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1
Belon, Claudine. "Rôle du facteur de virulence MGTC chez les mycobactéries et Pseudomonas aeruginosa et son inhibition par un peptide naturel." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS072/document.
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La résistance aux antibiotiques est un problème majeur en santé publique qui mène à développer de nouvelles stratégies thérapeutiques, notamment en ciblant des facteurs de virulence bactériens. MgtC est un facteur de virulence impliqué dans la survie intra-macrophagique chez plusieurs pathogènes intracellulaires. La protéine MgtC est également présente chez le pathogène extracellulaire Pseudomonas aeruginosa. De plus, un peptide MgtR a été identifié comme étant un antagoniste naturel potentiel de MgtC. Pour étudier le rôle de MgtC dans la virulence des mycobactéries, j'ai analysé un mutant mgtC de Mycobacterium marinum dans les modèles d'infection d'embryons de danio et de macrophages en culture. Cela a permis de mettre en évidence un nouveau rôle de MgtC au niveau de l'étape de phagocytose qui est augmentée avec le mutant mgtC. Chez P. aeruginosa, nous avons montré qu'un mutant mgtC est atténué dans l'embryon de danio et présente une sensibilité accrue à l'action bactéricide du macrophage. Par ailleurs, j'ai montré que les gènes mgtC de M. marinum et de P. aeruginosa sont régulés par le magnésium. De plus, l'expression de mgtC de P. aeruginosa est fortement induite dans les macrophages. Enfin, concernant les propriétés antagonistes de MgtR, des souches de Mycobacterium bovis BCG ou de P. aeruginosa exprimants mgtR semblent se comporter de la même manière que les mutants mgtC, suggérant des propriétés anti-virulence prometteuses pour MgtR et confirmant le choix de MgtC en tant que cible dans le cadre d'une stratégie anti-virulenceAntibiotic resistance is a major problem in public health, which leads to develop new therapeutics strategies, including strategies targeting bacterial virulence factors. MgtC is a virulence factor involved in intramacrophage survival in several intracellular pathogens. MgtC protein is also present in extracellular pathogen Pseudomonas aeruginosa. Moreover, a peptide MgtR has been identified as a potential and natural antagonist of MgtC.To study the role of MgtC in mycobacterial virulence, I have analysed a Mycobacterium marinum mgtC mutant in zebrafish embryo and macrophage infection models. This approach allowed us to uncover a new role of MgtC in phagocytosis, which is increased with mgtC mutant. In P. aeruginosa, we have shown that a mgtC mutant is attenuated in zebrafish embryos. In ex vivo experiments, mgtC mutant is more sensitive to macrophage killing. In parallel, I have shown that M. marinum and P. aeruginosa mgtC genes are regulated by magnesium. In addition, expression of P. aeruginosa mgtC is highly induced in macrophages.Finally, regarding MgtR antagonistic properties, Mycobacterium bovis BCG or P. aeruginosa strains expressing mgtR appear to mimic the behaviour of mgtC mutants, suggesting promising anti-virulence properties for MgtR and supporting the choice of MgtC as a suitable target of an anti-virulence strategy
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Stone, Christopher E., Keith D. Flint, and Gregory P. Mathis. "THE PHILLIPS LABORATORY’S MOBILE GROUND TRACKING STATION (MGTS)." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608411.
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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, NevadaPhillips Laboratory's Space Experiments Directorate (PL/SX) is operating and upgrading the laboratory's premier transportable satellite tracking station, the Mobile Ground Tracking Station (MGTS) program. MGTS supports orbital, suborbital, and aircraft missions as a range system capable of processing and recording multiple data streams. MGTS receives, processes, displays, and records satellite state-of-health data, infrared images in a variety of wavelengths, video data, and state vector solutions based on IR returns from the Miniature Sensor Technology Integration (MSTI) satellite program. The program has began in 1990 under BMDO sponsorship, with the intent to supplement existing test ranges with more flexibility in range operations. Wyle Laboratories and Systems Engineering and Management Company (SEMCO) provided the technical expertise necessary to create the first MGTS system. Autonomy and off-road capability were critical design factors, since some of the operations envisioned require deployment to remote or hostile field locations. Since inception, MGTS has supported the Lightweight Exo-Atmospheric Projectile (LEAP) sub-orbital missions, the MSTI satellite program, and Air Force wargame demonstrations. In pursuit of these missions, MGTS has deployed to White Sands Missile Range (WSMR), NM; Air Force Flight Test Center (AFFTC), Edwards AFB, CA; Vandenberg AFB, CA; Falcon AFB, CO; and NASA's Wallops Island Flight Facility, VA, to receive critical mission telemetry data conforming to both IRIG and SGLS standards. This paper will describe the evolution of the MGTS program, current hardware configurations and past and future mission scenarios for the MGTS team.
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Zhou, Sihai. "Processing and characterisation of MgB₂ superconductors." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20041111.135706/index.html.
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Ling, Jiayin. "Monofilament MgB₂ wires for MRI magnets." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78185.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-86).
MRI magnets are useful medical devices in early detection and efficient treatment of disease or injury. Because of the significant better performance, MRI magnets are made of superconductors rather than made of copper. Nowadays, there are over 20,000 superconducting MRI magnets installed worldwide. Most of them are made of NbTi or Nb₃Sn, but they are usually very expensive to purchase or operate. So, my colleagues chose MgB₂ wires to develop low-cost and easy-to-operate MRI units which serve to the majority of the humanity. Because we have a reliable technology to fabricate superconducting joints with monofilament MgB₂ wire, we decided to build our MgB₂ MRI magnet with monofilament wire instead of multifilament wire. Previously, flux jumping was found to be the main issue with monofilament superconducting wire; we have to demonstrate that flux jumping is not a big issue with monofilament MgB₂ wire before we can build our MRI magnet with it. In this thesis, a series of experiments was designed and carried out to prove that the monofilament MgB₂ wire performs as well as the multifilament MgB₂ wire in MRI magnet applications. Short samples of monofilament MgB₂ wires were tested, and magnetization trace of the short samples showed that flux jumping could be a minor issue with monofilament MgB₂ wire. Three 100-m sample coils made of multifilament MgB₂ wire, monofilament MgB₂ wire, and monofilament NbTi wire were wound, tested and compared. The results of these tests demonstrated that the monofilament MgB₂ wire has insignificant flux jumping which does not lead to a premature quench. So, monofilament MgB₂ wire is potentially a good option for MRI magnets.
by Jiayin Ling.
S.M.
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Flint, Keith D., Gregory P. Mathis, and Tom G. Cronauer. "The Phillips Laboratory's Mobile Ground Telemetry Station (MGTS) Configuration and Operations." International Foundation for Telemetering, 1993. http://hdl.handle.net/10150/611830.
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International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, NevadaIn support of the various programs that the Phillips Laboratory's Space Experiments Directorate is conducting for the Ballistic Missile Defense Organization (BMDO), the Range Operations Division is developing a mobile telemetry processing system as part of the Mobile Ground Telemetry Station (MGTS) program. The MGTS program's goals are to develop a mission-dedicated telemetry system to supplement current test range capabilities by receiving, processing and recording multiple data streams, sometimes exceeding 10 Mbps. The system will support airborne and suborbital vehicles as well as customized satellite downlinks designed for spacecraft bus State-of-Health monitoring and sensor payload observations. Autonomy and off-road capabilities are also important factors since some of the operations envisioned require deployment to remote field locations where no telemetry processing capabilities currently exist to support the unique data handling requirements. The Phillips Laboratory has completed, with support from Wyle Laboratories and Systems Engineering and Management Company (SEMCO), a "proof-of-concept" mobile telemetry processing system referred to as MGTS #2. Demonstration of the system has been accomplished with the successful deployment and operational support provided to both BMDO's Lightweight Exo-Atmospheric Projectile (LEAP) sub-orbital missions and Miniature Sensor Technology Integration (MSTI) satellite program. MGTS #2 has deployed and is scheduled for further deployment to various operating sites including: White Sands Missile Range (WSMR), NM; Air Force Flight Test Center (AFFTC), Edwards AFB, CA; Vandenberg AFB, CA; and NASA's Wallops Island Flight Facility, VA. While deployed MGTS #2 processes, records and rapidly distributes the critical mission telemetry data conforming to both IRIG and SGLS standards. This paper will describe the evolution of the MGTS program, current hardware configurations and the various mission scenarios that have been supported by the MGTS team.
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Avronsart, Julien. "Conception d’un aimant supraconducteur MgB₂ à hauts champs." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS292/document.
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La raréfaction de l'hélium utilisé pour le refroidissement des aimants supraconducteurs pousse les fabricants d'aimants supraconducteurs à se tourner vers d'autres types de supraconducteurs performants qui peuvent être employés et refroidis par conduction solide; C'est le cas du MgB₂ . Découvert en 2001, sa température critique (39 K), sa production en série sous différentes formes (rubans, câbles, films etc…) sur de grandes longueurs permettent d'envisager une utilisation à un prix compétitif dans les aimants en remplacement des supraconducteurs basses températures historiques que sont le NbTi et le Nb₃Sn.Cependant, les conducteurs en MgB₂doivent encore être améliorés notamment leur tenue mécanique par rapport aux conducteurs en NbTi et leurs performances réelles à hauts champs doivent encore être démontrées dans les applications concrètes.Cette thèse a pour but le dimensionnement et la fabrication d'un prototype d'aimant MgB₂ refroidi par conduction solide générant un champ au centre de 2 T dans un champ de fond de 3 T. Trois longueurs de conducteur ont du être soudées par deux jonctions résistives au centre du bobinage complexifiant la fabrication du prototype. La thèse s'articule autour de trois axes structurant. Tout d'abord, des caractérisations des performances supraconductrices et mécaniques de différents conducteurs en MgB₂ permettent de sélectionner le conducteur utilisé pour le bobinage du prototype. Ensuite, le dimensionnement du prototype est présenté : calculs mécaniques, thermiques, magnétiques et thermalisation de l'aimant sans oublier la protection. Après la phase de dimensionnement, les étapes nécessaires à la fabrication du prototype (bobinage,imprégnation, mise en place de l'instrumentation et des systèmes de thermalisations) sont détaillées. Afin de valider les étapes précédentes et les performances du prototype, la thèse se termine par une présentation et une analyse des résultats des tests effectués sur le prototypeHelium shortage is an issue for superconducting magnets and drives superconducting magnet designer to find other types of effective superconductors that could be used in conduction-cooled magnets.MgB₂ is a promising superconducting material and could fill the demand. MgB₂ was discovered in2001, its critical temperature (39 K) as well as its mass production of a variety of shapes (ribbons, films, cables, wires…) over long length makes MgB₂ a competitive substitute to historical low temperature superconductors such as NbTi and Nb₃Sn in magnets. Although promising, MgB₂ conductors still need mechanical improvement compared to NbTi's and their performance in practical applications has yet to be demonstrated especially for low bending radius magnets. This thesis aims to design and builda MgB₂ conduction-cooled prototype generating a 2 T on the axis on its own in a 3 T background field. Three lengths of conductors were fused by two resistive junctions at the very heart of the winding challenging the design and the fabrication because of the thermal issues. The thesis focuses on three main topics. First, superconducting and mechanical performances of several MgB₂ conductors candidates for the prototype are analyzed and discussed. The design calculation (magnetic, mechanical,thermalization of the prototype and protection) and all the fabrication process (winding, instrumentation, thermal apparatus and impregnation) are presented. In order to validate the fabrication steps and the performances of the prototype, the protoype is tested and the results discussed in the last chapter
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Tellaroli, Taís Marina. "TV DIGITAL INTERATIVA NO BRASIL: ESTUDO DOS APLICATIVOS INTERATIVOS STICKERCENTER E DO TELEJORNAL MGTV." Universidade Metodista de São Paulo, 2013. http://tede.metodista.br/jspui/handle/tede/648.
