Dans cette thèse de doctorat, nous menons des investigations théoriques et expérimentales relatives aux structures localisées dans des lasers à cavité verticale émettant par la surface (VCSELs), aussi appelées solitons de cavité. Elles consistent en des pics d'intensité lumineuse dans le plan transverse à la propagation du faisceau lumineux. Ils ont été notoirement proposés pour deux applications :stockage tout optique de l'information, et le traitement de l'information optique.Dans la première partie de cette thèse, nous investigons les aspects théoriques des structures localisées dans un VCSEL à grande surface d'émission soumis à une injection optique et à un retour retardé. Nous dérivons une équation de Swift-Hohenberg généralisée à retard, d'application lorsque le système est proche du régime de bistabilité optique. En premier lieu, nous caractérisons les structures localisées stationnaires, en construisant leur diagramme de bifurcation en serpentage, typique de leur regroupement dans la zone d'accrochage des paramètres. Ensuite, nous montrons que le retour retardé peut induire un mouvement spontané de structures localisées à deux dimensions dans une direction arbitraire du plan transverse. Nous caractérisons ces structures mobiles en estimant le seuil de ce mouvement, ainsi que sa vitesse.Dans la deuxième partie de cette thèse, nous rapportons la formation spontanée de structures localisées dans un VCSEL de 80 micromètres de diamètre, pompé au delà de son seuil d'émission laser, et soumis à une injection optique. Ces structures sont bistables en la puissance du faisceau d'injection, ainsi qu'en le courant électrique. Nous étudions expérimentalement leur formation pour différents décalages en fréquence avec le faisceau de pompe optique. Nous rapportons la première mesure expérimentale mettant en évidence le caractère vectoriel des structures localisées générées dans un laser à grande surface d'émission: la polarisation de la structure localisée n'est pas celle de l'injection optique, dans la mesure où cette dernière est elliptique. Nous apportons un éclairage théorique sur cette expérience, en prenant en compte la dynamique de retournement de spin propre aux VCSELs à puits quantique. Ces résultats laissent entrevoir la possibilité de multiplexer l'information transmise en utilisant les propriétés de polarisation des structures localisées, utilisées comme pixels à la surface du VCSEL. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

A new crystal plasticity scheme for explicit time integration codes is developed based on a forward Euler algorithm in the first part of this paper. The new numerical model is incorporated in the UMAT subroutine for implementing rate dependent crystal plasticity model in LS-DYNA/Explicit. The material is modeled as a Face centered cubic (FCC) polycrystalline aggregate, and a finite element analysis based on rate-dependent crystal plasticity is developed to simulate large strain behaviour. Accordingly, an element or a number of elements of the finite element mesh is considered to represent a single crystal within the polycrystal aggregate and the constitutive response at a material point is given by the single crystal constitutive model. The second part of this thesis presents two applications of the crystal plasticity scheme used in conjunction with numerical modeling of three-dimensional (3D) real microstructures. First, finite element meshes containing both particle and texture data are created with solid elements. Particle size, location and orientation are represented by 3D ellipsoids and the elements within these ellipsoids are given rigid properties. Simulations of in-plane plane strain with different combinations of texture and particle location are performed. The effect on texture development, strain magnitudes, and strain localizations is investigated. Second, the three dimensional (3D) polycrystalline microstructure of the aluminum alloy AA5754 is modeled and subjected to three different strain rates for each strain path. The effect of strain paths, strain rates and thermal softening on the formation of localized deformation is investigated. Simulations show that strain path is the most dominant factor in localized deformation and texture evolution.

A new crystal plasticity scheme for explicit time integration codes is developed based on a forward Euler algorithm in the first part of this paper. The new numerical model is incorporated in the UMAT subroutine for implementing rate dependent crystal plasticity model in LS-DYNA/Explicit. The material is modeled as a Face centered cubic (FCC) polycrystalline aggregate, and a finite element analysis based on rate-dependent crystal plasticity is developed to simulate large strain behaviour. Accordingly, an element or a number of elements of the finite element mesh is considered to represent a single crystal within the polycrystal aggregate and the constitutive response at a material point is given by the single crystal constitutive model. The second part of this thesis presents two applications of the crystal plasticity scheme used in conjunction with numerical modeling of three-dimensional (3D) real microstructures. First, finite element meshes containing both particle and texture data are created with solid elements. Particle size, location and orientation are represented by 3D ellipsoids and the elements within these ellipsoids are given rigid properties. Simulations of in-plane plane strain with different combinations of texture and particle location are performed. The effect on texture development, strain magnitudes, and strain localizations is investigated. Second, the three dimensional (3D) polycrystalline microstructure of the aluminum alloy AA5754 is modeled and subjected to three different strain rates for each strain path. The effect of strain paths, strain rates and thermal softening on the formation of localized deformation is investigated. Simulations show that strain path is the most dominant factor in localized deformation and texture evolution.

