McGill University Thèses et mémoires par auteur commençant par B

Variability is an intrinsic property of complex biological systems, including the human brain. At rest, brain signals fluctuate at multiple temporal scales. Micro- and meso-scale empirical studies and computational modeling work have demonstrated that these fluctuations are crucial for optimal brain function. Corresponding macroscale evidence remains however scarce, due to the complex and indirect nature of the most widely studied macroscale brain signal, the functional Magnetic Resonance Imaging (fMRI) Blood-Oxygen-Level-Dependent (BOLD) signal. Building a comprehensive understanding of fMRI BOLD signal variability is thus necessary, given fMRI’s accessibility and applicability as a tool to probe brain function and behavior. In this …  Lire la suite

Zsombor-Murray, Paul J. (Supervisor)  Lire la suite

Grad, Roland (Supervisor1)  Lire la suite

Background Bone graft procedures are commonly performed worldwide for segmental bone defects resulting from high-energy trauma, congenital deformity, infection or tumor resection. The current gold standard for repair of large long bone defects is the use of bone and blood vessels, as vascularized bone graft, harvested from another part of the body and transplanted to the area of the missing tissue. This creates significant donor site injury and is often an inadequate anatomical match. Making synthetic vascularized bone without recourse to potentially dangerous and expensive growth factors can potentially revolutionize reconstructive surgery and provide significant improvements in patients' lives. Inducing …  Lire la suite

Corriveau, Claudia (Supervisor2)  Lire la suite

To cut or not to cut? This dilemma points to an important aspect of collaborative research (Coburn & Penuel, 2016) that relies upon video captures from classroom activities to provide the impetus for teacher reflection on practice. Our research team partnered with consultants and teachers in youth sector mathematics to form a community of practice (CoP) (Wenger, 1998). This self-study reflects on one of many instrument producing activities. Specifically, the process of turning raw footage into edited clips. It describes the tensions that arise between researchers and teachers by adopting the framework of cultural-historical activity theory (Engeström, 1987). The data …  Lire la suite

The retreat of the glaciers of Peru's Cordillera Blanca is a potential threat to the human, ecological and economic welfare within the Rio Santa watershed. In a context of increasing stress on regional water resources, the relative contributions of groundwater – a major component of the region's dry-season stream flows - remain poorly characterised and oversimplified in existing hydrological models. By characterising both the variability of the groundwater contribution in space and time, identifying the major relevant hydrogeological processes, and using these data to produce a new mass balance based hydrological model, I investigate to what extent the forecasted loss …  Lire la suite

G protein coupled receptors, G proteins and their downstream effectors adenylyl cyclase (ACs) were thought to transiently interact at the plasma membrane by random collisions following agonist stimulation. However a growing number of studies have suggested that a major revision of this paradigm was necessary to account for signal transduction specificity and efficiency. The revised model suggests that signalling proteins are pre-assembled as stable macromolecular complexes together with modulators of their activity prior to receptor activation. How and where these signalling complexes form and the mechanisms governing their assembly and maintenance are not completely understood yet. Initially, we addressed this …  Lire la suite

Mitchell, Claudia A. (Supervisor2)  Lire la suite

There is great interest in solving microwave propagation problems in the urban environment, for planning and simulating cell phone systems. The most accurate approach would be to solve Maxwell's equations for the unknown field strength at every point. Traditional computational methods require dividing space into N subregions (e.g. finite elements) that are no longer than about half a wavelength across, and introducing several unknowns per subregion. This thesis investigates computationally efficient methods of solving such problems on electrically large domains and as a result, the Multi-Level Fast Multi-pole Method (MLFMM) is implemented to resolve two-dimensional problems and predict cellular signal …  Lire la suite

Gravel, Simon (Internal/Supervisor)  Lire la suite

The objective of this study was to examine the effects of plant sterols and/or glucomannan on lipid profiles and cholesterol kinetics in hyperlipidemic individuals with or without type 2 diabetes. It was hypothesized that plant sterols and glucomannan reduce circulating cholesterol levels and may have an additive or synergistic effect when combined by reducing cholesterol absorption. Thirteen type 2 diabetics and sixteen non-diabetics all mildly hypercholesterolemic free living subjects participated in a randomized crossover trial consisting of 4 phases, 21 days each. Subjects consumed plant sterols and glucomannan during the trial. Overall reductions in total and LDL-cholesterol levels were greater …  Lire la suite

