La spectrométrie de masse fournit deux types d’informations : la masse moléculaire des molécules présentes dans un mélange, en une première expérience (MS), puis leurs structures après isolation suivie de fragmentation, obtenues une à une (MS/MS). La spectrométrie de masse FT-ICR bidimensionnelle permet d’obtenir toutes ces informations en une seule expérience, sans isolation, quelle que soit la complexité de l’échantillon. Le prix à payer est une faible résolution dans la dimension indirecte, pouvant être améliorée par une augmentation du temps d’analyse, mais qui semblait limiter cette technique à une simple curiosité scientifique.Le premier objectif est d’implémenter l’échantillonnage non uniforme (NUS) en FT-ICR MS 2D. Cette technique consiste en l’acquisition aléatoire du même nombre de points dans la dimension indirecte que lors d’une acquisition uniforme, mais sur une plage de t1max plus grande. Les points manquants sont ensuite reconstruits par des algorithmes, entrainant une augmentation significative de la résolution du signal sans perte de temps sur le spectromètre. La première étape est de créer un algorithme générant un échantillonnage aléatoire de distribution uniforme pour une couverture optimale de la plage de t1max. Les algorithmes de reconstruction ayant des difficultés à reconstituer des signaux de faible intensité quand le nombre de points non échantillonnés augmente, la deuxième étape est de déterminer le facteur de sous-échantillonnage optimal afin d’obtenir le bon compromis entre résolution et signal-sur-bruit. La troisième étape est de réaliser des spectres MS/MS ayant des massifs isotopiques corrects pour des fragments produits à partir des isotopes les plus lourds.Le deuxième objectif est de décrire le comportement des ions dans la cellule ICR en fonction des impulsions RF utilisées à partir des équations de Lorentz. Dans une première partie, le but est d’établir les équations qui régissent le mouvement des ions précurseurs jusqu’à leur détection. Ensuite, il s’agit d’introduire la fragmentation et de déterminer les solutions analytiques décrivant le mouvement des fragments. La dernière étape est de simuler le comportement des ions précurseurs tout au long de la séquence d’impulsions ainsi que celui des nuages de fragments, de leur formation à leur détection. / Mass spectrometry provides two kinds of information: the molecular mass of molecules present in a mixture, obtained all at once (MS), and structure through isolation and fragmentation, obtained one by one (MS/MS). Two-dimensional FT-ICR MS allows simultaneous parallel acquisition of structural information without isolation, regardless of the number of molecules. Nevertheless, the low resolution in the indirect dimension, which could be improved by increasing the acquisition time, seemed to limit this method to a simple curiosity. The first objective is to implement non-uniform-sampling (NUS) in 2D FT-ICR MS. This method consist in the random acquisition of the same number of points in the indirect dimension as in uniform acquisition, but over a wider t1max range. Processing algorithms then reconstruct skipped points, and the result is an increase of signal resolution without wasting analysis time. The first step is to create an algorithm that can generate random sampling with a uniform distribution for an optimal coverage of the t1max range. Processing algorithms may have trouble to reconstruct small peaks when the number of skipped points increases. The second step is to choose the under-sampling ratio for the best compromise between the gain in resolution and the signal-to-noise ratio. The third and last step is to obtain MS/MS spectra with corrects isotopic patterns for fragments produced from heavy isotopes. The second objective is to improve the understanding of ion motions in ICR cells depending on the RF pulses by using Lorentz equations. The first goal is to determine the equations governing precursors motions until their detection. Then the fragmentation will be introduced and analytical solutions describing fragments motions will be established. The last step is to simulate the trajectories of precursors throughout the entire pulse sequence as well as the behavior of fragments clouds, from their formation to detection.

