A estampabilidade das ligas de alumínio é um assunto que interessa à vários segmentos industriais, pois é largamente aplicada na fabricação de peças e componentes. Entre dois processos de solidificação do alumínio, a solidificação de placa (DC) e o vazamento contínuo via caster (CC), o processo caster apresenta um histórico de condições inferiores para estampagens mais críticas nestas ligas. Este estudo visa avaliar as diferenças entre os processos de fabricação para chapas na liga AA1050 laminadas para 1,80mm, na condição recristalizada, durante a laminação e tratamento térmico e, caracterizar a microestrutura e textura. Ensaios de conformabilidade foram utilizados para identificar qual processo apresenta o melhor desempenho para estampagem. Para realização do estudo foram analisados três lotes de produção da Companhia Brasileira de Alumínio CBA, proveniente de processo de vazamento tipo placa (DC), e dois outros lotes provenientes de processo de vazamento tipo caster (CC) sendo, um com homogeneização intermediária e outro sem homogeneização. Os materiais foram processados em laminadores e fornos de escala industrial. A estrutura metalúrgica foi caracterizada através de ensaios metalográficos ao longo dos processos, obtendo-se a distribuição de intermetálicos e a estrutura cristalina através de microscopia ótica. A microscopia eletrônica também foi empregada para identificação dos precipitados. Ensaio de tração foi utilizado para identificar a variação das propriedades mecânicas ao longo do processo. Na condição final, ou seja, após laminação para 1,80mm de espessura com posterior recozimento foram utilizados os ensaios de orelhamento (earing), Erichsen, análise da anisotropia e levantamento da curva limite de conformação (CLC), para identificar qual processo apresenta o melhor resultado de conformação. A fim de entender as mudanças ocorridas nos materiais, foi estudada a macrotextura gerada no material ao longo da espessura da chapa. Na condição final foi realizada a microtextura no processo placa e caster sem homogeneização. A microestrutura dos materiais apresentou resultados distintos entre os processos, o material de placa mais homogêneo, tanto na distribuição dos intermetálicos quanto na estrutura granular. As propriedades mecânicas do caster, (LRT, LE e Dureza) ficaram um pouco superiores às do material de placa. O ensaio de Erichsen indicou que o material de placa resistiu a uma maior profundidade de conformação. No ensaio de orelhamento o caster sem homogeneização apresentou o menor índice, porém o material de placa apresentou a maior profundidade de conformação. As texturas encontradas ao longo dos processos foram principalmente a tipo Goss , Cubo e Cubo rodado . Também foram identificadas texturas típicas de cisalhamento após a laminação a frio, Dillamore {4 4 11} e Taylor {11 11 8}. A textura tipo S~ que é favorável a conformabilidade de metais CFC, apareceu ao final dos processos. Na curva limite de conformação (CLC) foi possível identificar que o caster com homogeneização apresentou o melhor resultado que os outros dois processos. Os ensaios de conformabilidade indicaram que o material de placa tem uma estampagem mais profunda, enquanto que o material de caster sem homogeneização tem um orelhamento menor. / Stampability of aluminum alloys is a subject of interest to several industrial sectors because they are largely used in the fabrication of several parts and components. The choice is based upon the stampability and the relative manufacturing capability in relation to other aluminum alloys that contain larger amounts of alloying elements and, consequently, higher mechanical properties. When comparing two solidification processes, namely the direct chill (DC) and the continuous casting (CC) via caster, the CC process historically presents inferior performance for the more critical stampings in these alloys. This study aims at the evaluation of the differences between the fabrication processes (routes) of AA1050 rolled to 1,80mm sheets in the conditions as annealed, rolled and after heat treatment and to characterize their microstructure and texture. Stamping tests have been performed to identify which process presents best stamping performance. To carry out these studies three production lots from the Companhia Brasileira de Alumínio CBA have been employed namely one from the DC method and two other lots from the DC method, one with and one without an intermediate homogenization treatment. All materials have been processed in rolling mills and ovens in an industrial scale. The metallurgical structure has been characterized by optical and electronic microscopy throughout the processes analyzing