McGill University Thèses et mémoires par auteur commençant par P

Misra, Arun K. (Supervisor2)  Lire la suite

The screening, biomass production of lipase-producing microorganisms from several sources, as well as the purification, characterization and utilization of the enzymatic extracts for the interesterification of butter fat were investigated. Pseudomonas fragi CRDA 323 and Aspergillus niger CBS 131.52 were considered to be good lipase producers, whereas, those from Pseudomonas putida ATCC 795 and Rhizopus oryzae ATCC 34612 as weak ones; all four microorganisms produced maximal amount of extracellular lipases by batch fermentation after three-four days of incubation in a continuously stirred tank reactor. The lipases were partially purified by ammonium sulfate precipitation and characterized with respect to pH, kinetic …  Lire la suite

Piper, Martha (Supervisor)  Lire la suite

Since physical activity is part of a healthy lifestyle, there is a lot of interest concerning the determinants of this behaviour in youth since it is tracked into adulthood. Environmental determinants belong to one subset of factors that influence physical activity. Baseline and one-year follow-up data on level of physical activity were collected in classroom questionnaires from 1264 7th grade students (56.2% of eligible students). Physical activity was assessed via an adaptation of the Weekly Activity Checklist. The effect of a ban on extracurricular activities on adolescent physical activity levels was determined. Multivariate logistic regression analyses were used to determine …  Lire la suite

Costopoulos, Andre (Supervisor2)  Lire la suite

This paper is a case study of Soviet political influences on Lithuanian archaeology. The work explores the application of central political rules of the Soviet Union to Lithuanian archaeology and analyses the consequences of these applications in the Post-Soviet period. The result of the study reveals that under Soviet policy, Lithuanian archaeologists developed a highly descriptive tradition. In Post-Soviet Lithuania, archaeologists continue to practice the descriptive tradition and rarely engage in theoretical debates. The work suggests possible explanations and solutions to the current problems in Lithuanian archaeology.  Lire la suite

Through the ages, coronary artery disease has been plaguing mankind by the millions every year. Many sudden mysterious and dramatic deaths were attributed to this disease, yet people did not know how it worked. It was only during the advent of the 20th century that medical science began to probe this mystery, especially these last 35 years. [...]  Lire la suite

Rahme, Elham (Internal/Cosupervisor2)  Lire la suite

Photochemical transformations have now been known to occur for over half a century since the time when sunlight was first used as a source of irradiation. Many reviews have been published since, covering many aspects of the subject(l-7). [...]  Lire la suite

Peu d'informations sont disponibles sur la carence en fer et l'anémie due à une carence en fer (ACF) chez les Inuits d'âge pré-scolaire. Un sondage transversales a été conduit avec 388 enfants Inuit âgés de 3 à 5 ans, dans 16 communautés du Nunavut. Des interviewers ont conduit des entrevues alimentaires et des questionnaires à propos des caractéristiques des ménages. La taille, le poids, ainsi que des marqueurs biologiques du niveau de fer et de l'exposition à Helicobacter pylori ont été mesurés. La prévalence de la carence en fer et de l'ACF a été calculée et les facteurs de risque …  Lire la suite

IMPORTANCE: Our understanding of the composites of technical expertise during spinal procedures including the insertion of pedicle screws is incomplete. Datasets generated from surgical simulation allows the quantitation of psychomotor skills, which can be analyzed using machine learning algorithms which allows a more complete understanding of surgical performance.OBJECTIVE: The primary aim of this study was to identify important features distinguishing skilled and less skilled levels of expertise during simulated pedicle screw insertion. The secondary aim was to benchmark the classification accuracy of surgical performance through the implementation of machine learning algorithms.DESIGN: Participants from four universities were recruited between July 15, …  Lire la suite

The CUX1 gene has been characterized genetically as a haploinsufficient tumour suppressor gene. Paradoxically, CUX1 overexpression is observed in the majority of human cancers and is associated with shorter patient survival. While many transcriptional targets may explain how CUX1 overexpression promotes tumour development and/or progression, the biochemical function(s) of CUX1 that explain its role in tumour suppression remain(s) to be defined. Recent studies have established a role for the p200 CUX1 protein as an auxiliary factor in DNA repair. Specifically, the CUT domains within CUX1 were found to stimulate the enzymatic activities of three enzymes of the base excision repair …  Lire la suite

