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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

A natureza de defeitos de Bulk e na superfície de semicondutores / The nature of defects in the Bulk and at the surface of semiconductors

Gustavo Martini Dalpian 11 August 2003 (has links)
Utilizando métodos de primeiros princípios, baseados na Teoria do Funcional da Desidade, investigamos, de forma sistemática, problemas de interesse na física de semicondutores: (i) A liga SixGe1-x: observa-se um pequeno desvio da linearidade, para o parâmetro de rede da liga, em função da concentração, sendo que as distâncias entre átomos de Ge são as que mais variam. O comportamento de vacâncias nessa liga se mostrou intermediário entre o Ge e o Si, e a energia de formação (EF) das vacâncias variou entre 2,06 eV e 2,90 eV, dependendo da vizinhança dessa. Propusemos um modelo para a difusão de Ge nessa liga. O fato das vacâncias com mais átomos de Ge como vizinhos ter menor energia de formação, faz com que a difusão das vacâncias se dê por caminhos lembrando o Ge puro, ou seja, a tendência será de que os vizinhos dessa vacância sejam de Ge, para ligas ricas em Ge; (ii) Superfícies: estudamos a adsorção de monômeros e dímeros de Ge sobre Si (100). Verificamos que, para monômeros, podem existir diversos mínimos locais da superfície de energia potencial para a mesma posição (x, y) na superfície, cuja diferença está na inclinação dos dímeros da superfície perto deste átomo. Mostramos que isso pode ser identificado em imagens teóricas de STM (Scanning Tunelling Microscopy) e propomos que isso seja verificado experimentalmente. Este tipo de efeito também ocorre com dímeros, sendo que isso já foi observado experimentalmente, mas com uma interpretação errônea. Através do nosso estudo podemos propor uma estrutura mais condizente com as imagens experimentais. O comportamento de átomos e dímeros de Si e Ge perto de degraus também foi analisado. Devido à diferença no parâmetro de rede do Si e do Ge, mostramos que a adsorção se torna diferente quando somente dois átomos estão na superfície. Através desses resultados, propomos um modelo para explicar a reversão da rugosidade dos degraus durante o crescimento de Ge sobre Si(100); (iii) Impurezas de Mn em Si: analisamos o comportamento de impurezas de Mn no cristal de Si e sobre a superfície. No cristal, observamos que a EF de sítios intersticiais é menor do que os sítios substitucionais. Sobre a superfície, existe um sítio substitucional que possue a mesma EF de um sítio intersticial. Esse é um fato importante para o desenvolvimento de semicondutores ferromagnéticos à base de Si. Propomos um método para que esse fato seja verificado experimentalmente, através de imagens de STM. / Using ab initio methods, based on Density Functional Theory, we have systematically investigated problems of interest for semiconductor physics: (i)The SixGe1-x alloy: we observe a small bowing in the lattice parameter, as a function of concentration, and that a larger variation in interatomic distances occurs for Ge-Ge bonds. The behavior of vacancies in this alloy is intermediate between Si and Ge, with formation energies (EF) varying from 2,06 eV to 2,90 eV, depending on the neighborhood of the vacancy. We propose a model for the diffusion of Ge in this alloy. As the vacancy with four Ge atoms as first neighbors hás smaller formation energy, the diffusion of the vacancies Will take place along paths that resemble purê Ge, for Ge-rich alloys; (ii)Surfaces: we study the adsorption of Ge monomers and dimers on Si(100). For monomers, there are several local mínima of the potential energy surface, for the same (x, y) position in the surface, depending on the buckling of the surface dimers near the adatom. We show that this can be identified in theoretical STM (Scanning Tunelling Microscopy) images. This kind of effect also occurs for dimers, and hás already been observed experimentally, but with a wrong interpretation. Through our study, we propose a new structure for the experimental images. The behavior of Si and Ge atoms and dimers near steps is also analyzed. Due to the differencein the lattice parameter of Si and Ge, we show that the adsorption becomes different when only two atoms are in the surface. Through these results, we propose a model to explain the reversion of step roughness due to Ge deposition on Si(100); (iii)Mn impurities in Si: we analise the behavior of Mn impurities in bulk Si ando n the surface. For the bulk, we observe that EF is lower for intersititial than for substitutional sites. On the surface, there is a substitutional site that hás the same EF AS A INTESTITIAL ONE. This fact may be important to the development of Si based ferromagnetic semiconductors. A method is proposed to verify this fact experimentally, through STM images.
112

