Highly selective and sensitive phosphate sensors have been fabricated by constructing a solid membrane disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO4) and powdered copper (Cu). Both binary and ternary electrode systems are produced depending on their composition. The ternary membranes exhibit greater selectivity over a wide range of concentrations. The ternary electrode with the composition 25% AlPO4, 25% Cu and 50% Al was selected as our preferred electrode. The newly fabricated ternary membrane phosphate selective electrodes exhibited linear potential response in the concentration range of 1.0 × 10−6 to 1.0 × 10−1 mol L−1. The electrodes also exhibit a fast response time of <60 s. Their detection limit is 1.0 × 10−6 mol L−1. The unique feature of the described electrodes is their ability to maintain a steady and reproducible response in the absence of an ionic strength control. The electrodes have a long lifetime and can be stored in air when not in use. The selectivity of the new phosphate selective electrodes with respect to other common ions is excellent. The results obtained provide further insight into the working principles of the newly fabricated phosphate selective electrodes. Dephosphorylation and phosphorylation reactions were monitored using the preferred phosphate selective electrode. The following reactions were studied and inferences drawn; (a) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[OH(PO2O)]2- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[OH(PO2O)]2- ratios.(b) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[O2NC6H4PO2(O)(OH)]- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[O2NC6H4PO2(O)(OH)]- ratios. (c) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)2O]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)2O]2- ratios, and (d) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)3O2]3- for the 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)3O2]3- ratios. Further insight into dephosphorylation and phosphorylation reactions is unravelled by the novel phosphate selective electrode monitoring. *For clarity of the complexes utilized, see chapter 4, table 4.1. KEY WORDS; Dephosphorylation, phosphorylation, ion selective electrodes, phosphate ion selective electrode, decontamination, electromotive force, potential difference, activity, concentration, selectivity coefficient, calibration, ionic strength, hydrolysis, inorganic phosphates, nitrophenylphosphate, pyrophosphate, tripolyphosphate, organophosphate esters. / Chemistry / D. Phil (Chemistry)

Thesis advisor: Amir H. Hoveyda / Abstract Chapter 1: Development of Efficient and Kinetically E-Selective Cross-Metathesis to Generate Alkenyl Halides We have devised a broadly applicable strategy to achieve kinetically E-selective cross-metathesis to generate a valuable set of E-alkenyl chlorides and fluorides in high efficiency. The synthetic utility was demonstrated through several concise syntheses of E-alkenyl chloride and fluoride precursors to biologically active molecules. The design principles delineated in this study are expected to initiate a wider range of efficient and kinetically controlled E-selective olefin metathesis processes where there is a diminished preference for the E isomer such as macrocyclic ring-closing metathesis. Chapter 2: Development of Efficient and Kinetically E-Selective Macrocyclic Ring-Closing Metathesis We devised a strategy to achieve high E selectivity in ring-closing metathesis to afford E-macrocyclic alkenes of various ring sizes regardless of the associated thermodynamic preferences. The key findings revealed that E-alkenylB(pin), widely recognized for its broad use in catalytic cross-coupling chemistry, possesses the appropriate steric and electronic attributes to serve as a suitable cross-partner in ring-closing metathesis with Mo alkylidenes. Synthetic utility was demonstrated through ring-closing metathesis at a late stage of a multi-step route. The investigation described herein offers a practical solution to a compelling problem in olefin metathesis, further elevating the utility of this widely used transformation. Chapter 3: Stereoselective Synthesis of E- and Z-Trisubstituted Alkenes by Combining Stereoretentive Catalytic Cross-Metathesis and Catalytic Cross-Coupling We introduced a general solution to a longstanding and compelling problem in olefin metathesis: a broadly applicable strategy for the reliable and efficient synthesis of acyclic E- and Z-trisubstituted alkenyl halides. Complications resulted from the formation of an unstable methylidene species or less reactive disubstituted alkylidene complexes can be addressed by utilizing a stereo-defined E- or Z-trisubstituted alkene and a 1,2-disubstituted olefin as substrates. By merging two central catalytic transformations in organic synthesis, cross-coupling and CM, various E- or Z-trisubstituted alkenyl chloride and bromides were readily accessed by the same catalytic system without the need for directing groups. The synthetic utility of the present protocol was demonstrated through several concise and efficient synthesis of biologically active natural products/synthetic precursors. Notably, the E- or Z-trisubstituted alkenyl halides prepared by CM may be readily converted to other trisubstituted olefins with complete retention of stereochemical purity by