McGill University Thèses et mémoires par auteur commençant par R

Johnston, C. Celeste (Supervisor1)  Read more

Antiarrhythmic drugs, designed to prevent or suppress cardiac arrhythmias, may cause the worsening of an arrhythmia already present in a patient or provoke new and qualitatively different arrhythmias. Cardiotoxic effects of antiarrhythmic drugs may be rate-related or due to intoxication, and may lead to serious and potentially lethal ventricular arrhythmias. The goals of my research were (1) to study the mechanisms by which class IC antiarrhythmic drugs cause ventricular arrhythmias and (2) to explain the mechanisms of action of sodium salts in the reversal of class IC cardiotoxicity. We used flecainide (F) as a prototype of its class to study …  Read more

L’état de l’art sur les modèles de reconnaissance a atteint une performance impressionnante. Ces modèles ont besoin d’une vue complète de la scène pour qu’ils puissent bien fonctionner, ce qui n’est pas toujours disponible. Par exemple, la détection et l’acquisition d’une scène complète est impossible dans les applications telles que l’imagerie aérienne. De plus, dans des applications telles que la reprise après sinistre, les dispositifs d'imagerie doivent être légers, peu coûteux et économes en énergie. C’est pour ces raisons que ces matériels sont souvent construits avec des caméras à petit champ de vision, qui ne capturent qu’une partie de la …  Read more

The thesis focuses on the significance of the cinematic medium for Elizabeth Bowen's novels, from the level of prose and formal representations to broader aspects of narrative and character. The chapters on To the North (1932) and The House in Paris (1935) examine complementary issues of motion and stillness and the consequent impact on subjective experiences of time, space, knowledge, and identity. The final chapter expands the issue of genre revision in The Heat of the Day (1949) to the greater problem of precedent and the reconstruction of identity through storytelling; the novel not only uses formal cinematic techniques by …  Read more

The wide-spread outbreak of Zika virus (ZIKV) infection poses a significant threat to global health. A strong link between Zika virus and clinical birth defects, particularly microcephaly, warrants urgent study of the molecular mechanisms underlying ZIKV pathogenesis. Virus-host interactions determine the outcome of infection, thus we delved into the innate immune response against ZIKV infection and evaluated ZIKV dependency on host metabolism. Type 1 interferons (IFNs) are critical for host resistance against ZIKV. The first part of this study evaluates the effect of interferon and interferon-stimulated genes (ISGs) against ZIKV infection of Asian lineages (PLCal_ZV and PRVABC59). We have shown …  Read more

The dominant role of social networking in the web is turning human relations into conduits of information flow. This means that the way information spreads on the web is determined to a large extent by human decisions. Consequently, information security, confidentiality and integrity of shared data, relies on the quality of the collective decisions made by the users. Recently, many access control schemes have been proposed to control unauthorized propagation and modification of information in online systems; however, there is still a need for mechanisms to evaluate the risk of information leakage and unauthorized modifications within online systems. First, the …  Read more

Delays in access to justice is a global crisis. It is a pathology of legal systems all over the world. Delivering timely justice, therefore, is one of the most formidable developmental challenges of the 21st century. To tackle the problem of excessive court delays, North American civil justice systems have undergone radical transformations in the last half century in as much as the justice systems in both Canada and the US have traveled far away from their traditional moorings. The litigant-dominated adversarial models of adjudication have been largely replaced by judge-controlled case-managed litigation processes that privilege judicial economy over substantive …  Read more

The genetic information stored in DNA must be faithfully copied and transmitted to the next generation of cells at every cell cycle. The replication of this genetic information is performed by special multiprotein replication machinery, referred to as “replisome,” which synthesizes both daughter duplexes simultaneously. At times, the accurate replication of the genome can go awry, causing mutations that can lead to a collection of diseases. In eukaryotic cells, detection and response to DNA damage during DNA replication is performed by the DNA damage response (DDR) pathway. DDR uses exposed single-stranded DNA as a signal for DNA damage and proceeds …  Read more

