HAL-Université de Bretagne Occidentale
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Efficient energy-dissipative bioinspired architectured composite materials with high mechanical properties
No full textInternational audienceAdditive manufacturing of stiff and strong architectured composite materials enables to replicate the intricate architectures found in biological systems while providing excellent mechanical performance, paving the way for efficient energy dissipative systems. By abstracting different Bouligand architectures found in various marine creatures, the innovative concept of pseudo-orthogonal Bouligand architectured laminates (POB) is introduced to address the requirements of energy dissipation. POB are also coupled with the introduction of functional voids, which geometry and content are inspired by the pore canals present in the exocuticle and endocuticle of the lobster shell. The different architectured laminates are 3D-printed with PolyAmide 12 (PA12) reinforced by continuous basalt fibre. Novel POBs concepts are tested under non-perforating low-velocity impact at 9.4 m.s−1 and an impact energy of 50 J, along with more conventional stacking sequences to allow for comparison. All the tested samples dissipate at least 73 % of the impact energy, with porous POBs demonstrating the highest efficiency, ranging from 90 % to 95 %. This represents an improvement of up to 10 % compared to their denser counterparts, while also being 30 % lighter. The resulting performance in terms of energy dissipation capacity is then attributed to the underlying damage mechanisms imparted by the architecture, highlighting the desirable behaviour of porous structures
Imagerie Hyperspectrale pour la Segmentation Automatique des Tissus en Chirurgie Orthopédique
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Collective forms of leadership and team cognition in work teams: A systematic and critical review
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High Connectivity at Abyssal Depths: Genomic and Proteomic Insights Into Population Structure of the Pan-Atlantic Deep-Sea Bivalve Ledella ultima (E. A. Smith, 1885)
No full textInternational audiencePhylogeographic analyses have advanced our understanding of evolutionary processes in the deep sea, yet patterns of genetic variation and population divergence at abyssal depths remain poorly understood. The bivalve Ledella ultima is one of the most abundant protobranchs in the abyssal Atlantic, making it a valuable model organism for studying phylogeographic patterns and population connectivity. However, evidence for sex-specific heteroplasmic mtDNA challenges the assessment of genetic structure using mitochondrial markers alone. To address this, we used mtDNA (COI, 16S), single-nucleotide polymorphisms (SNPs) from 2b-RAD, and proteomic profiles to examine the population structure of L. ultima across seven Atlantic basins spanning over 10,000 km in latitude. Five mitochondrial lineages with a lack of geographic structure were consistently identified by COI and 16S. Conversely, SNP and proteomic data did not mirror these findings, denoting that heteroplasmic mtDNA inflates intraspecific genetic divergence in this gonochoric species. Despite the SNP data revealing overall low genetic divergence, subtle genetic structure was detected by admixture analyses supporting two source populations: one in the north and central Atlantic, and a second in the south Atlantic, with moderate admixture in the Brazil and Cape basins. Proteomic fingerprinting revealed two basin-separated groups with patterns distinct from the nuclear data, suggesting environmentally driven shifts in protein expression. Our findings underscore the value of integrating nuclear genomic and proteomic tools to decipher population connectivity at abyssal depths, where minimal genetic differentiation necessitates fine-scale analyses
Flexural Analysis of Porous Microbeams Based on the Modified Strain Gradient Theory Including Stretching Effects
No full textBonjour, Je viens d'ajouter la référence bibliographique à mon résumé, comme demandé. Merci pour votre patience et votre assistance. Bien cordialement,International audienceFlexural Analysis of Porous Microbeams Based on the Modified Strain Gradient Theory Including Stretching Effect
Ce que coéduquer veut dire pour les acteurs d’une association d’éducation populaire. Représentations de la collaboration avec les parents dans le cadre de l’accompagnement à la scolarité
