<p>Molecular recognition is arguably the most elementary physical process essential for life that arises at the molecular scale. Molecular recognition drives events across virtually all length scales, from the folding of proteins and binding of ligands, to the organization of membranes and the function of muscles. Understanding such events at the molecular level is massively complicated by the unique medium in which life occurs: water. In contrast to recognition in non-aqueous solvents, which are driven largely by attractive interactions between binding partners, binding reactions in water are driven in large measure by the properties of the medium itself. Aqueous binding involves the loss of solute-solvent interactions (desolvation) and the concomitant formation of solute-solute interactions. Despite decades of research, aqueous binding remains poorly understood, a deficit that profoundly limits our ability to design effective pharmaceuticals and new enzymes. Particularly problematic is understanding the energetic consequences of aqueous desolvation, an area the Toone and Beratan groups have considered for many years.</p><p> In this dissertation, we embark on a quest to shed new light on aqueous desolvation from two perspectives. In one component of this research, we improve current computational tools to study aqueous desolvation, employing quantum mechanics (QM), molecular dynamics (MD) and Monte Carlo (MC) simulations to better understand the behavior of water near molecular surfaces. In the other, we use a synthetic host, cucurbit[7]uril (CB[7]), in conjunction with a de novo series of ligands to study the structure and thermodynamics of aqueous desolvation in the context of ligand binding with atomic precision, a feat hitherto impossible. A simple and rigid macrocycle, CB[7] alleviates the drawbacks of protein systems for the study of aqueous ligand binding, that arise from conformational heterogeneity and prohibitive computational costs to model.</p><p> </p><p> We first constructed a novel host-guest system that facilitates internalization of the trimethylammonium (methonium) group from bulk water to the hydrophobic cavity of CB[7] with precise (atomic-scale) control over the position of the ligand with respect to the cavity. The process of internalization was investigated energetically using isothermal titration microcalorimetry and structurally by nuclear magnetic resonance (NMR) spectroscopy. We show that the transfer of methonium from bulk water to the CB[7] cavity is accompanied by an unfavorable desolvation enthalpy of just 0.49±0.27 kcal*mol-1, a value significantly less endothermic than those values suggested from previous gas-phase model studies. Our results offer a rationale for the wide distribution of methonium in biology and demonstrate important limitations to computational estimates of binding affinities based on simple solvent-accessible surface area approaches.</p><p> To better understand our experimental results, we developed a two-dimensional lattice model of water based on random cluster structures that successfully reproduces the temperature-density anomaly of water with minimum computational cost. Using reported well-characterized ligands of CB[7], we probed water structure within the CB[7] cavity and identified an energetically perturbed cluster of water. We offer both experimental and computational evidence that this unstable water cluster provides a significant portion of the driving force for encapsulation of hydrophobic guests.</p><p> The studies reported herein shed important light on the thermodynamic and structural nature of aqueous desolvation, and bring our previous understanding of the hydrophobic effect based on ordered water and buried surface area into question. Our approach provides new tools to quantify the thermodynamics of functional group desolvation in the context of ligand binding, which will be of tremendous value for future research on ligand/drug design.</p> / Dissertation

Ce mémoire est une partie d’un programme de recherche qui étudie la superintégrabilité des systèmes avec spin. Plus particulièrement, nous nous intéressons à un hamiltonien avec interaction spin-orbite en trois dimensions admettant une intégrale du mouvement qui est un polynôme matriciel d’ordre deux dans l’impulsion. Puisque nous considérons un hamiltonien invariant sous rotation et sous parité, nous classifions les intégrales du mouvement selon des multiplets irréductibles de O(3). Nous calculons le commutateur entre l’hamiltonien et un opérateur général d’ordre deux dans l’impulsion scalaire, pseudoscalaire, vecteur et pseudovecteur. Nous donnons la classification complète des systèmes admettant des intégrales du mouvement scalaire et vectorielle. Nous trouvons une condition nécessaire à remplir pour le potentiel sous forme d’une équation différentielle pour les cas pseudo-scalaire et pseudo-vectoriel. Nous utilisons la réduction par symétrie pour obtenir des solutions particulières de ces équations. / This thesis is part of a research program studying superintegrable systems with spin. In particular, we consider a Hamiltonian with a spin-orbital interaction in three dimensions admitting an integral of motion that is a matrix polynomial second order in the momenta. Since we are considering a Hamiltonian which is invariant under rotation and parity, we classify the integrals of motion into irreducible O(3) multiplets. We obtain the commutator of the Hamiltonian with the scalar, pseudoscalar, vector and axial vector operators. We provide a complete classification for the scalar and vector cases. We find the necessary condition for superintegrability on the potential as a differential equation. We use symmetry reduction methods to obtain particular solutions of this equation.

