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Influence of printing orientation of Inconel 718 specimens on LEFM parameters analyzed via DVC
No full textInternational audienceLaser powder bed fusion (LPBF) is an additive manufacturing technique that enables for the production of metallic parts with complex geometries, and the possibility of locally adapting mesostructures. This study aims at determining the influence of hatch angle and build orientation on Linear Elastic Fracture Mechanics (LEFM) parameters of specimens obtained by LPBF. In the present work, the mechanical response of mini CT specimens made of Inconel 718 alloy obtained by LPBF were studied when subjected to in-situ tensile loading. The LEFM parameters of the different specimens were extracted from displacement fields measured with Digital Volume Correlation (DVC) using Williams' fields. The crack front and Stress Intensity Factors (SIF) profiles of the different experiments were analyzed. The extracted LEFM parameters for the different specimens displayed significant differences in Young's Modulus and fracture toughness due to variations in build orientation
A wide-field X-ray search for the Geminga pulsar halo with SRG/ART-XC
No full textInternational audienceSearches for the putative large-scale X-ray halo around the Geminga pulsar have been extensively performed using various narrow field-of-view X-ray telescopes. In this paper, we present wide-field scanning observation of Geminga with SRG/ART-XC. Our X-ray analysis provides, for the first time, direct imaging of a region in the keV energy band, comparable in extent to the expected Geminga emission. The ART-XC observation provides a highly uniform sky coverage without strong vignetting effects. The synchrotron X-ray halo flux was predicted using a physical model based on particle injection, diffusion, and cooling over the pulsar's lifetime, as well as the spectral and spatial properties of the synchrotron X-ray and inverse-Compton gamma-ray emissions. The model is tuned to reproduce existing multiwavelength data from X-ray upper limits and GeV to TeV gamma-ray observations. After accounting for the high particle background and its uncertainties, no significant emission is found in the assumed source region, and X-ray flux upper limits are derived. These limits are less constraining by up to a factor of three with respect to existing results obtained with narrow field-of-view telescopes and longer exposure times. Nonetheless, we place direct and independent constraints on Geminga's ambient magnetic field strength, which are compatible with other studies. Our methodology, including simulation for longer observation times, is applied for the first time to the wide field-of-view search for pulsar halos. Using extensive simulations, we also show that a 68% probability of detecting the Geminga pulsar halo can be achieved with a 20-day SRG/ART-XC exposure for a 3 magnetic field
Spectral induced polarization monitoring of toluene biodegradation by Rhodococcus wratislaviensis in controlled laboratory conditions
No full textInternational audienceThe global prevalence of organic pollutants presents a significant environmental challenge, necessitating sustainable remediation strategies. In situ biodegradation emerges as a cost-effective and eco-friendly solution. However, the real-time monitoring of in situ bacterial activities, particularly biodegradation processes, remains a challenge due to the limitations of traditional intrusive methods, including issues of representativeness, reproducibility and high-associated costs. Spectral induced polarization (SIP) has shown sensitivity to surface changes in subsurface environments, especially for biogeochemical reactivity monitoring including those associated with biodegradation. Despite this potential, advances have to be made to quantitatively link SIP parameters to in situ biodegradation processes. This study addresses this gap by conducting controlled biogeophysical experiments on a sand-packed column undergoing biodegradation facilitated by Rhodococcus wratislaviensis IFP 2006. SIP measurements were paired with bacterial growth kinetics to develop a quantitative model estimating bacterial growth. The results demonstrate that SIP, coupled with routine laboratory measurements, can effectively and quantitatively assess bacterial growth and the biodegradation of organic pollutants. These findings highlight the potential of SIP as a non-intrusive and reliable method for monitoring biodegradation in contaminated subsurface environments
