McGill University Thèses et mémoires par auteur commençant par O

Ce projet intègre des données génomiques, anthropologiques, et écologiques afin d'enquêter sur la manière dont des pressions diverses peuvent façonner l'adaptation génétique humaine au paludisme au sein des populations éthiopiennes et soudanaises d'Afrique de l'Est. En utilisant de nouvelles séquences de génome entier fournies par le projet CAAPA2 , cette étude offre un premier aperçu des réponses génomiques variées au paludisme endémique au sein de neuf populations. S'appuyant sur les efforts antérieurs du Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA), l'ensemble de données CAAPA2 inclut des individus d'Afrique de l'Est afin de saisir des variations génétiques de …  Read more

Kunz, Frank (Supervisor)  Read more

Let Q be a convex polygon in $E sp2$ and x be a point in $E sp2$ not contained in Q. The aperture angle $ theta(x)$ with respect to Q is defined as the angle subtended by the cone that: (1) contains Q, (2) has apex at x, and (3) has its two rays emanating from x tangent to Q. The Aperture-Angle Problem in the Euclidean Plane $E sp2$ is defined as follows: Given two disjoint convex sets P and Q in $E sp2$, find a point $X in P$ such that $ theta(X)$ is the maximum value of the …  Read more

Flax (Linum usitatissimum L.) peroxidase cDNAs (FLXPER1--4) were isolated from a lambdagt10 shoot library using probes encoding the amino termini of class III plant peroxidases. These probes were obtained by PCR amplification of the library with lambda primers flanking the EcoRI cloning site, and a mixed oligonucleotide corresponding to the catalytic domain (HFHDCFV) found in secretory plant peroxidases. The transcriptional expressions of FLXPER1 and FLXPER2 appear to be specific to stem based on northern blot analyses. FLXPER1 and FLXPER2 encode acidic peroxidases of calculated isoelectric points (pIc) 4.6 and 4.7, respectively. However, FLXPER1 differs from FLXPER2 in amino acid sequence …  Read more

Brazil instituted a crawling peg (mini-devaluation) exchange rate system in 1968 as a long-term device to put into operation an "export oriented growth-cum-debt" model of economic development. The crawling peg was expected to serve diverse objectives by decreasing the variability in the exchange rate. In this study we have analyzed the degree to which this strategy succeeded in realizing the desired goals during the period from 1968 to 1980. Our findings verified that the implementation of the crawl was an important tool that protected and enhanced Brazil's competitive position in world markets. The demand for Brazilian products became more responsive …  Read more

State-space models are used to study non-stationary data. However, in the presence on non-Gaussian error terms the standard state-space model does not apply. We investigate the properties of univariate and multivariate state-space models under conditional heteroskedasticity and multiple structural breaks. This allows us to extend the standard state-space models to heavy tailed data and allow for dynamic parameters. We develop a Gibbs sampling algorithm to carry out Bayesian inference on the parameters and the latent state vector. Finally, we carry out an empirical study on ICU data. We find that our models are better able to capture the variation in …  Read more

Two groups of perennial springs are observed in the Canadian High Arctic at Expedition Fiord on Axel Heiberg Island. Saline discharge (~1.3-2.5 molal) produces a variety of calcite (travertine) and gypsum-rich precipitates. Field observations, laboratory experiments, and geochemical modeling of the waters reveal that calcite precipitation is controlled primarily by CO2 degassing, but alternating light (sparite calcite crystals) and dark (amorphous micritic calcite spheres coated by organic material and trace metals) laminae are present. Evaluation of the geochemical environment in conjunction with field observations suggest that micrite layer formation may be influenced by microbial activity, although their presence has yet …  Read more

A common wastewater treatment process practiced by zinc production facilities is the single-stage mixing of acidic wastewaters with slaked lime, inducing the reactive precipitation of fine (~1 mum) gypsum (CaSO4.2H 2O) and other solids with a solids density less than 10%. These solids report to a tailings pond for containment. Tailings pond life would be increased if the solids density of the precipitated solids was improved. Previous work at McGill University suggested that a staged neutralization process with solids recycle and seeded with gypsum would produce large-sized gypsum crystals with a high solids density. A continuous lab-scale process run with …  Read more