Il est bien établi que la vitamine D contribue à la santé osseuse. Des données récentes d'études transversales, de cohortes prospectives et d'essais cliniques suggèrent que la vitamine D pourrait jouer un rôle dans la diminution des capacités fonctionnelles avec l'âge; toutefois, certaines lacunes de ces études n'ont toujours pas été étudiées. On sait peu de choses au sujet des niveaux de vitamine D chez les personnes âgées autonomes, en bonne santé, vivant en Amérique du Nord. Ces personnes peuvent être plus vulnérables aux carences d'une part à cause d'un faible apport en vitamine D et, d'autre part, à cause …  Lire la suite

Aucubin, a compound isolated from the leaves of Aucuba japonica and other plants, has been assigned the structure by Karrer and Schmid. It is of interest as the first x-furanol derivative reported as a natural product. [...]  Lire la suite

Neurogenic claudication is often seen in patients with lumbar spinal stenosis. The pathogenesis of neurogenic claudication is thought to be due to relative ischemia of cauda equina roots during exercise. We studied the effect of transient ischemia brought on by exercise on motor conduction in patients suffering from lumbar spinal stenosis. We found that there is a statistically significant difference in the motor evoked potential latency time and in the peripheral motor conduction time measured before and after exercise in the patients with signs of neurological deficit (Hest p<O.0001). This difference was not found to be statistically significant in patients …  Lire la suite

We introduce and study new lattice gas models of hydrodynamics to simulate thermal fluids in non-equilibrium. The new approach consists in modifying the conventional Lattice Gas Cellular Automata method for fluids by removing the constraints of the Fermi exclusion principle and by introducing internal potential energy levels for the particles. These modifications allow the effective employment of Monte-Carlo dynamics for the evolution of the models, so that the temperature is defined in a natural way, and the introduction of interactions becomes straightforward. Because the transport properties of fluids determine their behavior in non-equilibrium, we study in detail the effect of …  Lire la suite

Harris, Richard (Supervisor)  Lire la suite

À la suite d'une expérience douloureuse, les individus apprennent à éviter la répétition d'actions qui ont des conséquences nocives, en apprenant de manière adaptative à éviter la douleur. Cependant, ce comportement peut devenir inadapté lorsque l'action précédemment douloureuse n'est plus nocive, mais que l'individu continue à l'éviter en raison de la peur persistante de la douleur anticipée, ce qui entraîne des récompenses manquées et des opportunités perdues. Ce cycle d'évitement persiste jusqu'à ce que la réexploration de l'événement permette à l'agent d'apprendre que la douleur a disparu. Pour mieux comprendre ce phénomène, nous avons mené deux expériences distinctes axées sur …  Lire la suite

La progranuline est une glycoprotéine sécrétée se composant de sept répétitions et demi en tandem du motif de granuline riche en cystéine. La progranuline est capable de moduler la prolifération et la migration de cellules et est aussi impliquée dans différents mécanismes biologiques tels que l'homéostasie épithéliale, la cicatrisation, le système immunitaire ainsi que la différentiation sexuelle du cerveau et la formation de tumeurs. Récemment, des mutations du gène de la progranuline chez l'homme ont été associées à une forme de démence autosomale fronto-temporale dominante. Malgré le nombre élevé de publications rapportant l'implication de la progranuline dans de nombreux événements …  Lire la suite

Non-francophone teachers of French as a second or additional language (FSL) often struggle with overwhelming oral anxiety, consequent low self-confidence, and workplace marginalisation. Core French or Basic French teachers, in particular, and their subjects have been undervalued (Carr, 2007; Lapkin, McFarlane, & Vandergrift, 2006; Richards, 2002). Moreover, recent national FSL research points to challenges in the areas of teacher attrition, lack of methodological and /or linguistic preparation, and lack of professional development opportunities in the FSL context (Karsenti, 2008; Salvatori, 2007). In this dissertation, I present the findings of my qualitative research study, which examined the conditions and experiences of …  Lire la suite

The growth of grandparent caregivers has significantly increased in recent years, and therefore, more research is needed in this area. This particular qualitative study explored the feelings and experiences of permanent grandparent caregivers between the ages of 58 and 71. Data was collected using a semi structured interview format from four separate couple grandparents and one single grandmother. Although the study was limited due to the small sample size, the findings showed that despite some rewards, grandparent caregivers experienced a number of emotional issues. In analyzing the written transcripts, several themes emerged, included: feelings of loss; anger and frustration, disappointment …  Lire la suite

Jensen, O. G. (Supervisor)  Lire la suite

Malachi is a song cycle in one movement for soprano and an ensemble of fourteen musicians. It is a musical setting of eleven parts from the poem Malachi (in Hebrew: מלאכי) by Omri Livnat (b. 1993).The poem’s main subject is an enigmatic entity named Malachi (in Hebrew, also: “my angel”), inspired by the homonymous biblical prophet. At times, he is a lover; at others, a prophet or a god. A major share of the musical setting explores the notion of betweenness, which is woven through the entire poem.The musical material follows two types of models. The first is sound recordings …  Lire la suite

