125 research outputs found
Mise au point d'un réacteur épitaxial CBE
Ce projet de maĂźtrise consiste Ă l'asservissement et la mise en marche d'un rĂ©acteur d'Ă©pitaxie par jets chimiques au Laboratoire d'Ăpitaxie AvancĂ©e de l'UniversitĂ© de Sherbrooke. Le rĂ©acteur sert Ă la croissance dans l'ultravide de matĂ©riaux semi-conducteurs tels que l'arsĂ©niure de gallium (GaAs) et le phosphure d'indium-gallium (GalnP). La programmation LabVIEWâą et du matĂ©riel informatique de National Instruments sont utilisĂ©s pour asservir le rĂ©acteur. Le contrĂŽle de la tempĂ©rature de l'Ă©chantillon et de la pression de contrĂŽle des rĂ©actifs de croissance dans le rĂ©acteur est assurĂ© par des boucles de rĂ©troaction. Ainsi, la tempĂ©rature de l'Ă©chantillon est stabilisĂ©e à ±0,4 °C, alors que les pressions de contrĂŽle de gaz peuvent ĂȘtre modulĂ©es sur un ordre de grandeur en 2 Ă 4 secondes, et stabilisĂ©es à ±0,002 Torr. Le systĂšme de pompage du rĂ©acteur a Ă©tĂ© amĂ©liorĂ© suite Ă des mesures de vitesse de pompage d'une pompe cryogĂ©nique. Ces mesures rĂ©vĂšlent une dĂ©gradation sur plus d'un ordre de grandeur de son pompage d'hydrogĂšne avec l'opĂ©ration Ă long terme. Le remplacement de la pompe cryogĂ©nique par une pompe turbo-molĂ©culaire comme pompe principale a permis d'amĂ©liorer la fiabilitĂ© du systĂšme de pompage du systĂšme sous vide. D'autre part, la conductance du systĂšme d'acheminement de gaz et d'injection a Ă©tĂ© augmentĂ©e afin de rĂ©duire un effet mĂ©moire des sources le systĂšme et faciliter la croissance de matĂ©riaux ternaires. Ainsi, des croissances de GaAs (100) sur substrat de mĂȘme nature ont Ă©tĂ© effectuĂ©es et ont rĂ©vĂ©lĂ© un matĂ©riau de bonne qualitĂ©. Sa rugositĂ© moyenne de 0,17 nm, mesurĂ©e par microscopie Ă force atomique, est trĂšs faible selon la littĂ©rature. De plus, une mobilitĂ© Ă©levĂ©e des porteurs est obtenue Ă fort dopage au silicium, au tellure et au carbone, notamment une mobilitĂ© de 42 ± 9 cm2V_1s_1 des porteurs majoritaires "(trous) lors du dopage au carbone Ă 1,5 âą 1019 cm-3, en accord avec la courbe thĂ©orique. La croissance du matĂ©riau ternaire GalnP a aussi Ă©tĂ© rĂ©alisĂ©e en accord de maille avec le substrat de GaAs, et avec une rugositĂ© de 0,96 nm. Ceci constitue un premier pas dans la croissance d'alliages ternaires au laboratoire. Finalement, la mise eh marche du rĂ©acteur d'Ă©pitaxie par jets chimiques permet maintenant Ă cinq Ă©tudiants graduĂ©s de faire progresser des projets reliĂ©s directement Ă la croissance Ă©pitaxiale au Laboratoire d'Ăpitaxie AvancĂ©e de l'UniversitĂ© de Sherbrooke. [symboles non conformes
Abdominal adipocyte populations in women with visceral obesity
Visceral obesity is independently related to numerous cardiometabolic alterations, with adipose
tissue dysfunction as a central feature. Objective: To examine whether omental (OM) and
subcutaneous (SC) adipocyte size populations in women relate to visceral obesity,
cardiometabolic risk factors and adipocyte lipolysis independent of total adiposity. Design and
Methods: OM and SC fat samples were obtained during gynecological surgery in 60 women
[mean age: 46.1±5.9 years; mean BMI: 27.1±4.5 kg/m2 (range: 20.3-41.1 kg/m2)]. Fresh samples
were treated with osmium tetroxide and were analyzed with a Multisizer Coulter. Cell size
distributions were computed for each sample with exponential and Gaussian function fits.
