HAL - La Rochelle Université, Archives Ouvertes
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Egg Characteristics of Female Common Terns Are Repeatable, and Vary With Maternal Age and Laying Order
No full textInternational audienceAvian eggs exhibit striking variability in size, shape, colour, and maculation, not only among but also within species. Technical and analytical advances in image analysis offer the opportunity to understand the factors underpinning this variability, especially when individual-based longitudinal data are available. Making use of such data, collected over four years, we investigated sources of variation in eight egg characteristics capturing the colour, spottiness, shape, and size of 1589 eggs from 687 clutches produced by 330 female common terns (Sterna hirundo) of known age. We found a high repeatability of the eight egg traits, both within clutches (range 0.48-0.77), and among clutches of the same female laid in different years (range 0.48-0.73). We also observed a within-female increase in egg size and spottiness with age, and evidence for selective disappearance of females producing spottier eggs, suggesting that egg maculation could reveal female quality. We also found that the size and shape of eggs were affected by their laying order within the clutch, suggesting that these traits may mediate intra-brood competition. We suggest further studies to identify the specific agents of selection that shape variation in egg size and morphology, to fully understand the eco-evolutionary significance of this extended female phenotype and its potential consequences for reproductive success and offspring survival.</div
Irradiation-induced defect evolution in concentrated solid-solution alloys: a molecular dynamics perspective
No full textInternational audienceThis computational study delves into the intricate interplay of alloying elements on the generation, recombination, and evolution of irradiation-induced defects. Molecular dynamics simulations were conducted for collision cascades at room temperature, spanning a range of primary knock-on atom energies from 1 to 10 keV. The investigation encompasses a series of model crystals, progressing from pure Ni to binary concentrated solid solution alloys (CSAs) such as NiFe 20 , NiFe, NiCr 20 , and NiFeCr 20 CSA. We observe that materials rich in Cr actively facilitate dislocation emissions and induce the nucleation of stacking fault tetrahedra in the proximity of nanovoids, due to Shockley partial interactions. This result is validated by molecular static simulations, which calculate the surface, vacancy, and defect formation energies. Among the various shapes considered, the spherical void proves to be the most stable, followed by the truncated octahedron and octahedron shapes. On the other hand, the tetrahedron cubic shape is identified as the most unstable, and stacking fault tetrahedra exhibit the highest formation energy. Notably, among the materials studied, NiCr 20 and NiFeCr 20 CSAs stood out as the sole alloys capable of manifesting this mechanism, mainly observed at high impact energies
Rapport intermédiaire de la cartographie des produits de recherche de La Rochelle Université
No full textThis report provides an overview of current practices in open science within the university’s laboratories. In a context of growing demands for transparency and data sharing, the UCLR project supports the research community in improving the dissemination of its outputs, notably through a facilitation tool for deposits and an institutional catalogue listing research products.Three levels of development can be distinguished:1) Well-established practices, supported by dedicated data management services.2) Developing practices, showing positive momentum but still lacking human and organizational resources.3) Emerging practices, not yet established but driven by a clear willingness to grow.The report also highlights the specific case of codes and software, which are still rarely integrated into traditional repositories but are now included in the UCLR catalogue, in connection with national initiatives such as Software Heritage and HAL.Thus, the transition toward fully open science is well underway at La Rochelle Université. The objective for the second half of 2025 is to harmonize practices, strengthen training, and pool successful initiatives to enhance the visibility of scientific outputs.Ce rapport dresse un état des lieux des pratiques en matière de science ouverte au sein des laboratoires. Dans un contexte de montée en puissance des exigences de transparence et de partage des données, le projet UCLR accompagne la communauté scientifique vers une meilleure diffusion de ses productions, notamment grâce à un outil de facilitation du dépôt et un catalogue institutionnel recensant les produits de recherche.3 niveaux de développement se distinguent avec : 1) Des pratiques déjà bien établies, avec des services de gestion dédiés. 2) Des pratiques en cours de mise en place, avec une dynamique positive mais qui manquent encore de moyens humains et organisationnels. 3) Des pratiques non établies, mais une volonté de les développer sous peu.Ici est aussi soulignée la spécificité des codes et logiciels, encore peu intégrés dans les entrepôts classiques mais désormais pris en compte dans le catalogue UCLR, en lien avec les initiatives nationales (Software Heritage, HAL).Ainsi la transition vers une science pleinement ouverte est en marche à La Rochelle Université. L’objectif du second semestre 2025 est d’harmoniser les pratiques, de renforcer la formation et de mutualiser les bonnes initiatives pour une visibilité accrue des productions scientifiques
Generic passive-guaranteed nonlinear interaction model and structure-preserving spatial discretization procedure with applications in musical acoustics
No full textInternational audienceIn musical acoustics, the production of sound is usually described by the nonlinear interaction of the musician with a resonator (the instrument). For example a string (resonator) can be bowed or hit by a piano hammer (nonlinear interactions). The aim of this paper is to provide a stable (passive-guaranteed) simulation of such interaction systems. Our approach consists in first defining a generic passive-guaranteed structure for the interaction (finite dimensional) and for the resonator (infinite dimensional) and second constructing a generic procedure for the discretization of the resonator. This is achieved in the Port-Hamiltonian systems framework that decomposes a physical model into a network of energy-storing components, dissipative components and inputs-outputs, thus guaranteeing the passivity of the proposed models. Finally, a well established structure preserving time discretization method is used to provide numerical models which prove to fulfill a discrete power balance, hence the numerical stability. This generic procedure is applied to the sound synthesis of a bowed string and of a string hit by a piano hammer