A proposta aqui apresentada foi aplicada a uma turma de 40 alunos do Ensino Médio da modalidade Educação de Jovens e Adultos em uma escola privada situada na cidade de Estância Velha, RS. Os alunos desta modalidade caracterizam-se por serem alunos trabalhadores do setor coureiro e calçadista na cidade. O foco do trabalho é o ensino de Física na EJA, mais especificamente o ensino da cinemática e dinâmica do movimento circular uniforme. A escolha por este tema aconteceu a partir dos conhecimentos prévios do grupo de alunos relativos ao seu contexto profissional, formulando um tema gerador construído a partir dos conhecimentos prévios deste contexto, com o intuito de propiciar maior eficiência do processo ensino-aprendizagem. A partir de características profissionais em comum entre os alunos o tema gerador convergiu para o processo de produção do couro. Com isso, pretendemos tornar a Física significativa e relevante para o educando, uma Física viva e inserida no seu cotidiano, permitindo com que o aluno realizasse relações e analogias de situações presenciadas no seu trabalho com os conteúdos trabalhados. Tendo como fundamentação teórica as teorias de aprendizagem de David Ausubel e Joseph Novak e de Paulo Freire, buscamos desenvolver uma aprendizagem significativa de conteúdos de Física a partir de subsunçores existentes na estrutura cognitiva dos alunos, tornando o estudo do movimento circular uniforme relevante para os alunos partindo de conhecimentos prévios dos mesmos. Todo material didático trabalhado com a turma foi relacionado com o processo de produção do couro, visando tornar o material potencialmente significativo. Os mapas conceituais também foram utilizados como instrumentos de avaliação, visando analisar as relações conceituais estabelecidas na estrutura cognitiva dos alunos. Aplicamos um teste inicial objetivando averiguar os conhecimentos prévios dos alunos e constatar eventuais lacunas. Ao final da proposta aplicamos o teste final que objetivou verificar se todos os conceitos trabalhados durante a aplicação do projeto haviam sido aprendidos pelos educandos. A média geral da turma no teste final foi de 87,5% de ocorrência de respostas coerentes. Desta maneira, percebemos que o material apresentado e as relações do conteúdo com situações cotidianas foram fundamentais para o excelente desempenho dos alunos no projeto. / The proposal presented here has been applied to a class of 40 students from high school to form the Youth and Adult Education in a private school located in the town of Estância Velha, RS. Students of this type are characterized by students and workers in the leather footwear sector in the city. The focus of the work is the teaching of physics in EJA, specifically the teaching of kinematics and dynamics of uniform circular motion. The choice of this theme happened from the previous knowledge of the group of students on their professional context, making a theme generator built from previous knowledge of the context in order to provide greater efficiency of the teaching-learning process. From professional characteristics in common between students converged for the theme for the production process of leather. With this, we intend to make significant and physics relevant to the student, a physics and inserted into living their daily lives, allowing the student to make links and similarities of situations presence in his work with the content worked. With the theoretical foundation for learning the theories of David Ausubel and Joseph Novak and Paulo Freire, we develop a meaningful learning of content in Physics from subsumers in the cognitive structure of students, making the study of uniform circular motion relevant for students from previous knowledge of them. All material worked with the class was related to the production process of leather, to make the material potentially significant. The conceptual maps were also used as instruments of assessment, aimed at examining the relations established in the conceptual structure of the students learning. Apply an objective test initial check prior knowledge of the students and see any gaps. At the end of the final proposal put to the test aimed to check whether all the concepts worked for the implementation of the project are aware of learners. The overall average in the final test group was 87.5% of the occurrence of coherent answers. Thus, we see that the material presented and the relations of the content presented with everyday situations were key to the excellent performance of students in the project.

