Made available in DSpace on 2016-04-29T13:17:49Z (GMT). No. of bitstreams: 1 Luciano Ernesto Lobato.pdf: 2954753 bytes, checksum: 2947df16cc5620b74ecf5e946aec855a (MD5) Previous issue date: 2013-06-21 / The research aimed to verify whether interlocked behavioral contingencies (IBCs) established in contingency conditions between aggregate output and cultural consequence remains when the subsequent cultural event turns to have a relation of mere contiguity with the aggregate output. One experiment was conducted with ABAC design (Contingency I, Contiguity I, Contingency II, Contiguity II), in which a group of 3 participants played a computer game. 25 subjects participated in the experiment, a total of 23 generations (3 participants in each). Participants earned points if they had entered numbers whose sum to the numbers presented by the computer program resulted in odd numbers. The group earned food to be donated to a charity institution, if the sum of the participant's left was less than or equal to the sum of the participant's center and this was less than or equal to the sum of the participant's right in Contingency s phases (Contingency I and Contingency II), or 50% and 70% (phases Contiguity I and Contiguity II, respectively) of the cycles after any aggregate product. The results showed the selection of operant behavior in all phases and the selection by metacontingencies of different interlocked behavioral contingencies (IBCs) that generated aggregate output required for the production of cultural consequence in phases Contingency I and Contingency II. In phases Contiguity I and Contiguity II, these IBCs selected in the previous phase were maintained for a few generations, but at lower frequency, and giving rise to other interlocked behavioral contingencies that were possibly selected "accidentally" by subsequent cultural events / A pesquisa teve o objetivo de verificar se contingências comportamentais entrelaçadas (CCEs) estabelecidas em condições de contingência entre o produto agregado e a consequência cultural se mantém quando o evento cultural subsequente passa a ter uma relação de mera contiguidade com o produto agregado. Foi conduzido 1 experimento, com delineamento ABAC (Contingência I, Contiguidade I, Contingência II, Contiguidade II), no qual um grupo formado por 3 participantes jogava um jogo de computador. 25 sujeitos participaram do experimento, totalizando 23 gerações (3 participantes em cada). Os participantes tinham suas respostas individuais consequenciadas com pontos, caso inserissem números cuja soma com os números apresentados pelo programa de computador resultasse em números ímpares. O grupo tinha seus entrelaçamentos consequênciados com alimentos a serem doados para uma instituição de caridade, caso a soma do participante da esquerda fosse menor ou igual que a soma do participante do centro e esta fosse menor ou igual que a soma do participante da direita nas fases de Contingência (Contingência I e Contingência II), ou em 50% e 70% (fase Contiguidade I e Contiguidade II, respectivamente) dos ciclos após qualquer produto agregado. Os resultados mostraram a seleção do comportamento operante em todas as fases e a seleção por metacontingências de diferentes contingências comportamentais entrelaçadas (CCEs) que geravam o produto agregado exigido para a produção da consequência cultural nas fases de Contingência I e Contingência II. Nas fases de Continguidade I e Contiguidade II, estas CCEs selecionadas na fase anterior foram mantidas por algumas gerações, porém em frequência menor, e dando lugar a outros entrelaçamentos que possivelmente foram selecionados acidentalmente pelos eventos culturais subsequentes

Made available in DSpace on 2016-04-29T13:17:56Z (GMT). No. of bitstreams: 1 Dissertacao Thais Nogara.pdf: 1558052 bytes, checksum: ccb32c051365bae930fde318c9580dd9 (MD5) Previous issue date: 2006-03-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The effects of presenting stimuli that are well established as reinforcers independently of responding have been studied under two different perspectives. On the first perspective, through a procedure called accidentally reinforcement, stimuli are presented non-contingently, resulting in the accidental selection of a response, an effect called superstition. On the other perspective, in a procedure called uncontrollability stimuli are presented independently of responding resulting in a difficulty in learning when another contingency is presented, a behavioral effect called learned helplessness (LH). It has been suggested that the interval from the non-contingent presentation of the stimulus and the response may have an important role in producing either one of two behavioral effects. The goal of this study was to investigate: (a) the effects of different duration of an aversive auditive stimuli on the possibility of establishing contiguity between responding and the