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Protéger les cultures grâce à la diversité végétale : promesses agroécologiques, verrouillage socio-économique et leviers politiques
No full textInternational audiencePlant diversification at field, farm, and landscape scales is a key strategy for protecting crops from pests. But its level of adoption remains confidential, while the overall negative impacts of pesticides are now well established. To understand the obstacles to this adoption, we conducted an extensive review of literature in life and socio-economic sciences. We found that all diversification practices are largely effective in pest control, achieving satisfactory yields and many ecological cobenefits, although context dependent. Plant diversification does not appear solely as an alternative to pesticide-based pest control but as a transformative approach to achieve sustainable agrifood systems. However, its adoption is currently strongly hindered by socioeconomic barriers, including low short-term profitability, rigid agricultural sectors, and limited support from public policies. The most beneficial practices, agroforestry and diversified landscapes, face the greatest obstacles. In contrast, cultivar mixtures, while easier to implement, offer limited cobenefits. Collaboration between scientists, policymakers, and local stakeholders seems essential to scale up plant diversification.La diversification des plantes à l'échelle du champ, de l'exploitation et du paysage est une stratégie clé pour protéger les cultures contre les parasites. Mais son niveau d'adoption reste confidentiel, alors que les impacts négatifs globaux des pesticides sont désormais bien établis. Pour comprendre les obstacles à cette adoption, nous avons procédé à un examen approfondi de la littérature dans le domaine des sciences de la vie et des sciences socio-économiques. Nous avons constaté que toutes les pratiques de diversification sont largement efficaces dans la lutte contre les ravageurs et permettent d'obtenir des rendements satisfaisants et de nombreux avantages écologiques, bien qu'elles dépendent du contexte. La diversification des plantes n'apparaît pas seulement comme une alternative à la lutte contre les ravageurs à l'aide de pesticides, mais comme une approche transformatrice permettant de mettre en place des systèmes agroalimentaires durables. Toutefois, son adoption est actuellement fortement entravée par des obstacles socio-économiques, notamment la faible rentabilité à court terme, la rigidité des secteurs agricoles et le soutien limité des politiques publiques. Les pratiques les plus bénéfiques, à savoir l'agroforesterie et les paysages diversifiés, se heurtent aux obstacles les plus importants. En revanche, les mélanges de cultivars, bien que plus faciles à mettre en œuvre, offrent des avantages connexes limités. La collaboration entre les scientifiques, les décideurs politiques et les acteurs locaux semble essentielle pour développer la diversification végétale
Reconstruction of the volcanic history of Grande Comore and volcano-tectonic implications for the Comoros Archipelago
No full textInternational audienceSince the onset of Fani Maore submarine eruption, the volcanism of the Comoros Archipelago has gained renewed interest. Geochronological constraints have been recently obtained for Mohéli, Anjouan and Mayotte islands and nearby seamounts. Here we provide new groundmass K-Ar ages for Grande Comore. Along with major and trace element geochemistry and geomorphological analyses, these ages enable us to propose a three stages reconstruction of the island. The first, or M'Badjini stage, is much older than previously thought, with ages as old as 2.2 Ma. Following a period of quiescence and dismantling, the second phase occurred between 280 and 230 ka, probably on both La Grille and Karthala volcanoes. Then, volcanic activity resumed for a third phase from ca. 130 ka until present time. The Comoros geochronological database, updated with our new results, confirms that the construction history of the archipelago occurred as pulses and follows a northward propagation of volcanism (i.e. a widening of the volcanically active region)
8e Atelier "Apprentissage de la pensée informatique de la maternelle à l'Université (APIMU 1000)" @ EIAH 2025
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IMPACT DE LA MECANISATION SUR LE POTENTIEL DE LA CONCENTRATION DES MPD DANS LA MINE SOUTERRAINE DE KINSENDA
No full textInternational audienceIn 2014, the KINSENDA “KICC” underground mine acquired major diesel-powered equipment to meet production requirements, which, as a result of incomplete internal combustion, emit diesel particulate matter “DPM” from the exhaust gases. These gases constitute a new type of contaminants that the mine ventilation system must integrate into dilution operations and can be potentially harmful to human health at high exposure levels “ELV”.The aim of this research is to assess the impact of mechanization on the potential concentration of these gases, to calculate the quantity of air required for their dilution according to some of the mine's indices, and to propose a re-adaptation of the ventilation system. The methodology used will consist in determining the indicators for estimating DPM by assessing respirable combustible dust (RCP) and carbon according to the appropriate protocol. Standard sampling systems were used, as well as Drager accuro and DRAGER X-ACT 5000 instruments. The various DPM level measurements carried out in the mine during the 2023 period indicate the presence of high concentrations of exhaust gas emissions depending on production or development activities.Analytical index calculations for the mine show 542.63 m 3/s, the air