McGill University Thèses et mémoires par auteur commençant par J

Adams, Alayne Mary (Supervisor2)  Read more

Les protéines phosphatases agissent sur plusieurs substrats qui participent dans différents procédés dans les cellules de mammifères tel que le métabolisme du glycogène, la progression du cycle de la division cellulaire, la différenciation cellulaire, l'apoptose, la synthèse des protéines et la transduction du signal (Cohen, 2002; Berndt, 1999; Shenolikar, 1994). L'isoforme alpha de la protéine phosphatase de type 1 (PP1) peut jouer un rôle important dans la différenciation neurale. Nous avons démontré que le degré de phosphorylation de la PP1 affecte le degré de différenciation des cellules PC12 suite à un traitement au NGF. Cependant, la nécessité de la phosphorylation …  Read more

This thesis attempts to answer the following questions, each of which corresponds, sequentially, to chapter in this thesis: (1) What is the internal composition and the historical contextualization of the 18th chapter of the Qur'an, the Surat al-Kahf? (2) Who is al-Khadir, a figure in the Surat al-Kahf, verses 66-82? How has he been described in Muslim commentary and how has he been analyzed in nineteenth and twentieth century scholarship; and with whom has he been associated and/or identified in such commentary and scholarship? (3) How are probable prototypes or parallels of Khadir portrayed in non-Islamicate documents traceable to before …  Read more

The global demographic shift towards population aging will result in a dramatic increase in the numbers of elderly in the population. In order to cope with these changing demographics, it is imperative that we better understand aging and age-related pathologies. The reproductive tract provides an excellent system in which to study aging in that it is affected by aging, without compromising the overall health of the individual. In the Brown Norway rat model, the male reproductive tract (testis and epididymis) shows numerous signs of aging when other systems remain relatively unaffected by age, thus making this system ideal for studies …  Read more

La voie de signalisation Notch1, qui est strictement régulée, joue un rôle important dans les décisions du destin cellulaire et l'homéostasie tissulaire. Son dérèglement a été impliqué dans la pathogénèse de plusieurs maladies, y compris les maladies hématopoïétiques et le cancer. Notre groupe avait préalablement identifié Notch1 comme étant un site commun d'insertion provirale dans les leucémie à cellules T induites par mutagénèse insertionnelle chez les souris transgéniques (Tg) MMTV/cmyc. Deux produits de transcription ont été identifiés dans cette étude: une forme constitutivement activée du domaine intracellulaire Notch1 (NIC), ainsi qu'une forme tronquée et sécrétée du domaine extracellulaire Notch1 (NEC). …  Read more

Pediatric high-grade gliomas (HGG) are lethal childhood cancers. HGG are frequently driven by mutations in Histone 3, including lysine-to-methionine (H3K27M) mutations in H3.1, H3.2, and H3.3, and glycine-to-arginine or valine (H3G34R/V) mutations in H3.3. Tumors with different H3 mutations arise in distinct brain regions and time windows and co-occur with distinct partner mutations. A central question in understanding the biology of H3-mutant HGG is deciphering the effects of their driver alterations, but it has been challenging to uncouple oncogenic consequences from the contribution of tumor cell of origin. We hypothesize that specific cell types during development are uniquely susceptible to …  Read more

Cette thèse présente une méthodologie générale pour la segmentation et la détection des lésions dans des IRMs (imagerie par résonnance magnétique) de cerveaux en utilisant des réseaux neuronaux entièrement convolutionnels (REC). Le schéma REC est choisi en raison de sa capacité à modéliser le contexte multi-résolution dans le domaine de l'image et à produire des résultats de segmentation sémantique cohérents. Cette thèse étend le schéma REC pour mieux convenir à la tâche de segmentation et de détection des lésions cérébrales en incluant des convolutions 3D pour capturer le contexte complet des volumes IRM, une décroisance programée sur les poids des …  Read more

Desert Places is a composition for large orchestra with a duration of approximately 12 minutes. Inspired by the Robert Frost poem "Desert Places", the work is primarily concerned with "covering up" one type of musical material with another. Specifically, the work contains a large-scale "cross-fading" of two types of motivic material, and two types of harmonic material. While the processes at work remain clearly defined, the musical materials move smoothly and gradually through the piece, exchanging foreground and background positions, and blurring the divisions of sections.  Read more

