Facteurs psychosociaux liés aux risques d'infections virales (VIH/sida et hépatites) chez les cocaïnomanes

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Facteurs psychosociaux liés aux risques d'infections virales (VIH/sida et hépatites) chez les cocaïnomanes

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Comunicación

El primero de septiembre de 1976 se colectaron varias muestras de Equisetum giganteum en el Bajío de Palo Blanco, en la aldea Bolaños, cerca del Cerro y Río Singüil del departamento de Santa Ana no reportada para ese lugar. Fue reportada anteriormente en el pantano de Ateos por el Dr. Salvador Calderón e Ing. Paul C. Stanley en la flora salvadoreña, lista preliminar de plantas de El Salvador, C.A. El lugar donde fue reportada anteriormente ya no existe por lo cual esta especie se creía extinta. Posteriormente se hará un estudio exhaustivo de esta planta.

Dynamic instabilities in scalar neural field equations with space-dependent delays

In this paper we consider a class of scalar integral equations with a form of space-dependent delay. These non-local models arise naturally when modelling neural tissue with active axons and passive dendrites. Such systems are known to support a dynamic (oscillatory) Turing instability of the homogeneous steady state. In this paper we develop a weakly nonlinear analysis of the travelling and standing waves that form beyond the point of instability. The appropriate amplitude equations are found to be the coupled mean-field Ginzburg-Landau equations describing a Turing-Hopf bifurcation with modulation group velocity of O(1). Importantly we are able to obtain the coefficients of terms in the amplitude equations in terms of integral transforms of the spatio-temporal kernels defining the neural field equation of interest. Indeed our results cover not only models with axonal or dendritic delays but those which are described by a more general distribution of delayed spatio-temporal interactions. We illustrate the predictive power of this form of analysis with comparison against direct numerical simulations, paying particular attention to the competition between standing and travelling waves and the onset of Benjamin-Feir instabilities.

Relationship between religiosity, religious coping and socio-demographic variables among out-patients with depression or diabetes mellitus in Enugu, Nigeria.

Background: Religion is a powerful coping strategy. Diabetes and depression are common conditions in our environment that induce psychological distress, thus requiring coping for better outcome. Studies indicate that increased religiosity is associated with better outcome in clinical and general populations. Therefore, studies of the distribution of religiosity and religious coping among these populations are essential to improve outcome. Objectives: To assess the association between religiosity, religious coping in depression and diabetes mellitus, and selected sociodemographic variables (age, gender and occupational status). Methods:Using simple random sampling we recruited 112 participants with diabetes and an equal number with depression consecutively, matching for gender. Religiosity was determined using religious orientation scale (revised), religious coping with brief religious coping scale and socio-demographic variables with a socio-demographic questionnaire. Results: Intrinsic religiosity was greater among older people with depression than among older people with diabetes(t=5.02,p<0.001); no significant difference among young people with depression and diabetes(t=1.47,p=0.15).Positive religious coping was greater among older people with depression than among older people with diabetes(t=2.31,p=0.02); no difference among young people with depression and diabetes(t=0.80,p=0.43). Females with depression had higher intrinsic religiosity scores than males with depression(t=3.85,p<0.001); no difference in intrinsic religiosity between females and males with diabetes(t=0.99,p=0.32).Positive religious coping was greater among participants with diabetes in the low occupational status(t=2.96,p<0.001) than those in the high occupational status. Conclusion: Religion is indeed a reliable coping method, most commonly used by the elderly and females with depression. Positive religious coping is more common among diabetic patients who are in the low occupational status.

Predicting Successful Aging at One Hundred Years of Age

The present study is based upon a multidimensional model of successful aging. It aims to identify subgroups of centenarians sharing communalities in successful aging profiles, and determine the role of sociodemographic factors and psychological, social, and economic resources on successful aging.

Isolating the photovoltaic junction: atomic layer deposited TiO2-RuO2 alloy Schottky contacts for silicon photoanodes

We synthesized nanoscale TiO2-RuO2 alloys by atomic layer deposition (ALD) that possess a high work function and are highly conductive. As such, they function as good Schottky contacts to extract photogenerated holes from n-type silicon while simultaneously interfacing with water oxidation catalysts. The ratio of TiO2 to RuO2 can be precisely controlled by the number of ALD cycles for each precursor. Increasing the composition above 16% Ru sets the electronic conductivity and the metal work function. No significant Ohmic loss for hole transport is measured as film thickness increases from 3 to 45 nm for alloy compositions >= 16% Ru. Silicon photoanodes with a 2 nm SiO2 layer that are coated by these alloy Schottky contacts having compositions in the range of 13-46% Ru exhibit average photovoltages of 525 mV, with a maximum photovoltage of 570 mV achieved. Depositing TiO2-RuO2 alloys on nSi sets a high effective work function for the Schottky junction with the semiconductor substrate, thus generating a large photovoltage that is isolated from the properties of an overlying oxygen evolution catalyst or protection layer.

Design principles for maximizing photovoltage in metal-oxide-protected water-splitting photoanodes

Metal oxide protection layers for photoanodes may enable the development of large-scale solar fuel and solar chemical synthesis, but the poor photovoltages often reported so far will severely limit their performance. Here we report a novel observation of photovoltage loss associated with a charge extraction barrier imposed by the protection layer, and, by eliminating it, achieve photovoltages as high as 630mV, the maximum reported so far for water-splitting silicon photoanodes. The loss mechanism is systematically probed in metal-insulator-semiconductor Schottky junction cells compared to buried junction p(+) n cells, revealing the need to maintain a characteristic hole density at the semiconductor/insulator interface. A leaky-capacitor model related to the dielectric properties of the protective oxide explains this loss, achieving excellent agreement with the data. From these findings, we formulate design principles for simultaneous optimization of built-in field, interface quality, and hole extraction to maximize the photovoltage of oxide-protected water-splitting anodes.

Engineering interfacial silicon dioxide for improved metal-insulator-semiconductor silicon photoanode water splitting performance

Silicon photoanodes protected by atomic layer deposited (ALD) TiO2 show promise as components of water splitting devices that may enable the large-scale production of solar fuels and chemicals. Minimizing the resistance of the oxide corrosion protection layer is essential for fabricating efficient devices with good fill factor. Recent literature reports have shown that the interfacial SiO2 layer, interposed between the protective ALD-TiO2 and the Si anode, acts as a tunnel oxide that limits hole conduction from the photoabsorbing substrate to the surface oxygen evolution catalyst. Herein, we report a significant reduction of bilayer resistance, achieved by forming stable, ultrathin (<1.3 nm) SiO2 layers, allowing fabrication of water splitting photoanodes with hole conductances near the maximum achievable with the given catalyst and Si substrate. Three methods for controlling the SiO2 interlayer thickness on the Si(100) surface for ALD-TiO2 protected anodes were employed: (1) TiO2 deposition directly on an HF-etched Si(100) surface, (2) TiO2 deposition after SiO2 atomic layer deposition on an HF-etched Si(100) surface, and (3) oxygen scavenging, post-TiO2 deposition to decompose the SiO2 layer using a Ti overlayer. Each of these methods provides a progressively superior means of reliably thinning the interfacial SiO2 layer, enabling the fabrication of efficient and stable water oxidation silicon anodes.