McGill University Thèses et mémoires par auteur commençant par R

A numerical model is being developed for ice forecasting which is based on a granular dynamics approach. This model is intended to analyse the movements of broken ice fields at the mesoscale; i.e. for length scales of the order of 100 km and time scales of the order of a few days. It will therefore be useful for navigation, for the operation of offshore drilling platforms and for commercial fishing. At the mesoscale, the forces governing the motion of ice floes are wind drag, water drag, Coriolis force and the contact forces arising from internal collisions. Expressions are developed to …  Read more

Populations of Chlamydomonas were maintained in a benign laboratory environment as obligatory sexual or asexual populations for five years. Sexual reproduction is expected to facilitate the elimination of mildly deleterious mutations and thereby increase the mean fitness of a sexual population relative to an asexual population (Kondrashov 1988). Fitness in competition and in pure culture was measured. In neither of the fitness assays, both in solid and liquid cultures of Chlamydomonas, was a fitness advantage of sexual reproduction seen, even though the results varied depending on the definition of fitness. I hypothesized that the effect of mutation clearance could be …  Read more

De Mestral, Armand (Internal/Supervisor)  Read more

Many workplace tasks involve unilateral and/or bilateral overhead tasks. Overhead work and muscle fatigue have been shown to be important risk factors for musculoskeletal disorders. However, the mechanisms of fatigue adaptations to repetitive overhead upper limb movements remain unclear. Specifically, how hand dominance (dominant versus non-dominant), sex and arm task (unilateral versus bilateral) affect electromyographic adaptations to fatigue is poorly understood. The objective of this thesis was to examine the sex-specific effects of hand dominance on electromyographic characteristics during unilateral and bilateral overhead repetitive tasks.Healthy young male and female adults were recruited for two separate experiments (experiment 1, n = …  Read more

L'objectif de ce projet de Maîtrise était d'explorer les effets spécifiques au sexe de la fatigue musculaire localisée sur l'activation musculaire lors d'une tâche répétitive multi-articulaire. Les participants sans antécédents de blessures au haut du corps, de douleurs lombaires, de troubles musculo-squelettiques ou cardiovasculaires ont subi 3 protocoles de fatigue distincts qui visaient à fatiguer le coude, l'épaule et le dos. Avant et après chaque protocole de fatigue, les participants ont effectué une tâche de pointage répétitif de 30 secondes dans le plan horizontal tandis que les données électromyographies (EMG) étaient enregistrées à partir des muscles des bras, des épaules …  Read more

The question of prematurity and its role in the development of spasticity is investigated in this study. 319 spastic quadriplegic and 112 spastic paraplegic children from The Montreal Children's Hospital were selected as probands. The incidence of prematurity in this group was 33.8 per cent. [...]  Read more

Dasgupta, Kaberi (Supervisor1)  Read more

Objective: To evaluate caregiver's ability to perceive pain in their children with Down syndrome. Method: Data were gathered from parents of children with Down syndrome in French and English samples in Quebec and Ontario respectively, using the Oral assessment-in-Down-syndrome (OADS) questionnaire, the non-communicating-children's-pain-checklist (NCCPC) and additional questions related to the last pain. Results: Parents who reported difficulty perceiving pain also observed more behaviours of pain compared to those reporting no difficulty. Age of children was a determinant in the level of difficulty that parents had perceiving pain, with decreasing difficulty from 68% to 31% as age increased. Severe pain, long …  Read more

Ultrafast electron diffraction with bunch compression has reached a level of performance which allows for the accurate measurement of time-resolved diffuse scattering with a time-resolution of 150 femtoseconds. This information extends ultrafast electron diffraction to time- and momentum-resolved studies of phonon systems (lattice waves) in single-crystal materials. In this dissertation, time-resolved diffuse scattering is explored in two low-dimensional materials. First comes graphite, where anisotropic electron-phonon coupling and stiff phonon bands allow for maximum measurement contrast. The redundancy in ultrafast electron scattering patterns, as well as crystal symmetry, are used to robustly recover the occupancy of all in-plane phonon modes. The …  Read more