Results: Computed tomography-measured visceral fat accumulation was the best predictor of
larger cell populations as well as the percentage of small cells in both OM and SC fat (p<0.0000
for all). Accordingly, women with visceral obesity had larger cells in the main population and
higher proportion of small adipocytes independent of total adiposity (pâ€0.05). Using linear
regression analysis, we found that women characterized by larger-than-predicted adipocytes in
either OM or SC adipose tissue presented higher visceral adipose tissue area, increased
percentage of small cells and HOMAir index as well as higher OM adipocyte isoproterenol-,
forskolin- and dibutyryl cAMP- stimulated lipolysis compared to women with smaller-than predicted adipocytes, independent of total adiposity (pâ€0.05). Conclusion: Excess visceral
adipose tissue accumulation is a strong marker of both adipocyte hypertrophy and increased
number of small cells in either fat compartment, which relates to higher insulin resistance index
and lipolytic response, independent of total adiposity
L'Estuaire (65)
Ăditorial: La relance de la revue de l'Estuaire: 15 ans dĂ©jĂ ! -- Le chemin de fer et le tourisme au Bas-Saint-Laurent -- Les dames Drapeau -- Histoire oubliĂ©e: Une Ă©trange odyssĂ©e...des Madelinots s'Ă©tablissent sur l'Ăle Nepawa (Abitibi) en 1941 -- Ătude dĂ©mographique de la population de Rimouski 1701-1750 -- Sur la piste des forĂȘts du passĂ© -- Mgr Courchesne: la rĂ©cupĂ©ration des forĂȘts pour la colonisation -- Joseph-Pierre Ouellet, 2e architecte de l'Ă©glise de Trois-Pistoles -- La seigneurie de l'Anse-aux-Coques ou de Lepage-Thivierge -- Nouvelles brĂšves -- Livres Ă lir
Hybrid MBE-CBE Growth and Characterization of undoped In 0,53 Ga 0,47 As on Fe-InP(001) for avalanche photodiodes (APDs)
International audienc
Patient-Related Diet and Exercise Counseling: Do Providersâ Own Lifestyle Habits Matter?
The goal of this research was to evaluate the personal health behaviors of physicians in training and attending physicians in association with patient-related lifestyle counseling. Physicians at a major teaching hospital were surveyed regarding their personal lifestyle behavior, perceived confidence, and frequency of counseling patients regarding lifestyle behaviors. One hundred eighty-three total responses were received. Trainees were more likely to consume fast food and less likely to consume fruits and vegetables than attendings. Attending physicians were more likely to exercise 4 or more days per week and more than 150âminutes per week. Attending physicians were more likely to counsel their patients regarding a healthy diet (70.7% vs 36.3%, P150âminutes per week, being overweight, and reported adequate training in counseling. Only adequate training in counseling was a predictor of strong self-efficacy for counseling in diet. Many physicians lack confidence in their ability to counsel patients regarding lifestyle. Personal behaviors including regular exercise and better training in counseling techniques may improve patient counseling. Prev Cardiol. 2010;13:180â185. © 2010 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79167/1/j.1751-7141.2010.00079.x.pd
Lymph node fibroblastic reticular cells directly present peripheral tissue antigen under steady-state and inflammatory conditions
Lymph node stromal cells (LNSCs) can induce potent, antigen-specific T cell tolerance under steady-state conditions. Although expression of various peripheral tissueârestricted antigens (PTAs) and presentation to naive CD8+ T cells has been demonstrated, the stromal subsets responsible have not been identified. We report that fibroblastic reticular cells (FRCs), which reside in the T cell zone of the LN, ectopically express and directly present a model PTA to naive T cells, inducing their proliferation. However, we found that no single LNSC subset was responsible for PTA expression; rather, each subset had its own characteristic antigen display. Studies to date have concentrated on PTA presentation under steady-state conditions; however, because LNs are frequently inflammatory sites, we assessed whether inflammation altered stromal cellâT cell interactions. Strikingly, FRCs showed reduced stimulation of T cells after Toll-like receptor 3 ligation. We also characterize an LNSC subset expressing the highest levels of autoimmune regulator, which responds potently to bystander inflammation by up-regulating PTA expression. Collectively, these data show that diverse stromal cell types have evolved to constitutively express PTAs, and that exposure to viral products alters the interaction between T cells and LNSCs
Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse
Germanium (Ge) is increasingly used as a substrate for high-performance
optoelectronic, photovoltaic, and electronic devices. These devices are usually
grown on thick and rigid Ge substrates manufactured by classical wafering
techniques. Nanomembranes (NMs) provide an alternative to this approach while
offering wafer-scale lateral dimensions, weight reduction, limitation of waste,
and cost effectiveness. Herein, we introduce the Porous germanium Efficient
Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of
wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate
reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm
on top of nanoengineered void layer enabling layer detachment. Furthermore,
these Ge NMs exhibit compatibility with the growth of III-V materials.
High-resolution transmission electron microscopy (HRTEM) characterization shows
Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal
space mapping endorses high-quality GaAs layers. Finally, we demonstrate the
chemical reconditioning process of the Ge substrate, allowing its reuse, to
produce multiple free-standing NMs from a single parent wafer. The PEELER
process significantly reduces the consumption of Ge during the fabrication
process which paves the way for a new generation of low-cost flexible
optoelectronics devices.Comment: 17 pages and 6 figures along with 3 figures in supporting informatio
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.
In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field
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