McGill University Thèses et mémoires par auteur commençant par F

Plant growth regulators and nitrogen fertilization have been associated with the increased incidence of fusarium head blight, a destructive disease of wheat (Triticum aestivum L.). In Canada, the major causal organism of this disease is Fusarium graminearum Schwabe, the conidial state of Gibberella zeae (Schw.) Petch. Most studies concerning the effect of plant growth regulators on fusarium head blight were conducted in fields with natural infection. The objective of this research was to evaluate the effect of growth regulators and nitrogen fertilizer on the incidence of fusarium head blight of wheat with artificial inoculations. A survey conducted in a field …  Lire la suite

The use of plastic mulches in producing red bell pepper (Capsicum annuum L.) is relatively new to Quebec and management techniques need to be further developed in terms of nitrogen (N) fertilization as well as insect and disease control. A research project was undertaken in the 1995 and 1996 growing seasons to compare peppers grown on black and on silver mulches, and fertigated using either the conventional method (weekly N-fertigated) or N-fertigated using diagnostic chlorophyll meter readings. Both fertigation treatments resulted in similar yields, although those fertilized according to the chlorophyll meter received 28 to 42 kg N/ha less than …  Lire la suite

It is undeniable that climatic changes have affected species distributions and adaptations, and considerable effort has been deployed in the last decades to understand their consequences on genetic variation. However, little is known about how climate changes affect evolution of developmental systems within species. To explore this question, I studied populations of the ant Monomorium emersoni in five Arizona Sky Islands. These populations have experienced a climatic warm-up following the last glaciation, which is predicted to further continue under anthropogenic climate change scenarios. Queens of this species have two morphs, winged and wingless, where they each represent a different life …  Lire la suite

L'incapacité des neurones du système nerveux central (CNS) adulte à régénérer après dommage peut conduire à des conséquences dévastatrices, qui se traduisent souvent par la perte permanente des fonctions sensorielles et motrices. Les inhibiteurs de croissance présents dans la myéline (MBGIs) ont été identifiés comme étant les acteurs principaux qui empêchent la régénération axonale dans le CNS. Des données récentes ont montré qu'un complexe de récepteurs, constitués par les récepteurs p75NTR, NgR1 et Lingo1, est activé par des MBGIs et initie la cascade de signalisation inhibitrice. Nous avons identifié une protéine sécrétée, appelée LGI1, capable d'interagir avec les membres de …  Lire la suite

Dans cette thèse, nous étudions la formation et les propriétés des cordes cosmiques dans différents scénarios. La thèse est structurée en deux chapitres principaux: un chapitre introductif fournissant le cadre théorique nécessaire, et un second chapitre comprenant quatre articles publiés. Les chapitres 2 à 4 se concentrent sur l'interaction entre les cordes cosmiques et un modèle de matière noire superfluide (SFDM). En utilisant une description en théorie effective de la superfluidité à température finie, nous commençons par dériver le modèle phénoménologique à deux fluides comme limite non relativiste de la théorie effective. Nous analysons ensuite l'impact d'une corde cosmique se …  Lire la suite

Les modèles de diffusion variationnelle (VDMs) ont récemment émergé comme de puissants cadres génératifs, capables de modéliser des distributions de données complexes avec une grande fidélité et flexibilité. Cette thèse explore les VDMs comme un cadre unifié pour les tâches génératives et discriminatives en imagerie médicale, en mettant l’accent sur la pertinence clinique, l’explicabilité et l’estimation de l’incertitude. Nous commençons par examiner les fondements théoriques des VDMs, en reliant des concepts issus de la modélisation générative, des modèles à variables latentes et des processus de diffusion stochastiques, et en contextualisant leur importance pour l’imagerie médicale. En nous appuyant sur cette …  Lire la suite

A method was developed for measuring the rate of leaching of lignin macromolecules from the fibre walls of unbleached kraft pulp fibres suspended in water. From a comparison of a theoretical analysis with experimental results, it was concluded that the leaching process was governed by a diffusion mechanism. Very low and widely polydisperse diffusion coefficients were observed for this system. The molecular weights of the leached lignins were found to increase with wash time. A comparison of the molecular dimensions with pore size indicated that a flat disk-like conformation, rather than a spherical conformation was appropriate for the lignin macromolecule. …  Lire la suite