Les applications reliées à la génération d'énergie motivent la recherche de matériaux ayant un fort pouvoir thermoélectrique (S). De plus, S nous renseigne sur certaines propriétés fondamentales des matériaux, comme, par exemple, la transition entre l'état cohérent et incohérent des quasi-particules lorsque la température augmente. Empiriquement, la présence de fortes interactions électron-électron peut mener à un pouvoir thermoélectrique géant. Nous avons donc étudié le modèle le plus simple qui tient compte de ces fortes interactions, le modèle de Hubbard. La théorie du champ moyen dynamique (DMFT) est tout indiquée dans ce cas. Nous nous sommes concentrés sur un système tridimensionnel (3d) cubique à face centrée (fcc), et ce, pour plusieurs raisons. A) Ce type de cristal est très commun dans la nature. B) La DMFT donne de très bons résultats en 3d et donc ce choix sert aussi de preuve de principe de la méthode. C) Finalement, à cause de la frustration électronique intrinsèque au fcc, celui-ci ne présente pas de symétrie particule-trou, ce qui est très favorable à l'apparition d'une grande valeur de S. Ce travail démontre que lorsque le matériau est un isolant à demi-remplissage à cause des fortes interactions (isolant de Mott), il est possible d'obtenir de grands pouvoirs thermoélectriques en le dopant légèrement. C'est un résultat pratique important. Du point de vue méthodologique, nous avons montré comment la limite de fréquence infinie de S et l'approche dite de Kelvin, qui considère la limite de fréquence nulle avant la limite thermodynamique pour S, donnent des estimations fiables de la vraie limite continue (DC) dans les domaines de température appropriée. Ces deux approches facilitent grandement les calculs en court-circuitant la nécessité de recourir à de problématiques prolongements analytiques. Nous avons trouvé que la méthode de calcul à fréquence infinie fonctionne bien lorsque les échelles d'énergie sont relativement faibles. En d'autres termes, cette approche donne une bonne représentation de S lorsque le système devient cohérent. Les calculs montrent aussi que la formule Kelvin est précise lorsque la fonction spectrale des électrons devient incohérente, soit à plus haute température. Dans la limite Kelvin, S est essentiellement l'entropie par particule, tel que proposé il y a longtemps. Nos résultats démontrent ainsi que la vision purement entropique de S est la bonne dans le régime incohérent, alors que dans le régime cohérent, l'approche à fréquence infinie est meilleure. Nous avons utilisé une méthode à la fine pointe, soit le Monte-Carlo quantique en temps continu pour résoudre la DMFT. Pour permettre une exploration rapide du diagramme de phase, nous avons dû développer une nouvelle version de la méthode des perturbations itérées pour qu'elle soit applicable aussi à forte interaction au-delà de la valeur critique de la transition de Mott. Un autre sujet a aussi été abordé. L'effet orbital du champ magnétique dans les systèmes électroniques fortement corrélés est une question très importante et peu développée. Cela est d'autant plus essentiel depuis la découverte des oscillations quantiques dans les supraconducteurs à haute temperature (haut-T[indice inférieur c]). Par désir de développer une méthode la moins biaisée possible, nous avons dérivé la DMFT lorsqu'un champ se couplant à l'opérateur énergie cinétique par la substitution de Peierls est présent. Ce type d'approche est nécessaire pour comprendre entre autres l'effet de la physique de Mott sur des phénomènes tels que les oscillations quantiques. Nous avons obtenu un résultat très important en démontrant rigoureusement que la relation d'auto-cohérence de la DMFT et le système intermédiaire d'impureté quantique restent les mêmes. L'effet du champ peut être contenu dans la fonction de Green locale, ce qui constitue la grande différence avec le cas habituel. Ceci permet de continuer à utiliser les solutionneurs d'impuretés standards, qui sont de plus en plus puissants. Nous avons aussi développé la méthode pour le cas d'un empilement de plans bidimensionnels selon z, ce qui permet d'étudier l'effet orbital du champ dans des nanostructures et même dans les matériaux massifs, si le nombre de plans est suffisant pour obtenir la limite tridimensionnelle.

