Shocks, Winds, and a Torus: the Large Binocular Telescope Interferometer (LBTI) Resolves the Active Nucleus of NGC 4151

International audienceAbstract We present mid-infrared (MIR) observations of the Seyfert 1 galaxy NGC 4151 using the Large Binocular Telescope Interferometer (LBTI). We took open-loop Fizeau images with 66–104 mas (5.8–9.1 pc) resolution in the N -band (at 8.7 and 10.5 μ m), using the full resolution of the LBTI—equivalent to that of a 28.8 m telescope. These images were complemented by adaptive optics imaging in the LM -bands (3.7 and 4.8 μ m), with 50–62 mas (4.4–5.4 pc) resolution. These images bridge the scales between previous Very Large Telescope Interferometer (VLTI)/MIDI and VLT/VISIR data, delivering Extremely Large Telescope (ELT)–like imaging resolution in the N -band. We resolve a dusty torus (with a diameter of 32 pc and position angle of 125°), and detect dusty clouds within the narrow-line region. Matching the resolution across four bands, we measured spatially resolved SEDs of the central ∼100 pc. Modified blackbody fitting revealed dust temperature and extinction profiles, indicating both heating from the accretion disk and additional shock heating due to the radio jet. The spatial coincidence of ionized emission (e.g., [Fe II ] and [O III ]), extended MIR structures, and radio features further supports the interpretation of shock heating. Comparison with NGC 1068 tests the Unified Model of Active Galactic Nuclei: structures are similar, despite differences in orientation and Eddington ratio. NGC 4151’s torus is smaller than NGC 1068’s following a r ∝ L 0.5 scaling. These ELT-like observations of NGC 4151 and NGC 1068 highlight the need to revise MIR radiative transfer models of AGN to account for jet-related heating

A Unified Convergence Analysis for Semi-Decentralized Learning: Sampled-to-Sampled vs. Sampled-to-All Communication

International audienceIn semi-decentralized federated learning, devices primarily rely on device-to-device communication but occasionally interact with a central server. Periodically, a sampled subset of devices uploads their local models to the server, which computes an aggregate model. The server can then either (i) share this aggregate model only with the sampled clients (sampled-to-sampled, S2S) or (ii) broadcast it to all clients (sampled-to-all, S2A). Despite their practical significance, a rigorous theoretical and empirical comparison of these two strategies remains absent. We address this gap by analyzing S2S and S2A within a unified convergence framework that accounts for key system parameters: sampling rate, server aggregation frequency, and network connectivity. Our results, both analytical and experimental, reveal distinct regimes where one strategy outperforms the other, depending primarily on the degree of data heterogeneity across devices. These insights lead to concrete design guidelines for practical semi-decentralized FL deployments

Euclid Quick Data Release (Q1): Euclid spectroscopy of QSOs. 1. Identification and redshift determination of 3500 bright QSOs

International audienceThe slitless spectroscopy mode of the NISP onboard Euclid has enabled efficient spectroscopy of objects within a large FoV. We present a large and homogeneous sample of bright quasars identified from the Euclid Quick Data Release (Q1) by combining high-purity candidate selections from Gaia and WISE with the NISP spectra. Through visual inspection of the Euclid spectra of these quasar candidates, we identify approximately 3500 quasars with reliable redshifts at $0<z\lesssim 4.8$. We generate the first Euclid composite spectrum of quasars covering rest-frame NUV to NIR wavelengths without telluric lines, which will be pivotal to NIR quasar spectral analysis. We obtain an empirical spectroscopic depth of $J_{\rm E}\lesssim 21.5$ and $H_{\rm E}\lesssim 21.3$ at the sensitivity of the Wide Field Survey, beyond which the number of securely identified quasars declines sharply. We analyse VIS morphologies using Sersic and CAS metrics, and a deep-learning PSF fraction to track nuclear dominance. At low redshift ($z<0.5$), obvious host structures are common and a single Sersic model fits about half of the sources; at intermediate redshift ($0.5<z<2$), the nuclear component dominates, with 90% of the Sersic fits saturating at the upper index limit. In this intermediate redshift regime, $f_{\rm PSF}$ is available, and we use it as a more reliable compactness measure than the single-Sersic and CAS parameters to quantify nuclear versus host emission. We also explore the novel Euclid NIR colour space and discuss the role of these quasars in refining AGN selection techniques for future Euclid data releases. Our results highlight the potential of Euclid spectroscopy to advance quasar surveys and enable the construction of more complete AGN catalogues. The spectroscopic bright quasar catalogue of this work, and the composite quasar spectrum, will be available at https://cdsarc.cds.unistra.fr/. (abridged

