HAL-Université de Bretagne Occidentale
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Proposition d’un modèle précurseur pour une compréhension du cycle de la matière organique lors de la pratique du compostage à l’école maternelle
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Far-red light regulates phototactic behavior of benthic pennate epipelic diatoms under low irradiance
No full textInternational audienceDiatom-dominated microphytobenthic communities are exposed to steep and dynamic light gradients in intertidal sediments. The vertical migration of epipelic pennate diatoms is a key adaptive trait enabling optimal light acquisition. However, it remains unclear whether these organisms can detect and respond to long-wavelength light, especially because deeper photic layers are enriched in far-red due to attenuation of shorter wavelengths. Here, we investigated the phototactic responses of a natural microphytobenthic biofilm, primarily composed of epipelic pennate diatoms, to long-wavelength light at two low irradiance levels (5 and 20 µmol photons m⁻² s⁻¹), using a custom-built multispectral LED illuminator. Red light (660 and 680 nm) induced a strong upward vertical migration and a high effective quantum yield of photosynthesis. Far-red light (720 and 740 nm) also triggered a significant upward migratory response, although more moderate than red light. In contrast, near-infrared wavelengths (770 and 810 nm) elicited no significant migratory activity, indistinguishable from the dark controls. Phototactic migration was observed even at 5 µmol photons m⁻² s⁻¹, suggesting a high sensitivity to light at intensities potentially below the photosynthetic compensation point. Our results provide evidence that benthic pennate diatoms can behaviorally respond to long-wavelength, low-intensity light. This response, likely mediated by phytochrome-like photoreceptors, suggests the existence of a low-light, long-wavelength sensing mechanism that enables diatoms to detect fine-scale spectral gradients as cues for surface detection and vertical positioning within the sediment matrix
S’exprimer pour s’accorder. Appropriation des pratiques expressives de gestion de classe par les élèves dans deux écoles dites « alternatives »
No full textInternational audienceL’article évoque des pratiques de gestion de classe dites « expressives », réglant les désaccords par l’écoute des ressentis des élèves et évitant le recours à la sanction. Ces pratiques, justifiées en partie par un souci de bien-être des enfants, sont-elles pour autant accueillies favorablement par ces derniers ? Peuvent-elles susciter des résistances de leur part ? L’article explore ces questions en observant la réception des pratiques expressives de gestion de classe par des élèves âgés de 9 à 12 ans, scolarisés dans deux écoles privées hors contrat dans lesquelles ces pratiques sont particulièrement présentes. Les résultats montrent des appropriations différenciées par les enfants, entre adhésion, prise de distance critique et investissement selon des logiques propres, éloignées de celles des enseignants. Ces observations suggèrent une complexification du travail émotionnel demandé aux élèves au travers des pratiques expressives de gestion de classe
Atopic dermatitis beyond the skin: Characterizing skin pain in the “Scars of Life” study
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Phosphonate-based amphiphiles for nucleic acid delivery
No full textInternational audienceAmphiphilic compounds are used for the protection and delivery of nucleic acids for both in vitro and in vivo applications. Among the large diversity of molecular structures of amphiphiles, the current chapter focuses on the synthesis of phosphonate and phosphonic acid derivatives that were specially designed for the delivery of nucleic acids. Phosphonic acid compounds are an alternative to the calcium phosphate-based systems that were initially used for in vitro transfection. The first phosphonate was reported in 1995, and the number of such phosphorus-based compounds increased over time, also the incorporation of other types of phosphorus functionalities, including the phosphoramide moiety, in particular. The phosphonate function that allows the incorporation of two lipid chains and one polar head group is a versatile molecular platform, allowing specific modifications of each of these parts, permitting the optimization of the structure of phosphonate-based nucleic acid carriers
An experimental method for determining the in-plane shear modulus of carbon fibres
No full textInternational audienceThe performance of bituminous materials is often evaluated using rheological properties measured within the linear viscoelastic region. If there is a univocal temperature dependence of all the relaxation times, data obtained in different operating conditions can be translated onto a logarithmic scale where they partially overlap and merge into a single master curve. This is the well-known time–temperature superposition principle that has been successfully applied for decades. However, the empirical nature of the method has led to many different procedures being used for the graphical construction of the master curve. In addition, the continuously increasing calculating power has led to new approaches, such as the simultaneous modelling of the represented viscoelastic function. Losing track of the basic statements of the method is the hidden drawback of this wide range of available protocols with the risk of artefacts and incongruences being introduced in the construction of the master curves. This review summarizes these basic statements together with the empirical and phenomenological approaches developed over the years. The aim of this study is to help the reader in choosing the most appropriate method to build the master curves. Although the subject of the review is of general application, the field of bitumen is focused on
Les aventures des aventures de Rintintin, ou le tortueux parcours des archives de Célestin Lainé
