Les applications tribologiques des matériaux cellulaires en présence de liquide nécessitent une connaissance de leurs modes d’endommagement, mais elles restent peu connues à l’heure actuelle. L’étude, la compréhension et la modélisation du comportement d’un matériau composite cellulaire nécessitent une approche pluridisciplinaire due au caractère hétérogène du matériau qui reste difficilement caractérisable. Ce matériau peut être analysé suivant 3 axes bien distincts : les propriétés rhéologiques (analyses sous état de déformation complexe en compression et en cisaillement avec des rhéomètres adaptés), la morphologie des alvéoles (analyses 3D optiques et tomographiques), les propriétés tribologiques (analyse en frottement de l'interface et des particules d'usure). L’intérêt majeur de notre approche est d'aborder simultanément ces 3 axes et de comprendre leurs interactions respectives. La tomographie aux rayons X, suivie d’un traitement mathématique assisté par ordinateur, complété par l'analyse des particules d'usure a permis d'identifier les morphologies responsables des fonctions spécifiques du matériau cellulaire. Un tribo-abrasimètre innovant avec des surfaces abrasives modèles a mis en évidence l’importance des cinématiques dans l’endommagement du matériau. Des méthodes de caractérisation ont été mises au point afin de quantifier la dégradation tribologique du matériau permettant également de mesurer l’impact du vieillissement (chimique, thermique et mécanique). / Tribological applications of cellular materials in the presence of liquid require acknowledge of their modes of damage, but they remain little known at present. The study, understanding and modeling the behavior of a composite cell requires a multidisciplinary approach due to the heterogeneity of the material that is difficult to characterize. This material can be analyzed along three distinct axes: the rheological properties (analysis in complex state of deformation in compression and shear with adapted rheometer), the morphology of the cells (3D optical tomographic analysis), the tribological properties (analysis in interface friction and wear particles). The major advantage of our approach is to simultaneously address these three areas and to understand their interactions. The X-ray tomography, followed by computer-assisted mathematical treatment, supplemented by the analysis of wear particles identified morphologies responsible for specific functions of cellular material. A tribo-abrasimeter with innovative models abrasive surfaces highlighted the importance of kinematics in the damage of the material. Characterization methods have been developed to quantify the tribological degradation of the material can also measure the impact of aging(chemical, thermal and mechanical).

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Widely recognized security vulnerabilities in current wireless radio access technologies undermine the benefits of ubiquitous mobile connectivity. Security strategies typically rely on bit-level cryptographic techniques and associated protocols at various levels of the data processing stack. These solutions have drawbacks that have slowed down the progress of new wireless services. Physical layer security approaches derived from an information theoretic framework have been recently proposed with secret key generation being the primary focus of this dissertation. Previous studies of physical layer secret key generation (PHY-SKG) indicate that a low secret key generation rate (SKGR) is the primary limitation of this approach. To overcome this drawback, we propose novel SKG schemes to increase the SKGR as well as improve the security strength of generated secret keys by exploiting multiple input and multiple output (MIMO), cooperative MIMO (co-op MIMO) networks. Both theoretical and numerical results indicate that relay-based co-op MIMO schemes, traditionally used to enhance LTE-A network throughput and coverage, can also increase SKGR. Based on the proposed SKG schemes, we introduce innovative power allocation strategies to further enhance SKGR. Results indicate that the proposed power allocation scheme can offer 15% to 30% increase in SKGR relative to MIMO/co-op MIMO networks with equal power allocation at low-power region, thereby improving network security. Although co-op MIMO architecture can offer significant improvements in both performance and security, the concept of joint transmission and reception with relay nodes introduce new vulnerabilities. For example, even if the transmitted information is secured, it is difficult but essential to monitor the behavior of relay nodes. Selfish or malicious intentions of relay nodes may manifest as non-cooperation. Therefore, we propose relay node reliability evaluation schemes to measure and monitor the misbehavior of relay nodes. Using a power-sensing based reliability evaluation scheme, we attempt to detect selfish nodes thereby measuring the level of non-cooperation. An overall node reliability evaluation, which can be used as a guide for mobile users interested in collaboration with relay nodes, is performed at the basestation. For malicious behavior, we propose a network tomography technique to arrive at node reliability metrics. We estimate the delay distribution of each internal link within a co-op MIMO framework and use this estimate as an indicator of reliability. The effectiveness of the proposed node reliability evaluations are demonstrated via both theoretical analysis and simulations results. The proposed PHY-SKG strategies used in conjunction with node reliability evaluation schemes represent a novel cross-layer approach to enhance security of cooperative networks.

