Neste trabalho, dois macro-agentes de transferência de cadeia para polimerizações via RAFT, à base de poli(óxido de etileno), isto é, PEO-CPADB e PEO-CPP, foram sintetizados via duas rotas químicas e utilizados como estabilizantes coloidais e como agentes de controle de massa molecular na polimerização em miniemulsão do estireno. Látices de poliestireno (PS), estabilizados estericamente pelos segmentos de PEO, foram obtidos utilizando 2,2\'-azobis(isobutironitrila) como iniciador e hexadecano como co-estabilizador. O consumo de monômero foi determinado via análise gravimétrica. O tamanho de partícula e a distribuição de tamanhos de partículas (PSD) foram determinados por espalhamento de luz (LS). As massas moleculares e a distribuição de massas moleculares (nwMM) dos polímeros foram determinadas por cromatografia de exclusão de tamanho (SEC). Os resultados mostraram que o diâmetro das gotas e das partículas de polímero, assim como a estabilidade coloidal dos látices são fortemente dependentes do tipo e da quantidade de agente de transferência de cadeia utilizado nas polimerizações. Deslocamentos das curvas de distribuição de massas moleculares para massas moleculares maiores, em função da conversão, indicaram que a maioria das cadeias poliméricas apresentava características de cadeias vivas. Análises de GPC também mostraram que a polimerização foi bem controlada quando uma quantidade do macro-agente RAFT PEO-CPP, igual a 4,4 x 10-3 mol.L-1 foi utilizada, o que foi indicado pelo baixos índices de polidispersão obtidos (1,05-1,42). / In this work, two poly(ethylene oxide)-based macro-RAFT agents, ie, PEO-CPADB and PEO-CPP, were synthesized via two chemical routes and used as a stabilizer and a control agent in the miniemulsion polymerization of styrene. Polystyrene (PS) latexes sterically stabilized by the PEO segments were obtained using 2,2?-azobis(isobutyronitrile) as initiator and hexadecane as co-stabilizer. Monomer consumption was monitored by gravimetric analysis. The latex particle size and the particle size distribution (PSD) were measured by light scattering (LS). Molar masses and molar mass distributions (nwMM) of the polymers were determined by size exclusion chromatography (SEC). The results showed that the droplet/particle sizes and the latexes stability are strongly dependent on the type and on the amount of macro-RAFT agent used in the polymerizations. Shifts of the SEC chromatograms toward higher molar masses with conversion indicated that the majority of the polymer chains are living chains. Size Exclusion Chromatography (SEC) analysis also showed that polymerization was well controlled when an amount of macro-RAFT PEO-RAFT agent equal to 4.4 x 10-3 mol. L-1 was used, since low polidispersity indices (1.05-1.42) was achieved.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aiming to develop studies relating laboratory spectroradiometry with macro and micronutrients contents of vegetative materials of forest populations of Eucalyptus grandis W Hill ex Maiden, of different ages, an experimental área was selected for the study at the Fundação Estadual de Pesquisas Agropecuárias FEPAGRO FLORESTAS, at Santa Maria, Rio Grande do Sul, Brazil. Departing from the purpose of studying the spectral behaviour, the specific objectives were: 1) to evaluate the leaves of E. grandis contents of macro and micronutrients, in the four climatic seasons, under differente types of soil managements; 2) to evaluate the leaves of E. grandis spectral behaviour including the waveband of 475 to 980ηm and approach the interaction between: climatic seasonal periods, different soil managements and the cardinal points locations of the sampled trees; 3) evaluate the nutritional status of E. grandis young trees leaves through leaf analyses and spectroradiometry, and generate models capable to estimate macro and micronutrients from reflectancy data. Results indicate that the E. grandis population, of 44 months old, shows deficiencies of P, S, B; Cu and Mn showed high contents; N was the only nutrient showing significant differences; there is no significant differences between climatic seasons. For the E. grandis population of 20 months old, variations observed in the nutrients contents were equal to those of the