The Historical Introduction relating to the various aspects of this investigation will be divided into the following parts: 1) Statistical study of the heterogeneity of paper, 2) Physical factors affecting paper heterogeneity, and 3) Correlation of the physical properties of paper with the degree of heterogeneity. [...]  Lire la suite

Maple sap was successfully transformed into maple syrup and maple syrup products by evaporation of water by microwave heating. Pulsed power supply with duty cycles of 100%, 75% and 60% were used for the microwave application. The dielectric properties of maple syrup at different moisture contents during the process were determined at 25$ sp circ$C. The products obtained were of excellent quality and were comparable to the highest grade prescribed by the industry. Pulsed power supply was found to have better efficiency of heating, but it increased the total time required for the process. The total time was also found …  Lire la suite

In a disjunctive reaction time (DRT) task each class of signals (Sa, sb, etc.) requires a different response (Ra, Rb, etc.). Some interest has recently been shown in disjunctive RT tasks in which successive trials follow each other in a continuous series (Sa-Ra, Sb-Rb, Sb-Rb, Sa-Ra, etc.). This type of experimental paradigm has made it possible to study the way in which various properties of the series affect speed of discriminative responses. Three such serial performance affects on DRT are explored in the present study: (a) vigilance affect, (b) relative frequency effect, and (c) a proactive effect. Some Serial Performance …  Lire la suite

Historically the Wilson cloud chamber was one of the earliest tools for studying nuclear reactions. This instrument, far from having been relegated to a museum shelf, is still indispensable in nuclear Physics laboratories. This is due to the unique amount of direct information which a single cloud chamber photograph can yield about a disintegration process. A cloud chamber has been in use at this university since the earliest days of the Radiation Laboratory.  Lire la suite

A total of 1,830 neutron induced disintegrations in N14 have been studied by cloud chamber techniques. These events were observed with incident particles of energies ranging from one to forty-eight Mev. Out of the 23 reactions which were energetically conceivable, 12 have been confirmed and discussed in the present work. The apparatus and experimental procedure have been described and photographs of typical events included.  Lire la suite

Interleukin-(IL)-9 is a pleiotropic cytokine secreted by activated Th2 cells. Interleukin-9 and the α-chain of the IL-9 receptor (IL-9Rα) have been shown to affect the differentiation pathway of various cell types including human T cells, eosinophils, and mast cells, all key players in allergic inflammation. However, there is little information regarding the differentiation effect of IL-9 on B cells. Specifically, there are no reports describing the expression of the IL-9Rα on human B lymphocytes. To gain a better understanding of the effect of IL-9 on human B lymphocytes and its role in the B-Th immune synapse in the germinal center, …  Lire la suite

Introduction: Communication of distressing news such as metastatic cancer is challenging for patients and doctors. During the course of their care, 60% of patients diagnosed with cancer will receive a palliative treatment, and it is not clear if patients understand the goals of treatment and the incurable nature of their cancer at that stage. Our goal was to design a simple questionnaire to assess, in a rapid manner, if patients with metastatic cancer are aware of the extent and prognosis of their disease. Methods: The first phase was a review of the literature, including 25 validated questionnaires used in clinical …  Lire la suite

This thesis uses a study of the relationship between Japanese archaeology and its social, political and economic context to explore the issue of relativism versus positivism in archaeological interpretation. This is done through (1) a historical analysis of the growth of Japanese archaeological work and buried cultural properties administration prior to and after 1945, (2) a description of how Japanese political and business elites have used archaeological sites and information from the Asuka area to create a symbol of the Japanese people's national identity and (3) a presentation of opinions of archaeologists working in the buried cultural properties administrative system, …  Lire la suite

In the CNS, one of the neurotrophin family members, brain-derived neurotrophic factor (BDNF), plays an important role in neuronal survival and synaptic plasticity. However, the underlying mechanisms mediating these events are less clear. One approach to identify potential mechanisms is to better characterize the localization of endogenous BDNF protein in the CNS. This thesis has explored the subcellular localization of endogenous BDNF protein in the adult rat CNS, and the functional consequences of this localization. First, we show that endogenous BDNF protein can accumulate in microvesicles isolated from brain synaptosomes. Consistent with this localization, immunocytochemical data reveals a punctate staining …  Lire la suite

