Objetivo: A proposta deste trabalho é avaliar o tempo de fibroplasia em tela de polipropileno na correção de hérnias incisionais da parede abdominal, em ratos, por meio da quantidade de colágeno, correlacionando-o com a resposta inflamatória local. Métodos: Trinta e seis ratos machos da linhagem Wistar foram submetidos à ressecção longitudinal de um segmento músculo-aponeurótico e peritoneal (3x2 cm) da parede abdominal, seguida por reforço com tela de polipropileno, em forma de ponte sobre a aponeurose. Os animais foram distribuídos em seis grupos, de acordo com o tempo de fibroplasia a ser estudado (um, dois, três, sete, 21 e 30 dias de pósoperatório). Após os prazos estabelecidos para estudo da fibroplasia, os animais foram submetidos à eutanásia, e a área de fixação da tela de polipropileno foi avaliada histologicamente quanto à reação inflamatória e à percentagem de colágeno pela técnica videomorfométrica assistida por computador. Resultados: O colágeno total foi identificado junto à tela no 3º dia pós-implante, apresentou aumento progressivo na sua proporção em todos os dias subseqüentes até o 21º dia, quando atingiu sua proporção máxima (p<0,001). A partir do dia 3, o colágeno III sofreu um aumento progressivo até o dia 21, quando atingiu sua proporção máxima (p<0,001), e no 30º dia apresentou uma redução significativa (p<0,001). O colágeno tipo I surgiu entre o 7º e o 21º dia, apresentou sua máxima proporção no 21º dia e manteve-se inalterado até o final do período de observação. A relação colágeno tipo I/tipo III aumentou progressivamente até o 30º dia de observação (p<0,001). Os neutrófilos foram identificados no 1º dia pós-implante, mantendo-se junto à tela até o 21º dia. Os macrófagos, gigantócitos e linfócitos foram identificados no 2º dia. Trinta dias após a implantação da tela, desapareceram os neutrófilos e mantiveram-se estáveis as proporções de macrófagos, gigantócitos e linfócitos (p<0,001). Conclusões: Os resultados do presente estudo evidenciaram colágeno total no 3º dia pós-implante, aumentando progressivamente até o 21º dia. O colágeno tipo III foi observado no 3º dia, aumentou até o 21º dia, quando reduziu significativamente. O colágeno tipo I surgiu entre o 7º e o 21º dia, e sua máxima proporção ocorreu no 21º dia, atingindo um platô. A relação do colágeno tipo I/tipo III aumentou progressivamente até o 30º dia, indicando maior proporção de colágeno tipo I ao final do período. O prolongamento da resposta inflamatória da cicatrização e a persistência do processo inflamatório crônico junto à tela não interferiram no tempo da fibroplasia. / Objective: This study assessed the amount of collagen and correlated it with local inflammatory responses to evaluate the length of time required for fibroplasia when polypropylene meshes are used to repair incisional abdominal wall hernias in rats. Methods: Thirty-six male Wistar rats underwent longitudinal resection of a peritoneal and musculoaponeurotic tissue segment (3x2 cm) of the abdominal wall followed by defect reconstruction with polypropylene mesh bridging over aponeurosis. The animals were divided into six groups according to the time points for the analysis of fibroplasia: one, two, three, seven, 21 and 30 days post-implantation. Animals were sacrificed at each time point, and the site where the polypropylene mesh was implanted was evaluated histologically to assess inflammatory response and percentage of collagen using computer-assisted video morphometry. Results: Total collagen was found at the mesh site on the third post-implantation day, and increased progressively on all subsequent days up to the 21st day, when it reached its highest percentage (p<0.001). Type III collagen increased progressively from the 3rd to the 21st day, when it reached its greatest percentage (p<0.001); on the 30th day, it decreased significantly (p>0.001). Type I collagen was first found between the 7th and 21st days, reached its greatest percentage on the 21st day and then remained stable until the 30th day. The type I to type III collagen ratio increased significantly and progressively up to the 30th day (p<0.001). Neutrophils were found at the mesh site from the 1st to the 21st post-implantation day. Macrophages, giant cells and lymphocytes were seen on the 2nd day. Thirty days after mesh implantation, neutrophils disappeared, but the percentages of macrophages, giant cells and lymphocytes remained stable (p<0.001). Conclusion: This study showed that total collagen was fist seen on the 3rd day post-implantation, increased progressively up to the 21st day. Type III collagen was first seen on the 3rd day, increased up to the 21st day, and then decreased significantly. Type I collagen was first seen between the 7th and 21st days and reached its greatest percentage on the 21st day, after which it remained stable. The type I and type III collagen ratio progressively increased up to the 30th day, indicating a greater percentage of type I collagen at the last observational time point. The prolonged healing inflammatory response and the persistence of chronic inflammation surrounding to the mesh did not affect the length of time required for fibroplasia.

