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Measurements of quasar proximity zones with the Lyman- forest of DESI Y1 quasars
No full textInternational audienceThe intergalactic medium (IGM) around quasars is shaped by their dense environments and by their excess ionizing radiation, forming a "quasar proximity zone" whose size and anisotropy depend on the quasar's halo mass, luminosity, age, and radiation geometry. Using over 10,000 quasar pairs from the Dark Energy Spectroscopic Instrument (DESI) Year 1 data, with projected comoving separations , we investigate how the proximity zone of foreground quasars at affects Lyman-alpha absorption in their background quasars. The large DESI sample enables unprecedented precision in measuring this "transverse proximity" effect, allowing a detailed investigation of the signal's dependence on the projected separation of quasar pairs and the luminosity of the foreground quasar. We find that enhanced gas clustering near quasars dominates over their ionizing effect, leading to stronger absorption on neighboring sightlines. Under the assumption that quasar ionizing luminosity is isotropic and steady, we infer the IGM overdensity profile in the vicinity of quasars, finding overdensities as high as at comoving distance from the most luminous systems. Surprisingly, however, we find no significant dependence of the proximity profile on the luminosity of the foreground quasar. This lack of luminosity dependence could reflect a cancellation between higher ionizing flux and higher gas overdensity, or it could indicate that quasar emission is highly time variable or anisotropic, so that the observed luminosity does not trace the ionizing flux on nearby sightlines
Microstructural and sorption properties evolution on leached geopolymers for strontium decontamination
No full textInternational audienceGeopolymers are promising materials to be used as strontium adsorbent in fixed-bed processes for nuclear wastewater decontamination. Nevertheless, geopolymer formulation parameters – SiO2/M2O, H2O/M2O molar ratios – influence microstructure and strontium sorption property evolution under water leaching. Increasing the SiO2/M2O ratio increases the geopolymer’s compressive strength (16 MPa to 35 MPa) and reduces silicon leaching in water (1.31 mmol.g−1 to 0.26 mmol.g−1). This resistance to leaching results from a silicon-richer structure, reinforcing hydrolysis resistance. An increase in H2O/M2O ratio reduces the material’s strength (59 MPa to 28 MPa), and increases leaching due to greater porosity. Then, water leaching lowers sorption properties of the geopolymers by releasing AlIV, which are exchange sites for cations. Nonetheless, the composition with the lowest AlIV concentration achieved the highest distribution coefficient (KD) and fastest kinetics. This highlights the critical role of the silicon environment for optimal cation trapping, outmatch the total concentration of AlIV sites
Neoantigenic properties of TP53 variants influence cancer risk in individuals with Li-Fraumeni syndrome
No full textInternational audienceBackground Li-Fraumeni Syndrome (LFS) is a heterogenous cancer predisposition condition caused by pathogenic TP53 variants, characterised by a lifelong high risk of a broad spectrum of cancers. Certain pathogenic TP53 variants have been shown be immunogenic in a somatic context. Whether neoantigenicity contributes to LFS heterogeneity is unknown. In this study we analysed the correlations between predicted neoantigenic properties of pathogenic TP53 missense variants and LFS phenotypes. MethodsMHC-I presentation scores were generated for the set of nonameric neo-peptides surrounding each TP53 missense variant against 145 different HLA-I using NetMHCpan 4.1 and the Allele Frequency Net Database. A predicted neoantigenic score (PNS) was calculated for each variant. Association study was performed between PNS, LFS presentation and individual HLA-I genotyping, in individuals carrying TP53 germline pathogenic variants using data from mutation databases and clinical registries. Genotype-phenotype data were leveraged from the public TP53 database (germline dataset, n = 3446; https://tp53.isb-cgc.org/) and two independent LFS clinical registries (n = 339). Individual correlations between HLA-I genotyping, TP53 missense variants and phenotypes were investigated in a group of 173 subjects with LFS. Findings Among individuals with frequent TP53 pathogenic variants, PNS was strongly correlated with median age at first cancer (range 18-43 years, R = 0.69, p = 0.0132). Compared to individuals with low PNS (<1) variants, those with high PNS (<1) variants showed delayed median age at first diagnosis (34 years vs. 25 years, p = 0.0009), fewer sarcomas (osteosarcoma [RR 0.29, p = 0.02]; soft-tissue [RR 0.41, p = 0.02]), and more cancer types typically not associated with LFS spectrum [RR 1.61, p = 0.02]. Interpretation MHC-I neoantigenic properties of TP53 variants are associated with differences in cancer risk and spectrum in individuals with pathogenic TP53 variants, suggesting that individual variant-specific immune response could contribute to the heterogenous presentation of LFS
