HAL Collection UNC (Univ. de la Nouvelle Calédonie)
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Invasive macroalgae shape chemical and microbial waterscapes on coral reefs
No full textInternational audienceOver the past decades, human impacts have changed the structure of tropical benthic reef communities towards coral depletion and macroalgal proliferation. However, how these changes have modified chemical and microbial waterscapes is poorly known. Here, we assessed how the experimental removal of macroalgal assemblages influences the chemical and microbial composition of two reef boundary layers, the benthic and the momentum. Chemical and microbial waterscapes were spatially structured, both horizontally and vertically, according to macroalgal dominance and boundary layers. Microbes associated with reef degradation were enriched in the boundary layers surrounding macroalgal-dominated substrata. Dominant macroalgae were surrounded by a distinct chemical pool of diverse lipid classes (e.g., diterpenoids and glycerolipids) and labile organic matter (e.g., organooxygen compounds), which diffused from algal tissues to boundary layers according to their polarity. Finally, our results highlighted strong co-variations between specific algal-derived metabolites and planktonic microbes, giving insight into their roles in coral reef functioning and resilience
Trophodynamics in Coral Reefs: Current Knowledge and Research Perspectives
No full textInternational audienceCoral reef trophodynamics is extremely complex and still poorly understood, while investigated for decades. Recent advances on organic matter sources, fluxes, trophic niches of species, and spatiotemporal variations of food webs are first summarized. Then, tools used in trophodynamics research are briefly documented, from traditional pioneer methods of stomach content analysis to more recent biochemical methods (stable isotopes, fatty acids, biochemical composition, metabolomics, DNA metabarcoding, etc.) and modeling approaches. Eventually, future challenges and perspectives are presented addressing the diverse scenarios of coral reef trophic functioning response in front of the ongoing changes in global and local stressors
EM-SEC: Efficient Multi-head Set-valued Evidential Classification
No full textInternational audienceIn machine learning and deep learning, uncertainty quantification helps to accurately assess a model's confidence in its predictions, enabling the rejection of uncertain outcomes in safety-critical applications. However, in scenarios involving AI-assisted decision-making, proposing multiple plausible decisions can be more beneficial than either not making any decisions or risking incorrect ones. Set-valued classification is a relaxation of standard multiclass classification where, in cases of uncertainty, the classifier returns a set of potential labels instead of a single label. Current methods for set-valued classification often suffer from high computational complexity or fail to adequately quantify uncertainty. In this paper, we introduce a novel, computationally efficient approach to set-valued classification leveraging evidential deep learning and subjective logic, explicitly providing a measure of classification uncertainty. Our method employs a dual-head architecture: one head conducts multiclass evidential classification, while the other suggests candidate label sets when uncertainty is high. The proposed approach has linear worstcase computational complexity with respect to the number of classes. Extensive evaluation on several benchmark datasets demonstrates that our method showcases comparable performance to baseline set-valued methods, while being up to 23 times faster at inference on the benchmark datasets
Poétique, narrations et stratégies politiques dans l’œuvre de Déwé Gorodé
No full textInternational audienceThe Kanak independence movement is characterized by an interplay between politics and culture, a dynamic that sheds light on the significance of Déwé Gorodé’s entry into fiction starting in 1994. Through her poetry and narratives, Déwé Gorodé engaged in what she called the “revisitation of history” (Stefanson, 1998). Her poetic collection Sous les cendres des conques (1985), the short stories in Utê Mûrûnû, petite fleur de cocotier (1994), and the historical novel Tâdo Tâdo Wéé ! ou « No more baby » (2012) weave together an intimate and collective account of Kanak independence claims. These three works mark transitional moments in both literature and politics: the shift from poetry to narrative and a form of political reckoning through the historical novel. How does fiction engage with politics? This paper explores Déwé Gorodé’s work, first analyzing it as a document and an act of repair. Secondly, we will examine how narration and fiction serve as tools for social and political modeling.Le mouvement indépendantiste kanak se caractérise par une articulation entre le politique et le culturel dont la description permet de saisir les enjeux de l’entrée de Déwé Gorodé dans la fiction à partir de 1994. Par sa poésie et ses récits, Déwé Gorodé a procédé à ce qu’elle a nommé la « revisitation de l’histoire » (Stefanson, 1998). Le recueil poétique Sous les cendres des conques (1985), les nouvelles du recueil Utê Mûrûnû, petite fleur de cocotier (1994) et le roman Tâdo Tâdo Wéé ! ou « No more baby » (2012) déroulent un récit intime et collectif de la revendication indépendantiste kanak. Ces trois œuvres marquent des moments de transition tant littéraire que politique : le passage de la poésie au récit et une forme de bilan de l’action politique à travers le roman historique. Comment les fictions pensent-elles la politique ? Nous explorerons l’œuvre de Déwé Gorodé en l’analysant d’abord comme document et réparation. Dans un deuxième temps, nous verrons comment la narration et la fiction servent d’outils de modélisation sociale et politique
Shift in phytoplankton community composition over fronts