La sénescence cellulaire est reconnue pour stimuler la carcinogenèse et le développement de plusieurs maladies liées à l'âge, mais est également nécessaire pour divers processus physiologiques. Le phénotype sécrétoire associé à la sénescence (SASP) est un terme utilisé pour désigner les sécrétions de ces cellules. Ces sécrétions inflammatoires associées à l’âge jouent un rôle dans la progression des maladies liées à l’âge. Dans le chapitre 2, je démontre une nouvelle interaction entre la sénescence et la réponse au stress qui influence à la fois la progression de la sénescence et le comportement des cellules sénescentes. L’assemblage des granules de stress …  Read more

Using the rat as a model we tested the hypothesis that pregnancy might lead to an attenuation of the diuretic/natriuretic effects of atrial natriuretic factor (ANF) to allow physiologically required fluid expansion. Our studies revealed that this was indeed the case. Effects of ANF on fluid and sodium excretion as well as on glomerular filtration rate were significantly reduced during pregnancy This decrease in the renal effects of ANF during pregnancy was not associated with any changes in the pharmacokinetics or renal metabolism of ANF. However, binding studies demonstrated a significant decrease in guanylyl cyclase (GC)-linked ANF receptors and a …  Read more

Theodore, David (Supervisor1)  Read more

In this thesis a method based on Green's second identity is developed for computing several orders of derivatives from finite element solutions with $C sp circ$ continuity. The integration by parts implicit in Green's theorem permits numerical integration to replace numerical differentiation. This procedure is initially developed for harmonic functions, then extended to Poisson and Helmholtz equations for a circular region, as well as to harmonic potentials in axi-symmetric coordinates. For the 2-D Laplace operator three other base regions have been introduced: rectangle, sector of circle and sector of ring. The method is numerically stable, position independent and very accurate. …  Read more

The gastrointestinal tract imposes a chemical and physical barrier to the oral delivery of bio-therapeutics such as insulin. As a consequence, bio-therapeutics need to be injected subcutaneously. Swallowable capsules, capable of injecting a drug directly into the intestine wall, would enable painless and convenient oral delivery of these drugs. This thesis focuses on the development of needle deployment and retraction mechanisms to be implemented into Drug Injecting Swallowable Capsules (DISCs). The design space for the mechanisms is defined, and eleven novel designs, inspired by biological systems and macro-scale mechanisms, are proposed. One particular design, inspired by the defense mechanism of …  Read more

La cartographie idéologique sur les réseaux sociaux est généralement conçue comme une tâche de classification supervisée reposant sur l’existence de systèmes partisans stables et sur un vaste ensemble de données annotées. Ces hypothèses s’effondrent toutefois dans des contextes où l’institutionnalisation politique est faible, comme c’est le cas en Iran. Les grands modèles de langage (LLM) savent identifier les convictions politiques d’utilisateurs anglophones à partir de leurs publications, mais il reste difficile d’évaluer leurs performances dans d’autres langues et d’autres systèmes. Dans cette étude, nous reformulons la détection d’idéologies comme un problème de cartographie non supervisée et présentons un système de …  Read more

Bird, J. (Supervisor)  Read more

The cardiorespiratory effects of PEEP were critically re-assessed in 16 hypoxemic surgical patients. Total venous admixture was calculated in 11 of 16 patients while they breathed room air and true shunt was determined from data obtained during 100% oxygen breathing. The "non-shunt" fraction was calculated by subtracting the true shunt from the total venous admixture. Measurements were made at two levels of end expiratory pressures (0 and 10cm H20). The contribution of airway closure and distal alveolar gas trapping to pulmonary shunting was assessed in 11 of 16 patients by the nitrogen wash-out method and the hemodynamic consequences of 10cm …  Read more

Masai Mara, a large nature reserve in south-western Kenya, was created in the midst of semi-arid agropastoralist rangelands to protect wildlife. Wildlife and indigenous people co-existed for many years, usually with limited conflict; but in recent years, the conflict has intensified, mainly due to increasing human population, changing land use patterns, and altered perceptions of wildlife. This study examines the causes and nature of wildlife-human conflict in the Masai rangelands of Kenya, and considers how wildlife conservation and human development needs can best be integrated. Findings indicate that common conflicts are livestock depredation and crop damage, human deaths or injuries, …  Read more