ending of the stimulus; (b) the effects of the different stimulus-response intervals on the responding pattern; (c) the effects of different manipulations of stimuli presentation (response dependent, response independent, and delayed dependent) on the participants performances in a new escape contingency. Fifty participants were assigned to five groups: contingent (CON), yoked non-contingent (YNC), non-contingent (NC), contingent with delay (CD), and control. Four groups were exposed to two experimental phases: training and testing. In the training phase, each group experienced a different contingency: CON participants could escape from the aversive stimuli; YNC participants experienced the same aversive stimuli (order and duration) as CON participants, but could not escape; NC participants experienced 5s stimuli along the training phase and could not turn them off; CD participants could escape from the stimuli, but the emission of the response started a delay that was dependent upon the interval between the end of the stimulus and the preceding response emitted by a NC participant. The control participants were not exposed to a training phase. During test, all participants could escape from the aversive stimuli by emiting a new escape response. Results show that: a) 12 out of 40 participants showed some accidentally selected behavioral pattern during training. In the testing phase, all this 12 participants learned the new escape response. Other twenty-four participants had their performance in the testing phase classified as learned helplessness: 13 from NC and YNC groups, 4 from CON, 4 from control and 2 from CD; b) stimulus duration did not seem to determine the interval between the end of the stimuli and the preceding response; c) for some participants, temporal contiguity between the end of the stimulus and the preceding response was enough to select a behavioral pattern, but the contingent relation between these two events was a powerful variable in the selection and maintenance responding, even for those participants who were exposed to a contingent but not contiguous (delayed) stimuli-response relation / Os efeitos da apresentação independente das respostas de um sujeito de eventos ambientais bem estabelecidos como reforçadores têm sido investigados sob duas diferentes perspectivas. Para uma delas, a liberação não contingente desses eventos pode resultar na seleção acidental de respostas. O efeito em questão foi chamado de superstição e o procedimento, de reforçamento acidental. Sob uma outra perspectiva, a apresentação de estímulos independentemente do responder pode levar a uma dificuldade de aprendizagem quando uma nova contingência é apresentada. O efeito comportamental observado foi chamado de desamparo aprendido e o procedimento, de incontrolabilidade. Tem sido sugerido que o intervalo de tempo entre a apresentação não contingente do estímulo e as respostas dos sujeitos pode desempenhar um papel importante na produção desses efeitos. O objetivo do presente estudo foi investigar: (a) os efeitos de diferentes durações de um estímulo sonoro aversivo sobre o intervalo de tempo entre o seu término e a resposta precedente; (b) os efeitos desses diferentes intervalos sobre o responder dos participantes; e (c) os efeitos de diferentes arranjos experimentais (dependente, independente e dependente com atraso) sobre o desempenho dos participantes numa nova contingência de fuga. Para isso, 50 participantes foram distribuídos em seis grupos: contingente (CON), acoplado não contingente (ANC), não contingente (NC), contingente com atraso (CA) e controle. Quatro desses 5 grupos foram submetidos a duas fases experimentais: treino e teste. No treino, cada grupo passou por uma contingência diferente: ao grupo CON era dada a possibilidade de escapar do estímulo aversivo; o grupo ANC recebia os mesmos sons (mesma ordem e duração) que os participantes do grupo CON, mas não podiam escapar dos mesmos; o grupo NC experienciou sons com a duração de 5s durante toda a fase de treino e não podia desligá-los; o grupo CA podia fugir dos sons, mas a emissão da resposta de fuga iniciava um atraso que era determinado pelo intervalo entre o término do som e a resposta precedente, para o grupo NC. O grupo controle não passou pela fase de treino. No teste, todos os participantes podiam escapar dos sons por meio de uma nova resposta de fuga. Como resultado, observou-se que: a) 12 dos 40 participantes tiveram algum padrão de respostas acidentalmente selecionado no treino. No teste, esses 12 participantes aprenderam a resposta de fuga. O responder de outros 24 participantes, no teste, foi classificado como desamparo aprendido: 13 são dos grupos NC e ANC, 4, do grupo CON, 4, do grupo controle e 2, do grupo CA; b) a duração do som não foi a variável determinante do intervalo de tempo entre o término do som e a resposta precedente; c) embora, para alguns participantes, a contigüidade temporal entre o término do som e a resposta precedente tenha sido condição suficiente para selecionar um dado padrão de respostas, a relação de dependência entre esses eventos pareceu desempenhar um papel muito importante na seleção e manutenção do responder, mesmo para aqueles participantes expostos a uma relação estímulo-resposta contingente, mas não contígua (atrasada)

