McGill University Thèses et mémoires par auteur commençant par R

Zinde-Walsh, Victoria (Internal/Supervisor)  Lire la suite

The first description of an American field cricket of the genus Gryllus was published by Fabricius in 1775 when he described Acheta assimilis from Jamaica. By beginning of the 20th century no less than forty-seven New World species of Gryllus had been described (Blatchley, 1903), thirty-three of these were as recognized valid by Kirby (1906). Practically all the early workers on this group considered macro-morphology only: such characters as size, coloration, wing venation, body proportions, number and relative length of tibial spines, and the length of tegmina, wings, ovipositor and the hind femora.  Lire la suite

La maladie de Parkinson (MP) est une affection neurodégénérative progressive et hautement hétérogène, caractérisée par la perte de neurones dopaminergiques dans la substance noire pars compacte (SNc), entraînant une dérégulation de la voie nigrostriatale et des circuits des ganglions de la base. Bien que la MP soit classiquement définie par des troubles moteurs, une phase prodromique substantiellement, pouvant durer plus de 20 ans, est cliniquement caractérisée par une symptomatologie non motrice incluant le trouble du comportement en sommeil paradoxal (RBD), le dysfonctionnement gastro-intestinal, des caractéristiques dépressives et une perturbation circadienne. Les facteurs responsables de ces manifestations précoces restent inconnus ; …  Lire la suite

Leishmaniasis is a disease endemic to 88 countries that affects 12 million people worldwide. The causative agents are species of the genus Leishmania, with the clinical manifestation of this disease depending on the species. Once in the host, the parasite lives inside various cell types including macrophages, and must modulate the host cell functions to survive. Host macrophages are capable of detecting various foreign molecules and mounting cellular responses. Macrophages engulf their target pathogen and, through the maturation of the phagolysosome, will destroy it. To prevent aberrant activation of the cell, macrophages use protein tyrosine phosphatases (PTPs) to return activation …  Lire la suite

The ubiquitous mold Aspergillus fumigatus is the causative agent of a wide range of diseases consisting of invasive and non-invasive pulmonary infections that are associated with a high rate of mortality. Immunosuppressed patients are at high risk of developing invasive pulmonary aspergillosis, characterized by a progressive necrotizing pneumonitis which, if untreated, can disseminate to other organs. Patients with impaired lung function, such as those with cystic fibrosis, are at high risk of developing a chronic non-invasive infection of the airways that is associated with declining lung function, frequent hospitalizations and a high rate of mortality. Current therapeutics for both manifestations …  Lire la suite

Huk, Olga (Advisor)  Lire la suite

He awoke in the fuzzy half-dark of his room to muffled little noises. From the kitchen only a passage width away came the clink and the scraping of a pot in the sink, the discreet slushing rise in pitch of the tap water filling the pot, the tempered shuffle and heel click on the linoleum of his mother’s moving about. Up already, he thought. He listened hard for a moment. Her voice, still as young and fresh as a spring, gurgled in an endless flow of Yiddish past his closed door and into his room, punctuated every now and then …  Lire la suite

This thesis focuses on diffusion channel design for broccoli storage, an important cash crop and consumer commodity in Canada. Experiments were first conducted to determine the respiration rate of broccoli in modified atmosphere conditions created by the produce metabolic activity inside closed chambers, at four different temperatures in the cold room of 3, 7, 13, and 24$ sp circ$C. The respiration rate decreased with a reduction of O$ sb2$ concentration inside the chamber. A model to predict the respiration rate of broccoli as a function of O$ sb2$ concentration at different temperatures was developed. Experiments were then carried out to …  Lire la suite

Le soudage par transmission laser est une méthode pour joindre les plastiques qui prend avantage du fait que la majorité des thermoplastiques sont transparent aux infrarouges. Durant le procédé, un faisceau laser passe à travers une région transparente pour aller en frapper une autre rendue absorbante au moyen d'additifs tel que le noir de carbone. L'énergie laser absorbée est ensuite convertie en chaleur. Ce dégagement de chaleur permet de souder l'interface entre les deux parties en fondant le polymère. Dans le présent travail, une nouvelle technique de soudage par transmission laser basée sur la réfraction a été utilisée pour souder …  Lire la suite

This thesis addresses the problem of simultaneously transmitting several data signals across a single channel. For this purpose, a transmultiplexer that uses modulated filter banks is studied. Modulated filter banks comprise filters that are bandpass versions of a lowpass prototype. The filters serve to assign portions of the channel bandwidth to the data signals. The impulse responses of the filters are parameterized by a center frequency, delay and phase factor. The objectives in configuring modulated filter banks are to use the full channel bandwidth for transmission, cancel crosstalk between signals (arises when signals share bandwidth) and cancel intersymbol interference in …  Lire la suite

