McGill University Thèses et mémoires publiés en 2007

This thesis numerically solves the tensor order parameter continuum theory equations for nematic liquid crystals to investigate liquid crystal texturing mechanisms during an isotropic to nematic phase transition in a bulk unstable isotropic phase and next to solid surfaces. The Time Dependent Ginsburg Landau equation with a Landau de Gennes Helmholtz free energy density description is used to predict the shapes, textures and defect mechanisms that occur in the expanding droplets and films of a 4'-pentyl-4-cyanobiphenyl (5CB) nematic phase immediately after their nucleation from an unstable isotropic phase, due to a temperature quench. To create a robust simulation method able …  Read more

Les mouvements de la tête sont une source significative de dégradation de la qualité de l'image provenant de PET scans. Ils jouent un rôle particulièrement négatif avec les scanners PET à haute définition comme le HHRT (High Resolution Research Tomograph) qui possède une résolution approximative de 2,5 mm. Différents outils de stabilisation de la tête sont souvent utilisés afin de minimiser les mouvements, et le confort du sujet est essentiel pour obtenir des résultats fiables. Nous avons testé les mouvements du sujet au cours de longs scans (plus d'une heure) ainsi que la précision du repositionnement du sujet lors d'une …  Read more

We propose a linear mean square error channel estimator that exploits the joint space-time-frequency (STF) correlations of the wireless fading channel for applications in multiple-antenna orthogonal frequency division multiplexing systems. Our work generalizes existing channel estimators to the full dimensions including transmit spatial, receive spatial, time, and frequency. This allows versatile applications of our STF channel estimator to any fading environment, ranging from spatially-uncorrelated slow-varying frequency-flat channels to spatially-correlated fast-varying frequency-selective channels. The proposed STF channel estimator reduces to a time-frequency (TF) channel estimator when no spatial correlations exist. In another perspective, the lower-dimension TF channel estimator can be viewed …  Read more

Les effets de troubles de santé sur le bien-être d'enfants de même famille et sur lesrelations entre frères et soeurs furent évalués. Particulièrement, deux syndromes, lesyndrome de Phelan-McDermid et le Trouble du Déficit de l'Attention avec ou sansHyperactivité (TDAH), qui ont implications pratiques significativement différentes furentexaminés. Les entants de même famille ont complété des questionnaires sur leurfonctionnement émotionnel et comportemental, leur concept de soi et la qualité de larelation avec leur frère ou leur soeur. Pour les deux groupes d'enfants avec un frère ouune soeur atteinte d'un trouble quelconque, aucun effet positif ou négatif sur le bien-êtrefut découvert comparativement aux …  Read more

Les environnements virtuels immersifs peuvent procurer une interaction naturelle au sein d'un monde virtuel qui soit familière aux usagers car ils sont basés sur des actions de tous les jours. L'utilisation de tels environnements pour la représentation et le contrôle de sons 3-D reste largement inexplorée. On propose un nouveau paradigme pour l'interaction avec le son et l'utilisation d'un espace virtuel comme instrument pour le traitement spatial du son. Une architecture logicielle procurant des fonctionnalité qui ne sont pas disponibles dans d'autres systèmes pour sons 3-D a été développée, offrant un contrôle puissant sur la direction du son et la …  Read more

Damage in Multiple Sclerosis (MS) may be mediated by infiltration of immune cells into the central nervous system (CNS) and sustained due to failure of axons to regenerate. Little is known about the impact of immune cells on axonal regeneration. We demonstrate that peripheral blood mononuclear cells (PBMCs) have an inhibitory effect on neurite outgrowth dependent upon the cell subset and state of activation. Activated, purified CD3+ T cells inhibit outgrowth while untreated CD3+ cells and CD19+ B cells require pre-exposure to the cultured PBMC milieu. Neurons exhibited no evidence of cell death, indicating that the effect on outgrowth is …  Read more