The in situ, equimolar, trimethylaluminum/H$ sb2$O catalyst was used for the ring opening polymerization of racemic $ beta$-butyrolactone, $ beta$-heptanolactone and $ beta$-nonanolactone to form synthetic analogues of the naturally occurring family of biodegradable poly((R) -$ beta$-hydroxyalkanoate) polymers. This catalyst was found to produce both a better yield and a higher molecular weight of a high isotactic, primarily crystalline fraction of poly($ beta$-(R,S) -hydroxybutyrate) than the conventional in situ, equimolar triethylaluminum/H$ sb2$O catalyst. A mechanically tougher, less isotactic and less crystalline fraction of lower molecular weight and a largely amorphous fraction of even lower molecular weight were also isolated and …  Read more

On presente une generalisation d'un resultat de Wallin ainsi qu'une caracterisation des ensembles compacts polaires dans un espace de Brelot. Ces resultats se generalisent a un produit de n espaces de Brelot en demontrant la continuite des fonctions multireduites. On en deduit qu'un ensemble localement n polaire est un ensemble in polaire. Des resultats semblebles ont lieu pour une sous-classe des ensembles pluripolaires dans un domaine hyperconvexe et borne de C('n).  Read more

In this study, the near-limit propagation of detonations in annular channelsis investigated. Stoichiometric mixtures of methane-oxygen, acetylene-nitrousoxide diluted with 50% argon and acetylene-oxygen diluted with 70% argon areused in the experiments. Detonation velocity as well as smoked foil records ofnear-limit detonations are obtained. It is found that by normalizing the channellength scale by the ZND reaction length, ( i.e. L/ΔZND, where L is the channelgap) the velocity variations for different channels coalesces to a single curve.Thus the detonation velocity in annular channels depends on the relative rolebetween the geometry and the chemical sensitivity of the mixture. Detonationvelocities of the order …  Read more

The overarching goal of the work presented in this thesis is to formulate, implement, test, and demonstrate cost-effective mathematical models and numerical solution methods for computer simulations of fluid flow and heat transfer in loop heat pipes (LHPs) operating under steady-state conditions.A segmented network thermofluid model for simulating steady-state operation of conventional LHPs with cylindrical and flat evaporators is proposed. In this model, the vapor-transport line, condenser pipe, and liquid-transport line are divided into longitudinal segments (or control volumes). Quasi-one-dimensional formulations, incorporating semi-empirical correlations for the related single- and two-phase phenomena, are used to iteratively impose balances of mass, momentum, …  Read more

The experimental investigation described in this thesis is primarily aimed at acquiring digital particle-tracking velocimetry (DPTV) measurements of a free-surface granular flow down the upper inclined surface of a wedge-shaped static pile of the same material, contained in a narrow channel between two parallel vertical glass plates. The glass plates are 610 mm long and 350 mm high. Three different values of the normal separation distance between them were investigated: 25.4 mm, 38.1 mm, and 50.8 mm. For each of these separation distances, the following three values (nominal) of the mass flow rate per unit width were considered: 0.81 kg/s-m, …  Read more

The biggest challenge to islet transplantation is preserving cell mass and function. It is known that the stresses encountered during islet isolation have deleterious effects on beta-cell physiology. The nature of these effects, however, are incompletely known, partly due to the heterogeneity of islet preparations. Using a combination of laser capture microdissection and microarray technology, we therefore sought to determine the beta-cell specific events that occur as a result of islet isolation and in vitro culture. Our data shows that islet isolation and in vitro culture induce a large inflammatory response that is NF-kB dependent and involves the upregulation of …  Read more

Cette thèse vise à comprendre les propriétés optiques de petites nanocristaux (NC) semi-conductrices présentant une double émission intrinsèque (noyau et surface). Pour étudier la dépendance à la taille de petites NC, nous avons synthétisé un ensemble de NC CdSe avec des tailles allant de 0,89 à 1,66 nm de rayon. L'étude confirme que lorsque les nanocristaux deviennent petits, l'émission de surface augmente fortement en amplitude, et l'émission de noyau s'élargit et déplace à des énergies plus basses. Ces effets sont rationalisés en termes de couplage aux ligands via la théorie du transfert d'électrons. La transition entre le régime QD et …  Read more

