McGill University Thèses et mémoires par auteur commençant par T

The light sources chosen for special study were arc tubes through which a condenser was discharged. The discharge was initiated by an external control electrode. Tubes were made of Pyrex or quartz and had cathodes of mercury or nickel. Work was first done with mercury tubes at low pressures. Later, tubes were made having nickel cathodes and filled with argon. Tubes were tested to see at what voltage they discharged spontaneously one hence if they could be used with the 20,000 V power supply available. A 2500 V power supply was obtained for use with low voltage tubes. An integrating …  Lire la suite

Amadori and Heyns rearrangement products are currently produced as crude Maillard reaction mixtures, due to lack of convenient procedures for their synthesis. The objective of this study was to develop a synthetic strategy based on polymer-supported synthesis that allows the production of different derivatives of these sugar-amino acid conjugates. The strategy involved coupling of poly(ethyleneglycol) mono methyl ether (PEGME) with N-protected (t-BOC) amino acid through catalysis by DCC (dicyclohexylcarbodimide) to form a polymer bound ester of the amino acid (89% yield with beta-alanine), followed by deprotection of the t-BOC group through a novel microwave-assisted hydrolysis process in high yields (98%). …  Lire la suite

A method of heat treating uranium oxide semiconducting material by passing through it a current many times its rated value, is given. The resulting change is permanent and it can be controlled to obtain any desired resistance over a wide range. An outline of the factors involved in the heat treatment process is presented along with a theoretical explanation of the observed results.  Lire la suite

This study presents a discrete adjoint-based aerodynamic optimization algorithm for helicopter rotor blades in hover and forward flight using a Non-Linear Frequency Domain approach. The goal is to introduce a Mach number variation into the Non-Linear Frequency Domain (NLFD) method and implement a novel approach to present a time-varying cost function through a multi-objective adjoint boundary condition. The research presents the complete formulation of the time dependent optimal design problem. The approach is firstly demonstrated for the redesign of a NACA 0007 and a NACA 23012 helicopter rotor blade section in forward flight. A three-dimensional inviscid Aerodynamic Shape Optimization (ASO) …  Lire la suite

"Married couples' treatment groups have gradually developed in recent years in response to the need to find effective ways of alleviating marital discord. The purpose of this study was to review recent (1968-1973) professional literature on couples' group treatment in order to bring it together in concise form and make it available to those in the social work profession who are involved in the provision of marriage counselling services. For the purposes of this study the literature was re­viewed in terms of questions related to (a) theoretical and clinical considerations about advantages and disadvantages, goals of treatment, and indications and …  Lire la suite

L'étude de l'apprentissage autorégulé (AAR) dans des environnements hypermédias d'apprentissage est un domaine de recherche en développement. Une question essentielle concerne le rôle des connaissances antérieures qui peuvent influencer la manière dont les étudiants utilisent des stratégies d'AAR lorsqu'ils interagissent avec des systèmes hypermédias d'apprentissage. Dans cette étude, nous examinons les interactions de 52 étudiants de premier cycle universitaire avec MetaTutor, un environnement d'apprentissage multi-agents à base d'hypermédia portant sur le système circulatoire sanguin. Nous évaluons comment des niveaux de connaissances antérieures différents ont pu affecter l'usage par les étudiants de certaines stratégies cognitives et métacognitives d'AAR en termes de …  Lire la suite

In 1915 Twort published his classical paper entitled "An Investigation on the Nature of Ultra-microscopic Viruses". Among the non-pathogenic viruses that he was trying to isolate from various sources was calf vaccinia. Some "glycerinated calf vaccinia" preparations were contaminated with micrococci, and it is to his credit that he noted that the "inoculated agar tubes, after 24 hours at 37°C. often showed watery looking areas, and in cultures that gres micrococci, it was found that some of these colonies could not be subcultured, but if kept, they became glassy and transparent".  Lire la suite

