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Tectonic underplating at intermediate depths in subduction zones: structural and geochronological evidence preserved in Corsican ophiolites
No full textInternational audiencePeridotites from two ophiolitic units of Alpine Corsica show outcrop-scale reverse faults whose dip angles follow a bimodal distribution (weak vs. steep angles). These faults are outlined by pseudotachylyte or cataclasite, and formed concurrently at 35–70 km depths, during the subduction of the Piemonte-Ligurian oceanic lithosphere beneath Apulia in Cretaceous to Eocene times. 40Ar/39Ar dating of pseudotachylyte indicates a 38.1 Ma age of formation. The faults are interpreted as reflecting, at the outcrop-scale, similar structures formed during the propagation, along the subduction interface, of map-scale flats and ramps delimiting duplex-like thrust sheets eventually incorporated by underplating to the upper plate
Apprentissage machine en optique non-linéaire ultrarapide fibrée
No full textNational audienceLa combinaison des effets non linéaires et dispersifs en photonique guidée génèrent des dynamiques spectro-temporelles aussi riches que complexes. Les techniques d'apprentissage-machine offrent désormais de nouvelles perspectives pour en tirer le meilleur parti [1]. Nous présenterons ainsi plusieurs approches que nous avons déployées dans le cadre de la photonique ultrarapide fibrée.Un premier outil concerne l'optimisation expérimentale des systèmes photoniques ultrarapides. Les algorithmes évolutionnaires, notamment les algorithmes génétiques, sont en effet très bien adaptés aux expériences exigeantes comme l'étude de nouveaux régimes de fonctionnement dans les cavités fibrées : émission de solitons à respiration verrouillés en fréquence [2], d'impulsions bruitées ou bien encore de super vagues scélérates.Une autre approche est l'implication de réseaux neuronaux. Ils sont capables, après entraînement, de prédire avec précision les profils temporels et spectraux, se substituant efficacement à des méthodes numériques plus lourdes. Des résultats convaincants ont ainsi pu être démontrés dans l'étude de la propagation d'impulsions isolées, dans la génération de supercontinua ou bien de peignes de fréquence. Plus de trois ordres de grandeurs en temps de calcul peuvent être gagnés et ils sont aussi efficaces pour résoudre des problèmes inverses [3].Enfin, l'apprentissage-machine améliore la compréhension des dynamiques non linéaires : classification, décomposition en modes dynamiques, approche de l'équilibre dominant guidée par les données [4], ou méthodes comme SINDy [5] permettent d'extraire des modèles physiques pertinents à partir de données.L'ensemble de ces approches révolutionnent la photonique non linéaire, ouvrant la voie à l'exploration d'espaces de paramètres étendus, à la résolution efficace de problèmes inverses, et à une interprétation physique enrichie. [1] G. Genty et al, Nat. Photon., 15 (2021) 91-101.[2] X. Wu et al, Nat. Commun., 13 (2022) 5784.[3] S. Boscolo et al, Opt. Commun., 542 (2023) 129563.[4] A.V. Ermolaev et al, Sci. Rep., 13 (2023) 10462.[5] A.V. Ermolaev et al, Sci. Rep., 12 (2022) 12711
Choix de professions d'anciens enfants placés : Dégagement, réparation ou symbolisation ?