The Ethiopian Plateau is one of the few tectonically-active regions on Earth that is situated in continental rift zones. About 1.6 km deep gorge of the Nile was carved by the Blue Nile River on the Ethiopian Plateau, as the plateau has been experiencing continuous uplift and exhumation in the Cenozoic. Here, we used quantitative analysis of longitudinal rive-profile forms and parameters (knickpoint and normalized steepness-index ksn) of the Blue Nile tributaries to tease out regional tectonic signals. 244 knickpoints were examined in the tributaries, majority (>80%) of which are unassociated with lithology or geological structures. Knickpoint distribution throughout the plateau reveals three incision phases. The novel approach of correlation of ksn with mantle tomography suggests that higher and lower ksn values occur above low-velocity and high-velocity zones, respectively, indicating that thermal upwelling beneath the plateau linked to Afar mantle plume largely controls the uplift thus incision of the plateau.

<p>This work focuses on the construction and application of coded apertures to compressive X-ray tomography. Coded apertures can be made in a number of ways, each method having an impact on system background and signal contrast. Methods of constructing coded apertures for structuring X-ray illumination and scatter are compared and analyzed. Apertures can create structured X-ray bundles that investigate specific sets of object voxels. The tailored bundles of rays form a code (or pattern) and are later estimated through computational inversion. Structured illumination can be used to subsample object voxels and make inversion feasible for low dose computed tomography (CT) systems, or it can be used to reduce background in limited angle CT systems. </p><p>On the detection side, coded apertures modulate X-ray scatter signals to determine the position and radiance of scatter points. By forming object dependent projections in measurement space, coded apertures multiplex modulated scatter signals onto a detector. The multiplexed signals can be inverted with knowledge of the code pattern and system geometry. This work shows two systems capable of determining object position and type in a 2D plane, by illuminating objects with an X-ray `fan beam,' using coded apertures and compressive measurements. Scatter tomography can help identify materials in security and medicine that may be ambiguous with transmission tomography alone.</p> / Dissertation

Un C-arm est un appareil d’imagerie médicale par rayons X utilisé en radiologie interventionnelle. La plupart des C-arms modernes sont capables de tourner autour du patient tout en acquérant des images radiographiques, à partir desquelles une reconstruction 3D peut être effectuée. Cette technique est appelée angiographie rotationnelle et est déjà utilisée dans certains centres hospitaliers pour l’imagerie des organes statiques. Cependant son extension à l’imagerie du cœur ou du thorax en respiration libre demeure un défi pour la recherche. Cette thèse a pour objet l’angiographie rotationnelle pour l’analyse du myocarde chez l’homme. Plusieurs méthodes nouvelles y sont proposées et comparées à l’état de l’art, sur des données synthétiques et des données réelles. La première de ces méthodes, la déconvolution par FDK itérative synchronisée à l’ECG, consiste à effacer les artéfacts de stries dans une reconstruction FDK synchronisée à l’ECG par déconvolution. Elle permet d’obtenir de meilleurs résultats que les méthodes existantes basées sur la déconvolution, mais reste insuffisante pour l’angiographie rotationnelle cardiaque chez l’homme. Deux méthodes de reconstruction 3D basées sur l’échantillonnage compressé sont proposées : la reconstruction 3D régularisée par variation totale, et la reconstruction 3D régularisée par ondelettes. Elles sont comparées à la méthode qui constitue l’état de l’art actuel, appelé « Prior Image Constrained Compressed Sensing » (PICCS). Elles permettent d’obtenir des résultats similaires à ceux de PICCS. Enfin, deux méthodes de reconstruction 3D+temps sont présentées. Leurs formulations mathématiques sont légèrement différentes l’une de l’autre, mais elles s’appuient sur les mêmes principes : utiliser un masque pour restreindre le mouvement à la région contenant le cœur et l’aorte, et imposer une solution régulière dans l’espace et dans le temps. L’une de ces