McGill University Thèses et mémoires par auteur commençant par O

Devices controlled by cloud or edge resident coordinators are becoming an important trend for creating Internet of Things (IoT) systems and smart systems. The cloud provides a global perspective while the edge provides low latency and localized service to the devices. Coordinating these devices to work collectively to solve problems with strict timing requirements in the presence of disconnections is a challenge. An important coordination task is to have devices perform the same action at the same point in time. With the large number of devices and data being generated by millions of edge devices, there is a need for …  Lire la suite

Les dispositifs microfluidiques capillaires déplacent des liquides sans pompes, ni valves. Ils s'appuient sur les effets de tension de surface, définis par la géométrie et la chimie de surface. Cela les rend parfaitement adaptés à la miniaturisation et à l'automatisation des analyses biochimiques afin d'établir un diagnostic et dans le cadre de la recherche. Les systèmes microfluidiques capillaires sont composés d'éléments fluidiques capillaires individuels, tel que les pompes passives et les valves d'arrêts. Ces éléments sont typiquement micro-fabriqués dans des salles blanches. Cela limite l'accessibilité, augmente les coûts et ralentit le temps de prototypage. Récemment, il y a eu un …  Lire la suite

Au cours du dernier demi-siècle, les avancées instrumentales en astronomie à rayons X et gammas ont grandement amélioré notre compréhension des étoiles à neutrons. Une récente découverte importante est celle d'une classe d'étoiles à neutrons isolées, les "magnétars", dont la luminosité et des épisodes occasionnels de sursauts sont attribués à un champ magnétique élevé (10^14-10^15 G, tel que determiné par le chronométrage), contrairement aux pulsars ordinaires dont l'énergie provient du ralentissement de leur rotation. Cependant, il existe des pulsars alimentés par la rotation pour lesquels le champ magnétique déduit approche celui des magnétars. Il serait donc plausible que ces deux …  Lire la suite

This thesis examines the testimonies of victims related to the use of torture during the Pinochet dictatorship. It contends that the existence of a broad testimonial archive on torture, significantly produced by the victims themselves, points to a collective 'speech' by which victims have attempted to splinter the silence of the dictatorial state and, in the aftermath of the repression, to contest the 'official history' of the transitional state. The testimonies of torture victims, it will be argued, signify a specific mode of action, a 'doing' of memory, whereby the experience of torture is re-membered in an effort to bring …  Lire la suite

The somatosensory neocortex processes extrinsic information from the thalamus and intrinsic information from local circuits. We compared the effects of acetylcholine (Ach) on neocortical field potential responses evoked by stimulation of the whiskers and by local electrical stimulation in the upper layers of the neocortex vibrissae representation ("barrel cortex") of adult rats anesthetized with urethane. The two responses differed in terms of their frequency-dependent dynamics. In particular, the whisker response depressed when stimulated repetitively, whereas the intracortical response did not. The cholinergic system was manipulated in the barrel cortex by application of exogenous Ach using microdialysis, by increasing the endogenous …  Lire la suite

During the past fifteen years several investigators have shown that commercial or laboratory preparations of the posterior lobe of the pituitary gland when injected into frogsgive rise to a transient increase in weight. [...]  Lire la suite

Both quantity and composition of waterborne transport of dissolved organic carbon (DOC) from peatlands has been hypothesized to be affected by permafrost thaw. Changes in DOC can impact the carbon (C) balance of peatlands directly, but also the carbon balances and metabolism of downstream aquatic environments. In this study I have investigated the DOC export from different peatland types in the Stordalen catchment of northern Sweden (68.20N, 19.03E). The research was performed at various spatial and temporal scales in order to assess the importance of peatland permafrost thaw for both peatland and catchment DOC export. In the Stordalen catchment, peatland …  Lire la suite

Schettler keeps his eyes closed. Sprawled on his belly, he realizes the man, who called himself Cromboli, isn't wasn't never could be real. Cromboli puffed a cigar stub, lying in a bunkbed, and kept hitting his knees together. His legs from the knee down had been encased in carved wooden sheaths, of which he made no mention. Instead he had called atterntion to the plump young woman gyrating in naked come-and-get-me-ness only an arm's length away. His words had been, "It's going to hurt like hell, but you'll like it." Those carvings on the leg sheaths had smacked of church …  Lire la suite

The problem stated in its most general terms is this. Given a space S and a mapping t of S into itself, under what circumstances is there or is there not a fixed point? By a fixed point we mean, simply, a point x in S for which tx*x. Most investigations are concerned with single valued continuous mappings and the trend has been to search for ever larger classes of spaces for which fixed point conditions can be derived. Studies have, however, been made notably by M. H. A. Newman (15) and P. A. Smith (17) of the question of …  Lire la suite

