McGill University Theses and dissertations by author name (P)

L'inférence bayésienne computationnelle a de nombreuses applications dans plusieurs branches du domaine de traitement du signal et de l'apprentissage automatique. Les techniques bayésiennes permettent une modélisation fondée sur des principes de l'incertitude dans la conception des algorithmes d'inférence et offrent de meilleures performances empiriques que leurs homologues non bayésiennes dans divers contextes. Cependant, la distribution postérieure de la quantité d'intérêt n'est pas traitable analytiquement dans la plupart des tâches d'inférence pratiques. L'approximation de la distribution a postériori à l'aide des méthodes de Monte Carlo permet de mettre en œuvre des approches bayésiennes pour ces cas-ci. De telles approximations nécessitent souvent …  Read more

La résistance généralisée aux antibiotiques et le manque de nouveaux antibiotiques motivent les scientifiques à rechercher de nouvelles cibles pour lutter contre les infections bactériennes. Bien que le bon fonctionnement des ribosomes soit une cible antibiotique courante, notre manque de compréhension de son processus d’assemblage nous empêchés de développer de nouveaux antibiotiques qui ciblent ce processus. Une classe unique et hautement conservée de GTPases, appelées GTPases d'assemblage de ribosomes, joue un rôle essentiel dans l'assemblage de ribosomes des bacteries. Comment ces GTPases interagissent avec les intermédiaires immatures de ribosome et les étapes de maturation qu'elles catalysent sont des questions cruciales …  Read more

Over the last 60 years, technology for harvesting solar energy has been extensively developed and used. Examples of applications incorporating this technology include the following: heating and cooling of residential and commercial buildings; solar water heaters; photo-voltaic conversion to electricity; solar-thermal-electric power generation; and solar desalination of seawater. In parallel, thermal energy storage (TES) systems have also been extensively developed and employed for enhancing the efficiency of energy conversion systems, typically by matching thermal energy supply and demand during summer-winter, day-night, and peak-off-peak periods. In this work, the focus is on computational modeling of flat-plate solar-thermal collectors and sensible diurnal …  Read more

Rentschler, Carrie (Supervisor2)  Read more

The Food Habits of Canadians Survey, conducted in 1997--1998 examined food and nutrient intakes of non-institutionalized adults aged 18--65 years (n = 1543) randomly selected from across Canada using the multi-stage random sampling strategy. Dietary intake was assessed by 24-h recall and a repeat interview was conducted in a sub-sample (n = 446). The overall response rate was 26%. Males, younger age adults (18--34 years), single persons and those with lower education levels were underrepresented in the study sample thus limiting the generalizability of the study results. Examination of the characteristics of the selected areas (n = 63) by response …  Read more

Glioblastomas are aggressive brain tumors that invade normal brain parenchyma and spread wider quickly. Primary GBMs, which are usually detectable in elderly patients, grow rapidly de nova without precursor pathological lesions or and clinical symptoms1.Secondary GBMs are diagnosable and develop from low-grade astrocytoma for about 5-10 years. Patient cohort astrocytoma samples were used for initial promoter DNA methylation analysis using Infinium ®HumanMethylation450 BeadChip. Methylation states on 12 wild type Isocitrate dehydrogenase 1 (WT-IDH1) and 9 mutant Isocitrate dehydrogenase 1(MUT-IDH1) astrocytomas were compared. Results displayed in a heat map showed that the MUT-IDH1 tumors are hypermethylated relative to WT-IDH1 tumors. Mann-Whitney-Wilcoxon …  Read more

Orsat, Valérie (Internal/Supervisor)  Read more

Les nanotubes de carbone (CNT) ont connu une vague de popularité depuis les 20 dernières années. L'industrie des matériaux composites a développé un intérêt marqué pour leur utilisation dans des applications haute performance, telles que les fibres thermoplastiques. Par contre, une revue de la litérature a démontré qu'il y avait un manque d'information concernant le lien entre le comportement rhéologique des CNT-polymères et la facilité de fabrication par filage à l'état fondu. Dans ce travail, une méthodologie détaillée pour incorporer des nanotubes de carbone (CNT) dans des fibres thermoplastiques et relier leurs propriétiés mécaniques à leur qualité de surface et …  Read more

The automotive industry is increasingly using resin transfer moulding (RTM) to produce composite body panels at high volumes and low costs. However, one of the recurring issues is the control of the parts surface finish, which is closely linked to the resin volumetric changes during cure. These volumetric changes are caused by the resin cure shrinkage and thermal expansion which depend on material and processing parameters. Low profile additives (LPA) are thermoplastic particles incorporated to unsaturated polyester (UP) resin to compensate for cure shrinkage. The effect of LPA content and degree of cure on the volumetric cure shrinkage and the …  Read more