The basis of this study are mutant plants with ARP2/3 complex lacking in one of its subunits (arpc5 and arp2). These plants also express CSC subunit CESA6 of primary cell wall tagged by YFP. Thanks to modern imaging technologies, it is possible to observe the movement of tagged cellulose synthase complexes in vivo at plasmatic membrane. Kymograph analyses was used to measure the velocity of CESA complexes. In addition to observing CESA complexes directly on the plasma membrane, experiments were made to regenerate cell walls of protoplasts of Arabidopsis thaliana plants arpc5 and WT. It was found, that observed mutants arpc5 and arp2 have reduced velocity of CESA complexes in comparison to WT and arpc5 protoplasts regenerate cellulose mesh of cell wall slower. Keywords: Cellulose synthesis, ARP2/3 complex, CESA, CSC velocity, arpc5, arp2, Arabidopsis thaliana.

Le développement d’une couche limite turbulente sur des structures entraîne des vibrations et des nuisances sonores. Celles-ci sont estimées par des calculs vibro-acoustiques qui nécessitent le spectre de pression pariétale turbulente en fréquence-nombre d’onde. Ce spectre est généralement calculé via des modèles empiriques. Or ces modèles ont un domaine de validité très restreint et ne sont pas adaptés pour des écoulements complexes, avec notamment des gradients de pression. Dans ces travaux, une méthode est proposée pour calculer les corrélations spatio-temporelles de pression pariétale à partir d’une solution sous forme intégrale de l’équation de Poisson. Le spectre de pression est obtenu à partir de la transformation de Fourier de ces corrélations. L’expression retenue pour ces dernières fait intervenir les dérivées d’une fonction de Green ainsi que les champs de la vitesse moyenne et des tensions de Reynolds qui sont obtenus par simulation RANS. Elle fait aussi intervenir des coefficients de corrélation de vitesse spatio-temporelle qui doivent être modélisés. Pour cela, un nouveau modèle de coefficient de corrélation spatiale a été développé : l’Extended Anisotropic Model. Le calcul des corrélations et du spectre de pression est réalisé en utilisant une méthode numérique basée sur une stratégie d’échantillonnage adaptatif combinée à du krigeage. Elle permet de réduire le nombre de valeurs de corrélation de pression nécessaires pour obtenir le spectre de pression pariétale et donc de réduire le temps de calcul. La méthode est appliquée à des écoulements de couche limite turbulente sur une plaque plane et sur un profil NACA-0012 avec un gradient de pression adverse. / Turbulent boundary layer flows over structures induce vibrations and noise. The latter are estimated by vibro-acoustic studies which require the wavenumber-frequency turbulent wall-pressure spectrum. This spectrum is generally computed via empirical models. However, these models have a very narrow domain of validity and are not adapted for complex flows, in particular with pressure gradients. In this work, a method is proposed to compute space-time wall-pressure correlations from an integral solution of the Poisson equation. The pressure spectrum is obtained by the Fourier transform of these correlations. The expression retained for the pressure correlations involves the derivatives of a Green function as well as the mean velocity field and the Reynolds stresses which are obtained by RANS solutions. It also involves space-time velocity correlation coefficients that have to be modelled. To achieve this, a new model was developed for the spatial correlation coefficients: the Extended Anisotropic Model. To compute the wall-pressure correlations and spectrum, a numerical method based on a self adaptive sampling strategy combined with Kriging is used. It reduces the number of pressure correlation values required to compute the wall-pressure spectrum and thus reduces the computation time. The method is applied to turbulent boundary layer flows over a flat plate and over a NACA-0012 profile with an adverse pressure gradient.

