family made huge efforts to cooperate with the investigations into his death . Irene Ximenes investigated and took numerous people to give statements at the police station , frequently coming up against the police authority ' s inertia and negligence . On October 28 , 1999 , less than a month after the death of her brother , Irene discovered that an investigation into her brother ' s death had not even begun . Irene filed a denunciation before the Council for the Defense of Human Rights ( Conselho de Defesa dos Direitos Humanos , CDDH ) and the Ceará Council on Civil Society Participation ( Conselho de Participação da Sociedade do Estado do Ceará ) . When the case was finally opened in 2000 , Damião ' s mother , Albertina Ximenes Lopes , applied for and became an assistant to the Public Prosecution , so that she would have greater control over the progression of the case . On March 27 , 2001 , Irene and Albertina Ximenes received information that said the Public Prosecutor had ignored a request by the Ceará ' s Centro de Apoio Operacional aos Grupos Socialmente Discriminados do Ministério Público to amend the denunciation , and include Francisco Ivo de Vasconcelos , Marcelo Messias Barros , Maria Verônica Bezerra , José Eliéser Silva Procópio and Elias Gomes Coimbra as defendants in the criminal proceedings . Albertina Ximenes and Irene Ximenes were forced to send communications to the Public Prosecutor for the district of Sobral , requesting the inclusion of these accused as laid out by the Centro de Apoio Operacional . The murder of Damião Ximenes , Criminal lawsuit 2000 . 0172 . 9186 - 1 / 0 , is still being processed in the 3ª Circuit of the district of Sobral , Ceará , since March 28 , 2000 . The defendants in the case are Sérgio Antunes Ferreira ( owner and financial director of the Casa de Repouso Guararapes ) , Carlos Alberto Rodrigues dos Santos ( auxiliary nurse ) , André Tavares do Nascimento ( courtyard auxiliary ) and Maria Salete Moraes Melo de Mesquita ( nurse ) . They are accused of maltreatment followed by death , according to Article 136 , 2º of the Brazilian Criminal Code . On September 22 , 2003 , following insistent requests by family members , the Public Prosecutor requested the inclusion of Francisco Ivo de Vasconcelos ( director of the Casa de Repouso Guararapes Clinic ) and Elias Gomes Coimbra ( auxiliary nurse ) as defendants in the aforementioned case . Yet , six years later , the case has still not concluded . Civil Lawsuit 200001730797 - 0 / 0 , lodged by Damião Ximenes ' mother Albertina , is in the fact - finding phase of the procedure . 4 Similar to the criminal procedure , six years have passed and there has been no definitive decision regarding the civil case . The Ximenes family carries on without the due reparations for the damage and suffering they experienced . Progression of the Case in the Inter - American system Irene Ximenes ' denunciation was filed on 22 November 1999 . On October 9 , 2002 , the Inter - American Commission on Human Rights ( IACHR ) acted upon the denunciation and began to process the case , registering it as number 12 . 237 . 5 During the 119 th Session of the IACHR in October 2003 , the IACHR concluded that the Brazilian State was responsible for violating rights with respect to personal integrity , life , judicial protection and judicial guarantees , foreseen by articles 5 , 4 , 8 and 25 of the American Convention on Human Rights . These violations resulted from the cruel , inhumane and degrading treatment of Damião and the torture and subsequent murder within the Casa de Repouso Guararapes . The violation of the obligation to investigate the crimes , of the right to appeal and judicial guarantees were linked to the investigation of the events and the Brazilian judicial system . The IACHR also concluded that the Brazilian State violated its generic duty to respect and guarantee the rights outlined in the American Convention . The Inter - American Court of Human Rights ' sentence in the Damião Ximenes case is the first to deal with the cruel and discriminatory treatment of people suffering from psychological disorders . The acknowledgement by the Court of the vulnerable situation to which these people are subjected widens international jurisprudence , and strengthens the denunciations of organizations working against internment of psychiatric patients , particularly with respect to human rights violations perpetrated within psychiatric institutions . The Conduct of Brazilian Authorities and the Mental Health System Until today , not one individual or institution has been held responsible for the murder of Damião Ximenes Lopes . Despite the Public Prosecution Service having accused the owner and three employees of the Casa de Repouso Guararapes ( of Damião ' s death ) in March 2000 , and subsequently the director of the clinic and one other employee of the psychiatric institution , there has been no judicial decision until now . Since Damião ' s death , State agents have obstructed the search for justice and caused unjustified delays to the case . The State demonstrated a clear lack of will to extend judicial protection and secure appropriate legal recourse in the case , both in the initial treatment of the death and the subsequent processing of those responsible . During a public hearing in San José , Costa Rica , the seat of the Inter - American Court of Human Rights , between December 1 - 30 , 2005 , the Brazilian State acknowledged its responsibility with respect to articles 4 and 5 ( right to life and physical integrity ) of the American Convention on Human Rights . Following this , the State alleged in its defense the implementation of policies for the reduction of hospital beds and the control of services aimed at people suffering from psychiatric disorders carried out by the national coordination of the Ministry of Health ' s mental health system . Brazil ' s understanding was that these few measures would fulfill the recommendations made by the IACHR in its report on the case in 2003 . 6 It is important to emphasize that it was not the Brazilian mental health system and its recent reforms that were analyzed by the Inter - American Court of Human Rights , but the human rights violations suffered by Damião Ximenes and his family . Despite a certain amount of change and development in the treatment of people with mental disorders , no adequate or efficient instruments were set up to combat , investigate and monitor human rights violations suffered by psychiatric patients . As a way of preventing cases similar to that of Damião Ximenes , it is imperative that the Brazilian State proceeds with the closure of the psychiatric units failed by the National Program for the Evaluation of Psychiatric Hospitals ( PNASH ) . The evaluation of these psychiatric hospitals and centers as insufficient by PNASH confirms that these very institutions are potential violators of human rights , since they do not provide conditions for appropriate treatment for people with mental health disorders . The implementation of efficient mechanisms to receive and investigate denunciations of violence and maltreatment of people with mental health disorders is essential . This highlights the importance of participation of civil society representatives , the Office of the Public Prosecutor and groups representing professionals in the area of mental health , in the creation of a communication channel between patients and their families within the mental health system , and in the prevention of behaviors that lead to the violation of human rights . Other cases of violence against people suffering from psychiatric disorders The Dr . Milton Marinho psychiatric hospital , located in the municipality of Caicó , in the state of Rio Grande do Norte , was the scene of two murders of psychiatric patients , in 2000 ( José Martins da Silva ) and 2002 ( Sandro Fragoso ) . These two cases remain unresolved . The hospital remains open and those responsible for the deaths have not been brought to trial , despite an auditor from the Ministry of Health having concluded that with reference " to the denunciations attributed to the Dr . Milton Marinho psychiatric hospital of the deaths of José Martins da Silva and Sandro Fragoso , that we consider that the events that took place are directly related to the precarious nature of the care given to the patients . " 7 The murder of Wanderley Sobrinho Alves de Oliviera in Juiz de Fora , Minas Gerais , is another emblematic case of impunity . Oliveira , who was 53 years of age and suffered from schizophrenia , was hospitalized at the Dr . Penido clinic , and died on September 22 , 2000 . Oliveira ' s cause of death was attributed to serious hydroelectric shock , resulting from nearly 100 percent of his body being burnt . More than five years have passed since the murder of Wanderley de Oliveira , and the criminal case has still not been filled . In other words , a criminal process has not been opened . 8 In the municipality of Rio Grande , in the state of Rio Grande do Sul , on July 5 , 2006 , a serious example of the violation of human rights in a psychiatric clinic took place , as three young girls were burnt to death in a fire that took place in a room in the female ward of the local psychiatric hospital . According to criteria for the classification of psychiatric hospitals , which include the quality of care provided , number of beds , physical structure , dynamics , level of involvement in the mental health network and adherence to the technical norms prescribed by the SUS , the National Program for the Evaluation of Psychiatric Hospitals ( PNASH ) 9 recommended the removal of official accreditation for the following institutions : 10 In its 2002 annual report : 1 ) Casa de Saúde Santa Catarina - Montes Claros , Minas Gerais - 124 beds ; 2 ) Instituto de Reabilitação Funcional - Campina Grande , Paraíba - 145 beds ; 3 ) Fundação Hospitalar do Seridó ( Hospital Psiquiátrico Dr . Milton Marinho ) - Caicó , Rio Grande do Norte - 72 beds ; 4 ) Casa de Saúde Dr . Eiras - Paracambi , Rio de Janeiro - 980 beds ; e 5 ) Hospital Estadual Teixeira Brandão - Rio de Janeiro - 102 beds ; In its 2003 and 2004 reports : 1 ) Sanatório São Paulo - Salvador , Bahia - 175 beds ; 2 ) Sanatório Nossa Senhora de Fátima - Juazeiro , Bahia - 80 beds ; 3 ) Hospital José Alberto Maia - Camaragibe , Pernambuco - 980 beds ; 4 ) Hospital Santa Cecília - Nova Iguaçu , Rio de Janeiro - 200 beds ; 5 ) Hospital Colônia Lopes Rodrigues - Feira de Santana , Bahia - 500 beds . According to information from the Central Coordination for Mental Health , Ministry of Health , of these 10 hospitals , only three have been closed . 11 Seven remain open . 12 The Inter - American System of Human Rights For further information on the Inter - American Court of Human Rights , visit http : // www . corteidh . or . cr / general_ing / index . html For information about the Inter - American Commission on Human Rights , visit http : // www . iachr . org / what . htm Footnotes : 1 Law 8080 , article 18 , X ; 19 September 1990 . 2 Idem 3 Civil lawsuit 200001730797 - 0 / 0 . Information available at http : // www2 . tj . ce . gov . br / sproc / paginas / sprocprincipal . htm . 4 Inter - American Commission on Human Rights , Admissibility Report , Case 12 . 237 , Damião Ximenes Lopes vs . Brazil . 5 Relatório de Mérito n . º 43 / 03 da Comissão Interamericana de Direitos Humanos , página 43 . 6 Information contained in the SUS Audit Report , carried out by the National Audit Department ( Audit 689 , published on 2 December 2003 ) . 7 The police inquiry started on 25 October2000 . After three years of police inquiries , the police chief responsible for the investigation presented a report ( on 19 May 2004 ) and concluded for the indictment of six doctors and nine nurses of the Hospital Dr . João Penido , for the crimes of mal - treatment followed by death . Since this date the investigation became the responsibility of the Office of the Public Prosecutor in Minas Gerais to present a criminal denunciation before the local judge and , then start the criminal case . 8 PNASH was created by Law 10 . 216 / 2001 , to foster the improvement of hospital services and the des - internment of patients with mental disorders . It established a ranking of the public health service network , based on quality indicators defined by the Program itself and by the number of hospital beds available . 9 This list is available at http : // portal . saude . gov . br / portal / arquivos / pdf / GM251 - diretrizes % 20e % 20normas % 20para % 20assist . hosp . psiquiatria . pdf . 10 Official communication nº . 541 / 2005 - MS / SAS / DAPE / CSM , sent by the Coordination of Mental Health , Ministry of Health , to the petitioners on 6 th January 2006 . 11 Official communication nº 1333 - 05 / CG - CFP , dated 18 November 2005 , sent by the Vice - President of the Federal Council of Pyschology ( Conselho Federal de Psicologia ) to the petitoners . Information : Justiça Global : In Brazil : ( + 55 ) 21 2544 2320 / 8272 1916 / 8232 1771 - Sandra Carvalho , executive director ; Carlos E . Gaio , international relations director In the USA : ( + 1 ) 617 669 8606 - James Cavallaro , Justiça Global ' s vice - president and clinical director of Harvard Law School ' s Human Rights Program In the UK : ( + 44 ) 7908 061849 - Andressa Caldas , adjunct director Damião Ximenes Lopes ' family : In Sobral , Ceará : ( + 55 ) 88 3685 1281 / 9924 8142 - Irene Ximenes ( Damião ' s sister ) In Fortaleza : ( + 85 ) 8814 8112 - Dra . Lídia Costa , expert in the case

Sandra R . Haas 1 ; Fábio R . Nascimento 1 ; Ivo André H . Schneider 1 * ; Christine Gaylarde 2 1 FEAR , Universidade de Passo Fundo , Passo Fundo , RS , Brasil . 2 MIRCEN , Departamento de Solos , Universidade Federal do Rio Grande do Sul , Porto Alegre , RS , Brasil Submitted : November 11 , 1998 ; Approved : May 21 , 1999 . ABSTRACT The treatment of fine particles dispersed in liquids is common in several industries and especially important in mineral processing . The efficiency of settling operations can be substantially increased by flocculation . The aim of this work was to study the flocculation of fine fluorite particles by the bacterium Corynebacterium xerosis . Flocculation tests , microelectrophoresis measurements and optical microscopy were used to evaluate flocculation . The results showed that C . xerosis cells adhere to the fluorite surfaces promoting the aggregation of the particles . High quality flocs can be obtained rapidly at pH 7 . 0 using a cell concentration of 40 mg / l , considerably lower than previously reported in the literature . The results are discussed with reference to the surface characteristics of the mineral and of the microorganism . Key words : adhesion , Corynebacterium xerosis , flocculation , fluorite . INTRODUCTION At various stages during the processing of minerals it is necessary to separate the aqueous suspensions into their component solid and liquid phases . Typical examples of this are thickening of flotation concentrates , recovery of pregnant leach liquors , and dewatering of tailings . In many cases , the mineral particles settle out of suspension very slowly , so that the liquid - solid separation is slow and incomplete . The efficiency of such gravity settling operations can be substantially increased by aggregation of the mineral particles . Methods currently used for aggregation and settling of finely divided solids in slurries include pH adjustment , increasing ionic strength , introduction of inorganic coagulants such as aluminum and ferric salts , and introduction of organic flocculants such as starch and long chain synthetic flocculants ( 10 , 15 , 16 ) . These methods , in addition to increasing costs , can also lead to the release of polluting waste materials . Finely divided mineral particles can also be flocculated by microorganisms . An isolate of Arthrobacter has been shown to promote the settling of fines in manganese ore washings ( 5 ) . The bacterium Mycobacterium phlei ( 7 , 14 ) and the yeast Candida parapsilosis ( 12 , 13 ) improved settling rates in mineral suspensions , but flocculation was not as good as that obtained with commercial long chain flocculants . Most microorganisms adhere to solid surfaces if the charge and hydrophobic interactions between the cells and the solid surface are favorable , but do not always promote flocculation of mineral particles . The mechanism of this flocculation appears primarily to be cell adhesion and bridging between the particles . Van Loosdrecht et al . ( 17 , 18 ) showed that cells of M . phlei and Corynebacterium xerosis were highly hydrophobic and negatively charged . Since previous work has shown that the former microorganism does not effectively promote flocculation of fluorite ( 8 ) , we investigated the potential of the latter , C . xerosis , to flocculate fine fluorite particles . The effect of settling time , cell concentration , and pH of the suspension on solids settling was studied . The results are discussed in terms of the surface properties of the mineral and of the microorganism . MATERIALS AND METHODS Fluorite Fluorite crystals ( 99 % CaF 2 ) were obtained from a mining company ( Criciúma - Santa Catarina , Brazil ) . The crystals were ground in a laboratory mill . The particle size distribution of the sample used for flocculation tests was determined by laser difraction in a Malvern Particle Size Analyzer Model 3601 ( Table 1 ) . Microorganisms The bacterium Corynebacterium xerosis , from Caroline Biological Supply Company - USA , was grown for 72 hours in nutrient broth . Cultures were produced in 300 ml flasks , continuously shaken at 37 o C . Cells were harvested by centrifugation , washed twice in distilled water and finally suspended in water to give a 2 g / l suspension . This stock cell solution was kept at 5 o C and used in flocculation studies within 48 hours , either neat , or at various dilutions . Flocculation tests Flocculation studies were carried out using a standard " Jar Test " apparatus . Settling tests were performed by preparing 1000 ml suspensions containing 10 g / l of fluorite . The pH of the medium was adjusted as required and the microorganisms added to the mineral suspension . The suspensions were mixed by stirring for 1 min at 250 rpm to promote a uniform distribution of the cells . The stirrer speed was reduced to 50 rpm for 2 min , to create low shear conditions and allow floc formation . Particles were then allowed to settle under gravity and samples were withdrawn at set time intervals from 10 cm below the water surface . The flocculation efficiency was evaluated by the following parameters : - naked eye and microscope observation of floc quality ; - residual turbidity in nephelometric units of turbidity ( NTU ) ; - solids removal from water . The solids concentration was determined gravimetrically . The solids removal percentage ( or flocculation efficiency ) was calculated using the relationship . where : Ci = initial concentration of solids Cf = concentration of solids after time t Zeta potential measurements The electrokinetic properties were studied as a function of pH using a Rank Brothers Ltd microelectrophoresis apparatus . C . xerosis cells and fluorite particles were suspended in water containing 1x10 - 3 M NaNO 3 and the pH was adjusted by addition of NaOH and HNO 3 . For each pH value 20 readings were taken and averaged . The zeta potential was calculated from electrophoretic mobility using the Smoluchowsky equation ( 9 ) . RESULTS Fig . 1 shows photomicrographs demonstrating the flocculation of fluorite by C . xerosis . Fig . 1a shows dispersed fluorite particles in the absence of the microorganisms . In the presence of C . xerosis cells , particles are agglomerated ( Fig . 1b ) . These fluorite / cell aggregates settle very rapidly in water allowing an almost complete solids removal and a high clarification of the water . Figure 1 . Photomicrographs of fluorite particles suspended in water ( a ) and aggregated in the presence of Corynebacterium xerosis ( b ) . Magnification 100x . The effect of settling time on flocculation efficiency in the presence of 40 mg / l C . xerosis cells at pH 7 . 0 is shown in Fig . 2 . The result is compared to a plot obtained in the absence of flocculant . In the presence of bacteria , near maximum flocculation is obtained within 30 s after the beginning of settling . The same test procedure was used to evaluate the effect of settling time on residual turbidity , which was decreased from 130 NTU to 20 NTU in approximately 5 min in the presence of C . xerosis ( Fig . 3 ) . Figure 2 . Solids removal efficiency of fluorite suspensions as a function of settling time in the presence or absence of 40 mg / l of Corynebacterium xerosis ( pH 7 . 0 + / - 0 . 2 ) . Figure 3 . Residual turbidity of fluorite suspension as a function of settling time in the presence or absence of 40 mg / l of Corynebacterium xerosis ( pH 7 . 0 + / - 0 . 2 ) . Fig . 4 shows the flocculation results as a function of cell concentration . Good flocculation is obtained at a microorganism dosage of 20 mg / l and maximum flocculation at 40 mg / l . About 96 % of the solids present in the suspension were removed in a settling time of 1 min . Higher concentrations than 40 mg / l did not produce any improvement in floc quality . Figure 4 . Solids removal efficiency of fluorite suspensions as a function of Corynebacterium xerosis cells ( pH 7 . 0 + / - 0 . 2 , 1 min settling time ) . Fig . 5 represents flocculation efficiency as a function of pH . Also shown are data for fluorite flocculation in the absence of microorganisms . At the bacterial cell concentration used , the suspensions were readily flocculated at pH values of 4 . 0 - 9 . 0 , with an optimum pH of around 7 . 0 . Figure 5 . Solids removal efficiency of fluorite suspensions as a function of pH in the presence or absence of 40 mg / l of Corynebacterium xerosis cells ( 1 min settling time ) . Fig . 6 displays the zeta potential of C . xerosis cells and of fluorite particles as a function of pH . The C . xerosis cells had an isoelectric point at pH 2 . 0 while the isoelectric point of fluorite was near pH 10 . 0 . Negatively charged organisms should ready adhere to the positively charged fluorite at neutral pH values . At pH 7 . 0 , which gave best flocculation results , the C . xerosis cells have a zeta potential of - 30 mV and fluorite particles of about + 60 mV . Figure 6 . Zeta potential of Corynebacterium xerosis cells and fluorite particles as a function of pH . Ionic strength mantained by addition of 1x10 - 3 M NaO 3 - DISCUSSION The experimental data indicate that C . xerosis cells adhere to fluorite particles and promote flocculation of fine fluorite suspensions over a range of pH values . The quality of the flocs obtained are comparable to those produced with long chain polymers . The flocs are very " tight " and dense and contain little water . The flocculation occurs rapidly , within 1min . , showing that these bacteria are more efficient than the Arthrobacter species used by Deshpande ( 5 ) for clearing manganese mining wastewaters , which required a minimum of 30 min settling time . The mechanism of flocculation has been discussed elsewhere and primarily occurs by cell bridging ( 7 , 14 ) . This mechanism is specially efficient in systems where the microorganism is smaller or of a similar size to the particles ( 6 ) . In the present case , the median size of the particles was 12 . 5 µm and only 2 % of the fluorite has a particle size smaller than 1 µm ( approximate size of C . xerosis cells ) . In many cases , the adherence of a microorganism to a mineral surface can be predicted by a calculation based on the Derjaguin - Landau - Verwey - Overbeek ( DLVO ) theory ( 6 , 18 , 19 ) . According to this theory , the total long range interaction ( > 1nm ) between surfaces is a summation of van der Waals and coulombic interactions ( 1 , 4 ) . This theory explains the optimum flocculation behavior at neutral pH values in the fluorite - C . xerosis system . At pH 7 . 0 the fluorite has a high positive charge ( about + 60 mV ) and the bacteria a high negative charge ( about - 30 mV ) . However , a specific adsorption interaction should not be neglected . Bacteria having similar electrokinetic behavior were not able to promote the same degree of flocculation of fluorite ( 8 ) . It has been shown that some Gram - negative bacteria have specific adsorption mechanisms to solid surfaces , associated with the surface lipopolysaccharides ( 3 ) , and it is possible that a similar type of interaction may occur with this Gram - positive organism . Gram negative bacteria tested by us had no effect on settling ( results not shown ) . However , the members of the Acintomycetaceae have previously been shown to promote flocculation of fine particles ( 5 ) and one possibility is that this is due to the distinctive nature of their cell wall material ( 11 ) . In addition , the Corynebacterium group can produce short chains of cells because of incomplete separation after cell division ( 2 ) and this leads to a pseudo - polymeric structure , promoting cell bridging . The concentration of C . xerosis required to flocculate fine fluorite suspensions is lower than that of other microorganisms reported in the literature . For instance , flocculation of hematite suspensions with the yeast Candida parapsilosis requires about 50 kg / t of bioflocculant ( 12 ) , while flocculation of fluorite with C . xerosis is possible with only 4 kg / t . However , the dosage required is still higher than that used in flocculation with long synthetic polymers . A long chain polyacrylamide ( average molecular weight 1x10 6 ) flocculates some suspensions at concentrations below 0 . 1 kg / t . Microorganisms are potential low cost flocculants for solid - liquid operations in mineral processing . Further studies are necessary to increase their competitiveness with common flocculants used in the mining industry . These will include research to identify more bacterial strains able to adhere to mineral surfaces , investigate the mechanisms involved , develop procedures to isolate the biochemical fraction responsible for flocculation , and to optimize the production of the bioflocculants on large scale . ACKNOWLEDGMENTS The authors wish to acknowledge the financial support provided by following Brazilian institutions : FAPERGS ( process 96 / 1789 . 5 ) , CNPq ( process 521968 / 96 - 8 ) . RESUMO Floculação de partículas finas de fluorita com a Corynebacterium xerosis O tratamento de partículas finas dispersas em líquidos é comum em diversas indústrias e especialmente importante no processamento de minérios . A eficiência de operações de sedimentação pode ser substancialmente aumentada com a floculação . O objetivo deste trabalho foi estudar a floculação de partículas de fluorita com a bactéria Corynebacterium xerosis . A metodologia empregada para avaliar a floculação incluiu experimentos de floculação , microeletroforese e microscopia ótica . Os resultados demonstraram que as células da Corynebacterium xerosis se aderem na superfície da fluorita , promovendo a agregação das partículas . Flocos de alta qualidade podem ser obtidos rapidamente em pH 7 , 0 a uma concentração de microrganismos de 40 mg / l , dosagem esta consideravelmente menor do que aquelas previamente relatadas na literatura . Os resultados são discutidos em termos das propriedades superficiais do mineral e do microrganismo . Palavras - chave : adesão , Corynebacterium xerosis , floculação , fluorita . REFERENCES 1 . Adamson , A . W . Physical chemistry of surfaces . New York , John Wiley & Sons Inc . , 1990 . 2 . Atlas , R . M . Principles of Microbiology . Dubuque : Wm . C . Brown Publishers , 1997 . 3 . Beech , I . B . ; Gaylarde , C . C . Adhesion of Desulfovibrio desulfuricans and Pseudomonas fluorescens to mild steel surfaces . J . Appl . Bacteriol . , 67 : 201 - 207 , 1989 . 4 . Characklis , W . G . ; Marshall , K . C . In : Biofilms . New York , John Wiley & Sons Inc . , 1990 , p . 348 - 349 . 5 . Deshpande , H . A . Microbe - manganese interactions in iron - manganese mining areas in India . In : Karavaiko , G . I . ; Rossi , G . ; Avakayan , Z . A . ( eds . ) . Biohydrometallurgy . Moscow , Centre for International Projects , USSR State Committee for Environmental Protection , 1990 , p . 312 - 319 . 6 . Daniels , S . L . Mechanisms involved in sorption of microorganisms to solid surfaces . In : Britton , G . ; Marshall , K . C ( eds . ) . Adsorption of Microorganisms to Surfaces . London , John Wiley and Sons , 1980 , p . 7 - 58 . 7 . Dübel , J . ; Smith , R . W . ; Misra , M . ; Chen , S . Microorganisms as chemical reagents : the hematite system . Min . Eng . , 5 : 574 - 556 , 1992 . 8 . Haas , S . R . ; Schneider , I . A . H . Seleção de bactérias para a floculação de finos de fluorita . II Encontro Nacional de Microbiologia Aplicada ao Meio Ambiente , Florianópolis , 1998 . In press . 9 . Hunter , R . J . Zeta potential in colloid science . London , Academic Press , 1981 . 10 . Kitchener , J . A . Flocculation in mineral processing . In : Ives , K . J . ( ed . ) . The scientific basis of flocculation . Alphen aan den Rijn , Netherlands , 1978 , p . 283 - 328 . 11 . Poindexter , J . S . Microbiology - an introduction to protists . New York , MacMillan , 1971 . p . 194 . 12 . Schneider , I . A . H . ; Misra , M . ; Smith , R . W . Bioflocculation of hematite suspensions with products from yeast cell rupture . Devel . Chem . Eng . Min . Process . , 4 : 248 - 252 , 1994 . 13 . Schneider , I . A . H . ; Misra , M . ; Smith , R . W . Bioflocculation of fine mineral suspensions by Candida parapsilosis and its sonication products . In : Reagents for Better Metallurgy . SME , 1994 , 293 - 301 . 14 . Smith , R . W . ; Misra , M . Bacterial flocculation of phosphate wastes using a hydrophobic bacterium . In : Smith R . W . ; Misra , M . ( eds . ) . Minerals bioprocessing , Warrendale , TMS , 1991 , p . 747 - 756 . 15 . Smith , R . W . Liquid and Solid Wastes from Mineral Processing Plants . Min . Proc . Extrac . Metall . Rev . , 16 : 1 - 22 , 1996 . 16 . Somasundaran , P . Principles of flocculation , dispersion , and selective flocculation . In : Somasundaran , P . ( ed . ) . Fine particles processing . New York , AIME , 1980 , p . 947 - 976 . 17 . van Loosdrecht , M . C . M . ; Lyklema , J . ; Norde , W . ; Schraa G . ; Zehnder , A . J . B . The role of bacterial cell wall hydrophobicity in adhesion . Appl . Environ . Microbiol . , 53 : 1893 - 1897 , 1987 . [ Medline ] 18 . van Loosdrecht , M . C . M . ; Lyklema , J . ; Norde , W . ; Schraa , G ; Zehnder , A . J . B . Electrophoretic mobility and hydrophobicity as a measure to predict the initial steps of bacterial adhesion . Appl . Environ . Microbiol . , 53 : 1898 - 1901 , 1987 . 19 . van Loosdrech , M . C . M . ; Lyklema , J . ; Norde , W . ; Zehnder , A . J . B . Bacterial adhesion : a physicochemical approach . Microb . Ecol . , 17 : 1 - 15 , 1989 . * Corresponding author . Mailing address : FEAR , Universidade de Passo Fundo , Campus , Bairro São José , CEP 99001 - 970 , Passo Fundo , RS , Brasil . Fax : ( + 554 ) 316 - 8211 . E - mail ivoandre @ upf . tche . br © 2006 SBM Av . Prof . Lineu Prestes , 1374 Cidade Universitária 05508 - 900 São Paulo SP - Brazil Tel . / Fax : ( 55 11 ) 813 . 9647

