Os conceitos de mecânica da fratura têm sido cada vez mais utilizados em projetos de engenharia, permitindo a determinação de tamanhos críticos de defeito ou limites de solicitação em função da presença de trincas. No entanto, para aplicar com sucesso esses conceitos em uma avaliação de integridade estrutural é de suma importância a determinação exata do comportamento a fratura do material. Materiais com comportamento elasto-plástico têm ocupado cada vez mais lugar de destaque em estruturas e componentes críticos de engenharia e a maneira mais utilizada para caracterização da tenacidade à fratura desse tipo de material é a curva J-R. Embora existam métodos normatizados para determinação dessas curvas, esses possuem muitas vezes inconvenientes e limitações que tem justificado o desenvolvimento de vários estudos com vista à determinação de métodos alternativos. Nesse trabalho foi investigada a hipótese de que, a partir do estudo do campo deformacional nas proximidades da ponta de uma trinca, é possível desenvolver uma metodologia para determinação da curva de resistência à fratura de um material com comportamento elasto-plástico. Para tanto, um sistema óptico de medição de deformação baseado na técnica de correlação de imagem digital foi empregado para monitorar a deformação na superfície de corpos de prova do tipo SE(B) durante o ensaio de tenacidade à fratura. O objeto de estudo foi uma junta do aço API X65 soldada por processo de soldagem a laser. Os resultados obtidos demonstram o sucesso da técnica utilizada para obtenção da evolução do campo deformacional durante o ensaio. Além disso, a metodologia empregada possibilitou a determinação de expressões matemáticas que permitem associar valores de deformação com valores de integral J e Δa. Essas expressões são válidas para qualquer uma das três distintas regiões da junta soldada e permitem determinar com sucesso a curva J-R a partir da evolução da deformação durante o ensaio de um único corpo de prova. / The use of fracture mechanics has become increasingly popular in damage tolerance analysis or during determination of load limits in engineering components and structures. Nevertheless, the success of applying the concepts of fracture mechanics to investigate structural integrity assessment is highly dependent upon the correct determination of fracture mechanics material properties. The accurate prediction of ductile fracture behavior plays an important role in structural integrity assessment of critical engineering structures, including nuclear reactors, petrochemical vessels and tanks, pipelines in oil and gas industries and aircraft structures. J-R curve has become the most popular material parameters in elastic-plastic fracture mechanics and has been applied widely in practical engineering. There are procedures to determine J-R curves and they are widely presented in books and international standards. However, these procedures sometimes present some practical limitations or restrictions which have prompted research effort to develop alternative methods. In this work the hypothesis that is possible to develop a methodology to determinate J-R curve to materials with elastic-plastic behavior from analysis of near crack tip strain field was verified. For this purpose, an optical strain measurement system (OSMS) was used in order to monitor strains on surface of SE(B) specimens during fracture toughness testing. The methodology was applied to a laser welded joint of API X65 steel. The measurements successfully evaluate the strain field during testing. Besides of this, the methodology proposed allowed the determination of mathematical expressions to associate strain values with values of J-integral and crack extension (Δa). These expressions are valid to characterize these fracture toughness parameters to any one of the three distinct regions of the weld joint and made possible to determine J-R curve by monitoring the surface strain field evolution during a testing of a single specimen.

O presente trabalho teve como objetivo estudar a comparação entre o protocolo de Couto e o protocolo Strain Index, de Moore e Garg, para Análise Ergonômica do Trabalho, em dois postos de tornearia do setor de usinagem de uma indústria de médio porte, do setor metalúrgico. Para tanto, realizou-se uma fundamentação teórica, para apresentação dos métodos, cujos protocolos não são equivalentes (embora sejam aplicados como tal). Foi uma pesquisa aplicada, cujos resultados foram submetidos à análise quantitativa, buscando verificar os mecanismos de lesão a que estão sujeitos os operadores de tornos, neste caso específico, de uma indústria metalúrgica que possui dois postos de tornearia, sendo um para peças maiores que necessitam do uso de dispositivos de içamento e o outro posto dedicado a peças menores, capazes de serem manuseadas pelo operador. Concluiu-se que a relação entre o trabalho e a saúde requer a implantação e implementação, por parte das organizações e de políticas de prevenção, construindo uma cultura organizacional, em que seja propícia a realização da missão da organização com a garantia da qualidade de vida e realização das pessoas. / This study aimed to study the comparison between the protocol and the protocol Couto Strain Index, Moore and Garg, for ergonomic work analysis in two positions in the industry turning the machining of a medium-sized industry, metallurgical industry. To this end, we carried out a theoretical basis for presentation of methods, protocols are not equivalent (although they are applied as such). It was an applied research, whose results were submitted to quantitative analysis, in order to understand the mechanisms of injury that are subject to the operators of lathes in this particular case, a metal industry, which has two turning stations, one for larger parts that need the use of lifting devices and other station dedicated to smaller parts, capable of being handled by the operator. It was concluded that the relationship between work and health requires the establishment and implementation by organizations and prevention policies, building an organizational culture that is conducive to achieving the mission of the organization with the guarantee of quality of life and fulfillment of people.