méthodes génère des résultats meilleurs, c’est-à-dire à la fois plus nets et plus cohérents dans le temps, que ceux de PICCS / A C-arm is an X-ray imaging device used for minimally invasive interventional radiology procedures. Most modern C-arm systems are capable of rotating around the patient while acquiring radiographic images, from which a 3D reconstruction can be performed. This technique is called C-arm computed tomography (C-arm CT) and is used in clinical routine to image static organs. However, its extension to imaging of the beating heart or the free-breathing thorax is still a challenging research problem. This thesis is focused on human cardiac C-arm CT. It proposes several new reconstruction methods and compares them to the current state or the art, both on a digital phantom and on real data acquired on several patients. The first method, ECG-gated Iterative FDK deconvolution, consists in filtering out the streak artifacts from an ECG-gated FDK reconstruction in an iterative deconvolution scheme. It performs better than existing deconvolution-based methods, but it is still insufficient for human cardiac C-arm CT. Two 3D reconstruction methods based on compressed sensing are proposed: total variation-regularized 3D reconstruction and wavelets-regularized 3D reconstruction. They are compared to the current state-of-the-art method, called prior image constrained compressed sensing (PICCS). They exhibit results that are similar to those of PICCS. Finally, two 3D+time reconstruction methods are presented. They have slightly different mathematical formulations but are based on the same principles: using a motion mask to restrict the movement to the area containing the heart and the aorta, and enforcing smoothness of the solution in both space and time. One of these methods outperforms PICCS by producing results that are sharper and more consistent throughout the cardiac cycle

Orientador: Lenice do Rosário de Souza / Resumo: Introdução: A aids caracteriza-se por comprometimento do sistema nervoso central, cujas células são importantes alvos para o vírus da imunodeficiência humana (HIV). Alterações neurológicas acometem cerca de 40% a 70% das pessoas que vivem com HIV/aids, chegando a 90% ou mais em estudos de necropsia. A toxoplasmose cerebral é a infecção mais comum, acomete cerca de 3% a 40% dos pacientes com aids e é a causa mais comum de lesão expansiva focal. Alguns critérios clínicos e radiológicos são utilizados para definição de seu diagnóstico. Objetivo: avaliar os dados epidemiológicos, clínicos, terapêuticos e as alterações cerebrais tomográficas no diagnóstico presuntivo de toxoplasmose cerebral em indivíduos com aids. Casuística e métodos: foram estudados, retrospectivamente, 28 pacientes com diagnóstico presuntivo de toxoplasmose cerebral, que realizaram exames de imagem a partir da suspeita clínica, atendidos no período de junho de 2012 a dezembro de 2018 e que realizaram tratamento específico para a infecção oportunista. A coleta de dados foi realizada por meio de consulta aos prontuários médicos dos pacientes que apresentaram critérios de inclusão para o estudo. Os exames de imagem foram avaliados com auxílio de médico radiologista do Serviço. As análises foram descritivas com cálculo de médias e desvios padrão para variáveis quantitativas e frequências e percentuais para variáveis categorizadas. Os sintomas pré e pós-tratamento foram comparados pelo teste qui-quadrado. Resultado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: AIDS is characterized by impairment of the central nervous system, whose cells are important targets for the human immunodeficiency virus (HIV). Neurological changes affect about 40% to 70% of people living with HIV / AIDS, reaching 90% or more in necropsy studies. Cerebral toxoplasmosis is the most common infection, affecting about 3% to 40% of AIDS patients and is the most common cause of focal expansive lesion. Some clinical and radiological criteria are used to define its diagnosis. Objective: to evaluate epidemiological, clinical, therapeutic and tomographic brain changes in the presumptive diagnosis of cerebral toxoplasmosis in individuals with AIDS. Patients and Methods: 28 patients with a presumptive diagnosis of cerebral toxoplasmosis, who underwent imaging from the clinical suspicion, were studied retrospectively from June 2012 to December 2018 and who underwent specific treatment for the opportunistic infection. The data collection was done by consulting the medical records of the patients who presented inclusion criteria for the study. The imaging exams were evaluated with the assistance of the radiologist of the Service. The analyzes were descriptive with calculation of means and standard deviations for quantitative variables and frequencies and percentages for categorized variables. Pre and post-treatment symptoms were compared by the chi-square test. Results: the majority of the patients were men (53.6%), with a mean age of 39.8 years. Headache wa... (Complete abstract click electronic access below) / Mestre