The goal of this paper is to offer new insights into the climate change debate by shifting away from the heated anthropologic arguments that dominate politics, media, and popular science. Instead, I choose to rely on the long-term impacts of a changing climate on our planet. The paper begins with a break down of key processes involved in short-term and long-term climate change, using the latest research. After a foundational understanding of climate sciences is established, we will discuss the failure of the climate change debate in educating the general public about the facts of a changing climate. Finally, the importance of long-term foresight in climate policy and education, and how this perspective could drastically progress the climate debate, will be discussed.

Made available in DSpace on 2014-06-11T19:23:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T19:50:22Z : No. of bitstreams: 1 medeiros_ng_me_prud.pdf: 4732444 bytes, checksum: 68ffda87b04d5da40a3c9af553db0a4a (MD5) / A segmentação de imagens é um processo muito utilizado e relevante em diversas áreas do conhecimento. Neste trabalho tem-se um exemplo na área de cartografia. O processo de extração de feições não é uma tarefa fácil e necessita do uso de técnicas mais complexas e de dados com boa qualidade para o sucesso dos resultados. Assim, este trabalho teve por objetivo reunir técnicas de Processamento Digital de Imagens (PDI), em especial a Morfologia Matemática, em conjunto com imagens de Sensoriamento Remoto, na utilização específica da segmentação de imagens, visando a obtenção de resultados relevantes à área de cartografia. Visto que os operadores morfológicos utilizam como padrão de reconhecimento apenas os valores de brilho, a idéia foi realizar um tratamento de realce que melhorasse a qualidade das feições de interesse para serem extraídas no processo de segmentação. A melhora da qualidade dessas imagens pode contribuir para a obtenção de resultados mais significativos. Para isto, foram utilizados alguns dos operadores morfológicos contidos na toolbox de morfologia matemática acoplada ao software MATLAB, voltados a etapa de préprocessamento de imagens originais (“brutas”) e a implementação de duas abordagens utilizadas para a geração da imagem de marcadores. A imagem original e/ou tratada e a imagem de marcadores são usadas como parâmetros de entrada no processo de segmentação com o operador watershed. Os operadores implementados foram o gradiente morfológico multi-escala e o mínimos impostos. As imagens utilizadas são imagens orbitais do satélite Landsat, dos sensores TM e ETM+, disponíveis no banco de imagens da FCT - Unesp. Após a realização dos testes foi verificado o desempenho dos operadores implementados e realizada a análise dos resultados... / Image segmentation is a process often used in several different areas including Cartography. Feature extraction is a very troublesome task, and successful results require more complex techniques and good quality data. The aim of this work is to study Digital Image Processing techniques, with emphasis in Mathematical Morphology, using Remote Sensing imagery. These techniques were used to segment images aiming significant cartographic applications. Considering that morphological operators use grays levels as the major recognition pattern, the proposal of this research is to apply previously an enhancement technique aiming the improvement of the interest features to be extracted in the segmentation process. More meaningful results can be attained with this previous image enhancement step. In order to test the proposed approach some morphological operators related to early processing were applied in unprocessed images using an existing MatLab Toolbox. Furthermore, two distinct techniques generating marker images were implemented in the MatLab environment. The raw and the enhanced images, and the marker image were used as input parameters in the segmentation process with the Watershed operator. The implemented operators were the morphological multi-scale gradient and minima imposed. Orbital images of the Landsat satellite, sensors TM and ETM+ , available in the image database of FCT-UNESP were used. The performance of the implemented operators and the results were analised after some tests with the existing images. Extraction of linear features, such as highways, airports, etc., can contribute in cartographic applications as the feature identification or cartographic updating, considering that orbital images contain more recent information and the changes can be emphasized and extracted. The proposed objectives were reached with contributions to the segmentation processes using Watersheds.

