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Development and characterization of clay bio-composites for enhanced thermal performance: a sustainable approach utilizing Posidonia oceanica leaves
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Probing millisecond magnetar formation in binary neutron star mergers through X-ray follow-up of gravitational wave alerts
No full textInternational audienceThe nature of the remnant of a binary neutron star (BNS) merger is uncertain. Though certainly a black hole (BH) in the cases of the most massive BNSs, X-ray lightcurves from gamma-ray burst (GRB) afterglows suggest a neutron star (NS) as a viable candidate for both the merger remnant as well as the central engine of these transients. When jointly observed with gravitational waves (GWs), X-ray lightcurves from BNS merger events could provide critical constraints on the remnant's nature. We aim to assess the current and future capabilities to detect a NS remnant through X-ray observations following GW detections. To this end, we simulate GW signals from BNS mergers and the subsequent X-ray emission from newborn millisecond magnetars. The GW detectability is modeled for both current and next-generation interferometers, while the X-ray emission is reproduced using a dedicated numerical code that models magnetar spin-down and ejecta dynamics informed by numerical-relativity simulations. In our simulations, 2% - 16% of BNS mergers form millisecond magnetars. Among these, up to 70% could be detectable, amounting to up to 1 millisecond magnetar detection per year with SVOM/MXT-like instruments during the LIGO Virgo KAGRA LIGO India (LVKI) O5 run, with optimal detectability occurring about 2 hours post-merger. For next-generation GW interferometers, this rate could increase by up to three orders of magnitude, with peak detectability 3 to 4 hours post-merger. We also explore how the magnetar's magnetic field strength and observer viewing angle affect detectability and discuss optimized observational strategies. Although more likely with upcoming GW interferometers, detecting the spin-down emission of a millisecond magnetar may already be within reach, warranting sustained theoretical and observational efforts given the profound implications for mergers, GRBs, and NS physics of a single detection
How contrasted environments in the Humboldt Current System, Pacific Warm Pool and South Pacific Gyre, shape contrasted ecosystems. A modelling approach using APECOSM
No full textInternational audiencePelagic ecosystems exhibit a strong regional heterogeneity, driven by physical and biogeochemical characteristics. Using the global 3D marine ecosystem model APECOSM, we simulate six high-trophic-level communities, capturing their size structure, spatial distribution, and trophic interactions up to 1,000 metres depth. We examine how different environments shape their contrasting organisation and interactions in three Pacific Ocean regions: the productive Humboldt Current System, the oligotrophic South Pacific Gyre, and the thermally stratified Pacific Warm Pool. Simulations reveal strong regional contrasts in ecosystem responses. In the Humboldt, high primary production supports important biomass of small coastal pelagic fish. Seasonal warming enables tuna to forage in these productive waters, while low-oxygen conditions restrict the vertical range and abundance of mesopelagic organisms and concentrate epipelagic organisms close to the surface. In the Warm Pool, apex predators remain abundant despite low primary production, thanks to efficient trophic transfer and biomass import from neighbouring regions. Seamounts concentrate mesopelagic organisms into shallow layers, making them accessible to epipelagic predators. In contrast, the South Pacific Gyre supports sparse, imported high-trophic-levels with limited trophic coupling and strong intra-community predation. We quantify regional differences in trophic transfer efficiency and network complexity, identifying thresholds below which high-trophic-levels collapse. These findings illustrate the emergent plasticity of pelagic ecosystems and the importance of bottom-up control of high-trophic-level biomass. They emphasise the importance of temperature, transport, light and oxygen in modulating horizontal and vertical distributions, controlling the co-occurrence of predators and prey, and influencing the formation of schools, ultimately impacting trophic interactions and community assemblages
Antidote administration in mice exposed to sarin resulted in brainwave stabilization without cognitive protection: Partial neuroprotective effects of antidote in mice exposed to sarin
No full textInternational audienceResurgence of sarin use in the Syrian conflict demonstrates that chemical weapons are a vivid threat. Like other organophosphate compounds, sarin inhibits acetylcholinesterase resulting in cholinergic crisis. The current antidote therapy includes atropine (a muscarinic cholinergic antagonist) + an oxime (e.g., pralidoxime) to reactivate the inhibited cholinesterases. Long-term sequelae reported in victims of the 1995 Tokyo subway sarin attack emphasize the need to improve neuroprotection and to delineate more precise biomarkers of intoxication severity. Previously, we proposed that brain oscillations could indicate exposure severity to a sublethal dose of a neurotoxic agent. In the present study, we evaluated the effects of atropine + pralidoxime in mice exposed to a sublethal dose of sarin (0.9 LD 50 ) on changes in short-term recovery, brainwaves and behavioral patterns. We demonstrated the benefits of the antidotes on alleviation of the sarin-induced encephalopathy, stabilization of brain oscillations, and attenuation of anhedonia behavior. Nevertheless, mice exhibited work memory impairments associated with the disruption of theta oscillations during the task, the disruption of sleep architecture and the anxiety-like behavior when exposed to the non-convulsive sarin dose. These outcomes were not mitigated by atropine + pralidoxime administration. Our findings suggest that the currently recommended antidote for sarin poisoning provides only partial neuroprotection. Despite stabilizing brain waves in resting state, current antidote is not effective in preventing long-term neurobehavioral complication