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Com o avanço da tecnologia e chegada da TV digital no Brasil, estudos apontam que a televisão aberta começa um novo estágio desde seu surgimento. Esta mídia disponibiliza ferramentas que permitem aos emissores de conteúdo uma dimensão interativa ainda não experimentada, sobretudo nos processos de comunicação massivos indicando que é possível novos caminhos de investimento na produção de conteúdo por parte das emissoras de TV. Com esta realidade de fundo, experiências começam a ser testadas no âmbito da televisão, como o StickerCenter, um software - desenvolvido pela TOTVS - que reúne elementos da internet na TV possibilitando ao receptor maior interação com o conteúdo televisivo, outra experiência é a realizada pela Rede Integração, afiliada à Rede Globo em Minas Gerais, com o software desenvolvido pela HXD Interactive Television, que testa um modelo brasileiro de interatividade no telejornal. Este trabalho mostra como estas duas empresas estão desenvolvendo aplicativos interativos para a TV utilizando o Middleware Ginga e os motivos pelos quais sua popularização não aconteceu. O StickerCenter não se popularizou e indica que o motivo seja erro de estratégia da empresa em desenvolver um produto que une broadband e broadcast TV sem atrativos ao consumidor, já o aplicativo interativo da Rede Integração não foi colocado no ar e apresenta inúmeros fatores que demonstram que não explorará a interatividade pela ausência de canal de retorno. Este estudo investigou o impacto da interatividade no mercado da radiodifusão e como a convergência tecnológica aponta para a construção de uma nova mídia baseada em displays interativos capazes de oferecer aos consumidores uma nova forma de recepção de conteúdo.
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Yonamine, Anne Hitomi [UNESP]. "Estudo das propriedades supercondutoras e da microestrutura do supercondutor Mg'B IND. 2' puro e dopado com compostos de carbono." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/88449.
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Após a descoberta dos novos supercondutores óxidos no ano de 1986, houve uma intensa busca por outros materiais que apresentassem o fenômeno da supercondutividade. Dentre as novas descobertas encontra-se o diboreto de magnésio, material intermetálico cuja supercondutividade era desconhecida até 2001. Atualmente, este é considerado ter um grande potencial de aplicação real devido a sua simplicidade de confecção e ao baixo custo de resfriamento em cryocoolers, visto que o fenômeno ocorre próximo de 39K. Ao longo de quase uma década muitas pesquisas foram realizadas com os objetivos de melhor conhecer o mecanismo de supercondutividade presente no material, assim como de aperfeiçoar a sua capacidade de suportar correntes em campos magnéticos altos e desta forma ampliar suas possibilidades de aplicação industrial. Hoje, encontra-se claro que o mecanismo que rege a supercondutividade no Mg'B IND. 2' é o mesmo descrito em 1958 por Bardeen, Cooper e Schriefer, na teoria BCS. Mas, por outro lado, as questões práticas permanecem incompletas, pois a queda da capacidade de conduzir supercorrente sob campos magnéticos altos (acima de 6T) ainda não foi superada satisfatoriamente. Com este objetivo, estuda-se a introdução de diversos compostos na matriz do diboreto de magnésio tais como elementos metálicos ou compostos de carbono. Mais recentemente, os estudos se voltaram para a utilização das técnicas de processamento cerâmico a fim de aperfeiçoar a microestrutura e melhor densificar o material. Neste trabalho o estudo da adição de um novo dopante, o hidrocarboneto 'C IND. 8''H IND. 18', é realizado comparativamente à outros dopantes extensivamente citados na literatura como o carbeto de silício e o óleo de silicone. O processo de sinterização de pastilhas ex situ é também investigado para todas...
After the discovery of new superconducting oxides in the year 1986, there was an intense search for other materials that show the phenomenon of superconductivity. Among the new discoveries is magnesium diboride, an intermetallic material whose superconductivity was unknown until 2001. Currently, it is considered to have great potential for real application due to its easy fabrication and low cost cooling as cryocoolers, since the phenomenon occurs around 39K. For almost a decade surveys have been conducted with the objective of better understanding the mechanism of superconductivity in this material, as well as to improve its ability to withstand current in high magnetic fields and thus broaden their scope of industrial application. Today it is clear that the mechanism governing the superconductivity in Mg'B IND. 2' is the same as described in 1958 by Bardeen, Cooper and Schriefer, in the BCS theory. But on the other hand, practical issues remain incomplete, since the fall of the ability to conduct supercurrent in high magnetic fields (up to 6T) has not been satisfactorily overcome. To this end, it has been studied the introduction of several compounds in the matrix of magnesium diboride elements such as metal or carbon compounds. More recently, studies have turned to the use of ceramic processing techniques to improve the microstructure and better densification of the material. In this work the study of the addition of a new doping, 'C IND. 8''H IND. 18' hydrocarbon, is performed compared to other doping compounds that are extensively cited in the literature as silicon carbide and silicon oil. The process of sintering pellets ex situ is also investigated for all these additions in order to obtain denser material and therefore better performance in the transport properties. The used techniques include X ray diffraction, thermal analysis,... (Complete abstract click electronic access below)
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Rosas, Olvera Mariana. "KdpF et MgtR : deux peptides membranaires régulateurs de la virulence chez les mycobactéries et salmonelles." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT039.
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Les problèmes de santé publique causés par des bactéries comme Mycobacterium tuberculosis et Salmonella enterica sont amplifiés par l’émergence de souches multi-résistantes aux antibiotiques, d’où la nécessité de mettre au point rapidement de nouvelles stratégies antimicrobiennes. La découverte récente de peptides membranaires bactériens qui ont la propriété de réguler des partenaires protéiques membranaires impliqués dans la virulence bactérienne permet d’envisager des stratégies « anti-virulence » innovantes.Mon travail a porté sur l’étude de deux peptides membranaires, KdpF et MgtR, chez M. bovis BCG et S. typhimurium, qui sont des pathogènes intracellulaires capable de survivre dans les macrophages. La surexpression de KdpF chez M. bovis BCG et de MgtR chez S. typhimurium entraîne une diminution de la survie bactérienne dans les macrophages et je me suis attachée à en comprendre la mécanistique et à étudier l’effet biologique de peptides KdpF et MgtR synthétiques.Ces travaux m’ont permis de mettre en évidence que les peptides KdpF endogène et synthétique augmentent la sensibilité des bactéries au stress azoté. Nous proposons que cela soit en lien avec la déstabilisation de la nitrate réductase. De plus et pour la première fois, j’ai démontré que le peptide synthétique KdpF est biologiquement actif et mime les propriétés anti-virulence du peptide endogène KdpF dans les macrophages.J’ai montré que le peptide synthétique MgtR réduit la survie intra-macrophagique de S. typhimurium, et j’ai identifié un peptide variant ayant une action encore plus efficace. Ces deux peptides entraînent une diminution du taux de plusieurs protéines de la membrane interne, dont certaines sont des facteurs de virulence reconnus.De plus, j’ai contribué à une étude visant à tester l’effet anti-virulence du peptide MgtR de Salmonella chez les mycobactéries. En utilisant un système hétérologue, j’ai montré que l’ajout du peptide synthétique MgtR peut empêcher la dimérisation de la protéine MgtC de M. tuberculosis et également favoriser sa déstabilisation.En conclusion, l’ensemble de mes résultats permet de mieux comprendre le mécanisme d’action des peptides membranaires KdpF et MgtR et montre que les peptides synthétiques KdpF et MgtR possèdent des propriétés anti-virulence prometteuses, point essentiel pour valider la pertinence de ces molécules dans le cadre de stratégies innovantes alternatives ou complémentaires aux antibiotiquesThe public health problems caused by bacteria such as Mycobacterium tuberculosis and Salmonella enterica are amplified by the emergence of multi-drug resistant strains, leading to the demand of new antimicrobial strategies. The recent discovery of bacterial membrane peptides that have regulatory effects on membrane protein involved in bacterial virulence makes it possible to envisage innovative "anti-virulence" strategies.My work was focused on the study of two membrane peptides, KdpF and MgtR, in M. bovis BCG and S. typhimurium respectively, which are intracellular pathogens capable of surviving in macrophages. Overexpression of KdpF in M. bovis BCG and MgtR in S. typhimurium, has already been reported to decrease bacterial survival in macrophages. Therefore, I focused on the study of mechanism and biological effect of synthetic KdpF and MgtR peptides.This work allowed me to conclude that endogenous and synthetic KdpF peptides increase the sensitivity of bacteria to nitrosative stress. I propose that this is related to the destabilization of the enzyme nitrate reductase. In addition and for the first time, I have demonstrated that the synthetic KdpF peptide is biologically active and mimics the anti-virulence properties of the endogenous KdpF peptide in macrophages.In the next part of my study, I have shown that the synthetic MgtR peptide reduces the intramacrophage survival of S. typhimurium and I have identified a variant peptide with even stronger action. These two peptides cause a decrease in the level of several proteins of the inner membrane, some of which are recognized as virulence factors.In addition to that, I tested the anti-virulence effect of Salmonella MgtR peptide in mycobacteria. Using a heterologous system, I have shown that the addition of the synthetic MgtR peptide can prevent the dimerization of M. tuberculosis MgtC protein and also promote its destabilization.In conclusion, all my results provide a better understanding of the mechanism of action of KdpF and MgtR membrane peptides and show that the synthetic peptides KdpF and MgtR have promising anti-virulence properties. This is an essential factor to validate the relevance of these molecules as part of innovative, alternative or complementary strategies to antibiotics
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Shcherbakova, Olga V. "Development of MgB₂-xCx superconductors and understanding their electromagnetic behaviour." Institute for Superconducting and Electronic Materials - Faculty of Engineering, 2008. http://ro.uow.edu.au/theses/11.
