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Tunable synthesis of C-SiOxCy monoliths
No full textInternational audienceThis study establishes key structure–property relationships, offering valuable guidelines for designing porous monolithic C-SiOxCy materials for energy storage sensors, and electrocatalysis. We report a tunable sol-gel synthesis of monolithic C-SiOxCy composites with tailored physicochemical and electrical properties. By combining resorcinol, formaldehyde, TEOS, APTES, and kapok fibers, twenty-one formulations were prepared while systematically varying five synthesis parameters: TEOS-to-resorcinol molar ratio, sol concentration, sol pH, drying method, and pyrolysis temperature. The resulting composites exhibited silica contents ranging from 19 to 80 wt%, bulk densities from 0.10 to 1.11 g/cm³, specific surface areas up to 562 m²/g, and electrical conductivities reaching 8 S/cm. Structural analyses (SEM, ²⁹Si NMR, N2 adsorption) revealed that the materials consist of integrated hybrid networks rather than separate carbon and silica domains. Factor analyses highlighted the dominant roles of TEOS/R on composition and porosity, supercritical drying on texture, and pyrolysis temperature on conductivity. Acidic conditions and sol dilution promoted high surface areas and pore volumes, while alkaline pH and carbon-rich environments enhanced electrical transport
Observation of production in collisions at = 13 TeV with the ATLAS detector and constraints on anomalous quartic gauge-boson couplings
No full textInternational audienceThis Letter reports the observation of triboson production in 140 fb of data collected by the ATLAS detector from proton-proton collisions at a centre-of-mass energy of = 13 TeV at the LHC. Events with an opposite-charge pair, a high transverse-momentum photon, and significant missing transverse momentum are considered. The observed (expected) significance of the signal is 5.9 (6.0) standard deviations. The measured fiducial cross-section, defined for the final state is 6.2 0.8 (stat.) 0.6 (sys.) fb, in good agreement with the Standard Model prediction of 6.1 fb. Constraints on the Wilson coefficients of 13 dimension-8 operators describing physics beyond the Standard Model through anomalous quartic gauge-boson couplings are derived using the effective field theory framework
X-ray emission in IllustrisTNG circum-cluster environments. II -- Possible origins of the soft X-ray excess emission
No full textInternational audienceAn excess of soft X-ray emission (0.2-1 keV) above the contribution from the hot intra-cluster medium (ICM) has been detected in a number of galaxy clusters, including the Coma cluster. The physical origin of this emitting medium above hot ICM has not yet been determined, especially whether it be thermal or non-thermal. We aim to investigate which gas phase and gas structure more accurately reproduce the soft excess radiation from the cluster core to the outskirts, using simulations. By using the simulation TNG300, we predict the radial profile of thermodynamic properties and the Soft-X-ray surface brightness of 138 clusters within 5 . Their X-ray emission is simulated for the hot ICM gas phase, the entire Warm-Hot medium, the diffuse and low-density Warm-Hot Intergalactic Medium (WHIM). Inside clusters, the soft excess appears to be produced by substructures of the WARM gas phase which host dense warm clumps (i.e, the Warm Circum-Galactic Medium, WCGM), and in fact the inner soft excess is strongly correlated with substructure and WCGM mass fractions. Outside of the virial radius, the fraction of WHIM gas that is mostly inside filaments connected to clusters boosts the soft X-ray excess. The more diffuse the gas is, the higher the soft X-ray excess beyond the virial region. The thermal emission of WARM gas phase, in the form of WCGM clumps and WHIM diffuse filaments, reproduces well the soft excess emission that was observed up to the virial radius in Coma and in the inner regions of other massive clusters. Moreover, our analysis suggests that soft X-ray excess is a proxy of cluster dynamical state, with larger excess being observed in the most unrelaxed clusters
Mitigating Model Misspecification in Simulation-Based Inference for Galaxy Clustering
No full textInternational audienceSimulation-based inference (SBI) has become an important tool in cosmology for extracting additional information from observational data using simulations. However, all cosmological simulations are approximations of the actual universe, and SBI methods can be sensitive to model misspecification - particularly when the observational data lie outside the support of the training distribution. We present a method to improve the robustness of cosmological analyses under such conditions. Our approach first identifies and discards components of the summary statistics that exhibit inconsistency across related simulators, then learns a transformation that brings the observation back within the support of the training distribution. We apply our method in the context of a recent SimBIG SBI galaxy clustering analysis using the wavelet scattering transform (WST) summary statistic. The original analysis struggled to produce robust constraints for certain subsets of WST coefficients, where the observational data appeared out-of-distribution (OOD) relative to the training data. We show that our method enables robust cosmological inference and resolves OOD issues, while preserving most of the constraining power. In particular, the improved SimBIG WST analysis yields CDM constraints of and , which are respectively and tighter than those from a standard perturbation-theory-based power spectrum analysis, confirming the significant information gain of WST summary statistics. The proposed method is easily applicable to other cosmological SBI contexts and represents a step toward more robust SBI pipelines
La part du dissensus. Réflexion à quatre voix sur la littérature relationnelle
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Biodiversity co-variation patterns in a range of soil organism taxa across highly contrasting ecosystems
No full textInternational audienceSoil biodiversity as a critical component of terrestrial ecosystems and their functioning varies across spatial scales and environmental conditions. However, it remains unclear whether and how biodiversity patterns co-vary among different soil taxa across ecosystems.In this study, we compared diversity patterns of plants, earthworms, nematodes, bacteria, and fungi, as five major groups of soil organisms, across six strongly contrasting ecosystems ranging from mountain peatland to crop fields, including within-ecosystem variation in soil moisture. We hypothesized co-variation in taxonomic richness (alpha diversity) and composition (beta diversity) of multiple groups of soil organisms across ecosystems, moisture conditions and spatial scales.In partial contrast to our initial hypothesis, co-variation in the taxonomic richness among these groups was limited, though significant positive associations were found among bacteria, fungi, and earthworms across all sites. Plant diversity showed distinct associations with soil organism diversity, particularly with earthworms and bacteria, highlighting above-belowground biodiversity linkages. Beta diversity showed substantial co-variation among all soil organism groups, reflecting a spatial coupling of their communities that was influenced by differences in soil moisture conditions. These patterns were more pronounced in near-natural and no-till agroecosystems compared to conventional agricultural systems. Our results highlight that ecosystem type shapes broad-scale taxonomic richness, while local soil moisture critically influences soil biodiversity and spatial community composition, emphasizing the multi-scale drivers of soil biodiversity.</div
Le retour d'expérience, une contribution à la pédagogie frugale ?