former area; the winter sesason showed a differente behaviour from the other climatic seasons. For the different soil managements, the macro and micronutrients did not vary significantly. Evaluating the reflectancy data for the leaves of E. grandis, of 20 months old, it was concluded that: 1) the summer and spring seasons statistically interfered on the reflectancy; 2) samples of vegetative material may be collected independently of the type of soil management; and, 3) the spectral wavebands that better expresses the vegetation behaviour were the 12, 8, 7 and 3; and, 4) the evaluation of points where the leaves were sampled (East, West, North, South and central) in the no-tillage soil management treatment indicated that: a) sampling of vegetative material should be done separating the central part of the bordering population; and, b) the waveband that better characterized the spectral response of the vegetation was that of number eight. Analysis of the main components indicated the 8, 11 na 12 wavebands as responsible for a total of 98.10% of the reflectancy values under study. The elements P and K showed low adjusted correlation coefficients while generating models considering the elements as dependent variables from reflectancy and climatic seaso;n interacting with wavelengths; the r2aj. values for the remaining elements varied from moderate to high. / Com o intuito de desenvolver estudos relacionando a espectrorradiometria de laboratório com os teores de macro e micronutrientes em materiais vegetativos de povoamentos florestais de Eucalyptus grandis W. Hill ex Maiden, com diferentes idades, uma área experimental foi selecionada para estudo na Fundação Estadual de Pesquisas Agropecuárias FEPAGRO FLORESTAS, Santa Maria, Rio Grande do Sul, Brasil. A partir da proposta de estudar o comportamento espectral, os objetivos específicos foram: 1) avaliar os teores de macro e micronutrientes de folhas de E. grandis nas quatro estações climáticas do ano em diferentes tipos de preparo de solo; 2) avaliar o comportamento espectral de folhas de Eucalyptus grandis abrangendo o intervalo de comprimento de onda de 475 a 980ηm, e abordar as interações: períodos sazonais, preparos de solo e a localização cardeal das árvores amostradas; 3) avaliar o estado nutricional de folhas de plantas jovens de E. grandis por análise foliar e espectrorradiometria e gerar modelos capazes de estimar os teores de macro e micronutrientes a partir de dados de reflectância. Os resultados indicam que o povoamento de E. grandis, com 44 meses de idade, apresenta deficiência de P, S e B; Cu e Mn apresentam teores elevados; N é o único nutriente que apresenta diferença significativa; entre as estações climáticas não existem diferenças significativas. Para o povoamento de E. grandis com 20 meses, as variações obtidas para os teores de nutrientes foram iguais as da área anterior; a estação inverno apresentou comportamento diferenciado das demais estações. Para os diferentes preparos de solo os macro e micronutrientes, não variaram significativamente. Avaliando os dados de reflectância de folhas de E. grandis, com 20 meses de idade, conclui-se que: 1) as estações verão e primavera interferiram estatisticamente na reflectância; 2) as amostras de material vegetativo podem ser coletadas independentemente do tipo de manejo do solo; 3) as bandas espectrais que melhor expressaram o comportamento da vegetação, foram as bandas 12, 8, 7 e 3; e, 4) a avaliação das posições em que as folhas foram coletas (Leste, Oeste, Norte, Sul e central) no tratamento com preparo de solo plantio direto indicaram que: a) as coletas de material vegetativo devem ser realizadas separando a parte central do povoamento da bordadura; e, b) a banda que melhor caracterizou a resposta espectral dessa vegetação foi a de número oito. A análise de componentes principais indicou as bandas 8, 11 e 12, como responsáveis por um total de 98,10% dos valores de reflectância em estudo. Ao gerar modelos considerando os elementos como variáveis dependentes da reflectância e estação do ano interagindo com comprimentos de onda, os elementos P e K apresentaram os valores dos coeficientes de correlação ajustados baixos; os valores de r2aj. dos demais elementos variaram de moderados a altos.