Usselman, Charlotte (Supervisor1)  Read more

The work described involves the study of shock-induced reactions in binary/heterogeneous reactive powder mixtures that produce little or no gas and the possibility that a detonation could be produced in such mixtures. The first task was to identify the mechanism by which these mixtures reacted when shocked. Critical initiating shock pressure and autoignition temperature were determined for a number of mixtures by recovery of shocked samples and differential thermal analysis, respectively. In addition, recovery experiments using Mn+S in two different charge geometries and at two different nominal densities (60% TMD and 90% TMD) were carried out to study the effect …  Read more

An experimental study of the process of shock initiation of detonation in liquid nitromethane sensitized with diethylenetriamine (DETA) was conducted. In particular, the effect of the lateral boundary conditions on the sensitivity of the explosive to shock stimuli was investigated. The explosive was tested in a "gap test" arrangement. Various charge diameters and different materials for the capsule that contained the test explosive were used. The arrival time of the shock front was recorded at different locations along the test charge and the light emitted in the cases where detonation was initiated in the test explosive was monitored. It is …  Read more

This thesis introduces three new tools for studying the evolution of different organisms given the evolutionary, or phylogenetic, tree that relates them. First, we show how posterior state probabilities can be used for exploring phylogenetic uncertainty, through posterior entropy of ancestral states. Second, we derive an explicit formula for the expected number of substitutions on a branch in a phylogeny, given the pattern at the leaves. Algorithms were implemented, as part of the ATV software, to calculate these values. They are used, in conjunction with SplitsTree4, to assess variation in rates over sites and lineages, and to predict model violations. …  Read more

The study investigates farmers' decision to afforest marginal agricultural land to create carbon sinks in western Canada. A real option model, which incorporates price risks related to carbon and timber revenues as well as opportunity cost uncertainty, is used to assess the impact of a carbon market on farmers' afforestation decision. Irreversibility of the decision is also modeled by including sunk cost of forest establishment and the cost of reversing the afforestation process. In addition, the non-permanence impact on the profitability of afforestation was analyzed by assessing the effect of two non-permanence carbon accounting schemes. Results indicate that both, actual …  Read more

This work studies supermanifolds and some of their applications, the goal being to study Hamiltonian systems, in particular the idea of complete integrability and some systems associated to coadjoint orbits. The approach taken here is that of Jadczyk and Pilch [21] where the anticommuting quantities enter at the "point" or coordinate level. This is in contrast with the approach that enters them at the function level by modifying the sheaf of functions (Kostant [24]). The basic definitions are given, such as supernumbers, superspaces, concepts of analysis and finally the notion of a supermanifold. Once the groundwork is established, questions relating …  Read more

Communities of organisms that experience a change in environmental conditions must modify their phenotypes in order to persist. The matching of phenotypes to the environment can be driven by physiological plasticity within individuals, by genetic evolutionary change within populations, or by ecological shifts in species composition within communities. However, how these three nested scales of phenotypic change combine is not well understood. To address this question, I use communities of small free-floating aquatic plants, dominated by species within the family Lemnaceae, focusing on Lemna minor, the common duckweed. The highly reduced morphology and rapid reproduction of Lemnaceae make these plants …  Read more

Biological evolution is unlike other topics in science. For many students, it is emotionally-charged and conceptually difficult, and yet it is vital to making sense of biology. Considerable research has addressed the unique challenges of teaching evolution, but it has left many questions unanswered. In this thesis, I will provide an overview of the literature on strategies for teaching evolution with an emphasis on those for which there is empirical support. Conclusions that may be drawn from this literature and limitations of the studies will be discussed. Based on the findings, I will argue that the best approach to evolution …  Read more

Thombs, Brett D. (Supervisor1)  Read more

La sclérodermie systémique ou la sclérodermie (SSc), est une maladie auto-immune du tissu conjonctif qui est rare et chronique. Elle est caractérisée par des défigurements importants et visibles des parties du corps socialement pertinentes, tels que la bouche, le visage, et les mains. Il n'existe aucun remède pour la SSc et les traitements atténuent à peine les changements physiques défigurants qui peuvent être importants et difficiles à dissimuler. Il y a très peu de recherches faites sur la défiguration et sur les préoccupations de l'image corporelle chez les personnes atteintes de la SSc. La recherche actuelle se compose de deux …  Read more

