Les spectroscopies vibrationnelles infrarouge et Raman sont de formidables techniques d’analyse pour la caractérisation d’échantillons complexes. Elles permettent effectivement d’accéder à une grande richesse d’information moléculaire. Au-delà des caractérisations macroscopiques de ces techniques, le couplage des spectromètres à des microscopes rend possible la génération de cartographies représentant les distributions spatiales des espèces chimiques de l’échantillon analysé. Malgré ce fort potentiel, ces spectroscopies sont mal adaptées à l’imagerie d’échantillons de taille micrométrique et submicrométrique. Leurs résolutions spatiales en partie fixées par la limite de diffraction sont effectivement restreintes. L’augmentation de la résolution spatiale est donc toujours un enjeu majeur pour permettre une meilleure caractérisation des échantillons analysés. Deux approches se sont dégagées pour améliorer cette limite. La première solution est centrée sur le développement instrumental comme par exemple la spectroscopie champ proche. La seconde approche algorithmique tente de repousser les limites de résolution de système optique par le traitement mathématique et statistique des images générées sur des spectromètres classiques en champ lointain. C’est dans ce cadre que s’inscrit notre recherche. Nous présenterons ainsi dans ce travail le développement et l’optimisation d’un nouveau concept dit de « super-résolution » adapté aux imageries des spectroscopies moyen infrarouge, proche infrarouge et Raman. Différents échantillons d’origines pharmaceutiques, biologiques ou environnementales seront alors exploités. / Vibrational spectroscopic imaging (infrared and Raman) is a powerful technique for visualizing the distribution of chemical compounds of complex samples. Due to the very high content of information contained in their spectrum, vibrational spectroscopies have taken more and more importance in molecular imaging. With such far-field imaging spectroscopy, the resolution limit is first and foremost dictated by the photon wavelength due to diffraction limit. This becomes a real constraint when micron-sized or submicron-sized samples are analyzed because no more details are present in generated images. Thus increasing the spatial resolution is still a major challenge for a better characterization of the analyzed samples. Two approaches have emerged to go beyond this limit. The first approach focuses on the instrumental development such as the near-field spectroscopy. The second approach is an algorithmic one. It attempts to push the limits of resolution of optical system by the mathematical analysis of images generated on conventional far-field spectrometers. The aim of the presented work is to develop and optimize of a new concept called "super-resolution" in imaging for mid-infrared, near infrared and Raman spectroscopy in order to increase the spatial resolution. Different samples forms of pharmaceutical, biological or environmental origins will be exploited.

In large, open and distributed systems, agents are often used to represent users and act on their behalves. Agents can provide good or bad services or act honestly or dishonestly. Trust and reputation mechanisms are used to distinguish good services from bad ones or honest agents from dishonest ones. My research is focused on trust and reputation management in decentralized systems. Compared with centralized systems, decentralized systems are more difficult and inefficient for agents to find and collect information to build trust and reputation. In this thesis, I propose a Bayesian network-based trust model. It provides a flexible way to present differentiated trust and combine different aspects of trust that can meet agents different needs. As a complementary element, I propose a super-agent based approach that facilitates reputation management in decentralized networks. The idea of allowing super-agents to form interest-based communities further enables flexible reputation management among groups of agents. A reward mechanism creates incentives for super-agents to contribute their resources and to be honest. As a single package, my work is able to promote effective, efficient and flexible trust and reputation management in decentralized systems.

In large, open and distributed systems, agents are often used to represent users and act on their behalves. Agents can provide good or bad services or act honestly or dishonestly. Trust and reputation mechanisms are used to distinguish good services from bad ones or honest agents from dishonest ones. My research is focused on trust and reputation management in decentralized systems. Compared with centralized systems, decentralized systems are more difficult and inefficient for agents to find and collect information to build trust and reputation. In this thesis, I propose a Bayesian network-based trust model. It provides a flexible way to present differentiated trust and combine different aspects of trust that can meet agents different needs. As a complementary element, I propose a super-agent based approach that facilitates reputation management in decentralized networks. The idea of allowing super-agents to form interest-based communities further enables flexible reputation management among groups of agents. A reward mechanism creates incentives for super-agents to contribute their resources and to be honest. As a single package, my work is able to promote effective, efficient and flexible trust and reputation management in decentralized systems.

