HAL Université de Toulouse, et Toulouse INP
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Quantum confinement effects in the topological Dirac semimetal α-Sn on InSb(111)
No full textInternational audienc
TFEB triggers a matrix degradation and invasion program in triple-negative breast cancer cells upon mTORC1 repression
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Methodological concerns and clinical relevance: a critical appraisal of the meta-analysis on biosimilars versus originator follitropin alfa in ART
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Modélisation de l’interaction arc-cathode dans le cas des cathodes en matériau non-réfractaire
No full textInternational audienceLa modélisation des phénomènes relatifs à l'interaction des arcs électriques avec les électrodes permet d'une part de compléter les modèles magnétohydrodynamiques usuellementutilisés pour représenter la colonne, en fournissant des conditions aux limites utiles, et d'autre part d'étudier le chauffage et l'usure de ces électrodes. Cette modélisation est complexe en raison du grand nombre de phénomènes à prendre en compte et des écarts à l'équilibre thermodynamique local dus aux petites distances mises en jeu. Un enjeu important est donc de comprendre comment ces déséquilibres structurent la zone proche électrode, en particulier dans le cas peu étudié d'une cathode non réfractaire. Cet article présente, en s'appuyant sur la littérature, une méthodologie pour évaluer les distances caractéristiques d'apparition des déséquilibres thermique, chimique (ionisation), et de séparation de charges. Cette méthodologie est validée sur le cas bien connu du plasma d'argon sous 1 bar (existant par exemple devant une cathode réfractaire), puis est appliquée à un plasma de cuivre sous forte pression (28 bars) issu de la vaporisation d'une cathode en cuivre (non réfractaire) soumise à un arc. Les résultats de l'étude réalisée confirment les structures de zone cathodique établies par Benilov, et en particulier la présence d'ionisation dans la gaine associée à la cathode en cuivre. Un modèle auto-cohérent de zone cathodique prenant en compte ces phénomènes est ensuite présenté et appliqué au calcul d'une structure à N spots cathodiques stationnaires et indépendants. Dans le cas d'un arc s'accrochant sur la cathode creuse (en cuivre) d'une torche à plasma de forte puissance, de bons ordres de grandeur sont obtenus pour la tension de gaine et le taux d'usure par vaporisation. Pour conclure, des perspectives d'étude sur ce sujet sont proposées.</div
Phase retrieval using the Hessian operator
No full textInternational audiencePhase retrieval is a fundamental problem in optics, particularly in ptychography, where reconstructing an unknown wavefield from intensity-only measurements poses significant computational challenges. In this work, we introduce a novel phase retrieval method using the bilinear Hessian and Hessian operator to improve optimization efficiency. By formulating the problem in a differential calculus framework over linear spaces, we derive gradient and Hessian expressions without explicitly differentiating, enabling efficient second-order based solvers. This enables to implement and analyze conjugate gradient, quasi-Newton, and gradient descent methods with Newton step size, demonstrating a one-order-of-magnitude improvement in convergence speed compared to traditional approaches. Numerical experiments on near-field ptychography data validate the method's robustness and computational efficiency. Our approach significantly reduces reconstruction time, making it highly relevant for real-time imaging applications, such as in-situ experiments
Bayesian Unsupervised Multifractal Image Segmentation using a Multiscale Graph Label Prior
No full textInternational audienceThis paper presents a Bayesian multifractal segmentation method that segments multifractal textures in regions with different multifractal properties. First, a computationally and statistically efficient model for wavelet leaderbased multifractal parameter estimation is developed, assigning wavelet leader coefficients associated with distinct parameters to different image regions. Next, a multiscale graph label prior is introduced to capture spatial and scale correlations among these labels. Gibbs sampling is used to generate samples from the posterior distribution. Numerical experiments on synthetic multifractal images demonstrate the effectiveness of the proposed method, outperforming traditional unsupervised and modern deep learning-based segmentation approaches
Fibrillarin-mediated ribosomal RNA maturation is a novel therapeutic vulnerability in triple-negative breast cancer
