McGill University Thèses et mémoires par auteur commençant par N

This thesis is based on research carried out as part of a major cross sectional study of the epidemiology of childhood asthma in Kenya focusing on the impact of urbanisation. Study outcomes were lung function level and airway responsiveness to exercise and to methacholine. The hypotheses examined were that asthma occurred more frequently in urban than rural areas, and that the differences were due to the differences in the distribution of host and environmental risk factors. The analysis was based on the results of 485 rural and 586 grade 4 school children, aged 8-12 years. Host factors to which urban …  Read more

Metastatic breast cancer remains the biggest challenge to the successful treatment of this disease. Overexpression of the HER2/ErbB2 receptor tyrosine kinase is associated with metastatic disease and correlates with reduced patient survival. TGFβ can activate signaling pathways that cooperate with ErbB2 to enhance the migratory, invasive and metastatic behavior of breast cancer cells. Furthermore, TGFβ is a strong inducer of an epithelial-to-mesenchymal transition (EMT), and breast cancers with EMT features are associated with poor clinical outcomes.Using a panel of ErbB2-overexpressing breast cancer cells that undergo TGFβ-induced EMT, I identified Lipoma Preferred Partner (LPP) as an indispensable mediator of breast cancer …  Read more

The dissertation argues that libertine first-person lyrics of seventeenth-century England reveal a coherent literary strategy in formal, thematic, and ideological terms. My focus is the libertine poems of Donne, Suckling, Carew, Lovelace, and Rochester. I situate the lyrics in a period of historical change, an age of epistemological and ontological questioning. Libertine lyrics concern inconstancy on various levels, from the sexual to the ontological, and they explore the problems of freedom, human nature, identity, and individualism. I argue that the libertine's inconstant selfhood is a creative "solution" to a historical dilemma. This conception of inconstant selfhood is also a response …  Read more

Thin films of PbBiSrCaCuO superconductor have been produced by means of single target magnetron rf sputtering followed by a heat treatment. The effects of deposition and post-annealing parameters on film properties were investigated. It was found that film thickness decreases near the discharge center, possibly due to the preferential ion bombardment of the film during deposition. Superconducting films with the high Tc 2223 phase could be obtained after a heat treatment as short as 60 min. A structural transition from the semiconducting phase to the low T c 2212 phase took place in the film during the preannealing in O …  Read more

En déployant de petites cellules (dénommées les femtocells) au sein de la même zone de service que les cellules de tailles régulières (dénommées cellules macro), une efficacité spectrale zone beaucoup plus élevé, une meilleure couverture à l'intérieur, et d'importantes données mobiles de déchargement entre les deux cellules peuvent être réalisé tout en gardant faible coût. Vu que les femtocells réutilisent le spectre de fréquence déjà consacré à la cellule macro, auxquelles ils sont assignés, d'une manière non-coordonnée, de nouvelles limites de cellules sont créées et l'interférence devient beaucoup plus imprévisible que dans les réseaux traditionnels. Dans ce contexte réseau hétérogène, …  Read more

This thesis presents the design and implementations of some visual special effects for a virtual reality training system. The VR training system is being developed for use by the power station maintenance and electrical contractor personnel. In order for the trainee to perform correct and safe ground welding procedures under a variety of situations, visual cues representing those situations are necessary. Since there is a tradeoff between the realism and the interactivity in any real-time VR system, the challenge in implementing special effects in such a system is to develop a relatively realistic model that is also computationally efficient. The …  Read more

Les polymères conjugués (PC) ont une fluorescence amplifiée mais facilement supprimée, ce qui les rend utile pour la détection d'une vaste gamme de molécules. Ici on a crée des nouvelles structures luminescents basées sur les interactions entre la PC (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene (MPS-PPV) et des liposomes ou des particules de silice de diamètre environ 100 nm. L'interaction entre la PC et les lipides est vérifié avec la spectroscopie. Ajoutant une autre fluorophore aux lipides, on voit fluorescence resonance energy transfer (FRET) de la PC au fluorophore. L'encapsulation de la PC est vérifié par la réponse de la fluorescence des complexes PC / …  Read more

