McGill University Thèses et mémoires par auteur commençant par Ç

Various surgical options exist to correct pathologies of the aortic valve, including mechanical or biological valve implantation, reconstruction of the native vessels, and a combination of the two. Additionally, finite-element analysis and, to some extent, fluid-structure interaction (FSI) analyses have been used in the past to analyze how these procedures may affect various engineering metrics such as tissue stresses and opening and closing dynamics of the valves. In this work, a similar type of model and analysis is performed, however, in addition to modeling the actions of the aortic valve, coronary flows are also considered. By incorporating these vessels, it …  Lire la suite

The limitations of routine chemical analysis and the impracticability of digestion trials with large animals as indices of nutritive value of pasture grass are discussed. In view of this situation the use of rabbits as pilot animals for farm ruminants is suggested. A trial, comparing the digestive powers of steers and rabbits on pasture grass, is reported. The results show that in general rabbits do not digest the grass to the same extent as steers, the greatest difference showing in the crude fibre fraction. Nevertheless because of their uniform response in digestibility of pasture herbage and the ease with which …  Lire la suite

Verticillium wilt is often the cause of serious losses in potatoes in Eastern Canada and Northern United States. It is of minor importance in field tomatoes except in California and Utah. The disease is not uncommon in greenhouse tomatoes in North America and in Europe. [...]  Lire la suite

Knowledge o£ the importance or a nutritional factor in the etiology of rickets may be said to date from the pioneer work of Mellanby in 1919. The therapeutic value of fish oils tor rickets. although recognized for centuries~ was shown to be due to a factor quite distinct from vitamin A. The exact identity of the factor. however~ was obscured for some time when it was found that sunlight and ultraviolet irradiation also had curative effects. In 1926 accidental discovery of the role of cholesterol and related sterols made it possible to conclude that sunlight and cod liver oil cure …  Lire la suite

Norget, Kristin (Supervisor1)  Lire la suite

This thesis presents the design and validation of a method for digitally reconstructing white matter fibre tracts in vivo using magnetic resonance imaging (MRI). The technique uses diffusion weighted MRI to estimate a likelihood distribution function for the fibre direction(s) in each imaging voxel, and subsequently infers connectivity from any point in the central nervous system to another. The fibre tracking algorithm addresses issues that can confound fibre tract reconstruction, such as imaging noise, subvoxel partial volume averaging of fibre directions, and problems with the estimate of the diffusion probability density function (pdf). It can take as input a diffusion …  Lire la suite

Magnetic resonance imaging (MRI) can be used to image diffusion in liquids, such as water in brain structures. Molecular diffusion can be isotropic or anisotropic, depending on the fluid's environment, and can therefore be characterized by a scalar, D, or by a tensor, D, in the respective cases. For anisotropic environments, the eigenvector of D corresponding to the largest eigenvalue indicates the preferred direction of diffusion. This thesis describes the design and implementation of diffusion tensor imaging on a clinical MRI system. An acquisition sequence was designed and post-processing software developed to create diffusion trace images, scalar anisotropy maps, and …  Lire la suite

This thesis explores the symbolic and sensory dimensions of local carnival celebrations in the southern French village of Prats de Mollo. During carnival an ideal, locally-rooted Prateen community is articulated and experienced by participants through repeated acts of commensality and physical displays of friendship that are intensified by carnival's sensual indulgences and ritual interactions in public space. The aesthetic dimensions of carnival festivities in Prats de Mollo thus reflect an enduring desire for experiences of belonging that are deeply implicated in and informed by an affective relationship between self, community, and place, but that are at the same time in …  Lire la suite

The nature of closure is a major topic in modern theoretical discourse, as theorists recognize that the type of closure in a composition has an impact on its structure, direction, and overall character. The music of Johannes Brahms (1833-97) attracts great interest due to his deliberate and complex manipulations of the harmonic, formal, and melodic idioms associated with tonal music. Through utilizing both syntactic and semantic devices to close his pieces, Brahms creates intricate endings which potentially confirm or deny the listener's expectation that a piece will come to a complete and satisfying close. In this thesis, I explore Brahms's …  Lire la suite