Brandenberger, Robert (Internal/Supervisor)  Read more

Holder, Gilbert (Supervisor2)  Read more

Les ensembles de données modernes sont de plus en plus de haute dimension et multi-voies, naturellement représentés sous forme de tenseurs avec plusieurs variables indexées. De telles données apparaissent dans de nombreuses applications, notamment la prévision de séries temporelles multivariées, l'imagerie médicale 3D et la modélisation climatique. Bien que les Transformers aient démontré des performances exceptionnelles dans la modélisation de séquences et les tâches d'apprentissage de haute dimension, leur application directe aux données multi-voies reste prohibitivement coûteuse en raison de la complexité quadratique de l'attention par produit scalaire. De plus, les mécanismes d'attention automatique standard ne préservent pas intrinsèquement la …  Read more

La nourriture ou l'apport diététique est très essentiel à la vie humaine. Cependant, les maladies liées à l'alimentation telles que l'obésité, les maladies cardiaques chroniques et le diabète sont parmi les principales causes de décès dans le monde aujourd'hui. Au cours de la dernière décennie, la surveillance de l'apport alimentaire est devenue de plus en plus une étape importante vers un mode de vie sain.Les méthodes conventionnelles de collecte et d'évaluation des données par papier et stylo sur l'apport alimentaire souvent utilisées pour surveiller l'apport alimentaire, comprennent le rappel alimentaire de 24 heures (24HDR), le dossier alimentaire (FR) et les …  Read more

The visual environment contains a vast amount of information which is encoded efficiently by the visual system through the use of segregated dorsal and ventral streams. This study investigates the interaction between selected areas in the parallel dorsal and ventral pathways with the use of online repetitive TMS. The effects of TMS on two psychophysical tasks were investigated: a global motion task directed at the specialties of dorsal area hMT+ and a color contrast task directed at the specialties of ventral areas VO and V4. In each case, TMS was applied to the selected areas and a control area (vertex). …  Read more

Cotton (Gossypium spp. L.) is man's most important natural fibre crop. The world cotton production estimate for 1964-65 is 51.6 million bales from an estimated area of 81.6 million acres (Anonymous, 1965). The crop is grown in the warm areas of the tropical and sub-tropical regions of the world. [...]  Read more

In Tanzania, at least 12 new urban mega-developments branded as ‘cities’ have been planned since 2008, largely by government ministries and enduring socialist-era parastatals. These projects join a rising tide of new master-planned cities spreading throughout the Global South, as governments seek not only to respond to the needs of growing urban populations, but also to claim a place on the global stage. This thesis explores the emergence and evolution of new city building in Tanzania and positions it within broader global urban trends. Paying particular attention to Tanzania’s transition from socialism to market capitalism, I argue that institutional legacies …  Read more

Microtubule-actin interactions underlie a diverse number of biological processes including cell motility, neuronal outgrowth, cellular wound healing, cell division and cortical flow. CRMPs (Collapsin Response Mediator Proteins) are a family of cytosolic phosphoproteins that play roles in regulating both actin and microtubule dynamics. The roles of the CRMP family of proteins in regulating these cellular processes have only been partially described. Our lab has been particularly interested in the function of the CRMP4 isoform because of its unique ability to complex with RhoA, a master regulator of the actin cytoskeleton. In this thesis we explore the function of CRMP4 in …  Read more

Morin, Suzanne (Supervisor1)  Read more

Progranulin (PC-cell derived growth factor, acrogranin, granulin-epithelin precursor) is a secreted glycoprotein with growth promoting activities for diverse cell types and is the precursor for the 6 kDa granulin peptides. These peptides were initially identified in inflammatory cells i.e. neutrophils; and this led to the hypothesis that the grn(granulin ) gene and its products may be regulated during, and function in, wound repair. In response to tissue injury, the grn gene is induced in endothelial cells and fibroblasts. Expression was observed in epithelial and inflammatory cells with higher expression in the inflammatory cells in the early phases of wound healing. …  Read more