It is well known that mitochondria are the main site for ATP generation within most tissues . However , mitochondria also participate in a surprising number of alternative activities , including intracellular Ca 2 + regulation , thermogenesis and the control of apoptosis . In addition , mitochondria are the main cellular generators of reactive oxygen species , and may trigger necrotic cell death under conditions of oxidative stress . This review concentrates on these alternative mitochondrial functions , and their role in cell physiopathology . Key words : mitochondrial permeability transition , uncoupling proteins , alternative oxidase , cardioprotection , free radicals , aging Introduction In order to continuously generate ATP , mitochondria remove electrons from reduced substrates and transfer them to oxygen through a specialized group of respiratory complexes . According to Peter Mitchell ' s findings ( 1 ) , the energy generated in this process is used to move protons from the mitochondrial matrix to the mitochondrial intermembrane space in a process known as proton pumping . Since the inner mitochondrial membrane is normally highly impermeable to protons , respiratory chain - generated proton pumping produces a proton potential across the inner mitochondrial membrane , which is used by the mitochondrial ATP synthase to generate ATP from ADP plus inorganic phosphate . ATP is thus produced in a highly conservative fashion , a process essential for cell physiology . Although ATP synthesis is the primary role of mitochondria , it is not the only function of these organelles . Indeed , many studies have shown that mitochondria present a surprising diversity of activities within the cell . This is compatible with the recent finding that mitochondria may have originated at essentially the same time as the nuclear component of the eukaryotic cell rather than in a separate , subsequent event ( 2 ) . This review focuses on four of the main alternative mitochondrial functions and recent findings about them . The mitochondrial activities discussed here include heat generation , intracellular Ca 2 + regulation , reactive oxygen species generation and the triggering of cell death . Thermogenesis Newborn , cold adapted and hibernating mammals have the ability to maintain their body temperature in a manner independent of shivering , but secondary to an adrenergically stimulated increase in respiration ( 3 ) . Adrenergic stimuli in these animals promote a remarkable increase in blood flow to brown adipose tissue , which is the main tissue responsible for non - shivering thermogenesis ( 4 ) . Interestingly , mitochondria within brown adipose tissue cells behave rather differently from those in other tissues : ATP synthesis is limited , the membrane potential is reduced and respiratory rates are increased ( 5 , 6 ) . This suggests that these mitochondria have inner membranes with a higher permeability to protons . In fact , brown adipose tissue mitochondria contain the uncoupling protein - 1 ( UcP1 ) , a 32 - kDa inner membrane protein which stimulates proton conductance ( 7 ) . Ironically , UcP1 itself , when isolated and incorporated into liposomes , does not transport protons . Rather , it is an anion transporter , and promotes mitochondrial uncoupling by transporting fatty acid anions across the inner mitochondrial membrane in a manner regulated by purine nucleotides ( 8 , 9 ) . These fatty acids then protonate and flip - flop electroneutrally across the lipid phase of the inner mitochondrial membrane , leading to increased mitochondrial proton permeability ( see Scheme 1 ) . As a consequence of this increased inner mitochondrial permeability to protons , part of the energy stored as membrane potential generated by the mitochondrial respiratory chain is released in the form of heat , when protons return to the mitochondrial matrix . Scheme 1 - Energy - dissipating pathways in mitochondria . The mitochondrial respiratory chain ( resp . chain ) , located in the inner mitochondrial membrane , reduces oxygen to water to generate a proton gradient , essential for ATP synthesis . However , oxygen reduction may also be promoted by the plant mitochondrial alternative oxidase ( alt . ox . ) in a dissipating process which may not generate a proton gradient . The proton gradient is decreased by the activity of uncoupling proteins ( UcP ) , which translocate fatty acid anions from the mitochondrial matrix to the cytoplasmic surface of the inner mitochondrial membrane . Fatty acid anions then combine with protons , and flip - flop electroneutrally across the lipid bilayer . [ View larger version of this image ( 10 K GIF file ) ] UcP1 was discovered in the 1970s , and was thought to be the only protein of this kind for over 20 years , until Vercesi and co - workers ( 10 ) described the existence of an uncoupling protein in mitochondria isolated from potato tubers , and later in a variety of other plant mitochondria ( 11 ) . This uncoupling protein , known as plant uncoupling mitochondrial protein ( PUMP ) functions similarly to UcP1 ( 12 ) , and is involved in the heat generation necessary for fruit ripening ( 13 ) . Interestingly , in addition to PUMP , plant mitochondria may also contain the alternative oxidase , a mitochondrial respiratory pathway from ubiquinol to oxygen which does not promote proton pumping , and is , therefore , dissipative ( 14 ; see Scheme 1 ) . The mitochondrial alternative oxidase is involved in the heat generation of thermogenic plants such as the skunk cabbage , and can be inhibited by salicylhydroxamic acid ( 14 ) . The presence of two dissipative pathways in plants is curious , and raises questions regarding the regulation of these pathways . Although the contribution of each pathway under different conditions of plant thermogenesis has not been well established , it now seems clear that these pathways do not operate simultaneously ( 15 ) . Following the characterization of PUMP , three sequences corresponding to mammalian mitochondrial proteins homologous to UcP1 were found to be expressed ( in quantities much lower than UcP1 ) ubiquitously ( UcP2 ; 16 ) in skeletal muscle ( UcP3 ; 17 , 18 ) or in the brain ( UcP4 ; 19 ) . Recent studies have determined that UcP2 and UcP3 are capable of translocating fatty acids , confirming that they are uncoupling proteins ( 20 ) . The exact relevance of these newly characterized mammalian uncoupling proteins is still not completely clear , but some interesting studies suggest that they may be involved in the control of body weight . In this sense , it has been shown that UcP3 gene expression is stimulated by a high - fat diet ( 21 ) , and reduced by dietary restriction ( 22 , 23 ) . Reduced UcP3 expression is also linked to obesity - related non - insulin dependent diabetes ( 24 ) . The relationship between UcP2 and body weight is suggested by the demonstration that leptin , which reduces body weight by decreasing food intake and increasing thermogenesis , induces UcP2 gene expression ( 25 ) . Regulation of intracellular Ca 2 + homeostasis Cytosolic Ca 2 + levels are maintained at concentrations approximately 10 , 000 times lower than the Ca 2 + concentrations in the extracellular medium ( for review , see 26 , 27 ) . This process is controlled mainly by plasma membrane and endoplasmic reticulum Ca 2 + ATPases and by Ca 2 + exchanges in a process that requires energy . Clearly , if mitochondria become dysfunctional and ATP synthesis is impaired , cellular Ca 2 + homeostasis will be affected . In addition to providing the energy necessary for intracellular Ca 2 + regulation , mitochondria themselves participate in the control of intracellular Ca 2 + concentrations . In the presence of a membrane potential , cations can be accumulated in mitochondria down the membrane potential , as long as there is a transport pathway . Thus , mitochondria from vertebrates are capable of actively accumulating Ca 2 + ions , since they possess a Ca 2 + uniporter ( for review , see 26 , 27 ) . Ca 2 + uptake by mitochondria depends on the presence of a membrane potential which provides the driving force for accumulation ( the negative intramitochondrial charge ; see Scheme 2 ) , and is inhibited by submicromolar concentrations of ruthenium red , an inhibitor of the Ca 2 + uniporter ( 26 , 27 ) . Ruthenium red also inhibits a second mechanism for Ca 2 + uptake into mitochondria through the rapid Ca 2 + uptake mode ( RaM ; 28 ) , although 10 times higher concentrations are required . The channel which promotes RaM Ca 2 + uptake has not been characterized , and may be the Ca 2 + uniporter itself , operating under a more rapid conductivity mode . However , the distinct sensitivity of RaM to inhibitors of the Ca 2 + uniporter and mainly the lack of sensitivity to Mg 2 + , which inhibits Ca 2 + uptake via the Ca 2 + uniporter ( 28 ) , suggest that RaM may involve an independent channel . Scheme 2 - Mitochondrial Ca 2 + transport . Mitochondrial Ca 2 + influx is mediated by the inner membrane uniporter or RaM and driven by the proton electrochemical potential . Ca 2 + efflux is promoted by the Ca 2 + / 2H + and Ca 2 + / 2Na + ( or Ca 2 + / 3Na + ) exchange . Na + redistribution is maintained by the Na + / H + antiporter . resp . chain , Respiratory chain . [ View larger version of this image ( 14 K GIF file ) ] The total Ca 2 + accumulation capacity of mitochondria can be quite high , as long as inorganic phosphate is accumulated in parallel , to compensate for changes in the mitochondrial pH gradient across the inner mitochondrial membrane , and the inner membrane is not permeabilized by the mitochondrial permeability transition ( MPT ) ( see discussion below ) . Although accumulation capacity is high , the affinity for mitochondrial Ca 2 + uptake is low , requiring extramitochondrial Ca 2 + concentrations of at least 200 - 300 nM ( 26 , 27 ) . Because of this low affinity of the mitochondrial Ca 2 + uptake and the typical cytosolic free Ca 2 + concentrations under resting conditions ( < 100 nM ) , mitochondrial Ca 2 + uptake was believed not to occur inside the cell under physiological conditions . This hypothesis has now been overruled by observations of Ca 2 + uptake into mitochondria within intact cells ( 29 - 31 ) . It is possible that mitochondria take up Ca 2 + during periodic increases in intracellular Ca 2 + concentrations ( Ca 2 + spikes ; 29 ) , or through a close interaction with the endoplasmic reticulum Ca 2 + release pathways ( 30 ) and plasma membrane channels ( 32 ) . Confirming that Ca 2 + uptake by mitochondria is important for cell function , mitochondria have developed an elaborate Ca 2 + release system composed of two transporters : the Ca 2 + / 2H + exchange , and the Ca 2 + / 2Na + ( or Ca 2 + / 3Na + ; 33 ) exchange . As shown in Scheme 2 , Ca 2 + efflux is energetically uphill , and thus dissipates the mitochondrial proton gradient . Ca 2 + efflux through these carriers is 500 - 1000 times slower than Ca 2 + uptake through the uniporter , and can be inhibited by respiratory inhibitors and uncouplers ( Ca 2 + / 2H + exchange ) or diltiazem , verapamil , clonazepam , amiodarone , Mg 2 + and tetraphenylphosphonium ( Ca 2 + / 2Na + exchange ; for reviews , see 26 , 27 ) . The physiological role of Ca 2 + may be related to the regulation of respiratory activity . The presence of Ca 2 + in the mitochondrial matrix stimulates respiration by affecting three mitochondrial enzymes : pyruvate dehydrogenase phosphatase , NAD + - linked isocitrate dehydrogenase and 2 - oxoglutarate dehydrogenase . This enzymatic activation justifies the enhanced citric acid cycle activity and respiratory rates observed in tissues upon adrenergic stimulation , which leads to elevated intracellular Ca 2 + concentrations ( 34 ) . Although the presence of approximately 1 µM Ca 2 + in the mitochondrial matrix has the beneficial effect of stimulating respiratory activity , intramitochondrial Ca 2 + must be carefully regulated within the cell , since excessive mitochondrial Ca 2 + accumulation may lead to a nonselective inner membrane permeabilization , known as mitochondrial permeability transition ( MPT ; see 35 - 37 ) . MPT is a Ca 2 + - triggered permeabilization of the inner mitochondrial membrane to protons , ions and solutes of up to 1500 kDa . In isolated mitochondria , the Ca 2 + quantities necessary for MPT triggering vary widely with distinct experimental conditions and from one tissue to another . MPT is thus more likely to occur ( or occurs in the presence of smaller Ca 2 + loads ) in the presence of MPT inducers such as inorganic phosphate , pyridine nucleotide oxidants and dithiol reagents . On the other hand , ADP , Mg 2 + , antioxidants and cyclosporin A ( known as a specific MPT inhibitor ) prevent MPT . In vitro , mitochondrial membrane permeabilization secondary to MPT results in a cyclosporin - A sensitive drop in mitochondrial membrane potential , and the release of Ca 2 + accumulated previously , a process reversible through Ca 2 + chelation within a few minutes after its onset . In isotonic media , MPT also results in colloidosmotic swelling of isolated mitochondria due to the high protein content of the mitochondrial matrix . Undoubtedly , MPT occurring under these conditions results in irreversible mitochondrial dysfunction ( see further discussion under " Triggering cell death " ) . However , the characteristics of MPT under distinct experimental conditions are very variable , and a more selective ( < 300 kDa ) " low - conductance " mode of the permeability transition has been observed ( for review , see 38 ) . According to the model devised by Ichas and Mazat ( 38 ) , the low conductance mode of MPT does not involve mitochondrial swelling , is fully reversible upon matrix acidification secondary to the mitochondrial permeabilization to protons , and may be a mechanism through which Ca 2 + is quickly released from the mitochondrial matrix . In the intact cell , low - conductance MPT pores may participate in the regulation of cytoplasmic Ca 2 + signals ( 38 , 39 ) . Reactive oxygen species ( ROS ) generation As a by - product of electron transport , a small amount of molecular oxygen ( O 2 ) undergoes monoelectronic reduction at intermediate steps of the mitochondrial respiratory chain , resulting in the generation of the superoxide radical ( O 2 - · ) . This small but continuous " electron leak " makes mitochondria the main generation site for reactive oxygen species within most cells . Catalyzed by intramitochondrial superoxide dismutase , O 2 - · may form hydrogen peroxide ( H 2 O 2 ) , and subsequently hydroxyl radicals ( OH · - formed through the Fe 2 + - dependent Fenton ' s reaction ) and other ROS ( see Scheme 3 and Refs . 37 , 40 ) . Scheme 3 - Mitochondrial generation of ROS . The respiratory chain ( resp . chain ) produces superoxide radicals ( O 2 - · ) , which generate hydrogen peroxide ( H 2 O 2 ) and hydroxyl radicals ( HO · ) . Mitochondrial nitric oxide synthase ( NOS ) produces nitric oxide ( NO · ) , which combines with O 2 - · to generate peroxinitrite ( ONOO - ) . All these ROS may cause mitochondrial and cellular damage if present in excess . MPT , Mitochondrial permeability transition . [ View larger version of this image ( 12 K GIF file ) ] Normally , respiratory - chain generated ROS are detoxified by the efficient mitochondrial antioxidant systems ( see Scheme 3 and Ref . 40 for review ) , and do not cause any permanent damage to mitochondria . However , under nonphysiological conditions , or over time , mitochondrially generated ROS may lead to both mitochondrial and cellular damage . As an example , Ca 2 + - triggered MPT , which is an early step in some conditions leading to cell death , is a result of mitochondrial oxidative stress ( for reviews , see 37 , 40 ) . Also , glutamate neurotoxicity mediated by excessive stimulation of N - methyl - D - aspartate receptors occurs secondarily to excessive mitochondrial Ca 2 + uptake and oxidative stress ( 41 ) . Finally , many important results of mitochondrial oxidative stress may be observed during aging , when damage to mitochondrial DNA accumulates over time , and may result in alterations in the synthesis of components of the respiratory chain ( 42 ) . Monoelectronic reduction of oxygen resulting in mitochondrial ROS generation occurs mainly at the level of complexes I and III of the respiratory chain , most probably by donation of an electron from intermediately reduced forms of ubiquinones ( 43 ) . Since complex IV is not an important site for O 2 - · generation , mitochondria must not necessarily respire to generate ROS . In fact , certain respiratory inhibitors such as antimycin A may increase mitochondrial ROS generation as they lead to an accumulation of intermediately reduced ubiquinones . Other conditions that favor mitochondrial ROS generation are high membrane potentials , hyperoxia , excessive Ca 2 + uptake and anoxia / reoxygenation ( for review , see 40 ) . Both increased cytosolic Ca 2 + levels and anoxia / reoxygenation of mitochondria occur under conditions of ischemia / reperfusion in vivo . Indeed , reperfusion injury has been closely associated with mitochondrial oxidative stress and MPT ( 44 , 45 ) . In addition to producing O 2 - · through electron leakage in the respiratory chain , mitochondria also produce nitric oxide ( NO · ) through the activity of a constitutive nitric oxide synthase similar to the inducible cellular nitric oxide synthase . NO · levels regulate mitochondrial respiratory activity , but it is not yet known if this is the principal function of mitochondrial NO · ( 46 ) . Triggering cell death Not surprisingly , mitochondrial dysfunction and consequent cellular ATP depletion can result in cell death . Indeed , necrotic cell death under conditions such as ischemia / reperfusion is strongly inhibited by preventing associated mitochondrial alterations , suggesting that mitochondrial dysfunction is the primary trigger for cell death under these conditions ( 44 , 45 , 47 ) . Mitochondrial dysfunctions which may potentially lead to necrosis include MPT , respiratory inhibition , uncoupling between respiration and oxidative phosphorylation , and excessive ROS generation . Excessive ROS generation by mitochondria may contribute to necrotic cell death even if cellular ATP is maintained by affecting intracellular Ca 2 + homeostasis ( 41 ) . However , mitochondrially triggered cell death is not always necrotic . Recent evidence has identified these organelles as regulators of the highly complex process of energy dependent apoptotic cell death ( see Scheme 4 ) . Two mitochondrial intermembrane - space proteins , cytochrome c and the apoptosis inducing factor ( AIF ) , have been shown to migrate from a mitochondrial to a cytosolic location shortly before hallmarks of apoptosis are observed ( 48 , 49 ) . Also , microinjection of both proteins into healthy cells results in the induction of apoptosis ( 50 , 51 ) . In addition to cytochrome c and AIF , mitochondria contain pro - caspase 9 , pro - caspase 3 and pro - caspase 2 ( 52 , 53 ) which , when released into the cytosol and cleaved , act as aspartate - specific proteases that initiate the apoptotic cascade . Scheme 4 - Mitochondria can trigger cell death . Intact mitochondria contain cytochrome c ( circles ) and the apoptosis inducing factor ( AIF , lines ) in the intermembrane space . AIF is released from mitochondria after the latter undergo nonselective inner membrane permeabilization secondary to MPT , which results in mitochondrial swelling and outer membrane disruption . Cytochrome c may be released into the cytosol after MPT , upon Bax targeting to mitochondria or treatment with Ca 2 + . Once in the cytosol , both cytochrome c and AIF trigger apoptosis . MPT may also promote necrosis , since it results in mitochondrial dysfunction . MPT , Mitochondrial permeability transition . [ View larger version of this image ( 19 K GIF file ) ] Further evidence that mitochondria participate in apoptosis is provided by the location of Bcl - 2 family proteins within the cell . bcl - 2 was originally identified as a gene related to oncogenesis in B - cell lymphocytes , and later found to express a protein ( Bcl - 2 ) which is part of a family of proteins presenting both anti - and pro - apoptotic activities . Bcl - 2 itself is predominantly located on the outer mitochondrial membrane , and its main antiapoptotic effect seems to be the inhibition of mitochondrial cytochrome c and AIF release ( 48 , 49 ) . On the other hand , pro - apoptotic Bcl - 2 family proteins such as Bax and Bid are primarily cytosolic , and upon apoptotic stimuli assume a mitochondrial location , an event which coincides with the release of mitochondrial cytochrome c ( 54 , 55 ) . Although the latest evidence has been almost unanimous in showing that mitochondria have an important role in the control of apoptosis , the exact mechanisms by which mitochondria promote this regulation are not yet fully understood . As an example , it seems clear that the occurrence of MPT in vitro promotes the release of mitochondrial cytochrome c , but it is still controversial if this is the primary mechanism of cytochrome c release within cells . Also , the mechanism by which Bcl - 2 family proteins interact with mitochondria and promote or prevent the release of cytochrome c has not been well established . These and other still unresolved points of interest should be further investigated within the next few years . In agreement with studies showing a role for mitochondria in the initial steps of both necrosis and apoptosis , mitochondrially active drugs have been shown to be cardioprotective . Of great interest in this line of study is the evidence that openers of the mitochondrial ( but not plasma membrane ) ATP - inhibited K + channels , such as diazoxide , present cardioprotective effects . In addition , 5 - OH decanoate , a specific mitochondrial K + channel inhibitor , prevents ischemic preconditioning and the cardioprotective effects of K + channel openers ( 56 ) . These interesting experiments show that the increased flux of K + into mitochondria through the ATP - sensitive K + channel is cytoprotective . Since the primary effect of K + influx is to promote a small increase in mitochondrial volume ( which does not result in outer mitochondrial membrane rupture ) , cardioprotection promoted by diazoxide may be the result of increased ß oxidation of fatty acids and respiratory activity secondary to increased mitochondrial volume ( 57 ) . Inhibitors of the mitochondrial permeability transition are also cytoprotective in various in vivo and in vitro cell death models ( 44 , 45 , 47 ) . It is believed that these conditions lead to intracellular Ca 2 + increases , with excessive mitochondrial Ca 2 + uptake , oxidative stress and MPT . Preventing MPT avoids ATP depletion secondary to mitochondrial dysfunction , and protects from necrotic cell death under these conditions . Final remarks As summarized here , mitochondria present a variety of important functions in addition to producing ATP . As an example , mitochondria present regulated pathways that promote energy dissipation , such as the mitochondrial uncoupling proteins and the alternative oxidase , which seem to present the main function of promoting nonshivering thermogenesis . Thermogenesis is ultimately achieved when the chemical energy contained in reduced substrates is released , but not explored for ATP synthesis . It is also well established that mitochondria actively take up Ca 2 + within intact cells , and that this Ca 2 + uptake may both regulate mitochondrial respiratory parameters and influence cytosolic Ca 2 + transients . Mitochondrial Ca 2 + uptake occurs through the Ca 2 + uniporter or RaM , while Ca 2 + release occurs through exchange with Na + and H + or , eventually , the low - conductance MPT pore . In addition , mitochondria constantly produce ROS , and have thus developed an efficient antioxidant system . However , imbalances in ROS generation or detoxification systems may result in a condition of oxidative stress . Under these conditions , damage to both mitochondrial and cellular constituents may occur . Functional mitochondrial impairment leading to cellular ATP depletion is an initial step in many models for necrotic cell death . Mitochondria may also trigger ATP - dependent apoptotic cell death through the release of pro - apoptotic proteins from the mitochondrial intermembrane space into the cytosol . These findings agree with the characterization of the cytoprotective effects of mitochondrially active drugs ( 44 , 45 , 47 ) . Thus , alternative mitochondrial activities , in addition to ATP synthesis , are important factors in cell physiology , and may tip the balance between cell survival and death . Further knowledge about these alternative mitochondrial activities will contribute to the development of more efficient mitochondrially targeted drugs capable of better preventing ischemic injury . The modulation of mitochondrial activities may also be effective in the treatment of obesity and diabetes . References 1 . Mitchell P & Moyle J ( 1965 ) . Stoichiometry of proton translocation through the respiratory chain and adenosine triphosphatase systems of rat liver mitochondria . Nature , 208 : 147 - 151 . 2 . Gray MW , Burger G & Lang BF ( 1999 ) . Mitochondrial evolution . Science , 283 : 1476 - 1481 . [ Medline ] 3 . Nicholls DG & Locke RM ( 1984 ) . Thermogenic mechanisms in brown fat . Physiological Reviews , 64 : 1 - 64 . [ Medline ] 4 . Foster DO & Frydman ML ( 1978 ) . Brown adipose tissue : the dominant site of nonshivering thermogenesis in the rat . Experientia Supplementum , 32 : 147 - 151 . 5 . Smith RE , Roberts JC & Hittelman KJ ( 1966 ) . Nonphosphorylating respiration of mitochondria from brown adipose tissue of rats . Science , 154 : 653 - 654 . [ Medline ] 6 . Nicholls DG ( 1976 ) . The bioenergetics of brown adipose tissue mitochondria . FEBS Letters , 61 : 103 - 110 . [ Medline ] 7 . Nicholls DG , Bernson VS & Heaton GM ( 1978 ) . The identification of the component in the inner membrane of brown adipose tissue mitochondria responsible for regulating energy dissipation . Experientia Supplementum , 32 : 89 - 93 . 8 . Jezek P , Orosz DE , Modriansky M & Garlid KD ( 1994 ) . Transport of anions and protons by the mitochondrial uncoupling protein and its regulation by nucleotides and fatty acids . A new look at old hypotheses . Journal of Biological Chemistry , 269 : 26184 - 26190 . [ Medline ] 9 . Garlid KD , Orosz DE , Modriansky M , Vassanelli S & Jezek P ( 1996 ) . On the mechanism of fatty acid - induced proton transport by mitochondrial uncoupling protein . Journal of Biological Chemistry , 271 : 2615 - 2620 . 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The regulation and nature of the cyanide - resistant alternative oxidase of plant mitochondria . Biochimica et Biophysica Acta , 1059 : 121 - 140 . 15 . Sluse FE , Almeida AM , Jarmuszkiewicz W & Vercesi AE ( 1998 ) . Free fatty acids regulate the uncoupling protein and alternative oxidase activities in plant mitochondria . FEBS Letters , 433 : 237 - 240 . [ Medline ] 16 . Fleury C , Neverova M , Collins S , Raimbault S , Champigny O , Levi - Meyrueis C , Bouillaud F , Seldin MF , Surwit RS , Ricquier D & Warden CH ( 1997 ) . Uncoupling protein - 2 : a novel gene linked to obesity and hyperinsulinemia . Nature Genetics , 15 : 269 - 272 . [ Medline ] 17 . Boss O , Samec S , Paoloni - Giacobino A , Rossier C , Dulloo A , Seydoux J , Muzzin P & Giacobino JP ( 1997 ) . Uncoupling protein - 3 : a new member of the mitochondrial carrier family with tissue - specific expression . FEBS Letters , 408 : 39 - 42 . [ Medline ] 18 . Vidal - Puig A , Solanes G , Grujic D , Flier JS & Lowell BB ( 1997 ) . UCP3 : an uncoupling protein homologue expressed preferentially and abundantly in skeletal muscle and brown adipose tissue . Biochemical and Biophysical Research Communications , 235 : 79 - 82 . [ Medline ] 19 . Mao W , Yu XX , Zhong A , Li W , Brush J , Sherwood SW , Adams SH & Pan G ( 1999 ) . UCP4 , a novel brain - specific mitochondrial protein that reduces membrane potential in mammalian cells . FEBS Letters , 443 : 326 - 330 . [ Medline ] 20 . Jaburek M , Varecha M , Gimeno RE , Dembski M , Jezek P , Zhang M , Burn P , Tartaglia LA & Garlid KD ( 1999 ) . Transport function and regulation of mitochondrial uncoupling proteins 2 and 3 . Journal of Biological Chemistry , 274 : 26003 - 26007 . [ Medline ] 21 . Brun S , Carmona MC , Mampel T , Vinas O , Giralt M , Iglesias R & Villarroya F ( 1999 ) . Uncoupling protein - 3 gene expression in skeletal muscle during development is regulated by nutritional factors that alter circulating non - esterified fatty acids . FEBS Letters , 453 : 205 - 209 . [ Medline ] 22 . Millet L , Vidal H , Larrouy D , Andreelli F , Laville M & Langin D ( 1998 ) . mRNA expression of the long and short forms of uncoupling protein - 3 in obese and lean humans . Diabetologia , 41 : 829 - 832 . [ Medline ] 23 . Esterbauer H , Oberkofler H , Dallinger G , Breban D , Hell E , Krempler F & Patsch W ( 1999 ) . Uncoupling protein - 3 gene expression : reduced skeletal muscle mRNA in obese humans during pronounced weight loss . Diabetologia , 42 : 302 - 309 . [ Medline ] 24 . Krook A , Digby J , O ' Rahilly S , Zierath JR & Wallberg - Henriksson H ( 1998 ) . Uncoupling protein 3 is reduced in skeletal muscle of NIDDM patients . Diabetes , 47 : 1528 - 1531 . [ Medline ] 25 . Zhou YT , Shimabukuro M , Koyama K , Lee Y , Wang MY , Trieu F , Newgard CB & Unger RH ( 1997 ) . Induction by leptin of uncoupling protein - 2 and enzymes of fatty acid oxidation . Proceedings of the National Academy of Sciences , USA , 94 : 6386 - 6390 . [ Medline ] 26 . Gunter TE & Pfeiffer DR ( 1990 ) . Mechanisms by which mitochondria transport calcium . American Journal of Physiology , 258 : C755 - C786 . [ Medline ] 27 . Gunter KK & Gunter TE ( 1994 ) . Transport of calcium by mitochondria . Journal of Bioenergetics and Biomembranes , 26 : 471 - 485 . [ Medline ] 28 . Gunter TE , Buntinas L , Sparagna GC & Gunter KK ( 1998 ) . The Ca 2 + transport mechanisms of mitochondria and Ca 2 + uptake from physiological - type Ca 2 + transients . Biochimica et Biophysica Acta , 1366 : 5 - 15 . 29 . Rizzuto R , Simpson AW , Brini M & Pozzan T ( 1992 ) . Rapid changes of mitochondrial Ca 2 + revealed by specifically targeted recombinant aequorin . Nature , 358 : 325 - 327 . [ Medline ] 30 . Rizzuto R , Brini M , Murgia M & Pozzan T ( 1993 ) . Microdomains with high Ca 2 + close to IP3 - sensitive channels that are sensed by neighboring mitochondria . Science , 262 : 744 - 747 . [ Medline ] 31 . Bassani RA , Bassani JW & Bers DM ( 1992 ) . Mitochondrial and sarcolemmal Ca 2 + transport reduce [ Ca 2 + ] i during caffeine contractures in rabbit cardiac myocytes . Journal of Physiology , 453 : 591 - 608 . [ Medline ] 32 . Peng TI & Greenamyre JT ( 1998 ) . Privileged access to mitochondria of calcium influx through N - methyl - D - aspartate receptors . Molecular Pharmacology , 53 : 974 - 980 . [ Medline ] 33 . Jung DW , Baysal K & Brierley GP ( 1995 ) . The sodium - calcium antiport of heart mitochondria is not electroneutral . Journal of Biological Chemistry , 270 : 672 - 678 . [ Medline ] 34 . Hansford RG ( 1994 ) . Physiological role of mitochondrial Ca 2 + transport . Journal of Bioenergetics and Biomembranes , 26 : 495 - 508 . [ Medline ] 35 . Bernardi P ( 1996 ) . The permeability transition pore . Control points of a cyclosporin A - sensitive mitochondrial channel involved in cell death . Biochimica et Biophysica Acta , 1275 : 5 - 9 . 36 . Halestrap AP , Connern CP , Griffiths EJ & Kerr PM ( 1997 ) . Cyclosporin A binding to mitochondrial cyclophilin inhibits the permeability transition pore and protects hearts from ischaemia / reperfusion injury . Molecular and Cellular Biochemistry , 174 : 167 - 172 . [ Medline ] 37 . Kowaltowski AJ & Vercesi AE ( 1999 ) . Mitochondrial damage induced by conditions of oxidative stress . Free Radicals in Biology and Medicine , 26 : 463 - 471 . 38 . Ichas F & Mazat JP ( 1998 ) . From calcium signaling to cell death : two conformations for the mitochondrial permeability transition pore . Switching from low - to high - conductance state . Biochimica et Biophysica Acta , 1366 : 33 - 50 . 39 . Smaili SS & Russell JT ( 1999 ) . The permeability transition pore regulates both mitochondrial membrane potential and agonist - evoked Ca 2 + signals in oligodendrocyte progenitors . Cell Calcium , 26 ( in press ) . [ Medline ] 40 . Kowaltowski AJ & Vercesi AE ( 2000 ) . Reactive oxygen generation by mitochondria . In : Lemasters JJ & Nieminem A - L ( Editors ) , Mitochondria in Pathogenisis . Plenum Publishing Corporation , New York ( in press ) . 41 . Castilho RF , Ward MW & Nicholls DG ( 1999 ) . Oxidative stress , mitochondrial function , and acute glutamate excitotoxicity in cultured cerebellar granule cells . Journal of Neurochemistry , 72 : 1394 - 1401 . [ Medline ] 42 . Wei YH , Lu CY , Lee HC , Pang CY & Ma YS ( 1998 ) . Oxidative damage and mutation to mitochondrial DNA and age - dependent decline of mitochondrial respiratory function . Annals of the New York Academy of Sciences , 854 : 155 - 170 . 43 . Cadenas E , Boveris A , Ragan CI & Stoppani AO ( 1977 ) . Production of superoxide radicals and hydrogen peroxide by NADH - ubiquinone reductase and ubiquinol - cytochrome c reductase from beef - heart mitochondria . Archives of Biochemistry and Biophysics , 180 : 248 - 257 . [ Medline ] 44 . Griffiths EJ & Halestrap AP ( 1993 ) . Protection by Cyclosporin A of ischemia / reperfusion - induced damage in isolated rat hearts . Journal of Molecular and Cellular Cardiology , 25 : 1461 - 1469 . [ Medline ] 45 . Griffiths EJ & Halestrap AP ( 1995 ) . Mitochondrial non - specific pores remain closed during cardiac ischaemia , but open upon reperfusion . Biochemical Journal , 307 : 93 - 98 . 46 . Giulivi C ( 1998 ) . Functional implications of nitric oxide produced by mitochondria in mitochondrial metabolism . Biochemical Journal , 332 : 673 - 679 . 47 . Friberg H , Ferrand - Drake M , Bengtsson F , Halestrap AP & Wieloch T ( 1998 ) . Cyclosporin A , but not FK 506 , protects mitochondria and neurons against hypoglycemic damage and implicates the mitochondrial permeability transition in cell death . Journal of Neuroscience , 18 : 5151 - 5159 . [ Medline ] 48 . Green DR & Reed JC ( 1998 ) . Mitochondria and apoptosis . Science , 281 : 1309 - 1312 . [ Medline ] 49 . Susin SA , Zamzami N & Kroemer G ( 1998 ) . Mitochondria as regulators of apoptosis : doubt no more . Biochimica et Biophysica Acta , 1366 : 151 - 165 . 50 . Zhivotovsky B , Orrenius S , Brustugun OT & Doskeland SO ( 1998 ) . Injected cytochrome c induces apoptosis . Nature , 391 : 449 - 450 . [ Medline ] 51 . Susin SA , Lorenzo HK , Zamzami N , Marzo I , Snow BE , Brothers GM , Mangion J , Jacotot E , Costantini P , Loeffler M , Larochette N , Goodlett DR , Aebersold R , Siderovski DP , Penninger JM & Kroemer G ( 1999 ) . Molecular characterization of mitochondrial apoptosis - inducing factor . Nature , 397 : 441 - 446 . [ Medline ] 52 . Susin SA , Lorenzo HK , Zamzami N , Marzo I , Brenner C , Larochette N , Prevost MC , Alzari PM & Kroemer G ( 1999 ) . Mitochondrial release of caspase - 2 and - 9 during the apoptotic process . Journal of Experimental Medicine , 189 : 381 - 394 . [ Medline ] 53 . Krajewski S , Krajewska M , Ellerby LM , Welsh K , Xie Z , Deveraux QL , Salvesen GS , Bredesen DE , Rosenthal RE , Fiskum G & Reed JC ( 1999 ) . Release of caspase - 9 from mitochondria during neuronal apoptosis and cerebral ischemia . Proceedings of the National Academy of Sciences , USA , 96 : 5752 - 5757 . [ Medline ] 54 . Wolter KG , Hsu YT , Smith CL , Nechushtan A , Xi XG & Youle RJ ( 1997 ) . Movement of Bax from the cytosol to mitochondria during apoptosis . Journal of Cell Biology , 139 : 1281 - 1292 . [ Medline ] 55 . Luo X , Budihardjo I , Zou H , Slaughter C & Wang X ( 1998 ) . Bid , a Bcl2 interacting protein , mediates cytochrome c release from mitochondria in response to activation of cell surface death receptors . Cell , 94 : 481 - 490 . [ Medline ] 56 . Garlid KD , Paucek P , Yarov - Yarovoy V , Murray HN , Darbenzio RB , D ' Alonzo AJ , Lodge NJ , Smith MA & Grover GJ ( 1997 ) . Cardioprotective effect of diazoxide and its interaction with mitochondrial ATP - sensitive K + channels . Possible mechanism of cardioprotection . Circulation Research , 81 : 1072 - 1082 . [ Medline ] 57 . Halestrap AP ( 1989 ) . The regulation of the matrix volume of mammalian mitochondria in vivo and in vitro and its role in the control of mitochondrial metabolism . Biochimica et Biophysica Acta , 973 : 355 - 382 . Acknowledgments The author wishes to thank Dr . R . F . Castilho for a critical reading of the manuscript . Correspondence and Footnotes Address for correspondence : A . J . Kowaltowski , Caixa Postal 6043 , Universidade Estadual de Campinas , 13083 - 970 Campinas , SP , Brasil . Fax : + 55 - 19 - 788 - 1118 . Present address : Department of Biochemistry and Molecular Biology , Oregon Graduate Institute of Science and Technology , Beaverton , OR 97006 - 8921 , USA . E - mail : alicia @ bmb . ogi . edu . Publication supported by FAPESP . Received October 7 , 1999 . Accepted November 4 , 1999 . © 2006 Brazilian Journal of Medical and Biological Research Av . Bandeirantes , 3900 14049 - 900 Ribeirão Preto SP Brazil Tel . / Fax : + 55 16 3633 - 3825

QCad is a 2D CAD system with which you can draw and modify plans easily . General Notes A " plan " is any precise plane representation of a real object for study or for production purposes . The dimensions of each element ( entity ) of which the drawing consists of , must be exact no matter what scaling is used . This differentiates a CAD program from a vectorial drawing tool such as Sketch , Illustrator or Corel Draw , which is a more or less faithful representation of reality . With CAD a plan first of all has to be exact . This is in contrast to illustrations ( Drawing ) where the aesthetics of a picture are of more concern . Installation of QCad The version qcad - 1 . 4 . x used for this article is on the applications CD of the Redhat and Mandrake distributions as ready - made package . Other distributions surely have similar packages . You can download the newest version at http : // www . qcad . org / . Qcad needs QT 2 . 2 as GUI library . A little bit of theory Before beginning with your first document you should have understood certain CAD concepts and definitions . The entities An entity is a layout element that is " known " to the program by its form ( segment , arc ... ) , in the geometric characteristics of its position ( vertical , tangent ... ) , in its start and end positions which determine its dimension ( fixed at intersections , coordinates , center ... ) , in its attributes ( color , thickness , types of characteristics ) and its membership to a layer ( blue print ) . Generally speaking to build an entity , it is necessary : to define your view on the working layer to define the attributes to choose the nature : straight line , segment , circle , ellipse , point , curve , hatch , text ... to indicate the geometric framework of the construction : horizontal , oblique , concentric , vertical ... to indicate the constraints It results in building a virtual but exact sentence of this kind : circle of radius X from the center passes through the endpoints of an entity which was indicated by a right click , etc . The points will have to be indicated by a left mouse click near the desired points which have to be chosen among those that the system offers . It should be noted that the concept of fixation is found elsewhere under the name < snap > For example the sentence horizontal straight line , which touches the outer lines of an entity is composed with the following menus and sub - menus : Note : That you get to the first start menu by clicking with the right mouse button onto the " paper " . The layers Elsewhere called levels , plans , blue prints . The layers describe in fact a virtual pile of celluloids . Each celluloid contains a part of the drawing , recognizable as a whole if you look on the pile from above , thanks to its transparency . A layer can be moved in the pile , removed ( which affects only the part of the drawing that it contains ) , frozen or made invisible . The layer on which you work is the only active one at the moment . The operations that you carry out affect only it . When you assign attributes of color , line types or line thickness then all entities that you draw will have them by default . However you could assign blue to an entity that is on a red layer by modifying its properties . For a complex drawing you will work on one layer after the other which allows to make a certain subset visible or invisible , print only one piece , modify nothing but this . The status line The status line is located in the lower part of the main window . It is not specific to CAD software programs but nevertheless essential . As a command requires several successive operations carried out in a defined order , the program shows in the status line the operations that should follow and what it expects from you and this until the end . It is therefore absolutely necessary to read the information that is displayed in that lower line if you do not want to risk that the CAD session ends with the declaration that this is a + - @ - # !! program . In CAD the result is precise if the designer is working exactly and systematically . Methods of drawing There are several ways how to do it , with at least two of them being excellent . Both use the concept of drafts based on not dimensioned ( very long ) straight lines but with precise relative positions ( distance of one compared to the other ) . These straight lines , horizontal and vertical are called lines of construction in DTM or SoildWork and geometries in TSCadDraw . The first method consists of defining a profile based on these straight lines as points of support . The exercise which we will follow in the rest of this article will demonstrate this . The second method consists of defining a profile by adjusting the lines at fitting intersections . To do this with QCad you have to right click to get back to the main menus and then choose < edit > < Trim two object > then click on the line that you would like to trim ( cut ) next click on the line where your first line should stop . Here are 3 examples of editing objects : In this figure as in the following ones the yellow boxes show the selected functions , footnote : not colored by QCad itself , and the blue crosses show corner points on which you can click . With the function < Trim objects > one makes an element fit to another . It is important to click first ( 1 ) on the part that you want to fit and second ( 2 ) on the entity that intersects the first . For the function < Bevel > it is important to determine the X and Y values of the edge before , no matter if it is trimmed or not and finally to click on the entity to be beveled . The steps are the same when working with intersecting lines and the function < Round > . One should also mention that QCad tries to be quicker than the user or tries to help you with your decision , in fact when a function is activated which needs the selection of a second entity to go on , then QCad modifies the color of that entity which is near the pointer and indicates to you that you can select it with a left mouse click . It works the same way with the fixation points which are colored red . The right mouse click cancels an operation and allows you to go back to the main menu . The following figure shows the result of these various adjustments : Example application To get to know a program there is nothing better than to use it . Let ' s try to draw an object which is inspired by the logo of SEV Marchal which I usually use for my beginner ' s courses in numerical control . With DMT 10 by Mécasoft it can be drawn in less than 5 minutes , annotations included . Set up of a page format This is not strictly necessary for the exercise but a technical drawing obeys to standards which define among other things the view and the aspect of the format ( frame and data block ) in which they are contained . Here I use a format coming from DMT10 transferred to DXF , the only file type that QCad can read and generate which in turn guarantees the exchange in two directions with all CAD programs in the world . Once the format is loaded you see a mark off of the drawing zone with a zero reference in the middle of the area . It is recommended to delete unnecessary layers , to rename those which contain the format frame and to add those that are described in the following paragraphs . Managing the layers By clicking on the icon representing several piled up pages you open a side window called " Layer List " . The selected blue print becomes the active blue print , it appears with intensified brightness . The eye besides the name of the layer allows to make it visible or invisible . The open eye to the very right of the layer list window makes all layers visible while the closed eye makes them invisible . The plus sign adds a layer to the list , the minus sign eliminates the selected layer , the symbol REN allows to rename the selected layer and the trash can deletes all empty layers . Now we need a layer < Format A4 > that contains the frame , a layer < Trait > that contains the drawing in a front view and a layer < Annotation > that contains the annotations to the drawing . Defining a vertical reference This straight line passes through the origin ( zero ) and allows the construction of parallels on the X - axis . Our drawing will be symmetrical to this line . At first you activate the layer < Trait > ; then you choose a continuous width type with a thickness of 1 and the color red ( point 5 ) then you construct the " sentence " < straight line > < vertical ( 1 ) > < passing through absolute coordinates ( 2 ) > < enter 0 , 0 ( 3 ) > < click left ( 4 ) > Construct a parallel to 60 If necessary you remove the menus by several right mouse clicks and construct the following : < straight line > < Create parallels > < enter 60 > and approach the position marks of the reference straight line . It will become grey in turn and according to the position of the pointer QCad suggests to construct the parallel either to the right or to the left of the reference . Position the pointer slightly to the left and make a left mouse click . A straight line in cyan is created . Construct the other straight lines Most functions of QCad are repetitive , that is , they are active as long as they aren ' t replaced by another . Therefore < straight line > < Create parallel > < Distance of > is still activated . It is sufficient to replace the value 60 by 50 ( Vertical 2 ) and to click and then to replace 50 by 25 ( Vertical 3 ) and then to click . Go on with this for the horizontal straight lines which are defined with regards to the reference at 0 ( Horizontal 4 ) . Draw the horizontals ( 5 ) and ( 5 ' ) with distance 60 , then ( 6 ) with distance 30 and finally ( 7 ) with distance 40 . Construct the left half of the logo For the construction we rely here on the straight lines which we have just drawn . You have to go back to the main menu with a right mouse click and choose < lines > < multiple lines ( button : create lines ) > < passing through the intersection ( Snap automatically to .. ) > . From this moment on when we position the pointer near the intersection of the straight lines it will be marked with a red circle . When this intersection is suitable as the beginning of a character segment , then make a left click , move to the next intersection and make a left mouse click again . The segment is drawn . But as the function is modal this last point which is the end of the segment that we have just drawn will at the same time be the beginning of the next segment . This allows the drawing of closed contours . If you don ' t need it for an additional segment a right click will interrupt the active function but doesn ' t cancel it . So for this half side of the profile choose a continuous line type , thickness 2 and color blue like in point 1 in figure QCad10 ( below ) . Then left click on 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 and finally a right mouse click . The left half of the profile is ready . Easy ! Editing the result Editing is a modification of something existing . To add an adjustment or a beveling to a drawn profile or to delete a segment , that are modifications . Whatever the changes to make are there is a general approach . First you choose the function < Edit ( 1 ) > which opens a sub - menu of all possible modifications . Select the desired function , e . g . < delete objects ( 2 ) > , which opens a sub - menu for selection : contour , all entities , tag single element ... This allows you to choose the borders of the modification . If you choose for example < Tag single element ( 3 ) > design the element ( 4 ) and then acknowledge the action by a left mouse click on the arrow icon ( 5 ) then the chosen element is deleted . Please note that the function < ( un - ) tag single element ; > is a toggle , if you click on an element then it is selected , another click and it is deselected . This allows to remove certain elements from a global selection . Adjusting the basis of the ear Going back to the main menu we delete the construction straight line called 1 in figure QCad12 ( below ) and choose < Edit > < Round > < Radius 10 > < trimming > We determine the entities to trim , then we move the pointer near to the adjustment / link that has to be made . Qcad then suggests possible solutions ( radius 10 ) . If a fitting point is suggested a left mouse click keeps the linking / adjustment and trims the line . To construct the mirrored half of the profile With the existing 1 / 2 profile it would be nonsense to draw another one , therefore it is sufficient to duplicate the first one symmetrically to obtain a complete profile . We choose < Edit > < mirror objects > < Tag Range > < Point ( Snap to nothing ) > and draw a window around the 1 / 2 profile ( yellow frame in figure QCad13 ) . The profile is selected : it becomes red . We make a right mouse click : we get back to the selected sub - menu . We acknowledge by clicking on the arrow icon . We get back again to the fixation sub - menu : we choose < Extremity ( Snap to endpoints ) > and determine the points 1 and 2 as shown in figure QCad13 . A dialog box " Mirror " appears . If you type in a value of 0 , the 1 / 2 profile is moved , if you give in a value of 1 it is duplicated . Therefore you have to give in a value of 1 and click < Ok > . And the profile is ready . Drawing the eyes By using what we have seen already we can draw the left eye as well through the horizontal and vertical construction lines ( point 1 ) . Then you draw the profile by building upon this straight line with a polyline . You trim it with a radius 5 ( green crosses ) and a radius 25 ( magenta cross , points 2 and 3 ) ; finally you delete the construction line and duplicate the left eye by mirroring it to the right ( point 4 ) . All necessary commands for this operation have already been explained above . Adding dimensions Annotations are no strength of QCad : it is impossible to give tolerances or to write somewhere else than in the middle of the lines that indicate the dimensions . The consequence of this last point is that the size of the characters is changed depending on the available space between two reference points . This give the whole drawing a strange aspect . Well , no matter how it is , to make annotations you have : to position yourself on the annotation layer , choose a fitting line attribute , especially a thickness of 1 and a color different from the other lines , unique if possible . But this isn ' t obligatory . Select < Annotation ( Sub - menu dimensions ) > < Type of annotation horizontal or vertical or radius ... > < Endpoints to determine the position of the construction lines or certain intersection ( Snap manually to .. ) > < Point ( Snap to nothing ) for positioning the dimension > To change from one way of fixation to another you may use the short cut keys : F for < point > , E for < Extremity > , X for < automatic intersections > etc . The points A , B and C ( image below ) are difficult to annotate with a dimension . A sectional view ( cut ) : preparation The representation of a three dimensional object in 2D makes it necessary to order several views according to certain drawing norms even if it only is to show the thickness of the object . Our drawing represents an object of 20mm thickness worked on in a depth of 5mm . To just say this isn ' t explicitly enough and a cross sectional view becomes necessary . To do this : Make the layer < Annotation > invisible with a double click on the icon with the open eye . Add a layer < cross section > with the option + in the management menu for the layer . According to the norm a cross sectional cut is indicated by a line with a points and hyphens . Activate this as a style attribute and draw a line of width 1 between the eyes of our logo ( < straight line > < Polyline > < snap to grid points > ) . Sketch the cross sectional view In industrial drawing whether with pencil and paper or with CAD there must always be a correspondence between the views . The cross sectional view is a projection along the line that indicates the cross sectional cut through the object . Drawing and hatching of the cross sectional view We use again straight construction lines to draw the cross sectional profile with a polyline ( figure QCad18 , below ) . Modify the properties of the lines for the hatch ( 2 ) . Select < Create hatchings ( 3 ) > < Tag range > < Passing through the Point ( Snap to nothing ) > and draw a square around the cross sectional view to select the area ( 4 ) . Acknowledge ( 5 ) . The dialog box " Create hatchings " appears . We choose a fitting hatch parameter ( 6 ) . We press OK ( 7 ) and the hatched view ( 8 ) is ready . And finally the finish The cross sectional view as it is represented here is , according to the rules of industrial drawing , is a projection . Since obtain this view by virtually cutting our profile at the height of the eyes we have to indicate the depth of the eyes . You add this as follows < Straight polyline line ( button line ) > < create lines > Now the drawing is ready . Only the frame of our paper ( the data block ) has to be filled in with text . I leave it to you to discover the < text function > . Conclusion Linux CAD - Applications under the GPL aren ' t numerous . It is therefore appropriate to honor the authors of QCad and to thank them for the useful application they give to the community . Even though it isn ' t replacing industrial applications of the type of Cadkey , AutoCad or DMT , it remains a good educational tool and a tool for not too complex plans . One can regret the weaknesses of the annotation function , the absence of covering / lining / boarding functions ( rowness , geometrical tolerances , sectional views ) and the numeric limitation of the geometric border conditions . But you can congratulate the authors for the ease of handling , for the simple and convenient user interface , the powerfulness of linking / fitting and hatch functions , to the choice of the DXF format and not a proprietary format . Possibly as well to many other good things in QCad which I have not yet discovered . QCad has a help system but the documentation is English and remains therefore totally obscure to me . This proofs how easy the handling of QCad is . I have discovered everything by just playing around with the program . Having said that , the optics of CAD have changed dramatically in the recent years . It is less a question to produce 2D drawings to represent three - dimensional objects . But to work out a 3D model completely defined in form and dimension with the help of performant tools and volume modelers . The program generates then automatically plans , annotations and the listing for numerically controlled machines . These programs are ProEngineer , SoldConcept , Catia , Solid Edge or Think3D .... When will these tools be available to Linux ? At the moment we have QCad and CAM Expert , its commercial brother , equipped with two dimensional CAD and old MS - DOS products such as DMT10 by Mécsoft which runs perfectly in dos - emulation under Linux as you can see in the last screen shot ( below ) . Talkback form for this article Every article has its own talkback page . On this page you can submit a comment or look at comments from other readers :

G . C . Lichtenberg dreams of the earth as one huge , living organism : " Is it conceivable that the continental masses form one whole system of cooperating organs ? And should the different continents be understood in analogy with the internal organs : kidneys , liver , bowels ? And what happens to the surplus products , the excrements of the planet ? " Life on earth binds energy , consumes energy . What happens to the surplus , which explodes the restricted economy ? Few have thought about the analogy between the ecological system and human metabolism in such a drastic way as Lichtenberg . But the same idea resurfaces constantly : in Nietzsche ' s " grand economy , " in Bataille , and in theoreticians such as Fëlix Guattari . The flow of energy on earth is a material economy - emotions , thoughts , goods , money , desire , weapons , oil , art , information . Everything circulates , everything communicates . Fëlix Guattari : " Thus , it is impossible to remain outside of economy and describe it as a closed system . The dream of a systematic description and control of the economy has inspired all modern ideologies and totalitarian regimes . This dream is over . " " In truth , my brothers , the Spirit is a stomach " ( Nietzsche ) . Metabolism : thinking is eating . Incorporating and digesting . In Hegel ' s Enzyklopädie [ Encyclopedia ] we find a series of notes on the " oral system " and the double function of the mouth . The issue is the passage from interior to exterior and from exterior to interior - the incorporation of exterior substance and the expression of the inner . The mouth has the " double function of simultaneously initiating the transformation of food to a moment within the living animal organism , and , opposed to this interiorization of the exterior , the function of completing the objectivation of subjectivity taking place through the voice " ( paragraph 401 ) . The Spirit speaks through the voice . In order for written signs to be grasped they have to become voice . Hegel understands this appropriation in analogy with eating . The Spirit eats . In Hegel ' s early text Der Geist des Christentums [ The Spirit of christianity ] , there is an extended , speculative interpretation of the Holy Communion as the fundamental act of Christianity : the communal eating of Christ ' s flesh and drinking of his blood . The young Hegel constantly returns to the doctrine of incarnation . The sacrificial death of Christ and the salvation of the faithful ones through the sacraments . The Father is incarnated in the figure of the Son , who is sacrificed for the sake of Man ' s salvation - the Spirit becomes flesh , which is devoured and then returns to spirituality . In the ritual of the Communion , Hegel sees a dialectical movement between subjective and objective : the Host is an objectivation of Christ ' s infinite love for mankind , but this " love , having become objective , this subjective having become a thing , returns to its essence and becomes subjective again in the process of eating . " The speculative circle is closed in religious incorporation . Subject and object are reconciled in the complicated digestive system of dialectics . Werner Hamacher ' s pioneering Pleroma - zur Genesis und Struktur einer dialektischen Hermeutik bei Hegel [ Pleroma - on genesis and structure of a hermeneutic dialectic by Hegel ] ( 1978 ) , is dedicated to this far - reaching correspondence between eating and reading , digesting and understanding . The figures of incorporation characterize all of Hegel ' s philosophy . Spirit negates itself - and exteriorized , it becomes flesh . But the speculative movement rests upon the principle of double negation . Flesh is negated , devoured and again dematerialized into Spirit . In Hamacher ' s words : " The Spirit reads and eats itself as nutrition becomes writing . " Hegel ' s system is an auto - cannibalistic encyclopedia - all - encompassing . In the concluding chapters of the Phenomenlogy of Spirit , which deal with absolute knowledge , the externalization and successive return of Spirit through history is described as a laborious digestive process : the subject of history " has to penetrate and digest all of its rich substance . " The central notion of Aufhebung - both a canceling and a preserving - can be interpreted as a devouring . An epoch is devoured by the next , where it is broken down but also preserved as a moment in a more encompassing metabolism . The Spirit devours itself through history , successively it incorporates all substance , until it finally reaches the full satiety of absolute knowledge ( Absolute Eating ) - a state which Hegel , using a neo - Platonic term , calls Pleroma ( fullness , saturation ) . Lichtenberg ' s reveries about the world map as a digestive system remain a mere draft . But in Hegel , the continents are assigned to their places in the violent geopolitics of World Spirit - a system of incorporation and excretion . Geographies : the Spirit is European . He always eats " in the same direction . " Hegel draws a map where continents , ethnic groups , species of animals and plants acquire their ultimate positions in the dialectical structure . In a grand gesture Hegel delineates the basic traits : " The World Spirit moves from east to west , since Europe is the absolute end of history , and Asia its beginning . " The sun rises in the east - the Asiatic dawn of Reason is the birth of history . Like the radiant heavenly body , the World Spirit moves westwards . This geographical exposition commences with a violent exclusion : Africa . This continent is still " veiled in the dark color of the night , " and it is not part of the reasonable course of world history . Its inhabitants are said to be still caught in the blind and irrational forces of nature , and consequently they are " incapable of any kind of formation or development . We now leave Africa never to return . " A violent expulsion - excretion . " It is only now , having left Africa behind , that we find ourselves on the real stage of world history . Let us now briefly sketch the geographical foundations of Asia and Europe . Asia is the continent of commencement . It is true that it is situated to the west of America ; but just as Europe is the absolute center and end of the old world , so Asia is an absolute east . Asia was the dawn of reason and the beginning of world history . " The childhood of history takes place in the Oriental cultures . The light of reason is already strong , Hegel writes , but it is still situated outside of human subjectivity . The eastward movement of history signifies the gradual awakening of Man . In European humanism the process reaches its peak : the enlightened self - consciousness of European man is the final realization of reason . Metabolism - geography - politics : the map as an example of the violence inherent in classification . The belief in the possibility of mapping the system from the outside seems to amount to the erection of totalitarian structures . Fëlix Guattari wants to read the map after the downfall of the grand systems - to read the map from " within , " as itself part of the economy . What is the alternative to the totalitarian map ? A political rhizome . A flow diagram , the logic of transformation : blood , gold , filth , water , oil , fire ... Alternative geographies : Michel Leiris ' s Africa , Joseph Beuys ' s America . Eurocentric metabolism broken down : the geopolitical coordinates drawn anew . The inherent violence of the map vs . a politics of conflicting maps . On May 23 , 1974 , Joseph Beuys arrives at John F . Kennedy Airport in New York . Wrapped in blankets , he is carried out on a stretcher . An ambulance takes him to a Manhattan gallery , where a coyote awaits him . He has still not touched American soil . During four days and four nights a performance takes place , which Beuys names Coyote - I like America and America likes me . What is at stake is an encounter between worlds , between Europe and an America not yet drawn into the European sphere . The sacred animal of the Indians , the coyote , is confronted with items from the world of the artist : a walking stick , two blankets , a pile of copies of The Wall Street Journal . After four days of ritual communication between man and animal , Beuys returns in the same way that he arrived . He concludes : The powers of the coyote are so great that they are incomprehensible to mankind . However , the soul of Europe is not the Hegelian light , but a will to power and a ruthless violence . Michel Leiris calls the European spirit a " violent machinery , " whose heavy armor is " bloodstained both inwardly and outwardly . " The medium of European " spirit " is not reason , but violence . In his On the genealogy of morals , Nietzsche sketches a different history of European man . Modern humanism is not the result of increasing enlightenment , but of a primordial violence , successively refined , sublimated and made invisible . What has to be explained is the existence of " an animal endowed with a soul . " The first precondition for what we call " mental life " and " subjectivity " is memory ; and memory , Nietzsche claims , can only be produced through pain : " Something is burnt in , so that it hurts and stays in the memory ; only that which does not stop hurting will stay with us . " European culture rests entirely on violence and pain . It is not only the others who are repressed - the European is also a subtle tormentor of himself . " It was never without blood , torture and sacrifices , when man found it necessary to acquire a memory . " The animal man has become " interiorized , " he has created a painful interior space , entertained by subtle doses of self - torment ( what is usually called conscience ) . Instead of acting out his aggressions , all forces are directed inwardly , and suffering increases . Indications of other maps , different systems , breaking up the economy of European idealism . The limits of the system and of appropriation . Novalis : " Could anyone stay alive by eating his excrements ? " The would - be Hegelian economy at its extreme . He dreams of a total economy , an incorporation of all externality in the vast metabolism of the system . The subject of history has to " penetrate everything and digest all of its rich substance , " until finally everything is incorporated in a totally satiated body . The system eats ( or wants to eat ) it all : " Everything has to become food " ( Novalis ) . The young George Bataille reads Nietzsche , and identifies completely with him . He has finally come across a thinker with an eye for the importance of lightness and laughter . The affirmative power and laughter is more profound than all philosophical thought and all systems : laughter transcends , sublates , tears down - in its ecstatic whirl , the system is shattered . For Bataille , Nietzschean laughter signifies the transcending movement whereby the economy of closed thought is exploded . Laughter is excess , sacrifice , waste . Bataille ' s doctrine concerns the heterogeneous , which cannot be incorporated in the individual or social body , but has to be expelled . This science Bataille calls heterology ; its object of study is the basic expulsory mechanisms at work in the constitution of psychological and social organism ; what is foreign has to be rejected or sacrificed . Hence , it is declared filthy or holy - it becomes a fetish . Bataille ' s scatology and his obsession with sacrificial rituals are rooted in his will to liberate himself from the economy of dialectical thought , which he considers to be erroneously based on lack as the motivating force behind the system ' s infinite hunger and its will to appropriate outer substances . The act of eating within sacrificial rituals can be interpreted in a radically anti - economical way : not as a will to gain , but as pure expenditure - a limitless consumption of the surplus energy which resists assimilation . It is a matter of life and death . The living system seeks to exclude the hieroglyphs of death - those inanimate signs which do not allow for interpretation and incorporation . The hieroglyph par excellence : death itself . Bataille : " Death is the highest form of luxury . " Luxury - dirt . The ostentatious destruction of riches is a basic cultural mechanism also in modern societies , although in a sublimated form . There has to be a consumption of surplus energy : a ritual annihilation , eating in an infinite variety of guises . Bataille finds such a basic principle of loss in the investment of enormous sums in jewelry , in the production of sacred objects , and in the creation of poetry and art - a wasteful expenditure which cannot be accounted for by the principle of gain : luxury . CNN : " The negotiations ended with the agreement of a 50 % cut - down on land - based nuclear arms . The supervising of the dismantling and destruction procedures will be mutual . " A peaceful potlatch . Destroyed missiles , destroyed warheads . What luxury would surpass the voluntary destruction of mass destructive weapons ? Not destruction but destruction of destruction . The negation of negation . Result = 0 . The sun spreads its energy without demanding anything in return . The rays of this self - consuming heavenly body reach the earth and are transformed into a vital force in plants , animals , and human formations . An increasing surplus of energy is accumulated : surfeit . Sooner or later the explosion is bound to come .