In this thesis, I examine Gwendolyn Brooks’s diptych poems “Two Dedications” from her 1968 collection In the Mecca. Critical accounts of “Two Dedications” cast the poems as fixed oppositions between “frivolous” Western art and inspiring, communal black art. I propose that such binaries are reductive and overlook the intellectual benefits Brooks locates in abstract modernist art. Using Ezra Pound’s theories of modernist difficulty, Walter Benjamin’s concept of artistic “aura,” and the Black Arts Movement (BAM) manifestoes of Ron Karenga and Larry Neal, I argue that Brooks’s poems demonstrate the benefits of both abstract Western art and representational BAM art. Specifically, Brooks suggests that both types of art provide avenues for self-determination and liberation from institutional conventions.

L'auxine est une hormone végétale impliquée dans le développement du gynécée. La réponse à l'auxine dépend majoritairement de deux familles protéiques : les ARF (Auxin Response Factors) et les Aux/IAA. Les ARF sont des facteurs de transcription qui régulent la transcription des gènes de réponse à l'auxine, tandis que les Aux/IAA inhibent l'activité transcriptionnelle des ARF par dimérisation. En présence d'auxine, les Aux/IAA sont dégradés et libèrent les ARF. Au cours de ma thèse, je me suis focalisée sur deux proches paralogues ETTIN/ARF3 et ARF4 impliqués dans le développement du gynécée chez Arabidopsis thaliana. Parmi les cibles directes d’ETT identifiées dans l'équipe, 2 catégories ont retenu notre attention : des gènes impliqués dans la voie de signalisation de l'auxine et des gènes codant des enzymes de remodelage de la paroi. Mon projet a consisté à essayer de comprendre l'implication de ces régulations transcriptionnelles dans le développement du gynécée. Dans une première partie, j'ai étudié la signalisation de l'auxine dans le développement du gynécée, puis l'implication d'ETT dans cette signalisation. Dans une deuxième partie, j'ai confirmé la répression par ETT, des cibles identifiées. Nous avons montré qu'ETT induit la déméthylation des pectines en inhibant les inhibiteurs de pectine méthylestérase. De plus, j'ai montré qu'ETT et ARF4 agiraient de façon redondante pour contrôler positivement la croissance du gynécée. Dans une troisième partie, j'ai abordé l'analyse des domaines fonctionnels du facteur de transcription CRABS CLAW, également impliqué dans le développement du gynécée. En conclusion, mes travaux de thèse apportent une nouvelle vision sur le rôle de la signalisation de l'auxine au cours du développement du gynécée et montrent l'importance du remodelage de la paroi dans la morphogénèse des organes. / The phytohormone auxin, is implicated in gynoecium development. Auxin response mainly depends on two protein families: ARFs (Auxin Response Factors) and Aux/IAAs. ARFs are transcription factors that regulate the transcription of auxin responsive genes, whereas Aux/IAAs inhibit the ARFs transcriptional activity by dimerization. In the presence of auxin, Aux/IAAs are degraded and consequently, ARFs are released. During my thesis, I focused on two close paralogs ETTIN/ARF3 and ARF4 involved in gynoecium development in Arabidopsis thaliana. Among the direct targets of ETT identified in the team, two categories held attention: genes involved in auxin signaling and genes encoding enzymes involved in cell wall remodeling. The aim of my project was to understand the implication of these transcriptional regulations in gynoecium development. In a first part, I analyzed auxin signaling during gynoecium development, as well as the implication of ETT in this pathway. In a second part, I confirmed the repression of the target genes by ETT. Interestingly, we showed that ETT activates the pectins demethylation by inhibiting the inhibitors of pectin methylesterase. Furthermore, I showed that ETT and ARF4 act in a redundant manner to positively control gynoecium growth. In a third part, I initiated the analysis of the functional domains of CRABS CLAW, a transcription factor also involved in gynoecium development. In conclusion, these results bring new information on the role of auxin signaling during gynoecium development and highlight the importance of cell wall remodeling in morphogenesis.

