McGill University Thèses et mémoires par auteur commençant par B

Cereal aphids started to infest cereals in the first week of June and reached their peak in the second and third week of July. They could affect both the quantity and quality of grain yields, but I recommend chemical control only when the aphid population reaches the economic threshold level, which was calculated as 16 aphids/tiller. Pirimicarb is recommended for chemical control, as it controlled aphids efficiently and had a minimal effect on the available predators and parasites. A sequential sampling plan has been developed to detect if populations reach economic threshold. Temperature accumulation, starting from the first detection of …  Lire la suite

Introduction: Cannabis is often used to cope with affective symptoms, such as depression or anxiety. In Canada, 43% of people who used cannabis in 2023 perceived that cannabis use was beneficial to their mental health, while only 8% thought that it was harmful. Paradoxically, longitudinal studies suggest that cannabis use is associated with the development and maintenance of affective symptoms. It is therefore crucial to understand if cannabis abstinence benefits affective symptoms. Previous studies found that depressive and anxiety symptoms improved with 28 days of cannabis abstinence. However, most of these studies included participants with psychiatric/medical comorbidities or were conducted …  Lire la suite

Mallory, Mark (Supervisor2)  Lire la suite

The lethal form of human malaria is caused by the most prominent human protozoan parasite, Plasmodium falciparum, responsible for an estimated ~1 million deaths annually. Malaria treatment and, prevention heavily rely on antimalarial drugs. The synthetic substitute of quinine, chloroquine, was the most effective treatment for this disease. The rise of chloroquine resistant malaria in endemic areas has suppressed control efforts. Chloroquine resistance has been associated with mutations in a transmembrane protein on the digestive vacuole of the parasite, designated PfCRT. Moreover, the normal function(s) and natural substrate(s) of PfCRT remain a matter of speculation as direct evidence for the …  Lire la suite

L'émergence de la résistance aux antipaludiques a entravé les efforts mondiaux visant à éliminer le paludisme, et a coûté des millions de vies humaines. Les parasites Plasmodium falciparum sont responsables pour la majorité de la morbidité et de la mortalité, comparément aux autres espèces. Les thérapies combinées à l'artémisinine sont utilisées pour traiter les personnes infectées et ont connu un gros succès. Cependant, une résistance à ces combinaisons a récemment émergée et le schéma de progression est alarmant. La chloroquine était autrefois utilisée comme médicament principal pour le traitement contre le paludisme, mais elle est devenue inefficace en raison de …  Lire la suite

Peter Vanrolleghem (Supervisor2)  Lire la suite

The following thesis presents the results of four full scale beams tests as part of a research program conducted at McGill University. The purpose is to study the applicability of existing design provisions, in the American Association of State Highway and Transportation Officials (AASHTO) specifications, for the use of self-consolidating concrete (SCC) in precast pretensioned bridge girders. The test specimens had an overall length of 31 ft (9.4m) with a center-to-center span of 29 ft (8.8m). They were cast in four batches with different concrete attributes: two non air-entrained SCC mixtures and two high-performance concretes. For each type, compressive strengths …  Lire la suite

The liver parenchyma is the major target organ enriched in EGF and insulin receptors. Following the administration of a receptor saturating dose of EGF, there was a rapid internalization of receptor coincident with its tyrosine phosphorylation. In the endosome, the adaptor protein SHC was recruited to and tyrosine phosphorylated by the EGF receptor. GRB2 and the Ras guanine nucleotide exchange factor, SOS, was primarily associated with the EGF receptor in endosomes. This is believed to contribute to a cytosolic pool of a complex of tyrosine phosphorylated SHC-GRB2/SOS. The activation of these molecules lead to the initiation of the mitogenic Ras-MAPK …  Lire la suite

Vascular gas embolism is a potentially life-threatening medical condition caused by the presence of gas bubbles in the vascular network, leading to reduced blood flow and possible disruptions in the transport of oxygen to tissues and vital organs. Despite its significant implications for patient health, particularly in iatrogenic contexts, the origins and underlying mechanisms remain poorly understood. Since the onset of this condition is physical in nature, the purpose of this study is to investigate the genesis of gas embolism and its varied manifestations by employing a series of abiotic microfluidic devices designed to simulate the human vascular system with …  Lire la suite

Small molecule-based drugs are designed to bind to a primary target. However, their biological activity and toxicity are influenced by unspecific binding to secondary targets. The identification of these targets is referred to as target profiling. Chemical probes, which contain a small molecule scaffold as a warhead and a biotin tail designed to be captured with streptavidin-coated magnetic beads, can be utilized as a target profiling method. The development of target profiling tools to advance drug development, therapy combinations, and patient stratification in the areas of immuno-oncology and/or drug allergy is needed. This thesis investigates the feasibility of using chemical …  Lire la suite

