McGill University Thèses et mémoires par auteur commençant par L

Calvinism invested the institution of marriage with a dignity and importance it had never before enjoyed. With its enforcement of sacerdotal celibacy and its early established tradition of regarding marriage as nothing more than a remedy for lust, the Roman Church had devalued both human sexuality and matrimony throughout the Middle Ages. [...]  Lire la suite

This paper deals with the results of a study and review of the petrographical, stratigraphical, and structural characteristics of certain basic intrusives, generally distributed throughout the Canadian Shield, which are described as "diabase" dykks and sills. It is found that the cutting relationships reported afford positive evidence of at least four sequences of "diabase" intrusion. Except for degree of alteration, the sequences resemble each other so closely that positive age correlation on a petrographical basis is precluded. The dykes have predominant north west, north-south, and north a act trends. The writer concludes thab structural evidence suggests" the hypothesis that the …  Lire la suite

The claudins are a family of integral membrane proteins located in tight junctions. Tight junctionsare protein complexes that links the membrane of adjacent epithelial cells together. Claudinsregulate paracellular transport between cells in mature epithelia. Interestingly, claudins areexpressed in several branching organs during development, for example, the kidneys and thelungs, even prior to the initiation of paracellular transport. Previous results from my laboratoryshowed that the removal of a subset of claudins using the non-toxic protein reagent C-CPE (atruncated form of Clostridium perfringens enterotoxin) resulted in the reduction of branching inmouse embryonic kidney explants.To determine if claudins are required for lung branching …  Lire la suite

A feasibility study into the use of UHF-EM transillumination measurements in geophysics is presented. The electrical properties and absorption rates of common crustal materials are examined with the goal of identifying specific conditions under which sufficient material penetration at UHF frequencies is available. A prototype 445 MHz continuous-wave transillumination instrument designed for underground use is described. Test surveys, with this instrument, were conducted at the Big Nickel Mine in Sudbury, Ontario, to obtain a number of through-rock absorption rates. Estimated effective resistivities of between 500 and 1500 ohm-metres are determined from the survey data. Effective conductivities and permittivities from AC …  Lire la suite

This thesis focuses on the issue of occupational injuries. There are four different explanations of why accident rates vary. A set of research hypotheses were created based on these explanations. Multivariate regression analyses of aggregate secondary data were used to test four hypotheses. The findings of these analyses indicate that establishment size, unionization rates and strike and lockout rates are related to injury rates but earnings are not. A fifth hypothesis was tested using the mining industry of Ontario as a case study. This analysis indicates that safety-related legislative and regulatory changes were not effective in reducing either fatal injuries …  Lire la suite

Tampieri, Donatella (Supervisor2)  Lire la suite

The role of the thyroid gland in fish is little understood, while it is well known in mammals, birds and amphibians. Thus, in mammals and birds this gland controls the metabolism. In many amphibians the thyroid is responsible for the metamorphosis occurring at the transition from an aquatic to a terrestrial environment. [...]  Lire la suite

Lors de son arrivée dans le coin Sud-Ouest de l'Alberta en 1997, Conservation de la nature Canada (CNC) était un parfait étranger. Cependant, au cours d'une décennie, cet organisme est devenu le plus important propriétaire local grâce à l'achat de la majorité des terres adjacentes à l'est du Parc national des Lacs-Waterton. Ainsi est née la plus grande initiative de conservation privée au Canada existant à l'époque. La clé de son succès fut une alliance avec des éleveurs qui auront accepté de vendre leur ranch en échange de longs contrats de location par la suite. La science étant de son …  Lire la suite

Le suivi de la direction de la tête fait partie intégrante du système de navigation spatiale du cerveau. Il est important autant pour les systèmes de navigation qui reposent sur des repères visuels, comme la navigation par points de repère, que pour ceux qui n'en dépendent pas, comme l'intégration de trajectoire. Les cellules qui réagissent à un animal orienté dans une direction spécifique, appelées cellules de direction de la tête (HD), sont présentes dans plusieurs régions du cerveau, notamment dans le noyau thalamique antérodorsal (ADN), une région qui intègre les informations des systèmes vestibulaire et visuel.Lorsqu'il entre dans un environnement, …  Lire la suite