Hayden, Patrick (Supervisor1)  Lire la suite

Cette thèse est un projet ethnographique sur la jeunesse musulmane américaine participant aux associations d'étudiants musulmans (MSA) sur trois campus universitaires dans le nord-est des États-Unis. Il soutient que les MSA sont des endroits discursifs à travers lesquels les étudiants américains musulmans font l'expérience de l'islam. Précisément, il montre comment les MSA, comme des endroits discursifs, offrent à ces jeunes l'occasion de formuler et de partager de manière introspective des hypothèses existentielles et théologiques particulières. Par exemple, j'examine comment l'espace MSA discursif permet aux sertains étudiants musulmans de se démarquer des pratiques et des croyances de la génération de leurs …  Lire la suite

Kainate-type ionotropic glutamate receptors (KA iGluRs) are ligand-gated ion-channels that play a key role in regulating both excitatory and inhibitory synaptic transmission. They are implicated in several CNS disorders including neuropathic pain, epilepsy and fear conditioning. Despite this, we have a very limited understanding of their basic structural and functional properties. In fact, much of what we know about the KAR comes from the closely-related AMPAR. Interestingly, the crystal structure of the agonist-binding domain of closely-related AMPARs confirmed the proposed bi-lobed structure and together with functional studies show that the extent of clamshell closure is agonist-dependent and directly correlated to …  Lire la suite

The measurement of the electron mobility in Cadmium Sulphide was attempted using a transit-time method in which the carrier transit time is determined from the waveshape of the transient current associated with the drift of electrons photo-generated at one electrode by a short pulse of strongly absorbed light. [...]  Lire la suite

Two deep-sea cores from the Labrador Sea have been examined using a variety of techniques. Sediments from the eastern levee of the North Atlantic Mid-Ocean Channel consist of spill-over turbidites interstratified with hemipelagic sediments and ice-rafted detritus which are correlatable with levee cores described in earlier studies. The same facies are found on the lower Labrador Slope except that, here, the amount of ice-rafted detritus in the hemipelagic facies is more variable. Compressibility tests have enabled an evaluation of the porosity-permeability character of the levee spill-over facies at deeper levels of burial. Organic- and inorganic carbon contents, shear strength and …  Lire la suite

Cette thèse détaille le développement de systèmes de lecture avancés et de techniques de traitement des signaux numériques (DSP) pour l'expérience ALBATROS (Array of Long Baseline Antennas for Taking Radio Observations from the Seventy-ninth Parallel). L'objectif scientifique principal d'ALBATROS est d'ouvrir la voie à de futures détections du signal 21 cm décalé vers le rouge des âges sombres cosmiques et de l'époque de la réionisation (EoR) en créant des cartes de haute fidélité des avant-plans astrophysiques à basse fréquence.Le travail présenté aborde des aspects critiques de la collecte des données ALBATROS et du pipeline d'analyse. En ce qui concerne la …  Lire la suite

Zilic, Z. (Supervisor)  Lire la suite

A design for a unified model based on the hypermedia paradigm is proposed as a means to a better synergism of the functionalities of different knowledge manipulation tools. A survey of past and present hypermdia systems has been achieved, and their characteristics examined. Intelligent hypermedia-based system architectures have been evaluated, from which functional requirements for a unified architecture have been derived. Equivalence mappings based on Petri nets, that equate the structure and behavior of hypermedia networks and expert systems in a loose way, have ben developed. A unified model, that synthesizes the structural and behavioral equivalences among different knowledge representations …  Lire la suite

Damiano, Pasini, (Supervisor1)  Lire la suite

Failure of homologous synapsis during meiotic prophase triggers transcriptional repression termed meiotic silencing of unsynapsed chromatin (MSUC). In spermatogenesis the X and Y chromosomes incompletely synapse and are thus, silenced by MSUC, while the consequences of asynapsis of autosomes are not fully understood. To establish the dynamics of autosomal asynapsis and the proportion of spermatocytes with meiotic silencing of unsynapsed autosomes, we examined two marks of unsynapsed chromatin, histone variants γH2A.X and H3.3, in the spermatocytes of Robertsonian (Rb) translocation carrier mice using immunolocalization with fluorescent antibodies and chromatin immunoprecipitation (ChIP) assays. We also tested the hypothesis that MSUC marks …  Lire la suite

