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Frontiéralité et développement: dans la lecture des dynamiques croisées entre Mobilités, Cultures et Territoires
No full textInternational audienc
Linear landau equation as a limit of a tagged particle in mean field interaction with a free gas
No full textWe consider a tagged particle in mean field interaction with a free gas of density N at equilibrium. In dimensions , we prove the convergence of its trajectory, as N goes to infinity, to the one of a diffusion process associated with the linear Landau equation. The proof of the convergence of the martingale problem relies on two key ingredients: long time stability results of the microscopic dynamics, and controls on the probability of particle recollisions
A reappraisal of the amorphization kinetics of water ice: Combined experimental and numerical investigations and amorphization cross-sections in the 90–120 K range
No full textInternational audienc
New Bayesian optimisation framework for robust multi-objective design: decoupling performance and uncertainty
No full textInternational audienceRobust optimisation is increasingly critical in engineering design due to the growing emphasis on robustness under uncertainty. However, existing methods often neglect explicit control of performance stability, particularly regarding the variance of objectives. To address this limitation, this work introduces a Varianceconstrained Robust Bayesian Optimisation framework to e ciently perform multiobjective optimisation considering input uncertainty. A robust Gaussian process is employed to quantify input uncertainty by providing both the expected objective value and its associated uncertainty. These two aspects are then integrated using a variance-penalised scalarisation method, which leverages user-defined parameters to flexibly balance mean performance and variability, thereby accommodating different levels of stability tolerance. During optimisation, this scalarisation steers the acquisition function toward regions consistent with the desired stability preference; at reporting time, surrogate estimates are used to discard any designs that violate the uncertainty threshold, and the Pareto set is computed from the remaining stability-feasible points. The novelty lies in enabling a flexible, context-dependent design selection, while preserving the data-e ciency advantages of Bayesian Optimisation. The framework has been thoroughly tested on a series of synthetic benchmark problems, including a higher-dimensional (6D) case, demonstrating its e ectiveness in handling varying uncertainty tolerances and substantiating its strong potential for real-world applications
An autosomal recessive nonsense variant in the EGFR gene induces perinatal lethality in “Blonde d'Aquitaine” calves
No full textInternational audienceBackground: Six cases of perinatal lethality associated with phenotypes consistent across cases, short and brush-haired appearance, alopecia and erythematous areas on the limbs and facial protuberances, excess skin all-over the body, have recently occurred in the "Blonde d'Aquitaine" cattle breed in South-Western France, suggesting the emergence of a recessive genetic anomaly.Results:Genetic analysis identified a nonsense variant in the epidermal growth factor receptor (EGFR) gene, XP_002696936:p.Trp898Ter, as likely responsible for this anomaly and a bull born in 1967 as one ancestor that contributed to the spread of this allele in the breed. Functional studies on affected calves and cross-species comparisons of the phenotypes associated with such a variant were consistent with the results of the genetic study.Conclusion: A recessive nonsense EGFR variant was identified as being responsible for perinatal lethality in the "Blonde d'Aquitaine" cattle breed. It enabled the introduction of a screening test for this allele, which should lead to the progressive eradication of this genetic flaw
Computation of Large Spatial Datasets with the M function
No full textIncreasing access to large geo-referenced datasets, coupled with the development of computing power, has encouraged the search for suitable spatial statistical tools. Distance-based methods have been extensively developed in several scientific fields to detect spatial concentration, dispersion or independence of entities at any distance and without any bias. Recently, Tidu et al. (2024) highlighted the qualities of Marcon and Puech’s M function, a relative distance-based measure, and also expressed reservations about the computation time required. Herein, we propose a methodology that specifies the processing of large spatialized datasets with the M function using R software. The computational performance of M was conducted using two methods: (i) a precise evaluation of the computational time and memory requirements for geo-referenced data was conducted using the dbmss package in R via performance tests, and (ii) based on Tidu et al. (2024), we considered an approximation of the geographical positions of the entities. The deterioration extent of the M results was estimated and discussed as the gains it provides in computation time. We provided evidence that the individual location approximation generated information loss at substantially small distances, implying a trade-off between the smallest distanceat which spatial interactions could be detected and computing performance. The R code used in the article is given for the reproducibility of our results
Ecodélégués et professionnels de l'éducation : quel accompagnement à l'engagement éco-citoyen ?
No full textInternational audienceEn considérant désormais les jeunes comme des acteurs majeurs de nos sociétés et non comme des « citoyens de demain en formation » (Pleyers, 2016), les recherches se penchent de plus en plus sur l’analyse de leurs expériences pour comprendre les enjeux de la citoyenneté (Rouyer et al., 2020). Aussi, diverses conditions ont été identifiées comme favorisant les expériences d’engagement éco-citoyen : se sentir concerné, avoir des connaissances environnementales, comprendre les enjeux globaux, agir au sein d’une communauté, partager des expériences positives (Chawla et Derr, 2012 ; Bader et al., 2014) et agir localement (Morin et al., 2022), dans une visée d’amélioration de l’environnement (Bois et al., 2021 ; Lange et Barthes, 2021). Nous nous intéressons plus particulièrement aux expériences vécues en milieu scolaire, lieu où l’adolescent passe le plus clair de son temps. Quel sens les élèves donnent-ils à leurs rôles et à leurs expériences dans les dispositifs ; quelle place est accordée aux élèves
Modeling Ultra-High-Energy Cosmic Rays propagation using the input from Configuration Interaction Shell Model
No full textInternational audienceThe dipole response of a nuclear system, characterized by its photon strength function (PSF), is a key ingredient of many applications of nuclear structure, ranging from nuclear reactor design and nuclear waste transmutation to astrophysical models of nucleosynthesis and stellar evolution. While the majority of those applications require the knowledge of PSF of mid-mass and heavy nuclei, there is now renewed interest in strength distributions of light nuclei in the framework of the PANDORA project, which aims at an understanding of the mass distribution of ultrahigh-energy cosmic radiation (UHECR).UHECR is of extragalactic origin and its interaction along the travel path is dominated by photoabsorption of cosmic background radiation boosted to the Giant Dipole Resonance (GDR) energy region in the center-of-mass system. Thus, systematic knowledge of the photoabsorption cross sections in light nuclei and of their subsequent particle decay is required. The purpose of this work is to enhance the database of available theoretical evaluations of PSF of light nuclei that are necessary in the studies of UHECR propagation. We employ the Configuration Interaction Shell Model (CI-SM) approach to provide predictions of dipole response for and -shell nuclei, with mass number between 7 and 40. Theoretical predictions are compared to available data and to existing predictions from phenomenological and microscopic models. Finally, the impact of using of CI-SM PSF on the predicted propagation of a Ca UHECR source is studied
Structured Deformation Modeling with Implicit Deformation Modules
No full textThis paper presents a comprehensive theoretical exploration of implicit deformation modules and their application in shape analysis, especially registration problems. The implicit deformation module framework enables the generation of advanced structured deformations in a user-friendlyand efficient manner. We establish the well-posedness of deformations generated by these modules and demonstrate the existence of solutions to the resulting registration problem. To achieve this, we introduce the notion of featured landmarks, which enables the definition of point deformations carrying features under a flow of diffeomorphisms, even when the features themselves cannot be directly transformed via a group action of diffeomorphisms. These contributions bridge the gap left by the IMODAL1 software paper [42], which provides an implementation of some of the deformation modules presented here (explicit and implicit of order one) but lacks advanced theoretical guarantees. Finally, we demonstrate how complex structured deformation models can be estimated from data, supported by practical examples