International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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Association between thermal responses, medical events, performance, heat acclimation and health status in male and female elite athletes during the 2019 Doha World Athletics Championships
No full textInternational audiencePurpose To determine associations between thermal responses, medical events, performance, heat acclimation and health status during a World Athletics Championships in hot-humid conditions. Methods From 305 marathon and race-walk starters, 83 completed a preparticipation questionnaire on health and acclimation. Core (T core ; ingestible pill) and skin (T skin ; thermal camera) temperatures were measured in-competition in 56 and 107 athletes, respectively. 70 in-race medical events were analysed retrospectively. Performance (% personal best) and did not finish (DNF) were extracted from official results. Results Peak T core during competition reached 39.6°C±0.6°C (maximum 41.1°C). T skin decreased from 32.2°C±1.3°C to 31.0°C±1.4°C during the races (p<0.001). T core was not related to DNF (25% of starters) or medical events (p≥0.150), whereas T skin , T skin rate of decrease and T core -to-T skin gradient were (p≤0.029). A third of the athletes reported symptoms in the 10 days preceding the event, mainly insomnia, diarrhoea and stomach pain, with diarrhoea (9% of athletes) increasing the risk of in-race medical events (71% vs 17%, p<0.001). Athletes (63%) who performed 5–30 days heat acclimation before the competition: ranked better (18±13 vs 28±13, p=0.009), displayed a lower peak T core (39.4°C±0.4°C vs 39.8°C±0.7°C, p=0.044) and larger in-race decrease in T skin (−1.4°C±1.0°C vs −0.9°C±1.2°C, p=0.060), than non-acclimated athletes. Although not significant, they also showed lower DNF (19% vs 30%, p=0.273) and medical events (19% vs 32%, p=0.179). Conclusion T skin , T skin rate of decrease and T core -to-T skin gradient were important indicators of heat tolerance. While heat-acclimated athletes ranked better, recent diarrhoea represented a significant risk factor for DNF and in-race medical events
Evolution of continental temperature seasonality from the Eocene greenhouse to the Oligocene icehouse –a model–data comparison
No full textInternational audienceAt the junction of greenhouse and icehouse climate states, the Eocene–Oligocene Transition (EOT) is a key moment in Cenozoic climate history. While it is associated with severe extinctions and biodiversity turnovers on land, the role of terrestrial climate evolution remains poorly resolved, especially the associated changes in seasonality. Some paleobotanical and geochemical continental records in parts of the Northern Hemisphere suggest the EOT is associated with a marked cooling in winter, leading to the development of more pronounced seasons (i.e., an increase in the mean annual range of temperature, MATR). However, the MATR increase has been barely studied by climate models and large uncertainties remain on its origin, geographical extent and impact. In order to better understand and describe temperature seasonality changes between the middle Eocene and the early Oligocene, we use the Earth system model IPSL-CM5A2 and a set of simulations reconstructing the EOT through three major climate forcings: pCO2 decrease (1120, 840 and 560 ppm), the Antarctic ice-sheet (AIS) formation and the associated sea-level decrease. Our simulations suggest that pCO2 lowering alone is not sufficient to explain the seasonality evolution described by the data through the EOT but rather that the combined effects of pCO2, AIS formation and increased continentality provide the best data–model agreement. pCO2 decrease induces a zonal pattern with alternating increasing and decreasing seasonality bands particularly strong in the northern high latitudes (up to 8 ∘C MATR increase) due to sea-ice and surface albedo feedback. Conversely, the onset of the AIS is responsible for a more constant surface albedo yearly, which leads to a strong decrease in seasonality in the southern midlatitudes to high latitudes (>40∘ S). Finally, continental areas that emerged due to the sea-level lowering cause the largest increase in seasonality and explain most of the global heterogeneity in MATR changes (ΔMATR) patterns. The ΔMATR patterns we reconstruct are generally consistent with the variability of the EOT biotic crisis intensity across the Northern Hemisphere and provide insights on their underlying mechanisms
Une contribution pour une meilleure circulation entre les niveaux de savoir via un TP portant sur la saponification