Our provisions for dependent groups in our communities are so conditioned by the moralistic philosophy of the past, and by our attitudes towards them as individuals, that it becomes necessary from time to time to evaluate our thinking in this connection. It is somewhat disconcerting to discover that many of our present provisions for dependents in our society continue to be based on the theories that were widely held as far back as the seventeenth century. We are all too familiar with the reaction that meets any new social welfare measure which aims at putting certain economic props under various …  Read more

Cerruti, Marta (Supervisor1)  Read more

Les cellules souches pluripotentes ont été isolées dans au moins deux états distincts: totipotent et multipotent. Les cellules totipotentes, dérivées de la masse cellulaire interne (MCI), sont capables de produire tous les types cellulaires. D’autre part, les cellules multipotentes, dérivées de l’épiblaste de l’embryon post-implanté, sont à l’origine de différents types cellulaires spécifiques. Bien que ces cellules aient été largement étudiées dans le domaine de la génétique et de l’épigénétique concernant leur rôle dans différenciation, elles présentent également des caractéristiques morphologiques distinctes. En culture, les cellules totipotentes forment des colonies serrées et compactes de cellules non polarisées de façon désorganisée, …  Read more

Gros, Philippe (Supervisor1)  Read more

Several studies have demonstrated that certain genetic variants of beta-casein are closely related to milk production, milk composition and technological properties of milk such as coagulation properties during cheese making, calcium precipitation and water binding properties. The objective of current study is to investigate the effect of the genetic variants on hydrolysis of beta-casein by chymosin and pepsin. On the basis of a preliminary analysis, a total of 50 milk samples which provided representatives of different available genetic variants of beta-casein were collected from different herds in Quebec. Casein was prepared from milk samples by the acid precipitation and the …  Read more

Phoebe Friesen (Supervisor2)  Read more

O'Brien, Elizabeth Ann (Supervisor2)  Read more

Taxonomy, according to Lawrence (1951) is a science that includes identification, nomenclature ahd classification of objects, and is usually restricted to objects of biological origin. He, further says that the plant taxonomy is fundamentally based on morphology vdth the support of all interrelated sciences. [...]  Read more

The hypothalamic supraoptic nucleus (SON) in the rat contains neurons that synthesize either vasopressin (VP) or oxytocin and that receive prominent afferent connections of cardiovascular origin. In vivo electrophysiological studies were undertaken to characterise the selective depression of VP-secreting cell activity consequent to activation of peripheral baroreceptors. Electrical stimulation of the diagonal band of Broca evoked a similar selective inhibition of supraoptic VP neurons. Extracellular recordings in the diagonal band confirmed the involvement of this site in the baro-reflex input to the SON. Local application of bicuculline, a GABA antagonist, abolished both the diagonal band-evoked and the baroreceptor-induced inhibition of …  Read more

Durant le développement du cortex cérébral mammifère, des cellules souches neuronales situées dans la zone ventriculaire se différencient en neurones, astrocites, et oligodendrocites. Durant ce développement la neurogenèse prend place en premier, suivi par la différenciation des astrocites et celle des oligodendrocites. Les mécanismes régulateurs de la différenciation sont en parti sous le control des facteurs de transcriptions « basic-helix-loop-helix » (bHLH) appartenant au groupe « Hairy/Enhancer of split » (Hes). Plusieures protéines Hes sont activées par la signalisation de Notch. Ces protéines, tel Hes1 et Hes5, sont des inhibiteurs de transcription durant la neurogenèse corticale et promeuvent la différentiation …  Read more

Ghosh, Ratna (Supervisor)  Read more

Bergevin, Yves (Supervisor1)  Read more

The main objective of this research is to establish durability design models for flexural concrete elements subjected to a given aggressive environment. Because corrosion of reinforcement due to chloride ingress is the most significant threat to an existing reinforced concrete structure such as a road bridge or a harbor facility which is exposed to chloride-rich environments, corrosion due to chloride ingress is emphasized in this research. The concrete beams can get corroded to different corrosion levels. Mass loss of the reinforcement is an important parameter, and it can help define the corrosion level, and this information can be used to …  Read more