Induction of extracellular lipases from Pseudomonas fragi CRDA 037 and Geotrichum candidum was used to increase lipase production in a shorter period of time. Induction was performed using edibles oils such as olive oil, canola oil, fish oil and butter fat. Fermentation trials of the microorganisms in the selected media were done in order to optimize the production of lipases. Optimal lipase activity was obtained in the presence of butter fat (1%, v/v) for P. fragi which was cultivated at 15°C during 48 h, and fish oil (0.75%, v/v) for G. candidum incubated at 27°C for 56 h. The induced …  Read more

Linking education, science and technology with national development is a subject of increasing concern in many developing countries. In this dissertation, we have studied empirically the contribution, or lack of it, which public investment in education, science and technology has made to the attainment of development objectives in Cameroon since 1960. Using a small computable macroeconometric model of Cameroon incorporating some major relevant quantitative aspects of the knowledge sector, we have investigated the effects on that sector and on the overall economic system of increased education- and research-service resources. We have also analyzed some of the major qualitative factors that …  Read more

The number of mobile device subscribers worldwide grows at an exponential rate every year. This generates a congestion in the radio frequency (RF) bandwidth that may create unreliable communication. Therefore alternative means of communications should be investigated to sustain the RF channel. Visible light communication (VLC) which is a subset of optical wireless communication (OWC) could be a potential complement to RF channels. VLC is defined as a short-range optical wireless communication through light-emitting diode (LED) source. This technology could decongest the RF channel in the sense that VLC could cover indoor wireless communication where short distance transmissions are widely …  Read more

Le tabac est l'un des quatre principaux facteurs de risque de maladies non transmissibles (MNT) et la cause de décès et de maladie la plus évitable dans le monde. En réponse à l'épidémie de tabagisme, la Convention-cadre de l'Organisation mondiale de la santé (OMS) pour la lutte antitabac (CCLAT) exige que les parties adoptent une approche multisectorielle et pangouvernementale pour réduire à la fois l'offre et la demande de tabac. Dans le cas de la mise en œuvre de la lutte antitabac dans les pays producteurs de tabac, comme le Mozambique, les secteurs de la santé se concentrent souvent sur …  Read more

The hepatitis C virus (HCV) non-structural 5A (NS5A) protein is a multi-functional, RNA binding protein and an essential component of the HCV replication complex. It is subdivided into 3 domains; a highly structured domain I (DI), while DII and DIII are intrinsically unstructured yet mediate crucial interactions with several viral and cellular host factors. NS5A-DII protein mediates the interaction with Cyclophilin A (CypA), a cellular cis/trans isomerase essential for viral replication. Cyclosporine A (CsA), an inhibitor of CypA, inhibits this interaction and suppresses HCV replication. Mutations that confer resistance to CsA and derivatives have been identified within NS5A-DII (D320E and …  Read more

Une augmentation alarmante du nombre de satellites et de débris orbitaux autour de la Terre a engendré un besoin grandissant de développer des technologies pour l'entretien des satellites en orbite et afin de disposer des débris existants. Cette thèse porte sur une solution constituée d'un satellite de service muni d'un manipulateur robotisé qui lui permet de s'arrimer au satellite ciblé et en maintenir le contrôle afin de compléter les opérations requises. Plus spécifiquement, cette étude porte sur la phase après la saisie d'un satellite culbutant avec un moment angulaire inconnu et ayant des propriétés inertielles inconnues. Un aspect critique à …  Read more

BackgroundFood allergy management relies mainly on avoidance and appropriate treatment of severe reactions (anaphylaxis) with epinephrine. Accidental exposure remains a concern, and may occur in school, where allergic children must rely on school personnel to recognize and treat their reaction with an epinephrine auto-injector such as the EpiPen®. Methods used to solicit participation in a study to assess the ability of school personnel to use the EpiPen® may introduce selection bias. Objectives 1) To determine the annual incidence, characterize the severity and management, and identify predictors of accidental exposure among a cohort of children with peanut allergy. 2) To determine …  Read more

Since the introduction of Đổi Mới economic reforms in the late 1980s, Hanoi’s urban mobility landscape has undergone substantial transformations, with motorbikes being the dominant mode of transport. For many Vietnamese individuals and households, motorbikes remain a vital asset for everyday life and livelihoods. Such is the case for the informal motorbike taxi drivers, known locally as xe ôm. Despite lacking formal recognition, xe ôm drivers have provided an essential transport service to urban residents in Hanoi for nearly four decades, filling critical mobility gaps left by the city’s inadequate public transit network. In recent years, however, those who pursue …  Read more