No full textInternational audienceThis article aims to show the impact of a practical course on saponification on the distinction between levels of knowledge. The study was carried out in Cameroon in a scientific 12th grade class. The class divided into two groups : "experimental" group having followed the practical training and "theoretical" group not having followed the practical training. An analysis was carried out in order to show that the students having followed the practical training circulate more between the levels of knowledge compared to those of the theoretical class.Cet article vise à montrer l'impact de travaux pratiques portant sur la saponification, sur la distinction des niveaux de savoir. L'étude a été réalisée au Cameroun dans une classe de terminale scientifique. La classe est scindée en deux : groupe « expérimental » ayant suivi cette expérimentation et groupe « théorique » ne l'ayant pas suivie. Une analyse a été réalisée afin de montrer que les élèves ayant suivi les travaux pratiques circulent davantage entre les niveaux de savoir par rapport à ceux de la classe théorique
La dérivation illocutoire
No full textTout comme il est démontré que sans les tropes le langage serait impossible, il est aussi aisé de comprendre que le trope illocutoire (KERBRAT-ORECCHIONI, 1994) ou dérivation illocutoire est au cœur des actes de langage. Sa motivation est la nécessité de préserver la face qui oblige à une communication indirecte ou implicite parce que Tout ce qui est dit peut-être contredit. (DUCROT, 1972, p. 6). Ainsi, des actes de langage, comme l’affirmation ou la question, peuvent dériver d’autres qui se présentent souvent comme une requête
« L’évolution constitutionnelle du Mozambique : un cadre constitutionnel peu en phase avec le cadre social »
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A porosity-based flood inundation modelling approach for enabling faster large scale simulations
No full textInternational audienceFloods are among the most devastating natural hazards in the world. With climate change and growing urbanisation, floods are expected to become more frequent and severe in the future. Hydrodynamic models are powerful tools for flood hazard assessment but face numerous challenges, especially when operating at a large scale. The downside of discretising an area using a fine mesh yielding more accurate results, is the expensive computational cost of simulations. Moreover, critical input information such as bathymetry (i.e, riverbed geometry) are required but cannot be easily collected by field measurements or remote sensing observations. During the past few years, the development of sub grid models has gained a growing interest as these enable faster simulations by using coarser cells and, at the same time, preserve small-scale topography variations within the cell. In this study, we propose and evaluate a modelling framework based on the shallow water 2D model with depth-dependent porosity enabling to represent floodplain and riverbed topography through porosity functions. To enable a careful and meaningful evaluation of the model, we set up a 2D classical model and use it as a benchmark. We also exploit ground truth data and remote sensing derived flood inundation maps to evaluate the proposed modelling framework and use as test cases the 2007 and 2012 flood events of the river Severn. Our empirical results demonstrate a high performance and low computational cost of the proposed model for fast flood simulations at a large scale
Identité de l'adolescent mahorais en situation de handicap : choix et non choix d'orientation
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Development of biobased emulsions for postharvest citrus fruit preservation
No full textInternational audiencePenicillium digitatum is the causal agent for citrus green mold which generates 90% of post-harvest losses in Mediterranean countries. The use of a green seaweed extract to fight this fungal pathogen could represent an ecofriendly alternative to chemical fungicides. We propose to formulate an aqueous extract from Ulva lactuca (8.3%) in an emulsion for the preventive treatment of oranges. New biobased emulsifiers, alkyl aconitates, were synthesized according to a green process and were characterized by their hydrophilic and lipophilic balance (HLB) and their critical micelle concentration (CMC). These mono-, di and tri-dodecyl aconitates (8%) were effective in stabilizing an oil-in-water emulsion including the natural U. lactuca extract. The viscosities of resulting emulsions helped to form a film on the orange surface. Several in vitro microbiological tests towards Penicillium digitatum showed interesting anti-fungal activities for the new ingredients, as well as for the resulting emulsions. In-vivo tests also confirmed that mono-, di- and tri-docedyl aconitates could contribute to limit the development of P. digitatum on peel surface. Thus, the compositions of two ecofriendly emulsions combining a natural extract and a biobased emulsifier seem adapted to improve oranges preservation
