McGill University Thèses et mémoires par auteur commençant par A

Les parasites du genre Leishmania assurent leur survie et leur propagation par l'altération de voies de signalisation impliquées dans la capacité des macrophages (MØs) à détruire directement les pathogènes ou à activer les cellules du système immunitaire acquis. Une étape critique de ce mécanisme d'inactivation est l'activation par Leishmania de la protéine phosphatase SHP-1 de la cellule hôte. Il a été démontré que la protéine SHP-1 peut inactiver directement JAK2 ainsi que Erk1/2 et joue un rôle dans la régulation négative de plusieurs facteurs de transcription, tels que NF-κB, STAT-1α et AP-1, impliqués dans l'activation des MØs. L'altération de ces …  Lire la suite

Sjögren’s syndrome (SS) is a common, chronic, and debilitating autoimmune diseases, affecting nearly 4 million North Americans. It affects females approximately 14 times higher than males, most of which are postmenopausal women. It is characterized by exocrine glands lymphocytic infiltration and glandular destruction. SS is a slowly progressing disease that starts decades before the patients experience any symptoms. Patients will experience dry eyes and mouth, and a wide range of extra-glandular manifestations, including fatigue, arthritis, arthralgia, pulmonary, neurological, cutaneous, and muscular manifestations, and lymphoma. The generalized manifestations lead to a significantly compromised quality of life. The pathogenesis is complex and …  Lire la suite

Thermoplastics injection molding involves plastication followed by the injection of the melt into a cold cavity. Packing is employed to compensate for shrinkage due to cooling. Ultimately, the solidified part is ejected from the mold without damage. The successful operation of an injection molding machine requires control of the process variables during each of the consecutive stages in addition to correctly identifying the points of transition from one stage to the next. Pressure and its variation during the injection molding cycle play an important role with regard to productivity, product quality, and product reproducibility. From the practical point of view, …  Lire la suite

Les facteurs maternels pendant la gestation, tels que le stress, l’exposition à des toxines environnementales ou les infections bactériennes ou virales, sont systématiquement associés à des altérations du développement cérébral fœtal et à des troubles neurodéveloppementaux (TND). Ces facteurs variés sont de plus en plus compris dans un cadre conceptuel commun : celui de l’activation immunitaire maternelle (AIM). Des études cliniques et précliniques ont mis en évidence des altérations induites par l’AIM à plusieurs niveaux, allant des changements moléculaires aux changements volumétriques cérébrales, et ce, tout au long de la vie de la progéniture. Cependant, peu d’études ont appliqué les …  Lire la suite

For the past 30 years, titanium implants have been used routinely to treat partial and complete dental edentulism. The clinical success of titanium implants relies on osseointegration, a process similar to bone healing. Successful osseointegration of titanium implant requires normal functioning of the biological events that occur during bone healing. Therefore, any factor that alters bone healing will jeopardise the success of titanium implant and might cause peri-implant complication or premature implant loss.Many people worldwide are exposed to long-term use of systemic medications. Many of these medications are known to interfere with bone accrual. Yet, little is known about the …  Lire la suite

Murshed, Monzur (Supervisor1)  Lire la suite

The generalized least squares (GLS) method for phylogenetic inference assumes that errors in observed distances have an approximately Gaussian distribution. GLS has not been widely used nor properly evaluated because of computational difficulties. We examine issues relating to the implementation of GLS. Different estimates for the covariance matrix are examined. We found that the matrix is often ill-conditioned. Methods for solving the ill-conditioned unconstrained least squares problem are compared in terms of stability and efficiency. We conclude that the normal equations method, with a modified covariance matrix, performs best. Versions of the nonnegative constrained GLS method are discussed, implemented, and …  Lire la suite