Les principales fonctions de l'appareil urogénital sont le maintien de l'homéostasie ainsi que la reproduction, ce qui est essentiel à la fois à l'organisme et à la survie de l'espèce. Par sa complexité, le développement de l'appareil urogénital est vulnérable à plusieurs anomalies, certaines étant associées à une prédisposition plus élevée au cancer. Résultant d'une série d'affections hétérogènes, le cancer demeure un défit sérieux dû à notre connaissance limitée des processus cellulaires normaux. Les travaux décrits dans la présente thèse concernent l'étude du lien entre le développement d'un tissue et son mécanisme de transformation oncogénique. Plus précisément, nous nous sommes …  Read more

Self-cycling fermentation (SCF) control was applied to a semi-continuous, aerobic, fixed-film reactor for the treatment of simulated and real brewery wastewater. The simulated wastewater was treated at 25°C. After approximately 3 hrs, 86% to 96% of the soluble BOD (SBOD) was removed, producing an effluent with a SBOD between 169 mg/L and 412 mg/L. The treatment of real brewery wastewater was undertaken at 25°C and 35°C, and was operated under ammonia-nitrogen deficient condition. 83% to 92% of the total BOD (TBOD) was removed after 3 hrs at 25°C, and after 1.5 to 2 hrs at 35°C. The treated effluent produced …  Read more

Rhodium, platinum, copper, palladium, and rhodium-ceria catalysts were investigated in the catalytic partial oxidation of methyl acetate, the simplest methyl ester, to better understand the conversion of biodiesel to hydrogen. Only rhodium and rhodium-ceria catalysts allowed for an autothermal reactor operation. Both catalysts were active in producing hydrogen, carbon monoxide, water, and carbon dioxide, although the rhodium-ceria catalyst showed the greater methyl acetate conversion and the greater hydrogen and carbon monoxide selectivities. A low C/O feed ratio favored the methyl acetate conversion, the hydrogen selectivity, and the carbon monoxide selectivity. Furthermore, a high gas hourly space velocity also improved the …  Read more

Population-based molecular epidemiologic studies of tuberculosis have been widely performed to assess the burden of ongoing TB transmission within a population. By genotyping M. tuberculosis isolates (M.TB), cases with matching DNA "fingerprints" are inferred to be due to ongoing transmission, and those with non-matching or "unique" fingerprints are inferred to represent re-activation disease. Two population-based molecular epidemiologic studies using three genotyping methods (IS6110 RFLP, spoligotyping and MIRU) are presented here. The first study examines all TB cases among the Inuit community if Nunavik, Quebec (1990-2000). Our analysis identified previously unrecognized inter-village transmission and estimated that at least 65% of TB …  Read more

Differentiation between rejection and infection of lung allografts remains difficult. The effects of these two pathologic entities on the cytolytic activity of bronchoalveolar lavage (BAL) and peripheral blood lymphocytes (PBL) were investigated. Left lung allotransplantation was performed on sixteen mongrel dogs of which twelve were available for complete studies. All animals received cyclosporine A, azathioprine and prednisone for 2 weeks. Four grafts developed left lower lobe Gram negative pneumonia. The eight remaining recipients progressed gradually to severe rejection following acute reduction of immunosuppression. Cytolytic activity of blood and left lung BAL lymphocytes was quantitated by the natural killer (NK) and …  Read more

Les modèles de répartition des espèces (species distribution models; SDMs) sont l’un des outils numériques les plus populaires en écologie et sont régulièrement utilisés de façon prédictive pour la gestion d’invasions biologiques. Cependant, le niveau de prévisibilité des SDMs dans de nouveaux contextes — c’est-à-dire leur transférabilité — demeure largement inconnu, la majorité des études étant limitées à quelques espèces avec des résultats équivoques. Cette thèse se concentre sur l’évaluation de la transférabilité spatiale des SDMs appliqués aux invasions biologiques et les facteurs qui contribuent à leur prévisibilité. J’ai examiné la capacité discriminatoire des SDMs en ajustant deux approches de …  Read more