Zaloum, Ronald (Advisor)  Lire la suite

Les acides aminés (AAs) polaires et chargés sont les principaux composants des protéines non collagéniques, et sont impliqués dans la minéralisation d'hydroxyapatites (HA) dans les os. Bien que les AAs soit des candidats prometteurs pour contrôler la minéralisation d'HA, le mécanisme par lequel ils interagissent avec les ions Ca2+ et PO43- ou avec les cristaux d'HA pour induire ou inhiber la minéralisation n'est pas encore bien compris. La plupart des études sur les AAs et sur la cristallisation d'HA sont menées dans des conditions expérimentales différentes des conditions physiologiques, ce qui a rendu difficile l'obtention d'un véritable aperçu des effets …  Lire la suite

Braitstein, Lara E (Supervisor1)  Lire la suite

Relational memory consists of multi-domain cognitive processes involved in information encoding and retrieval. These relational domains include episodic, semantic, and spatial memory, and they operate by binding discrete domain-specific elements of subjective experience into a coherent mental scheme. For example, in episodic memory, successive spatiotemporal events are combined into an autobiographical abstraction known as an episode. Similarly, in semantic memory, facts and notions are organized into a hierarchy of conceptual categories, and in spatial memory, the physical locations of surrounding objects are mapped out into a mental repository known as a cognitive map.These distinct forms of relational memory have typically …  Lire la suite

RésuméIl a été montré que certains facteurs de transcription sont capables de stimuler l’activité enzymatique de protéines de la voie de réparation des bases. Plus particulièrement, l’équipe du Dr. Alain Nepveu a montré que les domaines CUT, des protéines CUX1, SATB1 et CUX2 stimulent l’activité de la glycosylase OGG1, l’endonucléase APE1 et la Polymérase Pol β. Des découvertes récentes au laboratoire suggèrent que d’autres facteurs de transcription, tels que BCL11B et MYC, pourraient également être impliqués dans la voie de réparation des bases.Mon projet a porté sur la caractérisation de ces protéines et l’étude de leur rôle dans la réparation …  Lire la suite

In order to achieve highly efficient and compact light sources for chip-level optical communications, different types of microcavity structures have been extensively studied. Among them, rolled-up III-V semiconductor microtubes exhibit distinct characteristics including directional emission and polarization control and can be readily transferred on Si substrate. Such tubular structures are formed when a coherently strained nanomembrane is selectively released from its native substrate. This dissertation reports on the achievement, for the first time, of III-V based optically and electrically pumped microtube lasers and also photodetectors operating at telecom wavelength. Furthermore, we report on the achievement of the first AlN nanowire …  Lire la suite

Attia, Mahmoud Helmi (Internal/Supervisor)  Lire la suite

Les cordes vocales (CV) sont deux lèvres de tissu mou du larynx impliquées dans la phonation. Les modifications de leurs propriétés viscoélastiques ont un effet direct sur la production vocale. Cette thèse étudie l'influence d'une poche de biomatériau injectable sur la réponse phonatoire d'un modèle synthétique de CV à l'aide d'un modèle informatique. Le tissu des plis vocaux a été idéalisé en tant que couche corporelle souple représentant la lamina propria recouverte d'une couche d'épithélium. Une cavité remplie de matériau synthétique d'échafaudage a été créée dans la couche corporelle pour étudier l'influence des hydrogels composites injectables sur la réponse vocale. …  Lire la suite

Introduction:Les lésions muqueuses intraorales sont des observations cliniques courantes qui varient considérablement en termes de présentation et d'étiologie, allant de lésions bénignes à malignes telles que le carcinome épidermoïde buccal (CEB). Un diagnostic précoce et précis est essentiel pour une intervention rapide, en particulier compte tenu du mauvais pronostic associé à l'OSCC à un stade avancé. Les progrès récents en matière d'intelligence artificielle (IA), en particulier les réseaux neuronaux convolutifs (CNN), ont montré leur potentiel pour faciliter les processus de diagnostic en automatisant la classification des lésions à partir de données d'images. Cependant, ces modèles sont souvent perçus comme des …  Lire la suite

