McGill University Thèses et mémoires par auteur commençant par S

Nous utilisons des simulations de dynamique moléculaire (DM), dotées d’un potentiel interatomique appris par machine, pour examiner l’impact du désordre structural sur le transport des phonons dans le graphène bidimensionnel. En générant des structures amorphes par des méthodes de Monte Carlo, nous procédons à une investigation systématique de la manière dont les défauts modifient la conductivité thermique et les propriétés vibrationnelles. Nos résultats démontrent qu’une concentration minimale de défauts de 0.2% entraîne une dégradation significative de la conductivité thermique : la composante hors-plan diminue d’un ordre de grandeur, tandis que la composante in-plan se réduit de moitié. Les analyses spectrales …  Lire la suite

Oxidative stress, which is, linked to numerous diseases results from an imbalance in cellular redox state causing damage to the cell cytoskeleton and morphology, thereby affecting the cells' viscoelastic properties. In this study, we introduce a quartz crystal microbalance with dissipation (QCM-D) biosensing strategy to assess the effects of oxidative stress on the viscoelastic properties of MC3T3 cells modulated by varying concentrations of hydrogen peroxide (H2O2). We successfully tracked the changes in dissipation (ΔD-responses) caused by the interaction of H2O2 with MC3T3 cells' monolayer attached to a poly-D-lysine-coated polystyrene quartz sensor. While recovery of ΔD-response curve close to the baseline …  Lire la suite

The decomposition of three phenyl-substituted 1,2-dithiolium salts, 3,5-diphenyl-, 3-phenyl- and 4-phenyl- in aqueous, ethanol and DMSO solutions have been examined. With bases of the type hydroxide, ethoxide, DMSO, and acetate, the 1,2-dithiolium ion formed adducts reversibly. Orders of adduct stability were determined in ethanol and water. Many of the adducts were unstable and decomposed to monothio-(beta)-dicarbonyls. The monothio-(beta)-dicarbonyls were in turn unstable and decomposed in aqueous media to the corresponding-(beta)-diketone in the case of the monothiodibenzoylmethane. Reaction of the 1,2-dithiolium ions with sodium sulphide or sodium borohydride led to dithio-(beta)-dicarbonyls. These species were unstable and decomposed to monothio-(beta)-dicarbonyls in the …  Lire la suite

Chromik, Richard (Supervisor1)  Lire la suite

Mon projet de thèse identifie et évalue les « cadres éthiques » qui dominent l’environnement éthique des organisations communautaires axées sur la jeunesse et le développement communautaire en Amérique du Nord. J’utilise le terme « cadre éthique » pour désigner un ensemble de sensibilités et de convictions plus ou moins liées entre elles, ainsi que certaines interprétations de concepts moraux associés. Par exemple, le cadre éthique de « l’entrepreneur » - l’un des principaux cadres que j’identifie et évalue dans ma thèse - est axé sur une compréhension particulière du travail et de l’efficacité, et privilégie ce qui est pratique …  Lire la suite

Un nouveau modèle de prédiction de chocs axisymétriques avec réflexion de Mach à leur axe est développé. Le modèle combine la méthode des caractéristiques avec les équations d’écoulement quasi-unidimensionnel. Une méthode est développée et appliquée pour étendre le modèle à des cas ayant des tiges de Mach extrêmement courtes, générées par de faibles chocs incidents.Les prédictions provenant de ces modèles sont comparées avec celles de la mécanique des fluides numérique (MFN) non-visqueux pour une gamme de géométries convergentes axisymétriques, et les effets de longueur de rampe et d’angle de choc au bord d’attaque sont examinés. Les nombreuses géométries de rampe …  Lire la suite

The program of this thesis is to trace the development of Hegel's thought in the writings of his youth as they evolved to and influenced the thinking of his maturity. These writings are of particular interest for they are characterized by a flexibility, a vitality, an historical, existential insight and concern which is relatively lacking in his later works. Furthermore, we can see in them the germs of his later thought. [...]  Lire la suite

Previous cross-cultural studies show that children’s moral evaluations of lie- and truth-telling may be influenced by culture. However, the potential impact of social factors such as parental disciplinary methods in different cultures has not been investigated. Also, previous findings in Eastern Asian cultures do not account for children who live in the Middle East. The purpose of this study was fivefold: a) to examine the impact of culture on mothers’ inclinations towards either collectivism or individualism; b) to identify the impact of culture on mothers’ disciplinary methods; c) to recognize the influence of maternal disciplinary methods on children’s moral evaluations …  Lire la suite