This work develops a digital-computer simulation of the interaction between an artificially polluted insulator and a high-voltage direct-current (HVDC) or an alternating-current (AC) source configuration. The polluted-insulator model includes conditions for the existance of arcs on contaminated surfaces; arc motion, speed of arc propagation, and arc reignition criteria; and thermodynamic phenomena in an unbridged wet layer. The effect of the source parameters on the leakage current waveform, the dynamic voltage drop and the critical flashover voltage is systematically investigated and supported by experimental results. The simulation results are used to establish the HV test source requirements and provide guidance for …  Read more

Since the fifth generation of cellular networks, machine-type communication has emerged as an important application of wireless networks to serve highly-automated production. However, it is challenging to meet the demands of machine-type communication by wireless networks due to its unique characteristics. Machine-type communication usually involves a large number of devices transmitting short packets sporadically. In addition, many machine-type devices require low-latency communication to support real-time applications.The existence of a large number of machine-type devices in a wireless network will cause the resource scarcity problem. Among many wireless technologies to alleviate this problem, massive multiple-input-multiple-output (mMIMO) has gained interest recently. A …  Read more

The effects of food availability and the presence of the parasite, Plagiorchis elegans, on the probability of Aedes aegypti preimagos to transform from one immature stage to the next over consecutive 24- or 48-hour periods of time were determined. Under conditions of low food availability, 24- and 48-hr transition probabilities of all larval instars, to the next were reduced. Increases in food availability reversed this process, causing significant decreases in same-stage transition probabilities. However, as transition to successive stages increased among first, second, third and fourth instars, there was concomitant significant increase in first and fourth preimago mortality. Addition of …  Read more

Les mécanismes responsables de l'internalisation de la neurotensine (NT) au niveau des terminaisons nerveuses demeurent inconnu. Dans la présente étude, nous avons étudié les mécanismes biochimiques responsables de l'internalisation de la NT au niveau des terminaisons nerveuses. Pour ce faire, nous avons effectué des expériences de liaisons et d'internalisation de la NT en utilisant un ligand radioactive, le [3H]-NT, sur des préparations de synaptosomes neostriataux purifiés. [...]  Read more

Otitis media with effusion (OME) is a chronic inflammatory disease of the middle ear space characterized by the accumulation of fluid. Previous investigations have found the composition of the inflammatory substrate in effusions of allergy-associated otitis media to be is similar to the late-phase allergic response seen elsewhere in the respiratory tract, such as in asthma and in allergic rhinitis. In addition, there is evidence suggesting that diseases of the upper and lower airways may represent different clinical manifestations of a single inflammatory airway syndrome, or the United Airway Concept. The objective of this research is to determine if the …  Read more

The Interferon Regulatory Factors (IRFs) are a family of interferon-inducible proteins which play distinct roles in diverse processes such as pathogen response, cytokine signalling, cell growth regulation and hematopoietic development. The objective of this research was to investigate the mechanisms by which IRF-1 and IRF-2 regulate gene expression and cell growth. Structure-function analyses of the IRF-2 protein demonstrate that transcriptional repression by IRF-2 is contained within the first 125 N-terminal amino acids and correlates directly with IRF-2 DNA binding. Overexpression of functional IRF-2 deletion mutant proteins in NIH3T3 cells results in oncogenic transformation and tumorigenesis, suggesting that IRF-2 oncogenicity correlates …  Read more

Recently, group III-nitride nanowire heterostructures have been extensively investigated. Due to the effective lateral stress relaxation, such nanoscale heterostructures can be epitaxially grown on silicon or other foreign substrates and can exhibit drastically reduced dislocations and polarization fields, compared to their planar counterparts. This dissertation reports on the achievement of a new class of III-nitride nanoscale heterostructures, including InGaN/GaN dot-in-a-wires and nearly defect-free InN nanowires on a silicon platform. We have further developed a new generation of nanowire devices, including ultrahigh-efficiency full-color light emitting diodes (LEDs) and solar cells on a silicon platform.We have identified two major mechanisms, including poor …  Read more