The design and characterization of both electromagnetic bandgap (EBG) and inter-coupled split-ring resonator (SRR) structures utilized in microwave frequencies were proposed and studied. A new double-stopband EBG structure with a passband region of 14 to 18 GHz was initially constructed by determining the critical structural ratios. To reduce the size of EBG structure, a novel tapered array pattern was introduced. The structural period, the number of slot, and the length of slot were examined and a strong correlation was found between the lowpass cutoff frequency and the center slot length. Non-linearly tapered configuration was applied to enhance the filter performance …  Read more

Risk assessment of trace-metal contamination in soils requires predictive models that can accurately describe the complex uptake processes at the soil-plant interface, which are usually characterized by the coexistence of and interaction between multiple components. Competing cations such as Ca and H can affect metal availability to plants and subsequent rhizotoxicity. The biotic ligand model (BLM) has been proposed as a promising approach to model these interactive processes. Under the BLM assumption, we designed experiments to investigate how the solution chemistry is correlated with metal uptake and rhizotoxicity. Our first goal is to acquire a set of BLM parameters that …  Read more

Human cognitive processes, such as learning and memory, are particularly vulnerable to the effects of cortisol, the human stress hormone. In the field of magnetic resonance imaging (MRI) the different cortisol characteristics are neither controlled nor accounted for. This study will aim to investigate, by means of functional MRI, the effects of morning and afternoon cortisol levels on neural activation changes in response to a working memory task in young males. We hypothesized a significant difference between morning and afternoon subjects' cortisol levels and neural activation patterns in relation to the task. Nineteen young males were recruited, 9 for the …  Read more

Understanding the genetic control of gametogenesis is a central goal of developmental biology and is important for treating infertility in humans. An approach to identifying critical genes in mammals is to search for and study homologues of genes known to play key roles in other organisms. In the fly, Drosophila melanogaster, GUS protein is a component of nuage, an electron-dense aggregation in early germ cells, and is required for oocyte development. GUS physically interacts with VASA, an RNA helicase thought to regulate mRNA metabolism. I identified two murine genes, SSB-1 and SSB-4, that are similar to and likely homologues of …  Read more

The pure methods in a program are those that exhibit functional or side effect free behaviour, a useful property of methods or code in the context of program optimization as well as program understanding. However, gathering purity data is not a trivial task, and existing purity investigations present primarily static results based on a compile-time analysis of program code. We perform a detailed examination of dynamic method purity in Java programs using a Java Virtual Machine (JVM) based analysis. We evaluate multiple purity definitions that range from strong to weak, consider purity forms specific to dynamic execution, and accommodate constraints …  Read more

The dissertation examines the close but overlooked relationship between male poetry societies and the sharp rise of literary courtesans in the late Ming. I attempt to identify a particular group of men who devoted exclusive efforts to the promotion of courtesan culture, that is, urban dwellers of prosperous Jiangnan, who fashioned themselves as retired literati, devoting themselves to art, recreation, and self-invention, instead of government office. I also offer a new interpretation for the decline of courtesan culture after the Ming-Qing transition. Chapter 1 provides an overview of the social-cultural context in which late Ming courtesans flourished. I emphasize office-holding …  Read more

Batters are highly complex systems with wide ranging ingredients including flours, water, flavorings, and spices. Interactions between the ingredients determine the performance of batters and the final quality of coated products. Addition of hydrocolloids into batters of different types of flour provides special effects on batter performance. The functionalities of hydrocolloids-flour mixtures in terms of the thermal and rheological properties of the resulting batter systems were investigated in this study. The rheological properties of the batter were determined using a strain/stress control rheometer. A steady state method was used to measure the viscosity as a function of the shear rate …  Read more

Over the past several decades, the S. cerevisiae replication system provided excellent tools to study the initiation of DNA replication, and has built basic models to understand this process in higher eukaryotes. Therefore, identification and characterization of budding yeast replication initiation proteins, and their associations with replication origins, have significantly advanced our knowledge of eukaryotic DNA replication. Taking advantage of this tool, I studied the role of the cruciform binding protein CBP/14-3-3 in the regulation of the initiation of DNA replication in the budding yeast. CBP/14-3-3 was previously identified as an origin binding protein, and both its cruciform and origin …  Read more