In this thesis, a computational techniques for visualizing crystalline electrostatic potential on the femtosecond time-scale is presented. This technique, called scattering potential mapping, displays local information on lattice changes and charge-density reorganization over time from ultrafast electron diffraction data. It can be applied directly on diffraction intensities from previous experiments. This tool is consistent with previous results, most importantly with radial pair-distribution function analyses. Scattering potential mapping could lead to easier comparison between experiments and simulations. A baseline-removal routine built on the discrete wavelet transform is also detailed in this work, as a replacement for the unstable interpolation and curve-fitting …  Read more

En 2009, la National Institute of Mental Health (NIMH) lance le Research Domain Criteria (RDoC). En tant que plus grand organisme subventionnaire de recherche en psychiatrie au monde, et en réponse aux critiques soulevées par les systèmes de classifications psychiatriques actuels tels que le manuel diagnostique et statistique des troubles mentaux (DSM), la NIMH vise par cette initiative à promouvoir une meilleure compréhension des enjeux fondamentaux de la pratique psychiatrique contemporaine. L’idée est de restructurer la discipline sur de nouvelles et plus robustes fondations théoriques. Alors que plusieurs ont décrié les présuppositions conceptuelles de l’initiative, ce mémoire vise plutôt à …  Read more

Le but de ce travail est d'arriver à la détermination du niveau d'induction (de tension et de courant lorsqu'un contact au sol est établi) sur un objet placé dans le champ électrostatique d'une ligne triphasée à très haute tension. Cet objet peut être quelconque mais plutôt de dimensions finies, v.g. un camion ou une remorque, de sorte que l'étude est essentiellement à trois dimensions. Ceci d'ailleurs explique le fait qu'aucune étude théorique, à la connaissance de l'auteur, n'existe sur ce sujet. On connait bien le phénomène d'induction électrostatique sur un fil ou câble parallèle à une ligne sous tension lorsque …  Read more

Magdélenant, J. L.  Read more

Le potentiel d’amélioration de la production alimentaire peut être atteint par l’exploitation du concept de « tracteur intelligent » pour les technologies à taux variable (VRT). Un contrôleur en temps réel intégré est la nouvelle possibilité développée dans ce projet. Ce système permet aux petites et moyennes productions agricoles d’adopter des pratiques d’agriculture de précision et donc d’optimiser leur production à des coûts relativement bas. Cette VRT a été explorée à travers différentes opérations agricoles. Pour présenter le concept de « tracteur intelligent », cette même option a été utilisée pour modifier la vitesse d’un tracteur en fonction de : …  Read more

Fernando Saltiel (Supervisor2)  Read more

A system is described for time-lapse stereoscopic cloud photography using 16-mm cameras, for rectification of the photographs for camera tilt, and for analysing them to obtain cloud dimensions by superimposing the projected images of stereo-pairs on a gridded screen. A discussion of theoretical photogrammetry as applied to cloud photography, and an analysis of the system errors and measurement uncertainties are given. [...]  Read more

Precup, Doina (Supervisor)  Read more

Les exigences strictes de la sélection naturelle ont abouti à une grande variété de matériaux multifonctionnels à haute performance à travers l'arbre de la vie. Face à notre courante crise environnementale, la durabilité inhérente des structures biologiques en fait un domaine d'étude scientifique attirant et inspire une nouvelle génération de matériaux libre de produits pétrochimiques. Les moules marines s’ancrent aux roches grâce à une structure appelé byssus (ou ‘barbe’), qui est devenu un système modèle prometteur en raison de son excellente adhérence aquatique et sa dissipation de l'énergie d'impact des vagues. Plus important encore, les fils individuels qui composent le …  Read more

Children who are hospitalized in a pediatric intensive care unit (PICU) are subjected to a barrage of highly invasive, often painful interventions necessary in overcoming the critical period of their illness. While the majority of these children survive, little is known about the impact of critical illness on their subsequent psychological adjustment. The purposes of this study were (a) to compare the psychological responses of children hospitalized in a Pediatric Intensive Care Unit (PICU) with those of children hospitalized on a general ward; and (b) to determine whether there was a relationship between children's psychological responses post-hospital discharge and their …  Read more

