L'enseignement en éducation physique au collégial en contexte de plein air

Cette étude exploratoire descriptive porte sur la situation de l'enseignement de l'éducation physique au collégial en contexte de plein air, présent dans près de 80% des institutions publiques et privées d'enseignement collégial au Québec. L'évolution récente de la pratique du plein air dans le monde et au Québec a occasionné une démocratisation marquée de la pratique, un attrait pour des destinations à plus haut risque et une hausse du nombre d'incidents. L'impact sur les organismes qui offrent des séjours encadrés en plein air, dont le milieu scolaire, est majeur et occasionne des changements en particulier dans l'encadrement de ces activités. Cette recherche multiméthodologique porte spécifiquement sur trois aspects de l'enseignement en contexte de plein air au collégial soit 1) qui sont les enseignants, 2) quelles sont les intentions pédagogiques qu'ils poursuivent et 3) quels sont les contenus d'enseignement qu'ils dispensent aux étudiants. Les principaux résultats montrent que les enseignants disposent de formations et d'expérience en lien avec l'encadrement d'activités de plein air, mais que des lacunes au regard des normes reconnues sont présentes. Quant aux intentions pédagogiques et aux contenus d'enseignement, les résultats montrent que l'accent est fortement mis sur les aspects techniques de la pratique des activités de plein air et que cela ne rejoint pas les critères de formation relatifs à une pratique autonome et sécuritaire du Conseil québécois du loisir (CQL). La conclusion identifie deux grands axes d'intervention. Premièrement, l'encadrement de groupe en contexte de plein air implique des responsabilités plus importantes qu'en milieu contrôlé comme un gymnase. Certaines lacunes en formation des enseignants montrent que les critères d'encadrement ne sont pas suivis par tous et que des efforts en formation seraient à favoriser. D'autre part, ces mêmes lacunes sont à la source de manques au niveau de l'apprentissage de l'autonomie en contexte de plein air, une des visées identifiées par le Ministère de l'Éducation au collégial. En effet, les contenus présentés dans les cours ne répondent pas aux éléments ciblés pour une pratique autonome et sécuritaire des activités de plein air.\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Éducation, collégial, plein air, aventure, pédagogie

Influence of mass and charge disorder on the phonon thermal conductivity of some high entropy ceramics by molecular dynamics simulation

We are exploring how the interplay between mass and charge disorder affects the thermal conductivity of high entropy ceramics that have potential use as ultra-high temperature materials and their oxides. Recent experiments by our team, for example, have shown that the thermal conductivity of the entropy stabilized oxide (Mg0.1Co0.1Ni0.1Cu0.1Zn0.1)O0.5, termed J14, is reduced by the addition of a sixth cation Sc, Sn, Cr, Ge or Sb in an equi-molar proportion. Classical phonon transport theory cannot account for this reduction based on mass scattering alone. Therefore we have been using molecular dynamics simulations to gain a better insight of the combined effects of disorder in mass and in electrostatic interactions on phonon-mediated thermal conductivity for these systems. Please click Additional Files below to see the full abstract

Metabolic syndrome increases operative mortality in patients undergoing coronary artery bypass grafting surgery

OBJECTIVES: The aim of this study was to determine the impact of the metabolic syndrome (MS) on operative mortality after a coronary artery bypass grafting surgery (CABG). BACKGROUND: Diabetes and obesity are highly prevalent among patients undergoing CABG. However, it remains unclear whether these factors have a significant impact on operative mortality after this procedure. We hypothesized that the metabolic abnormalities associated with MS could negatively influence the operative outcome of CABG surgery. METHODS: We retrospectively analyzed the data of 5,304 consecutive patients who underwent an isolated CABG procedure between 2000 and 2004. Of these 5,304 patients, 2,411 (46%) patients met the National Cholesterol Education Program-Adult Treatment Panel III criteria for MS. The primary end point was operative mortality. RESULTS: The operative mortality after CABG surgery was 2.4% in patients with MS and 0.9% in patients without MS (p < 0.0001). The MS was a strong independent predictor of operative mortality (relative risk 3.04 [95% confidence interval (CI) 1.73 to 5.32], p = 0.0001). After adjusting for other risk factors, the risk of mortality was increased 2.69-fold (95% CI 1.43 to 5.06; p = 0.002) in patients with MS and diabetes and 2.36-fold (95% CI 1.26 to 4.41; p = 0.007) in patients with MS and no diabetes, whereas it was not significantly increased in the patients with diabetes and no MS. CONCLUSIONS: This is the first study to report that MS is a highly prevalent and powerful risk factor for operative mortality in patients undergoing a CABG surgery. Thus, interventions that could contribute to reduce the prevalence of MS in patients with coronary artery disease or that could acutely modify the metabolic perturbations of MS at the time of CABG might substantially improve survival in these patient