Made available in DSpace on 2017-07-10T19:24:40Z (GMT). No. of bitstreams: 1 Gustavo Henrique Dalposso.pdf: 751881 bytes, checksum: d4ec13dacd0e510c7549e67525afd909 (MD5) Previous issue date: 2010-01-13 / The methods provided by the spatial statistics are of great importance for studies involving data related to agriculture, for they allow one to know the space variability of the study and identify regions that have similar characteristics, which allows completely localized treatment, maximizing productivity and minimizing the impacts of excessive input application. One of the branches of spatial statistics is geostatistics, which uses a set of regionalized variables to model the structure of spatial dependence, allowing the preparation of thematic maps. Currently, geostatistical studies do not end with the preparation of maps, but also estimates monitored the attribute in non-sampled locations. It is necessary to investigate the quality of these maps, investigating influential points and using measurements to compare maps and area estimations. Another form of research is known as spatial statistics of areas where the objects of analysis are polygons representing blocks, neighborhoods, cities, states and others. This type of analysis seeks to identify spatial autocorrelation in global and local levels, and the usual form of reporting is through thematic maps. In this work we used geostatistics to investigate the productivity of wheat in an agricultural area of 13.7 hectares in the municipality of Salto do Lontra PR. Out of the 50 samples, two were identified as influential, and thus, we chose to build two thematic maps and to compare them using metrics derived from the matrix of errors. The results showed that the maps are different and the removal of influential points was essential to improve the quality of thematic map, since the difference between the estimated yield and actual yield was only 40 Kilos. In order to display the resources provided by the spatial statistics of areas we compared to the vegetation rates NDVI and GVI's of soybean yield from 36 cities in Western Paraná in the agricultural year of 2004/2005. The results showed regions with similar characteristics and that soybeans grow at different times in the region. / As metodologias fornecidas pela estatística espacial são de grande importância para estudos envolvendo dados relacionados à agricultura, pois permitem conhecer a variabilidade espacial dos atributos estudados e identificar regiões que apresentam características semelhantes, o que permite realizar tratamentos localizados, maximizando as produtividades e minimizando os impactos causados pela aplicação de insumos em excesso. Um dos ramos da estatística espacial é a geoestatística, que utiliza um conjunto de variáveis regionalizadas para modelar a estrutura de dependência espacial, possibilitando a elaboração de mapas temáticos. Atualmente os estudos geoestatísticos não terminam com a elaboração dos mapas, pois além de estimar o atributo monitorado em locais não amostrados se faz necessário investigar a qualidade destes mapas, investigando pontos influentes e utilizando medidas que permitam comparar mapas e realizar estimações de áreas. Outra forma de investigação é conhecida como estatística espacial de áreas, em que os objetos de análise são polígonos que representam talhões, bairros, municípios, estados entre outros. Neste tipo de análise, procura-se identificar autocorrelações espaciais em nível global e local, e a forma usual de apresentação dos resultados é feita utilizando mapas temáticos. Neste trabalho utilizou-se a geoestatística para investigar a produtividade de trigo em uma área agrícola de 13,7 hectares no município de Salto do Lontra Pr. Das 50 amostras coletadas, identificou-se duas como influentes e, com isso, optou-se por construir dois mapas temáticos e compará-los utilizando métricas derivadas da matriz dos erros. Os resultados mostraram que os mapas são diferentes e a retirada dos pontos influentes foi de fundamental importância para melhorar a qualidade do mapa temático, visto que a diferença entre a produtividade estimada e a produtividade real foi de apenas 40 quilos. Para apresentar os recursos fornecidos pela estatística espacial de áreas comparou-se os índices de vegetação NDVI e GVI da produtividade de soja de 36 municípios da região Oeste do Paraná no ano agrícola 2004/2005. Os resultados permitiram identificar regiões com características semelhantes e que a soja é cultivada em períodos distintos na região.