Pour limiter le potentiel systémique des crises financières futures il est nécessaire de renforcer la dimension macro-prudentielle de la régulation. Nous proposons dans cette thèse les quatre pistes de réflexion suivantes pour la construction d’un cadre macro-prudentiel plus robuste : i) détecter les décisions qui jouent un rôle décisif sur le niveau de risque de la banque et sur son exposition aux crises financières; ii) se servir d’un indicateur de levier agrégé pour détecter l’emballement de l’offre de crédits ; iii) introduire une forme de Prompt Corrective Action en Europe dont les signaux de détection seraient composés d’informations sur le capital et sur la liquidité des banques ; iiii) trouver le meilleur moyen de lutter contre le risque de hasard moral des institutions financières systémiques. Les résultats de ces travaux sont les suivants :1) l’association d’une politique de levier agressive et d’une politique de financement largement orientée sur les marchés à court terme est le facteur déterminant pour repérer les banques vulnérables ; 2) l’indicateur de levier agrégé que nous avons construit a un pouvoir prédictif assez élevé et peut par conséquent être utilisé comme instrument de détection des crises financières ; 3) l’information sur le risque de liquidité semble être un bon complément aux ratios de capital pour détecter les banques vulnérables et déclencher l’intervention des superviseurs dans le cadre d’une Prompt Corrective Action européenne ; 4) les solutions les plus pertinentes pour résoudre le problème de hasard moral associé aux institutions systémiques semblent être celles qui visent à simplifier la structure des banques afin d’en faciliter la résolution. / It is crucial to reinforce macro-prudential regulation to reduce the systemic impact of the next financial crisis. In this thesis, we propose four trails to strengthen the robustness of the macro-prudential framework: i) to detect the decisions which have the most significant impact on banks’ risk and, on their exposure to financial crises; ii) to use an indicator of global aggregated leverage to detect credit deviation; iii) to introduce a kind of Prompt Corrective Action in Europe relying on a composite threshold which is made of information about capital and liquidity risk; iiii) to find the best way to reduce moral hazard risk associated to systemically important financial institutions. Our findings are the following: 1) the combination of an excessive leverage and the high use of market short term funding is the core criteria to identify vulnerable banks; 2) the global aggregated leverage ratio we have constructed has a high predictive power and therefore, can be used to detect financial crises; 3) information about banks’ liquidity risk seems to be a useful complement to capital adequacy ratios to detect vulnerable banks and, trigger supervisory intervention for the European Prompt Corrective Action; 4) solutions which aim to reduce banks’ complexity to facilitate the resolution of systemically important financial institutions seems to be the most relevant to reduce moral hazard risk.

Neste trabalho, dois macro-agentes de transferência de cadeia para polimerizações via RAFT, à base de poli(óxido de etileno), isto é, PEO-CPADB e PEO-CPP, foram sintetizados via duas rotas químicas e utilizados como estabilizantes coloidais e como agentes de controle de massa molecular na polimerização em miniemulsão do estireno. Látices de poliestireno (PS), estabilizados estericamente pelos segmentos de PEO, foram obtidos utilizando 2,2\'-azobis(isobutironitrila) como iniciador e hexadecano como co-estabilizador. O consumo de monômero foi determinado via análise gravimétrica. O tamanho de partícula e a distribuição de tamanhos de partículas (PSD) foram determinados por espalhamento de luz (LS). As massas moleculares e a distribuição de massas moleculares (nwMM) dos polímeros foram determinadas por cromatografia de exclusão de tamanho (SEC). Os resultados mostraram que o diâmetro das gotas e das partículas de polímero, assim como a estabilidade coloidal dos látices são fortemente dependentes do tipo e da quantidade de agente de transferência de cadeia utilizado nas polimerizações. Deslocamentos das curvas de distribuição de massas moleculares para massas moleculares maiores, em função da conversão, indicaram que a maioria das cadeias poliméricas apresentava características de cadeias vivas. Análises de GPC também mostraram que a polimerização foi bem controlada quando uma quantidade do macro-agente RAFT PEO-CPP, igual a 4,4 x 10-3 mol.L-1 foi utilizada, o que foi indicado pelo baixos índices de polidispersão obtidos (1,05-1,42). / In this work, two poly(ethylene oxide)-based macro-RAFT agents, ie, PEO-CPADB and PEO-CPP, were synthesized via two chemical routes and used as a stabilizer and a control agent in the miniemulsion polymerization of styrene. Polystyrene (PS) latexes sterically stabilized by the PEO segments were obtained using 2,2?