The people who live in the City of Montreal are exceedingly various. There are officially two languages and unofficially dozens. Many areas of the city provide examples of "culture islands" - those fast-disappearing settlements of "alien" peoples who preserve their alien ways of life in a new country, and so impart to the latter "atmosphere" and "flavour". To serve and satisfy the various demands of these people there are many and different institutions making it possible for individuals, if they wish, to live their entire lives in their native atmospheres.  Read more

Raghavan, G. S. Vijaya (Supervisor)  Read more

A double-pipe helical heat exchanger was studied numerically and experimentally for both heat transfer and hydrodynamic characteristics. Results from the numerical trials show that the inner Nusselt numbers in the heat exchanger were similar to literature data, despite the different boundary conditions. Nusselt numbers in the annulus were correlated to a modified Dean number. It was shown that the thermal resistance in the annulus to be the greatest limiting factor for the heat transfer, and heat transfer rates could be increased by increasing the inner tube diameter. The Prandtl number was shown to affect the inner Nusselt number; however the …  Read more

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease characterized by leukocytic infiltration of the central nervous system (CNS) and demyelination and remission/relapse. It is induced by CD4$ sp{+}$ T cells. We used reverse transcriptase/polymerase chain reaction to analyse T cell and cytokine gene expression in the CNS of SJL/J mice with myelin basic protein-induced EAE. Undetectable in normal CNS and cerebrospinal fluid, the expression of CD3, IL-2, IFN-$ gamma$, and TNF$ alpha$ increased in EAE, correlating with disease severity, then dropped to background levels during remission. IL-2 and IFN-$ gamma$ were produced by CD4$ sp{+}$ CD45RB$ sp{ rm low}$ T …  Read more

The goal of the present research consisted in trying to understand whether we process the meaning of words similarly when they are repeated or presented for the first time in an experiment. A number of studies have shown that repetition can disrupt the processing of meaning, resulting in a reduction or a suppression of semantic effects. I have investigated whether semantic effects such as congruity effects, concreteness or effects of semantic category would be maintained or suppressed for highly repeated words. Behavioral as well as event-related potentials (ERPs) measures were acquired. Results indicate that semantic processing and its neural bases …  Read more

The course and prognosis of childhood onset multiple sclerosis (MS) is not well defined unlike that with adult onset. A cohort of 380 patients with childhood onset (before the age of 16) MS and 3367 with adult onset were identified through the European Database for Multiple Sclerosis. The median time to reaching scores of four and six on the disability status scale was longer for childhood onset MS patients (20 and 29 years) compared with adult onset patients (12.8 and 23.7 years; p<0.0001). Two years after onset, the main prognostic factors of disability in childhood onset MS patients were age …  Read more

This report posits a need for social work intervention into suicidal behavior. Responsibility for prevention of suicide presently rests with the medical profession in general and with psychiatry in particular, because society defines such behavior in terms of mental illness. The medical model views the patient as sick, diag­noses his illness, and treats it, predominantly with drugs. This has been very successful when applied to physical disease, ss successful for mental illness, and quite un­successful when applied to self-destructive behavior. This lack of success is explained by the nature of suicidal be­havior: it is symptomatic of social difficulty, not a …  Read more

Jardim, Armando (Internal/Cosupervisor2)  Read more

During development of rats, hepatic microsomal NADPH dependent lipid peroxidation increased to reach a maximum activity at 25 days of age and then declined to adult activity by six weeks of age. Increased activity in 25 day old tats resulted in a greater decrease in the ability of microsomes to N-demethylate aminopyrine after preincubation under conditions which promoted lipid peroxidation. Although total NADPH oxidase activity was similar in 25 day old and adult rats, NADPH oxidase activity, which was specific for lipid peroxidation, was increased in 25 day old rats. Microsomal NADPH dependent lipid peroxidation reduced the magnitude of type …  Read more