TXS 0506+056-like blazar sources and their role as possible neutrino emitters
No full textInternational audienceThe interest in blazars as candidate neutrino emitters grew after the 3 evidence for a contemporaneous joint photon and neutrino emission from the flaring blazar TXS 0506+056 in 2017. Blazars, a class of extragalactic sources with relativistic jets pointing toward Earth, present a broadband emission interpretable via leptonic and hadronic processes, the latter relevant for proton acceleration and neutrino production. Several emission models have been developed to explain this multi-messenger observation, but the details of the neutrino production and the nature of TXS 0506+056 are not yet fully understood. In this work we investigate the properties of sources similar to TXS 0506+056. We select a sample of blazars from the Fermi 4LAC-DR2 catalog by constraining a number of key parameters in ranges centered on TXS 0506+056 values. We estimate their disk accretion efficiency and model their spectral energy distribution (SED) in terms of lepto-hadronic emission, gaining information respectively on the potential similarity of their environment with that of TXS 0506+056 and on their neutrino flux and detectability prospects at TeV energies. Our study shows the candidates’ high energy emission to be dominated by leptonic processes. Part of them also show a high accretion rate, characteristic of FSRQs. For these sources, the very high energy (VHE) and neutrino fluxes appear undetectable by current and future instruments in an average emission state
Assessing the integrity of SARS-CoV-2 and F-specific RNA bacteriophage RNA in raw wastewater (ANRS0160)
No full textInternational audienceRNA integrity is an essential parameter for analyzing the nature of viral particles, especially in environmental samples where assessing virus infectivity is often difficult or impossible. It is also an important factor in the effectiveness of virus sequencing in environmental matrices containing mixed viral populations composed of variants that differ from one another by only a limited number of mutations, such as in the case of SARS-CoV-2. This study introduces a multiplex Reverse Transcription Digital PCR (RT-dPCR) method for evaluating the RNA integrity of SARS-CoV-2 and F-specific RNA phages belonging to subgroup I (FRNAPH-I) using synthetic RNA, viral stocks, and then raw wastewater (WW) in which SARS-CoV-2 and FRNAPH-I were naturally present. An initial approach using one-step multiplex digital Reverse Transcription PCR (dRT-PCR) demonstrated unequal detection across the genomic regions of both FRNAPH and SARS-CoV-2. To overcome this methodological bias, a two-step method called Long-Range Reverse Transcription digital PCR (LR-RT-dPCR) was developed. This approach involves performing long-range reverse transcription at the 3′ end using a single specific reverse primer to generate contiguous cDNA that spans multiple targets of interest. Following cDNA synthesis, the sample is partitioned, and a multiplex amplification is carried out on targets located at the 3′ end, middle, and 5′ end of the sequence. The LR-RT-dPCR method enabled uniform detection with enhanced sensitivity and was validated using capillary electrophoresis on synthetic RNA of MS2, a phage which belongs to the FRNAPH-I subgroup. LR-RT-dPCR was employed in both triplex and quintuplex formats to analyze the MS2 phage genome (3,569 nucleotides (nt)) and SARS-CoV-2 genome (∼30,000 nt), respectively. Using this approach, viral RNA integrity was evaluated through the detection frequencies of genome fragments of the whole genome. The viral stocks of MS2 phages replicated in a laboratory and stored in phosphate-buffered saline (PBS) exhibited high RNA detection frequencies (> 50 %). In WW, RNA detection frequency was significantly lower, not exceeding 2 % even for the shortest fragment of the FRNAPH-I genome. On the other hand, SARS-CoV-2 RNA showed greater detection frequency than FRNAPH-I RNA in WW, with values exceeding 30 % for short fragments (<1,500 nt) and ranging from 0 % to 44 % for longer fragments (1,500 to 3,500 nt). The relationship between the detection frequency of a fragment and its length does not appear to be strictly linear, as factors other than length can influence genome integrity. These factors include the intrinsic properties of specific genomic regions. For example, the S3-ORF3a region of the SARS-CoV-2 genome appears particularly stable
The Tianlai-WIYN North Celestial Cap Redshift Survey
No full textInternational audienceWe present the results of a small, low redshift spectroscopic survey of galaxies within 3 degrees of the North Celestial Pole (NCP) selected using V-band photometry obtained from the North Celestial Cap Survey (NCCS) (Gorbikov & Brosch 2014). The purpose of the current survey is to create a redshift space template for 21 cm emission from neutral hydrogen with which to correlate radio line intensity observations by the Tianlai dish and cylinder interferometers. A total of 898 redshifts were obtained from the 2102 extended objects in the NCCS with m_V < 19 in the survey area. After accounting for extinction, the survey geometry and selection effects, the number density and clustering pattern of galaxies in the redshift catalog are consistent with other low redshift surveys. We were also able to identify 11 galaxy cluster candidates from this redshift catalog