-azobis(isobutyronitrile) as initiator and hexadecane as co-stabilizer. Monomer consumption was monitored by gravimetric analysis. The latex particle size and the particle size distribution (PSD) were measured by light scattering (LS). Molar masses and molar mass distributions (nwMM) of the polymers were determined by size exclusion chromatography (SEC). The results showed that the droplet/particle sizes and the latexes stability are strongly dependent on the type and on the amount of macro-RAFT agent used in the polymerizations. Shifts of the SEC chromatograms toward higher molar masses with conversion indicated that the majority of the polymer chains are living chains. Size Exclusion Chromatography (SEC) analysis also showed that polymerization was well controlled when an amount of macro-RAFT PEO-RAFT agent equal to 4.4 x 10-3 mol. L-1 was used, since low polidispersity indices (1.05-1.42) was achieved.

O parâmetro que determina o processo de transferência de oxigênio através da interface ar-água em escoamentos com superficie livre é o coeficiente de reaeração superficial, \'K IND.2\'. Existe um grande número de equações na literatura científica que realizam a previsão do coeficiente de reaeração, no entanto, a maioria dessas equações considera apenas algumas características hidráulicas do corpo de água como a velocidade e a profundidade, e ainda, como em sua maioria são de natureza empírica, acabam sendo adequadas para corpos de água específicos. Além destes dois parâmetros (velocidade e profundidade do escoamento), existem outros doze que são considerados importantes para estudos de reoxigenação em águas superficiais. É neste contexto que o objetivo deste trabalho foi estudar em condições de laboratório a influência da rugosidade do leito de um canal sobre o coeficiente de reaeração superficial. Além da rugosidade, foram variadas as condições de velocidade média do escoamento e profundidade da lâmina de água. A variação da rugosidade foi realizada através da implementação de obstáculos com geometria conhecida, dispostos transversalmente ao escoamento, e denominados como macro-rugosidades. Os resultados demonstraram evidências de que o coeficiente de reaeração superficial é controlado de forma significativa pela rugosidade do leito do canal. Foram desenvolvidos dois modelos matemáticos de natureza semi-empírica para a previsão do \'K IND.2\', os quais incorporam variáveis hidrodinâmicas e geométricas consideradas relevantes para o processo de transferência de massa na interface ar-água. / The parameter that determines the process of oxygen transfer through the air-water interface in flows with free surface is the superficial reaeration coefficient, \'K IND.2\'. There are a large quantity of equations in the cientific literature that perform the prevision of the reaeration coefficient; however, most of them consider only some of the hydraulic characteristics of water body; for example, the velocity and the depth. Most of these equations have empirical origin and are adequate just for a specific water body. In addition to these two parameters (velocity and depth of flow), there are another twelve important parameters in reoxygenation studies in superficial waters. In this context, the aim of this work was to study the influence of bed roughness of a channel on the superficial reaeration coefficient, under laboratory conditions. Besides the roughness, the conditions of mean velocity of the flow and depth of water were varied. The variation of roughness was done with implementation of obstacles with known geometry, arranged transversely to the flow direction, and called macro-roughness. The results have shown evidences that the surface reaeration coefficient is controlled significantly by the roughness of the channel bed. Two mathematical models of semi-empirical origin for the \'K IND.2\' prevision were developed, which incorporate hydrodynamic and geometric variables considered relevant in the process of mass transfer in air-water interface.