Surface plasmons¡]SPs¡^have been extensive applied to various kinds of detector and devices. There are very great relations of physical quantity, such as resonant angle, damping rate, halfwidth of resonance and reflection rate, etc. of resonating in the exciting of SPs. In this study, we derived some approximate formulas of these physical quantities from fresnel¡¦s formulas and pole approximate expansion, such as, the damping rate of SPs, the resonant angle, the optimum metallic thickness of these structure. In addition, we have also proceeding to some numerical simulations. Surface plasmons can also apply to near-field optics, using the super-resolution near-field structure¡]Super-RENS¡^ , the data densities can be promoted, and the diffraction limit can be overcome. SPs are excited at the Sb/SiN interface may concentrate light spot and enhance the field intensity. In this study, we have also expounded the fact that its antimony film in a Super-RENS of propagation, function and simulation of the SPs. As a result of calculations and simulations, we conclude that the enhanced filed intensity is larger for a system using a metal with a smaller imaginary part of the dielectric constant. The resonant angle decreases when the dielectric constant of the prism increases and the dielectric constant of the intermediate layer decreases. In addition, the optimum resonant condition in Super-RENS can be made by proper selection of parameters.

We intend to study the properties of two dimensional electron-hole systems in superlattice of ¢»-¢½ semiconductors at ultra-low temperature and high magnetic field by SdH measurement and QHE measurement and to explore the electron¡¦s oscillation varied with the external magnetic field. Considering the sample 2749,the electron densities of the first subband is 2.42¡Ñ1010cm-2,respectively,of which is 2.42¡Ñ1010cm-2 after low temperature¡¦s illumination. Considering the sample 2758,the electron densities of the first subband is 1.236¡Ñ1010cm-2,respectively,of which is 1.236¡Ñ1010cm-2 after low temperature¡¦s illumination. Data are the same, which may be concerned with the quality of the sample.

archives@tulane.edu / 1 / ZHU ZHANG

Alors que la microscopie super-résolue a apporté une amélioration considérable en imagerie des assemblages moléculaires dans les milieux biologiques à l'échelle nanométrique, son extension à l'imagerie de l'orientation moléculaire, utilisant l'anisotropie de fluorescence, n'a pas encore été complètement explorée. Apporter une information sur l'orientation moléculaire à l'échelle nanométrique aurait un intérêt considérable pour la compréhension des fonctions biologiques. Dans cette thèse, nous proposons une technique de microscopie super-résolution résolue en polarisation, capable d'imager les comportements d'orientation moléculaire dans des environnements statiques et dynamiques, dans le but de rapporter une information structurale à l'échelle de la molécule unique et à des échelles spatiales nanométriques. En utilisant la microscopie par reconstruction stochastique (dSTORM) en combinaison avec une détection polarisée, des images d'anisotropie de fluorescence sont reconstruites avec une résolution spatiale de quelques dizaines de nanomètres. Nous analysons numériquement le principe de la méthode en combinaison avec des modèles des mécanismes d'orientation moléculaire. Enfin, nous proposons une technique alternative basée sur l'émission de molécules uniques en fluctuations stochastiques: l'imagerie super-résolue polarisée par fluctuations (polar-SOFI), et comparons cette approche avec la précédente. Nous illustrons les deux techniques pour l'imagerie de l'ordre moléculaire dans des fibres de stress d'actine et de tubuline dans des cellules fixées, des fibres d'ADN et des fibrilles d'amyloïde à base d'insuline. / While super-resolution microscopy has brought a significant improvement in nanoscale imaging of molecular assemblies in biological media, its extension to imaging molecular orientation using fluorescence anisotropy has not yet been fully explored. Providing orientational order information at the nanoscale would be of considerable interest for the understanding of biological functions since they are intrinsically related to structural fundamental processes such as in protein clustering in cell membranes, supra-molecular polymerization or aggregation. In this thesis, we propose a super-resolution polarization-resolved microscopy technique able to image molecular orientation behaviors in static and dynamic environments, in order to report structural information at the single molecule level and at nanometric spatial scale. Using direct Stochastic Optical Reconstruction Microscopy (dSTORM) in combination with polarized detection, fluorescence anisotropy images are reconstructed at a spatial resolution of a few tens of nanometers. We analyze numerically the principle of the method in combination with models for orientational order mechanisms, and provide conditions for which this information can be retrieved with high precision in biological samples based on fibrillar structures. Finally, we propose an alternative technique based on stochastic fluctuations of single molecules: polarized super-resolution optical fluctuation imaging (polar-SOFI), and compare this approach with the previous one. We illustrate both techniques on molecular order imaging in actin stress fibers and tubulin fibers in fixed cells, DNA fibers and insulin amyloid fibrils.