La production de biocarburants de deuxième génération basée sur la transformation de la biomasse végétale est une question d’actualité. La biomasse végétale est représentée par les parois des cellules, qui consistent en un réseau de microfibrilles de cellulose et de polysaccharides enchâssés dans de la lignine. Pour exploiter pleinement le potentiel de cette biomasse, il est nécessaire d’apporter des connaissances complémentaires sur les mécanismes de biosynthèse de ces polymères pariétaux. Par exemple, il est important d’améliorer le rendement de saccharification des microfibrilles de cellulose afin de produire de plus grandes quantités de bioéthanol. Nous avons donc combiné des études basées sur le modèle bien connu Arabidopsis et sur Brachypodium distachyon, la nouvelle espèce modèle pour les graminées tempérées et les céréales monocotylédones dédiées à la production de biocarburants. La cellulose est synthétisée par des complexes membranaires de cellulose synthases (CSC) qui contiennent les sous-unités catalytiques de cellulose synthase (CESAs), et cela requiert d’autres partenaires parmi lesquels KOR1, une endo-β-1,4-glucanase. Le trafic intracellulaire des CESAs semble jouer un rôle crucial dans la régulation du niveau de la synthèse de la cellulose. Nous avons étudié en détails le trafic intracellulaire de KOR1 dans des hypocotyles d’Arabidopsis cultivés à l’obscurité. En parallèle, lors d’un crible visuel de la collection de mutants de Brachypodium de l’INRA de Versailles, nous avons sélectionné un mutant nommé spa. Ce mutant partage des caractéristiques avec les mutants brittle culm du riz et de l’orge, comme par exemple des tiges cassantes, un xylème irrégulier, et une importante déficience en cellulose, surtout au niveau des tiges, qui contiennent 50% de la quantité retrouvée dans une plante sauvage. Des dosages de lignine ont montré une augmentation significative chez spa. De façon itnéressante, ce mutant présente un défaut flagrant du port érigé, au contraire des mutants brittle culm qui sont parfaitement érigés. Les défauts mécaniques du mutant spa s’illustrent par un module de Young trois fois inférieur à celui d’une plante sauvage. Des approches complémentaires ont été mise en œuvre afin d’identifier les défauts génétiques responsables de ce phénotype : le séquençage de gènes candidats reliés à la synthèse de la cellulose a été réalisé ainsi qu’une approche de NGS. De plus, dans le cadre du projet Européen RENEWALL et du projet KBBE CellWall, et grâce à l’outil BradiNet (M.Mutvil, KBBE CellWall) permettant d’accéder aux réseaux de co-expression, des stratégies RNAi sont en cours afin d’inactiver certains gènes seléctionnés selon des critères d’expression spécifiques, et selon leur implication potentielle dans la synthèse de la cellulose, spécifiquement chez les monocotylédones. Parmi ces gènes nous nous sommes concentrés sur la famille des MAP65 (Microtubules Associated Proteins), qui pourraient, au vu de la relation étroite entre microtubules et microfibrilles, jouer un rôle dans la déposition de la cellulose. / The production of second-generation biofuels based on the transformation of plant biomass is a pressing issue. Biomass is represented by cell walls of the plant cells consisting of a network of cellulose microfibrils and polysaccharides encrusted by lignin. To enhance the potential of plant biomass, we need to provide insights on the mechanisms of the biosynthesis of cell wall polymers. For example, it is important to improve the saccharification yield of cellulose microfibrils to produce the highest amount of bioethanol. We therefore combine studies on the well-known model plant Arabidopsis and Brachypodium distachyon, the new model species for temperate graminae and monocotyledonous crops dedicated to biofuel production. Cellulose is synthesized by plasma membrane-bound cellulose synthase complexes (CSC) containing cellulose synthase proteins (CESAs) and requires other partners among which the endo-beta1,4 glucanase KOR1. The intracellular trafficking of CESAs seems to be crucial to regulate the cellulose synthesis rate. We investigated in detail the intracellular trafficking of KOR1 in Arabidospis dark-grown hypocotyls.In parallel we selected by visual screening of the Versailles collection of mutagenized Brachypodium distachyon a mutant called spa. This mutant shares characteristics of the brittle culm mutants of rice and barley, such as brittleness, irregular xylem, and a cellulose content deficiency especially in stems, with 50% of the amount found in the wild type. Lignin assays indicate a higher amount of lignin in spa. Interestingly, this mutant is also "floppy" unlike others brittle culm mutants which are fully erected and the mechanical strength defects of spa is illustrated by a Young’s modulus three times lower than that of WT. Complementary approaches were used to identify the SPA gene: sequencing of candidate genes related to cell wall synthesis or co-expressed with secondary cell wall cellulose synthases and a classical mapping strategy combined with NGS methods. Moreover within the framework of the European RENEWALL and KBBE CellWall projects and thanks to the co-expression network tool BradiNet (M. Mutwil, KBBE project), RNAi strategies are in progress to inactivate a few genes selected according to specific expression criteria and potentially involved in cell wall synthesis specifically in monocots. Among these genes we are focusing on the MAP65 family (Microtubules Associated Proteins), which could play a role in cellulose deposition according to the close relationship between microfibrils and microtubules.

