L'environnement semble jouer un rôle important dans le développement de la discrimination des stimuli sociaux. Le développement précoce de la discrimination des stimuli sociaux tels que les visages et les expressions faciales a suscité de nombreuses recherches. Par ailleurs, les individus avec autisme ne semblent pas répondre aux stimuli sociaux de la même façon que des individus au fonctionnement normal et ces différences apparaissent de manière précoce.Cependant, les recherches actuelles ne nous fournissent pas assez d'éléments dur la façon dont cette discrimination se met en place, en particulier sur les régions du visage qui sont importantes pour la discrimination. C'est ce point que nous avons choisi d'étudier au cours de cette thèse, auprès d'enfants avec autisme. Les travaux effectués dans le cadre de cette thèse ont eu pour objectifs tout d'abord de développer une tâche permettant de mesurer les éléments du visage impliqués dans la discrimination d'expressions faciales chez des enfants au développement typique et des enfants avec autisme (Etudes 1 & 2). Puis, nous avons mis en place une tâche ayant pour objectif d'évaluer l'importance des régions des yeux et de la bouche auprès d'enfants avec autisme et de montrer l'effet de la modification des patterns d'observation des visages sur la façon dont les éléments du visage exercent un contrôle discriminatif sur les réponses des enfants avec autisme (Etudes 3 & 4). Ces résultats sont discutés au regard de l'importance de l'environnement dans la mise en place de la discrimination des stimuli sociaux. Les implications concernant les recherches chez l'enfant au développement typique seront discutées, ainsi que la place de la direction du regard, en plus de l'expression des yeux, comme élément discriminatif / The role of the environment has been demonstrated in the development of the discrimination of social stimuli. The discrimination of social stimuli such as faces and facial expressions have been extensively studied during the past decades. In addition, people with autism show atypical responses to social stimuli compared to typically functioning individuals. Those discrepancies can be seen very early in life. However, there is still much to know about how this learning takes place, particularly on the face parts that are relevant for the discrimination. The focus of this work is to study more precisely how face parts come to control the responses of children with autism. The goal of our studies was first, to build a task to measure precisely which parts of the face are involved in facial expressions discrimination in children with autism and in typically developing children (Experiments 1 & 2). Subsequently, we devised a task which evaluated the role of the eyes' and mouth regions in children with autism and typically developing children in order to see the effect of the modification of observing patterns of faces on the way eyes and mouth come to control the responses of children with autism (Experiments 3 & 4). Results are discussed in line with the role of the environment in participating in the development of facial expressions discrimination. Implications for the study in early facial expression discrimination learning in typically developing children are discussed. Direction of gaze, in adition to the eyes region expression, is discussed as a relevant element for the discrimination of facial stimuli.

Pas de résumé / Pas de résumé

Male mammals compete for reproductive access to females. Gaining and maintaining this access can be stressful and anxiety-provoking. In humans, anxiety and associated protective behaviors can manifest as jealousy. Physiological stress is likely to increase in relation to jealousy as it does with anxiety. Hypothetically, higher levels of anxiety and cortisol may indicate, and may even promote, strong territorial or jealous behavior. Chronically elevated cortisol has been shown to be deleterious to prefrontal and hippocampal neurons and result in emotional and stress-response dysregulation. In very anxious and jealous individuals, chronic stress activation could further promote these tendencies via emotional disinhibition. Cortisol production also related to vasopressin (AVP) levels and AVP has been shown to increase mate preference and territoriality. Furthermore, physiological measures may be more valid than self-report of less socially desirable behaviors such as jealousy and anxiety. As a preliminary study, we measured salivary cortisol, heart-rate, and blood pressure in relation to self-reported anxiety and jealousy in healthy men and women in response to threatening male faces paired with smiling female faces. Elevated anxiety positively predicted jealousy in men but not women. Anxiety and jealousy also predicted elevated heart rate and blood pressure. Cortisol levels in response to the threat task and in relation to jealousy approached statistical significance (ps < 0.07) and suggest the need for a larger sample size.

