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The medieval bombards of Meaux: Manufacturing processes and supply of the metal
No full textInternational audienceWell-dated and preserved medieval bombards are rare and, most of the time, only exist in single exemplar. They are nevertheless exceptional testimonies of the medieval metallurgical skills. The musée de l'Armée (Paris), owns six impressive powder chambers, found in the same place (Meaux, France) and dated from the same period (15th c.). For the first time, this unique set has been studied by classical metallographic investigation, and recent approaches on slag inclusions using SEM-EDS and LA-ICP-MS analyses. The analyses permit to discuss the nature of the metal as well as the process used to obtain the metal (bloomery or finery) but also to consider the diversity of provenances for the metal that was used. These results suggest that five bombards may have been forged in the same area and possibly even in the same workshop, but anyway using metal produced through the bloomery process
L’effet de la mise en scène sur la compréhension et l’engagement des élèves: la théâtralisation comme vecteur de réussite scolaire ?
No full textDevant un public d’élèves de plus en plus exigeants, les enseignants ont recours à de multiples pratiques pour capter leur attention et accroître ainsi la réussite des élèves. L’une d’elle, la théâtralisation, est souvent mobilisée face à un jeune public lors de la lecture d’un album de jeunesse. Nous nous sommes efforcées de tenter de déterminer si à l’entrée à l’école élémentaire, les élèves étaient affectés par cette mise en scène lors de la construction du sens. Plus précisément, nous cherchions à comprendre si la mise en scène d’une présentation participe à une meilleure compréhension de celle-ci, tout en suscitant l’engagement des élèves. Pour cela, nous avons conduit une étude auprès de 15 élèves au sein de l’école Jules Guesde 1 à Argenteuil.Les résultats obtenus suggèrent que cette pratique présente plusieurs intérêts pour les élèves comme :- Captiver leur attention- Susciter leur adhésion et leur intérêt- Créer une curiosité et un certain engouement pour connaître la suite- Induire une mémorisation plus efficace et une meilleure appropriation de l’histoireAu-delà de cela, pour les élèves exprimant des difficultés, cette théâtralisation lève un certain nombre d’obstacles potentiels dans l’élaboration du sens, tel que celui lié au lexique mobilisé. Ce choix de pratique permet ainsi de rétablir l'enjeu phare de l’école du XXIe siècle : l'égalité des chances
Fabien Granjon, Classes populaires et usages de l’informatique connectée. Des inégalités sociales-numériques.
No full textInternational audienc
Virgo Filaments. II. Catalog and First Results on the Effect of Filaments on Galaxy Properties
No full textInternational audienceVirgo is the nearest galaxy cluster; it is thus ideal for studies of galaxy evolution in dense environments in the local universe. It is embedded in a complex filamentary network of galaxies and groups, which represents the skeleton of the large-scale Laniakea supercluster. Here we assemble a comprehensive catalog of galaxies extending up to ∼12 virial radii in projection from Virgo to revisit the cosmic-web structure around it. This work is the foundation of a series of papers that will investigate the multiwavelength properties of galaxies in the cosmic web around Virgo. We match spectroscopically confirmed sources from several databases and surveys including HyperLeda, NASA Sloan Atlas, NASA/IPAC Extragalactic Database, and ALFALFA. The sample consists of ∼7000 galaxies. By exploiting a tomographic approach, we identify 13 filaments, spanning several megaparsecs in length. Long >17 h –1 Mpc filaments, tend to be thin (<1 h –1 Mpc in radius) and with a low-density contrast (<5), while shorter filaments show a larger scatter in their structural properties. Overall, we find that filaments are a transitioning environment between the field and cluster in terms of local densities, galaxy morphologies, and fraction of barred galaxies. Denser filaments have a higher fraction of early-type galaxies, suggesting that the morphology–density relation is already in place in the filaments, before galaxies fall into the cluster itself. We release the full catalog of galaxies around Virgo and their associated properties
A combined use of in situ and satellite-derived observations to characterize surface hydrology and its variability in the Congo River basin