Dans le domaine de l'optomécanique, les forces de radiation ont permis un particulièrementgrand degré de contrôle sur la fréquence et la dissipation d'éléments mécaniques. Dansle cadre de cette dissertation, nous proposons d'abord une catégorie de systèmes optomé-caniques où la lumière exerce une forte influence similaire sur deux autres paramètres fondamentaux: la géométrie et la masse. En appliquant un piège optique au site réticulaired'un cristal phononique élargi, nous démontrons qu'il devrait être possible de créer un modemécanique localisé accordable. En raison des couplages simultanés et constructifs de la lumière avec le continuum de modes de la structure, nous estimons qu'un pouvoir …  Lire la suite

Improvements have been made in four aspects of grey scale CAPPI displays for weather radars. In order to improve continuity of the echo patterns across the boundary between adjacent CAPPI elements, the gaps between elements have been reduced. The grey scale equipment is now used in such a way that the no-signal areas of the cathode ray tubes do not produce any luminance. [...]  Lire la suite

The properties of (beta)-N-acetylhexosaminidase (HEX EC 3.2.1.30 and 3.2.1.53) in canine serum during endotoxin induced experimental shock were investigated. In normal canine serum, HEX activity is very low and the enzyme exists in two major isoenzymic forms: a predominant acidic form (HEX A) and a basic form (HEX B). Both HEX A and HEX B as well as a third isoenzyme HEX A('1) are also present in canine tissues. Only HEX A and HEX B are present in the urine. "Shocked" serum contains very high levels of total HEX activity with increased activity of both isoenzymes HEX A and HEX …  Lire la suite

Introduction: Active surveillance (AS) is commonly recommended for men with localized low-intermediate–risk prostate cancer (PCa). The aims of our study were to evaluate clinical and pathological factors that influence the risk for disease progression in a cohort of patients with low-intermediate risk PCa under AS and to assess the probability that patients with PCa would develop unfavorable disease features (UDF) while under AS for the purpose of evaluating whether immediate hemiablation therapy (HAT) could bring clinical benefit to selected patients.Methods: We studied a total of 300 patients diagnosed between 1992 and 2012 with prostate adenocarcinoma with favorable parameters or who …  Lire la suite

Field evidence suggests that the fate of sedimentary dissolved organic carbon (DOC) is linked to the diagenetic cycles of iron and manganese in marine sediments. Co-variations of their concentrations in sediment porewater, as well as the release of DOC upon the reductive dissolution of authigenic iron and manganese oxides lead us to believe that sorption (i.e., co-precipitation and/or adsorption) onto these oxides may play an important role on the diagenetic behavior of DOC. This DOC sink, if it exists, would considerably alter our views of the mechanisms that regulate DOC fluxes across the sediment-water interface as well as their quantification. …  Lire la suite

We have conducted a phenomenological research with four women victims of rape in order to discover the impact of the elements which give meaning to their lives, on their recovery. The results of our research demonstrate that overall the elements of the meaning of life have been beneficial for women's recovery. The elements that were identified are the importance of children, the philosophy of life, the goals to achieve, the significant relationships, the financial autonomy and helping others. Those elements have been identified in two previous researches. However two new elements appeared which are the attachment to their job and …  Lire la suite

Les protéines de la myéline du cerveau de souris ont été séparées à la suite d'une électrophorèse sur gel de polyacrylamide et analysées à l'aide d'un essai radioimmun pour la présence de protéines reliées antigéniquement à la protéine basique de la myéline (PBM). Nous avons ainsi identifié des protéines de poids moléculaire de 21,500, 18,500, 17,000 et 14,000. Lors d'études de structure comparatives, nous avons démontré que la PBM de poids moléculaire de 18,500 possède la même séquence primaire que la PBM de 21,500, sauf pour l'omission d'un domaine d'environ 30 acides aminés près du site N terminal; la PBM …  Lire la suite

Cette thèse examine l'impact de diverses techniques d'augmentation de données sur les performances de l'apprentissage par renforcement (RL) dans différents environnements. En évaluant systématiquement des techniques telles que le padding, la rotation et la variation de contraste, nous visons à identifier les paramètres d'augmentation optimaux qui améliorent la généralisation et l'efficacité des modèles RL. Notre étude inclut l'analyse de métriques statistiques comme les distances de Hamming et de SSIM pour quantifier le degré d'augmentation et sa corrélation avec les améliorations de performance. Les résultats soulignent l'importance de stratégies d'augmentation spécifiques à l'environnement, démontrant que les paramètres efficaces varient considérablement entre …  Lire la suite