O sucesso a longo prazo dos implantes tem como fatores críticos a incidência e a transferência de estresses mecânicos sobre a prótese, intermediários, implantes e destes para o tecido ósseo adjacente, devendo cada parte deste sistema ser submetido somente a forças às quais estão aptos a receber. A proposta deste trabalho foi avaliar a deformação gerada nos intermediários e na região óssea peri-implantar diante da aplicação de cargas funcionais e parafuncionais em prótese parcial fixa de três elementos parafusadas sobre dois implantes. Para este trabalho, foi utilizado um modelo experimental homogêneo à base de poliuretano, simulando o tecido ósseo, com dois implantes do tipo hexágono externo paralelos que receberam intermediários do tipo multi-unit. Na superfície de cada intermediário foram instalados três sensores (strain gauges), capazes de medir a microdeformação dispostos de maneira eqüidistante entre si. Na região óssea simulada, foram instalados quatro sensores para cada implante, posicionados nas faces mesial, distal, vestibular e lingual. A aplicação da carga estática de 300N foi realizada em uma máquina de ensaios universais. As leituras foram realizadas em quatorze momentos para todos os corpos de prova, variando o direcionamento da carga (axial e inclinada à 30 graus) e simulando ainda sete diferentes pontos de aplicação de carga (1- pilar mesial, 2 - pôntico, 3- pilar distal, 4- simultaneamente no pilar mesial, pontico e pilar distal, 5- no pilar mesial e distal, sem contato no pôntico, 6- no pilar mesial e no pôntico, 7- no pilar distal e no pôntico). Os resultados mostraram que a direção da carga interferiu na magnitude e distribuição da microdeformação, de forma que, no osso simulado, os valores encontrados na carga axial se encontraram dentro da tolerância fisiológica independente do local de aplicação de carga. Observou-se uma distribuição mais uniforme quando a carga foi aplicada simultaneamente nos pilres mesial, pôntico e pilar distal. Por outro lado, valores de microdeformação acima do limite de tolerância foram observados para a carga inclinada e nesta situação o local de aplicação teve influência na microdeformação, com valores extremamente elevados e sem uniformidade na distribuição, devendo o carregamento oblíquo ser evitado. / Long-term success with implants has some critical factors such as incidence and transmission of mechanical stress to the prosthesis, abutments, and implants to the adjacent bone tissue. Each part of the system should be subjected to loads under its strength limit. The purpose of the present study was to evaluate abutment and peri-implant bone tissue strains during functional and parafunctional loads application in a three-unit screw-retained fixed prosthesis supported by two implants. In order to simulate the bone tissue, an experimental model made of homogeneous polyurethane was used wherein two external hexagon implants were placed parallel to each other, provided with multi-unit abutments. On the surface of each abutment three sensors (strain gauges) were positioned equidistant to each other to measure microstrains. The simulated bone around each implant received four strain gauges, positioned on the mesial, distal, buccal and lingual aspects. The tests were performed applying a 300N static load on a universal testing machine. The readings were made at fourteen moments for each specimen, changing load direction (axial and 30 degrees oblique) and also simulating seven different points of load application (1- mesial abutment, 2- pontic, 3- distal abutment, 4- simultaneously on the mesial abutment, pontic and distal abutment, 5- mesial and distal abutment (no pontic contact), 6- mesial abumtent and pontic, 7- distal abutment and pontic. The results showed that the load direction significantly influenced the magnitude and distribution of microstrains, so that for the simulated bone, the values found during axial load were within the physiological threshold independent of the point of load application; however, a more uniform distribution was observed when force was applied simultaneously on the mesial abutment, pontic and distal abutment. Furthermore, microstrain values above the tolerance limits were observed during oblique load, and for this condition, the point of load application significantly influenced the microstrains, with extremely high values and non-uniform distribution for all load conditions tested. Therefore, oblique loading must be avoided.