Made available in DSpace on 2017-05-12T14:48:03Z (GMT). No. of bitstreams: 1 Gustavo Henrique Dalposso.pdf: 751881 bytes, checksum: d4ec13dacd0e510c7549e67525afd909 (MD5) Previous issue date: 2010-01-13 / The methods provided by the spatial statistics are of great importance for studies involving data related to agriculture, for they allow one to know the space variability of the study and identify regions that have similar characteristics, which allows completely localized treatment, maximizing productivity and minimizing the impacts of excessive input application. One of the branches of spatial statistics is geostatistics, which uses a set of regionalized variables to model the structure of spatial dependence, allowing the preparation of thematic maps. Currently, geostatistical studies do not end with the preparation of maps, but also estimates monitored the attribute in non-sampled locations. It is necessary to investigate the quality of these maps, investigating influential points and using measurements to compare maps and area estimations. Another form of research is known as spatial statistics of areas where the objects of analysis are polygons representing blocks, neighborhoods, cities, states and others. This type of analysis seeks to identify spatial autocorrelation in global and local levels, and the usual form of reporting is through thematic maps. In this work we used geostatistics to investigate the productivity of wheat in an agricultural area of 13.7 hectares in the municipality of Salto do Lontra PR. Out of the 50 samples, two were identified as influential, and thus, we chose to build two thematic maps and to compare them using metrics derived from the matrix of errors. The results showed that the maps are different and the removal of influential points was essential to improve the quality of thematic map, since the difference between the estimated yield and actual yield was only 40 Kilos. In order to display the resources provided by the spatial statistics of areas we compared to the vegetation rates NDVI and GVI's of soybean yield from 36 cities in Western Paraná in the agricultural year of 2004/2005. The results showed regions with similar characteristics and that soybeans grow at different times in the region. / As metodologias fornecidas pela estatística espacial são de grande importância para estudos envolvendo dados relacionados à agricultura, pois permitem conhecer a variabilidade espacial dos atributos estudados e identificar regiões que apresentam características semelhantes, o que permite realizar tratamentos localizados, maximizando as produtividades e minimizando os impactos causados pela aplicação de insumos em excesso. Um dos ramos da estatística espacial é a geoestatística, que utiliza um conjunto de variáveis regionalizadas para modelar a estrutura de dependência espacial, possibilitando a elaboração de mapas temáticos. Atualmente os estudos geoestatísticos não terminam com a elaboração dos mapas, pois além de estimar o atributo monitorado em locais não amostrados se faz necessário investigar a qualidade destes mapas, investigando pontos influentes e utilizando medidas que permitam comparar mapas e realizar estimações de áreas. Outra forma de investigação é conhecida como estatística espacial de áreas, em que os objetos de análise são polígonos que representam talhões, bairros, municípios, estados entre outros. Neste tipo de análise, procura-se identificar autocorrelações espaciais em nível global e local, e a forma usual de apresentação dos resultados é feita utilizando mapas temáticos. Neste trabalho utilizou-se a geoestatística para investigar a produtividade de trigo em uma área agrícola de 13,7 hectares no município de Salto do Lontra Pr. Das 50 amostras coletadas, identificou-se duas como influentes e, com isso, optou-se por construir dois mapas temáticos e compará-los utilizando métricas derivadas da matriz dos erros. Os resultados mostraram que os mapas são diferentes e a retirada dos pontos influentes foi de fundamental importância para melhorar a qualidade do mapa temático, visto que a diferença entre a produtividade estimada e a produtividade real foi de apenas 40 quilos. Para apresentar os recursos fornecidos pela estatística espacial de áreas comparou-se os índices de vegetação NDVI e GVI da produtividade de soja de 36 municípios da região Oeste do Paraná no ano agrícola 2004/2005. Os resultados permitiram identificar regiões com características semelhantes e que a soja é cultivada em períodos distintos na região.