Schizophrenia research over the years has documented evidence of structural neurodevelopmental abnormalities in the hippocampus and functional aberrations at the level of the prefrontal cortex. Rats with neonatal ibotenic acid lesions in the ventral hippocampus (nVH) mirror some of these disruptions and it is believed that these lesions may lead to structural and/or functional reorganization within cortical circuits (Lipska et al., 1993; Flores et al., 1996). Our laboratory has provided evidence of increased cortical alpha-1 adrenergic receptors in nVH lesioned animals. To further assess the possible role of these receptors in amphetamine-induced hyperlocomotion exhibited by nVH lesioned animals, the effect …  Read more

Out-of-autoclave prepreg contains partially impregnated fibre tows which act as paths for gas evacuation. The degree of impregnation of resin into the dry fibre bed is a quantitative measure of the size of these dry fibre pathways and can affect part quality and rejection rates. There is no well-defined and accurate standard method to measure this quantity. The current state-of-the-art is to manufacture discriminator panels, which are panels containing complex features such as tight radius corners, internal ply drop-offs, sandwich regions, etc. to determine the producability of specific components by specific material. That is, it is an empirical method used …  Read more

We study the aggregation equation $\rho_t + \nabla \cdot (\rho (-\nabla K \ast \rho)) = 0$ in $\Real^n$, a first-order nonlinear and non-local transport equation used to model swarming behaviour. The radial interaction potential is chosen $K$ to model both short-range repulsion and long-range attraction. We show global-well-posedness of solutions using the particle-trajectory method, a technique first used for the proving global existence and uniqueness of the Euler equation. Specifically, the interaction kernel is selected in order to calculate an analytic solution of density along particle trajectories and to make use of the well-developed theory of singular integral operators. We …  Read more

itions. Le profil des raies est rarement discuté, bien qu'il révèle les fluctuations et le désordre du système. L'analyse des profils de raies est d'une efficacité particulière en spectroscopie bidimensionelle (2D), qui résout ce profil selon plusieurs axes temp-fréquence. Dans certains cas, la dynamique de profil met à nu les processus à l'origine du déphasage. C'est le cas du couplage à aux dynamiques vibrationnelles cohérentes. En général, les profils et leur dynamiques fournissent des indices supplémentaires sur les dynamiques électroniques. L'interprétation du profil des raies spectrales requiert une solide fondation théorique, qui ouvre l'ouvrage. S'ensuit la présentation d'un spectromètre 2D …  Read more

This thesis outlines the implementation and testing of a binocular active vision system. Emphasis is placed on the bilateral gaze controller that allows the robotic system to perform specific orienting tasks. The gaze controller, based on existing biological gaze control systems, is capable of tracking a moving target by integrating smooth pursuit and saccadic modes of operation. Furthermore, the controller is able to gracefully fuse eye and head movements without the need for a separate head controller. This work represents the first time a head platform has been implemented with the bilateral gaze controller. Experiments and simulations that yield the …  Read more

Schmidt, Alexandra (Supervisor2)  Read more

L'éducation est un sujet qui a passionné de nombreux intellectuels du dix-huitième siècle. Si à l'époque, les traités pédagogiques étaient majoritairement théoriques, certains philosophes font appel à la fiction pour rendre leurs ouvrages plus accessibles. C'est le cas de Jean-Jacques Rousseau dans Émile, ou de l'éducation (1762) et de Louise d'Épinay dans Les conversations d'Émilie (1782). Pour présenter leurs idées novatrices sur l'éducation, le premier crée un texte hybride entre le traité et le roman alors que la seconde choisit le dialogue pour mettre en scène vingt conversations entre une mère et sa fille. Si les deux œuvres apparaissent donc …  Read more

Ma thèse a pour objectif de cerner les raisons qui incitent les élites/leaders gouvernementaux à perpétrer des massacres en s'appuyant sur les hypothèses du modèle stratégique, en cherchant à les affiner et à les soumettre à rude épreuve. Le modèle stipule que le massacre fait partie d'une politique instrumentale descendante rationnelle utilisée par les dirigeants pour combattre les menaces à leur pouvoir. Par conséquent, les massacres présentent une forte corrélation avec la remise en cause du pouvoir des élites, comme les assassinats, les guerres et les coups d'État. Si cette théorie jouit du plus grand soutien académique, elle présente trois …  Read more