Estratificar o risco de morte súbita é um grande desafio no manejo da cardiomiopatia hipertrófica (CMH). Os fatores de risco existentes atualmente apresentam baixo valor preditivo positivo e a estratégia para prevenção primária de morte súbita, que é o implante do cardiodesfibrilador implantável (CDI), baseia-se nesses fatores. Estudos que validem novos marcadores de risco são necessários, objetivando identificar pacientes com maior risco de morte súbita. A avaliação da deformação miocárdica (strain) por meio do Speckle Tracking na ecocardiografia bidimensional determina a função regional e global do ventrículo esquerdo, e, ainda, pode se correlacionar à fibrose miocárdica. Objetivo: Avaliar, em portadores de CMH e CDI, se a deformação miocárdica avaliada pelo Speckle Tracking, correlaciona-se com a ocorrência de taquiarritmias ventriculares registradas no monitor de eventos do CDI. Métodos: Foram incluídos 49 pacientes (43,5±15,8 anos; 59% mulheres) portadores de CMH e CDI acompanhados nos ambulatórios de Eletrofisiologia e Miocardiopatias do Instituto Dante Pazzanese de Cardiologia. Todos os pacientes foram submetidos à avaliação ecocardiográfica convencional padrão e análise do strain miocárdico pelo Speckle Tracking bidimensional. Foram divididos em dois grupos: grupo A, composto por aqueles que receberam terapia apropriada pelo CDI ou tiveram apenas a documentação de taquicardia ventricular não sustentada pelo CDI; e grupo B, composto por pacientes sem documentação de arritmias ventriculares no monitor de eventos. As variáveis contínuas foram comparadas utilizando-se testes t de Student pareado ou Mann-Whitney; para as categóricas o teste do x2 ou testes exatos de Fisher. Para análise dos dados, utilizou-se o programa SPSS. Valores de p < 0,05 foram considerados estatisticamente significativos. Resultados: Em 93,9% da população, a indicação do CDI foi por prevenção primária. Quinze pacientes (30,6%) compuseram o grupo A, 10 pacientes, por apresentarem taquicardia ventricular não sustentada (TVNS) e 5 por taquicardia ventricular sustentada (TVS). Os parâmetros ecocardiográficos convencionais não foram diferentes entre os grupos, com exceção do diâmetro da raiz aórtica, maior no grupo A (33,6 ± 4,4 e 29,4 ± 3,5, p = 0,001). Os valores do strain bidimensional longitudinal global, circunferencial global e radial global estavam reduzidos na população, porém não foram estatisticamente diferentes entre os grupos A e B. Pacientes do grupo A tiveram redução significante do strain circunferencial médio ao nível da valva mitral (SC médio VM) e do strain circunferencial no segmento ântero-septal ao nível da valva mitral (SC ântero-septal VM), em relação aos pacientes do grupo B (-12,3 ± 3,2 e -16 ± 3,9, p = 0,041 e -13,6 ± 6,6 e -18,7 ± 7,2, p = 0,039, respectivamente). O SC médio VM >= -14,2% apresentou 84,6% de sensibilidade e 70% de especificidade para predizer a ocorrência de taquicardias ventriculares em portadores de CMH com uma área sob a curva de 0,76 e nível de significância de 0,005; e O SC ântero-septal VM >= -17,9% apresentou 77% de sensibilidade e 60% de especificidade para predizer a ocorrência de taquicardias ventriculares em portadores de CMH com uma área sob a curva de 0,68 e nível de significância de 0,044. Conclusões: A presença de SC médio VM > -14,2% e SC ântero-septal VM > -17,9% correlacionaram-se com a presença de arritmias ventriculares malignas. Houve correlação positiva entre a presença de arritmias ventriculares malignas e o diâmetro da raiz da aorta. / Risk stratification for sudden cardiac death is still a challenging in the management of hypertrophic cardiomyopathy (HCM). The existing risk factors present low positive predictive value, and the strategy for primary prevention of sudden cardiac death, that is the implantable cardioverter-defibrillation (ICD), is based on these factors. Studies to validate new risk markers are necessaries to identify patients with higher sudden cardiac death risk. The evaluation of myocardial deformation (strain) through Speckle Tracking in two-dimensional echocardiography determines the regional and global function of the left ventricle, and still correlate with myocardial fibrosis. Objective: To evaluate, in patients with HCM and ICD, if the myocardial deformation evaluated through the Speckle Tracking correlates with the occurrence of ventricular tachyarrhythmias recorded in the monitor of implantable cardioverter-defribillation events. Methods: Forty-nine patients (mean age, 43,5 ± 15,8; 59% women) with hypertrophic cardiomyopathy and implantable cardioverter-defibrillation followed in Eletrophysiology and Cardiomyopathies Divisions at Dante Pazzanese Institute of Cardiology were included in the study. All patients underwent standard conventional echocardiographic evaluation and analysis of myocardial strain through two-dimensional Speckle Tracking. Patients were divided in two groups: group A, composed of those who received appropriate therapy by the ICD or had only the documentation of ventricular tachycardia not sustained by the ICD; group B, composed of patients without documented ventricular arrhythmias in the event monitor. Continuous variables were compared using paired t-Student test or Mann-Whitney. Categorical variables were analyzed using chi-square test or Fisher exact test. For data analysis, the SPSS program was used. P values < 0.05 were considered statistically significant. Results: Forty-nine patients (mean age, 43,5 ± 15,8; 59% women) were evaluated. 