Manipuler les mécanismes de réparation de l'ADN impliquées dans la réparation de dommage de l'ADN médiatisé de la topoisomérase-1 (Top I) peut renforcer les bienfaits thérapeutiques des poisons Top I. Les inhibiteurs de polymérase poly-ADP ribose (PARP) peuvent augmenter la cytotoxicité de plusieurs agents anticancéreux en inhibant différentes voies de réparation de l'ADN comprenant la réparation par recombinaison homologue (HRR)(1). Cependant, l'inhibition de la PARP peut entraîner une activation compensatoire de la voie ATR, limitant partiellement la sensibilisation des agents chimiothérapiques observés avec les inhibiteurs de PARP. Récemment, un inhibiteur de l'ATR spécifique, VE-821 a démontré une excellente sensibilisation à …  Lire la suite

Alcohol use disorders are among the top two most prevalent psychiatric conditions in the Americas. Their expression is complex and their developmental pathways are varied. Understanding how individual differences in these pathways lead to the full pathology is imperative for designing and implementing effective therapeutic and preventative interventions. To investigate these pathways, we studied healthy young adults who classified as high in either anxiety-sensitivity or sensation-seeking traits (HAS and HSS, respectively). All subjects completed two functional magnetic resonance imaging sessions following the ingestion of either ethanol (g/kg) or placebo given in a double-blind, counter-balanced repeated-measures design. In the scanner, subjects …  Lire la suite

Metamaterials offer unique electromagnetic properties that cannot be achieved with conventional materials. Virus-templating shows promise as a sustainable and scalable method to organize metal nanoparticles into metamaterials with high spatial precision. Tobacco mosaic virus coat protein self-assembles into disk- and rod-shaped particles depending on pH and ionic strength. The disk particles are particularly interesting as a template to create metal nanorings. In this work, we first discuss the use of alcohol cosolvents to stabilize tobacco mosaic virus disks under conditions that normally favour helical rods. We then demonstrate the use of a hexahistidine-tagged mutant disk to self-assemble extended nanostructures, including …  Lire la suite

Control of Taraxacum officinale (dandelion) and other broadleaf weeds in turfgrass has been readily achieved with phenoxy herbicides, but the herbicide option has been revoked in many regions, necessitating alternative weed control strategies. One biological alternative is Sclerotinia minor, an Ascomycete fungus. The impact of S. minor on broadleaf weed dynamics and biotic interactions were studied in a turfgrass environment. The goal was to maximize effectiveness of a S. minor formulation as a biocontrol of dandelion using an ecological approach. S. minor efficacy was not affected by turf microenvironments and was similarly efficacious with spring or fall application. All accessions …  Lire la suite

Potato is one of the most important crops grown in Canada and all over the world. Late blight caused by P. infestans is one of the major diseases of potato and is mainly managed by fungicides application. The extensive use of fungicides not only causes adverse effects on the environment but also accelerates the development of resistance in this pathogen. Horizontal resistance is considered as the best choice to control P. infestans as it is durable over years. Breeding for durable resistance requires evaluation of hundreds of breeding lines in greenhouses and in the field. This is usually done by …  Lire la suite

Marino, Faleh Tamimi (Supervisor2)  Lire la suite

The rapid growth of medical sciences and technologies created the need of increased use of computers to address the recognized problems associated with information overload, and to help health care professionals provide better quality decisions. This thesis presents the development, implementation, and evaluation of a real-time expert monitoring system (EMS) developed for the patient data management system (PDMS) of a pediatric intensive care unit. The objective of the EMS is to generate real-time warning signals in the event of life threatening patient conditions. The research in this thesis concentrated on the analysis of the performance of the expert system in …  Lire la suite

Tight regulation of the double-stranded RNA (dsRNA)-activated protein kinase (PKR) is critical for the maintenance of cellular homeostasis due to its potent inhibitory role on general translation. Previously, we have identified the adaptor protein Nck-1 as a novel cellular regulator of PKR activation through its interaction with PKR. In this study, we further confirmed that Nck-1 limits PKR activation under normal conditions. However, we demonstrate that the control of PKR activation by Nck-1 is reversible, since significant levels of dsRNA override Nck-1's negative control of PKR activation and induce dissociation of Nck-1 from PKR. Our data show that Nck-1 needs …  Lire la suite