Cette thèse a permis d'étudier la perméabilité du béton sous conditions thermiques et hydriques variables, ainsi que l'effet de fissuration. Nombreux essais (mesures de saturation et perméabilité, essai de compressions uniaxiales et triaxiales et hydrostatiques) ont été menés afin d'évaluer l'influence de la température et de la saturation sur le comportement hydraulique du béton sain et microfissuré. En parallèle, un dispositif de mesure de la perméabilité sur béton macro fissuré permet d'étudier le comportement d'une macro-fissure de béton confinée et soumise à écoulement de gaz sec ou l'air très humide à différentes températures. Les essais mécaniques multiaxiaux sont couplés aux mesures de perméabilité sur béton sain et micro-fissuré par gel-dégel, qui permet d'évaluer la perméabilité sous charge déviatorique et l'effet de préfissuration sous contrainte. Nous avons également effectué un essai de perméabilité relative du béton en fonction de la saturation en eau, soumis à la dessiccation ou à la resaturation, en conditionnant par les différentes humidités relatives imposées / The main objective of this study is to evaluate the variable thermal and hydric effect, with fissuration effect on the hydraulic behaviour of two concretes. Many experimental tests (saturation and permeability measurements, uniaxial and triaxial compressions tests) were carried out in order to investigate the temperature and saturation influence on the behaviour hydraulic on sound and micro-cracked concrete. Moreover, an experimental device for permeability measurement on macro-cracked concrete was realized, it allows to study the behaviour of macro-cracked of concrete confined and subjected to dry gas flow or very moist air at different temperatures. Multiaxial mechanical tests are coupled to the permeability measurements of sound concrete and micro-cracked by freezing and thawing, which allow to measuring the permeability under deviatoric load-unload with the effect of pre-cracking under stress. We also effectuated a test of relative permeability of concrete as a function of water saturation, subjected to drying and resaturation, conditioning by the different relative humidity imposed

Cette thèse est une partie du projet ONEMA pour le dimensionnement des passes à poissons et pour l’amélioration de la continuité écologique des cours d’eau. Ce travail s’est concentré sur les passes à poissons naturelles qui présentent des avantages de coût et paysager. Il s’agit d’un écoulement à forte pente autour des blocs (macro-rugosités) régulièrement repartis en quinconce avec des grands nombres de Froude. Les conditions hydrodynamiques sont alors très diverses, et peuvent être franchissables par un nombre élargi d’espèces de poisson. Ce mémoire présente les travaux réalisés à l’Institut de Mécanique des Fluides de Toulouse (IMFT). Afin d’étudier l’écoulement dans ces passes, on va mener des expériences sur des canaux réduits ainsi que des simulations numériques à l’aide du modèle Telemac 2D. L’objectif est de mieux connaître la structure de l’écoulement en fonction des conditions hydrauliques et géométriques comme le nombre, la forme et la taille des macro-rugosités. Plus particulièrement, la compréhension de l’interaction de phénomènes physiques généralement étudiés séparément, tels que le passage en régime torrentiel, l’interaction de sillage ou l’écoulement autour de macro-rugosités, a été recherchée. Des relations hauteur-débit ont été établies permettant une aider au dimensionnement des passes naturelles. Elles fournissent des critères de franchissement comme les vitesses maximales, la puissance dissipée ou la hauteur d’eau minimale. Pour atteindre une description plus locale de l’écoulement, des mesures de Vélocimétrie Acoustiques Doppler ont été conduites. Elles ont aussi permis de définir la plage de validité du modèle numérique 2D (Telemac). Ce modèle a alors était utilisé pour extrapoler les critères de franchissement pour des configurations non testées expérimentalement. Finalement, les connaissances sur l’écoulement ont été synthétisées pour définir des préconisations générales de dimensionnement. La précision des relations établies en laboratoire a pu aussi être vérifiée sur des passes