McGill University Thèses et mémoires par auteur commençant par O

Harrington, Rebecca (Supervisor2)  Lire la suite

This study examines how income, household division of power and maternal decision-making ability influence dietary intake and child morbidity. A sample of 154 households with children between one and three years was drawn from six villages in Busia District, western Kenya. Information on household and maternal characteristics, morbidity, dietary intake and anthropometry was gathered between July and November 1988. Household headship was found to have no significant or direct influence on children's nutritional status. Total income was higher in female-headed households. While women in male-headed households had greater financial responsibility for household maintenance, female heads of household assumed more farming …  Lire la suite

Receveur, Olivier (Supervisor)  Lire la suite

In 1900, Gomberg (32) demonstrated that hexaphenylethane dissociates symmetrically in solution into two electrically neutral triphenylmethyl fragments, each possessing a trivalent carbon atom. Ever since this discovery, the investigation of similar free radicals containing unpaired electrons has played an increasingly important part in the formal development of chemical kinetics and especially in the elucidation of complex reaction mechanisms. Prior to the suggestion that free alkyl radicals might be involved in the mechanisms of thermal and photochemical reactions of simple organic molecules, the role of free atoms in chemical mechanisms was firmly established.  Lire la suite

The Canagagigue Creek watershed, located in the Grand River Basin, is one of the fastest developing areas in Ontario. The watershed hydrology has changed considerably due to the increased anthropogenic activities, producing frequent floods and droughts as well as water quality problems. MIKE SHE, a watershed-scale model, was used to simulate surface runoff from the Canagagigue Creek watershed. Various management scenarios affecting the surface hydrology were also evaluated. The model was calibrated for four years (1994-95 to 1997-98) and validated for another four years (1990-91 to 19931-94). For the calibration period, the correlation between the observed and simulated daily runoff …  Lire la suite

The acceleration transients and the asymptotic stability of the balanced 3-phase induction motor operating from a balanced single frequency voltage supply have been investigated by a combination of numerical techniques and analytical methods. A critical review is given for the various reference frame formulations of the induction motor dynamics and the efficiency of the methods for solving the dynamic equations has been assessed. The modal approach is presented as a comprehensive framework around which the numerical results are systematically organized and such disparate subjects as acceleration transients, asymptotic stability and nonsimultaneous switching are unified. Detailed attention is given to the …  Lire la suite

Plasmodium falciparum is an obligate parasite that causes the most severe form of malaria in humans and several aspects of the immunopathology of this deadly disease remain unknown. As such, malaria prevention, control and elimination strategies are impeded. A new aspect of the parasites biology has come to light in recent research which involves the release of extracellular vesicles (EVs) from P. falciparum-infected red blood cells (RBCs). EVs are small membrane bound particles that contain functional biomolecular cargo and serve as a means of communication between and within cell populations. This biomolecular cargo is heterogenous, and largely depends on the …  Lire la suite

Lucas, A. (Supervisor)  Lire la suite

Au début de la période de lactation, les rattes allaitantes réagissent différemment aux agents stressants selon l'ampleur de l'impact de ceux-ci sur la sécurité de leur portée. Nous constatons une hyporéactivité au stress uniquement en l'absence des ratons ou en présence d'un facteur peu menaçant. Nous formulons l'hypothèse que les changements de l'activité du cortex préfrontal médian (CPFm) et de ses projections indirectes vers le noyau paraventriculaire de l'hypothalamus qui contrôle la reponse au stress lors de la lactation peuvent en être la cause. Nous avons étudié si la réaction au stress du système neuro-endocrinien, la morphologie du CPFm et …  Lire la suite