In this experimental, we use ECAE with route BC to produce the ultrafine-grain Al and use different annealing temperature to get grain size at 0.4

Scleroderma is a chronic autoimmune connective tissue disease of unknown etiology characterized by excessive fibrosis and is broadly divided into two clinical entities: localized scleroderma (LSc) and systemic sclerosis (SSc). SSc is a multi-system disease resulting in both skin and visceral organ fibrosis. The more benign disorder, LSc is for the most part self-limited with the disease pathology being confined to the skin and subcutaneous tissues. Proposed factors involved in the pathogenesis of these disorders include endothelial cell injury and dysfunction, immunological alterations and inflammatory activation, and abnormal ECM production by activated fibroblasts. However, the initiating mechanisms that leads to these changes remains largely unknown. This thesis examines the hypothesis that the transcriptional expression at the edge and centre of expanding LSc plaques could represent the metabolic changes involved in the different stages of disease. The major finding of this thesis was the identification of two panels of genes that showed significant changes in expression between LSc patients and healthy controls irrespective of whether the sample was taken from a diseased or clinically unaffected area of the patient. The first panel consisted of inflammatory genes including those genes characteristic of the Thl response and those induced by NF-KB. The Thl response was supported by an increased infiltration of CD4+ T cells in the LSc patients. The second panel consisted of a subset of array identified genes (scleroderma Signature) in SSc patients. Of interest, WIF1 was down regulated in both disorders and showed a gradual decrease in expression across the clinically different areas of the LSc patients. Both panels of genes showed the biggest changes of expression at the edge of the plaque suggesting their involvement in the initiating events of the disease. These results suggest that, like SSc, the underlying pathology of LSc is related to systemic changes in genes controlling amongst others, immunological and inflammatory responses. This information not only sheds light on the mechanisms involved in the initiation and progression of scleroderma, but could also contribute to the creation of a diagnostic test for the early detection of sufferers of this rare, but important disease.

In eukaryotic cells, some mRNAs localize to distinct areas of the cell where RNA is translated and the encoded protein is specifically localized. Recent studies have suggested that even though prokaryotic cells lack internal compartmentalization, different RNAs can localize to distinct regions of the bacterial cell. Our lab is developing methods for labeling and detecting RNA with the goal of determining localization of endogenous RNAs within single cells. We currently employ an eIF4a protein-specific aptamer for RNA labeling using one of two methods. (1) Target RNA is tagged with the aptamer sequence at the 3' end and the aptamer triggers protein complementation of two fusion proteins, each containing split EGFP and split eIF4A proteins. (2) Two RNA probes, each containing a half of a split eIF4a-specific aptamer and an antisense sequence complementary to the target RNA, bind the unmodified transcript through complementary interactions. This binding brings the two fragments of the split aptamer in close proximity and allows proper folding of a split aptamer. A fluorescent signal is generated by the aptamer-driven reassociation of the fusion proteins. In this work, we investigate the sensitivity of the first method for detecting transcripts expressed from their natural chromosomal loci, and describe attempts to increase the sensitivity of the method by using multiple aptamer tagging. We also present results suggesting that the second method, combining protein complementation and split aptamer approach, provides high sensitivity enabling detection of endogenous bacterial RNAs expressed at low level.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24124号 / 理博第4852号 / 新制||理||1694(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 竹見 哲也, 教授 榎本 剛, 准教授 重 尚一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

No description available.