réelles. L’hydrodynamique de ces passes est maintenant suffisamment connue pour savoir si un poisson peut remonter le courant et se reposer. Il restera à s’assurer que leur attractivité soit bonne et que des phénomènes liés aux échelles de longueurs de la turbulence ne présentent un obstacle au franchissement. / This thesis is supported by an ONEMA project for the design of fishways and improve ecological continuity of rivers. This work focused on nature-like fish passes that have cost and landscaped appearance advantages. There is a steep flow around the blocks (macro-roughness) regularly distributed in a staggered configuration with large Froude numbers. The hydrodynamic conditions are sufficiently different to be passable by an expanded number of fish species. This thesis presents the work carried out at the Institute of Fluid Mechanics of Toulouse (IMFT). To study the flow in these passes, experiments are conducted on physical models and numerical simulations using the Telemac 2D model. The goal is to better understand the flow structure based on hydraulic and geometric conditions such as the number, shape and size of macro-roughness. In particular, we considered the interaction of physical phenomena usually studied separately such that the passage in supercritical regime, the interaction of wake or flow around macro-roughness. The stage-discharge relationships were established to assist in the design of nature-like passes. They provide criteria useful for passability such as maximum speeds, power dissipation or minimal water height. To reach a local description of the flow measurements with an Acoustic Doppler Velocimeter were conducted. They also helped to define the valid range of the 2D model. This model was then used to extrapolate passability criteria for untested experimental configurations. Finally, the knowledge on flow has been synthesized to define general recommendations sizing. It has also been able to verify on real scale passes, the accuracy of the relations established in the laboratory. The hydrodynamics of these passes is now sufficiently described to know if a fish can swim upstream and rest. It will remain to ensure that their attractiveness is good and that phenomena related to the turbulence length scales do not present an obstacle to the fish passage.

La parution d’un certain nombre de travaux menés sur les « conjonctions de subordination », Deulofeu (1999a) sur que, Benzitoun (2006a) à propos de quand, Corminboeuf (2009) pour si, Debaisieux (2006) concernant parce que, quoique, puisque et bien que, etc., a permis de rendre justice à la pluralité des fonctionnements syntaxiques des structures ainsi introduites en faisant valoir le fait qu’elles ne peuvent être constamment ramenées à une relation de dépendance grammaticale. C’est dans cette même lignée que s’inscrit ce travail qui a pour objectif de recenser, sur la base de corpus de français parlé et écrit, les différents fonctionnements syntaxiques de la conjonction alors que en français contemporain. Il apparait que les séquences ainsi introduites relèvent de cinq principaux emplois, dont un seul est à considérer comme véritablement « subordonné ». Nous associerons par ailleurs un ou plusieurs effets de sens à chacun de ces emplois. / A number of recent studies dealing about the syntactic properties of French subordinating conjunctions such as que (which, who, that) (Deulofeu, 1999a), quand (when) (Benzitoun, 2006a), si (if) (Corminboeuf, 2009) or parce que, quoique, puisque and bien que (because, since, although) (Debaisieux, 2006) have brought an increased awareness of the various grammatical behaviors of such forms, which definitely cannot be reduced to a simple relation of syntactic dependency. Using this approach, the present dissertation will attempt to offer a precise account of the conjunction alors que (whereas) as it is used in spoken and written contemporary French. It will be demonstrated that the constructions introduced by alors que can be classified into five main syntactic types, only one of them presenting a truly “subordinating” effect. In addition to analyzing their specific syntactic structure, our different types will be described according to their particular semantic value.