93.9% in the ICD was for Primary Prevention. Fifteen patients comprised the group A, ten patients for presenting Nonsustained Ventricular Tachycardia (NSVT) and five for Sustained Ventricular Tachycardia (SVT). Conventional echocardiographic parameters were not different between the groups, except for the aortic root diameter, higher in group A (33,6 ± 4,4 and 29,4 ± 3,5; p= 0,001). The values of global longitudinal, global circumferential and global radial two-dimensional strain were reduced in the population, but not statistically significant between groups A and B. Patients in group A had a significant reduction of the mean circumferential strain at the level of the mitral valve (mean SC MV) and the circumferential strain at the anteroseptal segment at the level of the mitral valve (anteroseptal MV SC), compared to the patients in group B (-12.3 ± 3.2 and -16 ± 3.9, p = 0.041 and -13.6 ± 6.6 and -18.7 ± 7.2, p = 0.039, respectively). The mean MV SC >= -14.2% presented 84.6% sensitivity and 70% specificity to predict the occurrence of ventricular tachycardias in patients with HCM with an area under the curve of 0.76 and a level of significance of 0.005 and Anteroposterior MV >= -17.9% presented 77% sensitivity and 60% specificity to predict the occurrence of ventricular tachycardias in patients with HCM with an area under the curve of 0.68 and a level of significance of 0.044. Conclusions: The presence of mean circumferential strain at the level of the mitral valve > -14,2% and anteroseptal circumferential strain at the level of the mitral valve > -17,9% correlated with the presence of malignant ventricular arrhythmias. There was a positive correlation between the presence of malignant ventricular arrhythmias and the aortic root diameter.

Introdução: A disfunção atrial esquerda está associada a pior prognóstico em diversas situações clínicas. O método de strain bidimensional do átrio esquerdo permite avaliar de forma direta todas as fases da função atrial. Pouco se conhece sobre o comportamento das fases da função atrial esquerda em pacientes com síndrome coronariana aguda. O objetivo desse estudo foi correlacionar as funções de reservatório, conduto e contração do átrio esquerdo com desfechos adversos cardiovasculares em pacientes com síndrome coronariana aguda sem supradesnivelamento do segmento ST. Método: Esse estudo recrutou prospectivamente 109 pacientes com diagnóstico de infarto agudo do miocárdio sem elevação do segmento ST e de angina instável de risco moderado ou alto pelo escore GRACE para realização de ecocardiograma nas primeiras 72 horas. A função atrial foi avaliada por parâmetros ecocardiográficos convencionais e pelo strain bidimensional obtido pela média das janelas apicais 2 e 4 câmaras. O desfecho primário foi avaliado em até um ano de seguimento e foi composto pelos seguintes eventos adversos: óbito, insuficiência cardíaca nova, nova internação por síndrome coronariana aguda ou por insuficiência cardíaca, angina estável com necessidade de nova intervenção coronariana, arritmia (fibrilação atrial ou taquicardia ventricular) e acidente vascular cerebral. Os desfechos secundários foram os combinados desses eventos. Resultados: As médias do strain de reservatório, conduto e contração foram de 25% ± 8, 12% ± 5 e 12% ± 4, respectivamente. O desfecho primário teve uma incidência de 31,8% em até um ano e apresentou uma correlação significativa com o strain de reservatório (HR= 0,92; IC95% 0,88-0,96; p<0,001), de conduto (HR= 0,87; IC95% 0,81-0,94; p<0,001) e de contração (HR= 0,90; IC95% 0,84-0,98; p=0,011). Análise multivariada envolvendo variáveis clínicas e as de função atrial esquerda demonstraram que o strain de reservatório (p=0,03) e de conduto (p=0,046) se mantiveram significativos como preditores do desfecho primário. O strain de conduto se manteve significativo no desfecho combinado de óbito e insuficiência cardíaca (HR= 0,82; IC95% 0,74-0,91; p<0,001) mesmo após análise multivariada com parâmetros clínicos (p<0,001) e ecocardiográficos (p=0,049). Conclusão: A avaliação da função atrial esquerda por meio do strain bidimensional se correlacionou significativamente com desfechos adversos em pacientes com síndrome coronariana aguda sem elevação do segmento ST. O strain de reservatório e de conduto foram marcadores prognósticos independentes para o desfecho primário quando comparados às variáveis clínicas. Já para o desfecho combinado de óbito e insuficiência cardíaca, o strain de conduto foi um preditor independente mesmo após ajustado para variáveis clínicas e ecocardiográficas. / Background: Left atrial dysfunction is associated with worse prognosis in several clinical situations. The left atrial two-dimensional strain method allows direct evaluation of all phases of atrial function. There are few studies on the behavior of the various stages of left atrial function in patients with acute coronary syndrome. The aim of this study was to correlate the functions of reservoir, conduit and contraction of the left atrium with adverse cardiovascular outcomes in patients with non-ST elevation acute coronary syndrome. Method: This study prospectively recruited 109 patients with a non-ST-segment elevation myocardial infarction and unstable angina with moderate or high risk by GRACE score and echocardiography parameters were collected within the first 72 hours of admission. The atrial function was evaluated by conventional echocardiographic parameters and the two-dimensional strain obtained by the mean