Purpose: To explore differences in dietary behaviours, energy and macronutrient intake among individuals who had regained or maintained weight loss five or more years after bariatric surgery. Methods: Twenty seven subjects that underwent bariatric surgery on average 12.1±3.7 years earlier were contacted. Dietary assessment was performed using three-day food records. Daily energy intake (kcal), protein (g), carbohydrate (g), fat (g), and alcohol intake (g) were computed using the ESHA’s Food Processor™. Participants were classified by percent weight loss, maintainers (≥38%) and regainers (≤30%). We also explored differences between currently obese (BMI ≥ 30kg/m2) and non-obese individuals (BMI < 30kg/m2). Results: …  Lire la suite

Background. This thesis explores the link between travel and deep venous thrombosis (DVT). While it is biologically plausible that prolonged travel is an independent risk factor for venous thromboembolic disease (VTE), epidemiological data to date are conflicting. Aim. To determine whether there is a independent association between travel and DVT. Methods. This was a multi-center case control study. Consecutive patients presenting to the vascular laboratory with clinically suspected DVT were eligible to participate. Cases were patients with confirmed DVT; controls were patients who had DVT ruled out. Travel history and clinical characteristics were determined though standardized interviewer-administered questionnaire. Genetic testing …  Lire la suite

The purpose of this study was two-fold: (1) to examine the relationship between the amount of airway smooth muscle and the airway responsiveness to inhaled aerosolized methacholine (MCh) in guinea pigs, and (2) to characterize the distribution of airway narrowing following MCh. In summary: (1) the quantity of airway smooth muscle (ASM) does not appear to determine differences in maximal bronchoconstriction among normal guinea pigs; the lack of a correlation between responsiveness and amount of ASM may be explained by the heterogenous distribution of bronchoconstriction among the airways studied or the modality of challenge; (2) the sensitivity to MCh appears …  Lire la suite

Il existe de nombreuses mesures statistiques de corrélation, tels que le Pearson coefficient de corrélation des variables aléatoires, le chi-carré pour les variables aléatoires discrètes et, finalement, l'information mutuelle. La plupart de ces mesures sont symétriques et ne pas permettre la détection d'influence. Nous proposons une nouvelle mesure de l'information-théorique dont la valeur indique la direction de le dépendence fonctionnelle. La mesure algorithme de calcul est effectué sur la valeur réelle de données quantifiées en bacs. Cette quantification est une fondation de l'algorithme proposé, car elle informe à la fois la signification statistique entre les variables et la force de …  Lire la suite

Flotation is a widely used mineral separation technique that relies on several components functioning at the optimum conditions in order to achieve a well-tuned integrated system. The recovery of mineral particles is mainly attributed to the bubbles generated and by rule the smaller the bubbles the more surface area available for the transport of mineral particles to the froth zone. The use of surfactants such as frothers aid in the preservation of small bubbles that are generated in a flotation machine. This function is accredited to their coalescence prevention characteristics based on their chemical and structural compositions. Additionally, research shows …  Lire la suite

La gestion communautaire des ressources naturelles (GCRN) a fait l'objet d'une grande attention dans le monde entier et est maintenant considérée comme une approche participative qui concilie la gestion des ressources et le bien-être socio-économique des communautés locales. Au Ghana, le Community Resource Management Areas (CREMA) a été institué comme un modèle de GCRN qui cherche à promouvoir la gestion durable des ressources fauniques en dehors des zones protégées en encourageant la participation des communautés locales à la gestion des ressources par le biais de la dévolution des droits de gestion des ressources. Dans le parc national de Mole, le …  Lire la suite

Polyphenoloxidases (EC 1.10.3.1) (PPO) were extracted from the skin layer between the muscle and exoskeleton, of lobster (Homarus americanus) by the successive steps of (NH$ sb4) sb2$SO$ sb4$ fractionation, ion-exchange chromatography and isoelectric focusing. The lobster 'PPO-fraction' recovered by the 40-80% (NH$ sb4) sb2$SO$ sb4$ fractionation step was found to exist in the inactive precursor form which required trypsin for activation and was inhibited by polyvinyl pyrrolidone (PVP). A comparative study of the lobster 'PPO-fraction' and the commercial tyrosinase from mushroom (EC 1.14.18.1) indicated that the two enzymes were similar with respect to substrate specificity, response to pH and selected …  Lire la suite