A proposta aqui apresentada foi aplicada a uma turma de 40 alunos do Ensino Médio da modalidade Educação de Jovens e Adultos em uma escola privada situada na cidade de Estância Velha, RS. Os alunos desta modalidade caracterizam-se por serem alunos trabalhadores do setor coureiro e calçadista na cidade. O foco do trabalho é o ensino de Física na EJA, mais especificamente o ensino da cinemática e dinâmica do movimento circular uniforme. A escolha por este tema aconteceu a partir dos conhecimentos prévios do grupo de alunos relativos ao seu contexto profissional, formulando um tema gerador construído a partir dos conhecimentos prévios deste contexto, com o intuito de propiciar maior eficiência do processo ensino-aprendizagem. A partir de características profissionais em comum entre os alunos o tema gerador convergiu para o processo de produção do couro. Com isso, pretendemos tornar a Física significativa e relevante para o educando, uma Física viva e inserida no seu cotidiano, permitindo com que o aluno realizasse relações e analogias de situações presenciadas no seu trabalho com os conteúdos trabalhados. Tendo como fundamentação teórica as teorias de aprendizagem de David Ausubel e Joseph Novak e de Paulo Freire, buscamos desenvolver uma aprendizagem significativa de conteúdos de Física a partir de subsunçores existentes na estrutura cognitiva dos alunos, tornando o estudo do movimento circular uniforme relevante para os alunos partindo de conhecimentos prévios dos mesmos. Todo material didático trabalhado com a turma foi relacionado com o processo de produção do couro, visando tornar o material potencialmente significativo. Os mapas conceituais também foram utilizados como instrumentos de avaliação, visando analisar as relações conceituais estabelecidas na estrutura cognitiva dos alunos. Aplicamos um teste inicial objetivando averiguar os conhecimentos prévios dos alunos e constatar eventuais lacunas. Ao final da proposta aplicamos o teste final que objetivou verificar se todos os conceitos trabalhados durante a aplicação do projeto haviam sido aprendidos pelos educandos. A média geral da turma no teste final foi de 87,5% de ocorrência de respostas coerentes. Desta maneira, percebemos que o material apresentado e as relações do conteúdo com situações cotidianas foram fundamentais para o excelente desempenho dos alunos no projeto. / The proposal presented here has been applied to a class of 40 students from high school to form the Youth and Adult Education in a private school located in the town of Estância Velha, RS. Students of this type are characterized by students and workers in the leather footwear sector in the city. The focus of the work is the teaching of physics in EJA, specifically the teaching of kinematics and dynamics of uniform circular motion. The choice of this theme happened from the previous knowledge of the group of students on their professional context, making a theme generator built from previous knowledge of the context in order to provide greater efficiency of the teaching-learning process. From professional characteristics in common between students converged for the theme for the production process of leather. With this, we intend to make significant and physics relevant to the student, a physics and inserted into living their daily lives, allowing the student to make links and similarities of situations presence in his work with the content worked. With the theoretical foundation for learning the theories of David Ausubel and Joseph Novak and Paulo Freire, we develop a meaningful learning of content in Physics from subsumers in the cognitive structure of students, making the study of uniform circular motion relevant for students from previous knowledge of them. All material worked with the class was related to the production process of leather, to make the material potentially significant. The conceptual maps were also used as instruments of assessment, aimed at examining the relations established in the conceptual structure of the students learning. Apply an objective test initial check prior knowledge of the students and see any gaps. At the end of the final proposal put to the test aimed to check whether all the concepts worked for the implementation of the project are aware of learners. The overall average in the final test group was 87.5% of the occurrence of coherent answers. Thus, we see that the material presented and the relations of the content presented with everyday situations were key to the excellent performance of students in the project.