First, we review the basics of baryogenesis and models for baryogenesis in the early literature. Then, we discuss the main theme in this thesis, electroweak baryogenesis, which utilizes the electroweak phase transition. We present how the phase transition can be used to achieve baryogenesis. Next, we develop our model, which is the Standard Model with a singlet field coupled to the Higgs doublet negatively and to the right-handed neutrinos. It is a simple extension of the singlet Majoron model. We focus on numerical analysis of the model. Parameter space satisfying all the conditions are found and relevant quantities, such as …  Read more

Since the "reform and opening-up" policy, Chinese society has been greatly affected by rapid industrialization, the installation of a market economy, and exposure to Western ideas and practices. These changes are having an impact on the current moral education program in varying degrees of intensity. The purpose of this thesis is to develop a framework for moral education in a meaningful and practical manner, and to provide an antidote to the current confusion regarding values in China. This thesis examines moral theories from both Eastern and Western perspectives. It focuses on Confucianism and Storytelling primarily. Confucianism, specially the Five Constant …  Read more

There is a class of plate buckling problems in which buckling occurs in the presence of a constraining medium. This type of buckling has been investigated by many researchers, mainly as buckling of elastic columns and plates on elastic foundations. Analytical solutions have been obtained by assuming the foundation to provide tensile as well as compressive reaction forces. The present work differs from the previous ones in two respects. One, the foundation is assumed to be one-sided, thus providing only the compressive resistance. Two, the plates are allowed to be stressed in the plastic, strain-hardening range. Equations for determining the …  Read more

Regulators of G protein signaling (RGSs) are negative regulators of G protein coupled receptors (GPCRs). Our lab has demonstrated that yeast Saccharomyces cerevisiae is a useful system to study RGS and G protein signaling. Mammalian RGSs can be expressed in yeast and favored to interact with mammalian GPCRs as well. Based on the observation that human RGS1 causes yeast cell growth arrest, I therefore used RGS1 expressing yeast cells to screen a mouse T cell cDNA library in order to find potential interacting proteins. From the screen, I identified a mouse sphingomyelin synthase 1 (SMS1) cDNA. By using a series …  Read more

Plant Breeders' Rights (PBR) are a form of intellectual property rights enabling breeders of new plant varieties to have the exclusive right to produce and sell propagating material of their new plant varieties. The existence of effective property rights has been pointed to as a stimulus of increased R&D and productivity. Canada has had legislation to provide PBR protection for about two decades, and is considering further strengthening of the regulatory framework. However, there are few studies that have examined the effectiveness of the legislation on crop productivity. This thesis investigates the hypothesis that the adoption of wheat varieties qualifying …  Read more

Previous studies have suggested that sympathetic sprouting in the periphery may contribute to the development and persistence of sympathetically-maintained pain in animal models of neuropathic pain. The purpose of this thesis was to examine morphological changes in the cutaneous innervation in rats after chronic constriction injury (CCI) to the sciatic nerve. More specifically, this study addresses the question of whether sympathetic fibres sprout de novo into the upper dermis of the rat hindpaw skin after CCI of the sciatic nerve. We also determined changes in peptidergic sensory innervation following CCI. At several periods post-injury, hind paw skin was harvested and …  Read more

Repeated exposure to amphetamine (AMPH) induces sensitization to its behavioral-activating effects. The development of sensitization depends on (1) the direct actions of AMPH in the ventral tegmental area (VTA), the cell body region of the mesocorticolimbic DA system, and (2) AMPH-induced glutamatergic neurotransmission in this region. Moreover, sensitization is accompanied by morphological changes in mesocorticolimbic DA circuitry. During development, the DA system is organized, at least in part, by the netrin-1 family of guidance cues. Both netrin-1 and its DCC and UNC-5 receptors continue to be expressed in the mesocorticolimbic DA system of the adult brain. Importantly, netrin-1 receptor deficient …  Read more