Kir3 channels contain multiple Gβγ binding sites within their N- and C-terminal domains. However, the channel opens when only a few binding sites are occupied by Gβγ, suggesting that some sites subserve roles other than agonist-dependent interactions. We delineated these roles on Kir3.2 channels with mutations in their N- or C-terminal Gβγ binding sites. The N-terminal mutant displayed a high affinity site for Gβγ but this affinity was reduced with the C-terminal mutant. Also, the N-, but not the C-terminal mutant could traffic to the cell surface. Carbachol stimulation of the muscarinic M2 receptor, resulted in conformational changes between Gβγ …  Lire la suite

Le molybdène (Mo) et l'alliage TZM présentent des propriétés mécaniques et thermiques prometteuses, ce qui en font des matériaux candidats idéaux pour une grande variété d'applications industrielles. La nature réfractaire de ces matériaux limite leur formabilité à des pièces de géométrie simple par la voie de la métallurgie des poudres. Le processus de fabrication additive (AM, en anglais) par fusion laser sur lit de poudre (LPBF, en anglais) est une technique de fabrication moderne qui permet de fabriquer des pièces de forme presque nette avec des géométries et des caractéristiques internes complexes. Quelques études dans la littérature font état d'un …  Lire la suite

The term "bark" is applied in common parlance to denote the material that surrounds the woody substance (xylem) in a mature tree. It is thus situated outside the cambium which is the living tissue of a growing tree. The anatomical structure of bark is rather complex but in general it can be said that the bark tissue is composed of different kinds of cella, such as sieve, longitudinal parenchyma, ray parenchyma, fiber cella, etc., some of which are also typical of the wood tissue. The physiological function of these tissue elememts in the bark is mainly concerned with the translocation …  Lire la suite

Conventional numerical methods such as the Finite Element Method (FEM) and Finite Difference Method (FDM) have been employed to solve electrostatics and magnetostatics problems involving Partial Differential Equations (PDEs). With the recent boom in deep learning, alternative ways to solve such PDEs subject to boundary value constraints have been proposed and implemented, in contrast to classical numerical solvers. One such entity is a Graph Neural Network (GNN), which precisely depicts the internodal connectivity in a graph structure comprising nodes and edges. At the structural level, a GNN is analogous to the tessellations (here, triangular simplices) of a finite element mesh. …  Lire la suite

L'evaporation d'eau d'une couche mince (film) de la liqueur noire a ete etudiee en utilisant l'injection par jet; d'air chaud ou de la vapeur. L'epaisseur du film est variee entre 0.8 et 1.2 mm et la temperature du sechage est echelonnee de 180 a 250$ sp circ$C. Autres parametres ont ete etudies; le pourcentage du solide dans la liqueur noire (60-74%) et le debit du fluide du sechage (0.8-1.0 kg/s m$ sp2$). Les caracteristiques du transfert du systeme de sechage ont ete determinees en utilisant la technique de sublimation du naphthalene. Les procedures et les techniques experimentales ont ete verifiees …  Lire la suite

Cell physiology and survival critically depend on mechanisms that regulate the development and maintenance of polarity, which is manifested by the asymmetric distribution of proteins or organelles to specific sub-cellular compartments. A prime example of this is observed in mammalian photoreceptor cells, where the proteins involved in the phototransduction cascade are housed exclusively in a specialized primary cilium called the outer segment (OS). Despite the importance of polarized protein trafficking in photoreceptor physiology and disease, the mechanisms regulating this process remain largely unknown. Recent studies have shown that Numb, an endocytic adapter protein, is an essential regulator of directional protein …  Lire la suite

The propagation of their own kind seems to be the fundamental aim of all forms of life. It is equally true that competition, of whatever nature it may be, threatens to curtail the overwhelming increase of any one kind of life. In other words, there is a struggle for existence -- a struggle that attains a tremendous magnitude in the lives of orgasims living as parasites on others. A parasite that exploits its host to the point of extinction is, itself, in danger of annihilation. Hence, the only motto for any successful parasite is the well being of its host.  Lire la suite

In an article on binocular perspective, Verhoff (1925) made passing mention of his observation that if the centre of a bent line were viewed "steadily with one eye for a short time" and the eye then fixed on a straight line, the latter appeared bent in the opposite direction. Verhoff suggested that this effect might be due to “unconscious mental comparison” of the second line with the after-image of the first. Gibson (1933) found that Ss who had worn lenses which made verticals appear curved remarked, on removing the glasses, that verticals now appeared curved in the opposite direction.  Lire la suite

