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GRB 221009A: Observations with LST-1 of CTAO and implications for structured jets in long gamma-ray bursts
No full textInternational audienceGRB 221009A is the brightest gamma-ray burst (GRB) observed to date. Extensive observations of its afterglow emission across the electromagnetic spectrum were performed, providing the first strong evidence of a jet with a nontrivial angular structure in a long GRB. We carried out an extensive observation campaign in very-high-energy (VHE) gamma rays with the first Large-Sized Telescope (LST-1) of the future Cherenkov Telescope Array Observatory (CTAO), starting on 2022 October 10, about one day after the burst. A dedicated analysis of the GRB 221009A data is performed to account for the different moonlight conditions under which data were recorded. We find an excess of gamma-like events with a statistical significance of 4.1 during the observations taken 1.33 days after the burst, followed by background-compatible results for the later days. The results are compared with various models of afterglows from structured jets that are consistent with the published multiwavelength data, but entail significant quantitative and qualitative differences in the VHE emission after one day. We disfavor models that imply VHE flux at one day considerably above erg cm s. Our late-time VHE observations can help disentangle the degeneracy among the models and provide valuable new insight into the structure of GRB jets
Cemented dual-mobility total hip arthroplasty cups in a custom-made acetabulum: a clinical and radiological evaluation
No full textInternational audienceBackground: Acetabular reconstruction during revision total hip arthroplasty (THA) with major bone loss is a complex surgical challenge. The combination of custom-made (CM) acetabular components with cemented dual mobility (DM) cups may improve postoperative outcomes in this context. This study aims to assess the clinical, functional, and radiological results of this surgical approach. Methods: We conducted a retrospective, single-center observational study including 16 patients (mean age 70 years) who underwent revision THA between May 2016 and December 2024 using a cemented DM cup in a CM acetabular component. All patients presented with Paprosky 3A or 3B defects, and 38% had a history of periprosthetic joint infection (PJI). Functional outcomes were measured using the Oxford Hip Score (OHS) and modified Harris Hip Score (mHHS) pre- and postoperatively. Radiographic assessment included measurement of the center of rotation (COR) deviation in both axes, as well as acetabular inclination and anteversion on postoperative CT scans. Implant survival was analyzed using Kaplan-Meier methodology. Results: At a mean follow-up of 16.2 months, overall implant survival was 75%, increasing to 93.8% when excluding isolated DM cup revisions. No postoperative infections were observed. OHS improved from 14.1 to 27.6 and mHHS from 27.4 to 52.7 (p < 0.001 for both). A significant negative correlation was observed between vertical (y-axis) COR deviation and functional scores (p < 0.01), highlighting the importance of restoring vertical COR. Mean inclination and anteversion were 41.2° and 29°, respectively, generally within target alignment zones. Discussion: The combination of cemented DM cups with CM acetabular components appears to be an effective technique in complex revision THA. Functional recovery and implant survivorship are consistent with the existing literature, and the absence of infection despite prior PJI history suggests benefit from a multidisciplinary approach. Restoration of vertical COR is a predictor of functional outcomes
Lateritic Cenozoic paleoenvironmental and paleoclimatic conditions in the Central Amazon basin, Brazil, inferred from mineralogy, geochemistry and geochronology
No full textInternational audienceLateritic profiles are natural archives recording the weathering history in the tropics over million-year time-scales. This study combines oxygen, hydrogen, and silicon isotope data with mineralogical, geochronological, and geochemical analyses of lateritic secondary mineral assemblages to constrain the environmental and climatic conditions prevailing in the central Amazon Basin during the Cenozoic. The studied lateritic profile was developed over the sedimentary succession of the Alter do Chao Formation in Manaus, Brazil. Three distinct weathering episodes were identified, each constrained by (U-Th)/He and EPR ages. Dated to the Oligocene, the earliest (Oligocene) and long-lasting (duration >10 Ma) weathering episode involves the formation of well-ordered kaolinites through in situ chemical weathering of parent minerals under well-drained conditions, indicative of a tropical climate with restricted seasonality. The second episode, occurring in the mid-Miocene (similar to 16 +/- 3 Ma), involves the formation of a ferruginous duricrust. Most probably resulting from lateral iron migration and precipitation at the oxidizing front of an oscillating water table, the duricrust developed in a context of rising sea levels. The third episode, during the Upper Miocene (similar to 10 Ma), led to the replacement of the kaolinite initially precipitated at the top of the profile by lower-crystallinity kaolinite formed at faster kinetics. This episode coincides with the final phase of the Andean uplift and the onset of the transcontinental Amazon River, reflecting enhanced water drainage under a "monsoon-type" climate
WMSAN: Wave Model Sources of Ambient Noise Python Library. From Modeling to Applications.