Il est d’un grand intérêt d'étudier les corrélats neuronaux de l'apprentissage sensorimoteur et le rôle des différentes zones du cerveau impliquées dans l'acquisition des aptitudes motrices. Il existe plusieurs formes d'apprentissage sensorimoteur, chacune d'entre elles recrutant vraisemblablement des mécanismes et des processus neuronaux distincts. Cependant, il existe encore des conjectures sur la façon dont ces processus sont réalisés dans le cerveau. Cette thèse a consisté à étudier les réseaux cérébraux impliqués dans l'apprentissage de nouvelles tâches sensorimotrices. Nos paradigmes expérimentaux exigeaient que les sujets apprennent des mouvements dans de nouveaux environnements haptiques obtenus par des interfaces robotiques. Une imagerie par …  Lire la suite

Pain is a distressing sensory and emotional phenomenon often caused by a damaging intense noxious stimulus. The activation of nociceptive circuits elicits a multi-component response including complex behavioural reactions to alleviate pain and coping responses such as aversion after chronic exposure to pain. The generation of appropriate nocifensive responses strongly relies on the anterolateral system (AS) neurons that transmit a wide range of inputs from the spinal cord to multiple supraspinal targets including the medulla, midbrain and diencephalon. Despite the considerable progress made over the past five decades in understanding the contribution of AS neurons, the programs that guide their …  Lire la suite

Cette thèse a exploré les trajectoires d'immigrants qualifiés et instruits, leur investissement dans l'apprentissage des langues, la construction de l'identité et l'intégration à Montréal, Québec. Le Québec accueille des immigrants professionnels et qualifiés pour bâtir son économie, ainsi que pour promouvoir l’identité et le nationalisme du Québec. Bien que le Québec ait adopté des politiques interculturelles visant à reconnaître la diversité linguistique, ces efforts ont été enchâssés dans un cadre linguistique français, dont la Charte de la loi française (loi 101), qui fait du français la langue officielle et de tous les jours au Québec. Plusieurs immigrants sélectionnés dans le …  Lire la suite

Cell-surface interactions have been identified to be of a primary relevance in a wide variety of biomedical applications. Despite the availability of a large number of studies, the cell-surface interactions are not still fully understood; thus, owing to the importance of these interactions, it is crucial to understand the nature of their governing parameters. Synthetic polymers play an important role in disease management and health care. However, due to the chemical inertness of their surfaces, their interactions with the biological environment can be improved by modifying the surface properties, for example by plasma polymerization. It is proposed that the physio-chemical …  Lire la suite

Ce travail présente des techniques de conception d'amplificateurs de transimpédance à haute vitesse et à faible bruit pour des applications dans les récepteurs optiques et les SerDes de la prochaine génération. Les différentes possibilités de compromis disponibles dans les architectures TIA sont discutées et des conceptions sont proposées pour réduire le bruit référencé en entrée sans compromettre la bande passante. À cette fin, trois conceptions sont proposées dans ce travail. Chacune de ces conceptions tend à minimiser le bruit sans compromettre la bande passante et le gain. Certaines conceptions se concentrent sur la réduction de la consommation de surface tandis …  Lire la suite

A two-length-scale turbulence model is introduced in this thesis for the computation of quasi-two-dimensional turbulent shear flow with two distinct length scales of motion. In the model, the turbulence motions of the two distinct length scales are computed separately. The small-scale turbulence is treated as a background component locally in equilibrium while the large-scale turbulence is simulated using a second-order closure procedure. The development of the turbulent shear flows depends on the rate of energy transfer from the large-scale to the small-scale turbulence. Two mechanisms are identified to have a significant effect on the rate of this energy transfer. On …  Lire la suite

Cette étude qualitative examine le leadership d'une directrice d'une école secondaire anglaisedans la grande région de Montréal. L’étude avait pour objectif d’apprendre comment la directricede l’école secondaire assume ses responsabilités en tant que dirigeante. Plus précisément, lesquestions qui ont conduit à cette étude étaient : “ Quelles qualités attribue-t-elle audéveloppement du leadership ? ”, “Quelles sont ses approches pour la mise en œuvre duleadership ? ”. Les sources de données comprenaient des entrevues avec une directrice, quatreparties prenantes, mémos de réflexions, artefacts scolaires, informations en ligne, y compris le filTwitter de la directrice et le site internet de l’école.L'analyse thématique …  Lire la suite