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Cascade screening in familial hypercholesterolaemia is associated with earlier statin initiation and fewer cardiovascular events than opportunistic screening
No full textInternational audienceAims: The aim of this study is to assess whether the family cascade screening strategy for identifying patients with heterozygous familial hypercholesterolaemia (HeFH) is associated with a reduction in cardiovascular events compared with opportunistic screening strategies.Methods and results: We retrospectively included 3232 patients, from the French FH registry, REFERCHOL, with a molecular diagnosis. We compared patients according to their screening strategy for HeFH: index cases (opportunistic screening) and cascade screening cases (patients diagnosed by cascade screening) on clinical and biological characteristics. We first compared patients according to screening modality using χ² and Student’s t-tests and performed multivariate logistic regression to assess the association between screening strategy and the risk of cardiovascular events. We finally performed the same tests in an age- and sex-matched subpopulation. Compared with index cases (2106 patients), cascade screening cases (1126 patients) started statin use 14 years earlier [18.1 (interquartile range 12.5–29.1) years vs. 31.8 (19.7–42.4) years, P < 0.001] and 8.3% had a cardiovascular event prior to the first visit, vs. 26.5% in the index cases group (P < 0.001). In multivariate logistic regression, the cascade screening was independently associated with 51% less atherosclerotic cardiovascular disease (ASCVD) than the opportunistic screening. Age at statin initiation was also associated with ASCVD, with a higher adjusted odd ratio for higher age categories. In an age- and sex-matched analysis, cascade screening was no longer associated with ASCVD, but age at statin initiation remained.Conclusion The cascade screening strategy for familial hypercholesterolaemia is associated with 51% fewer cardiovascular events in genetically confirmed heFH probably due to an earlier age at treatment initiation
NM-USNet: A novel generative model for parathyroid glands detection in nuclear medicine
No full textInternational audienceRecent advances in Generative Artificial Intelligence (GAI) have revolutionized various fields, notably medical imaging. In the context of Parathyroid Glands detection in Nuclear Medicine, physicians rely on a subtraction process involving two different images. Consequently, the subtracted image depends entirely on the two images. This methodology is manual, time-consuming, and depends entirely on medical expertise. Conditional GAI, a sub-field of GAI, generates new data based on input specifications, enabling more controlled results. However, generative models require a large amount of data and still present limitations in precisely controlling outputs over inputs. This paper presents a new model named Nuclear Medicine U-Net Siamese Network (NM-USNet) based on a combination of U-Net and Siamese networks. The U-Net takes two input images and generates one, while the Siamese network distinguishes between the generated and the reference images. The proposed methodology achieves a mean correlation of 0.956 compared to reference images, showing its potential as a reliable medical tool to assist physicians in the detection of parathyroid glands. This advancement not only improves the accuracy of diagnosis, but also represents a significant step forward in integrating GAI into medical practice. The proposed approach gives high results despite the limited data size
Generation of broadband THz radiation by polariton parametric scattering in a LiNbO3 waveguide
No full textInternational audiencePolariton scattering from the lowest A1-symmetry TO vibrational mode in lithium niobate presents a promising approach for generating THz radiations. Nevertheless, a notable challenge hindering this technique is the generation of frequencies exceeding 2 THz, primarily attributed to the gain spectrum of Lithium Niobate centered at 2 THz and the substantial absorption coefficient at higher frequencies. Although THz output beyond this frequency has been intermittently observed in THz generators utilizing stimulated polariton scattering, the generation of higher frequency outputs remains largely unexplored. In this study, we report a direct measurement of a broadband THz field with a bandwidth of approximately 4 THz centered at 3.1 THz. This electric field is generated from ultra-short 1 µm wavelength pump pulses focused in a waveguide made of LiNbO3. The theoretical phonon-polariton dispersion curve, calculated parametric gain, and the measured signal spectrum generated in the near-infrared confirm the THz field emission obtained from an electro-optic detection
local exact controllability of some one-dimensional bilinear Schrödinger equations