Des études de suivi portant sur des groupes d’éléments tels que des individus, ou des régions géographiques ou écologiques, sont souvent réalisées dans le but d’obtenir plus d’informations sur l’évolution d’un ou plusieurs de ces éléments au fil du temps. À la suite d’observations initiales ou de référence d’un certain nombre d’éléments, la loi des valeurs observables peut être sujette à changement dû à une intervention expérimentale ou une cause naturelle. Le moment précis au cours duquel la loi d’une valeur change n’est parfois pas lui-même observable; en ce cas, l’inférence statistique suit le cadre général dit d’inférence sous point …  Lire la suite

The purpose of this study is to investigate the possible relationship between social mix and the quality of life in housing. Quality of life is measured by levels of satisfaction, social integration, mobility and freedom of choice, etc. This study has identified some factors which may have an effect on the quality of life in socially mixed housing projects. This study has formulated general observations from these factors which could influence the way the built environment is shaped, especially ways in which residents, can or cannot, appreciate and tolerate social mix. The evidence indicates that design, quality of construction, good …  Lire la suite

A Solid State Transformer (SST) performs the tasks of a conventional transformer by means of power electronic converters and high-frequency transformers. In addition to voltage level transformation, some SST topologies are able to provide ancillary services to the AC grid.In a three-stage SST, the first-stage is an AC/DC converter. In most designs, this stage employs a multilevel converter topology rather than a two-level converter. The reason for this is that a multilevel converter provides such advantages as capability to interface with a medium voltage AC grid. Among all multilevel converter topologies, a new generation of multilevel converters called Modular Multilevel …  Lire la suite

L'hypertension artérielle (HTA) est le principal facteur de risque de maladie et mortalité. Elle est associée à une inflammation chronique de bas niveau, et il serait intéressant d’identifier des cibles diminuant cette inflammation. Le récepteur purinergique P2X7 (P2RX7) est un régulateur clé de la signalisation inflammatoire. Des niveaux élevés d'ATP plasmatique ont été observés chez des patients hypertendus, fournissant un mécanisme potentiel d'activation de P2RX7. De plus, un polymorphisme hypomorphe pour P2X7 est corrélé à une diminution du risque d'HTA essentielle chez les femmes ménopausées chinoises. Les travaux rapportés dans cette thèse testent l'hypothèse selon laquelle P2RX7 médie l'élévation de …  Lire la suite

Abstract Studying the effect of temperature cycles on the mechanical behavior of geosynthetic material is essential for the analysis and design of reinforced soil structures in cold climate. High-strength fiberglass geogrids are relatively new soil reinforcement materials that have improved properties with a potential for a wide range of applications. This research involves a preliminary experimental investigation that has been performed to examine the effect of temperature cycles on the response of two different biaxial geogrid materials, namely polymeric and stiff fiberglass geogrids. A total of seventy-two single ribs of the two types of geogrids were subjected to different thermal …  Lire la suite

Cette thèse étudie le potentiel d'utilisation des géogrilles en fibre de verre pour améliorer les performances des dalles de béton au sol dans des conditions environnementales difficiles, en particulier dans les régions froides. La recherche est motivée par les limitations des renforcements en acier conventionnels, qui sont sensibles à la corrosion et à la dégradation dues aux fluctuations extrêmes de température et aux cycles de gel-dégel, nécessitant des techniques de renforcement plus durables.La première partie de cette étude se concentre sur la compréhension de l'effet de la température sur la réponse en traction des géogrilles en fibre de verre haute …  Lire la suite

There has been an escalating demand for dynamically reconfigurable photonic structures to implement any linear optical transformation between the input and output ports. Such devices are often constructed as a mesh of reconfigurable Mach-Zehnder interferometers(MZIs). Consequently, the programmed MZIs can redistribute the light to implementarbitrary unitary transformations from an input vector of optical signals to an outputvector of coherent optical modes. These structures have been widely used as a promising hardware platform for fast and energy-efficient matrix multiplications in different applications, such as information processing, machine learning algorithms, neural networks(NNs), etc. Matrix multiplication is an essential but time- and energy-consuming …  Lire la suite

A modeling technique for simulating the fatigue behaviour of laminated composite materials with or without stress concentrations, called progressive fatigue damage modeling, is established. The model is capable of simulating the residual stiffness, residual strength and fatigue life of composite laminates with arbitrary geometry and stacking sequence under complicated fatigue loading conditions. The model is an integration of three major components: stress analysis, failure analysis, and material property degradation rules. A three-dimensional, nonlinear, finite element technique is developed for the stress analysis. By using a large number of elements near the edge of the hole and at layer interfaces, the …  Lire la suite