High-entropy metal diborides: a new class of ultra-high temperature ceramics

Several equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering [Scientific Reports 6:37946 (2016)] or conventional pressure-less sintering. Most compositions synthesized, e.g., (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 and several others, processed single solid-solution phases of the hexagonal AlB2 structure, while a few other compositions yielded two or more boride phases. These materials represent a new type of ultra-high temperature ceramic (UHTC) as well as a new class of high-entropy materials that possess a non-cubic (hexagonal) and layered (quasi-2D) crystal structure (Fig. 1). Please click Additional Files below to see the full abstract

Urinary And Breast Milk Biomarkers To Assess Exposure Ro Naphthalene In Pregnant Women: An Investigation Of Personal And Indoor Air Sources

Naphthalene exposures for most non-occupationally exposed individuals occur primarily indoors at home. Residential indoor sources include pest control products (specifically moth balls), incomplete combustion such as cigarette smoke, woodstoves and cooking, some consumer and building products, and emissions from gasoline sources found in attached garages. The study aim was to assess naphthalene exposure in pregnant women from Canada, using air measurements and biomarkers of exposure

Measurements and simulations of the phonon thermal conductivity of entropy stabilized alloys

The phonon thermal conductivity of solids is intimately related to any changes in atomic scale periodicity. As a classic example, the phonon thermal conductivity of alloys can be greatly reduces as compared to that of the corresponding non-alloy parent materials. However, the improved mechanical properties and environmental stability of alloyed materials makes these multi-atom solids ideal for a wide variety of applications. In this sense, entropy stabilized oxides and high entropy diborides are promising new materials that have potential to withstand extreme environments consisting of high temperatures and pressures. In these novel materials, thermal characterization is essential for understanding and predicting performance at elevated temperatures, as the presence of multi atomic species (5+ different atoms) in these solid solutions could lead to drastically modified phonon scattering rates and thermal conductivities. In this talk, we present recent measurements and molecular dynamics simulations on multiple atom alloys, including entropy stabilized oxides and high entropy diborides. We use time-domain thermoreflectance (TDTR), and optical pump-probe technique, to measure the thermal conductivity of these various systems. We also demonstrate the ability to extend TDTR measurements to temperatures above 1000 deg. C. The TDTR measurements show drastic reductions in the thermal conductivity of these crystalline solid solution materials, approaching values of the amorphous phases. These reductions in thermal conductivity can not be explained by phonon-mass scattering alone. Thus, to investigate the nature of the reduction in thermal conductivity of these multi-atom solid solutions, we turn to classical molecular dynamics simulations. In agreement with the Klemens’ perturbation theory, the thermal conductivity reduction due to mass scattering alone is found to reach a critical point, whereby adding more impurity atoms in the solid solution does not reduce the thermal conductivity. A further decrease in thermal conductivity requires a change in local strain-field, which together with mass defect scattering can lead to ultralow thermal conductivities in solid solutions, which surpasses the theoretical minimum limit of the corresponding amorphous phases. These simulations qualitatively agree well with our experimental measurements, and add insight into the nature of phonon scattering in entropy stabilized materials. This work is supported by the U.S. Office of Naval Research MURI program (grant No. N00014-15-1-2863)