Search for charged Higgs bosons decaying into top and bottom quarks in lepton+jets final states in proton-proton collisions at = 13 TeV
No full textInternational audienceA search is presented for charged Higgs bosons (H) in proton-proton (pp) collision events via the pp (b)H processes, with H decaying into top (t) and bottom (b) quarks. The search targets final states with one lepton, missing transverse momentum, and two or more b jets. The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb. We search for charged Higgs bosons in the 200 GeV to 1 TeV mass range. The results are interpreted within the generalized two-Higgs-doublet model (g2HDM). This model predicts additional Yukawa couplings of the Higgs bosons to the top quark , the top and charm quark , and the top and up quark . This search focuses on the real components of and , which are probed up to values of unity. An excess is observed with respect to the standard model expectation with a local significance of 2.4 standard deviations for a signal with an H boson mass () of 600 GeV. Limits are derived on the product of the cross section (pp (b)H) and branching fraction (H tb, t b), where = e, . The values of 0.150.5 are excluded at 95% confidence level, depending on the and assumptions. The results represent the first search for charged Higgs bosons within the g2HDM framework and complement the existing results on additional neutral Higgs bosons
Clustering redshift distribution calibration of weak lensing surveys using the DESI-DR1 spectroscopic dataset
No full textInternational audienceWe estimate the source redshift distribution of current weak lensing surveys by applying the clustering-based redshift calibration technique, using the galaxy redshift sample provided by the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1). We cross-correlate the Bright Galaxy Survey (BGS), Luminous Red Galaxies (LRGs) and Emission Line Galaxies (ELGs) from DESI, within the redshift range , with overlapping tomographic source samples from the Dark Energy Survey (DES), Kilo-Degree Survey (KiDS), and Hyper Suprime-Cam (HSC) survey. Using realistic mock catalogues, we test the stability of the clustering-redshift signal to fitting scale, reference-sample choice, and the evolution of source galaxy bias, and we explicitly model and marginalise over magnification contributions, which become non-negligible at due to the depth of the DESI ELG sample. We then compare the resulting bias-weighted redshift distributions to those calibrated using self-organising map (SOM) techniques, finding agreement within uncertainties for all surveys and tomographic bins. Our results demonstrate that clustering redshifts enabled by DESI's unprecedented spectroscopic sample provides a robust, complementary, and independent constraint capable of reducing one of the dominant systematic uncertainties in weak lensing cosmology
Confinement properties of zeolite-rich rocks with respect to water and various ionic tracers
No full textInternational audienceThe studied materials are zeolite-rich rocks (>70 wt% analcime, named analcimolite) forming a laterally continuous aquitard within the southern of the Tim Mersoï Basin (Niger). This unit, commonly referred to as the Abinky Formation, occurs as three mineralogical facies: a reduced facies containing Fe-chlorite, an oxidized facies with hematite, and an intermediate 'transition' facies. This analcimolite unit acts as an aquitard, separating the overlying and underlying sandstone aquifers, the latter locally providing potable water. Due to the low permeability of these analcime-rich rocks, diffusion is expected to be the dominant transport mechanism. However, no data on transport properties in zeolite-rich formations have been reported, and the mobility of water and ionic solutes remains unknown. This study aims to characterize diffusion in the three facies of the Abinky formation, identifying key controls on water and ion transport prior to any anthropogenic perturbation. Through-diffusion experiments using water tracers (HDO and HTO) showed that water diffusion (effective diffusion coefficient from 1.3 to 2 × 10 -11 m²/s) is primarily controlled by pore throat size rather than total porosity. A dual-porosity model was required, distinguishing a fast-transport network (open, low-tortuous zones) from a slow one (confined, tortuous zones). Despite variations in diffusion coefficients, all data are interpreted with capacity factors equal to total external porosity measured by water impregnation (excluding crystal water located in zeolite micropores). This confirms that water behaves as an inert tracer and that micropores contribute negligibly to water migration. For ionic tracers in reduced facies, 36 Cl -is partially excluded from external pores (anionic exclusion) and slightly adsorbed, with an extent of about 0.1 meq/100 g, a very small value compared to the cation exchange capacities of such rocks (up to ~40 meq/100 g for H+ and NH4+ ). In contrast, ²²Na⁺ exhibits strong adsorption due to isotopic exchange with 23Na+ in the analcime framework, leading to a diffusivity ~4 times higher than that of water. This dataset is a first step in constraining reactive transport models of water and solutes in zeolite-rich porous media under environmental conditions and prior to anthropogenic disturbance