means of a second cross-coupling reaction. Based on the new findings, we revisited previously unaddressed problems and establish that readily available isoprenoid alkenes can serve as a suitable surrogate for unhindered terminal alkenes in CM. Chapter 4: In situ Protection/Deprotection for Catalytic Olefin Metathesis in the Presence of Polar Protic Functional Groups We demonstrated that protic groups such as alcohols and carboxylic acids that are problematic with high-oxidation-state alkylidenes could be effectively masked in situ prior to CM reactions by an appropriate borane reagent. The commercial sample of alkenes that are usually contaminated with protic impurities could be ‘purified’ in situ by a sub-stoichiometric amount of pinacolborane. Deprotection of the in situ boron-based protecting group proceeded under mild conditions and could be performed in the same vessel. The one-pot protection/cross-metathesis/deprotection of alcohol and carboxylic acid-containing alkenes described herein is likely to have an impact on the diversity of organic molecules that can be prepared in a laboratory setting. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Introdução - No Brasil, o Programa Municipal de Coleta Seletiva (PMCS) pode ser executado pelo próprio município, por empresa contratada ou em parceria com uma organização de catadores. Mais de 50 por cento dos PMCS no Estado de São Paulo é realizado por essas organizações. Logo, a maioria dos estudos foca-se nessas organizações, mas os municípios que não possuem parceria também precisam ser estudados. Objetivo - Analisar e avaliar PMCS realizados sem parceria com organização de catadores, na perspectiva de sustentabilidade socioeconômica, ambiental e institucional. Métodos - Para esse estudo, 7 municípios foram selecionados conforme os critérios porte do município e tempo de existência mínima de 2 anos do PMCS, a partir de dados do Sistema Nacional de Informações sobre Saneamento e ligações telefônicas Os municípios estudados foram divididos em pequeno (4) e grande (3) porte. Os responsáveis pelo PMCS foram entrevistados, com base em questionário semiestruturado. Os resultados permitiram caracterizar os PMCS e alimentar 13 indicadores e 2 índices de sustentabilidade de PMCS. Resultados - Foram identificados 4 arranjos institucionais de execução dos PMCS, envolvendo a prefeitura municipal e empresa terceirizada. Os municípios de grande porte apresentam mais indicadores favoráveis à sustentabilidade que os de pequeno porte. A produtividade é maior nos de grande porte, mas a remuneração é melhor nos pequenos. Por outro lado, esses apresentam melhor taxa de recuperação, adesão e atendimento e menor taxa de rejeito, o que eleva o índice de sustentabilidade. Para os 2 índices considerados, os municípios de pequeno porte são mais favoráveis à sustentabilidade que os de grande porte. Conclusões - Os municípios de pequeno porte apresentam maior tendência à sustentabilidade nos indicadores considerados mais importantes num PMCS sem parceria com organizações de catadores. Embora a Política Nacional de Resíduos Sólidos priorize PMCS em parceria com organização de catadores, arranjos sem parceria são possíveis e apresentam-se também sustentáveis na sustentabilidade da valorização de materiais recicláveis. / Introduction - In Brazil, the Municipal Program for Selective Collection (MPSC) can be performed by the municipality itself, by a company contracted or through a partnership with waste pickers organization. More than 50 per cent of the MPSC in São Paulo State is performed by these organizations. Then, most of the studies focuses on these organizations, but the municipalities that dont have partnership also need to be studied. Objective - To analyze and evaluate MPSC performed without partnership with waste pickers organization, through the perspective of socioeconomic, environmental and institutional sustainability. Methods For this study, 7 municipalities were selected according to the criteria: size and minimum time of existence, using data form the National Sanitation Information System and phone calls. The municipalities studied were divided into small (4) and large (3) sizes. The people responsible for MPSC were interviewed, based on a semi-structured questionnaire. The results allowed to characterize the MPSC and feed 13 indicators and 2 MPSC sustainability indexes. Results - Were identified 4 institutional arrangements of MPCS, involving the city government and outsourcing company. The large cities have more favorable indicators of sustainability than the small ones. The productivity is bigger in large municipalities, but the payment (compensation) is better in the small ones. Nevertheless, these present higher recovery rate, adherence and attendance and lower reject rate, what raises the sustainability index. For the 2 index considered the small municipalities are more sustainability favorable than the large ones. Conclusions - Small municipalities are more likely to sustainability for those indicators considered more important in a MPCS without a partnership with waste pickers organizations. Although the National Solid Waste Policy prioritizes MPCS through a partnership with waste pickers organization, arrangements without these kind of partnership are possible and also are sustainable for the recovery of recyclable materials.