Entamoeba histolytica is a protozoan parasite and the causative agent of amoebiasis. While infection is associated with suppression of cell-mediated, immunity, drug-cured patients are resistant to reinvasion by amoebae. Macrophages are the principal effector cells in host defence against E. histolytica via production of nitric oxide which is cytotoxic for the parasite. The objective of this study was to determine the T cell cytokine responses associated with host defence against E. histolytica . A mixed Th1/Th2 (Th0) response predominated at days 5--10 of amoebic liver abscess development in gerbils, as indicated by spleen and hepatic lymph node cell IL-2 (Th1 …  Lire la suite

Gerbils, experimentally infected with Giardia lamblia trophozoites, had trophozoites and encysting trophozoites in all 3 equal sections of the small intestine and in the colon at necropsy. Cysts were found in the second and third sections of the small intestine and in the colon. WB strain derived trophozoites (WB, D1, WB-C6, and V1) differed in levels of encystation in vitro but not in gerbils. Passage in gerbils increased the in vitro encystation levels of WB and D1 but decreased that of WB-C6 and V1. No differences were found in the total protein profiles or isoenzyme patterns of these G. lamblia …  Lire la suite

The Klondike District of Central Yukon Territory around Dawson City is particularly advantageous for the study of the sequence of the Pleistocene epoch because it was never glaciated and therefore has never lost its fossiliferous superficial deposits. This paper presents a pollen diagram from a Sphagnum peat bed, which was the youngest deposit discovered, and pollen floras from different ages back to the Pliocene. The peat bed flora shows fairly steady climatic conditions little different from the present; the Pliocene flora shows a distinctly warmer climate; and all the others appear to show colder climates. The paper also presents a …  Lire la suite

The retrovirus XMRV (xenotropic murine leukemia virus-related virus) was first identified in association with Chronic Fatigue Syndrome in 2009. Following the publication of this research there erupted a major controversy within the scientific literature over the status of the XMRV virus, that wound to a close in 2012 with the editorial retraction of the original research and the conclusion that the virus was a laboratory artefact. This paper maps the dynamics of the XMRV-CFS controversy, and how the status of the virus itself changed over the course thereof. The question of the "reality" of both the virus and its putative …  Lire la suite

Les jeux du genre roguelike partagent un ensemble commun de systèmes de jeu de base. Ces systèmes sont souvent complexes et impliquent une randomisation qui peut être un obstacle à l'automatisation. En particulier, l'exploration de niveaux générés aléatoirement est un mécanisme critique et pourtant souvent répétitif, tandis que le combat contre les monstres nécessite généralement une stratégie méticuleuse, ce qui constitue également un défi pour l'automatisation. Cette thèse présente une approche pour les systèmes d'exploration et de combat dans le jeu prototypique roguelike, NetHack. Pour l'exploration, nous présentons un algorithme qui utilise des occupancy maps provenant du domaine de la …  Lire la suite

The Tomato - Lycopersicon esculentum -,a member of the Solanaceae family, is one of the most useful and interesting of all horticulture plants. It ranks next to the potato and the sweet potato in total value on this continent. It heads the list among the perishable vegetables as well as ranking first as a canning crop. If "variety is the spice of life” then we owe this crop a great deal for according to Carver (1918) there are 115 ways of preparing it for the table.  Lire la suite

We investigate the nonlinear development of a forced wave packet in the presence of a critical layer in a shear flow. Two different geophysical flows are considered: vertically propagating internal gravity wave packets in a stratified shear flow and Rossby wave packets propagating toward the equator in a zonal flow. Most previous analyses of these phenomena have dealt with spatially periodic, monochromatic waves. These studies observed that, in the initial linear stages, the disturbance is absorbed at the critical layer, but subsequently, the linear theory breaks down and nonlinear phenomena such as wave breaking and reflection result. For a more …  Lire la suite

Moslowe (Supervisor)  Lire la suite

Introduction. Durant une procédure causant un dommage tissulaire, le contact de peau entre un bébé prématuré et sa mère diminue les réactions de douleur de celui-ci et l'aide à récupérer plus rapidement au niveau physiologique. Aucune étude n'a examiné si le contact ou la présence d'un jumeau prématuré pourrait avoir un effet réconfortant sur son jumeau. Objectif. Lors d'une procédure causant un dommage tissulaire (ponction au talon), comparer l'effet réconfortant du partage de lit entre jumeaux, le co-bedding, sur la réponse à la douleur en contrastant les bébés qui sont en co-bedding avec ceux qui ne le sont pas. Méthodes. …  Lire la suite