Cette thèse présente des méthodes objectives pour étudier le système de réflexe vestibulo-oculaire (RVO). Le RVO est une réponse involontaire des yeux qui est évoquée par le mouvement de la tête pour stabiliser les images visuelles sur la rétine. Il joue un rôle essentiel pour maintenir une vision sans flou lors de nos activités de la vie quotidienne et son dysfonctionnement cause des problèmes sérieux de l'équilibrioception. De plus, en raison de sa structure relativement simple et ses réponses très complexes, souvent observées dans d'autres systèmes moteur complexes, le RVO fournit une structure excellente pour comprendre le fonctionnement général des …  Read more

Kinematic design and performance evaluation of serial-type robotic manipulators is the main focus of this thesis with due attention being paid to redundant manipulators. The thesis provides a review of the existing contributions made to the subject, identifying those areas that can be advanced in depth or breadth and making theoretical contributions to some of these areas. The design, manufacturing and commissioning of a full-scale representative example of a redundant manipulator designed for kinematic isotropy is also discussed. Although various theoretical methods of analysis and characterization of the kinematic performance have been reported in the past two decades, the kinematic …  Read more

Gleeson, Thomas (Internal/Supervisor)  Read more

Thirty-two isolates of rhizosphere bacteria, selected for their ability to inhibit zoospore germination and/or mycelial growth of Pythium aphanidermatum (Pa) in vitro, were evaluated in a test tube bioassay using cucumber c.v. 'Straight 8'. These isolates were identified as Psedudomonas corrugata (Pc13 or 35) and P. fluorescens (Pf15, 16 or 27). All but one of the five isolates effectively colonised the roots of cucumber plants in short term studies. Isolates 15 and 35 were found to maintain high population densities throughout the time period. Pa-inoculated plants treated with the Pc13 or Pf15 produced fruit yields equal to 92 and 74% …  Read more

With the centralization of power supply in the hands of the public utility companies, the use of purchased powernhas become habitual for the great majority of industrial consumers. Nevertheless, a real investigation into choice of power supply is suggested as being well worth while. It is shown that the day of the internal plant is far from over, and this idea is carried further by giving some general rules relative to cases where such plants may be economic propositions. [...]  Read more

A review of all the foregoing test work indicates that solution should be offered to at least three distinct problems. The first problem can be termed a physical and chemical problem, and refers to the reasons for the firebrick reactions under impingement, carbon deposition and carbon penetration between temperatures 2000 F and 2300 F. The second problem can be termed a problem of design, and simply stated refers to a suggested design for a low cost and low maintenance refractory furnace, for an oil fired steam boiler. The third problem is a mechanical engineering problem and refers to the selection …  Read more

Les tourbières sont des réserves de carbone (C) importants et mondialement significatives. Cependant, une tourbière peut osciller entre une source et une réserve de C en raison des variations annuelles du climat. La majorité de la variation se produit en raison de changements dans la productivité primaire et la dynamique de la respiration autotrophique (AR, respiration par les plantes), et nous comprenons assez bien ces composants. Cependant, les modèles des tourbières et les mesures directes de la respiration ne partitionnent que grossièrement la respiration de l'écosystème en ses composantes autotrophique et hétérotrophique (HR, respiration par les bactéries microbiennes, les mycorhizes, …  Read more

Peatlands, in their pristine state, are important long-term sinks of carbon. The extraction of peat for agricultural purposes or for biofuel leads to a drastic shift in the carbon dynamics. Additionally, the change in environmental conditions after extraction could also allow for invasive species to establish and spread across the peatland. Many studies have shown the benefits and advantages of various restoration management practices, but few studies have explored the carbon exchange from unrestored peatlands. This study analyzed the methane (CH4) and carbon dioxide (CO2) fluxes from a post-extraction, unrestored peatland in Eastern Québec at both the plant community scale, …  Read more

Reader, Simon (Supervisor1)  Read more

A quarter of a century has elapsed since the first steroid hormone was isolated. Since then, there has been a profound and significant advance in our knowledge of the biogenesis of these steroid hormones and their ultimate fate in the living organism. Less progress, however, has been made in understanding the mode of their physiological action. Studies during the last decade have pointed to a more or less common pathway of steroid biogenesis and metabolism.  Read more