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Discovered in 2001, magnesium diboride (MgB2) is the latest superconductor suitable for large scale applications (magnetic resonance imaging systems (MRI), fault current limiters (FCL), high-field magnets). Compared to other metallic superconductors like NbTi (Tc = 9 K) and Nb3Sn (Tc = 18 K), it has the advantage of a higher critical temperature (Tc = 39 K), which enables its application at the temperature of 20 K and, hence, significantly reduces the cost of the cooling system. This, together with the abundance of the magnesium and boron raw materials, as well as the relatively simple fabrication of MgB2 wires and tapes, has motivated the active investigation and study of this superconductor by many research groups all over the world. As a result, a significant breakthrough for application of MgB2 conductors at high fields has been made with introduction of carbon into the crystal lattice of MgB2 via chemical doping. The main focus of this work was on the study of the microstructural and superconducting properties of MgB2-xCx superconductors and establishing correlations between them. To obtain MgB2-x Cx compounds with different characteristics, various C-based doping materials and processing parameters were employed. The systematic study of the microstructural and superconducting properties of MgB2-x Cx samples conducted in this work allowed us: (i) to predict suitable dopants for MgB2; (ii) to improve chemical doping by carbon; (iii) to identify the relevant negative microstructural factors and estimate their effects on limitation of the current-carrying ability in MgB2-xCx samples. The results described in this work can be used as a guide for the achievement of the characteristics required for practical applications of MgB2 superconductors. Investigation of the properties of MgB2-xCx superconductors as a function of the processing parameters showed that the doping level, sintering temperature, and cooling time control the density of pinning centers in MgB2-xCx, and affect the connectivity of grains and transparency of grain boundaries to current flow. Analysis of the pinning mechanism in the samples studied has led to establishing that the dominant pinning is on grain boundaries in the pure MgB2 samples, and on grain boundaries and crystal lattice defects in the MgB2-xCx samples. To demonstrate the effect of the pinning environment on the current-carrying ability in MgB2-xCx superconductors, a comparative study of the microstructural and superconducting properties for pure, nano SiC-, and C-doped MgB2 wires was carried out. In both SiC- and C-doped samples carbon substitution into the MgB2 crystal lattice results in the enhancement of the upper critical field, Bc2. However, it was revealed that the presence of SiC dopant allowed carbon substitution and MgB2 formation to take place simultaneously at low temperatures. Therefore, the microstructure of this SiC-doped sample assures maximal density of pinning centers (large number of grain boundaries, i.e. small grain sizes, and crystal lattice defects) and enhances pinning. These factors (higher Bc2 value and stronger pinning) are responsible for the superior enhancement in critical current density at relatively high fields in the SiC-doped sample. In contrast, for C-doping, higher processing temperatures are required for generation of a dense network of crystal lattice defects. In this case, the microstructure consists of larger grains, and the pinning on smaller number of grain boundaries becomes weaker, reducing the total pinning force and critical current density. An important outcome of this study was the establishment of the dual reaction model (simultaneous formation of MgB2 compound and C substitution into the lattice), which enables us to predict desirable dopants for enhancing the properties of MgB2. These should be C-based compounds which decompose, producing highly reactive C at temperatures below the temperature of MgB2 formation. Ideally, dopants should be homogeneously distributed within host the Mg and B powders and not contaminate grain boundaries in formed MgB2. The liquid mixing approach, a new advanced and at the same time simplified approach to chemical doping of MgB2 superconductor with carbon, was found to partially fulfill these requirements. Carbohydrates (sugar and malic acid) and polycarbosilane (a polymer analog to nano SiC-doping) were employed as doping materials. Liquid mixing has been shown to coat each individual nano sized boron powder particle with a nano-layer of amorphous carbon. Fresh unpassivated carbon extracted from carbohydrates or polycarbosilane easily incorporates itself into the MgB2 crystal lattice. This enhanced incorporation promoted by the maximal reaction surface assured by coating generates microstructure with a dense network of pinning sites and results in significant improvement of the superconducting properties in MgB2-xCx material. The results observed suggest that sugar as a dopant exhibits a stronger potential for practical application of MgB2 superconductor in the high field region than nano carbon doping. Similarly, stronger enhancement of superconducting properties was observed in polycarbosilane-doped MgB2 compared to nano SiC doping. The latter was ascribed to the formation of a microstructure with Mg2Si impurity phases mainly distributed within superconducting MgB2 grains. In this case, transparency of grain boundaries was likely improved, which resulted in the observed enhancement of critical current density over the entire field range. Systematic analysis of the microstructures and superconducting properties of sugar-, malic acid-, and polycarbosilane-doped MgB2 samples demonstrated that the critical current density was also significantly affected by the microstructural properties in the low field region. The results observed led to the development of a model, which allowed us to estimate the level of critical current density (Jc) limitation due to the microstructural features of pure and C-doped MgB2 samples. This model is based on the identification of individual contributions by various defects to critical current density limitation. These defects in the MgB2 microstructure include porosity and non-superconducting phase inclusions (so-called “geometrical” defects), as well as the connectivity and transparency of grain boundaries. The results observed showed that a higher level of “geometrical” defects results in stronger limitation of critical current flow through the sample and lower measured Jc values. The elimination of the “geometrical” defects would result in critical current densities that are a factor of 1.5 - 2 higher than currently measured values. The role of grain boundaries connectivity was found to be even more dramatic. For samples with fully connected grains, the estimated critical current densities were about one order of magnitude higher than the measured values. Moreover, the results of analysis showed that the low field Jc values are mainly determined by the connectivity and transparency of grain boundaries, while in field Jc(Ba) performance is affected by these defects in the microstructure to a lesser extent, and its behaviour is mainly determined by the pinning environment in the samples. It also was observed that while a denser pinning network favors in field Jc(Ba) behaviour, this results in reduction of grain boundary transparency and more pronounced critical current density limitation in the low field region.
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Chen, Soo Kien. "Clinical modification of MgB₂ for optimisation of critical current density." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597515.
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This work focuses on the optimisation of critical current density, Jc of bulk polycrystalline MgB2 via studying the influence of boron precursor powder, nominal Mg non-stoichiometry and finally by chemical modification. On the influence of the nature of the boron precursor on the superconducting properties of MgB2, Jc’s for the MgB2 made from high purity amorphous boron are at least a factor of three higher than typical values measured for standard MgB2 samples made from amorphous precursors. Two possible mechanisms are proposed to account for this difference. Samples made from crystalline boron powders have around an order of magnitude lower Jc’s compared to those made from amorphous precursors. X-ray, superconducting transition temperature, Tc and resistivity studies indicate that this is as a result of reduced current cross section due to the formation of (Mg)B-O phases. The samples made from amorphous B contain far fewer Mg(B)-O phases than crystalline B despite the fact that the amorphous B contains more B2O3. The different reactivity rates of the precursor powders can account for this anomaly. The influence of Mg content was investigated in a series of samples with systematic variation of nominal Mg non-stoichiometry. Jc(H) was found to be influenced significantly with variation of Mg while leaving Tc unchanged. Mg deficient samples show higher degree of disorder as inferred from the Raman spectroscopy data. The Mg deficient samples also show higher Hirr and Hc2 compared to samples with reduced Mg vacancy as the Mg nominal content increases. Based on the results from Raman spectroscopy studies, XRD, resistivity and normalised Jc(H), a phase diagram for MgxB2 – Mg is proposed. For chemical modification, different reaction conditions and amount of Cu, GaN and Dy2O3 additions into MgB2 during the in situ reaction enhance Jc at 6k and 20K up to 5T without changing Tc appreciably compared to undoped samples whereas ZrO2 additions combined with ball milling degrade Tc and Jc. Attempt of Cu substitution in varying annealing temperatures does not result in doping of lattice structure. The optimisation of Jc is found to rest on the competing effects between the improved grain connectivity and MgB2 phase formation versus Mg-Cu secondary phase formation which decreases Jc. Additions of Ga in the form of GaN into MgB2 produce plate-like grains and enhance Jc. Dy2O3 additions result in the highest Jc at both 6K and 20K up to 5T among the additives studied. The best sample (only 0.5 wt.% Dy2O3) had a Jc ~ 6.5 X 105 Acm-2 at 6K, 1T and 3.5 x 105 Acm-2 at 20K, 1T, around a factor of 4 higher compared to the best pure sample, and equivalent to hot-pressed or nano-Si added MgB2 at ≤ 1T. Even distributions of nano-scale precipitates of DyB4 and MgO were observed within the grains. The room temperature resistivity decreased with Dy2O3 indicative of improved grain connectivity.
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Bartolleti, Flávia. "Avaliação da relação genética e perfil de sensibilidade de Klebsiella pneumoniae resistentes à polimixina B." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-21122016-103009/.
