McGill University Thèses et mémoires par auteur commençant par X

Situées dans le rein, les cellules juxtaglomérulaires (JG) sont la principale source de rénine active circulante de l'organisme, une protéase qui catalyse l'étape limitante du système rénine-angiotensine (SRA). La voie du SRA conduit à la production de peptides appelés angiotensine, un puissant régulateur en sels, fluide et pression artérielle. Dans les cellules JG, la rénine est tout d'abord synthétisée sous forme de zymogène inactive nommé prorénine puis est transportée à l'intérieur de vésicules denses semblables à des lysosomes sécrétoires où elle est activée par un mécanisme inconnu à ce jour.En effet, la rareté des cellules à rénine (représentant 1/100e à …  Lire la suite

La zinc métalloprotéase STE24 (ZMPSTE24) est une zinc métalloprotéase transmembranaire humaine située dans la membrane nucléaire. Il provoque la maturation de la prelamine A farnésylée en lamine A mature qui est une composante structurelle de la lamine nucléaire. Des études biochimiques ont demontré un lien entre l' accumulation de la prelamine A (soit en raison des mutations qui empêchent la prelamine A d'étre transformée soit en raison d'une inactivité du ZMPSTE24) et la sénescence cellulaire. Il a déjà été démontré que la sénescence provoquée par l'accumulation de la prelamine a des propriétés anti-tumorales. Il n'existe actuellement aucun composé robuste pouvant …  Lire la suite

Le syndrome douloureux régional complexe (SDRC) est une douleur chronique sévère semblable à la douleur neuropathique, et se caractérise par la présence de douleur spontanée et évoquée par stimulation, des anomalies vasculaires, des changements sudomoteurs et des anomalies ossseuses et musculaires. Les recherches récentes suggèrent que les processus d'ischémie sont impliqués dans les mécanismes de la douleur du syndrome SDRC et particulièrement pour le syndrome SDRC de type I, dans lequel il n´y a pas de lésion de nerf majeure identifiable. On pense que l'ischémie chronique dans les membres des patients SDRC est reliée à l'efficacité des traitements anti-sympathetiques analgésique …  Lire la suite

The Sexuality Education program in Québec has been mandated across all schools in the province, however its English-language content had not yet been evaluated in the context of evidence-based practices. The present study used content analysis to explore the efficacy of Québec’s Sexuality Education content by determining how well it follows established guidelines. This research was grounded in a constructivist Intersectionality-Based Policy Analysis theoretical approach, rooted in critical policy studies. English-language Sexuality Education program documents were compared with UNESCO’s International technical guidance on sexuality education. A framework analysis approach to data analysis allowed themes to emerge from the data inductively …  Lire la suite

Human type I interferons offer a relevant system to examine cell-specific inducible gene expression. Interferon genes are transcriptionally activated in a variety of cell types following induction by synthetic double-stranded RNA (poly I:C) and viruses. A transient expression system was developed which permits regulated expression of different IFN-CAT (chloramphenicol acetyltransferase) hybrid genes in human cells. Using this system in vivo competition assays identified positive and negative cellular factors interacting with the IFN-$ beta$ promoter. A factor that recognizes negative upstream regulatory sequences was also identified in uninduced myeloid cell extracts. Complementary studies demonstrated that transcription of the IFN-$ beta$ gene …  Lire la suite

The protection regimes (international human rights law, international criminal law and international humanitarian law) are true expressions of the utopian ideals of the international community in trying to deal with mass human rights violations and atrocities. These expressions, however, can create hierarchies in the protection that is awarded and in a sense create categories of exclusion, rather than categories of protection. The subaltern outside these categories, the one that is not protected must be recognized. By using the definition of genocide, more specifically the mental component conceptualised in the Genocide Convention, the aim of this paper is to argue that …  Lire la suite

Metabolic syndrome and diabetes mellitus are increasing rapidly recently. Pancreas regeneration and replication of β-cell are some of the challenges that medical doctors and researchers face today. Cellular communication network factor 5 (CCN5) is a matricellular protein, the expression of which is under the regulation of Wnt signaling and IGF-1. Our previous characterization supports the notion that CCN5 promotes the proliferation and survival of pancreatic β-cells leading to metabolic benefits. To examine the role of endogenous CCN5 in metabolism and specifically in pancreatic islets and adipose tissues we generated total CCN5 knockout mice and fed them either with a normal …  Lire la suite