Dans cette thèse, on étudie la stabilité orbitale d’états stationnaires de modèles mathématiques de type "Hamiltonian mean-field", dits modèles HMF. Cette étude est d’abord menée d’un point de vue théorique en utilisant des méthodes variationnelles. Puis, elle est menée d’un point de vue numérique en commençant par l’élaboration de schémas conservant exactement des états stationnaires. Le Chapitre 2 présente une étude théorique de la stabilité orbitale des états stationnaires du modèle HMF Poisson. Plus précisément, on prouve la stabilité orbitale d’une grande classe d’états stationnaires solutions du système HMF avec potentiel de Poisson. Ces états stationnaires sont des minimiseurs d’un problème à une, deux ou une infinité de contraintes d’une certaine fonctionnelle. La preuve s’appuie sur une approche variationnelle. Cependant le caractère borné du domaine empêche l’utilisation des techniques usuelles basées sur des invariances d’échelles. On introduit alors de nouvelles méthodes, spécifiques à ce problème, mais demeurant dans l’esprit des outils de réarrangements introduits pour le système de Vlasov-Poisson. En particulier, ces méthodes permettent de considérer un nombre arbitraire de contraintes et aboutissent à un résultat de stabilité pour une grande classe d’états stationnaires. Dans le Chapitre 3, on construit des schémas numériques conservant exactement des états stationnaires donnés. Ces schémas modélisent mieux la propriété de stabilité orbitale que les schémas classiques. Puis, on propose un schéma plus général en construisant un schéma qui conserve tous les états stationnaires des modèles HMF. Pour finir, à l’aide de ces schémas, est menée une étude numérique de la stabilité des états stationnaires du système de HMF Poisson qui vient compléter l’étude théorique du Chapitre 2. / In this thesis, we study the nonlinear orbital stability of steady states of "Hamiltonian mean-field" models, called HMF models. First, this study is being done theoretically by using variational methods. It is then carried out numerically by building numerical schemes wich exactly preserve steady states. Chapter 2 presents a theoretical study of the orbital stability of steady states which are solutions to the HMF Poisson system. More specifically, the orbital stability of a large class of steady states which are solutions to the HMF system with Poisson potential is proved. These steady states are obtained as minimizers of an energy functional under one, two or infinitely many constraints. The proof relies on a variational approach. However the boundedness of the space domain prevents us from using usal technics based on scale invariance. Therefore, we introduce new methods which, although specific to our context, remain somehow in the same spirit of rearrangements tools introduced for the Vlasov-Poisson system. In particular, these methods allow for the incorporation of an arbitrary number of constraints, and yield a stability result for a large class of steady states. In Chapter 3, numerical schemes exactly preserving given steady states are built. These schemes model the orbital stability property better than the classic ones. Then, a more general scheme is introduced by building a scheme wich preserves all steady states of HMF models. Lastly, by means of these schemes, we conduct a numerical study of stability of steady states solutions to HMF Poisson system. This completes the theoretical study in Chapter 2.