Four separate polynucleotide kinase activities were observed following Polymin P precipitation of crude extract of calf thymus tissue (Prinos et al., 1995). A single activity designated Polymin P-Precipitable Polynucleotide Kinase (PP-PNK) was detected in the pellet fraction. The other three separable activities, designated SNQl, SNQII and SNQIII, were found in the supernatant fraction after chromatography on a Q-Sepharose column. The PP-PNK activity was purified 4,200 fold after 6 purification steps. The PP-PNK preparation preferentially used ATP as a gamma-phosphoryl donor compared with GTP. Chromatography on a Sephadex G-150 column demonstrated that it had a molecular weight of 130 kDa. Immunoblot …  Read more

The effects of altered thyroid states have been investigated in a DMBA induced mammary tumor system in Sprague-Dawley rats. Results revealed that both tumor incidence and gross tumor yields were less in the thyroidectomized and 1-thyroxine treated groups, as compared to the intact controls. Furthermore, increasing the dose of 1-thyroxine in the thyroxine treated group, resulted in a reversaI of the progressive tumor growth potential with regression and complete extinction of a significant number of the established mammary tumors in this group. Histologically, tumors of the thyroidectomized and control groups were identical, while a characteristic morphologic variant was seen only …  Read more

Nearly three hundred years ago, the protozoa-both free-living and parasitic were first seen by the father of protozoology, Antony van Leeuwenhoek. Ever sinee various biological studies and experiments have been carried out on this fascinating "little animal." [...]  Read more

A procedure for isolating mitochondrial particles with relatively high respiratory activity and good respiratory control in quantity from etiolated Mung bean (Phaseolus aureus) seedlings is described. The mitochondrial preparation can be preserved in the frozen state for two to four weeks by freezing at -15°C in the presence of dimethyl sulfoxide (DMSO) and bovine serum albumin (BSA). Damage to mitochondria by freezing at 77°K may be reduced by DMSO addition. The supplements Ficoll, dextran, MgCl2, KCl, dithiothreitol (DTT) and DMSO had no importance as stabllizers of the activity of mitochondria in liquid suspension (0°c), whereas Tricine (N-Tris (hydroxymethyl) methylglycine) and …  Read more

Paradis, M. (Supervisor)  Read more

La voie de réparation des bases (VRB) est la principale voie responsable de la réparation des lésions basiques — les résidus d’uraciles, les bases désaminées, alkylées et oxydées — ainsi que des sites abasiques et des bris simple brin (BSBs). Plusieurs facteurs de transcription agissent comme cofacteurs auxiliaires de la VRB, stimulant les activités enzymatiques des ADN glycosylases qui reconnaissent les bases oxydées de l'ADN. Les protéines du domaine CUT (CUX1, CUX2 et SATB1) renforcent les activités glycosylase et AP-lyase de la 8-oxoguanine ADN glycosylase 1 (OGG1), tandis que les protéines à doigts de zinc BCL11A et BCL11B stimulent la …  Read more

Centrosomes are major microtubule organizing centres that set up an internal microtubule (MT) network contributing to cell shape and to the formation of the mitotic spindle during cell division. Rearrangement of this MT array can be dictated by the centrosome and occurs during cell adhesion, polarization and migration. However, little is known about what regulates centrosome assembly and maintenance. beta1-integrins are common cell surface receptors and we show that beta1-integrin signalling is necessary for modulation of centrosome dynamics. In an attempt to identify the downstream components of beta1-integrin signalling involved, we also discovered that the activation of focal adhesion kinase …  Read more

Les maladies infectieuses causées par des bactéries pathogènes et résistantes aux antibiotiques sont un problème croissant dans le monde entier. La détection infaillible à haut débit de bactéries pathogènes est une demande urgente pour la société d'aujourd'hui. Les méthodes diagnostics utilisés actuellement pour détecter les bactéries, tels que les géloses et PCR en temps réel, sont longues, intensives, et souvent nécessitent des équipements de qualité de laboratoire. Pour répondre à la nécessité grave pour un test diagnostic répandu, rapide, et à faible coût, nous démontrons un nouveau test pour la détection abordable, facile, et rapide (< 2 h) de bactéries …  Read more