The horn fly, Siphonairritans (L.), has been the subject of a considerable amount of study. In general, it seems to be true that the groups of insects that have received the most attention belong to one of three classes: those that are of economic importance, those that are especially adapted to laboratory manipulation, and those that are particularly attractive to collectors. Despite intensive and extensive studies, the economically important horn fly does not land itself very wall to research in the laboratory at the present time.  Read more

The cross sections for the reactions Cu63(p,n)Zn63 and Cu63(p,pn)Cu62 were measured in comparison with the known cross section C12(p,pn)C 11. For the reaction Cu63(p, n)Zn63, the maximum value of the cross section was 528 millibarns at a mean proton energy of 12.3 Mev. Cross section values for the reaction Cu63(p,pn)Cu62 were determined up to proton energies of 22.5 Mev. At this energy the cross section is 775 millibarns and is still rising slowly. The excitation curves are rather smooth. The curves do not have any major peaks like in oxygen and there is no sure evidence for minor peaks.  Read more

Background. Growth-arrest specific 6 (gas6) is a novel vitamin-K dependent protein whose role in venous thromboembolism was recently characterized in murine models. Gas6 is suggested to be a prothrombotic protein capable of mediating thrombus stability. However, the association between gas6 and venous thromboembolism has yet to be elucidated in humans. The present work aims to delineate the existence of such an association in humans and propose a mechanism by which gas6 expression is related to venous thromboembolic disease. Methods. To analyze the association between gas6 and venous thromboembolism, a highly specific ELISA method was used to measure plasma gas6 levels …  Read more

Major depressive disorder (MDD) is a debilitating, heterogeneous disease characterized by depressed mood, diminished interests, impaired cognitive function, and vegetative symptoms. Roughly 300 million people worldwide are currently living with MDD, with the lifetime prevalence of MDD significantly higher in women than in men. The most dramatic consequence of MDD remains suicide, with psychological autopsy studies suggesting that >50% of adults who died by suicide have had a previous diagnosis of depression. In Canada alone, nearly 4000 deaths occur by means of suicide annually: representing a significant and pertinent public health concern. Despite the burden of this disorder and despite …  Read more

Les Han occidentaux étaient une dynastie de la Chine ancienne dont l'histoire a duré deux cents ans. La constitution et le développement de l'empire ont souvent été accompagnés par le déplacement géographique des nobles et par la réorganisation administrative des territoires. Cependant, les outils de visualisation et les outils interactifs manquent pour présenter des changements aussi spectaculaires. La carte Web, qui offre une interface simple tout en fournissant des informations spatiales et temporelles, est largement utilisée pour les services interactifs. Cela nous a conduit, mes collègues et moi, à développer une carte Web fonctionnelle pour visualiser les changements dynamiques des …  Read more

The erosion of copper cathodes having different microstructures ranging from hundreds of nm to tens of mum were studied in both pulsed vacuum arcs and continuous running magnetically rotated atmospheric pressure arcs. Cathodes having different grain sizes were formed by various thermal spray and heat treatment methods namely, high-velocity oxygen fuel (HVOF) method, atmospheric pressure plasma spraying (PS), vacuum plasma spraying (VPS), cold spraying (CS) and annealing techniques. The coatings produced were characterized for their chemical composition, oxide content, microstructure, porosity and thermal conductivity. Arc velocity and erosion measurements were performed on these cathodes. The results show that, the cathodes …  Read more

This thesis addresses the problem of minimum distance localization in environments that may have structural self-similarities. In other words, how can a robot most efficiently collect sensor data to estimate its position and rule out ambiguity (as opposed to merely increasing accuracy). The formalism is that a mobile robot is placed at an unknown location inside a 2 D self-similar environment modeled by a simple polygon P . The robot has a map of P, can sense its environment and hence compute visibility data. However, the self-similarities in the environment mean that the same visibility data may correspond to several …  Read more