Comprovada a importância do uso de imagens de satélite de alta resolução como ferramenta em muitas áreas, permitindo agilidade, qualidade e baixo custo aos usuários, torna-se importante também, o estudo da aplicação destas imagens no cadastro técnico rural multifinalitário, visto que a informação cadastral precisa e atualizada, obtida de forma rápida, com qualidade e relação custo-benefício atrativa, é um componente essencial ao processo de tomada de decisão por parte dos órgãos competentes. Além do cadastro ambiental, com a regulamentação da Lei 10.267/2001, que trata do georreferenciamento de imóveis rurais, o cadastro técnico rural geométrico vem merecendo atenção especial devido às grandes discussões e dúvidas geradas em torno deste tema. O objetivo deste trabalho, portanto, é investigar a aplicabilidade das imagens de alta resolução espacial do Sensor QuickBird II no cadastro técnico rural multifinalitário de uma área rural com relevo levemente ondulado e comparar as recomendações da Norma Técnica para Georreferenciamento de Imóveis Rurais do INCRA, principalmente no tocante às medições de limites naturais (drenagens), com os resultados obtidos através da imagem. Para tanto, utilizou-se uma imagem orbital do referido sensor nos modos pancromático e multiespectral, em seu estado bruto, isto é, sem nenhum tipo de tratamento. A partir da imagem bruta, realizou-se uma técnica de fusão, de forma a permitir trabalhar com uma imagem de alta resolução espectral e espacial ao mesmo tempo. A seguir realizou-se a correção geométrica planimétrica da imagem (registro) e o georreferenciamento, utilizando-se 19 pontos de controle medidos em campo com tecnologia GPS, seguindo da geração de um MDT através de curvas-denível de 10 em 10 metros da cartografia sistemática brasileira. De posse deste MDT, bem como do MDT da SRTM, com pixel de 90 metros, gerou-se duas orto-imagens por meio do processo de ortorretificação (correção geométrica altimétrica). A partir das orto-imagens, gerou-se os vetores correspondentes ao limite da Estação Experimental Agronômica da UFRGS, gleba Sul, área piloto de estudo. Após gerados os três vetores correspondentes, respectivamente, à carta topográfica de escala 1:25.000, à imagem ortorretificada através das curvas-de-nível e à imagem ortorretificada através do MDT da SRTM, comparou-se os resultados com o limite medido por técnicas de topografia convencional, o qual foi tomado como referência. Para atingir os objetivos do trabalho, avaliou-se separadamente os limites secos e o limite natural, respeitando suas particularidades. Após analisados os resultados, conclui-se que o melhor produto éoriundo da imagem ortorretificada pelo MDT da SRTM, com exatidão de 1,90 metros e recomenda-se a utilização deste, numa escala de referência máxima de 1:8.000, atendendo em grande parte as necessidades da administração de uma propriedade rural, bem como o planejamento e gerenciamento de um projeto florestal. Com relação à determinação de limites naturais (drenagens), conclui-se que a imagem orbital ortorretificada pelo MDT da SRTM é 3,5 vezes mais exata que a cartografia existente, recomendada pela Norma Técnica do INCRA. / Clear the importance of the use of satellite imagery of high resolution as a tool in many areas, allowing agility, quality and low cost to users, it is also important, the study of the application of these images in the multipurpose rural technical cadaster, since the information cadastral accurate and updated, obtained quickly, with quality and attractive cost-benefit, is a key component to the decision-making process by the competent agencies. Besides the environmental cadaster with the regulations of Law 10.267/2001, which is the georreferencing of rural property, the geometric rural technical cadaster comes deserving special attention because of the big discussions and doubts generated around this theme. The goal of this study, therefore, is to investigate the applicability of the images of high spatial resolution of the sensor QuickBird II in the multipurpose rural technical cadaster of an rural area with relief slightly wavy and compare the recommendations of the Technical Standard for georreferencing of rural property of the INCRA, mainly regarding measurements of natural limits (drainings), with the results gotten the image. For this, was used an image of the related orbital sensor in pancromatic and multispectral modes, in its raw state, that is, without any kind of treatment. From the raw image, there was a technique of merger, in order to work with an image of high spectral and spatial resolution at the same time. To follow it was become the planimetric geometric correction image (register) and the georreferencing, using 19 measured points of control in field with GPS technology, following the generation of a MDT through curves-of-level of 10 in 10 meters the Brazilian systematic mapping. Of ownership of this MDT, as well as of the MDT's SRTM with pixel of 90 meters, generated two ortho-images through the process of orthorrectification (altimetric geometric correction). From ortho-images, has been the corresponding vectors to the limit of the Experimental Station Agronomic of UFRGS, soil South, pilot area of study. After the three vectors generated corresponding, respectively, to the topographical map of scale 1:25.000, the image orthorrectificated through curves-of-level and image orthorrectificated through MDT's SRTM, compared themselves with the results measured by the limit conventional techniques of topography, which was taken as a reference. To reach the goals of the work, is evaluated separately the limit dried and the natural limit, respecting its particularities. After analyzed the results, concluded that the best product comes from the image orthorrectificated by MDT of the SRTM, with accuracy of 1.90 meters and it isrecommended to use this, on a scale of reference maximum of 1:8.000, given largely the needs of the administration of a rural property, as well as the planning and management of a forestry project. With regard to the determination of natural limits (drainingss), it is concluded that the orbital image orthorrectificated by MDTof the SRTM is 3,5 times more accurate that the existing mapping, recommended by the Norm of INCRA.