D.Ing. / This thesis deals with an investigation into facial recognition and some variables that influence the performance of such a system. Firstly there is an investigation into the influence of image variability on the overall recognition performance of a system and secondly the performance and subsequent suitability of a neural network based system is tested. Both tests are carried out on two distinctly different databases, one more variable than the other. The results indicate that the greater the amount of variability the more negatively affected is the performance rating of a specific facial recognition system. The results further indicate the success with the implementation of a neural network system over a more conventional statistical system.

Many views to facial expression recognition exist. This work presents one of approaches. Existing methods of human face representation by model are discussed. The AAM method, where final appearance model is created from model of shape and model of texture is proposed. Model of shape and model of texture is created by statistic analysis. Using this representation, an effective method is achieved that is complexity of information for searched face in static image. Choice and combination of suitable features for classification of facial expression is principle for facial expression recognition based on AAM. Two approaches of facial expression classification are compared. Classification based on LDA and classification based on SVM. These methods with necessary face localization using AdaBoost form an automated face recognizer in image.

L'objectif d'amélioration des performances de cellules solaires sur des substrats de silicium cristallin de plus en plus en minces (< 200 µm) est indispensable à la réduction des coûts du module et donc à l'essor du photovoltaïque à l'échelle mondiale. Cette thèse se propose de répondre à la problématique d'amincissement des plaquettes sur substrats monocristallins (Cz) de type p de grande surface (239 cm2 - 180 µm) par le développement d'une structure en face arrière capable de générer un rendement de conversion élevé tout en limitant le degré de complexité du procédé de fabrication de la cellule. La solution explorée est celle des cellules à face arrière passivée et contacts localisés et les schémas de passivation étudiés s'appuient sur l'utilisation d'empilements diélectriques à base d'oxydes de silicium (SiO2) et d'aluminium (Al2O3) couplés au nitrure de silicium (SiNx). Ces travaux ont pour objectif d'optimiser les propriétés de passivation des couches diélectriques tout autant que les briques technologiques nécessaires à leur intégration dans la structure de cellule finale (conditionnement de surface, ablation laser sélective, métallisation par sérigraphie). Le procédé de fabrication résultant a permis d'obtenir des cellules avec un rendement de conversion de 19.1% pour l'empilement SiO2/SiNx. Il est cependant démontré que les limitations des performances de cette structure peuvent être partiellement compensées en introduisant une couche d'alumine, permettant d'atteindre un rendement remarquable de 19.5% (+0.4% par rapport à une structure standard). / Improving the solar cell efficiency on thin wafers (< 200 µm) has become a must in the industry in order to reduce the module cost and enhance the photovoltaics field growth worldwide. This work addresses the issues regarding the thickness reduction of large monocrystalline p-type wafers (239 cm2 - 180 µm) by developing a back side architecture capable of increasing the efficiency while limiting the cell fabrication level of complexity. Thus back passivated and local contacts, also known as PERC-type, solar cells are investigated. Those include passivation schemes relying on the use of dielectric stacks based on silicon oxide (SiO2), aluminum oxide (Al2O3) both coupled with silicon nitride layers (SiNx). This PhD study attempts to carry out an optimization of the passivation properties as well as of the technological steps required for a proper integration in the final cell structure (surface preparation, selective laser ablation, screen-printing metallization). The resulting optimized process led to the fabrication of solar cells displaying an 19.1% conversion efficiency by using SiO2/SiNx layers. Nevertheless it was shown evidence that the limited electrical performances can be overcome by introducing an Al2O3 layer, eventually reaching a remarkable 19.5% efficiency. This represents an absolute gain efficiency of +0.4% compared to the standard full-area Al-BSF solar cell architecture.

