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Surface water and flood-based agricultural systems : mapping and modelling long-term variability in the Senegal river floodplain
No full textInternational audienceIn the alluvial plains of large rivers, annual flooding is essential for numerous ecosystem services, including flood-based agriculture, biodiversity and groundwater recharge. Remote sensing provides increased opportunities to monitor surface water dynamics across large floodplains that are currently poorly captured by local hydrological monitoring and modelling due to data scarcity and the flat, heterogeneous topography. Combining the advances in earth observations with hydrological modelling and extensive in situ fieldwork, this research seeks to improve our understanding of surface water dynamics and associated agricultural practices in the Senegal river floodplain. 2813 mosaics from Landsat, MODIS and Sentinel-2 earth observations are created to map and monitor surface water variations using a site specific MNDWI classification adapted to complex, wetland environments. Validated against ground truth data, the approach is upscaled using cloud computing across this 2250 km 2 floodplain over 1999-2022. Statistical regression models are then developed to estimate flooded and cultivated areas based on upstream flow values since 1950 and analyse trends and exceedance probabilities over time. Results reveal extreme interannual variations in peak flooded areas, ranging from 30,000 ha and 720,000 ha between 1950 and 2022, while annual water modules fluctuate between 210 and 1460 m 3 /s. After 1994, flooded areas show partial recovery, with 95th percentile reaching 89,000 ha during 1994-2022 compared to 37,000 ha in 1972-1993. Flood-based agricultural practices cover between 13,000 ha and 133,000 ha over the same period, highlighting the pronounced variability faced by local rural communities. Occurrence maps and predictive models for annual flooded and cultivated areas based on upstream flows can support early warning tools, helping to prepare for extreme floods and droughts. These outputs are crucial to assess the impact of future climatic and anthropic changes in the region, including planned dams, on the amplitude of annual floods and their associated environmental benefits
The Genetic Evolution of DENV2 in the French Territories of the Americas: A Retrospective Study from the 2000s to the 2024 Epidemic, Including a Comparison of Amino Acid Changes with Vaccine Strains
No full textInternational audienceBackground: Dengue virus type 2 (DENV2) is endemic to hyperendemic in the French territories of the Americas (FTAs), including French Guiana, Guadeloupe, Martinique, Saint-Barthelemy, and Saint-Martin. In 2023–2024, French Guiana, Martinique, and Guadeloupe experienced unprecedented dengue epidemics partly associated with this serotype. In response, we conducted a retrospective study of the diversity of DENV2 strains circulating in the FTAs from 2000 to 2024. Methods: To this end, we selected DENV2 samples from the collection at the National Research Center for Arboviruses in French Guiana (NRCA-FG) and sequenced them using Oxford Nanopore Technologies (ONT)-based next-generation sequencing (NGS). Results: Phylogenetic analysis revealed that (i) the 77 DENV2 sequences from the FTAs belong to two distinct genotypes—Asian American and Cosmopolitan; (ii) from the 2000s up to the 2019 epidemic in French Guiana, all sequenced strains belonged to the Asian American genotype; (iii) and from 2019 to 2020, strains circulating in Martinique and Guadeloupe belonged to the Cosmopolitan genotype, specifically the Indian subcontinent sublineage, while (iv) strains from the 2023–2024 outbreak in Martinique, Guadeloupe, and French Guiana fall within a distinct sublineage of the same genotype—Other Cosmopolitan. Additionally, we analyzed amino acid (AA) changes in FTA sequences compared to the Dengvaxia® and Qdenga® vaccines. The analysis of amino acid changes in FTA sequences compared to the vaccines (Dengvaxia® and Qdenga®) identified 42 amino acid changes in the prM/E regions (15 in the prM region and 27 in the E region) relative to CYD-2 Dengvaxia® and 46 amino acid changes in the prM/E regions relative to Qdenga®, including 16 in the prM region and 30 in the E region. Some of these AA changes are shared across multiple genotypes and sublineages, with 8 substitutions in the prM region and 18 in the E region appearing in both analyses. This raises questions about the potential impact of these changes on vaccine efficacy. Conclusion: Overall, these findings provide a current overview of the genomic evolution of DENV2 in the FTA, which is crucial for developing more effective prevention and control strategies and for selecting future vaccines tailored to circulating strains