La photométrie des transits permet de détecter des planètes extrasolaires en mesurant leur rayon. Dans cet objectif, le télescope spatial CoRoT (Convection, Rotation et Transit planétaires), lancé en décembre 2006, est doté d'un photomètre de haute précision permettant à la fois l'étude de la structure interne des étoiles par astérosismologie et la détection de planètes par la méthode des transits. Pour cette thèse, j'ai développé différents outils informatiques permettant la détection, l'analyse détaillée de transits dans les courbes de lumière de CoRoT. J'ai appliqué ces outils aux quelques 12 000 étoiles observées durant chacune des dix premières campagnes d'observation. La collaboration des équipes de détection et de suivi au sol par d'autres méthodes d'observation a permis, à ce jour, la découverte de quinze planètes et deux naines brunes.Il est possible de contraindre les modèles de ces exoplanètes grâce à la connaissance des paramètres (masse, rayon): gazeuses, de glace, telluriques, ou d'autres types mixtes.La recherche de planètes rocheuses en particulier est un objectif motivé tant par la rareté des détections de ces objets jusqu'à présent (liée à leur faibles rayon et masse), que par la grande variété potentielle de leur nature.Ainsi, la découverte de CoRoT-7b, la première exoplanète compatible avec un modèle rocheux et dont le rayon (1,6 rayon terrestre) et la masse (environ 7 masses terrestres) ont pu être mesurés, a permis d'élaborer un modèle physique auquel j'ai contribué.J'ai étudié la possibilité d'observer cette planète très chaude en proche infrarouge avec le JWST, au cours de son orbite, afin d'estimer le contraste de température entre les faces jour et nuit. Ceci doit permettre de confirmer / invalider notre modèle qui suppose l'absence d'une atmosphère suffisamment dense pour redistribuer la chaleur à la surface de CoRoT-7b. / The transit photometry makes it possible to detect exoplanets by measuring their radii. Pursuing this goal, the space telescope CoRoT (Convection, Rotation and planetary Transits), launched in December 2006, is equiped with a high-precision photometer allowing both planet detection by transit photometry, and stellar physics studies (asteroseismology).For this PhD thesis, I have developed various computing tools for the detection and detailed analysis of the transits in CoRoT light curves. I have applied these tools to almost 12 000 stars observed during each of the first ten campaigns of observation. The collaboration between the detection and ground based follow-up teams led to the discovery, up to now, of fifteen planets and two brown dwarfs.It is possible to constrain the physical natures of these exoplanets thanks to the knowledge of the masses and radii: they can be gazeous, icy, rocky or with an mixed nature.The search for rocky planets in particular, is a goal motivated by their singular nature, and both by the paucity of detections of these objects (due to their low masses and radii), Thus, the discovery of CoRoT-7b -- the first exoplanet compatible with a rocky model and whith measured radius (1.6 Earth radius) and mass (around 7 Earth masses) -- allowed us to develope a physical model to which I contributed :I studied the possibility of observing this very hot planet in the near infrared range with JWST, during its orbit, to estimate the temperature contrast between the day and the night faces. This should allow to confirm / invalidate our model with atmosphere dense enough to redistribute heat at the surface of CoRoT-7b.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Uma liga metÃlica que vem apresentando um desempenho satisfatÃrio em ambientes de maior agressividade à o aÃo inoxidÃvel super duplex. Esse tipo de aÃo possui boas propriedades de resistÃncia mecÃnica, resistÃncia à corrosÃo e tenacidade ao impacto. Mesmo apresentando desempenho satisfatÃrio, esses aÃos podem apresentar problemas de corrosÃo quando sofrem algum tratamento tÃrmico devido à precipitaÃÃo de uma fase deletÃria chamada de alfa linha (â), a qual precipita em temperaturas entre 300 ⁰C e 550 ⁰C e pode ocasionar uma diminuiÃÃo da resistÃncia à corrosÃo e tenacidade do material. Portanto, o objetivo deste trabalho à avaliar a resistÃncia à corrosÃo dos aÃos inoxidÃveis super duplex fundidos de grau 5A e 6A apÃs sofrerem tratamento tÃrmico a 475 ⁰C. O grau 6A se difere do 5A pela presenÃa de cobre e tungstÃnio na sua composiÃÃo quÃmica. A resistÃncia à corrosÃo dos corpos de prova foi avaliada por meio das seguintes tÃcnicas eletroquÃmicas: monitoramento do potencial de circuito aberto, polarizaÃÃo anÃdica, polarizaÃÃo cÃclica, espectroscopia de impedÃncia eletroquÃmica e temperatura crÃtica de pite. Foi realizada a caraterizaÃÃo microestrutural dos materiais, onde foi possÃvel observar sua estrutura bifÃsica composta por uma matriz ferrÃtica e ilhas de austenita em proporÃÃes coerentes. O ensaio de dureza Brinell mostrou que a dureza aumenta nas primeiras horas de tratamento tÃrmico e, depois, hà uma diminuiÃÃo nessa taxa de aumento da dureza. Os resultados eletroquÃmicos indicaram que, para os dois tipos de aÃo estudados, as amostras com 10 horas de tratamento tÃrmico apresentaram uma maior resistÃncia à corrosÃo.