Goad, Heather (Supervisor2)  Lire la suite

Nandi, Arijit (Supervisor2)  Lire la suite

Kalan, Amir (Supervisor2)  Lire la suite

Digital platforms have emerged as a central focus of digital innovation in the IT industry, with many of today’s biggest and fastest growing firms all operating platform businesses. In the so-called platform revolution, however, we are currently limited in our understanding of how social factors influence the generative mechanisms by which platforms evolve to dominate traditional businesses. In three essays, this dissertation makes progress toward deepening understanding of digital platforms as new organizing forms and their pathways to generative or disruptive performance. Essay 1 examines how organizational rules, norms, routines and practices embedded in social and structural properties give different …  Lire la suite

Chudasama, Yogita (Internal/Supervisor)  Lire la suite

Khadra, Anmar (Supervisor1)  Lire la suite

Nodal, a morphogen of TGF-β superfamily, is indispensable in early embryonic development. Components of the Nodal signaling pathway have recently been shown to be implicated in mammalian reproduction. Nodal is expressed in the mouse uterus during pregnancy. Uterine-specific Nodal knockout female mice exhibit severe subfertility, placental malformations, IUGR and preterm birth; insinuating Nodal's essential role in the successful establishment, maintenance and termination of pregnancy. To further understand the molecular mechanisms through which Nodal modulates these events, we aimed to characterize the spatiotemporal distribution of Nodal signaling components and investigate the effects of loss of maternal Nodal during pre-implantation and early …  Lire la suite

In the wake of the abolition of the Caliphate in the Islamic world with the advent of the Mongols in the 13th century, Islamic scholarship paradoxically flourished, especially in the Shi'i milieu. This era marked a renaissance which has influenced the course of Shii thought ever since. Through its major thinkers, i.e. Ibn Sa'ada, 'Ali ibn Sulayman and Maytham, the school of Bahrain contributed vigorously to this renaissance by integrating philosophy and mysticism into Shi'ism. Yet, the writings of this school are barely known to modern scholarship and many are still in manuscript form. Drawing upon both published and unpublished …  Lire la suite

Previous investigations of a single family aggregate with developmental language impairment have suggested that the impaired members are disabled in their ability to use anaphoric pronouns. The present thesis sought to investigate further the use of anaphoric reference in this family using detailed, discourse-oriented analyses. Oral narratives were elicited from eight mature-language users, four language-impaired and four unimpaired. Discourse analysis was accomplished using procedures taken from normal acquisitional studies in which both the form (pronominal or nominal) and the function served by each form (switching or maintaining reference) are considered. The analysis revealed some differences between the language-impaired and unimpaired …  Lire la suite

Lloyd, L. E. (Supervisor)  Lire la suite

Studies of the effect of α-methyltryptophan on carbohydrate metabolism have shown that this amine acid analogue stimulates hepatic glycogenesis in the rat, in contrast to tryptophan which inhibits this process. Other differences in the actions of the two amino acids have been found: whereas tryptophan interferes with the conversion of the exogenous pyruvate into glycogen, α-methyltryptophan does not. Tryptophan promotes an increase in the assayable level of phosphoenolpyruvate carboxykinase in liver, but α-methyltryptophan causes a decrease. α-Methyltryptophan acts only in the presence of glucocorticoids. Furthermore, α-methyltryptophan accelerates in vivo the oxidation of tryptophan, an essential amino acid, thus probably creating …  Lire la suite

AMTP (alpha-methyl-dl-tryptophan) stimulates the conversion of amino acids, acetate and pyruvate to hepatic glycogen in rats. Accompanying this phenomenon there is an enhanced rate of oxidation of these substances (except acetate) to carbon dioxide. The action of AMTP on glutamate and pyruvate oxidation is dependent upon the adrenal gland; for leucine, isoleucine, alanine and threonine, the effect is only partially dependent; for histidine it is independent of the adrenal. [...]  Lire la suite