of the apical two- and four-chamber views. The primary endpoint was assessed during the 1 year follow-up period and was composed of theses adverse events: death, heart failure, rehospitalization for acute coronary syndrome or heart failure, stable angina requiring new coronary intervention, arrhythmia (atrial fibrillation or ventricular tachycardia) and stroke. Secondary outcomes were those combined for these events. Results: The means of reservoir, conduit and contraction strain were 25% ± 8, 12% ± 5 and 12% ± 4, respectively. The primary endpoint occurred in 31.8% patients during the 1 year follow-up period and had a statistically significant correlation with the reservoir strain (HR = 0.92, 95% CI: 0.88-0.96, p <0.001), conduit strain (HR = 0.87, 95% CI: 0.81-0.94, p <0.001) and contraction strain (HR = 0.90, 95% CI: 0.84-0.98, p = 0.011). Multivariate analysis involving clinical variables and left atrial function showed that the reservoir strain (p = 0.03) and conduit (p = 0.046) were independent predictors of endpoint primary. The conduit strain were statistically significant in the combined outcome of death and heart failure (HR = 0.82, 95% CI: 0.74-0.91, p <0.001) even after multivariate analysis with clinical (p <0.001) and echocardiography parametrs (p = 0.049). Conclusion: Evaluation of left atrial function by two-dimensional strain correlated significantly with adverse outcomes in patients with non-ST elevation acute coronary syndrome. The reservoir and conduit strain were independent prognostic markers for the primary endpoint when compared to clinical parametrs. For the combined outcome of death and heart failure, the conduit strain was an independent predictor even after adjusting for clinical and echocardiographic variables.

This dissertation presents a numerical study using molecular dynamic simulations that interrogates the polymer structure as it is strained continuously in time and correlates it with the stress developed in it. We investigate the role of external control variables such as temperature, strain-rate, chain length, and density. At temperatures higher than glass transition, stress anisotropy is reduced even though bond stretch is greater at higher temperatures. There is a significant increase in stress level with increasing density. At faster rates of loading stress anisotropy increases. Deformation is mostly due to bond stretch and bond bending rather than overall shape and size. Stress levels increase with longer chain length. Cross-linkers beyond a critical value of functionality cause increased constraint on the motion of monomers and uniaxial stress developed increases. Stacking of chains also plays a dominant role in terms of excluded volume interactions. Low density, high temperature, low values of functionality of cross-linkers, and short chain length, facilitate chain uncoiling and chain slipping in crosslinked polymers. Uniaxial stress in linear polymers, on the other hand, is only mildly in uenced by temperature. Sinusoidal strain loading clearly reveals the viscoelastic nature of polymers. Internal structural parameters of the chains such as bond length, bond angle show hysteresis during loading and unloading. However, parameters representing overall size and shape of chains do not display any hysteresis. Small size magnetic particles and their small volume fractions in polymers show no signi cant e ect of applied external magnetic eld on anisotropic stress. Stress increases with lowering temperature, increasing density, decreasing volume fraction of magnetic particles, and increasing chain length

Cette thèse présente une étude structurale qualitative et quantitative du socle paléozoïque des Pyrénées. Elle se base sur une étude de terrain et une compilation exhaustive et inédite des structures, harmonisées à l'échelle de toute la chaîne des Pyrénées. A partir de cette base de données, nous avons construit le champ de déformation régional varisque produit au Paléozoïque supérieur (310-295 Ma). On montre que lors du raccourcissement régional majeur, la déformation est partitionnée entre une croûte supérieure s'épaississant en régime transpressif et une croûte inférieure fluant latéralement. Une zone d' " attachement " a permis de maintenir la cohérence cinématique entre ces deux domaines aux comportements structuraux contrastés. Le fluage latéral au sein de la croûte inférieure permet l'emplacement de dômes extensifs dans ce contexte convergent. Le refroidissement progressif de la croûte favorise i) le couplage mécanique progressif entre ces deux domaines et ii) une localisation de la déformation dans des zones de cisaillement transpressives verticales d'échelle crustale. Bien que situées dans l'avant-pays de la chaîne varisque, les Pyrénées enregistrent une déformation typique d'une lithosphère anormalement chaude. Ce contexte thermique est l'expression d'une délamination progressive du manteau lithosphérique initiée dans les zones internes de l'orogène et qui a permis la fermeture de la syntaxe ibéro-armoricaine ainsi que l'échappement latéral de la croûte ductile pyrénéenne pris dans cette syntaxe. L'analyse quantitative du champ de déformation à partir d'outils géostatistiques montre que ce champ résulte d'une déformation assimilable à un cisaillement pur produit par un raccourcissement NS tandis que la composante dextre de la transpression se concentre aux bordures de plutons ou de dômes. Ainsi, la mise en place de ces objets structuraux gouverne l'hétérogénéité du champ de