Harpp, David N. (Supervisor)  Lire la suite

The problem of Divine Attributes had been one of the most central issues in the theological discussions of the Muslims over which (along with other issues) the world of Islam was divided into numerous sects. In the present study we have tried to look at the problem through the discussions of al-Ghazali who is the most representative of orthodox Islam. Indeed, until the coming of al-Ghazali in the 11th and 12th centuries no serious thinker after al-Ash'ari was able to challenge the Mu'tazilah sect over the matters of creed. The core of this thesis is the translation of the part …  Lire la suite

Les Accords commerciaux régionaux (ACR) se sont multipliés à un rythme sans précédent depuis la création de l'Organisation mondiale du commerce (OMC). Bien que l'OMC reconnaisse légalement aux pays le droit de former des accords commerciaux régionaux, ni l'OMC, ni les parties aux ACR ont une compréhension claire de la relation entre l'OMC et les accords commerciaux régionaux. En d'autres termes, les controverses juridiques résultant du flou relatif à l'application de règles de l'OMC / GATT risquent de nuire aux objectifs du système commercial multilatéral.Cette thèse aborde un phénomène qui est le plus souvent considéré comme relevant essentiellement des domaines …  Lire la suite

Thioredoxin-interacting protein (TXNIP), also known as Vitamin D upregulated protein (VDUP), is an alpha arrestin family member that acts as an endogenous inhibitor of the thiol oxidoreductase thioredoxin (TRX). TXNIP expression is heightened in response to hyperglycemia, vitamin D, and longevity-inducing factors such as calorie restriction and fasting. During studies of the role of TXNIP in diabetic nephropathy, it was observed that TXNIP KO cells were characterized by decreased cell number but also decreased apoptosis, reminiscent of cellular senescence. Thus this thesis aimed to investigate TXNIP's role in cellular senescence and organismal aging using a replicative model of senescence in …  Lire la suite

Mid-infrared (IR) wavelength range (2–12 μm), encompassing numerous molecular fingerprintswith strong fundamental vibrational transitions, is tremendously important for variousspectroscopy applications. Currently, commercially available mid-IR sources are mostly basedon semiconductor or gas gain media, nonlinear wavelength conversion in bulk nonlinear crystals,and rare-earth doped fluoride fibers. Generally, fiber lasers have the advantages of highefficiency, compactness, superior reliability, and excellent beam quality. Commercially availablemid-IR fiber lasers are mostly based on silica or fluoride fibers. However, transmissionwindows of silica and fluoride glasses are limited to 2.5 μm and 5.5 μm, respectively, and emissionfrom rare-earth dopants can only cover a small portion of the mid-IR …  Lire la suite

This study is an analysis of thirty-one interviews held in 1952, with men who were residing at the Meurling Refuge, a municipal shelter in the city of Montreal. It is undertaken with a view to learn of the factors that might have some bearing on why these particular men have become dependent on an institution of this nature. In addition, the writer will survey other existing services available in Canada for the homeless and consider how these services meet the needs of these men. As described in this study, a "homeless man" will denote one who is not attached to …  Lire la suite

Al-Jallad, Hadil (Internal/Cosupervisor2)  Lire la suite

The process of knowledge transfer (KT) is an important factor in minimizing the loss of productivity and increasing performance in various organizations. This study adopts the view of a high school as a knowledge-based organization and responds to calls for research at the intersection of education and knowledge management. The postulation is that students will benefit from KT. In order to verify this postulation, the study’s framework is based on the adaptation and use of an empirically tested model put forth by Szulanski (1996). The study’s purpose is to investigate the transfer of experiential knowledge from past student cohorts to …  Lire la suite

