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Author Correction: Late Paleolithic whale bone tools reveal human and whale ecology in the Bay of Biscay
No full textCorrection to: Nature Communications https://doi.org/10.1038/s41467-025-59486-8, published online 27 May 2025International audienceIn the version of the article initially published, due to a version error, the image shown in Fig. 2 did not include an inset map shown in the “16-14.5 ka cal BP” panel indicating region 22, as is now updated in the HTML and PDF versions of the article
High-temperature flow behavior and associated microstructural evolution of 316Nb austenitic stainless steel - transition between discontinuous and continuous dynamic recrystallization
No full textInternational audienceHot torsion tests up to high amounts of strain ( = 8), followed by microstructural observations were performed on 316Nb austenitic stainless steel to investigate its dynamic recrystallization (DRX) behavior. The test temperature varied from 950 °C to 1150 °C and the strain rate varied from 5×10 -3 s -1 to 5×10 -1 s -1 . The resulting Zener-Hollomon values ( ≈ 4. 10 -2. 10 s -1 ) encompassed a large range of industrial forging conditions. The effect of niobium in solid solution was investigated thanks to two heat treatments prior to testing, which modified the initial amount of Nb atoms in solid solution. In contrast to post-dynamic and static recrystallization, this parameter did not significantly affect the DRX behavior. The dominant phenomenon was continuous DRX, which is unusual for an austenitic stainless steel at such elevated temperatures. Discontinuous DRX was also observed for temperatures higher than 950°C, increasing when the deformation temperature increased, but appeared very sluggish. The peak and steady state stress and strain values, as well as the Derby exponent were in accordance with a combination of continuous and discontinuous DRX over the broad range of investigated deformation conditions. This recrystallization behavior was probably linked to the roles of molybdenum and niobium on the stacking fault energy and on the mobility of grain boundaries
Solar fuels generators: integration at different levels and scales
No full textInvited keynote lectureInternational audienc
Status and perspectives of the FUSION INFN project for the study and optimization of the nuclear fusion reaction for Inertial Confinement applications
No full textInternational audienceThe FUSION project (an acronym for FUsion StudIes of prOton boron Neutron-less reaction in laser-generated plasma) was launched in 2022 by researchers from INFN (Istituto Nazionale di Fisica Nucleare) and ENEA. This project marks the first scientific initiative funded by INFN in the field of Inertial Confinement Fusion (ICF). The main objectives of FUSION are to develop a new generation of solid targets designed to enhance the fusion reaction rate, being this reaction a potential candidate for future ICF schemes. FUSION will also focus on designing novel diagnostic techniques for measuring reaction products and, ultimately, estimating alpha and proton cross-sections in a plasma environment. The project will be carried out through two experimental campaigns at a laser facility equipped with a high-energy, long-pulse (picosecond) laser. In the proposed experimental setup, the reaction will be triggered simultaneously ‘in target’ by the protons generated in the laser matter interaction and 11B present in the same expanding plasma and in the ‘pitcher-catcher’ configuration. In FUSION, a set of measurements will also be dedicated to a first estimation of the proton and alpha-stopping power in a plasma. FUSION will enable a comprehensive understanding of the reactions and will help in optimize the conditions for future applications in inertial nuclear fusion with the reaction.</jats:p
Réseaux de Bragg en nitrure de silicium et amplificateurs optiques en réflexion GaAs pour la réalisation de lasers hybrides à cavité étendue autour de 965nm
No full textInternational audienceNous présentons une nouvelle plateforme de laser hybride émettant autour de 965nm. Cette cavité est composée d’un réflecteur de Bragg en nitrure de silicium et un amplificateur optique à semi-conducteurs en réflexion en GaAs
Three-point functions in critical loop models