Baker, Don (Internal/Supervisor)  Lire la suite

Formation of gametes capable of supporting development is dependent on a number of genetic and epigenetic events. DNA methylation is an epigenetic modification catalyzed by enzymes named DNA methyltransferases (DNMTs). In the mouse, methylation of DNA is associated with the control of gene expression and proper embryo development. Methylation patterns are established in a sex- and sequence-specific manner during male and female germ cell development and further modified during early embryonic development. Even though new DNMTs have recently been identified, little information is known on the origin of the methylation marks during male germ cell development (spermatogenesis). The main goal …  Lire la suite

La protéine p66Shc est caractérisée comme pro-oxydante et induisant la génération de ROS en réponse au stress cellulaire, ce qui a le potentiel d’induire la mort cellulaire. Dans les cellules normales, p66Shc est cruciale pour l'apoptose induite par p53 en réponse aux insultes oxydatives. L'expression de p66Shc varie dans les cancers du sein, suggérant qu'elle est tolérée dans certains contextes de cancer. Pour étudier les contextes où p66Shc favorise ou inhibe la croissance tumorale, p66Shc a été surexprimé dans les cellules primaires du modèle de souris du cancer du sein induit par ErbB2, MMTV-Neu(NDL2)-IRES-Cre (NIC). De plus, les tumeurs NIC …  Lire la suite

The effects of the three factors (modification, grain refinement, and hydrogen level) on the amount of porosity, impact strength, and performance of the reduced pressure test in A356 alloy have been studied. It was found that grain refinement, acting singly and in combination with modification, reduces the porosity by inducing mass feeding. However, this beneficial effect may not be found at all cooling rates and casting sizes. There is less total shrinkage in Sr-alloyed samples than in those which are non Sr-alloyed. The reason for this is supposed to be a difference in the liquid density which may be higher …  Lire la suite

The concentration of hydrogen is one of the most important parameters in liquid aluminum processing because it is responsible for gas porosity which affects casing quality, ie. pressure tightness, mechanical properties etc. In order to gain optimum quality, the amount of hydrogen dissolved in liquid aluminum must be known prior to casting. This has led to the development of several techniques to quantify hydrogen in liquid aluminum. Among these is the Reduced Pressure Test (RPT). The RPT is simple, very inexpensive and commonly used in aluminum foundries to obtain a qualitative evaluation of the melt hydrogen level. In this thesis …  Lire la suite

Pack, Christopher (Supervisor2)  Lire la suite

Brain tumour stem cells (BTSCs) possess a unique metabolic phenotype in glioblastoma multiforme (GBM), relying on oxidative phosphorylation (OXPHOS) as opposed to aerobic glycolysis seen in the bulk of the tumour. The mechanisms regulating this metabolic distinction are poorly understood. Here, I report a novel role of oncostatin M receptor (OSMR) in the upregulation of OXPHOS in BTSCs. Our laboratory has recently established that OSMR is a requisite component of the oncogenic EGFRvIII signaling pathway, and RNA seq analysis of OSMR candidate target genes revealed OSMR regulation of key metabolic genes. To determine the effect of OSMR signaling on metabolic …  Lire la suite

The Ghana Health Service’s (GHS) outreach program has expanded its reach to remote rural communities through monthly growth monitoring and promotion (GMP) community-based clinics. Even though the wasting (< -2 weight-for-length z-score [WLZ]) prevalence rate is higher than underweight in infancy, only weight is measured; no provision exists to measure length in the GHS GMP outreach service. The inadequate nutrition knowledge and poor counselling skills of community-based health personnel (community nurses and health volunteers) and the lack of counselling aids and tools further impede the prevention and management of wasting. The aim of this study was to determine if increasing …  Lire la suite

Common-pool resources often become depleted because they are rival goods and exclusion of users is difficult. Collective action systems are historically effective solutions to this problem that use agent heterogeneity and complex social structures to motivate sustainable extraction and generate abundance in the community. However, most economic analyses of the depletion problem and its solutions are based on individualistic choice models which assume that agents are homogenous, self-interested utility maximisers who make decisions independently of other agents. Such models cannot process social features or unique agent characteristics and thus treat collectives as single decision-making units, preventing the mechanisms within them …  Lire la suite