the intermetallics and precipitate distribution. Tensile tests have been perfumed to identify the evolution of the mechanical properties throughout the process. In the final condition, i.e., after rolling down to 1,80mm and annealing, earing tests, Erichsen drawing tests and anisotropy have been evaluated together with the Forming Limit Diagram( FLD), to evaluate which process presented the best results in terms of formability. In order to understand the changes that occurred, the macrotexture has been studied along the thickness of the rolled sheets. In the final condition, the microtexture of the DC and the CC without homogenization have been compared. Different microstructures have been obtained for the studied processes: the DC material was more homogeneous, both in terms of intemetallic distribution and grain size. The mechanical properties of the CC material, in terms of TS, YS and hardness, were sligthly higher than those for the DC material. Erichsen test showed that the DC material takes higher deformations. Earing tests showed that the CC material without homogeneization presented the best results however the DC material presented better cup height. The textures analyzed for the different process stages were mainly of the Goss , Cube and rotated Cube types. Also some typical shear textures of the Dillamore {4 4 11} and Taylor {11 11 8} types have been observed in cold rolled sheets. The S~ type, which is favourable for the formability of FCC metals, showed up in the final processing stages. The FLD showed that the CC with homogenization presented better results when compared to the other two processing routes. The stamping tests showed that the DC material presents higher drawability while the CC material without homogenization presents lower earing index.

Made available in DSpace on 2016-04-04T18:27:55Z (GMT). No. of bitstreams: 1 Ana Paula Gomes Moreira.pdf: 2034442 bytes, checksum: 75e3a66dafdd6737a6288c97989e7446 (MD5) Previous issue date: 2010-12-07 / This work is circumscribed within the framework of School Psychology, as a field of application, research and intervention. Its development tried to discuss the application of the concept of limit-situation, created by Ignacio Mart?n-Bar?, to the context of early childhood education. The limit-situation refers to the situation that somehow plays negative impact to the development of children. We believe the development process as a dynamic and historically process detailed, so the discussion is linked to notions of risk, protection, vulnerability and resilience. Based on the principles of Liberation Social Psychology and the Historical and Dialectical Materialism, we made an analysis of field diaries produced by professionals of psychology who worked in an Municipal Kindergarten School during 2008 and 2009. Then, we delimited the dimensions of everyday life or elements of reality that characterized the occurrence of limit-situations in the view of key agents involved with the Early Childhood Education: psychology professionals, educators and families and / or children. This elements emphasizes the dimensions of violence, conflicting relations between the educational team members and breakdown of education politics. / Este trabalho est? circunscrito nos marcos da Psicologia Escolar, enquanto ?rea de aplica??o, pesquisa e interven??o. A sua realiza??o buscou discutir a aplica??o do conceito de situa??o-limite, delineado por Ign?cio Mart?n-Bar?, ao contexto da Educa??o Infantil. A situa??o-limite refere-se ? situa??o que, de alguma forma, exerce impacto negativo sobre o desenvolvimento das crian?as. Entendemos o processo de desenvolvimento como din?mico e historicamente circunstanciado e, portanto, a discuss?o sobre situa??es-limite no ?mbito do desenvolvimento est? vinculada ?s no??es de risco, prote??o, vulnerabilidade e resili?ncia. Fundamentados nos princ?pios da Psicologia Social da Liberta??o e do Materialismo Hist?rico e Dial?tico, realizamos a an?lise dos di?rios de campo produzidos por profissionais de psicologia que atuaram em uma Institui??o Municipal de Educa??o Infantil no per?odo de 2008 a 2009. Delimitamos, por meio de um processo construtivo-interpretativo, grandes categorias referentes aos elementos da realidade que caracterizassem a ocorr?ncia de situa??es-limite na vis?o dos principais agentes envolvidos com a Educa??o Infantil: os pr?prios profissionais de psicologia, os educadores e a as fam?lias e/ou crian?as. A elabora??o de tais categorias demonstra que estes elementos referem-se, prioritariamente, ? dimens?es de viol?ncia, rela??es conflituosas entre os membros da equipe educativa e desagrega??o das pol?ticas de educa??o.