A ativação ultrassônica é um dos métodos mais utilizados para aumentar a eficiência mecânica e química dos irrigantes. No entanto, além de possivelmente causar desgastes indesejáveis na parede do canal, questiona-se a eficiência mecânica da irrigação ultrassônica ativada em canais com curvatura acentuada. O presente estudo teve como objetivo avaliar, por meio da microtomografia computadorizada (micro-CT) a influência do grau de curvatura dos canais radiculares nos desgastes dentinários não controlados produzidos pelo uso da Irrigação Ultrassônica Ativada (UAI), no percentual de debris dentinários remanescentes após UAI e o transporte do canal. Foram selecionados canais mesiais de 24 molares inferiores permanentes humanos, sendo 12 dentes com curvatura média de 25,5º (Curvatura Moderada) e 12 dentes com curvatura média de 50,9º (Curvatura Acentuada). Após escaneamento pré-operatório com um Microtomógrafo de raios-X, os canais foram preparados com os instrumentos Mtwo. Os dentes foram divididos em 2 grupos: Grupo CM (n=12) e Grupo CA (n=12). Ambos os grupos receberam irrigação ultrassônica ativada e em seguida foram escaneados novamente. Foram quantificados o volume e a profundidade máxima dos desgastes não controlados das paredes dos canais radiculares, o percentual de debris dentinários remanescentes e o transporte do canal. Foi realizada análise estatística, utilizando o software GraphPad Prism 7, com nível de singnificância de p <0,05. Os resultados mostraram que os grupos, apresentaram resultados semelhantes quanto ao volume de desgaste não controlado, porém o grupo CA apresentou desgastes mais acentuados no terço apical e um maior percentual de debri remanescente nos terços médio, apical e no total do canal radicular, além de promover desvio do canal no terço apical. Este estudo concluiu que curvaturas acentuadas interferem na profundidade do desgaste, na manutenção dos debris e no transporte do canal. / Ultrasonic activation is one of the most widely used supplementary irrigation methods. However, besides Ultrassonic Activated Irrigation (UAI) possibly causes uncontrolled removal of dentin in the root canal walls, it is unknown the efficiency of the ultrasonic irrigation in root canals with severe curvatures. The aim of the present study was evaluate using microcomputed tomography, the influence of the degrees of curvature in the percentage of remaining hard tissue debris, uncontrolled removal of dentin during UAI and root canal transportation. Twenty-four mesial roots of mandibular molars, 12 teeth with a mean curvature of 25.5º (Moderate Curvature) and 12 teeth with a mean curvature of 50.9º (Accentuated Curvature) were selected. After the pre-operative scanning with an X-ray microcomputed tomography, the specimens were prepared to size 35.04. The teeth were divided into two groups: Group CM (n = 12) and Group CA (n = 12). Both groups received ultrasonic irrigation and were scanned again. The maximum deep of the defects, volume of the uncontrolled removal of dentin, the percentage of remaining hard tissue debris and the root canal transportation were quantified. A statistical analysis was performed using GraphPad Prism 7 software, use Mann-Whitney test with a significance level of p <0.05. The results showed that the groups CM and CA had similar results in volume of uncontrolled removal of dentin, but the CA group show maximum deep defects more severe in the apical third, more percentage of hard tissue debri remaining in the middle, apical and total thirds of the canal root canal and a higher transport of the canal in the apical third. This study concluded that severe curves interfered in the maximum depth defects, in the maintenance of the debris and the transport of the canal.