No full textInternational audienceOceanic fronts often support enhanced phytoplankton biomass. Yet, how fronts influence thecomposition of phytoplankton communities remains poorly understood. Here, we leverage 18 years ofhigh-resolution satellite data of sea-surface temperature and ocean color-derived pigments,converted into concentrations of seven phytoplankton groups, including diatoms, prokaryotes, andfive other eukaryotic groups, to examine changes in phytoplankton community composition overfronts across oligotrophic to eutrophic conditions in the Northwest Atlantic. We found a populationshift towards more diatoms and less prokaryotes at fronts, while the change in proportion of the othereukaryotic groups varies. This shift accounts for up to a half of the large-scale community dissimilarity,underscoring the substantial influence of fronts on phytoplankton community composition. Ourfindings suggest that fronts may serve as natural diatom refuges in a warming climate, highlighting thenecessity of incorporating fine-scale oceanographic features like fronts into climate models
Construction et (dé)légitimation des savoirs et des représentations dans la gouvernance évolutive du « risque requin » (La Réunion)
No full textNational audienceThis interdisciplinary study explores a humanities and social science expertise commissioned and later contested by the State regarding shark risk in Réunion Island. The appointed expert implemented a participatory framework with transformative aims and authored a novel to expose power dynamics while circumventing institutional pressures. The dual communication approach (scientific expertise and literary narrative) is discussed with both the expert-author and the state commissioning authority. Referring to the theory of evolutionary governance, this study illustrates how power-knowledge forms related to risk management are contested and reconfigured in a context of public controversy.Cette étude interdisciplinaire porte sur une expertise en sciences humaines et sociales commanditée puis contestée par l’État, sur le risque requin à La Réunion. L’expert mandaté a déployé un dispositif participatif à visée transformative et rédigé un roman pour y révéler des rapports de pouvoir en contournant les pressions institutionnelles. Le double dispositif communicationnel (expertise scientifique et récit littéraire) est discuté avec l’expert-auteur et le commanditaire étatique. Se référant à la théorie de la gouvernance évolutive, cette étude illustre comment des formes de pouvoir-savoir sur la gestion des risques sont contestées et reconfigurées dans un contexte de controverse publique
The European Prospective Investigation into Cancer and Nutrition Cohort (EPIC): a gateway to rare cancer epidemiological research
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Hacia una alfabetización crítica de la IA en la enseñanza de idiomas: antropomorfización, descolonización del conocimiento y agencia distribuida en contexto plurilingüe
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Compression optimisée des CNNs par élagage sous contrainte spatiale
No full textInternational audienceL’article présente un nouveau critère d’élagage des filtres adapté aux modèles profonds générant des images. Contrairement aux approches traditionnelles qui se basent sur l’intensité des pixels dans les activations intermédiaires, la méthode proposée prend en compte la position des pixels dans l’image et utilise des masques binaires pour distinguer les zones essentielles (objets) et l’arrière-plan. Cette technique permet d’évaluer l’importance des filtres en tenant compte des zones significatives dans les “feature maps”. L’article compare plusieurs critères d’élagage, démontrant que notre approche permet d’atteindre des taux de compression élevés tout en maintenant une faible erreur quadratique moyenne sur les images reconstruites
Les impacts de l’évolution culturelle et alimentaire sur l’obésité en Polynésie française
No full textInternational audienceThis article examines the impact of cultural and dietary change on obesity in French Polynesia. It highlights the socio-cultural and economic transformations that have altered the population's eating habits, leading to a high prevalence of obesity and associated metabolic disorders. The arrival of Europeans and colonisation introduced Western consumption patterns, different social norms and a cash economy, leading to a rapid transition to a sedentary lifestyle. This transition was exacerbated by the massive importation of processed foods of low nutritional quality, amplifying the obesity epidemic. Combating obesity in French Polynesia requires a multi-dimensional approach, coordinating medical, educational and political interventions to prevent and manage this condition. Political and economic challenges must be overcome in order to promote effective public health policies that have lasting benefits for the population.Cet article examine l'impact de l'évolution culturelle et alimentaire sur l'obésité en Polynésie française. Il met en lumière les transformations socioculturelles et économiques ayant modifié les habitudes alimentaires de la population, favorisant la prévalence élevée d'obésité et de troubles métaboliques associés. L'arrivée des Européens et la colonisation ont introduit des modèles de consommation occidentaux, des normes sociales différentes et une économie monétaire, entraînant une transition rapide vers un mode de vie sédentaire. Cette transition a été exacerbée par l'importation massive de produits alimentaires transformés de faible qualité nutritionnelle, amplifiant l'épidémie d'obésité. La lutte contre l'obésité en Polynésie française nécessite une approche multidimensionnelle, coordonnant les interventions médicales, éducatives et politiques pour prévenir et gérer cette condition. Les défis politiques et économiques doivent être surmontés pour promouvoir des politiques de santé publique efficaces et durablement bénéfiques pour la population