Salmonella spp. is a widely distributed Gram-negative foodborne pathogen that is a major cause of foodborne outbreaks in North America. The Public Health Agency of Canada (PHAC) estimates that approximately 88,000 Canadians are affected by foodborne Salmonellosis annually. In recent years, contaminated fresh produce has emerged as an important source of salmonellosis. Standardized culture methods for Salmonella spp. are considered as the "gold standard" in food diagnostics and are still in use today; however, they are laborious, time-consuming and must be confirmed by secondary biochemical tests. Immunoassays are the most commonly used rapid methods for the detection of Salmonella in …  Lire la suite

Les insectes du sol jouent un rôle important en affectant l'écosystème végétal. Les racines sont les principales victimes des insectes du sol car ceux-ci sont attirées par le dioxyde de carbone dégagé par la respiration des racines. La plupart des insectes causant des dommages aux racinaires appartiennent à des ordres d'insectes communs tels que les lépidoptères, les diptères, les homoptères, les hyménoptères et les coléoptères. Parmi eux, les taupins (Coleoptera: Elateridae), les vers blancs et les larves de diptères (Diptera: Anthomyiidae) sont considérés comme les ravageurs les plus importants des grandes cultures. La mesure de lutte la plus courante contre …  Lire la suite

The experimental work of this thesis can be divided into two distinct parts. The first part is a continuation of the investigation of the isotopic exchange reaction between x-iodostearic acid monolayers and substrate iodide ions. The second part is a study of the effect of various substituents in the hydrocarbon chain of stearic acid on the mechanical properties of the respective monolayers.  Lire la suite

La radiothérapie stéréotaxique corporelle (RSC) est actuellement l’alternative pour les patients inopérables souffrant du cancer du poumon non à petites cellules (CPNPC) de stade précoce ou oligométastatique. Malheureusement, une minorité de patients ne bénéficie pas du traitement. Quoique les médecins utilisent des variables cliniques et des traits radiologiques sémantiques pour decider du bon traitement, les images médicales contiennent une richesse de détails pathophysiologiques pouvant être extraits et appliqués à des systèmes de soutien clinique, sous forme d’algorithmes and de biomarquers predictifs. De plus, tandis que quelques traits radiomiques ont démontré un potentiel pour predire les résultats des tumeurs CPNPC traitées …  Lire la suite

Human seminal plasma contains a factor(s) which preferentially suppress the release of FSH from the pituitary. The active factor (inhibin) was isolated and purified to homogeneity by ion exchange chromatography, molecular sieving and high pressure liquid chromatography. The purified peptide on gel electrophoresis at pH 4.5 rapidly migrated as a single component. The purified peptide has a mass of approximately 5000 daltons. The amino acid composition showed a high proportion of basic amino acids and absence of aromatic residues and sugars. The human seminal plasma peptide with inhibin-like activity has been characterized and its partial amino acid sequence has been …  Lire la suite

The primary objective of this thesis was to develop a system through which precision spraying of herbicides could be applied to a corn field at an early post-emergence stage of development. The initial hypotheses underlying this thesis were that it was possible to: 1) capture a series of digital images using a tractor-mounted camera; 2) tag these images using a Global Positioning System (GPS); 3) develop an algorithm to detect weeds in an image; 4) develop a weed map using a series of images tagged with the presence or absence of weeds; and 5) significantly reduce the amount of spraying …  Lire la suite

Thulium ions (Tm3+) provide an effective means for developing fiber lasers at a wide range of wavelengths. Additionally, the extended transmission window of ZBLAN glass allows for operation well into the mid-infrared range. This thesis presents the design of several single and multi-wavelength Tm3+:ZBLAN fiber lasers.First, an optimized laser cavity operating around 1480 nm is designed by measuring several different cavity configurations and lengths of gain fiber. Using a 34 cm length of gain fiber and a 4% Fresnel air reflection as the output mirror/coupler, 32% conversion efficiency is obtained, with a threshold pump power of 400 mW and a …  Lire la suite

Currently, Afghan school principals are in the vulnerable situation of not being fully capable of responding to a complex school context. This is because there is no program of studies at the university level to prepare them for this position even though school principals have a significant leadership role. They must hold the entire school community accountable for the provision of access to quality education while providing direct support to assistant principals, head teachers, and teachers to achieve the desired learning outcomes for their students. In this study, I considered the evolution of Afghan school principals’ leadership practices in relation …  Lire la suite

As there is a shortage of black foster homes, a number of black children are placed in care with white foster parents. The purpose of the present study was to find out if there is any difference in the self-esteem of those black children placed in foster care with black parents and of those with white parents. This study asks whether the black f05­ter child in the black home feels and thinks differently about himself than the black child in the white home. To the knowledge of the re­searchers, there have not been any studies examining whether the racial background …  Lire la suite