Retinal ganglion cell (RGC) axon arbors within the optic tectum are refined in development through a dynamic process of activity-dependent remodeling. The synaptic adhesion molecule N-cadherin is a candidate for mediating selective stabilization and elaboration of RGC axons due to its localization to perisynaptic sites and its modifiability by neural activity. RGCs of Xenopus tadpoles were co-transfected with plasmids encoding a dominant negative N-cadherin (N-cadDeltaE) and eGFP or eYFP. Using two-photon in vivo time-lapse imaging, we found that axons expressing N-cadDeltaE became less elaborate than controls over three days of daily live imaging. Shorter interval time-lapse imaging of axons expressing …  Lire la suite

Les coupleurs de fibres optiques sont des composantes essentielles utilisées dans divers dispositifs et systèmes optiques. Ils possèdent plusieurs fonctionnalités, allant d'un simple fractionnement ou d'une combinaison de puissance, pouvant même être utilisés dans un récepteur avancé de détection cohérente à grande vitesse. De récents progrès dans la production de sources et composantes fonctionnant dans l'infrarouge moyen requièrent l'utilisation de coupleurs infrarouge à fibres optiques. Des coupleurs à fibres de silice déjà bien implantés sur le marché atteignent des ratios de couplage arbitraires dans la bande C. Toutefois, ceux-ci sont dotés d'une grande absorption dans l'infrarouge moyen (2-12 µm), ce …  Lire la suite

Rapid population growth is now one of the biggest socio-economic and consequently, health problems in the world. The significance of this dramatic increase in population becomes apparent when the limited possibilities of socio-economic growth are considered among developing countries. The use of modern contraceptives in order to control birth rates, on the other hand, is rather limited in these countries. The present study investigates the knowledge and attitudes of family planning programs by Iranian males, who play a major role in all familial decision-making, including the practice of family planning. This research examines subjects' reasoning strategies about practicing family planning. …  Lire la suite

Van de Ven, Theodorus G. (Supervisor2)  Lire la suite

Electromagnetic band-gap (EBG) structures, often termed frequency selective surfaces (FSSs) or photonic band-gap (PBG) materials, have found widespread applications as filters for microwaves and optical signals. Due to their frequency selective features and ease of implementation in printed circuit board (PCB) technology, EBG structures are utilized in power distribution networks (PDNs) to induce wide stopband and to provide global power/ground noise suppression. Attenuation characteristic of EBG structures within their forbidden frequency regions is examined in this thesis which ultimately provides the insertion loss obtained by inserting the EBG structure in the PDN. Bandgap characterization is efficiently achieved by applying the …  Lire la suite

SRY (Sex determining Region of Y chromosome) is the master gene initiating testis determination in mammals. To shed light on the molecular mechanism of SRY action during testicular differentiation, we examined the effects of TAT-HMG fusion protein on gonadal sex differentiation in culture. HMG is the DNA binding motif of SRY and "TAT" is a protein transduction domain. Each pair of CD1 mouse gonadal primordia at 11.5 days post coitum (dpc) was cultured with or without TAT-HMG dissolved in dimethyl sulfoxide (DMSO) up to 3 days. Immunocytochemical labeling and Real-time RT-PCR of Sry, Sox9 and Mis indicated that DMSO blocked …  Lire la suite

Paidoussis, Michael P. (Supervisor2)  Lire la suite

Antécédent: les patients transplantés rénaux hautement sensibilisés sont sur la liste de transplantation en raison d'anticorps anti-HLA. Les protocoles actuels de désensibilisation sont non fiables. Interleukin-21 est une cytokine de type I qui signale par intermédiaire d'un récepteur commun entre les facteurs de croissance des cellules T (TCGFs). Sécrétée par les cellules T, l'IL-21 agit comme un régulateur de la production d'anticorps anti cellule B, de la différenciation des plasmocytes, ainsi de la commutation de classe d'immunoglobuline. Il co-stimule la prolifération et la réponse de la mémoire dans les cellules T. Nous avons évoqué l'hypothèse que l'IL-21 pourrait être un …  Lire la suite