Comprovada a importância do uso de imagens de satélite de alta resolução como ferramenta em muitas áreas, permitindo agilidade, qualidade e baixo custo aos usuários, torna-se importante também, o estudo da aplicação destas imagens no cadastro técnico rural multifinalitário, visto que a informação cadastral precisa e atualizada, obtida de forma rápida, com qualidade e relação custo-benefício atrativa, é um componente essencial ao processo de tomada de decisão por parte dos órgãos competentes. Além do cadastro ambiental, com a regulamentação da Lei 10.267/2001, que trata do georreferenciamento de imóveis rurais, o cadastro técnico rural geométrico vem merecendo atenção especial devido às grandes discussões e dúvidas geradas em torno deste tema. O objetivo deste trabalho, portanto, é investigar a aplicabilidade das imagens de alta resolução espacial do Sensor QuickBird II no cadastro técnico rural multifinalitário de uma área rural com relevo levemente ondulado e comparar as recomendações da Norma Técnica para Georreferenciamento de Imóveis Rurais do INCRA, principalmente no tocante às medições de limites naturais (drenagens), com os resultados obtidos através da imagem. Para tanto, utilizou-se uma imagem orbital do referido sensor nos modos pancromático e multiespectral, em seu estado bruto, isto é, sem nenhum tipo de tratamento. A partir da imagem bruta, realizou-se uma técnica de fusão, de forma a permitir trabalhar com uma imagem de alta resolução espectral e espacial ao mesmo tempo. A seguir realizou-se a correção geométrica planimétrica da imagem (registro) e o georreferenciamento, utilizando-se 19 pontos de controle medidos em campo com tecnologia GPS, seguindo da geração de um MDT através de curvas-denível de 10 em 10 metros da cartografia sistemática brasileira. De posse deste MDT, bem como do MDT da SRTM, com pixel de 90 metros, gerou-se duas orto-imagens por meio do processo de ortorretificação (correção geométrica altimétrica). A partir das orto-imagens, gerou-se os vetores correspondentes ao limite da Estação Experimental Agronômica da UFRGS, gleba Sul, área piloto de estudo. Após gerados os três vetores correspondentes, respectivamente, à carta topográfica de escala 1:25.000, à imagem ortorretificada através das curvas-de-nível e à imagem ortorretificada através do MDT da SRTM, comparou-se os resultados com o limite medido por técnicas de topografia convencional, o qual foi tomado como referência. Para atingir os objetivos do trabalho, avaliou-se separadamente os limites secos e o limite natural, respeitando suas particularidades. Após analisados os resultados, conclui-se que o melhor produto éoriundo da imagem ortorretificada pelo MDT da SRTM, com exatidão de 1,90 metros e recomenda-se a utilização deste, numa escala de referência máxima de 1:8.000, atendendo em grande parte as necessidades da administração de uma propriedade rural, bem como o planejamento e gerenciamento de um projeto florestal. Com relação à determinação de limites naturais (drenagens), conclui-se que a imagem orbital ortorretificada pelo MDT da SRTM é 3,5 vezes mais exata que a cartografia existente, recomendada pela Norma Técnica do INCRA. / Clear the importance of the use of satellite imagery of high resolution as a tool in many areas, allowing agility, quality and low cost to users, it is also important, the study of the application of these images in the multipurpose rural technical cadaster, since the information cadastral accurate and updated, obtained quickly, with quality and attractive cost-benefit, is a key component to the decision-making process by the competent agencies. Besides the environmental cadaster with the regulations of Law 10.267/2001, which is the georreferencing of rural property, the geometric rural technical cadaster comes deserving special attention because of the big discussions and doubts generated around this theme. The goal of this study, therefore, is to investigate the applicability of the images of high spatial resolution of the sensor QuickBird II in the multipurpose rural technical cadaster of an rural area with relief slightly wavy and compare the recommendations of the Technical Standard for georreferencing of rural property of the INCRA, mainly regarding measurements of natural limits (drainings), with the results gotten the image. For this, was used an image of the related orbital sensor in pancromatic and multispectral modes, in its raw state, that is, without any kind of treatment. From the raw image, there was a technique of merger, in order to work with an image of high spectral and spatial resolution at the same time. To follow it was become the planimetric geometric correction image (register) and the georreferencing, using 19 measured points of control in field with GPS technology, following the generation of a MDT through curves-of-level of 10 in 10 meters the Brazilian systematic mapping. Of ownership of this MDT, as well as of the MDT's SRTM with pixel of 90 meters, generated two ortho-images through the process of