No trabalho estuda-se o crescimento de trincas em carga monotônica e cíclica nos casos de materiais quase-frágeis, introduzindo uma lei de dano cíclico. Revisam-se conceitos sobre modelos coesivos, leis de carga-descarga, leis de evolução de dano e efeito de escala. É seguido o modelo coesivo irreversível proposto por Wang e Siegmund (2006). Em particular se dá ênfase aos efeitos de escala não estatísticos. O modelo de zona coesiva irreversível apresenta uma formulação de dano e considera carregamento em fadiga. Quando o tamanho estrutural é reduzido (ou as trinca se extendem), a fratura por fadiga não mais ocorre por propagação de trinca, mas sim por uma decoesão uniforme. O objetivo desde trabalho é implementar este modelo e verificar sua potencialidade na captura de efeitos de escala, comparando com experimentos e dados disponíveis na literatura. / At present work is intended to study crack growth in cyclic and monotonic loading in the case of quasi-brittle materials, introducing a damage mechanism, is reviewed concepts of cohesive models, loading-unloading laws, damage evolution laws and effect of scale. The irreversible cohesive zone model proposed by Wang e Siegmund (2006) is followed. In particular emphasizes in the not statistical size effects. The irreversible cohesive zone model, presents a damage formulation and considers fatigue loading. It is demonstrated in this study that, when the structure size is reduced (or extend cracks), the fatigue fracture no longer occurs by crack propagation, then occurs by uniform decohesion . The objetive of this work is implementing this model and verify its capability to capture the scale effect compared with experiments and data available in literature.

Este trabalho procura responder a questão: \"quais as barreiras conceituais que impedem a compreensão da segunda lei da Termodinâmica pelos estudantes? A partir de três questões apresentadas a estudantes do terceiro ano do ensino médio e do primeiro ano do curso superior de licenciatura em física, foram coletadas as respostas produzidas; posteriormente analisadas, permitiram a explicitação de concepções que, confrontadas com as idéias da Termodinâmica clássica, revelaram um raciocínio inadequado. A idéia de sistema centrado no objeto, parece constituir uma barreira conceitual difícil de transpor; assim também ocorre com os conceitos de processo e transformação exibidos pelo senso comum. Tais conceitos são fundamentais para o estabelecimento da Termodinâmica e devem ser pensados no trabalho em sala de aula capaz de produzir conflitos cognitivos com meta a uma mudança conceitual. Por outro lado, numa perspectiva histórica, foi possível identificar alguma ressonância entre as idéias dos estudantes e o desenvolvimento da concepção de calor; focalizamos especialmente as idéias de Carnot e de Clausius ao longo da elaboração das leis da Termodinâmica. O trabalho também identificou lacunas decorrentes da forma como os conteúdos científicos são apresentados na sala de aula e nos livros didáticos o que pode explicar as dificuldades encontradas. Finalmente, o trabalho apresenta subsídios de relevância pedagógica que podem contribuir para a melhoria do ensino da Termodinâmica no nível médio, com atividades especiais que tocam nos pontos conflitantes entre as concepções dos estudantes e o conhecimento científico. / This work aims to answering the following question: what are the conceptual barriers that prevent students from understanding the second law of Thermodynamics ? Starting from three questions that were proposed to third year secondary school and to first year physics teaching university students, the collected answers were analysed and led to an explicitation of conceptions that disclose inadequate reasoning when confronted with the ideas of classical Thermodynamics. The idea of a system centered on the object seems to be a conceptual barrier that is difficult to overcome and the same happens with the concepts of process and change that are usual in commonsense. But these concepts are essential for the fundamentals of Thermodynamics and should be used in class work to create cognitive conflicts aiming to a conceptual change. On the other hand, from a historical perspective, it was possible to identify some of the students ideas in the development of the concept of heat particularly in the development of the ideas of Carnot and Clausius in the elaboration of the laws of thermodynamics. The work has also identified gaps resulting from the way scientific contents are presented in the classroom and in textbooks that could explain the students difficulties. At last, the work presents pedagogically relevant contributions that may be helpful in teaching thermodynamics in secondary schools with special activities that touch points that are conflicting between students conceptions and scientific knowledge.