Innate responses in the central nervous system (CNS) provide first-line defense against infection and injury. Microglia and astrocytes may direct leukocyte infiltration to the injured CNS. The signaling mechanisms that orchestrate this response are ill-defined. Innate roles for microglia and astrocytes are supported by reports demonstrating glial expression of Toll-like receptors (TLRs). TLRs recognize conserved pathogen-associated motifs and generate innate immune responses, usually by signaling through the adaptor protein, MyD88. TLRs may also generate innate responses to tissue damage. The data in this thesis implicate TLR2/MyD88 as key mediators of innate response to brain injury in mice. Transection of axons …  Lire la suite

This thesis examines the effects of continuous theophylline pretreatment on the A$ sb2$ adenosine receptor system in cultured murine neuroblastoma cell lines, which either do or do not also express A$ sb1$ adenosine receptors. N-Ethylcarboxamido adenosine (NECA) stimulates cAMP accumulation and binds to A$ sb2$ receptors in a saturable and biphasic fashion in both types of cell cultures. Sixteen hours of theophylline treatment led to a significant increase in the number of low affinity A$ sb2$ binding sites, as well as a potentiation of NECA-stimulated cAMP accumulation, regardless of whether the cells expressed A$ sb1$ receptors. The enhanced adenylate cyclase …  Lire la suite

Afin d'étudier la fonctionnalité des déshydrogénases du dihydrolipoamide de Sinorhizobium meliloti, les gènes lpdA1, lpdA2 et lpdA3 ont été mutés par la méthode de mutagenèse dirigée par le recombinaison cross-over unique, au moyen de plasmides suicides modifiés pVIK112. Le mutant lpdA1n'a pas été capable de croître sur le pyruvate, et sa croissance a été considérablement retardée sur les autres sources de carbone qui furent essayées. L'activité du complexe pyruvate déshydrogénase n'a pas été décelée dans ce mutant, et la régulation du lpdA1 ne dépendait pas de la présence de pyruvate. Ce mutant était Nod +, mais il paraissait être Fix-. …  Lire la suite

Varro, Daniel (Supervisor2)  Lire la suite

The study attempts to determine the extent to which Arab nationalism, as expressed tn the writings of Michel 'Aflaq, may be considered truly secular. The analysis of 'Aflaq's published essays and speeches focuses upon his treatment of religion in general and of Islam in particular. In order to present a valid analysis of his writings, the origins of 'Aflaq's thinking are traced to the experiences and influences he underwent.  Lire la suite

The study attempts to determine the extent to which Arab nationalism, as expressed in the writings of Michel Aflaq, may be considered truly secular. The analysis of Aflaq's published essays and speeches focuses upon his treatment of religion in general and of Islam in particular. In order to present a valid analysis of his writlngs, the origins of Aflaq's thinking are traced to the experiences and influences he underwent. It is shown that, although Aflaq uses religious terms and concepts, he deprives them of all supra-human implications. Thus, the particularism engendered by different religious modes of worshlp loses much of …  Lire la suite

Lametti, David (Supervisor)  Lire la suite

In this thesis, a widened X-branch optical waveguide by K$ sp+$-Na$ sp+$ ion-exchange in glass, to be used as a single mode-optical wavelength division demultiplexer (WDM) at the wavelengths 1.31$ mu$m is designed, fabricated, and tested. The widened X-branch is a channel guide structure. To carry out the design, the effective-index method (EIM) together with the 2D-beam propagation method (FD-BPM), are employed. In order to get an accurate model for the lateral effective index in the channel guide, in the EIM, the diffusion process related to the ion-exchange is numerically simulated using an explicit 3D finite difference scheme. Experimentally, extinction …  Lire la suite

Background Sedentarism or prolonged sitting time is an emerging risk factor for obesity, independent of physical activity (PA). Bariatric surgery seems to be most effective form of treatment that works for severely obese individuals (Body Mass Index (BMI) of >40 kg/m2). Objectives The purpose of this investigation was to characterize with the use of accelerometers, daily steps/day and sedentary behavior (SB) by measuring time-spent sitting/lying in severely obese patients before and after bariatric surgery. Setting McGill University Health Center (MUHC). Methods Seventeen patients (58.5% of the patients were female) with a mean age of 46.5 ± 10.1 years, and a …  Lire la suite