No full textInternational audienceIn the context of partnership policies in education, this paper focuses on anaspect of a doctoral research project examining the relationships between parents, schools, and associations. More specifically, the paper explores issues relating to the collaboration between parents (mainly working-class immigrant mothers) and people working for a Parisian public education association, within the framework of a school support program. Within this program, how do association workers concretely perceive collaboration with families? What expectations and perceptions do they have of parents? The analysis of empirical data—collected from interviews with association workers (sociocultural activity professionals and volunteers) and in situ participant observations—reveals a significant diversity of discourses. Some workers—mainly from the permanent team—see parents as true partners while others, principally volunteers, perceive them (or even the school) as an obstacle to the children’s educational success and therefore adopt a compensatory rationale. On this basis, it is then possible to construct a set of three ideal types to better understand the tensions and constraints affecting themEn esta época de políticas de colaboración educativa, este artículo plantea un aspecto de una investigación doctoral cuya finalidad es poner de relieve las relaciones entre padres, escuelas y asociaciones. Más concretamente, este artículo examina los retos de la colaboración entre los padres (principalmentemadres inmigrantes de clases populares) y los miembros de una asociación parisina de educación popular durante sus actividades de acompañamiento escolar. En este contexto, ¿cómo perciben los actoresasociativos la colaboración con las familias en sus discursos individuales? ¿Cuáles son sus expectativas y su percepción con respecto a los padres? El análisis de los datos empíricos —procedentes de las entrevistas con los actores asociativos (tanto facilitadores como voluntarios) y de los comentarios de los participantes in situ— pone de manifiesto una gran diversidad de discursos. Algunos actores (sobre todo parte del equipo permanente) señalan a los padres como auténticos compañeros; otros (sobre todo parte de los voluntarios) consideran a los padres (y hasta a la Escuela) como un obstáculo para el éxito de sus hijos y, por tanto, actúan con una lógica compensativa. A partir de estos resultados, es posible construir un conjunto de tres tipos ideales que permiten comprender mejor las tensiones y limitaciones que afectan a los distintos actores.À l’ère des politiques de coéducation, cet article propose de s’arrêter sur l’un des aspects d’une recherche doctorale, visant à mettre au jour les relations entretenues entre parents, École et associations. Plus précisément, cet article se penche sur les enjeux de la collaboration entre les parents (essentiellement des mères de familles populaires immigrées) et les acteurs d’une association d’éducation populaire parisienne, dans le cadre d’un dispositif d’accompagnement à la scolarité. Dans le cadre dudit dispositif, comment les acteurs associatifs appréhendent-ils concrètement la collaboration avec les familles dans leurs discours individuels ? Quelles sont leurs attentes et leurs représentations à l’égard des parents ? L’analyse des données empiriques – issues d’entretiens auprès d’acteurs associatifs (professionnels de l’animation socioculturelleet bénévoles) et d’observations participantes in situ – montre une réelle diversité dans les discours. Certains acteurs – plutôt issus de l’équipe permanente – voient les parents comme de véritables partenaires, tandis que d’autres – plutôt parmi les bénévoles – considèrent les parents (voire l’École) comme un frein à la réussite éducative des enfants accueillis et agissent donc dans une logique compensatoire. Sur cette base, il est alors possible de construire un ensemble de trois idéaux-types permettant de mieux saisir les tensions et contraintes qui s’exercent sur les différents acteurs
Rituximab Versus Conventional Therapy for Remission Induction in Eosinophilic Granulomatosis With Polyangiitis : A Randomized Controlled Trial
No full textInternational audienceBackground: Eosinophilic granulomatosis with polyangiitis (EGPA) is an eosinophilic antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Rituximab has emerged as the standard of care in other types of ANCA-associated vasculitis, but controlled studies on its use in EGPA are yet lacking.Objective: To compare rituximab with conventional strategy for the induction of remission in patients with EGPA.Design: Phase 3, multicenter, randomized, controlled, double-blind, superiority trial. (ClinicalTrials.gov: NCT02807103).Setting: France.Participants: Patients with a diagnosis of EGPA, newly diagnosed or relapsing disease at the time of screening, with active disease defined as a Birmingham Vasculitis Activity Score (BVAS) of 3 or greater.Intervention: Glucocorticoids plus rituximab (1 g 2 weeks apart) compared with the conventional strategy (glucocorticoids alone or in combination with cyclophosphamide in severe forms) for induction of remission.Measurements: The primary end point was remission defined as a BVAS, version 3, of 0 and a prednisone dose of 7.5 mg/d or less at day 180. Secondary end points included duration of remission during the study, average daily glucocorticoid dose, and safety.Results: A total of 105 participants were randomly assigned. Thirty-three (63.5%) patients in the rituximab group achieved the primary end point compared with 32 (60.4%) in the control group (relative risk, 1.05 [95% CI, 0.78 to 1.42]; P = 0.75). Results were similar at day 360. The mean duration of remission was 48.5 ± 6.51 weeks in the rituximab group and 49.1 ± 7.42 weeks in the conventional strategy group (P = 0.41). All relapse and major relapse rates were similar between the 2 groups. There was no statistically significant difference in the average daily glucocorticoid dose and no statistically significant differences in the rates of adverse events between the treatment groups.Limitation: Design not appropriate to answer the question of equivalence between rituximab and cyclophosphamide in patients with severe EGPA.Conclusions: Rituximab was not superior to a conventional remission induction strategy in EGPA.Primary funding source: French Ministry of Health