A series of bicyclic peptides have been designed and synthesized to provide ammonium ion complexation sites via hydrogen bonding in a tetrahedral geometry. Molecular modeling dynamics and electrostatics studies indicate that target compounds 1d-6d may provide better selectivity for ammonium ions over potassium ions than the ammonium ionophore currently used for blood analysis applications, nonactin. Attempts to synthesize 1d, cyclo(L-Glu1�D-Val2�L-Ala3�D-Lys4�D-Val5�L-Val6)-cyclo-(1ã-4å), were unsuccessful due to poor solubility of the synthetic intermediates. This led to the design of 2d-6d in which specific amino acid residues were chosen to provide higher solubility. Compound 2d, cyclo(L-Glu1�D-Ala2�D-Ala3�L-Lys4�D-Ala5�L-Ala6)-cyclo-(1ã-4å), was successfully synthesized, but was also too insoluble for characterization or testing in an ion selective electrode (ISE) sensor format. Compound 6d, cyclo(L-Glu1�D-Leu2�Aib3�L-Lys4�D-Leu5�D-Ala6)-cyclo-(1ã-4å), was successfully synthesized and characterized. When 6d was incorporated into an ISE sensor and tested as an ammonium ionophore, results indicated that the bicyclic peptide lacked solubility in the ISE membrane. A 13C-NMR study has been initiated in order to evaluate selectivity of 6d for ammonium over potassium and sodium cations in solution. Preliminary results with the potassium ionophore valinomycin as a control have been completed.

Wong Chi Ming. / "August 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 182-215). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Os atuais recursos tecnológicos têm favorecido o desenvolvimento de diferentes métodos de disseminação seletiva de informações, permitindo, inclusive, maior autonomia aos usuários. Neste contexto, teve-se como objetivo analisar o processo de disseminação seletiva de informações, por meio de estudo exploratório em uma biblioteca digital federada, visando a valorizar a mediação por intervenção humana. Para tanto, realizou-se uma revisão bibliográfica sobre os temas disseminação seletiva de informações e bibliotecas digitais federadas, assumindo-se a visão de mediação, a partir da perspectiva de Kuhlthau. Realizou-se, ainda, um estudo de caso no NEP (New Economics Papers), um serviço da biblioteca digital RePEc (Research Papers in Economics), sendo a coleta de dados realizada a partir de variadas fontes de evidências. Em relação ao questionário usado na coleta de dados, dos 61 editores temáticos voluntários, que faziam a seleção de informações a serem disseminadas nas categorias temáticas do NEP, contou-se com 41 respondentes. Para a análise dos dados, derivados das respostas do questionário, utilizou-se análise de conteúdo, buscando a identificação de fatores relevantes relacionados às variáveis analisadas (interação entre mediadores e usuários, seleção dos documentos, motivação dos mediadores, impacto do serviço e perfil dos mediadores), promovendo, quando necessário, o agrupamento de respostas semelhantes em categorias, enfatizando a ocorrência de determinado fator e não sua freqüência. Dentre os resultados destacam-se: caracterização de três distintas gerações de serviços de disseminação seletiva de informações, em relação ao desenvolvimento tecnológico; identificação de distintas possibilidades e níveis de mediação nos serviços de disseminação seletiva de informações; identificação de fatores correspondentes às variáveis analisadas em relação à mediação realizada por meio de intervenção humana, em serviços de disseminação seletiva de informações em bibliotecas digitais federadas. Conclui-se que, embora a tecnologia possibilite a autonomia por parte do usuário, em relação aos serviços de disseminação seletiva de informações, é viável um planejamento prévio que reconheça a possibilidade de se atuar em diferentes níveis de mediação a serem adotados, uma vez que a presença da mediação pode agregar valor ao serviço. / Technological advances has facilitated the development of various resources enabling the implementation of selective dissemination of information services which offer autonomy to users. Thus, the objective was to analyze the process of selective dissemination of information, through an exploratory study in a federated digital library, aiming to enhance the mediation by human intervention. For this, a literature review was made comprising the themes: selective dissemination of information and digital libraries, assuming mediation from the perspective of Kuhlthau. Also, it was conducted a case study based on NEP (New Economics Papers), a service of the digital library RePEc (Research Papers in Economics) being the data collection made from various sources of evidence. Regarding the questionnaire used in the data collection, out of 61 volunteers, who were responsible for selecting information on the NEP themes to be disseminated, 41 responded the questionnaire. For data analysis, derived from responses from the questionnaires, it was used content analysis, seeking to identify relevant factors related to the analyzed variables (interaction between mediators and users, documents\' selection, mediators\' motivation, services impact and mediators\' profile), promoting, when necessary, the grouping of similar responses into categories, emphasizing thus, the occurrence of a particular factor and not it\'s frequency. Among the results are: characterization of three different generations of selective dissemination of information services, in relation to technological development; identification of different possibilities and levels of mediation in services of selective dissemination of information; identification of factors related to the variables analyzed, in relation to the mediation made by means of human intervention in services of selective dissemination of information. It is found that, although the technology allows the autonomy of the user, referring to the selective dissemination of information services, it is possible to make a previous planning that recognize the possibility of acting from different levels of mediation to be adopted, since the presence of mediation can add value to the service.