Made available in DSpace on 2015-05-08T14:57:18Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3795959 bytes, checksum: 7a11a6cf0b41c67297d55642c2b80df3 (MD5) Previous issue date: 2014-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, we analyse different architectures of analog-to-digital converters (ADC) and propose an architecture based on sampling by crossing levels and adaptive quantization step, aiming at reducing the energy required to convert and process specific signals. The proposed architecture has parameters which can be dynamically configured by the user, as to adapt the conversion process to the signal being sampled and to the requirements of power consumption of the target application. The architecture was modeled and simulated using Matlab, and used to convert several test signals, of which an ECG signal. The use of the proposed architecture resulted in SNR improvements of up to 10dB if compared against uniform (periodic) sampling. The digital logic was implemented in FPGA from a SystemVerilog description functionally compatible with the Matlab model, and the analog part was implemented with discrete components. / Neste trabalho, faz-se uma análise de diferentes arquiteturas de conversores analógico-digitais, e propõe-se uma arquitetura de conversor analógico-digital baseado em amostragem por cruzamento de níveis (não-uniforme) com adaptação do passo de quantização, com o objetivo de reduzir o consumo de energia requerido pela conversão analógica-digital e processamento de sinais com características específicas. A arquitetura proposta possui parâmetros que podem ser configurados dinamicamente pelo usuário, a fim de que o processo de conversão se adeque às características do sinal a ser amostrado e aos requerimentos de consumo de energia da aplicação. A arquitetura foi modelada e simulada em MatLab, tendo sido utilizada na conversão de diversos sinais de teste, dentre os quais um sinal típico de eletrocardiograma. Verificou-se que a amostragem não-uniforme com adaptação do passo de quantização proposta resultou em um aumento da relação sinal-ruído do sinal amostrado de até 10dB quando comparado com a amostragem uniforme. A implementação da parte digital foi feita em FPGA a partir de uma descrição em SystemVerilog funcionalmente compatível com o modelo em Matlab, e a parte analógica foi implementada com componentes discretos.

Um novo procedimento para construir os estados coerentes (CS) e os estados semiclássicos (SS) no campo de um magnético-solenóide é proposto. A idéia principal é baseada sobre o fato de que o AB solenóide quebra a simetria translacional no plano-xy, isto apresenta um efeito topológico tal que surgem dois tipos de trajetórias, aquelas que circundam e aquelas que não circundam o solenóide. Devido a este fato, deve-se construir dois tipos diferentes dos CS/SS, os quais correspondem as referidas trajetórias no limite semiclássico. Seguindo esta idéia, construímos os CS em duas etapas, primeiro os CS instantâneos (ICS) e os CS/SS dependentes do tempo como uma evolução dos ICS. A construção é realizada para partículas não-relativísticas e relativísticas, de spin-zero e com spin ambas em (2 + 1)- e (3 + 1)- dimensões e gera um exemplo não-trivial de SS/CS para sistemas com uma Hamiltoniana não-quadrática. É enfatizado que os CS dependendo dos seus parâmetros (números quânticos), descrevem ambos os estados puramente quânticos e semiclássicos. Uma análise é representada de modo que classifica os parâmetros dos CS em tal relação. Tal classificação é usada para as decomposições semiclásicas de diversas quantidades físicas. / A new approach to constructing coherent states (CS) and semiclassical states (SS) in magnetic-solenoid field is proposed. The main idea is based on the fact that the AB solenoid breaks the translational symmetry in the xy-plane, this has a topological effect such that there appear two types of trajectories which embrace and do not embrace the solenoid. Due to this fact, one has to construct two different kinds of CS/SS, which correspond to such trajectories in the semiclassical limit. Following this idea, we construct CS in two steps, first the instantaneous CS (ICS) and the time dependent CS/SS as an evolution of the ICS. The construction is realized for nonrelativistic and relativistic, spinning and spinless particles both in (2 + 1)- and (3 + 1)- dimensions and gives a non-trivial example of SS/CS for systems with a nonquadratic Hamiltonian. It is stressed that CS depending on their parameters (quantum numbers) describe both pure quantum and semiclassical states. An analysis is presented that classifies parameters of the CS in such respect. Such a classification is used for the semiclassical decompositions of various physical quantities.