Neslehova, Johanna (Supervisor1)  Lire la suite

This thesis provides a comprehensive criticism of the current models of understanding and caring for the mentally ill in a western context. I will outline the debates surrounding the conceptualization, diagnosis and treatment of mental illness. The western, psychiatric, biologically based understanding of mental illness is the dominant model of understanding and treating mental illness, despite the evidence that it encompasses an incomplete understanding of the causation and nature of mental illness. I will outline the difficulties in the creation of a cohesive definition of mental illness, including philosophical and cultural perspectives. I will examine the impact of historical, societal …  Lire la suite

Feldman, Liane S (Internal/Cosupervisor2)  Lire la suite

La polykystose rénale autosomique dominante humaine (PKRAD) est une maladie monogénique parmi les plus fréquentes héréditaire et se présente avec des kystes rénaux et autres manifestations extrarénales. La majorité des cas d'ADPKD sont causés par des mutations dans PKD1, un gène qui code pour la protéine polycystine-1 (PC1). Nous étudions plusieurs modèles de souris Pkd1 afin d'étudier le rôle que joue PC1 dans l'homéostasie et la kystogenèse rénales et extrarénales: un modèle de knockout Pkd1 murin total, Pkd1-/-, un modèle transgénique de surexpression systémique du gène de Pkd1, Pkd1TAG, un modèle transgénique du gène de Pkd1 ciblé aux reins, SBPkd1TAG, …  Lire la suite

The treatises of the German artist Albrecht Durer (1471-1528) reveal the first instances of modern means of architectural representation. These works, the Underweysung der Messung (1525) and the Vier Bucher von Menschlicher Proportion (1528), employ an unprecedented degree of graphic projection to render visual various geometrical and architectural figures. Nevertheless, Durer's obsessive interest in geometry and visualisation is not necessarily expressive of a strictly modern intentionality. Although his treatises have some continuity with the reductive techniques of contemporary practice, they were formulated in a traditional world and manifest many of its concerns. This thesis elucidates the interplay between these aspects …  Lire la suite

The present experiments were designed to examine the hypothesis that the hippocampus and caudate nucleus are parts of independent memory systems which differ in the type of memory they mediate. In experiment 1, the mnemonic functions of the hippocampus and caudate were doubly dissociated; lesions of the caudate nucleus impaired acquisition of the "habit memory" component of the 4 x 4 radial maze task, but had no effect the "cognitive memory" component of the task. Lesions of the fimbria-fornix produced the opposite behavioral dissociation. In experiment 2, lesions of the caudate nucleus produced a transient deficit in cognitive win-shift radial …  Lire la suite

Post-transcriptional mechanisms regulate the amount of protein being synthesized from messenger RNAs (mRNAs). These mechanisms include repressing mRNA translation and/or initiating mRNA destabilization, events collectively referred to as ‘silencing'. The RNA-binding protein Tristetraprolin (TTP) constitutes an important post-transcriptional regulator that binds to AU-rich elements (AREs) in the 3' untranslated regions (UTRs) of mRNAs. Examples of mRNAs targeted by TTP include pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and cancer-related mRNAs, such as c-myc and vascular endothelial growth factor (VEGF). Not surprisingly, TTP knockout mice display a hyper-inflammatory phenotype and downregulation of TTP has been observed in …  Lire la suite

L'hémojuvéline (HJV) est une protéine membranaire qui contrôle le métabolisme systémique du fer. Les mutations de HJV conduisent à l'hémochromatose juvéline, qui découle de l'absorption incontrôlée du fer de l'alimentation et des dépots de ce métal dans les cellules parenchymateuses du foie. La surcharge hépatique en fer mène progressivement à l'inflammation, la fibrose et le carcinome hépatocellulaire. Les mécanismes moléculaires responsables des dommages au foie qui sont attribuables au fer ne sont pas entièrement caractérisés. Nous avons donc étudié la contribution potentielle de l'ablation de HJV sur le fer hépatique, le métabolisme des lipides et son rôle dans la pathogénèse …  Lire la suite

