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Acceleration of implicit schemes for large systems of delay differential equations
No full textInternational audienceThe objective is to accelerate numerical implicit schemes for solving large linear or nonlinear delay differential equations. These schemes require solving large linear or nonlinear systems at each integration step, making effective initial guesses critical for rapid convergence. For nonlinear problems, an inexact Newton method is used, whose efficiency depends heavily on the quality of these initial guesses. To generate them, line search or trust-region algorithms are employed -each involving the solution of large linear systems. These linear systems are solved using a Krylov subspace method. Initial guesses are constructed via a Petrov-Galerkin process applied to low-dimensional approximation subspaces derived from previous steps. Error estimates are provided, linking the accuracy of the initial guesses to the timestep size, the scheme's order, and the subspace dimension. Numerical experiments show speedups of up to two orders of magnitude over standard predictor-based methods, when those converge
Contrastive learning and physics oriented evaluation for advanced segmentation in electron tomography
No full textInternational audienceDeep learning methods are now achieving strong results for segmentation tasks, and the standard metric for evaluating methods is the Intersection over Union (IOU). However, we show in this paper that IOU is not efficient in evaluating the quality of segmentation for electron tomography (ET) images of zeolites. We perform a physics-oriented evaluation to ensure that the segmentation results yield coherent physical measures. We also formalize Mixed Supervised / Self-Supervised Contrastive Learning Segmentation (M3S-CLS), a semi-supervised approach using a contrastive learning approach that uses expert annotations to train the neural network model. A detailed comparison of this method with a standard cross-entropy-based model is provided. In addition, we publish a database of five fully segmented ET volumes along with corresponding baseline results. The code and the database is available at http://gitlab.univ-st-etienne.fr/labhc-iscv/M3S-CLS
Digital 3D Technologies for Preserving and Transmitting Cultural heritage and Historical Memories
No full textInternational audienceIn an era marked by both environmental transformations and the resurgence of conflicts, the preservation of cultural and historical memory faces unprecedented challenges. Whether submerged by dam reservoirs or obscured by the passage of time, landscapes and cultural heritages risk fading from collective memory. Yet, these elements are crucial for educating current and future generations about the impacts of human activity or conflict on local populations. This communication explores how 3D digital technologies, particularly 3D Geographic Information Systems (GIS) and geovisualization, can restore these threatened memories and make them accessible to a broad audience. Using two case studies, we will demonstrate the potential of these tools to reconstruct, archive, and disseminate lost or endangered heritage.First, we will examine the Gorges de la Loire valley in France, where the construction of reservoir dams submerged landscapes and cultural sites . By combining 3D GIS with historical databases, we created a "backup copy" of the flooded valley, enabling local populations to re-appropriate their submerged heritage. This approach not only preserves the memory of lost landscapes but also provides a model for safeguarding other sites threatened by environmental changes.Second, we turn to Saint-Étienne during World War II, where events and local community memories risk being forgotten . Here, 3D GIS and virtual reality tools were used to archive and visualize the city’s wartime experiences, from resistance, occupation and collaboration acts to bombed neighborhoods.By integrating maps, 3D models, and immersive videos, we developed a multidimensional archive that engages diverse audiences – from researchers to students and local inhabitants – in exploring the past.Our methodology highlights three key contributions:1.Technological Innovation: The use of 3D GIS and geovisualization to create dynamic, interactive representations of lost or threatened heritage.2.Cultural Preservation: The development of digital archives that serve as memory backups.3.Public Engagement: The adaptation of these tools for educational and commemorative purposes, fostering a deeper understanding of historical and environmental impacts
Effect of 12 weeks with a 30-min nap opportunity during the night shift of healthcare workers on early cardiovascular risk biomarkers: the NAPWORK study protocol of a randomised controlled trial
No full textInternational audienceBackground Night shift work is well known to cause health disruption in the short and long term. Among healthcare workers, sleep deprivation is a common concern with many nurses reporting sleep of <6 hour per 24-hour period. Consequences of this chronic sleep restriction have been associated with long-term health issues such as endothelial dysfunction, which plays a key role in the development of cardiovascular diseases, arterial hypertension and type 2 diabetes. While countermeasures such as nap at work have been suggested to mitigate these deleterious effects, the impact of such intervention on endothelial function remains unclear. Therefore, the aim of the present study will be to investigate the effect of a 30 min nap opportunity during night shift work on endothelial function in healthcare workers working in 12hour shifts. Methods and analysis A 12-week randomised controlled trial will be performed with two conditions: (1) a 30 min nap opportunity during night shift work in a dedicated quiet room with a bed and (2) a control condition including a 30 min rest period in a break room. A total of 80 nurses and assistant nurses from interventional care units working a 2×12 hour shift schedule will be recruited. The main outcome will be endothelial dysfunction assessed through the reactive hyperaemia index using the EndoPAT device. Secondary outcomes will include other cardiovascular risk biomarkers, including arterial stiffness (pulse wave velocity), blood pressure, heart rate variability, proinflammatory blood parameters, self-reported fatigue, recovery needs, sleep quality and sleepiness, which will be assessed using validated questionnaires. Our study will address whether napping on the night shift can decrease cardiovascular risk through early cardiovascular biomarkers, including endothelial function, arterial stiffness and heart rate variability. If effective, such interventions could contribute to the development of more sustainable and health-conscious shift work practices, benefiting both workers and the organisations that employ them.The study protocol is in accordance with ethical principles established by the 18th World Medical Assembly (Helsinki 1964) and received approval from an institutional review board ‘comité de protection des personnes EST III’ (23CH138). Written informed consent will be obtained from all participants. Trial registration number NCT05955729; ClinicalTrials.gov 2023-A01109-36 Registered on 21 July 2023