A asma é uma doença crônica das vias aéreas, cuja fisiopatologia compreende inflamação, hiper-responsividade e remodelação. As características clínicas e a espirometria são usadas para avaliar o controle da doença. Alguns asmáticos não conseguem controlar tomando altas doses de medicações de controle (asma de difícil controle). A tomografia computadorizada quantitativa de tórax (TCQ) é pouco usada na asma, mas pode fornecer biomarcadores da doença. Objetivos: Comparar os achados de TCQ de indivíduos sem doenças respiratórias (grupo controle - GC), com asma controlada (ABC) e com asma de difícil controle (ADC), visando prioritariamente parâmetros substitutivos do remodelamento das vias aéreas. Investigar se há correlações entre os parâmetros QCT e espirometria. Materiais e Métodos: Recrutamos sujeitos com ADC e ABC em um hospital terciário. Usamos registros médicos e convite pessoal para obter dados de CG. Todos os indivíduos foram submetidos a tomografia computadorizada de alta resolução e espirometria. Um software (Yacta) foi usado para obter dados de TCQ. O teste t de Student, o one-way ANOVA e o teste exato de Fisher foram realizados para comparar os dados dos grupos. Os coeficientes de correlação de Pearson foram calculados para avaliar as correlações entre os parâmetros espirométricos e TCQ. Resultados: O GC foi composto por 21 sujeitos; ABC, de 28 e ADC, de 27. Estes últimos eram mais idosos que GC e ABC (50,85 (10,11); 41,27 (11,57); 42,04 (10,11) anos; p = 0,002). A espessura relativa das vias aéreas (ERP3-8) foi significativamente diferente entre GC e ADC (45,31% (3,71); 49,38% (3,38); p = 0,001) e entre GC e ABC (45,31%, 71); 48,25 (4,51); p = 0,001). A espessura normalizada das vias aéreas (Pi10) foi significativamente diferente entre ADC e ABC (0,51 (0,10); 0,44 (0,10); p = 0,0001) e entre ADC e CG (0,51 (0,10), 0,39 (0,08), p = 0,0001). A área da parede das vias aéreas (AP/ASC-mm2) da terceira geração brônquica foi significativamente diferente entre o ADC e o GC (37,14 (9,70); 30,18 (5,06); p = 0,005) e entre ABC e GC (35, 54 (6,37); 30,18 (5,06); p = 0,005). A área da luz da via aérea da terceira geração brônquica (LA/ASC-mm2) foi significativamente diferente entre ADC e ABC (28,81 (10,08); 35,88 (7,12); p = 0,002) e entre ADC e GC (28 81 (10,08); 36,14 (7,29); p = 0,002). A atenuação máxima média (MMA-Hounsfield Units) da terceira geração brônquica foi significativamente diferente entre ADC e GC (-128,68 (67,15); -232,01 (75,20); p = 0,0001) e entre ABC e CG (-147,81 (75,31); -232,01 (75,20); p = 0,0001). Encontramos correlações negativas entre o volume expiratório forçado no primeiro segundo (VEF1) e a ERP na terceira, quarta e quinta gerações brônquicas; entre o índice Tiffeneau e a ERP nessas gerações; entre fluxo expiratório forçado (FEF25-75%) e ERP nas mesmas gerações. Encontramos correlações negativas entre VEF1 e AMMna terceira e quarta gerações e entre o índice de Tiffeneau e AMM nessas gerações. Encontramos correlações negativas entre o FEF(25-75%) e o AMM nessas gerações. Conclusões: Mesmo os asmáticos com doença controlada apresentaram evidências radiológicas de comprometimento da parede das vias aéreas; as evidências foram maiores em asma de difícil controle. Características tomográficas podem ser devido a inflamação ou remodelação. Encontramos correlações entre os parâmetros espirométricos e TCQ. Nossos achados reforçam a utilidade potencial dos parâmetros do TCQ como biomarcadores do controle da asma e da resposta ao tratamento, em pesquisa e em bases clínicas / Asthma is a chronic airway disease whose pathophysiology comprises inflammation, hyperresponsivenes and remodelling. Clinical characteristics and spirometry are used to assess disease control. Some asthmatics do not achieve control taking high doses of controller therapy (difficult to control asthma). Quantitative lung computed tomography (QCT) is seldom used in asthma but may provide asthma biomarkers. Objectives: To compare QCT findings of subjects without respiratory diseases (control group - CG), with controlled asthma (CA) and with difficult to control asthma (DCA), aiming primarily at surrogate parameters of airway remodelling. To investigate whether there are correlations between QCT and spirometry parameters. Materials and Methods: We recruited subjects with DCA and CA from a tertiary hospital. We used medical records and personal invitation to obtain CG data. All subjects underwent high resolution computed