The convulsant and K$ sp+$ channel blocker, 4-aminopyridine (4AP), induces two types of synchronous, spontaneous field potentials in the stratum radiatum of the CA3 subfield, in an in vitro hippocampal slice obtained from adult rat. The first type of activity is a positive-going interictal-like potential that corresponds to a burst of population spikes, and is abolished by non-NMDA receptor antagonists; the second type of field potential is a low frequency, negative going synchronous event which is sensitive to GABA$ rm sb{A}$ receptor antagonism. Knowing that in the hippocampus, adenosine A1 receptors are located presynaptically, on the terminals of excitatory neurons, …  Lire la suite

The objectives of this thesis were to study the generation, the modalities of propagation and the mechanism of control of limbic seizures originating in the entorhinal cortex. Entorhinal ictal-like discharges induced by bath application of 4-aminopyridine to hippocampal-entorhinal slices were initiated by a synchronous GABAA receptor-mediated potential that was associated with a transient rise in extracellular potassium. Seizure-like activity of entorhinal cortex origin, induced by either 4-aminopyridine or low-magnesium was disrupted by hippocampal interictal discharges generated in the CA3 region. Blockade of ictal activity could also be achieved through rhythmic electrical stimulation of hippocampal outputs. Schaffer collateral cut disclosed the …  Lire la suite

Dubrovsky, B. O. (Supervisor)  Lire la suite

Low, Bronwen (Internal/Supervisor)  Lire la suite

Inflammatory bowel diseases (IBD) are a group of complex inflammatory diseases of the gastrointestinal tract, the two main forms of which being Crohn's disease (CD) and ulcerative colitis (UC). Mechanisms involved in disruption of the intestinal epithelial barrier, microbiota symbiosis and immunological tolerance are posited to contribute to IBD. Genetic and functional studies have recently implicated cell death as a potential pathological mechanism in IBD. The predominant view that apoptosis, a physiologically essential cell death program, is the dominant form of cell death in IBD is now challenged with the recent discovery of regulated necrosis, including necroptosis. 'Patchy necrosis' has …  Lire la suite

Patterson, D. (Supervisor)  Lire la suite

Three solution thermodynamic models are studied: the first one, FHV, is the classical Flory-Huggins using the Flory-Huggins combinatorial and in which the interactional term is a function of the molecular volumes. The second one, FHS, uses the same combinatorial but considers the interactional term as a function of the molecular surfaces. The third one, MCS, changes the combinatorial with "s", the surface/volume ratio, keeping the interactional term as a function of the surfaces. These models are first tested with the classical system polystyrene-cyclohexane. The FHV model predicts good phase separation temperatures but gives wrong coexistence curve shape and critical compositions. …  Lire la suite

This research attempted to examine the reasons why children and youths disclose their sexual victimization, as well as the manner of their disclosure, specific to the school setting. An original questionnaire was developed, and given out to all the school social workers from one social service agency. Each worker chose, non-randomly one case of sexual abuse disclosure. It was hypothesized that if a child or youth had decided to disclose their sexual victimization in the school setting they would do so in a planned and overt manner, choosing an adult with whom they had a close, positive and trusting relationship; …  Lire la suite

Cette thèse présente deux perspectives en ce qui a trait à la participation active en musique: celle des effets de l'anxiété de performance musicale (APM) chez les musiciens ayant différents parcours musicaux, et celle de l'impact de la pratique instrumentale sur la santé et le bien-être des aînés. Les questions de recherche visent à déterminer (a) dans quelle mesure la participation musicale apporte des bienfaits biologiques, psychologiques et sociaux et (b) dans quelle mesure certains paramètres biologiques, psychologiques et sociaux influencent les niveaux d'APM. En se référant au modèle Biopsychosocial (Engel, 1980), les hypothèses proposent que l'APM aurait des effets …  Lire la suite

Ce projet de recherche visait à développer et à valider un nouveau questionnaire permettant d'évaluer dans quelle mesure les performances hautement stressantes affectent la perception du niveau d'anxiété de performance musicale (APM) des musiciens populaires. À cet effet, nous avons créé le «Performance Anxiety Inventory for Musicians » (PerfAIM), un questionnaire auto-administré démontrant des propriétés psychométriques satisfaisantes. Les objectifs spécifiques de ce projet consistaient à évaluer la validité et la fidélité du questionnaire. La validité de contenu et la validité apparente ont été établies avec des groupes focus et des entrevues auprès d'experts. Un échantillon de 69 musiciens populaires (professionnels …  Lire la suite