Faramarz P Hassani (Supervisor2)  Lire la suite

One of the main questions of modern biology is how our cells interpret our genetic and epigenetic information. DNA methylation is a covalent modification of the genome that is essential for mammalian development and plays an important role in the control of gene expression, genomic imprinting and X-chromosome inactivation (Bird and Wolffe, 1999; Szyf et al., 2000). Furthermore, changes in DNA methylation and DNA methyltransferase 1 (DNMT1) activity have been widely documented in a number of human cancers (Szyf, 1998a; Szyf et al., 2000). In Escherichia coli, timing and frequency of initiation of DNA replication are controlled by the levels …  Lire la suite

This thesis presents a dual plasma process allowing for the single-step synthesis of surface functionalized metal nanoparticles. The process uses a pulsed cathodic arc discharge to erode a metal target and form nanoparticles. These nanoparticles are then coated in flight through plasma polymerization in a radio-frequency glow discharge. This discharge was sustained in a wide range of organic precursors to affect the resulting surface properties of the nanoparticles. Using ethane as the plasma polymerizing monomer, a super-hydrophobic surface is formed. Alternatively, the use of ethylene glycol to modify the particle results in the formation of a super-hydrophilic surface. This treatment …  Lire la suite

The work reported in this thesis is motivated by the need for new screening techniques for detecting early-stage breast tumors. In recent years, pulsed microwave imaging in the gigahertz range has been suggested as a promising complementing methodology to the currently existing detection and imaging modalities. This technique is based on significant electrical contrast between the cancerous and healthy breast tissue in the microwave range. To exploit this electrical contrast for imaging purposes, a broadband trans-receiving antenna is placed near the breast surface. The antenna launches a pulse and then collects the backscattered response, used for detection of the potentially …  Lire la suite

1,25-dihydroxyvitamin D3 (1,25D3), also know as cholecalciferol, is still best known as a regulator of calcium homeostasis. However more recent studies have revealed the pleiotropic actions of 1,25D 3, including immune and nervous system modulation, and cellular proliferation and differentiation. Epidemiological and model studies have revealed the anticancer properties of 1,25D3, which modulates gene transcription through the nuclear vitamin D receptor (VDR). This dissertation is composed of four different studies that focus on the molecular and genetic events that underlie the anticancer properties of 1,25D3. Our first set of experiments was a genome-wide exploration of cognate 1,25D3 response elements (VDREs), …  Lire la suite

This thesis has focused on the measurement of gas holdup in flotation systems, a variable not measured reliably to date. A sensor was designed using so-called flow conductivity cells. Their properties were studied and modelled, and their application in the design, construction, and operation of a gas holdup probe for use in flotation systems described. A flow cell is defined as one that allows a fluid or dispersion to flow through freely while the electrical conductivity is measured. One of the most important features of a flow cell is the so-called cell constant. Once the cell constant is determined, the …  Lire la suite

Bone marrow transplantation (BMT) involves the use of maximal doses of chemotherapy and total body irradiation. As a result, even well-nourished patients exhibit negative nitrogen balance and hypoproteinemia in the post-transplant period, despite a high energy and protein intake from Total Parenteral Nutrition (TPN). The purpose of this research was to investigate the impact of cytotoxic therapy, with a view toward explaining and improving the response to nutritional support. Stool, urine and serum biochemistry were studied prospectively in 10 BMT patients. Analysis of stool revealed increased sodium and decreased potassium. Examination of serum electrolytes indicated hyponatremia and hyperkalemia. A significant …  Lire la suite

During processing, polymers are exposed to complex thermal and deformation fields. Under these conditions, partially crystalline polymers undergo crystallization, which contributes significantly to their ultimate properties. While the thermal effects on polymer crystallization have been studied extensively, there is much less research carried out with regard to the effects of deformation and stress on crystallization kinetics. This is in part due to experimental difficulties in making appropriate measurements. In the present work, the Linkam Shearing Cell, in conjunction with a polarized light microscope, was used to study the effect of shear on the growth kinetics of various linear low-density polyethylene …  Lire la suite