Magnetic measurements are useful tools for quality control of cemented carbides. Previous work at Sandvik Mining and Rock Technology has shown that the coercivity increases with increased cooling rate during sintering for a specific grade.  This study aims to investigate why the coercivity changes with the cooling rate and if this is true for other cemented carbide grades as well. Three different cemented carbide grades were sintered with different cooling rates and evaluated with coercivity, Cobalt-magnetic saturation and hardness measurements, and with microscopy and Electron Backscatter Diffraction analysis. It was found that the coercivity increased with increasing cooling rates for the previously studied grade, but not for the two other grades. It was expected that the increased coercivity would indicate a decrease in WC grain size, but the results showed that the WC grain size of the fastest and slowest cooling rate were the same. However, a change in size of the Co areas between the WC grains was found. The fast cooled sample showed smaller Co areas than the slow cooled sample. These Co/WC grain boundaries increase the coercivity. An increased fraction of hcp-Co/fcc-Co was also found for the fast cooled material which also increases the coercivity. No relationship between the hardness and the coercivity or the cooling rate was found.   The contiguity for the different grades was also calculated.  No significant difference in contiguity between the different cooling rates of each material was found but the contiguity values between the different materials differed.  This is probably mainly dependent on the different binder contents of the materials. / Magnetiska egenskaper är en viktig del av kvalitetskontrollen av hårdmetaller.  Tidigare forskning hos Sandvik Mining and Rock Technology har visat att koerciviteten hos en hårdmetallsort ökar med ökad kylhastighet vid sintring.  Målet med den här studien är att undersöka varför koerciviteten ökar med kylhastigheten och om detta även gäller andra hårdmetallsorter.  Tre olika hårdmetallsorter sintrades med olika kylhastigheter undersöktes med mätningar av koercivitet, magnetisk mättnat i koboltfasen och hårdhet,  samt med mikroskopi och Electron Backscatter Diffraction analys. Det  visade  sig  att  koerciviteten  ökade  med  ökad  kylhastighet  för  hårdmetallsorten  som  studerats tidigare, men inte för de andra två sorterna.  En ökad koercivitet förväntas visa på en minskad WC-kornstorlek, men resultaten visar att det långsamt kylda och snabbkylda provet hade samma WC-kornstorlek.  Däremot upptäcktes en ändring av storleken på Co-områdena mellan WC-kornen.  Det snabbkylda provet visade en mindre storlek av Co-områdena jämfört med det långsamt kylda provet. Fler Co/WC-korngränser i det snabbkylda provet leder till en ökad koercivitet.  Fraktionen av hcp-Co/fcc-Co-korngränser ökade också för det snabbkylda provet vilket också ökar koerciviteten. Inget samband mellan hårdheten och koerciviteten eller kylhastigheten upptäcktes.  Beräkning av kontiguiteten för de olika sorterna genomfördes också. Ingen signifikant skillnad i koercivitet mellan de olika kylhastigheterna för the olika sorterna hittades,  men kontiguiteten mellan de olika sorterna varierade. Det beror mest troligt på att dom olika sorterna har olika mängd matrismaterial.

<p><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi / mso-bidi-font-weight:bold">The basic premise of this study was that when a learner is confronted with two contradictory explanations of the same phenomenon, there is cognitive dissonance in the learner as the learner tries to determine which of the two explanations is correct. An argumentation-based instructional intervention programme (ABIIP) was created for and used on and by the Grade 10 learners in order to attempt to ameliorate this cognitive conflict. </span><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The purpose of this study was to determine the relative impact of that intervention programme on Grade 10 learners&rsquo / conceptions of lightning and thunder. The programme was designed to help learners to develop argumentative skills and use the acquired skills to negotiate and harmonise divergent and conflicting explanations of the nature of lightning and thunder that are propounded by different worldviews (Science and indigenous knowledge).</span><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The research design was primarily a case study of 16 Grade 10 learners of the Xhosa ethnic group at a high school in the Eastern Cape Province of South Africa. The Xhosa people are a typical example of a people whose cultural values were undermined and whose voice was silenced by the colonisers and whose local knowledge has been repressed and replaced by forms of Western privileged knowledge and understandings but who remain, deeply and resolutely, steeped in their cultural values and practices, making them a classic example of a people who would battle to harmonise the indigenous and the scientific explanations of natural phenomena. The research instruments used were questionnaires which were administered to learners, educators, community leaders, indigenous knowledge holders and experts to solicit information on causes, dangers and prevention of lightning / individual and group activities as learners went through the lessons on both argumentation and on lightning / follow up interviews and