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Oceanographic and hydroclimatic data explain depressed water level in the coastal karst hosting the decorated Paleolithic Cosquer cave (France)
No full textInternational audiencePaleolithic decorated caves are home to a priceless heritage, but their preservation depends on hydroclimatic conditions within the cave. In coastal areas, changing sea levels pose a further threat to caves, as the sea floods the karst and obliterates Paleolithic artefacts. In this paper, we study the case of the Cosquer Cave, a half-submerged coastal cave located in southeastern France, home to Upper Paleolithic archeological remains. This is a very special case, where the sea represents both an opportunity and a threat for the preservation of an archeological site. The cave is confined, submerged in its lower part, and embedded in a limestone massif with low permeability in the unsaturated zone. Several times a year, mainly in autumn, winter, and spring, air flows through the karstic massif, most likely below sea level, raising the cave's air pressure above atmospheric pressure. The resulting overpressure lowers the cave water level for weeks, keeping it below sea level and temporarily keeping the lowest wall paintings and engravings emerged. However, the oceanographic conditions that cause a pressurization event have not yet been described, although it is a key understanding to help preserve the natural heritage housed in the Cosquer Cave. Based on nine years of in situ continuous monitoring, we use descriptive statistics to decipher the oceanographic conditions controlling air inflow, air outflow, and absence of air flow through the submerged karst. We show that waves are the engine for the pressurization of the cave. The three main factors controlling air entrance are wave height, wave direction and seawater level. 90 % of air inflows coincide with significant wave heights exceeding 0.8 m. Additionally, air inflows are more efficiently caused by SSW and SW waves, propagating in a direction orthogonal to the cliff than by waves from the SE-SSE direction, propagating along the cliff. The minimum wave height required for air inflow to occur increases with sea-level rise, likely because submerged conduits become less accessible for air input. This study establishes a conceptual model of functioning for the natural hydrosystem of the Cosquer Cave, and provides the basis for further modeling and predictions according to scenarios of climate change and sea-level rise
Une sémantique de Kahn mécanisée pour les machines à états
No full textInternational audienceLes machines à états hiérarchiques sont utilisées pour programmer des comportements séquentiels ou dépendants d'un mode d'opération. Dans les langages comme Lucid synchrone et Scade 6, elles se composent librement avec les opérateurs flot de données qui sont plus adaptés pour la programmation des filtres et autres algorithmes de l'automatique. Si l'on n'est pas préoccupé par la génération de code pour une exécution en temps et mémoire bornés, les machines à états peuvent être exprimées en termes de réseaux de Kahn récursifs ou, de façon équivalente, par la programmation fonctionnelle avec des flots paresseux. Dans cet article, nous étendons un développement en Rocq des réseaux de Kahn avec des définitions de machines à états, fournissant ainsi une sémantique fonctionnelle pour un langage flot de données ressemblant à un sous-ensemble de Scade 6
Nivolumab in Metastatic Clear-cell Renal Cell Carcinoma: An Integrative Biomarker Analysis from the NIVOREN GETUG-AFU 26 Phase 2 Study
No full textInternational audienceNivolumab improved survival in patients with refractory metastatic clear-cell renal cell carcinoma (ccRCC), but no reliable biomarker of activity has been identified. We conducted a real-world phase 2 trial of nivolumab in patients progressing after one or more vascular endothelial growth factor (VEGF) receptor-directed therapies, which included an integrated translational programme. Candidate tissue and circulating biomarkers were assessed using immunoassays and gene expression profiling. Overall, 720 patients were treated, with activity and safety in line with pivotal trial data. Exploration of tissue architecture showed that the presence of tertiary lymphoid structures, CD8+ lymphocytes, and CD163+ macrophage infiltration at the invasive margin were all marginally associated with longer progression-free survival, similarly to PD-1 expression on immune cells. Expression of hypoxia-related marker VEGF on tumour cells was however strongly associated with shorter progression-free and overall survival. Recapitulation of microenvironment composition based on gene expression signatures showed that patients harbouring a high tumour lymphocyte infiltration, concomitantly to low infiltration of neutrophil and non-immune stromal cells, had improved response to nivolumab. Conversely, circulating cytokines related to protumoral inflammation interleukin (IL)-6 and IL-8 were independently associated with shorter progression-free and overall survival. Overall, immune and angiogenic features helped inform outcomes to nivolumab. Circulating factors were best potential predictors for immunotherapy activity in ccRCC
Euclid Quick Data Release (Q1): Euclid spectroscopy of QSOs. 1. Identification and redshift determination of 3500 bright QSOs
No full textInternational 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 . 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 and 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 (), obvious host structures are common and a single Sersic model fits about half of the sources; at intermediate redshift (), the nuclear component dominates, with 90% of the Sersic fits saturating at the upper index limit. In this intermediate redshift regime, 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
CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission
No full textInternational audienceThe Galactic magnetar SGR 1935+2154 has exhibited prolific high-energy (HE) bursting activity in recent years. Investigating its potential tera-electronvolt counterpart could provide insights into the underlying mechanisms of magnetar emission and very high-energy (VHE) processes in extreme astrophysical environments. We aim to search for a possible tera-electronvolt counterpart to both its persistent and sub-second-scale burst emission. We analysed over 25 h of observations from the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) during periods of HE activity from SGR 1935+2154 in 2021 and 2022 to search for persistent emission. For bursting emission, we selected and analysed nine 0.1 s time windows centred around known short X-ray bursts, targeting potential sub-second-scale tera-electronvolt counterparts in a low-photon-statistics regime. While no persistent or bursting emission was detected in our search, we establish upper limits for the tera-electronvolt emission of a short magnetar burst simultaneous to its soft gamma-ray flux. Specifically, for the brightest burst in our sample, the ratio between tera-electronvolt and X-ray flux is less than . The non-detection of either persistent or bursting tera-electronvolt emission from SGR 1935+2154 suggests that if such components exist, they may occur under specific conditions not covered by our observations. This aligns with theoretical predictions of VHE components in magnetar-powered fast radio bursts and the detection of MeV - GeV emission in giant magnetar flares. These findings underscore the potential of magnetars, fast radio bursts, and other fast transients as promising candidates for future observations in the low-photon-statistics regime with Imaging Atmospheric Cherenkov Telescopes, particularly with the CTAO
Uniform Value and Decidability in Ergodic Blind Stochastic Games
No full textInternational audienceWe study a class of two-player zero-sum stochastic games known as \textit{blind stochastic games}, where players neither observe the state nor receive any information about it during the game. A central concept for analyzing long-duration stochastic games is the \textit{uniform value}. A game has a uniform value if for every \varepsilon>0, Player 1 (resp., Player 2) has a strategy such that, for all sufficiently large , his average payoff over stages is at least (resp., at most ). Prior work has shown that the uniform value may not exist in general blind stochastic games. To address this, we introduce a subclass called \textit{ergodic blind stochastic games}, defined by imposing an ergodicity condition on the state transitions. For this subclass, we prove the existence of the uniform value and provide an algorithm to approximate it, establishing the \textit{decidability} of the approximation problem. Notably, this decidability result is novel even in the single-player setting of Partially Observable Markov Decision Processes (POMDPs). Furthermore, we show that no algorithm can compute the uniform value exactly, emphasizing the tightness of our result. Finally, we establish that the uniform value is independent of the initial belief
Opinion note on nonlinearity in induced polarization
No full textInternational audienceThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for nonlinearities, if they exist, can further enhance the sophistication of our models. Nonlinearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the nonlinearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The nonlinearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the nonlinearities still present. We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence
Turning a solar cell into a catalyst: (Ag,Cu)(In,Ga)Se<sub>2</sub> p–n junction enabling ambient dry reforming of methane
No full textInternational audiencePhotocatalysis driven by solar energy offers a sustainable alternative to thermocatalysis for methane valorization, however large-scale deployment remains limited by catalyst efficiency and scalability. Meanwhile, photovoltaic technologies, though highly developed for electricity generation, still face challenges in costly energy storage and underutilized potential in direct solar-to-chemical energy conversion. In this context, CIGS thin-film solar cells emerge as promising candidates for photocatalytic applications due to their strong light absorption, tunable electronic properties, and industrial scalability. In the present work, we use a thin-film CIGS solar cell plates, re-designed as a monolithic photocatalyst, to drive DRM under ambient conditions. A 2 µm ptype (Ag,Cu)(In,Ga)Se2 (ACIGS) absorber deposited on a soda-lime glass/Mo substrate is overcoated with an ntype CdS layer, forming a p-n junction that couples strong light absorption with built-in charge separation. Under irradiation, ACIGS/CdS plates produce > 2 mmol g cat -1 syngas with ≈ 85 % CO selectivity at ambient conditions, without any external electric power or thermal input. Mechanistic evidence indicates deep CH4 dissociation to surface carbon and hydrogen, with subsequent CO2 reduction by surface carbon to CO. The catalytic plates are air-regenerable under light and exhibit notable stability. Turning a solar-cell design into the catalytic junction tackles efficiency and manufacturing hurdles for CH4/CO2 conversion. Because CIGS and CdS processes already exist at industrial scale, this approach provides a practical route to deployable solar chemical hardware; further gains are expected from junction optimization and selective co-catalysts
Unlocking the radio-gamma spectrum of the pulsar wind nebula around PSR J1124-5916 in SNR G292.0+1.8
No full textInternational audienceWe present the first detection of GeV -ray emission potentially associated with the pulsar wind nebula (PWN) hosted by the young core-collapse supernova remnant G292.0+1.8, based on a detailed time-resolved analysis of \textit{Fermi}-LAT data. By isolating the unpulsed component from the dominant magnetospheric radiation of PSR~J11245916, we successfully disentangle a candidate nebular emission in the GeV range, characterise its morphology and extract its spectrum. This identification places G292.0+1.8 among the few systems in which the pulsar and PWN contributions have been spectrally resolved at high energies, offering new insight into their respective emission mechanisms. We characterise the -ray spectrum of the pulsar and model the broadband spectral energy distribution (SED) of the PWN using radio, X-ray, and GeV data. The emission is well described by a single electron population with two spectral breaks: one intrinsic to the injection spectrum and another produced by synchrotron cooling in a magnetic field of 15~G. Notably, the inferred magnetic field and the low TeV flux of the nebula resemble those of 3C~58, suggesting that similar low-field environments can arise in young PWNe. The high-energy portion of the SED is now tightly constrained by our GeV detection and existing TeV upper limits. Compared to our model, earlier predictions tend to underpredict the -ray flux, while others that succeed in reproducing the GeV component often overpredict the TeV emission. This mismatch underscores the challenges in modelling particle acceleration and radiation processes in young PWNe and establishes G292.0+1.8 as a valuable benchmark for testing and refining such models