With the advance of ethnographic research in Amazon and Central Brazil over the past thirty years , two distinct and apparently irreconciliable versions of gender relations have emerged . I refer to these in “ male domination ” and “ sexual equality . ” [ 2 ] The first centers on the structural - functionalist distinction between the public and private domains and privileges phenomena such as dual organization , political economic control over reproduction , and relations between communities . Within this perspective , “ masculine ” and “ feminine ” are associated with the ( encompassing ) political or the ( encompassed ) domestic spheres of these social formations . The other position , arising from the cultural - feminist critique of the public / private distinction , seeks to demonstrate - based on the intimate character of native economies , the internal relations of the local group and the mutuality - the perfect equilibrium between the masculine and the feminine within these societies . In sum , gender relations are defined either as hierarchical ( male domination ) or symmetrical ( sexual equality ) , according to the point of view which corresponds to evidently irreconciliable positions . The present communication intends to defend an analytical path that permits the passage from one conception to the other . I seek to show that genders in the societies of lowland South America are defined vis - à - vis one another in terms of kinship ( consanguinity / affinity ) . In synthesis , I suggest that gender and kinship correspond to a system of interdependent signs in the social philosophies of Amerindian societies . In other words , I propose that a consideration of sexuality that is sensitive to the intuition underlying the structuralist theory of kinship formulated some fifty years by Lévi - Strauss . Let us recall that in this model gender relations are not formulated in terms of an opposition between “ masculine ” and “ feminine ” as absolute and substantive notions related hierarchically or symmetrically but rather as a bundle of complex oppositions of relations between individuals of the same sex and individuals of the opposite sex . Precisely in this sense , in the feminist contestation of the model of marriage alliance in which men exchange women , Lévi - Strauss underlined that the structure of alliance that ground and organize the sociality , function in the same manner with women exchanging men . The consideration of an exemplary ethnographic case may allow us to dimly discern the possibility of circumventing the debate between the alternatives of “ male domination ” and “ sexual equality ” in South American indigenous societies . We may observe how the Enawene Nawe , an Aruak people of the Southern Amazon define “ masculine ” and “ feminine ” within their social universe . The sexual emblems Among the Enawene Nawe , the trajectory towards adult life is socially marked in both sexes by emblems of sexuality and reproductive capacity : the penis sheath and tatoos on the belly and breasts , decorations of immense value in the symbolic economy of the Enawene Nawe are acquired in the course of what we might call “ rites of sexuality . ” [ 3 ] During puberty , boys should wait for the growth of pubic hair in order to have access to a sexual life . This physical transformation of the body is the necessary but not sufficient condition for the exercise of their sexuality . In addition they are required to wear a penis decoration . This decoration consists in a strip of Buriti palm leaf of approximately thirty centimeters of long by one centimeter of wide that is tied around the foreskin , with a knot similar to that of a necktie with the penis forced back into the pelvic region . One day before the affixing of this ornament , the boy s mother cuts his hair and substitutes his childhood body ornaments . Assisted by her daughters , the mother prepares a fairly large amount of beiju manioc cakes to be offered to the brother - in - laws of her child ( the husbands of his sisters or brothers of his future spouse ) who will officiate at the ritual . During the daybreak that precedes the awarding of the ornaments , the officiating brother - in - laws stationed within the clans ’ cerimonial house , located in the centre of the village , begin the final preparations for the ceremony : the fashioning of a series of items that will be used by the boy during the course of his initiation , such as arrows , palm strips used to make the penis sheath , achiote red coloring , palm mats , and palm strips comprising part of the costume of the yakwa ( ritual that celebrates the clan system ) . Simultaneously within the boy s parent s house , the boy lying in his hammock is painted with a light layer of achiote over his entire body and dressed with only a part of the ceremonial costume : the complement of the part to be offered by his brother - in - laws . At a given time , one of the initiate s brothers - in - law ( preferably his sister s husband ) will go and fetch him at his house and lead him to the center of the village . After this point his close consanguines ( parents and siblings ) remain in their house to assemble the gifts which will be offered to the officiating affines immediately after the bestowal of the penis ornament . A straw mat is placed in the entranceway of the clans ’ cerimonial house where the initiate will remain lying down until his penis ornament is bestowed , when he will also receive the remainder of his ceremonial costume . One of the older brother - in - laws will hold the initiate by his hands while the others beat him lightly . After a few minutes , the brothers - in - laws offer bows and arrows to the boy as well as an extras stock of Buriti palm thatch used to make new ornaments since ornaments deteriorate with time and need to be substituted . Two or three brothers - in - law will solemnly lead the boy back to the his close consanguine relative s residence compartment . His biological parents and siblings await his return while laying in their hammocks . When the boy is returned , his parents pay the brother - in - law with the gifts they have prepared beforehand . With this transaction , the intitiate comes to potentially enjoy sexual access to the sisters of his “ others . ” In sum , if the consanguineal relatives ( especially the mother and father ) are responsible for the manufacture of the physical person of their child ( the body ) , from his conception until puberty , his “ others , that is , his real or virtual affines are responsible for the manufacture of his social persona , which is immediately endowed with sexuality . Some time afterward a “ co - brother - in - law ” invites the initiate to accompany him to a spot in the forest that surrounds the village - that is to say in the opposite direction from where he was led by his brother - in - laws during the initiation - where he will exchange the showy ceremonial penis ornament for a more discrete model used in daily life . In contrast to the boy s brothers - in - law , the co - brother - in - law receives nothing for this service . There is only exchange between affines ; one does not exchange between consanguines or between affines of affines as is the case with co - brother - in - laws . Following this , the boy returns to his hammock in the company of his co - brother - in - law where a newly initiated girl offers him two large gourds of a drink prepared by her mother . The boy drinks this beverage until he vomits the entire remainder of any food he has ingested previously . After this , his first meals should be made with brand new utensils unless a person apt to perform blessings blows over all of the used utensils and the food prepared with them . From then on , the boy begins a new life characterized by sexuality , by responsibility for productive activities - agricultural , fishing and collecting - and by his obligatory participation in ceremonial life . With females initiation occurs differently , although events are also heavily ritualized . Since they are very little , girls wear a red - dyed cotton miniskirt . After her first menstruation a girl is considered ready for sexual activity , which may only begin after her second period . Her tatoos are performed precisely in this one month ( or one moon ) interval . The visible social signs ( which are openly discussed ) of the imminence of the transition from child to adult life are the growth of breasts and the darkening of the nipples . These signals are taken as indications of the occurrence of all the other relevant bodily transformations in the same way that the growth of pubic hairs signals these in a boy s case . On the first day of her first menstruation , the girl initiate remains in her hammock . Informed of the event , her mother asks her husband ( the father of her child ) to construct a new partition in the house where the girl may remained secluded for the length of a single lunar cycle . As their first precautionary measure the family solicits the aid of a blesser who is charged with blowing of the kitchen fire of the domestic group to which the girl belongs as well as her hammock . Simultaneously , new bottle gourds , pestle , and pots are procured for the girl s use . On the following day , the girl s father collects a certain vine with which her mother will prepare an infusion to be offered to the girl by a newly - initiated boy wearing a ceremonial penis adornment . The infusion has strong emetic properties which results in the girl vomiting “ all the old food ” she has eaten previously which had remained in her body . Afterward the blesser blows over the girl s head in order to prevent headaches . The activitiy of the blesser with the girl extends to the dawn of the third day at which point he [ or she ] leaves the girl in order to blow over the rest of the houses in the village . When the menstrual flux subsides , a tatoo specialist , preferably a sister of her mother or a mother s mother scratches a series of vertical lines colored with Genipapo dye on the belly and breasts of the initiate . After she is tatooed her hair is cut and all of her childhood ornaments ( necklaces , belts , earrings , bracelets , etc . ) are substituted with new items . Following this the blesser blows over the house where the girl resides as well as the places where she bathes and goes to the bathroom and finally over the clans ’ house and a few trees on the outskirts of the village . In this case we can see that a girl s initial period of fertility has consequences not only for her own body but for the entire social universe . At the beginning of the second menstruation , the girl returns to her seclusion and begins again to observe food taboos . Once again the blesser comes to blow over her house and the other houses in the village . In contrast to the penis ornament , the girl s tatoos are not paid for since one does not pay for the services of consanguines . The penis sheath and tatoos on the breast and belly are not merely symbols of sexuality but parts of the newly initiated person acquired as perpetual aspects of their being and imbued with a profound cosmic meaning . On the occasion of their death , on the path to the eno ( empyreal heaven , located behind the visible sky ) where the vital essence is destined to reside , the Enawene Nawe will cross swollen rivers inhabited by gigantic spiders . These rivers are crossed by means of bridges which are , in fact , huge non - poisonous snakes . To the living these bridges are the rainbows . Only people wearing the proper ornaments that mark sexual difference may safely cross from the earthly path to the sky . Men without penis ornaments as well as women lacking tatoos are summary devoured by the gigantic spiders when they attempt to cross the serpent - bridges . Finally , it is worth noting that pushing the penis shaft partially back into the body cavity has the effect of considerably increasing the volume of the scrotum which is the locus of male fertility which enhances its visibility . In the same fashion , if the vulva is always hidden by the mini - skirt or by leaves held in place by one or several belts of tucum beads during the bath , the tatoos visually and tactilely call attention to the potential for conception , gestation and lactation . This brief communication regarding the rites for the production of sexuality in both men and women shows that , in both cases , such events exercise an influence over much more than the individuals submitted to them . The fabrication of men and women is a matter that centers fundamentally around their social “ others ” and , in its broadest sense , involves the participation of the entire group . There is no question of opposing “ man ” and “ woman ” rooted in the “ public ” / “ private ” or in the “ center ” / “ periphery “ domains . Although girls are tatooed within the family compartment while boys receive their penis ornaments in the “ clans cerimonial house , the blesser does not only blow over the girl initiate and her hammock but also over all the houses of the village and even on the “ clans ’ cerimonial house . ” Moreover , we should not forget that the boy receives ritual paraphernalia not only in the clans ’ house but also within his domestic compartment . In this particular ethnographic case , the public / private opposition seems to obscure a more fundamental socio - cosmicological dichotomy , that is , the relation between consanguinity and affinity . The definition of sexuality proves to be a fundamental principle of social order . The paths leading to adult life for both males and females are , however , defined in opposed directions . Among the Enawene Nawe the articulation between gender relations and kinship relations associates the categories of masculinity and femininity with those of affinity and consanguinity , respectively . Tatoos are produced by consanguineal relatives , others - of - the - same - kind ( mother , mother s sister , grandmother , etc . ) under the auspices of mutuality , while the penis ornament is bestowed on a boy by affinal relations -- by others - of - a - different - kind ( brothers - in - law ) according to a formula of reciprocity . The opposition between consanguinity and affinity corresponds to an ordering principle of the public , domestic , and cosmological spheres , which always manifests itself as a relation between relations rather than as a relation between two terms : in sum , a system of signs in the saussurean sense . The gender opposition , here understood as that derived from the relation between individual of the same sex and of the opposed sex corresponds to an analogously ordered system . Rituals of construction of the opposition and complementarity of the genders make clear the immediate social character of sexuality . During male initiation , the relations between individuals of the same gender and same kind show themselves between the boy initiate and his father ; between individual of the same gender and different kind , between the boy and his brother - in - law ; between individuals of the same kind and different gender , between the boy and his mother ; and between individuals of gender and kind different , between the boy and the newly initiated girl who offers him the medicinal beverage which induces him to vomit all the food present within his body ingested during his time as a child . During female initiation , on the other hand , a similar set of contrasts are thematized : between individuals of the same gender and same kind , between the girl initiate and her tatooer ; between individuals of the same kind and different gender , between the girl and her father ; and between individuals of different gender and kind , between the girl and the newly initiated boy who furnishes her with the emetic . We can observe in this sense that , despite their differences , both initiation rites reserve identical roles for relations between individuals of distinct gender and kind who are males and females in a potential marriage relation to one another , which immediately evokes a notion of symmetry and complementarity between the sexes . Nevertheless , female iniciation apparently do not thematize the opposition between individuals of same gender and different kind , like husband s sister / brother s wife or husband s mother / son s wife . The acquisition of the penis ornament and tatoos on the breast and belly marks the beginning of a phase of sexual life which is especially intense , in some cases , with serval partners who are not limited to the same age but also with those who are much older . These sexual affairs both before and during marriage are characterized by a different dynamic than the sexual life between spouses . There are times when women acquire trade goods from men and other highly coveted items , such as belts , necklaces , bracelets , fish , etc . which are literally “ exchanged for the vagina . ” The ostentatious use of these goods as well as their quantity corresponds to the visible signs of a woman s sexual activity . As marriage approaches men and women tend to concentrate more fully on sex with their future spouse , although , they may , in some circumstances , seek out other sexual partners . The social cosmological context According to their native ideas , the Enawene Nawe reside on the intermediate level of the universe , between a level containing celestial spirits and the level of subterranean spirits . The celestial spirits are beautiful , generous , playful , of good character , and healthy , living in a world of sexual and alimentary abundance within a perfect sociological order . The Enawene Nawe refer to these spirits as their “ grandfathers ” to whom an almost absolute power to prevent and cure infirmities is attributed . The celestial spirits are the owners of honey and of some flying insects and accompany the Enawene Nawe when they travel on fishing or collecting expeditions , protecting them from the dangers of the world beyond the village . The sociological perfection of the celestial world is reflected in the absolutely perfect architectural symmetry of the “ grandfathers ’ village ” and the luxuriant nature that surrounds it , which is a inexhaustable source of all sorts of gastronomic pleasures . On the other hand , the spirits of the subterranean level are ugly , implacable , avaricious , insatiable and vectors of disease and death . They are owner of almost all of the resources found in nature , such as fish , wood , fruits , and the principle cultivated products . While the celestial spirits share a reasonably homogeneous physical appearance between themselves , the subterranean spirits assume extremely variable forms , all hideously disfigured . Moreover , they are extremely lazy . Since these spirits are the owners of existing natural resources the Enawene Nawe depend on them for their food and consequently for the reproduction of their social life . Thus , while the celestial world is defined fundamentally as a world of the “ self - relations , ” the world of humans - as an imperfect reflection of this world - corresponds to the “ relations between others , ” since human reproduction is dependent on the subterranean world ( the world of alterity ) . Within the Enawene Nawe cosmos , the celestial and the subterranean worlds correspond , respectively , to the archetypes of consanguinity and affinity in their pure state . The human world , on the other hand , corresponds to an arena in which these two principles are combined . Therefore the social structure defines its constitutive units ( nuclear family , extended family , residential group , and clan ) precisely in terms of the articulation of these parameters with the parameters of gender . The Enawene Nawe ceremonial sphere is notable for its complexity . In general terms we can observe that the native calendar distinguishes two well - defined ritual “ seasons , ” one related to the celestial spirits , coinciding with the period of high waters and another much more extensive season devoted to the subterranean spirits . The latter season encompasses the period of the rising and falling waters and the dry season . If both of these seasons are essential , the first is marked by much less formality than the second . This informality can be so extensive that , in stark contrast to the ceremonies for the subterranean spirits , celestial spirit ceremonies may be greatly abridged for purely pragmatic reasons . The ritual complex dedicated to the subterranean spirits is basically characterized by a dynamic in which the “ hosts , ” all the women and the men of one or more clans , remain in the village while the “ others , men from the other clans , organize large fishing expeditions . While the men who have left are responsible for gathering fish , those reamaining in the village , together with some of their sisters ( the “ hostesses ) , process a large quantity of manioc flour and vegetable salt . The radical separation is symbolically constructed between those who stay and those who leave , the fishermen return to the village dressed as threatening subterranean spirits where they are received by the hosts who are adorned only with their human emblems of gender . The hosts , furnishers of manioc and salt porridge , conceive of themselves as humans and metonymically represent the social whole . At the same time , the men who have arrived from the fishing expedition metaphorically represent the subterranean spirits who aggressively invade the village . Little by little the group of hosts domesticates the group of spirits by making them lower themselves to grab salt with their hands . The meeting of these two groups is marked by a series of ceremonies that include ritual oratory , dances , performances of both instrumental and choral music by the fishermen , representatives of alterity . The hosts , that is those representing humans , limit themselvs to remain seated around the dance circle where they keep stoking the fires that illuminate and heat the central patio and to serve food and drink to the singing and dancing spirits represented by the fishermen . The hosts are defined as a community united by consanguinity in opposition to the fisherfolk who are related to one another as affinal spirits . In this regard it is important to note that the hosts are ideally members of both sexes of a single exogamic clan or clans who do not practice spouse exchange ( being , therefore , “ functional consanguines ) . Simultaneously , the fishermen constitute a contingent composed of individuals of the same gender but of different kinship groups - that is , as affinally related amongst themselves - representing all of the other clans . The men who have remained in the village represent the female role in opposition to men who have arrived from without ( representatives of the spirits ) since , during everyday life , women offer porridge to men , while men reciprocate with fish for the women . Beyond the formal and rigid aspects of the ritual , other notable differences distinguish the ceremonies dedicated to the celestial and subterranean spirit legions . In contrast to what has just been described of the relation between the Enawene Nawe and the subterranean spirits , the rites that focus on the celestial spirits are never accompanied by a climate of tension or simulated hostilities . Moreover , the chants aggregate all of the men or all of the women in the village center without any further disposition to differentiate people in terms other than gender . Bodily ornaments and painting are not used : people are represented as gendered humans and nothing more . During this period of the Enawene Nawe yearly cycle , all the men go together to gather honey and fish while all the women apply themselves to the task of making porridge . With the return of the men to the village , the gender complementary and sexual equilibrium is stressed . On these occasions , men exchange honey ( masculine vaginal mucus ) produced by men for women for porridge ( feminine semen ) produced by the women for men . [ 4 ] The men run after the women in order to smear honey all over their bodies . According to the Enawene Nawe , honey smells like the vagina . On the other hand , the analogy between porridge and sperm is equally evident if one focuses on the color and consistency of these two substances . In summary , during the ritual season that focuses on the relation between the Enawene Nawe and the subterranean spirits ( the “ Different Others ) , kinship relations are brought forward through the inversion of the opposition between genders . On the other hand , during the season in which the relationship between the Enawene Nawe and the celestial spirits ( the “ Identical Others ) are foremost , gender relations are emphasized by neutralizing the opposition between kinship . In sum , gender and kinship distinctions do not only cross - cut the domestic kinship sphere but correspond properly speaking to fundamental cosmological categories through which the social and cosmological universe is organized . We may now return to the starting point of our consideration of gender . Based on Enawene Nawe ethnography we may formulate two hypotheses about gender relations , one emphasizing “ masculine domination ” could rest , for example , on the notion of “ control of the social order , based on the universe of affinity and , therefore , of masculinity . The hypothesis of “ sexual equality , in its turn , could be anchored in the production and dynamics of the social life of this system in which “ masculine ” and “ feminine ” correspond to complementary roles is strict equilibrium . Enawene Nawe ethnographic data provides support for both of these hypotheses as long as we realize that they are two faces of the same coin . We have already noted that rites that produce sexuality associate feminity and masculinity with consanguinity and affinity , respectively . We then saw how consanguinity and femininity articulate internally with one another to identity and to gender relations while affinity and masculinity and masculinity articulate exxternally to difference and to kinship relations . Finally , we noted that gender and kinship correspond to cosmological organizing principles that hold not only between living beings but also in organization of the entire universe . The Enawene Nawe operation in such a manner that gender opposition is most visible in the world of beings in “ self relations ” when represented in terms of the relation between the Enawene Nawe and their “ Identical - Others ” ( humans and celestial spirits ) while the kinship opposition appears to be most what is highlighted in the world of difference of the “ relations between others ” ( between humans and subterranean spirits ) The Javaé of Bananal Island , a Karajá subgroup studied by Patrícia Rodrigues provides an extremely interesting counterpoint to the Enawene Nawe case . According to the Javaé , time may be divided into two periods - an anterior period marked by the absence of sexual relations and a present period characterized by sex and procreation . Javaé cosmology centers around the opposition between two beings , the aruanã and the aõni . The first are the original humans who have been unsuccesful in escaping from the primitive aquatic world . Among these reigns the empire of consanguinity in a world in which neither aging nor death exists and food is abundant . Although they are endowed with sexuality and beautiful physiques , there is no sex life because all are brothers and sisters to one another . During rituals their movements are controlled and contrained while they sing beautiful and rhythmically well defined melodies . In contrast , the aõni inhabit an invisible terrerstrial dimension and are strangers to one another . Although sexual differences cannot be observed among them , they are highly sexual and insaciable . They emit unintelligible grunts and are ugly , agitated , impulsive and profoundly avaracious . According to the Javaé , incest or miserliness with food results in humans being transformed into these creatures . Humans are situated at an intermediate point between the absolute consanguinity of the aruanã and the absolute affinity of the aõni . Javaé ceremonial life takes its central theme to be the control of the aõni by the aruanã . In this contexts , the lyrics of the songs of the aruanã stress the immeasurable sexual appetite of the aõni in contrast to their disinterest in sex . The Javaé say the aõni are the “ wives ” of the aruanã . Beyond the ethnographic differences between the Javaé and the Enawene Nawe it is very tempting to draw parallels between their respective spirit worlds . A comparison of the Javaé and the Enawene Nawe allows us to immediately affirm that gender and kinship categories are indissociable in both cases . However , the association between the two orders is not formed in the same manner in both cases . While the Enawene Nawe conjoin affinity and masculinity and consanguinity and femininity , the contrary occurs among the Javaé . For these people affinity is feminine and consanguinity is masculine . In summation , Amerind thought seems to present different possibilities for the combination of the signs of gender and kinship . We can therefore conclude that any ethnographic generalization based on the a priori association between a given gender and a given kinship relation will be untenable . A native model This perspective on the analysis of gender relations enables us to grasp native concepts regarding gender . The spoken language of the Enawene Nawe contains categories that express sexual dimorphis : ena ( man , masculine , male sex ) and wiro ( woman , feminine , female sex ) which can be used for humans as well as animals and spirits . The native terms for the genitalia are akositi and talasiti , “ vagina , ” and “ penis , ” respectively . Moreover , the language contains gender suffixes - re and - lo ( e . g . yaya - re / yaya - lo , “ masculine and feminine shame ) . With the association of gender suffixes and the terms that designate the genitalia , the Enawene - nawe generate a new pair of concepts in the field of gender relations , akosita - re and talasita - lo , in order to designate sexually active men and women , respectively . A morphological analysis of these terms results in the following literal translation : akosita - re = “ vagina + masculine gender suffix ” talasita - lo = “ penis + feminine gender suffix ” The native classification thus appears to corroborate precisely the perspective of sexuality as a system of signs ( of relation ) rather than a mere opposition between substantive attributes . Moreover , the categories of gender define a system that articulates two assymmetrical oppositions ( term and relation ) and the inverse ( according the to sexual perspective ) , whereby the term ena ( man ) is to the relation talasita - lo ( woman - for - a - man ) as the term wiro ( woman ) is to the relation akosita - re ( man - for - a - woman ) . We can sum up by concluding that the genital organ of a gender is the sexual organ of its gender opposite . References ALENCAR SÁ , Cleacir . 1996 . As fases da vida : categorias de idade enawene ( ru ) nawe . Ms . Cuiabá : OPAN - Operação Amazônia Nativa COSTA JR . , Plácido . 1995 . A pesca na sociedade enawene - nawe . In Estudo das Potencialidades e do Manejo dos Recursos Naturais na Área indígena Enawene Nawe . OPAN , dat . DUMONT , Louis . 1971 . Introduction à deux théories d anthropologie sociale . Mouton . ___________ . 1983 . Stocktaking 1981 : affinity as a value . In Affinity as Value : Marriage Alliance in South India with Comparative Essays on Australia . Chicago : University of Chicago Press , pp . 145 - 214 LÉVI - STRAUSS , Claude . [ 1949 ] 1967 . Les Structures Élémentaires de la Parenté . Mouton . ( 2nd edition ) MENDES DOS SANTOS , Gilton . 1995 . Agricultura e coleta enawene - nawe : relações sociais e representações . In Estudo das Potencialidades e do Manejo dos Recursos Naturais na Área indígena Enawene Nawe . OPAN , dat . OVERING , Joanna . 1984 . Dualism as an expression of difference and danger : marriage exchange and reciprocity among the Piaroa of Venezuela In Kensinger , Kenneth , org . Marriage Practice in Lowland South American Societies . University of Illinois Press . RODRIGUES , Patrícia de Mendonça . 1995 . Alguns aspectos da construção do gênero entre os Javaé da ilha do Bananal . In Cadernos Pagu nº 5 , pp . 131 - 146 . PAGU : Núcleo de Estudos de Gênero / UNICAMP . SILVA , Marcio . 1995 . Estrutura social enawene - nawe : um rápido esboço . In Estudo das Potencialidades e do Manejo dos Recursos Naturais na Área indígena Enawene Nawe . OPAN , dat . __________ . 1996 . O princípio do ‘ terceiro incluído ’ no parentesco sul - americano : o caso enawene - nawe . m . s . Conferência apresentada ao ciclo 6a . do mês , USP / FFLCH , em 18 de outubro de 1996 , dat . VIVEIROS DE CASTRO , Eduardo . 1986 . Araweté : os deuses canibais . Rio de Janeiro : J . Zahar Editor . __________ . 1990 . “ Princípios de parâmetros : um comentário a L Exercice de la Parenté . Comunicação do PPGAS , Vol . 17 . __________ . 1993 . Alguns aspectos da afinidade no dravidianato amazônico . In Viveiros de Castro , E . & Carneiro da Cunha , M . ( orgs . ) Amazônia : etnologia e história indígena . EDUSP / NHII . [ 1 ] Mestre em Lingüistica pela Universidade Estadual de Campinas , com dissertação sobre fonologia de uma língua tupi do Alto Xingu ( kamayurá ) , e Doutor em Antropologia Social pelo Museu Nacional , com uma tese sobre parentesco em um povo carib da Guiana ( waimiri - atroari ) . É atualmente Professor do Departamento de Antropologia da Universidade de São Paulo , onde desenvolve pesquisa sobre um povo aruak da Amazônia meridional ( enawene - nawe ) . Nos últimos dois anos publicou os artigos “ Linguagem e Parentesco ” ( Revista de Antropologia v . 42 n . 1 / 2 , 1999 ) , “ Tempo e espaço entre os Enawene - Nawe ” ( Revista de Antropologia v . 41 n . 2 , 1998 ) e “ Masculino e feminino entre os Enawene - Nawe ” ( Sexta - Feira , n . 2 , 1998 ) . Seus temas de interesse são parentesco , estruturas sociais sul americanas , lingüística e antropologia . [ 2 ] These designations ( male domination ” and “ sexual equality ) must be understood as shorthand labels . Clearly , we are not dealing with a debate between supporters of an unchanging “ primitive machismo ” and defenders of a paleolithic “ égalité . ” Here it is only necessary to emphasize the distinction between perspectives that define , in Amerindian societies , gender relations as either hierarchical or symmetrical . [ 3 ] For a vision of the relation between these rites and Enawene Nawe age categories , see the text by Cleacir Alencar Sá ( 1996 ) . The ethnography presented here about these rites derives from this research which was conducted with my guidance . [ 4 ] The symbolism of honey and of porridge , defined respectively as “ masculine vaginal mucus ” and “ feminine semen ” calls to mind the classic example of the Araweté ( Viveiros de Castro 1986 ) .

