HAL-Université de Bretagne Occidentale
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Place de la TEP-FDG dans les rhumatismes inflammatoires chroniques : une revue clinique et imagerie croisée
No full textInternational audienceLa TEP au [18F]FDG est de plus en plus employée comme outil diagnostique et de suivi dans les maladies inflammatoires chroniques, notamment les rhumatismes inflammatoires. Cet article présente une synthèse des principales indications et limites de la TEP dans ce contexte, en s’appuyant sur une session conjointe entre un clinicien et un médecin nucléaire. Chaque entité nosologique (polyarthrite rhumatoïde, spondyloarthrites, rhumatismes microcristallins, pseudo-polyarthrite rhizomélique [PPR]) est abordée sous l’angle de sa présentation clinique, des enjeux diagnostiques et des apports potentiels de l’imagerie TEP. L’analyse met en évidence la valeur ajoutée de la TEP dans la PPR, notamment pour le diagnostic différentiel et la stratification des patients, ainsi que les scores d’interprétation développés récemment. En revanche, les données restent non concluantes pour la PR et SPA et limitées pour les rhumatismes microcristallins. L’article se conclut sur les perspectives offertes par de nouveaux traceurs et une intégration plus fine des données cliniques et d’imagerie
Rôle de la TEP-FDG dans les cancers des voies aérodigestives supérieures : indications cliniques, pièges diagnostiques et perspectives technologiques
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Rapid microbial activity in marine sediments significantly enhances silica cycling rates compared to abiotic processes
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High precision Al-Mg dating of NWA 15118 challenges a primary anorthositic crust on Vesta
No full textInternational audienceA lunar-like magma ocean model has been proposed for the asteroid 4 Vesta, where a global primary anorthositic crust formed from buoyant plagioclase floating above complementary diogenitic cumulates. In this hypothesis, the crystallization of the anorthosite should predate the formation of eucrites that are thought to reflect secondary magmatism at the surface of Vesta. To test this model, we present the first 26 Al-26 Mg age of the anorthosite Northwest Africa (NWA) 15118. The NWA 15118 yields a model 26 Al-26 Mg age younger than 4.35 ± 0.03 Myr after CAIs formation. However, eucritic crust formation initiated at ∼2.88 Myr after CAIs, and predating NWA 15118 by over 1.5 Myr, contradicting the proposed global primary anorthositic crust of Vesta formed from a magma ocean. Instead, anorthosite NWA 15118 more plausibly represents a fragment of regional crust formed after the primary crustal differentiation of Vesta, potentially related to late stage basaltic eucrites with negative Eu anomalies or derived from a chemically distinct source
La Tisseuse d’Histoires : From Virtual Reality to Collective Improvisation
No full textAt the crossroads of theater, cinema, and virtual reality, our research-creation investigates ourbodily relationship with digital spaces and the imaginaries that emerge from them. We explore howthese technologies foster new shared narratives, interactive social dynamics, and dialogues betweencreators and audiences. Our performance [1] consists of segments lasting about 10 minutes, wherestories [2] unfold through different roles:• The Puppeteer stages the story using a VR puppet theater, animating characters and objectsin a 3D setting.• The Switcher selects and shapes the narrative by choosing story fragments via a tablet.• The Narrator brings the story to life by reading or adapting the unfolding text.• The Musician enriches the experience with improvised music and sound effects.While each role influences what the audience sees, the experience primarily fosters listening andcollaboration, ensuring that each combination results in a unique performance, reaching Dixon'sfourth level of interactivity [3]. A secondary spectacle emerges—the scenic device itself—whereparticipants of all ages and backgrounds break free [4] through play and cooperation, if only for theduration of a story. For TMD2025, we will present our creative process and address key questions oninteractivity, immersion, and the theatricality of digital storytelling
Le Teatre de la Carrièra et la question du féminisme
No full textInternational audienceDans une perspective historique qui suit la vie de la troupe, je propose d’analyser l’évolution de la place et de l’image de la femme dans le Teatre de la Carrièra qui a marqué la fin du vingtième siècle par une aventure d’un genre et d’une ampleur inédits. J’interroge notamment la place des femmes dans la troupe ainsi que les images véhiculées par les textes et la mise en scène. Je porte également un regard particulier sur quelques figures marquantes de comédiennes, parfois autrices des textes
Engagement and Disclosures in LLM-Powered Cognitive Behavioral Therapy Exercises: A Factorial Design Comparing the Influence of a Robot vs. Chatbot Over Time
No full textInternational audienceMany researchers are working to address the worldwide mental health crisis by developing therapeutic technologies that increase the accessibility of care, including leveraging large language model (LLM) capabilities in chatbots and socially assistive robots (SARs) used for therapeutic applications. Yet, the effects of these technologies over time remain unexplored. In this study, we use a factorial design to assess the impact of embodiment and time spent engaging in therapeutic exercises on participant disclosures. We assessed transcripts gathered from a two-week study in which 26 university student participants completed daily interactive Cognitive Behavioral Therapy (CBT) exercises in their residences using either an LLM-powered SAR or a disembodied chatbot. We evaluated the levels of active engagement and high intimacy of their disclosures (opinions, judgments, and emotions) during each session and over time. Our findings show significant interactions between time and embodiment for both outcome measures: participant engagement and intimacy increased over time in the physical robot condition, while both measures decreased in the chatbot condition
