HAL Collection UNC (Univ. de la Nouvelle Calédonie)
Not a member yet
7579 research outputs found
Sort by
Investigating hydrological modeling uncertainties in the Mediterranean region by combining precipitation and soil moisture products
No full textInternational audienc
Scleractinian Coral Skeletons as Natural Archives of Global Change: A Cross-Disciplinary Investigation
No full textInternational audienceScleractinian coral skeletons serve as valuable environmental archives, offering key insights into past climate and ocean variability. Understanding the mechanisms underlying coral calcification is essential for reconstructing accurate paleoenvironmental records. However, calcification is a complex process regulated by both biological and environmental factors. This study explores the interplay between coral skeletal geochemistry and physiological processes, focusing on species-specific growth patterns, biomineralization dynamics, and the impact of diagenesis. We highlight the use of elemental ratios (e.g., Mg/Ca, Sr/Ca, Li/Mg) as proxies for environmental reconstructions while addressing biases introduced by skeletal heterogeneity, bioerosion, and secondary mineral precipitation. Additionally, we discuss how physiological traits, such as symbiosis, nutrient uptake, and respiration, influence calcification and may affect the preservation of geochemical archives over time. The integration of high-resolution geochemical analyses with biological insights is of great importance for refining paleoenvironmental proxies and enhancing the accuracy of climate reconstructions. This multidisciplinary approach provides a broader perspective on coral biomineralization, a critical issue for assessing reef resilience in a changing ocean
MLKAPS: Machine Learning and Adaptive Sampling for HPC Kernel Auto-tuning
No full textInternational audienceMany High-Performance Computing (HPC) libraries rely on decision trees to select the best kernel hyperparameters at runtime,depending on the input and environment. However, finding optimized configurations for each input and environment is challengingand requires significant manual effort and computational resources. This paper presents MLKAPS, a tool that automates this task usingmachine learning and adaptive sampling techniques. MLKAPS generates decision trees that tune HPC kernels’ design parameters toachieve efficient performance for any user input. MLKAPS scales to large input and design spaces, outperforming similar state-of-the-artauto-tuning tools in tuning time and mean speedup. We demonstrate the benefits of MLKAPS on the highly optimized Intel MKLdgetrf LU kernel and show that MLKAPS finds blindspots in the manual tuning of HPC experts. It improves over 85% of the inputswith a geomean speedup of ×1.30. On the Intel MKL dgeqrf QR kernel, MLKAPS improves performance on 85% of the inputs with ageomean speedup of ×1.18
Burying the Hatchet. Power-sharing and Citizen Inclusion in New Caledonia
No full textInternational audienc
SARRA, histoire d'un modèle de simulation des cultures pour les zones intertropicales
No full textInternational audienceThe SARRA (Regional Analysis System for Agroclimatic Risks) model family has been under development by the French Agricultural Research Centre for International Development (CIRAD) since the 1970s. Used in intertropical regions, the early versions of the model were designed to assess the impact of water stress—that is, the lack of accessible water for crops—on production and seedling losses. Their objectives were to improve riskestimation, optimize sowing management, and serve as a regional-scale early warning system for food security. Since the 2000s, the model has been increasingly used to analyze the impacts of climate change on agroclimatic risks. Several developments have enabled the integration of, on the one hand, the genetic characteristics of crops, and on the other hand, a better consideration of spatio-temporal dynamics, particularly through the use of remote sensing. Additionally, SARRA has gradually evolved from a descriptive model into a scenario-based anticipation tool, requiring structural transformations and the adoption of modern programming and versioning techniques to ensure traceability and reproducibility of simulations. Recognized for their simplicity, parsimony, and robustness, these models have proven effective for monitoring agricultural seasons, managing foodsecurity, and supporting decision-making in the face of climate risks. This article provides a retrospective analysis of their development, highlighting major innovations and their potential to guide resilient agricultural practices in response to current climate challenges.La famille de modèles SARRA (Système d'Analyse Régional des Risques Agroclimatiques) est développée par le CIRAD depuis les années 1970. Utilisées dans les régions intertropicales, les premières versions