The development of engineered wood products (EWPs), such as glued laminated timber, has led to the production of structural members with increased strength and spanning capabilities compared with solid sawn lumber and timber, and similar to what one could attain with commonly sized steel and reinforced concrete members. An important reason for the underutilisation of wood for heavy construction is the limitation of the CSA O86 Wood Design Standard especially as it applies to the design of fastenings for highly loaded connections. This thesis addresses the connection design of glulam and sawn wood using structural self-tapping/self-drilling screws from Europe.The CSA–O86 …  Lire la suite

Arab Canadians are a heterogeneous and frequently misunderstood group whose educational background and cultural heritage have received little attention in the scholarly literature. In multicultural Canada, educators, curriculum developers, textbook authors and policy makers rely on available literature to inform their decision-making processes. Mainstream media, as a source of information and insight, do not fill this need. In this inquiry, I examine the cross cultural and educational experiences of ten Arab undergraduate students in two English-language universities in Montreal. Participants were from Libya, Tunisia, Algeria, and Morocco and have been in Canada for three to seven years. Classic qualitative methodological …  Lire la suite

Cette thèse se concentre sur l'étude de la transformation des matériaux d'un état isotrope à une phase cristalline liquide ordonnée lamellaire de type smectique A par l'entremise de modélisations et de simulations de multi-échelles. Cette approche s'appuie sur le modèle phénoménologique de Landau-de Gennes qui est capable de faire le lien entre les observations expérimentales de phénomènes macroscopiques et la croissance nanoscopique associé à la structure inhérente d'un cristal liquide. L'un des attraits principaux de cette thèse basée sur les simulations provient du fait qu'elle vérifie directement des données expérimentales observées par le passé. Dans la même optique, les apports …  Lire la suite

Le récepteur de la [pro]rénine (PRR) est un acteur largement étudié dans le Système Rénine-Angiotensine (SRA). Par ailleurs, des preuves récentes nous indiquent que PRR aurait aussi un rôle important dans une multitude d'autres fonctions cellulaires et physiologiques notamment le métabolisme énergétique et le cancer. PRR est clivé pour former deux produits: le fragment soluble PRR (sPRR) et le fragment M8.9. Des études, portant sur les niveaux plasmatiques de sPRR, mettent en évidence le potentiel de sPRR en tant que biomarqueur diagnostique pour plusieurs maladies. De plus, plusieurs études attribue au PRR pleine longueur et le sPRR un rôle dans …  Lire la suite

This study involved characterizing the oxidation behaviour of low carbon steel in various gas mixtures of O$ rm sb2, CO sb2, H sb2O$ and N$ sb2,$ at different oxidation temperatures. Rate measurements for the oxidation of the low carbon steel during reheating in a walking-beam steel reheat furnace were also carried out. Scaling rates during reheating were predicted from oxidation rates obtained in the laboratory. In-situ characterization of the phase compositions of the iron oxides, "scale", that form on low carbon steels during their oxidation at elevated temperatures was carried out using a neutron diffraction technique. Growths in the intensities …  Lire la suite

In hot strip mills, in the steel industry, reheat furnaces are utilized to reheat slabs, billets, blooms, etc., to uniform rolling temperatures prior to hot working. During this reheating operation, hot steel surfaces react with the in-furnace oxidizing atmosphere resulting in the formation of an iron oxides layer (scale). The yield loss due to this phenomenon depends on furnace operating conditions, i.e. steel temperature, excess combustion air, steel residence time in the furnace, etc., and ranges between 1.5 to 3% of reheated steel. In this research, the oxidation of a mild steel during reheating cycles as function of furnace atmosphere, …  Lire la suite

Localized Surface Plasmon Resonance (LSPR) sensors have attracted substantial interest in various applications due to their plasmonic properties, low cost instrumentation, and small sample requirement. LSPR is a photon-driven oscillation of the conduction electrons in metallic nanostructures. It features a short electromagnetic (EM) decay length, increasing the specificity to the bound analytes and reducing artefacts due to the variations in bulk refractive index (RI). However, the short EM decay length degrades the signal to noise ratio (SNR) of LSPR sensors, thereby reducing the accuracy of the results. To improve the SNR and accuracy of LSPR sensors, this thesis introduces new …  Lire la suite