Clinical Phenotypes of Critically Ill Patients with COVID-19 Infected with Omicron: A Nationwide Prospective Cohort Study
No full textInternational audienceINTRODUCTION: The clinical presentation of critically ill patients with coronavirus disease 2019 (COVID-19) has evolved significantly with the emergence of the Omicron variant. Current intensive care unit (ICU) admissions involve patients with diverse comorbidities and immune statuses, highlighting the need to redefine homogeneous phenotypic subgroups within this population. This study aimed to characterize distinct clinical phenotypes among critically ill patients with COVID-19 and acute respiratory failure. METHODS: This multicenter prospective substudy of the SEVARVIR cohort included adult patients from 39 French ICUs between December 2021 and October 2024 with acute respiratory failure and infected with the Omicron variant. Clustering analysis was conducted using Kohonen’s self-organizing maps (SOMs) and validated with ClinTrajan, two unsupervised clustering methods, to identify homogeneous patient phenotypes. RESULTS: During the study period, 777 patients with Omicron infection were included, and 7 distinct clinical clusters were identified. Clusters 1 and 2 included patients with metabolic and cardiovascular comorbidities. Cluster 3 featured younger, mildly ill patients with isolated chronic respiratory failure, while cluster 4 comprised older male patients with isolated respiratory failure. Cluster 5 included patients with isolated hematologic malignancies, cluster 6 patients with multiorgan failure, and cluster 7 organ transplant recipients, with high severity scores and impaired renal function. ICU management varied substantially across clusters. Patients in clusters 5 and 7 had the highest requirements for organ support, with frequent use of invasive mechanical ventilation, vasopressors (cluster 6), and renal replacement therapy (cluster 7). Dexamethasone and tocilizumab were most commonly prescribed in cluster 4 (91.3% and 30.2%, respectively). Mortality at day 28 varied significantly across clusters, ranging from 13.1% in cluster 3 to 41.1% in cluster 6. CONCLUSIONS: This clustering analysis highlights, for the first time, the clinical heterogeneity of critically ill patients infected with Omicron, identifying seven distinct clusters with varying clinical presentations, management strategies and outcomes. These findings underscore the relevance of a phenotype-driven approach to support personalized treatment strategies and guide future clinical trials. TRIAL REGISTRATION: Clinicaltrials.gov, NCT05162508. A Graphical Abstract is available for this article
Le genre Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) à Madagascar, avec la description de 12 nouvelles espèces, 4 nouvelles sous-espèces et 1 nouvelle variété
No full textPignal M., Phillipson P.B. & Bardot-Vaucoulon M. 2025. The genus Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) in Madagascar, with the description of 12 new species, 4 new subspecies and 1 new variety. European Journal of TaxonomyThe genus Chlorophytum Ker Gawl. (Asparagaceae) is revised taxonomically for Madagascar. It is a palaeotropical genus of more than 200 species, all of which are geophytes that are distributed throughout Africa, the Arabian Peninsula (Oman), Southeast Asia, the Indian subcontinent, China and Australia. We recognise 39 endemic taxa for Madagascar (30 species, 4 subspecies, 3 varieties and 2 potential species not formally named due to incomplete material). Descriptions and geographical data are provided for all taxa, of which 17 are newly described in this revision: 12 species (C.Le genre Chlorophytum Ker Gawl (Asparagaceae) fait l'objet d'une révision taxonomique pour Madagascar. Il s'agit d'un genre paléotropical comptant plus de 200 espèces, toutes géophytes, réparties en Afrique, dans la péninsule arabique (Oman), en Asie du Sud.