No full textInternational audienceDebriefing sessions (After-Action Review) are working meetings that bring a team together to review a recent, significant experience in order to develop a shared understanding of that experience and learn lessons from it that will improve future collective actions in similar situations. This discipline, initially developed in the military to address significant capacity development challenges, has gradually spread to businesses through several channels and in various formats. Given its proven effectiveness and simplicity of implementation, the question arises as to whether this practice of learning from experience should be extended to management training in order to combine pedagogical effectiveness, frugality of means, and training in metacognition to develop independent thinking, critical thinking, and systemic thinking among students or participants.Le retour d'expérience à chaud est une réunion de travail qui rassemble une équipe dans la perspective de revisiter une expérience récente, et à enjeu, pour faire émerger une compréhension partagée de cette expérience et en tirer des leçons afin d'améliorer des actions collectives futures, dans des situations de nature semblable. Cette discipline, développée initialement dans le monde militaire pour répondre à des enjeux de développement de capacités importants, s'est progressivement répandue dans les entreprises par le biais de plusieurs canaux et dans des formats variés. Au regard de son efficacité avérée et de sa simplicité de mise en œuvre, la question se pose d'élargir cette pratique d'apprentissage de l'expérience aux formations en gestion pour combiner efficacité pédagogique, frugalité des moyens, et entrainement à la méta-cognition au service du développement de l'autonomie de pensée, de l'esprit critique et de la pensée systémique chez les élèves ou participants.</div
Tree water status behavior of two common European urban species using dendrometric measurements and remote sensing imagery.
No full textInternational audienceWith growing urban populations and rising heatwaves, urban trees are increasingly valued for their cooling benefits through transpiration and shading. However, water stress can limit transpiration, and the effects of urban environment and species-specific traits on tree water status remain understudied. This work investigates how meteorology, soil imperviousness and species influence tree water status behavior, and how vegetation indices derived from remote sensing relate to tree water status, at both seasonal and individual tree scales. Eleven mature Acer platanoides and Tilia x euchlora trees (two common European urban species) growing under varying soil imperviousness levels in a medium-sized French city were monitored. For summer 2023 and spring 2024, two dendrometric indicators of water status - maximum daily shrinkage (MDS) and tree water deficit (TWD) - were calculated, and vegetation index NDVI was extracted from SuperDove imagery. Results show that TWD, more than MDS, effectively assessed tree water status and was closely linked to vapor pressure deficit and relative humidity. Higher soil imperviousness increased water deficit in both seasons, particularly for trees in pits. Acer platanoides exhibited a more isohydric strategy than Tilia x euchlora. NDVI was strongly correlated with TWD in summer 2023 (R² = -0.43), and with MDS in spring 2024 (R² = 0.40). These findings underline the value of dendrometric measurements in urban environments for understanding tree water status, and highlight the potential of very high spatio-temporal resolution satellite data to assess individual tree water status across cities, supporting improved management to maximize the cooling benefits of urban trees
Early warfare in ancient Egypt, from the Predynastic to the First Intermediate Period (ca. 3500-2050 BC)
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Citizen science contributions to soil biodiversity research and conservation: insights from European studies
No full textInternational audienceCitizen science (CS) has emerged as a valuable approach for bridging knowledge gaps in biodiversity studies by expanding spatial and temporal coverage, yet remains underused in soil biodiversity monitoring. We conducted the first Europe-wide synthesis of CS initiatives dedicated to soil biodiversity, systematically reviewing published and unpublished projects to assess their contributions and limitations. A total of 126 papers and projects were analyzed across 36 countries, with Western European countries leading in study volume. National-scale studies dominated, with urban areas being the most studied land use type. Taxonomic coverage was broad but uneven, dominated by soil macrofauna (ants, gastropods and earthworms) and fungi. Methodologies ranged from opportunistic sampling to structured surveys, reflecting diverse scientific objectives and producing data of variable quality. Citizens contributed substantially to species identification, although verification practices varied widely, from expert validation to self-reported identifications without verification. Overall, our synthesis reveals a fragmented but dynamic CS landscape that, while providing valuable contributions, remains far from realizing its full scientific potential. Strengthening the role of CS in soil biodiversity research will require greater emphasis on taxonomic accuracy, with error rates systematically assessed. Emerging image-based identification tools, including community-based identification features and automated species recognition, offer promising avenues to enhance both taxonomic accuracy and participant engagement. Equally important is fostering inclusive participation to broaden spatial coverage and co-develop conservation-relevant indicators with stakeholders. Finally, dataset interoperability and metadata standardization are essential to integrate heterogeneous initiatives and unlock the full potential of CS for researchers and soil biodiversity monitoring frameworks