Made available in DSpace on 2015-07-22T20:50:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-24 / Introdução: O defeito na parede abdominal na área doadora do retalho musculocutâneo transverso do reto do abdome – retalho TRAM - é extenso, complexo e predispõe ao surgimento de hérnia, abaulamento e fraqueza abdominal. A reconstrução da parede abdominal deve ser anatômica e funcional, preferencialmente com tecidos autólogos, materiais de síntese resistentes e mínima tensão na sutura. As técnicas de descolamento músculo-aponeurótico seletivo da parede abdominal permitem uma reconstrução com tecido autólogo e tensão reduzida. Apesar dos relatos clínicos e avaliações em cadáveres, não foram encontrados estudos com a finalidade de comprovar, de maneira objetiva, a eficácia das manobras de descolamento músculo-aponeurótico seletivo na área doadora do retalho TRAM. Objetivo: Avaliar a resistência à tração dos componentes músculo-aponeuróticos na área doadora do retalho TRAM bipediculado. Métodos: No período de Maio de 2006 a Maio de 2008, foram estudadas 20 pacientes, com idade entre 29 e 58 anos, submetidas a reconstrução mamária com retalho TRAM bipediculado. A resistência à tração medial dos componentes músculo-aponeuróticos na área doadora do retalho TRAM foi medida, bilateralmente, com um dinamômetro analógico que foi fixado à margem lateral da lâmina anterior da bainha do músculo reto do abdome 3 cm inferior ao umbigo. Os coeficientes de tração foram comparados em três fases: Fase inicial sem qualquer incisão ou descolamento adicional na área doadora do retalho; Fase 1 incisão sobre a margem lateral da bainha do reto; Fase 2 descolamento do músculo oblíquo externo até a linha axilar anterior. Para a análise estatística foram utilizados os testes de Wilcoxon e o teste de t para dados emparelhados na comparação dos coeficientes de tração direito e esquerdo nas Fases inicial, 1 e 2. O teste de Friedman e teste post hoc de Dunn foram utilizados para comparar os coeficientes de tração das Fases inicial, 1, 2 no lado direito e no esquerdo. Resultados: Houve redução estatisticamente significante da resistência à tração após cada fase do descolamento seletivo. Conclusão: A resistência à tração medial dos componentes músculo-aponeuróticos na área doadora do retalho musculocutâneo transverso do reto do abdome diminuiu, após a incisão na margem lateral interna da bainha do músculo reto do abdome e após o descolamento do músculo oblíquo externo. / Introduction: The defect on the abdominal wall in the transverse rectus abdominis myocutaneos flap -TRAM flap- donor site is extensive, complex and predisposes the emergence of hernia, bulging and abdominal weakness. The closure of the abdominal wall must be anatomic and functional, preferably with autologous tissues, resistance synthesis material and minimal tension suture. The selective musculoaponeurotic undermining of the abdominal provide a abdominal wall closure with autologous tissue and reduced tension. Despite many clinical studies, no experimental researches prove the real efficacy of selective musculoaponeurotic undermining in the TRAM flap donor site. Objective: The aim of this study is to evaluate the resistance to medial traction of the musculoaponeurotic components in the bipedicled TRAM flap donor site. Methods: In the period of May of 2006 until May of 2008, 20 patients, with ages from 29 to 58 years old, submitted to mammary reconstruction with bipedicled TRAM flap were studied. The resistance to medial traction of the musculoaponeurotic components in the bipedicled TRAM flap donor site was measured with a dynamometer that was fixed in the lateral edge of the defect, 3 cm below the umbilicus. The traction coefficients obtained were compared in three situation: Initial Stage - with no incision or