A proposta aqui apresentada foi aplicada a uma turma de 40 alunos do Ensino Médio da modalidade Educação de Jovens e Adultos em uma escola privada situada na cidade de Estância Velha, RS. Os alunos desta modalidade caracterizam-se por serem alunos trabalhadores do setor coureiro e calçadista na cidade. O foco do trabalho é o ensino de Física na EJA, mais especificamente o ensino da cinemática e dinâmica do movimento circular uniforme. A escolha por este tema aconteceu a partir dos conhecimentos prévios do grupo de alunos relativos ao seu contexto profissional, formulando um tema gerador construído a partir dos conhecimentos prévios deste contexto, com o intuito de propiciar maior eficiência do processo ensino-aprendizagem. A partir de características profissionais em comum entre os alunos o tema gerador convergiu para o processo de produção do couro. Com isso, pretendemos tornar a Física significativa e relevante para o educando, uma Física viva e inserida no seu cotidiano, permitindo com que o aluno realizasse relações e analogias de situações presenciadas no seu trabalho com os conteúdos trabalhados. Tendo como fundamentação teórica as teorias de aprendizagem de David Ausubel e Joseph Novak e de Paulo Freire, buscamos desenvolver uma aprendizagem significativa de conteúdos de Física a partir de subsunçores existentes na estrutura cognitiva dos alunos, tornando o estudo do movimento circular uniforme relevante para os alunos partindo de conhecimentos prévios dos mesmos. Todo material didático trabalhado com a turma foi relacionado com o processo de produção do couro, visando tornar o material potencialmente significativo. Os mapas conceituais também foram utilizados como instrumentos de avaliação, visando analisar as relações conceituais estabelecidas na estrutura cognitiva dos alunos. Aplicamos um teste inicial objetivando averiguar os conhecimentos prévios dos alunos e constatar eventuais lacunas. Ao final da proposta aplicamos o teste final que objetivou verificar se todos os conceitos trabalhados durante a aplicação do projeto haviam sido aprendidos pelos educandos. A média geral da turma no teste final foi de 87,5% de ocorrência de respostas coerentes. Desta maneira, percebemos que o material apresentado e as relações do conteúdo com situações cotidianas foram fundamentais para o excelente desempenho dos alunos no projeto. / The proposal presented here has been applied to a class of 40 students from high school to form the Youth and Adult Education in a private school located in the town of Estância Velha, RS. Students of this type are characterized by students and workers in the leather footwear sector in the city. The focus of the work is the teaching of physics in EJA, specifically the teaching of kinematics and dynamics of uniform circular motion. The choice of this theme happened from the previous knowledge of the group of students on their professional context, making a theme generator built from previous knowledge of the context in order to provide greater efficiency of the teaching-learning process. From professional characteristics in common between students converged for the theme for the production process of leather. With this, we intend to make significant and physics relevant to the student, a physics and inserted into living their daily lives, allowing the student to make links and similarities of situations presence in his work with the content worked. With the theoretical foundation for learning the theories of David Ausubel and Joseph Novak and Paulo Freire, we develop a meaningful learning of content in Physics from subsumers in the cognitive structure of students, making the study of uniform circular motion relevant for students from previous knowledge of them. All material worked with the class was related to the production process of leather, to make the material potentially significant. The conceptual maps were also used as instruments of assessment, aimed at examining the relations established in the conceptual structure of the students learning. Apply an objective test initial check prior knowledge of the students and see any gaps. At the end of the final proposal put to the test aimed to check whether all the concepts worked for the implementation of the project are aware of learners. The overall average in the final test group was 87.5% of the occurrence of coherent answers. Thus, we see that the material presented and the relations of the content presented with everyday situations were key to the excellent performance of students in the project.