Este estudo teve como objetivo comparar o efeito agudo de três métodos de recuperação pós-exercício (recuperação ativa, passiva e crioterapia) sobre o desempenho físico, marcadores fisiológicos, psicológicos, bioquímicos e imunológicos, bem como os sentidos atribuídos por sujeitos treinados. Doze corredores treinados em provas de meio-fundo e fundo, voluntários, do gênero masculino (idade: 20,6 ± 1,7 anos; Massa corporal: 64,1 ± 5,6 Kg; Estatura: 1,74 ± 0,05 m.; Gordura corporal: 6,8 ± 2,7 %; VO2máx: 57,0 ± 5,9 mL.Kg-1.min-1; vVO2máx: 15,7 ± 1,7 Km/h; Tlim: 603 ± 243 s.) realizaram três corridas de 30 minutos, em esteira rolante, a 80% da vVO2max, estimado através de teste incremental. Em seguida foram aplicados os métodos de recuperação ativa (corrida a 40% da vVO2max), passiva (sentado em uma cadeira) e crioterapia (imersão em água com gelo quebrado a 5° [±1º] até a altura da crista ilíaca) por 20 minutos, em ordem contrabalanceada. Logo após, os sujeitos realizaram um teste de corrida (Tlim) a 100% da vVO2max. Uma semana antes da realização dos testes, foi realizado um procedimento de familiarização com os métodos de recuperação a serem aplicados. As taxas dos marcadores tempo limite de corrida, distúrbio de humor total, razão fadiga/vigor, percepção subjetiva de esforço, frequência cardíaca, lactato, IL-6, TNF-, leucócitos, neutrófilos, monócitos e linfócitos foram mensuradas no momento anterior a corrida (M1), após a corrida na esteira rolante (M2), imediatamente após a aplicação dos métodos recuperativos (M3) e após a aplicação do teste de corrida tempo limite (M4), exceto a PSE que foi mensurado no M1 e M4, e o Tlim e a entrevista (para análise de representações sociais) que foram realizadas no M4. Foram retirados 18ml de sangue venoso, em cada momento de coleta, para realização dos procedimentos de análise sanguínea. Após os resultados concluímos que o uso dos métodos de recuperação ativa, passiva ou crioterapia durante 20 minutos após uma corrida de 30 minutos a 80%vVO2máx não afetou o desempenho subsequente de corrida a 100%vVO2máx até a exaustão. A crioterapia promove maior queda na frequência cardíaca e menor remoção de lactato após exercício a 80%vVO2máx comparada aos métodos de recuperação ativa e passiva, promovendo maior produção de lactato e menor resposta cronotrópica durante corrida subsequente a 100%vVO2máx até a exaustão e que o uso da crioterapia não interfere na percepção de esforço e nas respostas psicológicas após o esforço, mas induz uma maior perturbação sobre os marcadores imunológicos, especificamente, sobre leucócitos e linfócitos. Na perspectiva qualitativa, verificou-se uma variedade discursiva sobre a escolha do melhor método de recuperação. Os sentidos que mais se destacaram foram: uma maior leveza do corpo, acalmando a musculatura e fica mais... assim, relaxado na crioterapia; ação natural do corpo e quando se está cansado paramos para descansar na recuperação passiva e; continuidade de movimentos, operabilidade, manutenção do ritmo e da normalidade na recuperação ativa / This study aimed at comparing the acute effect of three post-exercise recovering methods (active, passive and cryotherapy recovering) on the physical performance, physiological, psychological, biochemical, immunological, performance and sense markers attributed by trained subjects. Twelve male volunteer runners (aged 20.6 + 1.7 years old; Body mass: 64.1 + 5.6 kg; Height: 1.74 + 0.05 m; Body fat 6.8 + 2.7%; VO2máx: 57,0 ± 5,9 mL.Kg-1.min-1; vVO2máx: 15,7 ± 1,7 Km/h; Tlim: 603 ± 243 s.) trained in middle-distance and distance races have accomplished three 30-minute runnings on a treadmill at 80% of the vVO2, estimated through an incremental test. After that, the active (running at 40 % of the vVO2max), passive (sitting on a chair) and cryotherapy (immersion in water with broken ice at 5° [+ 1°] until the height of the iliac crest) recovering methods were applied for 20 minutes in counterbalanced order. Then, the subjects carried out a running test (Tlim) at 100% of the vVO2max. One week before the accomplishment of the tests, a procedure in order to familiarize them with the recovering methods to be applied was carried out. The running limit time markers, total humor disturb, fatigue/vigor ratio, subjective perception of effort, heart rate, lactate, IL-6, tnf-, leucocytes, neutrophils and lymphocytes rates were measured at the moment before the running (M1), after running on the treadmill (M2), immediately after applying the recovering methods (M3) and after doing the limit time running test (M4), except the PSE, which was measured in M1 and M4, and the Tlim and the interview (to analyze the social representations), which were carried out in M4. 