Les théories de la fugue au XIXe siècle reposent sur deux épistémologies opposées : le rationalisme et l’empirisme. Les théories rationalistes considèrent la connaissance comme issue de l’esprit et dérivée de l’intuition ou de la déduction. À l’inverse, les théories empiristes considèrent que la connaissance provient de l’étude du monde et est générée par le raisonnement inductif. Cette dichotomie et son application à la théorie musicale sont explorées à travers l’analyse des théories de la fugue au XIXe siècle. La première épistémologie est incarnée par Anton Reicha, qui estime que la véritable nature de la fugue n’est pas encore connue, …  Read more

The first phase of the research involved analyses of a linked database of a large sample of Canadians surveyed in 2001 as part of the Canadian Community Health Survey (CCHS) 1.1 and followed up with recorded death events to December 31, 2011 and hospitalizations to March 31, 2004. Analyses were stratified by two age groups, 55 – 64 (n=6,822) and 65 and older (n=8,966), owing to differing patterns of mortality and health care utilization for these age divisions. Social support measures operationalized several support constructs of interest, including tangible support, affection, emotional and informational support, positive social interactions, living alone, …  Read more

Baker's yeast, Saccharomyces cerevisiae, is a well-studied model system in genetics and molecular biology. It is also a promising system for experimental ecology, evolution, and epidemiology, and is very important in the fermentation industry. The large amount of information generated by studies using this organism cannot be fully exploited until sufficient ecological data is gathered. Only when the natural environment of S. cerevisiae is well characterized can research using this yeast as a model system be put into context. The lack of information about the natural environment of S. cerevisiae is what prompted this work. First, I review the current …  Read more

This thesis reports a study of the motivational and emotional function of the midline and intralaminar structures of the thalamus of the rat. Following the work of Moruzzi and Magoun (1949), and the activation theory of emotion developed by Lindsley (1951), a great deal of psychological research has been devoted to the relation between behavior and the activity of the non-specific projection system (or systems) of the brain stem. Most of this work, however, has been directed toward the functions of the ascending reticular formation of the medulla and mesencephalon.  Read more

Walter, H. (Supervisors)  Read more

We define the notion of relative sectional curvature for 2-complexes, and prove that a compact angled 2-complex that has negative sectional curvature relative to planar sections has coherent fundamental group. We analyze a certain type of 1-complex that we call flattenable graphs Gamma→ X for an compact angled 2-complex X, and show that if X has nonpositive sectional curvature, and if for every flattenable graph pi1 (Gamma) → pi1( X) is finitely presented, then X has coherent fundamental group. Finally we show that if X is a compact angled 2-complex with negative sectional curvature relative to pi-gons and planar sections …  Read more

La prolactin(PRL) et sa voie de signalisation en aval Jak2/Stat5a sont requies à la croissance de la glande mammaire, ainsi qu'à la différentiation des épithéliales mammaires. Cependant, le rôle de la PRL dans le développement du cancer du sein n'est pas encore clair. Quelques preuves récentes, obtenues par notre laboratoire, montrent que la PRL pourrait supprimer certains aspects de la carcinogenèse du sein. Par consequent, nous avons effectué une analyse de puce à ADN pour examiner les genes cibles de la en utilisant les cellules épithéliales mammaires de souris HC11. Sur la base de l'analyse micro-array, nous avons identifié la …  Read more

Contexte Malgré les nombreuses pandémies survenues au cours de l'histoire et l’accès aux technologies du 21ème siècle, le monde n'était toujours pas prêt à affronter le nouvel agent pathogène connu comme le coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2) en 2019. Jusqu'au développement et à la distribution de vaccins, les responsables de la santé se fiaient beaucoup sur les diagnostics pour limiter la propagation de la maladie. Le test de transcription inverse suivie d'une réaction en chaîne de la polymérase (RT-PCR) continu d’être la référence idéale pour le diagnostic de SRAS-CoV-2 grâce à sa sensibilité et à sa spécificité …  Read more