Made available in DSpace on 2014-08-20T14:31:30Z (GMT). No. of bitstreams: 1 dissertacao_andrio_zafalon_silva.pdf: 3030038 bytes, checksum: a10638c2996d28623646b9fa7980b243 (MD5) Previous issue date: 2013-07-05 / The fragmentation of natural environments is a major concern among conservation ecologists nowadays, especially in areas with a great diversity of habitats as the coastal plains of Rio Grande do Sul. In order to provide the basis to the managers responsible for the maintenance of natural areas, as well as to develop the knowledge of the Muscidae family in the southern Brazil, this study aimed to determine the biodiversity of the Muscidae family, in addition to proposing a method to evaluate the pattern of the species-area relationship (SAR) without using a different sampling effort between the areas of different sizes. To do that, 140 Malaise traps were installed distributed in 35 areas of five regions in the Coastal Plains. Each region was composed of seven areas with four traps at proportional distances. A total of 6102 individuals were collected distributed among 120 species/morphspecies in the five regions. Based on the lists it can be stated the degree of conservation and the anthropic influence on the studied areas, mainly by the presence of the species of Muscinae and Coenosiinae. The similarity between the communities of Muscidae was determined by the proximity of the collection places or by the climatic conditions of the period, and it was also observed a positive relationship in the species-area relationship for the linear and logistic models. Although the model with the power function is not significant, it showed coefficients that allow the interpretation of the types of fragments that occur in the coastal plains of RS. / A fragmentação das áreas naturais é uma das maiores preocupações entre os ecólogos da conservação na atualidade, principalmente em áreas com uma grande diversidade de habitats como a Planície Costeira do Rio Grande do Sul. A fim de prover embasamento aos gestores responsáveis pela manutenção das áreas naturais e desenvolver o conhecimento sobre a família Muscidae no sul do Brasil, o presente estudo objetivou conhecer a biodiversidade da família Muscidae, além de propor um método para a avaliação do padrão de relacionamento espécie área (SAR) sem utilizar esforço amostral distinto entre as áreas de diferentes tamanhos. Para isso, foram instaladas 140 armadilhas Malaise distribuídas em 35 áreas de cinco regiões na Planície Costeira. Cada região foi composta por sete áreas com quatro armadilhas com distâncias proporcionais. Foram coletados 6102 indivíduos distribuídos entre 120 espécies/morfoespécies nas cinco regiões. A partir das listas podemos constatar o grau de conservação e a influência da ação antrópica nas áreas naturais amostradas, principalmente pela presença de espécies de Muscinae e Coenosiinae. A similaridade entre as comunidades de Muscidae foi determinada pela proximidade entre os locais de coletas ou pelas condições climáticas do período, e observamos ainda uma relação positiva no relacionamento espécie-área para os modelos linear e logístico. Apesar do modelo com a função de poder não ser significativo, apresentou coeficientes que possibilitam a interpretação dos tipos de fragmentos que existem na planície costeira do RS.

Cette thèse examine la dispersion multivariée des modelés normales stables Tweedie. Trois estimateurs de fonction variance généralisée sont discutés. Ensuite dans le cadre de la famille exponentielle naturelle deux caractérisations du modèle normal-Poisson, qui est un cas particulier de modèles normales stables Tweedie avec composante discrète, sont indiquées : d'abord par fonction variance et ensuite par fonction variance généralisée. Le dernier fournit la solution à un problème particulier d'équation de Monge-Ampère. Enfin, pour illustrer l'application de la variance généralisée des modèles Tweedie stables normales, des exemples à partir des données réelles sont fournis. / This thesis examines the multivariate dispersion of normal stable Tweedie (NST) models. Three generalize variance estimators of some NST models are discussed. Then within the framework of natural exponential family, two characterizations of normal Poisson model, which is a special case of NST models with discrete component, are shown : first by variance function and then by generalized variance function. The latter provides a solution to a particular Monge-Ampere equation problem. Finally, to illustrate the application of generalized variance of normal stable Tweedie models, examples from real data are provided.