Constraints on gravitational waves from the 2024 Vela pulsar glitch

International audienceAmong known neutron stars, the Vela pulsar is one of the best targets for gravitational-wave searches. It is also one of the most prolific in terms of glitches, sudden frequency changes in a pulsar's rotation. Such glitches could cause a variety of transient gravitational-wave signals. Here we search for signals associated with a Vela glitch on 29 April 2024 in data of the two LIGO detectors from the fourth LIGO--Virgo--KAGRA observing run. We search both for seconds-scale burst-like emission, primarily from fundamental (f-)mode oscillations, and for longer quasi-monochromatic transients up to four months in duration, primarily from quasi-static quadrupolar deformations. We find no significant detection candidates, but for the first time we set direct observational upper limits on gravitational strain amplitude that are stricter than what can be indirectly inferred from the overall glitch energy scale. We discuss the short- and long-duration observational constraints in the context of specific emission models. These results demonstrate the potential of gravitational-wave probes of glitching pulsars as detector sensitivity continues to improve

La mobilité durant la vie et les fonctionnements sociaux des premiers agropasteurs du Néolithique à partir des isotopes de l’oxygène et du strontium

International audienceLe développement d’études pluridisciplinaires croisant données biochimiques et génétiques a démontré que les fonctionnements de certains groupes néolithiques étaient fortement liés au sexe des individus au travers de mobilités spécifiques pour les femmes, de patrilinéarités dans les recrutements des ensembles funéraires et de possibles fonctionnements patrilocaux. Dans la continuité de ces travaux, le projet WomenSOFar (ANR-21-CE03-0008) explore les différences liées au sexe et aux moments de la vie dans les organisations sociales des premiers groupes d’agropasteurs d’Europe de l’Ouest et d’Afrique du Nord.En nous appuyant sur un corpus de 155 échantillonnages réalisés sur l’émail de molaires, nous avons étudié les variations dans les signaux isotopiques (87Sr/86Sr, δ18O) au cours de la période de formation des couronnes dentaires de 74 individus datés du Néolithique moyen (4500-3300 BCE) provenant du Bassin Parisien, du Massif Central, de la Vallée du Rhône et de la Côte Méditerranéenne. Nous avons comparé ces variations à des référentiels publiés et inédits sur les isotopes biodisponibles localement. Nous avons employé des modélisations statistiques pour caractériser les mobilités au cours de la vie et les différences dans les histoires de vie entre les femmes et les hommes.Les résultats montrent une importante variation des rapports isotopiques principalement pour des sujets féminins, et de façon plus prononcée sur la côte méditerranéenne. Des changements d’environnement peuvent avoir lieu durant l’enfance et l’adolescence, soulignant l’importance de la relation entre âge et statut social. L’emploi de mesures multiples par individus montre des trajectoires individuelles variées : certains individus se déplacent vers de nouveaux environnements, d’autres semblent quitter puis revenir dans les environnements de leur enfance. Ces données mettent en évidence l’importance des histoires individuelles ainsi que des identités biologiques et sociales dans les fonctionnements des groupes étudiés

Ubiquitous Small-scale Dynamics in the Slow Solar Wind Formation Region Observed by Proba-3/ASPIICS