Stroke is a leading cause of disability for adults. Several studies confirm cognitive impairment in persons following stroke. Every stroke patient should have rapid access to cognitive screening and evaluation. In this study, Rasch analysis was used to determine the suitability of the telephone version of the Mini-Mental State Examination (MMSE) in screening for cognitive impairment in persons with stroke. The specific objectives were to determine the range of difficulty represented by the items of the telephone version of the MMSE, to identify the hierarchy of item difficulty and to compare the French and English versions of the test. Rasch …  Lire la suite

Popovich, Milica (Supervisor2)  Lire la suite

Les références de fréquence sont nécessaires dans tous les appareils électroniques modernes, incluant téléphones mobiles, ordinateurs personnels et instruments médicaux. Les applications mobiles requièrent des oscillateurs à coûts réduits, faible complexité et grande capacité d'intégration pour une consommation faible. Ceci a induit, en particulier, un intérêt considérable pour les résonateurs radiofréquences (RF) 'MicroElectroMechanical Systems (MEMS)' produits à grande échelle. Un défi important pour les résonateurs MEMS est d'avoir une stabilité en température comparable avec les résonateurs quartz.La première partie de cette Thèse se concentre sur le développement des résonateurs MEMS du type 'Free-Free beam' avec PolyMUMPS, un processus commercial à …  Lire la suite

Davies, David (Supervisor1)  Lire la suite

Ultrafast optical signal processing, which shares the same fundamental principles of electrical signal processing, can realize numerous important functionalities required in both academic research and industry. Due to the extremely fast processing speed, all-optical signal processing and pulse shaping have been widely used in ultrafast telecommunication networks, photonically-assisted RFlmicro-meter waveform generation, microscopy, biophotonics, and studies on transient and nonlinear properties of atoms and molecules. In this thesis, we investigate two types of optical spectrally-periodic (SP) filters that can be fabricated on planar lightwave circuits (PLC) to perform pulse repetition rate multiplication (PRRM) and arbitrary optical waveform generation (AOWG). First, we …  Lire la suite

A systematic analysis of all-optical gain-clamped L-band EDFAs for long-haul DWDM transmission systems is presented in this thesis. A full numerical model is used to simulate and fully characterize the performance and properties of single-stage and two-stage EDFAs. We focus on two configurations of two-stage L-band EDFAs with gain-clamped characteristics using partial gain-clamping. Partial gain-clamping is obtained by forming a fiber grating laser in either the first or the second stage of the two-stage EDFA. From our simulation and experimental results, we conclude the following: (1) a good gain-clamping effect can be achieved by partially gain-clamped configurations in which only …  Lire la suite

Insulin resistance, a harbinger of the metabolic syndrome, is a state of compromised hormonal response resulting from the dysregulation of a wide range of insulin-controlled cellular processes. However, how insulin affects cellular energy metabolism via long-term transcriptional regulation and whether boosting mitochondrial function alleviates insulin resistance remains to be elucidated. Herein, I reveal that insulin directly enhances the activity of the nuclear receptor ERRα via a GSK3β/FBXW7 signaling axis. Liver-specific deletion of GSK3β or FBXW7 and mice harboring mutations of ERRα phosphosites (ERRα3SA) co-targeted by GSK3β/FBXW7 result in accumulated ERRα proteins that no longer respond to fluctuating insulin level. ERRα3SA …  Lire la suite

Mobile applications (also called apps) have greatly extended and innovated users' daily tasks. The mobile programming model features event-driven execution, rapid changing APIs (about three generations per year) and ubiquitous accesses to user's personal data. These features enrich app functionalities but also give rise to many new software problems that impact performance or damage user privacy, many of which are not occasional programming mistakes. In this thesis, we systematically study these problems and develop dynamic program analyses to effectively detect, diagnose and fix these new problems. We start by researching the sensitive data leakage problem in apps. Since mobile apps …  Lire la suite

Experiments were carved out in a stirred tank reactor with both two phase and three phase systems. A systematic examination of the effect of solid particles on parameters such as volumetric liquid-side mass transfer coefficient kLa, specific interfacial area a, gas holdup epsilong, bubble size dB, and average bubble residence time tau, was conducted. Both dimensional and dimensionless correlations were generated and conclusions were drawn. The work was carried out in the context of the industrial experience that stirred tank reactors are widely used in both metallurgical and chemical engineering processes that often involve gas absorption in two and three …  Lire la suite

