Journal of Next-Generation Research 5.0
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Le développement professionnel des enseignants expérimentés par la transmission explicite de pratiques entre pairs
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Déresponsabiliser les enseignants novices pour mieux les former et accroitre leur satisfaction professionnelle
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Challenges of mastering the energy sector and sustainable solutions for development in Africa
No full textInternational audienceThe African continent is currently experiencing a period of sustained economic and population growth that requires massive investment in the energy sector to effectively meet the energy needs in the context of sustainable development. At the same time, COP21 agreements now call all the states to use clean energy. Yet a great energy potential is available, but the electrification rate of the continent currently accounts for only 3% of the world's energy production. Also, the demand for both quality and quantity energy requires the mastery of applied mathematical tools to efficiently solve problems arising in the energy system. In this article, the major problems affecting the energy sector in Africa are identified, some solutions to the challenges are recalled and some new ones are proposed, with emphasis given to applied mathematics tools as well as energy policy. As case studied, a new control strategy of Static Synchronous Series Compensator (SSSC) devices-which are modern power quality Flexible Alternating Current Transmission Systems (FACTS)-is proposed for Power Flow Control.Le continent africain connait actuellement une période de croissance économique et dé-mographique soutenue qui requiert un investissement massif dans le secteur de l'énergie en vue d'un développement durable. Dans le même temps, les accords de la COP21 interpellent désor-mais les états à recourir aux énergies propres. Malgré son potentiel énergétique énorme, le taux d'électrification en Afrique reste très faible (3%) notamment au sud du sahara. D'autre part, la de-mande d'énergie en qualité et en quantité nécessite un recours aux outils mathématiques modernes pour résoudre les problèmes des réseaux électriques. Dans cet article, les principaux problèmes af-fectant le secteur de l'énergie en Afrique sont identifiés, certaines solutions aux défis de la maîtrise de ce secteur sont rappelées et de nouvelles solutions sont proposées, en mettant l'accent sur les outils de mathématiques appliquées ainsi que sur la politique énergétique. A titre d'illustration des nouvelles solutions mathématiques, une nouvelle stratégie de contrôle du compensateur statique, synchrone et série (SSSC) qui fait partie des systèmes modernes et flexible de transmission du courant alternatif (FACTS) est proposée pour le contrôle du flux de puissance
Caractérisation de la fissuration de bois tropicaux en mode mixte par la méthode de la grille
No full textInternational audienceRESUME Cet article traite de la caractérisation de la fissuration en mode mixte de trois essences tropicales gabonaises : le Milicia excelsa (iroko), l'Aucoumea klaineana (okoumé) et le Pterocarpus soyauxii (padouk). Une approche expérimentale basée sur la méthode de la grille est proposée. Les courbes force-déplacement, le processus de croissance de la fissure ainsi que l'ouverture de fissure sont déduits des images enregistrées. La méthode permet également de calculer le taux de restitution d'énergie critique d'éprouvettes modifiées Mixed Mode Crack Growth (MMCG) avec des taux de mixité de 15° et 30° en s'appuyant sur la méthode de la complaisance. Les résultats montrent une influence de la densité sur les taux de restitution d'énergie et indiquent également que le rapport GI/GII est constant. Mots clés : bois tropicaux clés ; méthode de la grille ; éprouvette MMCG ; taux de restitution d'énergie
Spatio‐temporal variability of rainfall in a high tropical island: Patterns and large‐scale drivers in Réunion Island
No full textInternational audienceWeather forecasting is challenging because of the complex interplay between local conditions and regional atmospheric forcings. In this article, we analyse the relationships between local daily rainfall and large‐scale synoptic patterns in the geographical context of Réunion Island, a high volcanic island in the southwestern Indian Ocean basin. Given the critical role of trade winds on weather conditions at island scale, we analyse those relationships across seasons defined with respect to yearly trade‐wind regimes. The analysis of the distribution of inversion events' elevation and frequency allows us to characterize the trade‐wind inversion layer (TWIL) and identify four seasons with homogeneous distributions. We characterize the spatio‐temporal variability of rainfall measured at island scale by a dense network of rain‐gauges over 37 years and relate it to large‐scale weather regimes identified using geopotential height meteorological data. After seasonal signal removal using Fourier transforms and dimension reduction via Principal Component Analysis, we perform Canonical Correlation Analysis to identify canonical variables relating rainfall and geopotential height patterns at the two different studied spatial scales. We then combine Ascending Hierarchical Classification and partitioning k‐means methods to identify homogeneous large‐scale synoptic conditions within each season. From this information, we build composite maps of geopotential height that characterize weather regimes and further analyse rainfall patterns at island scale in each regime. Elevation and orientation are used as descriptive variables at island scale as they strongly structure the patterns. Overall, four homogeneous seasons were identified based on trade‐wind regimes, within which six large‐scale weather regimes were identified for summer, the most variable season, and four for the others. Finally, rainfall patterns at island scale are described in relation to the highlighted synoptic regimes and local descriptive variables
The Xe‐SiO 2 System at Moderate Pressure and High Temperature
No full textInternational audienceXenon (Xe), the heaviest of the stable noble gases, is missing by a factor of 20 relatively to other noble gases, when comparing the Earth's and Mars's atmospheres with chondrites. In this work, the possibility of Xe retention in quartz, a major mineral of the continental crust, is tested. The Xe-SiO 2 system is investigated from 0.7 to 2.7 GPa and up to 1900 K, by in situ X-ray powder diffraction and infrared spectroscopy. Experimental data are complemented by ab initio calculations to retrieve Xe incorporation mechanisms. An excess of quartz unit cell volume up to 4.2% is observed, consistent with a Xe for Si substitution in the quartz structure. Xe has a linear oxygen environment composed of two O atoms located at 1.98-2.00 Å from the Xe atom. Moreover, a new phase is evidenced above Xe melting curve at 0.8-1.0 GPa. The new (Xe,Si)O 2 phase is orthorhombic and corresponds to an elongation of the quartz unit cell. In this phase, Xe substitutes for Si with a nearly planar oxygen environment composed of four O atoms located at 2.06-2.09 Å from the Xe atom. Xe incorporation in SiO 2 proves to be significant, as previously shown for olivine. Xe incorporation is therefore expected to occur in the whole range of lithospheric silicate minerals. These findings emphasize the need to consider Xe incorporation in crust and upper mantle minerals as a process to store and fractionate xenon, in the framework of the "missing xenon" issue
Telomerase Activation and ATRX Mutations Are Independent Risk Factors for Metastatic Pheochromocytoma and Paraganglioma
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Actualisation des recommandations françaises de traitement du pemphigus
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De quelques media morts-vivants. Littérature médiévale et archéologie des media
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Impact of host endosymbionts on parasitoid host range — from mechanisms to communities
No full textInternational audienceIn insects, bacterial endosymbionts are known to influence the ecology of their hosts by modifying interactions with natural enemies such as parasitoids. Symbionts can modulate both parasitoid behavioral and/or physiological traits as well as host behaviors and life-history traits. Together these suggest that endosymbionts may impact the host range of parasitoids. For example, endosymbionts may narrow parasitoid host range through first, reducing parasitoid ability to locate hosts and/or larval survival, second, affecting fitness traits of the emerging adult parasitoid and/or third, modulating the outcome of interference and exploitative competition between parasitoid species. From both a fundamental and applied point of view, these symbiotic effects would influence the ecology and evolution of parasitoids and associated population-level processes and ecosystem services (e.g. biocontrol)