Urban flood susceptibility modelling using AHP and GIS approach: case of the Mfoundi watershed at Yaoundé in the South-Cameroon plateau
No full textInternational audienceFloods are considered as the natural hazards that affect the world's major metropolises the most. Thus, the present study aimed at evaluating the sensitivity to flood risks of the Mfoundi watershed (96.5 km2) located in the heart of the Cameroonian political capital in a tropical humid forest zone, more precisely in the South Cameroon plateau. The methodological approach adopted was to identify the factors that most favor the risk of flooding in the area from intense literature review and field investigations; the analysis of these factors and the calculation of the Flood Harzard Index (FHI) using the Analytical Hierarchy Process (AHP) approach coupled with the Geographical Information System (GIS) environment. The results reveal that among the ten parameters of the natural environment (elevation, drainage density, rainfall, slope, distance from the river, topographic humidity, hydraulic conductivity, groundwater level, geology and land cover) selected, the land cover, elevation and the geology are the factors that most influences the flooding phenomenon in the area. The value of Flood Hazard Index (FHI) varied from 4.16 to 9.16, the higher the value, the more sensitive the area is to the risk of flooding. Five main classes of flood susceptibility are highlighted: very low, low, moderate, high and very high, representing 9.50, 26, 23, 22 and 19.5%, respectively of the study area. To validate the efficiency of the obtained flood susceptibility map, the adopted Area Under the Curve (AUC) method shows a very good accuracy (0.84 or 84%). The results of this study constitute a basic tool for decision-making for environmental management by public authorities and decentralised territorial authorities with territorial jurisdiction
Geochemical evolution of soils on Reunion Island
No full textInternational audienceChemical weathering of basaltic rocks plays a major role in the regulation of the global carbon cycle at geological timescales, in particular tropical, basaltic islands although representing a small area of exposed land. Although soils from Hawai’i have been extensively studied, other tropical islands have received much less attention. In this study, we investigate the mineralogical and geochemical composition of three weathering profiles developed on stable landforms (planèzes) of Reunion Island, Indian Ocean. Pyroxenes and feldspars are progressively replaced by gibbsite and halloysite, and differences in weathering extent could be accounted for by the variable composition of the parent material. Only where soil has been developing for up to two million years we observe a complete loss of primary minerals and soluble elements throughout the entire profile. Elsewhere, complete loss is only achieved in the top meter. Chemical erosion and CO2 consumption fluxes estimated using soil geochemistry at the study sites, correspond to a small fraction of the overall fluxes for Reunion Island. These observations suggest that stable landforms play a limited role on chemical weathering on tropical, basaltic island, where hydrothermal alteration and weathering of rapidly eroding regions dominate. These results also show that, despite extreme weather events, stable landforms of Reunion Island, preserve a large fraction of their soluble element budget (including nutrients) for 100,000′s of years (possibly replenished by atmospheric inputs).Moreover, modelling of uranium-series isotope compositions shows that, in the topsoil, weathering ages (time elapsed since onset of chemical weathering) are similar to the age of the parent material for each profile, providing an independent validation of the use of uranium-series isotopes in weathering profiles to derive weathering ages and soil production rates. All profiles show a decrease in production rates with decreasing depth and a negative relationship between production rates and weathering ages, illustrating the depletion of soluble material with time. While production rates exceed 100 mm/kyr in the early stages of basalt weathering, they slow down to only a few mm/kyr after a million years