Recent developments in environmental management (EM) in Trinidad and Tobago have produced several umbrella legislation and institutional reforms. Since their enactment in 1995, there are still questions about their efficacy and key issues of these are examined. A multi-variant, cross-comparison approach relates the new and existing EM strategies to recommended guidelines found in the literature and collected from local opinion. Environmental Impact Assessment (EIA) is used in tandem with EM, as it is the main tool of EM in Trinidad and Tobago. A case study of EIA application is used to assess the effectiveness of EIA and EM in Trinidad …  Lire la suite

Cere, Daniel M. (Supervisor1)  Lire la suite

Charm Jets in photoproduction have been studied in electron-proton collisions with the ZEUS detector at HERA, using an integrated luminosity of 120 pb-1. Jets were reconstructed using the longitudinally invariant kT-clustering algorithm. The dijet cross section for events containing at least one D*+/- charmed meson was measured as a function of various observables sensitive to hard scattering and the structure of the photon. The results are compared with predictions from leading-order parton-shower Monte Carlo simulations and with next-to-leading-order QCD calculations. Differential cross sections of dijets as a function of the angle between the charm jet and the proton-beam directions in …  Lire la suite

La communication intercellulaire est importante pour tous les organismes, facilitant l'échange de molécules d'une cellule à l'autre. Récemment, un groupe de nanoparticules nommées vésicules extracellulaires (VE) sont devenus d’importants médiateurs de cet échange. Les VE sont un groupe hétérogène de nanostructures membranaires sécrétées par les cellules. Les VE peuvent voyager à travers l'environnement extracellulaire et fusionner avec d’autres cellules et leur livrer leur contenu, modifiant leur comportement. Parmi les biomolécules présentes dans les VE, les ARN sont un groupe sous-étudié et leur rôle dans la communication cellule-cellule reste nébuleuse.Dans le premier chapitre de cette thèse, j'explore certaines des connaissances accumulées …  Lire la suite

Les modifications post-traductionnelles (MPT) sont des modifications chimiques covalentes des histones qui jouent un rôle clé dans la régulation de la structure de la chromatine et de l'expression des gènes. Les progrès du séquençage à haut débit ont permis de cartographier les MPT à l'échelle du génome, facilitant ainsi l'étude de la contribution de leur dérégulation, notamment par des mutations des enzymes déposant des MPTs d'histones, aux maladies et au cancer. Parmi celles-ci, la méthylation de la lysine 36 de l'histone H3 (H3K36me) est une composante épigénétique essentielle à la régulation de l'expression des gènes. Malgré son importance dans le …  Lire la suite

Avec l'avancée de la technologie, les réseaux sans fil ad hoc de capteurs prennent de l'importance dans le domaine du contrôle et de la surveillance, notamment dans les régions reculées et les environnements dangereux pour l'intervention humaine. Un exemple d'une telle application serait la surveillance et le contrôle des équipements, tels que les transformateurs et les disjoncteurs situés dans les postes de transport d'énergie. Étant donné que les réseaux de capteurs sont souvent utilisés dans des endroits inaccessibles, il est indispensable que ces réseaux puissent fonctionner pendant de longues durées. Beaucoup de travaux de recherche sont encore menées sur le …  Lire la suite

This dissertation consists of three essays in international asset pricing. The first essay develops a model where investors face barriers to foreign portfolio investment. Using the standard mean-variance framework, risk return relationships for all securities are developed. It is also shown that: (1) previous models adopting this approach are special cases of this model, and (2) all investors generally prefer complete removal of barriers over other market structures. Essay #2 empirically explores the issue of the degree of segmentation of the international capital market for risky securities. Using the 'emerging market' (EM) data base, it is shown that the international …  Lire la suite

The experimental work described in the thesis consisted of a series of tests of model footings on dry silt of various porosities. It was done from the point of view of settlement-pressure relationship. Also, one of the theories of settlement is examined, and the results of the tests are compared with that theory. The principal factors affecting the tests are pointed out, and suggestions are made to guide further studies of the subject.  Lire la suite

Characteristic features of the long atmospheric waves are discussed on the basis of spherical harmonic analysis of global weather charts for September 1957. At first, there is a discussion of the Trapezoidal and Simpson's numerical integration rules as applied to the computation of the Spherical harmonic coefficients. [...]  Lire la suite