discussions with learners individually or in groups to seek further clarification of the ideas the learners would have raised in their earlier responses to questionnaires or group discussions / guided and reflective essays by the learners to determine the learners&rsquo / levels of understanding of the major tenets of the two thought systems and the relationship between the two worldviews and to determine the qualitative gain, if any, that the learners got from the intervention programme / observation schedules used by the researcher during participant observation of group discussions and during the lessons on lightning / an achievement test on lightning / field notes used by the researcher for memoing observations and reflections as the research process proceeded / informal and serendipitous sources of information. <span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The collected data were analysed, mostly, qualitatively. Frequencies, percentages and t-test values were used to express and analyse quantitative data. Aspects of several analytical frameworks that included Toulmin&rsquo / s Argumentation Pattern (TAP) [and its modified versions such as that of Leitao (2000) and that of Osborne et al (2004)] and Contiguity Argumentation Theory (CAT) were used to attach meaning to the collected data and to address the research questions.</span></span></p>

Made available in DSpace on 2016-04-29T13:18:02Z (GMT). No. of bitstreams: 1 Carolina E Perroni.pdf: 1145832 bytes, checksum: a05ff28512b53e57b44921cf8796556a (MD5) Previous issue date: 2006-12-20 / The present study investigated the effects of exposure to aversive events- controllable and incontrollable on the performance of young adults on an escape/avoidance task that followed such exposure. A second goal of the present study was to evaluate the possible effects of requests of verbal reports over the participants performances. Participants were 40 adults assigned to 3 groups: participants of the Escape Group were exposed to a Training Condition when an aversive sound could be turned off by his/hers responses. These participants were, then, exposed to a Test Condition (40 trials) where a second response turned off the same sound. Participants of the Yoked Group where exposed to a Training Condition similar to the Escape Group, but no responses were effective to turn off the sound. The same Test condition was programmed for participants off the Yoked and Control Groups. Participants off the Escape and Yoked Groups were assigned to 1 of 3 conditions of verbal report: they were asked if they know how to turn off the sound on the 40th trial, or 3 different trials, or on 23 trials of the Training Condition. Results did not suggest the common effects associated with helplessness. Results also showed that the verbal reports did not contribute to the emergence or to the prevention of helplessness. Results showed, on the other hand, that certain patterns of responding on the Training Condition were closely related to participants performances on the Test Condition / O presente estudo teve como objetivo investigar quais seriam os efeitos da exposição a eventos aversivos incontroláveis ou controláveis sobre o desempenho em uma tarefa posterior a tal exposição, em sujeitos humanos. Um segundo objetivo foi verificar se estes efeitos seriam alterados pela solicitação de relatos do desempenho aos participantes. Para tanto foi utilizado um procedimento de tríades, comumente usado em estudos que investigam desamparo. Os participantes também receberam, na fase de treino, solicitação de relatos acerca da tarefa e de seu desempenho. Participaram 40 adultos que foram distribuídos aleatoriamente em 7 grupos experimentais: Fuga, Emparelhado e Controle (com 8 participantes cada um) e Fuga 3, Emparelhado 3, Fuga 23 e Emparelhado 23 (com 4 participantes cada um). Os participantes (exceto do Grupo Controle) foram submetidos a duas fases experimentais (Treino e Teste), cada uma com 40 tentativas de apresentação de um som. Na Fase de Treino, os participantes dos Grupos Fuga, Fuga 3 e Fuga 23 podiam terminar o estímulo aversivo (som), caso teclassem 3 vezes a tecla F1. Para os participantes dos grupos Emparelhado, Emparelhado 3 e Emparelhado 23 nenhuma resposta era efetiva para o término do estímulo aversivo na Fase Treino. Todos esses participantes receberam em determinadas tentativas da fase de treino solicitação para que relatassem se sabiam como desligar o som: a diferença entre eles foi o momento de solicitação de relatos verbais e a quantidade de solicitações. Em uma tentativa de evitar comportamentos supersticiosos, as apresentações de sons de diferentes durações para os participantes dos Grupos Emparelhados na fase de treino foram randomizadas. Os resultados apontaram que os participantes dos Grupos Emparelhados tiveram melhor desempenho na Fase de Teste do que os participantes dos outros grupos, indicando que neste caso não se observou os efeitos da exposição a eventos aversivos incontroláveis que vêm sendo chamados de desamparo. Os participantes do grupo Fuga tiveram um melhor desempenho na Fase Teste em relação aos participantes do grupo Controle. Em relação às solicitações de relato verbal, dizer que sabia o que fazer não foi preditivo de sucesso na Fase de Teste. No entanto, as repetidas perguntas parecem ter tido o efeito de promover a descrição, pelo participante, de seu próprio comportamento, sugerindo que o perguntar poderia ter induzido algum comportamento de auto-observação. Além disso os resultados indicam que certos padrões de respostas na Fase de Treino, estão relacionados com o desempenho na Fase de Teste