In this inquiry, I examine how six repatriated students from China perceive their experiences in Japanese schools and in Japanese second language education. I focus on their voices and perspectives gained through audio-taped interviews. Employing Pierce's (1995) concept of investment and Rampton's (1990) concepts of language expertise, affiliation, and inheritance, I focus on how these adolescent students perceive the relationship between languages and identities and how their experiences affect their ways of looking at themselves. The data I collected through interviews in Japan supports the views that identity is multiple and fluid, and languages are profoundly and intricately related with …  Read more

This study is intended to furnish an explicability of hunter-gather's organizational model on the lithic technology. The fieldwork area is the Imjin-Hantan River Area (the IHRA) located at the midwestern part of the Korean Peninsula. The archaeological sites included in the fieldwork are Jangsanri (ca 0.2 Mya BP), Chongokni (ca 60 Kya BP), Juwolri, and Kawolri (younger than ca 50 Kya BP). In addition, a previously excavated Upper Palaeolithic assemblage of Janghungri (ca 23 Kya BP) is included in the quantitative analysis of lithic assemblages. For the background of the research area, chapter II is devoted to demonstrating the general …  Read more

Polychlorinated biphenyls (PCBs) are a group of 209 chemical congeners that are toxic and persistent organic contaminants---they have been present in the environmental for several decades. Sites contaminated with PCBs pose serious health and safety risks to the surrounding environment due to their toxicity, persistence and bioaccumulation in creature. Polychlorinated biphenyls were commercially produced complex mixtures for a variety of applications. Before production was discontinued world-wide in 1977, several million tons of PCBs have been directly disposed to the soil. Researchers have been encouraged to develop novel techniques/approaches to detoxify PCB compounds and PCB contaminated soil. Ideally, these methods would …  Read more

Skeletal development is a complex event that requires a delicate balance between bone formation and bone resorption. Multiple transcription factors expressed in the bone-forming cells, osteoblasts, play crucial roles during the process of bone formation. Among them, ATF4 (Activating Transcription Factor 4) is a basic domain-leucine zipper transcriptional activator that is responsible for osteoblast differentiation, osteoblast-specific genes expression, synthesis of type I collagen, and osteoclast differentiation. Mice deficient for ATF4 are runted and exhibit severe skeletal dysplasia. Our laboratory has discovered Factor Inhibiting ATF4-mediated Transcription (FIAT), whose name was coined for its interaction with ATF4 and subsequent repression of ATF4-mediated …  Read more

Retrotransposition is an active process in mammalian gene evolution. It involves the reverse transcription of an mRNA transcript and the subsequent re-integration of the resulting cDNA into genomic DNA. This study was to derive a complete picture of the role of gene retrotransposition in the genome evolution of vertebrates, particularly in mammals. A robust procedure to annotate putative retrogenes (PRs) was applied to eight vertebrate genomes (human, chimp, dog, cow, rat, mouse, chicken and the puffer-fish T. nigriviridis). Mammalian genomes were estimated to contain 400-800 PRs (up to ~4% of genes). For the eight genomes studied here, no significant correlation …  Read more

Constant improvements in computer communications, microprocessors and operating systems are finally making wide-area public computing utilities (PCUs) a reality. The core idea of a CU is to connect resources that are geographically distributed and potentially heterogeneous into a single networked system such that clients can obtain on-demand the necessary resources for their computing needs from this system. Several PCUs have been created in the recent past using the Grid technology for both research and commercial purposes. Because PCUs often bring together resources from geographically distributed locations, they are ideally suited for applications that have geographically distributed resource demands. An example …  Read more

This thesis proposes an efficient power system simulator to estimate the automatic sequence of events that follow a fault contingency leading to islanding and cascading outages. The simulator is based on a quasi-steady state model that includes island identification, under-frequency load shedding, over-frequency generator tripping, and island load flow. Contingencies can include the outage of generators, loads, or transmission lines. Often times, a fault of one or two of these power system elements can lead to many cascaded outages and system islanding. The simulator utilizes an innovative method that analyzes the null space of the DC load flow susceptance matrix …  Read more