Precup, Doina (Supervisor1)  Lire la suite

Cet article examine de manière critique les justifications éthiques des vaccinations obligatoires pour les travailleurs de la santé pendant la pandémie de Covid-19. Adoptant un cadre non-conséquentialiste, j'explore les arguments fondés sur les droits des deux côtés du débat ainsi que l'étendue et les implications du devoir de diligence des travailleurs de la santé pendant la pandémie. En fin de compte, je soutiens que les professionnels de la santé ont un devoir de diligence et que la vaccination est un moyen de remplir ce devoir. Toutefois, il ne s'agit que d'un outil parmi d'autres. Je propose donc que le devoir …  Lire la suite

La capacité réduite des personnes âgées à acquérir de nouvelles compétences motrices suggère la présence de déficits lors de la consolidation de leur mémoire. Ces déficits pourraient être causés par une atteinte des mécanismes responsables de la plasticité neuronale et nécessaires à l'acquisition de nouvelles mémoires motrices. Parmi ces mécanismes, il est possible de distinguer la potentialisation à long terme (LTP) qui est un marqueur de renforcement des synapses, un élément essentiel à la formation de la mémoire. L'objectif de ce projet est de déterminer si le niveau d'excitabilité cortical (CSE), une mesure non invasive corrélée à la LTP, peut …  Lire la suite

In the yeast Saccharomyces cerevisiae, fermentation is the most important pathway for the production of energy, even under aerobic conditions (Crabtree effect). With low concentrations of glucose, ethanol produced during fermentation is used for the production of this sugar. This process relies on a shift to a respiratory mode. This change in metabolism requires a massive reprogramming of gene expression. For example, increased expression of genes for gluconeogenesis and the glyoxylate cycle is observed upon a shift to ethanol. This process is controlled in part by the transcriptional regulators Cat8, Sip4, Rds2, and Ert1 that belong to the family of …  Lire la suite

Notre capacité à naviguer dans le monde qui nous entoure requière que le cerveau maintienne une représentation précise de nos déplacements. Pour ce faire, les informations vestibulaires issues des mouvements angulaires et linéaires de la tête sont relayées via les afférents vestibulaires contenus dans le nerf crânien VIII jusqu'au noyau vestibulaire situé dans le tronc cérébral. Le signal vestibulaire contribue aux reflexes de stabilisation de la posture et du regard grâce aux projections vers la moelle épinière ainsi celles vers les neurones oculomoteurs. De plus, le signal vestibulaire contribue aux processus corticaux de l'orientation spatiale et de la perception de …  Lire la suite

Adaptive processes were comparatively examined in elementary school children experiencing the postdivorce process and their peers from intact homes using a developmental conceptualization of coping with a family systems perspective. Children's psycho-social coping resources were assessed using the Self Perception Profile for Children, Coping Inventory, Children's Beliefs About Parental Divorce Scale, and Family Environment Scale. Children's global and specific coping efforts were measured using the Child Behavior Checklist and the Schoolagers' Coping Strategies Inventory, respectively. Parental coping efforts were examined using the Ways of Coping Questionnaire. Children from disrupted families were found to have diminished psycho-social coping resources (self-efficacy, self-esteem, …  Lire la suite

This study investigates the influence of family configuration and environment on children's adjustment. Half of the seventy-six elementary school age participants were from families where separation and divorce had occurred, and the remaining children were from intact families. Children's self-efficacy was assessed using the Harter Self Perception Profile (Harter, 1985). Parental perceptions of children's behavior and specific family environmental characteristics were obtained by employing the Child Behavior Checklist (Achenbach & Edelbrock, 1983), Family Environment Scale (Moos & Moos, 1986) and Overt-Hostility Scale (O'Leary & Porter, 1980). Children from homes where parental divorce had previously occurred were compared to children from …  Lire la suite