Indian Journal of Human Genetics , Vol . 8 , No . 2 , Jul - Dec , 2002 pp . 52 - 59 Review Article p53 in Brain Tumors : Basic Science Illuminates Clinical Oncology Chitra Sarkar , Sanjay Mukhopadhyay , Mehar Chand Sharma Departments of Pathology , All India Institute of Medical Sciences , New Delhi , India . Address for correspondence : Dr . Chitra Sarkar , Professor , Room No . 1083 , 1st Floor , Department of Pathology , All India Institute of Medical Sciences , Ansari Nagar , New Delhi 110029 , India . E - mail : sarkarcs @ hotmail . com Code Number : hg02011 p53 is a tumor suppressor gene known as the " guardian of the genome " It protects cells from cancer , by preventing cells with damaged DNA from proliferating wantonly . This function is achieved by various unique mechanisms . These include cell - cycle arrest , which facilitates cell repair ; and apoptosis , which ensures the death of cells too severely damaged to be repaired . We discuss these mechanisms and their significance in tumor biology . The p53 gene enjoys the dubious distinction of being the single most common target for genetic alteration in human tumors . We discuss here the role of p53 and its mutations in astrocytomas and other brain tumors . The study of p53 in astrocytomas is one of the prime examples of the close and fruitful collaboration between molecular biology and clinical practice . After decades of research , it is now accepted that p53 is involved both in the initiation as well as the progression of astrocytomas . A multi - step sequence for the evolution of astrocytomas to glioblastomas has been elucidated . The prognostic significance of p53 expression in brain tumors has also been a matter of extensive research . Finally , we touch upon the therapeutic implications of p53 in astrocytomas . Given the dismal consequences of the absence , malfunction or mutation of this gene , many workers have tried to halt the progression of tumors by reintroducing the wild - type gene as a form of biological therapy . This approach , conceptualized in the laboratory and actualized at the bedside , holds much promise for the treatment of these challenging tumors . p53 : The Gene and the protein p53 is a tumor suppressor gene located on the short arm of chromosome 17 at band 13 . 1 and consists of 11 exons . The major role of p53 is the maintenance of genomic stability . It is therefore referred to as the " guardian of the genome " and is thought to be a critical " gatekeeper " , guarding against the formation of cancers . 1 There is evidence to show that p53 acts as a " molecular policeman " in preventing the propagation of genetically damaged cells . 1 , 2 This function is accomplished either directly by the participation of p53 in mechanisms that maintain DNA integrity , or indirectly , by the induction of cell - cycle arrest , senescence , or apoptosis of damaged cells . 2 More recent data shows that p53 also has an important role in angiogenesis and tumor invasion , two processes fundamental to malignancy . 2 The protein p53 , derived from the p53 gene is named for its biochemical nature ( phosphoprotein ) and its molecular mass ( 53 kilo daltons ) . It is also called tp53 , or tumor protein 53 . Three independent groups , using different approaches 3 - 5 to the study of tumorigenesis , discovered p53 in 1979 . Functions of the p53 gene ( i ) p53 senses DNA damage and then induces growth arrest or apoptosis The p53 gene is summoned to action only when DNA is damaged . p53 functions primarily to control the transcription of other genes , the goal being to limit the proliferation of potentially cancerous cells containing damaged DNA . This involves augmentation or enhancement of the p53 gene product by a mechanism that is poorly understood . In any event , enhanced p53 acts as a transcription factor by binding to DNA . The genes that it then transcribes function to attain cell cycle arrest and / or apoptosis . ( ii ) p53 and cell - cycle arrest p53 suppresses the cell cycle at the G1 / s and G2 / m transitions . To cause cell cycle arrest , p53 recruits the phosphoprotein p21 ( also called Cip1 ) in what has become known as the p53 / mdm2 / p21 pathway . p21 is a 21 - kilo dalton ( kda ) protein encoded by the cdkn1 gene , that acts as a cdk ( cyclin - dependent kinase ) inhibitor . 6 It inhibits a range of cdk / cyclin complexes required for cell - cycle progression . The inhibition of cdk / cyclin complexes by p21 in turn prevents the phosphorylation of the retinoblastoma ( Rb ) gene that normally allows cells to move from the G1 to the S phase of the cell cycle . This pause in cell cycling ( " G1 arrest " , the raison d ' être of p53 ) is a welcome breather for the cell , during which the damage inflicted on DNA by mutagens is repaired . 7 To achieve this repair , p53 activates the transcription of a DNA - repair protein called gadd45 ( growth arrest and DNA damage - inducible ) . 8 If gadd45 succeeds in its mission , p53 selflessly calls for its own down - regulation ( by activating a gene called mdm2 or murine double minute - 2 ) 9 and cell division is allowed to proceed as before . This sequence is illustrated in figure 1 . ( iii ) p53 and apoptosis However , if gadd45 fails in its endeavor to repair the DNA damage , p53 consigns the potentially malignant cell to its death . To this end , p53 activates the apoptosis - inducing gene bax and the death receptor Gd 95 ( also known as Fas / Apo1 ) while inhibiting the expression of the apoptosis - inhibiting protein bcl2 . Thus , p53 has a pro - apoptotic function . 10 Tp53 gene mutations The p53 gene enjoys the dubious distinction of being the single most common target for genetic alteration in human tumors . 11 , 12 This is possibly because of the diversity of the biological pathways in which p53 is involved . All classes of mutations , deletions , insertions , transitions and transversions occur in the Tp53 gene . Several mutational " hot - spots " have been observed in the p53 gene , all of which occur within four highly conserved amino acid sequences ( exons 5 to 8 ) . Although more than 250 codons in the Tp53 gene are potential human mutation sites , the most frequently observed mutations are found in only 5 of these codons - 175 , 245 , 248 , 249 and 273 . 13 There are two ways in which both alleles of a pair of p53 genes can be knocked out and rendered ineffectual . In most cases , both inactivating mutations occur in somatic cells of the organism . Less commonly , some individuals inherit a mutant allele in germ - line cells . All that is then needed to inactivate the normal allele is a second " hit " during the life of the individual . Such individuals are said to have the Li - Fraumeni syndrome , and have a 25 - fold greater chance of developing a malignancy by 45 to 50 years of age compared with the general population . 14 A wide variety of tumors , e . g . sarcomas , breast cancer , leukemia , brain tumors and adrenocortical carcinomas occur in these patients . Further , these tumors tend to occur at younger ages and are prone to multiplicity when they occur as part of the Li - Fraumeni syndrome . p53 mutations can have three consequences . 15 Loss of functions inherent to wild - type p53 Dominance of the mutant p53 protein over the wild - type p53 protein ( the " dominant - negative effect " ) . The acquisition of transforming potential in the mutated p53 , independent of its effect on the wild - type p53 . Wild - type and Mutated p53 protein The " normal " p53 protein is called " wild - type p53 " , as opposed to the deranged " mutated " p53 that occurs in tumors . Under physiologic conditions , the half - life of wild - type p53 protein is short ( 15 - 30 minutes ) , presumably because of ubiquitin - mediated proteolysis . As a result , wild - type p53 protein is present at very low levels in normal cells 16 and is undetectable by immunohistochemistry . In contrast , the half - life of mutant p53 protein is in the range of hours , resulting in high , immunohistochemically detectable levels of the protein . For all practical purposes , therefore , if the protein can be detected in tissue sections by immunohistochemistry , it is assumed that the gene is mutated . 16 However , this generalization is not absolute . Thus , not every mutation of the p53 gene results in immunohistochemically detectable p53 overexpression 17 . By the same token , not all immunohistochemically detectable p53 protein positivity results from p53 gene mutations . Indeed , many p53 immunopositive cases are not the result of accumulation of mutant p53 protein , but rather are due to accumulation / overproduction of wild - type p53 protein . The accumulation could either be through binding of wild - type p53 to altered cellular or viral proteins or simply due to accumulation of wild - type p53 in rapidly dividing tumor cells independent of p53 mutation . Another possibility is the stabilization of wild - type p53 protein by formation of complexes . 18 , 19 Further , in a study on 40 astrocytomas it was found that p53 immunopositivity was governed not by alterations of the p53 gene itself but by other putative tumor suppressor genes in the chromosomal region 17p13 . 3 . 20 Similarly , tumors with p53 gene mutations but with p53 protein immunonegativity have been reported . This has been attributed to synthesis of truncated protein which either lacks or cloaks the epitopic region or prevents its binding to proteins that prolong its half - life . 19 Thus , p53 immunohistochemistry may reflect several different biological conditions other than p53 gene mutation . However , immunohistochemistry for p53 protein will continue to play a significant role in characterizing the biology of this protein in neoplastic conditions because of the relative ease of the methodology compared to standard molecular techniques . p53 in brain tumors Here we review the role of p53 in brain tumor development . We will concentrate on astrocytic tumors , which are the commonest primary brain tumors , and in whom p53 plays the most significant role . The role of p53 in other tumors will be mentioned briefly . The many findings in recent years that have demonstrated the importance of the p53 gene in the development of astrocytic tumors will be highlighted . We will also discuss the potential use of wild - type p53 in the therapy of tumors in which the normal p53 pathways are disrupted or dysfunctional . p53 in astrocytic tumors According to the who , 21 these tumors can be divided into four grades : Pilocytic astrocytoma ( WHO grade i ) Diffuse astrocytoma ( WHO grade ii ) Anaplastic astrocytoma ( WHO grade iii ) Glioblastoma multiforme ( WHO grade iv ) ( i ) The role of p53 in astrocytoma initiation / early astrocytic tumorigenesis Evidence for causal involvement of p53 in glial tumorigenesis came from the finding that expression of exogenous wild - type p53 in glioblastoma cell lines suppressed their growth . 22 In addition , tissue culture experiments conducted on the cortical astrocytes of mice indicated that loss of function of p53 resulted in the immortalization of these cells . In addition , these murine cells lacking p53 activity became aneuploid , an observation that was in keeping with the aneuploidy seen in human astrocytomas with p53 mutations . 23 The notion that p53 mutations are an important factor in the genesis of brain tumors was also supported by the observation that patients with the Li - Fraumeni syndrome ( see above ) have a high ( 13 % ) incidence of brain tumors early in life . 24 The majority of brain tumors in the Li - Fraumeni syndrome are indeed astrocytomas , in which the p53 gene is frequently mutated . 25 These observations are important because mutations in the germ line ( as seen in p53 mutations in malignancies of the brain , breast , bone and soft tissue ) are believed to be " mutator " mutations , initiating tumor formation . Allelic loss of chromosome 17p 26 and mutations of Tp53 have been observed in approximately one - third of adult astrocytic tumors of who grades ii , iii and iv , suggesting that inactivation of p53 is an early event in the formation of grade ii tumors . In concordance with the p53 gene mutation , increasing incidence of p53 protein reactivity has been reported with increasing grades of malignancy . 27 - 29 grade ii : 18 - 46 % , grade iii : 29 - 57 % , grade iv : 49 - 70 % . Most Tp53 studies have concentrated on the conserved exons 5 to 8 . However , some studies that have included all the coding sequences ( exons 2 to 11 ) found only a handful of mutations outside exons 5 to 8 . The three most commonly mutated codons reported , in order of frequency , are 273 , 248 and 175 . In other human tumors , the most frequently mutated codons are 248 , 249 and 175 . However , there are no data indicating the role of brain tumor - specific mutations . 11 , 13 , 30 ( ii ) p53 in malignant progression of astrocytic tumors Recurrence and malignant transformation are important features of astrocytic tumors . 19 , 31 Two distinct types of glioblastoma are now recognized , based on the types of genetic alterations that characterize them . Primary glioblastomas These glioblastomas rarely show p53 mutations ( only approximately 10 % have p53 mutations ) but rather have amplification of the epidermal growth factor receptor ( EGFR ) gene on chromosome 7 , platelet - derived growth factor receptor ( PDGFR ) gene amplification , loss of deleted in colon carcinoma ( DCC ) gene expression , and loss of heterozygosity ( LOH ) involving chromosome 10 . 32 These abnormalities are typically found in older patients with a short clinical history and no evidence of progression from a lower grade astrocytoma . These tumors are hence termed primary , or de novo , glioblastomas . 32 Secondary glioblastomas More than 65 % of these glioblastomas show p53 mutations , of which more than 90 % were already present in the first biopsy ( original tumor ) . They occur in younger patients whose tumors have progressed from a lower grade astrocytoma over a comparatively long time period . It is possible that the genomic instability associated with p53 loss facilitates the accumulation of additional genetic mutations that promote the transformation to secondary glioblastomas . Studies that have compared pairs of primary and recurrent astrocytic tumors have found that both sets of tumors harbored similar p53 mutations . The percentage of glioma cells with p53 protein increased from the first biopsy , suggesting that the recurrence or progression occurred by clonal expansion of the p53 - mutated cells in the primary tumor . 33 - 35 Our own data show that the percentage of tumors that are p53 positive increases at recurrence , irrespective of the initial grade of the tumor . Thus , 56 . 25 % of primary tumors were initially p53 positive , while in recurrent tumors associated with malignant progression this frequency increased to 70 . 83 % . Further , recurrence was associated with increase in the percentage of p53 immunopositive cells . No case that was initially p53 - positive in our study became negative at recurrence . In conformity with the literature , we found a higher degree of p53 - positivity in secondary glioblastomas ( 84 % ) compared with de novo glioblastomas ( 43 % ) 27 . These genetically distinct types of glioblastoma cannot be distinguished on histological grounds alone , and it remains uncertain whether survival after diagnosis is different in these groups . 32 , 36 p53 brain tumors To summarize , although the role of p53 in the recurrence and progression of astrocytomas is still debated , there is growing evidence 34 , 37 - 40 that : a ) Genetic alterations occur with equal frequency both in low - and high - grade astrocytoma , indicating a role for p53 in the formation / initiation of low - grade disease . b ) p53 also has a role in the progression from low - grade astrocytoma to secondary glioblastoma . c ) p53 as a prognostic factor in astrocytic tumors p53 mutations correlate with prognosis in a number of human cancers , including cancers of the breast , stomach , colorectum and lung . 41 , 42 In these tumors , a high rate of p53 mutation connotes increased tumor aggressiveness , a high metastatic rate and poor prognosis . The predictive role of p53 mutations in astrocytomas however is still poorly understood . Recent studies indicate that in low - grade astrocytomas that progress to glioblastoma , the frequency of p53 mutations is very high , of the order of 58 - 83 % . 28 , 43 Neoplasms with p53 mutations also appear to progress more frequently than neoplasms without the mutation , but evidence for this correlation remains circumstantial . 44 - 46 The time interval to progression appears to be shorter in patients with low - grade astrocytomas that carry a p53 mutation . 28 Hence , it seems that low - grade astrocytomas with p53 mutations progress to glioblastomas faster and more often than tumors without these mutations . The effect on patient survival , however , is still murky , with some studies showing that p53 mutations have no effect on clinical outcome and survival . 45 , 47 , 48 Others propose that low - grade astrocytomas that carry a p53 mutation appear to be associated with a shorter survival . 49 It must be noted that some of these studies are based on childhood malignant gliomas , which may be biased because p53 mutations in children occur almost exclusively in brainstem gliomas , which are known to have a very poor prognosis . On the other hand , the relatively poor prognosis of gemistocytic astrocytomas may be due to the fact that they have a higher frequency of p53 mutations . In contrast , some authors claim that the existence of p53 mutations in recurrent high - grade tumors may indicate a better prognosis . 29 Our studies have shown that p53 positive anaplastic astrocytomas had significantly shorter symptom - free survival than p53 negative tumors . No difference in survival , based on p53 positivity , was observed in the glioblastoma multiforme group2 . 7 , 50 p53 in other brain tumors In contrast to astrocytomas , p53 mutations do not seem to play a significant role in the evolution of ependymoma , 51 pineocytoma / pineoblastoma 52 or medulloblastoma ( in which p53 mutations are found in only 5 - 10 % of cases ) . 53 The role of p53 in pilocytic astrocytoma 25 , 54 is controversial . Earlier studies have reported a low mutation frequency in these tumors , whereas some recent studies that have used more inclusive mutation detection systems have reported that p53 mutations may occur in up to 35 % of pilocytic astrocytoma . 55 Other neoplasms in which p53 mutations do occur include gliosarcoma , 56 oligodendroglioma and mixed oligoastrocytoma . 57 - 59 Two studies on oligodendrogliomas suggest that the demonstration of p53 in tumor cells is associated with reduced patient survival . 58 , 59 p53 in Gene therapy It was not long before the scientific community realized that p53 was ideal for therapeutic use . It was observed that radio - and chemo - sensitive tumors such as teratocarcinomas and childhood acute lymphoblastic leukemias shared the property of retention of the normal p53 gene and protein . 60 In contrast , radio - and chemo - resistant tumors such as non - small cell lung cancers and colon cancers , frequently carried p53 mutations . These observations gave rise to the theory that chemotherapeutic agents killed cells by inducing apoptosis rather than by causing cellular damage 61 . p53 is now being used in therapeutic trials in which wild - type p53 is being introduced into tumors with p53 mutations . This maneuver is expected to restore the chemosensitivity of these tumors . 62 , 63 Wild - type p53 has also been used as a stand - alone therapy , with the expectation that it would induce tumor cell death by senescence and apoptosis . 64 So far , the vector of choice for the transfer of p53 into cells seems to be the adenovirus . 64 , 65 Many such studies have been conducted using animal models or experimental glioma cell lines , and have shown encouraging responses to the introduction of wild - type p53 , including apoptosis , inhibition of tumor growth and even tumor regression . 64 - 66 Phase I clinical trials are currently being conducted to clarify whether specific and non - specific cytotoxic effects may occur after p53 therapy . An extended family : the " Big Brother " of p53 For almost 20 years after its discovery , the p53 gene was the only known gene of its kind , both structurally and functionally . That changed in 1997 with the discovery of the p73 gene , dubbed the " Big Brother " of p53 67 . Located on 1p36 , this gene encodes a protein similar to the p53 protein , its talents including cell cycle arrest and apoptosis . 68 Deletions of the gene locus for p73 are common in a variety of tumors , including neuroblastoma and colon and breast cancers . Much interest is now focused on this " relative " of the p53 gene . References Levine AJ , Momand J , Finlay CA . The p53 tumor suppressor gene . Nature 199 ; 351 : 453 - 6 . Fulci G , Ishii N , Van Meir EG . P53 and brain tumors : from gene mutations to gene therapy . Brain Pathol 1998 ; 8 : 599 - 613 . Lane DP , Crawford LV . T antigen is bound to a host protein in SV40 - transformed cells . Nature 1979 ; 278 : 261 - 3 . DeLeo AB , Jay G , Appella E , Dubois GC , Law LW , Old LJ . Detection of a transformation - related antigen in chemically induced sarcomas and other transformed cells of the mouse . 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An INEA executive statement by Dave Rossin Assisted by Gerald Clark , Jorge Spitalnik , Robert Nickell . , Dan Meneley , Manning Muntzing , Bertrand Barre , Walter Kato and several others SUMMARY QUESTIONS THAT ARE ASKED ABOUT NUCLEAR POWER PLANTS : What could terrorists do to nuclear power plants , spent fuel storage or fuel cycle facilities ? Could terrorists cause the release of radioactivity ? What harm could come to individuals or populations from radioactivity released or spread by terrorists ? We have chosen to discuss these questions to provide a sound overview for people to consider . The brief answers to our questions are : While actual damage would be hard to inflict , facilities would be forced to shut down for inspection and damage assessment , and might be kept down for extended periods for political re - examination of policy issues . It is very unlikely that any significant amounts of radioactivity would be released . It is hard to imagine any way for actual harm to come to either individuals or populations from radioactivity . In summary , our examination of these questions leads to an important finding : Public confusion and even panic could pose far greater risks than physical damage to facilities or actual dangers from potential exposure of people to radiation . MAIN PAPER After 9 / 11 there was a rush of TV and newspaper reports about important places and their potential vulnerability to terrorist attacks . Typically , statements included concern about the ability of nuclear power plants to withstand terrorist attacks , from World Trade Center - type airplane strikes to assaults by trained and heavily - armed cadres . Expert statements in response were often met with skepticism , but the facts and engineering realities are very clear : nuclear plants represent hardened targets and already had strong security forces in place . The charge was made that nuclear plants were not designed for such attacks . They were not . That concept was not in the minds of the designers and regulators . Their objective was to keep radioactivity and contamination WITHIN the facility in the event of an accident . After 9 / 11 , analysts re - examined the designs of nuclear plant systems and structures . The major design criterion that contributes to the ruggedness of the reinforced containment buildings that surround the primary reactor system is the requirement to withstand internal pressure during an accident without leakage . This ruggedness enables reinforced concrete containment structures to protect against winds of up to 300 miles per hour , a telephone pole or tree as a missile carried by such a hurricane or tornado , and flammable liquids such as gasoline or oil . The barriers to protect against radiation releases have proved to be very robust . An attack that could damage auxiliary equipment or electrical switchyards would be a serious matter , but the reactors were designed for safe shutdown even if these systems were lost . During the mid - 1970 s , the U . S . AEC initiated classified studies on the potential for sabotage at commercial nuclear power plants . The work was done at Sandia Laboratories with teams of engineers with nuclear plant design and operating experience working alongside weapons designers and top security experts . The studies showed that even if knowledgeable insiders could disable key safety equipment , redundant systems would provide backup protection . In scenarios where all engineered safety systems were ruined , there was still a period of hours to take corrective actions before onset of core damage . The containment structure is the outer plant barrier of defense - in - depth . Major damage to massive walls and pipes would have to be caused before radiation could be released outside the containment building . As a result of these and other studies , recommendations were made that added to defense against both external and internal threats . An example is the " two - man rule " that precludes a single individual from being in the containment alone and possibly out of sight of a person or tele - monitors . The analysts also noted that the larger the number of adversaries in the scenario , the higher the likelihood of detection and neutralization . Intelligence services of nations have a better chance of discovering plots , especially now that they are better prepared and supported . The AEC followed the study with extensive regulations that required hardened guard positions , weapons training and security fences . In 2002 the Nuclear Energy Institute requested the Electric Power Research Institute to study the potential damage that could be caused by deliberately crashing a large commercial jet airplane into containment structures at nuclear power plants , as in a World Trade Center scenario . Detailed structural analyses showed that a direct strike by either the fuselage or an engine would not breach or perforate post - tensioned or reinforced containment walls except at unrealistically high impact velocities . Through - wall penetration was found for reinforced concrete shield buildings on the exterior of free - standing steel containment structures , but no subsequent failure of the steel shell was shown . Penetration of other , less rugged structures , such as BWR reactor buildings , auxiliary buildings , and diesel - generator buildings causes extensive dispersal of jet fuel and fire damage . However , even penetration and fire damage should not prevent safe shutdown . [ An unclassified press release on the NEI / EPRI study was issued in January 2003 , and excerpts were published in the February 2003 issue of Nuclear News . The work was presented to the Nuclear Regulatory Commission staff in December 2002 and to the Advisory Committee on Reactor Safeguards in June 2003 . ] In the 1980 s Canada s Ontario Hydro Co . studied the possible effects of crashing a 747 into a containment building at a commercial CANDU reactor . A perfect hit was assumed , with all four engines impacting the building at the same time . The analysis showed that although there would be some concrete spallation off the inside of the walls , but no building penetration would occur . After 9 / 1l , several nuclear adversary groups published articles which claimed that spent fuel storage pools would be vulnerable to aircraft attack . In fact , some pools are covered by light structures . While roofs could be destroyed , the pools themselves have very thick reinforced concrete walls . These walls are generally behind other large structures like water storage tanks and equipment bays , and would be very difficult to breach . The pool water above the stored spent fuel is 10 to 20 feet deep , and would deaden the impact of debris falling from overhead . Safety of spent fuel in a storage pool depends on keeping the fuel under water . Draining of pool water is extremely unlikely , and there are many actions that could be taken to pump more water into a pool , if that should ever become necessary . The conclusion of the sabotage work and of numerous other studies on accidents and attacks on power reactors is that while not impossible , the likelihood of actual release of a significant amount of radioactivity is extremely low . Thus , the probability of actual radiation exposure to members of the public from a terrorist attack or sabotage is also extremely low . Nevertheless , it is widely recognized that any attack on a nuclear facility would result in sensational news reporting and front page media attention . The actions of the 9 / 11 suicide terrorists served warning that nuclear facilities should be re - examined for new types of threats . Additional physical barriers , detection equipment and inspection procedures for incoming trucks and other shipments have been added . Personnel security has been upgraded . Guard forces now have night detection equipment , more advanced weapons and more intense training . These technical discussions refer specifically to licensed U . S . water - cooled power reactors . Many power reactors in other nations comply with criteria based on USNRC regulations . Other designs including Soviet - design reactors have been examined on a case - by - case basis . Security has become a higher priority at every nuclear station around the world . Although information is not public , threat reduction technology and training suitable to specific plants and sites have been upgraded . The IAEA and WANO provide advice and assistance ; however each nation is responsible for the safety and security of its own facilities . Since 9 / 11 , managers of power reactors , as well as bridges , dams and tall buildings all over the world , have re - examined and strengthened their security programs . Operation and Security : All nuclear power plants are required to have security plans . Security personnel are trained to operate detection and surveillance systems , to handle firearms , and to understand directions and orders of security managers . New and more rigorous training programs have been developed and are being conducted at all plants . A basic principle of security planning is secrecy of the plan itself is that plans cannot be published or released to members of the public . Only properly authorized persons should have access to security plans , and in some cases , only to the portions of the plans they need to know . Success of security may turn on the potential adversary not being sure of , or even aware of , fundamental aspects of plans . There is no justification for exceptions to this policy , even in the case of nuclear power plants for which the tradition has been to include public participation in the licensing process . Communications plans are vital elements of an emergency plan . These plans are the vehicles for setting up cooperation between state , county and local jurisdictions , law - enforcement departments , the NRC , FBI , the Coast Guard and the Department of Homeland Security . The 9 / 1l events have led to increased requirements for emergency drills . Drills are designed to test communications links , familiarity with emergency plan steps and requirements , and the ability of various administrative entities to work together . Drills are designed by experts to challenge participants . Rather than being just walk - throughs of pre - planned steps , drills are designed to find weaknesses and failures , and to fix them . A headline about a facility having " failures " in emergency exercises really means that drills are working , lessons will be learned , and improvements will be made . The US NRC has initiated a pilot program with a number of United States nuclear utilities to develop and test force - on - force drills which simulate an attack on a plant by a highly armed terrorist group . These drills not only test training and compliance with regulations , but contacts with local , regional and state law enforcement agencies , officials and the media . The purpose is to find problems and areas of improvement before these teams are ever needed . The nuclear power industry is the only private - sector entity that undergoes these kinds of exercises and security requirements . While expensive , they add to deterrence of attacks . Any adversary sophisticated enough to plan an armed attack would know that the chances of causing damage would be very small , and the risks of being thwarted or killed before reaching the plant are serious . Pathways for Releases of Radiation Real danger to members of the public would have to involve the dispersal of radioactive material . We have argued above that a terrorist attack is unlikely to result in any significant release of radioactive material , certainly nothing on the scale of Chernobyl , or even Windscale . These releases were caused by design characteristics and equipment problems , and further actions of operators and managers , not from any external attack . And despite the extensive publicity about radiation , the only deaths from the Chernobyl accident were plant workers . A number of thyroid cancers have been detected in children due to drinking of local cows milk . These cases have been treated successfully , according to IAEA studies . In the event of an actual radiation release , data from radiation detectors and modeling of wind and other weather conditions would be used to predict where and when any members of the public might be exposed . Most likely , members of the public would be best protected in the short term by remaining in their homes . Sheltering would best be achieved by staying inside a building , and that would certainly minimize the chance of breathing any contaminated air . Experts , both on radiation and on personal behavior , warn that the greatest risk would come from the possibility of panic . An attempt by a lot of people to evacuate a particular area in panic could result in accidents , fights , heart attacks , and more panic . Panic makes honest and verifiable reporting extremely important . For this reason , current emergency plans emphasize the need for nuclear plant managers to work with the local media in advance to build a better understanding of radiation hazard in terms of familiar immediate and long - term risks . Likewise , national and international nuclear organizations are strengthening their efforts to communicate effectively and to establish communication channels to major news outlets and organizations . Low Doses of Radiation and International Standards We live in a world where there is a small amount of background of radiation all the time . It comes from the Sun , from the earth s crust , and building materials . In the extended debate about nuclear power , the subject of effects on health from low additional doses of radiation has been confusing and even frightening to some people . Calculations of the possible effects of tiny additional amounts of radiation , similar to and often within the margins of variation of natural background levels , have been used to project the incidence of deadly cancers in a population . The theory is simple and the numbers are easy to calculate . The maximum theoretical numbers of cancers have often been turned into headlines . However , most experts recognize that these predicted numbers of cancers are not real . In fact , the generally used theory predicts a maximum theoretical number of cancer cases for an exposed population , and then states that the actual number is somewhere between that number and zero , and for low individual doses , it is most likely zero . Public Communication and the News Media It is impossible to overstate the importance of public understanding of nuclear power issues , of radiation and of threats from terrorism . Much of the present negative impression people have about radioactivity and nuclear power stems from our own failure as scientists and engineers , despite decades of effort , to build a broad public understanding of the basic scientific facts about radiation . That is why we believe it is important to work with journalists , local and national press , TV news producers and writers , and with interested elected representatives and their staffs . As more people with public responsibilities become better informed about radiation , safety and security , they will be able to ask the right questions and evaluate the answers they get . Then there is hope that if a terrorist attack ever occurs on a nuclear facility , the public is more likely to be better served with facts rather than sensational headlines . THIS IS AN EXECUTIVE STATEMENT OF THE INEA in collaboration with the International Nuclear Societies Council . It represents the views of the author but has been endorsed by the Executive Committee of the Academy as a contribution to the responsible development of civil nuclear energy .

by Arundhati Roy IVE been asked to speak about " How to confront Empire ? " Its a huge question , and I have no easy answers . When we speak of confronting " Empire , " we need to identify what " Empire " means . Does it mean the U . S . government ( and its European satellites ) , the World Bank , the International Monetary Fund , the World Trade Organization , and multinational corporations ? Or is it more than that ? In many countries , Empire has sprouted other subsidiary heads , some dangerous byproducts nationalism , religious bigotry , fascism and , of course , terrorism . All these march arm in arm with the project of corporate globalization . Let me illustrate what I mean . India the worlds biggest democracy is currently at the forefront of the corporate globalization project . Its " market " of one billion people is being prised open by the WTO . Corporatisation and Privatization are being welcomed by the government and the Indian elite . It is not a coincidence that the Prime Minister , the Home Minister , the Disinvestment Minister the men who signed the deal with Enron in India , the men who are selling the countrys infrastructure to corporate multinationals , the men who want to privatize water , electricity , oil , coal , steel , health , education and telecommunication admirers of the RSS . The RSS is a right wing , ultra - nationalist Hindu guild , which has openly admired Hitler and his methods . The dismantling of democracy is proceeding with the speed and efficiency of a Structural Adjustment Programme . While the project of corporate globalization rips through peoples lives in India , massive privatization , and labor " reforms " are pushing people off their land and out of their jobs . Hundreds of impoverished farmers are committing suicide by consuming pesticide . Reports of starvation deaths are coming in from all over the country . While the elite journeys to its imaginary destination somewhere near the top of the world , the dispossessed are spiraling downwards into crime and chaos . This climate of frustration and national disillusionment is the perfect breeding ground , history tells us , for fascism . The two arms of the Indian government have evolved the perfect pincer action . While one arm is busy selling India off in chunks , the other , to divert attention , is orchestrating a howling , baying chorus of Hindu nationalism and religious fascism . It is conducting nuclear tests , rewriting history books , burning churches , and demolishing mosques . Censorship , surveillance , the suspension of civil liberties and human rights , the definition of who is an Indian citizen and who is not , particularly with regard to religious minorities , is becoming common practice now . Last March , in the state of Gujarat , two thousand Muslims were butchered in a state - sponsored pogrom . Muslim women were specially targeted . They were stripped , and gang - raped , before being burned alive . Arsonists burned and looted shops , homes , textiles mills and mosques . More than a hundred and fifty thousand Muslims have been driven from their homes . The economic base of the Muslim community has been devastated . While Gujarat burned , the Indian Prime Minister was on MTV promoting his new poems . In January this year , the government that orchestrated the killing was voted back into office with a comfortable majority . Nobody has been punished for the genocide . Narendra Modi , architect of the pogrom , proud member of the RSS , has embarked on his second term as the Chief Minister of Gujarat . If he were Saddam Hussein , of course each atrocity would have been on CNN . But since hes not and since the Indian " market " is open to global investors the massacre is not even an embarrassing inconvenience . There are more than one hundred million Muslims in India . A time bomb is ticking in our ancient land . All this to say that it is a myth that the free market breaks down national barriers . The free market does not threaten national sovereignty , it undermines democracy . As the disparity between the rich and the poor grows , the fight to corner resources is intensifying . To push through their " sweetheart deals , " to corporatise the crops we grow , the water we drink , the air we breathe , and the dreams we dream , corporate globalization needs an international confederation of loyal , corrupt , authoritarian governments in poorer countries to push through unpopular reforms and quell the mutinies . Corporate Globalization - or shall we call it by its name : Imperialism - needs a press that pretends to be free . It needs courts that pretend to dispense justice . Meanwhile , the countries of the North harden their borders and stockpile - weapons of mass destruction . After all they have to make sure that its only money , goods , patents and services that are globalized . Not the free movement of people . Not a respect for human rights . Not international treaties on racial discrimination or chemical and nuclear weapons or greenhouse gas emissions or climate change , or - god forbid - justice . So this - all this - is " empire . " This loyal confederation , this obscene accumulation of power , this greatly increased distance between those who make the decisions and those who have to suffer them . Our fight , our goal , our vision of Another World must be to eliminate that distance . So how do we resist " Empire " ? The good news is that were not doing too badly . There have been major victories . Here in Latin America you have had so many - in Bolivia , you have Cochabamba ; in Peru , there was the uprising in Arequipa ; in Venezuela , President Hugo Chavez is holding on , despite the U . S . governments best efforts . And the worlds gaze is on the people of Argentina , who are trying to refashion a country from the ashes of the havoc wrought by the IMF . In India the movement against corporate globalization is gathering momentum and is poised to become the only real political force to counter religious fascism . As for corporate globalization s glittering ambassadors - Enron , Bechtel , WorldCom , Arthur Anderson - where were they last year , and where are they now ? And of course here in Brazil we must ask ... who was the president last year , and who is it now ? Still ... many of us have dark moments of hopelessness and despair . We know that under the spreading canopy of the War Against Terrorism , the men in suits are hard at work . While bombs rain down on us , and cruise missiles skid across the skies , we know that contracts are being signed , patents are being registered , oil pipelines are being laid , natural resources are being plundered , water is being privatized , and George Bush is planning to go to war against Iraq . If we look at this conflict as a straightforward eyeball - to - eyeball confrontation between " Empire " and those of us who are resisting it , it might seem that we are losing . But there is another way of looking at it . We , all of us gathered here , have , each in our own way , laid siege to " Empire . " We may not have stopped it in its tracks - yet - but we have tripped it down . We have made it drop its mask . We have forced it into the open . It now stands before us on the worlds stage in all its brutish , iniquitous nakedness . Empire may well go to war , but its out in the open now - too ugly to behold its own reflection . Too ugly even to rally its own people . It wont be long before the majority of American people become our allies . Only a few days ago in Washington , a quarter of a million people marched against the war on Iraq . Each month , the protest is gathering momentum . Before September 11 , 2001 America had a secret history . Secret especially from its own people . But now Americas secrets are history , and its history is public knowledge . Its street talk . Today , we know that every argument that is being used to escalate the war against Iraq is a lie . The most ludicrous of them being the U . S . governments deep commitment to bring democracy to Iraq . Killing people to save them from dictatorship or ideological corruption is , of course , an old U . S . government sport . Here in Latin America , you know that better than most . Nobody doubts that Saddam Hussein is a ruthless dictator , a murderer ( whose worst excesses were supported by the governments of the United States and Great Britain ) . Theres no doubt that Iraqis would be better off without him . But , then , the whole world would be better off without a certain Mr . Bush . In fact , he is far more dangerous than Saddam Hussein . So , should we bomb Bush out of the White House ? Its more than clear that Bush is determined to go to war against Iraq , regardless of the facts and regardless of international public opinion . In its recruitment drive for allies , the United States is prepared to invent facts . The charade with weapons inspectors is the U . S . governments offensive , insulting concession to some twisted form of international etiquette . Its like leaving the " doggie door " open for last minute " allies " or maybe the United Nations to crawl through . But for all intents and purposes , the New War against Iraq has begun . What can we do ? We can hone our memory , we can learn from our history . We can continue to build public opinion until it becomes a deafening roar . We can turn the war on Iraq into a fishbowl of the U . S . governments excesses . We can expose George Bush and Tony Blair - and their allies - for the cowardly baby killers , water poisoners , and pusillanimous long - distance bombers that they are . We can re - invent civil disobedience in a million different ways . In other words , we can come up with a million ways of becoming a collective pain in the ass . When George Bush says , " youre either with us , or you are with the terrorists , " we can say " No thank you . " We can let him know that the people of the world do not need to choose between a Malevolent Mickey Mouse and the Mad Mullahs . Our strategy should be not only to confront empire , but to lay siege to it . To deprive it of oxygen . To shame it . To mock it . With our art , our music , our literature , our stubbornness , our joy , our brilliance , our sheer - relentlessness - and our ability to tell our own stories . Stories that are different from the ones were being brainwashed to believe . The corporate revolution will collapse if we refuse to buy what they are selling their ideas , their version of history , their wars , their weapons , their notion of inevitability . Remember this : We be many and they be few . They need us more than we need

With one foot in the Nuclear Club and a middle class of 300 million of people who modernise themselves each day , the country will be the third largest economy by 2040 . By Florencia Costa : Special envoy to Hyderabad ( India ) The popular wisdom says that money attracts money – in India s case , it attracts money and much more . That s why the eyes of the world are looking for this country , the second most growing one of the globe , only behind China . India has been keeping for 25 years the admirable yearly average of 6 % - growth – in 2005 , it reached 8 % . And if it is being cherished for so long as an emerging economic power , India is now being treated as a skyrocketing giant also in the sandy lands of geopolitics . The US has just given to India a new status in the global chess : they offered India the key to enrol in the exclusive atomic club , whose partners are UK , Russia , France and China – besides US , of course . These nations are the only recognised as “ genuine ” holders of nuclear weapons . If India enrols in this privileged group ( the agreement must be submitted by the US Congress ) , India will be considered the sixth nuclear power , eligible to have access to the civilian nuclear technology of the US . It would be a golden opportunity for this country with more than 1 billion inhabitants and the sixth highest energy consumption of the globe . The Indian Prime - Minister Manmohan Singh is a brilliant economist with PhD in Oxford , and one of the responsible for the economic opening of the country during the 1990 s , when he was the Minister of Finance . He already warned : the growth of his country should continue steady and firm , as the “ steps of the elephants . In the end of last year , Singh forecasted that India would continue growing at an average yearly rate from 7 . 5 % to 8 % till 2008 . From this point , in his predictions , the most challenging prediction of reaching the 10 % - level . In the beginning of last March , George W . Bush visited New Delhi , and this was the third visit of an US President in a 28 - year - period . Bush agreed with the Indian Prime Minister an historical agreement that may finish with the Indian nuclear isolation . This hand given by Bush shows how much the US is betting high with this strategic partnership with the Indian emerging power . As per the agreement signed with the Yankees , India permits the inspection of 14 out of their 22 nuclear reactors . And , before Bush , Jacques Chirac signed a similar agreement with them . Both Bush and Chirac praises India , who left being a nuclear plague to become a “ responsible power . The agreement is polemical , as the country is not a signatory of the TNP . For decades , India has been developing its own nuclear programme , including for military purposes , and the critics of Bush s agreement say that he opened a door that will make more difficult the attempts to stop the ambitions of countries like Pakistan , North Korea and Iran . Putting geopolitical questions apart , with its economy growing more and more , India has an endless thirsty for energy sources . Nowadays , the country is the emerging star of the BRIC – Brazil , Russia , India and China . The acronym became famous with the Goldman Sachs Report about the growth perspectives of these emerging economies . India should be the third biggest economy of the world till 2040 and investors from everywhere are with their eyes on the Indian immense consumer market – the Indian middle class totals 300 million inhabitants ( the Brazilian population is of 180 million approximately ) . It is a social extract that is modernising each and every year , eager for new products and that is greater than the Brazilian population in 120 million people – a market that consumes US $ 200 bn annually in durable goods . The power of India goes much farther than the financial values : it is also in their famous brains . The country has been investing for years in higher education , it has one of the best technologic institutes of the world and graduates 3 million people a year , 700 thousand post - graduates and 1500 PhDs . Since the 1990 s , the country is becoming the nest of IT Enterprises and service companies like Call Centres . It also became famous for the development of biotechnology & pharmaceutical companies . The growth of the middle class sparked the expansion of markets like telephony , automotive and processed food . That s why Bush availed his visit as maximum as he could . Besides the nuclear pact , he negotiated economic agreements in views of doubling the commercial exchange between both countries till 2010 . Doubling means reaching US $ 30 billion ... ISTOE Weekly News Magazine , No . 1907 , 10 . 5 . 2006 , pages 106 ~ 108

" The Latin American Section of ANS has been able to gather , in its membership , an important portion of the professional and entrepreneurial nuclear community of Latin America . This feature has attracted to the Section firms and individuals from other regions of the world who share common interests and maintain business activities in Latin America . In this way , the Section has the means to serve as a forum of information exchange and individual relationship in a broad array of nuclear activities within a very large geographical area . This has been the result of an effort of almost a quarter of a century , which has allowed a continuous expansion of the LAS / ANS influence , not only within the Latin American countries , but also around the world through its active promotion of , and participation in international organizations like the INSC ( International Nuclear Societies Council ) and the PNC ( Pacific Nuclear Council ) . " Sérgio de Salvo Brito ( † ) 1977 - 1978 José Ribeiro da Costa ( † ) 1978 - 1979 Antonio E . F . Müller 1979 - 1981 Jorge Oscar Cosentino ( † ) 1982 - 1983 Witold P . S . Lepecki 1983 - 1984 LAS , along its more than one - quarter century of existence , fulfilled the following roles , which , in my opinion , are unique : By being the only regional organization of its kind , it integrated the nuclear communities of all the countries in the region ; By choosing to be a Section of the American Nuclear Society , rather than an autonomous Society , it integrated both the Latin American and North American nuclear technical communities , contributing to mutual understanding , not only at the technical level , but also in matters that are politically delicate ; By achieving , along the years , to represent Latin America with equal weight to other regions of the world in international organizations ( e . g . , INSC ) , it contributed , in an essential way , to project its nuclear technical community in the wider world - wide scene . Arthur Eduardo Gasparian ( † ) 1984 - 1985 Juan Eibenschutz 1985 - 1986 Ronaldo A . C . Fabrício 1986 - 1987 Miguel Medina Vaillard 1987 - 1988 Márcio Costa 1988 - 1989 Oscar Armando Quihillalt ( † ) 1989 - 1990 Evaldo Césari de Oliveira 1990 - 1991 Rafael Fernández de la Garza 1991 - 1992 Cláudio B . M . Campos 1992 - 1993 Professional societies which have an international approach are one of the best ways to amplify the integration of people and organizations which have similar interests . Under this perspective I must say that I was very pleased to receive the invitation to join LAS in middle 80 ' s . Having the opportunity to work together with my colleagues in LAS I was firstly involved in the task of integration of technical standards and after some years becoming LAS ' president in 1992 . I must say that it was a very enriching experience where I learned a lot and it helped me to improve my understanding and contacts in the globalization environment we are facing today in our personnal and professional lives . LAS is certainly an organization I will always be proud to be a member . Julio A . Recalde 1993 - 1994 Which are the three sentences that provide the best description of the LAS / ANS ' spirit , achievements and contribution to the community ? · An organization that has evolved from " representing the interests of the professionals in the nuclear arena " to " having reached a deserved prestige by representing and safeguarding the expectations of the Latin American community in as far as nuclear issues are concerned " . · An organization that , since its foundation , has always fostered and followed the path of a well - understood Latin American globalization . · A fourth of a century of ceaseless and productive work in the hands of a group of people who have enriched each other within the framework of an agreeable environment of professional friendliness . And , finally , as far as I am concerned , " an organization of which I will always be proud to be a member " . Pedro J . Diniz de Figueiredo 1994 - 1995 I think that the Latin America should have others organisations in other fields of activities , like the Latin American Section of ANS . It is a very privilegiated and unique forum for the nuclear business professionals . Several common problems and expectations were discussed and are frenquently discussed among the latin americans engineers and professionals . No other forum is available for such a discussion and interaction . During the period that I was president of LAS , I enphasized the important of developing the proper standard and regulations appropriated to every region . I still continue believing that commom regulations for the latin americans in the nuclear business would be a very strong point of common development . This policy would be of beneffit if others organisations in other fields of activities had the same common goal as the LAS . The Latin American Section of the ANS set a very good example how latin americans could work together in diferent areas of interest in benefitt of the whole Latin America . Carlos Vélez Ocón 1995 - 1996 Ayrton J . Caubit da Silva 1996 - 1997 Oscar José Quihillalt ( † ) 1998 - 1999 Olga C . R . L . Simbalista 1998 - 1999 In my opinion , the main role of the Latin American Section of the American Nuclear Society - LAS is to act as an integrating vehicle , non - governmental , of nuclear activities in the Americas . Since July 1998 , LAS contributed to get together local nuclear societies of Argentina ( Asociación Argentina de Tecnologia Nuclear - AATN ) , Brazil ( Associação Brasileira de Energia Nuclear - ABEN ) , Mexico ( Sociedade Nuclear Mexicana - SNM ) , Canada ( Canadian Nuclear Society - CNS ) as well as of the U . S . ( American Nuclear Society - ANS ) through meetings sponsored by LAS ( Buenos Aires Nuclear Symposium and Washington Meeting of the Americas ) . This integration was reinforced , in Acapulco , in July 1999 , during the International Joint Meeting on the Role of Nuclear Power to Mitigate Climate Change , co - sponsored by SNM , LAS , Federación Latino Americana de Sociedades de Protección Radiológica and Sociedad Mexicana de Seguridad Radiológica . José Francisco Torres Ramírez 1999 - 2000 Looking at the 21st century , Latin America faces the challenges that the new millennium presents and these challenges can take on only with a change in mentality and with advanced technologies . Therefore the LATIN AMERICAN SECTION OF THE AMERICAN NUCLEAR SOCIETY is focused to innovate , develop and communicate a quality culture , safety and environmental protection based on the benefits that the use of Nuclear Energy provides to different areas with peaceful purposes , all with Latin American presence and participation . Promote extensive exchange of experiences in coordination with public and private organizations inside the nuclear community through the following activities : . Spreading the technological advances . . Participate in technological research . . Attending problem resolutions and consulting nuclear engineering related issues . . Foster mutual cooperation and work closer with in the nuclear community . . Organize meetings and congresses . . Continue promotional effort to increase number of collaborators . . Promote use of nuclear energy . Antonio Carlos de O . Barroso 2000 - 2001 Roberto Omar Cirimello 2001 - 2002 LAS - ANS is the result of a pioneering effort of several professionals and executives of nuclear organizations of the region . The continuity over more than 25 years show that pursuing free and fair cooperation among peoples and countries gave an encouraging result of diffusion of nuclear activities . During the time when nuclear energy in our region reached low ebb periods LAS - ANS contributed to keep closely linked the nuclear communities of our countries and encouraged professionals and managers to pursue in their efforts to maintain the nuclear option open . Nowadays , due to the better prospect foreseen for nuclear energy , the role of LAS - ANS will be to strengthen the scope of its activity in the region and to enlarge the participation of other countries to become active partners in this endeavor . To be a part of LAS is a professional achievement . Fernando S . Henning 2002 - 2003 Roberto Hojman 2003 - 2004 Zieli Dutra Thomé Filho 2004 - 2005 Juan Luis François 2005 - 2006 We are living exciting days , more than ever the nuclear energy renaissance is close to a reality . There are two main drivers of this phenomenon : the climate change , due to the earth s global warming , mainly caused by the emission of greenhouse gases from fossil fuels combustion , and the high international prices of oil and gas . The first is very closely related to the environment and the second to the economics ; and both are very important dimensions of the sustainability of an energy source . The maturity of the nuclear industry , expressed in plant reliability ( higher capacity factors ) and operational safety , is also an important driver of the new confidence in the nuclear industry . Recently we have seen how Finland , a country greatly concerned about the environment , after a very detailed study , has selected the nuclear option to increase the electric power capacity . Criteria such as cost , reliability and environmental issues were taken into account in their final decision . In Latin America the situation is similar to the rest of the world . Nowadays the economics and the environment are global issues , which affect the strategic decisions of the countries . In particular the energy sector is a strategic one , which strongly depends on these issues ; we are also facing the high prices of the fossil fuels and the climate change disturbances . Some other local political decisions in Latin America , like the nationalization of gas in Bolivia , have added a new element into the decision making process of the energy policies in countries like Argentina and Brazil . This new element , related to the security of the energy source supply , is becoming one of the key issues in the definition of the energy portfolio in the countries . Nuclear energy has demonstrated , over the years that it is a reliable source of energy , independent of the political disturbances around the world . This is why I am convinced that once more , the role of the LAS - ANS is very important at this moment , such as it has been over thirty one years of existence , promoting the deployment of nuclear energy and gathering the nuclear community of Latin America . Nuclear energy must play a new and very important role in the short term in Latin America , vis a vis the energy needs and the economical and environmental concerns . We as Latin Americans , facing similar technical , social and political issues , can share experiences and knowledge through LAS - ANS in order to work for the renaissance of nuclear energy in our countries .