Cette thèse est composée d’un essai sur la relation entre l’aversion au risque des individus et leur décision de migration et de deux essais sur l’importance de sauver la face et la réciprocité en termes d’image.Le premier essai s’appuie sur une expérience de terrain en Chine afin d’étudier si le statut migratoire est corrélé aux préférences en matière de risque, ambiguïté et compétitivité. Il montre que les migrants et les non-migrants ne présentent pas de différences dans leurs préférences concernant le risque et l’ambiguïté dans des loteries standard. En revanche, les migrants ont une attitude plus compétitive face à une incertitude stratégique dans un jeu d’entrée sur un marché.Le deuxième essai étudie si les individus sont prêts à sacrifier des ressources pour sauver la face en payant pour éviter l'exposition publique du membre de leur groupe le moins productif à l’aide d’une expérience de laboratoire à effort réel. La majorité des individus sont prêts à payer pour préserver à la fois leur image et celle des autres. Ce résultat est robuste à une manipulation de l'identité de groupe. Le sentiment de honte toujours présent à la suite d’une exposition publique évince la motivation intrinsèque.Le troisième essai étudie la récompense de la bienveillance et la punition de l’égoïsme en termes d'image. Il montre que les individus récompensent la bienveillance et expriment de la réciprocité vis-à-vis de ceux qui ont préservé leur image ou celle d’un tiers. En revanche, l’égoïsme de ceux qui ne font pas d’effort pour sauver la face des autres n’est pas sanctionné. / This thesis consists of one essay on the relationship between risk attitudes and migration and two essays investigating the importance of saving face and reciprocity in terms of social image.The first essay is based on a field experiment conducted in China to study whether the migration status is correlated with one's preferences regarding risk, ambiguity, and competitiveness. It shows that migrants and stayers exhibit no difference in their preferences over risk and ambiguity as elicited with standard lottery choices. In contrast, migrants are significantly more likely to enter competitive markets in the context of strategic uncertainty. The second essay studies whether individuals forego resources to avoid the public exposure of the worst performer in their group in a real-effort laboratory experiment. A majority of individuals are willing to pay to preserve both self- and others’ image. This finding is robust to a manipulation of group identity. While the threat of exposure encourages effort, public exposure and a feeling of shame crowd out future intrinsic motivation.The third essay investigates whether individuals reward kindness and punish selfishness in terms of image. It shows that people reward kindness and reciprocate to people who have saved their face or others’ face. However, selfish behavior in terms of image saving is not sanctioned.