Quantification des pools de nucléotides à l'aide de la chromatographie liquide couplée à la spectrométrie de masse en tandem : applications à l'étude de la progression tumorale / Quantification of nucleotides pools with liquid chromatography coupled with tandem mass spectrometry : applications in cancer research

Machon, Christelle 13 November 2015 (has links)
Les nucléotides, terme regroupant les nucléosides monophosphate, diphosphate et triphosphate, sont impliqués dans de nombreux processus cellulaires. Ils représentent les éléments constitutifs des acides nucléiques, fournissent de l'énergie à des réactions métaboliques, jouent le rôle de transporteurs et seconds messagers. L'exploration des pools nucléotidiques apparaît indispensable afin de connaître leur rôle précis dans des situations physiologiques ou pathologiques. Nous avons développé une méthode de dosage des nucléotides endogènes (formes mono-, di- et triphosphate) par extraction en ligne sur colonne WAX couplée à la LC-MS/MS. La séparation analytique est réalisée sur colonne Hypercarb, sans agent de paire d'ions dans la phase mobile. Grâce à l'utilisation d'un triple quadripôle et une ionisation en mode positif, les nucléotides endogènes sont identifiés sans équivoque, y compris ceux possédant la même masse molaire. L'extraction et la séparation des nucléotides sont réalisées en 20 min. L'ensemble de la méthode, en comptant la ré- équilibration des colonnes, dure 37 min. La méthode de dosage a été validée pour les formes mono- et triphosphate et est applicable à des séries d'une vingtaine d'échantillons biologiques. D'autre part, dans une étude pré-analytique basée sur les plans d'expériences, nous avons comparé les conditions de préparation d'échantillons en vue du dosage de nucléotides intracellulaires dans 4 lignées cellulaires : 2 adhérentes (Messa et NCI-H292) et 2 en suspension (RL et L1210). Nous avons montré que les conditions pré-analytiques optimales dépendent de la lignée cellulaire soulignant ainsi l'importance de cette phase dans l'analyse des nucléotides. Enfin, l'expérience et les connaissances acquises lors du développement de la méthode de dosage des nucléotides ainsi que la large palette de molécules analysables avec cette méthode (nucléosides, nucléotides sucrés, autres métabolites), nous ont permis de développer des collaborations dans le domaine de la cancérologie avec différentes équipes de recherche. Par exemple, nous avons étudié l'implication des pools nucléotidiques dans le stress réplicatif induit par le stress oxydant et dans la reprogrammation cellulaire observée dans les cellules cancéreuses. Ainsi, les informations apportées par notre approche analytique, complémentaires des autres approches utilisées, ont montré l'implication des pools nucléotidiques dans la tumorigénèse. En conclusion, ce travail a permis de développer une technique analytique et de mettre en place une méthode de travail pour le dosage des nucléotides endogènes dans différents milieux biologiques / Nucleotides, term including nucleoside mono-, di- and triphosphates, are endogenous compounds playing various roles in biology. They are components of nucleic acids, provide energy to metabolic reactions and act as carriers or second messenger. The study of endogenous nucleotides has become of great interest in physiological and pathological conditions. We developed a method for the quantification of endogenous nucleotides, using an on-line extraction on a WAX column coupled with LC-MS/MS. Analytical separation is performed on a Hypercarb column, without ion pairing agent in the mobile phase. The use of a triple quadrupole mass spectrometer following positive mode ionization allows the unambiguous identification of nucleotides presenting the same mass. Extraction and separation of nucleotides are achieved within 20 min and the method including re-equilibration of the two columns within 37 min. The method was validated for the quantification of nucleoside mono- and triphosphates, and could be applied to series of more than twenty biological samples. Secondly, in a study based on design of experiments, pre-analytical parameters influencing results of intracellular nucleotides were compared in four cell lines. We demonstrated that optimal pre-analytical parameters depend on cell lines. This clearly highlights the importance of pre- analytical conditions for the quantification of intracellular nucleotides to be as representative as possible of the real levels in cells. Then, thanks to experience acquired during the development and the validation of the analytical method, scientific collaborations have been established with several cancer research teams. For example, implication of nucleotide metabolism in replicative stress induced by oxidative stress or in the metabolic reprogramming in cancer cells was studied. Results obtained by our analytical approach were complementary to those obtained by other techniques. To conclude, our work consisted on the study of the entire workflow for the analysis of endogenous nucleotides in various biological samples
113

Hidden Power: Content Marketing as a part of global business strategies of Westen companies in the Russian environment