Mother Nature ( the Ultimate Chemist ) : South America holds some of the richest rain forests in the world where Nature , through the abundance of the essentials of life has produced a rich spectrum of biological molecules . The early inhabitants of these regions , over thousands of years , have , through experimentation , identified plants and animals that contain components that they have found to be beneficial for their health or so toxic that they can be used as a weapon . Do any of you know any examples of drugs or toxins that have evolved to commercial products that have had their origin from the experience of pre - modern history South Americans ? While the knowledge of these important biological compounds was passed on through generations from stories and the practice of medicine by learned members of these native communities , until recently , these stories and " home remedies " were not recognized by the science community as having much validity . Long before penicillin was discovered , the Native people knew that a bad wound would heal more quickly if moldy bread were layered over the wound . Although we have reached a high level of sophistication in synthesizing biological compounds , Nature , through the experience of millions of years , has developed synthesis pathways that are marvels in their complexity and ingenuity . Consequently , many scientists are not only isolating and identifying the active ingredients of a plant but also elucidating the pathways that Nature uses to produce that species . The countries of South America have been a rich natural laboratory for these activities . Poisonous South American tree frogs and mass spectrometry When a plant or animal is identified as having pan of its chemical make - up , a species that has important physiological properties , that species is first isolated and purified . The 3 - dimensional chemical structure is elucidated utilizing a variety of spectroscopic tools . The most information rich of these methods are NMR , IR , and x - ray diffraction of pieces of the molecule and the whole molecule . A structure is proposed that fits all of this information and a molecular mass determination is made that is a direct measure of the inventory of the atoms comprising the molecule . If the measured mass does not fit the proposed structure , them something is wrong with the proposed structure and it must be modified . The molecular mass determination is made by converting molecules of the species into gas phase molecular ions and the mass is measured by the interaction of these ions with magnetic or electric fields or a combination of these . The specific example that illustrates this scenario is given by the Panamanian tree frog whose skin contains a highly toxic molecule called tetrodotoxin . It ' s proposed structure based on spectroscopic evidence is given below : Figure 1 . Proposed Structure of Tetrodotoxin . This molecule interferes with the electrical circuitry of the heart and induces cardiac arrest . It is used in heart research to induced heart attacks in laboratory animals and to study the physiological action of this event . Attempts to obtain the molecular mass of this molecule by mass spectrometry in the early 1970 ' s failed because no gas phase molecular ions could be produced in the mass spectrometer . In fact , a large fraction of Nature ' s biomolecules could not be studied by mass spectrometry in that era because of this fundamental problem . The reason for this can be understood if the tetrodotoxin structure is examined in more detail . The highly polar groups on the structure result in a very strong dipole / dipole interaction between neighboring molecules in a sample of tetrodotoxin which means that it is difficult to pull them apart by thermal agitation . When the sample is heated to increase the intermolecular excitation , the thermal energy excites internal vibrations of the molecule and it dissociates . This process is depicted below . Figure 2 . Thermal excitation of a tetrodotoxin matrix leading to decomposition . A Chance Observation in a Nuclear Physics Study Leads to a Solution to the Problem In 1972 , our group at Texas A & M University was studying the emission of radioactive recoil ions from surfaces using time - of - flight mass spectrometry . In addition to the expected ions , molecular ions of impurities on the surface also appeared in the mass spectrum which were postulated to be due to the ionization of molecules on the surface of the sample by the nuclear radiation . To test this hypothesis , a 252 Cf - source was placed behind the sample and fission fragments from the spontaneous of this nuclide irradiated the sample . Molecular ions of surface molecules were indeed produced in high abundance and detected in the mass spectrum verifying the origin of the molecular ions in the nuclear physics experiment . Key individuals participating in this study in 1972 in our lab are participating in the Desorption ' 98 meeting this week . They are Karl Wien and Hartmut Jungclas from Germany . This phenomenon was so unexpected and interesting that it became the topic of our future studies and the nuclear physics interests gradually dwindled to obscurity . We began to coat the surface with a variety of different materials including those with biological significance and in all cases , we obtained molecular ions of whatever was put on the surface . My nuclear physics colleagues who were working on problems in the same nuclear physics field also became interested in this new adventure , and since they all had the same nuclear physics technology were able to do the same thing in their lab . Many of these individuals , ( nuclear physicists turned mass spectroscopists ) are also participating in this week ' s activities and have made major contributions to the field over the past 2 decades . In addition to Wien and Jungclas , they include Yvon Le Beyec , Bo Sundqvist , Ken Standing , Helmut Voit , and Brian Chait . Back to the Poisonous Frog and the Molecular Decomposition Problem In 1973 - 4 , when our studies on the use of fission fragments of 252 Cf to generate mass spectra was beginning to evolve , one of the students in my group began his graduate studies at Stanford University working for Harry Mosher , a renowned natural products chemist . Professor Mosher hid been studying the tetrodotoxin structure problem for several years and proposed the structure shown above . He was not able to verify this structure by MW determination because of the involatility / decomposition problem . He had tried for several years using every new mass spectrometric method that had evolved but with no success . At the urging of his new student , he sent us a sample to run and we got a good result . At that time , we didn ' t know it was a tough problem and we also didn ' t know about the problem mass spectrometry was having with involatile biomolecules . The spectrum we got by shooting fission fragments through a sample of this toxin is shown below . Figure 3 . First Mass Spectrum of tetrodotoxin obtained by PDMS Naming the Method Professor Mosher was very excited about this result . He suggested that we forget about this nuclear physics stuff and really develop the method into a technology for natural product studies . He also insisted that we come up with a name for it , something organic chemists could pronounce and remember and , after several attempts , came up with 252 Cf PDMS or PDMS ( Plasma Desorption Mass Spectrometry ) . So how do Fission Fragments solve the Problem ? A fission fragment is a high energy , highly - charged ion that is a highly destructive species . The surprise was that a component of its interaction with solids is gentle , resulting in the desorption and ionization of fragile molecules without decomposing them . Later studies showed that the combination of high energy density and short - excitation time was they key feature of the interaction that makes PDMS work and that even very large biomolecules can survive the hostile environment of the fission track and become intact gas phase molecular ions . PDMS Research , 1974 - 1984 During this era , our laboratory at Texas A & M was flooded with requests to " run samples " , primarily to determine the MW of molecules of biological importance . For the most part , these were pharmaceuticals being developed by drug companies and the MW determination was a requirement for acceptance as a drug for the public . Many of these compounds were known only by a code . We got some nice looking spectra but had no idea what it all meant . We must have been quite successful because the sample came flooding in . This was a confusing time for us because we were still more nuclear scientist than mass spectroscopist , and in fact , we knew very little about the field . We now know that many of the samples we studied have become important drugs currently in use . These include vancomycin , bleomycin , amphotericin , and thiostreptin . Although we were successfull with these molecules , the mass spectrometry community did not embrace our endeavors for several reasons : fear of radioactivity , use of time - of - flight and not a magnet or quadrupole , low mass resolution , and you had to wait for more than a minute to obtain the mass spectrum . It was a time when editors of journals were more sympathetic to our manuscripts than reviewers . Accelerator Studies , 1976 - present During the time when we were actively involved in " running samples " , my nuclear physics colleagues , who , like most physicists , generally distain chemistry , began to tackle the problem of mechanism of PDMS using their nuclear accelerators . It was from these experiments , that the properties of the incident ion were elucidated and the interaction of high energy ions with solids as a field in its own began to emerge . These activities were initiated and sustained by Voit at Erlangen , Sundqvist at Uppsala , Le Beyec at Orsay , Wien at Darmstadt , da Silveira at Rio and Tombrello at Caltech . Intense and enduring friendships with these groups for the past 25 years have been one of the richest components of my professional and private life . We have maintained this closeness through the series of Desorption ' xx meetings that have taken place in wonderful and interesting sites that include Brazil as a two - time favorite of this group . Over the years , the group has expanded as the field has grown and developed new roots and branches . It is this feature that I wish to address next . Secondary Ion Mass Spectrometry ( SIMS ) This method was well established before PDMS came along . Low energy ions bombard the surface of a sample producing gas phase ions of the matrix . The method was used extensively for characterizing the surfaces of inorganic species before 1974 and continues today . The mechanism involves collisions of the incident ion with surface atoms that are ejected . Molecular ions were also present in the mass spectrum which were an " unwanted background " . When PDMS was introduced , it was realized that a component of the SIMS process also was similar to PDMS , the rapid deposition of energy , and molecular ions of involatile molecules could also be desorbed by these low energy ions . From 1976 to the present , SIMS has been a member of the Desorption ' xx family , led by Benninghoven at Munster and Standing in Winnipeg . A friendly rivalry emerged during this era where a series of papers were presented on SIMS catching up to PDMS in terms of number of ions desorbed and the mass range . In terms of acceptance by the mass spec . community , SIMS had the same problem as PDMS because it did not use sophisticated magnets and have high mass resolution . This acceptance issue comes up in several places here because it was a real dilemma . Thousands of mass spec . people were essentially ignoring the work of the PDMS / SIMS people despite the successes . The Beginning of Being Accepted The first mass spectrometry meeting where PDMS results were presented was in 1976 . It was the last paper of a week - long meeting and 4 people were in the audience ( they were waiting for their plane ) . But as it turned out , they were very important people and each became part of the PDMS family . They were highly respected in the mass spec . community politics and 3 of the 4 became President of the American Society for Mass Spectrometry and the fourth is now President of a large mass spectrometry company in the US . It was through these individuals and their foresight and unselfish devotion to the good of the field that PDMS began to be a part of this community . To Frank Field , Hank Fales , Jim McCloskey , and Ian Jardine , the Desorption ' xx group can be grateful to these bridge builders . For Frank Field and Victor Tal ' Rose , their strong intellectual leadership became the base for acceptance by the mass spectrometry community . The Competition Heats Up , Laser Desorption is Introduced It was generally accepted by the mass spectrometry community that there must be a better way than PDMS to obtain mass spectra of biomolecules but using the same general idea . In the late 1970 ' s , Meuzzelar in Holland began to obtain impressive mass spectra using laser excitation . When I heard one of his first talks on his work , I had the feeling that the days of the monopoly that PDMS had on the field were numbered . Laser desorption had so much going for it in terms of control of the excitation . The pulsed laser was a natural for the TOF technique . However , the promise did not convert to reality in the next few years . One of the Desorption ' xx participants , Franz Hillenkamp , took up the challenge of laser desorption at that time and for several meeting Hillenkamp kept us informed on the progress of the development of the method . The mass spectrometry community and commercial mass spectrometer makers patiently waited for something more attractive . Fast Atom Bombardment ( FAB ) makes its debut In the early 1980 ' s , we were working with Kenneth Reinhart , a natural product chemist at Illinois , on a series of potentially important antibiotics derived from marine organisms . These were tough molecules to analyze . In the middle of the studies , Ken told us about a method he heard was just developed in England that was an important breakthrough for the analysis of involatile biomolecules . He was going to England immediately with his samples and would report back . When he returned , he told the story of a clandestine operation literally clocked in secrecy where he handed his samples to an operator who then went behind a curtain , prepared the samples and inserted them into a mass spectrometer . Out came high quality spectra and the big news was that a " proper " mass spectrometer was used i . e . a magnetic sector instrument . The professor in charge was Michael Barber and the method is known as fast atom bombardment . The incident species is a high energy neutral atom and the matrix is a liquid matrix . A high yield of ions , a steady current of these ions is produced , and it is compatible with the technology currently in use by the mass spectrometry community at that time . High resolution , instant gratification in the time required to get the data , important criteria for acceptance , was a part of the FAB technique . Within the next year , I heard Mickey Barber present his method and results at a meeting in London , the last talk of the meeting , and I knew then that PDMS was on its way to become part of the past history of mass spectrometry . Most of the important pharmaceutical problems could now be solved by FAB and the demand for PDMS measurements was reduced to almost nothing . The mass spectrometry community embraced FAB and there was a public impression that now there was a method far analyzing involatile biomolecules . This perception was not challenged by the Desorption ' xx community ( I ' m not sure why ; intellectual maturity ? , unselfish devotion to the science and not the publicity ? , ..... ? ) and the FAB researchers chose not to be a part of the Desorption ' xx community even though the mechanisms of the process were closely related . In later years , Mickey and I had several good interactions and conversations . In the last ( I didn ' t know it would be the last ) , I got up the courage to ask him a question I had pondered since I first heard about FAB and the basis for the question was the lack of the development of a link between FAB and the other desorption / ionization methods . My question : " Mickey , did PDMS have any influence on the development of FAB ? Mickey : " You damn right it did ! We were so angry that you were able to run all those samples on a TOF instrument that we put one of your spectra on the wall of our lab as a daily reminder that we must find a way to run these samples on a proper mass spectrometer . " I cherish that moment . The Post - FAB era and the birth of MALDI What kept PDMS going after FAB was introduced was the ability to study larger biomolecules . Largely through the work of the Uppsala group , the mass range limit was pushed up to close to 40 , 000 for a protein . But it was hard work . At the same time , biotechnology and medicine was becoming more sophisticated and the desire to obtain accurate and precise molecular weights of biopolyimers was becoming more acute . It was obvious from our studies that there was a limit to the size of a protein that could be desorbed by a fission fragment . This was a bit of disappointment because our own interests were heading in a direction in medical research where we wanted to use PDMS to characterize proteins involved in human health and disease . It was clear that PDMS was not going to be used in these studies . In the late 1980 ' s , at an International Science meeting in Bordeaux , Franz Hillenkamp gave a talk , imbedded deep in the program on the work he and Michael Karas were doing with laser desorption ; a breakthrough and a new acronym : MALDI . You will hear more about this method from Franz in the next day or two . This time , my response to his talk was absolute excitement ! I could see my desire to have a method available to accomplish my long term goal : to make a contribution to medicine , had a chance . I close this long set of lecture notes with an excerpt of dream that has become reality . Dateline : January 30 , 1998 , Scott & White Hospital , Temple , Texas . A 51 year old white female admitted to emergency room with chest pain rated as 9 out of 10 with radiation to the upper jaw and associated with shortness of breath , nausea , and diaphoresis . A new technique for monitoring the severity of the heart damage is employed . MALDI spectra , recorded over a period of 3 days on the proteins present in the patients HDL , shows an increase in the concentration of the acute phase response protein , serum amyloid SAA , an indication of extensive damage to the inferior myocardial wall . Attending physician , Catherine J . McNeal , MD , Ph . D . MALDI spectra of a heart patient recorded over a period of 3 days . ( A special thanks to Dave Russell and his group in the Texas A & M , Department of Chemistry , Laboratory for Biological Mass Spectrometry for obtaining these data for us . It was carried out on a very long Perspective Biosystems Instrument ) . © 2006 Sociedade Brasileira de Física Caixa Postal 66328 05315 - 970 São Paulo SP - Brazil Tel . : + 55 11 3091 - 6922 Fax : ( 55 11 ) 3816 - 2063

CEB - Centro de Engenharia Biomédica This issue of MultiCiência brings about matters on Health Technology . Plenty of prospective and hope seem to lie ahead over new technologies . A significant amount of work has been carried out , and significant advances are noticeable in every single area . Nevertheless , one needs to consider carefully the meaning of owning and using health care equipment based on more advanced technology . What are the benefits and problems that may ensue ? It is not hard to figure out the amazing benefits brought about by miniaturization of diagnostic devices . This issue presents new ideas on equipment for clinical analysis ( diagnostic devices ) . A clear trend towards lab - on - chip using the microfabrication and miniaturization technology will most likely flood the market in the next few years . Brazilian research can effectively bring contributions to this field , as shown by Luiz Otavio Saraiva Ferreira in his article , also warning us about the new challenges . As the author points out , “ one may conclude that a cultural change involving the entire community dealing with diagnostic devices is under way affecting equipment operators , maintenance crews , personnel in charge of equipment specification , and health system managers . Innovative technologies will require new approaches regarding their use and incorporation . Maybe no other area in medicine has benefited more from technology from a practical point of view than medical imaging . From a deeper knowledge on anatomical structures gained from the application of non - invasive procedures , to the realm of the structure - function association , technological advances have brought about innovations and improvements regarding the medical practice , both for diagnosis and for surgical treatment support . It is unquestionable that nuclear magnetic resonance and other techniques developed from nuclear medicine have contributed significantly , as analyzed and richly depicted by Eduardo Tinóis da Silva in his article . Positron emission tomography ( PET ) and functional magnetic resonance imaging ( fMRI ) exemplify how image technology has made the unknown accessible , rendering visible what formerly seemed transparent . Nowadays , it is virtually impossible to ignore the myriad of new products constantly becoming available . Digital electronics changes rapidly . Millions of people all over the world have incorporated to their daily lives cell phones , produced with new shapes , colors , and functions of increasing complexity . Yet , how many of them do not hesitate to exchange more essential products for new cell phones , in order to play those little keyboards , talk to friends , and get so many messages at any time or place ? Computers may be seen as another trivial example . Nevertheless , how many computer owners can actually use a computer for more than “ browsing the Internet ? ” The big issue is that health equipment cannot be considered an exception . However , from the sphygmomanometer routinely used for blood pressure measurement , to the complex equipment for nuclear magnetic resonance , the problems are the same : How to procure , maintain and use medical equipment correctly and safely ? When update or consider them obsolete ? Using equipment poorly installed and maintained , or kept in improper environment and / or operated by untrained personnel may be catastrophic . As well shown by Gerson Florence and Saide Jorge Calil in their article , much of the risk ( i . e . , potential sources of damage ) involving medical equipment stems from the environment , rather than from the equipment itself . There are ways to minimize the risk , but actions ought to be taken at several levels . The risk factor is a systemic issue . It is not legitimate to say " making errors is human " ! In the hospital environment errors do not necessarily occur due to negligence . There are a number of error - generating factors , and most of them can be targeted . Advanced centers where health systems are carefully controlled , more than five people die due to errors every hour in USA hospitals ( 1 ) , and in UK , errors have harmed as much as ten per cent of inpatients , which corresponds to about 850 , 000 cases per year ( 2 ) . Medical equipment ownership and use do require special care and financial resources for maintenance . In 1995 , the Brazilian Ministry of Health ( MH ) revealed that medical equipment in bulk quantities worthing billions of reals were inoperative due to poor maintenance . It can be figured that 10 to 20 per cent of the total available medical equipment in Brazil would fail if submitted to safety inspection tests . The awareness of such a situation has triggered reaction from the MH , which recently has initiated a program for personnel training in medical equipment maintenance management practices ( 3 ) . Data has being issued by the MH regarding medical equipment in health facilities ( HF ) in Brazil . From the data available in 10 / 19 / 2004 for São Paulo State ( http : // cnes . datasus . gov . br ) , we can estimate that all equipment would be worthing from a minimum of R $ 8 , 150 , 631 , 150 . 00 up to a maximum five times greater ( source : ECRI - Emergency Care Research Institute , USA ) . Therefore , if the equipment is to receive adequate maintenance , at least 6 % of their nominal value should be spent yearly , or R $ 489 , 037 , 869 . 00 based upon the minimum above . We believe that less than 10 % of the public hospital network have being able to apply effectively 2 % to 6 % of their equipment investment in maintenance and technological updating . Deterioration is therefore inevitable , and the amount of inoperative equipment thereby will also increase , all together increasing the risk for the patient . The foregoing deals only with maintenance , which certainly is not the sole factor to be considered . If other aspects are also taken into account , one may conclude that the scenario is quite complex and may have an overwhelming impact over the entire population . Health technology evolution implies stepping up robustness . The more robust a system is , the easier its operation becomes . Small mistakes do not disturb the outcome , for the equipment is able to resist to certain disturbances and flaws , up to a certain point . As a result , however , vulnerability increases . The good news is machines can issue diagnosis . Vulnerability lies in the operation of such machines by someone trained exclusively with keyboard operations , as once learned when dealing with mobile telephones . Although terrific images may be produced by computerized tomography , the patient is the one who takes the burden of being heavily exposed to X - rays should the utilization criteria be relaxed , or the former ( often safer ) technology be abandoned just because a new one has shown up . It has become very easy and appealing to undergo ultrasonography during pregnancy . Even against the recommendation of the American College of Osteopathic Obstetricians and Gynecologists , about 70 % of pregnant women are submitted to an echogram at least once . With an increase in power by 5 million times , little difference is observed in the image produced by the most modern ultrasound equipment , but this is not so regarding the risk of ultrasound undesired effects . As it has being emphasized , no law states that only the lowest power should be used . One should consider , as well , the extreme variability in competence of all those involved with the operation of such equipment ( 4 ) . Our statistics in the management of equipment maintenance for UNICAMP s health area show that about 1 . 5 % of all equipment sent for repair at the Center for Biomedical Engineering are not deranged , andthe malfunction cannot be attributed to operation error . What would possibly be the reason for the malfunctioning ? After detailed study and advances in this specific area , we are now able to identify the main reason : electromagnetic interference ( EMI ) . This is not necessarily related to the inadequacy of the electrical circuitry . Undisputable and solid data on the effects of cell phone use in the hospital environment are presented by Suzi Cristina Bruno Cabral and Sérgio Santos Mühlen in their article , where the authors remind us the wider question of crossed interference among pieces of equipment . “ One of the most effective ways to avoid EMI is to build equipment providing for electromagnetic compatibility under pre - established conditions . Wireless communication inside a hospital may turn out to be an electromagnetic ocean with unpredictable “ waves . This is a concrete and a definitely unresolved issue ! Should we make believe it is inexistent , or are we going to engage ourselves in an effort to make it visible to the point that it may be considered as a managerial risk ? Solutions to enhance safety in the use of health technology need to be systemic and multidisciplinary . The article by Binseng Wang presents a realistic proposal of framework towards planning , incorporation and management of medical technology . One important point is that the approach should include a health policy defined in a broader scope , and the various phases of the technological incorporation would require adequate strategic planning by the very health promoting institutions . As policy and rules from government must permeate through the whole process , the feedback from health facilities might and should serve to regulate the process within acceptable levels and according to the conditions of each country . We are not aiming at expressing pessimism or skepticism towards what is our greatest motivation in Biomedical Engineering , namely , to pursue solutions to face new challenges and society wishes . Our goal is to emphasize the importance of a careful and thorough analysis of all aspects of a given problem . Assessment and incorporation of medical technology based on political or bureaucratic reasons do not demonstrate an effort to improve the service . Such attitudes add up problems , rather than solving them , leaving no room for a healthy competition among available technologies . Should the country be unable to use and maintain such technologies , it will as well be unable to offer future benefits to all who are in the greatest need of health care : the patients ( that is , all of us ) . See also into the Interdisciplinary Network : “ Análise quantitativa do termo interdisciplinaridade no período de 1970 a 2004 ” ( Quantitative analysis of the term ‘ interdisciplinarity ’ between 1970 and 2004 ) de Lorena Dall ´ Ara Guimarães e Miriam Plaza Pinto ; “ Análisis em inteligencia tecnológica ¿ Qué es para que sirve ? ( Analysis in Technological Intelligence : What Is It and What It Is Used For ? ) de Q . Luzselene Ricón Arguelles e Victor Gerardo Ortiz Gallardo , e “ Quintais domésticos e sua relação com estado nutricional de crianças rurais , migrantes e urbanas ” ( Household Backyards and How They Relate with the Nutritional Condition of Rural , Migrant and Urban Children ) , de Ana Paula Branco do Nascimento , Marcelo Correa Alves e Silvia Maria Guerra Molina . Bibliography : 1 - Bogner , M S . Stretching the search for the ‘ Why ’ of error : The systems approach . J . Clinical Engineering , 27 : 110 - 115 , 2002 . 2 - Rigg N . Department of Health . An organization with a memory : Report of an expert group on learning from adverse events in the National Health Service . Norwich , U . K . : The stationery Office , 2000 . 3 - Brasil . Ministério da Saúde . Secretaria de Gestão de Investimentos em Saúde . Projeto Reforsus . ( The Medical Hospital Equipment and the Maintenance Management : Web based training ) . Editora do MS , 720p , 2002 . 4 - ACOG practice patterns . Routine ultrasound in low risk pregnancy . evidence - based guidelines for clinical issues . N . 5 , August 1997 . American College of Obstetricians and Gynecologists . Int . J . Gynaecol Obstet . , 59 ( 3 ) : 273 - 278 , 1997 . José Wilson Magalhães Bassani Master and Doctor in Electrical Engineering by UNICAMP ( with focus on Biomedical Engineering ) . Chaired professor – Biomedical Engineering – Electrical and Computing Engineering College , Department of Biomedical Engineering – UNICAMP Director of the Center for Biomedical Engineering between 9 / 18 / 1998 and 9 / 8 / 2005 .