déformation. La cohérence du champ de déformation varisque met en question l'existence de nappes de socle lors de la construction du prisme orogénique pyrénéen à partir du Crétacé supérieur. En dehors de la bordure ouest et sud de la Zone Axiale, le socle n'est affecté que par des réactivations mineures, y compris dans les Pyrénées centrales où le chevauchement de Nogueres ne peut être enraciné. Ce chevauchement correspondrait plutôt à un décollement dans les séries paléozoïques supérieures, impliquant des quantités de raccourcissement moindres durant la collision pyrénéenne que celles calculées précédemment. / We present a qualitative and quantitative structural study of the Paleozoic basement of the Pyrenees. Based on new observations and an extensive compilation of structural data that were harmonized at the scale of the orogen, we built the regional-scale Variscan strain field. The main Variscan deformation was partitioned between transpressional thickening of the upper crust and the laterally flowing lower crust. An attachment zone acted to maintain the kinematic coherency between these two structural domains. Lateral flow of the lower crust accompanied emplacement of syn-convergence extensional domes. Regional cooling progressively increases the degree of mechanical coupling between the two structural levels and enhanced strain localization in steep regional transpressive shear zones. Though part of the foreland of the Variscan orogen the Pyrenees developed strain patterns typical of hot crusts/lithospheres. Such a hot thermal context is due to lithospheric mantle delamination that initiated beneath the hinterland of the orogen and allowed the Iberian-Armorican syntax to close and extrude the soft Pyrenean crust trapped in it. Geostatistical analysis of the strain field suggests that it results bulk pure shear deformation with a dextral transpressional component restricted to the boundaries of plutons and domes. Emplacement of such structural objects governed the degree of heterogeneity of the strain field. The coherency of the strain field argues against the stacking of large basement nappes in the Axial Zone of the Pyrenees during building of the orogenic prism since the Late Cretaceous. Only the southern and western parts of the Axial Zone are affected by "Alpine" thrusting and only minor local reactivation occurred elsewhere in the Axial Zone. Therefore, the Nogueres thrust cannot root into the Axial Zone but is a decollement within Late Paleozoic series. This suggests a lower amount of Alpine shortening in this part of the Pyrenees than previously estimated.

Les anévrysmes se développant au niveau des fistules artério-veineuses (FAV), représentent une complication rare mais potentiellement mortelle dont la physiopathologie reste inexplorée. Jusqu’à présent la pratique courante était de les remplacer par un segment prothétique. Nous avons proposé un nouveau traitement chirurgical consistant en une anévrysmorraphie veineuse renforcée extérieurement par une exoprothèse. Notre premier objectif a été de rapporter les résultats à un an de cette nouvelle technique. Dans un second temps nous avons perfusé ex vivo des veines saphènes humaines renforcées par la même exoprothèse dans des conditions hémodynamiques de shear stress (SS) artériel en faisant varier la pression. L’analyse morphologique a montré le développement d’une hyperplasie intimale dans la veine sans et avec exoprothèse à haute pression. L’analyse des gènes et des protéines impliqués dans le remodelage vasculaire n’a pas montré de différence entre la veine nue et la veine renforcée mais nous a permis de mieux caractériser le rôle du SS et de la pression dans le mécanisme de l’artérialisation veineuse. Notre troisième objectif a été de décrire le remodelage anévrysmal des FAV. A partir d’une tissuthèque constituée d’échantillons de veines prélevées chez les patients opérés, nous avons comparé la veine artérialisée anévrysmale à la veine non artérialisée non anévrysmale. Les métalloprotéinases et leurs inhibiteurs participent activement à ce remodelage. Les anévrysmes régulièrement ponctionnés ont un profil inflammatoire qui influence la nature de ce remodelage. / Aneurysm complicating arteriovenous fistula (AVF) is a rare but potentially life-threatening complication. To date, its pathobiology remains unexplored and prosthetic replacement constitutes the conventionnal treatment. We have proposed a new surgical technique consisting in a venous aneurysmorraphy reinforced by an exoprosthesis. Our first goal was to evaluate the one-year results in terms of patency and aneurysm recurrence. Secondly, we have studied the impact of the exoprosthesis on human saphenous veins perfused ex vivo and submitted to different flow conditions consisting in an arterial shear stress (SS) in association with a low or a high pressure setting. Morphological analysis revealed an intimal hyperplasia in veins with and without exoprosthesis under high pressure. Analysis of the proteins and genes involved in the vascular remodeling did not showed an exoprosthesis effect but allowed us to better decipher the selective role played by SS and pressure in the arterialization process. Thirdly, we have collected tissue samples from patients operated and compared aneurysmal arterialized veins to non-aneurysmal non-arterialized veins. Metalloproteinases and their inhibitors actively participate in the remodeling. In aneurysms frequently cannulated inflammation influence the remodeling process.