Khudododov, Rustam, Kim, Alexandra January 2017 (has links)
International companies face many challenges when operating in foreign country markets, as a new environment could be absolutely opposite to the one of the home market, which the companies are used to. One of the biggest issues for a company in the foreign market is to understand how to market its product and make it more appealing to the audience. This research is aimed at studying content marketing strategy as a new trend and a part of marketing strategy of an organization. Particularly, the main focus of this research is to investigate the process of building content marketing strategy of Western firms in the Russian environment. During the study, a few questions are illuminated, such as what steps are undertaken in order to manage a sound content marketing strategy and how the characteristics of Russian consumers influence the decision making and to what extent. The paper studies all these issues by the qualitative approach, presenting data and insights acquired through interviews with four Western companies, operating in Russia: Burger King, Johnson & Johnson, The Coca-Cola Company and Visa Inc. The analysis of the findings is done, comparing the experience of the companies with each other, which enables the authors to extract general patterns for content marketing strategy in Russia in terms of strategy building and consumer orientation and comparing empirical data with theoretical knowledge gained after the examination of the theory. The paper concludes giving answers to the research question and generalizing the analysis, as well as presenting the revised conceptual model. Later on, the main limitations of this study are mentioned and the suggestions for future research are stated to develop the understanding of content marketing strategy.
114

Metody a způsoby řízení projektů zaměřených na Change Management / Management of Change Projects

Kubíček, Milan January 2010 (has links)
The thesis is dedicated to management of projects that focus transitional and transformational changes in organizations. The theoretical part of the thesis covers terminology and definition of change management. Project and change management dependencies are defined. Consequently, Prosci change management methodology, Kotter's 8 Steps for Leading Change and GE Change acceleration process are analyzed. Finally, a methodology for practical part of the thesis is selected. Practical part includes description and usage of most frequent CAP tools as well as a case study. A real change project is described and evaluated from CAP methodology perspective.
115

Synthèse d’analogues carbonés de la Ribavirine pour leurs activités antivirales / Synthesis of carbonated analogs of Ribavirin for their antiviral activities

Cosson, Fanny 24 April 2014 (has links)
La Ribavirine est un analogue nucléosidique de la guanosine constitué d'un ribose et d'un noyau triazole. Cet antiviral, synthétisé en 1970, possède une activité contre différents virus comme le virus respiratoire syncytial chez les enfants en détresse respiratoire, les virus des hépatites B et E, ainsi que contre certains cancers et leucémies. Elle est surtout connue pour son utilisation dans le traitement de l'hépatite C, en combinaison avec l'Interféron. Cependant, l'efficacité de cette thérapie est limitée à certains génotypes du virus et les effets secondaires résultants sont nombreux. C'est pourquoi il est nécessaire de trouver d'autres analogues actifs contre l'hépatite C et moins toxiques afin d'offrir un traitement aux 170 millions d'individus atteints de cette maladie chronique et pouvant évoluer vers des cirrhoses et des cancers du foie. Par une méthodologie d'alcynylglycosylation médiée à l'indium suivie d'une cycloaddition 1,3 dipolaire, des C-nucléosides analogues de la Ribavirine ont été synthétisés. L'un deux, SRO-91, a montré une activité antivirale comparable à celle de la Ribavirine vis-à-vis de l'ARN polymérase du virus de l'hépatite C. L'objectif de cette thèse est donc de synthétiser d'autres C-nucléosides analogues sur le modèle de SRO-91. Des modifications ont été effectuées autant sur le ribose que sur le noyau triazole. Concernant les transformations du ribose, nous nous sommes intéressés à la position C2', notamment en introduisant une quaternisation avec différents groupements (CH3, CF3, F …) ou bien en désoxygénant cette position. Cette thèse décrit les différentes stratégies explorées pour la synthèse de plusieurs de ces C-nucléosides dont les activités antivirales seront étudiées ultérieurement. / Ribavirin is a nucleosidic analogue of guanosine composed of a ribose and a triazole ring. This antiviral compound, synthesized in 1970, exhibits an activity against a broad-range of viruses such as respiratory syncytial virus in respiratory distress children, hepatitis B and E viruses as well as some cancers and leukemia. It is especially known for its use in hepatitis C treatment in combination with Interferon. However, the efficiency of this therapy is limited to a few genotypes of the virus and leads to numerous side effects. Therefore, finding new efficient and less toxic analogs is necessary to treat the 170 million individuals that are chronically infected and at risk of developing cirrhosis and liver cancer. Thanks to a methodology of indium mediated alcynylglycosylation followed by a 1,3-dipolar cycloaddition, C-nucleosides analogs of Ribavirin have been synthesized. Among them, SRO-91, showed a comparable activity to Ribavirin towards hepatitis C virus ARN polymerase. This thesis' objective is to synthesize other C-nucleosides analogs based on SRO-91 model. Modifications have been made on the triazole ring as well as on the ribose. In regards to the ribose transformations, we have been interested into the C2' position, in particular by introducing a quaternisation with different moieties (CH3, CF3, F …) or by deoxygenating this position. This thesis describes the different strategies explored for the synthesis of some of these C-nucleosides whose antiviral activities will be studied later.
116