The constitution , evaluation and ceramic properties of ball clays * ( Constituição avaliação e propriedades cerâmicas de " ball clays " ) Ian Richard Wilson Overseas Geological Services ECC International Europe John Keavy House , ST . Austell Cornwall , PL25 4DJ , England Abstract Ball clay is a fine - grained highly plastic , mainly kaolinitic , sedimentary clay , the higher grades of which fire to a white or near white colour . The paper will review the origin of the term " Ball Clay " and the location and origins of several deposits with particular emphasis on the mineralogical , physical and rheological properties which make the clays so important in ceramics bodies . Particular attention will be paid to the well known bay clay deposits of Devon and Dorset in southwest England , which are mined by ECC International Europe and Watts Blake Bearne & Company PLC , and brief descriptions from elsewhere in the world of ball clays from the United States , Germany , Czech Republic , Thailand , Indonesia , Argentina and China . The evaluation of deposits will be covered along with a description of the main types of ball clay for ceramics with details of the mining , processing and blending techniques which are necessary to ensure long term consistency of products . A brief description in given of the ceramic properties of some Brazilian ball clays . The location of some ball clay deposits is shown in Fig . 1 . Resumo “ Ball clay ” é uma argila sedimentar , essencialmente caulinítica , muito plástica e com uma granolometria muito fina ; os tipos de melhor qualidade queimam com cor branca ou próxima à branca . Este artigo apresenta uma revisão do termo “ Ball Clay ” e a localização e origens de vários depósitos , com ênfase particular nas propriedades reológicas , mineralógicas e físicas que fazem essas argilas tão importantes para certos tipos de massas cerâmicas . Uma atenção especial é dedicada aos bens conhecidos depósitos de “ ball clays ” de Devon e Dorset no sudoeste da Inglaterra , os quais são minerados pela ECC International Europe e pela Watts Blake Bearne & Company PLC . Descrições sumárias são apresentadas de outros depósitos de “ ball clays ” nos Estados Unidos , Alemanha , República Tcheca , Tailândia , Indonésia , Argentina e China . A avaliação dos depósitos será feita conjuntamente com uma descrição dos principais tipos de “ ball clays ” para Cerâmica , com detalhes sobre a mineração , processamento e técnicas de mistura que são necessários para garantir uma constância de propriedades dos produtos ao longo do tempo . É feita uma breve descrição das propriedades cerâmicas de algumas “ ball clays ” brasileiras . A localização de alguns dos depósitos de “ ball clays ” é mostrada na Fig . 1 . Figure 1 : The location of some Ball Clay Deposits in the World . WHAT IS BALL CLAY ? Ball clay is a fine - grained highly plastic , mainly kaolinitic , sedimentary clay , the higher grades of which fire to a white or near white colour in an oxidising atmosphere . They consist of varying proportions of kaolinite , mica and quartz , with small amounts of organic matter and other minerals , and are commercially values because they increase the workability and strength of various ceramic bodies and have white or near white firing characteristics . The name " Ball clay " is believed to be derived from the original method of extraction , in which the clay was cut on the floors of open pits with approximately 25 cm cubes or " balls " weighing about 15 - 17 kgs . This original production method was carried out up to 50 years ago in England and is still the main method of mining in the island of Kalimantan ( Indonesia ) as illustrated in Fig . 2 . Alternatively the name was derived from the digging implement formerly used called a tubal . Even to this day a power driven spade is used underground in Dorset to mine the very highest quality ball clay . Figure 2 : Ball Clay being mined with a tubal in Kalimantan Island , Indonesia . Figure 2A : Ball Clay from the Kalimantan mine being stacked up ready for transportation . A detailed description of the origins , properties and uses of English ball clays in ceramics was presented at the Brazilian Ceramic Congress in Recife in 1982 [ 1 ] . The term " Ball clay " has , therefore , no mineralogical significance , nor does it describe the age , properties or utilisation of the clay . LOCATION OF BALL CLAY DEPOSITS The location of some of the word ' s ball clay deposits is shown in Fig . 1 . It is beyond the scope of this paper to include all known deposits of ball clay but an attempt will be made to describe some of the important areas for ball clay production . Particular attention will be paid to the English ball clays to demonstrate the procedures necessary from evaluation through to utilisation . BALL CLAYS FROM SOUTHWEST ENGLAND General England is home to world - class deposits of ball clay and the consistency and high quality has allowed the United Kingdom to become a leading world exporter of ball clays . The importance of the industry was recognised in 1949 when the Ball Clay Standing Conference was constituted by the Minister of Town and County Planning . Because of the national importance and scarcity of ball clay , deposits from needless sterilisation by other forms of development . Three areas - the Bovey and Petrockstow Basins in north and south Devon respectively and the Wareham Basin in Dorset - were identified as being of strategic importance for production . United Kingdom sales of ball clay , by area , are shown in Table I for the years 1990 - 1993 : Table 1 : UK Sales of ball clay for 1990 - 1993 ( in tonnes ) ( source : British Ball Clay Producers ' Federation ) . Since 1993 the production of ball clay from the United Kingdom has increased as the data in Table II demonstrates : Table II : United Kingdom production of Ball Clay , 1991 - 95 ( source : British Geological Survey , 1995 ) . LOCATION OF ENGLISH BALL CLAYS The location of the Devon and Dorset ball clay deposits in shown in Fig . 3 . The commercial ball clay deposits are confined to three Tertiary basins in south - west England : the Bovey Basin of south Devon , the Petrockstow Basin in north Devon and the area around Wareham in south - east Dorset . Similar Tertiary clays occur in Northern Ireland but they are silty and have too high an iron content to be of commercial value as high quality ball clays . Figure 3 : Location of ball clay deposits in southwest England . Derivation and Deposition of the Ball Clays The climate in the lower Tertiary period was sub - tropical and the very warm and wet conditions resulted in a deep weathering mantle on the Carboniferous and Devonian slates and the granite uplands . The feldspar minerals within the granite were changed to a moderately ordered kaolinite . The unweathered slates have a clay mineralogy dominated by illite and chlorite . The weathering process converted all the chlorite and some illite to a disordered kaolinite . Bristow [ 2 ] has demonstrated that the weathered Carboniferous slates preserved beneath the ball clays in North Devon show a complete gradation from fresh slate to a ball clay mineralogy . Further movement and erosion along the Sticklepath - Lustleigh fault system in the mid - Tertiary period resulted in a large northwest - southeast trending valley . Sediments derived from the erosion of the thick weathering mantle were channelled into this valley by rivers . The coarser sands and gravels formed alluvial sheets or fans on the valley floor and the clay , silt and vegetation debris accumulated in the swamp - like lakes . A series of tectonic basins developed along the fault line giving rise to the south Devon Bovey Basin and the north Devon Petrockstow Basin . These tectonic basin were areas of crustal weakness which enabled the slow accumulation of ball clays , unconsolidated sands and lignites . Subsidence of the valley floor in the basin areas was probably linked to periods of earthquake activity and movement on the fault system . A Bovey Basin gravity survey recorded a maximum depth in excess of 1300 metres [ 3 ] : at Petrockstow a British Geological Survey borehole confirmed a maximum depth of approximately 750 metres [ 4 ] . These sediments have been dated by examining pollen samples and they range from upper Eocene to Middle Oligocene , 35 to 28 million years old [ 5 ] . The South Devon Bovey Basin The Bovey Basin extends for approximately 11 km northwest - southeast and 6 km in an east - west direction ( Fig . 4 ) . A complex sedimentary history with sediments derived from different sources has been identified [ 6 , 7 ] . The ball clay mineralogy comprises varying proportions of disordered or ordered kaolinite , illite and quartz . The ball clays containing a high content of ordered kaolinite were largely derived from weathered granite - these types of ball clay are often found in the upper levels of the sequence and may represent the products of unroofing and erosion of the Dartmoor granite . Those sediments containing disordered kaolinite and illite are probably derived from weathered slates . Figure 4 : Stratigraphy of Bovey Basin , south Devon . The geological sequence ( Bovey Formation ) has been sub - divided based on the clay , sand and lignite content and the clay mineralogy ( Fig . 3 ) . The sequence is a follows ( Table III ) . Table III : The Bovey Formation . A geological section across the eastern part of the Bovey Basin is shown in Fig . 5 . A typical view of a sequence from a ball clay pit in the Bovey Basin is shown in Fig . 6 exhibiting the wide range of working seams interbedded with lignites . Figure 6 : A typical south Devon Ball Clay pit face . The North Devon Petrockstow Basin The Petrockstow Basin is narrower and more elongate that the Bovey Basin being 6 km northwest - southeast by 1 . 5 km east - west . The basin is divided into a deep , axial trough and shallower , marginal shelves in the northeast and southern areas , which have been developed for clay extraction . The clay area is bounded by two north - westerly trending faults of the Sticklepath - Lustleigh fault zone ( Fig . 7 ) . Faulting divides the basin into a deep central trough with marginal shelf areas . In the centre of the trough , a hole drilled on the site of a small negative gravity anomaly proved a total thickness of 661 m of Tertiary sediments , overlying Upper Carboniferous strata . The sediments filling the axial trough consist largely of silts , sands and gravels , with only subordinate brown clays and lignites . On the marginal shelf areas coarse sediments are absent and ball clays with variable silt content and some lignite are dominat , but towards the central trough the quality of the clay rapidly deteriorates . The Petrockstow Basin is thought to be the relic of a river system which flowed northwards along the line of the Sticklepath fault zone , the coarse sediments being deposited along the central trough , with deposition of the ball clays taking place under the gentler conditions of a flood - plain environment . Figure 7 : Geological map of the Petrockstow Basin , north Devon . Wareham Basin The Dorset ball clays in the Wareham Basin ( Fig . 8 ) are formed from the erosion of Juarassic and Creataceous rocks under sub - tropical conditions . The clays were transported down meandering rivers to a large flood - plain . Here the clay - laden suspension mixed with acid swamp water causing sedimentation of the clay particles ( by flocculation ? ) . Dorset ball clays occur within the various clay sequences of the Poole Formation within the Brackelsham Group ( Fig . 9 ) formerly known as the Bagshot beds and are of lower - mid Eocene in age . The sediments comprise interbedded sands , silts and clays deposited in a large flood - plain . Figure 9 : Stratigraphy of the Wareham Basin Tertiary Sediments , Dorset . Dorset clays are fine grained , very plastic and exceptionally low in carbon content . Geological Evaluation of Deposits Both ECC International Europe - ECC Ball Clays ( will be referred to as ECC ) and WBB Devon Clay Ltd ( the operations in Devon of Watts Blake Bearne & Co PLC - will be referred to as WBB ) have carried out detailed exploration and , on a regular basis , carry out drilling for deposit evaluation and mine control purposes . Despite the vast array of sophisticated geological , geochemical and geophysical exploration tools available today few have any real application to assist in the exploration for ball clay : Exploration Methods a . Geochemistry has little application as most ball clays are relatively inert and do not leachable or mobile trace elements which show up in stream or soil samples . b . Geophysics can be defined into two types , first remote sensing from satellites or aircraft and second group systems . Remote sensing may well prove useful and essential in parts of the globe where the terrain is difficult or there are no maps . Also spectral analysing certain wavelengths of light , some are capable of identifying clay minerals where exposed at surface or where they affect vegetation . They also allow structural analysis to be carried out which may prove invaluable in defining fault zones and basins . Most importantly maps can be made from satellite imagery and air photographs . Ground based geophysics may help identify whether a clay sequence or seam is present , or indicate its subsurface features / geometry ( Seismic profiling . Gravity surveys can help define basins like Bovey and Petrockstow ) . Whilst borehole geophysics and gamma logs have their uses it does not tell the user the clay quality or quantity . c . Borehole Geophysics can assist in the exploration for stratified clay deposits and has advanced considerably with many slim hole systems now available . The main method used is the natural gamma logger . A probe is lowered down the hole which contains a scintillation counter which is extremely sensitive and picks up radioactive particles which is extremely sensitive and picks up radioactive particles which is extremely sensitive and picks up radioactive particles which occur naturally . In most sediments the isotope of Potash ( K40 ) is present - the greater the clay content the greater the K40 . Sands and lignites obviously give very low levels . Therefore a continuous recording of each borehole can be made ( Fig . 10 ) , which is more important for its signature than its actual radioactive count . It is in essence a geological finger - print with comparison of logs through the same sequence exhibiting similar patterns which can be utilised for correlation purposes in defining the stratigraphy and , sometimes , the structure . Figure 10 : Gamma Ray Borehole log from a Dorset Borehole . d . Drilling is the only satisfactory way to explore and develop ball clay deposits by obtaining representative samples regularly spaced in the seam and across the deposit . This can be achieved by core drilling ( typical drill rig shown in Fig . 11 ) , percussive shell and auger , flight auger , or by pitting and face samples . These are the only positive methods . Because ceramic test require large amounts of sample , and often clays are difficult to core drill , large diameter samples are desirable . In the U . K . " N " size ( 55 mm ) or " H " size ( 75 mm ) core are taken and have proved effective for evaluating clay deposits . ECC utilise the " Datamine " system for evaluating reserves and detailed plots are prepared ( Fig . 12 ) from borehole information ( a typical borehole print - out is shown in Fig . 13 ) . Figure 11 : A Geological Exploration rig drilling for Ball Clay in Devon . Figure 12 : Computerised logging of pit geometry utilising borehole information . Planning and Environmental Matters The need for planning permission to work a mineral is a major hurdle to overcome in developing a mineral resource . The planning process is complex , frequently taking several years to prepare an application which it is hoped will prove successful . The planning process required description of the deposit , the need for the mineral , how it will be worked , the methods of working and removal of mineral , and importantly how the site will be restored at the end of the day . Recently , certain mineral developments have been required to produce an environmental assessment of their proposal which basically requires an existing audit of the environment at the site and surrounding area - these include assessments of geology , ecology , archaeology and landscape value of a site . Also details must be given of environmental protection and restoration . Having prepared all the relevant information a planning application is lodged with the mineral planning authority . At this stage the application is publicised , the public invited to comment and statutory or nominated consultees are given the application to comment on ( bodies such as Nature Conservancy , English Heritage and Ministry of Agriculture ) . The planning authority collate and examine the responses and recommend to the elected representatives whether the scheme should be approved or not . If it is approved then a permission is issued with conditions which have to be met by the mineral developer . The whole process can take months as the information is exchanged , sought and clarified . Summary of Explorations Stages A brief summary of exploration activity would be as follows ; 1 . Geological Investigation based on market demand for internal and export markets . 2 . Target areas selected , exploration permit acquired . 3 . Drilling programme drawn up . 4 . Limited objective drilling programme ; 4 . 1 To determine geology . 4 . 2 Occurrence of ball clay seams ( one hole per 20 hectares ) . 5 . Intensive drilling programme - every 50 m our down to 20 m spacing if necessary . 5 . 1 Determine detail for mine planning . 5 . 2 Sufficient sample for laboratory assessment . 5 . 3 Establish ceramic grade and continuity of quality ( one hole per hectare - minimum ) . 6 . Report , analyses , reserves . Bulk sampling and detailed laboratory investigation with trial samples to customers . Body work evaluation . 7 . Planning permission : Public enquiry . 8 . Working of pit . 9 . Above all - a good return on investment . Mineralogical Composition of Ball Clays Ball clays , unlike china clays , generally cannot be economically refined after they have been excavated , and therefore the customer has to accept them as they are , with all the mineralogical components still present in the sediments . All the components are in a finely divided form , and occur as an intimate mixture which defies attempts at separation without the use of expensive and lengthy processes . The principal components of ball clays are disordered kaolinite , micaceous matter and quartz . The kaolinite components of ball clays of Devon is of the ` b - axis disordered ' type . A TEM of a typical ball clay ( Fig . 14A ) showing the disordered kaolinite is compared with a crystalline kaolinite derived from a Cornish granite ( Fig . 14B ) . Various workers have suggested methods by which the degree of crystallinity of the kaolinite may be quantified . A degree of crystallinity of zero represents completely disordered kaolinite , whilst a degree of crystallinity of approximately 2 represents nearly perfectly formed kaolinite . For the south Devon clays , a range of values from approximately 0 . 1 to 0 . 9 has been obtained , whilst the range of values from the north Devon deposit is much narrower , ranging from less than 0 . 1 to 0 . 25 - 0 . 30 . In addition of the structural disorder , isomorphous substitution is known to occur within the kaolinite lattice . The most common substitution which occurs is that of iron and magnesium replacing aluminium in the octahedral layer of the kaolinite which results in a charge inbalance which will affect certain other properties of the clay , for example its cation exchange capacity . Ball clays from both the Devon deposits contain substantial amounts of micaceous materials . A great many ideas have been put forward as to the exact nature of the micaceous matter , it having been variously described as illite , micromica , hydromica and hydro - muscovite . Its silica - alumina ratio and alkali content point to its being a hydro - muscovite . Its silica - alumina ratio and alkali content point to its being a hydro - muscovite , and this is borne out X - ray diffraction patterns being similar to muscovite . Figure 14A : TEM of a typical Devon Ball clay showing dis - ordered kaolin type . Figure 14B : TEM of a typical Cornish China clay showing crystallinity of kaolin . The quartz found in the ball clays is not the same coarse angular material found in china clay matrix but a much finer water - worn material , as to be expected from the fact that it has been subjected to several different sequences of transportation . A significant characteristic of the fine quartz - sand in ball clays is the absence of tourmaline present in association with china clay quartz - sand . Ball clays , being whole sediments , in a number of cases contain traces of other mineral substances classed as minor impurities or accessory minerals . The main ones are lignite , anatase , goethite , siderite , hematite , limonite and pyrite . The most significant of these , particularly in south Devon is lignite , which is a soft brownish coal - like substance formed by the compression of decayed peat beds sandwiched in between successive seams of clay . The type of sequences shown in Fig . 6 were common during Tertiary times and are known as V - P - L phases ( vegetation - peat - lignite ) . During the Tertiary era there were a considerable number of these V - P - L phases , giving rise in places to numerous seams of lignite . In some parts of the Westerwald of West Germany as many as seven V - P - L phases can be identified as one cuts down through the clay bearing strata , The United Kingdom deposits are not so lignitic as those in the Westerwald , but are not completely free of its . In the Bovey Basin beds of lignite separate the Eocene sands from dark grey clays , above which a further seam of lignite underlies early Oligocene sandy clays , and all told there are four separate seams of lignite or lignitic material . Very little lignite occurs in the clay beds of the Petrockstow basin , but in the West Marland Beds there is one seam of black lignitic clay . The Wareham Beds ( Dorset ) do not contain much lignite , but there is evidence of one V - P - L phase during the period of deposition , which manifests itself as seam of lignite about one metre thick . The composition of the lignite is : resins and tannins ; fats and waxes ; lignin and humic acids ; cellulose and some residual mineral matter . An analysis of a typical lignite is given as Carbon , 46 . 8 % ; Hydrogen , 3 . 5 % ; Nitrogen , 0 . 5 % ; Sulphur , 3 . 2 % ; Oxygen , 18 . 3 % and ash , 27 . 8 % . The carbonaceous material has a profound effect upon the green strength of clays . The modulus of rupture of a ball clay increases with increasing carbonaceous content matter . There are dangers though if the carbonaceous matter is too high and these will be mentioned later in the section on Fired Properties . Carbonaceous matter can also contribute to the problem of specking of ware , largely due to the relatively high amounts of ferruginous matter associated with the rather coarsely particulate ( approximately 50 microns ) lignite . Montmorillonite present in ball clays increases the green strength , the plasticity and the dry contraction . In the firing of clays , the presence of montmorillonite increases the firing contraction and , because it contains iron , also has deleterious effect on the fired colour of the product . Probably the major effect of montmorillonite , however , is in ceramic casting slips where it materially affects the deflocculation behaviour of the clay resulting in a high deflocculant demand , low slip stability and high slip viscosity . In summary the mineralogical composition of ball clays is tremendously variable from one area to another and within the same deposit . Whilst summarising such varied compositions is often meaningless the mineralogical composition of English ball clays is shown in Table IV . Table IV : Mineralogical Compositions of Ball Clays , Including Siliceous Ball Clays [ 8 ] . Detailed work carried out on the mineralogy of the - 1 / 2 micron fraction shows some interesting relationships . The north Devon clays contain montmorillonite and the Dorset clays a significant amount of mixed layer mica - montmorillonite , the south Devon clays tend to be composed essentially of an illitic mica . Relating this to strength clays , it would seem that the montmorillonite of north Devon is more efficient weight for weight in bringing about a high strength clay than the mixed layer material of Dorset , and both the north Devon and Dorset materials are more effective than the illite mica of south Devon . It would appear that the cause of high strength clays lies in the mica - type minerals rather than the kaolinite . Thus a small amount of montmorillonite thoroughly dispersed may endow the whole clay with high strength and high plasticity while the same number of expanding layers in an illitic mica are less effective . For general descriptive purposes a ball clay can therefore be regarded as an idealised ternary system consisting of kaolinite , mica and quartz . Thus , ternary composition diagrams can be prepared which show the general range of composition of Devon ball clays . Two such composition diagrams are shown in Fig . 15 . Figure 15 : Mineral Compositions of the south and north Devon Ball Clays . Physical and Rheological Properties Compared with primary china clays , the United Kingdom ball clays contain a remarkably high proportion of extremely fine particles . The north Devon clays are the coarsest , with 20 - 30 % finer than 0 . 2 microns and 45 - 60 % finer than 1 micron . The south Devon clays have between 25 - 40 % of particles below 0 . 2 microns and between 65 - 90 % finer than 1 micron . With such fine particle sizes , all the British ball clays exhibit high modulus of rupture , the south Devon and north Devon clays having modulus of rupture between 4 . 0 - 10 . 0 MNm - 2 dried at 110 o C while Dorset clays have modulus of rupture between 4 . 5 - 7 . 5 MNm - 2 ( nowadays the MOR values are often given as MNm - 2 or MPa ( 1 MPa = 1 MNm 2 ) whilst previously the results were given as kgf / cm 2 or lb / in 2 ( lb / in 2 = MPa x 145 and kgf / cm 2 = MPa x 10 . 2 ) . The south Devon black clays contain most disordered kaolinite , least hydro - muscovite and fairly high quantities of lignitic matter . They are inclined to lack plasticity , but they have good white fired colour . The south Devon blue clays are fat and very plastic with a high content of colloidal material . The south Devon semi - lean clays are higher in quartz and lower in carbonaceous matter content than the blue and black clays , while the high silica stoneware types of clay have a higher content of coarse particles and lower unfired modulus of rupture . The north Devon clays are all of the lean stoneware type but can be divided into two types . Some of the mica content of these clays consists of mixed - layer illite montmorillonite or leverrierite , and not type has a significant montmorillonite content , having very high strength and plasticity for a lean clay , while the other type is lower in its montmorillonite content and is lower in strength and plasticity . The Dorset clays do not differ so much from one another as do the Devon clays . They all have high modulus of rupture as shown above , and they have high plasticity , the exception being a very siliceous stoneware type clay which has a modulus of rupture of only 15 kgf / cm 2 at 80 % relative humidity . As might be expected from their mineralogical composition there is a considerable variation in the rheological behaviour of ball clays . The carbonaceous matter content and soluble salts content both affect the rheology . The black and blue south Devon clays exhibit fairly high fluidity and low deflocculant demand , due , so it seems to their humic acid content , this appearing to act as a buffer . Although the blue clays produce casting slips which are easily deflocculated , they tend to need high speed dispersion . The leaner south Devon clays tend to be very thixotropic , this property being made use of when blended clays are produced for slip casting . The north Devon clays , with their traces of mixed - layer - illite - montmorillonite tend to be less easy to deflocculate . The Dorset clays produce rather low fluidity slip with high thixotropy . It is these slip characteristics which commend them for use in sanitaryware recipes . Fired Properties The fired properties of ball clays vary in accordance with their chemical and mineralogical composition . To be able to estimate the probable fired properties of a given ball clay , it is not enough merely to know its chemical composition . It is also necessary to know how the various elements present are distributed as minerals - in other words , where the SiO 2 , Al 2 O 3 , Fe 2 O 3 and alkalis are known , the amount of each of these in combination as kaolinite , hydromuscovite and quartz must be established . Generally speaking , a ball clay with a high iron and titanium content will fire to a darker colour than one with a lower content of the two , but where some of the iron occurs as a substitution for aluminium in the lattice it has less effect on the fired colour than when free iron is present as limonite or siderite . The appearance of the raw clay before firing is no guide to its fired colour , as some of the blackest and darkest brown of the ball clays both from the English deposits and from the Westerwald fire white . Given proper firing conditions , the carbonaceous matter which is the cause of this dark colour in the raw clay should be all oxidised to carbon dioxide and eliminated from the body . The south Devon clay which of all clays from the Bovey Basin contains the highest amount of carbonaceous matter is also that which has the highest fired brightness . Where the carbonaceous matter occurs in particulate form and there are an excessive number of large particles of this material present in a body , care is needed during the firing operation to avoid the problems of what is known as " black coring " . Large lignite particles may also give rise to the phenomenon of specking , but this is more often caused by the presence in the body of nodules or crystals of anatase , pyrites , marcasite or siderite . The south Devon black and dark brown clays also have the highest fires contraction and are of medium to good strength . The dark blue clays generally speaking do not fire so bright but show lower fired contraction . The semi - lean and lean clays again have lower fired brightness and also lower fired contraction . The north Devon clays fire to a brightness similar to that of the leaner south Devon clays . They have the lowest fired contractions of all the Devon clays . Dorset clays fire mostly from ivory to buff although one or two with higher iron contents fire to a russet shade . Strangely , one clay with a fairly high iron and titanium content has the best fired colour of all the Dorset clays . This is because the iron is bound up in the kaolinite lattice and not present in the free state . It has , however , the highest fired contraction , but is of good strength . Apart from this clay , almost all the other Dorset clays fire to a similar fired contraction of between 9 - 11 % at 1180 o C . The only exception to this is the very lean stoneware clay which has a good fired colour but the lowest strength of all Dorset clays . It has , however , also the lowest fired contraction , even lower than the very lean north Devon clays . The presence of the finely divided micaceous material in both north Devon and Dorset clays appears to contribute greatly to their vitrification . Classification of Ball Clays WBB have proposed a classification of ball clays - for the south Devon area the clays have been divided into four groups ; South Devon ( Bovey Basin ) Ball clays . Group 1 . Clays in this group are noted for their excellent fired colour . They are dominantly kaolinitic with low mica and quartz contents and frequently contain appreciable quantities of carbonaceous matter . This carbonaceous matter can act as a protective colloid in the production of clay / water slips , and ensure a high fluidity and low alkali demand at optimum deflocculation . historically , clays from this group were termed " black " ball clays . Group 2 . The clays from this group , the so called " dark blue " clays , are again dominantly kaolinitic , but contain rather more micaceous mineral and quartz than the clays of Group 1 . These clays also contain a certain amount of carbonaceous matter which is generally helpful in producing easily deflocculated casting slips . The clays of this group are amongst the strongest clays found in the South Devon deposit . Group 3 . The clays of this group , the so - called " light blue " clays , contain rather less kaolinite and higher proportions of mica and quartz than clays of the preceding two groups . Generally speaking , the carbon content of these clays is low ( less than 0 . 5 % ) . Clays in this group tend to be extremely thixotropic and use is made of this property in the production of blended clays intended for slip casting . Group 4 . The clays of this group are the most siliceous of the Devon clays . They are generally similar to the clays of Group 3 , but with higher quartz contents and lower carbonaceous contents . Fig . 16 shows the general form of the dilatometric curves of clays of each of these groups - the original basis of this classification . To a certain extent these groupings are arbitrary and , inevitably , some overlap occurs with some seams falling between adjacent groups . Figure 16 : Characteristic thermal expansions of south Devon Ball Clays . North Devon Ball Clays ( Petrockstow Basin ) The north Devon clays are more difficult to classify , but basically there are two types : Type 1 . Contain appreciable quantities of montmorillonite resulting in high deflocculant demand values and relatively high slip viscosities . Type 2 . Contain relatively little montmorillonite , and consequently have lower deflocculant demand values and relatively high slip viscosities . This relatively simple classification can , however , be confused somewhat by the presence of extremely siliceous types of clay found in association with both the above groups . Table V summarises the chemical analyses of clays typical of th above mentioned groups of south and north Devon ball clays . Table V : Chemical and Mineralogical analyses of Typical Devon Ball Clays . Physical Properties of Ball Clays The principal physical characteristics of ball clays from the various production area in Devon are summarised in Table VI , and , generally the widest spectrum of properties is obtained from the south Devon clays , this being consistent with their origins and previously described mineralogy . Fig . 17 illustrates typical ball clay deflocculation curves of Type A and Type B referred to in Table VI . Figs . 18 and 19 illustrate fired colour and vitrification characteristic of the four main groups of south Devon clays . Figure 17 : Deflocculation characteristics of English Ball clays from Devon . Figure 18 : Fired colour / temperature relationship of south Devon Ball Clays . Figure 19 : Vitrification characteristics of south Devon Ball Clays . It is rare that any single clay can be found which completely satisfies all the manufacturing requirements of any one product . For this reason blended clays are produced which consist of many components from several individual seams , each selected in order to provide its own specific contribution to the physical properties of the final blend . Thus , it is possible to buy blends of south Devon Group 1 , Group 2 and Group 3 clays , as well as blended clays containing components from the north Devon production areas . Obviously different sets of criteria are important to the production of any specific blend . For example , a blended clay produced principally for use in the sanitaryware industry would have as its principal requirement an easily deflocculated , easily controlled , fast casting , stable , predictable slip , with high green strength , yet without excessive drying contraction which can result in cracking and distortion . Such a blend may be produced by the judicious mixing of the carbonaceous Group 1 south Devon clays with , for example , plastic Group 2 clays and some of the north Devon material to assist in vitrification . Undoubtedly , the most suitable clays for the production of this type of ware are blends of the north Devon clays . These have the additional advantage of remaining workable over a wide range of moisture content and are also eminently suitable for extrusion or large pieces which are to be subsequently finished by turning . The ball clay producer , ever mindful of the changing circumstances throughout the industry due to the rapid advancement of technology , continues to improve the flexibility and control of each blend he produces , and additionally continues his researches for new blends to remain abreast of the steady improvements and modifications in production methods . Production Processes For ECC the production process is essentially the same in all three areas - North and South Devon and Dorset . Initially the raw component clays are selected and mined in the pit according to the recipe in question . A general view of a ball clay pit is shown in Fig . 20 with an underground mine entrance in Fig . 21 . An intimate knowledge of the different clays in the deposit allows the pit operatives to select the different seams of clay with great accuracy with digging machines ( Fig . 22 ) . Nearly all the production is in open pit working , but ECC also operates four underground mining is high but it is believed that the quality benefits imparted by these hard - won materials are extremely worthwhile . Figure 20 : A general view of a Ball Clay pit from Devon . Figure 21 : An underground Ball Clay Mine entrance . Figure 22 : Accurate selection of Ball Clay seam in a typical pit . The individual component clays are then transported to a central processing plant where they are stored in individual bays awaiting blending . Some blends contain clays from more than one production location . Each component clay undergoes a process of shredding ( Fig . 23 ) before being mixed with others according to the blend recipe . Some very complex blends are made up from a number of sub - blends which are then mixed to ensure homogeneity ( Fig . 24 ) . The final blend is then stored separately ready for despatch . Most of the ball clays are sold in this shredded form , but facilities also exist for a range of further processing options , in particular drying , granulating , milling and classifying . For instance , shredded clays can be dried to a moisture level of 8 % , and the , if required , broken down to a granular form . The most common form of further processing however is milling ( Fig . 25 ) . ECC operates six mills in which the clay is first dried and then disintegrated into powder . If required the powder clay may then be further refined by a process of microseparation . Most of the powder clay is then bagged , palletised and shrink - wrapped . Several stages of further beneficiation of ball clays are carried out at ECC ' s Caly Center in Stoke - on - Trent ( Fig . 26 ) . These involve the refining of the materials to a condition where they are ready - to - use by the customer without further processing . They clay is mixed with water to form a slurry which further processing . They clay is mixed with water to form a slurry which is passed through vibratory sieves and across electro - magnets . The clay slurry can then either be delivered to customers in ready - to - use form or spray dried to form a granulate . Spray dried granulate ( Hypure ) is extremely easy to turn into slurry or to blend with other materials in an extensive mixing process . A summary of the ball clay production process is shown in Fig . 27 . Figure 23 : Primary shredding of the Ball Clay . Figure 24 : Blending of the various components in a mixer . Figure 25 : A typical milling facility to process Ball Clay . Figure 26 : The Clay Centre at Stoke - on - Trent . Figure 27 : Summary of the Ball Clay Production Process . Quality control is an important aspect of the production process and beings at the exploration stage continuing throughout the whole process by sampling clay at the pit face , before , during and after blending , and finally , prior to despatch . All testing takes place on a routine basis in the production control laboratories situated in each of the three production areas . Clays are tested for various characteristics such as chemical composition , modulus of rupture , rheological and fired properties . A standard system of testing is used and details of these tests were presented previously [ 8 ] . BALL CLAY PRODUCTS A summary of some of the ECC ball clay products from Devon and Dorset is presented in Table VII and VIII respectively . There are a large number of products but the main types may be summarised as follows ( Table IX ) : Table IX : Main Types of Ball Clays WBB Devon Clays Ltd produce a wide range of refined , composite and standard ball clay blends along with a range of clays based on the Groups 1 to 4 . A summary of their product range from Devon is shown in Table X . BALL CLAY UTILISATION Tableware The ECC International Europe tableware ball clay range consists of seven key products - Hyswite Astral , Hywite Superb , Hywite Magnum , Hymod Blue , Hymod Prima , Hyplas 64 and Hypure Sigma . The key characteristics of the seven products are fired colour , strength and plasticity and fluidity . The range is suitable for all types of tableware and most production processes including plastic making , slip casting , pressure casting , dust pressing and ram pressing . Table XI summarises the data for the seven products with details of typical recipes for Earthenware , Fine stoneware , Hotelware and Porcelain . Table XI : The ECC International Europe tableware ball clay range . Sanitaryware The ECC International Europe sanitaryware ball clay range consists of four key products - Hycast Classic , Hycast Rapide and Hycast Mega . Table XII shows the typical data for the clays with key characteristics and applications shown . Some typical recipes for various end uses are also shown . Table XII : The ECC International Europe sanitaryware ball clay range . Summary of Producers The largest producer of ball clay in the UK is WBB Devon Clays which operates seven open pits and two mines in the Bovey Basin and two open pits in the Petrockstow Basin . The company produces about 500 , 000 tpa from these two deposits . Around 200 , 000 tonnes of production is used in sanitaryware applications , including some 135 , 000 tpa of Sanblend . Blended specifically for the sanitaryware industry , the series includes Sanblend 75 , the world ' s first refined ball clay . Over 80 % of WBB Devon Clays ' products are exported and world - wide demand continue to grow . To meet this increasing demand the company is planning to integrate its south Devon operations to form a single pit , thus allowing the efficient extraction of higher levels of ball clay . This expansion will be achieved by close cooperation with local planning authorities and environmental bodies [ 9 ] . ECC International Europe Ball Clays produces approximately 330 , 000 tpa from its three deposits . Almost 95 % of the production is sold to the ceramics industry . New products are fast being developed to meet the increasing demand for high quality and consistency . BALL CLAYS FROM THE WESTERWALD , GERMANY General Geology Clays are mined throughout Germany but by far the most important regions for the production of plastic clays is the Westerwald region . The Westerwald region is situated between Frankfurt and Bonn ( Fig . 28 ) and the main area of the basin is divided into a number of topographic and generic basins which are controlled bye earlier fault patterns . The nature and geology of the clays the Westerwald region differs from those found in the UF , in that the structural geology is simpler and clay more variable in their content ( as demonstrated by the mineralogy in Fig . 29 ) . Clay bearing sequences were laid down in subsidence hollows in the Tertiary period , some 25 - 45 my ago . The deposits comprise fine grained clays , largely disordered kaolinite , together with sand , silt and other detritus derived from the Devonian strata . The clays were laid down in phases , the first being a period of sandy outwash fan deposition , with occasional lacustrine interludes . The more complex second phase followed which occurred over a much wider area leading to deposition of clays ranging from coarse sediments to fine grained plastic clays . Volcanic activity commenced towards the end of the second phase , and the subsequent weathering of the mainly basaltic lavas dramatically increased the iron content of the clays . The clays deposited during the volcanic episode are characterised by high iron contents , the highest of which impart a clear red colour to the fired body . During the final phase of sedimentation grey clays of lower iron content are predominant . However the presence of small amounts of montmorillonite in these final phase clays still indicates some volcanic influence . Figure 28 : Location of the Westerwald Ball Clay area , Germany . Figure 29 : Ternary composition of the Westerwald Ball Clays . A Major Producer - WBB ' s Fuchs - Ton The Italian floor tile market accounts for over 30 % of Fuchs ' Westeerwald ball clay sales , and whilst the weakness of the Italian Lira since September 1992 has boosted the already substantial export sales of Italian ceramic tile customers , it has also generated strong pressures on the pricing of imported Westerwald ball clay . This pressure has been exacerbated by increasing imports of competitively priced Ukrainian and French ball clays . Mainly as a result of these pressures , Fuchs lost some important customers at the end of 1993 . Whilst sales tonnages in Italy recovered during the year , Fuchs were unable to increase prices in Italy in line with production costs in Germany . In the German domestic market for Westerwald ball clays , demand from Fuchs ' high quality facing - brick customers was strong , but demand weakened from their ceramic drainage pipe customers . Demand from the domestic floor tile sector also weakened due , principally , to increased imports , especially from Italy . Although exports to Belgium and the Netherlands continue to grow , Fuchs ' ball clay sales tonnages in 1994 fell by 1 % to about 1 . 07 million tonnes . In 1994 , Fuchs - Ton ' s substantial ceramic body preparation busines in the Westerwald had to contend with the loss of a number of local ornamentalware customers , who went out of business due to the recession in Germany and increasing imports of low priced products from countries such as Portugal . Nevertheless , some of the surviving companies have performed very strongly , enabling ceramic body sales tonnage to be maintained at about 105 , 000 tonnes . The total turnover of the on - going Westerwald ball clay and ceramic body businesses in 1994 was unchanged from the pervious year at DM63 million whilst margins fell about 1 . 5 % . WBB acuire MPR In 1994 Fuchs - Ton completed the acquisition on the 1st October of Martin & Pagenstecher Rohstoffbetriebe ( " MPR ) . MPR is the third largest producer of ball clays in the Westerwald whose sales tonnage in 1994 was almost 550 , 000 tonnes . It has reserves and operations largely complementary to those of the existing Fuchs - Ton business . The sales of MPR in the year ended 30th September , 1994 were approximately £ 7 . 5 million , and the pre - tax profit , before exceptional items , was approximatly £ 0 . 7 million . WWB HAS Significantly added to its reserves of Westerwald ball clay by this acquisition which strengthens its leading market position already enjoyed by Fuchs - Ton - the company now have a wide range of ball clays available and the business is already benefiting from the application of the group ' s technology . Seilitz - Lothain , Fuchs - Ton ' s kaolin and ball clay operation near Meissen ( formerly East Germany ) which was acquired in 1990 , had a very successful year in 1994 , with sales tonnages up more than 40 % to almost 80 , 000 tonnes resulting in a substantial increase in profitability . Products Fuchs - Ton produce plastic clays from the westerwald , Vordereifel and Pfaz regions of Germany . A large number of grades of ball clay are prepared on the basis of their fired colour - white - light grey , light grey - light cream , yellow and light red - dark red . These colours are largely dependent on the iron values with titania levels being much the same in all types of clay . A summary of the Plastic Clays is shown in Table XIII along with kaolinitic clays from elsewhere in Germany and plastic clays from the small operation of Pornon & Cie in the Allier region of France ( 40 , 000 tpa ) . Fuchs - Ton also produce in Germany a plastic body , crumble body , dry powdered body , spray - dried body and a casting slip by bulk container . U . S . A . BALL CLAYS Ball clays of the U . S . A . are found in Kenthcky and Tennessee ( Eocene Age ) and in Texas ( Lower Eocene Wilcox Group ) . The total production is around 1 million tonnes and the main companies involved are Kentucky - Tennessee Clay Company and United Clays Inc ( a subsidiary of Watts Blake & Bearne PLC ) . The prime market in the USA for ball clay is the whiteware industry , with dinnerware and pottery , wall and floor tiles and sanitaryware market sectors dominating . Significant quantities are also used to produce refractories , tableware , electrical porcelain and glazes , and in total these applications account for more than 70 % of domestically produced material . There has also been an increase in the amount of ball clay consumed in the fiberglass industry and also in insulating fireboard as the amount of asbestos used decreases . This is owing to ball clay ' s intrinsic properties as a fire retardant and filler [ 13 ] . Kentucky - Tennessee operates from active mines in Kentucky , Tennessee and Mississippi and has four processing plants at Mayfield , Kentucky ; Gleason , Tennessee ; Whitlock Tennessee ; and Sledge , Mississippi . Approximately over 500 , 000 tpa is produced with over 50 different blends to suit specific customers ' requirements . United Clays Inc ( WBB ) produce 400 , 000 tpa of ball clay and soapstone from their operations in the USA . The ball clay is mined in Indiana , Mississippi , Tennessee and Texas . The growing Mexican ceramics markets became increasingly important for United Clays during 1994 . They are only producer of Texas ball clays which are particularly well located to serve both the Texas and Mexican ceramic tile markets . In the early part of 1994 a new grade of Texas ball clay for ceramic wall tile manufacture was successfully introduced and , achieved substantial sales during the year , helping total Texas ball clay and soapstone sales tonnages to increase by 16 % . The Mexican sanitaryware and dinnerware industries are important markets for Tennessee ball clays . During the early part 1994 , pilot plant production of refined ball clay noodles for this market was successfully tested by a leading Mexican sanitaryware customer , as a result of which the pilot plant was scaled ut to satisfy sales , currently running at the rate of 25 , 000 tpa . United clays are the only US producers of refined ball clay noodles , and the introduction of this product has further enhanced their technical reputation . The greater part of US ball clay sales to the domestic sanitaryware industry is supplied in the form of refined slurry , of which United Clays is a leading producer . Slurry sales form the Gleason plant in Tennessee continued to grow in 1994 . The range of ball clays produced in the USA by United Clays is shown in Table XIV . CZECH REPUBLIC BALL CLAYS The areas for ball clay production in the Czech Republic are shown in Fig . 30 . There are three main types of ball clays ( " tone " clays ) exploited in the Czech Republic as follows ; a . White burning clays ( white firing ) . b . Ball Clays . c . Refractory Clays . Figure 30 : Location of the Czech Republic Ball Clays . There are mine area for ball clay production and these areas are described in Table XV with the name of the mine , ball clay classification and production name . There are five companies operating in the mine areas but the situation regarding ownership is changing since privatisation of large parts of the Czech economy . Table XV : Ball clay producing regions with details of Mines , Clay types and Product Names , Czech Republic . Production and Quality of Czech Ball Clay In the Czech Republic the best quality white firing ball clay is often used on wall tiles - even though with glazing this is not important on the wall the Czech ' s by tradition , will always look at the unglazed side to see if it is white firing ! The production of clays in the Czech Republic is as follows for 1990 ( Table XVI ) : Table XVI : Production of Ball Clays in the Czech Republic for 1990 . For white - burning clays the best quality ball clay is found in the Cheb basin . The ball clay is mined in the Nova Ves , Karel and Vackov areas ( Fig . 30 ) . These deposits have been exploited since the nineteenth century and some clays is exported to Germany . The lower part of the basin is formed by lignite covered by green clays . In the deposit of Nova Ves the white burning clay series commence above the green clays with a very bituminous clay knows as Nero F and continues to the IB clays . These clays are characterised by fine particle size , very good plasticity , white firing , good MOR and relatively low iron and titania . Production of white burning clays from the Cheb region is said to be 160 , 000 tpa . The clay Wi from the Karel mine is deposited on the green clays and shows similarities to the IB clay but with higher iron and titania . The KyF ball clay from the Kysice deposit ( Pilsen area ) is said to be white - firing but is not of the same quality as Nero F . The white - burning clays are the ones that we would compare to ball - clays from other regions . The so called ball - clays and refractory clays is mainly used in heavy clayware and as source of sintering clays [ 14 ] . BALL CLAYS OF THAILAND Location and Geology Claymin ( a subsidiary of WBB ) was established in 1986 and is a joint venture to develop the ball clay deposits of Northern Thailand . Total sale of all products in 1994 exceeded 100 , 000 tonnes . The thriving domestic ceramics industries are the major market for these clays , and exports continue to grow steadily . The deposits are situated in the Lampang area of Northern Thailand ( Fig . 31 ) at Mae Than , Wang Nua and Jae Korn . Geologically the oldest of the three deposit is at Mae Than , about 40 km south of Lampag . The Mae Than deposit is of Lower Triassic age and the workable clays found consist of reddish - brown conglomerates , sandstones , tuffaceous sandstones and calcareous shales . The main clay sequence , underlain by a subbituminous coal seam , probably represents lacustrine and backswamp enviromental phases . It is 24 metres thick and includes 22 seams of five different selections . Figure 31 : Ball Clay Deposits of Northern Thailand . The deposit at Jea Korn , 65 km north of Lampang , lies unconformably upon the Triassic rocks of the area , and is of Tertiary age . The Tertiary rocks include freshwater sandstones , shales , carbonaceous shales , limestones and lignites . The clays sequence occurs in the shales of Pliocene and Miocene age and includes clays of mainly white , yellow and red colour . Their third clay deposit is situated in the Wang Nua area , 100 km north of Lampang , and these clays are the most recent in origin and contain much organic material . They were probably laid down in a backswamp environment associated with the rise in sea level around 6 - 8000 years ago . There is very little overburden covering these clays enabling the extraction process to be easily carried out . Properties of the Clays Mae Than Area Mae Than area contains five different types of clay and in each the principal clay mineral is disordered kaolinite , associated with illitic mica and quartz . In addition , certain of the seams contain an interstratified clay mineral , and colloidal carbonaceous matter . Two Types of carbonaceous clays may be identified , which represent the most plastic and strongest , which is almost certainly a reflection of the influence of the colloidal carbonaceous matter which is present . Clays of this type ( e . g . Mae Vit W ) are particularly suited to the production of tableware ( both vitreous and porous ) where a clean fired result is desired . The second type of carbonaceous clay , containing rather less carbonaceous material , is again a strong and plastic clay which deflocculates easily and presents a good , clean , fired colour . The properties of this type of clay make it ideally suited to incorporation in blends for the production of vitreous china sanitaryware ( e . g . Mae San ) . The carbonaceous clays from Mae Than represent the most fine grained of materials available from this area . The remaining three types of clay are all non - carbonaceous , and contain more free silica in the form of quartz than the carbonaceous clays . They are less plastic and more coarsely grained , and careful blending of these three types can produce a clay ideally suited to the production of white - firing porous wall tiles ( e . g . Mae Tile ) . Jae Korn Area Three types of clay may be identified from the Jae Korn deposit on the basis of their raw and fired colours ; a red firing clay , a buff firing clays and a white firing clay . All three types are extremely fine grain , very strong and highly plastic . For some of these clays , green strengths in excess of 150 kg / cm 2 have been recorded . The clay consists of a disordered kaolinite together with illitic mica and quartz , with varying amounts of chlorite . Occasional goethite has also been noted . It is the presence of chlorite , and to a lesser extent goethite , in the red and buff burning varieties , which give rise to the fired colour exhibited by these materials . The presence of organic matter in either colloidal or massive form is not significant . Because of their strength and plasticity , the red and buff burning varieties are ideally suited to the production of extruded vitrified products , particularly split tiles and bricks ( e . g . Jae Vit R ) . The white burning variety , which can be deflocculated readily , has useful application as a plasticising agent in many white firing ceramic compositions , including sanitaryware and tableware bodies . Details of the quality of the Mae Than and Jae Korn products are shown in Table XVII . Wang Nua Area The clay in this area consists of a disordered kaolinite , associated with small quantities of illitic mica and some quartz . Very small quantities of interstratified mineral have also been detected , and all examples of the clays contain large quantities of colloidal carbonaceous material . A consequence of the fine grain size and the high level of colloidal carbonaceous matter is a very high green strength , in excess of 150 kg / cm 2 . The clays deflocculate readily , have generally low residues and fire to a clean cream colour at 1200 ° C . Their chemical and physical properties make these clays suitable for inclusion in blends intended for the production of vitreous sanitaryware and also white firing porous and vitreous tableware . Chinese Ball Clays WBB Pacific Clays have a joint venture in Guangdong Province , China , in which the Division has invested through Clayorient in Hong Kong , has not been as successful as planned owing to the slow acceptance in the region of the particular refined clays produced by Xiangshan . Another problem has been the sterilisation of ball clay reserves as a result of the extremely rapid development of construction in the area where the plant is located . However , because of the enormous potential of the Chinese market , other opportunities exist which are being actively pursued . The quality of Ball Clay No . 1 is shown in Table XVII . BALL CLAYS OF INDONESIA - KALIMANTAN There are a number of ball clay prospects in Indonesia and the one considered here is the operations of PT Clayindo . The ball clay concessions of the company are situated approximately 100 km north of Pontianak ( on the equator ) on the island of Kalimantan ( formerly Borneo ) . Geologically the sequence is 4 - 5 m of overburden with an observed sequence of up to 10 metres of light creamy brown ball clay interbedded with sandy horizons . The method of mining is the traditional way with a " tubal " ( see Fig . 1 earlier ) following removal of overburden by an excavator . Production is up to 5 , 000 tonnes per month . There appears to be potential in the region for good quality ball clay and the current mined material is white firing but with low strength . Blending with other grades of ball clay may be necessary to meet the specification of higher quality ceramic potting applications . A typical result from the deposit near Pangkalam Batu shows a MOR of 23 ( at kg / cm 2 at 110 ° C ) , a fired brightness of 74 , absorption of 17 . 5 and contraction of 3 . 7 at 1120 ° C , and iron and titania levels at 1 . 1 and 1 . 2 wt . % respectively and the SiO 2 level of 58 % is reflected in the mineralogy of 73 % kaolinite , 8 % mica and 19 wt . % quartz . BALL CLAYS OF ARGENTINA The San Julian area of Patagonia ( Fig . 32 ) contains sedimentary clays of Quaternary age which are exploited as ceramic kaolins and utilised as a ball clay substitute . There are some 70 prospects in the area of which several are being mined . Some years ago the following mines were producing with the product name and utilisation shown ( Table XVIII ) : Figure 32 : Location of the San Julian Ball Clays , Argentina . Table XVIII : Mines , products and utilisation of San Julian ceramic kaolins . The Tehuelche mine shows three distinct layers of clay which are mined selectively for different end - uses as indicated in Table XVIII . There is little difference between the quality of the layers apart from the presence of carbonaceous ( lignite ) material present . The El Chulengo mine exhibits a grey to white matrix , the colour depending on the carbonaceous content , and consists of kaolinite and fine - grained silica . The clays here are not so fine grained as ball clays elsewhere in the world but they have been effectively used as a ball clay substitute . A typical analysis of a ceramic kaolin from the Tehuelche and El Chulengo mines is shown in Table XIX . Table XIX : Quality of " Ball clay " from San Julian , Argentina . BALL CLAYS OF BRAZIL General There are a number of small producers of so called " ball clay " in Brazil especially in the region around São Paulo - São Simão , Suzano and Ribeirão Pires , amongst others ( Fig . 33 ) . All the clays , with a few exceptions , can be classified as ceramic kaolins rather than the true ball clays and it is often necessary to blend one or two of the different clays to arrive at a suitable ceramic body . There is a need still in Brazil for more investment in the exploration and exploitation of ball clays to meet the future requirements of the important ceramic industry . A brief description of some of the deposits is now given . Figure 33 : Location of Ball Clays in the São Paulo Region , Brazil . São Simão Ball Clay The São Simão ball clays are mined in a number of concessions and are sedimentary in origin . They are usually light grey silty to sandy clays with little carbonaceous matter . One sample , a browner variant , contain much peat - like fibrous material which suggest a young ( perhaps Quaternary ? ) age for the deposits . Orange and yellow staining is common in the near surface samples ; the iron contaminant is finely divided and has a deleterious effect on fired colour . Most of the free quartz , which can be as high as 24 % , is sufficiently coarse to be removed by screening at 300 # . The - 120 # quartz may be advantageous in modifying rheological properties for sanitaryware . For tableware further screening of the siltier clays at a finer mesh would probably be beneficial in reducing abrasion and improving plasticity . Testing of a number of samples from the São Simão area shows a wide range of fired brightness values . The principal clay mineral present is kaolinite , probably a very well - ordered variety . Electron micrographs show hexagonal platelets with well defined crystal faces throughout the particle size range ( Fig . 34 - this should be compared to the TEM of an English ball clay in Fig . 13 which is a disordered kaolinite ) . Free quartz varies from 3 to 24 % , kaolinite accounting for more than 90 % of the remaining minerals . Mica content is low with the kaolinite / mica ration being close to 20 : 1 . Traces of montmorillonite were detected by XRD but are too small to have any effect on physical properties . Similarly not more than 1 % gibbsite is present ; minor peaks are clearly evident on the DTA curves but here also the quantities are not significant . Figure 34 : SEM of the São Simão Ball Clay , Brazil . Particle size distributions were carried out on nine samples and the results are shown in Fig . 35 . Apart from the finer sample , G , the particle size distributions are similar in shape and range are typical of sedimentary kaolins . The sub - micron fractions are considerably less than British ball clays . There is a very broad relationship with moduls of rupture ( Fig . 36 ) . Halloysite was not detected by XRD or in the electron micrographs . Good casting concentrations and casting rates with low deflocculant demand and thixotropy were found . Figure 35 : BRAZILIAN CLAYS São Simão PSD - 300 # Fraction ( Calculated ) . Figure 36 : BRAZILIAN CLAYS - São Simão . Of the samples examined only G has physical properties approaching a ball clay . Its strength is similar to Hywhite Superb ( a blend of carbonaceous clays from south Devon ) but its casting concentration is inferior . Nevertheless , a blend of G with any of the unstained São Simao clays could form the total clay component of a good casting body . The future development and importance of the São Simão deposits would be considerably enhanced if more of the G type clay could be found . Its strength together with good fired colour are invaluable and it could be used to greater advantage than fine clays from other areas . for other uses , such as tiles and tableware , the São Simão clays would serve as kaolins but need to be supplemented by stronger , more plastic clays from elsewhere . The results of the São Simão clay ( sample G ) are shown in Table XX . Table XX : Test results of a São Simão Ball Clay . Santo Amaro Clays , Ribeirão Pires The Santo Amaro clays are light , brown - grey , sandy to gritty , and slightly carbonaceous . From samples examined the quartz content varies widely , ut to maximum 29 % . Apart from those samples containing much free quartz , plasticity and modulus are similar to the south Devon range of ball clays . The particle size distribution curves ( Fig . 37 ) for the Santo Amaro clays are alike ; each clay contains a high proportion of sub - micron material . Their high moisture absorption is also consistent with large surface area . On the contrary , casting properties are better than expected for this particle size range . Casting concentrations are high though deflocculant demand is high . Deflocculation curves are quite normal and slip control should not be difficult . Gibbsite present has no adverse effect on rheology . Figure 37 : BRAZILIAN CLAYS Santo Amaro PSD - 300 # Fraction With high alumina and low alkalis , the clays are open burning and even more so when gibbsite and carbonaceous matter are present . Mineralogically the clays are dominantly kaolinite - probably of a fine , disordered type . The Santo Amaro clays are useful in providing strength and plasticity , an to supplement the weaker sedimentary kaolins . Their main disadvantage is their variable quartz content which has to be largely removed to prevent abrasion and cracking and to improve workability and surface finish . Suzano and Nigrii Clays The clays from this area are light grey to brown , sandy to very sandy clays with very little iron staining . The free quartz varies from 7 - 45 % in the Suzano samples examined and 12 - 41 % from the Nigrii deposits . Abnormally high alumina is due to appreciable amount of gibbsite , particularly in the Suzano clays ( as high as 41 % Al 2 O 3 with 13 % gibbsite in one sample ) . The excess alumina and low alkalis make these clays open burning . Improved vitrification of the - 300 # material is due to removal of quartz and coarse gibbsite particles . The coarse gibbsite can be visually separated from the free quartz ; it is a dull white microcystalline material . Fe 2 O 3 values fall within fairly narrow limits , 1 . 0 - 1 . 4 % in the raw unscreened samples . TiO 2 is more variable , 1 . 1 - 2 . 8 % , and is mainly responsible for variation in fired colour . Kaolinite is of fine particle size , mainly disordered . Halloysite is detected by electron microscope in some of the samples . Particle distribution curves ( Fig . 38 ) are similar in shape to those for Santo Amaro clays but the > 5 micron fractions are greater . The range of modulus of rupture is also similar but plasticity is impaired by high free quartz content . Casting properties are generally good . Thixotropy is low and there is no evidence that it is influenced by gibbsite in the samples examined . Figure 38 : BRAZILIAN CLAYS Suzano & Nigrii PSD - 300 # Fraction ( Calculated ) . Summary of São Paulo Region Ball Clays The São Simão clays are sedimentary kaolins with variable quartz content . Strengths are typically low with poor plasticity but rheological properties are good . Although iron and titania levels are of the order of 203 % , high fired colour and absorption reflect the low level of alkalis . They are used in sanitaryware , tableware and tiles . The finer clays from Santo Amaro , Suzano and Nigrii are more like ball clays in strength and plasticity , but have the disadvantage of containing considerable amounts of free quartz . They are also fairly open burning with low alkalis : fired colours at 1180 ° C are good but are likely to fall with additional fluxes in a body . Gibbsite is a common constituent in these clays but appears to have little effect on their good rheological behaviour . Mineração Tabatinga Ltda A visit was made to operations of Min . Tabatinga following the Curitiba Congress in 1993 . The area is within the Parana depression and consists of a series of sedimentary sequences which are green , grey and whitish in colour . The project started some 15 years ago and following a detailed drilling and evaluation programme a resource of some 500 million tonnes , enough for 400 years , has been identified . Production in 1993 was put at 12 , 000 tonnes per month , mainly destined for the São Paulo market due to being adjacent to the main BR101 highway . Strip mining was taking place at the rate of 1 hectare / year . Clay is mined from several areas - Mina1 , Mina 2 , Susi , Preta and AD44 . Various grades are sold for tableware , sanitaryware , refractories , tiles and many other uses . The physical and chemical characteristics from several of the mines is shown in Table XXI . ACKNOWLEDGMENTS The writer would like to thank the Brazilian Ceramic Association for their kind invitation and support to attend the 1993 Congress in Curitiba during May 1993 and to present this paper on Ball Clays . Thanks are also due to the Directors of Mineração Tabatinga for organising such an excellent field trip to their ball clay operations . I would particularly like to thank Quentin Palmer , Chief Geologist of ECC Ball Clays , Wareham , Dorset for providing some of the information on ball clay exploration . Also to Nigel Glasson , the Technical Director of ECC Ball Clays , for many discussions on ball clays over the past few years . Thanks to my colleagues in ECC International Europe , especially Chris Hogg , Ian Attwood , Richard Hirst and Caryl Gould for information on ceramic raw materials , and also to Simon Warren of ECC Am - Pac based in Atlanta , USA . I would also like to thank Dr . Simon Mitchell of Watts Blake & Bearne Ltd for kindly sending me information on their range of products and operations in many parts of the world . I would particularly like to thank all the mine owners in many parts of the world for permission to visit their operations . In Brazil I would like to thank the late Frederico Angeleri of Celite S . A . who introduced me to the ball clay deposits of the S . Paulo regions . Thanks also to Ivo Pellegrino of Santo Amaro S . A . for being so helpful in supplying information on his mines and products . May I also thank once again Professor Persio de Souza Santos for all his help in preparing this paper and for all his kindness over the last 20 years in introducing me to so many mine owners and ceramic companies . Finally thanks also to my colleagues in ECC do Brasil , particularly Jan Bidwell ( Managing Director ) and Pedro Bottesi ( Geologist and responsible for Mining and Exploration ) . REFERENCES [ 1 ] I . R . Wilson , " Ball Clays " inglesas ; origens , propriedades e usos em cerâmica , Cerâmica , 29 , 165 ( 1983 ) 217 - 238 . [ 2 ] C . M . Bristow , The derivation of the Tertiary sediments in the Petrockstow Basin , North Devon , Proceedings of the Ussher Society , 2 ( 1968 ) 29 - 35 . [ 3 ] M . J . R . Fasham , A gravity survey of the Bovey Basin , Geological Magazine , 108 ( 1971 ) 119 - 130 . [ 4 ] E . C . Freshney , et al . , Geology of the country around Chumleigh , Memoirs of the Geological Societh of Great Britain , London , ( 1979 ) . [ 5 ] M . E . J . Chandler , The Oligocene flora of the Bovey Tracey lake basin , Devonshire , Bulletin of the British Museum ( Natural History ) , 3 ( 1957 ) 71 - 123 . [ 6 ] A . Vicent , Sedimentary environments of the Bovey Basin , Unpublished M . Phil . Thesis , University of Surrey , England , ( 1974 ) . [ 7 ] R . A . Edwards , Tertiary sediments and structure of the Bovey Basin , South Devon , Proceedings of the Geologists Association , 87 ( 1976 ) 1 - 26 . [ 8 ] D . A . Holdridge , Composition variation in ball clays , Transactions of the British Ceramic Society , 11 ( 1959 ) 645 - 659 . [ 9 ] WBB Devon Clays Ltd . WBB publication on " The production and properties of Devon Ball Clays " , Booklet . [ 10 ] I . R . Wilson , Constituição , avaliação e propriedades cerâmicas de caulins de alta qualidade , Cerâmica , 41 , 270 ( 1995 ) 81 - 100 . [ 11 ] Industrial Minerals , March 1996 , UK Minerals , Section on Ball Clay , 39 - 41 . [ 12 ] Watts Blake & Bearne & Co PLC , Report & Accounts for 1994 . [ 13 ] A . Russel , Ball & Plastic Clays - value added products for ceramic demands , Industrial Mineral , October ( 1988 ) 27 - 47 . [ 14 ] Czech " Tone " ( Ball - Clays ) Clays , Czechoslovak Ceramics Booklet . ( * ) A tradução adequada de “ ball clays ” é argilas plásticas para Cerâmica Branca ; não é usada na Indústria Cerâmica Brasileira , nem a tradução ao pé - da - letra “ argila bola ” . Já é pratica normal o uso do termo original “ ball clay ” . © 2006 ABC Caixa Postal 11049 05422 - 970 São Paulo SP CMDMC - CCTM - IPEN Av . Lineu Prestes , 2242 - Cidade Universitária 05508 - 900 São Paulo SP - Brazil Tel . / Fax : ( 55 11 ) 3816 - 9343