La différence entre les cultures politiques des États-Unis et du Canada est un sujet qui a attiré l'attention de générations de chercheurs. On dit souvent que cette différence est exprimée par les valeurs divergentes exprimées dans leurs constitutions respectives: «Vie, liberté et la quête du bonheur» dans la Déclaration d'indépendance des États-Unis et «Paix, ordre et bon gouvernement» dans la Loi constitutionnelle du Canada, 1867.Une partie de la littérature traitant de la stabilité relative du secteur bancaire canadien par rapport à celle des États-Unis après la crise financière mondiale (CFM) de 2007-2008 suggère une corrélation entre les cultures politiques divergentes …  Lire la suite

Mogrosides, the main active components in S. grosvenorii SWINGLE, are considered to be some 250 times sweeter than sucrose and to possess several medicinal attributes. Previous isolation processes used large quantities of toxic solvent that resulted in toxic residues of organic solvent in this high value food. Supercritical fluids fulfill the requirements of non-toxicity, recycle ability, and useful solvent characteristics. The work presented in this thesis is directed to the extraction of mogrosides from the powdered S. grosvenorii concentrate (SG) and the crude extract after resin treatment (MG) with sub critical water and supercritical CO2. Because no source of mogroside …  Lire la suite

La pandémie de COVID-19 a souligné l'importance d'une surveillance rigoureuse et de données épidémiologiques pour éclairer les réponses locales et mondiales. Les réponses efficaces doivent être globales et tenir compte des inégalités en matière de santé, des schémas de morbidité et de mortalité, des interventions pharmaceutiques et non pharmaceutiques et de la dynamique de transmission du SRAS-CoV-2. Ma thèse vise à comprendre et à documenter les réponses du Canada aux épidémies locales de COVID-19 en étudiant ces différentes facettes des réponses à la pandémie afin d’améliorer la préparation future. Pour éclairer leur réponse, les autorités provinciales se sont fiées à …  Lire la suite

This thesis consists of two essays on evaluating mutual fund performance and its predictability. In the first essay, I study the ex ante predictability of 12 well-known predictors for fund performance from investors’ perspective. The 12 predictors cover three major categories: fund characteristics, fund performance, and holding-based activeness measures, which are constructed using real-time information. For performance evaluation, I exploit two types of fund picking strategies with either rule-based approach or machine learning methods and find that utilizing machine learning can deliver superior real-time economic gains for investors with fund short-term performance being the primary driver underlying predictability. Specifically, using …  Lire la suite

van de Ven, Theo G. M. (Supervisor)  Lire la suite

ASP acts as a paracrine and autocrine signal to increase triglyceride synthesis in adipocytes. ASP administration results in more rapid postprandial lipid clearance. This present work consists of a series of experiments on complement C3 knockout mice (therefore ASP deficient mice) in vivo. The aim of this work is to understand the role of Acylation stimulating protein (ASP) in energy regulation. Compared to wild type mice, ASP deficient mice have delayed triglyceride and fatty acid clearance, decreased fat mass and body weight with concurrent increases in food intake. Both male and female ASP deficient mice have increased oxygen consumption, an …  Lire la suite

Mathematical models have been widely used in agricultural fields to simulate hydrologic process and to predict water transport in farmlands. The field-scale Root Zone Water Quality Model (RZWQM version 2.94.00) is proven to be satisfactory in modeling agricultural subsurface drainage in many studies. However, while focusing on long-term period drainage simulation and overall model performance, few study investigates simulations in short-term high drainage peak events, where models usually show relatively unacceptable performance. Alternative methods should be evaluated in improving drainage peak simulations, and high time resolution data should be utilized in these short-term period tests. Therefore, this study aims at: …  Lire la suite

Le durcissement par carbonatation précoce du béton est considéré comme une méthode efficace d'utilisation du CO2 pour réduire les émissions de carbone et améliorer les performances du béton. Cela se fait généralement avec du gaz pur à haute pression dans une chambre de pression. Pour promouvoir davantage d'applications de la technologie, cette thèse consiste à examiner la faisabilité de réaliser un séchage par carbonatation à pression ambiante dans une enceinte flexible constituée de feuilles de plastique et de fermetures à glissière résistantes à la pression. L'enceinte flexible peut être assemblée en usine ou sur le chantier et peut s'adapter à …  Lire la suite