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INTRODUÇÃO: O aumento da incidência de infecções causadas por bactérias resistentes a múltiplos antimicrobianos limita cada vez mais as opções terapêuticas, dificultando o tratamento e aumentando os índices de morbidade e mortalidade, além dos gastos em saúde. Ao longo dos últimos cinco anos, essa limitação tem levado ao reestabelecimento do uso de antimicrobianos consideradas ultrapassados, como as polimixinas. Este grupo passou a ser utilizado com cada vez mais frequência no tratamento de infecções causadas por microrganismos gram-negativos resistentes aos carbapenêmicos. As enterobactérias, em particular a espécie Klebsiella pneumoniae, tem apresentado frequentemente esse perfil, porém, a resistência à polimixinas têm sido relatada, eliminando essa importante alternativa terapêutica. Apesar da importância do tema, são escassas as publicações sobre frequência de resistência às polimixinas em K. pneumoniae e a relação clonal entre isolados resistentes à polimixina B no Brasil. OBJETIVOS: Avaliar a relação genética, perfil de sensibilidade antimicrobiana e mecanismos de resistência às polimixinas em K. pneumoniae. MATERIAIS E MÉTODOS: A execução deste trabalho dividiu-se em duas partes principais: (i) levantamento de dados de culturas positivas para K. pneumoniae da rotina de pacientes hospitalizados em instituições atendidas pelo serviço de análises clínicas do Fleury Medicina e Saúde; (ii) confirmação das concentrações inibitórias mínimas (CIM) para polimixina B, avaliação da relação clonal por eletroforese em campos pulsados (PFGE),e sequenciamento de múltiplos loci (MLST), avaliação da integridade do gene mgrB e da presença do gene mcr-1 por PCR entre isolados resistentes à polimixina B e aos carbapenêmicos (CPRKp). RESULTADOS e CONCLUSÕES: Na análise de 3.085 isolados de K. pneumoniae obtidos de pacientes internados em 11 hospitais da Grande São Paulo entre os anos de 2011 e 2015, foi evidenciado um aumento estatisticamente significativo na resistência aos carbapenêmicos de 6,8% em 2011 para 35,5% em 2015. Em 2015, KPC foi detectada em 96,2% dos isolados resistentes aos carbapenêmicos. A distribuição das concentrações inibitórias mínimas de polimixina B entre todos os isolados de K. pneumoniae evidenciou uma distribuição bimodal com a CIM de 2 mg/L como o valor de ponto de corte para a susceptibilidade à polimixina B; assim, 3,6% do número total de isolados sensíveis aos carbapenêmicos foram interpretados como resistentes enquanto essa proporção foi de 22,5% entre as resistentes aos carbapenêmicos (CRKp). Entre esses últimos isolados também houve um aumento estatisticamente significativo na tendência anual de resistência à polimixina B, de 0% em 2011 para 27,1% em 2015. Estas taxas variaram de 0,7% em 2011 para 3,9% até junho de 2014 entre os sensíveis aos carbapenêmicos. Entre os antimicrobianos alternativos, a amicacina e a tigeciclina foram os compostos mais ativos. A análise por PFGE de 60 isolados de CPRKp obtidos de pacientes distintos nos anos de 2014 e 2015 evidenciou dois grandes grupos clonais: CPRKp1 e CPRKp2, os quais segundo a análise por MLST pertencem, respectivamente, aos grupos ST11 e ST437, ambos do complexo clonal 258. Foi observado o mesmo grupo ST entre isolados obtidos dentro de um mesmo hospital e também entre diferentes hospitais, públicos e privados. O mecanismo de resistência mais comum entre os isolados de CPRKp foi a presença de sequências de inserção interrompendo o gene mgrB. O gene mcr-1 não foi detectado em nenhum dos isolados.INTRODUCTION: The increasing incidence of infections caused by bacteria resistant to multiple antimicrobials increasingly limits therapeutic options, making treatment difficult and increasing the morbidity and mortality and health spending. Over the past five years, this limitation has led to the reestablishment of the use of antimicrobials deemed outdated, such as polymyxins. This group is now used with increasing frequency to treat infections caused by carbapenem-resistant gram-negative microorganisms. Enterobacteria, especially Klebsiella pneumoniae, have often presented this profile, however, resistance to polymyxins have been also reported, eliminating this important therapeutic alternative. Despite the importance of this issue, the publications are scarce on the polymyxins resistance frequency in K. pneumoniae and clonal relationship among isolates resistant to polymyxin B in Brazil. OBJECTIVES: To evaluate the genetic relationship, antimicrobial susceptibility profile and polymyxin B resistance mechanisms in K. pneumoniae. MATERIALS AND METHODS: The execution of this work was divided into two main parts: (i) survey data on routine cultures positive for K. pneumoniae from patients hospitalized in institutions attended by the clinical analysis service of Fleury Health and Medicine; (ii) confirmation of to polymyxin B minimum inhibitory concentrations (MIC), evaluation of clonal relationship by electrophoresis pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), evaluation of the integrity of the mgrB gene and the presence of mcr-1 gene by PCR among isolates resistant to polymyxin B and carbapenems (CPRKp). RESULTS AND CONCLUSIONS: The analysis of 3,085 K. pneumoniae isolates obtained from inpatients from 11 hospitals in the São Paulo urban area between 2011 and 2015, has shown a statistically significant increase in carbapenem resistance from 6.8% in 2011 to 35.5% in 2015. In 2015, KPC was detected in 96.2% of isolates resistant to carbapenems. The polymyxin B MIC distribution of all Klebsiella pneumoniae showed a bimodal distribution with the MIC of 2 mg/L as the cutoff value for polymyxin B susceptibility; thus, 3.6% of the total number of isolates susceptible to carbapenems were interpreted as resistant while this proportion was 22.5% among carbapenem-resistant isolates (CRKp). Among these isolates there was also a statistically significant increase in the annual trend of polymyxin B resistance, from 0% in 2011 to 27.1% in 2015. These rates ranged from 0.7% in 2011 to 3.9% by June 2014 between carbapenem-susceptible isolates. Among alternative antimicrobials, amikacin and tigecycline were the most active compounds. The analysis by PFGE of 60 CPRKp isolates obtained from different patients in the years 2014 and 2015 showed two major clonal groups: CPRKp1 and CPRKp2, which according to the analysis by MLST belong respectively to ST11 and ST437 groups, both from clonal complex 258. We observed the same ST group of isolates obtained within a hospital and between different public and private hospitals. The most common mechanism of polymyxin B resistance among CPRKp isolates was the presence of insertion sequences interrupting the mgrB gene. The mcr-1 gene was not detected in any of the isolates.
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Bhatia, Mohit. "MgB2 superconductors: processing, characterization and enhancement of critical fields." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1190055943.
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Yao, Qiwen. "Study of synthesis, structures and superconducting properties of magnesium diboride MgB₂ material." Access electonically, 2004. http://ro.uow.edu.au/theses/404.
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Alix, Eric. "Régulation, fonction et polymorphisme de MgtC : un facteur de virulence conservé chez différentes bactéries pathogènes intracellulaires." Montpellier 2, 2008. http://www.theses.fr/2008MON20028.
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MgtC est un facteur de virulence conservé chez différentes bactéries pathogènes intracellulaires, telles que Salmonella enterica serovar Typhimurium (S. Typhimurium), Mycobacterium tuberculosis, Brucella suis et Burkholderia cenocepacia. Un mutant ΔmgtC de ces différentes espèces est atténué pour la réplication dans les macrophages et pour la croissance dans un milieu de culture carencé en ions Mg2+. J'ai étudié la fonction, la régulation et le polymorphisme de MgtC, dans le but de comprendre son implication dans la virulence. L'analyse de mutants ponctuels de la protéine MgtC de S. Typhimurium au niveau de résidus conservés montre que la fonction de MgtC pour la réplication dans les macrophages peut être dissociée de sa fonction liée à la croissance dans un milieu pauvre en Mg2+. Ces résultats nous renseignent sur les conditions environnementales rencontrées par S. Typhimurium dans le macrophage. Le résultat principal de cette thèse concerne la découverte d'un nouveau mécanisme de régulation post-traductionnelle faisant intervenir un peptide membranaire. La stabilité de la protéine MgtC de S. Typhimurium est en effet régulée par un peptide membranaire de 30 acides aminés, MgtR, qui interagit directement avec MgtC pour induire sa dégradation par la protéase FtsH. Ce résultat souligne l'importance, ignorée jusqu'à présent, des peptides membranaires fonctionnels chez les bactéries. Enfin, l'étude du polymorphisme de mgtC chez M. Tuberculosis a révélé un polymorphisme nucléotidique spécifiquement associé à la famille Haarlem, constituant un marqueur moléculaire de cette famille. L'ensemble de ces travaux confirme que MgtC est une cible intéressante dans le cadre d'une stratégie anti-virulence, et identifie un antagoniste potentiel de cette cible, MgtRMgtC is a virulence factor shared by several intracellular pathogenic bacteria, including Salmonella enterica serovar Typhimurium (S. Typhimurium), Mycobacterium tuberculosis, Brucella suis and Burkholderia cenocepacia. The ΔmgtC mutants of these species are attenuated for replication in macrophages and for growth in a culture medium depleted in Mg2+. In this work, I studied function, regulation and polymorphism of MgtC, in order to get insight into its role in virulence. Analysis of point mutations in S. Typhimurium MgtC protein on conserved residues showed that MgtC function for intramacrophage replication can be dissociated from its function for growth in a Mg2+-depleted medium. This result is interesting for the comprehension of the currently unknown conditions undergone by S. Typhimurium in the phagosome. The major result of this thesis concerns the discovery of a new post-translational regulation mechanism. Indeed, S. Typhimurium MgtC stability is regulated by a 30 aminoacids transmembrane peptide, MgtR, that directly interacts with MgtC to induce its degradation by FtsH protease. This finding highlights the misestimated importance of transmembrane peptides in bacteria. Finally, I studied mgtC polymorphism in M. Tuberculosis, and identified a single nucleotide polymorphism specifically linked to Haarlem genotype, that could be used as an epidemiological marker of this genotype. Altogether, these results confirm MgtC as an interesting target in an antivirulence strategy, and identify MgtR as a potential antagonist of MgtC
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JACQUEMARD, PAUL. "Fluid field analysis on a flexible combustor for a hybrid Solar / Brayton system : A numerical study." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287853.
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Recent improvements to concentrating solar dish systems lead to further focus on hybridization systems for small-scale power generation applications. Variability of the solar load creates new requirements for combustion systems. This thesis presents a CFD simulation of the air flow inside a new combustor design for the combination of an impinging air solar receiver and a MGT. The system consists of a LPP tubular combustor with radial main swirler and central pilot burner. Focus is made on the pressure loss at the downstream impinging cooling wall for appropriate flow distribution between reacting and bypass air. Heat transfer is not studied due to lack of time. A fully-hexahedral multi-zones mesh of the system without fuel injection has been generated with Ansys ICEM software, making use of its O-grid capabilities. A realizable k-epsilon model is used for turbulence modelling. Several impinging hole’s diameters are studied to find the right balance between the two streams. Streamlines are also observed to confirm the location of recirculation zones and recommend design improvements.Nya förbättringar av koncentrerade solskålssystem leder till ytterligare fokus på hybridsystem för småskaliga applikationer för elproduktion. Ojämn solstrålning skapar nya krav på förbränningssystem. Detta examensarbete presenterar en CFD-simulering av luftflödet i en ny förbränningsdesign för en kombination av en solfångare med forcerad konvektionskylning och en mikrogasturbin (MGT). Systemet består av en LPP-rörbrännare med radiellt virvelsystem och central pilotbrännare. Studien fokuserar på tryckförlusten vid slaghålsväggen, som används för kylning vid förbränning, och lämplig flödesfördelning mellan reagerande- och förbigående flöde. Värmeöverföring studeras inte på grund av tidsbrist. Ett helt sexkantigt nät med flera zoner i systemet utan bränsleinsprutning har genererats med Ansys ICEM-programvara som använder O-nätfunktioner. En realiserbar k-epsilon-modell används för turbulensmodellering. Flera slaghålsdiametrar studeras för att hitta rätt balans mellan de två strömmarna. Även strömlinjer observeras för att bekräfta placeringen av återcirkulationszoner och kunna rekommendera förbättringar av designen.