La théorie de la gestalt définit un ensemble spécifique de principes de base qui sont considérés comme des lois selon lesquelles le système visuel organise et intègre les éléments séparés en ensemble unique (Koffka, 1935). L'inclusion des stimuli de la gestalt dans la présente étude chez les enfants autistes de haut fonctionnement (AHF) par rapport au enfants à développement typique (DT) spécifie sur un plan cognitif à quel moment la perception visuelle chez les enfants AHF se différencie, et prête preuve envers la spécificité de la théorie de Cohérence Centrale Faible (Frith & Happé, 1994). Les principes de la gestalt …  Lire la suite

Burack, Jacob A. (Supervisor1)  Lire la suite

This study investigated nonverbal communication patterns in siblings in the prosocial, neutral, and agonistic conditions. Sixty-four children aged 3 years 3 months to 9 years 6 months (16 same-gender and 16 mixed-gender sibling dyads) participated. All children's behaviors were coded using the system for Identifying Affect Expressions by Holistic Judgments (AFFEX, facial expressions) and the Behavioral Coding System (BCS) for behaviors. The major finding was that all children were as likely to imitate positive facial expressions in the prosocial as in the aggressive conditions. However, they were more likely to imitate positive behaviors in the prosocial condition and negative behaviors …  Lire la suite

Spatial cognition is essential to the complex spatial behaviours that many avian species exhibit, yet the extent to which this cognitive ability influences these behaviours remains poorly understood. Few studies have effectively investigated the direct relationship between controlled measures of spatial performance and quantified natural behaviour, in part due to the challenge of developing ecologically appropriate testing devices and tasks for free-living animals. As the inaugural phase of a larger study, my thesis proposes and validates a novel apparatus to measure spatial ability in wild Ring-billed Gulls (Larus delawarensis; RBGU) and evaluates alternative analytical approaches for small-scale behavioural datasets. I …  Lire la suite

"Primum non nocere has been the cardinal rule in medicine, including dental medicine, since Hippocrates. In order to follow this simple humanitarian rule, it is necessary to have a deep knowledge of the changes of iatrogenic nature. An eighteenth century German theory was to give the patients some more of the poison that was believed to cause their disease. Such treatment was, at best, an experiment in the survival of the fittest. However, the idea behind it may coincide with the idea of modern vaccines. Also, .American medical history has its notorious stories of diseases of iatrogenic nature. Blood letting …  Lire la suite

L'évaluation biomécanique pour la réhabilitation du ligament croisé antérieur (LCA) et l'évaluation du risque de blessure est généralement réalisée à l'aide de laboratoires de capture de mouvement, qui sont généralement coûteux, nécessitent l'intervention d'un expert et sont limités à un seul endroit. De récentes avancées dans le domaine de la vision par ordinateur et des techniques d'apprentissage automatique ont rendu possible le suivi tridimensionnel du squelette et l'évaluation subséquente à partir d'un seul appareil mobile. Cette thèse évalue le potentiel de l'utilisation d'une application téléphone intelligent pour l'évaluation en temps réel du risque de blessure au LCA, qui peut être …  Lire la suite

This study examined whether children's cognitive perceptions of the amount of skill and luck involved in gambling activities could be modified as a function of reinforcement schedules on a gambling task (Hilo). Children (N = 174) from grades 5 and 7 completed a questionnaire to evaluate cognitions and played a computer simulated card-cutting game. Cognitions were assessed after the game to examine if cognitive perceptions changed and then again one and four weeks later to evaluate if changes were maintained. Results reveal that experiencing repeated losses decreased perceived skill and increased perceptions of luck on gambling tasks in general. Cognitive …  Lire la suite

Waddell, Candace S. (Supervisor)  Lire la suite

Researchers have linked resin and fatty acids (RFAs) to acute toxicity, especially in thermomechanical and chemithermomechanical pulp and paper mill effluents. Thus, the measurement of total RFAs may be a rapid, inexpensive alternative to standard methods of toxicity monitoring, such as 96-hour rainbow trout testing. Current procedures for the analysis of RFAs typically involve solvent extraction and concentration, derivatization, and analysis by GC, HPLC, or TLC. These procedures are far too expensive, complicated, and time-consuming for implementation at mill sites. This thesis reports the development of a rapid, colourimetric assay based on the dye methylene blue (MB) for the quantification …  Lire la suite

Two phenomena give particular emphasis to problems of Public Finance, and make necessary a thorough analytical treatment of the subject. They are: 1. The increase of public expenditures; 2. The increase and expansion of the entrepreneurial activities of the state. [...]  Lire la suite