tomography and spirometry. A software (Yacta) was used to obtain QCT data. Student\'s t-test, one-way ANOVA and Fisher\'s exact test were performed to compare data from the groups. Pearson correlation coefficients were calculated to assess correlations between spirometric and QTC parameters. Results: The CG was comprised of 21 subjects; CA, of 28 and DCA, of 27. The latter had older subjects than CG and CA (50,85 (10,11); 41,27 (11,57); 42,04 (10,11) years; p=0,002). Relative airway thickness (RT) was significantly different between CG and DCA (45,31% (3,71); 49,38% (3,38); p=0,001) and between CG and CA (45,31% (3,71); 48,25 (4,51); p=0,001). Normalised airway thickness (Pi10) were significantly different between DCA and CA (0,51 (0,10); 0,44 (0,10); p=0,0001) and between DCA and CG (0,51 (0,10); 0,39 (0,08); p=0,0001). Airway wall area (AWAmm2) of the third bronchial generation was significantly different between DCA and CG (37,14 (9,70); 30,18 (5,06); p=0,005) and between CA and CG (35,54 (6,37); 30,18 (5,06); p=0,005). Airway lumen area of the third bronchial generation (ALA-mm2) was significantly different between DCA and CA (28,81 (10,08); 35,88 (7,12); p=0,002) and between DCA and CG (28,81 (10,08); 36,14 (7,29); p=0,002). Mean maximum attenuation (MMA-Hounsfield Units) of the third bronchial generation was significantly different between DCA and CG (-128,68 (67,15); -232,01 (75,20); p=0,0001) and between CA and CG (-147,81 (75,31); -232,01 (75,20); p=0,0001). We found negative correlations between forced expiratory volume on the first second (FEV1) and RT on the third, fourth and fifth bronchial generations ; between the Tiffeneau index and RT on those generations; between forced expiratory flow (FEF25-75) and RT on the same generations. We found negative correlations between FEV1 and MMA on the third and fourth generations and between the Tiffeneau index and MMA on those geneations. We found negative correlations between FEF25-75 and MMA on those generations.Conclusions: Even asthmatics with controlled disease had radiological evidence of airway wall involvement; the evidences were greater in difficult to control asthma. Tomographic features can be due to inflammation or remodelling. We found correlations between spirometric and QTC parameters. Our findings reinforce the potential usefulness of QTC parameters as biomarkers of asthma control and of response to treatment, on research and clinical grounds

OBJECTIF : L’intégrité vasculaire est une pierre angulaire de la viabilité des organes solides, notamment en cas de transplantation. L’objectif de ce travail est de décrire les modifications du réseau vasculaire du cortex rénal dues à une séquence d’ischémie-reperfusion (IR) induite dans un modèle préclinique porcin d’autotransplantation rénale. MATÉRIELS ET MÉTHODES : Nous avions mis en place une technique d’analyse de la microvascularisation corticale rénale après acquisition microscanner et traitement des images de reins de porc perfusés avec un polymère de silicone radio-opaque.RÉSULTATS : L’ischémie-reperfusion rénale induit une diminution corticale du volume du segment vasculaire associée à une raréfaction des microvaisseaux inférieurs à 30 µm en particulier dans la corticale interne. Dans le cortex, une augmentation de la connectivité caractérisée par une augmentation des bifurcations et une diminution du facteur d’arborescence a été observée. L’hypercholestérolémie associée à l’ischémie-reperfusion entraine une raréfaction microvasculaire dans la corticale moyenne. Trois mois post-autotransplantation, l’augmentation de la durée de conservation des greffons induit une augmentation significative de l’épaisseur de la zone corticale, un effondrement du pourcentage de microvaisseaux. CONCLUSION : Trois mois après autotransplantation rénale, l’ischémie-reperfusion induit une raréfaction des microvaisseaux de la corticale interne. Nos résultats suggéreraient que l’altération de la fonction rénale chez des greffons pourrait être liée à une hypoxie chronique et une fibrose induite par une raréfaction microvasculaire proportionnelle à la durée de la conservation. / Purpose:Vascular integrity is a cornerstone of organ viability, particularly in cases of transplantation. The aim of this study is to describe the modifications of renal cortex vascular network due to an ischemia-reperfusion sequence in a preclinical pig kidney autotransplantation model.MATERIALS AND METHODS: Porcine kidneys were perfused with