No full textThe local exact controllability of the one-dimensional bilinear Schrödinger equation with Dirichlet boundary conditions has been extensively studied in subspaces of H 3 since the seminal work of K. Beauchard. Our first objective is to revisit this result and establish the controllability in H 1 0 for suitable discontinuous control potentials. In the second part, we consider the equation in the presence of periodic boundary conditions and a constant magnetic field. We prove the local exact controllability of periodic H 1 -states, thanks to a Zeeman-type effect induced by the magnetic field which decouples the resonant spectrum. Finally, we discuss open problems and partial results for the Neumann case and the harmonic oscillator.</div
Sommet du Mont d'Or, Sondages archéologiques: PCR occupation et exploitation de la haute vallée du Doubs ans la longue duréeVolume II axe II Occupation d'altitude durant la Protohistoire
No full textLa nécropole tumulaire de Briod-Conliège (Jura), présentation d'un projet de recherches
No full textInternational audienceUn projet de recherches en cours a pour but de créer un inventaire complet, détaillé et à jour de la zone tumulaire de Briod-Conliège (Jura) méconnue et pourtant d’intérêt majeur compte tenu des éléments de prestiges importés qu’elle comporte. Situé sur le Premier plateau du Jura externe, dans le sud de la Franche-Comté dans le Jura. La reculée de Conliège est un passage naturel entre la plaine de Lons-le-Saunier et le Premier plateau. Point de passage entre la vallée du Doubs et la vallée du Rhin, des interactions et des échanges ont caractérisé ce territoire à la Protohistoire notamment. Les sources salées deLons-le-Saunier et de Montmorot situées à 6 kilomètres de cette zone de Conliège ont eu dès cette période un rôle important dans l’implantation humaine de cette zone au cœur des échanges entre le massif jurassien/alpin et la plaine de la Saône. Afin de circonscrire l’occupation tumulaire, nous avons fait le choix de trois objectifs principaux :- un inventaire précis des tumuli présents dans une zone circonscrite autour de la nécropole des Monceaux par le biais d’une prospection pédestre réalisée en 2023 et des données Lidar. - une recherche documentaire pour une reprise de l’ensemble des données anciennes retravaillées à l’aune des récentes avancées sur le sujet (analyse chronologique, architecture des monuments, évolution de la nécropole…).- des prospections géophysiques- un plan pluriannuel de fouilles programméesCette reprise s’avère prometteuse en perspectives scientifiques d’autant qu’elle se complète d’éléments comme ceux d’une vaisselle importée et rare, une amphore étrusque et son simpulum. Cette nécropole apparaît en effet comme un témoin privilégié des échanges opérés entre l’Étrurie via le Tessin et la Bourgogne/Franche-Comté et se trouve ainsi au cœur d’une problématique rarement renouvelée du fait du caractère exceptionnel des découvertes de ce type, celle des circuits « commerciaux » considérés ces dernières années avec les récents travaux de la tombe princière de Lavau dans l’Aube et son abondant mobilier importé
Facile preparation and crystallographic characterization of a new zero-dimensional antimony (III)-based organic-inorganic material with white light emission properties
No full textInternational audienceZero-dimensional materials based on antimony(III) chloride have attracted considerable attention as broadband emitters. These 0D compounds exhibit structural adaptability, adopting either octahedral or square-pyramidal geometries, which significantly influence their emissive properties. In this context, a novel organic-inorganic hybrid material, (Qx-H)₄Sb₂Cl₁₀ (Qx-H⁺: quinoxalinium), was synthesized and thoroughly characterized using X-ray diffraction at 100 K, Hirshfeld surface analysis, vibrational spectroscopy, and optical studies. The compound crystallizes in the triclinic P space group, and its crystal structure reveals unusual Sb···Cl interactions in the solid state, leading to the conversion of individual [SbCl₅]²⁻ polyhedra into discrete binuclear [Sb₂Cl₁₀]⁴⁻ units. The three-dimensional (3D) supramolecular framework of (Qx-H)₄Sb₂Cl₁₀ is stabilized by multiple secondary interactions, including N–H···Cl hydrogen bonds and π···π stacking interactions. Additionally, 2D fingerprint plots and Hirshfeld surface analyses were employed to identify the key intermolecular interactions governing the crystal packing. A vibrational analysis was carried out using Raman and infrared spectroscopy. The optical properties were investigated by UV–Visible spectroscopy, revealing a band gap of 3.99 eV. Density Functional Theory (DFT) calculations at the CAM-B3LYP/Lanl2dz level were performed to gain theoretical insights into the electronic structure, particularly the absorption spectrum and the HOMO–LUMO gap. Furthermore, the nonlinear optical (NLO) properties were examined to evaluate the dipole moment, linear polarizability, and second hyperpolarizability. Notably, the compound exhibits significant white light emission upon excitation at 375 nm. The correlated color temperature (CCT) was measured at 6623 K, indicative of a "cool" white light emission