McGill University Thèses et mémoires par auteur commençant par M

Patitsas, Elizabeth (Supervisor1)  Read more

Plant growth regulator(s) (PGR) can be used as lodging inhibitors and/or yield promoters for spring barley (Hordeum vulgare L.). From 1987 to 1990 four field experiments were conducted to monitor barley main-stem apical development and to determine the effects of chlormequat (CCC) and ethephon on the development, physiology and yield of spring barley. Our data provide a description of barley apical development and the general pattern of leaf and spikelet primordium production under field conditions. In general, PGR treatment reduced the apical dominance of dominant sinks allowing the survival and greater development of more subordinate sinks. Early application of either …  Read more

Meyer, Brett (Internal/Cosupervisor2)  Read more

Avec le développement des services Internet, les internautes peuvent facilement accéder à un grand nombre de produits et d'applications en ligne. Bien que cette croissance offre aux utilisateurs un plus grand nombre de choix disponibles, il est également difficile pour eux de choisir un article préféré parmi une multitude de candidats. Afin de réduire la surcharge d'informations et de satisfaire les divers besoins des utilisateurs, les systèmes de recommandation personnalisés voient le jour et jouent un rôle de plus en plus important dans la société moderne. En particulier, ces systèmes peuvent fournir des expériences personnalisées, répondre à d'énormes demandes de …  Read more

The low density lipoprotein receptor-related protein 1 (LRP1) is a single transmembrane receptor that mediates the endocytosis of over 40 different ligands. Although LRP1 is traditionally classified as a scavenger receptor due to its role in lipoprotein uptake and its large selection of ligands, recent studies have shown strong evidence in its role in cellular signaling. The PTB domain-containing engulfment adapter protein 1 (GULP) is the adapter protein regulating the endocytosis of LRP1. Previous studies in our laboratory have presented the effect of GULP on lipid homeostatsis, where elevated GULP expression resulted in accumulation of glycoshpingolipids in the lysosome. Moreover, …  Read more

Dunkley, David Michael (Supervisor)  Read more

This thesis addresses calibration of joint torque sensors and identification of a gravity compensation (GComp) model. The two problems are related: calibrated torque information is prerequisite for the GComp model identification; the identified GComp model makes on-line automatic torque sensor calibration possible. In the first part, we propose an autonomous joint torque sensor calibration method, which utilizes combinations of single-joint rotations and an arm's own gravity load. The method determines not only joint torque sensor gains and offsets, but also those of the joint angle sensors. When one joint of a manipulator is rotated, the gravity torque exerted on the …  Read more

Up until recently, the development and generalization of h-type and hp-type refinement techniques and strategies for the efficient and effective adaptive finite element analysis of continuum problems has been limited by the widespread use of geometrically conforming mesh discretizations, designed to maintain the continuity of the field model. These limits have retarded the growth, and restricted the potential, of modern adaptive finite element methods for engineering electromagnetic systems modeling, analysis and simulation. A new generalized theory and family of techniques which alleviate the need for conforming meshes is presented. The method is based on the concept of generalized irregular meshes …  Read more

Nous introduisons un modèle basé sur l'apprentissage des données qui produit des rendus d'apparences de peau réalistes sur des têtes humaines en transformant les G-Buffers d'espace de l'écran en une image de rendu final. Les G-Buffers incluent les normales de surface, les positions de surface par rapport à la caméra et les valeurs d'albédo par pixel. Leur synthèse est extrêmement économique. Nous avons choisi d'utiliser une combinaison de Réseaux antagonistes génératifset de la perte d'image pour former nos modèles. Les deux pertes sont d'abord appliquées ensemble, ensuite seule la perte basée sur l'image est appliquée. Avoir 2 stratégies d'entraînement aide …  Read more

The objective of this study is to gain an understanding of the factors which influence and control the formation of self-assembled monolayers (SAMs) chemisorbed on metal surfaces and how these SAMs modulate electron transfer kinetics. To achieve this purpose various alkyl thiol-SAMs with chain lengths from C4SH to C22SH and terminal functional groups such as -CO2H, -OH, -NH2, and -SO3- were prepared on gold surfaces. The electron transfer processes across thiol-SAMs have been extensively studied by electrochemical techniques including cyclic voltammetry and rotating disk electrode (RDE) voltammetry. RDE results indicate that a thiol monolayer greatly reduces the electron-transfer rate at …  Read more