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Harding, Alexander Stanley. "Single Event Mitigation for Aurora Protocol Based MGT FPGA Designs in Space Environments." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4117.
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This work has extended an existing Aurora protocol for high-speed serial I/O between FPGAs to provide greater fault recovery in the presence of high-energy radiation. To improve on the Aurora protocol, additional resets that affect larger portions of the system were used. Detection for additional error modes that occurred but were not detected by the Aurora protocol was designed. Radiation testing was performed on the Aurora protocol with the additional mitigation hardware. The test gathered large amounts of data on the various error modes of the Aurora protocol and how the additional mitigation circuitry affected the system. The test results showed that the addition of the recovery circuitry greatly enhanced the Aurora protocol's ability to recover from errors. The recovery circuit recovered from all but 0.01% of errors that the Aurora protocol could not. The recovery circuit further increased the availability of the transmission link by proactively applying resets at much shorter intervals than used in previous testing. This quick recovery caused the recovery mechanism to fix some errors that may have recovered automatically with enough time. However, the system still showed an increase in performance, and unrecoverable errors were reduced 100x. The estimated unrecoverable error rate of the system is 5.9E-07 in geosynchronous orbit. The bit error rate of the enhanced system was 8.47754E-015, an order of magnitude improvement.
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Moussouni, Malika. "Facteurs bactériens impliqués dans la survie intramacrophagique de Pseudomonas aeruginosa et recherche d’inhibiteurs spécifiques : du modèle expérimental cellulaire au modèle vertébré Danio rerio." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTT003.
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Pseudomonas aeruginosa, fait partie des bactéries pathogènes classées par l’OMS «hautement prioritaires», résistantes aux antibiotiques et pour lesquelles il est urgent d’identifier de nouveaux moyens de lutte. P. aeruginosa, responsable d’infections aiguës ou chroniques, est impliqué dans des infections nosocomiales et est également le principal pathogène responsable de la morbidité et la mortalité des patients atteints de mucoviscidose, maladie génétique à transmission récessive, liée à des mutations du gène cftr. Le macrophage est en première ligne de la défense immunitaire innée. Le rôle dans l’infection de la capacité de P. aeruginosa à résister à l’action bactéricide des macrophages est un aspect mal connu, que ce soit dans le contexte de la mucoviscidose ou pas. Des facteurs de virulence comme MgtC et OprF, ont récemment été identifiés comme important dans la survie intramacrophagique de P. aeruginosa. Notre projet a pour objectif principal de mieux comprendre le rôle de ces facteurs dans l’établissement de l’infection à P. aeruginosa, de tester la contribution du canal CFTR à ce niveau, et de développer une stratégie thérapeutique innovante. L’intérêt étant de mieux contrôler l’infection, nous proposons de développer une nouvelle stratégie, en complément de l’antibiothérapie, qui vise à limiter la capacité de P. aeruginosa à survivre dans le macrophage. Cette approche se base sur la cible MgtC et un inhibiteur naturel MgtR. Nous avons testé ici pour la première fois, l’effet d’un peptide synthétique MgtR sur P. aeruginosa. MgtR réduit la survie bactérienne dans les macrophages, via son effet sur la protéine MgtC, validant ainsi, l’effet biologique du peptide synthétique. Cette approche antivirulence est couplée à une approche structurale, afin de caractériser l’interaction MgtC/MgtR d’un point de vue moléculaire et d’étudier l’effet de MgtR sur la dimérisation de MgtC. Ceci pourrait permettre in fine d’optimiser le peptide MgtR afin de pouvoir le tester dans un modèle animal (des études préliminaires dans l’embryon de poisson-zèbre s’étant avérées infructueuses). J’ai de plus contribué à une étude visant à caractériser les facteurs bactériens de P. aeruginosa impliqués dans le stade intramacrophagique. Ces travaux ont montré l’implication de MgtC et OprF dans l’expression du SST3, lui-même responsable d’un phénomène de lyse des macrophages par les bactéries intracellulaires. L’utilisation du mutant oprF comme « indicateur » du rôle intramacrophagique in vivo, nous a permis de montrer l’importance de l’action bactéricide du macrophage (e.g. l’acidification du phagosome) dans le contrôle de l’infection à P. aeruginosa, dans des macrophages en culture et dans l’embryon de poisson-zèbre. Ce modèle vertébré est pertinent non seulement pour l’étude de l’infection à P. aeruginosa, mais également pour l’implication du CFTR. Les embryons cftr-/- semblent être particulièrement susceptibles à l’infection par P. aeruginosa, et ce modèle pourrait permettre de déterminer la contribution spécifique du CFTR à l’action bactéricide du macrophage. En conclusion, une meilleure compréhension de la phase intramacrophagique de P. aeruginosa et des facteurs bactériens impliqués, pourraient permettre de mieux contrôler l’infection à P. aeruginosaThe increased number of antibiotic-resistant bacteria is a real challenge for medical research. WHO has published a list of very high priority pathogens, which includes Pseudomonas aeruginosa, a bacterium responsible for acute and chronic infections. P. aeruginosa is involved in nosocomial infections and is also the main pathogen responsible of the morbidity and mortality of patients with cystic fibrosis, a genetic disorder caused by mutations in the cftr gene.The macrophage is in the first line of the innate immune defense. The role during infection of the ability of P. aeruginosa to resist to the bactericidal action of macrophages is poorly understood, both in the context of cystic fibrosis or in normal conditions. Virulence factors such as MgtC and OprF have been recently identified as important in the intramacrophage survival of P. aeruginosa. The main objective of our project is to better understand the role of these factors in the establishment of P. aeruginosa infection, to test the contribution of the CFTR channel at this stage, and to develop innovative therapeutic strategy.Since it is important to better control the infection, we propose here to develop a new strategy, in addition to antibiotic therapy, which aims to limit the ability of P. aeruginosa to survive within macrophages. This approach is based on the MgtC target and a natural MgtR inhibitor.We have tested for the first time the effect of MgtR synthetic peptide on P. aeruginosa. MgtR reduces bacterial survival in macrophages, through its action on the MgtC protein, thus validating the biological effect of the synthetic peptide. This antivirulence strategy is combined with a structural approach, to characterize the MgtC/MgtR interaction from a molecular point of view and to study the effect of MgtR on MgtC dimerization. This could ultimately lead to optimize the MgtR peptide in order to test it in an animal model (preliminary studies in the embryo of zebrafish were inconclusive).In addition, I contributed in a study to characterize the bacterial factors involved in the intramacrophage stage of P. aeruginosa. This work revealed the involvement of MgtC and OprF in the expression of the T3SS, itself responsible for a lysis of macrophages by intracellular bacteria. The use of oprF mutant as an "indicator" of the intramacrophage role in vivo, allowed us to show the importance of bactericidal action of macrophage (e.g. phagosomal acidification) in the control of P. aeruginosa infection, both in cultured macrophages and in zebrafish embryo. This vertebrate model is relevant for the study of P. aeruginosa infection, but also for the involvement of CFTR. cftr-/- embryos appear to be highly susceptible to P. aeruginosa infection, and this model could determine the specific contribution of CFTR to the bactericidal action of macrophage.In conclusion, a better understanding of the intramacrophage stage of P. aeruginosa and the bacterial factors involved, may provide a better control of P. aeruginosa infection
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Xi, Yiheng. "A cross-level investigation of the effects of leadership style of school principals on teachers' satisfaction and organizational citizenship behavior : the mediating role of trust-in-principal /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202005%20XI.
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Song, Jiwen. "Organizational control mechanisms and employee outcomes : processes and configuration /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202005%20SONG.
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Yao, Kun. "Preventing a crime? exploring the impact of corporate governance on corporate illegal behavior in China /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202006%20YAO.
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Yang, Jing Yu. "Failure-induced interorganizational learning : entry and survival analysis of Japanese firms in China, 1980-2000 /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202006%20YANG.
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Liang, Jian. "Voice behavior in organizations : scale development, psychological mechanisms, and cross-level modeling /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202007%20LIANG.
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Huang, Guohua. "Workplace self-concept : a new conceptualization of self-concept in organizations /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202007%20HUANG.
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Yang, Zhen. "The inter-dependence model revisited : the development of modern banks and the effects on the evolution of piao-hao firms in the context of the Shanghai banking industry, 1847-1940 /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202008%20YANG.
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Tang, Yi. "A bird known by its note : identity legitimacy, network dynamics, and actor performance in the Hong Kong film industry, 1970-1997 /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202009%20TANG.
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Wang, Hui. "CEO leadership attributes and organizational effectiveness : the role of situational uncertainty and organizational culture /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202002%20WANG.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 106-122). Also available in electronic version. Access restricted to campus users.
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Zhong, Jing. "Foreign R & D activities in China : general trends and entry mode choice /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202002%20ZHONG.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 65-75). Also available in electronic version. Access restricted to campus users.
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Yue, Rui. "Contagion or competition : partner abandonment in Korean television advertising industry, 1985-1996 /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202004%20YUE.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 68-81). Also available in electronic version. Access restricted to campus users.
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Ling, Jiayin. "A persistent-mode MgB₂ 0.5-T/240-mm solid-nitrogen-cooled magnet for MRI." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103484.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 137-140).