Les animaux de compagnie présentent un intérêt majeur dans les études cardiovasculaires soit comme modèles expérimentales soit comme modèles spontanées. De plus, le développement de méthodes d'exploration non invasives en médecine vétérinaire est devenu une nécessité à cause de régulations strictes concernant le bien être de l'animal. Un facteur limitant demeure l'exactitude et la fiabilité (répétabilité/reproductibilité) des techniques d'exploration pour leur utilisation répétitive chez des animaux vigiles. La mesure de la pression artérielle systémique (PA) non invasive et l'échocardiographie conventionnelle et avancée ont gagné de la place dans le domaine de recherche ; cependant, il n'existe pas de recommandations spécifiques sur la validation métrologique de méthodes quantitatives utilisées en recherche clinique ou fondamentale en médecine vétérinaire. Le présent travail a premièrement focalisé sur la validation métrologique de la mesure de la PA chez le chien et le chat en étudiant la répétabilité et la reproductibilité de la méthode Doppler (chez les deux espèces) et de la méthode oscillométrique (chez le chien) et en déterminant l'influence du niveau d'expérience de l'opérateur sur la variabilité intra- et inter-jour et le pourcentage de mesures réussies. Puis l'effet de la position de l'animal et du nombre de mesures répétées sur de variables sélectionnées d'échocardiographie bidimensionnelle (2D) et temps-mouvement (TM) a été évalué. De plus, la méthode de l'aire de la surface de l'isovélocité proximale (PISA) pour la quantification de la régurgitation mitrale (RM) ainsi que le strain (St) et strain rate (SR) dérivé du Doppler tissulaire ont été validé chez le chien par le calcul de la répétabilité et la reproductibilité des techniques. Dans un deuxième temps les techniques précédemment validées ont été appliquées chez des chiens sains, des chiens souffrant de maladie valvulaire mitrale dégénérative (MVD) spontanée et dans un modèle expérimental de myopathie centronucléaire (CNM) chez des Labradors retrievers. Toutes les études ont été réalisées à l'Unité de Cardiologie d'Alfort, à l'Ecole Nationale Vétérinaire d'Alfort. Pour les mesures de la PA, toutes les deux études ont montré que l'entrainement est important, notamment pour la mesure de la pression diastolique avec le Doppler, tandis que la répétabilité et reproductibilité sont bonnes pour un opérateur expérimenté. Concernant l'échocardiographie 2D et TM, la technique peut être réalisée chez des chiens couchés ou debout avec une répétabilité/reproductibilité similaire. La fraction régurgitée évaluée par la méthode PISA est une variable répétable et reproductible pour l'évaluation de la RM chez le chien souffrant de MVD. De façon similaire le St et SR peuvent être mesurés de manière fiable chez le chien vigile et leur utilisation combinée avec d'autres paramètres échocardiographiques offre une nouvelle approche à l'étude de la fonction systolique dans cette espèce et peut complémenter l'échocardiographie conventionnelle pour la mesure de la performance myocardique. L'intérêt de ces méthodes validées a été illustré dans des études avec des chiens souffrant de MVD de gravité variable et une différence significative des paramètres étudiés (PA et fraction régurgitée) a été retrouvée dépendant du stade de la maladie. Enfin dans le modèle de CNM, des altérations sous-cliniques ont été détectées et considérées comme significatives étant donnée les faible coefficients de variation de techniques utilisées. En conclusion, le présent travail a évalué la répétabilité et la reproductibilité de quelques techniques d'exploration cardiovasculaires et a démontré l'importance de la validation en les appliquant dans des circonstances cliniques. Cependant ces résultats ne sont valables que dans les conditions spécifiques utilisées dans ces études. / Small animais present a major interest in cardiovascular studies either as experimental or as spontaneous models. Additionally, the development of non-invasive exploration methods in veterinary medicine has been impeding since regulations applying to animais are getting stricter and animal welfare has been the subject of many debates recently. A limitation factor regarding noninvasive cardiovascular exploration by different methods remains the accuracy, and reliability of the different techniques, that is to say, if the methods are repeatable and reproducible, and able to be used in repeated manner in awake animais. Although non-invasive arterial blood pressure (ABP) measurement and conventional, as weil as, advanced echocardiographic techniques have gained place in the domain of veterinary research, there are no specifie guidelines on how to metrologically validate a quantitative imaging