Résumé Les implants en titane sont facilement contaminés par la salive durant l'intervention chirurgicale ou après la mise en place. Cette contamination risque de modifier les caractéristiques de la surface et d'avoir une incidence sur le processus d'ostéointégration, ce qui peut mener à une péri-implantite et à la perte de l'implant. Même si plusieurs substances chimiques sont souvent utilisées pour la décontamination des implants, leur effet exact reste mal connu. La détermination de leurs effets sur les contaminants du titane et de la bouche est donc cruciale lorsqu'il s'agit de développer des traitements améliorés de décontamination des implants dentaires en …  Lire la suite

This thesis presents an implementation of supervised learning performed with a stochastic neural net, as applied to a classification of business firms based on financial statements and ratios. The general Boltzmann Machine Algorithm is presented in detail, as well as the specific version designed for this application. We describe in detail several classifications that we attempted to reproduce, and some of the different possible ways of encoding the data issued from the income statements and the balance sheet. The results are shown to depend on the chosen encoding. We also confirm that the neural net behaves better when it is …  Lire la suite

Adrenal glands from five species of South African antelope; cape eland (Taurotragus o.oryx), gemsbok (Oryx g.gazella), southern greater kudu (Tragelaphus s.strepsiceros), red hartebeest (Alcelaphus buselaphus caama), springbok (Antidorcas marsupialis hofmeyri), were collected from 43 trophy-hunted males for histology and corticosteroid analysis. The gross anatomy of the adrenal glands are species-specific, with the left gland being most variable. There were differences found in the number of cortex capsular layers and zona glomerulosa between species. Extensive capsular trabeculae penetrates deep into the cortex in only the largest antelope, i.e. eland and gemsbok, and are representative of these species. In all species the …  Lire la suite

Mitchell, Claudia A. (Supervisor2)  Lire la suite

Loss of germ cells that entered meiosis at different developmental stages was compared. Mice were injected with BrdU at 13.3, 14.3 or 15.3 days post coitum (dpc) and sacrificed either 3 days after BrdU injection or 4 days post partum (dpp). BrdU-labeled germ cells were detected in ovarian sections through double immunofluorescent staining for BrdU and either GCNA-1 or MVH as a germ cell marker. The results show that the loss of germ cells that entered meiosis at 13.3 or 15.3 dpc was excessive compared to the loss of total germ cells. Such preferential elimination was not found for germ …  Lire la suite

Lyster, Roy (Supervisor)  Lire la suite

This report presents the results of a laboratory investigation of the influence of the corrosion process on the flexural capacity such as strength, deflection and steel and concrete strains in reinforced concrete beams. Examination of the behaviour of crack development was also examined. Fourteen simply supported concrete beams were cast and subjected to two third point concentrated loads, increased monotonically until failure. The strength, strain and crack development data were recorded to assess the corrosion rate and its effect on the steel bars. An electrochemical system was used to achieve the different corrosion levels. The specimens were immersed in a …  Lire la suite

Many concrete structures built in the 1960s and 1970s are now showing significant signs of deterioration. The Dickson Bridge, constructed in 1959, was decommissioned by the City of Montreal in 1994 due to extensive deterioration of the bridge deck. A collaborative research investigation was carried out in 1997--8 on the bridge to: (a) assess the corrosion induced damage in the concrete deck, (b) identify the causes of the observed deterioration, and (c) investigate suitable test techniques for predicting corrosion. The results of this collaborative research program between McGill University and The Queen's University of Belfast, Northern Ireland, and some industrial …  Lire la suite

ContexteLa résection de tumeurs subpiales adjacentes à des zones cérébrales critiques est l'une des procédures chirurgicales aux enjeux les plus élevés, qui manque de possibilités de pratique délibérée sûre. De plus, l'évaluation basée sur la performance dans l'apprentissage de la neurochirurgie est inefficace et vulnérable à la subjectivité. En utilisant l'intelligence artificielle (IA) pour classifier l'expertise psychomotrice neurochirurgicale, nous avons développé le premier tuteur alimenté par l'IA dans la formation neurochirurgicale par simulation, connu sous le nom d'Assistant Opératoire Virtuel (VOA), pour augmenter la formation à l'acquisition de compétences techniques en fournissant un retour intelligent.ObjectifsDéterminer comment l'apprentissage avec le VOA …  Lire la suite