In this investigation the behavior of pin-loaded composite plates is studied analytically. A progressive damage model is presented which is capable of predicting the three different mechanisms of failure: bearing, shearout, and net tension. The model consists of three major parts: stress analysis, and material property degradation rules. Based on the model a computer code is developed. The computer code is capable of assessing damage, evaluating residual strength, and predicting ultimate strength of pin-loaded composite plates. Predicted results are compared with available experimental data. Excellent agreement between the predicted and the experimental data was found. The computer code is used …  Lire la suite

Les dispositifs électroniques traditionnels à base de silicium sont limités par leur rigidité et leur fragilité, ce qui les rend inadaptés à la demande croissante en appareils flexibles et portables. Les transistors à couches minces flexibles (TFTs) représentent une alternative prometteuse, les TFTs à nanotubes de carbone à paroi simple (SWCNT) se distinguant comme une option économique et performante pour l’électronique flexible. Dans cette étude, des TFTs à double grille à base de SWCNT ont été fabriqués en utilisant une méthode par dépôt en solution afin d’évaluer l’impact du PDMS en tant que diélectrique de grille flexible, en complément du …  Lire la suite

La maladie de Parkinson (MP) est une maladie neurodégénérative dévastatrice quitouche de plus en plus notre population vieillissante. La forme juvénile autosomiquerécessive de la MP est causée par des mutations de perte de fonction dans des protéines,dont la kinase PINK1. Sous des conditions physiologiques, PINK1 est responsable de ladétection des lésions mitochondriales et du déclenchement des voies de renouvellementdes mitochondries. La modulation de PINK1 par de petites molécules pourrait aider àrétablir la fonction de la kinase et constituer un outil de recherche important dans la MP.Notre objectif est de caractériser des petites molécules inhibitrices de PINK1 commepoints de départ pour …  Lire la suite

Introduction: En 2020, le Canada a consacré 12,9 % de son PIB aux soins de santé, dont 3 % aux dispositifs médicaux. L'adoption précoce de dispositifs chirurgicaux innovants est principalement le fait des médecins et un retard dans l'adoption peut priver les patients de traitements médicaux importants. De nombreux chirurgiens au Canada ont des priorités et des critères différents pour fonder leurs décisions concernant l'adoption d'une nouvelle technologie chirurgicale innovante dans leur pratique. Cependant, l'absence de critères unifiés fondés sur des données probantes pour les décisions d'adoption de technologies au stade précoce au Canada affecte la qualité des soins de …  Lire la suite

The hypothalamus is that part of the forebrain which forms the floor of the third ventricle in immediate topographical relation with the pituitary gland (1). The limiting boundary of the hypothalamus is ill-defined. It extends, without any sharp line of demarcation, into the parolfactory region of the telencephalon anteriorly and into the tegmental part of the mid-brain posteriorly. Laterally the hypothalamus is direct1y continuous with the subthalamus (1). [...]  Lire la suite

Cette thèse offre une traduction et une translittération d'un texte datant de la fin de l'ère Meiji sur les arts martiaux, Moral Instruction in Budo (1912), ainsi qu'une étude sur l'auteur, Chiba Chosaku (1861-1935). L'objectif visé consiste à conceptualiser la pensée de Chiba dans la perspective des événements historiques et des courants idéologiques de son époque, en vue de faciliter une meilleure compréhension de sa véritable contribution. Chiba défendait l'idée que la pratique des arts martiaux (budo) soit la manière de maintenir et de transmettre l'éthique religieuse martiale (bushido) dans la condition moderne du Japon occidentalisé. L'oeuvre de Chiba prend …  Lire la suite

This study is designed to evaluate water diffusion parameters of clay based buffer material (mixture of clay and sand) used in nuclear fuel waste disposal vault for the following three cases: (a) No volume change in the soil fabric with no air loss. (b) No volume change in the soil fabric with air loss. (c) A complete change in the soil fabric with air loss. One dimensional diffusion type unsaturated flow equation was solved by finite difference method. Powell's optimization technique was used to minimize the material parameters in the proposed diffusion function. The adopted technique makes the use of …  Lire la suite