orthorrectification (altimetric geometric correction). From ortho-images, has been the corresponding vectors to the limit of the Experimental Station Agronomic of UFRGS, soil South, pilot area of study. After the three vectors generated corresponding, respectively, to the topographical map of scale 1:25.000, the image orthorrectificated through curves-of-level and image orthorrectificated through MDT's SRTM, compared themselves with the results measured by the limit conventional techniques of topography, which was taken as a reference. To reach the goals of the work, is evaluated separately the limit dried and the natural limit, respecting its particularities. After analyzed the results, concluded that the best product comes from the image orthorrectificated by MDT of the SRTM, with accuracy of 1.90 meters and it isrecommended to use this, on a scale of reference maximum of 1:8.000, given largely the needs of the administration of a rural property, as well as the planning and management of a forestry project. With regard to the determination of natural limits (drainingss), it is concluded that the orbital image orthorrectificated by MDTof the SRTM is 3,5 times more accurate that the existing mapping, recommended by the Norm of INCRA.

La compétition des interactions est une caractéristique essentielle des systèmes frustrés, elle est à l'origine d'une large dégénérescence des états fondamentaux classiques ou, obtenus par une théorie de champ moyen.Fréquemment la dégénérescence peut être levée par des fluctuations thermiques ou quantiques, ce qui constitue la base du mécanisme appelé textit{ordre par le désordre}.Les systèmes magnétiques étudiés expérimentalement contiennent une quantité inévitable de désordre structural.Dans cette thèse de doctorat, l'influence des défauts, créé par des sites inoccupés ou par un désordre des liens sur l'espace dégénéré des états fondamentaux est étudiée pour des systèmes frustrés divers.Nous avons trouvé qu'un désordre structural est, lui aussi, capable de lever systématiquement la dégénérescence; par ailleurs, la tendance est inverse par rapport au le mécanisme d'ordre par le désordre produit par les fluctuations.Pour chacun des modèles considérés, les corrections à l'énergie ont été calculées sous la forme de termes anisotropes effectifs qui agissent sur l'espace dégénéré des états fondamentaux.Ces arguments analytiques ont été confirmés par des calculs numériques que nous avons effectués par minimisation de l'énergie, ainsi que par simulation de type Monte-Carlo classique. La séquence des états ordonnés que nous avons détectée est attribuée à la compétition entre l'effet d'ordre induit par les fluctuations et celui induit par les défauts structuraux. L'effet observé peut ouvrir des possibilités supplémentaires de contrôler la structure magnétique des systèmes.Enfin, les effets d'un champ magnétique externe ont été étudiés pour le système antiferromagnétique pyrochlore pur avec anisotropie de plan facile.Nous avons observé des transitions de phases qui dépendent de l'orientation du champ et qui n'existent pas dans la description de type champ moyen du système. Elles constituent une généralisation des transitions de type spin-flop pour le cas de la symétrie discrète $mathbb{Z}_k$ brisée avec $k > 2$. / Competing interactions is an essential feature of frustrated systems, they stand behind the large degeneracy of classical or mean-field ground states.%produce degeneracy of classical mean-field ground states.In many cases the degeneracy can be lifted by thermal and quantum fluctuations, such mechanism is commonly called textit{order from disorder}.Experimentally studied magnetic systems inevitably contain a finite amount of structural disorder.In this work the influence of defects, namely vacancies and bond disorder, on a degenerate ground state manifold is studied for various frustrated systems.We find that quenched disorder is also capable of consistently lifting the degeneracy, moreover, it has%in a wide range of frustrated systems.%Moreover, the effect of quenched disorder leads toan opposite tendency, compared to the order by disorder mechanism, produced by fluctuations.For every considered model, analytic energy corrections are derived in the form of effective anisotropic terms, which act on the manifold of degenerate ground states.Analytical arguments are confirmed by numerical calculations, which include energy minimization and classical Monte Carlo simulations.The detected sequences of ordered states is attributed to competition of fluctuations and structural disorder.The observed effect can open additional possibilities in tuning magnetic structure of the system.Finally, the effect of external magnetic field is investigated for the pure $XY$ pyrochlore antiferromagnet.Depending on the field orientation we observe phase transitions, which do not exist within the mean-field description of the system.They are generalizations of the spin-flop transition for the case of broken discrete $mathbb{Z}_k$ symmetry with $k > 2$.