L’anticorps conjugué à un médicament (ADC) Trastuzumab deruxtecan (T-DXd) est un traitement hautement efficace pour les cancers du sein exprimant HER2, y compris ceux présentant de faibles niveaux de HER2. Cependant, une difficulté clinique majeure est la résistance thérapeutique, qui limite le bénéfice à long terme du médicament. Les processus moléculaires spécifiques qui conduisent à cette résistance ne sont pas complètement compris.L’objectif de cette étude était de modéliser et de caractériser le développement de la résistance au T-DXd. Pour ce faire, un panel de modèles de xénogreffes dérivées de patients (PDX) a été utilisé, représentant l’éventail de l’expression de HER2 …  Lire la suite

Katz, M.  Lire la suite

Dawson, C. (Supervisors)  Lire la suite

Latin America has experienced a series of political changes since the neoliberal turn and the re-opening of competitive elections in the 1980s and 1990s. At the core lies citizens’ relationship with political parties, a key prerequisite for democratic politics. Applying an age-cohort-period analysis, we investigate the place parties hold in citizens’ minds across all 18 countries in the region over a period of 14 years (2006-2020). We find important age, period, and cohort effects, suggesting that partisan learning does not stem from differences in regime type but from the clarity of the choices to which voters are exposed in the …  Lire la suite

The combination of pretransplant donor specific transfusion (DST) and cyclosporin (Cys) has proven to be an effective mode of immunomodulation in numerous allograft models. Our experiments were designed to study the effect of clinically applicable protocols using DST and low-dose cyclosporin in an heterotopic, fully allogenic model of small bowel transplantation in the rat. A 1 ml systemic DST 24 hours pretransplant with Cys (10 mg/kg day $-$1, 5 mg/kg POD 0 to 7, 2.5 mg/kg POD 8 to 14) was shown to be more effective than DST or Cys alone in prolonging graft survival (p $<$ 0.05). Adding successive …  Lire la suite

The Cuban Crisis of October 22-28, 1962, pitted against each other the two world giants who have weapons that can destroy each other and at the same time all of human society. The suspenseful events of that week brought the world to the brink of World War III. As the crisis receded upon agreement of the Soviet Union to remove the offensive missiles from Cuba and by the States to refrain, under certain conditions, from invading Cuba, so did the memory of that week. [...]  Lire la suite

There are increasing numbers of preterm children of very low and extremely low birth weights surviving due to advances in neonatal care. The majority of these children attend mainstream classrooms and perform in the low average range on cognitive measures compared to peers. However, outcome studies document a range of subtle, clinically important impairments in their motor, visual-motor and visual perceptual performance compared to peers. The impact of these impairments on a complex, occupational task such as handwriting performance has never been investigated in the preterm population using an objective measure, except through parent or teacher questionnaires. The primary objective …  Lire la suite

La traduction des découvertes biologiques fondamentales en applications cliniques améliorant la santé humaine reste une entreprise lente, coûteuse et encline à l'échec, malgré les importants progrès de la génétique et de la biologie moléculaire. Les échecs dans le processus de développement des médicaments ont des coûts énormes, dont ceux de causer préjudice à des patients-volontaires et de gaspiller des ressources rares qui pourraient servir à d'autres sphères de recherche plus prometteuses. Afin de comprendre pourquoi tant de médicaments en apparence prometteurs au stade des études précliniques obtiennent de si mauvais résultats lors d'essais cliniques postérieurs, cette thèse élabore une méthode …  Lire la suite

Despite substantial research investment, and a growing understanding of the pathophysiology of pain, there has been little progress in developing novel, efficacious and safe analgesics. Translational attrition–defined as a failure to show that a promising drug is useful–exacts a significant toll. It exposes patients in trials to unsafe and ineffective drugs, diverts funds away from other potentially beneficial avenues of research, and impacts health care systems by increasing the price of drugs. This thesis explores dynamics at three junctures of the drug development pipeline: during preclinical testing, at the transition between preclinical and clinical testing and at the transition of …  Lire la suite

Several basic papers have been written by students at the Institute of Islamic Studies dealing with political-religious movements in Indonesia during the twentieth century. This study of the Persatuan (abbreviated Persis) is not intended to take issue with these studies, but rather to supplement them and provide a fuller picture of Indonesian Islam in the twentieth century. [...]  Lire la suite