flow rate required for dilution, which is double that supplied by the mine's main fans (245.75 m 3/s), and also the ratio of the flow rate required by the machinery used by the two contractors, giving KKC's Vm (%) equal to 109.74 and Phoenix's Vm (%) equal to 111.7 ; i.e. a rate greater than unity, representing a malfunction between the flow required to dilute the mine's exhaust gases and that supplied by the fansKey words: MPD, KICC, VLE, PCR, DilutionLa mine souterraine de KINSENDA « KICC » a acquis en 2014 d’importants équipements mus au moteur diesel compte tenu des exigences de la production et qui, suite à une combustion interne incomplète émettent des matières particulaires diesel « MPD » provenant des gaz d’échappement. Ces gaz constituent un nouveau type de contaminants que le système de ventilation de la mine doit intégrer dans des opérations de dilution et peuvent être potentiellement nocives à la santé humaine à des niveaux d'exposition élevés « VLE ». Cette recherche vise l’évaluation de l’impact de la mécanisation sur le potentiel de la concentration de ces gaz, le calcul de la quantité d’air utile pour leur dilution suivant quelques indices de la mine ainsi que la proposition d’une réadaptation du système de ventilation. La méthodologie utilisée consistera à déterminer les indicateurs de l’estimation des MPD par l’évaluation des poussières combustibles respirables « PCR » et de carbone suivant le protocole adapté. Les systèmes d’échantillonnage standards ont été utilisés ainsi que les appareils Drager accuro et DRAGER X-ACT 5000. Les différentes mesures de niveau de MPD effectuées dans la mine durant l’année 2023 signalent la présence des concentrations des émissions de gaz d’échappement selon les activités de la production ou du développement à un taux élevé. Les calculs analytiques d’indices révèlent 542, 63 m3/s le débit d’air requis pour la dilution qui est le double de celui fourni par les ventilateurs principaux de la mine donc 245,75 m3/s, et aussi le taux de proportion du débit exigé par la machinerie des équipements utilisés des deux entrepreneurs donnent respectivement le Vm (%) pour KKC et PHOENIX 109,74 et 111,7 ; donc des taux supérieurs à l’unité, ce qui atteste le disfonctionnement entre le débit requis pour la dilution des gaz et celui fourni par les ventilateursMots clés : MPD, KICC, VLE, PCR, Dilutio
Projections of extreme rainfall and floods in Mediterranean basins from an ensemble of convection-permitting models
No full textInternational audienceFloods have major impacts in the Mediterranean regions, but their evolution with climate change is unclear. This issue is related to the inadequacy of climate and hydrological models in terms of spatial and temporal resolutions to simulate flash floods over small basins. This study explores future flood scenarios of 12 Mediterranean basins using meteorological forcings from an ensemble of high-resolution convection-permitting climate models. Results indicate an overall increase in flood intensity across all basins, particularly for the most severe events, but also a strong spatial variability of the climate change signal given the geographic location and catchment characteristics. There is a good agreement between the models towards an increase of hourly rainfall extremes, but these changes are not well correlated with changes in floods, indicating that rainfall intensity alone is a poor predictor of future floods. An overall conclusion towards an increase of floods in this region is limited by the short length of the available high-resolution climate simulations. Longer time series are required to better assess the robustness of the projected changes
Comparison of liquid-vapor relations and the critical points of CaO and MgO
No full textInternational audienceRefractory materials play an important role in lunar formation as they are some of the first components to coalesce from vaporized material that resulted from a giant impact. CaO is chemically and structurally similar to MgO and together they make up over 40% of both pyrolite and lunar composition models. In this work, we explore the liquid-vapor coexistence region of CaO. We determine the critical point to be located between 6000 and 6500 K and between 0.3 and 0.7g/cm3, which puts it slightly below the one previously obtained for MgO. Structurally, both CaO and MgO consist mostly of sixfold and sevenfold coordinated cations at the higher density and threefold and fourfold ones at the lower end of the density studied. The vapor consists mainly of Ca, CaO, O, O2, Ca2O2, Ca2O, and CaO2. The main difference with MgO is that the relative abundance of molecular oxygen is much lower in the vapor of CaO. Similarly to the MgO system, we find that the vapor appears to be close to neutral in charge, indicating an atomic vapor as opposed to an ionic one
Characterization of copepod ingestion rates in the Humboldt Archipelago and implications for a biogeochemical model in the Coquimbo upwelling system