<p><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi / mso-bidi-font-weight:bold">The basic premise of this study was that when a learner is confronted with two contradictory explanations of the same phenomenon, there is cognitive dissonance in the learner as the learner tries to determine which of the two explanations is correct. An argumentation-based instructional intervention programme (ABIIP) was created for and used on and by the Grade 10 learners in order to attempt to ameliorate this cognitive conflict. </span><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The purpose of this study was to determine the relative impact of that intervention programme on Grade 10 learners&rsquo / conceptions of lightning and thunder. The programme was designed to help learners to develop argumentative skills and use the acquired skills to negotiate and harmonise divergent and conflicting explanations of the nature of lightning and thunder that are propounded by different worldviews (Science and indigenous knowledge).</span><span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The research design was primarily a case study of 16 Grade 10 learners of the Xhosa ethnic group at a high school in the Eastern Cape Province of South Africa. The Xhosa people are a typical example of a people whose cultural values were undermined and whose voice was silenced by the colonisers and whose local knowledge has been repressed and replaced by forms of Western privileged knowledge and understandings but who remain, deeply and resolutely, steeped in their cultural values and practices, making them a classic example of a people who would battle to harmonise the indigenous and the scientific explanations of natural phenomena. The research instruments used were questionnaires which were administered to learners, educators, community leaders, indigenous knowledge holders and experts to solicit information on causes, dangers and prevention of lightning / individual and group activities as learners went through the lessons on both argumentation and on lightning / follow up interviews and discussions with learners individually or in groups to seek further clarification of the ideas the learners would have raised in their earlier responses to questionnaires or group discussions / guided and reflective essays by the learners to determine the learners&rsquo / levels of understanding of the major tenets of the two thought systems and the relationship between the two worldviews and to determine the qualitative gain, if any, that the learners got from the intervention programme / observation schedules used by the researcher during participant observation of group discussions and during the lessons on lightning / an achievement test on lightning / field notes used by the researcher for memoing observations and reflections as the research process proceeded / informal and serendipitous sources of information. <span style="font-size:12.0pt / line-height:150% / font-family: &quot / Times New Roman&quot / ,&quot / serif&quot / mso-bidi-font-family:&quot / Times New Roman&quot / mso-bidi-theme-font: minor-bidi">The collected data were analysed, mostly, qualitatively. Frequencies, percentages and t-test values were used to express and analyse quantitative data. Aspects of several analytical frameworks that included Toulmin&rsquo / s Argumentation Pattern (TAP) [and its modified versions such as that of Leitao (2000) and that of Osborne et al (2004)] and Contiguity Argumentation Theory (CAT) were used to attach meaning to the collected data and to address the research questions.</span></span></p>

Le carbure cémenté (WC-Co) est un système biphasé constitué de grains de carbure de tungstène enrobés dans un liant à base de cobalt. Dans ce matériau composite, qui allie donc la dureté du carbure à la résilience du cobalt, la maîtrise de la microstructure est un paramètre clef pour l’optimisation des propriétés mécaniques.Le but de ce travail est de mettre au jour les mécanismes régissant le développement des joint de grain et des joints de phase lors du frittage. L’effet de la teneur en liant, du taux de carbone et du temps de frittage ont été particulièrement étudiés.Ce travail est basée sur la caractérisation du matériau par EBSD (Electron BackScattered Diffraction), une méthode qui facilite la séparation des grains et donc l’utilisation de techniques d’analyse d’image pour étudier la microstructure. En outre un programme basé sur les données d’orientation des grains collectées par EBSD et permettant l’analyse de la texturation des joints de grain et des joints de phase a été développé pour cette étude.L’étude de la contiguité montre qu’elle ne dépend pas du taux de frittage ni de la teneur en carbone du liant, mais essentiellement de la fraction volumique de liant. Cela implique que l’encombrement et l’imbrication des particules sont les principaux paramètres entrant en compte dans l’établissement de la contiguité. Un grossissement plus rapide et plus marqué a été observé dans les échantillons riches en carbone, ainsi que dans ceux présentant un fort taux de liant. Un grossissement anormal a été observé dans les échantillons riches en carbone et à fort taux de liant. La