Phonon scattering mechanisms contributing to the low thermal conductivities of entropy stabilized oxides and high entropy carbides

The phonon thermal conductivity of solids is intimately related to any changes in atomic scale periodicity. As a classic example, the phonon thermal conductivity of alloys can be greatly reduced as compared to that of the corresponding non-alloy parent materials. However, the improved mechanical properties and environmental stability of alloyed materials makes these multi-atom solids ideal for a wide variety of applications. In this sense, entropy stabilized oxides and high entropy carbides are promising new materials that have potential to withstand extreme environments consisting of high temperatures and pressures. In these novel materials, thermal characterization is essential for understanding and predicting performance at elevated temperatures, as the presence of multi atomic species (5+ different atoms) in these solid solutions could lead to drastically modified phonon scattering rates and thermal conductivities. In this talk, we present recent measurements and molecular dynamics simulations on multiple atom alloys, including entropy stabilized oxides and high entropy diborides. We use time-domain thermoreflectance (TDTR), and optical pump-probe technique, to measure the thermal conductivity of these various systems. We also demonstrate the ability to extend TDTR measurements to temperatures above 1000 deg. C. The TDTR measurements show drastic reductions in the thermal conductivity of these crystalline solid solution materials, approaching values of the amorphous phases. These reductions in thermal conductivity can not be explained by phonon-mass scattering alone. Thus, to investigate the nature of the reduction in thermal conductivity of these multi-atom solid solutions, we turn to classical molecular dynamics simulations. In agreement with the Klemens’ perturbation theory, the thermal conductivity reduction due to mass scattering alone is found to reach a critical point, whereby adding more impurity atoms in the solid solution does not reduce the thermal conductivity. A further decrease in thermal conductivity requires a change in local strain-field, which together with mass defect scattering can lead to ultralow thermal conductivities in solid solutions, which surpasses the theoretical minimum limit of the corresponding amorphous phases. These simulations qualitatively agree well with our experimental measurements, and add insight into the nature of phonon scattering in entropy stabilized materials. This work is supported by the U.S. Office of Naval Research MURI program (grant No. N00014-15-1-2863

Le Forum, Vol. 42 No. 2

https://digitalcommons.library.umaine.edu/francoamericain_forum/1095/thumbnail.jp

Functional Characterization of EngAMS, a P-Loop GTPase of Mycobacterium smegmatis

Bacterial P-loop GTPases belong to a family of proteins that selectively hydrolyze a small molecule guanosine tri-phosphate (GTP) to guanosine di-phosphate (GDP) and inorganic phosphate, and regulate several essential cellular activities such as cell division, chromosomal segregation and ribosomal assembly. A comparative genome sequence analysis of different mycobacterial species indicates the presence of multiple P-loop GTPases that exhibit highly conserved motifs. However, an exact function of most of these GTPases in mycobacteria remains elusive. In the present study we characterized the function of a P-loop GTPase in mycobacteria by employing an EngA homologue from Mycobacterium smegmatis, encoded by an open reading frame, designated as MSMEG_3738. Amino acid sequence alignment and phylogenetic analysis suggest that MSMEG_3738 (termed as EngAMS) is highly conserved in mycobacteria. Homology modeling of EngAMS reveals a cloverleaf structure comprising of α/β fold typical to EngA family of GTPases. Recombinant EngAMS purified from E. coli exhibits a GTP hydrolysis activity which is inhibited by the presence of GDP. Interestingly, the EngAMS protein is co-eluted with 16S and 23S ribosomal RNA during purification and exhibits association with 30S, 50S and 70S ribosomal subunits. Further studies demonstrate that GTP is essential for interaction of EngAMS with 50S subunit of ribosome and specifically C-terminal domains of EngAMS are required to facilitate this interaction. Moreover, EngAMS devoid of N-terminal region interacts well with 50S even in the absence of GTP, indicating a regulatory role of the N-terminal domain in EngAMS-50S interaction