No full textInternational audienceCopepod ingestion rates (IR) have not yet been addressed in the upwelling system of Coquimbo (30°S), despite their critical role in linking the region's high primary productivity to upper trophic levels and biodiversity within the Humboldt Archipelago. Given its natural variability and influence on mesozooplankton biomass, IR represents a challenging step during the parameterization of biogeochemical models employed to understand and predict the productivity of marine ecosystems. This has led to a reliance on simplified and imported information that does not necessarily represent the local environmental-ecological context, significantly influencing the uncertainty of the current generation of Earth system models. In the upwelling system of Coquimbo, the ENSO-Climate change and Carbon Cycle in the Pacific Southeast (ECLIPSE) project is parameterizing a coupled Biogeochemical model for Eastern Boundary Upwelling Systems (BioEBUS) since 2022. Thus, in addition to characterizing the IR of the copepods, the research effort aims to understand the relationship between the El Niño Southern Oscillation (ENSO) and oxygen/CO2 fluxes in the sub-tropical upwelling regions of the HCS. To constrain BioEBUS outputs, in this study we report the results of grazing experiments conducted in the system throughout the 2023–2024 seasonal cycle, with different copepod species under food resources varying between 18 and 30 mg Chl m‑2 and 1–7 g C m‑2. The IR of Calanus chilensis (copepodite V and adult females), Calanoides patagoniensis, Metridia lucens and Paracalanus cf. indicus varied between 2 and 63 μg C ind‑1 d‑1, maximum IR was 1.6 d‑1, while the IR of the corresponding size class reached 300 g C m‑2 d‑1. These results may alert the modeling community to reconsider parameterization information regarding mesozooplankton grazing rates
Seasonal Variation in the Biochemical Composition and Fatty Acid Profiles of the Red Alga Halymenia durvillei from Ngazidja (Comoros)
No full textInternational audienceThe study of Comorian red alga Halymenia durvillei showed a significant biochemical composition with high ash and polysaccharide content and the presence of n-3 and n-6 essential fatty acid molecules. Seasonal monitoring showed a real change in biochemical composition depending on the harvesting period. On an annual average basis, the algae contained 35.59 ± 2.55% dw ashes, 0.7 ± 0.19% dw soluble proteins, 0.27 ± 0.02% dw total lipids, and 35.09 ± 6.14% dw polysaccharides. The pigment composition was 130 µg/g dw R-phycoerythrin, 1.49 µg/g dw chlorophyll a, and 0.09 µg/g dw carotenoids. The most abundant fatty acid identified was palmitic acid (C16:0), which accounted for almost 43.33% of total fatty acids. Oleic acid (C18:1n-9) was the most abundant unsaturated fatty acid, at 11.58%. Linoleic acid (C18:2n-6) was reported to be the most abundant polyunsaturated fatty acid in Halymenia durvillei. The fatty acid profile was also characterized by arachidonic acid (C20:4n-6) and eicosapentaenoic acid (C20:5n-3)
PROVAXHPV-3 : Protocole d’étude en vue d’une autonomisation de l’infirmier(e) scolaire dans la vaccination scolaire anti-HPV chez les élèves de 5ème en France
No full textBackground: HPV is responsible for many cancers, but vaccination coverage is low in France. A school vaccination campaign for 7th graders exists since 2023, currently carried out by mobile teams from external vaccination centers. Number of studies around the world have identified school nurses as confidence facilitators in school vaccination. Method: Prospective randomized multicenter interventional study in clusters, over one school year, comparing 4 vaccination strategies in 7th graders in a French academy: (1) by an external mobile vaccination team as recommended by the Government, (2) by an external mobile vaccination team plus a school nurse for the rest of the year, (3) by a school nurse alone for the whole school year, and (4) by a school nurse alone with a financial bonus according to the number of vaccinations performed. Expected results: Significantly higher vaccination coverage for girls and boys is expected in the 2nd, 3rd and 4th groups involving the school nurse, compared with the control strategy in the 1st group, given an easier organization and a bond of trust with the pupils. In addition, a better cost-effectiveness ratio is expected in these same three groups, enabling both an increase in HPV vaccination coverage and public health savings. Conclusion: This original study protocol will shed light on the best school-based HPV vaccination strategy, with the aim of achieving the 70% national vaccination coverage rate recommended by the HCPH, and ensuring the long-term sustainability of the project at a lower cost.Introduction : L’HPV est responsable de nombreux cancers, mais la couverture vaccinale est faible en France. Une campagne de vaccination scolaire chez les élèves de 5ème existe depuis 2023, actuellement réalisée par des équipes mobiles de centres de vaccination extérieurs. Plusieurs études mondiales exposent les IDE scolaires comme leviers facilitateurs de confiance dans la vaccination scolaire. Méthode : Étude interventionnelle prospective randomisée multicentrique en clusters, sur une année scolaire, comparant 4 stratégies vaccinales chez les élèves de 5ème de collèges d’une académie française : (1) par une équipe mobile vaccinale extérieure telle que préconisée par le Gouvernement, (2) par une équipe mobile vaccinale extérieure ainsi que par une IDE scolaire le reste de l’année, (3) par une IDE scolaire seul(e) toute l’année, enfin (4) par une IDE scolaire seul(e) avec prime financière selon le nombre de vaccinations réalisées. Résultats attendus : Il sera attendu une couverture vaccinale significativement plus élevée chez les filles et les garçons dans les 2ème, 3ème et 4ème groupes impliquant l’IDE scolaire comparativement à la stratégie témoin du 1er groupe, de par une organisation facilitée et un lien de confiance avec les élèves. Par ailleurs, il est attendu un meilleur ratio coût-efficacité dans ces trois mêmes groupes, permettant à la fois une augmentation de la couverture vaccinale contre l’HPV et une économie de santé publique. Conclusion : Ce protocole d’étude originale mettra en lumière la meilleure stratégie vaccinale scolaire anti-HPV et ainsi espérer atteindre les 70% de taux de couverture vaccinale nationale recommandés par le HCSP et s’assurer d’une pérennisation de l’action à moindre coût