Memoria (licenciado en ciencias jurídicas y sociales) / La presente memoria de investigación aborda la reparación del daño ambiental irreversible mediante una interpretación extensiva de la reparación como objeto de la acción ambiental contemplada en el inciso primero del artículo 53 de la Ley Nº 19.300. Al respecto, se sostiene que ante la imposibilidad de reparar in natura el daño ambiental ocasionado, y bajo la premisa de que no resulta posible reconocer normativamente en Chile un ámbito de irrestricta irresponsabilidad, resulta procedente, por analogía, la aplicación de medidas de compensación ambiental como forma de reparación en equivalencia frente a esta categoría de daños no previstas por el legislador. Se plantea que la solución acá ofrecida, además de resultar idónea en atención al bien jurídico tutelado por la acción ambiental, resulta coincidente con los principios que inspiran el sistema de responsabilidad civil por daño ambiental en Chile, en tanto concretiza la idea básica sobre la cual se articula cualquier sistema de responsabilidad: que quien resulte responsable de la ocasión de un daño ambiental se encuentre obligado a su reparación. Palabras

This masteral thesis describes phenomenon of electroporation and it’s use to deal with occluded self-expandable metalic stent. Thesis briefly summarizes theory of electroporation, currently used medical treatments of occluded stents. The next part of the thesis is dedicated to current state of mathematical simulations of electroporation. The core of the thesis are simulations of electroporation effects on tissue of occluded metal stents.

Cette thèse porte sur les conséquences de l’aversion à l’ambiguïté dans des contextes dynamiques en économie. En particulier, elle s’intéresse aux conséquences de l’aversion à l’ambiguïté dans les décisions d’investissement irréversibles, ainsi que dans un problème d’aléa moral dynamique, modélisé en temps continu. Le premier chapitre propose une revue de la littérature traitant de l’aversion à l’ambiguïté en contexte dynamique. Nous y passons en revue les modèles existants ainsi que leurs applications en économie et en finance. Le second chapitre s’intéresse aux décisions d’investissement irréversible d’un monopole et de firmes en compétition parfaite, en présence d’ambiguïté à propos de la volatilité du processus stochastique gouvernant la demande. Cette notion particulière d’ambiguïté nécessite de mobiliser les outils récents de la théorie des espérances non linéaires. On y montre qu’en présence d’aversion à l’ambiguïté, la stratégie optimale d’un monopole implique d’investir plus rapidement que dans un marché en concurrence parfaite. Le troisième chapitre s’appuie sur les résultats du second chapitre pour traiter le cas d’une concurrence imparfaite entre deux firmes. Le quatrième chapitre traite d’un problème d’aléa moral dynamique en temps continu et on y introduit la notion plus classique d’ambiguïté à propos de la dérive du processus gouvernant l’incertitude. On y montre que sous certaines restrictions semblables au cas standard, le contrat optimal est linéaire par rapport à la production finale. Ce résultat nous permet ensuite de discuter l’effet de l’aversion à l’ambiguïté sur les incitations et l’utilisation de l’information. / This thesis focuses on the consequences of ambiguity aversion in dynamic contexts in economics. In particular, we focus on the consequences of ambiguity aversion in irreversible investment problems, and in dynamic moral hazard problems in continuous-time. The first chapter reviews the literature on ambiguity in dynamic contexts, and reviews existing models as well as their applications in economics and finance. The second chapter deals with irreversible investment in the monopoly case and under perfect competition, under ambiguous volatility. The notion of ambiguous volatility requires the use of recent tools in non linear expectation theory. We show that the optimal entry strategy of a monopoly under ambiguous volatility implies investing sooner than the perfectly competitive equilibrium under volatility ambiguity. The third chapter builds on the results of the second chapter and treats a special case of imperfect competition. The last chapter deals with a dynamic principal-agent problem under moral in continuous-time, in which agents perceive ambiguity about the drift of the relevant process. We show that under certain conditions, the optimal contract is linear in final output. We then use this result to discuss the effect of ambiguity aversion on the incentive power of the optimal contract and the informativeness principle.