Os atuais recursos tecnológicos têm favorecido o desenvolvimento de diferentes métodos de disseminação seletiva de informações, permitindo, inclusive, maior autonomia aos usuários. Neste contexto, teve-se como objetivo analisar o processo de disseminação seletiva de informações, por meio de estudo exploratório em uma biblioteca digital federada, visando a valorizar a mediação por intervenção humana. Para tanto, realizou-se uma revisão bibliográfica sobre os temas disseminação seletiva de informações e bibliotecas digitais federadas, assumindo-se a visão de mediação, a partir da perspectiva de Kuhlthau. Realizou-se, ainda, um estudo de caso no NEP (New Economics Papers), um serviço da biblioteca digital RePEc (Research Papers in Economics), sendo a coleta de dados realizada a partir de variadas fontes de evidências. Em relação ao questionário usado na coleta de dados, dos 61 editores temáticos voluntários, que faziam a seleção de informações a serem disseminadas nas categorias temáticas do NEP, contou-se com 41 respondentes. Para a análise dos dados, derivados das respostas do questionário, utilizou-se análise de conteúdo, buscando a identificação de fatores relevantes relacionados às variáveis analisadas (interação entre mediadores e usuários, seleção dos documentos, motivação dos mediadores, impacto do serviço e perfil dos mediadores), promovendo, quando necessário, o agrupamento de respostas semelhantes em categorias, enfatizando a ocorrência de determinado fator e não sua freqüência. Dentre os resultados destacam-se: caracterização de três distintas gerações de serviços de disseminação seletiva de informações, em relação ao desenvolvimento tecnológico; identificação de distintas possibilidades e níveis de mediação nos serviços de disseminação seletiva de informações; identificação de fatores correspondentes às variáveis analisadas em relação à mediação realizada por meio de intervenção humana, em serviços de disseminação seletiva de informações em bibliotecas digitais federadas. Conclui-se que, embora a tecnologia possibilite a autonomia por parte do usuário, em relação aos serviços de disseminação seletiva de informações, é viável um planejamento prévio que reconheça a possibilidade de se atuar em diferentes níveis de mediação a serem adotados, uma vez que a presença da mediação pode agregar valor ao serviço. / Technological advances has facilitated the development of various resources enabling the implementation of selective dissemination of information services which offer autonomy to users. Thus, the objective was to analyze the process of selective dissemination of information, through an exploratory study in a federated digital library, aiming to enhance the mediation by human intervention. For this, a literature review was made comprising the themes: selective dissemination of information and digital libraries, assuming mediation from the perspective of Kuhlthau. Also, it was conducted a case study based on NEP (New Economics Papers), a service of the digital library RePEc (Research Papers in Economics) being the data collection made from various sources of evidence. Regarding the questionnaire used in the data collection, out of 61 volunteers, who were responsible for selecting information on the NEP themes to be disseminated, 41 responded the questionnaire. For data analysis, derived from responses from the questionnaires, it was used content analysis, seeking to identify relevant factors related to the analyzed variables (interaction between mediators and users, documents\' selection, mediators\' motivation, services impact and mediators\' profile), promoting, when necessary, the grouping of similar responses into categories, emphasizing thus, the occurrence of a particular factor and not it\'s frequency. Among the results are: characterization of three different generations of selective dissemination of information services, in relation to technological development; identification of different possibilities and levels of mediation in services of selective dissemination of information; identification of factors related to the variables analyzed, in relation to the mediation made by means of human intervention in services of selective dissemination of information. It is found that, although the technology allows the autonomy of the user, referring to the selective dissemination of information services, it is possible to make a previous planning that recognize the possibility of acting from different levels of mediation to be adopted, since the presence of mediation can add value to the service.