technique in veterinary medicine for use in clinical or fundamental research. The present work focused firstly on metrological validation of non-invasive ABP measurement in dogs and cats by assessment of repeatability and reproducibility of Doppler ultrasonography (DU, in both dogs and cats) and high definition oscillometry (in dogs) and by determination of the influence of the observer's level of experience on within-day and between-day variability and the percentage of successful measurements. Then, the effect of animal position and number of repeated measurements on selected 2-dimensional (20) and M-mode echocardiographic variables in heal~hy dogs was evaluated. Moreover, the proximal isoveJocity surface area (PISA) method for quantification of mitral regurgitation (MR) and the tissue Doppler-derived strain (St) and strain rate (SR) technique in the dog were validated by calculation of repeatability and reproducibility. In a second step, the previously validated techniques were applied to healthy dogs, dogs suffering from spontaneous mitral valve disease (MVD) and to an experimental model of centronudear myopathy (CNM) in labrador retrievers. A total of 7 studies were realized. Ali studies were conducted at the Cardiology Unit of Alfort, in the National Veterinary School of Alfort. For ABP measurements, bath studies showed that training is important especially for evaluation of diastolic ABP with DU, whereas repeatability and reproducibility are good for sufficiently experienced observers. Regarding transthoracic 20 and M-mode echocardiography, itcan be performed on dogs in both standing position and lateral recumbency, and the repeatability of measurements is similar. Regurgitant fraction assessed by the PISA method is a repeatable and reproducible variable for the non-invasive evaluation of MR in awake dogs with MVD. This Doppler index is reliable, and its assessment can therefore be recommended for use, in combination with evaluation of other Doppler echocardiographic variables, in longitudinal studies of mitral valve disease in dogs. SimilarJy, myocardial St and SR can be measured non-invasively and in real time from regional myocardial velocities by TOI with good repeatability and reproducibility in the awake dog. The combined use of. St and SR indices with other tissue Doppler parameter's offers a new ultrasound approach to the systolic function in this species and may complement conventional echocardiographic measure of myocardial performance. The interest of those validation methods was firstly iIIustrated in studies involving dogs suffering from MVD of differing severity, where a relevant difference of the evaluated parameters (ABP and regurgitant fraction) was found depending on the stage of the disease.

Liquefaction is a costly phenomenon where soil shear modulus degrades as the generation of excess pore pressures begins. One of the methods to mitigate liquefaction, is the use of prefabricated vertical drains. Prefabricated vertical drains provide a drainage path to effectively mitigate the generation of pore pressures and aid in shear modulus recovery. The aims of this study were to define shear modulus degradation vs. shear strain as a function of excess pore pressure ratio; define the effects of prefabricated vertical drains on the behavior of pore pressure generation vs. shear strain; and to define volumetric strain as a function of shear strain and excess pore pressure ratios. A large-scale laminar shear box test was conducted and measured on clean sands with prefabricated vertical drains spaced at 3-feet and 4-feet. The resulting test data was analyzed and compared to data without vertical drains. The results show the effect of increasing excess pore pressure ratios on shear modulus and curves where developed to encompass these effects in design with computer programing like SHAKE or DEEPSOIL. The data also suggests that prefabricated vertical drains effectively mitigate excess pore pressure build-up, thus increased the shear strain resistance before pore pressures were generated. Regarding volumetric strain, the results suggests that the primary factor governing the measured settlement is the excess pore pressure ratio. This indicates that if the drains can reduce the excess pore pressure ratio, then the resulting settlement can successfully be reduced during a shaking event. The curves for shear modulus vs. cyclic shear strain as function of pore pressure ratio were developed using data with high strain and small strain which leaves a gap of data in the cyclic shear strain range of 0.0001 to 0.01. Further large-scale testing with appropriate sensitivity is needed to observe the effect excess pore pressure generation on intermediate levels of cyclic shear strain.