This chapter is about basic conditions of seeing motion ( mostly of single objects in the frontoparallel plane ) . It emphasizes the richness and challenge of phenomena in motion perception . Apart from the distinction between afferent ( retinal ) and efferent ( oculomotor ) mechanisms , motion percepts can result from real ( object ) motion as well as from various forms of apparent motion ( stroboscopic or phi motion , induced motion , autokinesis ) . Further intriguing motion phenomena include motion contrast and assimilation , motion adaptation and aftereffects , and velocity transposition . Finally , anticipatory performance of motion extrapolation is considered as a dynamic case of amodal perceptual completion , indicating that visual motion is closely related to action . Keywords : Motion perception ; Afferent / efferent mechanisms ; Oculomotor system ; Apparent motion ; Velocity transposition ; Motion extrapolation RESUMO Este capítulo é sobre as condições básicas no ver movimento ( na maioria das vezes , de um único objeto no plano frontoparalelo ) . Ele enfatiza a riqueza e o desafio do fenômeno da percepção do movimento . Longe da distinção entre mecanismos aferente ( retinal ) e eferente ( oculomotor ) , os perceptos de movimento podem resultar de movimento real ( objeto ) assim como de várias formas de movimento aparente ( estroboscópico ou movimento phi , movimento induzido , autocinese ) . Outros fenômenos de movimento intrigantes incluem contraste de movimento e assimilação , adaptação e pós - efeitos de movimento , e transposição de velocidades . Finalmente , desempenho antecipatório da extrapolação do movimento é considerado como um caso dinâmico da completação perceptual amodal , indicando que o movimento visual está estreitamente ligado à ação . Descritores : Percepção de movimento , mecanismos aferente / eferente ; Sistema oculomotor ; Movimento aparente ; Transposição de velocidade ; Extrapolação de movimento INTRODUCTION Motion is perhaps the most important and powerful visual stimulus dimension . Practically everything of any interest in the visual world moves . Stimuli that share approximately the same speed and direction are seen as a unit , a figure , that is easily segregated from the background according to the Gestalt factor of common fate ( 1 ) . For example , an animal that is perfectly camouflaged as long as it remains still , will pop out as soon as it moves . Motion can tie together stimuli that are widely distributed over the visual field , by this overriding proximity and similarity as perceptual grouping factors . Even when the objects around us are stationary , their images on the retina can move , because the eyes and head are never entirely still . It is therefore not surprising to learn that separate visual subsystems exist that are specialized to process motion as there are subsystems mediating the perception of brightness , form , or color ( 2 - 4 ) . Another aspect of motion is that it is closer than any static stimulus dimension tied to motor action . Motion signals a change in the conditions of the environment , and change may require reaction . It may mean the approach of danger or of a desirable target . If we just consider the motion of a single object we can distinguish absolute from relative motion . Absolute motion perception refers to the case of an object which is seen in an otherwise homogenous field ( Ganzfeld ) , or in a field in which the object is so far removed from other objects that their presence does not affect its judgement . The other , much more common , form of motion perception may be termed relative motion perception . It arises when the observer judges the motion of one object in reference to the position of other objects in her or his visual field . This chapter will focus on the basic conditions of visual motion ( mostly of single objects moving in the frontoparallel plane ) rather than on more complex forms of multi - element motion as represented by optic flow fields , biological motion , random - dot motion , motion perspective or motion parallax ( 5 - 7 ) . Motion is a spatio - temporal event , defined as a change in spatial location over time . Target motion , thus , does not only convey dynamic properties such as direction and velocity , but also static spatial properties such as position and distance . For example , an observer can determine the position of a moving target at any given moment which may be indicated by an auditory signal ( 8 ) . The distance information under kinetic conditions might resemble but also differ from that under static conditions , as has been demonstrated , for example , with kinetic versions of geometrical - optical illusions ( 9 ) or with a distance - analog of Runeson ' s velocity effect ( 10 ) . Retinal image motion can result from displacement either of the object relative to a stationary environment , or of the observer relative to a stationary object . Both object and observer can also move together . All these conditions cause changes in the pattern of stimulation at the retina , but despite these we retain an appropriate representation of both our position in space as well as that of the object . Occasionally , errors do occur in our perception of motion , and these can be very instructive in understanding the nature of motion perception . For instance , illusory percepts of motion can arise from static patterns . Striking examples of apparent motion arising from a stationary black - and - white patterns are given in Fig . 1 . Most observers see a " sliding motion " of the inset relative to the surround . When the figure is slowly moved , the inner disk appears to float relative to the concentric annulus . Eye movements cannot account for this illusion , since it persists in stabilized vision where apparent motion is perceived not only for the disk , but also for the ring ( 11 ) . This illusion is an example of intrafigural apparent motion ( 12 - 13 ) and is possibly based on the modulating activity of slow hyperpolarizing potentials of " configural units " in cortical area V4 ( 14 ) . Not only do we perceive a structured meaningful world , but we see it composed of distinct objects some stationary , others moving in various directions at different rates of speed . An initial answer that one might think of is that changes in displacement of an image on the retina are detected . In fact , many cortical cells are sensitive to motion across the retina and thus could signal such changes . However , a problem arises with this simple account if you consider self - motion of the observer in the environment ( 15 ) . Changes in retinal location can be due either to objects moving in the environment or to movements of the observer . How the perceptual system resolves the locus of motion constitutes a primary problem of motion research ( 6 ) . AFFERENT AND EFFERENT MOTION SIGNALS If we keep our eyes fixed , motion is perceived by the successive stimulation of adjacent retinal loci ( afferent motion signals ) . Retinal image motion is , however , not the only condition of motion perception . When our eyes pursue a moving object , the retinal image of the pursued target is held relatively stationary on the retina . Nevertheless , we perceive motion . Thus , the perception of motion can be also based on a sensorimotor or efferent motion signals . Afferent motion processing relies on an inflow of visual motion signals based on retinal projections of object motion . Conversely , the efferent process infers motion from the pursuit movements of the eyes following a stimulus and keeping it fixed within the fovea ( Fig . 2 ) . The displacement of position on the retina is not sufficient to specify that an object is moving , because the displacement may be due to ( eye ) movements of the observer . Two theories have been classically proposed to account for the problem of how an observer ' s own movements are distinguished from motion in the world . The inflow theory supposes that the feedback from the muscles that control eye movements is monitored by the brain . The change due to the eye movements is then subtracted from the shift in location of the image on the retina . In contrast , outflow theory states that the motor signal sent to the eyes is monitored . A copy of this outgoing signal , which is called an efference copy or corollary discharge , is used to cancel the resulting movement of the image on the retina . This is achieved by a still hypothetical brain mechanism , a comparator , which is supposed to match the signals from the oculomotor centers with those from the afferent flow of images from the retina . Modern research favors outflow over inflow theory ( 16 ) . An initial evidence for outflow theory is that the visual world appears to move when you press on the lid of the eye with a finger . In this case , movement is incorrectly seen because there is no efference copy associated with the commands of the eye muscles to indicate that the eye moved . Furthermore , it has been shown that such apparent movement can occur even when the eye actually remains stable on a fixated target , with the eye muscles providing force to prevent the finger pressure from moving the eye ( 17 ) . In this situation , illusory motion is seen because there is an efference copy but no movement of the eye . Further evidence supporting the outflow theory comes from studies in which an observer ' s eye muscles were temporarily paralyzed . When the observer tries to move her or his eyes ( which do not actually move ) , the scene appears to move to a new position ( 16 , 18 ) . A comprehensive functional model which supposes a reference signal that combines oculomotor information ( efference copy ) with optokinetic - vestibular information about head movement has been worked out by Wertheim ( 19 ) . The reference signal encodes how the eye move in space rather than in their orbits . It is matched with the retinal signal in order to distinguish percepts of object and ego motion in space . Wertheim ' s model can especially account for the loss of position constancy , the Filehne illusion , occurring during pursuit eye movements . There is experimental support for the model ' s predictions on how to manipulate the optokinetic ( visual ) input to change the strength of the Filehne illusion , or even invert it ( 20 - 21 ) . According to these and other findings ( 22 ) , the optokinetic pattern must be large , not move too fast , and remain visible for some time in order to ensure perceptual constancy . Although Wertheim ' s model addresses smooth self - motion and continuous eye movements , it may be extended to ballistic bodily movements and saccadic eye movements as well ( 23 ) . REAL OR OBJECT MOTION Real or object motion means that an object is continuously displaced from one point in the outer space to another . Object motion can cause a corresponding retinal image shift , if we keep our eyes fixed . It is , however , also perceived with pursuing eyes , although in that case the image of the moving object remains stationary on the retina . Both modes of motion detection are often intermixed , for example , motion across the retina provides the stimulus for initiating pursuit eye movements . Much of the research on real motion has focused on determining the factors which influence our threshold for motion perception under steady fixation . People are good at discriminating motion as a function of changes in retinal position . Motion can be seen if a small dot moves against a stationary background at speeds as low as 0 . 2 degrees of visual angle per second ( ° / s ) . Motion sensitivity is even greater if a stationary visual reference point is present ( 24 ) . In such situations , changes as little as 0 . 03 ° / s produce a motion percept . An important difference between afferent and efferent detection of object motion is perceived velocity . A moving object seems to move more slowly when it is pursued with smooth eye movements than when it is observed with fixed eyes . This phenomenon , known as the Aubert - Fleischl effect , may be due to an efferent underregistration of the eye velocity ( 25 ) . Jung ( 26 ) has pointed out the fact that angular displacement differs for afferent and efferent conditions ( see Fig . 2 ) . The angular displacement of the fovea is smaller , if it follows a moving object ( Fig . 2b ) than the angle of a retinal image shift produced by the same moving object ( Fig . 2a ) , because the eye rotates around an axis through the center of the eyeball . This difference in angular extent alone , however , cannot sufficiently account for the Aubert - Fleischl effect , since it has been found to depend also on other factors such as spatial and temporal frequency of the stimulus pattern and circular vection ( 19 , 27 ) . Models of motion detection first addressed the problem how the visual system might extract information from the stimulus on the retina , i . e . afferent conditions , were based on the visual system of insects ( bees , flies ) whose eyes are fixed on the head . The well - known motion - detection models by Hassenstein and Reichardt propose a bilocal delayed - coincidence detector based on bidirectional cross - correlation ( 28 ) . This can serve to understand afferent motion detection in humans as well . However , as pointed out by van de Grind , Koenderink , & van Doorn ( 29 ) , human bilocal detectors must be unidirectional correlators to ensure that we can cope with motion transparency ( i . e . , the simultaneous perception of motion in different directions and layers of depth ) . Van de Grind ' s model is depicted in Fig . 3 . A succession of images produced by a moving object shifts across the retina . The motion thus registered is due to the sequential activity of receptors in the path of the shifting retinal image feeding into bilocal delayed - coincidence detectors , i . e . into neuronal units most likely of the primary visual cortex ( gobal motion detection ) and of other secondary visual cortex - representations , namely to medial temporal ( MT ) area and to the medial superior temporal ( MST ) area ( 27 , 31 ) . Those detectors are tuned to a given velocity S / T , where S is the span between two receptive fields on the retina and T the delay . A two - fold coincidence unit ( C2 ) receives the input from both fields and multiplies them together . The coincidence unit responds optimally when the same pattern of light strikes first the region sampled by F1 and then , some time ( T ) later strikes the region sampled by F2 . One good stimulus would be an image that moved continuously across the retina from left to right . It is important to realize that this is not the only stimulus that would work . For example , a stationary light flashed briefly on F1 and after T on F2 should be as effective . We will see in the next section that indeed such nonmoving ( stroboscopic ) stimuli dupe the visual system into treating them as though they had moved . Thus , the basic idea in this model is that a relatively precise temporal coincidence of the signals from the subfields is required at the multiplier if it is to generate a response . It should be noted that the delay box in Fig . 3 should not taken literally to mean that this box represents a separate neuronal unit ; the delay could be as well a functional part of " filter " F1 or be in addition reflected by the " multiplier " C2 ( 29 ) . APPARENT MOTION The term apparent motion refers to any motion percept occurring when there is no real or object motion corresponding to the percept . Apparent motion comprises various phenomena such as stroboscopic motion , induced motion , autokinesis , the Filehne illusion , and motion aftereffects . Stroboscopic motion The most prominent example of apparent motion is stroboscopic motion so that one often finds the term apparent motion just referring to this form of motion . Stroboscopic motion consists of discrete , successive changes of stimulus positions which lead to the perception of continuous motion . It is the basis for perceived motion in movies ( cinema ) . The fact that we perceive smooth motion from motion pictures conveys the power of this form of apparent motion . Much work on stroboscopic motion has been conducted with simple displays . It can be demonstrated by just two stimuli ( see Fig . 4 ) . As the light in position A flashes on and off , the light in position B flashes off and on , i . e . one light is onset shortly after the other is offset . If the spatiotemporal stimulus conditions are appropriate one perceives motion across the intervening space between A and B in the direction from A to B , i . e . , a single light is seen moving through the empty space between A and B . According to Wertheimer ( 1912 ) who first systematically investigated stroboscopic motion , we can distinguish several stages . If the time interval is too short leading to a high rate of alternation , simultaneity rather than apparent motion is seen , i . e . , two lights are perceived flashing each at a different location . With increasing time interval , the percept changes to partial moving and " pure motion " ( phi phenomenon ) to optimal motion . If the time interval is further increased , only succession will be perceived - two light alternately flashing . Apparent motion can be obtained over separations of 10 ° and more ; with increasing spatial separation the temporal interval that produces optimal motion needs to be increased as well . Strictly speaking , the term phi phenomenon should be reserved for the illusion that motion is taking place without noticeable object displacement ( 33 ) . But nowadays it is often used for all forms of stroboscopic motion and strict phi is sometimes referred to as ' pure phi ' . This occurs at time intervals somewhat shorter than that necessary for optimal stroboscopic motion : one sees only two objects at their terminal positions , yet there is a clear impression of motion from one place to the other . For Wertheimer ( 32 ) this meant that motion is just as immediate and direct a datum of experience as color or brightness ; it can be perceived under appropriate conditions in a pure form , analyzable no further - an experience of sheer , objectless motion . Further forms of stroboscopic motion have been distinguished and labelled alpha , beta , gamma , and delta motion ( 13 ) . Alpha motion refers to the case in which a line or figure is seen to expand or contract when stimuli of different sizes are presented stroboscopically . Beta motion is a synonym for optimal apparent motion , i . e . , if the duration of each exposure and interstimulus interval are adequately adjusted , the appearance of motion is indistinguishable from that of a stimulus genuinely moving , hence the term optimal . Gamma motion describes the percept that a light expands for a brief time after coming on and contracts briefly when it is extinguished . Delta motion occurs when two successive stimuli are only slightly displaced from one another and the second is more intense than the first ; then the second stimulus appears to move to the first . An easy way to experience the phi phenomenon is be produced by holding a finger close enough to the eyes that double images are seen and then alternately opening and closing the two eyes : The finger seems to leap from one place to another , but no image moves across the space . INDUCED MOTION , AUTOKINESIS Stationary visual context , a condition mentioned before to increase motion sensitivity can also lead to illusions of motion . In such cases , motion is attributed to the wrong part of the visual display , for example , when the moon is seen racing through the clouds on a windy night . The moving clouds induce motion of the quasi - stationary moon ( 34 ) . Another example of induced motion is the experience that our train starts moving while actually another train leaves the platform . When the induced and inducing objects are in close spatial proximity , the effect is referred to as motion contrast ( see section 6 ) , whereas induced motion typically refers to conditions in which test and inducing objects are spatially separated . An easy experimental demonstration of induced motion is a luminous stationary dot presented inside a large , luminous diamond or circle in a dark room ( 12 - 13 , 34 ) . When the circle is displaced ( steadily moved or successively presented at two positions ) , it is the dot that will normally be seen to move in opposite direction ( Fig . 5 ) . Under both real and stroboscopic motion conditions , one of two stimuli needs to be larger , enclosing the other . If the larger stimulus is moved , all or at least part of its motion is attributed to the smaller , enclosed stimulus . The enclosing figure is presumed to serve as a frame of reference relative to which the smaller stimulus is displaced ( 25 ) . The fact that smaller objects are more likely to move relative to larger and enclosing stimuli might reside on ecological constraints to our perception . Usually small objects move whereas larger objects , for example , walls , trees or fields in our environment are stable . Induced motion is not restricted to linear paths . For instance , a patterned stationary disk can be induced to rotate by the rotation of a surrounding concentric patterned annulus ( 34 - 35 ) . A number of stimulus variables can be identified that reduce or promote induced motion . For example , induced motion diminishes when the motion of the inducing pattern increases in speed ( 36 ) . Another critical condition for induced motion is that the frame that defines the background and the enclosed stimulus should be adjacent to one another , i . e . within the same plane and distance from the observer . If the surrounding field lies too far in front of or behind the enclosed target , induced motion falls off appreciably ( 37 ) . This finding points out the complex interrelationship that exists between motion and depth perception . Another example of apparent motion is called autokinesis . This refers to motion which is experienced when fixating on a stationary point of light in an otherwise completely darkened environment . It was first observed by Alexander von Humboldt in 1799 with respect to the apparent wandering of stars ( 35 ) . The key condition for autokinesis to occur is the lack of another visual reference or background , i . e . , absolute motion mentioned in the introduction . This spatial uncertainty makes the stationary light drift or wander irregularly after some time of inspection . Typically , the point of light appears to make small excursions , but considerable motion is sometimes noticed . Autokinetic phenomena reflect the role of eye movements and resulting efferent motion signals that produce the effect of apparent motion , especially in the absence of other visual cues that may serve as a spatial reference ( 38 ) . MOTION CONTRAST AND ASSIMILATION When two targets travel at the same speed against a field of dots that move with a horizontal gradient of velocity , the target which is traveling faster than its immediate surround appears to have a larger absolute velocity than the target which is traveling slower than its immediate surround ( 39 ) . This phenomenon reminds on brightness contrast and is analogously referred to as motion contrast ; it has been recently shown to rely likewise on lateral inhibitory interactions among specialized neuronal detectors ( 40 ) . Conversely , an example of motion assimilation has been reported by Bressan ( 41 ) . She obtained an analog of brightness assimilation ( seen in the Munker - White effect , Fig . 6a ) in the velocity domain . The stimulus display consisted of two sets ( separated by 9 . 2 ° ) of three horizontal rows each ( Fig . 6b ) . There were 11 dots in each row , at a distance of 1 . 5 ° from each other , and 0 . 6 ° separated neighboring rows within a set . Within one set of three rows , the dots of the first and third rows ( flanking rows ) had the same color and moved with the same velocity a . The central row consisted of three separate sections ; the dots of the left and right sections ( collinear rows , 7 dots each ) had the same color as the dots of the flanking rows and moved with velocity b ; the dots of the central section ( test row , 4 dots ) had a different color and moved with velocity c . The upper and lower sets were identical except for the fact that assignments of velocities to the contextual rows would always be reversed : so if flanking and collinear rows traveled respectively with velocities a and b in the upper set , they would travel respectively with velocities b and a in the lower set , and vice versa . Dots moved horizontally at a constant speed across the screen ; whenever a dot disappeared at one end of the screen a new dot appeared on the other end , producing a continuous stream of moving elements . Velocities a and b were fixed at 3 ° and 9 ° / s , respectively . The velocities of the test rows were varied across trials , and were either 6 ° / s or slightly more or less . Observers had to compare the apparent velocity of the two test rows and to report which row appeared to be moving faster . Under these conditions , the test row flanked by high - speed rows ( Fig . 6b , upper set ) looked faster not only when it actually was as fast as the other , flanked by low - speed rows ( Fig . 6b , lower set ) , but even when it was actually slower ( 41 ) . In order to be perceived as travelling at the same speed , the test - dot velocity in the upper set could be by at least 0 . 6 ° / s slower than in the lower set . MOTION ADAPTATION AND AFTEREFFECTS Prolonged inspection of a moving stimulus leads to a gradual decrease in perceived speed resulting from motion adaptation . For example , a slowly rotating spoke wheel viewed peripherally appears to slow down and ultimately come to an apparent standstill , although its physical speed is unchanged ( 42 ) . When the speed of the wheel is slightly reduced , the perceived rotation resumes , but now in the opposite direction . The subsequent effects of motion adaptation can be vividly observed if you stare at a waterfall for some time and then look at a stationary scene , for example , the adjacent rocks . The scene will appear to be moving upward . This is called the waterfall illusion and is a striking example of a motion aftereffect . A likely first explanation of the waterfall effect first proposed by Addams in 1834 was that the downward pursuit movements established in response to the water persisted when the eyes were turned to the rocks ( 43 ) . However , a similar aftereffect is obtained if you watch a rotating spiral ( Fig . 7 ) . If the spiral appears to shrink or recede during rotation , it will appear to expand or approach when the rotation is suddenly stopped . It is obvious that no sort of eye movements can account for the fact that an object seems to expand in all directions at once . Furthermore , as first demonstrated by Mach and Dvorák in 1870 ( 44 ) , it is impossible for the eyes to shrink and expand at the same time as do the seen afterimages when adapting to the rotation of two concentrically arranged spirals of opposite throw , see Fig . 7 . Even for the waterfall illusion , the eye - movement explanation is inadequate , since one can obtain the same effect , at least in part of your visual field , if one fixates a point at the rock at one side of the fall , in which case pursuit eye movements are excluded ( 45 ) . Motion aftereffects typically consist on illusory motion in opposite direction to previous exposure to continuous motion in the same direction . They provide evidence that motion perception is not merely bound on stimulus motion and indicate the dynamics of special direction - sensitive motion - units which are selectively adapted during stimulation . Cells that selectively adapt to the direction of motion have been found in monkey area MT ( 46 ) . When stimulated by a pattern moving in their preferred direction , these cells show a brief burst of excitation at motion onset , followed by a rapid decrease of the firing rate and finally an " off " response at motion offset that falls below the resting discharge which might be a correlate of the seen aftereffect . Electrophysiological and psychophysical correlates of the motion aftereffect have also been comparatively studied in man ( 47 ) . Interestingly , no motion aftereffect occurs following the stimulation of the entire retina by linear motion ( 48 ) . In this case , however , a displacement of sound opposite to the direction of visual motion adaptation can be observed , suggesting a cross - modal , visual - auditory aftereffect ( 49 ) . Motion aftereffects can also be obtained from ( and interact with ) induced motion ( 36 ) . These and other findings ( 50 ) indicate the existence of several different motion aftereffects , depending upon the site at which adaptation effects occur . These aftereffects may serve as a tool for investigation of putative adaptation sites and sensory mechanisms . MOTION AND SPACE : VELOCITY TRANSPOSITION The size of the target in proportion to the size of the background affects strikingly its perceived speed . This phenomenon is called velocity transposition ( 51 - 52 ) and can be regarded as a form of motion constancy ( 53 ) . It takes into account that the retinal image velocity , like retinal image extent , is inversely proportional to the distance of the imaged object from the observer . Velocity transposition can be demonstrated most simply by using two squares , each of which is moved behind a separate aperture with the size proportion of the squares and their apertures being 1 : 2 ( see Fig . 8 ) . Observes , asked to adjust the velocity of one display until it appears to match that of the other , typically give an equality match when the physical speed of movement of the large aperture is set at almost twice the speed of the motion of the small aperture ( 25 , 52 ) . This general effect of target size and its background on perceived speed has been recently confirmed and further elaborated by Ryan & Zanker ( 54 ) ; it also extends to motion extrapolation ( see section 9 ( 55 ) ) . Thus , perceived velocity of an object depends on the relation of object size relative to aperture size as well as on its physical speed in that it maintains constancy of an object ' s velocity despite variations in its distance and corresponding retinal projections . LINKING PERCEPTION TO ACTION : MOTION EXTRAPOLATION More than any other stimulus dimension , visual motion is linked to motor action . For example , when catching a ball we do not only perceive a moving object , but also most naturally extrapolate this perceptual information to allow for advance ( and hence successful ) specification of corresponding motor acts . Motion extrapolation ( with respect to the stimulus ) or motion anticipation ( with respect to the acting subject ) describes a performance of a relatively simple and most common task in daily life . This performance , although it transcends stimulus - bound or modal perception , is obviously directly ( perceptually ) present rather than a result of indirect cognition . Thus , extrapolation seems to be directly linked to perception with which it has been found to share common properties ( see below ) , and may hence be best considered as a form of amodal perceptual completion ( 56 ) . Sensory , modal , motion perception already entails some sort of short - term integration in sampling motion signals over time in order to derive a velocity estimate on which amodal ways of motion perception might be based in addition to higher - order integrative cognitive processes such as visuo - spatial forms of attention and working memory ( 57 ) . A typical motion extrapolation task consists of presenting a moving object that is " occluded " or " vanishes " en route while approaching another object or observer . The task then is to press a key to indicate when the initially visually and later virtually moving object reaches the observer or the other object . For various conditions of motion presentation , linear regression is found to describe the individual performance of extrapolation ( 58 ) almost as appropriately as perceived velocity ( 46 , 52 ) . Motion extrapolation thus might be considered as a special , action - related , case of velocity perception . For example , Ehrenstein ( 59 ) used extrapolation of visual motion to compare the performance under afferent and efferent motion conditions ( see Fig . 9 ) . A bright dot moved horizontally over 12 ° at 6 ° / s and then disappeared . Subjects had to extrapolate the visual motion and press a key at the moment when the virtual motion reached at one of 5 extrapolation distances , marked by LED - pairs ( Fig . 9 , top ) . In one condition , subjects had to fixate the center of the respective LED - pair from motion onset until the key press ( afferent motion ) , in the other condition , they had to pursue the moving target with their eyes and , when it disappeared , direct their gaze to the given LED - position ( efferent motion ) . Linear regression analysis of the mean extrapolation times ( from motion offset to key press ) yielded a high correlation with extrapolation distance ( r = 0 . 99 ) in both conditions . Regression lines , however , differed in their slopes for both conditions ( Fig . 9 , bottom ) , indicating a slower extrapolation velocity for efferent ( 4 . 2 ° / s ) than afferent ( 5 . 2 ° / s ) motion conditions . This reduction in extrapolation velocity might be related to the above mentioned Aubert - Fleischl effect . The underestimation of perceived velocity of a moving object during ocular pursuit seems to extend on , or at least reflected by , motion extrapolation . 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Ehrenstein Leibniz Research Center for Working Environment and Human Factors , University of Dortmund ArdeystraBe 67 - D - 44139 , Dortmund , Germany email : ehrenst @ arb - phys . uni - dortmund . de © 2006 Conselho Brasileiro de Oftalmologia Alameda Santos , 1343 - 11º andar cj . 1110 CEP : 01419 - 001 São Paulo SP Brazil Tel : 11 - 3266 - 4000 Fax : 11 - 3171 - 0953

he most remarkable thing in a remarkable universe is so commonplace that it is accepted without wonder or understanding . This is the appearance of reality and solidity that surrounds us when our eyes are open , which we call simply vision . Intellectual effort is required to realize that this seeming reality is within us , distinct for each individual , but so concordant with reality and with each other , and so stable , that it is accepted without question . The explanation for this wonderful aspect of consciousness is completely unknown . The information that allows the mind to create and maintain this appearance is collected entirely by the visual system . When the eyes are closed , the appearance vanishes . At least , it does for me . Some people may be able to create realistic pictures with their mind ' s eye , but I cannot . I can still imagine my environment more or less accurately , but the vivid picture is gone . The ability to make an accurate visual model of the external world is learned , not innate . The necessary materials are there at birth , of course , but they must be trained , or programmed , before the skill is perfected . This seems to be done in the first instance by comparing the chaotic impressions of light with the solid evidence of touch , which gives the perception depth and form . The visual sense ever after shows subtle indications of its origin in touch , though it becomes completely independent of touch after perfection . The ability to acquire this skill vanishes early in mental development . A person totally blind from birth whose vision may become normal at a later age can never make sense of the visual information and arrange it in a consistent manner . The Chain of Perception There are three links in the chain of perception . The first is external and physical : the propagation of electromagnetic waves from the object to the eye . The second is the physical visual apparatus , from eye to brain , consisting of nervous tissue , although some important preliminary processing takes place . The third , and most complex , is the interpretation of the visual stimulus and the creation of the internal model of the world that is used by the consciousness . In the third step , the visual stimulus received from outside is combined with information from the memory to create the picture . This is the most important part of vision , and how it is done is unknown . All the really interesting parts of vision occur here . The physical visual system from eye to brain has been studied in exquisite detail , its parts examined and described , and even the nerve impulses observed and measured , but all this gives no satisfying explanation of vision . It has been established , however , that important preliminary processing takes place here , including the differencing and the coding of stimuli . Coding is necessary to reduce the flood of information to a manageable amount . The visual system has a bandwidth problem , indeed . The world picture must be constructed from incomplete information , in fact inferred from clues . The three - dimensional world is sensed by the two - dimensional retina , emphasizing the central role of depth clues . The picture depends on the unconscious recognition of objects , so that the remembered properties of objects can be transferred to those they seem to be on the basis of visual hints . Recognition is what gives vision its reality , showing the central role of mind . Illusion and Hallucination A picture so assembled on the basis of partial information must be expected to occasionally be in error . The mind will always try to match stimulus and memory to create a picture . It will make what seems to be the most likely choice , and present that to the consciousness . An illusion occurs when the choice is incorrect . If a picture is created solely from memory , without visual stimulus ( or with only a minimal visual stimulus ) the result is hallucination , with which we shall not be concerned here , since it is a disorder of perception , not a normal or intended part of it . Things that are not there can also appear in illusion , it must be emphasized , but here it is normal . An illusion can arise in any of the three links of visual perception . The mirage is an example of an external illusion , created in the first , physical link of light rays . It is visually interpreted as an actual scene , though we consciously recognize it as an illusion , and understand its cause . When we stare at a brightly illuminated red disk for a time , then transfer our attention to a white paper , we see a green disk as a result of what is called rather inaccurately fatigue . The green disk is an illusion created in the second partly physical , partly mental link . When the full moon is seen at the horizon , it seems much larger than when riding high in the sky , though physically it subtends exactly the same angle at the eye . This familiar illusion occurs in the third , mental link of vision , and a satisfying explanation of it is unknown . Optical Illusions Illusions occurring in the third link are those most generally recognized as optical illusions . Their scientific study began with J . Oppel in Jahresberichte des physikalisches Vereins zu Frankfurt , p . 138 ( 1854 ) . Much work was done later in the century , but tapered off after 1900 , although the subject is still actively researched by psychologists . Recent work deals largely with color and motion illusions , not on the static , black - and - white illusions that dominated earlier work . Popular interest in optical illusions has been sustained . The books by M . Luckeish ( Visual Illusions , 1920 ) , S . Tolansky ( Optical Illusions , 1964 ) , and M . Fineman ( The Nature of Visual Illusion , 1981 ) are evidence of the continuing fascination . Each of these books gives references to further information . All theories of optical illusion in the third link are mere jejune speculation . Feel free to create your own theories ; they will be as valid as those created by many a psychologist ! Sometimes a phenomenon is called an illusion when it really is not , but is simply a true picture of an unexpected observation . An example is the searchlight illusion described by Luckeish . The beam of a bright searchlight is visible because of scattering by dust and fog in its path , so that it seems practically a physical object . When the beam is projected up into the sky , it seems to vanish abruptly while still in full glory . When you look at this apparent end of the beam , you are looking in the direction in which the beam is pointed . If the beam were parallel ( as your mind expects ) it would , by perspective , narrow to a point . However , a searchlight beam is actually more or less divergent , fooling this expectation . It is only one ' s mental interpretation that is an illusion in this case , not the observation . Stars can be pointed out to others by means of a strong laser using this effect . If you view the searchlight beam from a distance , you see it diverge and become attenuated , and perhaps penetrating the layer of dusty air . Optical illusions are badly named , since they are not unreal perceptions , but just misjudgments or ambiguous ones . The visual sense does the best it can to interpret the scene around us , but sometimes it fails . Two of the most striking failures are the stereoscopic perception of solid form on viewing a stereopair , and the appearance of continuous motion in the jerky image sequences of cinema . Both are pleasurable and desirable failures . Let us consider some more subtle ones in this article . I recall with nostalgia and pleasure the many times I have watched a full autumn moon rise into the hazy evening sky over a wide eastern horizon . Its face is tawny , because the frequent inversions of autumn evenings hold the smoke of burning leaves close to the ground . She looks large , gigantic , larger than the trees and bluffs , or the houses and the highways . I think I should be able to see craters and mountains easily on the magnified disc , but I cannot . Sometimes even the familiar maria are hard to make out . The disc is round and seems perfectly circular , though I know it must be slightly flattened because of atmospheric refraction . As she rises , the haze is slowly left behind , and she becomes whiter and brighter , and the maria now look sharper . An hour or two later when I look , the moon is hard and bright and sharp , again in her normal celestial haunts after a visit to ours . What I have seen is called the horizon illusion , known and remarked from antiquity . The rising moon seemed four times as large as the moon in the zenith . At first it seemed close , almost an earthly thing , but later its celestial nature took hold . Ptolemy explained that this was only apparent ; the objective size of the moon was no different on the horizon than in the zenith . He said that although the celestial sphere was , indeed , a sphere , it appeared farther from the observer at the horizon , and bodies subtending the same angle appeared larger when presumed to be at a greater distance . A man at 1000 yards subtending the same angle as a man at 100 yards , would indeed appear to be a giant . It was the misjudgment of distance that caused the illusion . I feel that this explanation , though incomplete and unsatisfying , is still rather close to the best that can be said given our state of knowledge . There have been very many explanations and analyses of the horizon illusion , many which accept Ptolemy ' s foundation , and seek to understand why distances to the horizon are misjudged , and others that look for some different cause . In fact , there is a book on the horizon illusion , and it has been the subject of more scientific papers than any other optical illusion . I will direct the reader to this voluminous literature for a deeper study , and only make some comments on the basis of my own observations . When I see the moon near the horizon , it is clearly behind any objects I see there , clouds as well as houses and trees . Any object behind another is farther away and the moon is generally larger than anything else in sight in the distance . I do not know how strong the illusion is if , for example , the moon rises behind a uniform wall relatively close to me . I usually see it rising over vegetation and buildings . It looked remarkably large once when it rose behind a large office tower about a mile away , and was wider than that structure . The haze and creamy light help to make the moon seem a terrestrial thing , not the celestial body I know it is at a vast distance . The moon is , in fact , perceived as an earthly object , and in this guise can only seem gigantic . Constellations near the horizon share this expansion . I seldom have seen the moon setting in the west in the dawn , since I usually sleep until well after the sun is up . I have done so , however , and my memory is that the moon appears pale in the cool , clear air . It seems a celestial body , and its size may be a little expanded , but nothing like in the autumn evenings . The red setting sun appears quite large and flattened , larger than the dawn moon , and sunspots are not visible , just as lunar detail is not visible in the haze . In the clear air of Wyoming , the sun sets into the Laramie Range as a brilliant ball I do not look at . My impression from glances is that it seems hard and bright . I conclude that the illusion is variable in strength , strongest in hazy air with subdued illumination , weakest in limpid air with bright light , and is mainly due to an unconscious assumption that the disc is a terrestrial object . Some illusions are caused by ambiguity in the scene . In 1860 , Sinsteden noticed a remarkable thing about a windmill seen in silhouette towards the darkening evening sky of the west . This view is represented to the left . It is unclear whether the axis of the sails is directed away from you or towards you . The direction of rotation of the sails depends on which is the case . Sinsteden and I can , by a conscious effort , imagine the scene in whichever way we choose , and if we switch views , the direction of rotation reverses ! This remarkable illusion can be shown here through the magic of GIF animation . The absolutely exciting message of this illusion to me is that conscious thought can change the perception , reinforcing my view that mental processing plays the essential role in vision ; everything else is auxiliary . A couple of years earlier , Schroeder had published a static ambiguous figure , shown in the middle below . This is a very famous illusion , still often shown . The red surface can either be to the front of the figure , or to the back . In one case a flight of stairs is shown , in the other something less common , perhaps stairs seen from below . As in the case of the Sinsteden illusion , one can go from one interpretation to the other by an effort of will . There are many other such ambiguous figures , including the intaglio faces that can be seen as faces in relief . The drawing procedure called isometric projection is very subject to ambiguity , since perspective gives no aid . The figure on the left , due to Zöllner , shows the effects of contrast with the diagonal teeth on the parallel vertical bars . The bars seem anything but parallel ! The method of drawing this figure affects the strength of the illusion , and the form shown is one of the strongest . However , the illusion occurs to some degree however the short diagonal elements are drawn . This illusion shows an error in estimation . The lines tend to become more parallel if you concentrate on a pair of them , but there is always some tension . When I look at the figure with both eyes , I also get a stereoscopic effect , as if it were corrugated . A related illusion is shown at the left below , where it should be noted that there are no inclined lines at all . These patterns should certainly be avoided in decoration ! One of the most frequently mentioned illusions , called Poggendorff ' s illusion , is shown above at the right . His name was probably chosen either to honour him , or because he suggested it at one time or another to an investigator . It is fairly strong in the case on the left . The diagonal lines meet at the point where the left - hand side of the vertical bar is crossed , but the right - hand lines seem too low . It is usually presented as shown at the right , where the diagonal lines do not seem to be in the same straight line . The one on the right seems too low . This tendency has been taken into account in the Union Flag of the United Kingdom , where the red saltire of St Patrick is displaced so that it seems to be continuous on both sides of the cross of St George . This gives the flag a definite top and bottom , which those unfamiliar with it usually reverse . There are many variants of Poggendorff ' s illusion . Another illusion of the same kind as Zöllner ' s was constructed by Hering , and is shown above in two forms . The horizontal parallels are seen bowed outwards in the top figure , and bowed inwards in the bottom figure . Below are two more geometrical - optical illusions which came along later . In Bourdon ' s , the horizontal line seems bowed upwards . I do not perceive this illusion distinctly , but you may . Different people do not have the same responses to these illusions , again showing the intervention of the mind . In Loeb ' s illusion , the bottom of the two parallel lines on the right seems a bit higher than the top of the two parallel lines on the left , whereas in fact the two are in the same straight line . On the left below are two forms of the celebrated Müller - Lyer illusion , in which two lines of equal length seem unequal because of their surroundings . In both cases , the line ab is the same length as the line a ' b ' , which seems a little longer . On the right is an illusion due to Baldwin . The small cross is midway between the two discs , but the large disc seems to attract it a little towards itself . I do not find this a strong illusion . In the figure on the right , the vertical line is the same length as the horizontal line . You may find this difficult to believe , since the illusion is so strong , but measurement should convince you . This is called the top hat illusion , because it is often illustrated by a top hat , in which the crown is as high as the brim is broad , but looks much higher . This illusion gives clear evidence of the tendency to over - estimate vertical distances that makes hills ahead of us seem steeper , and valleys deeper , than they actually are . It is , of course , completely distinct from the horizon illusion with which this paper began , and the two are not related . Helmholz suggests sketching squares freehand and then measuring them to see how strong the illusion is . My squares tend to be rather square , but there seems to be an overestimation of about 1 part in 20 . The figure at the left , called the Kanisza square , shows that the impression of a square in front of the four circles is one way the mind interprets the picture , which is really just four circles , each with a quadrant removed . The square is not strongly or irresistibly perceived , the mind only offering it as a probable explanation for the figure . You may notice that the mind may supply ghostly edges to the square to separate it from the background . This figure was used in recent research with infants ( Science , around November 2000 ) to find out the age at which different elements are combined to form a recognizable object . The age was determined as about 7 months after birth , on the basis of brain activity recorded electrically . This demonstrates yet again that perception is learned , not innate . Other classes of illusions are concerned with contrasts in illumination , irradiation , and very frequently , with colour . Some of these have physical explanations , but most still involve mental processing . A practical reason for studying optical illusions is to understand how to counteract their unwanted effects . In classical Greek temple architecture , columns were expected to look evenly tapered , and architraves straight and level , to an observer standing before the building . However , columns appear slightly concave , and the architraves appear to sag . Therefore , columns were deliberately made slightly convex , an effect called entasis , and architraves slightly bowed , to counteract this tendency . The displacement of the saltire of St Patrick in the Union Flag is another example . Classic Static Illusions Let ' s look at some classic static illusions created by black - and - white figures . All are third - link illusions resulting from a failure of estimation , or from the faulty comparison of distances or objects . In the bisection illusion , the vertical line is the same length as the horizontal line it bisects , though it seems about 25 % longer . The illusion persists if the figure is rotated 90 ° , so it is not due to asymmetry of the retina , as one witless psychologist asserted . In the Müller - Lyer illusion , the line is bisected by the center arrowhead . The segment with the diverging wings appears longer , but it is not . In the annulus illusion , the area of the central disk is equal to the area of the annulus surrounding it , though it appears greater . Distance b - c in the lozenge illusion is equal to distance a - b , though appearing significantly longer . In the curvature illusion , all three arcs have exactly the same radius of curvature . Poggendorff ' s illusion is very famous . Line 2 is actually the continuation of the line on the left , although line 1 appears to be . This illusion is counteracted in the British Union Flag by displacing the arms of St . Patrick ' s cross on either side of St . George ' s cross so they appear to be in the same line . Greek temples were designed with deliberate distortions to make the building appear correctly . Columns were given entasis , a slight swelling in the middle , so they would look straight , and architraves were cambered up slightly in the center so they would appear straight . Modern buildings are not so sensitively designed . There is no satisfying explanation for any of these illusions , or even of the reasons why they should exist . Depth clues are not involved in any of them , at least obviously , or ambiguous or incomplete information . They can , however , be recognized and classified , and have some practical application . Ambiguous Figures Sometimes a view may not contain enough information for the mind to make a conclusive interpretation . Where there are only two reasonable interpretations , the mind may alternate them , as if unable to make up its mind . The rate of alternation gives some idea of the length of time between reconsiderations of input data by the visual system , or of the operation of the short - term memory that is so necessary to avoid overload in the face of the flood of information bombarding the mind . In the ambiguous figures shown , the one on the left can be interpreted either as an open book , or as a folded card with the fold towards you . The cube can be interpreted either with the diagonal line in the lower left - hand corner out of the page , or behind it . Vision is not really fooled here ; there is simply insufficient depth information for a conclusive choice . Modifying the figures to give better depth clues , as shown , makes the interpretation unique . In one case , the figure was made to resemble a definite object , an open book , and in the other hidden lines were removed to make the cube appear solid . Other Optical Illusions Illusions can also arise from contrast of brightness , as the perception strives to maintain line and shade . The well - known illusion shown at the right is an example . There are gray patches at every crossing , except for the one you are looking at directly . This effect is something to avoid when designing linoleum . Illusions of motion and color are difficult to illustrate in text , and are so extensive as to require individual study . Color can be perceived in a rotating black - and - white disc of suitable pattern , which is probably due to different fatigue characteristics of the color - sensitive proteins in the cone cells of the retina . Many color illusions are due to physical causes , because of the poor spectral resolution of the eye , and differences in illuminants and pigments . Adaptation , where the ambient illumination comes to appear as white as possible , and color constancy , where colors are interpreted similiarly under different conditions of illumination , are fundamental and useful properties of the color sense , not illusions . Illusions and Binocular Vision Stereoscopic binocular vision is a remarkable facility that provides many interesting illusions , mostly useful and entertaining ones . When both eyes are fixated on the same nearby object , the images on the two retinas are not identical and conflict , since each eye sees the object from a different position . Detecting the conflict , the mind checks to see if the conflict can be explained by the different positions of the eyes , and if so , immediately interprets the object as located in the proper position in space . The two images are then said to have fused . Of all depth clues , the mind regards stereoscopy as superior , overriding all other clues . Stereoscopic vision is most effective in the same regions as human hands work , and must be considered predominantly as an aid to such activities . Accommodation and convergence of the axes of vision may play a part in stereoscopy , but image conflict is the primary cause , as was realized by Charles Wheatstone , the first to study stereoscopy around 1838 . When the conflicting images cannot be explained in this way , rivalry occurs instead of fusion , resulting in rejection of one image , alternation of images , or double vision . When sufficiently addled by alcohol , the mind may not feel like exerting the effort required for fusion . When the image in one eye is markedly poorer than the image in the other , it is usually suppressed , and the image from the good eye governs . If red is presented to one eye , and green to the other , rivalry results , in my perception , in an intermediate state than cannot be described as either color or any mixture of them . This allows stereoscopic views to be presented to the eyes separated by colored lenses without color conflict . The stereoscopic illusion is the fusion of two scenes presented separately to the two eyes into one three - dimensional scene . The feeling of three dimensions is very strong , so that viewing such stereopairs is quite pleasant . When the two views are printed on a page about 65 mm apart , a normal interocular distance , a trained observer can fuse them by simply diverging her optic axes as if viewing a distant object . When this is done , the fused image appears between the two original images , so three images are actually seen . This is more easily done by the older observer , since accommodation of the eye does not hinder fusion when the axes are diverged . To allow larger stereopairs , and to help untrained observers , stereoscopes using prisms and lenses were invented . The common stereoscope was invented by David Brewster , and has now been reduced to spectacles with prism lenses . If the two scenes are presented in different colors , they can be printed on the same surface and separated by glasses with colored lenses , as mentioned above . Such stereopairs are called anaglyphs . The strength and independence of the stereoscopic facility is shown by the lately - discovered fact that it is fully effective even when an object cannot be recognized , provided only that corresponding points can be identified in the two views . A stereopair can be made with random dots , identical except for small displacements that would occur if they were located on a three - dimensional surface . Such pairs can be fused , and the shape of the imaginary surface made visible in three dimensions . This clearly shows that memory plays no essential role in stereoscopy , in contrast to the major role it plays in all other visual interpretation . Autostereograms A related type of stereogram consists of cunningly arranged areas in a single picture , often only small dots , such that each area does double duty , as a point of an object for each eye at the same time , but on different objects . These stereograms fuse when the optic axes are made parallel , so the areas do their intended double duty . The picture appears only upon fusion , and cannot be perceived in advance . The same thing happens if the optic axes are over - converged , but the stereoscopic effect is inverted ( depth is reversed ) . These single - image random - dot stereograms are generally called autostereograms . These stereograms attracted great public interest in the early 1990 ' s , when they were published in newspapers and books , and even appeared in outdoor advertising . Viewing autostereograms is excellent practice for learning how to fuse stereograms without aid , called free fusion . Camouflage Tricking the eye into recognizing one thing while observing another is often very useful to living things . There are three different ways to do this . First , one might mimic something dangerous or nasty - tasting , as does the fly who resembles a wasp , a brightly - colored butterfly , or an armed , uniformed policeman . Another way is to merge with the background , as do moths , stick insects , tabby cats , or wealthy people wearing old clothes in the street . An interesting way to do this is to break up a familiar outline by a contrasting pattern . Warships were painted in bold , zig - zag patterns in the First World War for this purpose . The patterns did indeed break up the outline when you were close enough to see that they were ships , but at large distances aerial perspective ( blue haze ) smoothed the pattern , revealing again that they were ships . The third way is to look like something else . Cylindrical snakes and lizards are dark on top and light on the bottom , contrary to the normal modelling of a cylinder , so they resemble flat objects containing no meat . Deliberate Illusions A picture drawn on a flat background is an attempt to trick the eye into perceiving a three - dimensional scene . This is very effective , since the eye must do something similar in its normal functioning , becauseerful is perspective drawing . In moving pictures , the mind interprets the succession of static frames as continuous motion , again something it must do in its normal functioning . There must be a temporal element in sensing a changing world , which is revealed by the flicker frequency , the rate above which continuous motion is perceived instead of jumps , of about 20 to 30 Hz . We are very thankful for these illusions ( if we realize what they are ) and are glad to have them . Conjurors , three - card monte men , swindlers , mediums , priests , and others interested in influencing people sometimes make effective use of visual ( and other ) illusion . Stage magicians who are only concerned with entertainment call themselves illusionists to make it clear what they do , and to distinguish themselves from those who ascribe their wonders to spirits or chemicals . Illusionists , and the the other sorts of entrepreneurs , mainly use other kinds of illusions , but optical illusions are not ruled out . These procedures have been perfected through centuries and even millenia of profitable use , and remain evergreen owing to the continuous copious production of fools . Final Remarks A curious illusion shows how the mind does its best to interpret its data . Fixate on a finger resting on a book at normal reading distance from your eyes . Now move the finger toward your eyes , keeping your fixatin on the page of the book . As soon as your finger is far enough from the page that what is obscured from the right eye is seen by the left , and vice - versa , it will become transparent , and you will see the book unobstructed by the finger . The finger is surely there , right in the way , but it is suppressed , probably because your fixation shows you are looking at the book , not the finger . Illusions show that visual perception is much more complicated than was ever imagined in primitive views of it . One early view interpreted sight as touching by visual rays from the eye in the presence of activating rays from the source of light . More recently , the eye was perceived as a camera making a picture that was viewed somehow by the brain . The most interesting aspects of vision are , however , yet unexplained . References M . Hershenson ( editor ) , The Moon Illusion ( Hillsdale , NJ : Lawrence Erlbaum Associates , 1989 ) shows that the horizon illusion has not lost its fascination . Note the title , which may lead the unwary to assume that it deals only with the moon . For a bibliography of work on optical illusions up to 1924 , and especially the horizon illusion , see H . v . Helmholtz , Handbuch der Physiologischen Optik ( New York : Dover , 1962 ) vol . III , p . 364 - 369 . M . Luckeish , Visual Illusions ( New York : Dover , 1965 ) . A reissue of the original of 1915 . A good survey , and widely available . S . Tolansky , Optical Illusions ( Oxford : Pergamon Press , 1964 ) C . H . Paraquin , The World ' s Best Optical Illusions ( New York : Sterling Publ . Co . , 1987 ) M . Fineman , The Nature of Visual Illusion ( Mineola , NY : Dover Publ . , 1981 ) To Know more Eyetricks . com - site devoted to optical illusions , 3D stereograms , online games and other mind - teasing oddities . The Principles of Artistic Illusions - from Escher to Penrose to Thiery and more . Visual Illusions Gallery - presents illusory stimuli , with added hypertext and graphical material relevant to students studying sensation , perception , or research methods . The Senses : The senses have common properties and origins The Eye and Visual Perception : How vision works Stereopsis : 3D from Wheatstone to the Autostereogram Anomalous Colour Vision : Why some people have different color perception Haidinger ' s Brush : The Eye Is Sensitive To Polarization The Horizon Illusion : A Clear Explanation Is Still Lacking The Searchlight Illusion : An Error of Interpretation Amazing Optical Illusions - pick your favorite optical illusion Optics and Visual Perception The Author James . B . Calvert Associate Professor Emeritus of Engineering , University of Denver , Denver , CO , USA . jcalvert @ du . edu This paper is a composition of two original papers published by Dr . Calvert in his site :