Plant sterol-containing food products are known to reduce low density lipoprotein (LDL) cholesterol, with the degree of placebo-adjusted reduction ranging from 5% to 15%. Factors that affect plant sterol efficacy such as the type of formulation and dosing frequency are still to be determined. Thus, the objective of this thesis was to investigate the impact of novel plant sterol preparations, frequency of intake and time of intake of plant sterols on cholesterol kinetics and/or plasma lipid profile. Three randomized, placebo-controlled, single-blind, crossover, supervised feeding trials were conducted in 75 subjects with LDL levels of > 3.0 mmol/L. The results from …  Lire la suite

Introduction: Cancer survivors will experience a wide range of physical and emotional sequelae from cancer and from its treatment which will negatively impact their well being and quality of life (QOL). As a result, QOL in people with cancer has become an important outcome for both clinical care and research. Patient Generated Index (PGI) is designed to both ask and document QOL concerns. Its validity with respect to standard QOL measures has not been fully established for advanced cancer when QOL concerns predominate. The global aim of this thesis is to contribute evidence towards the applicability of the PGI in …  Lire la suite

Les personnes ayant subi un accident vasculaire cérébral (AVC) éprouvent des problèmes de marche qui sont caractérisés par une vitesse lente et une capacité réduite à s'adapter aux exigences de l'environnement. Changer la direction de la marche peut être difficile, surtout lorsqu'exposé à des informations visuelles complexes. Il a été démontré auparavant que les personnes ayant subi un AVC présentent des altérations de leur capacité à changer de direction pendant la marche en réponse à des changements de flux optique. Le but de cette étude était de comparer des personnes ayant subi un AVC et des personnes en bonne santé …  Lire la suite

Moutih Rafei (Supervisor2)  Lire la suite

The major aim of this thesis has been to contribute to the understanding of the CH$ sb2$/OH/NH$ sb2$ group interactions by means of studies of alcohol-amine mixtures in the gas and liquid phases. To study these interactions in the gas phase a Burnett type equipment was designed, built and operated at low pressure, obtaining experimental pressure-temperature (P-T) data for various systems including alcohol-amylamine mixtures. The P-T data were reduced by a method developed in this work to give values of second virial coefficients. Measurements on known systems were in excellent agreement with values reported in the literature. A group contribution …  Lire la suite

Processing of petrochemical compounds produces a large amount of wastewater. This wastewater consists of toxic (hazardous) materials that can not be discharged to the environment without treatment. As restrictive environmental constraints increase, new technologies are needed to treat those toxic materials before discharging them to the environment. Wet Air Oxidation (WAO) is one of these new methods. This study casts light on the effect of initial pH on the WAO of benzene at different temperatures and pressures. It was found that at pH 6, a temperature of 260°C and a partial pressure of oxygen of 1.38 MPa around 97% degradation …  Lire la suite

This thesis addresses the problem of producing three-dimensional constrained Delaunay triangulated meshes from the sequential two dimensional MRI medical image slices. The approach is to generate the volumetric meshes of the scanned organs as a result of a several low-level tasks: image segmentation, connected component extraction, isosurfacing, image smoothing, mesh decimation and constrained Delaunay tetrahedralization. The proposed methodology produces a portable application that can be easily adapted and extended by researchers to tackle this problem. The application requires very minimal user intervention and can be used either independently or as a pre-processor to an adaptive mesh refinement system. Finite element …  Lire la suite