With the aim of simulating the hot rolling process, single and double hit compression tests were performed in the temperature range 800 to 1200$ sp circ$C at strain rates of 0.2 to 50 s$ sp{-1}$ on selected low carbon steels containing niobium, boron and copper. The stress/strain curves determined at high strain rates were corrected for adiabatic heating and constitutive equations were formulated. When dynamic recovery is the only softening mechanism, these involve a rate equation, consisting of a hyperbolic sine law, and an evolution equation with one internal variable. When dynamic recrystallization takes place, the incorporation of the dynamically …  Lire la suite

In recent years, research on informal language learning has expanded significantly (Dressman & Sadler, 2020), highlighting its role in increasing learner motivation, confidence, and real-world communicative competence (Montrul, 2019, Mihre & Fiskum, 2021, Polat & Kim, 2014, Arndt, 2019). However, very few studies (Reva, 2012; Cabrera Arias, 2022) have examined institutionally organized informal activities within university language centers that are designed to complement formal instruction. This qualitative study investigates Cocurricular and Extracurricular Activities (CECA) within two Quebec university language learning centers. Using a phenomenological approach, ecological framework, and reflective thematic analysis, the research explores students’ value perception of CECAs as …  Lire la suite

Denov, Myriam (Supervisor1)  Lire la suite

Pour déterminer si les élèves peuvent être invités à recevoir de l'information et de divulguer leur résultats de maladies sexuellement transmissibles (MST) à leurs partenaires romantiques et leurs parents, pour aider à freiner la propagation du VIH, l'herpès, ou de l'hépatite, 303 élèves (183 de l'Université McGill et 120 à l'Université du Kwa-Zulu Natal, (M = 21 ans) ont été invités à indiquer comment ils préféreraient se dévoiler leur résultats MST: (1) par rendez-vous; (2) par appel cellulaire; (3) par message texte (SMS); ou (4) par d'autres modes de communication médiatisées par ordinateur. Les étudiants ont aussi indiqué qu'ils préféreraient …  Lire la suite

Dube, Laurette (Supervisor1)  Lire la suite

Aplysia californica is a model organism for determining the molecular basis of memory. In this system, identified synaptic changes have been closely linked to behavioral memories. Indeed, serotonin (5-HT) was characterized as the primary neuromodulator responsible for sensitization. Application of 5-HT to sensory-motor cultures can induce synaptic strengthening, termed facilitation, much like that seen in behavioral learning paradigms. Short-term facilitation is dependent on phosphorylation by key protein kinases, while long-term synaptic changes between sensory and motor neurons require both gene expression and protein synthesis. One important mechanism for translational control is mediated through the target of rapamycin (TOR). An important …  Lire la suite

Schizophrenia (SCZ) is believed to be a neurodevelopmental disorder resulting from genetic and environmental factors. Obstetric complications, particularly fetal hypoxia, seem to be a risk factor for SCZ. The hippocampus is highly sensitive to ischemic episodes, and there is substantial evidence for hippocampal malfunction in SCZ. Thus, utilizing a rat model of global anoxia (15 min and 21 min) during Cesarean-section birth (C-section), hippocampal proliferation was examined in the dentate gyrus and CAI region at postnatal day 21 and day 60. Incorporation of 5-bromo-2-deoxyuridine (BrdU) was used as a marker of cell proliferation. Rats were sacrificed 2 hours after BrdU …  Lire la suite

Despite the early diagnosis and efficient treatment of most early-stage tumors, prostate cancer (PCa) remains the second leading cause of cancer-related deaths in North American men. This reflects the use of androgen deprivation therapy, initially described in 1941, as the standard treatment for patients diagnosed with advanced disease despite the eventual development of incurable castration-resistant metastatic cancer. Therefore there is an urgent need for novel and innovative approaches to effectively treat this disease. Elevated tyrosine phosphorylation is a major contributor to tumor progression. As such, many tyrosine kinase inhibitors are presently being tested for the treatment of advanced PCa in …  Lire la suite

The effects of temperature on a 58-kDa phosphoprotein (PP58) have been examined in cell-free extracts of two alfalfa (Medicago sativa L.) cultivars, Apica and Trek. In the extracts prepared without the use of Triton X-100, PP58 is present in a 12,000 x g (P12), 28,000 x g (P28) and 100,000 x g (P100) pellets but is enriched in the P28 fraction. In these fractions PP58 is substantially and equally phosphorylated at both 4° and 24°C. When extracts are prepared in the presence Triton X-100, PP58 is present in the 28,000 x g supernatant (TXS fraction) is extensively dephosphorylated at 24°C …  Lire la suite