18 ml of venous blood were taken, in each moment of the blood collecting so as to carry out the blood analysis procedures. After the results, we reached the conclusion that the use of active, passive and cryotherapy recovering methods within 20 minutes after a 30-minute running at 80%vVO2máx hasnt affect the performance of a following running at 100%vVO2máx until exhaustion. The cryotherapy promotes a higher fall in the heart rate and a smaller lactate removal after the exercise at 80%vVO2máx, compared to the active and passive recovering methods, thus promoting higher production of lactate and a smaller chronotropic response during the follow-up running at 100%vVO2máx until exhaustion; and that the use of cryotherapy does not interfere in the effort perception or in the psychological responses after effort, but it leads to a higher disorder on the immunologic markers, specifically on the leucocytes and lymphocytes. Within the qualitative perspective, it was verified a discursive variety about the choice of the best recovering method. The senses which were highlighted most were, a larger lightness of the body, calming the muscles down and it gets sort of, relaxed in cryotherapy; natural action of the body and when youre tired we stop to rest in the passive recovering; and, continuity of movement, operability, keeping the rhythm and the normality in the active recovering

Neste trabalho estão apresentadas novas estratégias para funcionalizar superfícies de ouro baseadas na sustentação de bicamadas lipídicas em superfícies de sensores de imagem por Ressonância de Plasmons de Superfície (SPRi) e a construção de um biosensor para detecção de citocromo c. SPRi é uma técnica ótica de gravimetria em tempo real. Por meio de medidas de variações de índice de refração (n) próximas a uma interface, a adsorção e desorção de moléculas podem ser mensuradas. Inicialmente testamos várias estratégias para encontrar um suporte adequado que se ligasse na superfície de ouro e que oferecesse sustentação e estabilidade para a bicamada de fosfolipídeo biotinilado. Estudos de FT-IR e MEV mostraram que a quitosana facilita a formação de uma bicamada íntegra de fosfolipídeos, de tal modo, que a mesma alcança valores de espessura próximos àqueles previstos, ~ 34,5 Å. Além disso, mostramos que esse sistema apresenta vantagens perante outros modelos, tais como, (poli-lisina/fosfolipídeos) e (tiol hidrofóbico/fosfolipídeo). Utilizando-se o complexo químico biotina/estreptoavidina conseguimos imobilizar o anticorpo anti cit c na bicamada, mantendo-o afastado da superfície de ouro. A construção do biosensor foi acompanhada com experimentos de SPRi. O limite de detecção de citocromo c atingido foi de 10-11mol/L. Um sensor construído somente com BSA e anticorpo anti cit c apresentou sensibilidade semelhante. Esta sensibilidade é em torno de três ordens de grandeza superior aos experimentos de imunoblotting usualmente utilizados para detecção de cit c. A principal limitação deste biosensor, tal como de outros imunoensaios, está intimamente ligada às vantagens e desvantagens dos anticorpos como ferramentas analíticas. / In this work we developed new strategies to functionalize gold surfaces based on the support of lipid bilayers on the surfaces of surface plasmon resonance imaging sensors (SPRi) and the construction of a biosensor for detection of cytochrome c. SPRi is an optical gravimetric real time technique. Through measurements of changes in refractive index (n) in close proximity to an interface, the adsorption and desorption of molecules can be measured. Initially we tested several strategies for finding a suitable medium that would adsorb on the gold surface and also support and stabilize a biotinylated phospholipid bilayer. Studies of FT-IR and SEM showed that chitosan induces the formation of an intact phospholipid bilayer, so that it reaches thickness values close to those expected, ~ 34.5 Å. Furthermore, we showed that this system has advantages in relation to other models, such as (poli-lisine/phospholipids) and (thiol hydrophobic / phospholipid). Using the chemical complex biotin/streptavidin anti cyt c antibody could be immobilized in the bilayer, keeping it away from the gold surface. The construction of the biosensor was accompanied with SPRi experiments. The limit of detection of cytochrome c was achieved from 10-11mol / L. A sensor built only with BSA and anti cyt c showed similar sensitivity. This sensitivity is about three orders of magnitude higher than the immunoblotting experiments commonly used for detection of cyt c. The main limitation of this biosensor, like in other immunoassays, is linked to the advantages and disadvantages of antibodies as analytical tools.