Visualisation et amélioration de la force : vers un renforcement de la liaison cerveau-muscles chez l'athlète
No full textInternational audienceMotor imagery (MI), the mental representation of an action without intention to physical execution, activates neural networks largely overlapping with those involved in actual motor performance. While MI has long been used as an adjunct to physical training, its potential to induce corticomotor plasticity and optimize elite performance remains insufficiently understood. Bridging fundamental neuroscience and applied sport science, we investigated how MI reshapes perception-action coupling and supports force enhancement, inter-skill transfer, and neuromuscular efficiency in high-level athletes. Our findings demonstrate that MI can induce measurable cortic:muscular connectivity changes, prime the central nervous system, and improve force production when integrated into resistance training. In field-based studies with elite CrossFit athletes, MI enhanced power performance and enabled performance gains to transfer across distinct yet biomechanically related tasks. Furthermore, we show that MI’s effects are magnified when applied concomitantly with physical practice or when combined with non-invasive peripheral stimulation techniques (e.g., tendon vibration, transcutaneous vagus nerve stimulation). We propose MI as an active endogenous neuromodulation strategy, moving beyond its classical role as a cognitive training tool. By integrating MI with multimodal interventions, we aim to develop new neuromotor reprogramming paradigms prompting corticomotor remapping to facilitate elite sports performance and neurorehabilitation. Our approach positions MI at the crossroads of motor control, applied neurophysiology, and sports science to delineate original perspectives regarding how perception-action networks adapt to achieve elite performance.La représentation mentale d’une activité motrice fictive, c’est-à-dire pensée mais non réalisée, qu’on dénomme Imagerie Motrice (IM), active des réseaux encéphaliques proches de ceux impliqués dans l’exécution motrice réelle et constitue un levier original d’optimisation des performances neuromotrices. Nos travaux, à l’interface entre neurosciences fondamentales et applications de terrain, montrent que l’IM peut induire une plasticité cérébrale, améliorer la force musculaire et favoriser le transfert inter-habiletés chez des athlètes experts. Nous proposons de considérer l’IM comme une stratégie de neuromodulation endogène, dont le potentiel s’amplifie lorsqu’elle est intégrée à la pratique physique ou combinée à des stimulations périphériques non invasives. Cette approche ouvre la voie à de nouveaux paradigmes de reprogrammation neuromotrice, visant à identifier les conditions optimales de remodelage des réseaux perception-action. Nos résultats suggèrent que l’IM pourrait devenir un outil central pour l’entraînement de la très haute performance et la rééducation neuromotrice
Le témoignage d’Agatharchide à l’épreuve des données archéologiques : laveries et traitement du minerai dans les mines d’or ptolémaïques désert Oriental égyptien
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Comparative endocranial anatomy in the crocodylians Leidyosuchus canadensis and Stangerochampsa mccabei from the upper Cretaceous of Alberta, Canada
No full textInternational audienceAbstract Crocodylians evolved a high variety of rostral morphologies during their evolutionary history, highlighting the strong links between morphological plasticity and environmental and ecological parameters. Two Late Cretaceous alligatoroids, the mesorostrine Leidyosuchus canadensi s Lambe, 1907, and the brevirostrine Stangerochampsa mccabei Wu et al., 1996, from Alberta, Canada, preserve a large groove‐shaped recess on the posterior part of the maxilla that has not been documented in other alligatoroids. Despite the potential phylogenetic and paleoecological significance of this neurovascular feature, internal and endocranial structures remain under‐explored among stem alligatoroids. The endocranial morphology, including the paratympanic sinus system of Leidyosuchus canadensis and Stangerochampsa mccabei , was compared to those of extant crocodylians and of the extinct alligatoroid Diplocynodon ratelii based on computed tomography data. The Cretaceous alligatoroids share endocranial features, such as a posteroventral neurovascular projection of the labiolateral canal that connects to the groove‐like recess at the posterior edge of the maxilla and a paratympanic sinus system most similar to those of small‐bodied and young extant crocodylians, suggesting that these pedomorphic features may reflect the ancestral crocodylian condition. Future phylogenetic studies should consider internal and endocranial characters alike to improve our understanding on the relationships among crocodylians
"Du désordre dans une société trop ordonnée" : Censure, adaptation et création dans le théâtre argentin de la dernière dictature
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Flaubert et la peinture
No full text•Stéphanie Dord-Crouslé, « Flaubert et la peinture », avec Yvan Leclerc et Françoise Mobihan, dans le cadre d’une table ronde « Flaubert, à Maupassant : “dessine-moi Étretat” » organisée par les Amis de Flaubert et de Maupassant le 17/01/2026 au Musée des Beaux-arts de Lyon à l’occasion de l’exposition « Étretat, par-delà les falaises. Courbet, Monet, Matisse » (29/11/2025-01/03/2026).National audienc