The creation of a new project within an existing built environment requires more than just the careful preservation of the historical setting or domination of the ongoing architecture. Rather, the new work must sustain the vital reality of place and its external form in conjunction with the unity of all ages: past, present and future. It is through this quest for architectural continuity that the peculiarly human quality of different places may be understood and reinterpreted. In this way, architecture can give shape to and preserve the meaningful lived-reality of place. Only through an active encounter with "place", may we …  Read more

La stratification des fluides se produit lorsque des fluides de compositions ou de caractéristiques thermodynamiques différentes sont présents sous forme de volumes distincts dans un système séparés par une interface stable ou quasi-stable. La stratification des fluides et la déstabilisation sont des phénomènes courants dans les systèmes magmatiques. Pour résoudre ce problème, nous avons mené une série d'expériences analogues et de simulations numériques. Nous présentons trois séries d'expériences modélisant le comportement d'instabilité qui se développe entre deux magmas stratifiés de manière stable et le degré de mélange qui s'ensuit. La première série d'expériences analogues examine l'instabilité qui se développe à …  Read more

This thesis presents a new method of analyzing Gaussian distributions as found in photopeaks in scintillation spectrometry. The technique provides an improvement in accuracy and convenience for obtaining line widths and positions over previously available methods. Some aspects of energy resolution of scintillation counters are investigated, and a semi-graphical method is described for resolving lines that overlap too much to be easily analyzed by other techniques.  Read more

Equipment has been constructed to increase the rate of accumulating energy spectrum data during the short beam burst of the McGill synchrocyclotron. The system operates by storing up to seven 100-nanosecond pulses per burst as lines of charge on the face of a conventional cathode-ray tube with a resolving time of 300 nanoseconds. An analogue output is provided for existing multichannel pulse height analyzers during the time between bursts. An analysis is given of the counting losses associated with the shape of the beam burst. [...]  Read more

BB rats spontaneously develop an insulin-dependent diabetes mellitus strikingly similar to the syndrome observed in man. The disorder requires the presence of multiple susceptibility genes and unknown environmental factors. At least one susceptibility gene resides within the u haplotype of the rat major histocompatibility complex (RT1). Restriction fragment length polymorphism analysis of genomic DNA from rats generated from a series of intercrosses between diabetic BB rats and Buffalo rats (RT1$ sp{ rm b})$ demonstrated that animals heterozygous throughout the RT1 developed IDDM. A single dose of the high risk allele was thus shown to be sufficient for the development of …  Read more

This thesis is a study of the difficulties arising from the application of section 1 of the English Bills of Lading Act, 1855. This study is conducted in the context of the evolution of the law, relevant judgments, international conventions as well as academic views. By the custom of merchants a bill of lading is transferable by indorsement the property in the goods may thereby pass to the indorsee; nevertheless all rights in respect of the contract of carriage evidence by the bill of lading continue in the original shipper or owner. In order to solve this problem, the Bills …  Read more

Les enfants qui sont nés prématuré souvent ont besoin de soutenir avec ventilateur mécanique invasif dans les premières semaines de la vie. La durée de ventilation doit être minimiser enfin de prévenir le développement de maladie pulmonaire chronique. Cependant, sevrer le bébé (extubation) trop tôt est également dangereux et pourrait entraîner la mort. Actuellement, les médecins n'ont pas les protocoles objectifs à faire cette décision si difficile. Celui a conduit à haut taux de échecs d'extubation, d'ici 70% dans quelques cas. Cette étude a profité des methodes de apprentissage automatique pour explorer prédicteurs de l'état de préparation à exubation chez …  Read more

Cette thèse aborde les défis techniques liés à l’application de l’apprentissage automatique pour comprendre et interpréter les signaux audio médicaux. Les sons de nos poumons, de notre cœur et de notre voix transmettent des informations essentielles sur notre santé. Pourtant, en médecine contemporaine, ces sons sont principalement analysés par des experts, à l’aide d’appareils comme les stéthoscopes. L’analyse automatisée offre la possibilité de standardiser le traitement des sons médicaux, de permettre le dépistage dans les régions à faibles ressources où les médecins sont rares et de détecter des motifs subtils qui pourraient échapper à la perception humaine, facilitant ainsi un …  Read more