This thesis project consists of developing a hand-held, one-thumb input device small enough to be placed on gestural controllers and providing performers with a simple way to select between multiple options with few movements of a thumb. Most commercial input devices for the thumb make the assumption that buttons are the de facto standard. However, buttons are not always the best solution especially where space is very limited. This project explores a new approach to input design by analyzing the thumb's movements and designing a suitable input device that can track them. The design progression from the first to the …  Read more

Restenosis is the major cause of the failure of reconstruction methods to restore the blood flow in atherosclerotic arteries. Restenosis results from neointima formation and consequent constrictive remodelling. Vascular smooth muscle cell (VSMC) migration from the tunica media toward the intima is crucial in neointima genesis. The prerequisite for VSMC migratory activity is the modulation from the differentiated (contractile) to the de-differentiated (noncontractile) phenotype. VSMC phenotype change is associated with the altered expression of integrins. alpha8beta1 integrin is upregulated in cell types with contractile properties, including myofibroblasts and mesangial kidney cells. It is one of the integrins that is intensely …  Read more

Bulk nanostructured silver components were fabricated from nano-sized powder using a shockwave consolidation technique. The grain size evolution during compaction, the mechanical properties of the bulk components, and the effect of surface finish on the mechanical behavior were studied. X-Ray diffraction, transmission electron microscopy (TEM), atomic force microscopy (AFM), microhardness, compression testing and shear punch testing at room temperature were used to characterize the materials. Upon consolidation, the average grain size calculated from image analysis of the TEM micrographs was 49+/-22 nm, showing the feasibility of maintaining a nanostructure upon dynamic consolidation. The hardness of the bulk nanostructured components was …  Read more

The aim of this dissertation is to study a class of endogenous coalition formation problems with externalities where each agent's payoff depends not only on the coalition he or she belongs to but also how others partition themselves. This dissertation contains both theoretical and application elements. At the theoretical front (Chapter 1 and Chapter 2), two dynamic coalition formation games with endogenous choice of proposers are introduced. We prove that each game admits a dynamically efficient Markov perfect equilibrium. Moreover, we prove that the equilibrium payoff allocation of the game presented in Chapter 2 is unique. At the application front …  Read more

The work reported in this thesis is motivated by the need for wireless powering of a miniaturized implantable device for neurophysiological research and possible clinical applications. The antenna used in such applications must be studied in the context of biological tissue media. In this thesis, we perform a preliminary study of antenna behaviour in the complex tissue environment. Our test cases are the wire dipole antenna chosen for its structural simplicity and the spiral antenna, selected for its wide bandwidth. The simulation tool SEMCAD-X, is based on the Finite-Difference Time-Domain (FDTD) method and is used throughout this work. To have …  Read more

Cu3Au is a classic model for the experimental investigation on the transitional process because of its very long relaxation time from the disordered to the ordered state. When Cu3Au is quenched from higher temperature above its critical temperature (383°C) to some temperature below its critical temperature, the small regions of ordered phase (domains) form in the background of disordered phase. As time evolves, large domains grow at the expense of small domains. X-ray intensity fluctuation spectroscopy (XIFS) is a technique using coherent X-rays to measure the fluctuations of the diffracted intensity (speckle patterns) from the sample. During the ordering process, …  Read more

Contact is a ubiquitous means by which bodies interact mechanically with each other. Dedicated to the study of the dynamic response of bodies in contact and to the mathematical description of the contact phenomenon, contact dynamics modeling has been and remains an intensive area of research with numerous applications in the engineering practice, such as mechanism analysis and design, aerospace engineering, robotics, bioengineering, sports, computer engineering and material engineering. However, contact dynamics behavior is not easy to model because of the complex dependencies on the properties of the contacting bodies, including the geometry of contact and kinematic configuration, the inertia …  Read more