a radio-opaque silicone polymer and the cortex studied by X-ray micro-computed tomography. RESULTS: Renal ischemia-reperfusion led to decreased vascular segment volume associated with the rarefaction of vessels less than 30 µm diameter, particularly in the inner cortex. Vessels showed higher connectivity throughout the cortex. The decrease in microvasculature correlated with a deterioration of renal function, proteinuria, and tubular dysfunction, and was associated with the development of fibrous tissue. The hypercholesterolemia associated with ischemia-reperfusion promoted concomitant microvascular rarefaction for small vascular segments particularly in the middle cortex. At M3, the hypothermic preservation for 48 H of grafts compared to 24 H induced a significant increase in the cortical area thickness, associated with a drastic decrease of microvessels. CONCLUSION: Three months after renal autotransplantation, ischemia reperfusion induces a rarefaction of microvessels of the internal cortex. The hypercholesterolemia leads to a renal microvascular rarefaction which accentuates vascular remodeling due to ischemia reperfusion. Our results suggest that long preservation duration impacting the renal function in grafts could be associated with chronic hypoxia and fibrosis related to microvascular rarefaction.

Orientador: César Augusto Moreira / Resumo: Este trabalho apresenta a caracterização geológico-geofísica de duas ocorrências auríferas, uma na Fazenda do Funcho e a outra no Gabro Santa Catarina, ambas situadas no município de São Sepé, região centro-sul do Rio Grande do Sul. Ocorrências de ouro em concentrado de bateia em geoquímica de sedimentos de correntes realizados por trabalhos anteriores motivaram a continuidade da pesquisa nas duas áreas. A metodologia utilizada para atingir os objetivos foi o reconhecimento geológico de campo, levantamento de medidas estruturais e aquisição de dados geofísicos com aplicação dos métodos eletrorresistividade (ER) e polarização induzida (IP), por meio da técnica de tomografia elétrica, com execução dos arranjos dipolo-dipolo e Schlumberger. Os dados foram processados com base na técnica de inversão elétrica 2D e posteriormente interpolados para uma visualização em 3D. A análise dos dados permitiu a delimitação tridimensional de possíveis mineralizações sulfetadas em profundidade provenientes de fluidos hidrotermais provavelmente oriundos da intrusão do Granito São Sepé, que se caracterizou como uma fonte de calor e que remobilizou o ouro de outras rochas da região para as rochas das áreas estudo. A integração dos dados geoelétricos e estruturais, associados ao contexto metalogenético da região sugerem que as mineralizações de ouro estão hospedadas em fraturas, foliação e veios de quartzo nas rochas da Fazenda do Funcho e em fraturas do Gabro Santa Catarina. A partir da análise e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This thesis presents the geological and geophysical characterization of two gold occurrences, one at Funcho Farm and the other at Santa Catarina Gabbro, both located in the city of São Sepé, south-central region of Rio Grande do Sul. Gold occurrences in pan concentrate in stream sediment geochemistry performed by previous works motivated the continuity of the research in both areas. The methodology used to achieve the objectives was the geological field recognition, structural measures survey and geophysical data acquisition with the application of the electroresistivity (ER) and induced polarization (IP) methods, by means of the electric tomography technique, with the execution of the arrangements dipole-dipole and Schlumberger. Data were processed based on the 2D electrical inversion technique and then interpolated for a 3D view. The data analysis allowed the three-dimensional delimitation of possible deep sulphide mineralizations from hydrothermal fluids probably from the São Sepé Granite intrusion, which was characterized as a heat source and remobilized the gold from other rocks of the region to the rocks of the areas. study. The integration of geoelectric and structural data associated with the region's metallogenetic context suggests that gold mineralizations are hosted in fractures, foliation and quartz veins in the rocks of Funcho Farm and in fractures of Santa Catarina Gabbro. From the analysis and interpretation of 2D inversion and 3D visualization models acquired ... (Complete abstract click electronic access below) / Doutor