Shared goals and priorities for biodiversity monitoring for the 3rd instalment of Biodiversa+
No full textThis report presents the updated biodiversity monitoring priorities of the Biodiversa+ Partnership for the period 2025–2028. It builds on the previous instalments (2021–2023, 2023–2025), maintaining the same 12 thematic priorities and one transversal topic, now with refined descriptions to guide implementation. These priorities focus on key biodiversity components—from genes to ecosystems—across terrestrial, freshwater, and marine realms, where enhanced monitoring efforts and transnational coordination are urgently needed. The report outlines the rationale, existing initiatives, and policy relevance for each priority, offering a framework for future Biodiversa+ activities, including transnational projects, pilot actions, and national monitoring support. It also promotes the use of Essential Biodiversity Variables (EBVs) and the DPSIR framework for harmonised biodiversity assessment and reporting
Grande variabilité de la diversité microbienne du sol et de ses fonctions dans une plantation d'Eucalyptus grandis de 20 ans
No full textInternational audienceThe spatial heterogeneity in soil properties as well as in molecular and catabolic diversities of the soil microbial community were investigated by soil analyses, Illumina MiSeq sequencing and MicroResp™ profiling, respectively, in 51 plots of a 20 year-old eucalyptus plantation in south Brazil. The relationships between these parameters were assessed to test whether small scale variation in soil properties and understory vegetation generated heterogeneity in the soil microbial community. The spatial variability of soil microbial community and functioning was shown to be substantial. A greenness index, used as a proxy of the density of the understory biomass, explained very little of the soil microbial parameters. Variability in soil properties (mainly C availability, pH) partly explained shifts in molecular and catabolic parameters of the soil microbial community. Bacterial (and, to a lower extent, fungal) molecular parameters were the main factors explaining the catabolic capabilities of the soil microbial community. But overall, the sequencing data was of little use in explaining C processes in these soils, underlying the difficulty in predicting the contribution of large tree-plantations to the global C cycle
Aerosol Background Concentrations Influence Aerosol‐Cloud Interactions as Much as the Choice of Aerosol‐CloudParameterization
No full textSoumis a Geophysical Research LettersInternational audienceWe use an independent observational estimate of aerosol-cloud interactions (ACI) during the 2014 Holuhraun volcanic eruption in Iceland to evaluate 4 ACI parameterizations in a regional model. All parameterizations reproduce the observed pattern of liquid cloud droplet size reduction during the eruption, but strongly differ on its magnitude and on the resulting effective radiative forcing (ERF). Our results contradict earlier findings that this eruption could be used to constrain liquid water path (LWP) adjustments in models, except to exclude extremely high LWP adjustments of more than 20 g/m2. The modeled ERF is very sensitive to the non-volcanic background aerosol concentration: doubling the non-volcanic aerosol background weakens the ACI ERF by ˜30%. Since aerosol biases in climate models can be an order of magnitude or more, these results suggest that aerosol background concentrations could be a major and under-examined source of uncertainty for modeling ACI
Tell me what you cook and I'll tell you who you are. A study of the influence of the representations and identities of aspiring chefs on their intentions to reduce meat in favour of plant-based dishes
No full textInternational audienceFaced with increasing recommendations for a more plant-based diet, the catering sector is particularly affected. This study investigates how future chefs' representations and identities (professional or otherwise) influence their intentions to offer less meat-based and more plant-based menus, either by reducing meat in dishes or replacing meat-based dishes with vegetarian options. Theories of representations and multiple identities were chosen to study how future chefs may or may not consider to reduce the amount of meat in their menus, in relation to the literature that shows links between representations, identities, and relationship with meat. Culinary students from two French schools (n = 286) were investigated. Participants' representations of the effectiveness of pro-environmental measures in restaurants were analysed using t-tests, while the association of identities on intentions to reduce meat was examined with bivariate and multivariate regressions. The results indicate that future chefs perceive meat reduction in favour of plant-based products in the offer (dishes, menu) less favourably than other measures (e.g., favouring local sourcing, limiting waste, etc.). Furthermore, environmental, food, and cultural identities are associated to future chefs' intentions to reduce meat in favour of plant-based products. Theoretical and managerial implications are suggested, as well as perspectives for future research