Introdução - No Brasil, o Programa Municipal de Coleta Seletiva (PMCS) pode ser executado pelo próprio município, por empresa contratada ou em parceria com uma organização de catadores. Mais de 50 por cento dos PMCS no Estado de São Paulo é realizado por essas organizações. Logo, a maioria dos estudos foca-se nessas organizações, mas os municípios que não possuem parceria também precisam ser estudados. Objetivo - Analisar e avaliar PMCS realizados sem parceria com organização de catadores, na perspectiva de sustentabilidade socioeconômica, ambiental e institucional. Métodos - Para esse estudo, 7 municípios foram selecionados conforme os critérios porte do município e tempo de existência mínima de 2 anos do PMCS, a partir de dados do Sistema Nacional de Informações sobre Saneamento e ligações telefônicas Os municípios estudados foram divididos em pequeno (4) e grande (3) porte. Os responsáveis pelo PMCS foram entrevistados, com base em questionário semiestruturado. Os resultados permitiram caracterizar os PMCS e alimentar 13 indicadores e 2 índices de sustentabilidade de PMCS. Resultados - Foram identificados 4 arranjos institucionais de execução dos PMCS, envolvendo a prefeitura municipal e empresa terceirizada. Os municípios de grande porte apresentam mais indicadores favoráveis à sustentabilidade que os de pequeno porte. A produtividade é maior nos de grande porte, mas a remuneração é melhor nos pequenos. Por outro lado, esses apresentam melhor taxa de recuperação, adesão e atendimento e menor taxa de rejeito, o que eleva o índice de sustentabilidade. Para os 2 índices considerados, os municípios de pequeno porte são mais favoráveis à sustentabilidade que os de grande porte. Conclusões - Os municípios de pequeno porte apresentam maior tendência à sustentabilidade nos indicadores considerados mais importantes num PMCS sem parceria com organizações de catadores. Embora a Política Nacional de Resíduos Sólidos priorize PMCS em parceria com organização de catadores, arranjos sem parceria são possíveis e apresentam-se também sustentáveis na sustentabilidade da valorização de materiais recicláveis. / Introduction - In Brazil, the Municipal Program for Selective Collection (MPSC) can be performed by the municipality itself, by a company contracted or through a partnership with waste pickers organization. More than 50 per cent of the MPSC in São Paulo State is performed by these organizations. Then, most of the studies focuses on these organizations, but the municipalities that dont have partnership also need to be studied. Objective - To analyze and evaluate MPSC performed without partnership with waste pickers organization, through the perspective of socioeconomic, environmental and institutional sustainability. Methods For this study, 7 municipalities were selected according to the criteria: size and minimum time of existence, using data form the National Sanitation Information System and phone calls. The municipalities studied were divided into small (4) and large (3) sizes. The people responsible for MPSC were interviewed, based on a semi-structured questionnaire. The results allowed to characterize the MPSC and feed 13 indicators and 2 MPSC sustainability indexes. Results - Were identified 4 institutional arrangements of MPCS, involving the city government and outsourcing company. The large cities have more favorable indicators of sustainability than the small ones. The productivity is bigger in large municipalities, but the payment (compensation) is better in the small ones. Nevertheless, these present higher recovery rate, adherence and attendance and lower reject rate, what raises the sustainability index. For the 2 index considered the small municipalities are more sustainability favorable than the large ones. Conclusions - Small municipalities are more likely to sustainability for those indicators considered more important in a MPCS without a partnership with waste pickers organizations. Although the National Solid Waste Policy prioritizes MPCS through a partnership with waste pickers organization, arrangements without these kind of partnership are possible and also are sustainable for the recovery of recyclable materials.