Dans l'espace de l'OHADA, la diffusion massive du terme de gouvernance relève essentiellement du contexte de la coopération internationale pour le développement. Ce nouvel impératif de gouvernance est depuis quelques années, dans le débat sur la construction d'une gouvernance d'entreprise, au cœur de tous les discours, des réformes, de toutes les initiatives en matière de développement des affaires et de fonctionnement efficace de l'entreprise. En réalité, dans cet environnement communautaire de l'OHADA, (CEMAC et UEMOA), il se trouve que la volonté politique est avant tout économique, le droit ne jouant qu'un rôle de second plan de mise en ordre a posteriori. Aussi, cela pose le problème suivant, à savoir : comment concilier d'une part, l'objectif de sécurité juridique et judiciaire indispensable pour drainer des flux importants d'investissements et, d'autre part, l'enjeu essentiel dont participe l'OHADA à l'établissement de ce qu'il est aujourd'hui coutume d'appeler « la bonne gouvernance » et de l'Etat de droit en Afrique comme vecteur de la performance économique.Au regard de l'ambition affichée par les rédacteurs de l'AUSCGIE et, sous le prisme des normes internationales, d'exigences nouvelles de développement économique et de la pérennité des entreprises, la gouvernance des sociétés commerciales pose la problématique de l'efficacité juridique de ce corps de règles. En d'autres termes, comment faire émerger dans un espace où le contrôle de l'Etat sur les activités économiques est mis à mal, des règles de gouvernance d'entreprise efficace au sein des sociétés commerciales ? Vaste programme.Dans la pratique, compte tenu des réalités, « la gouvernance dans les Etats membres de l'OHADA signifie souvent tout autre chose. Il ne s'agit pas de la gouvernance des sociétés dans le sens classique, mais au contraire, de l'influence politique ». De fait, il se trouve qu'aujourd'hui, la zone OHADA souffre avant tout, non pas de l'absence de règles, mais de la persistance de graves faiblesses et d'un manque cruel en terme de gouvernance et de contrôle de la bonne application des règles de droit, notamment, vis-à-vis de l'entreprise. Au regard de cette situation, l'on est tenté de dire que l'application des règles et principes de la gouvernance d'entreprise reste quelque peu limitée ou n'a pas encore porté les fruits escomptés. Une gouvernance d'entreprise dans l'espace OHADA est-elle une illusion ? Le constat objectif est bien évidemment non. C'est donc au prisme des enjeux économiques actuels et, face aux nouvelles attentes et défis des Etats membres, des axes de convergences ne seraient possibles qu'en vertu du réalisme du droit de l'OHADA, qui doit concilier à la fois, impératif économique (besoin d'investissement) et sécurisation juridique et judiciaire des activités économiques (quête de sécurité juridique).Mots clés : OHADA (Organisation pour l'Harmonisation en Afrique du Droit des Affaires), Droit, Gouvernance, Entreprise, Acte uniforme. / In the space of OHADA, the massive dissemination of the term governance essentially within the context of international cooperation for development. This new imperative of governance in recent years, the debate on building a corporate governance at the heart of all the speeches, reforms, all initiatives in the development of effective business and operation of the 'business. In fact, at that Community environment OHADA (CEMAC and UEMOA), there is the political will is above all economic, law playing only a role of second order implementation plan afterwards. Also, this poses the following problem, namely how to reconcile one hand, the essential objective of legal and judicial security to drain large flows of investment and, secondly, the essential challenge which involved the OHADA in establishing what is today commonly called "good governance" and the rule of law in Africa as a vector of economic performance. Given the ambition of the drafters of the AUSCGIE and, from the perspective of international standards, new requirements of economic development and enterprise sustainability, governance of corporations raises the issue of the legal effectiveness This set of rules. In other words, how to emerge in a space where the state control on economic activities is undermined, effective corporate governance rules within the commercial companies? Extensive program.In practice, given the realities, "Governance in the OHADA member states often means something else entirely. There is no corporate governance in the classic sense, but rather of political influence." Indeed, it is today the OHADA area suffers above all, not the absence of rules, but serious weaknesses persistence and a severe lack in terms of governance and control proper application of rules of law, particularly vis-à-vis the company. Given this situation, one is tempted to say that the rules and principles of corporate governance remains somewhat limited and has not yet yielded the expected fruits. Is a corporate governance in OHADA an illusion? The objective fact is obviously not. So the prism of current economic challenges and face new challenges and expectations of Member States, would only be possible convergence of the axes of realism that under the law of the OHADA, which must reconcile both imperative Economic (investment required) and legal and judicial security of economic activities (search for legal certainty).Keywords: OHADA (Organization for the Harmonization of Business Law in Africa), Law, Governance, Enterprise, Uniform Act.

