Portail HAL de l'Université du Littoral Côte d'Opale
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Liens entre CLES et enseignements en langues dans l’enseignement supérieur public : étude de cas
No full textInternational audienceÀ l'occasion des 25 ans du CLES, cette communication propose d'explorer les liens entre certification et formation dans l'enseignement supérieur public à partir d'une étude de cas institutionnelle engagée depuis 2014. Inscrite dans une politique linguistique transversale, la démarche repose sur la perspective actionnelle, l'organisation par groupes de niveaux CECRL et l'intégration du travail autonome dans les CRL. Le projet s'appuie sur un pilotage stratégique centralisé, une adhésion collective des acteurs (présidence, conseils, enseignants, étudiants) et une intégration du CLES dans les modalités de contrôle des connaissances avec prise en compte d'une conversion des résultats à hauteur de 50% des résultats en UE LV en L3 S6 et M2 S3.L'étude mobilise les cadres de la gestion de projet et de l'ingénierie de formation pour analyser les étapes : analyse des besoins, conception, pilotage institutionnel, mise en œuvre et évaluation (Parmentier, 2008 ; Dennery, 2006). Le nombre d'admis au CLES a été multiplié par dix entre 2010 et 2022 et l'étude montre certains effets washback (Mac Gaw, 2017 et 2020) sur les pratiques pédagogiques et les résultats des étudiants. Cette communication montre que le CLES peut devenir un outil structurant de la formation universitaire, articulant reconnaissance externe, exigences pédagogiques et équité. Il contribue à renforcer la qualité, la lisibilité et la professionnalisation des langues dans l'enseignement supérieur public
Generalized prelie and permutative algebras
No full textFinal version. To be published in Journal of Algebra and ApplicationsWe study generalizations of pre-Lie algebras, where the free objects are based on rooted trees which edges are typed, instead of usual rooted trees, and with generalized pre-Lie products formed by graftings. Working with a discrete set of types, we show how to obtain such objects when this set is given an associative commutative product and a second product making it a commutative extended semigroup. Working with a vector space of types, these two products are replaced by a bilinear map Φ which satisfies a braid equation and a commutation relation. Examples of such structures are defined on sets, semigroups, or groups. These constructions define a family of operads PreLie Φ which generalize the operad of pre-Lie algebras PreLie. For any embedding from PreLie into PreLie φ , we construct a family of pairs of cointeracting bialgebras, based on typed and decorated trees: the first coproduct is given by an extraction and contraction process, the types being modified by the action of Φ; the second coproduct is given by admissible cuts, in the Connes and Kreimer's way, with again types modified by the action of Φ. We also study the Koszul dual of PreLie Φ , which gives generalizations of permutative algebras
Spatio-temporal dynamics in biofilm and planktonic microbiota during vibriosis in a Dicentrarchus labrax aquaculture system
No full textInternational audienceAquaculture plays a critical role in meeting the global seafood demand, with the European sea bass (Dicentrarchus labrax) being a key species in European fisheries. However, bacterial diseases like vibriosis – often caused by Vibrio harveyi – remain a major threat. To better understand the potential impact of biotic factors on vibriosis, this study investigates the spatio-temporal dynamics of microbial communities in a semi-open sea bass aquaculture system in northern France, frequently affected by vibriosis. From May to November 2022, water and biofilm samples were collected at three depths (0.3 m, 2.15 m, and 4 m) in a 4-meter-deep tank. Illumina MiSeq sequencing of the 16S rRNA V4-V5 region was used to characterize bacterial populations. The sampling period comprised two vibriosis outbreaks requiring antibiotic treatment. Results revealed that microbial communities in water and biofilms were dominated by Proteobacteria (73.5 % and 46.7 %, respectively) and Bacteroidota (20.4 % and 38.1 %, respectively). Vibrionaceae were present throughout the campaign, indicating their persistent occurrence in the tank. Temporal and spatial variations were more pronounced in biofilms, whereas water samples showed mainly temporal differences. Microbial shifts coincided with disease episodes and antibiotic treatments, suggesting links between community structure, environmental conditions, and disease emergence. This study provides insights into microbial dynamics under disease stress and highlights the importance of monitoring microbial communities for improving disease management in aquaculture systems
Analyse 3D de la forme des otolithes pour l'identification des stocks
No full textInternational audienceAccurate spatial stock delineation is crucial for sustainable fisheries management, yet traditional methods often struggle to account for the spatial complexity of fish populations. Otoliths, calcified structures in the inner-ear of fish, serve as natural biological markers that encode valuable information about an individual’s life history, habitat, and population structure. Otolith shape is widely used for stock identification because it reflects genetic and environmental influences, allowing researchers to distinguish between fish populations. However, conventional otolith shape analysis relies primarily on two-dimensional (2D) imaging, which captures only a single plane of these inherently three-dimensional structures. This approach can introduce biases due to orientation inconsistencies and the loss of crucial morphological details. To overcome these limitations, we applied an innovative, three-dimensional (3D) otolith shape analysis to red mullet (Mullus barbatus) stocks in the Mediterranean Sea, comparing it to traditional 2D methods. The Elliptical/Spherical Fourier Descriptors were applied in both 2D and 3D data.Using 316 sagittal otoliths from 16 geographical sub-areas, we used various supervised and unsupervised machine learning techniques to assess stock structure. The results show that 3D shape analysis provides a more accurate and robust stock delineation with both supervised and unsupervised methods, capturing the full spatial complexity of otolith morphology. The estimated stock structure was compared with stock delineations based on expert-defined references and environmental data, showing a closer match when using 3D analysis. Unsupervised classification suggested an optimal division into two major stocks, supervised learning confirmed that 3D descriptors outperform 2D in stock identification. 