No full textInternational audienceInteractions between oceanic waves and the seafloor generate seismic waves recorded globally and referred to as natural ambient “noise.” In particular, the 3-10s period band, known as the secondary microseismic band, corresponds to non-linear oceanic wave-wave interaction and represents the highest peak in a seismic station PSD. While surface waves are prominent in this period band, body waves, which sample deeper areas and are less scattered, can also be identified. These body waves are valuable for examining the properties of the deep Earth due to their sensitivity to the inner medium.In the last decade, improvements in global oceanographic hindcast, such as the WAVEWATCHIII model, have allowed seismologists to track the spatiotemporal behavior of these ocean-generated seismic sources. Since these unconventional sources are non-impulsive, interferometric methods, by correlating signals between stations for a few hours, are necessary to highlight surface and body waves from local to global scale.We introduce the WMSAN Python library for Wave Model Sources of Ambient Noise, which allows for the visualization of oceanic sources of ambient noise distribution and computation of proxy for seismic observables in a user-friendly fashion. This library provides functions and simple examples to map secondary microseismic source distributions for Rayleigh, P, and SV waves using oceanographic data. Seismic data counterparts are then inferred from these source distributions, such as synthetic spectrograms and cross- or auto-correlation functions. We will detail the benchmark examples of this library and its application to extract body wave interference (PP-P) differential travel times from a single secondary microseismic event occurring 8-11 December 2014 in the Northern Atlantic Ocean
Dynamic Mosaicity Modulates Ion Transport in Stimuli‐Responsive Liquid Crystal Electrolytes
No full textInternational audienceStructural mosaicity and defects are ubiquitous across materials and critically influence functional properties, from semiconductors to biological membranes. In soft matter electrolytes, these features remain difficult to probe and exploit due to complex synthesis and limited long‐range structural order. A dimensionally tunable model system based on thermotropic ionic liquid crystals (TILCs) is introduced to investigate the interplay between structural mosaicity and ion transport. In two‐dimensional (2D) anion‐conducting smectic TILCs, ion transport exhibits a pronounced anisotropy—up to four orders of magnitude at 70 °C—attributed to ion confinement within 0.7–1.2 nm‐thick lamellar sublayers. In situ and operando synchrotron X‐ray scattering combined with electrochemical analyses reveal direct experimental evidence of a strong correlation between long‐range supramolecular organization, quantified via dynamic mosaicity, and mesoscopic ion transport. Application of a 1 Tesla magnetic field enhances domain size by 1.5× and boosts conductivity threefold, demonstrating stimuli‐responsive, mosaicity‐controlled ionic transport. These findings establish a generalizable structure–function framework for confined ion conduction in soft materials and bridge concepts from thermotropic liquid crystals to lyotropic phases, biological assemblies, and organic semiconductors. Positioning dynamic mosaicity as a key design parameter, this work lays the foundation for rational development of adaptive, self‐organized electrolyte systems for energy storage and conversion, ionotronics, and bioinspired ionic devices
Next generation of improved High Temperature Membrane Electrode Assembly for Aviation
No full textInternational audienceThe aeronautic industry is facing one of its major challenges: how to reduce its CO2 emissions in the context of a constantly increasing air traffic. High Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFCs) technology is of great interest for aviation, due to his easier thermal management, his low sensitivity to fuel impurities, and a simplified water management system. However, current HT PEMFCs Membrane Electrode Assembly (MEA) operated at 160°C are not at the expected level of performance. In this context, NIMPHEA project aims at developing a new-generation HT MEA at temperature above 120°C, addressing the challenging requirements of fuel cells for aviation. Nowadays, performance limitations are still poorly understood and quantified, which is why mathematical models are essential to the development and understanding of systems. Indeed, models are useful for analyzing the experimental results and better identifying the cause of performance losses, and predicting performance in representative operating conditions to help cell design. In this work, a 2D rib/channel model and a 2D channel model of a HT PEM Fuel cell, have been developed in COMSOL. The first model is used to simulate the flow and electrochemistry in a domain located between two consecutive channels and containing one rib, while the second one allows simulating the physics in a domain which is a plane perpendicular to the cell and parallel to the channels in-between two ribs. Both models integrate the effect of phosphoric acid