Ichthyop: A Lagrangian tool for modelling ichthyoplankton dynamics
No full textIchthyop is a free Java tool designed to study the effects of physical and biological factors on ichthyoplankton dynamics. It incorporates the most important processes involved in fish early life: spawning, movement, growth, mortality and recruitment. The tool uses as input time series of velocity, temperature and salinity fields archived from ROMS, MARS, NEMO or SYMPHONIE oceanic models (either files or OpenDAP)
Computational and experimental insights into single-atom catalysts supported on g-C<sub>3</sub>N<sub>4</sub>: Unraveling the superior stability and catalytic activity of Rh in hydroformylation reactions
No full textInternational audienceSingle-atom catalysts (SACs) have emerged as a promising class of materials, leveraging the benefits of both homogeneous and heterogeneous catalysis to enhance efficiency and selectivity. In this work we have investigated the catalytic performance of SACs supported on graphitic carbon nitride (g-C3N4) for hydroformylation reactions. A systematic evaluation of nine transition metal SACs (Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt) anchored on g-C3N4 was conducted using a combination of Density Functional Theory (DFT) calculations and experimental validation. Computational results indicate that at higher metal loadings, most metal atoms tend to migrate into the interlayers of g-C3N4, reducing their accessibility to reactant species and limiting their involvement in the catalytic process. However, Ru, Os, Ir, and Co single atoms remain stabilized on the heptazine rings, residing on the outermost layer and preserving active sites, albeit with lower predicted catalytic activity compared to Rh, while Fe, Ni, Pd, and Pt preferentially localize within the interlayers. Ru, Rh, and Co SACs anchored on g-C3N4 were experimentally synthesized and characterized using Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), along with catalytic testing, confirming the single-atom nature of the catalysts and corroborating the theoretical findings
Scientific response to the 2021–2022 seismic swarm in the Monts Dore volcanic province (France): dynamic insights from temporal surveys (2/2)
No full textInternational audienceDuring years 2021-2022, an unusual seismic swarm was recorded at crustal level beneath the Monts Dore volcanic province (France). Complementary field and remote measurements were performed. Together with the time series recorded on the seismological and GNSS national networks, these measurements were fundamental for monitoring the evolution of the seismic swarm and deciphering its origin. Although a potential vertical migration of the seismic events is suggested, the complementary measurements presumably discard the hypothesis of magma intrusion at shallow crustal level. The ascent of a CO2-rich fluid originating from the mantle might instead have reacted with the hydrothermal system beneath the Monts-Dore since at least the summer 2021 leading to the reactivation of pre-existing tectonic structures with known associated seismicity. Feedback on the management of the 2021-2022 seismic swarm prompts for several recommendations that should be considered in future to better face and address at the national level the issues raised at long-dormant volcanic provinces in mainland France
Les dendrimères : exemples de leurs propriétés biologiques
No full textArticle publié sur le site CultureSciences-Chimie (https://culturesciences.chimie.ens.fr/a-propos). CultureSciences-Chimie a été créé dans le cadre de la diffusion des savoirs et de la convention signée entre la direction générale de l'enseignement scolaire (DGESCO) du Ministère de l'Éducation Nationale et les Écoles Normales Supérieures. Il a pour vocation d'offrir aux enseignants du secondaire et du supérieur des ressources leur permettant d'assurer une auto-formation initiale et continue et de préparer leurs enseignements.Les dendrimères, aussi appelés arbres moléculaires à cause de leur structure qui ressemble à la ramure des arbres, sont des macromolécules hyper-ramifiées tri-dimensionnelles. N'existant pas dans la nature, elles proviennent uniquement de la synthèse. Cet article présente les voies de synthèse de quelques dendrimères et leurs applications en médecine, notamment en nanomédecine (puces de diagnostic)