désorientation aux joints de grains est caractérisée par un couple axe/angle décrivant la rotation liant les deux cristaux. L’étude de la distribution des axes a révélé que trois rotations sont particulièrement abondantes : celles autour de [101 ̅0], [21 ̅1 ̅0] et [0001]. Elles représentent environ 30% de la surface totale des joints de grains. Pour chacune des rotations particulières ont été détectées : [101 ̅0]/90°, [21 ̅1 ̅0] / (48°- 60°- 90°) et [0001]/90°. L’étude de la géométrie de ces joints suggère que leur remarquable stabilité est due au fort taux de cohérence dans le plan de joint. L’analyse statistique des plans de joint de grain et de joint de phase montre que la plupart d’entre eux correspond à un plan basal ou prismatique pour au moins l’un des deux grains (70% environ de la surface totale de joint de grain, et 50% environ de la surface totale de joint de phase). Sur la base de ces résultats, un scénario décrivant l’évolution de la microstructure durant le frittage est finalement proposé. / WC-Co cemented carbide is a two phase system constituted of a cobalt based binder matrix embedding hard tungsten carbide grains. This material is especially used in fields such as metal cutting or mining, where high mechanical properties are required. Therefore, the microstructure is a key parameter to control to optimize the mechanical properties of the alloy.This work aims at understanding the mechanisms of grain boundary and phase boundary development during sintering, and how they may influence the final microstructure. The effect of the binder content, carbon content and sintering time was especially investigated.Electron BackScattered Diffraction characterization was chosen to conduct this study. First because the precise separation of grains in the resulting images makes possible automation of the measurements, and thus allows a statistical analysis of several microstructural parameters (as grain size, contiguity) on numerous samples. Secondly because orientation data collected by this way make possible the analysis of grain boundary and phase boundary texture. To this end, an automated method was developed for analysis of grain boundaries and estimation of remarkable boundary planes fraction from 2D EBSD measurements.The study of contiguity shows that it does not depend on sintering time or carbon content in the binder, but essentially of the carbide grain volume fraction. This result implies that impingement is the first order parameter in the evolution of contiguity. Grains appear to grow faster and in a larger extent in samples with a carbon rich binder, as well as in high binder content samples. Abnormal grain growth seems to be favored by high binder content in carbon rich samples. All grain boundaries were characterized by a couple of rotation axis and misorientation angle. Three particular rotation axes were identified: [101 ̅0], [21 ̅1 ̅0] and [0001]. They represent around 30% of the total grain boundary surface area. In addition, specific rotations were found to be particularly abundant in the microstructure: [101 ̅0]/90°, [21 ̅1 ̅0] / (48°- 60°- 90°) and [0001]/90°.A study of their geometry suggests that their stability would be due to a particularly coherent boundary plane. A statistical analysis shows that most grain boundaries and phase boundaries have a habit plane parallel to a basal or prismatic plane (about 70% of the total grain boundary surface area and 50% of the total phase boundary area. Finally, a scenario is proposed for the microstructure development model during sintering of cemented carbides on the basis of the results.

Magister Educationis - MEd / The research reported in this paper involves the use of dialogical argumentation in scientific context with 7-9 year olds as part of teaching and learning in primary classrooms. To develop an understanding of scientific concepts, four suitable collaborative activities on river pollution were used as a stimulus to effectively engage learners in scientific reasoning and use evidence for decision-making through cognitive harmonization. The research, involved four groups of five children each. Data were collected through analysis of children’s Water Pollution Questionnaire (WPQ), classroom observation, documentation of field notes, conversations and focus group interviews. The study found that all groups were able to engage in the activities to some extent, but that good quality argumentation develops when children are familiar with working in this manner. This study sought to investigate the opportunities, possibilities and challenges associated with a dialogical argumentation teaching and learning approach in a primary school science class A mapping technique was used to analyze the children’s discussions and identify the quality of their different “levels” of argument. This study confirmed that an argumentation based instruction was an effective way of enhancing learners’ understanding of river pollution. The learners’ listening skills improved tremendously and they were actively involve during discussions and provided claims with valid grounds or reasons. They were also very enthusiastic and challenged each other’s claims during these argumentation lessons, but most of all was the enjoyment that was visible on their young faces. Further research needs to be carried out over a longer period to determine the effectiveness of an argumentation based instruction. / South Africa