Cette thèse se propose d'analyser les effets des ruptures dans les trajectoires professionnelles sur l'état de santé des individus en Europe. Nous considérons ici deux ruptures : l'une en début de carrière -- l'entrée sur le marché du travail dans une économie dégradée -- et l'autre en fin de carrière -- le passage à la retraite. Entre ces deux périodes critiques, nous portons un intérêt spécifique à l'impact sur la santé d'une rupture cette fois anticipée : la peur de perdre son emploi. Nos analyses empiriques combinent des données d'enquêtes Européennes et Britanniques. Afin de pallier les problèmes d'endogénéité propres à toute analyse empirique du lien entre santé et trajectoire professionnelle, nous exerçons des chocs exogènes sur la carrière des individus. Nous utilisons ainsi une expérience naturelle (la crise pétrolière de 1973) et les caractéristiques institutionnelles telles qu’elles sont définies dans la législation de chaque pays Européen (âges légaux de passage à la retraite, degrés de protection de l’emploi, règles de scolarité obligatoire). Les résultats soulignent l'effet néfaste des ruptures au cours de la vie professionnelle sur la santé des individus, à la fois à court et à long terme.Notre projet se propose d’identifier un lien causal entre l'activité professionnelle des individus et leur catégorie d'obésité via l’utilisation de techniques économétriques spécifiques tenant compte de l'endogénéité et l'utilisation des données de la cohorte GAZEL (qui suit depuis 1989 20 000 volontaires employés chez EDF-GDF). / The main objective of this thesis is to analyse the health consequences of career shocks in Europe. It considers two actual career shocks over the lifecourse: leaving full-time education in a bad economy, and, at the other end of the age spectrum, retiring. In-between these two critical periods, it investigates how an anticipated career shock -- i.e. anticipated job loss -- damages health. Empirical analyses are conducted using large European and British surveys. We use institutional features and natural experiments to find neat instruments for causal identification~: the existence of compulsory schooling laws, the cross-country variation in employment protection legislations, the cross-country variation in retirement systems and the 1973 oil crisis. The results emphasise the causal and health-damaging impact of career shocks, both in the short and in the long-term.

Cette thèse se compose de trois études sur le rôle du désaccord en économie. Dans le premier chapitre, j’étudie l’impact des incertitudes judiciaires sur le rôle du désaccord dans le marché financier. J’ai commencé par documenter et définir ces incertitudes judiciaires, de la manière la plus approfondie et détaillée possible. L’incertitude liée à la capacité imparfaite d’observation par des régulateurs est intitulée the monitoring problem, et celle liée à la pénalité et la possibilité de payer des amendes the enforceability problem. J’introduis ces concepts dans un modèle avec frictions financières. La simulation du modèle nous montre que la capacité d’observation des régulateurs détermine la stabilité ou la fragilité du secteur bancaire. Le coût du capital n’augmente pas beaucoup dans une économie avec des incertitudes judiciaires mais le taux de retour de l’économie à l’état stationnaire baisse. Par exemple le taux de retour de l’économie à l’état stationnaire (après avoir subi un choc externe de niveau moyen) dure en moyenne 7 – 12 trimestres. Je donne des arguments que cela est en raison de changement de qualité des actifs en présences des incertitudes judiciaires. Finalement, je regarde si le modèle simulé pourrait reprendre les fluctuations du cycle économique après la crise financière et il le fait bien. En outre je donne des arguments détaillés pour l’analyse des programmes de bien-être social en présence des incertitudes judiciaires. Dans le deuxième chapitre, j’étudie la volatilité due au désaccord dans le marché du travail. J’essaye d’identifier les sources de cette volatilité élevée de manière structurelle. Ainsi, j’utilise un vecteur autorégressif avec volatilité stochastique (Time Varying Parameter SVAR) pour investiguer les propriétés de la création d’emploi aux Etats-Unis et leurs variations dans le temps. Au vu des résultats, un choc technologique semble expliquer moins de 40% des fluctuations observées de la volatilité de la création d’emplois après les années 1980 et ils indiquent que la volatilité dépend largement des chocs de demande et de prix. Les postes vacants (autrement dit, la création d’emploi) réagissaient négativement aux chocs technologiques jusqu’au début des années 90. On retrouve la même tendance pour la période récente. Ce résultat est très important pour les autorités publiques car il remet en question la création d’emplois