The avian reticuloendothelial virus strain T (REV-T) is among the most overtly transforming of all known retroviruses, and has been shown to transform a wide range of lymphocytes. The transforming ability of REV-T is attributed the v-rel oncogene, a member of the Rel/NFkappaB family of transcription factors. Although it is believed that v- rel mediated transformation involves the disregulation of normal NF-kappaB function, the intracellular requirements for transformation are still unknown. We have used the RCAS vectors (R̲eplication C̲ompetent A̲vian Leukosis LTR with S̲plice Acceptor) for infection and dissemination of viral particles in chicken cells, permitting somatic transgenesis of the …  Read more

A study has been made of the internal parasites of 14 seagulls, Larus argentatus, captured at intervals on the Ottawa River near Ste. Anne de Bellevue, Quebec, during September and October, 1948, and June and July, 1949. The birds were brought immediately to the laboratory and a careful examination of each was made for external and internal parasites. Blood smears were also examined for protozoan parasites. None of the birds showed any external parasites or protozoans in the blood but, at the same time, no bird was free from parasites of the digestive system. The nematode parasites were fixed in …  Read more

La perception du mouvement visuel est l’une des fonctions critiques du système visuel. La direction et la vitesse sont des caractéristiques importantes des stimuli visuels de mouvement, et le traitement de ces caractéristiques se produit principalement dans la voie visuelle dorsale du cortex visuel. Le complexe temporel moyen (MT+) a une sélectivité de direction sensible; il joue un rôle clé dans la perception du mouvement visuel. Le cortex visuel primaire (V1) a été largement étudié. Il présente différentes réponses aux stimuli de mouvement visuels par rapport aux réponses de la zone MT +.La majorité des études précédentes ont révélé que …  Read more

Les nanoparticules artificielles (NPAs) sont devenues des composants importants des produits de consommation basés sur les nanotechnologies. L’augmentation de l’utilisation des NPAs ainsi que, par conséquent, leur rejet dans des environnements aquatiques tels que dans les eaux de surface naturelles, engendre le besoin de caractériser leur devenir et leur comportement en milieu naturel pour rigoureusement comprendre les risques qu’elles posent pour l’environnement et la biote. Après être émises dans l’environnement aquatique, les NPAs subissent plusieurs transformations, ce qui influence leur devenir et leur biodisponibilité. L’objectif principal de cette thèse est de caractériser les différents processus de transformation des nanoparticules d’argent …  Read more

mRNA surveillance pathways are host quality control mechanisms that degrade aberrant mRNA to prevent the accumulation of potentially toxic truncated or misfolded proteins. Substrates for mRNA surveillance include transcripts that have pre-termination codons, long 3’ untranslated regions (UTRs), retained introns or upstream open reading frames. The human immunodeficiency virus type 1 (HIV-1) genomic RNA (vRNA) also contains long 3’ UTRs. However, not only is the vRNA able to evade mRNA surveillance, HIV-1 has also been demonstrated to recruit the mRNA decay proteins to promote vRNA stability and ensure viral gene expression. UPF1 is an integral protein of the nonsense-mediated mRNA …  Read more

Targeted therapy is designed to block specific oncogenic products involved in disordered signaling, with the purpose of inducing selective therapy. However the activation of compensatory and alternate signaling pathways to bypass the inhibitory effects of targeted therapies has led to both intrinsic and acquired resistance. Here, in order to abrogate these adverse signaling nodes, we investigated two major approaches: (a) the design of single agents termed "combi-molecules" targeted to key players of multiple signaling pathways and (b) the determination of Achilles' heels in this complex network of signaling pathways to be targeted for effective therapy. This thesis focuses on the …  Read more

This thesis describes numerical methods to solve the models of differential-algebraic systems via simulation software. Preference of software with the type of DAE has been discussed. DAE real-time model solutions have been compared on simulation software. Categorization of DAE along with constraints have been mentioned. Complex DAE with IVP and BVP has been considered for the problem-solution. The thesis has been extended discussing the general methods of filtering of DAE and a filtering approach has been discussed  Read more