International audienceThe origin of the slow solar wind remains a subject of ongoing debate. Several mechanisms have been proposed: the large expansion factor of open magnetic field in the corona, interchange reconnection between open and closed field lines in streamers and pseudostreamers, reconnection within the web of separatrices (S-web), and the field line pinch-off at streamer cusps. Many of these mechanisms involve the release of small-scale density inhomogeneities into the solar wind. A significant obstacle to understanding these processes is the difficulty of observing the region between the lower corona (traditionally observed with extreme ultraviolet imagers) and the high corona (traditionally observed with externally occulted coronagraphs), where these small-scale structures are thought to originate. Here, we present for the first time high-cadence (30 s) and high-spatial-resolution (5 . ″ 6) white-light observations of the solar corona in the range of the radial distances r of 1.1 R ⊙ &lt; r &lt; 3 R ⊙ taken by the ASPIICS coronagraph on board the formation-flying Proba-3 mission. The ASPIICS data reveal ubiquitous, weak (0.5%–2% of the background brightness), small-scale dynamic features (blobs, outflows, inflows, jets, and waves). Their speeds range from 14 km s −1 to 520 km s −1, with outflowing structures generally propagating faster than the inflowing ones. All these features appear to originate from streamers and pseudostreamers. ASPIICS observations provide important constraints on the role of small-scale dynamics in the formation of the slow solar wind

Predictive factors of effectiveness of occipital nerve stimulation for chronic cluster headache: data from for the French ONS registry

International audienceEffectiveness of Occipital Nerve Stimulation (ONS) in refractory chronic cluster headache (rCCH) is supported by series of cases and a unique controlled trial, and its risk/benefit ratio has been questioned. Our objective was to identify predictive factors of ONS effectiveness in rCCH patients, to optimize this risk/benefit ratio and better select eligible patients. We analyzed 125 patients (43 women, mean age 46,4) included prospectively in the “French ONS registry”, suffering from rCCH, treated by ONS for more than one year, and with data concerning putative preoperative predictive factors of effectiveness, including demographic, CCH characteristics and severity, treatment use and co-morbidities. We studied factors associated with ONS response, defined as a ≥ 50% reduction of weekly attack frequency (WAF) between baseline and one year follow-up. Factors predictor of good response to ONS were high preoperative WAF (p = 0.0003), high number of days with attack treatment use (p = 0.0006) and absence of epilepsy (p = 0.019). The best cut-off to predict ONS effectiveness was a WAF of 14 attacks/w. ONS response&#39;s rates were 77.0% and 37.3% in patients with WAF ≥ 14/w and WAF < 14/w, respectively. However, in both groups, quality of life was significantly improved after ONS (p < 0.001). Preoperative WAF was the main predictive factors of ONS response in rCCH, with a cut-off of 14 attacks/w, which may help to select patients and increase the ONS risk/benefit ratio. However, this threshold should be used with caution, as patients with WAF < 14/w also benefited from ONS. The study has been registered (clinicaltrials.gov identifier NCT01842763)

Tarsal lipids regulate xenobiotic penetration in Drosophila melanogaster

International audienceInsects touch their proximal environment with their tarsi. The immediate contact with xenobiotics occurs with the tarsal cuticle surface that is covered with cuticular hydrocarbons (CHCs). In this work, we tested the hypothesis that xenobiotics entry through the tarsi depended on CHC amounts and composition. Applying RNA interference, we suppressed the expression of genes coding for the key enzymes of CHC production Cyp4G1 (total CHC), desat1 (unsaturated CHCs) and FASN2 (branched CHCs) in lipid producing oenocytes and analyzed the penetration efficiency of the insecticides DDT and chlorantraniliprole and of the inert dye Eosin Y in the respective flies. As expected, in walking experiments, reduction of CHC amounts (cyp4G1RNAi) enhanced insecticide and dye penetration into the tarsi. In the same assay, we identified unsaturated CHCs as the main CHC component attenuating DDT and chlorantraniliprole at low concentrations. Likewise, tarsal adhesion and uptake of Eosin Y depended rather on unsaturated than on branched CHCs. Extrapolating from our data, we propose a two‐step model of xenobiotics penetration through the tarsal cuticle: first, modulated by unsaturated CHCs, the molecule is repelled or adheres to the cuticle surface; upon adhesion, the molecule penetrates the cuticle and accumulates in the tarsal lumen in a second step. Whether these mechanisms apply to molecules other than Eosin Y remains to be investigated. Taken together, the tarsal cuticle constitutes a selective bipartite barrier against uncontrolled uptake of contact xenobiotics