Aluminum-silicon-copper cast alloys of the 319-type have attained a commercially important status because of their widespread use. Artificial aging treatments are routinely applied to these alloys in order to obtain precipitation hardening and improve their mechanical properties. Standard treatments may not always yield the optimum achievable properties, thus Mg and Sr are commonly added to improve the response of the alloy to aging and to modify the eutectic Si morphology from acicular to fibrous, respectively. The present study was carried out to investigate aging behavior of four 319-type alloys in regard to such mechanical properties as their ultimate tensile strength, …  Lire la suite

The capability of a brain to efficiently carry out its fundamental function of information processing depends on normal morphogenesis which includes optimal development and maturation. Adolescence is a period when the brain is completing its structural and functional maturation and exhibits heightened susceptibility to adult mental illness, an example of which is schizophrenia. In addition to the clinical manifestation of positive, negative and cognitive symptoms, anomalies documented in schizophrenia patients include cerebrocraniofacial dysmorphology and elevated levels of oxidative stress. The causes of schizophrenia are still unknown, but many stressors have been identified as risk factors. However, it is not known …  Lire la suite

The autophosphorylating protein kinase CheA plays a central role in the chemotaxis signal transduction system of Escherichia coli. CheA receives information regarding the chemical composition of the extracellular milieu from transmembrane chemoreceptor proteins and conveys this information to CheY, a cytoplasmic protein that directly influences the swimming behaviour of the cell. The research presented in this thesis focused on understanding the interaction of CheA with ATP and ADP; it led to our development of a minimal kinetic model describing CheA autophosphorylation and dephosphorylation and enabled determination of kinetic constants describing CheA-nucleotide interactions and phospho-transfer. This information was utilized to study …  Lire la suite

Les perturbations sont omniprésentes dans la nature et il a été démontré qu’elles affectent différemment les niveaux écologiques. Les effets écologiques et les réponses du biote à de multiples perturbations ont rarement été documentés en raison de la rareté des perturbations concomitantes au niveau du paysage. Cette thèse de maîtrise vise à discerner les effets des perturbations anthropiques et naturelles simultanées à Long Point, Ontario, Canada à deux niveaux écologiques : 1) comprendre les associations de paysages et d'habitats au niveau de la population des grenouilles et des crapauds après perturbation, et 2) pour explorer les différences de composition et …  Lire la suite

This work presents novel architectures for improving the performance of capacitive-based micromachined thermal detectors, ultrasonic transducers, and multiplexers. The proposed designs are implemented in a pure-play commercial process, which is known for its reliability and cost-effectiveness. In addition, several performance-limitation issues are tackled. Furthermore, a novel approach is proposed for implementing standalone MEMS arrays, to avoid the complicated and expensive post-processing of complementary metal-oxide-semiconductor (CMOS) wafers.The first part of this work presents a novel dual-level capacitive bimorphous thermal detector architecture that is prototyped in the commercial PolyMUMPs by MEMSCAP. The dual-level design exhibits a 6.5 fF/°C sensitivity which is over …  Lire la suite

Un des rapports internes les plus importantes que nous ayons recus du Hijas concernant les ashraf est Khulasat al-Kalam fi Bayan Umara' al Balad al-Haram. Dahlan (1816-1886) était le mufti du rite Shafi'ite et le shaykh al-'ulama' a Makkah. Etant un observateur et savant religieux de premier ordre a Hijas dans la seconde moitié du 19e siecle, cela certainement, fait de lui une source extremement importante si les historiens désirent tracer un portrait clair de l'histoire des ashraf a cette époque.  Lire la suite

The rat integrin $ alpha sb1$ subunit was purified, its N-terminal sequence and its full cDNA sequence were obtained. The $ alpha sb1$ subunit is found complexed with the $ beta sb1$ subunit forming a heterodimer that mediates the adhesion of type-1 astrocytes to laminin and collagen. Cultured type-1 astrocytes also express other functional integrins from the $ beta sb1$ and $ beta sb3$ subclasses. Type-2 astrocytes and oligodendrocytes express different arrays of $ beta sb1$ and $ beta sb3$ integrins suggesting that CNS glia interact differentially with the extracellular matrix. Integrins on type-1 astrocytes are localized either to focal …  Lire la suite