O reconhecimento de expressões faciais de emoções (REFE) é essencial para a interação social cotidiana e a comunicação interpessoal e é considerado um aspecto importante da cognição social. É uma condição inata e universal nos seres humanos, mas pode ser influenciada por diferentes variáveis sociodemográficas como sexo, idade e escolaridade. Apesar do número expressivo de estudos relacionados ao REFE, não existe uma tarefa padrão utilizada em sua avaliação e as que se encontram disponíveis nem sempre passaram por um procedimento de padronização e normatização. O presente estudo propôs-se a avaliar comparativamente três diferentes tarefas de REFE utilizadas no contexto brasileiro, e disponibilizar um procedimento normatizado às características socioculturais de nossa população, considerando as variáveis anteriormente destacadas, em uma amostra da população geral, estimada estatisticamente (n=240). Para composição desta amostra, foram incluídos sujeitos de ambos os sexos, com idade entre 18 e 75 anos, sem prejuízos intelectuais e com variados níveis de escolaridade. A coleta de dados foi realizada individualmente. Os dados referentes a acurácia, tempo de resposta e intensidade para o reconhecimento das expressões foram salvos automaticamente pelo programa computacional gerador da atividade e alocados manualmente em um banco de dados. Utilizou-se para as análises estatísticas o programa Statistical Package for the Social Sciences (SPSS). Os dados sociodemográficos da amostra e aqueles relacionados ao desempenho nas tarefas foram analisados através de testes estatísticos descritivos e paramétricos (teste t de Student, Anova, Qui-Quadrado e Teste de Correlação de Pearson). O tamanho de efeito das diferenças foi calculado por meio do eta2 parcial e do d de Cohen. Para realizar o procedimento de normatização calculou-se a distribuição dos dados em percentis de acordo com cada tarefa e grupo estudado. Os resultados apontaram para uma ligeira superioridade das mulheres no REFE em tarefas dinâmicas, maior prejuízo do grupo na faixa etária dos 61-75 anos independente da tarefa, e menor acurácia dos sujeitos com menor escolaridade na tarefa estática. No que diz respeito às tarefas utilizadas observou-se que a acurácia foi maior na tarefa dinâmica preto e branco e que a tarefa estática exigiu maior tempo de resposta mas menor intensidade de emoção para o REFE. Em análises comparativas a tarefa dinâmica pareceu ser aquela com maior proximidade à condição real de contato humano. Considerando que a TDPB foi aquela com maior média de acerto considerou-se esta a mais apropriada para uso no nosso contexto. O estudo apresentou/disponibilizou ainda dados normativos para o contexto brasileiro em função do sexo, idade e escolaridade, que poderão servir como parâmetro de comparação em outros estudos clínicos, bem como para pesquisa de avaliação do reconhecimento emocional. / The recognition of facial expressions of emotions (REFE) is essential for everyday social interaction and interpersonal communication and is considered an important aspect of social cognition. It is an innate and universal condition in humans, but it can be influenced by different sociodemographic variables such as sex, age and schooling. Despite the significant number of studies related to the REFE, there is no standard task used in its evaluation and those that are available do not always undergo a procedure of standardization and normatization. The aim of this study was to compare three different REFE tasks used in the Brazilian context and to provide a normalized procedure to the sociocultural characteristics of our population, considering the variables previously mentioned in a statistically significant sample of the general population (n= 240 ). For the composition of this sample, subjects of both genders, aged between 18 and 75 years, without intellectual losses and with varying levels of schooling were included. Data collection was done individually. The data referring to the accuracy, response time and intensity for the recognition of the expressions were automatically saved by the computational program generating the activity and manually allocated in a database. Statistical Package for the Social Sciences (SPSS) was used for statistical analysis. The sociodemographic data of the sample and those related to performance in the tasks were analyzed through descriptive and parametric statistical tests (Student\'s t test, Anova, Chi-Square and Pearson\'s correlation test). The effect size of the differences was calculated by means of partial eta2 and Cohen\'s d. To perform the standardization procedure, the distribution of the data in percentiles was calculated according to each task and group studied. The results pointed to a slight superiority of the women in the REFE in dynamic tasks, greater loss of the group in the age group of 61-75 years independent of the task, and lower accuracy of the subjects with less schooling in the static task. Regarding the tasks used it was observed that the accuracy was higher in the black and white dynamic task and that the static task required a longer response time but a lower intensity of emotion for the REFE. In comparative analyzes the dynamic task seemed to be the one with the closest proximity to the real condition of human contact. Considering that the TDPB was the one with the highest average accuracy, it was considered that this was the most appropriate for use in our context. The study presented / provided normative data for the Brazilian context based on sex, age and schooling, which may serve as a benchmark in other clinical studies, as well as for the evaluation of emotional recognition.