-Est., dans le sous-continent indien en Chine et en Australie. Nous reconnaissons 39 taxons endémiques à Madagascar (30 espèces, 4 sous-espèces 3 variétés et 2 espèces potentielles non nommées officiellement en raison d’un matériel incomplet). Les descriptions et les données géographiques sont fournies pour tous les taxons, dont 17 sont nouvellement décrits dans cette révision : 12 espèces, (C. albociliatum sp. nov., C. aspidistrifolium sp. nov., C. basivaginatum sp. nov., C. candelabrum sp. nov., C. darainense sp. nov., C. helvillae sp. nov., C. meridionale sp. nov., C. nigrogranulosum sp. nov., C. nusbaumeri sp. nov., C. ranirisonii sp. nov., C. ratovosonii sp. nov., C. tolyanum sp. nov.) ; 4 sous-espèces (C. sofiense subsp. gautieri subsp. nov., C. graniticum subsp. ambrense subsp. nov., C. meridionale subsp. ihoyense subsp. nov., C. meridionale subsp. tulearense subsp. nov.) et 1 variété. (C. madagascariense var. boinense var. nov.). Chlorophytum gramineum (Baker) H.Perrier, est basé sur un nom illégitime (Anthericum gramineum Baker), et est remplacé par le nom légitime postérieur, C. madagascariense Baker, que nous considérons comme un synonyme taxonomique. Nous conservons les variétés décrites par Perrier de la Bâthie au sein de cette espèce, en les transférant à C. madagascariense, et nous décrivons une variété supplémentaire : C. madagascariense var. pervillei. De plus, nous désignons un lectotype pour huit espèces C. decaryanum, C. decipiens, C. dianellifolium, C. geayanum, C. graniticum, C. namorokense H.Perrier, C. sofiense, C. subligulatum, et deux variétés : C. dianellifolium var. transiens et C. madagascariense var. sciaphilum comb. nov.) . Une clé d'identification et des évaluations préliminaires du statut de conservation selon les critères de la Liste rouge de l'UICN sont fournies pour toutes les espèces.Mots-clefs : Anthericum, Anthericaceae, Asparagacea
A prospective clinical evaluation of new ECCO2R technology in mild to moderate ARDS patients: assessing ultra-lung-protective ventilation with PRISMALUNG+
No full textInternational audienceBackgroundExtracorporeal carbon dioxide removal (ECCO2R), when used as an adjunct to mechanical ventilation in patients with mild to moderate acute respiratory distress syndrome (ARDS), has been proposed as a strategy to control hypercapnic acidosis during ultra-lung-protective ventilation (ULPV). However, no multicenter study has systematically assessed ventilation improvement markers with a standardized protocol using ECCO₂R devices featuring a peristaltic pump design. This prospective, multicenter study conducted in France addresses these gaps by evaluating the performance and safety of PRISMALUNG+, a novel membrane lung specifically developed for ECCO2R, either as a standalone therapy or combined with continuous renal replacement therapy (CRRT). A specific protocol for ULPV was used to minimize lung stress and mitigate the risk of hypoxemia.MethodsBetween April 2021 and December 2023, 58 patients were treated with ECCO2R (16 in combination with CRRT). Tidal volume (VT) was reduced stepwise from 6 mL/kg to 4 mL/kg. Once the partial pressure of carbon dioxide (PaCO2) exceeded 50 mmHg, sweep gas (100% oxygen at 10 L/min) was initiated to provide ECCO2R. Outcomes were measured at 8 and 24 h, while safety was monitored until discharge or day 28.ResultsDuring VT reduction and before ECCO2R initiation, peak hypercapnia and respiratory acidosis reached PaCO2 of 53.0 [50.0–55.0] mmHg and pH of 7.30 [7.24–7.36]. After 24 h of treatment, VT significantly decreased from 6.0 [6.0-6.1] to 4.0 [4.0-4.30] (p < 0.0001), driving pressure (∆P) from 12.0 [10.0–16.0] cmH2O to 10.0 [8.0–13.0] cmH2O (p < 0.0001), ventilatory ratio (VR) from 1.7 [1.5–2.1] to 1.3 [1.0-1.6] (p < 0.0001) and mechanical power from 18.8 [15.0–22.0] J/min to 11.8 [8.8–15.5] J/min (p < 0.0001). PaO2/FiO2 did not significantly change over time and respiratory acidosis resolved with treatment, as evidenced by normalization of pH and a reduction in PaCO2. Importantly, no major bleeding events, intracranial hemorrhages, or hemolysis were reported during the study.ConclusionThis study demonstrates that hypercapnic acidosis occurring during ultra-low VT ventilation (ULPV) can be safely mitigated with ECCO₂R in mechanically ventilated patients with mild to moderate ARDS. Moreover, under ULPV, ∆P, VR and mechanical power were improved without inducing hypoxemia
Exploring the Vibrational Raman Modes of P-O-P Bonds in Oligomeric Sodium Metaphosphates: A Comprehensive DFT Study
No full textInternational audienceThis work presents an in-depth density functional theory (DFT) study aimed at elucidating the Raman vibrational patterns of P-O-P bonds in oligomeric structures of sodium metaphosphate (NaPO₃)n structures. To investigate their vibrational behavior, DFT methods were employed on three oligomeric crystal structures: monoclinic, triclinic, and orthorhombic, as well as a nonperiodic cyclic structure. Vibrational frequencies, computed using several exchange-correlation functionals and basis sets, were compared with the available Raman spectra in the literature, showing good agreement. The normal modes were analyzed, and the role of external conditions (laser, temperature, and pressure) was computed and discussed. The PBE0 functional combined with the DZVP provided the best geometry, while the TZVP basis set provided the best overall agreement with the experimental vibrational results, accurately capturing the majority of key vibrational peaks, including the critical P-O-P bond stretching modes. These findings clarify the origin and characteristics of vibrational modes in (NaPO₃)n structures and the role of external factors common in the search for complex phosphate materials