Partially observable Markov decision processes (POMDPs) have emerged as a principled framework for planning and decision making under uncertainty. Planning in large POMDPs is challenging especially when information-gathering efforts or long planning horizons are required. A few recent algorithms successfully tackle one of the above two cases but at the expense of a weaker capacity of tackling another based on the notion of point-based value iteration. To bridge the gap between the two classes of point-based approaches, this thesis proposes Information Gathering and Reward Exploitation of Subgoals (IGRES), a randomized POMDP planning algorithm that leverages information in the state space …  Read more

La technique de la membrane liquide émulsion (MLE) est une technique modifiée qui combine l'extraction traditionnelle au solvant et le stripage dans une seule opération unitaire. Les caractéristiques de la MLE comprennent la grande surface interfaciale et une grande sélectivité lors du traitement des ions de métaux lourds. Par à l'étude de l'application de la technique MLE pour extraire et déshabille des ions cuivre et le nickel à partir de solutions simples de cations, cette thèse vise l'extraction et la séparation de différents métaux tels que le cuivre, le nickel et le calcium, en utilisant le réactif et la consommation …  Read more

China now is one of the most attractive destinations for foreign direct investment (FDI) and mergers and acquisitions (M&As) have become an increasingly important mode of FDI entry in China since its accession to the World Trade Organization. M&As in China are expected to play a vital role in the restructuring of its inefficient State-owned enterprises. This thesis characterizes and analyzes the evolving Chinese legal regime governing M&As in the context of the ongoing economic reform. In addition, it identifies the antitrust issues arising from foreign acquisitions of Chinese domestic enterprises, which can result in market dominance and restrictive practices …  Read more

L'étude de l'immuno-métabolisme a pris de l'importance ces dernières années avec le développement de nouvelles technologies permettant de mieux comprendre la contribution du métabolisme à la fonction des cellules immunitaires. Le glucose et la glutamine sont des substrats métaboliques clés qui jouent un rôle important dans le soutien bioénergétique, biosynthétique et les fonctions mitochondriales des lymphocytes T, qui soutiennent la croissance, le développement et le maintien de l'homéostasis et les fonctions des cellules immunitaires. À ce jour, la plupart des études métaboliques ont porté sur des lymphocytes T en culture in vitro. Ces études ont été utiles pour identifier les …  Read more

Le muscle squelettique, un tissu hautement adaptable, est capable de répondre aux stimuli. Dans les derniers stades des maladies chroniques tels que la maladie rénale et le cancer, les patients développent une condition appelée cachexie. La cachexie est caractérisée par une perte de poids causé par un gaspillage involontaire du muscle et du tissu adipeux. Durant la perte musculaire, la dégradation accrue des protéines musculaires clés et la diminution de la synthèse des protéines entraînent une détérioration musculaire. De plus, le développement de la cachexie réduit la qualité de vie et contribue à la mortalité des patients. L'inflammation chronique associée …  Read more

L’activation de lymphocytes pnmaIres induit l’initiation du programme apoptotique. Parcontre, les cellules ne meurent pas par apoptose. L’objectif de cette étude était de déterminer les protéines clées régulatrices qui contrôlent l’activation des caspases lors de l’activation des lymphocytes T. Pour ce faire, la signalisation impliquée dans l’apoptose a été analysée au niveau de lymphocytes T hautement purifiés. Les résultats obtenus révèlent que, suivant l’activation de lymphocytes T par anti-CD3 et anti-CD28 en présence d’IL-2, un clivage initial de caspase-3 générant le fragment inactif p20 a lieu et les substrats clés, essentiels à la signalisation apoptotique, n’ont pas été clivés. Ce …  Read more

This thesis reports on the design of an optical relay for use in a color, stereo Head-Mounted Display (HMD) system. Based on reviews and discussions of the requirements of the human visual system, major factors affecting the visual acuity, the aberration tolerances of the human eye, and optical design limitations, we derive the design criteria for the optical relay. A survey of alternate approaches to the three components of HMDs is presented. A brief review of first order optics, aberration theory, general design principles, and computer aided lens design is also given. Two multi-spherical lens systems, a straight structure and …  Read more