adsorption on the catalyst. This means that the platinum specific surface is modified with a surface coverage coefficient varying as a function of temperature and potential. The electrochemical parameters used in the models are fitted to experimental measurement perform with a specific cell design (1.8cm²) to promote homogeneous operation in the plane of the active area. The proposed parametrization uses experimental data obtained under various operating conditions: 2 temperatures, 2 pressures, 2 combinations of oxygen fraction and Relative Humidity (RH) and 2 hydrogen fraction combination. The tested single cell was based on commercial Phosphoric Acid doped Polybenzimidazole (PA-PBI) MEA supplied by Advent technologies. With this model, it is possible to analyze performance losses under different conditions and to compare the performances with the ones measured in a technical cell (25cm²). We propose here a comparison of performance losses with a variable RH and a constant partial pressure of oxygen
Probing local vibrational properties of MoS2 monolayer by Tip Enhanced Raman Spectroscopy (TERS)
No full textInternational audienceTransition metal dichalcogenides (TMDs) such as MoS₂ exhibit strong potential for advancedapplications in electronics, optoelectronics and sensing. Few layers or monolayer MoS2 can be obtainedusing various methods, including mechanical exfoliation from bulk sample, chemical vapor deposition,molecular beam epitaxy, etc. In this study, we focus on MoS₂ grown via atomic layer deposition (ALD) [1], atechnique that allows a growth with high homogeneity over large-scale areas, up to 300mm wafer. However,ALD MoS₂ presents a smaller crystallite size (~ few tens of nm) and a relatively higher density of defectscompared to MoS₂ grown by other methods. While micro-scale characterization techniques (e.g., Raman,photoluminescence, X-ray photoemission, etc.) can provide valuable information, nanoscale characterizationis crucial for in-depth understanding of the nature of these defects, which is essential for improving thegrowth process as well as the integration of ALD MoS₂ in devices. Over the last two decades, tip-enhancedRaman spectroscopy (TERS) demonstrated powerful nanoscale analysis capabilities relying on plasmonicenhancement of the electromagnetic field at the apex of a laser-illuminated metallic SPM tip. In this work, wepresent side-illumination TERS analyses of ALD-grown MoS₂ transferred on a gold substrate. The laterleverages the gap-mode configuration to enhance sensitivity. We observed Raman signatures correspondingto in-plane E2g and out-of-plane A1g modes, with variations in relative intensities as a function of position onsample. Our results evidence the significant influence of substrate interactions on the MoS2 and its TERSsignal, emphasizing the need to account for these substrate-induced effects when interpreting the data, thusadvoiding any misinterpretation of the TERS results on the intrinsic property of the grown MoS2. The origin ofobserved variations will be discussed
Black holes and wormholes in sourceless three-dimensional conformal Killing gravity
No full textInternational audienceWe derive all the sourceless solutions of three-dimensional conformal Killing gravity with two Killing vectors. Along with singular solutions and BTZ black holes, the stationary solutions include regular warped AdS3 black holes and wormholes
Archaeobiological evolution of barley (Hordeum vulgare) over the last eight millennia in the northwestern Mediterranean Basin
No full textInternational audienceThe past agrobiodiversity and evolution of barley, a staple cereal in the northwestern Mediterranean region for the last ca 8000 years, is still poorly documented. This study employed an intensive sampling strategy to analyse morphometric variation of 9817 grains (264 samples and 102 sites), dating from the Neolithic to the Late Middle Ages, from southern France and Catalonia. We utilized an archaeophenomic approach to quantify grain size and shape through elliptic Fourier transformation. We contrasted the variation of archaeological grains with that of 6397 caryopses from 105 modern Euro-Mediterranean varieties of 2-row/6-row subspecies, hulled/naked types. Past climate conditions in southern France/Catalonia were investigated to provide an environmental framework for interpreting morphometric variation. Barley grains increased in size, and changed in shape over time, likely owing to a combination of factors, including environmental adaptation and human selection, coupled with changes in agricultural practices. Naked barley was prevalent during the Neolithic, while the proportion of hulled barley increased from the Late Bronze Age onwards. In contrast, subspecies were identified in all assemblages, without clear temporal trends but with strong variation between assemblages. This study uncovers a complex interplay of environmental and human factors in cereal evolution, highlighting the evolution of agrobiodiversity that fuelled the development of modern societies. This article is part of the theme issue ‘Unravelling domestication: multi-disciplinary perspectives on human and non-human relationships in the past, present and future’