Magnetic resonance imaging (MRI) has become one of the major noninvasive diagnostic imaging tools today. The annual $5-billion market drives magnet engineers to develop advanced and innovative, high-quality, low-cost, easy-to-operate MRI magnets. Because superconductors carry more than 100 times higher current density than copper, while generating no Joule heat, they are the only practical choice for diagnostic MRI magnets with field strengths above 1 T. A low-temperature superconductor of niobium titanium (NbTi) with a critical temperature of 9.8 K stands out among other superconductors because of its excellent mechanical properties, adequate electromagnetic properties and low manufacturing cost. Since the MRI magnet became available in the 1970s, most commercial superconducting MRI magnets have been of NbTi wire and operated in liquid helium bath at 4.2 K. Nowadays, the sharply increasing price of helium has driven magnet designers to consider other superconductors with higher critical temperature for liquid-helium-free MRI magnets. Discovered in 2001, a new high-temperature superconductor of magnesium diboride (MgB₂) with a critical temperature of 39 K has spurred intensive R&D effort. A combination of high critical temperature, low manufacturing cost, and good in-field performance makes it viable competitor to NbTi and the basis for this thesis study. This dissertation, a result of the 0.5-T/240-mm MgB₂ magnet project performed in the Magnet Technology Division of the Francis Bitter Magnet Laboratory, includes design, construction and operation details of the magnet. Each key component of the magnet, i.e., superconducting joint and persistent-current switch (PCS), was designed and tested to evaluate its performance. Each PCS was designed also to absorb energy when protecting the magnet; its protection performance, as well as switching function, was evaluated before deployed. Each finished coil module was tested separately before assembled to complete the magnet. The magnet was operated in persistent-mode in the temperature range 10-15 K. During operation, this liquid-helium-free magnet was immersed in a volume of solid nitrogen that provided a needed thermal mass to the magnet. Temporal and spatial field homogeneity are critical parameters of MRI magnets. Thus actual fields were measured and compared with the designed values to demonstrate its acceptability to MRI application. Operation also examined and validated a protection technique deployed for this magnet, as protection is one of the vital requirements of the superconducting magnet.
by Jiayin Ling.
Ph. D.
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Spurrell, Jessica. "Thermal stability and current transfer in twisted-pair helium gas-cooled MgB₂ DC cables." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415831/.
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CERN’s helium gas-cooled, twisted-pair superconducting cable design, typically consisting of intercalated superconducting and copper (stabilising) tapes, is a novel design which offers low cable inductance for high-current DC power transmission. The electrical and thermal contacts between the copper and superconducting tapes, which are given by wrapping the complete ‘sandwich stack’ of tapes together in Kapton, are important parameters for current sharing, cryogenic stability and quench propagation. Observation of both IC and superconductor-stabiliser contact inhomogeneities due to the mechanical twisting process and the gas-cooling regime has shed light on overcoming the unique challenges these create in cable operation. Both an MgB2 twisted-pair cable assembly manufactured at CERN and a short-length single-sandwich strand made at the University of Southampton have been studied and a novel method for measuring contact resistance in situ has been designed and validated. Tests included measuring thermal runaway propagation velocity (vp) and minimum quench energy (MQE) plus long-period stability tests for the cable, along with characterisation of current transfer as well as contact resistance measurements between the superconductor and stabiliser layers in the single-sandwich. The results suggest that an optimised cable operation strategy may exist, being a trade-off between: high stabilisation with lower superconductor-stabiliser contact resistance; and fast propagation resulting in easier quench detection with higher superconductor-stabiliser contact resistance. The results of the investigations are relevant to both the CERN LHC High Luminosity upgrade and future superconducting power transmission projects.
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Yonamine, Anne Hitomi. "Estudo das propriedades supercondutoras e da microestrutura do supercondutor Mg'B IND. 2' puro e dopado com compostos de carbono /." Bauru : [s.n.], 2010. http://hdl.handle.net/11449/88449.
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Orientador: Dayse Iara dos SantosBanca: Raquel de Almeida Ribeiro
Banca: Durval Rodrigues Júnior
Resumo: Após a descoberta dos novos supercondutores óxidos no ano de 1986, houve uma intensa busca por outros materiais que apresentassem o fenômeno da supercondutividade. Dentre as novas descobertas encontra-se o diboreto de magnésio, material intermetálico cuja supercondutividade era desconhecida até 2001. Atualmente, este é considerado ter um grande potencial de aplicação real devido a sua simplicidade de confecção e ao baixo custo de resfriamento em "cryocoolers", visto que o fenômeno ocorre próximo de 39K. Ao longo de quase uma década muitas pesquisas foram realizadas com os objetivos de melhor conhecer o mecanismo de supercondutividade presente no material, assim como de aperfeiçoar a sua capacidade de suportar correntes em campos magnéticos altos e desta forma ampliar suas possibilidades de aplicação industrial. Hoje, encontra-se claro que o mecanismo que rege a supercondutividade no Mg'B IND. 2' é o mesmo descrito em 1958 por Bardeen, Cooper e Schriefer, na teoria BCS. Mas, por outro lado, as questões práticas permanecem incompletas, pois a queda da capacidade de conduzir supercorrente sob campos magnéticos altos (acima de 6T) ainda não foi superada satisfatoriamente. Com este objetivo, estuda-se a introdução de diversos compostos na matriz do diboreto de magnésio tais como elementos metálicos ou compostos de carbono. Mais recentemente, os estudos se voltaram para a utilização das técnicas de processamento cerâmico a fim de aperfeiçoar a microestrutura e melhor densificar o material. Neste trabalho o estudo da adição de um novo dopante, o hidrocarboneto 'C IND. 8''H IND. 18', é realizado comparativamente à outros dopantes extensivamente citados na literatura como o carbeto de silício e o óleo de silicone. O processo de sinterização de pastilhas ex situ é também investigado para todas... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: After the discovery of new superconducting oxides in the year 1986, there was an intense search for other materials that show the phenomenon of superconductivity. Among the new discoveries is magnesium diboride, an intermetallic material whose superconductivity was unknown until 2001. Currently, it is considered to have great potential for real application due to its easy fabrication and low cost cooling as cryocoolers, since the phenomenon occurs around 39K. For almost a decade surveys have been conducted with the objective of better understanding the mechanism of superconductivity in this material, as well as to improve its ability to withstand current in high magnetic fields and thus broaden their scope of industrial application. Today it is clear that the mechanism governing the superconductivity in Mg'B IND. 2' is the same as described in 1958 by Bardeen, Cooper and Schriefer, in the BCS theory. But on the other hand, practical issues remain incomplete, since the fall of the ability to conduct supercurrent in high magnetic fields (up to 6T) has not been satisfactorily overcome. To this end, it has been studied the introduction of several compounds in the matrix of magnesium diboride elements such as metal or carbon compounds. More recently, studies have turned to the use of ceramic processing techniques to improve the microstructure and better densification of the material. In this work the study of the addition of a new doping, 'C IND. 8''H IND. 18' hydrocarbon, is performed compared to other doping compounds that are extensively cited in the literature as silicon carbide and silicon oil. The process of sintering pellets ex situ is also investigated for all these additions in order to obtain denser material and therefore better performance in the transport properties. The used techniques include X ray diffraction, thermal analysis,... (Complete abstract click electronic access below)
Mestre
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Yelland, Edward Alexander. "Thermal and magnetic properties of YBa₂Cu₄O₈ and MgB₂ single crystals : an experimental study." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619591.
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Al-Hossain, Md Shahriar. "Study of superconducting and electromagnetic properties of un-doped and organic compound doped MgB₂ conductors." Access electronically, 2008. http://ro.uow.edu.au/theses/90.
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Rodrigues, Mikael Timóteo. "Acoplamento do modelo hidrológico MGB ao modelo atmosférico WRF visando estimar vazão na bacia do rio Paraíba do Meio AL/PE." Universidade Federal de Alagoas, 2012. http://repositorio.ufal.br/handle/riufal/904.
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Because of computational advances its evolution in relation to speed and memory capacity in recent years, along with adding the weather, the coupling between atmospheric and hydrological models has been the object of study in several studies in recent decades. The management of large river basins is determined by several variables, with the main system and the volume of river flows. Given volume water in a basin can be affected in different ways and many different factors, as the main factors having the variability in time and space of rainfall that produces immediate changes in the flow of a given system. As the results of large precipitation events directly affect the flow regimes, this work has as main objective the coupling of the hydrological model MGB - HPI with the WRF atmospheric model in an attempt to estimate flow in the basin of the Middle Rio Paraíba,. The rainfall data provided were simulated by WRF model and the observed rainfall and flow observed awarded by the National Water Agency - ANA, for 3 (three) station pluviometric and 4 (four) fluviometric respectively. The flow simulation was carried out hydrological rainfall-runoff model MGBIPH. Analyses were made in two steps: Kriging interpolation in KGM-normal rainfall and observed, and comparison between simulated hydrographs (rain predicted and observed) and observed (gauging stations). In the spatial correlation values were found in the order of 0.54 to 0.92 for normal rainfall and the observed one. The flow simulations with data generated by the WRF, were correlated with Pearson coefficients ranging between 0.46 and 0.56, representative values for this type of meteorological and hydrological study. Pierson coefficients obtained from simulations of flows of the observed data showed best correlations with values between 0.4 and 0.71. The coupling of hydrologic models (rainfall-runoff) and atmospheric models can be considered a useful technique to aid in prognosis prediction of extreme events. There is a perceived need for calibration of the atmospheric model, to become a real and effective tool in developing warning systems for flood basin of the Paraiba do Meio, among others, which will be analyzed laterFundação de Amparo a Pesquisa do Estado de Alagoas
Devido o avanço computacional e sua evolução em relação à velocidade e capacidade de memória nos últimos anos, juntamente com ascendência das previsões meteorológicas, o acoplamento entre modelos atmosféricos e hidrológicos tem sido o objeto de estudo em diversas pesquisas nas ultimas décadas. O gerenciamento de grandes bacias hidrográficas é determinado por inúmeras variáveis, sendo a principal, o regime e volume das vazões dos rios. Como os resultados de grandes eventos de precipitação pluviométrica afetam diretamente nos regimes de vazão, este trabalho tem como o objetivo principal o acoplamento do modelo hidrológico MGB IPH com o modelo Atmosférico WRF na geração de vazão na Bacia do Rio Paraíba do Meio (AL/PE). Os dados de precipitação prevista foram simulados pelo modelo WRF e os de precipitação observada e vazão observada concedidos pela Agencia Nacional de Águas ANA, para 3(três) postos pluviométricos e 4 (quatro) fluviométricos, respectivamente. A simulação de vazão foi realizada no modelo hidrológico precipitação vazão MGB-IPH. As análises foram feitas de duas etapas: interpolação por Krigagem-KGM das precipitações previstas e observadas; comparação entre hidrogramas simulados a partir dos dados de precipitações previstas e observadas. Na correlação espacial foram encontrados valores na ordem de 0,54 para as precipitações previstas e 0,92 para as observadas. As simulações de vazões com dados gerados pelo WRF apresentaram testes significativos, com coeficientes de Pearson variando entre 0,46 a 0,56, valores representativos para este tipo de estudo meteorológico e hidrológico. Os coeficientes de Piaerson obtidos através das simulações das vazões dos dados observados apresentaram correlações melhores com valores entre 0,4 a 0,71. O acoplamento de modelos hidrológicos (precipitação-vazão) e modelos atmosféricos podem ser considerados uma técnica útil no auxilio no prognóstico de vazões elevadas. Há uma necessidade eminente na calibração do modelo atmosférico, para que se torne uma ferramenta eficiente e real na elaboração de sistemas de alertas de cheias para bacia do Paraíba do Meio, dentre outras, que serão analisadas posteriormente
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HOWARD, JENNIFER DIXON. "DEVELOPMENT OF THE AUDITORY THALAMUS IN THE FERRET." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022254330.