Couette Taylor instabilities in the small-gap regime

The Couette-Taylor instability occurs in a viscous fluid confined between two coaxial rotating cylinders. When the Taylor number surpasses a critical value, the stable Couette flow destabilizes, giving way to steady Taylor vortices. As the Taylor number increases further, these vortices themselves become unstable, transitioning into wavy Taylor vortices.In this article, we focus on the small-gap limit, where the ratio of the cylinder radii approaches unity and the rotation rates of the cylinders are nearly identical. We provide a rigorous proof of the existence of a critical Taylor number T c , at which the Couette flow loses stability.For Taylor numbers just above T c -under fixed axial periodicity-the solutions to the limiting Navier-Stokes system are governed by a Ginzburg-Landautype partial differential equation. Beyond the classical Taylor vortex flow, we demonstrate that a two-parameter family of solutions emerges at criticality for T &gt; T c . This family includes not only wavy vortices but also a variety of other exotic flow patterns, all of which remain steady in the frame rotating at the average angular velocity of the cylinders.</div

État des lieux des connaissances des médecins généralistes concernant les principales atteintes locomotrices rencontrées chez le coureur à pied

Introduction : la pratique de la course à pied connaît un essor marqué et s’accompagne d’une augmentation des pathologies locomotrices. En première ligne du parcours de soins, les médecins généralistes jouent un rôle central dans le diagnostic, la prise en charge et la prévention de ces atteintes. Peu de données sont disponibles concernant leurs connaissances, leurs pratiques cliniques et leurs besoins en formation dans ce domaine. Cette thèse vise à dresser un état des lieux des connaissances et des pratiques des généralistes face aux principales blessures du coureur à pied. Matériel et méthodes : il s’agit d’une étude descriptive transversale menée par un questionnaire fermé auprès de médecins généralistes en exercice. Le questionnaire explorait les connaissances diagnostiques, les pratiques cliniques, le recours à l’imagerie, les stratégies thérapeutiques, les modalités d’orientation, la prévention et les besoins en formation en traumatologie du sport. Résultats : 60% des médecins déclaraient recevoir au moins un coureur par semaine en consultation et 71% constataient une hausse de leur fréquentation. Les connaissances diagnostiques étaient globalement maîtrisées pour les atteintes les plus fréquentes telles que les tendinopathies et les lésions musculaires aiguës, tandis que les pathologies moins courantes étaient moins bien reconnues. Les pratiques variaient tant dans l’examen clinique, le recours à l’imagerie et que dans la prise en charge. 80% des médecins déclaraient collaborer avec les kinésithérapeutes et intégrer des conseils de prévention, et 53% exprimaient un intérêt marqué pour un renforcement de leurs compétences. Conclusion : les médecins généralistes sont régulièrement confrontés aux blessures du coureur avec un niveau de maîtrise variable selon les situations cliniques. Les tendinopathies et les lésions musculaires aiguës semblent globalement bien identifiées et prises en charge, à l’inverse du conflit fémoro-acétabulaire, qui demeure insuffisamment connu et reconnu. Cette étude souligne des besoins en formation complémentaire ainsi que l’intérêt d’outils pédagogiques adaptés pour soutenir le raisonnement diagnostic et la prise en charge en soins primaires, dans un contexte de pratique de la course à pied en constante augmentation