No full textInternational audienceCélestin Lainé is one of the most singular Breton nationalist leaders. When he came to politics in the mid-1920s, he soon advocated clandestine violent action, before imagining the training of a future Breton army. It is finally a supplementary troop of the German occupier that he will be allowed to form, at the end of 1943, and who takes refuge in Germany at the Liberation. Pursued by the French justice system for intelligence with the enemy, he exiles to Ireland, where he dies in 1983. His archives followed his singular trip, from one country to another, before being gathered at the home of Louis Feutren, one of his seconds, who gave a part to the Breton and Celtic Research Centre in 2008, and the other in 2010 at the National Library of Wales, where they regularly spark debates much more ideological than scientific. Now the archives are for the historian, who is neither judge nor lawyer, the material from which he tries to simply say why what happened happened. The Lainé papers, in Brest and Aberystwyth, allow one to calmly consider a whole section of 20th century political history. This is what various historians, essentially French, often students of the University of Western Brittany, have understood.Célestin Lainé est un des leaders nationalistes bretons des plus singuliers. Venu à la politique au milieu des années 1920, il prône bientôt l’action violente clandestine, avant d’imaginer l’instruction d’une future armée bretonne. C’est finalement une troupe supplétive de l’occupant allemand qu’il sera autorisé à constituer, à la fin des années 1943, et qui se réfugie en Allemagne à la Libération. Poursuivi par la justice française pour intelligence avec l’ennemi, il s’exile en Irlande, où il meurt en 1983. Ses archives ont suivi son parcours singulier, d’un pays à l’autre, avant d’être rassemblées chez Louis Feutren, l’un de ses seconds, qui en a donné une partie au Centre de recherche bretonne et celtique en 2008, et l’autre en 2010 à la Bibliothèque nationale du pays de Galles, où elles suscitent régulièrement des débats bien plus idéologiques que scientifiques. Or les archives sont à l’historien, qui n’est ni juge ni avocat, le matériau à partir duquel il tâche de dire simplement pourquoi ce qui s’est passé s’est passé. Les papiers Lainé, à Brest et Aberystwyth, permettent d’envisager sereinement tout un pan de l’histoire politique du XXe siècle. C’est ce qu’ont compris divers historiens, essentiellement français, souvent étudiants de l’Université de Bretagne occidentale
Iterative LLM-based improvement for French Clinical Interview Transcription and Speaker Diarization
No full textAutomatic speech recognition for French medical conversations remains challenging, with word error rates often exceeding 30% in spontaneous clinical speech. This study proposes a multi-pass LLM post-processing architecture alternating between Speaker Recognition and Word Recognition passes to improve transcription accuracy and speaker attribution. Ablation studies on two French clinical datasets (suicide prevention telephone counseling and preoperative awake neurosurgery consultations) investigate four design choices: model selection, prompting strategy, pass ordering, and iteration depth. Using Qwen3-Next-80B, Wilcoxon signed-rank tests confirm significant WDER reductions on suicide prevention conversations (p < 0.05, n=18), while maintaining stability on awake neurosurgery consultations (n=10), with zero output failures and acceptable computational cost (RTF 0.32), suggesting feasibility for offline clinical deployment
Magnon Kerr effect in a magnetic thin film strongly coupled to a microwave resonator
No full textCavity magnonics investigates hybrid systems where magnons interact coherently with photons, providing a platform to harness light-matter interaction in magnetic materials. Progress in this field hinges on achieving stronger and tunable nonlinear effects, which are essential for controlling magnon dynamics and frequency conversion. Here, we demonstrate the magnon Kerr effect in an anisotropic magnonic system comprising a 200~nm-thick yttrium iron garnet film strongly coupled to a three-dimensional microwave resonator. The strong shape anisotropy significantly enhances the magnon Kerr effect compared to a sphere of equivalent volume, while the cavity enables sensitive probing of magnetization dynamics. We demonstrate continuous tunability of the magnitude and sign of the Kerr shift by controlling the static orientation of the magnetization. Input-output modeling of the magnon-photon interaction provides a consistent description of our system and Kerr coefficients matching the experimental results. Our findings demonstrate a scalable approach to enhancing Kerr anharmonicity in hybrid magnon-photon systems while preserving strong coupling
À Terre libérée : une dystopie glocale
No full textInternational audienceAujourd’hui le retour à la terre est recherché comme une panacée qui nous délivrerait des maux de l’urbanité, de la pollution et de l’anthropocène. En s’immergeant dans la terre chacun espère encore aujourd’hui1 libérer la terre de l’exploitation de l’anthropocène trouverait dans les communs2 une nouvelle expérience durable. Elever3 en respectant les cycles de la nature est rendu complexe dans le contexte : la perturbation globale des cycles de la nature par la pollution et le changement climatique est plus important encore aujourd’hui mais existe déjà dans la critique au début du XXe siècle que nous décrivons ici. 4 Andruchiw A., 2025, Voir son assiette comme un outil de lutte, pour une déviandisation de nos usage (...)2Ce lien entre critique de l’industrialisation par l’anthropocène et recherche de solution contre le carnivorisme4 implique une « déviandisation » : celle-ci est moins une privation qu’une nouvelle économie végétaliste de la terre. La libération pourrait être globale par le renversement du capitalisme mais aussi, comme nous le démontrons ici, par une modification des modes de vie, de production, de l’habitat et d’alimentation.3Cette libération de la terre du modèle industriel la construction de colonie agricole alternative aura commencé dans les causes anarchistes. Plutôt que de détruire par la violence politique, nous cherchons ici à décrire la dystopie végétarienne de Terre Libérée. Puissions nous libérer la terre