Lorsque nous pensons à nous-mêmes, à toutes les caractéristiques physiques ou psychologiques qui nous définissent, à tous les objets que nous possédons, nous avons limpression quils ont un statut bien particulier dans notre esprit, quils sont spéciaux pour nous. Notre propre visage est certainement parmi lune des plus uniques et distinctives de toutes ces informations autoréférentielles. Dans ce travail, nous nous sommes penchés sur les spécificités du traitement visuel du propre visage. Dans un premier chapitre théorique, nous avons questionné la possibilité dutiliser le traitement du propre visage comme un indice de conscience de soi (voir Chapitre 1). Ensuite, nous avons passé en revue les différentes études existantes qui concernaient la spécificité du propre visage ou dautres informations autoréférentielles (voir Chapitre 2). Suite à cette revue de la littérature, il est apparu que lintuition selon laquelle notre propre visage est un stimulus spécial navait pas pu être confirmée unanimement par les études qui nous précédaient. Ce travail ambitionnait donc dévaluer empiriquement dans quelle mesure notre propre visage est traité par le système cognitif de façon différente des autres visages que nous rencontrons. Nous avons tenté de répondre à cette question selon trois angles différents. Tout dabord, nous nous sommes intéressés à la précision de la représentation de notre propre visage en mémoire. Pour cela, nous avons utilisé dans notre première étude une méthode psychophysique permettant de déterminer dans quelle mesure nous sommes capables de détecter des modifications fines apportées à des photographies de notre propre visage (voir Chapitre 4). Ensuite, nous avons examiné si la reconnaissance de notre propre visage, mais aussi celle de notre propre corps, sont sous-tendues par des zones cérébrales spécifiques. A cette fin, au cours dune seconde étude, nous avons utilisé limagerie par résonance magnétique fonctionnelle (IRMf, voir Chapitre 5). Enfin, nous avons testé si le propre visage est particulièrement apte à capturer ou à retenir notre attention lorsquil est présenté de façon inopportune alors que nous sommes occupés à réaliser une tâche sans rapport (voir Chapitres 6, 7 et 8). Pour ce faire, nous avons eu recours, dans une série de trois études, à différents paradigmes attentionnels : un paradigme de jugement de parité, un paradigme de cécité attentionnelle, et un paradigme de recherche visuel lors duquel nous avons procédé à lenregistrement des mouvements oculaires des participants. Tout au long de ce travail, nous avons adopté une approche visant à différencier les effets dautoréférence de simples effets de familiarité. Pour ce faire, dans toutes nos études, nous avons comparé les réponses obtenues lors de la présentation du propre visage du participant à celles obtenues lors de la présentation du visage dune personne hautement familière pour le participant (un ami ou un collègue du même groupe dâge et du même sexe). Par ailleurs, dans les études attentionnelles, les réponses subséquentes à la présentation de ces deux visages familiers étaient également comparées à celles obtenues suite à lapparition de visages de personnes inconnues. En somme, si les performances obtenues sur le propre visage et le visage très familier différaient, nous pourrions penser que ces différences sont dues à laspect autoréférentiel du propre visage. Par contre, si les performances ne différaient pas entre le propre visage et lautre visage très familier mais que ces deux visages se distinguaient des visages inconnus, nous pourrions supposer que nous sommes face à de simples effets de familiarité. La première étude psychophysique a montré que la représentation que nous avons en mémoire de notre propre visage est très précise. Cette précision est seulement limitée par les capacités de discrimination perceptive de notre système visuel. Cependant, il en était de même pour le visage dune autre personne hautement familière. De ce point de vue, il ne semble donc pas que notre propre visage soit spécial. Néanmoins, il semblerait que cette représentation soit sous-tendue par des substrats cérébraux spécifiques, comme indiqué par notre seconde étude en IRMf. Cette étude a aussi montré que notre propre corps serait également traité par des régions cérébrales spécifiques. De plus, certaines régions seraient dédiées au traitement abstrait de notre propre apparence physique puisquelles étaient impliquées indépendamment du type de matériel présenté (visage ou corps). Enfin, nous avons montré, grâce aux trois études attentionnelles, que le propre visage nest pas un distracteur exceptionnel par rapport à dautres visages familiers. En effet, le propre visage ne semble pas capturer lattention de façon automatique. Il semblerait que le propre visage bénéficie simplement dune allocation de lattention préférentielle par rapport à des visages inconnus. En dautres termes, lallocation de lattention au propre visage est sujette à diverses contraintes (par exemple sa localisation spatiale) et il semblerait que lattention soit nécessaire pour identifier le propre visage en tant que tel. Cet ensemble de résultats est discuté dans un dernier chapitre (voir Chapitre 9) où nous tentons de mettre les données provenant des trois perspectives différentes (représentation en mémoire, substrats cérébraux et propriétés attentionnelles relatifs au propre visage) en rapport. De plus, la possibilité dutiliser le propre visage comme outil détude de la conscience de soi ou de différents processus cognitifs (reconnaissance ou attention visuelle) est brièvement passée en revue.