Frost, David (Internal/Cosupervisor2)  Read more

The characteristic feature of non-volatile solid fuel suspensions is the absence of a continuous premixed gas flame front. Instead, the reaction is localized to or near the surface of individual particles. This “flame-within-a-flame” structure gives rise to a multi-faceted combustion process, whose dynamics are governed by a range of underlying mechanisms. To understand the combustion of solid fuels, fundamental studies often explore the different “facets” of the process. This approach is used in the present thesis which examines two such mechanisms – front coupling and heat locking – and interprets them via simple formulations based on thermal considerations.Front coupling governs …  Read more

Le gène nommé microseminoprotéine, associé à la prostate (MSMP), également connu sous le nom de microseminoprotéine sécrétée par les PC-3, code pour une petite protéine sécrétée qui comporte une certaine homologie avec la β-microseminoprotéine. Des études récentes ont classé la MSMP comme un ligand pour le récepteur CCR2 (C-C chemokine receptor type 2). Bien que la MSMP ait été initialement identifiée comme une protéine spécifique de la prostate, notre groupe a découvert que le gène Msmp est surexprimé dans un modèle murin d'ostéogenèse imparfaite (OI) de type V. L'OI de type V est une dysplasie osseuse autosomique dominante causée par …  Read more

A novel reaction for the dehalogenation of aryl halides is discussed in terms of its stoichiometry, mechanism, yields and potential for analytical purposes. The active dehalogenation reagent can be prepared through the reaction of molten potassium with polyethylene glycols (MW $>$ 200), in the absence of oxygen, to form the corresponding potassium glycolate, a powerful nucleophilic agent. This reaction is applied to the determination of PCBs in waste oils. Following dechlorination, the reaction sample is analyzed for chloride using a flow-injection analysis system employing a novel thin-layer amperometric detector with a silver working electrode. The liquid chromatographic retention behaviour, separation …  Read more

Antiphospholipid syndrome (APS) is defined by the presence of antiphospholipid antibodies (aPL) and clinical manifestations. It is unclear why some patients have high levels of aPL, but no clinical symptoms, while others develop APS. Recent studies have demonstrated T cell reactivity to beta2-glycoprotein I (beta2GPI) in patients with APS. To understand why a T cell response develops selectively in some individuals the requirements for antigen presentation and T cell reactivity were evaluated in a murine model of aPL induction. aPL were readily induced in immunized mice, and required MHC class II, but not CD1, antigen presentation. In contrast, induction of …  Read more

Therapeutic options for the treatment of breast cancer have long been limited to invasive surgical procedures, or chemo- and radiotherapies that are plagued with detrimental side-effects. Selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, are a large subclass of molecules that have been used in adjuvant therapies and have provided substantial clinical benefits as preventative and long-term treatment options. Despite their success, endocrine therapies face several challenges including the development of endocrine resistance and, in the case of tamoxifen, the increased risk of endometrial cancer. Recent studies have shown that dual administration of SERMS and histone deacetylase inhibitors …  Read more

The primary purpose of this study is to determine if three coping strategies (exercise, hobbies, and social support) were related to some or all of the three dimensions of burnout (Emotional Exhaustion, Depersonalization, and Personal Accomplishment). One hundred and forty-three secondary school teachers from schools in urban and suburban areas of Eastern Canada participated in this study. The Maslach Burnout Inventory was used to assess burnout scores and a coping strategies questionnaire was used to assess participation in activities. Exercise and social support were positively related to the Personal Accomplishment dimension of burnout.  Read more

The work described in this thesis is divided into two parts. Part I is concerned with the volume fraction estimation of phases in metallurgical microstructures. A rapid method of phase analysis, using a modified form of point counting, is described and experiments on various kinds of cast irons are reported. [...]  Read more

Bussey, Dr. Howard  Read more

Metabolic plasticity allows cancer cells to adapt to energetic and environmental stresses. The mitochondria play a key role in metabolic flexibility of cancer cells by providing energetic and biosynthetic resources needed for neoplastic growth, metastasis, and therapeutic resistance. However, the molecular mechanisms that are exploited by cancer cells to adapt to energetic stress are incompletely understood and constitute an intense area of investigation. Through the use of genome-wide CRISPR-Cas9 screens, we uncovered genes whose loss confers reduced susceptibility to various mitochondrial poisons. Ras GTPase-activating protein-binding protein 1 (G3BP1) emerged as one of the top candidate genes whose loss is protective …  Read more