La dimensionnalité d’un système affecte fortement ses propriétés physiques ; les transitions de phasequi s’y déroulent ainsi que le type d’ordre qui y apparaît dépendent de la dimension. Dans les systèmesde basse dimension, la cohérence s’avère plus difficile à établir car les fluctuations thermiques etquantiques y jouent un rôle plus important. Le fluide de Bose à deux dimensions est particulièrementintéressant car, même si un ordre total est exclu, un ordre résiduel à « quasi-longue » portée s’établit àbasse température. Deux ingrédients ont un effet significatif sur l’état du système : (i) la taille finie d’unsystème réel permet de retrouver une occupation macroscopique d’un état à une particule ; (ii) les interactionsentre particules conduisent à l’apparition d’un type non-conventionnel de transition de phasevers un état superfluide.Dans cette thèse, nous présentons une étude expérimentale du gaz de Bose bidimensionnel (2D) utilisantdeux types de paysages énergétiques pour piéger nos atomes. Dans la première partie, nous utilisonsla dépendance spatiale de certaines propriétés locales d’un gaz inhomogène pour caractériser l’étatdu système homogène équivalent. Nous extrayons son équation d’état des profils de densité et noustestons son comportement superfluide en mesurant le chauffage induit par le mouvement d’une perturbationlocale. Dans la deuxième partie, nous observons et caractérisons l’émergence d’une cohérencede phase étendue dans un gaz 2D homogène, en particulier via le passage de trois dimensions à deux(croisement dimensionnel). Nous étudions l’établissement dynamique de la cohérence par un passagerapide du croisement dimensionnel et nous observons des défauts topologiques dans l’état superfluidefinal. Nous comparons nos résultats avec les prédictions du mécanisme de Kibble–Zurek. / The dimensionality of a system strongly affects its physical properties; the phase transitions that takeplace and the type of order that arises depend on the dimension. In low dimensional systems phasecoherence proves more difficult to achieve as both thermal and quantum fluctuations play a strongerrole. The two-dimensional Bose fluid is of particular interest as even if full order is precluded, a residual"quasi-long" range order arises at low temperatures. Then two ingredients have a significant effecton the state of the system: (i) the finite size of a real system enables one to recover of a macroscopicoccupation of a single-particle state; (ii) the interactions between particles lead to the emergence of anon-conventional type of phase transition toward a superfluid state.In this thesis, we present an experimental study of the two-dimensional (2D) Bose gas using two differentenergy landscapes to trap our atoms. In the first part, we use the spatial dependence of somelocal properties of an inhomogeneous gas to characterize the state of the equivalent homogeneous system.We extract its equation of state with a high accuracy from the gas density profiles and test itssuperfluid behavior by measuring the heating induced by a moving local perturbation. In the secondpart, we observe and characterize the emergence of an extended phase coherence in a 2D homogeneousgas in particular via a 3D-to-2D dimensional crossover. We investigate the dynamical establishment ofthe coherence via a rapid crossing of the dimensional crossover and observe topological defects in thefinal superfluid state. We compare our findings with the predictions for the Kibble–Zurek mechanism.