Využití osobnostní typologie Predictive Index v managementu změn dle J.Kottera / Utilizing the Predictive Index personality typology in change management by J.Kotter

Vlček, Tomáš January 2015 (has links)
The thesis offers results of a research which has been conducted to look for and describe the typical personal characteristics of a change manager using Predictive Index tool and Kotter´s 8 steps process of change management. The thesis also offers set of practical recommendations for change management leaders as well as for the organizations.
117

Étude de la distribution de campylobacter à différentes étapes de la transformation primaire de la volaille dans des abattoirs du Québec

Quessy, Alexandre 05 1900 (has links)
Campylobacter est la principale cause de gastro-entérite bactérienne d’origine alimentaire à travers le monde. Chez les consommateurs, les campylobactérioses d’origine alimentaire sont en grande majorité dues au contact et à la consommation de produits de volaille, le poulet à griller étant particulièrement mis en cause. La contamination de la carcasse se fait souvent lors de l’abattage des oiseaux. Bien que plusieurs données concernant la distribution de Campylobacter à l’abattoir soient disponibles dans certains pays, aucune étude récente visant à décrire la présence et la distribution de ce pathogène, tout au long de la chaîne d’abattage, n'a été réalisée au niveau des établissements d'abattage canadiens. Notre hypothèse était que l’on pouvait identifier des étapes clés d’intervention pour contrôler la contamination par Campylobacter sur les carcasses de volaille à l’abattoir en étudiant la présence de ce pathogène sur les produits de viande et dans l’environnement de production. Il y avait deux objectifs principaux dans cette étude. Premièrement, nous voulions décrire la distribution de Campylobacter lors des différentes étapes de production dans deux établissements de transformation québécois. Deuxièmement, nous voulions déterminer si les moyens de gestion du risque mis en place au moment de l’étude étaient suffisants pour prévenir la contamination du produit de viande destiné au consommateur. Pour répondre à ces objectifs, un oiseau par lot d’élevage a été échantillonné par rinçât de carcasse pour chaque étape suivante de la transformation (n=4) : avant l'abattage, tout juste après la saignée, au transfert entre les chaînes d'abattage et d'éviscération, après l'éviscération et après l’étape du refroidissement dans deux abattoirs québécois. Cette procédure fut répétée pour un total de 379 échantillons de rinçâts de carcasses de poulets de chair qui ont été collectés à l’occasion de multiples visites à l’abattoir et ce, de février à juillet 2017. Un total de 217 échantillons environnementaux pouvant être impliqués dans la contamination croisée des oiseaux ont aussi été récupéré pendant les diverses visites. Les échantillons ont été dilués dans de l'eau peptonée et une identification de Campylobacter par PCR a été faite à l’aide d’amorces spécifiques au gène codant pour l’ARN ribosomal 16S. Les résultats obtenus pour la période étudiée indiquent que la positivité des carcasses de poulets de chair à Campylobacter est significativement plus élevée pour les échantillons effectués l’été comparé au printemps. En revanche, la présence de la bactérie dans l’environnement des abattoirs étudiés apparaît plus élevée durant l’hiver. Puisque la présence de la bactérie sur les carcasses de poulets a diminué tout au long de la chaîne de production, qu’aucune carcasse positive n’a été retrouvée après un refroidissement à l’air et que la positivité des carcasses suite au refroidissement à l’eau était aussi très basse, nos résultats suggèrent, malgré certains enjeux associés à la sensibilité de la méthode d’identification des échantillons positifs, que les mesures actuelles de gestion du risque sont efficaces pour contrôler Campylobacter dans les deux abattoirs québécois suivis. / Campylobacter is responsible of the highest number of bacterial gastroenteritis worldwide. Most diseases in humans attributed to meat can be associated to consumption of or contact with poultry derived products; broiler chicken being involved in the majority of cases. The contamination of carcasses often occurs during the slaughter process. While many studies from various countries reported the distribution of Campylobacter among various critical steps of the slaughter process, none has been published, to our knowledge, in Canada regarding the presence and distribution of this bacterium within the abattoir. Our hypothesis was that it would be possible to identify key steps to control the contamination of carcasses by this bacterium by studying the presence and distribution of Campylobacter on carcasses and within the environment during the slaughter process. This study had two objectives. The first objective was to describe the distribution of Campylobacter within two selected slaughterhouses in Quebec in order to understand which processing step(s) play(s) a critical role in carcasses contamination. In the second objective, we aimed to verify if actual management procedures applied in these abattoirs were efficient in preventing consumer’s exposition. To meet these goals, four birds by production lot, one at each of the following steps (after bleeding, at transfer between killing and evisceration chain, after evisceration and after the cooling process) were sampled for a total of 379 birds from February 2017 to July 2017 in two slaughterhouses located in the province of Quebec. Furthermore, 217 environmental samples were collected during these visits in various sites possibly in contact with birds. Samples were suspended in peptone water and submitted to a PCR assay, using a specific 16S ribosomal probe, for detection of Campylobacter. Overall, for the year of the study, we observed a significantly higher number of positive carcasses in summer compared to spring, while the environmental samples were more often positive in winter compared with summer. Furthermore, our results indicated that the number of positive carcasses decreased over the various processing steps, being either negative (air chilling) or low (water chilling) after the cooling process. Although we experienced some issues associated with the sensitivity of the procedure we used in this study to recover Campylobacter, taken together, these results suggest that the actual management procedures of Campylobacter in studied slaughterhouses are efficient.
118