RÉSUMÉ L'utilisation de champs électriques pulsés (CEP) dans la transformation d'aliments est une technique de pointe qui nécessite des études approfondies. Une meilleure compréhension de l'effet de traitements CEP sur les modifications structurales, l'hydrophobicité en surface et les propriétés rhéologiques de protéines alimentaires est nécessaire à l'application de cette méthode pour l'amélioration des propriétés fonctionnelles de protéines alimentaires dans les systèmes alimentaires. Deux principaux paramètres CEP furent étudiés: l'intensité du champ électrique, variant de 12 à 25 kV cm-1, et le nombre de pulsions, variant de 10 to 120. L'effet de traitements CEP sur les modifications structurales, l'hydrophobicité en surface …  Lire la suite

A simple and accurate multisheet Brewster angle measurement technique has been developed to measure substrate indices. Both K$ sp+$ and Ag$ sp+$ ion-exchanged optical waveguides in glass substrates were characterized for infrared wavelengths $ lambda=1.152$ and 1.523$ mu m.$ For the characterization of Ag$ sp+$ ion-exchange waveguide, the WKB method has been modified to handle the index truncation point at the waveguide boundary inside the substrate accurately. An explicit and stable finite-difference vector beam propagation method has also been developed for efficient numerical simulations of the guided-wave optical devices. A modified Y-branch wavelength multi/demultiplexer (abbreviated as WDM) for $ lambda=1.31$ …  Lire la suite

Tumogenèse mammaire est un processus évolutif où les processus cellulaires cruciaux pour la croissance et la survie de la tumeur sont sélectionnés et enrichis dans une tumeur. La biologie des cellules tumorales au cours des premiers stades de l'initiation de la tumeur peut être très différente de celle d'une tumeur établie au stade terminal. mTORC1 est un régulateur principal de la croissance cellulaire et joue un rôle bien établi dans la régulation de la traduction de l'ARNm par la régulation des 4EBP et de la S6 kinase. À ces regards mTORC1 contribue aux processus cruciaux pour la croissance et la …  Lire la suite

Three bovine casein peptides, LLY, PGPIPN, and TTMPLW, have been reported to stimulate phagocytosis of sheep red blood cells by murine macrophages. TTMPLW also protected mice against Klebsiella pneumoniae infection. The purpose of this study was to investigate the effects of these three peptides on cytokine (TNF-$ alpha$ and IL-6) production and nitric oxide (NO) release by bone marrow macrophages (BMM). The peptides alone were incapable of stimulating cytokine production or NO release in naive or IFN-$ gamma$-primed BMM. However, when BMM were coincubated with the peptides (1.0 $ mu$M) and LPS (100 ng/ml), an augmentative effect on TNF-$ alpha,$ …  Lire la suite

Eukaryotes achieve short duplication times of their genomes by the simultaneous activity of multiple replisomes at each DNA molecule. Regulation of the replisome assembly at origins of replication ensures timely and efficient duplication the genome. Origins of DNA replication have characteristic firing timing and efficiency and they are heterogeneously distributed in the genome. These features define the program of DNA replication and determine the progression of genome duplication. Although it is known that origin firing is controlled by the availability of low copy number initiation factors, what determines the preferential binding of these factors to certain origins is still unknown. …  Lire la suite

A new gold centrifugal concentrator, the Falcon SuperBowl, was tested both at plant and laboratory scales to assess its ability to recover gold from grinding circuits. The performances of a 21-in SuperBowl (SB21) at Mineral Hill and New Britannia Mines showed that it could recover gravity recoverable gold (GRG) of all sizes, especially below 25 mum at Mineral Hill Mine. Three types (to test the effect of gangue density and size distribution) of synthetic feeds were used to characterize a laboratory 4-in SuperBowl (SB4) as a function of feed rate and fluidization water flow rate. A 20-in Knelson Concentrator and …  Lire la suite

ABSTRACTObjectives: The main objective of this study was to establish and characterize a recovery model of pediatric IBD using piglets. Secondly, the objective was to characterize and compare the effects of adequate protein (anabolism) and N-acetylcysteine (antioxidant and anti-inflammatory) on growth and disease severity of colitis piglets during early recovery. Methods: The study conducted over 15 days. 40 female piglets, that were 7 to 10 days old weighing 3.17 to 4.09kg (7 to 9 pounds) underwent surgery for catheter insertion on Day 1. Piglets received a liquid protein deficient diet (15% of National Research Council requirement) infused intragastrically from Day …  Lire la suite