Une précédente étude de l’expression génétique des différents facteurs immunitaires régulé par l’activité neuronal a permis d’identifier la cytokine pro-inflammatoire Interféron gamma (IFNγ) comme étant un potentiel candidat. L’objectif de cet article est de déterminer le rôle de l’IFNγ dans la régulation des synapses corticales inhibitrices et excitatrices, ainsi que son impact au niveau comportemental en utilisant d’un modèle de rongeur IFNγ-KO.Afin d’examiner les effets à courts terme du traitement à l’IFNγ, nous avons réalisé une étude électrophysiologique des courants excitateurs glutamatergiques et des courant inhibiteurs GABAergiques sur des cultures de neurones dissociés provenant de cortex de rat. Le traitement …  Lire la suite

Les dérivés réactifs de l'oxygène (DRO) sont des molécules chimiquement réactives contenant de l'oxygène, formées par diverses réactions enzymatiques et non-enzymatiques. Bien qu'elles soient traditionnellement associées au stress oxydant et impliquées dans certaines pathologies, d'autres résultats suggèrent que les DRO effectuent aussi des signalisations physiologiques au sein de divers tissus humains. Cependant, leurs rôles dans le cerveau des vertébrés adultes sont peu connus. Par conséquent, l'objectif principal de cette thèse était de pallier à ce manque de compréhension. Le rôle de la régulation des DRO au niveau des synapses GABAergiques inhibitrices est particulièrement intéressant. Dans le cerveau adulte, la neurotransmission …  Lire la suite

Science and medicine are not objective or neutral fields of knowledge. Specifically, the medical discourse about people with disabilities has been historically shaped by elements like ideology, and moral, political and economic views. Proof of this, are methods for measuring intelligence, such as Craniometry and IQ testing, and the eugenic scientific theory and movement, which related "feeblemindedness" with gender, racial and social stereotypes, and the degeneration and lack of progress of societies. This work studies current judicial decisions of non-consented sterilization of people with cognitive disabilities of the United States, Canada and Colombia in a comparative perspective, and analyses the …  Lire la suite

Aviation and the internet are two conveniences without which the modern world would almost grind to a halt given our current dependence levels (on them). If both were to suddenly vanish, mankind would be thrown back to the late 19th century reminiscent of a world which was once a smaller place. Aviation plays a critical role in our daily life transporting man and material over vast distances in a relatively short period of time. A vital cog in this wheel is the airport that 'facilitates' the safe loading, unloading, take-off and landing of aircraft. For some time now, aircraft have …  Lire la suite

A cross-sectional survey was carried out to evaluate the nutritional correlates of growth in 93 HIV-infected children in the early and middle stages of infection. Also, as zinc is important for growth and immune function, foods commonly eaten by these children were evaluated for zinc content. Foods with relatively high zinc were identified in Uganda, and these food items were legumes and cereals. A high prevalence of stunting and wasting was found in HIV-infected children. The study also found that the frequency of past week oil/fat and staples consumption was non-significantly correlated to weight-for-height at the early stage, while household …  Lire la suite

Constructing and negotiating one’s identities is a central life task that continues across the lifespan and occurs within specific social, cultural, and historical contexts. For persons with impairments, dominant social beliefs and ideas embedded within these contexts, are likely to shape self-perceptions and the identities individuals construct. While negative stereotypes and ideas have historically been associated with disability, this diverse group of people has strived, both collectively and individually, to resist negative characterizations. One example of these efforts is the Disability Arts Movement and within the existing literature, we find evidence that creating and sharing art can help individuals with …  Lire la suite

Dissociation between memory for individual items and memory for associations has been reported in behavioral neurosciences, clinical populations and cognitive studies. At the brain level, this dissociation could reflect distinct patterns of activation for encoding and/or retrieval of items and associations. We used event-related functional Magnetic Resonance Imaging to assess neural correlates of item and associative encoding and retrieval in eighteen healthy subjects. During encoding, subjects memorized doubles (two identical images) and pairs (two different images). During retrieval, subjects made item recognition judgments (old versus new items) and associative recognition judgments (intact versus rearranged pairs). Greater hippocampal activation was observed …  Lire la suite