additional underminig in the flap donor site; Stage 1 - incision above the lateral edge of the rectus sheath; Stage 2 - undermining of the external oblique muscle. To the statistical analyses it was used the Wilcoxon and the t test to paired data in the comparison of the right and left traction coefficients in Initial Stage, Stage 1 and Stage 2. The Friedman test and the post hoc of Dunn test was used to compare traction coefficients in initial Stage, stage 1 and Stage 2, in the right and left sides. Results: There was a significant reduction of traction resistance after each stage of the dissection. Conclusion: The incision on the internal lateral edge of the rectus sheath and the external oblique undermining reduce the medial traction resistance of the musculoaponeurotic components in the TRAM flap donor site. / TEDE / BV UNIFESP: Teses e dissertações

O estudo do processo de fusão e solidificação da água contida dentro de materiais confinantes tem sido amplamente discutido em química, biologia, física, geologia, e com diversas aplicações tecnológicas, tais como aplicação na fabricação de etanol de segunda geração, ou etanol celulósico, separação de fases, fabricação de nanomateriais. Pesquisas mostraram que as temperaturas de transição da água nanoconfinada são muito sensíveis ao diâmetro do poro, mas que podem ser pouco afetadas pela natureza, hidrofóbica ou hidrofílica, da superfície do poro. Outra importante constatação em experimentos de fusão e congelamento em nanoporos é que nem toda água presente nos poros pode ser cristalizada até gelo. A existência de uma camada de água pré-fundida em nanoporos tem sido confirmada através de experimentos. Com o objetivo de entender mais profundamente como a temperatura de transição da água confinada depende da natureza da parede confinante e do tamanho do confinamento, propõe-se um modelo de nanoporos de celulose para o confinamento, onde varia-se o diâmetro e comprimento do nanoporo, além da natureza da parede do nanoporo. Nossos estudos, mostram que para sistemas hidrofóbicos, com formação de camada de água líquida na parede, as temperaturas de transição variam desde relativamente baixas, para menores valores de calor latente, até atingindo a temperatura de transição da água bulk, para calor latente mais alto. Enquanto que para sistemas hidrofílicos, para nenhum dos valores de calor latente trabalhados, e para nenhum tamanho do sistema, a temperatura de transição atinge o valor de bulk. / The study of the fusion process and water solidification inside confining materials has been widely discussed in Chemistry, Biology, Physics, and Geology, and has various technological applications as the usage and fabrication of second generation ethanol or cellulosic ethanol, phase separation, and nanomaterials fabrications. Researches have shown that nanoconfined water’s transition temperature are highly sensitive to the pore. Another interesting remark on freezing and fusion experiments on nanopores is that not all water present in pores can be crystallized into ice. The existence of a water layer pre-melted on nanopores has been confirmed through experiments. Aiming at understanding deeply how water’s transition temperature depends on the nature of the confining wall and size, a cellulose nanopore model is proposed to the confinement, where the nanopore diameter and length are varied, besides the nature of the wall of the nanopore. Our studies show that for hydrophobic systems, with the liquid water layer formation on the wall, the transition temperatures vary from relatively low latent heat to smaller values, even reaching the temperature transition on bulk water to higher latent heat. While for hydrophilic systems, for none of the latent heat used and no system size the transition temperature reaches bulk value.