Resumo: O planejamento ambiental em bacias hidrográficas exige um levantamento intenso de dados sobre a distribuição e comportamento das variáveis de análise selecionadas. Nesse trabalho, chama-se a atenção para a delimitação de unidades ambientais como resultado da integração de diferentes fatores ou elementos do meio físico, na busca de expressar a complexidade existente na unidade funcional da bacia hidrográfica. Desta forma o presente estudo teve como objetivo levantar as unidades homogêneas da bacia, com o auxilio do Sistema de Informação Geográfica. A bacia do Rio Capivara, localizada no município de Botucatu (SP), é um dos mais importantes afluentes da margem esquerda da bacia do Rio Tietê, situada entre as coordenadas planas 758000; 7486000 e 779645; 7456286, com uma área total de 22.218 ha. Utilizaram-se como materiais, as cartas planialtimétricas do IBGE, escala 1:50.000; fotografias aéreas da BASE, escala 1:30.000; imagens orbitais SPOT e Landsat de 1997 e CBERS de 2005; Sistema de Informação Geográfica ILWIS 3.2 for Windows; scaners; GPS; ploters e estereoscópio de espelho. Para a elaboração dos mapas temáticos foram agregados fatores do relevo tais como altitude e classes de declive que geram o mapa classes de altitude e declividade, somado ao mapa de unidades de solo (Piroli, 2002) gerou a primeira aproximação das unidades homogêneas da bacia, refinadas com as informações de uso do solo e vegetação natural. O mapa temático de unidades ambientais contém 11 unidades distintas, sendo elas: Frente da Cuesta de Botucatu, Fundo de vale do médio e baixo Capivara, Interflúvios ocidentais do médio e baixo Capivara, Interflúvios 2 orientais do médio e baixo Capivara, Topos conservados do alto Capivara, Topos do médio e baixo Capivara, Vertentes do Córrego Capivari, Vertentes do Ribeirão Duas Águas, Vertentes e fundos de vale... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hydrographic basins environment planning demands an intense amount of collecting data about the distribution and the behavior of the different variables that are selected for the analysis. In this work, we bring the attention to the delimitation of ambient units as a result of integration of different factors or elements of the physical medium, in order to express the complexity that exists in the functional unit of the hydrographic basin. This way, the present study had the objective to raise the homogeneous units of the basin, with the aid of the Geographic Information System. River Capivaraþs basin, that is located in the city of Botucatu (SP), is one of the most important affluent of the left margin of the River Tietê, situated between the plain coordinates 758000; 7486000 e 779645; 7456286, with a total area total of 22.218 ha. Were used as materials, the planialtimetric maps from IBGE, scale 1:50.000; air photographs of the BASE, scale 1:30.000; orbital images SPOT and Landsat from 1997 and CBERS from 2005; the Geographic Information System ILWIS 3.2 for Windows; scanners; GPS; plotters and mirror stereoscopy. For theme map elaboration were joined factors of the releif such as heighness and declive classes that generate class altitude and declivity map classes, added to the map of soil units (Piroli, 2002) generated the first approximation of the homogeneous units of the basin, refined with the information of soil usage and natural vegetation. The thematic map of the environment units have 11 different units, that are: Front of the Botucatuþs cuesta, Botto n of the valley of the medium and low Capivara, Ocidental Mountaintops of the medium and low Capivara, Mountaintops orientais of the medium and low Capivara, Conservated tops of the high Capivara, Tops of the medium and low Capivara, Vertents... (Complete abstract, clic electronic access below) / Orientador: Sérgio Campos / Coorientador: Luiz Alberto Blanco Jorge / Banca: Célia Regina Lopes Zimback / Banca: Mário Sérgio Rodrigues / Mestre