Hydro-Quebec's electricity exports greatly affect our economy and our environment. They may be concluded either under "interconnection agreements" to sell excess capacity and production during off-peak periods, or completed under "firm sales" contracts. Hydro-Quebec exports could thereby replace production plants that are needed and difficult to build south of the border. Economics and regulation of the American industry have led to the writing of too much rigidity into the clauses. There are long term, responsibility, major force and other clauses that prevent the contracts from adapting to the changing competitive market conditions. Utilities involved in such international sales would be …  Lire la suite

Cell death and inflammation are two central, tightly coupled, innate immune processes. The inflammasome triggers both in response to pathogens and tissue damage. This cytosolic signalling complex contributes to host-defence, tissue repair and inflammatory disease, but the factors governing inflammasome activity are poorly characterized. This thesis examines the function of inflammasome modulators in infection and immunity. Inflammasome activity is antagonized by caspase-12. In humans, caspase-12 expression is limited to populations in geographical locations that overlap with regions endemic for malaria. We found that caspase-12 dampens the inflammatory response to Plasmodium, the malaria-causing parasite, resulting in impaired parasite clearance, but protection …  Lire la suite

Sepsis-induced diaphragmatic force loss and failure are associated with an increased exposure to proinflammatory mediators. The septic diaphragm has recently been reported to overexpresse chemokines, including the CC chemokine MCP-1 (monocyte chemoattractant protein-1). This thesis seeks to address the significance of MCP-1 overproduction in diaphragm proinflammatory mediator expression and skeletal muscle contractile function. Neutralization of endogenous MCP-1, produced following administration of LPS, decreased transcription of iNOS, IL-6, IL-1alpha, IL-1beta and MCP-1 in the diaphragm and prevented a decrease in diaphragm force production. Furthermore, exogenous MCP-1 stimulated IL-6 and MCP-1 transcription in primary diaphragm myotubes, and injection of MCP-1 in the …  Lire la suite

Latency represents the major obstacle currently faced in the development of a curative HIV therapy. Latency is responsible for the persistence of HIV in treated individuals and can be established in different cell types. It has been shown that components of intrinsic immunity play a critical role in the establishment and maintenance of latency. Protein Kinase R (PKR) is an interferon stimulated gene (ISG). It is a sensor of pathogen associated molecular patterns (PAMP) and is activated by double stranded RNA. Activated PKR inhibits the production of viral proteins in HIV infected cells. PKR is transiently activated at the beginning …  Lire la suite

The polymerase chain reaction (PCR) is a highly specific and sensitive diagnostic tool and the gold standard in many of its applications, such as the detection of bacterial infections. During a polymerase chain reaction, target fragments of nucleic acid are duplicated thanks to the actions of the polymerase enzyme, leading to an exponential increase in the concentration of the target, making it easier to detect. PCR is performed via a cyclical change of temperature, rising to 92°C for the DNA strands to melt and separate, then down to 55°C and 72°C for the other reagents to act and start the …  Lire la suite

The two rounds of cell division that constitute meiosis are a conserved process that generates the gametes required for sexual reproduction. Given the importance of this specialized cell division in forming new life it is imperative for meiotic cells to ensure that the homologous chromosomes (at meiosis I) and subsequently the sister chromatids (at meiosis II) are properly segregated to avoid aneuploidy and infertility. As a first step in this process the maternal and paternal chromosomes (the homologs) have to be able to recognize each other and align along their length (pairing). In many organisms this culminates in the formation …  Lire la suite

Cette thèse étudie certaines fonctions rationnelles dépendant d'un élément positif du réseau des racines d'un système de racines. Ces fonctions apparaissent comme produit de Shapovalov de vecteurs de Whittaker dans les modules de Verma pour les groupes quantiques, de plus haut poids donné par l'opposé du vecteur de Weyl. Elles apparaissent également comme séries de Hilbert d'espaces de Zastava et sont liées au système de Toda. Ce sont des spécialisations de fonctions multivariées plus généralement étudiées dans la littérature. Nous examinons le dénominateur de ces fonctions rationnelles et nous donnons une formule combinatoire explicite pour le numérateur en type A. …  Lire la suite