There appeared in 1883 an article by Barlow [1] in Nature in which the problem of the densest packing of spheres is discussed from the point of view of the physical chemist. While Thue [2,3] may be credited with the earliest mathematical formulation of a packing problem, namely that of the densest packing of equal circles in the plane it was not until H. Minkowski [4] had laid a firm foundation to the Geometry of Numbers that wider interest was stirred in problems of this type. [...]  Lire la suite

Nous avons initié un programme de recherche qui a pour but de développer des sondes fluorescentes, sensibles aux radicaux libres, qui soient solubles dans les solutions lipidiques. Ces sondes devront pouvoir rapporter les activités anti-oxidantes des bi-couches lipidiques. Ce travail fournit des informations importantes pour la conception rationnelle de colorants dérivés du pyrrométhane qui pourront servir d'indicateurs fluorescents "on-off" de la visualisation des réactions redox. Dans cette thèse, nous rapportons les propriétés du nouvel indicateur Trolox-PM605 (B-TOH) qui montre un comportement fluorescent "on-off" marqué en présence de radicaux en solutions homogènes et micro-homogènes. Les spectres d'absorption et de fluorescence, les …  Lire la suite

Les médicaments stimulants (MED) sont le traitement principal pour les adultes diagnostiqués d'un trouble du déficit de l'attention avec ou sans hyperactivité (TDAH). Cependant, des traîtements non-pharmacologiques attire de plus en plus l'attention dont l'exercice d'aérobie. Mais à ce jour, aucune étude scientifique n'a pu démontrer la supériorité de l'efficacité de l'exercice d'aérobie (EA) par rapport aux traitements conventionnels pour les adultes. Par conséquent, l'objectif principal de cette étude est d'examiner l'efficacité relative de l'exercice d'aérobie (n = 21 par rapport aux médicaments stimulants (n = 10) après avoir suivi une intervention de huit semaines avec un suivi de six …  Lire la suite

In this thesis I examine a delay differential equation model for an artificial neural network with two neurons. Linear stability analysis is used to determine the stability region of the stationary solutions. They can lose stability through either a pitchfork or a supercritical Hopf bifurcation. It is shown that, for appropriate parameter values, an interaction takes place between the pitchfork and Hopf bifurcations. Conditions are found under which the set of initial conditions that converge to a stable stationary solution is open and dense in the function space. Analytic results are illustrated with numerical simulations.  Lire la suite

Infection with human T cell Leukemia virus (HTLV-1) can cause Adult T-cell Leukemia (ATL) or the neurological disorder HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). Although the majority of HTLV-1--infected individuals remain asymptomatic carriers (AC) during their lifetime, 2-5% will develop either ATL or HAM/TSP. The factors that determine HTLV-1 pathogenesis remain elusive, and therefore represent a serious obstacle in the establishment of effective therapies for HTLV-1-associated diseases. Using gene expression profiling of CD4+ T-lymphocytes isolated from HTLV-1-infected individuals, we identified candidate genes differentially regulated in HTLV-1-associated diseases. Of particular interest, SOCS1 was up-regulated in HAM/TSP and AC patients -- but not …  Lire la suite

Le rétrovirus T-lymphotropique humain (HTLV-1) est l'agent étiologique de la leucémie à cellule T de l'adulte (ATL) - une leucémie agressive et fatale des lymphocytes T CD4+. HTLV-1 est également associé à une forme de myélopathie chronique appelée Paraparésie Spastique Tropicale ou atteinte neurologique connue sous le nom de HTLV-1 - Associated Myelopathy (HAM/TSP). Bien que la majorité des individus infectés avec HTLV-1 demeurent asymptomatiques (AC) au cours de leur vie, 2 à 5% développent soit une ATL soit une HAM/TSP. Les facteurs qui déterminent la pathogénèse de l'HTLV-1 restent inconnus, et représentent donc un sérieux obstacle à la mise …  Lire la suite

The osmotic control of neurohypophysial hormone release is mediated by central and peripheral osmoreceptors which perceive changes in fluid osmolality. The mechanism underlying signal transduction in these structures, however, has remained obscure. Supraoptic neurons, which synthesize and secrete the neurohypophysial hormones, are themselves recognized to be osmoreceptors. Combined electrophysiological and micromorphometric measurements were therefore obtained in acutely isolated rat supraoptic neurons to determine the cellular basis for signal transduction in osmoreception. Osmotically-evoked changes in cell volume and a gadolinium-sensitive cationic conductance were found to be temporally and proportionally related. In agreement, cell-attached patch-clamp recordings revealed the presence of gadolinium-sensitive cationic …  Lire la suite

This thesis draws on twenty-three women's retrospective accounts of their abortion experiences to examine the course of their feelings and the social, situational and personal contexts in which these feelings arose. Their experiences and feelings were affected by abortion's morally ambiguous status; its quasi-legal status (particularly between 1969 and 1988); its provision in medical settings in ways that differ significantly from the provision of other health services; and the on-going polarized ideological conflict over its acceptability. The experiences and feelings of the women interviewed were also affected subtly and profoundly by widely held expectations about how women in such situations …  Lire la suite