A new methodology is proposed to obtain the forming limit diagram (or FLD) of sheet materials by utilizing routinely obtained experimental load versus displacement traces and incorporating finite element (FE) analysis of strain history to extract the characteristic points of diffuse and localized necking and further the limit strains. The experimental data from hemispherical punch stretching test such as limit dome height, maximum load and location of inflection point are utilized to adjust the load curves in the FE simulations. An optimization procedure to obtain various parameters in material definition has been established to obtain a good agreement between the FE-based and experimental punch load versus displacement curves. An analysis of FE model based strain history is then carried out to determine the limit strains. This approach avoids using experimental strain measurement in the vicinity of the neck on the dome specimens. The materials tested with the new methodology include automotive sheets AA6111-T4, AA6181-T4 and DP600. The one utilized for optimization of FE inputs was AA6111-T4. The proposed method for FLD determination considers out-of-plane displacement, punch-sheet contact and friction, and avoids the use of a rather arbitrary inhomogeneity factor to trigger localization such as in the Marciniak-Kuczynski method. A new criterion to determine the localized necking is proposed by seeking an inflection point m the major strain rate curve, or, maximum point in the second order of derivative of major strain, (ε1)max. The proposed localized necking criterion is compared with other two methods to determine the onset of localized necking. These are (i) Bragard criterion for post-test of deformation, and (ii) critical major strain (ε1)cr based on comparison of strain of material inside the localized site and its vicinity in the un-necked site. The new criterion of (ε1)max exhibits a more definite physical meaning towards developing an understanding of flow localization, formability and fracture. This new approach for obtaining FLDs is rapid and accurate and could be implemented easily for routine FLO generation in a lab setting with little user input and subjectivity. / Thesis / Doctor of Philosophy (PhD)

Made available in DSpace on 2014-06-11T19:32:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-10Bitstream added on 2014-06-13T20:04:06Z : No. of bitstreams: 1 laperutaneto_j_dr_botfca.pdf: 2768401 bytes, checksum: 338080756314f0ac76b64ee591f2a757 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / A irrigação localizada tem como características principais a economia e um alto grau de uniformidade de distribuição de água. A irrigação localizada por gotejamento tem como componente principal os gotejadores que se encontram inseridos nas linhas laterais de gotejamento e são os grandes responsáveis pela economia de água e pela uniformidade de distribuição de água. Contudo, apesar dessas vantagens, esse sistema é também suscetível a uma série de fatores que alteram seu funcionamento, afetando a uniformidade de distribuição de água, conseqüentemente prejudicando a cultura, refletindo no lucro do produtor. Um desses fatores que afetam o funcionamento dos emissores é o depósito de partículas provenientes da água utilizada para irrigação. Essas partículas influenciam na variação da perda de carga mangueira da mangueira gotejadora. Este trabalho teve como objetivo avaliar a perda de carga em três modelos de mangueiras gotejadoras, duas com emissores coaxiais e uma com emissores nãocoaxiais, encontradas comercialmente em três condições distintas, quando novas, após 500 horas de uso com uma água rica em ferro e com emissores totalmente entupidos. O experimento foi conduzido no laboratório de ensaios de equipamentos de irrigação do Departamento de Engenharia Rural, da Faculdade de Ciências Agronômicas, Universidade Estadual Paulista “Julio de Mesquita Filho” – Campus de Botucatu, São Paulo. Primeiramente foram executados ensaios para obtenção do diâmetro interno, espessura da parede, área da seção do tubo com emissor inserido e vazão média das mangueiras gotejadoras, com base nas normas ISO 9261:2004 e NBR 12:02.08-21/1986, características essas importantíssimas, pois influenciam diretamente na perda de carga das mangueiras gotejadoras. Com base nesses ensaios, verificou-se que os valores encontrados e suas variações estavam dentro... / The main characteristics of localized irrigation are the economy and high uniformity of water distribution. In drip irrigation the main component are the emitters placed on the side of drip lines largely responsible for saving water, and the uniformity of water distribution. Despite these advantages, this system is also susceptible to a number of factors that affect its operation, affecting the uniformity of water distribution, causing damage to the culture, reflecting the profit of the producer. One of those factors that affect the operation of the emitters is the deposit of particles from the water used for irrigation. These particles cause wear of the walls of the drip lines and emitters and can lead to clogging. This study aimed to evaluate the head loss in three models of drip lines commercially available in three different conditions, when new, after 500 hours of use with rich iron water, and with clogged emitters. The experiment was conducted in the laboratory testing of irrigation equipment at the Department of Agricultural Engineering, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista Julio de Mesquita Filho - Campus de Botucatu, São Paulo. First tests were performed to obtain the constructive characteristics of drip lines, based on ISO 9261:2004 and NBR 12:02.08-21/1986, all important characteristics that affects directly the pressure drop of drip lines. Based on these results, it was found that the values and their variations were within the values established by standard, showing good quality in the manufacture of these drip lines. After that, the main head loss and local head loss in sites established in the sidelines of these drip lines were obtained. Based on these results it was found that the equations showed in the literature still needs adjustments with respect to the conditions that were subjected the drip lines. It was found that the non-coaxial... (Complete abstract click electronic access below)