This dissertation examines the increase in youth cultural production and youth involvement in the creative industries. The project researches structures that youth encounter, including federal, provinicial, and municipal policies, as they attempt to create small-scale and self-generated careers for themselves in the creative industries, and also looks at initiaves that youth create themselves, including artist networks, in order to facilitate their entry in the realm of work in the creative industries. After examining Canadian federal cultural policy in comparison to British cultural policy and provincial educational policy in Québec, I turn to a series of case studies concerning local, national, …  Lire la suite

The origins of two jurisdictional issues in Canadian correctional law have long puzzled experts. First, why is sentence length of two years set as the dividing line between prison and penitentiary custody? Second, why are prisons under provincial authority and penitentiaries under federal authority? This thesis traces the origins of both rules and posits reasons for their genesis. Evidence is presented to document that the two-year "rule" first arose in England in 1706 as a cap on the length of sentences of imprisonment. Its subsequent application in British North America where it was transformed into a jurisdictional "split" was not …  Lire la suite

Optical isomers (enantiomers) are chiral molecules, which are commonly used in the drug and food industry. The major difference between the two D and L enantiomers is the spatial arrangement of atoms around a central carbon. During normal chemical synthesis a mixture of L and D enantiomers are formed in equally proportion (racemic mixture). Currently, the most common technique for resolution of a racemic mixture is chromatography using chiral specific columns. However, this method is limited in scale and is rather costly. This work studies the possibility for the resolution of racemic glutamic acid by crystallization. Since the solubility of …  Lire la suite

"Demographic changes in the last seventy-five years have resulted in the increase of those over sixty-five In both numbers and in the proportion of the total population which they constitute. Numerous problems in areas such as financial security, health care and use of leisure time have arisen consequently. Although much research has been conducted in recent years on various aspects of aging, existing knowledge is not integrated into one theory of aging. It was speculated that the development of such a comprehensive framework of viewing aging, integrating the diverse research findings and theories of aging, would facilitate understanding of the …  Lire la suite

Placebo effects constitute context-dependent medical phenomena, and exemplify the link between psychosocial factors and physiological processes. By surveying medical students (Study 1) and practicing physicians (Study 2), the present thesis explores the knowledge and attitudes towards the role of placebos, and their related effects, in the clinic. In addition, this thesis addresses the ethics of deception in clinical practice (Commentary Response 1). Findings from Study 1 demonstrate that medical students are unaware of many non-drug effects that influence response to treatment, and yet, approximately 40% reported that they would prescribe a placebo in clinical practice. Such placebo science knowledge is …  Lire la suite

Because they occur in the contentious public arena that surrounds abortion, the development, introduction, and use of RU486, also known as "the abortion pill," provide a valuable opportunity for understanding how sociotechnical analysis can contribute ta the study of communication phenomena. The essay presents a preliminary case study of RU486 in Canada, drawing on an earlier U.S. study performed by Adele Clarke and Therese Montini (1993), supplemented by Bruno Latour's actor network theory and Ruth Schwartz Cowan's framework for linking gender, technology and public policy. [...]  Lire la suite

One of the elements commonly seen in cancer is the change in methylation status of the genome. These aberrations in methylation appear to be critical for the neoplastic phenotype and manifest as changes to gene expression of oncogenes and tumour suppressors. In addition to epigenetic alterations, the proteins involved in maintaining the plastic methylation status of the genome, DNA methyltransferases and demethylases, also show methylation-independent protein-protein interactions that have effects on cell cycle progression and proliferation. As changes in gene expression and mitotic regulation are seminal elements of cancer, and because several methylated DNA binding proteins show differential expression in …  Lire la suite

There are four principal sources of random fluctuation, or noise, arising in amplifier circuits. They are: "shot effect" and "flicker effect" in vacuum tubes, and "thermal noise" and "Bernamont noise" in resistors. [...]  Lire la suite

Experiments involving the random insertion of foreign DNA constructs into the genome have frequently had unanticipated but informative consequences. In the Tg4 line of transgenic mice, an hsp68-lacZ transgene caused an insertional mutation of the dystonia musculorum (dt) locus. In the same line, the transgene gained an ectopic expression pattern in the neural tube floor plate. The co-occurence of these events suggested that the dt phenotype of postnatal sensory neuropathy might arise from a primary defect expressed in floor plate cells. To test this hypothesis, the cellular target of the dt mutation was determined by analyzing $dt/dt leftrightarrow +/+$ chimeras, …  Lire la suite