We describe how to embed a graph into a small n-dimensional hypersphere such that the endpoints of any edge are placed exactly one unit of distance apart. As an application, we show how such an embedding can be used to find large independent sets in sparse 3-colorable graphs. By combining this algorithm with another which is specialized in dense graphs, we obtain a randomized, polynomial time algorithm that can color any 3-colorable graph using at most O(n1/4 log 1/2n) colors.  Lire la suite

The orphan nuclear receptor NR5A2 is implicated in a multitude of biological processes including cholesterol homeostasis and development. Its role in cholesterol metabolism and cell proliferation is now well established in vitro and in vivo. Both in vitro and gene expression studies have suggested a role for NR5A2 in ovarian function. In this study, we provide in vivo evidence for its involvement in reproductive function by demonstrating that heterozygosity for a null mutation of NR5A2 leads to a reduction in female fertility. Furthermore, we showed that NR5A2+/- females display a severe reduction in ovarian progesterone production and that progesterone supplementation …  Lire la suite

Kura clover was successfully established via sod-seeding in different environments. Its establishment and yields were initially inferior to that of red clover and white clover. But, its presence slowly increased in the sward and, by the first harvest of the second post seeding season, it was yielding significantly more than the legume species presently recommended for pastures. Clover establishment increased with increasing intensity of herbicide suppression. Best overall results were obtained with glyphosate at low rate (0.8 kg a.i. ha-1). Paraquat (0.9 kg a.i. ha -1) did not suppress sufficiently the grass population for clovers to establish while glyphosate applied …  Lire la suite

Demented persons of the Alzheimer type, and to a lesser degree, persons suffering from major depression, experience a loss of autonomy in their activities of daily living (ADL). This loss of autonomy is often associated with a decrease in the initiation, organization and continuation of the activity. The Psychogeriatric Basic ADL Scale developed for this study, was especially created for the aged experiencing a loss of autonomy as a consequence of problems other than motor and/or sensorial. It assesses the following activities: taking of a bath (or shower), dressing, grooming, continence and feeding, in relation to some higher cognitive functions. …  Lire la suite

Activation of the Unfolded Protein Response (UPR) following stress in the Endoplasmic Reticulum (ER) is an important mechanism by which obesity results in insulin resistance and type II diabetes. We uncovered a role for the adaptor protein Nck in modulating the UPR. In this study, we report that obese Nck1-/- mice, which show lower levels of UPR in liver and adipose tissue, present improved insulin signalling in these tissues. We established that the effect of Nck1 is cell autonomous by showing that HepG2 cells treated with Nck1 siRNA have reduced ER stress-induced UPR and Insulin Receptor Substrate-1 (IRS-1) serine phosphorylation. …  Lire la suite

Site-selective laser excitation and emission spectra were obtained with a 20% Eu$ sp{+3}$ exchanged sodium $ beta sp{ prime prime}$-alumina crystal at 77 and 6.4 K. Excitation into the $ rm sp5D sb0$ level (568-579 nm) shows that the trivalent europium ion occupies at least two types of site distributions. The first distribution occurs at the higher energy of the tuning range and has site symmetry C$ sb{ rm 3v}$ or C$ sb3.$ It corresponds to the crystallographic Beevers-Ross position. The other site distribution is observed at lower energy and is associated with the mid-oxygen crystallographic position (site symmetry: C$ …  Lire la suite

La résistance multiple à la chimiothérapie (MDR) dans le cancer est un phénomène qui nuit à l'efficacité du traitement et est devenue un important problème. Les transporteurs ABC comme la P-glycoprotéine (P-gp ou ABCB1) et la protéine associée à la résistance multiple 1 (MRP1 ou ABCC1) sont reconnue pour pomper de façon active les médicaments hors des cellules et de ce fait induisent la MDR. Une approche prometteuse visant à cibler spécifiquement ces cellules MDR est de prendre avantage de leur sensibilité accrue (sensibilité collatérale) face à certains composés.Le second chapitre de cette thèse visait à élucider le mécanisme de …  Lire la suite

In recent years, the trend for continuous down-scaling of CMOS device dimension has made analog design much more challenging. This trend has been a major driving force in trying to find new approaches for designing common analog building blocks. One such block is the bandgap voltage reference. This common circuit serves the purpose of generating a fixed DC voltage reference and has uses in a wide variety of applications. This thesis introduces a new way of generating a programmable DC voltage reference with similar performance to the traditional means. This voltage reference generator is based on periodic bit-stream modulation and …  Lire la suite