<br> <br> When we think about ourselves, about the traits that define us, about the physical characteristics or the objects that we own, we have the intuition that they have a special status in our mind. We deeply feel that they are different from everything else in the world. This thesis concerned the specificity of a highly distinctive self-referential stimulus: the self-face. In the present thesis, we have conducted five studies examining whether the self-face is processed in a special way by comparison with other faces. We have put three main questions: (1) how accurate is the representation of the self-face in memory?; (2) is this representation subtended by specific neural correlates?; and (3) does the self-face have special abilities to attract and/or to hold attention? First, we showed that the perceptual representation in memory of the self-face is similar to that of other familiar faces as regard with its precision. Second, we demonstrated that although ones own face perceptual representation is not really special, the visual processing of the self-face is subtended by specific neural correlates. Apparently, the self-body is also processed via specialised pathways in the brain. In addition, some regions seem devoted to the abstract processing of ones own physical appearance independently of the material presented. Third, we showed that ones own face is not a particularly potent distractor by comparison with other familiar faces. It does not seem able to capture attention but rather benefits from a preferential allocation of attention by comparison with unfamiliar faces. In other words, its attentional processing is subject to various constraints (e.g. spatial localisation, available attentional resources) and attention seems necessary to process self-referential parts of a face. We discussed the idea that the presentation of the self-face can constitute a way to enhance chances of eliciting responses in non-communicative patients but that it is not the best way to study self-consciousness in normal adults when using only behavioural methods. In addition, because of its unique characteristics, the self-face can represent a useful tool of investigation of visual recognition and visual attention.

Heterojunction bipolar transistors (HBT) based on SiGeC havebeen investigated. Two high-frequency architectures have beendesigned, fabricated and characterized. Different collectordesigns were applied either by using selective epitaxial growthdoped with phosphorous or by non-selective epitaxial growthdoped with arsenic. Both designs have a non-selectivelydeposited SiGeC base doped with boron and a poly-crystallineemitter doped with phosphorous. Selective epitaxial growth of the collector layer has beendeveloped by using a reduced pressure chemical vapor deposition(RPCVD) technique. The incorporation of phosphorous and defectformation during selective deposition of these layers has beenstudied. A major problem of phosphorous-doping during selectiveepitaxy is segregation. Different methods, e.g. chemical orthermal oxidation, are shown to efficiently remove thesegregated dopants. Chemical-mechanical polishing (CMP) hasalso been used as an alternative to solve this problem. The CMPstep was successfully integrated in the HBT process flow. Epitaxial growth of Si1-x-yGexCy layers for base layerapplications in bipolar transistors has been investigated indetail. The optimization of the growth parameters has beenperformed in order to incorporate carbon substitutionally inthe SiGe matrix without increasing the defect density in theepitaxial layers. The thermal stability of npn SiGe-based heterojunctionstructures has been investigated. The influence of thediffusion of dopants in SiGe or in adjacent layers on thethermal stability of the structure has also been discussed. SiGeC-based transistors with both non-selectively depositedcollector and selectively grown collector have been fabricatedand electrically characterized. The fabricated transistorsexhibit electrostatic current gain values in the range of 1000-2000. The cut-off frequency and maximum oscillation frequencyvary from 40-80 GHz and 15-30 GHz, respectively, depending onthe lateral design. The leakage current was investigated usinga selectively deposited collector design and possible causesfor leakage has been discussed. Solutions for decreasing thejunction leakage are proposed. <b>Key words:</b>Silicon-Germanium-Carbon (SiGeC),Heterojunction bipolar transistor (HBT), chemical vapordeposition (CVD), selective epitaxy, non-selective epitaxy,collector design, high-frequency measurement, dopantsegregation, thermal stability.