Génération augmentée de récupération pour les journaux historiques
No full textNational audienceLa numérisation des archives historiques permet d’améliorer leur accessibilité et leur préservation à long terme, ouvrant ainsi de nouvelles perspectives de recherche interdisciplinaire. Cependant, l’ampleur des données disponibles pose des défis considérables. Diverses tâches de traitement automatique du langage naturel, telles que la reconnaissance d’entités nommées et la segmentation en articles, ont permis de faciliter l’accès du public en extrayant et structurant l’information. Néanmoins, l’agrégation des articles de presse historiques demeure largement inexplorée. Ce travail met en évidence le potentiel d’un cadre de génération augmentée de récupération (RAG), combinant des grands modèles de langage, un module de recherche sémantique et des bases de connaissances, pour agréger des articles de journaux historiques. Nous proposons également des métriques d’évaluation des systèmes génératifs ne nécessitant pas de vérité de terrain. Les premiers résultats de notre chaîne de traitement RAG sont prometteurs, démontrant que la récupération sémantique, renforcée par le reranking et la reconnaissance d’entités nommées, peut atténuer les erreurs d’océrisation et les fautes de frappe dans les requêtes
The PARES Database: Information Extraction over Historical Parish Records
No full textInternational audienceAbstract Historical census records convey information that is key to perform genealogical research and demographic studies. Given the large number of documents of this type that exist, it is crucial to research methods that allow the automatic extraction of information from this type of document. In this work, we present a new corpus of this kind, comprising 535 historical census tables from French archives. Alongside this dataset, we have assessed three different baseline methods for information extraction. The first two methods employ a traditional sequential approach, where table rows are detected before extracting information. The third baseline uses an end-to-end model that directly extracts information from the table images without prior row detection. Our results demonstrate the effectiveness of all three baselines in tackling the information extraction task
Les diplomaties euro-africaines au tournant des indépendances
No full textInternational audienceComment passer d’un rapport impérial, fortement polarisé par une métropole, à des relations plus équilibrées, qui s’inscrivent dans un cadre associant des diplomaties bilatérales et multilatérales ? La question se pose aux États africains nouvellement indépendants. Croisant une histoire des relations internationales et une histoire sociale du politique, ce livre explore les reconfigurations des diplomaties euro-africaines, alors que le continent s’insère dans un système international dominé par les enjeux de Guerre froide et reconfiguré par l’arrivée des pays du Tiers-Monde.La boîte à outils de l’historien permet d’envisager cette vaste question de manière empirique. Fruit d’une collaboration entre les Archives diplomatiques et Nantes Université, l’ouvrage dresse un état des lieux des fonds diplomatiques français concernant l’Afrique au tournant des indépendances. Le dialogue entre archivistes et historiens met en lumière la richesse de ces archives et nourrit une réflexion méthodologique quant à leur interprétation.L’ouvrage examine la combinaison de continuités et de ruptures qui caractérise la décolonisation des relations entre Europe et Afrique. Aux Nations Unies, les États africains doivent prendre en compte les antagonismes de la Guerre froide, et tentent de renforcer leur place par des regroupements continentaux (panafricanisme) ou transcontinentaux (non-alignement, afro-asiatisme). L’ouvrage interroge aussi les notions d’aide et de développement – idéaux centraux de l’après-guerre – qui structurent les ambivalences des relations euro-africaines
Temporal and Spatial Survey on the Abundance of Amoebae and Bacteria in an Estuary and the Role of Environmental Parameters
No full textInternational audienceFree‐living amoebae are phagotrophic protists that prey on bacteria. However, under certain conditions, some bacteria can resist phagocytosis and become pathogenic. Environmental parameters altered by climate change may impact amoebae and bacterial diversity, as well as their pathogenicity. In our study, we monitored amoebae and bacterial abundance both temporally, over 1 year, and spatially, along a river estuary, while also recording key environmental parameters. Naegleria was the most represented amoebae genus, present year‐round from the river to the estuary. Similarly, Vibrio was the most dominant bacterial genus. Salinity, and to a lesser extent dissolved oxygen, influenced amoebae and bacterial abundance. In particular, the genera Naegleria , Paramoeba , Pseudomonas and Legionella were the most affected. In conclusion, this study highlights the impact of salinity on amoebae diversity, suggesting that this parameter, as a key factor in coastal environments, will impact both amoebae and the associated bacterial communities
Predicting fisheries from albatross movements requires accounting for individual variability in interaction
No full textInternational audienceFisheries have major ecological impacts including bycatch of foraging seabirds, but it is often difficult to obtain comprehensive information on the presence of fishing vessels. Automatic Identification System (AIS) data can be used to monitor fisheries and their interactions with GPS-tracked seabirds, but not all vessels have their AIS operational. Bird-tied radar detectors can overcome this limit and complement monitoring, but the technology is recent and costly. We used both methods combined as a training dataset for classification algorithms, to extend the identification of interactions to GPS tracks without radar detectors nor AIS. We studied over 3 years wandering albatrosses from the French Southern Territories, interacting with toothfish and tuna longliners. We used 196 GPS tracks combined with radar detectors, to calculate different movement variables over various scales (time spent in an area, sinuosity, speed) and used a Random Forest to distinguish behaviour in presence or absence of fishing vessels. Our model reached high classification accuracy (ca. 85%) for individual birds included in the training dataset. However, we lost predictive power (around 72% of accuracy, with a drop of specificity from 76 to 59%) when predicting on individuals not included in the training dataset. Our results emphasize the importance of documenting and accounting for individual variations to use animals as sentinels. We discuss the pros and cons of different research avenues (data sampling, classification model, bird species, etc.) to eventually get to predict fisheries from bird movements only