La mise en œuvre de la prescription de l’action publique n’est pas, en principe, subordonnée à la connaissance de l’infraction par les personnes pouvant déclencher les poursuites pénales. Le législateur retient en effet comme point de départ du délai de prescription le jour de la commission des faits et non celui de leur découverte. Cette règle connaît toutefois une exception lorsque l’infraction est dite clandestine. Parce que le ministère public et la victime n’ont pas pu avoir connaissance de l’existence de cette infraction, la prescription ne court pas tant que les faits ne sont pas apparus et n’ont pu être constatés dans des conditions permettant l’exercice de l’action publique. L’exception de clandestinité empêche donc le temps de produire son effet destructeur sur l’action publique. Sa mise en œuvre évite ainsi que certaines infractions restent impunies par le seul jeu de l’écoulement du délai. S’il ne fait aucun doute que la clandestinité d’une infraction constitue un obstacle à la prescription de l’action publique, la notion même de clandestinité reste à circonscrire. Elle recouvre en effet, en droit positif, de multiples réalités qui rendent impossible sa systématisation. Aux termes de la recherche, il apparaît que le critère déterminant de la clandestinité consiste dans l’ignorance légitime de l’existence de l’infraction par les personnes habilitées à mettre en mouvement l’action publique. En application de l’adage contra non valentem agere non currit praescriptio, cette ignorance caractérisée devrait autoriser le report du point de départ de la prescription de l’action publique de toute infraction au jour où les faits peuvent être constatés par le ministère public ou par la personne lésée. / In criminal matters, the setting of the time limit for prosecution is theoretically not subject to the knowledge of the offense by the people who can trigger criminal proceedings. Indeed, according to the law, the starting point of the said time limit period is the day the offense was committed, and not the day it was discovered. However, an exception to this rule exists when the offense is said to be clandestine. When both the prosecutor and the victim could not have know of the existence of this offense, the time-limit period does not run until the facts appear and can be noticed in the same conditions. An exception of clandestinity prevents time to produce its destructive effect on the prosecution. It avoids certain offenses to remain unpunished by the single flow of time. Undoubtedly, clandestinity is an obstacle to the prosecution of an offense. Yet, the notion itself remains to be circumscribed. In substantive law, clandestinity refers to a wide variety of realities ; its systematization is thus impossible. In a prospective approach, a criterion is to be found in the justifiable ignorance of the offense by those who can initiate a criminal action. Under the adage “contra non valentem agere non currit praescriptio”, this specific ignorance allows postponement of the starting point of the time limit for prosecution of any offence on the day on which the facts have been noticed by the prosecutor or the victim.