Teukolsky on slowly-rotating Kerr-de Sitter in the vanishing limit
No full textWe prove energy, Morawetz and rp-weighted estimates for solutions to the Teukolsky equation set on a slowly-rotating Kerr-de Sitter background. The main feature of our estimates is their uniformity with respect to the cosmological constant Λ>0 (thus allowed to tend to 0), while they hold on the whole domain of outer communications, extending up to r∼Λ−12. As an application of our result, we recover well-known corresponding estimates for solutions to Teukolsky on a slowly-rotating Kerr background in the limit Λ→0
Benchmark for two-dimensional large scale coherent structures in partially magnetized E×B plasmas -Community collaboration & lessons learned
No full textLow-temperature plasmas are essential to both fundamental scientific research and critical industrial applications. As in many areas of science, numerical simulations have become a vital tool for uncovering new physical phenomena and guiding technological development. Code benchmarking remains crucial for verifying implementations and evaluating performance. This work continues the Landmark benchmark initiative, a series specifically designed to support the verification of low-temperature plasma codes. In this study, seventeen simulation codes from a collaborative community of nineteen international institutions modeled a partially magnetized E×B Penning discharge. The emergence of large scale coherent structures, or rotating plasma spokes, endows this configuration with an enormous range of time scales, making it particularly challenging to simulate. The codes showed excellent agreement on the rotation frequency of the spoke as well as key plasma properties, including time-averaged ion density, plasma potential, and electron temperature profiles. Achieving this level of agreement came with challenges, and we share lessons learned on how to conduct future benchmarking campaigns. Comparing code implementations, computational hardware, and simulation runtimes also revealed interesting trends, which are summarized with the aim of guiding future plasma simulation software development.</div
Biochemical signatures of Holothuria tubulosa and Holothuria forskali (Echinodermata) in co-culture with sea bass in the Frioul Islands (France)
No full textInternational audienceConsiderable knowledge in the reproductive biology, habitat and life-history traits of European sea cucumbers was acquired in recent years with the objective to use them as extractive species in multi-trophic aquaculture systems. Yet, the trophic link between aquaculture wastes and sea cucumbers remains insufficiently evidenced. The aim of this study was to assess the potential of Holothuria tubulosa and H. forskali to utilise fish waste as a food source within a co-culture system. The two species were placed below sea bass cages in the northwest Mediterranean Sea. After one year of caging, fatty acids and stable isotopes indicated that sea cucumbers located near the fish cages were in good physiological condition. Higher levels of the fatty acid 18:2ω6, a biomarker of terrestrial plant oils, in sea cucumber tissues clearly indicate the transfer of fish feed to holothurians. In the case of H. forskali, this signature was also linked to an increase in bacterial biomarkers, indicating that sea cucumbers likely do not feed directly on fish wastes. Feeding habits differed between the two species, with H. tubulosa poorly modifying its diet when placed in captivity but probably requiring a significant access to sediment to maintain growth, while H. forskali probably collecting increased secondary production stimulated by the inputs of fresh organic matter directly on the cage walls. Finally, fatty acid profiles of both the body wall and muscular bands of the sea cucumbers revealed a similar imprinting of fish feed, indicating that each tissue can be analysed individually for trophic purposes