Understanding the spatial and temporal variations of the precipitation process is essential for the planning, design, and management of various water resources systems. Recent years, climate change impacts on precipitation have been considered as one of the most critical issues for water resources management worldwide. Hence, it is essential to establish the linkage between the large- scale climate variables in the atmosphere with the precipitation characteristics at a local site of interest for impact and adaptation studies. The present study is therefore carried out to develop appropriate methods for improving the accuracy of precipitation estimation at a gauged or ungauged …  Read more

Dans un système multicellulaire, la réutilisation universelle des fréquences peut être utilisée dans un réseau de cellules voisines pour une efficacité spectrale supérieure. Cependant, la réutilisation universelle des fréquences provoque de l'interférence intercellulaire (ICI) sévère, qui peuvent nuire à la performance globale du système, en particulier dans les stations mobiles (MS) qui se trouvent dans la périphérie de la cellule. Pour contrer activement l'ICI, la norme de communication sans fil émergente préconise le concept de coordination multicellulaire informée d'interférence. Connu comme coordonnée de transmission/réception multipoint (CoMP), ce nouveau paradigme permet au système multicellulaire de contrôler activement et même de profiter …  Read more

Meaney, Michael (Supervisor1)  Read more

Our current understanding of how brokerage provides social capital is incomplete. While the processes through which network brokers reap rewards are well established, we know little about the outcomes of those connected to brokers, i.e., secondhand brokerage. This dissertation aims to explore how connections to network brokers impact individuals’ career sustainability, with a particular focus on whether this effect differs for women and men. Using large-scale digital trace data, I track the longitudinal collaboration networks of 571,851 filmmakers between 2000 and 2022 to investigate whether network contacts’ brokerage affects movie directors’ likelihood of continuing a directing career after their debut. …  Read more

Diksic, M. (Supervisor)  Read more

De plus en plus de personnes utilisent l'internet pour rechercher des informations sur la santé en raison de la facilité d'accès, de la diversité des choix et du caractère privé de ces sources d'information en ligne. Toutefois, la surveillance des sites web consacrés à la santé, qui s'appuie sur des technologies de suivi invasives, s'est accrue au fil du temps, conduisant à la collecte et à l'agrégation d'une grande quantité de données personnelles sur les utilisateurs. Nous avons échantillonné et analysé 22 sites web d'information sur la santé pertinents pour les résidents canadiens afin de détecter les niveaux de surveillance …  Read more

A cDNA encoding the precursor form of rat liver mitochondrial matrix enzyme, ornithine carbamyl transferase (pOCT) was cloned and its complete nucleotide sequence was determined. Full-length pOCT cDNA was cloned in pSP64 and expressed under the control of the SP6 promoter. The SP6-produced precursor protein was imported by rat heart mitochondria in vitro and processed to mature protein. Fusions of pOCT presequence to bacterial asparagine synthetase (AS) facilitated delivery of the hybrid protein to the mitochondrial matrix, indicating that the signal sequence of precursor ornithine carbamyl transferase contains sufficient information to target and translocate attached proteins into mitochondria. Deletion mutation …  Read more

The antioxidant capacity of 38 essential oils (EOs) and their enrichments were evaluated using two in-vitro methods: the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the Oxygen Radical Absorption Capacity (ORAC) assays. Phenols were found to significantly contribute (p < 0.05) to the synergistic effects within EOs in both assays. Combining EOs with polyphenols (PPs) can lead to synergistic effects, decreasing the quantity required to extend shelf life. These effects were investigated using a multiple-method approach where 6 selected EOs were enriched with 8 individual PPs, 4 mixtures of major plant extract PPs, and 4 crude plant extracts. As the number of advantageous functional …  Read more

To investigate the role of neurofilaments (NFs) in amyotrophic lateral sclerosis (ALS), levels of the three subunits were genetically manipulated in transgenic mice expressing a mutant superoxide dismutase 1 (SOD1 G37R). Reducing the amount of NFs in motor axons and thereby reducing axonal caliber, did not slow down motor neuron disease in SOD1G37R mice. Moreover, increasing the density of NFs in axons by human NF-L overexpression did not accelerate pathology either. Therefore, it is concluded that a high NF content and a large caliber of axons may not account for the selective degeneration of motor neurons in ALS mice. Surprisingly, …  Read more