Muitos sistemas físicos são modelados por sistemas dinâmicos discretos. Com o advento da tecnologia digital os sistemas discretos tornaram-se ainda mais importantes, sendo assim, o desenvolvimento de ferramentas analíticas para este tipo de sistema é de grande importância. Neste trabalho, estudam-se alguns dos principais resultados relacionados à estabilidade de sistemas dinâmicos discretos, e alguns novos são propostos. É bem conhecido na literatura que a estabilidade de um ponto de equilíbrio pode ser caracterizada pelo Método Direto de Lyapunov, via uma função auxiliar denominada função de Lyapunov. LaSalle, ao estudar a teoria de Lyapunov, estabeleceu uma importante relação entre função de Lyapunov e conjuntos limites de Birkhoff, que deu origem ao Princípio de Invariância de LaSalle. Este, entre outras coisas, permite a análise de estabilidade assintótica. Tanto o Método Direto de Lyapunov quanto o Princípio de Invariância requerem que a variação da função de Lyapunov seja não positiva ao longo das trajetórias do sistema. Em sistemas com comportamentos mais complexos, dificilmente encontra-se uma função com esta propriedade. Neste trabalho, propõe-se uma versão mais geral do Princípio de Invariância para sistemas discretos, a qual não exige que a variação da função de Lyapunov seja sempre não positiva. Com isto, a obtenção de funções deste tipo torna-se mais simples e muitos problemas, que antes não poderiam ser tratados com a teoria convencional, passam a ser tratados através deste novo resultado. Os resultados desenvolvi- dos, neste trabalho, são úteis para encontrar estimativas de atratores de sistemas não-lineares discretos. / Many physical systems are modeled by discrete dynamic systems. With the evolution digital technology, the discrete systems became still more important, so the development of analytic tools for this type of system has high importance nowadays. ln this work, some of the main results in stability of discrete dynamic systems are studied and some new ones are proposed. lt is well known in the literature that the stability of an equilibrium point may be characterized by the Lyapunov\'s Direct Method, with a function known as Lyapunov auxiliary function. LaSalle, when studying the Lyapunov theory, established an important relationship between Lyapunov function and Birkhoff limit sets. Then, he created the Lasalle\'s lnvariance Principle. This, among other features, allows the analysis of asymptotically stability. Both the Lyapunov\'s Direct Method and the lnvariance Principle request the variation of the Lyapunov function to be negative semidefinite along the system trajectory. In systems with more complex behaviors, a function is hardly found with this property. This work developed a more general version of the lnvariance Principle for discrete systems, which does not require the variation of the Lyapunov function to be always negative semidefinite. This new theory enables to find these functions easily and many insoluble problems, which could not be treated with the conventional theory before, become treatable by this new result. The results of this work are useful to find estimates of discrete nonlinear systems atractors.

Cette thèse porte sur l'étude probabiliste des réponses démographique et génétique de populations à certains événements ponctuels. Dans une première partie, nous étudions l'impact de catastrophes tuant une fraction de la population et survenant de manière répétée, sur le comportement en temps long d'une population modélisée par un processus de branchement. Dans un premier temps nous construisons une nouvelle classe de processus, les processus de branchement à états continus avec catastrophes, en les réalisant comme l'unique solution forte d'une équation différentielle stochastique. Nous déterminons ensuite les conditions d'extinction de la population. Enfin, dans les cas d'absorption presque sûre nous calculons la vitesse d'absorption asymptotique du processus. Ce dernier résultat a une application directe à la détermination du nombre de cellules infectées dans un modèle d'infection de cellules par des parasites. En effet, la quantité de parasites dans une lignée cellulaire suit dans ce modèle un processus de branchement, et les "catastrophes" surviennent lorsque la quantité de parasites est partagée entre les deux cellules filles lors des divisions cellulaires. Dans une seconde partie, nous nous intéressons à la signature génétique laissée par un balayage sélectif. Le matériel génétique d'un individu détermine (pour une grande partie) son phénotype et en particulier certains traits quantitatifs comme les taux de naissance et de mort intrinsèque, ou sa capacité d'interaction avec les autres individus. Mais son génotype seul ne détermine pas son ``adaptation'' dans le milieu dans lequel il vit : l'espérance de vie d'un humain par exemple est très dépendante de l'environnement dans lequel il vit (accès à l'eau potable, à des infrastructures médicales,...). L'approche éco-évolutive cherche à prendre en compte l'environnement en modélisant les interactions entre les individus. Lorsqu'une mutation ou une modification de l'environnement survient, des allèles peuvent envahir la population au détriment des autres allèles : c'est le phénomène de balayage sélectif. Ces événements évolutifs laissent des traces dans la diversité neutre au voisinage du locus auquel l'allèle s'est fixé. En effet ce dernier ``emmène'' avec lui des allèles qui se trouvent sur les loci physiquement liés au locus sous sélection. La seule