Faculty of Engineering and Built Enviroment School of Mining Engineering 0315711f musakale@egoli.min.wits.ac.za / Rockfalls are a significant risk in open pit mines. Once movement of a rock perched on the top of a slope (bench) has been initiated, the most important factor controlling its fall trajectory is the geometry of the slope (bench). The best possible knowledge of rockfall trajectories and energies is important in order to determine accurate risk zoning and for the design and construction of adequate defence systems near the threatened areas. This study attempts to determine the influence of bench geometries, and the coefficient of restitution of rock, on rockfall behaviour. A study of literature was carried out to review previous studies and other relevant information on rockfalls and their analysis. The literature may be divided into two categories: experimental methods involving physical modelling, and computer models involving rockfall analyses using computers analysis methods. Rockfall computer simulation is considered to be applicable, quick to carry out and reproducible. The accuracy of the results depends on the knowledge of site conditions and slope geometry. The use of the Modified Ritchie criterion for the design of catch benches in open pit mines was also investigated. The assessment of bounce height, maximum run-out distance and kinetic energy achieved during the fall of rocks on the catch bench were the bases of the evaluation of the results obtained in this project. The computer program, Rocfall Version 4, was used for the purposes of the research. The following parameter variables were considered in the analyses: three types of rock; slopes with three stack configurations; four bench heights; and four bench face angles. The results show that, for all stack configurations and rock types, the maximum runout distance and maximum bounce height increase as functions of bench height at a specific bench face angle. A single bench configuration provides a maximum run-out distance of falling rocks larger than the value determined using the Modified Ritchie criterion for all rock types and bench face angles. Multiple bench stack configurations provide maximum run-out distances less than the value determined using the Modified Ritchie criterion only for the 90o bench face angle in all rock types; those with 60o, 70o and 80o bench face angle provide a larger maximum run-out distance. Therefore, the validity of the Modified Ritchie criterion for the design of catch bench widths in open pit mines with inclined benches must be questioned. According to Ritchie’s study (1963), rocks that fall in trajectory (free fall) seldom give high bounces after impact on a catch bench. This project shows that this finding is valid for rocks with low coefficients of normal restitution. Rocks with lower coefficients of normal restitution provide larger run-out distances with flatter bench face angles compared with rocks with higher coefficients. In contrast, rocks with higher coefficients provide larger run-out distances than those with lower coefficients for steeper angles. The consideration of the influence of geometry (shape) of falling rocks on rockfall behaviour showed that, for a flatter slope, as could logically be expected, the maximum run-out distance is greatest for rounder rocks and smallest for flatter slabby iv rocks. This is due to the fact that on a flatter slope, the mode of falling of rounder rocks is rolling down the slope. This mode provides essentially no resistance to motion, resulting in largest maximum run-out distance. In contrast, for long flat slabs, the mode of movement will be sliding, which results in a smaller maximum run-out distance. The maximum run-out distance as function of rock shape reduces as the normal coefficient of restitution increases. For all rock types, the maximum bounce height reduces as a function of the friction angle for flatter slopes. This is due to the fact that rocks are in contact with the slope during the rockfall. As the coefficient of normal restitution increases, an increase in the maximum bounce height results.

The need to establish baseline artisan productivities in the South African employmentintensive construction sector stems from the fact that these productivity norms have not been reviewed on a frequent basis. To others, these productivity norms hardly exist. With both scenarios, it is difficult to compare artisan productivity trends in the last fifty years to the trend of international standards. Constructive efforts have been made in this document to highlight the productivity norms that have existed within the building industry since the 1950’s. A similar exercise has been done for the USA and other European countries, notably the UK. A comparison of these trends of productivity norms has revealed that the current artisan productivity figures in South Africa are the lowest since the 1950’s. Again, they are the lowest amongst these countries. In the 1950’s, the artisan productivity norms in South Africa were quite close and thus comparable to the European countries but the gap has widened thereafter. The USA has generally experienced a continuous improvement in their productivity norms on an annual basis and this has been due partly to the improvement in the working tools of artisans. Another important factor is the poor quality of artisanship. The constructive effort being made by the South African government towards ensuring the sustainability of small and emerging contractors in employment-intensive construction is not in balance; the Contractor learnership programme of the Expanded Public Works Programme (EPWP) must go hand-in- hand with an artisan learnership programme. Key words: baseline artisan productivity, task-group, work-study, construction, face & stock-bricks, plastering, painting and tiling.