Regional economic disparities are a widely noted characteristic of the Canadian economy. This thesis examines regional disparities in terms of wages and labour productivity in the manufacturing sector. Regional disparities are analysed along three dimensions: provinces, rural/urban areas and industrial structure. Various competing theories are discussed and compared to the findings. Shift-share based decomposition analyses the magnitude and pattern of disparity and controls for industrial structure. Weighted regression is used to combine provincial and rural/urban effects. The findings support theories that emphasize provinces as units of analysis. The rural/urban results gave qualified support to urban theory. Accounting for industrial structure …  Lire la suite

Machine learning models are vulnerable to adversarial attacks. One approach to addressing this vulnerability is certification, which focuses on models that are guaranteed to be robust for a given perturbation size. A drawback of recent certified models is that they are stochastic: they require multiple computationally expensive model evaluations with random noise added to a given input. In our work, we present a deterministic certification approach which results in a certifiably robust model. This approach is based on an equivalence between training with a particular regularized loss, and the expected values of Gaussian averages. The derivation of our proposed loss …  Lire la suite

The proliferation of large digital audio collections has motivated recent research on content-based music information retrieval. One of the primary goals of this research is to develop new systems for searching, browsing, and retrieving music. Since tonality is a primary characteristic in Western music, the ability to detect the key of an audio source would be a valuable asset for such systems as well as numerous other applications.A typical audio key finding model is comprised of two main elements: feature extraction and key classification. Feature extraction utilizes signal processing techniques in order to obtain a set of data from the …  Lire la suite

This thesis focuses on the representation of physical violence in the first Romantic French dramas of the 19th century. Before 1829, the Classic movement forbade spectacles of violence in the major theatres. However, with the production of the first Romantic play, Henri III et sa cour, the stage was transformed into a space of murder, physical brutality and suicide. In this study, we will interrogate the reasons for which violent acts reappear on the French stage. The influence of the guillotine will be examined as well as the sublime and grotesque nature of murder. The theories of Christine Marcandier-Colard, which …  Lire la suite

Low plasma high-density lipoprotein cholesterol (HDL-C) is strongly associated with an increased risk of cardiovascular disease. In the following studies we investigated two key functions of HDL: as an acceptor of cholesterol efflux, and as a vasodilatory agent through endothelial nitric oxide stimulation. We investigated the functionality of HDL particles by measuring the ABCA1-dependent cholesterol efflux capacity of apoB-depleted plasma isolated from 16 subjects of French Canadian descent with a genetically defined HDL deficiency (Familial HDL Deficiency –FHD), selected for a HDL-C < 5th percentile. Additionally, we examined the endothelial nitric oxide induction capacity of HDL isolated from 16 patients …  Lire la suite

The performance of a new horizontal retort (Steriflow Standard 1-Basket Model, Barriquand, Paris, France) was evaluated on the basis of temperature, heat and lethality distribution. Time-temperature data for these studies were obtained from bare thermocouples (type T), and rectangular bricks fabricated from Teflon$ sp{ rm TM}$ and Lexan$ sp{ rm TM}$ with thermocouples positioned at their geometrical centres. The effect of entrapped air on processing parameters for bricks packaged in retort pouches was determined using silicone rubber bricks (10 x 14.5 x 2 cm), containing 5 thermocouples with their junctions positioned from the geometrical centre to near the top surface. …  Lire la suite

A growing literature has reported a significant reduction in pain sensitivity among hypertensioe animals and humans. One of the key questions about this finding is whether a reduced sensitivity to pain can be observed in normotensive individuals who go on to develop high blood pressure. Blood pressure was re-assessed in one hundred and fifteen 19 year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Analyses indicated that information regarding pain sensitivity improved prediction of changes in blood pressure beyond that afforded by differences in blood pressure at age 14, parental …  Lire la suite

Progress in the art of cooking wood by the sulphite process for the production of cellulose pulp for papermaking and similar uses has been attained chiefly by empirical experience.Very little advance has been made toward the scientific explanation of the mechanism of the main reaction, that between the solution of sulphur dioxide and the lignin of the wood whereby the latter is dissolved. [...]  Lire la suite