IC Modeling via Machine Learning Regressions: A Data-Driven Approach to SPICE Integration
No full textInternational audienceThis paper presents a method for generating accurate and efficient macromodels of high-speed I/O buffers. Extending existing techniques, the proposed approach enables a modular and scalable model generation tool based on machinelearning. Given the limitations of traditional methods, this work leverages kernel regression to develop SPICE-compliant models. Two compression schemes, random selection and Nyström approximation are used and thoroughly compared to reduce the number of expansion terms, with beneficial effects in terms of compactness of the SPICE implementation. The effectiveness of the method in terms of model accuracy and efficiency is stressed through real devices and typical signal and power integrity cosimulations
Apport des images tri-stéréoscopiques Pléiades pour la discrimination des habitats naturels côtiers
No full textInternational audienceCette étude présente l’évaluation des images satellitaires Pléiades pour la discrimination des habitats naturels côtiers sur un site Natura 2000 de 22 km2 en Bretagne (France). Un Modèle Numérique de Surface (MNS) a été généré à 0,5 m de résolution spatiale à partir d’images tri-stéréoscopiques acquises en juillet 2021 en utilisant le service de calcul en ligne Formater DSM-OPT (Digital Surface Models from OPTical stereoscopic very-high resolution imagery). Ensuite, un modèle numérique de hauteur (MNH) a été calculé en soustrayant un Modèle Numérique de Terrain (MNT) dérivé de données LiDAR (RGE ALTI, IGN®) au MNS. La précision verticale du MNH et son apport pour la discrimination des habitats naturels ont été évalués en utilisant une centaine de relevés floristiques collectés sur le terrain, spécifiquement pour cette étude. L’effet de la pente du terrain sur la précision du MNH a aussi été évalué. Les résultats montrent que la précision verticale de la hauteur de végétation dérivée des images Pléiades (MNH) est bonne (erreur absolue moyenne de 0,49 m) et n’est pas significativement impactée par la pente. De plus, ils indiquent qu’une grande part (43%) de la variance du MNH est expliquée par les types d’habitats naturels. Cette étude souligne l’intérêt des images tri-stéréoscopiques Pléiades pour discriminer les habitats naturels côtiers en vue de leur cartographie et leur suivi. Elle montre également que le service en ligne DSM-OPT permet de générer facilement et rapidement un MNS
N-3 long-chain polyunsaturated fatty acids in fish physiology: From aquaculture to economic, ecological and public health challenges
No full textInternational audienceN-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA), particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential molecules to fish physiology, influencing their development, metabolism, immunity, behavior, and reproduction. However, fish have a limited ability to synthesize these fatty acids endogenously, and must obtain them through diet. The dietary availability of these molecules is increasingly challenged by both ecological and aquaculture constraints linked to climate change and to sustainability of ressources (e.g. fisheries). Currently, global changesincluding ocean warming -may reduce the availability of these fatty acids in marine food webs, raising concerns for fish population dynamics and aquaculture sustainability that still largely depends on forage fish. In this review, we first summarize the metabolic pathways and tissue distribution of n-3 LC PUFA in freshwater and marine fish, highlighting differences in bioconversion capacities. We then explore the physiological and behavioral consequences of varying dietary n-3 LC PUFA levels in aquaculture feeds and natural environments, including effects on growth, locomotion, cognition, metabolic performance, oxidative status, immune response, and reproductive investment. We also review current alternatives to fish meal and fish oil, such as plant, insect, microbial, and genetically modified sources, and discuss their potential to meet fish nutritional needs. Altogether, this synthesis underscores the current challenge of n-3 LC PUFA dietary shortage for fish health, aquaculture production and nutritional security of human population, and identifies knowledge gaps that must be addressed to ensure both ecological resilience and sustainable aquaculture development in a rapidly changing world.</div