Cette étude analyse les écarts de prix attribuables à des caractéristiques observables de lait et de gruau vendu au détail par la méthodologie des prix hédoniques. L'évaluation des prix implicites des allégations sur le devant des emballages, des caractéristiques de magasins et des caractéristiques régionales associés aux produits alimentaires s'est effectuée par le traitement de données. Pour ce, deux sources de données ont été appariées, à savoir les données scanographiques agrégées de Nielsen datant de 2010 et des données primaires sur l'étiquetage nutritionnel des produits préemballés, recueillies durant l'automne 2011, comprenant les allégations nutritionnelles et les tableaux de valeur nutritive. …  Lire la suite

Jessica, Lin, (Supervisor1)  Lire la suite

Nattel, Stanley (Supervisor1)  Lire la suite

The objective of this research is to map snow cover in the Quebec area using passive microwave and other remote sensing data. The areal snow extent and snow water equivalent are determined and a twelve year snow water equivalent map is produced for the purpose of analyzing interannual snow variability. The presence of vegetation cover will affect the data obtained with passive systems. For heavily vegetated areas such as Quebec, the vegetation effect should be predetermined and classified to reduce the error on snow water equivalence calculation. In dry snow conditions, forest coverage and snow density are the two major …  Lire la suite

Cells are highly functional units that frequently adapt to changes in their environmental conditions. Some conditions such as increased temperature, oxidative stress conditions, and nutrient depravation are not optimal for cells to operate because they alter the functional protein conformation and disrupt protein homeostasis. In response to such stressful circumstances, cells activate a universal survival mechanism known as the heat shock response (HSR). The HSR mitigates the stressors' adverse effects on damaging proteins through the robust induction of heat shock proteins (Hsps), especially Hsp70. The transcription and translation of HSP70 mRNA are upregulated under stress conditions because Hsp70 is essential …  Lire la suite

The human gastrointestinal tract (GIT) hosts a diverse and complex community of microorganisms, including bacteria, archaea, viruses, and eukaryotes, which is referred to as the GIT microbiota. Recently, there has been a considerable amount of studies pertaining to the influence the GIT microbiota has on human health and disease, showing that microbial dysbiosis has been linked to numerous diseases such as diabetes, autoimmune diseases, cancer, and neurodegenerative diseases. However, the findings are still preliminary and limited, and many microbial functions and features remain unknown due to the inaccessibility of the human GIT for sampling, limiting systematic experimentation. Studying the GIT …  Lire la suite

A study on the acoustic simulations of early reflections in three-dimensional rooms is presented. Measurements of four real rooms in Schulich School of Music and computational simulations in Matlab are compared to verify the results.The four real rooms are modeled with two methods commonly used in modern geometric acoustic modeling, the image source method and the ray-tracing method. Then the simulation results are compared with the measurement in impulse responses and echo densities. Discussions about the differences between measurements and modeling results are based on geometrical models and acoustic properties. Factors influencing the accuracy of the simulations include the geometric …  Lire la suite

The Lenstra, Lenstra and Lov\'{a}sz (LLL) reduction is the most popular lattice reduction and is a powerful tool for solving many complex problems in mathematics and computer science. The blocking technique casts matrix algorithms in terms of matrix-matrix operations to permit efficient reuse of data in the algorithms. In this thesis, we use the blocking technique to develop two floating point block LLL reduction algorithms, the left-to-right block LLL (LRBLLL) reduction algorithm and the alternating partition block LLL (APBLLL) reduction algorithm, and give the complexity analysis of these two algorithms. We compare these two block LLL reduction algorithms with the …  Lire la suite

La macromodélisation des structures passives comme les réseaux d'interconnecte est une étape difficile dans l'analyse de l'intégralité des signaux et de l'énergie. Un modèle de base physique est difficile à obtenir pour beaucoup de structures et pour obtenir un macromodèle, il est nécessaire d'utiliser des techniques numériques comme Vector Fitting et l'interpolation par les matrices Loewner. Cependant, les techniques numériques mentionnées ne peuvent pas garantir la passiveté par construction des macromodèle, ce qui résulte dans la nécessité d'ajouter des méthodes de perturbation pour la rectification de passivité comme dernière étape dans la macromodélisation. Dans cette thèse, nous étudions les méthodes …  Lire la suite