3D-bases hierarchical clustering has a higher stock determination rate (Adjusted Rand index over 0.6) than those obtained from 2D data. Moreover, 3D-based supervised classifiers, especially Random Forest as the best model fitted the data, achieved an accuracy gain of around 10% compared to the 2D data with the same approaches. By offering a more precise and scalable approach to stock identification, 3D otolith shape analysis presents a powerful tool for improving spatial stock assessments
Nighttime chemistry of furanoids and terpenes: Temperature dependent kinetics with NO3 radicals and insights into the reaction mechanism
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Real-Time Rendering of Old Glass Panes
No full textInternational audienceMany cultural heritage projects involve the 3D reconstruction of old glass buildings. Old glass, however, has many defects, due to the artisanal manufacturing techniques of the time, such as crown or cylinder blowing. The presence of these defects has a number of visual consequences, manifesting itself in the deviation of light passing through or reflecting off the glass panes. The appearance of these old glasses, the lighting produced through their surface, and the vision of the world perceived through them, is thus very different from what is perceived through contemporary industrial glass, and therefore has a considerable impact on the rendering that will be produced in their presence. However, setting up interactive virtual tours that take into account these old glasses is proving complex, as the materials available in commercial 3D rendering engines are unable to faithfully reproduce the lighting effects produced. In this paper, we propose a precise, real-time rendering of the surface and volume defects (bubbles, chords) present in some old glass and their impact on the appearance of the world perceived through these panes. Our approach is based on ray tracing, which not only interacts with the material's geometric defects, but also takes into account the curvature of light as the glass's refractive index varies
Evaluation of nine candidate absorbents for VOC removal in biogas upgrading : Experimental and theoretical study
No full textInternational audienceBiogas is a promising energy source that could replace non-renewable, polluting energy. However, some impurities, including carbon dioxide, hydrogen sulfide, and especially various volatile organic compounds (VOCs), should be removed prior to end-use. In this work, nine solvents were evaluated for the first time for their potential to capture six VOCs found as biogas impurities. The vapor-liquid partition coefficients (K) of the six VOCs in the nine solvents were determined using static headspace-gas chromatography. Conductor-like Screening Model for Real Solvents (COSMO-RS) and quantum chemical calculations were used to analyze the intermolecular interactions between absorbents and VOCs. Diethylene glycol dibutyl ether was found to be the best performing absorbent for hydrophobic VOCs with K value up to 62,295 times lower than that of water in the case of decamethyltetrasiloxane. The selected absorbents maintained high VOC absorption capacity of > 98 % over ten absorption-desorption cycles, demonstrating their effectiveness and stability. Furthermore, the partition coefficients of VOCs in absorbents were found to be affected by both the free volume of the absorbent and the binding energy of the absorbent-VOC complex. Taken together, the experimental and theoretical results suggest that the studied absorbents are promising alternatives for VOC removal in biogas upgrading processes
Linking oceanographic conditions to foraging behaviour of southern elephant seals by characterising mid-trophic levels with an animal-borne echosounder
No full textInternational audienceChanges in Southern Ocean thermohaline conditions could drive changes in phytoplankton community composition propagating into upper-trophic levels, from the abundance and composition of mid-trophic level communities to foraging behaviour of top marine predators. Studies exploring the ecological consequences of such processes are largely limited by our in-situ observation capacity. The simultaneous deployment of a miniature sonar tag, combining active acoustics and movement sensors, with oceanographic tags on 4 adult female southern elephant seals from the Kerguelen Islands provided in-situ measurements of thermohaline conditions, mid-trophic level abundance and seal-foraging behaviour. In addition, chlorophyll-a concentration and relative abundance of different phytoplankton size classes were assessed from satellite ocean colour data. This study reveals that east of the Kerguelen Islands, the subsurface scatterer abundance (related to mid-trophic level organisms) assessed by the sonar tag was partly positively linked to surface satellite-derived microphytoplankton biomass, especially in colder waters and frontal zones. Female elephant seals were found to dive shallower with higher subsurface scatterer abundance, which indicated a better prey accessibility, and were found to catch more prey when foraging in shallow and/or frontal zones. This study highlights the usefulness of the sonar tag, deployed on deep-diving elephant seals, to link thermohaline conditions and phytoplankton community composition in mid-trophic levels. Our result suggests that in addition to phytoplankton biomass, mid-trophic level abundance and distribution might be key factors in influencing top-marine predator foraging performances