The Sloko Lake Volcanic Complex (SLVC) is the largest erosional remnant (600 km2 in area) of a Paleogene volcanic complex within the northern Canadian Cordillera. It is located along a linear trend of volcanic and plutonic rocks that once formed part of a widespread continental volcanic arc that extended from west-central British Columbia into southeastern Alaska and the southwestern Yukon Territory. The preserved stratigraphy within the SLVC is 1500 m thick, consisting of flat to gently dipping volcanic and pyroclastic flows, with minor well-bedded epiclastic strata that were likely deposited in a westward dipping half-graben. Four stratigraphic units are defined: …  Read more

Many different methodologies have been developed for analyzing multithreaded programs. These analyses present a wide variety of approaches and tend to be rather complicated because they work on applications formed by several threads executed in a nondeterministic order. To address these issues this thesis introduces XThread, a flexible and modular framework for developing different concurrency analyses over multithreaded applications. The main objective of XTHREAD is to reduce the complexity of developing concurrency analyses by providing high level abstractions that close the breach between the language spoken by the researcher and the language the framework provides. Moreover, this framework provides different …  Read more

La pluie verglaçante pose un risque majeur le long de la vallée du fleuve Saint-Laurent au Québec. Pour les grandes villes comme Montréal, des épisodes graves peuvent avoir un effet dévastateur sur la population, les biens et le commerce. Dans cette thèse, nous effectuons une analyse à l'échelle planétaire et synoptique des épisodes de pluie verglaçante à Montréal au Québec. En utilisant les données de surface, 46 épisodes graves sont identifiés à Montréal pour la période 1979-2008. Ces épisodes graves sont ensuite divisés en trois types selon l'emplacement de l'axe du zone dépressionnaire de 500-hPa. Des représentations composites sont produites …  Read more

Une méthodologie est proposée pour réduire l'erreur dans l'estimation de la vélocité à « Particle Tracking velocimetry » (PTV) pour l'étude de la région de développement d'une couche de mélange peu profonde turbulente. Premièrement, les erreurs d'estimation de la vélocité ont été réduites en améliorant la précision de l'estimation du centre des particules en maximisant la résolution spatiale de l'image qui contient la couche de mélange. Puisque l'extension de la couche de mélange dépend de la vitesse et de la profondeur des écoulements libres ainsi que la largeur du canal, les projections horizontales des couches de mélange de 31 combinaisons …  Read more

This dissertation identifies and proposes mitigating solutions for some of the adverse economical and technical impacts of integrating wind generation into existing power systems. The main focus is on the short-term operation looking seconds to hours ahead, and on day-ahead scheduling looking 12 to 36 hours ahead. First a thorough review illustrates how wind power uncertainty affects the operation of power systems composed of conventional fossil, nuclear and hydro power sources. Then, the impact of wind power variability is studied in the short-term operations (with a time frame of less than an hour) by estimating: 1) The probability distribution of …  Read more

Let E be an elliptic curve of conductor pq^2, where p and q are prime numbers, and let K be a quadratic extension of Q. If K is imaginary and p and q are split in K, there are Heegner points on the modular curve X_0(pq^2) defined over ring class fields attached to orders in K, which can be mapped to points on E. If q is inert, there are no Heegner points on the modular curve, but points can be obtained from the Cartan non-split curve Xε(q,p). If K is real the panorama is quite different. If p is …  Read more

ABSTRACT Based on a new conception of airports, and recognizing the airport's preeminent role in strengthening a region's economy, this thesis centers on the positive and negative aspects of privatizing international airports. The core case study for the investigation is Eldorado International Airport, serving the city of Bogotá and port of entrance to the South American continent. It concludes that privatization of international airports has grown to be the best means by which large-scale aviation infrastructure projects are to be realized if airports are to not only attend rising traffic demand, but also as private enterprises that deliver users quality …  Read more

This thesis investigates how female-headed households solve their housing needs. Housing is an important resource for them: first because women spend more time in the house and home conditions are of great concern to them because these determine the time and difficulties in fulfilling their domestic responsibilities and, second, because the home is the site of production and economic activities that help increase women's low incomes. The study is based on the analysis of different women's lives in three different neighborhoods in Medellin, Colombia. This is a qualitative study aimed at providing insight into household patterns, and determining housing alternatives. …  Read more