Ligand-dependent corepressor LCoR was discovered almost ten years ago in the laboratory of Dr. John White through a yeast two-hybrid screen in which the ligand binding domain (LBD) of the estrogen receptor alpha (ERalpha) was used as bait. LCoR represses gene transcription by recruitment of the corepressor C-terminal binding proteins (CtBPs) and histone deacetylases (HDACs) through distinct domains. The action of HDACs strengthens the interactions of histones with negatively charged DNA resulting in stable nucleosomal and chromatin structures and repression of transcription. CtBPs interact with many transcriptional repressors through a common motif P/VLDLS/TXK/R, of which there are two in LCoR. …  Read more

Milot, Marie-Helene (Supervisor2)  Read more

Contexte: L’hétérotopie nodulaire périventriculaire (l’HNPV) est une malformation congénitale du cerveau qui est caractérisée par des amas nodulaires de matière grise anormales dans la région autour des ventricules latéraux. L’HNPV est associée avec l’épilepsie chez des personnes atteintes de ce maladie, et présentement, l’épilepsie de type HNPV est considérée comme résistantes aux médicaments. La littérature existante est cependant limitée et, par conséquent, l'épileptologie n’est pas bien connu. Objectifs: Nous avons cherché à clarifier le spectre des phénotypes d'épilepsie chez l’HNPV et l'importance de modèles plus spécifiques de malformation cérébrale afin de pouvoir fournir aux cliniciens des recommandations judicieuses pour le …  Read more

Growth factor receptor tyrosine kinases (RTKs) are critical initiators of signal transduction pathways necessary for cell growth, differentiation, migration and survival. Many of these signals are coordinated through scaffold proteins that are phosphorylated upon their recruitment to the activated receptor complex. This provides binding sites for multiple proteins to activate and generate distinct biological responses. The amplitude and duration of a signal is regulated via dephosphorylation and degradation of target proteins. Signal regulation in this manner acts to promote the formation and disassembly of multi-protein complexes and diversify and localize signals downstream from RTKs. The Met RTK and its ligand, …  Read more

Alcohol affects many neurochemical processes, causing long-lasting changes in both the adult and developing brain. The Jak-Stat transcriptional activation pathway plays a role in the control of neuronal proliferation, survival and differentiation, but the effects of ethanol on the system have not been fully elucidated. The goal of this project was to define the effects of acute and subchronic ethanol exposure on the expression of proteins in the Jak-Stat pathway, using cultured NG108-15 cells, and in addition, to test the hypothesis that these effects are mediated through the NMDA receptor. I found that ethanol dose-dependently decreased Jak2 and Stat3 following …  Read more

Early Drosophila development is a coordinated series of temporal and spatial events leading to specific localized gene expression. The maternally expressed gene Bicaudal-C (Bic-C) encodes a KH-domain RNA binding protein required in the developing oocyte for anterior-posterior patterning and follicle cell migration. The dominant heterozygous phenotype results in the development of embryos with bicaudal and head defects. A two-hybrid screen using BIC-C as "bait" identified the novel protein ANTIMEROS (ATMS) and the SH3-domain containing protein MILE END (MILE). ATMS is highly conserved between humans and mice, its expression is almost entirely female-specific, and is limited to certain developmental stages. Mutant …  Read more

Le pancréas artificiel est une technologie émergente pour traiter le diabète de type 1. Le pancréas artificiel, également appelé un système d'administration d'insuline en boucle fermée, comprend trois dispositifs: une pompe à insuline, un moniteur de glucose en continu et un algorithme de contrôle qui module l'administration de l'insuline en fonction des taux de glucose. L’objectif du pancréas artificiel est d’améliorer le contrôle glycémique, de diminuer les faibles taux de glucose dans le sang et de réduire le fardeau des patients en répondant à la variabilité des taux de glucose en modulant la délivrance d’insuline en temps réel. La détermination …  Read more

Les alliages de magnésium ont fait l'objet de recherches actives notamment dans l'industrie automobile pour concevoir des véhicules légers afin de parvenir à une meilleure efficacité énergétique et réduire les gaz à effet de serre. Le contrôle de la microstructure de coulée d'alliages de magnésium est essentielle, car de nombreux composants automobiles sont faits d'alliages de magnésium et utilisées dans leur forme brute. Même pour les alliages de magnésium forgé, la compréhension de la microstructure de coulée est très importante pour optimiser les processus en aval tels que l'homogénéisation, le laminage et le recuit. Le développement de la microstructure au …  Read more