Le Concerto pour Hautbois et Ensemble à Vent est orchestré pour hautbois solo et un ensemble à vent de trente-huit musiciens. Inspirée par la nouvelle d'Edgar Allan Poe intitulée "Le Cœur révélateur", la forme narrative globale de l'œuvre est linéaire. Elle commence en établissant une atmosphère glauque par le biais d'une texture légère, puis évolue continuellement vers des textures plus complexes et épaisses, culminant en un climax final et furieux. Celui-ci se libère en se dissipant jusqu'à la fin. Pour la décrire plus formellement, la pièce montre un côté plus historique dans le traitement de la relation entre le soliste …  Read more

Parathyroid hormone-related peptide (PTHrP) is a factor with numerous biological functions elicited either by secreted isoforms activating the cell surface type 1 PTH receptor or by intracrine species mediating actions at the level of the cell nucleus/nucleolus. To gain insight into the mechanism(s) whereby PTHrP, normally a secreted protein, bypasses the secretory pathway and enters the cytosol for subsequent nuclear import, we characterized its nuclear forms. In transfected COS-1 cells, three nuclear PTHrP isoforms were identified, which were larger than the mature protein but smaller than preproPTHrP and comprised both the peptide's amino and carboxyl termini. These also encompassed part …  Read more

Malgré les nombreuses améliorations de la technologie, il reste encore très difficile pour les prévisions météorologiques numériques de prédire avec précision l’évolution des systèmes météorologiques. Alors qu’une grande partie de la recherche sur ce problème se concentre sur l’amélioration des conditions initiales (CI) des petites échelles pour obtenir des prévisions plus précises, plusieurs études récentes ont montré que les erreurs dans les grandes échelles peuvent réduire considérablement la prévisibilité du modèle de prévision numérique du temps. Cette thèse étudie l’influence des différentes échelles spatiales dans les CI sur l’évolution de deux événements de précipitations. Pour y parvenir, le champ du …  Read more

L’insuffisance rénale aiguë sous la forme d’un délai de la fonction ou d’une fonction lente est la complication la plus fréquente après une greffe rénale et provoque des conséquences immunologiques négatives. Présentement, il n’y a aucun biomarqueur clinique pour prédire cette condition reliée à une blessure d’ischémie-reperfusion et aucune thérapie clinique pour la prévenir. Les lymphocytes T régulateurs (Tregs) sont des lymphocytes T CD4+ qui jouent un rôle essentiel pour maintenir la tolérance en transplantation et protègent contre la blessure d’ischémie-reperfusion chez les rongeurs. Leur différentiation à partir des lymphocytes T CD4+ naïfs est étroitement reliée aux lymphocytes Th17. Le …  Read more

Hydatidiform mole (HM) or molar pregnancy is a rare complication of pregnancy characterized by the excessive proliferation of the trophoblast and abnormal embryonic development. Recurrent hydatidiform moles (RHM) are defined by the occurrence of at least two HMs in the same patient. Though there are two genes, NLRP7 and KHDC3L, whose mutations cause RHM, there exist other patients without mutations in the known genes.Chapter 2 in this thesis describes my MSc project before I fast-tracked to the PhD program. This project focused on the genetic characterization of the conceptions of patients with bi-allelic NLRP7 mutations. Our work showed that NLRP7 …  Read more

Les neurones du cortex visuel du bas niveau sont parmi les cellules les plus étudiés du système visuel. Ces neurones peuvent être classés en deux types distincts en fonction de leur réponse à la phase spatiale du stimulus visuel. Les cellules simples dépendent de la phase spatiale tandis que les cellules complexes sont invariantes par rapport à la phase. Un aspect attirant des cellules simples est qu'elles peuvent être modélisées comme un système quasi-linéaire. En raison de l'invariance de phase, les cellules complexes sont beaucoup plus difficiles à estimer, ce qui nécessite des modèles lourdement paramétrés. Nous introduisons deux méthodes …  Read more

This thesis is arranged in two distinct parts. The first part involves the construction of a novel dynamical scheme which is capable of generating the masses of the quarks and the elements of the Kobayashi-Maskawa matrix, and which does not rely upon the Higgs mechanism. The up quarks acquire their masses by coupling to a new heavy fermion via emission and reabsorption of a new scalar boson. The down quarks, on the other hand, obtain their masses via a correction to the up mass matrix as a result of an anomalous flavour changing interaction of the $W sp pm$. Extensions …  Read more