Antônio Luís de Miranda Ferreira e Denis A . Daniel - Coordenadores With each new year begins the round of planning for the Rio Legal Committee s ( RCL ) calendar of activities , covering lunch - time talks , articles , newsletters , workshops , seminars and events , both national and international . In 2006 the RLC faces a double challenge ; as well as planning for a successful year , a handing over of roles is due to take place . The transition we are speaking of is that of the Presidency of the Rio Legal Committee , which Dr . Denis Daniel initiated six years ago with the first luncheon meeting on January 27th 2000 . The new incumbent is Antônio Luís de Miranda Ferreira , partner of the Machado , Meyer , Sendacz e Opice Law Offices and former Legal Director of Shell Brasil . The challenge of the RCL has always been to combine topical , interesting issues with speakers from all walks of the legal profession , who can variously shed new light on the subject at hand , succinctly sum up the differing points of view , and through their experience bring a wider legal , political or historical perspective to bear . Top speakers and relevant topics , brought together within a framework stamped with British punctuality ( always 12 : 15 p . m . to 2 : 00 p . m . ) , have guaranteed that RLC participants come to the meetings in the knowledge that they will be educated , entertained , watered and fed and subsequently dispatched back to their business within a predictable timeframe . A centralized downtown location permits most participants to dispense with motorized transport . The lunch - time talks serve as the primary source for the RLC Newsletter , which appears as a bilingual pull - out in every Britcham magazine . Back issues of the RLC Newsletters are to be found on the Chamber s official website or available from the Chamber Office . Some of these articles , which also include comparative studies , have covered topics such as Binding Decisions , Foreign Law Firms in Brazil , Protection of Minority Shareholders in Britain and Brazil , The Crime of Unlawful Tax Demands , Mediation - How to Avoid Court Disputes , Lawyers Being Sued by Clients ? , Simple ( limited ) Companies and the New Civil Law , Banking Confidentiality under British and Brazilian Law , Preventative Injunction , Contracts and the New Civil Code , Reform of the Judiciary , The ISS and the Liberal Professional , Current Status of Public Private Partnerships , The Role of Legal Departments in Major Corporations and the Relationship with Outside Counsel , The Reform of the Judiciary and the Role of the Lawyers in the Advancement of Decision Rendering , and The New Legal Directives of the Regulatory Agencies . The RLC has provided and will certainly continue to provide a forum for prominent legal professionals to meet . One of the main objectives of the RLC is to offer informative , stimulating and useful events relating to British and Brazilian legal matters that could be of interest to lawyers and to members of the Chamber as a whole . A further aim is to make known to Chamber members the representatives of law firms in Rio that specialize in different areas of practice . A further stimulus for participants of the RLC meetings is that articles produced by lawyers are placed on the Britcham site in the RLC section . Members can refer their clients to the site , where they will find legal opinions showing tightly reasoned arguments and sometimes hard - hitting conclusions . In 2005 the RLC focused on major issues such as Public - Private Partnerships ( PPP s ) , Bankruptcy Law and other topics that are of interest to the law profession and to the business community at large . The same year also saw the beginning of a series of legal workshops of an essentially technical / educational nature . These are short workshops of three to four hours , usually held in the morning and have proven to be very useful for the developing of junior staff in law firms in Rio . In 2006 the RLC will continue to follow the successful formula of lunch - time talks and technical / educational workshops , focusing on major legal issues . Special attention will be given to legislation reform and development , mainly taking into account the themes that will certainly be part of the political agenda of the new government to be inaugurated at the beginning of 2007 . In this sense , the possibilities of the RCL to serve as a permanent forum for the relevant discussions will be explored . The RLC has counted and will certainly continue to count on the efforts and dedication of its members , a brilliant group of lawyers and professionals from various areas that have been fundamental for its development . To all of them the RLC credits the high quality of the events , the most enjoyable and friendly atmosphere and the prestige that has been achieved by the Committee amongst the legal community in Rio .

E lectrostatic machines are electromechanical devices that produce " static electricity " , or electricity at continuous ( DC ) high voltage . They were fundamental in the early studies about electricity , started in the XVII century , in the form of " friction machines " , and their development culminated at the end of the XIX century with the development of powerful " influence machines " . Today , some specialized uses for them continue to exist , but they are mostly seen as demonstration devices in physics laboratories , with much of their history forgotten . I started experimenting with these machines by 1973 , building a first series of machines . With this I learned a lot about electricity , and I still think that all people interested in electricity or electronics shall try these machines to get a real feel of the subject . At least , high voltage static electricity is something that you can see and feel . Eventually I abandoned the subject for several years , but in 1996 I renewed my interest in this subject , started to study and build new machines , and set up these pages . Below are pictures and descriptions of my old machines , of machines that I built more recently , of machines built by others , pictures from old books and papers related to electrostatic machines and other high - voltage devices , and also some pictures from museums . There are also extensive references , covering classical and new materials . This site is always in construction . I plan to add more details about the machines depicted and historical material , as soon as I find or receive more data from interested people , build and experiment with new machines , and have time . Está também disponível uma seção em português . To navigate through this site efficiently , use the " open link in a new window " function of your browser to see the pictures in the links , and use its search function for searching . Recent changes . " Ignis ubique latet , naturam amplectitur omnem " Machines of Toepler , Bonetti , Voss , Bohnenberger , and Nicholson My machines A Wimshurst machine [ 1 ] [ 2 ] that I built in 1974 . Front view , back view , and with two Leyden jars . A schematic diagram , with the disks represented as cylinders , and a description of how the Wimshurst machine works . A Ramsden friction machine [ 2 ] , built in 1975 . Small ( 18 cm acrylic disk ) , but useful to test the insulation of materials and for for starting the influence machines in humid days . A Lebiez machine , or simplified Voss machine [ p31 ] , in front view and in back view . Built in 1975 as a kind of Voss machine , and rebuilt in 1996 in this form . Schematic diagram , with cylinders instead of disks for my machine . This machine is equivalent to Lord Kelvin ' s " replenisher " ( see below ) , with better insulation . The classic Voss machine , also known as Toepler - Holtz machine , is better and is built in this way , with charge collectors and inductor plates separated . A possible similar true Voss machine is shown here and here . A small cylindric simplified Voss machine built in 1997 , with the same structure of the previous machine . Side view , and another view . It is similar to a Dirod machine [ 10 ] . A symmetrical 2 disks Toepler machine [ 4 ] , with some modifications , built in 1997 . Side view , another view . A drawing . A schematic diagram , with the disks shown as cylinders . This machine has excellent performance , and can generate higher voltage and even more current than a conventional Wimshurst machine with the same disk size . In 1999 , I built a larger machine . Look at the bottom of the page here for a description . The first classic Toepler machine ( 1865 ) was built in this way [ 4 ] [ 9 ] , with a different interconnection and disks with two sectors only . Toepler described also a symmetrical machine ( 1866 ) that is very similar to my machine ( the picture shows a sectorless machine and a similar device used as voltage multiplier ) . schematic diagram [ p39 ] . My first sectorless Wimshurst machine , or Bonetti machine [ 4 ] [ 5 ] [ 8 ] ( ray - tracing drawing ) , built in 1997 , with 31 cm disks . A drawing . Another view . Pictures of the actual machine , in front view , and back view . A detail of the charge collectors and neutralizers . Pictures ( video frames ) of sparks from this machine : A short spark , a long spark with a loop , and a longer one . The original Bonetti machine ( 1894 ) [ 31 ] used series of brushes as neutralizers instead of combs . A Holtz machine [ 2 ] [ 4 ] - [ 7 ] of the first kind , that I built in 1997 . A drawing . Another view , and a schematic diagram . Pictures of the actual machine , in front view , and back view . This machine was the first really powerful influence machine , invented in 1865 , and was very popular , even requiring external excitation to start . An apparently complete actual machine is here . Some additional pictures , from books by H . Pellat : A Holtz machine [ 6 ] ( the fixed disk is in a wrong position ) , a better picture [ 7 ] , a double Holtz machine [ 6 ] [ 7 ] , and a machine with neutralizer and friction starter [ 6 ] [ 7 ] . And another good picture [ 14 ] . This picture shows a machine with a more modern structure [ 22 ] . A multiple machine [ 24 ] . Here is a picture of the Holtz machine of the second kind , that uses two counter - rotating disks , as the Wimshurst and Bonetti machines . A drawing of a possible machine . The Leyser machine ( 1873 ) [ 4 ] [ 19 ] , is variation of the Holtz machine with the output taken at positions that would be under the inductor plates in the regular machine , and the neutralizer bar where the original output circuit would be . This is the schematic diagram of the machine , with a cylinder instead of the disk . This is a different design due to Weinhold ( 1887 ) , with wood inductors and no insulating plate [ 19 ] . This diagram [ 19 ] shows how it operates . Initial plans for a machine that I have built are here , in front view and back view . The version that actually worked was somewhat different . A double Voss machine , or double Toepler - Holtz machine , with classical structure , built in 1998 . A drawing , and a photo of the machine . This is a good self - exciting machine , invented in 1880 . With 27 cm rotating disks , it produces sparks with up to 10 cm and more than 50 uA of short - circuit current . A Bohnenberger machine ( 1798 ) [ 4 ] , that I built in 1998 . A drawing , and a picture of the machine . An ancient machine of the " doubler " type , it is not a powerful machine , but is very interesting . See more about " doublers " in the section about influence machines below . In June 1999 I made experiments with a bipolar Van de Graaff generator , ( drawing ) similar to the original machine , but smaller . This is a large Bonetti machine , that I started to build in December 1999 . The disks are old ebonite disks that come with the Radiguet & Massiot Bonetti machine that I recently restored . A drawing of it . Front view , and back view . Another view of it , and another . Some sparks , that may reach 20 cm .. In April 2000 I finished a Wimshurst triplex machine . ( drawing ) . It ' s a double Wimshurst machine , using the close proximity between the central disks to increase the output current , through greater induction and mutual shielding . Pictures of the machine , in front view , back view , and side view . The machine produces a high current ( 100 uA with the 36 . 5 cm disks rotating at 16 turns per second , 4 times more than a single Wimshurst machine with the same disks ) . With the original design , it reached only 8 - 12 cm sparks , eventually reaching 14 or 15 cm on dry days , because with the rather small separation of the sectors it easily sparked through them and the neutralizer bars . With half of the sectors removed , it produces consistent 15 cm sparks . By the same time , I made also a working version of Bennet ' s doubler , a curious simple influence machine . In August 2000 I made a version of Nicholson ' s doubler , the first automatic influence machine ( 1788 ) . In January 2001 I completed a double Wommelsdorf machine , following closely the original design of [ p84 ] ( 1920 ) , but with modern materials . Front view , and back view . A collection of parts . Partial assembly . Assembling the neutralizer . Neutralizer and other details assembled . Back view . The machine , almost complete . Back . The disks , and the switches . The complete machine . back view , side view , other side , and another view , with only painting missing . The machine works quite well ( 13 . 5 cm sparks , 100 uA current ) for the two 28 cm disks . In March 2001 I made a curious AC electrostatic machine , apparently new , that I named as " half Wimshurst machine " . And by April 2001 I extended the same idea to a three - disks machine , that I named as " unfolded Wimshurst machine " . A Wehrsen machine , completed in April 2002 . It is a prototype for a large Wehrsen machine ( see below ) , that I started to build in August 2001 . Some parts for it at the start of the construction . Almost complete , by March 2002 . Back view . Working , it performs quite well , with 11 cm sparks and 70 µA of short - circuit current . An electrostatic linear motor , completed in January 2002 . A large Wehrsen machine , first tested by August 2003 . Almost complete by July 2003 . Another view , back view . Ray - tracing picture . Just before the first test . First test . The machine is still without its definitive rotating disk due to construction and insulation difficulties . This is a Toepler - Dirod machine that I was building by March 2004 , still without spark terminals , and with terminals . It ' s connected as the symmetrical Toepler machine , but uses Dirod - type disks . A drawing of the final machine . The machine works , but is weak . Bohnenberger ' s Bennet ' s doubler . A curious little machine that I built in April 2004 . Bohnenberger ' s Nicholson ' s doubler . A version of Nicholson ' s doubler with back - and - forth movement , built in May 2004 . So far not so good as the other doublers . See also the comments about machines that I have restored , in the section about influence machines below . Machines built by others A big Wimshurst machine built by Jim Banas . A sectorless Wimshurst machine with 60 cm disks . This machine was built by Ed Wingate . A spark from this machine . Another sectorless Wimshurst machine , with 30 cm disks . Similar to the one described by R . A . Ford in [ 8 ] . A more recent picture . Side and base view . Neutralizers , Charge collectors . Another view . This machine was built by J . Hardesty and Ed Wingate . Photos sent by Steve Cole . An old Wimshurst machine repaired by Johannes Zolk in 1996 , with the original broken disks replaced by LP records , with good results . Front view , and back view . Photos sent by J . Zolk . A " shake - sphere " machine [ 10 ] , built by Joachim Bolz and his students in 1997 . It is an influence machine using two balls in a tube , moved by shaking the tube , instead of disks . It works as my Toepler machine above . An schematic diagram of it . Photo and drawing by J . Bolz . Operation of the machine . Complete plans for a beautiful Wimshurst machine , built by J . M . S . van Gelderen in 1997 . Plans for the disks , a top view , a back view , a side view , and details of the terminals and Leyden jars . Pictures from the machine , seen from the front and back sides , and from above here and here . Ricardo " Rike " built this Wimshurst machine in 1997 , using LP records for the disks . It produces 7 cm sparks . Another view . A beautiful large Wimshurst machine ( 40 cm disks ) , built by James T . Garavuso in 1998 . A frontal view , another , a side view , a back view with the terminals in storage position , another , and a view from above . Details if the charge collectors , neutralizers , and secondary spark gap . This machine produces 12 cm sparks . A Toepler machine , built by Maximiliano Guzman , from Spain , in 1998 . The disks have 27 cm of diameter . A later version used larger shields and a speed multiplier in the crank . A Wimshurst machine , built by Raymond Zaborski , from the USA , in 1999 . The small intersector distance and the neutralizers at low angle result in intense current and easy self - excitation , but relatively small spark length . A big motorized Bonetti machine , built by Emery Wayman , from the USA , in 1999 . The machines has disks with 61 cm of diameter , and produces sparks with up to 28 cm of length . Some sparks from the machine : 1 , 2 , 3 . The terminals balls have 7 . 5 cm of diameter . Mr . Wayman has built also a similar , smaller , machine with motors driving directly the disks . A motorized 2 disks Toepler machine , built by Roger Magnuson in 1999 . The disks have 20 cm of diameter . Another view . Note the small Leyden jars built in the terminal supports . A classic Wimshurst machine , built by Ronald Coleman in 1999 . Detail of the crank , and of the charge collectors . The machine is prepared for an upgrade with larger disks . A Wommelsdorf condenser machine with double rotation , built by Bert Pool , following plans in a thesis written by Wommelsdorf in 1904 . Another view . This machine is a compressed version of a multiple Wimshurst machine , with sectors mounted between pairs of insulating rings , interconnected through the external or internal edges of the rings . One set of rings / sectors is held by the inner side and the other by the outer side , and both turn in opposite directions . A well built small Wimshurst machine , made by Harry Boneham , from Canada . The support structure was machined from aluminum , with the disks having 18 . 5 cm of diameter . Another view . A Wimshurst machine , built by Terry Baines , from England , in 1999 . With 30 cm disks , it produces sparks with 3 cm . A Wimshurst machine , built by Alex Rice , from England , in 1999 . The machine has 32 cm disks , and produces sparks with 10 - 11 cm of length . The spark is a double exposure . A spark from the machine . In 2000 , he built an improved machine . A Wimshurst machine , with 18 " acrylic disks , built by John Clark , from England , in 2000 . It produces 3 " sparks . Dan Bowlds , from Kentucky , USA , designed this original machine . A bare disk rotates behind an insulating plate , that holds four wood blocks painted with conductive ink . The lateral blocks are connected to blades collecting charges from the back surface of the rotating disk , and to Leyden jars made in the supports . The upper and lower blocks are inductors , and are charged from the terminal blocks through single corona points , also made of wood . Opposite to the inductor blocks there are interconnected neutralizer blades . The terminals are directly connected to the Leyden jars in the supports . An elegant structure for a small motorized machine ( the disk has 6 " of diameter ) that works essentially as the Voss machine . The machine requires an initial charge to start , and produces sparks with 1 " of length . Back view , Lateral view . A Wimshurst machine with acrylic structure made by Scott Nagel in 2000 . With disks with 14 . 5 " of diameter , it produces sparks with up to 6 " . Another spark . Note the separated small balls in the positive terminal , and the good dimensions for the sectors in the disks . The charge collectors , with some sharp corners , were later modified . What is probably the largest working Wimshurst machine was built by Paul Hendriksen in 2000 , for a technical show by ROVC , in the Netherlands . The machine uses two glass disks with 2 . 15 meters of diameter ( 2 cm more than the large machine built by Wimshurst in 1884 ) , 12 mm thick . The output voltage reaches 1 MV , producing sparks of up to 1 meter . It turns at up to 100 rpm , producing 10 uA of current . The output voltage is too high for Leyden jars , and so two copper globes are used as distributed capacitors . Details of the driving pulleys and a curious discharging mechanism . A long spark , another , and more sparks . A big Wommelsdorf condenser machine with 10 55 cm disks was built by Serge Klein , in France , in 2000 . It can produce 25 cm sparks and up to 0 . 7 mA of current . Frontal views , from the left and right sides , a view of the motor that turns it , detail of the disks and inductors , and another view . The disks are composed of three disks glued with epoxy glue , with the central disks separating two sets of intercalated sectors . The inductor plates are also enclosed between plastic sheets glued with epoxy glue . It works better with the neutralizer brushes removed , with the gap between the disks and the neutralizer bars making the role of the gap in the neutralizer circuit of the classic machines . The machine was later upgraded to 12 disks , with better brush supports , in an attempt to increase the output current . A spark from the machine . Mr . Klein has also built other machines , as a Dirod , a Wimshurst machine , a big Bonetti machine , that produces 30 cm sparks , a machine similar to a Felici machine with disks and operating in open air , and a triplex sectorless Wimshurst machine . Another view . A nice Wimshurst machine , built by Julian Phillips , in New Zealand , in 2000 . With 30 cm disks , it can produce 7 cm sparks . Another spark , and a description of it . A very simple setup was developed by Michael Foster , in Los Angeles , USA , in 2001 , to produce long sparks by frictional electricity . He used nothing more than a long PVC tube , a paper towel , a very simple Leyden jar capacitor , and a special positive terminal to excite long sparks . A description of his procedure . a Wimshurst machine , built by Luca La Valle , in Rome , Italy . He built also other high - voltage devices , as a Van de Graaff generator and a Tesla coil . A curious small Wimshurst machine , designed by Fausto Gazzi , in Bologna , Italy . Mr . Gazzi deals with ancient instruments , and frequently makes restorations , as of this 4 disks Wimshurst machine . A nice Wimshurst machine , built by Chris Kitching , from England , in 2001 . Top view , detail from the charge collectors , and a spark with 14 . 5 cm produced by it . The acrylic disks have 36 cm of diameter and 4 mm of thickness , and are mounted on nylon bosses . The balls at the spark gaps and joints are softened steel balls . This and this Bonetti machines I found at eBay . They are similar to the machine described by R . A . Ford [ 8 ] . Builders unknown . Tony J . Meijers , in the Netherlands , built this nice Wimshurst machine . With 37 cm disks , it produces 14 cm sparks . Note the driving system , without crossed cords . Front view . Back view . He built also this Triplex Wimshurst machine , in 2000 , that with 41 cm disks produces 24 cm sparks . It also has a curious implementation of the driving system , with the driving axle making an angle of 10 degrees with the upper axle , so the crossed cord that drives the central disks don ' t touch itself at the crossing . Front view . Back view . Side view . Other view . Assembly of the disks . A thick 24 cm disk at the center and disks at the outer sides impede sparking to the center of the machine . The Leyden jars also have increased insulation . Georges Hublart , from France , built this Wimshurst machine , motorized and with a curious construction . Side view . With 33 cm disks , it produces 16 cm sparks . Note the chains driving the disks . He has also other high - voltage devices , as a Van de Graaff machine . A Wimshurst machine , with conductors insulated within PVC tubes and LP record disks covered by adhesive plastic foil , built by Ben Noviello , USA , in 2002 . It produces 10 cm sparks . A Wimshurst machine , built by Rod Heidel , from the USA , in 2002 . With 20 cm disks , it produces 5 cm sparks . The frontal structure is a capacitor . A beautiful Wimshurst machine , built in cherry wood and brass by Gerald J . Schaefer , from the USA , in 2002 . The disks have 18 " of diameter . Side view , Frontal view , With two demonstration devices . An intense spark from it . A symmetrical Toepler machine , built by J . Keverline , from the USA , in 2002 . With 30 . 5 cm disks , it produces sparks with up to 16 cm . The disks have increased insulation with a material used to insulate tool handles . This resulted in voltage high enough to pierce the spark shields , that had to have their thickness increased to 4 mm . A Wimshurst machine that was once used for demonstrations at the Science Museum , in London , England , restored in 2002 by Rob Skitmore . A large Bonetti machine , built by Karl Kehrle , in Germany , in 2003 . With 80 cm polystyrene disks , it produces 63 cm sparks , between a pair of aluminim balls ( 8 , 12 cm ) at the positive terminal and a 30 cm styrofoam ball covered with aluminum foil at the negative terminal . The glass Leyden jars have 720 pF each . Mr . Kehrle wrote a book [ 49 ] showing experiments with a similar sectored machine , that with 90 cm disks produces 47 cm sparks . A Toepler machine with 48 cm disks , built by Alain Tramasaygues , from France , in 2003 . This improved version , with the inductor plates mounted inside a box , worked better . This is a curious Van de Graaff generator also built by him , that can produce 30 cm sparks . This is his Van de Graaff with external belt . He also built a Dirod machine . Another view . A sectorless Wimshurst machine , with 60 cm disks , built by Grant Vincent Wells , in New Zealand . It can be operated by hand or by a motor , has an electronic startup system , and produces sparks with up to 24 cm . These two machines were built by Alan Kerley . The larger machine is a Voss machine with a 21 " and 17 . 5 " disks , and the other is a small Wimshurst machine made from CD disks . This is a Wimshurst machine made by Keith Stuart , by 2000 , in New Zealand . It produces 10 cm sparks . He also restored an old machine ( probably German , from around 1900 ) for the Auckland Museum of Transport and Technology . Front view , back view . By the end of 2003 , he made a curious combination between a symmetrical Toepler machine and a Dirod . Side view , other side , top view , end view . With 12 cm disks , it produces 4 cm sparks . A motorized Wimshurst machine , made by Thomas Rapp , in Munich , Germany , in 2004 . Another view . The disks have 30 cm of diameter . More informations and other projects can be found at the author ' s site . A Van de Graaff generator , made by Richard Linder , in Burlington , USA . The terminal is a stainless steel sphere with 45 cm of diameter . The bottom roller is made of Nylon , and the top roller of Teflon . The belt is made of 0 . 4 mm Mylar foil . Mr . Linder makes demonstrations using it at the Burlington Science Center . For the 2004 - 2005 school season , he built a larger machine , with a 36 " terminal . The 6 " belt is made of vinyl impregnated nylon . It produces arcs with 18 " to 24 " to a 1 . 5 " grounded sphere . A Wimshurst machine , built by Ricardo Triches , in Brazil , in 2004 . Another view . A big Van de Graaff machine , built by Harold Pollner , in California , USA , in 2004 . The terminal has 30 " of diameter , the comumn is 9 " PVC , the belt is made with 4 " Neoprene , and the machine is powered by a 1 / 4 hp 1725 rpm ac motor . Excitation is by rolling friction between the belt and the lower roller , that is a 4 " PVC coupling mounted over a wooden core . It produces 22 " to 27 " sparks , but from the rim of the sphere opening to a grounded target electrode positioned below the sphere , ( as in the picture ) . Sparks from other points of the sphere reach only 6 " to 7 " . A small Wimshurst machine , with 20 cm disks , built by Hannu Eloranta , from Espoo , Finland , in 2005 . A nice Wimshurst machine , belonging to Dr . Alistair Miller , England . The machine has 19 " disks and produces 6 . 5 " sparks . It was built by Anthony Swift , that runs a museum dedicated to Victorian science in North Yorkshire , England . A motorized Wimshurst machine , built by Peter Bradley , in England . Spark picture . Another spark . A curious friction machine built as a Gramophone , by Kaj V . M . Heiden , in the Netherlands . A spark . Several Wimshurst and Bonetti machines built by Jarrod Kinsey . Another view . A Wimshurst machine , built by Christophe Branger , in France , in 2006 . Another view , and another . Spark , another spark . A Wimshurst machine , built by Emiliano Salinas Covarrubias , from the Universidad de Sonora , Mexico . The acrylic disks have 40 cm of diameter , and the structure is made of polystyrene . It procuces 6 cm sparks . A big Bonetti machine , made by Hal Pollner , in the USA , in 2006 . With 25 " disks , it produces 11 " sparks . A Van de Graaff generator is used to excite the machine . Another view . Friction machines The first electrostatic machine [ 15 ] , was built by Otto von Guericke [ 16 ] by 1663 , using a sulphur globe frictioned by hand . The globe could be removed and used as source for experiments with electricity . A picture of a working replica of the machine , from the University of Oldenburg . Another important early researcher was Francis Hauksbee , that built several machines using glass globes [ 50 ] [ 53 ] and cylinders by 1705 . The friction machines were gradually improved through the works of many researchers . This is the machine with a glass globe of the abbot Nollet ( ~ 1740 ) [ 7 ] . Eventually , the machines took a stable form , with leather friction pads ( Winkler , 1744 ) , glass globes ( Bose , 1751 ) , and insulated charge collectors . Demonstrations with these machines were common . Watson ' s machine [ 51 ] [ 52 ] ( 1746 ) had a large wheel turning several glass globes . The prime conductors were a sword and a gun barrel suspended from silk cords . A Ramsden electrostatic friction machine [ 2 ] . Another picture [ 7 ] , another [ 12 ] , a good drawing [ 17 ] , and a picture of a large machine [ 14 ] . The first popular machine using a disk ( 1766 ) . Designed by J . Ramsden , an instrumentist that also designed many other good instruments in the 1700 ' s . A beautiful restored Ramsden machine , found at eBay in 1999 . Photos by Fausto Gazzi . This large machine I found in a museum in Geneva , Switzerland . A simpler machine built by myself is in a photo above . The machine of Le Roy ( 1772 ) [ 50 ] [ p26 ] was suitable for the production of long sparks , due to the high insulation between the friction pads and the charge collectors ( see a more modern version as the Winter machine , below ) . This large disk machine ( 1785 ) with 1 . 6 m disks can be seen at the Musée du Conservatoire Nacional des Arts et Metiers , In Paris , France . On its base is written the motto at the top of this page . There is a picture of it in [ 21 ] . A brass model of a Ramsden machine . A curious decorative object , possibly from the 1930 ' s or before . The disk has 3 . 5 " of diameter . Photos sent by Blake Awbrey . A Nairne electrostatic friction machine [ 7 ] , built in 1770 , consists in a glass cylinder , a friction pad in one side , and a charge collector in the other , both connected to insulated conductors . Another one . The van Marum electrostatic friction machine ( 1784 ) [ 9 ] . By moving the two curved bars with charge collectors , it was possible to collect charge from the disk ( bars as shown ) , or from the friction pads ( bars turned 90 degrees ) , producing voltage with any polarity , as shown here . Van Marum is also known for the big machine [ 16 ] [ 21 ] that he had made in 1784 , that is now in the Teylers museum . A similar machine , now in the Deutches Museum , Munich , Germany , belonged to Georg Ohm ( 1830 ? ) [ 21 ] . Another view . Photos sent by Hans Bussmann . A belt machine [ 50 ] built by N . Rouland by 1785 , had a charge collector with blades that collect charges from a silk belt rubbed by two grounded tubes covered with hare fur [ 21 ] . An old friction machine using a glass disk . Another picture of the same machine . Photos sent by Don Day . A Winter electrostatic friction machine . One of the most efficient friction machines . A picture from an old book [ 3 ] , and another , from H . Pellat [ 7 ] . This was the last popular structure for friction machines , as shown in these catalog pictures from the 1920 ' s : this and this are from [ 17 ] , and this is from [ 22 ] . The characteristics of the machine are the disk frictioned at one side , at both faces , with a pair of charge collectors at the other side , shaped as rings with points turned to the disks . Sometimes a large wood ring ( Winter ' s ring ) with a metallic core was attached to the terminal , increasing it ' s capacitance . A double version can be seen on the first picture . The Woodward machine ( 1840 ) [ 43 ] [ 21 ] was a modified Ramsden machine , with the prime conductor located above the disk , or disks , saving some space . It could also generate negative voltage , by mounting the upper friction pad in place of one of the charge collectors . This double machine is in the University of Porto , Portugal . Partially disassembled . Pictures by Marisa Monteiro . The Armstrong hydroelectric machine [ 2 ] , a friction machine using steam as charge carrier ( 1840 ) . It is just an insulated boiler producing a steam jet mixed with water droplets . A better picture is here [ 9 ] . The Lorente generator . A triboelectric machine composed of four cylinders that roll together without friction , under a slight pressure . The two outermost cylinders are metallic , and the two central cylinders are of distinct insulating materials ( nylon and teflon ) . Opposite charges are collected in the metallic cylinders . The basic machine produces voltages of some tens of kV , but several modules can be stacked for more voltage . A coaxial version is also possible . Pictures from actual models are here and here . This device was invented and patented by G . Lorente , who sent the pictures . Influence machines The first rotating influence machines were the " doublers " . The first was Nicholson ' s doubler [ p14 ] ( 1788 ) . It was a rotating implementation of Bennet ' s doubler ( 1787 ) , a device based on Volta ' s " electrophorus " ( see also here ) ( 1776 ) , that allowed great multiplication of a small initial charge by a series of repeated operations with three insulated plates . The original machine proposed by Nicholson didn ' t require a connection to ground , but versions with explicit ground connections are also possible , as this [ 28 ] , and this ( built by Wimshurst ) [ p14 ] . An actual machine exists the Musee d ' histoire des sciences , in Geneva ( the site has a movie of the doubler in operation ) , that looks as this machine ( John Read ' s doubler ) [ p106 ] . See my Nicholson ' s doubler . A similar implementation , where the two plates that are fixed in Nicholson ' s device rotate , is Bohnenberger ' s machine ( 1798 ) [ 4 ] . Bohnenberger designed several other doublers , as this automated version of Bennet ' s doubler and this variation of Nicholson ' s doubler ( 1801 ) [ p107 ] , both operating with back and forth movements . See my Bohnenberger ' s machine . Multipliers based on a different system are also possible , as Péclet ' s condenser ( 1841 ) that increases the charges linearly with the number of operations [ p87 ] and a multiplier with 4 plates invented by Pfaff and Svanberg that combines addition and multiplication [ 54 ] . A similar adding device was Cavallo ' s multiplier ( 1795 ) , where a movable insulated plate was moved back and forth , alternatively being grounded under the influence of a second previously charged plate , and touching a third insulated plate close to a grounded fourth plate . After some cycles , the grounded plate would be removed , causing the accumulated charge at the third plate to rise its potential to about the potential of the second plate times the number of cycles [ 4 ] . The next development was of symmetrical influence machines , using influence to generate new charges and Faraday ' s shielding effect to collect them . The first was Belli ' s machine [ 4 ] [ p14 ] ( 1831 ) , the first symmetrical influence machine . A picture of an elaborated actual machine . Belli developed also a different machine using the same principle , shown here . The same basic structure appears in Lord Kelvin ' s " replenisher " [ 2 ] [ p92 ] ( 1867 ) , in schematic representation , and as constructed [ 12 ] . A simple machine built with insulated curved metal plates , used as part of measurement instruments . Here is a ray - tracing picture similar to a machine that I built by 1973 . The rotation of the central insulating bar with two metallic carriers , touching the four contacts , causes accumulation of opposite charges in the outer plates . Another similar machine was the Varley machine [ 26 ] ( 1860 ) . A curious machine [ 18 ] that appears to be similar , if the lateral brushes are connected to the fixed plates . The same machine appears illustrating this advertisement ( 1962 ) but with an added set of brushes installed , to separate the output circuit from the inductor plates , as in the Voss machine . The Piche machine , or Bertsch machine ( 1866 ) [ 7 ] . One of the simplest influence machines , uses an insulator plate ( I ) , that is separately electrized by friction , and used to generate charges in the rotating disk by induction . See the original letters about this machine in the references . A similar device is the Dubrowski machine [ 22 ] . This type of machine was called " continuous electrophorus " . The Carré machine [ 6 ] ( 1868 ) . A friction machine below charges by induction a fast rotating disk , that transfers charge to the upper conductor . It is similar in operation to the Bertsch machine , but regenerates the charge in the inductor . A better picture [ 7 ] . A variation [ 14 ] with slanted combs . A ray - tracing drawing . A photo from an actual machine , sent by John Newman . A machine with a double terminal . The Van de Graaff generator [ p4 ] [ 8 ] is an evolution of this machine , with a belt instead of the disk , and a more efficient charge collector at the top . This machine is in a museum in Switzerland . Another machine , in a Museum in Spain . A double Bonetti machine from the same museum , with curiously shaped neutralizer combs ( ? ) . Another antecessor of the Van de Graaff generator is Righi ' s electromer [ p55 ] ( 1872 ) , that used a rubber string with brass rings for charge transport , and a hollow sphere as charge collector . A picture of this machine [ 41 ] . Similar machines are also discussed in [ p59 ] ( 1875 ) , as a bipolar machine , that must have grounded pulleys , and another , that adds a neutralizer circuit and can use insulated pulleys . Righi studied also a belt machine [ p59 ] , that antecipates a regenerative charging system used in some Van de Graaff machines , and shows a curious polarity reversal phenomenon , where for some time the belt operates with bands of both polarities . Righi designed this big Holtz machine [ 41 ] ( ~ 1875 ) , used at the Regio Istituto Tecnico de Bologna for teaching and research . A drawing of a similar machine [ 42 ] . A Lord Kelvin ' s water machine ( 1867 ) [ 1 ] [ p91 ] . It is an influence machine that uses water droplets instead of rotating carriers . It works in the same way of the 2 disks Toepler machine . Another picture [ 6 ] of a similar machine . An improvement of this machine using two additional units for output , avoiding the discharge of the inductors , was proposed by Fuller in 1888 [ p103 ] [ p62 ] . A different version was proposed by Sylvanus Thompson in 1887 [ p104 ] . The Schwedoff influence machine [ 9 ] [ 13 ] [ 29 ] ( 1868 ) . A very strange machine . The lower plates form a modified Holtz machine , with inductor plates replaced by combs ( dotted lines ) charging the lower surface of the lowest fixed disk with charge taken from the charge collectors . This first machine provides bias for the sectors in the lower plate of the upper assembly ( the even - numbered ones with one polarity , the others with another ) , that form a current multiplier . The output is taken between the two insulated sets of combs over the upper , rotating disk . This picture from the original paper [ p46 ] shows more clearly the connections . This is the charge collector [ p46 ] that completes the machine . A Toepler - Holtz machine , or Voss machine with classical design . From a catalog from the 1920 ' s . Two more pictures here and here . Pictures found in the Gemmary ' s forum . Several Toepler - Holtz , or Voss , machines from [ 17 ] : A simple machine , another , a double machine , a quadruple machine ( see one here ) , and a multiple machine . Two more simple machines from [ 18 ] : this and this . And another one , from [ 22 ] . A magnific quadruple Voss machine , at the museum of the University of Pavia , Italy . A Holtz - Wimshurst machine [ 4 ] [ 23 ] , simple and with a frictional starter [ 4 ] [ 23 ] . These were Holtz - type machines with several disks and improved construction , as the inductors fixed in separate square glass plates , developed by Wimshurst by 1878 . The Kundt machine [ 4 ] ( 1868 ) was a mixed friction - influence machine , similar to a Bertsch machine with the back side of the disk frictioned by a friction pad with a silk flap attached , as in a friction machine . At the front side are positioned two charge collectors , as in the Bertsch machine . A similar machine was the Cantoni machine ( 1869 ) , that added a third charge collector at the back side of the disk , so the machine can also be used as a friction machine . A good picture of a classic Wimshurst machine ( 1883 ) [ 1 ] . A Line drawing of the same picture [ 2 ] . A Wimshurst machine [ 6 ] , similar to one that exists in the Museum of the UFRJ Engineering School , and that I restored . Another [ 14 ] similar machine . That machine was built by F . Ducretet and E . Roger , Paris , and originally should look as in this ( front ) and this ( back ) ray - tracing drawings . Here are comments about the restoration and more pictures . This is how it is now , compared with my 1974 Wimshurst . A large spark produced by the machine in a demonstration . Another picture , showing two of these machines connected as a generator and motor pair [ 24 ] . These pictures [ 23 ] show discharge images on photographic plates obtained with one of these machines . A positive discharge , and a negative discharge . A multiple machine from the same instrument builder , at the University of Porto , Portugal . Here is another Wimshurst machine from the same museum that I restored ( ray - tracing ) , a picture of it , and some comments about the restoration . The largest Wimshurst machine ever built is presently at the Science and Industry Museum in Chicago , USA . It was built in England in 1885 , with 7 foot glass disks 3 / 8 inch thick , and produced sparks with 22 inches . This picture is from Engineering , Vol . 39 , 1885 , scanned from [ 23 ] ( also appears in [ 4 ] [ 5 ] [ 8 ] [ 26 ] ) . More informations and pictures about this machine . More Wimshurst machines , from [ 14 ] : A large simple machine , a double machine , a quadruple machine , and an octuple machine . And also two machines from [ 15 ] , with ebonite disks and Leyden jars with two sections , and with glass disks . Two more large machines from [ 22 ] : A simple machine and a quadruple machine . Wimshurst machines , from the collection belonging to Louie Scribner : A French machine ( Bonetti ) , and a German machine ( Leybold , 1901 ) . Wimshurst machines that have full construction details in [ 4 ] [ 23 ] : A laboratory machine , a long spark machine , and a twelve plates machine . Designs by J . Wimshurst . A " Voltana " Wimshurst machine [ 34 ] ( 1921 ) , used to run an electrostatic motor , and a bank of Geissler tubes . A larger machine , a smaller machine , another machine , more Geissler tubes being lighted , lighting a spinning Geissler tube , charging a Leyden jar , and charging a spring , that expands when charged [ 35 ] . Several machines , from [ 38 ] , that illustrate the state of the art by 1900 : A classic Wimshurst m