Gaskin, Susan J. (Supervisor1)  Lire la suite

This thesis is an introduction to the ideas and attitudes of some of the women who participated in the Canadian campaign for woman's suffrage. The first chapter outlines briefly the activities of the suffragists and examines the reaction to the suffrage question of two representative women's organizations. Chapter II contains the arguments for and against woman's suffrage together with an ideological study of these arguments. The third chapter examines the suffragists' attitude toward the woman's role in society. Chapters IV and V deal with the suffragists’ tactics, the attitudes of their political allies, and the suffragists' reaction to World War …  Lire la suite

Ce mémoire explore l’utilisation des cultures sonores, dont le langage et la musique, à travers les TikToks de queers et trans de la diaspora guyanaise (République de Guyana), dans ce que je considère comme étant des formes de drag numérique : des performances racisées et « culturées » du genre et de la sexualité. Le prisme du drag numérique aide à comprendre les auto-conceptions d’endogroupes et l’existence transgressive malgré le refus et la stigmatisation sociétaux et étatiques. Avec les idées de créolisation, ce mémoire est composé de trois chapitres qui suivent des créateur·ice·s de contenu dans les diasporas au Canada, …  Lire la suite

Implicit self-esteem is the automatic and unconscious component of self-esteem, which is generally not correlated with more traditional measures of explicit self-esteem. The goal of the research presented in this dissertation was to test a cognitive model of implicit self-esteem. Drawing from interpersonal theories of self-esteem and from theories of evaluative learning, I hypothesized that implicit self-esteem is developed through repeated exposure to pairings of the self with interpersonal rejection or acceptance, leading to unconscious and automatic self--rejected or self--accepted cognitive associations. I tested this theory using a computer-based conditioning task designed to enhance implicit self-esteem through the repeated pairing …  Lire la suite

Torriano, Federico (Internal/Cosupervisor2)  Lire la suite

An investigation is made to ascertain the relative importance of three and two-body /\-nucleon potentials which have the same order of coupling constant. The three-body potential, which is derived using perturbation theory from a pseudoscalar interaction, is found to be weakly singular and hence much smaller than the two-body potential. ln addition, the largest terms are non-central. In the hypertriton where correlations are large, it is found that three-body forces are repulsive for S states and may amount to 4%. D state admixture tends to make the three-body force less repulsive.  Lire la suite

Le cerveau se développe à travers une série de processus qui se produisent lors de fenêtres périodes critique où une sensibilité accrue aux signaux génétiques et environnementaux est observée. Ces signaux incluent des perturbations impliquées dans l’étiologie du trouble du spectre autisme (TSA). Bien que le TSA ait une étiologie et présentation hétérogènes, il se caractérise par des signes tels que des difficultés d’adaptation sociale. Le TSA est caractérisé par un déséquilibre du rapport neuronal excitation/inhibition (E/I), qui joue un rôle essentiel dans la formation des circuits régissant le comportement tout au long de la vie. En effet, de nombreux …  Lire la suite

Telomerase is a ribonucleoprotein (RNP) enzyme responsible for the replenishment of repetitive DNA sequences present at the ends of most eukaryotic chromosomes. Telomerase is minimally composed of a protein catalytic subunit, the telomerase reverse transcriptase (TERT), and an RNA subunit. Using a small single-stranded segment (7--11 nucleotides) of the telomerase RNA as a template, the active site of the TERT catalytic subunit adds complementary nucleotides onto telomeric DNA. The primary goal of the work presented in this thesis was to biochemically and functionally characterize the human telomerase reverse transcriptase (hTERT) and the human telomerase RNA (hTR), as well as to …  Lire la suite

Semiconductor nanoparticles, or quantum dots (QDs) are being increasingly applied as luminescent labels in optical studies for biophysical and cell biological applications due to their unique spectroscopic properties as compared to traditional organic fluorescent probes. However, the intermittency in the fluorescence emission of QDs, commonly referred to as 'blinking', is suggested to affect transport studies using fluctuation correlation techniques. The QD size has also been suggested to be sterically limiting for some studies. The focus of this thesis work is to examine the photophysical blinking properties and steric size effects of QD nanoparticles and determine how they influence biophysical measurements …  Lire la suite

One common way of describing the tasks addressable by machine learning is to break them down into three categories: supervised learning problems, unsupervised learning problems, and reinforcement learning problems. At least two key steps are required for solving problems in any of these categories: one must construct a class of models broad enough to contain a reasonable solution to the problem at hand, and one must design a search process capable of finding a reasonable solution based on some available data. In realistic settings, a proper balance must be struck between the representational capacity of the model class through which …  Lire la suite