Experimental and numerical studies of coupled heat and moisture flow induced in an unsaturated soil by simultaneously imposed temperature and hydraulic gradients, in opposite directions, are presented. The experimental portion of the study was designed to provide information on the moisture and temperature distributions in relation to elapsed time and distance from the heat source. Tests were conducted on three different materials: (a) buffer (equal proportion of silica sand and sodium bentonite), (b) backfill (25 percent low swelling clay and 75 percent crushed granite rock), and (c) sand. Each material was compacted to its maximum dry density and optimum water …  Lire la suite

L'influence modulatrice du système cholinergique local et des prostaglandines d'origine endogène sur l'activité contractile induite par l'histamine furent étudier in-vivo et in-vitro chez le muscle lisse des voies aériennes du chien. In-vitro l'atropine et la tetrodotoxine ont eu pour effet de diminuer, alors que la neostigmine a eu pour effet d'augmenter la force contractile du muscle lisse de la trachée (MLT) en réponse a l'histamine. Un autre effet de l'atropine fut une diminution des changements de la conductance pulmonaire produite par l'inhalation d'histamine chez le chien anesthesié et après vagotomie bilatérale. Les résultats démontrent que la libération locale d'acétylcholine, indépendamment …  Lire la suite

Several stochastic and sampling processes leading to the logarithmic series distributions and related distributions are studied. An attempt has been made to present a unified picture, using a single notation, of the various derivations and approaches that appear in the literature. These derivations and approaches are compared and some of the relationships among them are brought out. Though the work is mainly interpretative, there are a few results that seem to be new.  Lire la suite

Witcher, Michael (Supervisor1)  Lire la suite

A model, two-dimensional leak-proof, heat exchanger was built. Local shell-side, heat transfer coefficients were measured in a typical section between two segmental baffles. Three baffle spacings, with five flow rates at each spacing, were used. The results indicate that the crossflow region can be divided into a dead zone and flow zone. The size of these sub-zones is a function of the area ratio, Ar, and thus the average coefficient is also a function of Ar.  Lire la suite

There is a growing awareness of the inadequacy of the traditional framework of international law as a means of dealing with current environmental problems. This has led to calls for a new approach. In view of the links between the protection of the environment and the protection of human rights, one such approach has been to focus on the development of international human rights law concepts and mechanisms to address environmental concerns. This thesis undertakes a critical assessment of a human rights approach to environmental protection, with the aim of suggesting ways in which it could realistically contribute to the …  Lire la suite

The aim of this research was to enhance existing knowledge about the runaway child in order that guidelines for future preventive work be considered.The study was conducted at the Children's Service Centre, Montreal, and covered the period from June ,30, 1962 to June 30, 1963. The sample consisted of 25 foster children, all of whom were in care at the time of the runaway episode. [...]  Lire la suite

This thesis examines the social and pedagogical challenges of implementing Québec's Ethics and Religious Culture program (ERC). This program advocates multi-religious instruction as a means toward social harmony at a time when people from differing religious cultures increasingly co-exist. In this context there is a crucial need for children to learn about the culture and religious beliefs of others. The distinct culture and religious history of Québec makes it a unique setting for such a program. The thesis examines the strained and complex feelings regarding religion that have pervaded Québec society since the Quiet Revolution. In the end the thesis …  Lire la suite

The solvolysis of a given compound I, where G is the neighbouring group and X a group which readily departs with the electron pair, thereby generating a carbonium ion, brings into play varying effects. The neighbouring group can compete with the solvent or other dissolved nucleophilic agents sufficiently well to determine partially or wholly the nature of the final products. Neighbouring groups are classified as functional, for example bromide, iodide, methoxy and acetoxy, or non-functional, e.g., alkyl, vinyl, aryl and hydrogen. In the case of neighbouring carbon, the amount of activation energy involved in the rearrangement must be small for …  Lire la suite

Ce mémoire présente un modèle graphique et mathématique du conflit dyadique dans le domaine de la sécurité internationale. Le modèle permet d'interpréter la course aux armements et le déclenchement des guerres dans un cadre formel. Le modèle est construit a partir de concepts rigoureusement définies et nos postulats ont été présenté de manières explicites. Les valeurs d'équilibre pour une course aux armements voulant assurer la sécurité nationale sont prédits à partir du modèle et comparé aux valeurs produites pour une course aux armements avec des objectifs de conquête. Différents résultats d'analyse statique sont comparés pour différentes perturbations du modèle de …  Lire la suite