possibilité pour un locus de ne pas être ``emmené'' est l'occurence d'une recombination génétique, qui l'associe à un autre haplotype dans la population. Nous quantifions la signature laissée par un tel balayage sélectif sur la diversité neutre. Nous nous concentrons dans un premier temps sur la variation des proportions neutres dans les loci voisins du locus sous sélection sous différents scénarios de balayages. Nous montrons que ces différents scenari évolutifs laissent des traces bien distinctes sur la diversité neutre, qui peuvent permettre de les discriminer. Dans un deuxième temps, nous nous intéressons aux généalogies jointes de deux loci neutres au voisinage du locus sous sélection. Cela nous permet en particulier de quantifier des statistiques attendues sous certains scenari de sélection, qui sont utilisées à l'heure actuelle pour détecter des événements de sélection dans l'histoire évolutive de populations à partir de données génétiques actuelles. Dans ces travaux, la population évolue suivant un processus de naissance et mort multitype avec compétition. Si un tel modèle est plus réaliste que les processus de branchement, la non-linéarité introduite par les compétitions entre individus en rend l'étude plus complexe / This thesis is devoted to the probabilistic study of demographic and genetical responses of a population to some point wise events. In a first part, we are interested in the effect of random catastrophes, which kill a fraction of the population and occur repeatedly, in populations modeled by branching processes. First we construct a new class of processes, the continuous state branching processes with catastrophes, as the unique strong solution of a stochastic differential equation. Then we describe the conditions for the population extinction. Finally, in the case of almost sure absorption, we state the asymptotical rate of absorption. This last result has a direct application to the determination of the number of infected cells in a model of cell infection by parasites. Indeed, the parasite population size in a lineage follows in this model a branching process, and catastrophes correspond to the sharing of the parasites between the two daughter cells when a division occurs. In a second part, we focus on the genetic signature of selective sweeps. The genetic material of an individual (mostly) determines its phenotype and in particular some quantitative traits, as birth and intrinsic death rates, and interactions with others individuals. But genotype is not sufficient to determine "adaptation" in a given environment: for example the life expectancy of a human being is very dependent on his environment (access to drinking water, to medical infrastructures,...). The eco-evolutive approach aims at taking into account the environment by modeling interactions between individuals. When a mutation or an environmental modification occurs, some alleles can invade the population to the detriment of other alleles: this phenomenon is called a selective sweep and leaves signatures in the neutral diversity in the vicinity of the locus where the allele fixates. Indeed, this latter "hitchhiking” alleles situated on loci linked to the selected locus. The only possibility for an allele to escape this "hitchhiking" is the occurrence of a genetical recombination, which associates it to another haplotype in the population. We quantify the signature left by such a selective sweep on the neutral diversity. We first focus on neutral proportion variation in loci partially linked with the selected locus, under different scenari of selective sweeps. We prove that these different scenari leave distinct signatures on neutral diversity, which can allow to discriminate them. Then we focus on the linked genealogies of two neutral alleles situated in the vicinity of the selected locus. In particular, we quantify some statistics under different scenari of selective sweeps, which are currently used to detect recent selective events in current population genetic data. In these works the population evolves as a multitype birth and death process with competition. If such a model is more realistic than branching processes, the non-linearity caused by competitions makes its study more complex

Nesta tese, o limite não re1ativistico em teorias quânticas de campos em 2+1 dimensões é discutido1 perturbativamente, através da introdução de um corte intermediário que permite 0 cálculo de.expansão /P/m das amplitudes quânticas. especificando a origem, no espaço dos estados intermediários, de cada uma. das contribuições. Este procedimento é aplicado à teoria 4 e um esquema de redução a nível das amplitudes, que identifica a contribuição do setor de baixas energias com 0 resultado da teoria não re1ativistica, é proposto. Quando aplicado á teoria de Chern-Simons escalar, este procedimento sugere correlações relativísticas para o espalhamento Aharonov-Bohm. / n this thesis, the nonrelativistic limit of quantum field theories in 2 + 1 dimensions is discussed, perturbatively, through the introduction of an intermediate cutoff which generates the /p/m expansion of the quantum amplitudes and specifies the origin of each contribution in the space of the intermediary states. This scheme is applied to the theory 4 and a reduction procedure for the amplitudes that identify the low energy sector contribution with the results of the nonrelativistic theory is proposed. When applied to the scalar Chern-Simons theory, this procedure gives relativistic corrections to the Aharonov- Bohm scattering.