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Wu, Yi Sun. "Fabrication of in-situ MgB₂ thin films on Al₂O₃ substrate using off-axis PLD technique." Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080917.103857/index.html.
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Ellsworth, Kevin M. "Understanding Design Requirements for Building Reliable, Space-Based FPGA MGT Systems Based on Radiation Test Results." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3159.
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Space-based computing applications often demand reliable, high-bandwidth communication systems. FPGAs with Mulit-Gigabit Transceivers (MGTs) provide an effective platform for such systems, but it is important that system designers understand the possible susceptibilities MGTs present to the system. Previous work has provided a foundation for understanding the susceptibility of raw FPGA MGTs but has fallen short of testing MGTs as part of a larger system. This work focuses on answering the questions MGT system designers need to know in order to build a reliable space-based MGT system. Two radiation tests were performed with a test architecture built on the Aurora protocol. These tests were specifically designed to discover system susceptibilities, and effective mechanisms for upset detection, recovery, and recovery detection. Test results reveal that the Aurora protocol serves as an effective basis for simple point-to-point communication for space-based systems but that some additional logic is necessary for high reliability. Particularly, additional upset detection and recovery mechanisms are necessary as well as additional status indicators. These additions are minimal, however, and not all are necessary depending on system requirements. The most susceptible part of the MGT system is the MGT tile components on the RX data path. Upsets to these components most often results in data corruption only and do not affect system operation or disrupt the communication link. Most other upsets which do disrupt normal system operation can be recovered automatically by the Aurora protocol with built-in mechanisms. Only 1% of observed events in testing required additional recovery mechanisms not supplied by Aurora. In addition to test data results, this work also provides suggestions for system designers based on various system requirements and a proposed MGT system design based on the Aurora protocol. The proposed system serves as an example to illustrate how test data can be used to guide the system design and determine system availability. With this knowledge designers are able to build reliable MGT systems for a variety of space-based systems.
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Tan, Kai Sin. "In situ resistometric phase formation analysis for Nb₃Sn, Nb₃Al and MgB₂ high critical current superconductors." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613914.
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Amin, Abdullah Al. "MULTISCALE MULTIPHYSICS THERMO-MECHANICAL MODELING OF AN MGB2 BASED CONDUCTION COOLED MRI MAGNET SYSTEM." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case151385068164148.
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Mhaya, Amel. "Analyse de la résistance aux antibiotiques chez les entérobactéries et étude d’une potentielle voie alternative aux traitements antibiotiques." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0420.
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L’augmentation des bactéries multirésistantes (BMR) aux antibiotiques est un problème majeur de santé publique. Le premier objectif de la thèse a été de rechercher la présence, peu documentée, de BMR dans la communauté en Tunisie. Pour la première fois, nous isolons une Klebsiella pneumoniae de séquence type ST147 productrice de la carbapénèmase NDM-1 dans ce milieu, à Sfax. Nos données indiquent aussi une proportion inhabituellement élevée (47%) d’Escherichia coli produisant deux ß-lactamases à spectre élargi. Quatre d’entre eux, avec CTX-M-15 et CTX-M-27, se divisent en 2 souches clonales de type A-ST617 (2 isolats) et B2-ST131 subclade C2 (2 isolats). Toutes contiennent un plasmide avec la même combinaison allélique, F31:A4:B1 ; suggérant une possible dissémination de ce réplicon. Lors d’une autre étude (milieu communautaire, Djerba), une souche clonale Eh22 d’Enterobacter hormaechei multirésistante, contenant un plasmide conjugatif IncHI2 de 300 kpb, a été isolée chez 2 patients sans lien épidémiologique apparent. Le plasmide a été séquencé et montre la présence de différents gènes de résistance incluant 4 gènes codant pour des ß-lactamases (blaTEM-1, blaDHA-1, blaCTX-M-3 et blaSHV-12). Dans une seconde partie, nous avons étudié chez Eh22 la résistance à la colistine (CS), antibiotique de dernier recours. Après avoir sélectionné un mutant in vitro, nous avons montré pour la première fois, chez Enterobacter spp, que cette résistance pouvait être due à une mutation dans le gène codant pour MgrB, un régulateur négatif du système à 2 composants PhoQP qui permet la synthèse de groupements cationiques sur le lipopolysaccharide, cible de la CS. Dans une dernière partie, des molécules de type bactériocines actives sur les BMR ont été recherchées à partir d’une collection de Bacillus thurengiensis. L’une d’elle, BUPM103, inhibe la croissance de BMR. Une analyse in silico a permis d’identifier le gène d’une potentielle bacthuricine F103 (11 kDa) qui a été produite dans E. coli. Le surnageant de sécrétion filtré a montré une activité d’inhibition de la croissance de K. pneumoniae multirésistante, contrairement au contrôle (sans sécrétion). Cette bacthuricine recombinante pourrait constituer une alternative thérapeutique pour le traitement des BMRThe increase of multidrug-resistant bacteria (BMR) to antibiotics is a major public health problem. The first objective of the thesis was to search for the presence of BMR, poorly documented in the community in Tunisia. For the first time, we isolate a Klebsiella pneumoniae belonging to the sequence type ST147 producing carbapenemase NDM-1 in this setting, at Sfax. Our data also indicate an unusually high proportion (47%) of Escherichia coli producing committally two extended-spectrum ß-lactamases. Four of them, with CTX-M-15 and CTX-M-27, are divided into 2 clonal strains of type A-ST617 (2 isolates) and B2-ST131 subclade C2 (2 isolates). All contain a plasmid with the same allelic combination, F31: A4: B1; suggesting a possible dissemination of this replicon. In another study (community-based, Djerba), a multiresistant clonal strain Eh22 of Enterobacter hormaechei, containing a 300 kbp conjugative plasmid of IncHI2, was isolated from 2 patients without apparent epidemiological relationship. The plasmid was sequenced and shows the presence of different resistance genes including 4 genes encoding β-lactamases (blaTEM-1, blaDHA-1, blaCTX-M-3 and blaSHV-12). In a second part, we studied in Eh22, the resistance to colistin (CS), antibiotic of last resort. After selection of an in vitro mutant, we showed for the first time, in Enterobacter spp, that this resistance can be due to a mutation in the gene encoding MgrB, a negative regulator of the 2-component PhoQP system that allows the synthesis of cationic residues on lipopolysaccharide, target of CS. In the last part, bacteriocins-like molecules active on BMR were searched in a collection of Bacillus thurengiensis. One of them, BUPM103, inhibits the growth of BMR. The gene for a potential bacthuricin F103 (11 kDa) was identified by an in silico analysis and it was produced in E. coli. The filtered supernatant secretion showed a growth inhibitory activity against a multiresistant K. pneumoniae, in contrast to control (without secretion). This recombinant bacthuricine could constitute a therapeutic alternative for the BMR treatment
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Juřica, Libor. "Rozhraní pro průmyslovou HD kameru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221114.
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Master´s thesis deals with creating circuit for receiving data from industrial camera. IP Core is designing for FPGA. Theoretical part of the work describes SDI interface, analysis of relevant SMPTE standards and specification of data format. The thesis include general characteristics of multigigabit transceivers. Practical part include VHDL description of SDI receiver. Thesis presents simulations of created circuit, implementation for real application and measurement results for signal transmission over slip ring.
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Hohloch, Martina [Verfasser], and Manfred [Akademischer Betreuer] Aigner. "Entwicklung und experimentelle Untersuchung eines Betriebskonzepts für die Mikrogasturbine in einem MGT/SOFC Hybridkraftwerk / Martina Hohloch ; Betreuer: Manfred Aigner." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1207836818/34.
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Li, Fuli. "A stress and coping perspective on creativity : a reward for creativity policy as a stressor in organizations = Cong ya li he ying dui de jiao du li jie chuang xin : zu zhi chuang xin jiang li zheng ce zuo wei yi zhong ya li yuan / Li Fuli." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-mgt-b30082468f.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Management in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 158-173)
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Chen, Zhenjiao. "Exploring the underlying mediating processes between intragroup conflict and team outcomes : a social information processing perspective /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-mgt-b30082353f.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Management in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 174-195)
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Zhang, Yi. "The relationship between organizational authority-control and employees' proactive behavior : the moderating role of individual proactive personality /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-mgt-b23750819f.pdf.
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Thesis (M.Phil.)--City University of Hong Kong, 2009."Submitted to Department of Management in partial fulfillment of the requirements for the degree of Master of Philosophy." Includes bibliographical references (leaves 117-147)
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Murad, Omar Rachid [UNESP]. "Propriedades de transporte eletrônico em filmes finos policristalinos de diboreto de magnésio (MGB IND.2') analisados pelo modelo de Bloch-Grüneisen." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/88505.
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murad_or_me_bauru.pdf: 1607364 bytes, checksum: a13c081e60319e997b56935fa0771793 (MD5)O presente trabalho teve como objetivo estudar as propriedades magnéticas e de transporte elétrico de filmes finos de MGBIND.2', de espessura, rescidos pelo método de Pulsed Laser Deposition, diante de variações de conformidade microestrutural. Para efeito de comparação, foram utilizados filmes finos com 100 e 400nm de espessura crescidos pelo método Chemical Vapor Deposition. O trabalho foi possível graças ao desenvolvimento de um sistema de fixação de amostras que mostrou ser eficaz nos casos onde a deposição de terminais com epóxi prata inutiliza as amostras para estudos posteriores devido à contaminação. Foram realizados ensaios de magneto-transporte, magnetização e susceptibilidade magnética utilizando o Physical Property Measurement System (PPMS). Os resultados de magneto-transporte foram modelados matematicamente por meio do modelo de Bloch-Grüneisen, mediante o uso do software Mathematica. A análise dos resultados mostrou que diferenças microestruturais conduzem a um comportamento de resistividade no estado normal diferenciado. A possível existência de uma microestrutura diferenciada, onde há dificuldade em se definir um contorno de grão, e praticamente a inexistência de material intragranular, podem ser a chave para o entendimento de medidas de transporte elétrico e magnéticas tão singulares, onde não há evidências de comportamento inter e intragranular, como ocorre geralmente nos supercondutores cerâmicos. Por último, o modelamento da resistividade permitiu validar todo o sistema de medidas utilizado, pois os resultados obtidos estão em acordo com a literatura.