Development and Cross-Validation of a Cadence-Based Metabolic Equation for Walking

Moore, Christopher C 02 July 2019 (has links)
The ACSM Metabolic Equation is a widely recognized equation for predicting metabolic intensity from walking speed. However, an equation that uses an observable metric (i.e., cadence [steps/min]), accounts for individual characteristics, and is validated across walking conditions may enable more accessible and accurate predictions of walking intensity. PURPOSE: To develop metabolic equations that predict metabolic intensity (oxygen consumption; mL/kg/min) from cadence using a large treadmill walking dataset (Study One) and cross-validate these equations during overground unconstrained and cadence-constrained walking conditions (Study Two). METHODS: In Study One, 193 adults (21-81 years) completed treadmill walking bouts while oxygen consumption was measured with indirect calorimetry (converted to metabolic equivalents [METs]; 1 MET=3.5 mL/kg/min=1 kcal/kg/min). Directly-observed step counts divided by bout duration produced cadence. The least squares regression of the cadence-intensity relationship produced a simple equation and a full equation was developed using best subsets regression (additional possible predictors of leg length, body mass, BMI, percent body fat, sex, and age). Predictive accuracy and bias of each cadence-based metabolic equation and the ACSM Metabolic Equation was evaluated through k-fold cross-validation. In Study Two, these three metabolic equations were applied to data collected from 20 young adults during overground walking at self-selected paces (unconstrained) and with foot-strikes entrained to music tempos (cadence-constrained). RESULTS: In Study One, the simple equation predicted walking intensity within 0.5 METs, on average, and approximately no bias (CONCLUSIONS: The simple equation performed comparably to the full equation (which accounted for individual characteristics) and appreciably better than the ACSM Metabolic Equation. The simple cadence-based metabolic equation is an improved, user-friendly tool for predicting and prescribing walking intensity with reasonable accuracy (within ~0.5 METs; 45 kcals/hr for the average American).
119

Prodloužení životnosti cementobetonových krytů / Extension of life time of concrete pavements

Renzová, Martina January 2013 (has links)
The aim of the theoretical part of this Master´s thesis is to make a research of possible ways in repairing PCC pavements without anchoring transverse joints. The pratical part is focused on the design of PCC pavements segmentations in experimental sections and evaluation measurement by testing muted impact.
120

Fabrication of Nano Josephson Junctions Using the Femtosecond Laser Technique on High Tc Superconducting YBCO Thin films

Umenne, Patrice 27 February 2018 (has links)
This PhD work involves the utilization of the femtosecond laser technique to fabricate the novel S-shaped Josephson Junctions on the high - T_C superconducting YBCO thin films. Initially, it was envisaged as the title states to fabricate nano sized Josephson Junctions using this femtosecond laser technique. However in this PhD work, micron sized (1 – 2 µm) and near nano sized (500 – 800 nm) Josephson Junctions where achieved. / University of South Africa / Electrical and Mining Engineering

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