Propriétés Typestates avec Frama-C
No full textInternational audienceNous présentons dans cet article le greffon Typestates de la plate-forme d'analyse de code C Frama-C. Il permet à son utilisateur de spécifier et vérifier des propriétés de type "Typestate". Ces propriétés visent à préciser, pour un objet d'un certain type de données, quelles opérations peuvent s'appliquer à lui en fonction de son état courant. Pour cela, le greffon introduit une extension d'ACSL, le langage de spécification standard de Frama-C, et instrumente le programme original avec des annotations ACSL classiques, afin d'utiliser les analyseurs Frama-C habituels pour la vérification
A wafer-scale method for the characterization of 2D MoS2 layers
No full textInternational audienceWafer-scale deposition of 2D TMDs (Transition Metal Dichalcogenides) is a key point for their integration in future devices. While significant efforts have been dedicated to improving the quality and uniformity of 2D materials, their implementation requires a robust characterization protocol to assess the surface coverage, layer number, stoichiometry, homogeneity, crystallinity and morphology. In this work, we developed a characterization protocol that combined local analyses and large-scale methods. This protocol was applied to MoS2 films grown on SiO2 substrate by Atomic Layer Deposition (ALD) using two different precursors, enabling the determination of the number of ALD cycles required to achieve a strict monolayer with full wafer-scale coverage. Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), and Scanning Transmission Electron Microscopy (STEM) provided insights into composition, surface coverage and equivalent thickness from sub-monolayer to above-monolayer thickness range at low scale. The combination of Wavelength-Dispersive X-ray Fluorescence (WDXRF), Scanning Electron Microscopy (SEM), Raman spectroscopy and Photoluminescence, enables a rapid and accurate evaluation of the uniformity at wafer scale, the equivalent thickness and composition of TMD films across the wafer
Transient Large-Scale Anisotropy in TeV Cosmic Rays due to an Interplanetary Coronal Mass Ejection
No full textInternational audienceLarge- or medium-scale cosmic ray anisotropy at TeV energies has not previously been confirmed to vary with time. Transient anisotropy changes have been observed below 150 GeV, especially near the passage of an interplanetary shock and coronal mass ejection containing a magnetic flux rope ejected by a solar storm, which can trigger a geomagnetic storm with practical consequences. In such events, cosmic rays provide remote sensing of the magnetic field properties. Here we report the observation of transient large-scale anisotropy in TeV cosmic ray ions using data from the Large High Altitude Air Shower Observatory (LHAASO). We analyze hourly skymaps of the transient cosmic ray intensity excess or deficit, the gradient of which indicates the direction and magnitude of transient large-scale anisotropy across the field of view. We observe enhanced anisotropy above typical hourly fluctuations with 5 significance during some hours of November 4, 2021, in separate data sets for four primary cosmic ray energy ranges of median energy from =0.7 to 3.1 TeV. The gradient varies with energy as , where . At a median energy 1.0 TeV, this gradient corresponds to a dipole anisotropy of at least 1%, or possibly a weaker anisotropy of higher order. This new type of observation opens the opportunity to study interplanetary magnetic structures using air shower arrays around the world, complementing existing in situ and remote measurements of plasma properties
WHITENING SPHERICAL GAUSSIAN MIXTURES IN THE LARGE-DIMENSIONAL REGIME
No full textAccepted for publication at ICASSP 2026Whitening is a classical technique in unsupervised learning that can facilitate estimation tasks by standardizing data. An important application is the estimation of latent variable models via the decomposition of tensors built from high-order moments. In particular, whitening orthogonalizes the means of a spherical Gaussian mixture model (GMM), thereby making the corresponding moment tensor orthogonally decomposable, hence easier to decompose. However, in the large-dimensional regime (LDR) where data are high-dimensional and scarce, the standard whitening matrix built from the sample covariance becomes ineffective because the latter is spectrally distorted. Consequently, whitened means of a spherical GMM are no longer orthogonal. Using random matrix theory, we derive exact limits for their dot products, which are generally nonzero in the LDR. As our main contribution, we then construct a corrected whitening matrix that restores asymptotic orthogonality, allowing for performance gains in spherical GMM estimation
A Rahman Syndrome mutation in histone H1.4 disrupts chromatin compaction and phase separation