Made available in DSpace on 2016-06-02T20:09:19Z (GMT). No. of bitstreams: 1 5795.pdf: 7169522 bytes, checksum: 82089f61a5b06c7100940687172cc2e6 (MD5) Previous issue date: 2014-02-19 / Universidade Federal de Minas Gerais / The resistance to compression is the property that determines the use of masonry as a structural system since the great majority of structural elements in such systems are generally subjected to compressive stresses. One of the factors to be taken into account in the design of these compression elements is their slenderness. For design in Brazil it is still used the concept of simplified slenderness where the buckling length is determined by an effective depth (hef) and the radius of gyration is replaced by a parameter called the effective thickness (tef) for calculating a resistance reduction factor. This reduction factor has its origin in very old international standards and building codes, dating back to when these codes used the allowable stresses method for the dimensioning of structural elements; due to its age, an effective explanation and derivation of this factor, therefore, has been lost and is unknown at this time. With the various updates of international standards for structural masonry and the consequent adoption of the limit state design method for dimensioning of elements, this factor has been abolished. In the Brazilian standards, however, even with the adoption of the limit state design method, this factor is still used, which is a contradiction. Studies on the strength reduction due to slenderness effects show that there are large differences when comparing the results given by the simplified method in the NBR with those given by international standards. These differences probably don t lead to loss of structural integrity of structures in Brazil because the slenderness ratio has been limited to low values, particularly in the case of unreinforced masonry. / A resistência a compressão é propriedade determinante no uso da alvenaria como estrutura, uma vez que a grande maioria dos elementos estruturais nesse tipo de sistema construtivo são submetidos preponderadamente ao esforço de compressão. Um dos fatores a ser levado em conta no dimensionamento de elementos comprimidos é a esbeltez desse elemento. Até hoje no Brasil utiliza-se o conceito de esbeltez simplificado, onde o comprimento de flambagem é determinado por uma altura efetiva (hef) e o raio de giração é substituído por um parâmetro chamado espessura efetiva (tef) para cálculo de fator minorador de resistência. Esse fator tem sua origem em normas e códigos de construção internacionais bastante antigos, remontando a épocas em que esses códigos tratavam o dimensionamento pelo Método das Tensões Admissíveis, tendo sido perdida e, portanto, sendo desconhecida a efetiva explicação da sua dedução. Com as diversas atualizações de normas internacionais em alvenaria estrutural e com a consequente adoção do Método dos Estados Limites para dimensionamento, esse fator foi abolido. Na normalização brasileira, mesmo com a adoção do Método dos Estados Limites, esse fator continua vigente, o que gera uma contradição. Estudos sobre o efeito da redução da resistência devido à esbeltez, mostram que existem grandes diferenças nos resultados quando se compara o método simplificado na NBR com os de outras normas internacionais. Essas diferenças provavelmente não induzem a perda de segurança nas estruturas nacionais porque o índice de esbeltez tem sido limitado a valores baixos, em especial no caso de alvenaria não-armada.

The aim of this research is to develop an optimisation tool to support the preliminary design of gas turbine combustors by providing a partial automation of the design process. This tool is to enable better design to be obtained faster, providing a reduction in the development costs and time to market of new engines. The first phase of this work involved the analysis of the combustor design process with the aim of identifying the critical tasks that are suitable for being automated and most importantly identifying the key parameters describing the performance of a combustor. During the second phase of this work an adequate design methodology for this problem was defined. This led to the development of a design optimisation Toolbox based on genetic algorithms, containing the tools required for it's proper integration into the combustor preliminary design environment. For the development of this Toolbox, extensive work was performed on genetic algorithms and derived techniques in order to provide the most efficient and robust optimisation method possible. The optimisation capability of the Toolbox was first validated and metered on analytical problems of known solution, where it demonstrated excellent optimisation performance especially for higher-dimensional problems. In a second step of the testing and validation process the combustor design capability of the Toolbox was demonstrated by applying it to diverse combustor design test cases. There the Toolbox demonstrated its capacity to achieve the required performance targets and to successfully optimise some key combustor parameters such as liner wall cooling flow and NOx emissions. In addition, the Toolbox demonstrated its ability to be applied to different types of engineering problems such as wing profile optimisation.