Dans le domaine des cavités optomécaniques, nous utilisons la lumière réfléchie et transmise d’une cavité optique afin de sonder les déplacements d’un élément mécanique. Cependant, la pression de radiation de la lumière perturbe aussi la trajectoire de cet élément mécanique. Dans ce mémoire, je vais présenter le travail réalisé vers la réalisation d’un système optomécanique où la trajectoire d’un ``trampoline'', agissant comme résonateur mécanique, est déterminée majoritairement par la pression de radiation quantique de la lumière émise par un laser dans un micro-cavité optique à base de fibres optiques. Cette cavité comprend deux fibres optiques avec miroir séparées par ∼100 …  Read more

Lange, Fabian (Supervisor1)  Read more

Human immunodeficiency virus (HIV) is the causing agent of the acquired immune deficiency syndrome (AIDS). Like all retroviruses, HIV carries two copies of viral genomic RNA in each virion. HIV genome encodes three structural genes, including gag, pol and env, as well as two regulatory genes (rev and tat) and four accessory genes (vif, vpr, vpu and nef). It is noted that none of these nine viral proteins bears the helicase activity. Helicases are able to unwind RNA duplex and remodel the structure of RNA-protein (RNP) complexes using energy derived from hydrolysis of nucleotide triphosphates (NTPs). They are involved in …  Read more

De Mestral, Armand (Supervisor)  Read more

After almost 15 years of effort, China is finally on its way to membership of the WTO. Accordingly, China will liberalize its financial sector that basically consists of banking, insurance and securities industry and it will phase out most of the existing restrictions respecting foreign participation in this sector. However, in a sector with a formidable legacy of substantial non-performing loans, low efficiency, and the moral hazards attendant on a command economy, the future of liberalization in this sector is anything but certainty. Through reviewing the application of GA TS principles on financial services, canvassing the past and present of …  Read more

After almost 15 years of effort, China is finally on its way to membership of the WTO. Accordingly, China will liberalize its financial sector that basically consists of banking, insurance and securities industry and it will phase out most of the existing restrictions respecting foreign participation in this sector. However, in a sector with a formidable legacy of substantial non-performing loans, low efficiency, and the moral hazards attendant on a command economy, the future of liberalization in this sector is anything but certainty. Through reviewing the application of GA TS principles on financial services, canvassing the past and present of …  Read more

van de Voort, F. R. (Supervisor)  Read more

"The laboratory rat serves as the normal host for Nippostrongylus brasiliensis and as an abnormal host for the pig Ascaris, A· suum. The migration and behaviour of these parasitic nematodes in the rat and the parasite-induced changes in the host's lungs and blood were studied and compared. In its normal rat host, N· brasiliensis undergoes a regular and predictable pattern of migration via the blood circulation to the lungs and finally to the small intestine, where the worm becomes sexually mature. The migratory process is mostly passive. Development of the larva in the lungs is essential, representing a logarithmic growth …  Read more

Worsley, K. J. (Supervisor)  Read more

Recent years have witnessed the large number of Chinese immigrants in Canada. However, talk about the return migration of Chinese immigrants is circulating within the Canada's Chinese communities, especially among Chinese immigrants who have obtained Canadian academic credentials. This inquiry explores ten Chinese immigrants' perceptions about their immigration and living experiences in Canada. My goal is to understand, from a social-cultural-historical context, the phenomenon of Chinese-Canadian return migration among recent Chinese immigrants in Canada. The theoretical framework is derived primarily from Bourdieu's capital theory and his critical approach to the concept of habitus . Drawing on an interpretative, qualitative approach, …  Read more

Recent years have witnessed the large number of Chinese immigrants in Canada. With the coming of those immigrants is the large number of school age children. Hence, immigrant families' educational expectations and parental participation in their children's schools become major educational concerns. This study focuses on recent Chinese immigrants' expectations of and concerns about their children's schooling. Drawing from Bourdieu's cultural capital theory and Ogbu's social mobility theory, in this study, I used a qualitative interview methodology to explore the educational expectations and school involvement of five Chinese parents who had recently immigrated to Canada. The educational expectations for their …  Read more

Page segmentation is one of the important and basic research subjects of document analysis. Traditionally, there are two major kinds of page segmentation approaches. One is the top-down approach and the other is the bottom-up approach. Though these two approaches are been used till now, they are not effective for processing documents with high geometrical complexity and the process of splitting document needs iterative operations which is time consuming. The Modified Fractal Signature (MFS) approach which was presented in recent years can overcome the above weaknesses, however it needs to calculate modified fractal signature which makes the theory and the …  Read more