No full textInternational audienceBackground Triple-negative breast cancer (TNBC) remains one of the most challenging breast cancer subtypes to treat due to the lack of effective therapeutic options. Ribosome biogenesis has recently emerged as a promising therapeutic target across various cancers. Despite the current targeting of ribosome biogenesis through RNA polymerase I (RNA Pol I) inhibition, we speculated that other factors essential for ribosome assembly, such as ribosomal RNA (rRNA) maturation factors, may also represent therapeutic targets in TNBC.Methods Ribosome biogenesis was evaluated in each breast cancer subtype using expression level of ribosome biogenesis factors from the UCSC XENA database. The sensitivity of TNBC cell to inhibition of ribosome biogenesis was evaluated on the TNBC cell lines MDA-MB-231 and BT-20, either using RNA Pol I inhibitors CX-5461 or BMH-21 or by knocking-down Fibrillarin (FBL) gene using an shRNA approach. Tumor cell growth and survival was monitored both in vitro and as xenografted tumors.Results We demonstrate that ribosome biogenesis-related genes are significantly overexpressed in TNBC compared to other breast cancer subtypes, highlighting its potential role in TNBC progression. Accordingly, we show that RNA Pol I inhibition exerts potent anti-proliferative effects in pre-clinical models of TNBC, both in vitro and in vivo. However, the DNA-damaging activity of RNA Pol I inhibitors raises safety concerns, highlighting the need for alternative strategies to inhibit ribosome biogenesis. To this end, we show that targeting a downstream rRNA maturation step, specifically pre-rRNA cleavage, by inhibiting the maturation factor Fibrillarin, also inhibits tumor growth in TNBC models. Notably, ribosome biogenesis inhibition, through either RNA Pol I or Fibrillarin targeting, induces cell cycle arrest without triggering significant cell death
Suivi de la santé du troupeau ovin allaitant de la mise en lutte à l’agnelage : mise en pratique dans 6 élevages de la région Centre-Ouest
No full textWhile herd health management is considered a promising field in the future of veterinary medicine in France, it remains underdeveloped in meat sheep farming. However, current challenges in livestock farming argue in favor of its expansion. A flock health monitoring protocol was implemented across six meat sheep farms (including both primiparous and multiparous ewes) in the Centre-West region, covering the period from breeding to early lactation, between September 2024 and April 2025. The protocol included various diagnostic tools: body condition scoring (BCS), coproscopy, trace element blood profiling, urine analysis (pH, density), as well as blood concentrations of beta-hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA). Beyond tracking the evolution of these indicators in each monitored flock, the study also aimed to assess the relevance, feasibility, and cost-effectiveness of such a monitoring program.Si la médecine collective en France est un secteur d’avenir dans le monde vétérinaire, elle est peu développée dans les élevages d’ovins allaitants. Pour autant, les enjeux du monde de l’élevage sont en faveur de son développement. Un protocole de suivi de la santé du troupeau couvrant la période s’étalant de la mise en lutte au début de la lactation a été mis en place dans 6 élevages de brebis allaitants (primipares et multipares) de la région Centre-Ouest, entre septembre 2024 et avril 2025. Parmi les examens complémentaires utilisés dans ce suivi on retrouve : les notes d’état corporel (NEC), les coproscopies parasitaires, les profils sanguins en oligo-éléments, les analyses d’urine (pH, densité) ainsi que les concentrations sanguines en bêta-hydroxy-butyrate (BHB) et acides gras non estérifiés (AGNE). En plus d’étudier l’évolution de ces indicateurs dans chaque troupeau suivi, cette étude s’est attachée à évaluer la pertinence, la faisabilité ainsi que la rentabilité d’un tel suivi
Étude de l'accord dans des textes annotés sans consignes précises : le cas de la charge mentale dans des témoignages professionnels
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A molecular census to elucidate the demixing mechanism of membraneless organelles
No full textInternational audienceAbstract Background Cells contain membraneless organelles that have been proposed to form via phase separation involving dense networks of multivalent intermolecular interactions. As it is notoriously difficult to experimentally distinguish punctate structures formed by phase separation from those formed by other mechanisms, this issue is controversial. To complement experimental assays, we present a computational by-the-numbers approach to phase separation. We mine publicly available datasets to perform a molecular census of prominent subnuclear organelles in mouse embryonic stem cells: nucleoli, transcriptional condensates, heterochromatin foci, and Polycomb bodies. We estimate copy numbers and intermolecular distances and compare the latter to the Debye length, which is the characteristic distance over which intermolecular interactions typically occur. Results We find that none of the organelles studied here contain any protein species that shows intermolecular distances below the estimated Debye length if molecules in the organelles are randomly distributed, which disfavors the classical one-component phase separation scenario. Considering multiple species based on databases of phase-separating proteins, we find that nucleoli and transcriptional condensates are compatible with multi-component phase separation driven by proteins and RNAs, while heterochromatin foci and Polycomb bodies are better explained by a model in which proteins bind to chromatin without phase-separating via dense multivalent interaction networks. We also provide an interactive tool that allows testing of alternative multi-component scenarios. Conclusion We introduce a computational by-the-numbers approach to benchmark different demixing models that may explain the assembly of membraneless organelles. Our results suggest that cells use different mechanisms to form subnuclear organelles with different biophysical properties