In recent years the magnesium application in automobile sector has been increasing. Recent research and development studies of magnesium and its alloys have focused on weight reduction, energy saving and limiting environmental impact. In this regard researchers have identified incorporating certain key alloying elements like Al, Zn, Si, Pb, Ge, Bi, Sb, Sr, etc. to the magnesium alloys.These alloying elements are seen as potential elements for novel magnesium alloy design with superior structural properties to the existing alloys used for automotive applications. The continued developments in CALPHAD (Chapter 2) assessment of alloys (and other materials) brought about the development of …  Read more

Bien qu’actuellement impliqué dans des considérations liées à la sécurité, le glyphosate est un herbicide largement utilisé et efficace. On sait que le glyphosate provoque une certaine diminution du taux de photosynthèse des plantes tolérantes au glyphosate pendant une certaine période après l'application, probablement en raison d'un niveau de toxicité faible, entraînant un stress pour les plantes. L'acide salicylique (AS) est une hormone végétale impliquée dans la coordination des réactions des plantes au stress. L’objectif général de ce travail était de déterminer si l’application de l’acide salicylique pouvait inverser les effets négatifs du glyphosate sur le taux de photosynthèse des …  Read more

A new type of adiabatic electrical calorimeter has been designed for use at high pressures, by means of which the heat capacities of gases at constant volume can be determined over short temperature ranges with an accuracy of about 0.2%. The arrangements are such that the lags occurring after a change in temperature in the critical region can be followed, and their effect as an error in the heat capacity measurement eliminated. A very efficient low temperature fractionating unit has been constructed, in order to assure the purity of the material used. The heat capacity of ethylene has been determined …  Read more

Fellows, Lesley K (Internal/Cosupervisor2)  Read more

The ability to accurately identify individuals is required for the detailed study of animals. Numerous artificial markers have been developed for this purpose. Negative effects on survival, reproductive success and behavior have been reported for most marking methods, significantly affecting the very parameters being studied. Birds of prey have suffered the shortcomings of artificial marking methods. In light of the known and potential deleterious effects of marking, attention has been focused on developing new techniques to identify individual raptors without attaching artificial markers. This study investigated the use of tarsal scale patterns as unique individual identifiers in birds of prey. …  Read more

Language learning crucially depends on the long-term memory storage and on the updating of our linguistic representations. Thus, a fundamental question in psycholinguistic research is how novel linguistic representations become integrated in long-term memory stores (i.e., consolidation). Computational accounts of this phenomenon suggest that the timing of this process is dependent upon pre-existing linguistic representations. However, most research on this topic has focused on native English speakers, presumably monolingual. Interestingly, a separate research stream suggests that bilingualism shapes linguistic and metalinguistic skills relevant to novel language learning. Here, I sought to bridge these two areas of the literature by focusing …  Read more

Nanostructures, molecular assemblies at the nanometer scale, are currently influencing diagnostics, imaging, and therapeutics. Many nanostructures are built using supramolecular chemistry principles, where hydrogen bonding between simple building blocks causes the formation of specific morphologies. Here we hypothesize that a six stranded DNA nanotube can be generated by tethering triaminopyrimidine and cyanuric acid building blocks as bases on the natural DNA backbone. We also hypothesize that cyanuric acid, a secondary oxidation product of guanine, will form complex architectures with adenine, its natural hydrogen bond complement. To test these hypotheses, we used multi-step synthetic strategies to generate DNA strands of cyanuric …  Read more

Le mariage d'enfants, que l'ONU définit comme toute union officielle ou informelle avant l'âge de 18 ans, constitue une violation des droits de la personne et une forme de violence fondée sur le genre. Les phénomènes météorologiques extrêmes peuvent faire augmenter le nombre de mariages d'enfants en aggravant les difficultés économiques, en réduisant l'accès à l'éducation et à l'emploi, et en augmentant les risques de violence sexuelle. Toutefois, les preuves quantitatives sur l'effet des phénomènes météorologiques extrêmes sur le nombre de mariages d'enfants restent limitées. Ce mémoire a pour objectif d'examiner les études quantitatives existantes sur ce lien et d'estimer …  Read more

Previously, J. Lambek et al. have used Production Grammars to study the kinship terminology of English, Hindi, Sanskrit and Malagasy. This technique is applied here to the kinship terminology of Burmese and four closely related Indonesian languages: Indonesian, Javanese, Madurese and Sundanese. The production grammars are then compared, noting differences between Burmese and the others, and differences within the group of Indonesian languages. Particular attention is paid to the reduction rules, as they are indicative of the structure of the grammar. It was found that although differing in the structure of its kinship descriptions, Burmese is quite similar to the …  Read more