Ever since 1929, when Lashley (14) published the results of his brain-extirpation experiments and Kohler (11) his critique of associationism and behaviorism, psychologists have been prone to tacit acceptance of the equipotentiality hypothesis. For over two decades, many a contemporary theorist has conceded Lashley’s argument and, consequently, has assumed that some form of configuration theory constitutes the only adequate attack upon behavioral problems. [...] The recognition-differential for Jewish words, although in the opposite direction from the English differential, was small and, consequently, one could argue that the conditions for Jewish-word recognition were, in some way, qualitatively different from that of …  Lire la suite

Fifty-one children, ages 4, 5, and 6, wcre required to learn a temporal series of spatial positions under three expcrimental conditions which varied in their emphasis on visual and motor cues. For 5 and 6 year old subjects fewest errors were made undcr a condition which required overt motor activity. The greatest number of errors were made under the condition which minimized both kinethetic cues and cues of observed movement. There was no significant difference in performance between the overt motor condition, and a condition which involved cues of observed movement. The results support the hypothesis that covert motor processes …  Lire la suite

A new vapor-liquid equilibrium apparatus was constructed to measure temperature, pressure, and phase compositions up to 8 MPa. Systems of CO(,2) with 2-methyl-1-pentene, 1-hexene, 1-heptene and m-xylene were studied at 303.15 K, 323.15 K, and 343.15 K. A general method was proposed for equation of state construction. Two equations of State were constructed. Using critical temperature, critical pressure, critical compressibility factor and acentric factor, these equations can predict saturation properties of normal fluids. The equations were extended to mixtures using van der Waals' one fluid theory, Lee-Kesler corresponding state approach and a virial-like approach. They had limited predictive abilities compared …  Lire la suite

In the extrusion blow molding process the shape and thickness distribution of the finished container depend on the dimensions of the parison at the time of inflation. In particular, the processes of swell and sag act to cause a variation of parison dimensions between the time the melt emerges from the die and the moment of inflation. In the present study the effects of die geometry, extrusion velocity and the rheological properties of the resin on parison behavior were studied. Four annular dies (a straight, a diverging and two converging dies) and three high density polyethylene resins were used. To …  Lire la suite

A series of experiments was designed to investigate processes involved in written anaphor resolution. The first experiment established that lexical decisions are affected by phonological relationships between primes and targets that are presented visually. Experiment 2 explored the possibility that phonological codes are involved in processing gaps and pronouns, which are examples of surface and deep anaphors, respectively. No evidence was found to support this hypothesis. However, the complete lack of anaphor effects in Experiment 2 suggested that the lexical decision paradigm was not sensitive to anaphor processing. Experiments 3 and 4 compared the priming effects found using a probe …  Lire la suite

Schirrmacher, Ralf (Internal/Supervisor)  Lire la suite

Les neurones cholinergiques du cerveau antérieur basal (NCCAB) composent principalement l’innervation du cortex et de l’hippocampe. Ils sont essentiels à l’apprentissage, à la mémoire et à l’attention, et sont parmi les premiers à dégénérer dans la maladie d’Alzheimer (MA) contribuant aux premiers déficits cognitifs. Les inhibiteurs de l’acetylcholinesterase (IAchE), qui améliorent la signalisation cholinergique, peuvent adoucir le déclin cognitif sans toutefois affecter la progression de la maladie.Plusieurs études récentes ont démontré qu’un traitement IAchE retarde l’atrophie de l’hippocampe, du cortex et du cerveau antérieur, alors que les patients suivant un traitement anticholinergiques sont plus probables à développer la MA, indiquant …  Lire la suite