Cellulose is the most abundant biopolymer in nature. Cellulose is renewable, biocompatible, biodegradable, and non-toxic. However, strong inter- and intra-molecular hydrogen bonds as well as hydrophobic interactions exist among cellulose molecules. Consequently, it is rendered insoluble in most commonly used inorganic/organic solvents. The traditional cellulose solvent from the viscose route causes serious environmental pollution, so many efforts have been made to develop novel cellulose solvents and study their dissolution mechanisms. Several solvent systems have been reported in recent years, which can be classified as acidic aqueous systems, alkali/urea aqueous systems, ionic liquid systems, and mixed solvent systems. Various cellulose-based functional …  Lire la suite

Casein Kinase I (CKI) is one of the first serine/threonine protein kinase activities to be isolated and characterized. In vertebrates, CKI represent a multigene family with seven isoforms, alpha, beta, delta, ε, gamma1-3 for which, very little is known with respect to their biological functions. This study reports that stable overexpression of CKI-gamma2 into fibroblasts impairs cell morphology and the organization of the actin cytoskeleton in a kinase-dependent mechanism and cell proliferation through a kinase-independent mechanism. In addition, by immunofluorescence we determined the subcellular distribution of CKI-gamma2 to perinuclear vesicles. Furthermore, we established that a putative prenylation motif present in …  Lire la suite

The advent of X-ray astronomy has turned the study of compact objects into one of the most active research fields in modern-day physics. Diverse luminosity phenomena have been remarked upon in neutron stars and it is believed that in many of them the neutron star crust plays a critical role. This work presents a steady-state model for the neutron star crust that describes, in particular, the profiles of temperature and flux along this region. It is divided as follows: First, a review of observational phenomena in neutron stars, where crust characteristics are thought to be crucial, are presented, alongside general …  Lire la suite

In mineral beneficiation, grinding is used to reduce the size of the ore particles, generate larger surface area, and liberate valuable components. Grinding represents the most energy consuming stage of the process. Continuous research has aimed to increase the rates and efficiencies of milling by predicting the behaviour of large industrial mills, for example, through an examination of energy-size relationships and by using population balance models. The input for these models comes from data extracted from small laboratory-scale mills or impact tests. However, these breakage-testing techniques do not properly describe the behaviour of industrial mills, since these techniques cannot achieve …  Lire la suite

This dissertation examined the influence of room acoustic variations on listener loudspeaker preferences in multichannel audio reproduction, and the extent to which listeners adapt to the room acoustics. Listener preferences among 4 different 5-channel loudspeaker systems were observed in 4 different virtual listening rooms via a binaural room scanning (BRS) measurement and playback system. To study room acoustic adaptation, 2 groups of listeners evaluated identical stimuli according to 2 different trial blocking schemes, termed either the successive or the intermixed treatment. In the successive treatment condition, the loudspeakers were evaluated under a given room acoustic condition before moving to the …  Lire la suite

This thesis deals with the long-term planning of electric energy systems. Such systems are defined by complex interconnections of end-uses, energy conversion devices and natural resources. The planning process is usually guided by a number of design criteria, namely, economic, social and environmental impacts as well as system reliability and efficiency. The planning challenge is to find an acceptable compromise among these often conflicting objectives. System efficiency is a critical design criterion normally measuring the ratio of the system output and input energies. In electric energy systems, efficiency is normally defined according to the First Principle of Thermodynamics which states …  Lire la suite

Following the important work on unit roots and cointegration which started in the mid-1980s, a great deal of econometric works has been devoted to the study of the subtleties and varieties of near nonstationarity and persistence that characterize so many economic and financial time series. In recent years research activity has gained importance with outstanding contributions made on estimation and testing of a wide variety of long memory processes, together with many interesting and imaginative applications over a wide variety of different fields of economics and finance. For these reasons, this study provides empirical evidence to an aspect of fractional …  Lire la suite

Les problèmes de apprentissage automatique sont naturellement de grande dimension et des méthodes d'optimisation doivent être spécifiquement conçues pour les resoudre. L'un des algorithmes les plus communs est le du gradient stochastique. Lorsqu'il s'agit d'un problème fortement convexe, la vitesse de convergence optimal est O(1/k).Cette valeur est théoriquement bornée, mais la constante correspondante peut encore être améliorée. Dans cette thèse, nous commençons par passer en revue les méthodes d'optimisation pour l'apprentissage automatique. Ensuite, nous explorons les constantes théoriques de convergence pour la descente de gradient stochastique avec le taux d’apprentissage optimal et un taux d’apprentissage inspirée par Polyak. Enfin, nous …  Lire la suite