The hypothesis that irreversible ischemic injury is related to sub-sarcolemmal blebbing and an inherent osmotic fragility of the blebs was tested by subjecting isolated control and ischemically preconditioned (IPC) or calyculin A (CalA)-pretreated (protected) rabbit cardiomyocytes to ischemic pelleting followed by resuspension in 340, 170 or 85 mosmol medium containing trypan blue. At time points from 0-240 min, osmotic fragility was assessed by the percentage of trypan blue permeable cells. Membrane blebs were visualized with India ink preparations. Bleb formation, following acute hypo-osmotic swelling, developed by 75 min and increased with longer periods of ischemia. Osmotic fragility developed only after 75 min. Cells resuspended in 340 mosmol media did not form blebs and largely retained the ability to exclude trypan blue, even after 240 min ischemia. Although the latent tendency for osmotic blebbing preceded the development of osmotic fragility, most osmotically fragile cells became permeable without evident sarcolemmal bleb formation. The onset of osmotic fragility was delayed in protected cells, but protection did not reduce the bleb formation. It is concluded that blebbing and osmotic fragility are independent manifestations of ischemic injury. The principal locus of irreversible ischemic injury and the protection provided by IPC may lie within the sarcolemma rather than at sarcolemmal attachments to underlying adherens junctions.

The question whether and how closed quantum systems equilibrate is still debated today. In this thesis a generic spin system is analysed and criteria to classify unique equilibration dynamics are developed. Furthermore, the eigenstate thermalization hypothesis is investigated as a possible cause for the unique equilibrium. For both problems novel numerical methods for solving the time-dependent Schroedinger equation based on series expansions and typicality are developed. Furthermore, the problem of markovian dynamics on the level of single measurements is discussed.

The movements of salt and water, particularly in fairly dry soils or compacted shales, are important processes in both agronomic studies and hydraulics of deep ground water which is important in the location of oil.

No description available.

The design of probes for the selective recognition of biopolymers (nucleic acids and proteins) is a fundamental task for studying, diagnosing, and treating diseases. Traditional methods utilize a single component (small molecule or oligonucleotide) that binds directly to the target biopolymer. However, many biopolymers are unable to be targeted with this approach. The overarching goal of this dissertation is to explore a new, binary approach for designing probes. The binary approach requires two components that cooperatively bind to the target, triggering a recognition event. The requisite binding of two-components allows the probes to have excellent selectivity and modularity. The binary approach was applied to design a new sensor, called operating cooperatively (OC) sensor, for recognition of nucleic acids, including selectively differentiating between single nucleotide polymorphisms (SNPs). An OC sensor contains two oligonucleotide probe strands, called O and C, each with two domains. The first domain contains a target recognition sequence, whereas the second domain is complementary to a molecular beacon (MB) probe. Binding of both probe strands to the fully matched analyte generates a full MB probe recognition site, allowing a MB to bind and report the presence of the target analyte. Importantly, we show that the OC sensor selectively discriminates between single nucleotide polymorphisms (SNPs) in DNA and RNA targets at room temperature, including those with stable secondary structures. Furthermore, the combinatorial use of OC sensors to create a DNA logic gate capable of analyzing DNA sequences of Mycobacterium tuberculosis is described. The binary approach was also applied to design covalent inhibitors for HIV-1 reverse transcriptase (RT). In this application, two separate pre-reactive groups were attached to a natural RT ligand, deoxythymidine triphosphate (dTTP). Upon binding of both dTTP analogs in the RT active site, the pre-reactive groups are brought into the proper proximity and react with each other forming an intermediate that subsequently reacts with an amino acid side chain from the RT. This leads to covalent modification of RT, and inhibition of its DNA polymerase activity. This concept was tested in vitro using dTTP analogs containing pre-reactive groups derived from ?-lactamase inhibitors clavulanic acid (CA) and sulbactam (SB). Importantly, our in vitro assays show that CA based inhibitors are more potent than zidovudine (AZT), a representative of the dominant class of RT inhibitors currently used in anti-HIV therapy. Furthermore, molecular dynamics simulations predict that complexes of RT with these analogs are stable, and point to possible reaction mechanisms. The inhibitors described in this work may serve as the basis for the development of the first covalent inhibitors for RT. Moreover, the pre-reactive groups used in this study can be used to design covalent inhibitors for other targets by attaching them to different ligands. Overall, the work presented herein establishes the binary approach as a straightforward way to develop new probes to selectively recognize nucleic acids and proteins.