Four variable-depth pier cap beams were constructed and tested. These specimens were designed to have reinforcement details similar to types 04A and 168 pier cap beams used in the existing Champlain Bridge. The primary objectives were to examine and compare the behavior of variable depth cap beams at service loading and at failure, to analyze the effectiveness of crack control reinforcement, and to investigate the influence of external horizontal post-tensioning. Additionally, the observed cap beam responses were compared with three prediction models: sectional analyses, strut-and-tie models, and non-linear finite element analyses. It was concluded that the amount of crack control …  Lire la suite

One of the challenges facing the mining industry is the geological uncertainty associated with the variability of minerals within deposits. This variability can have significant implications for every stage of the process. The aim of this research is to enhance the implementation of data-driven frameworks for evaluating mining projects, incorporating stochastic simulation to develop digital tools that support management decisions. The objective is to create a quantitative framework that integrates geological and geometallurgical models, enabling a deeper understanding of how various variables influence the overall performance of mining systems. In mining is common generate a single plan based on a …  Lire la suite

The use of a biofungicide on the perfect stage of V. inaequalis on leaf litter is one potential way to reduce the number of fungicides used to control apple scab. The previous in vitro screenings of Quebec mycoflora have shown that several isolates are able to significantly reduce the primary inoculum of the pathogen. Among the screened fungi, P176A and P130A, reduced over 98% of the ascospore production and were as effective as Athelia bombacina. However, because in vitro tests are generally poor predictors of in vivo assays a re-evaluation of the antagonists was done under field conditions. Eight fungal …  Lire la suite

Human carcinoembryonic antigen (CEA) is the prototypic member of a large family of highly related cell surface glycoproteins that includes CEACAM6 (formerly NCA) and CEACAM1 (formerly BGP). The extracellular domains of CEA/CEACAM6 are bound to the external surface of the plasma membrane through a glycosylphosphatidyl inositol (GPI) anchor and are over-expressed in more than 50% of all human cancers. In contrast, CEACAM1 contains extracellular, transmembrane and cytoplasmic domains, and its level of expression is down-regulated in human tumors of the colon and prostate. When over-expressed on the surface of various cell types in model systems, CEA/CEACAM6, but not CEACAM1, function …  Lire la suite

Collet, Jean-Paul (Supervisor)  Lire la suite

Introduction. Research into medications for Alzheimer's disease (AD) is primarily conducted in drug trials, were efficacy is assessed by changes in score on established outcome measurement scales. However, physicians' and caregivers' perspectives on efficacy, along with their perspectives on other factors that may influence prescribing (e.g., adverse effects), remain largely unexplored. The objective of this thesis is to examine these perspectives to gain a broader understanding of the factors that can influence the use of medications in AD. Methods. Two studies were conducted. The first involved all of the Province of Quebec's geriatricians, neurologists, and psychogeriatricians, as well as a …  Lire la suite

Les expériences linguistiques précoces des bébés jouent un rôle important dans leur développement langagier. Dans cette dissertation, j'ai exploré la nature de cette relation dans un contexte bilingue. Plus précisément, j'ai étudié comment les parents bilingues fournissent l'apport langagier à leurs bébés, et comment des mesures globales de cette exposition bilingue influencent la segmentation précoce des mots (c.-à-d. la capacité de reconnaitre des formes de mots dans le contexte de phrases). Les présents travaux sont importants afin de mieux comprendre les facteurs qui contribuent à la trajectoire développementale et aux capacités de traitement des bébés bilingues. Dans la première partie …  Lire la suite

The problems of implementing a relational database are considered. In part 1, a new class of data structures for processing range queries is described. A member of this class is derived from a data structure which supports random and sequential accessing. We also describe two new data structures with this property that seem to have better performance than the Btree. In part 2, a new design for the physical database is proposed. This design is based on the separation of a relation into two parts: a static "master file" and a dynamic "differential file" which stores updates. Our design includes …  Lire la suite