La simulation par model est devenue une étape clée dans la conception de system de circuit à cause de l’avantage de pouvoir évaluer un system avant de consacrer de la resource physique. La macro-modélisation est une importante technique de modélisation des circuits qui utilise les données dans le domaine de la fréquence représentant les relation entre les ports du system pour créer un model de boîte noire du system utilisable dans les simulation. Naturellement, la macromodélisation encourage et est en synergie avec l’utilisation de syst`emes modulaire avec lesquels une simulation du system en entier est achev´e en combinant ces modules. …  Lire la suite

Parkinson's disease (PD) is the second most frequent neuro-degenerative disease worldwide. Due to dopamine depletion within the basal ganglia, the disorder primarily affects the patients motor functions, but it can also be accompanied with psychiatric symptoms, sleep disorder, and cognitive impairment. Deep brain stimulation (DBS) is an effective surgical treatment for Parkinson's disease besides traditional medication. The procedure requires accurate placement of an electrode into the dorsal-lateral site of the subthalamic nucleus (STN) deep in the brain. However, the small nucleus is difficult to visualize on conventional T1w MRIs. Accurate knowledge of its 3 dimensional (3D) geometry in relation to …  Lire la suite

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Chronic high frequency Deep Brain Stimulation (DBS) has provided remarkable therapeutic benefits for PD patients, who do not respond well to pharmaceutical treatments. One of the most popular targets of stimulation is the subthalamic nucleus (STN), which is surrounded by delicate subcortical structures and has a small average size. Therefore, it is critical to localize the surgical target accurately with minimal invasiveness to achieve the optimal outcome. Common practice applies a long trial-and-error probing with a micro-electrode to locate the sites with the correct electrical response after an initial …  Lire la suite

Moodie, Erica (Supervisor2)  Lire la suite

Background. Clustering of observations occurs frequently in epidemiological and clinical studies of time-to-event outcomes. However, only a few papers addressed the challenge of accounting for clustering while analyzing right-censored survival data. I propose two bootstrap-based approaches to correct standard errors of Cox's proportional hazards (PH) model estimates for clustering, and validate the approaches in simulations. Methods. Both bootstrap-based approaches involve 2 stages of resampling the original data. The two methods share the same procedure at the first stage but employ different procedures at the second stage. At the first stage of both methods, the clusters (e.g. physicians) are resampled with …  Lire la suite

Networks and their services have been growing rapidly in recent years, so has the complexity of configuring the network operations. In order to manage the rapidly expanding networks, new management protocols are thus needed to change the network management from configuration of individual devices to automation of the whole network. SNMPCONF, a policy-based configuration with SNMP protocol, is proposed by IETF to meet this requirement. SNMPCONF is suggested to configure networks with a policy MIB (Management Information Base). However, deploying this protocol in existing network devices needs more work, because the policy MIB defined by SNMPCONF is not implemented now …  Lire la suite

Copper solubility in water vapor and liquid was measured in the HCl-NaCl-H 2O system at temperatures up to 400°C and vapor-saturated pressure by two series of experiments. The thermodynamic data from these experiments were then applied to model the genesis of volcanogenic massive sulfide deposits and the partitioning of copper between vapor and liquid. The solubility of copper in liquid was measured in vapor-saturated aqueous HCl/NaCl solutions at temperatures ranging from 40 to 300°C, total chloride concentrations from 0.01 to 1 m, and pH from 0 to 3.5. Copper was found to dissolve primarily as CuCl(aq), CuCl2- and CuCl32-. Data …  Lire la suite

Determining whether or not a gold gravity circuit should be installed in a gold plant requires a prediction of how much gold will be recovered. This has always been a difficult task because recovery takes place from the grinding circulating load, in which gold's behavior must be described. A population-balance model (PBM) to predict gold gravity recovery was developed at McGill University in 1994 (Laplante et al, 1995). The objective of this research was to make this PBM user friendly. This was achieved in two different ways. First, the behavior of gravity recoverable gold (GRG) in secondary ball mills and …  Lire la suite

Modeling gravity recovery of platinum group minerals (PGMs) in the grinding circuit is based on three components: Ore characterization of gravity recoverable platinum group minerals (GRPGM), their behavior in grinding mills and hydrocyclones, and the performance of the gravity recovery units. This thesis focuses on the first two components. A laboratory methodology to characterize gravity-recoverable platinum group minerals (GRPGMs) in an ore with four incremental liberation and recovery stages was developed. It was applied to quantify GRPGM content of four ore samples from Canada. To measure the behavior of GRPGMs in the grinding circuit, a methodology to characterize the already …  Lire la suite