No full textInternational audienceIn two-dimensional models of critical non-intersecting loops, there are -leg fields that insert open loop segments and can have nonzero conformal spins, and diagonal fields that change the weights of closed loops. We conjecture an exact formula for 3-point functions of such fields on the sphere. In the cases of diagonal or spinless 2-leg fields, the conjecture agrees with known results from Conformal Loop Ensembles. We numerically compute 3-point functions in loop models on cylindrical lattices, using transfer matrix techniques. The results agree with the conjecture in almost all cases. We attribute the few discrepancies to difficulties that can arise in our lattice computation when the relevant modules of the unoriented Jones-Temperley-Lieb algebra have degenerate ground states
Brain connectivity: complex, not chaotic
No full textInternational audienceThe term “connections” is a commonly used and convenient shorthand for describing the complex organization of the brain, but it can easily lead to an overemphasis on pairwise or point-to-point, source-target network connectivity. Anatomical studies make clear that there are other important features to consider such as divergence and collateralization (axons or bundles branching to multiple targets), convergence (multiple bundles from different sources converging on the same target), and scrambled topography along a trajectory. This short “Did You Know” communication elaborates on several of these features from the anatomical perspective, while inviting continued dialogue with the tractography community in addressing the shared goals of better understanding brain organization
Salinisation de l'estuaire de la Casamance : modélisation des processus physiques
No full textThe estuary of the Casamance River, located in southern Senegal, is a zone of intense economic activity but remains poorly documented. After a period of active research in the 1980s, studies have become scarce, leading to a lack of data to establish a baseline and monitor its evolution. This estuary experiences significant salinity fluctuations: during the dry season (November-June), it becomes "inverse," with salinity increasing upstream, ranging from 20 psu during the rainy season to 50 psu in the dry season. The primary objective of this thesis is to study salinity fluctuations using a hydrodynamic model (CROCO) and in situ data. The first part of the study focused on tides. To calibrate the model, observed and simulated tidal water levels and currents are compared. The simulated water levels align well with the observations, but tidal currents remain underestimatedby 50%. The residual Lagrangian circulation, primarily directed upstream, is significantly lower than the downstream Eulerian residual circulation. These first results highlight the need for longer time series of current and bathymetric data to refine the model. The second part focuses on salinity fluctuations. Longitudinal profiles near the river mouth show strong longitudinal gradients, weak vertical stratification and significant seasonal variability. Two model configurations (CASAM1 and CASAM200, at 1 km and 200 m horizontal resolution, respectively) are forced by ERA5 reanalysis and GloFAS hydrological discharge. During the rainy season, the salinity decrease is influenced by the discharge and salinity values imposed upstream. CASAM1 simulates notable interannual variability: in the dry season, maximum salinity depends on cumulative evaporation and the previous year's minimum salinity. While CASAM200 provides more realistic hydrodynamics, an underestimation of the salinity increases during the dry season persists. A vertically-integrated salinity budget analysis reveals that salinity increases are primarily driven by evaporation and horizontal advection, compensated by horizontal mixing. This thesis provides a first step in the hydrodynamic modelling of the Casamance and draws perspectives to improve simulations. Extending the model upstream, collecting bathymetric data, and using hydrological models better suited to the region are essential. Multi-year monitoring based on in situ observations is also recommended to strengthen basic knowledge and better evaluate the models.L'estuaire du fleuve Casamance, au sud du Sénégal, est une zone d'intense activité économique mais son fonctionnement hydrodynamique demeure peu documenté. Depuis une période de recherche active dans les années 80, les études sont rares, entraînant un manque de données pour établir une base de référence de l'estuaire et suivre son évolution. Cet estuaire connaît d'importantes fluctuations de salinité : durant la saison sèche (novembre-juin), il s'inverse