This study is concerned with the effect of slantwise convection in general circulation models (GCMs). The approach is through the development of a slantwise convective parameterization scheme (SCPS) and its implementation into version 11 of the third generation GCM of the Canadian Climate Centre for modelling and analysis (CCCma gcm11). We first study the characteristics of conditional symmetric instability (CSI) in an environment which is also unstable for conditional upright instability (CUI). The results indicate features common to both upright and slantwise convection. This so called slantwise buoyant instability (SBI) possesses two relevant time scales and its horizontal scale can …  Read more

One of the most common industrial cold forging processes is cold heading of steel wire or rod to produce screws, bolts, nuts and rivets. The process is limited by a complicated interplay of many factors. The cold work (pre-drawing) is one of them. Although several investigations into the effects of pre-drawing on the formability of metals during cold heading processes have been conducted, so far no attention has been given to the numerical simulations of this phenomenon. The current work aims at examining effects of pre-drawing on formability during cold heading through numerical simulations. Physical tests in the literature investigating …  Read more

Rabbany, Reihaneh (Supervisor1)  Read more

Learning on graphs has emerged as a fundamental direction in machine learning, as part of the broader field of geometric deep learning, which focuses on modeling the intricate structures and symmetries underlying complex data.However, existing standard paradigm of graph neural networks (GNNs) -- message passing neural networks (MPNNs) -- face inherent limitations in terms of expressivity, capacity, flexibility, and generality.This thesis introduces a novel paradigm—learning on pseudo-coordinates—which provides not only enhanced expressive and representational power but also greater modeling flexibility.Pseudo-coordinates serve as coordinate-like spatial representations that relax the strict constraints of conventional coordinate systems.They are particularly valuable for domains lacking …  Read more

Objective: Osteogenesis Imperfecta (OI) is a heritable bone fragility disorder of wide ranging severity, which sometimes also manifests tooth abnormalities known as Dentinogenesis Imperfecta (DI). It is unreported how the OI severity and these tooth abnormalities affects Caries Prevalence and Experience (CPE) in these individuals. The objectives of this study were to quantify the caries experience among different OI types and quantify how these values change due to DI. Methods: The adjusted DFT scores were used to account for frequent hypodontia, impacted teeth and retained teeth in an OI population. Univariate logistic regression followed by stepwise multivariate logistic regression was …  Read more

Bruce, Lennox, R. (Supervisor2)  Read more

As operating frequency increases and device sizes shrink, the complexity of current state-of-the-art designs has increased dramatically. One of the main contributors to this complexity is high speed interconnects. At high frequencies, interconnects become dominant contributors to signal degradation, and their effects such as delays, reflections, and crosstalk must be accurately simulated. Time domain analysis of such structures is however very difficult because, at high frequencies, they must be modeled as distributed transmission lines which, after discretization, result in very large networks. In order to improve the simulation efficiency of such structures, model order reduction has been proposed in the …  Read more

The main challenge for developing accurate and efficient delay metrics has been the prediction of delay to points on the interconnect which are relatively close to the source. Those metrics which are relatively successful in meeting this challenge require two-dimensional look-up tables and algorithm tuning, and are quite challenging to implement. The simpler explicit metrics only work well on so-called far nodes, which are characterized by all-pole frequency responses. In this thesis, we first review an existing delay metric for wires and then try to extend it to arbitrary tree networks. Thorough tests demonstrate it to be accurate and efficient …  Read more

Cette thèse concerne les techniques de traitement du signal tout-optique et de photoniquemicro-ondes basées sur des dispositif photoniques intégrés sur silicium. Tout d'abord,nous avons conçu et caractérisé un type de régénérateur 2R intégré pour la restaurationdes signaux de type on-off keying (OOK) à 10 Gb/s en simulation, avec la possibilitéde régénération simultanée multi-canaux 2R pour à vitesse encore plus élevée. Deplus, nous démontrons la génération photonique d'impulsions micro-ondes chirpées à l'aided'une cavité Fabry-Pérot distribuée integrée sur silicium permettant la mise en forme spectrale,avec la possibilité d'une solution finale 'blackbox'. Ces deux démonstrations étudientl'intensification du niveau d'intégration du dispositif de silicium …  Read more