La voie de signalisation de la kinase en 3' phosphatidylinositol (PI3K)/Akt est activée dans plusieurs cancers humains. Des mutations de l'isoforme p110alpha de la kinase PI3K ainsi que la perte de régulateurs négatifs tel que le suppresseur de tumeur "phosphatase and tensin homologue on chromosome 10" PTEN sont à l'origine de l'augmentation de la signalisation de la voie de PI3K. L'activation des récepteurs tyrosines kinases tels HER2/ErbB2, qui sont surexprimés dans 30% des cancers du sein, peuvent aussi induire cette voie proto-oncogénique. En fait, l'activation de la voie PI3K dans les cancers du sein a été associée à une résistance …  Read more

Prichard, Roger K. (Supervisor1)  Read more

Les modèles de systèmes multicorps représentent des corps en interaction et sont essentiels pour simuler le mouvement de systèmes divers. La simulation numérique de ces systèmes est devenue fondamentale dans les industries automobile, aérospatiale et robotique pour prédire le comportement et optimiser les conceptions tout en réduisant les coûts de développement, d'essai et de validation. Grâce aux avancées des capacités informatiques, les analystes abordent maintenant des problèmes plus complexes impliquant des phénomènes tels que le contact et le frottement.Cette thèse se concentre sur la simulation et la co-simulation de systèmes multicorps non-réguliers soumis à des contacts unilatéraux et au frottement …  Read more

Adenosine triphosphate (ATP), the source of metabolic energy for a majority of chemical reactions in the cell, is now considered as an ancient messenger molecule used in intercellular communications. The ionotropic effects of ATP are mediated by P2X receptors which constitute a novel family of ligand-gated ion channels (LGICs). The seven vertebrate subunits, which form homomeric as well as heteromeric channel complexes, show little structural resemblance to other families of LGICs such as the Cys-loop family exemplified by the nicotinic acetylcholine receptors. P2X receptors have been shown to play important physiological roles in processes such as transmission of pain, vasoconstriction, …  Read more

Wall, A. E. (Supervisor)  Read more

Definitions and concepts of learning in the workplace have evolved considerably in the last two decades in response to significant changes impacting most workplace environments throughout the industrialized world. Comprehensive definitions of learning at work go beyond an emphasis on improving performance to consider the workplace as a social environment which can be structured to enhance or thwart adult learning and development. A wider and more socially relevant range of approaches to workplace learning are emerging. By focusing on learning as a process rather than a product, this study attempts to gain a deeper understanding of the daily informal learning …  Read more

Taylor, Charles (Supervisor)  Read more

The process of remastering old recordings comprises two basic stages: the transfer of the material from the source to a modern format, and the subsequent restoration of the transferred material through various forms of signal processing. The transfer stage in particular requires an understanding of issues which are becoming increasingly less familiar to engineers as the science of recording progresses further into the digital era. To a lesser extent, the restoration stage involves the use of certain techniques and forms of processing which are specific to this application. This thesis is intended as a reference for those recording engineers who …  Read more

This thesis examines the role of broadcasting in Canada with regard to developing and maintaining a national identity in the face of United States influence via the media. The subject is examined within the theoretical framework provided by the science of cybernetics and the Laws of Thermodynamics. A historical overview of Canadian broadcasting policy and institutions is provided. The work of the various royal commissions and other investigatory bodies is analyzed. The most important contemporary institutions, the CRTC, the CBC and the federal Department of Communications, are situated within the context. The effects of the most recent technologies, cable television, …  Read more

As far back as Euclid's ruler and compass constructions, computation and geometry have been domains for the exploration and development of fundamental mathematical concepts and ideas. The invention of computers has spurred new research in computation, and now with a variety of applications couched in the fundamentals of Euclidean geometry, the study of geometric algorithms has again become a popular mathematical pursuit. In this thesis, the computational aspects of a fundamental problem in Euclidean geometry is examined. Given a set of line segments in the Euclidean plane, one is asked to connect all the segments to form a simple closed …  Read more