This study was conducted to understand the interactions between irrigation water management and water quality (agro-ecological interactions). The Uda Walawe basin, in Southern Sri Lanka was chosen as the study area. Fluctuations in water quality, especially microbiological water quality, affect human health. Since the source of domestic water (drinking and washing) in this region is from the irrigation system, there is a concern for the human health effects. All the potential water sources and the water use habits of the community were identified. The water quality of these sources was then monitored for a period of 5 months (August--December 2000). …  Lire la suite

The distinction between emotions expressed by and evoked by music is often blurred by the use of methodologies that are difficult to compare, preventing progress towards a unifying theory of emotion and music. In this thesis, a methodology for experimentation that clarifies how research in these areas can be conducted clearly and independently is proposed. The study of evoked emotions is emphasized, and two novel controllers are developed to examine methods of recording emotional response continuously. These controllers, along with a number of the proposed methodological changes, are tested against an established controller in an experiment designed to record emotional …  Lire la suite

Hibbert, H. (Supervisors)  Lire la suite

This thesis presents methods for supervised and unsupervised speaker adaptation of Gaussian mixture speaker models in text-independent speaker verification. The proposed methods are based on an approach which is able to separate speaker and channel variability so that progressive updating of speaker models can be performed while minimizing the influence of the channel variability associated with the adaptation recordings. This approach relies on a joint factor analysis model of intrinsic speaker variability and session variability where inter-session variation is assumed to result primarily from the effects of the transmission channel. These adaptation methods have been evaluated under the adaptation paradigm …  Lire la suite

This thesis will trace the development of Conservative ideology in Great Britain between 1906 and 1914. During these years the Conservative party was defeated by the Liberal party on three separate occasions. Many historians believe that this string of electoral contretemps offers convincing evidence that Conservatism, as an evolving pattern of beliefs, was fundamentally unsuited to the political climate of Great Britain at the turn of the century. According to this interpretation of Edwardian Conservatism, it was only the timely onset of war which saved the party from having to come to terms with the democratic impulse of an unfamiliar …  Lire la suite

A leading hypothesis for the etiology of multiple sclerosis (MS) is that a delayed infection by Epstein-Barr Virus (EBV) generates an abnormal immune response, thereby inducing the disease. EBV is ubiquitous. While asymptomatic in children, the infection produces the clinical entity infectious mononucleosis (IM) when it is delayed until adolescence or young adulthood. Typically, case-control studies have measured exposure to EBV by serology assaying EBV antibodies or by IM self-report. The findings of these studies are not consistent. Part of the problem in establishing a definite causal relationship between EBV and MS in case-control studies is related to exposure measurement …  Lire la suite

Superantigens (SAgs) are bacterial (bSAgs) or viral (vSAgs) proteins that can trigger a large number of T lymphocytes bearing specific Vbeta regions. This results in either anergy or deletion of those activated T cells. SAgs have long been implicated in various disease as well as autoimmune conditions. SAgs require binding to the Major Histocompatability Complex (MHC) class II molecules on antigen presenting cells (APC) to be presented to their responsive T cells. The work presented in this thesis represents a study of the different cellular factors implicated in MHC class II maturation pathway that could affect its ability to present …  Lire la suite

This thesis presents the first fully integrated array of high-voltage (HV) digital-to-analog converters (DACs). It was designed in DALSA Semiconductor's 0.8mum CMOS/DMOS HV process technology. The 6-bit 300V DACs are based on a current-steering, thermometer coded architecture. Two designs adapted to the HV technology are proposed for the current-to-high-voltage conversion as traditional output resistor or op-amp solutions are not optimum for the HV process: one uses a high-compliance current mirror, while the other uses a simple current mirror. The DACs show a DNL of 0.16LSB and 1LSB, respectively, while the INL profile is 0.16LSB and 13LSBs for the first and …  Lire la suite

Cryptococcus neoformans, la principale cause de la cryptococcose humaine, est une levure encapsulée répartie de façon omniprésente dans l'environnement. Chez les individus atteints d'une réponse immunitaire défectueuse, la réplication incontrôlée de C. neoformans dans le poumon peut entraîner la dissémination dans d'autres parties du corps avec un tropisme pour le cerveau. Des facteurs génétiques encore non-caractérisés pourraient jouer un rôle important dans la détermination de la susceptibilité à une infection progressive. Le but général de ce projet de doctorat était de disséquer les aspects génétiques et immunologiques de la susceptibilité de l'hôte à C. neoformans en appliquant des méthodes d’investigations …  Lire la suite