Quand le client travaille pour consommer : le contrat psychologique du client en contexte de coproduction
No full textInternational audienceDans un contexte où les dispositifs de coproduction se généralisent, les clients sont fréquemment engagés dans la réalisation d’un travail d’exécution dirigé par l’entreprise. Cet article explore le contrat psychologique du client lorsqu’il réalise ce travail d’autoproduction dirigée. Fondés sur des observations et des entretiens, les résultats révèlent la nature et le rôle des promesses de l’entreprise perçues par le client et les contreparties consenties par ce dernier sur la perception de l’équité de la relation de coproduction et in fine son acceptabilité
Étude numérique et expérimentale du cisaillement d’un acier doux en grandes déformation : anisotropie, effet d'histoire et effet de la vitesse de déformation
No full textWhile the propulsion mode of automobiles seems to be shifting from internal combustion to electric power, the manufacturing method for the vehicle body is still mainly based on the assembly of sheet metal formed by plastic deformation. Increased knowledge of the behavior of the sheet materials can help, through numerical forming and crash simulations, to optimize the quantity of material to be used for the vehicle body.To expand the database of experimental data on material behavior, 2 complementary experimental set-ups involving large shear strains have been developed.The first device is based on the in-plane torsion test, which enables shear kinematic to be applied under quasi- static and dynamic conditions. This test also enables all material directions to be loaded simultaneously, providing direct access to the material's anisotropy across the entire surface of the metal sheet.The second device is based on the simple shear test: 2 translating jaws and a rectangular specimen. The innovative idea is to sequentially machine the free edges of the rectangular specimen, where the limitations of the simple shear test are concentrated. The central zone of the specimen can therefore achieve large strains under simple shear kinematic, keeping the simple shear test’s simplicity and straightforward analysis.Linear load paths are useful for determining damage accumulation laws. However, during forming and further impact, a material element undergoes complex loading paths. To investigate the performance of the various damage indicators proposed in the literature, an experimental campaign was carried out up to fracture for differentcombinations of 2 proportional paths.Alors que la propulsion automobile évolue du thermique vers l'électrique, le procédé de fabrication de la caisse du véhicule repose toujours sur l’assemblage de tôles mises en forme par déformations plastiques. Une connaissance accrue du comportement de ces matériaux permet, grâce aux simulations numériques de mise en forme et de crash, d’optimiser la quantité de matière utilisée pour la réalisation de la structure.Afin d’élargir la base de données expérimentales sur ces matériaux, deux dispositifs expérimentaux complémentaires appliquant des sollicitations de cisaillement en grandes déformations sont présentés.Le premier repose sur l’essai de torsion plane, permettant d’appliquer un cisaillement dans des conditions quasi- statiques et dynamiques. Cet essai sollicite toutes les directions du matériau simultanément, permettant un accès direct à l’anisotropie du matériau dans le plan de la tôle métallique.Le second dispositif est basé sur l’essai de cisaillement simple : 2 mors en translation et une éprouvette rectangulaire. Cet essai est limité par des phénomènes locaux aux bords libres. L’innovation consiste à re-usiner ces bords de manière séquentielle, permettant ainsi d’atteindre de grandes déformations tout en conservant la simplicité de l’essai.Les trajets de chargements linéaires sont essentiels pour la calibration de modèles de cumul d’endommagement. Cependant, lors d’une phase de mise en forme ou d’un impact, le matériau subit des trajets complexes. Afin de qualifier les modèles de cumul d’endommagement proposés dans la littérature, une campagne expérimentale dedétermination de la déchirure pour différentes combinaisons de 2 trajets proportionnels a été réalisée
Assessing Local Inductive Bias in Deep Learning-Based Three-Gamma Event Classification
No full textInternational audienceThe XENON Medical Imaging System (XEMIS) project aims to develop the first liquid xenon (LXe) Compton camera for functional three-gamma medical imaging. A critical challenge is accurately classifying events based on the number of interacting gamma rays, which is essential for dedicated data treatment and image reconstruction techniques. Traditional methods, such as energy cuts or spatial clustering, are limited in handling the complex, high-dimensional data, noise, and overlapping interactions from monolithic detectors like XEMIS2. To address these limitations, we investigated deep learning methods for event classification. We compared two architectures: a permutation-invariant PointNet model and sparse convolutional tensor networks (STN), implemented using the Minkowski Engine. Both models process unstructured raw spatial and light detection data derived from Geant4 simulations of XEMIS2, specifically using the number of photoelectrons measured by each of the 64 photomultiplier as input. Our objective was to differentiate between events originating from single-, double-, and triple-gamma interactions. We reported classification performance results. While overall accuracy was comparable between the architectures (75.5% for PointNet vs. 76.8% for MinkowskiNet), sparse convolutional networks consistently showed improvements in class-wise discrimination. Notably, the class benefited from significantly higher precision (81.3% vs. 76.4%) when using MinkowskiNet. This improved separation for the class was observed across different model variants, suggesting that the local inductive bias incorporated by sparse convolutions aids in disentangling the complex spatial features of the class. These findings offer insights into the feasibility and performance of STNs for handling the complex data typical of XEMIS2