Diagnostic cognitive assessment (DCA) was explored using Bayesian networks and evidence-centred design (ECD) in a statistics learning domain (ANOVA). The assessment environment simulates problem solving activities that occurred in a web-based statistics learning environment. The assessment model is composed of assessment constructs, and evidence models. Assessment constructs correspond to components of knowledge and procedural skill in a cognitive domain model and are represented as explanatory variables in the assessment model. Explanatory variables represent specific aspects of student's performance of assessment problems. Bayesian networks are used to connect the explanatory variables to the evidence variables. These links enable the network to …  Read more

The development of a mid-temperature range (250°C--500°C) heat pipe for high heat flux applications has been the focus of numerous researchers during the last 40 years. However, until this work a viable working substance for the heat pipe has eluded researchers. While the most mentioned element has been sulfur, its unusual viscosity-temperature relationship has prevented the commercialization of a sulfur-based heat pipe. The recent development (and patenting) of the McGill heat pipe revived the question of whether sulfur would be viable in such a unit. Extensive testing showed that it is possible to make a high heat flux heat pipe …  Read more

The cytochrome P450 enzymes (CYPs) are very attractive biocatalysts because of their ability to regio- and stereo-selectively catalyze the insertion of a single atom of molecular oxygen into inactivated C-H bonds. There are many drawbacks, however, limiting the use of these enzymes in organic synthesis, including the need for expensive cofactors, low stability, and low tolerance to organic solvents. The goal of this thesis was to overcome some of these drawbacks for human CYP2D6. This isoform was selected because of its broad substrate promiscuity and high importance in drug metabolism. We have tested inexpensive chemicals to replace the natural cofactors …  Read more

This thesis focuses on construction, properties and estimation of asymmetric heavy-tailed distributions, as well as on their applications to financial modeling and risk measurement. First of all, we suggest a general procedure to construct a fully asymmetric distribution based on a symmetrically parametric distribution, and establish some natural relationships between the symmetric and asymmetric distributions. Then, three new classes of asymmetric distributions are proposed by using the procedure: the Asymmetric Exponential Power Distributions (AEPD), the Asymmetric Student-t Distributions (ASTD) and the Asymmetric Generalized t Distribution (AGTD). For the first two distributions, we give an interpretation of their parameters and explore …  Read more

Les adolescents qui éprouvent des difficultés d'apprentissage (DA) ont plus de risques que les autres de présenter des problèmes scolaires, socio-émotionnels et comportementaux. Bien que des relations familiales unies et flexibles constituent un facteur de protection pour les adolescents à risque en général, il y a peu de recherches empiriques portant spécifiquement sur les familles d'adolescents avec des DA. Le but de cette étude était d'exploiter les domaines des relations parent-enfant et de l'adaptation des adolescents avec des DA afin de déterminer si certains aspects de la communication parent-enfant comme la clarté, l'expression des émotions et la résolution de problèmes, …  Read more

Pre-operative radiotherapy for patients with locally advanced rectal carcinoma has been shown to improve survival rates and local tumour control. The ability to identify tumours most likely to undergo a complete or partial response would improve the selection of patients for radiotherapy and potentially modify post-treatment planning. The aim of this study was to develop a multi-marker model of tumour response to pre-operative high-dose rate endorectal brachytherapy (HDREB). Immunohistochemistry (IHC) for p53, Bcl-2, VEGF, APAF-1 and EGFR was carried out on 104 pre-treatment rectal tumour biopsies from patients undergoing a pre-operative HDREB protocol. Immunoreactivity was scored by at least three …  Read more

This work proposes some generic approaches to offer transparency and efficiency to checkpoint-recovery implementations on Windows. On the one hand, a complete environment is proposed to prepare Windows to incorporate transparently any checkpoint-recovery implementation whose architecture respects a simple contract of reusability. The environment allows any application to use some checkpoint-recovery services with only the default process creation mechanisms offered by Windows. Moreover, it handles automatically the recovery of the processes in case of a crash and requires no human intervention in most scenarios. On the other hand, an optimization module is proposed to minimize the checkpointing time and to …  Read more