Traditionally, flexible pavement design relies on past experience and semi-empirical methods developed through a combination of element testing and modelling. Element testing in this area especially, has centred on the performance of clean sands. This is in conflict with actual practice where a wide range of fines and soil gradations could be present in a real-world project. This research investigates the characteristics of natural sands and examines the influence of these marginal materials in pavement design using element testing and controlled modelling of an actual flexible pavement system. The element tests concentrated on separate, natural soils sourced from Kazakhstan which had similar mineralogy, but varying amounts of fines. One of the key parameters examined was equivalent void ratio and its efficiency to account for the behaviour change in granular materials which comes from increased fines content. Starting with monotonic triaxial results combined with strength-dilatancy methods it was shown that prediction of shear strength in a silty-sand could be improved by 13%. Incorporating this finding into repeat load triaxial tests, the transitions between elastic, plastic, and ratcheting failure behaviours (i.e. shakedown boundaries), commonly used to help predict the lifespan of a flexible pavement, were examined. It was seen that cycling a silty-sand, the stress path and yield surface could change depending on the fines content. The Cambridge Airfield Pavement Tester (APT) was designed and constructed to measure permanent subgrade deformation resulting from various surface loads. The number of input variables required to design flexible pavements is one of the most frequently stated problems in the field; variation of aircraft types, environmental conditions, and materials makes mechanistic design of the soil foundation problematic. Accordingly physical pavement modelling continues to be the only experimental method that allows input parameters and material characteristics to be examined simultaneously. Digital image correlation (DIC) was incorporated into the system; the first time this technology has been used in flexible pavement research. A Null Pressure System was also installed to measure soil stress distributions. It was observed that the critical failure mechanisms for thin and thick surficial layers are different, resulting in changes in the rates of surface rutting. Finally, by combining element and APT results, knowledge of the causal relationships between subsurface deformation and failure mechanisms in flexible pavement were advanced. In-situ soils, which are frequently incorporated into subgrade designs, were found to have a substantial role in the serviceability of the pavement. Correlations between element tests and APT results highlighted the complicated loading and boundary conditions present in a pavement.

Sistemas de reação-difusão têm sido largamente estudados em diferentes contextos e através de diferentes métodos, motivados pela sua constante aparição em modelos de interação em contextos químicos, biológicos e ainda em fenômenos ecológicos. Neste trabalho nos propomos a estudar existência e unicidade - tanto do ponto de vista local como global - de soluções para uma classe de sistemas de reação-difusão acoplados, denidos em R^2, utilizando como ferramenta a teoria de semigrupos de operadores lineares. Apresentamos dois importantes exemplos: o modelo de Rosenzweig-MacArthur e um particular caso da classe de equações lambda-omega. Para o primeiro obtemos um resultado de existência e unicidade global utilizando um método de comparação envolvendo sub e super-soluções. Investigamos ainda a existência de soluções de ondas viajantes periódicas através do teorema de Bifurcação de Hopf. Já para o caso da equação lambda-omega obtemos a existência e unicidade de solucões, entretanto, a partir da aplicação da teoria de semigrupos de operadores lineares. / Reaction-diffusion systems have been widely studied in a broad variety of contexts in a large amount of disctinct approaches. It is due firstly by their constant appearance in interaction models in disciplines such as chemistry, biology and, more specific, ecology. The aim of this thesis is to provide an existence-uniqueness result - both from the local as well as from the global point of view - for solutions of a particular class of coupled reaction-diffusion systems defined over R^2. It is done applying the well established theory of semigroups of linear operators. Two remarkable examples of such systems are discussed: the Rosenzweig-MacArthur predator-prey model and a special case of lambda-omega class of equations. For the former one, an existence and uniqueness result is obtained through a comparison method - based on the notions of lower and upper solutions. Moreover, we investigate the existence of periodic travelling wave solutions via a Hopf bifurcation theorem. For the lambda-omega model another existence and uniqueness for solutions is obtained, on its turn, through the machinery obtained previously from the theory of semigroups for linear operators.