Dumitru-Daniel Andrei (Supervisor1)  Read more

The kinematics and dynamics for the purposes of analysis, control, simulation, and design of general platform-type parallel manipulators are the subject of this thesis. Two new methods of direct kinematics for displacement analysis are proposed. Velocity and acceleration analyses for general kinematic architectures are fully studied. Furthermore, kinematic singularities are classified based on their nature. Architecture singularities and architecture conditioning are deeply studied and incorporated into design strategies, along with design examples. Moreover, formulation singularities are also given due attention with case studies. In dynamics modelling, the method of the natural orthogonal complement is applied such that the resulting models …  Read more

In order to combat channel failures in data communications, multiple description coding (MDC) produces two or more equally important bitstreams or descriptions, and transmits them independently over erasure channels. If only one description is correctly received, a coarse copy of the source is obtained. The more descriptions correctly received, the finer the accomplished quality. When all descriptions are correctly received, the transmitted signal can be completely reconstructed. In this work, we apply MDC to accommodate multimedia transmissions over hybrid wireline-wireless networks, which require low delay and high robustness against both packet losses and bit errors. In addition to the classical …  Read more

Les matériaux naturels qui peuvent façonner leur forme en réponse aux changements environnementaux ont inspiré la conception de matériaux synthétiques contenant des géometries et des fonctions multiples et uniques. Les approches actuelles utilisent principalement un système en couches minces et souples pour générer des transformations géométriques en réponse à un stimulus externe. Ce type de système permet d’atteindre les transformations de forme dans l'espace mais sans résistance structurelle et morphing évolutif dans le temps. En présence de ces limites, le morphing de forme dans des applications réelles telles que les enveloppes de bâtiments intelligents nécessitant un comportement structurel, temporel et …  Read more

The kinetoplastid protozoan parasite Trypanosoma brucei is the causative agent of human African trypanosomiasis (HAT), also known as sleeping sickness. Most anti-trypanosomal treatments require invasive administration and induce severe side effects. Recently, the Drugs for Neglected Diseases Initiative (DNDi) entered an oral treatment, fexinidazole, into a phase III clinical trial in the Democratic Republic of Congo and Guinea for the treatment of Trypanosoma brucei gambiense infection. Fexinidazole is the first entirely oral treatment for HAT. In contrast, the currently available drugs for treating HAT are specific to life-stage and subspecies of T. brucei infections. They also require invasive administration procedures. …  Read more

Integer least squares (ILS) is an important class of optimization problems that may arise from estimating the integer parameter vector in a linear model with additive Gaussian noise in applications such as communications, control and global navigation satellite systems. This thesis is concerned with solving the underdetermined box constrained ILS (UBILS) problems. We propose a modified alternating direction method of multipliers (ADMM) algorithm as a heuristic approach. Simulation results show that such heuristic is much superior to original ADMM on UBILS problems. Based on the existing direct tree search (DTS) algorithm, we show how to incorporate ADMM methods for computing …  Read more

The aim of this thesis study was to investigate the substance P (SP)-immunoreactive (IR) sensory fiber innervation of CNS target tissues in two experimental models. In the first model, we examined the SP-IR boutons apposed to three functional types of dorsal horn neurons and their morphological interaction with calcitonin gene-related peptide (CGRP) and enkephalin (ENK) in the cat spinal cord, using a combination of intracellular electrophysiological recording and horseradish peroxidase injection with ultrastructural immunocytochemistry. In addition to SP-IR only boutons, we detected boutons co-localizing SP plus CGRP and SP plus ENK immunoreactivities presynaptic to nociceptive neurons. Quantitatively, significantly higher numbers …  Read more

Interest in local intercellular communication within tissues in fields such developmental biology, neuroscience, and oncology have motivated the development of spatially resolved transcriptomics technologies. These technologies come with trade-offs; for in situ capture methods such as 10x Genomics Visium, for example, the gene expression captured from a single spot may come from multiple cells, and thus computational methods for integrating single-cell data to deconvolve cell type proportions have gained interest. To date, these have required sample-matched datasets from each modality, whereas in most cases these are not available. Taking inspiration from and building on CellDART, a method that uses domain …  Read more