Les hommes et les femmes politiques ont tendance à être traités différemment par les médias. Ces différences sont subtiles et moins subtiles (Kahn, 1994; Sreberny-Mohammadi and Ross, 1996; Gidengil and Everitt, 1999, 2000, 2003b; Uscinski and Goren, 2011). Étant donnée que 'l’homme' est la norme dans la vie politique, les rapports politiques ont tendance à être encadrés dans un récit masculin, et ainsi le comportement de la femme est dénaturé (Sreberny-Mohammadi and Ross, 1996). Une manière subtile dans laquelle les journalistes couvrent différemment les hommes et les femmes politiques constitue ce que Sreberny-Mohammadi et Ross (1996) appellent la médiation sexuée. …  Lire la suite

Les protéines G hétérotrimériques sont composées de trois sous-unités : α et le dimère βγ. Elles sont localisées à la surface des cellules et transmettent les signaux reçus par les récepteurs couplés aux protéines G (RCPG) aux différents effecteurs intracellulaires. Cette fonction des protéines G fut relativement bien étudiée durant les dernières décennies. Toutefois, de récents travaux ont permis de découvrir que les protéines G sont aussi localisées à l’intérieur du noyau des cellules et qu’elles peuvent interagir avec certains facteurs de transcription. Afin de déterminer les principales fonctions de ces protéines G nucléaires, nous avons établi un criblage des …  Lire la suite

Biotin is a water soluble vitamin that is mainly used as a cofactor in carboxylation reactions by a class of enzyme known as biotin-dependent carboxylases. In order to act as a cofactor, the biotin molecule has to be covalently attached to a lysine residue by an enzyme called holocarboxylase synthetase (HCS). Inherited deficiency of the biotin-dependent propionyl-CoA carboxylase (PCC) results in the inborn error of metabolism propionic acidemia. Mutations in either the alpha (PCCA gene) or beta (PCCB gene) subunit of the enzyme have been shown to cause propionic acidemia. Mutation analysis of the PCCB gene have revealed several mutations. …  Lire la suite

Les inhibiteurs du cotransporteur sodium-glucose 2 (SGLT2i) ont été développés pour traiter le diabète de type 2 en inhibant la réabsorption rénale du glucose. Cependant, des essais cliniques ont démontré qu'ils procurent également des avantages cardioprotecteurs considérables bien au-delà du contrôle glycémique. En effet, le traitement par SGLT2i (et en particulier l'empagliflozine (EMPA ; Jardiance®)) entraîne des réductions significatives du taux d'événements cardiovasculaires majeurs tel que l'insuffisance cardiaque. Il a été démontré que la fonction des cellules endothéliales (CEs) change avec l’EMPA in vitro et in vivo grâce à une meilleure régulation de la vasorelaxation et de la réponse inflammatoire. …  Lire la suite

This study examines the relative contribution of algae and vascular plant litter to the food chains of freshwater marshes. Twelve enclosures (5 m diam.) were deployed in a nutrient-poor marsh of the Interlake region of Manitoba. Algae levels in six of the enclosures were increased by fertilizing the water column. In addition, the hardstem bulrush (Scirpus lacustris glaucus (Sm.) Hartm) litter present was replaced with a non-nutritive artificial substrate in half of the fertilized and unfertilized enclosures. Fertilization did not affect the dry weight loss of bulrush litter, but N and P concentrations were higher in the decomposing litter of …  Lire la suite

In 1892, in one of his characteristic attacks, Arthur Buies denounced the "deplorable" style of certain young French-Canadian writers of the day. The "jeunes barbares", as he called them, published in small magazines such as Le Recueil litteraire and L'Echo des jeunes, and were strongly influenced by French fin-de-siecle writing (the decadent and Symbolist schools in particular). The creation of the Ecole litteraire de Montreal in 1895 can be seen as a continuation of these varied literary endeavours. Quite aware of the criticisms leveled at young writers by Buies and others, the members of the Ecole viewed their association as …  Lire la suite

For Milan Kundera, the question of identity is one of the essential questions around which a novel is constructed. The novelist attempts to define the issue by exploring the existential themes that are tied to it. These themes are examined from different angles with the aid of what the author calls "motifs". Our study is centered on one of those motifs, that of the mirror, through which the author explores the "enigma of the ego". The typological analysis of this motif in Kundera's ten novels brings out in the characters two fundamental attitudes with regard to their identity. The first …  Lire la suite

Ricard, François (Supervisor)  Lire la suite