No full textRahman syndrome (RS) is a rare developmental disorder caused by frameshift mutations in linker histone H1.4 that produce a truncated C-terminal domain (CTD) with reduced positive charge. We investigated the effects of an RS-associated mutation on chromatin structure and dynamics, focusing on H1.4-bound nucleosomes and hexanucleosomal arrays. We report that the RS mutation induces a more extended and flexible array conformation, characterized by enhanced linker DNA accessibility and an inability to form compact, regularly stacked nucleosome structures. Notably, mutant H1.4-bound arrays show a reduced capacity to undergo liquid-liquid and liquid-solid phase separation, closely resembling linker histone-free arrays. Molecular dynamics simulations corroborated by FRET analysis indicate that the mutated CTD interacts with a shorter linker DNA segment, resulting in a more open nucleosome conformation. Consistent with these structural changes, the RS mutation significantly enhances H1.4 mobility within cell nuclei, reflecting a weaker chromatin association. The combined data suggest that RS mutations promote an aberrantly relaxed chromatin state, potentially leading to the dysregulation of gene expression that may drive RS pathology. These findings underscore the essential role of the CTD in chromatin compaction and provide mechanistic insights into the molecular etiology of RS
Search for a boosted Higgs boson decaying to bottom quark pairs in association with a W or Z boson in proton-proton collisions at = 13 TeV
No full textInternational audienceA search is conducted for standard model Higgs bosons with large transverse momentum () decaying to bottom quark pairs and produced in association with a hadronically decaying W or Z boson at the LHC. The result is based on a dataset of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector in 20162018, corresponding to an integrated luminosity of 138 fb. Boosted Higgs, W, and Z boson decays are reconstructed using large-radius jets with 450 GeV and identified with heavy-flavor classifiers based on a graph convolutional neural network. The observed signal strength relative to the standard model expectation is = 0.7 including statistical and systematic uncertainties
Prussian blue functionalized MIL-101(Cr)-SO3H for Cs+ ion capture for the management of contaminated water
No full textInternational audienceThis study investigates the property of Metal-Organic Frameworks (MOFs) grafted with Prussian blue analogs (PBA) for the efficient removal of Cs+ ions from aqueous solutions. MIL-101(Cr)-SO3H-PBA material was synthesized using a two-step process: hydrothermal reaction between monosodium 2-sulfoterephthalic acid (BDC-SO3Na) and chromium oxide (CrO3) to produce MIL-101(Cr)-SO3H, followed by grafting with CuK2[Fe(CN)6] (PBA). Both materials were characterized using XRD, IR, N2 sorption and Raman spectroscopy. The results confirmed the conservation of MOF porosity after functionalization and the successful incorporation of PBA. Batch adsorption experiments were conducted to evaluate Cs+ removal performance of the adsorbents. The study examined contact time (up to 1440 min), pH (2, 7 and 11), initial Cs+ concentration (from 9 ppb to 1800 ppm) and competing ions. The resistance of the porous solids under drastic conditions involving gamma radiation (from 0.5 MGy up to10 MGy) was also investigated.MIL-101(Cr)-SO3H-PBA exhibited a maximum Cs⁺ adsorption capacity of 242 mg.gMOF-1, compared to 161 mg.gMOF-1 for pristine MIL-101(Cr)-SO3H and showed high selectivity toward Cs+ in the presence of competing ions (Na+, K+, Mg2+, Ca2+, Sr2+). MI-101(Cr)-SO3H-PBA also demonstrates remarkable stability under radiation and alkaline conditions, maintaining 95% efficiency, whereas the performance of pristine MIL-101(Cr)-SO3H material decreased significantly (7.5-fold decrease).Cette étude examine les propriétés des structures métal-organiques (MOF) greffées avec des analogues du bleu de Prusse (PBA) pour l'élimination efficace des ions Cs+ des solutions aqueuses. Le matériau MIL-101(Cr)-SO3H-PBA a été synthétisé selon un procédé en deux étapes : réaction hydrothermale entre l'acide 2-sulfotéréphtalique monosodique (BDC-SO3Na) et l'oxyde de chrome (CrO3) pour produire du MIL-101(Cr)-SO3H, suivie d'un greffage avec du CuK2[Fe(CN)6] (PBA). Les deux matériaux ont été caractérisés par DRX, IR, sorption de N2 et spectroscopie Raman. Les résultats ont confirmé la conservation de la porosité des MOF après fonctionnalisation et l'incorporation réussie du PBA. Des expériences d'adsorption par lots ont été menées pour évaluer les performances d'élimination du Cs+ des adsorbants. L'étude a examiné le temps de contact (jusqu'à 1 440 min), le pH (2, 7 et 11), la concentration initiale en Cs+ (de 9 ppb à 1 800 ppm) et les ions concurrents. La résistance des solides poreux à des conditions extrêmes impliquant un rayonnement gamma (de 0,5 MGy à 10 MGy) a également été étudiée.Le MIL-101(Cr)-SO3H-PBA a montré une capacité d'adsorption maximale de Cs+ de 242 mg.gMOF-1, contre 161 mg.gMOF-1 pour le MIL-101(Cr)-SO3H, et a montré une forte sélectivité pour le Cs+ en présence d'ions concurrents (Na+, K+, Mg2+, Ca2+, Sr2+). Le MI-101(Cr)-SO3H-PBA présente également une stabilité remarquable dans des conditions de rayonnement et alcalines, maintenant une efficacité de 95 %, tandis que les performances du matériau MIL-101(Cr)-SO3H ont diminué de manière significative (diminution de 7,5 fois)