Carbonetto, Turner and coworkers have isolated a monoclonal antibody (Mab 3A3; Turner et al., 1989) which selectively inhibits neurite outgrowth by PC-12 cells, a rat pheochromocytoma cell line, on laminin and collagen. I have shown that Mab 3A3 detaches PC-12 cells from laminin and collagen but not from fibronectin or polylysine. Mab 3A3 immunoprecipitates from rat brian homogenates two cell-surface proteins of 185 and 115 kDa. Three lines of evidence presented in this thesis suggest that these two proteins are a heterodimer that belongs to the integrin family of receptors. First, an antiserum that recognizes a $ beta sb1$ subunit …  Lire la suite

Les anomalies du système vasculaire y compris les thromboses locales et périphériques, sont des caractéristiques importantes des glioblastomes (GBM) et le résultat de la dérégulation des programmes génétiques et épigénétiques des cellules cancéreuses.Dans ce projet de thèse nous avons étudié la relation, encore inconnue, entre la complexité de l’architecture des populations de cellules individuelles constituantes des GBM avec la distribution des gènes reliés au système vasculaire et ainsi leur impact sur le développement des thromboses. Nous avons examiné la relation entre les mutations conductrices et les programmes épigénétiques dans l’émergence des sous populations de cellules cancéreuses liées ou non au …  Lire la suite

The purpose of this study was to explore wheelchair rugby coaches lived experiences in the development of their athletes who had acquired a spinal cord injury (SCI). Four elite wheelchair rugby coaches in Canada were interviewed using a semi-structured open-ended interview format. Smith and Osborn's (2008) Interpretative Phenomenological Approach (IPA) was used to inductively analyze and interpret the data. Results revealed three higher-order categories: (a) Coach Attributes and Development, highlighted the evolution of the coaches and their methods of knowledge acquisition in the sport of wheelchair rugby; (b) Coaching the Sport, described the sporting environment of wheelchair rugby, including the …  Lire la suite

Energy availability and environmental issues are of growing concern; nations are striving to use energy more efficiently while at the same time decreasing the negative impacts on the environment. The objectives of this study are to: (1) establish a supply price for ethanol derived from switchgrass, (2) establish an accounting budget for carbon dioxide during feedstock production and processing into ethanol, and (3) determine the cost/tonne of CO$ sb2$ using this strategy. Total cost of production of the feedstock for cycles of 5, 10, 15, and 20 years are $357.06/ha ( $32.73/ODT), $337.81/ha ( $30.96/ODT), $331.52/ha ( $30.39/ODT), and $328.47/ha …  Lire la suite

Worldwide CO2 generation is estimated to range between 25 and 30 gigatonne per year. Environmental specialists and legislators suggest that preventing even a small percentage of this CO2 from entering the atmosphere can help alleviate the emission-induced climatic changes. It is estimated that for the cement industry, each tonne of cement clinker generates approximately 0.8 tonne of CO2. Therefore, the mitigation of carbon dioxide has become a collective global challenge, where legislative efforts in many countries seek to mandate the recovery of flue gas CO2 in the near future. The concept of Carbon Capture and Utilization (CCU) presents a valid …  Lire la suite

Smooth design spectra are generally used to describe the seismic excitation provided by the maximum design earthquake for safety evaluation of critical facilities located in Eastern Canada. However, a comprehensive study of the inelastic behaviour of critical structural systems requires step-by-step inelastic analysis in the time domain. This thesis presents a study of inelastic seismic analysis of short-period structures subjected to ground motion acceleration time histories compatible with Eastern Canadian conditions and defined (i) from historical records scaled to the smooth design spectrum intensity, (ii) from spectrum-compatible accelerograms generated by random vibration theory, and (iii) from the modification of the …  Lire la suite