Obesity and type 2 diabetes mellitus (T2D) are metabolic disorders often accompanied by elevated blood glucose and fatty acid levels. Chronic hyperglycemia and increased free-fatty acid (FFA) concentrations lead to the build-up of reactive oxygen species and toxic metabolites that are harmful to beta-cells and eventually cause their progressive deterioration. Both T2D and obesity are characterized by an excess deposition of triacylglycerol (TAG) and subsequent lipid droplet (LD) accumulation in adipose tissue. Perilipin-2 (PLIN2) is a ubiquitously expressed LD-associated protein that regulates TAG metabolism and LD formation. However, PLIN2 expression in the pancreas and its potential role in the pathogenesis …  Read more

Les insectes utilisent des enzymes associées aux glandes salivaires labiales ou au système digestif pour détoxifier les molécules de défense des plantes ou atténuer leurs défenses induites. Les études récentes suggèrent que l’activité de telles enzymes peut être affectée par l’alimentation à travers deux facteurs principaux : les métabolites secondaires des plantes et la qualité nutritionnelle. La manière dont différents régimes de plantes affectent l’activité enzymatique de chenilles de Spodoptera exigua (Hübner) est mal connue. C’est pourquoi l’objectif de cette étude est de comprendre la façon dont différents régimes de plantes affectent l’activité des enzymes suivantes des chenilles : le …  Read more

Breast cancer is the predominant cancer type among Canadian women, with a striking incidence rate of one in eight women during their lifetime. Transcription factors play pivotal roles in breast cancer initiation and progression. Signal transducer and activator of transcription 3 (Stat3) is a transcription factor that mediates the expression of a variety of genes in response to cytokines and growth factors. The activation of Stat3 plays key roles in cell growth, survival and apoptosis, cell migration and invasion, and inflammation. Using the conditional Stat3 knockout mouse model, our lab previously demonstrated that Stat3 deficiency can impede the metastasis of …  Read more

Pommes de terre, en raison de sa forte consommation dans le monde, peut être exploitée pour la livraison des aliments fonctionnels, en particulier pour les pauvres qui ne prend pas de suppléments. Dans cette étude, les métabolites liés à les aliments fonctionnels dans les tubercules cuits de huit génotypes de pommes de terre diploïdes (phureja de Solanum tuberosum Groupe) de Colombie ont été explorées. Les plantes ont été cultivées dans des conditions de terrain dans un design en blocs aléatoires. Un total de 24 échantillons (8 génotypes*3 répétitions) ont été utilisés dans cette étude. Les tubercules ont été récoltés, lyophilisée, …  Read more

Relaying techniques are commonly used in cooperative communication to combat channel fading impairments. Network coding is often used in such systems to improve the system performance. Polar codes have drawn much interest in recent years, because of their low decoding complexity and high performance. In this work, polar codes are employed in a multi-way selective detect-and-forward (DF) cooperative relaying system, and used as network codes. We demonstrate how systematic polar codes can be used in such a system. Next, we analyze performance when employing any binary linear block code with maximum likelihood decoding, including the pairwise error probability, diversity order …  Read more

Ce mémoire explore comment des ateliers de théâtre, en tant que méthode de recherche et « terrain », peuvent être mobilisés pour encourager la solidarité et les relations dépassant le cadre de la recherche universitaire. En m'appuyant sur des entretiens et des ateliers de théâtre organisés avec Chinatown Youth (CTY), une organisation locale qui œuvre à la protection et à la promotion du quartier chinois de Montréal grâce à la participation de jeunes adultes, j'explore comment le théâtre peut ouvrir un espace d'échange et de critique, permettant ainsi de reconsidérer et critiquer les discours dominants. Si les discours identitaires nationalistes …  Read more

In this thesis, we present the first-principle calculations of inelastic electron tunneling spectroscopy(IETS) in single molecular break junctions. In a two-probe electrode-molecule-electrode setup, density functional theory(DFT) is used for the construction of the Hamiltonian and the Keldysh non-equilibrium Green's function(NEGF) technique will be employed for determining the electron density in non-equilibrium system conditions. Total energy functional, atomic forces and Hessian matrix can be obtained in the DFT-NEGF formalism and self-consistent Born approximation(SCBA) is used to integrate the molecular vibrations (phonons) into the framework once the phonon spectra and eigenvectors are calculated from the dynamic matrix. Geometry optimization schemes will also …  Read more