In this work it was studied magnetic and electrical transport properties of MGB IND.2' thin films, with 200nm of thick, grown by the method of Pulsed Laser Deposition, in front of microstructure variation. For comparison, were also analyzed thin films with 100 and 400nm of thickness grown by Chemical Vapor Deposition method. This study was possible since the development of sample fixing system that showed be effective in the cases that the terminals depositions with silver epoxy make samples useless for the future studies due to contamination. Magnetic-transport, magnetization and magnetic susceptibility were performed using the Physical Property Measurement System (PPMS). The results of magnetictransport measurements were modeled by the Bloch-Grüneisen model through the Mathematica Software. Analysis of the results showed that microstructural differences of the samples make different the value of resistivity in the normal state. Possible existence of the different microstructural where have difficult to define the grain boundary and absent of intergranular material, factors that can the key for the understanding of electrical transport and magnectic measurements how individuals, where no have evidences of inter and intragranular behavior, how exist in the ceramic superconductors. At last, the resistivity model permitted validates all the measurement system utilized, because the results obtained are in agreement with the literature.
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Fagundes, Hugo de Oliveira. "Modelagem hidrossedimentológica de grandes bacias com o apoio de dados in situ e sensoriamento remoto." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/175012.
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A utilização de modelos hidrossedimentológicos em grandes escalas é escassa, principalmente devido à falta de dados observados, necessários nas etapas de calibração e validação. Nesse contexto, foi realizada a simulação hidrossedimentológica com o modelo MGB-SED e avaliada a dinâmica espaço-temporal dos sedimentos em suspensão na bacia hidrográfica do rio Doce, localizada nos estados de Minas Gerais e Espírito Santo, que drena uma área de cerca de 86.715 km². Além disso, foi investigada a aplicabilidade de dados observados de concentração de sedimentos em suspensão (CSS), turbidez, sólidos suspensos totais (SST) e reflectância espectral de superfície na calibração e validação de modelos hidrossedimentológicos de grandes bacias. O modelo MGB-SED é resultante do acoplamento de um módulo de sedimentos ao modelo hidrológico de grandes bacias MGBIPH. O MGB-SED é um modelo empírico-conceitual, distribuído, discretizado em minibacias e que utiliza o conceito de Unidades de Resposta Hidrológica (URHs). Nas URHs são gerados os volumes de água e de sedimentos (calculado a partir da equação MUSLE) que serão propagados nos trechos de rio. A propagação do escoamento é feita por meio da equação de Muskingum-Cunge. O transporte de sedimentos é realizado por meio da equação de difusãoadvecção para materiais que estão em suspensão (argila e silte) e por meio da equação da continuidade dos sedimentos para a carga de fundo (areia). Foram estabelecidos quatorze experimentos para a calibração e validação do modelo MGB-SED com os dados observados. Os resultados mostraram que mesmo usando os valores padrão, o modelo MGB-SED apresentou resultados satisfatórios, com coeficiente de correlação acima de 0,50 para mais de 60% das estações de CSS, colaborando para a compreensão da dinâmica dos sedimentos na bacia. Os experimentos indicaram que os resultados podem ser melhorados ao: (i) aumentar o número sub-bacias; (ii) combinar métricas que representem a correlação, o viés e a amplitude de variação; (iii) utilizar o logaritmo da CSS ao invés da CSS diretamente; (iv) utilizar uma concentração de base; e (v) utilizar um intervalo de busca dos parâmetros calibráveis menor. A aplicação do modelo na bacia do rio Doce, da forma realizada, não permitiu representar sempre os grandes picos de CSS. A utilização do modelo permitiu identificar alguns padrões e comportamentos na bacia como o fato de que no período seco a principal fonte de sedimentos não é as encostas, mas sim os canais. A análise dos diferentes tipos de dados indica que os rios que mais contribuem com a carga de sedimentos para o rio Doce são o Caratinga, o Suaçuí Grande e o Guandu.The use of erosion and sediment transport model at large scales is scarce, mainly due the lack of observed data, necessary in calibration and validation steps. In this context, erosion and sediment transport simulation was carried out using the MGB-SED model and the spatialtemporal dynamics of suspended sediment in the Doce river basin were evaluated. In addition, we investigated the applicability of observed suspended sediment concentration (SSC), turbidity, total suspended solid (TSS) and surface spectral reflectance in the calibration and validation of erosion and sediment transport models for large river basins. The MGB-SED model is the result of the coupling of a sediment module to the large-scale hydrological model MGB-IPH. The MGB-SED is an empirical-conceptual, distributed model that uses a catchmentbased discretization and the hydrological response units (HRU) approach. In the HRUs, volumes of water and sediments (estimated by MUSLE equation) that will be routed in river reaches are generated. Flow routing is performed using a Muskingum-Cunge equation. Sediment transport is performed using a diffusion-advection equation for materials that are suspended (silt and clay) and performed using a sediment continuity equation for bed load (sand). Fourteen experiments to calibration and validation of the MGB-SED model using the observed data were established. Results showed that even using standard values, the MGBSED model presented satisfactory results, with correlations coefficient above 0.50 for more than 60% of the CSS gauges, collaborating to understand the sediment dynamics in the basin. Experiments indicated that results can be improved by: (i) increasing the number of sub-basin; (ii) combine metrics that represent the correlation, the bias, and the amplitude variation; (iii) use the logarithm of SSC instead of SSC directly; (iv) using a background concentration; and (v) use a smaller search interval of calibrated parameters. The application of the model in Doce river basin, in the way it was done, did not allowed to always represent the large SSC peaks. The use of the model allowed to identify some patterns and behaviors in the basin such as the fact that in the dry period the main source of sediments is not slopes but channels. The analysis of the different types of data indicates that the rivers that contribute most for the Doce river sediment load are Caratinga, Suaçuí Grande and Guandu.
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Lopes, Vitória Ache Rocha. "Modelagem hidrológica e hidrodinâmica integrada de bacias e sistemas lagunares com influência do vento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/172898.
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A modelagem hidrológica-hidrodinâmica de bacias, rios e grandes corpos d’água, como lagos e lagunas, é usualmente realizada por meio do acoplamento externo entre modelos hidrológicos-hidráulicos e modelos hidrodinâmicos de duas ou três dimensões. Dessa forma, simulam-se com o modelo hidrológico-hidráulico as vazões nos rios afluentes e utiliza-se essa informação como entrada no modelo hidrodinâmico dos grandes corpos d’água. Essa abordagem permite considerações sobre a hidrodinâmica desses sistemas de forma detalhada. No entanto, quando o interesse é a simulação de níveis e áreas alagadas, por exemplo, para previsões de vazões ou realizações de estudos de mudanças climáticas, a mesma pode ser custosa e de difícil operacionalização. Dessa forma, o presente estudo foi desenvolvido para investigar uma abordagem alternativa, a simulação de bacias, rios e lagos e/ou lagunas com um só modelo hidrológico-hidráulico, o modelo MGB-IPH Inercial, avaliando a inclusão da influência do vento no algoritmo inercial de propagação de vazões na simulação, já que esse fator pode exercer influência importante em grandes corpos d’água. A área de estudo selecionada para testar essa abordagem consistiu na bacia hidrográfica da Laguna dos Patos, localizada no Brasil e no Uruguai. Os resultados mostraram que foi possível utilizar a abordagem integrada proposta no presente estudo na simulação dos níveis d’água na Laguna dos Patos, RS. Resultados das métricas de desempenho dos níveis foram comparados com a literatura, verificando similaridade com resultados obtidos por meio da abordagem tradicional. Analisou-se a influência da inclusão do efeito do vento no método inercial e propôs-se um ábaco para estimar o efeito máximo que o vento exerce sobre escoamentos de características específicas. Verificou-se que a inclusão da influência do vento melhorou a representação do sistema modelado, portanto, encorajando a utilização da versão modificada proposta nesse estudo na simulação de outros locais influenciados por esse fator. Testes realizados permitiram a obtenção de novos conhecimentos da técnica de modelagem utilizada, sinalizando melhorias com a utilização de conjuntos de dados de vento com maior disponibilidade temporal e espacial e com a utilização de dados de níveis d’água como condição de contorno de jusante. Estudos futuros viabilizados a partir deste trabalho englobam a utilização do modelo proposto em análises de mudanças climáticas e de uso do solo, reanálise de cheias históricas, como a cheia de 1941, e estabelecimento de sistemas de previsão dos níveis no Guaíba e na Laguna dos Patos.Hydrological-hydrodynamic modelling of basins, rivers and large water bodies such as lakes and lagoons is usually performed by the external coupling of hydrological-hydraulic models and 2D or 3D hydrodynamic models. Therefore, the river discharges into the lake are calculated by the hydrologic-hydraulic model and then used as an input in the hydrodynamic model. This approach allows for detailed simulation of lake or lagoon hydrodynamics and circulation. However, when the objective is to simulate water levels and flooded areas, this approach may become too costly, making it difficult to stablish operational systems such as flood forecasting. Therefore, in the present study, an integrated approach is proposed by the use of one integrated hydrologic-hydraulic model, the MGB-IPH Inertial model, to simulate such complex systems including wind shear influence in the inertial flood routing algorithm. The study area was the Patos Lagoon basin, located in both Brazil and Uruguay. Results showed that it was possible to use the proposed approach to simulate flooded areas and water levels in the Patos Lagoon and Lake Guaíba. Results of performance indicators were compared to results available in the literature obtained by the use of 2D hydrodynamic models and similarity among them was verified. The influence of the wind shear inclusion on the inertial routing method was analyzed; an abacus and an equation were proposed to estimate the maximum influence wind shear can exert in a system under specific conditions. Improvement of model results were verified with the inclusion of wind effect in the flow routing algorithm, encouraging the use of the modified model in the simulation of other locations susceptible to wind influence. Tests performed allowed for the acknowledgment of factors that influence the modelling approach proposed. More spatially and temporally detailed wind data helped to improve results, such as the use of water level data as downstream boundary condition to include tide effects in the system. Future studies of the proposed model of the Patos Lagoon basin include climate change and land change effects on water levels, historical flood simulations, such as the famous flood of 1941, and the establishment of flood forecasting systems to predict lagoon water levels.
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Idrobo, Juan Carlos. "A study of the electronic structure and the effects of oxygen on the superconducting properties of MgB₂ by electron energy loss spectroscopy /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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