No full textInternational audienceThe Congo River basin (CRB) is the second largest river system in the world, but its hydroclimatic characteristics remain relatively poorly known. Here, we jointly analyse a large record of in situ and satellite-derived observations, including a long-term time series of surface water height (SWH) from radar altimetry (a total of 2311 virtual stations) and surface water extent (SWE) from a multi-satellite technique, to characterize the CRB surface hydrology and its variability. First, we show that SWH from altimetry multi-missions agrees well with in situ water stage at various locations, with the root mean square deviation varying from 10 cm (with Sentinel-3A) to 75 cm (with European Remote Sensing satellite-2). SWE variability from multi-satellite observations also shows a plausible behaviour over a ∼25-year period when evaluated against in situ observations from the subbasin to basin scale. Both datasets help to better characterize the large spatial and temporal variability in hydrological patterns across the basin, with SWH exhibiting an annual amplitude of more than 5 m in the northern subbasins, while the Congo River main stream and Cuvette Centrale tributaries vary in smaller proportions (1.5 to 4.5 m). Furthermore, SWH and SWE help illustrate the spatial distribution and different timings of the CRB annual flood dynamic and how each subbasin and tributary contribute to the hydrological regime at the outlet of the basin (the Brazzaville/Kinshasa station), including its peculiar bimodal pattern. Across the basin, we estimate the time lag and water travel time to reach the Brazzaville/Kinshasa station to range from 0-1 month in its vicinity in downstream parts of the basin and up to 3 months in remote areas and small tributaries. Northern subbasins and the central Congo region contribute highly to the large peak in December-January, while the southern part of the basin supplies water to both hydrological peaks, in particular to the moderate one in April-May. The results are supported using in situ observations at several locations in the basin. Our results contribute to a better characterization of the hydrological variability in the CRB and represent an unprecedented source of information for hydrological modelling and to study hydrological processes over the region
Surveying the Surveyors to Address Risk Perception and Adaptive Behaviour Cross-study Comparability
No full textInternational audienceOne of the key challenges for risk, vulnerability, and resilience research is how to address the role of risk perceptions and how perceptions influence behaviour. It remains unclear why people fail to act adaptively to reduce future losses, even when there is ever richer information available on natural and human-made hazards (flood, drought, etc.). The current fragmentation of the field makes it an uphill battle to cross-validate the results of existing independent case studies. This, in turn, hinders comparability and transferability across scales and contexts and hampers recommendations for policy and risk management. To improve the ability of researchers in the field to work together and build cumulative knowledge, we question whether we could agree on (1) a common list of minimal requirements to compare studies, (2) shared criteria to address context-specific aspects of countries and regions, and (3) a selection of questions allowing for comparability and long-term monitoring. To map current research practices and move in this direction, we conducted an international survey – the Risk Perception and Behaviour Survey of Surveyors (Risk-SoS). We find that most studies are exploratory in nature and often overlook theoretical efforts that would enable the comparison of results and an accumulation of evidence. While the diversity of approaches is an asset, the robustness of methods is an investment. Surveyors report a tendency to reproduce past research design choices but express frustration with this trend, hinting at a turning point. To bridge the persisting gaps, we offer several recommendations for future studies, particularly grounding research design in theory, improving the formalisation of methods, and formally comparing theories and constructs, methods and explanations while collecting the most-in-use themes and variables and controlling for the most-in-use explanations
Quand les engins de déplacement personnel transforment la mobilité urbaine
No full textNational audienceLes engins de déplacement personnel (EDP) viennent bousculer la mobilité urbaine. Qu’il s’agisse de trottinette, de gyroroue, de skateboard, ces modes individuels légers permettent de parcourir quelques kilomètres et éventuellement de pratiquer l’intermodalité. L’objectif de cet article est de faire un point sur la connaissance actuelle des pratiques de micromobilité et d’estimer l’impact à terme du développement de ces « nouveaux » modes