et sa salinité croit vers l'amont, atteignant 50 psu en saison sèche puis 20 psu en saison humide (juillet-septembre). L'objectif de cette thèse est d'étudier les fluctuations de salinité à l'aide d'un modèle hydrodynamique (CROCO) et de données in situ. La première partie de la thèse a pour objet l'étude de la marée dans l'estuaire. Afin de calibrer la friction du modèle, les hauteurs d'eau et les courants de marée simulés et observés sont comparés. Malgré un bon accord des hauteurs d'eau, les courants de marée simulés sont sous-estimés de 50 %. La circulation résiduelle Lagrangienne, principalement orientée vers l'amont, est beaucoup plus lente que la circulation résiduelle eulérienne orientée vers l'aval. Ces premiers résultats illustrent le besoin d'acquérir des séries temporelles de courant plus longues et des données bathymétriques dans la partie est de l'estuaire pour améliorer le modèle. La seconde partie se concentre sur les fluctuations de salinité. Des radiales longitudinales réalisées près de l'embouchure indiquent de forts gradients longitudinaux, une faible stratification verticale et une forte variabilité saisonnière. Deux configurations du modèle (CASAM1et CASAM200, respectivement 1 km et 200 m de résolution horizontale) sont forcées par la réanalyse ERA5 et le débit d'eau douce GloFAS. Pendant la saison des pluies, la baisse de salinité est influencée par le débit et la salinité de l'eau saumâtre imposés en amont. CASAM1 simule une forte variabilité inter-annuelle : en fin de saison sèche, le maximum de salinité dépend du cumul d'évaporation et du minimum de salinité de l'année précédente. CASAM200, malgré une hydrodynamique plus réaliste, sous-estime l'augmentation de salinité en saison sèche. L'analyse du bilan de salinité intégré sur la verticale révèle que l’augmentation en saison sèche est principalement causée par l'évaporation et l'advection, et compensée par le mélange horizontal. Cette thèse marque une première avancée dans la modélisation hydrodynamique de l'estuaire de Casamance. Elle propose des pistes d'amélioration comme l'extension du domaine modélisé vers l'amont et l'usage de modèles hydrologiques mieux adaptés à la région. Une collecte pluriannuel d'observations in situ permettra également de consolider les connaissances et de mieux valider le modèle
Experimental Investigation and Behavioral Modeling of the Ron vs. Gate Overshoots Relationship in Schottky p-GaN HEMTs
No full textInternational audienceThe semi-floating p-GaN layer of commercial schottky HEMTs is suspected to be related to instabilities of the device's electrical characteristics. Particularly, we recently explained how gate voltage spikes at turn-on can cause a drastic, lasting and reproducible dynamic Ron increase. The proposed explanation only partly matched the dynamics of the observed Ron fluctuations and only one device reference was tested. In this work, higher voltage spikes are explored and a device from an other manufacturer is also studied. We demonstrate with a ngspice simulation how all observed dynamic Ron behaviors can be explained with a two-diode model of the gate stack
Aluminum-Based Superconducting Tunnel Junction Sensors for Nuclear Recoil Spectroscopy
No full textInternational audienceThe BeEST experiment is searching for sub-MeV sterile neutrinos by measuring nuclear recoil energies from the decay of Be implanted into superconducting tunnel junction (STJ) sensors. The recoil spectra are affected by interactions between the radioactive implants and the sensor materials. We are therefore developing aluminum-based STJs (Al-STJs) as an alternative to existing tantalum devices (Ta-STJs) to investigate how to separate material effects in the recoil spectrum from potential signatures of physics beyond the Standard Model. Three iterations of Al-STJs were fabricated. The first had electrode thicknesses similar to existing Ta-STJs. They had low responsivity and reduced resolution, but were used successfully to measure Be nuclear recoil spectra. The second iteration had STJs suspended on thin SiN membranes by backside etching. These devices had low leakage current, but also low yield. The final iteration was not backside etched, and the Al-STJs had thinner electrodes and thinner tunnel barriers to increase signal amplitudes. These devices achieved 2.96 eV FWHM energy resolution at 50 eV using a pulsed 355 nm (~3.5 eV) laser. These results establish Al-STJs as viable detectors for systematic material studies in the BeEST experiment