The significance with wbich ACh is attributed in the role of a neurotransmitter is reviewed.The sparcity of the chemical evidence used to characterize ACh is described and this evidence is criticised. The difficulties which arise by assuming a general transmitter function for ACh are discussed and the alternatives are reviewed.It is pointed out that many cholinergie materials are present in the brain and ACh itself is often present in very small amounts.  Lire la suite

Over fifty cell types were examined under the light microscope after staining of rat tissues with the periodic acid - Schiff technique for detection of glycoproteins, and colloidal iron at low pH for detection of acidic carbohydrates. With both techniques, nearly all cells investigated were outlined by a thin band of stained material. In epithelia, the stained layer was usually interrupted where two adjacent plasma membranes fused to form tight junctions. This finding indicated that the layer was not part of the plasma membrane itself but rather a "cell coat" located on its outer surface. [...]  Lire la suite

DNA methylation is a vital component of several mammalian genome functions such as X-inactivation, allele and tissue specific gene expression, parental imprinting, and condensation of transcriptionally inactive chromatin. Aberrant post developmental fluctuations in the levels of DNA methylation and patterns of DNA methylation are commonly observed in transformed or cancerous cells. Proper control over the process of DNA methylation appears to be essential for proper cellular function, however the regulation of the expression of DNA MeTase has remained only loosely elucidated and is still debatable. Chapter 1 presents the complete genomic structure of the human dnmt1 gene which provides an …  Lire la suite

Mounting biochemical and immunohistochemical evidence implicates Caspase 6 (Casp6) activation as an early event in familial and sporadic Alzheimer disease (AD). Given the need for early AD diagnosis and the ample evidence implicating the activation of Casp6 as an initiating event in AD, we propose to investigate if Casp6 activity in the cerebrospinal fluid (CSF) measured by Tau cleaved by Casp6 protein, may serve as a biomarker for early AD. To address our hypothesis, we designed a sandwich enzyme-linked immunosorbent assay (ELISA), which specifically detects tau protein that has been cleaved by Casp6. This sandwich ELISA was used to detect …  Lire la suite

Les carcinomes des kératinocytes (CK) sont les cancers les plus fréquents dans le monde. Il existe deux principaux types de CK : le carcinome basocellulaire (CBC) et le carcinome épidermoïde cutané (CEC). À ce jour, peu de biomarqueurs prognostiques et thérapeutiques fiables pour ces cancers sont disponibles. De plus, il existe peu d’alternatives efficaces, tolérables et abordables aux interventions chirurgicales pour gérer le CBC et le CEC. Par exemple, les rétinoïdes ont été étudiés comme traitements et agents prophylaxies contre le CK mais les mécanismes de résistance limitent leur application clinique. L’antigène PRAME (Preferentially Expressed Antigen in Melanoma) est un …  Lire la suite

This thesis presents a multidisciplinary effort towards closed loop glucose control for diabetes management and offers contributions to three domains related to the topic. First, an introduction is given to the historical, physiological and mathematical perspectives of diabetes mellitus and closed loop glucose control. Next, a reference design for validation of closed loop glucose control strategies is proposed to incorporate the safety critical constraints of embedded biomedical systems with special emphasis on closed loop insulin control. Glucose-insulin kinetics models are typically designed based on hybrid approaches leveraging theoretical knowledge and empirical data. As a result model parameters are generalized to …  Lire la suite

d'Anglejan, Bruno (Supervisor)  Lire la suite

Publicists, scholars, and practitioners of international law have yet to produce a sustained analysis of the law of war as applied to armed conflict in outer space. Though no reported cases of armed conflict in space exist, the principal spacefaring nations have contemplated space warfare for decades. Concluding that the general legal regime regulating means and methods of warfare will apply to space combat, should it occur, this thesis attempts a preliminary examination. Chapter One presents a hypothetical space warfare scenario, followed by a chapter on the history of space militarization with a review of existing (and foreseeable) technology useful …  Lire la suite

Zilic, Zeljko (Supervisor1)  Lire la suite

Gravity currents occur when a dense fluid intrudes into a lighter ambient. The density contrast is the buoyancy source produced by either an instantaneous release of dense fluid or a continuous flux of buoyancy. These flows occur in a wide range of geophysical and engineering contexts, including turbidity currents generated by submarine landslides and dense discharges from wastewater effluents and desalination brines. Submarine landslides triggered by storm surges and earthquakes can produce turbidity currents that travel along the seabed, transporting sediment and exerting significant forces on offshore infrastructure. Similarly, wastewater effluent and desalination brines can significantly impact submarine environments and …  Lire la suite

Perez-Aleman, Paola (Supervisor1)  Lire la suite