La liaison de l'Hormone de Croissance humaine (GH) à son récepteur (GHR) sur les cellules cibles conduit à l'activation de trois voies de signalisation intracellulaires majeures: JAK2/STAT5, PI3K/AKT et ERK/MAPK. Cependant, en plus de la forme intégrale (FL) du GHR, il existe deux isoformes tronquées (Tr) du GHR, GHR1-279 et GHR1-277 qui ont perdu la majorité de leur domaine intracellulaire dû à l'épissage alternatif de l'ARNm du GHR. Alors que les études in vitro et in vivo suggèrent que les isoformes tronqués du GHR auraient un effet de dominant négatif sur le GHR FL en formant des hétérodimères stables, peu …  Lire la suite

The Epoch of Reionization (EoR) is the period of our Universe's history where the neutral hydrogen in the Inter Galactic Medium (IGM) is ionized. Despite its importance to our understanding of the Universe, it remains observationally unconstrained and poorly understood. One method to directly observe the EoR is to measure the 21cm photons emitted by the hyperfine transition of neutral hydrogen when the electron flips its spin relative to the atomic nucleus. Mapping the 21cm line in the IGM as a function of redshift can directly probe the EoR. In this thesis we consider two methods to measure the 21cm …  Lire la suite

Cosmic strings are linear concentrations of trapped energy produced throughsymmetry breaking processes of eld theory models. Though they can onlycontribute a maxiumum of 10 percent to structure formation they have beenshown to arise as a generic consequence of many inationary setups of supergravitymodels. In addition they provide another avenue to probe physicsbeyond the "Standard Model". Cosmic strings can intersect producing stringloops. These topological defects are formed at early times creating largeamounts of accretion and thus lead to large amounts of baryon overdensities.These baryonic overdensities of hydrogen lead to a unique 21cm signature.We focus on cosmic string loops in addition to …  Lire la suite

Since the end of the Cold War, considerable attention has been paid to "ethnic" or "identitive" conflicts. Some scholars argue that these conflicts tend to draw in 'kin' states who support the belligerent(s) with whom they share identitive affinities. This thesis examines such involvement, based on identitive affinities, in ethnopolitical conflicts. In particular, it analyses the pattern of involvement of one country: Iran. Specifically, it looks at Iran's policy towards five conflicts: Afghanistan, Nagorno-Karabakh, Iraq, South Lebanon and the Israeli-Palestinian conflict. This thesis argues that kinship is only a permissive cause of involvement while the presence and scope of involvement …  Lire la suite

In 1939 Rossby published a theory of wave motion in the atmosphere which formed the basis of later work on this subject. One year later Haurwitz extended the theory to waves of finite lateral extent and to wave motion on a spherical earth. During the next ten years various investigators, including Rossby, developed the theory further, attempting to approximate more closely the baroclinic nature of the atmosphere. [...]  Lire la suite

The bipolar budding pattern of a/a Saccharomyces cerevisiae cells appears to depend on persistent spatial markers. Genetic analysis reported here indicates that BUD8 and BUD9 potentially encode components of the markers at the distal and proximal poles, respectively. Mutants deleted for BUD8 or BUD9 bud exclusively from the proximal and distal poles, respectively, and the double-mutant phenotype suggests that the bipolar budding pathway has been totally disabled. Moreover, overexpression of these genes can cause either an increased bias for budding at the distal (BUD8) or proximal (BUD9) pole or a randomization of bud position, depending on the level of expression. …  Lire la suite

Elderly who require community support services to remain autonomous are at high risk of malnutrition. A 12-week intervention was undertaken to test the feasibility of nutritional supplementation to improve the nutritional status of subjects with an excessive involuntary weight loss or a body mass index (BMI=kg/m2) <20. Fourteen subjects aged 65-90 (mean 78±13) were provided with a 500 kcal nutrient dense supplement. BMI was low in 11 subjects (14.3-18.9); those remaining had lost weight. The mean overall weight gain among all subjects was 1.3 kg, however, underweight (BMI<20) subjects gained 2.1 kg (p<0.005). The mean caloric intake was 397 kcal/day …  Lire la suite

La chute and the six short stories of L'exil et le royaume by Albert Camus constitute a sort of renewal of the author's art and thought. Having left the absurd behind, having experienced revolt, Camus now brings to the forefront a theme that underlies all his work, the essential solitude of human beings. This thesis attempts to illustrate the various manifestations of this theme in the last works of the Algerian writer in order to underline the remarkable cohesion of these formally dissimilar texts.  Lire la suite