suite à de nouvelles technologies. Le troisième chapitre est consacré au désaccord sur le marché des prêts où je montre comment le droit des faillites pourrait intensifier le problème d’aléa moral entre une entreprise débitrice et ses créanciers. Ce chapitre essaye de faire un lien entre le droit des faillites et le coût du capital en étudiant le niveau de demande des clauses restrictives dans un contrat. L’hypothèse que je vais essayer de valider empiriquement est celle-ci : si le droit de faillite devient de plus en plus en faveur des entreprises, les créanciers mettent en place de plus en plus de clauses restrictives dans le contrat (c’est-à-dire cherchent à obtenir un contrôle renforcé sur le comportement des débiteurs). Je valide l’hypothèse susmentionnée et je montre qu’une clause restrictive additionnelle baisse le taux de rentabilité par 23 points de base. Ainsi, Je donne une nouvelle interprétation des clauses restrictive par rapport à la littérature. / In this thesis I have investigated three aspects of market frictions. Chapter 1 is about financial frictions, i.e. frictional forces prevailing in the financial lending markets and how monitoring and legal fines imposed on banks affect financial fragility. Chapter 2 explores the frictional labor market, i.e. frictional forces that prevent the smooth matching process between employees and employers in labor markets. In this chapter I investigate the sources of fluctuations in labor market volatility. Chapter 3 investigates the asymmetrical information in lending markets and how bankruptcy law could potentially affect this asymmetrical information between a borrower and its lenders. In Chapter 1, I have investigated the implications of legal fines and partial monitoring in a macro-finance model. This primary motivation of this work was the unprecedented level of fines banks faced in recent years. The research in this field is very sparse and this work is one of the few to fill in the void. I have tried investigating the implications of fines and partial monitoring in static and dynamic frameworks. There is partial monitoring in the sense that dubious behavior of intermediaries is not always observed with certainty. Moreover intermediaries can pay some litigation fees to mitigate the punishment for their conduct should they get caught. Several insights can be drawn from introducing such concepts in static and dynamic frameworks. Partial monitoring and legal fines make the incentive constraint of intermediaries more relaxed, in the sense that bankers are required to pledge less collateral to raise fund. This decrease in the asset pledgeability pushes the corporate spread down. In a dynamic set-up due to changes in asset qualities caused by such possibilities, recovery in output and credit become sluggish in response to an adverse financial shock. The dynamic implications of the model for the post-crisis period are investigated. This paper calls for further research to broaden our understandings in how legal settlements interact with banks' behaviors. In Chapter 2 (joint with Elisa Guglielminetti) I have investigated the time-varying property of job creation in the United States. Despite extensive documentation of the US labor market dynamics, evidence on its time-varying volatility is very hard to find. In this work I contribute to the literature by structurally investigating the time-varying volatility of the U.S. labor market. I address this issue through a time-varying parameter VAR (TVP-VAR) with stochastic volatility by identifying four structural shocks through imposing robust restrictions based on a New Keynesian DSGE model with frictional labor markets and a large set of shocks. The main findings are as follows. First, at business cycle frequencies, the lion share of the variance of job creation is explained by cost-push and demand shocks, thus challenging the conventional practice of addressing the labor market volatility puzzle à la Shimer under the assumption that technology shocks are the main driver of fluctuations in hiring. Second, technology shocks had a negative impact on job creation until the beginning of the '90s. This result is reminiscent of the “hours puzzle” à la Gali. In Chapter 3 (joint with Garence Staraci) I provide an additional rationale why creditors include covenants in their contracts. The central claim is that covenants are not only included as a means of shifting the governance from debtors to creditors, but also to potentially address the concerns creditors might have about how the bankruptcy law is practiced. To investigate this claim, I take advantage of the fact that covenants are nullified inside bankruptcy. This fact permits us to show that any change to the bankruptcy law affects the spread through changes that it brings to the contractual structure...