The adhesion of wet fibers is usually explained by the presence of capillary forces, which keep the swollen fibers together. These bonds are due to the free water present outside the wall of the swollen fibers. However, what happens when the free water is being removed and the tensile strength of the wet web continues to increase is not well understood. Tensile strength's measurements of refined fibers in presence of polyelectrolytes and mineral particles suggest that no enhancement of bonding occurs between the fibers when the free water is gone. The addition of microfibrils tends to enhance the wet web …  Lire la suite

In this thesis, physical and biological aspects of three linear-accelerator-based stereotactic radiosurgery techniques, namely the dynamic rotation, static conformal beam, and intensity-modulated beam, are compared. Comparisons are carried out using simulated targets which include spheres, hemispheres and a C-shaped target wrapped around a critical structure, inserted within modified slabs of an Alderson Rando anthropomorphic phantom. The phantom is CT-scanned with a stereotactic frame, and the images are transferred to the treatment planning systems. The best possible treatment plans are generated for each simulated target and for each of the three techniques. Treatment plans are compared using both physical (homogeneity and …  Lire la suite

This essay discusses Le Corbusier's Modulor through its appearance in the Poeme de l'angle droit. The Poeme reveals the architect's later thinking in a synthetic and precise way, offering precious help for its comprehension. A study of the Modulor in such context demonstrates that it was more than an attempt to develop a modular methodology. Embodied in the Poeme, the Modulor discloses Le Corbusier's struggle to create a framework for his practice, providing invaluable insights into our present condition.  Lire la suite

Piana, Roberta La (Supervisor2)  Lire la suite

"This study lays stress on the need for training of parents in basic interpersonal skills, deeming it insufficient to simply offer parents child-rearing information and behavioral guides. It is suggested that the skills required to build effective human relation­ships have, to date, remained largely in the realm of social workers and other helping professionals, and that dissemination of these skills to parents is essential to the enhancement of healthy childhood development. Implicit here is this study's focus on the need for preventive adjuncts to social work practice. Parent Effectiveness Training (P.E.T.) is a parent education program noteworthy for its emphasis …  Lire la suite

Kakkar, A. K. (Supervisor)  Lire la suite

Dans le but de renverser le déclin de l’agriculture à petite échelle en Amérique Latine, plusieurs mouvements de gauche font la promotion de « l’agroécologie » et de la « souveraineté alimentaire. » L’agroécologie est une approche axée sur la diversité biologique et culturelle comme fondation des systèmes agricoles. Le concept de la souveraineté alimentaire est, quant à lui axé sur le commerce international. Ceux qui proposent la souveraineté alimentaire estiment que les systèmes alimentaires devraient prioriser avant tout les producteurs et les citoyens locaux, et que ceux-ci devraient décider du fonctionnement du système. En Uruguay, la création d’une proposition …  Lire la suite

Environmental education faces special challenges in areas of acute conflict over resource use. This thesis assesses the role of popular environmental education workshops carried out by an external non-governmental organization in a forest-based community in Morelos, Mexico. Factors investigated as possible influences on the impact of workshops included: the pedagogy employed; local perceptions of environmental problems; obstacles to participation; and motivations of participants. The research indicates that the potential role of environmental education for collective action is enhanced when workshops not only increase access to, and sharing of, relevant information, but encourage organizational capacity and inspiration through group work. Furthermore, …  Lire la suite

Numerous attempts have been made to classify the various types of lentic environments. None of the systems of classifying lakes, whether based on dissolved oxygen, thermal conditions, chironomid larvae or numerous other criteria, has been wholly successful, nor are they likely to be until lakes in the more inaccessable regions of the world are investigated. Welch (1941) wrote, "In fact, I am disposed to view most of them as premature and worthy of little attention." Though the volume of limnological knowledge has increased greatly since then, attempts at classification are still largely premature.  Lire la suite

The notion of identity between the ancient and the contemporary, which has its source in Mayan studies, informs the design principles of this work. Specific techniques are listed for the design of musical space and time in Guacamayo, which is "a musical drama that strives for synthesis." There follows an outline of the principle motivic material, approaches to melodic construction and text setting, techniques used to design space (or pitch) and time (or rhythm)--including traditional harmony, symmetrical modes, non-octaviating space and random number generation in the first case, and speech rhythm, folk rhythm, metre and tempo in the second--as well …  Lire la suite

Man’s interest in himself and the way in which he differs from his fellow is a common and frequently observed phenomenon. Psychologists too, concerned as they are in studying the human organism, are interested in individual differences. The amount of information one possesses with respect to any object, person, or event may be thought to be a function of the number of statements of difference one is able to make about it and the things around it. The lack of adequate methods for measuring psychological properties has long been one of the major difficulties confronting research workers in this field. …  Lire la suite