du modèle permettaient d'évaluer l'impact des stress hydriques, c'est-à-dire le manque d'eau accessible par la culture, sur sa production ainsi que les pertes de semis. Elles avaient pour objectif d'améliorer l'estimation des risques, la gestion des semis et de servir de système d'alerte à l'échelle régionale pour la sécurité alimentaire. À partir des années 2000, le modèle a été sollicité pour analyser les effets du changement climatique sur les risques agroclimatiques. Plusieurs évolutions ont permis d'intégrer, d'une part, les caractéristiques génétiques des plantes et, d'autre part, une meilleure prise en compte des dynamiques spatio-temporelles, notamment par le biais de la télédétection. Par ailleurs, SARRA a progressivement évolué d'un modèle descriptif vers un outil d'anticipation et de simulation de scénarios, nécessitant des transformations structurelles et l'adoption de techniques modernes de programmation et de versioning afin d'assurer la traçabilité et la reproductibilité des simulations.Reconnus pour leur simplicité, parcimonie et robustesse, ces modèles se sont avérés efficaces pour le suivi des campagnes agricoles, la gestion de la sécurité alimentaire et la prise de décision face aux risques climatiques. Cet article propose une rétrospective de leur développement et met en lumière les innovations majeures ainsi que leur potentiel pour guider des pratiques agricoles résilientes face aux défis climatiques actuels
A note on some Eocene benthic foraminifers of West and Central Iran, with remarks on palaeontology and biostratigraphy: Reply to Hadi and Schlagintweit comment (2024)
No full textInternational audienceThis article is a reply to the comment by Hadi and Schlagintweit (2024, Acta Palaeontologica Romaniae 2: 17–2) on the article by Babazadeh and Cluzel (2023, Bulletin de la Société Géologique de France 194: 1–24) about the internal structure and stratigraphic range of some benthic foraminifers from the Eocene carbonate deposits in the Shahr-e Kord and Mahallat regions of Iran. The comment focuses on the diagnosis of a limited number of species, and the introduction of new species of Eocene agglutinated foraminifers from the Mahallat region. In this reply, the disputed data are briefly reviewed and discussed in more detail. The interpretation of benthic foraminifers is based on their morphological variability and comparisons. Here the authors use re-illustrations of the types of nummulitids ( Nummulites ), orbitolinids ( Coskinolina , Daviesiconus, Coleiconus and Barattolites ), and other comparative material to confirm their determinations. Therefore, the hyaline foraminifers constitute the main subject of investigation, whereas the alveolinids are of secondary importance
L'apprentissage du français en contexte multiculturel: Les interférences linguistiques
No full textInternational audienceApprendre le français dans un contexte multiculturel et multilingue peut être un parcours du combattant pour l'enfant qui ne grandit pas avec cette langue à la maison. Comment l'aider à structurer efficacement son apprentissage de la langue attendue à l'école quand l'élève souffre d'un déficit d'interaction dans son entourage ? Comment l'aider lorsqu'il perçoit négativement ce que représente la langue standardisée
Pratiques agricoles et défis climatiques en Océanie : regards croisés entre sciences sociales et climatologie
No full textInternational audienceIn a context of marked climate change, agricultural practices and knowledge in the Pacific are undergoing profound transformations. Increasing climate variability, particularly concerning water resources, presents major challenges for local agri-food systems, raising questions of adaptation, resilience, and knowledge transmission. What strategies are local communities developing to adapt to these environmental changes? What are the current limitations and future challenges for agriculture in the face of these new water-related constraints?To explore these issues, IRD and Météo-France organized a scientific mediation event open to the general public. This event offered a cross-perspective between social sciences and climatology through several key moments:A visual presentation of how New Caledonian children perceive climate change, illustrating intergenerational perspectives on these transformations;A showcase of public speaking performances by young individuals engaged in defending their territories, highlighting the dynamics of social mobilization in response to environmental challenges;A discussion with a panel of researchers in social sciences and climate sciences, sharing their latest findings;A screening of the documentary Paradise in Peril, which examines the understanding of climatic phenomena in New Caledonia and the adaptation of lifestyles in response to these disruptions.Dans un contexte de changements climatiques marqués, les pratiques et savoirs agricoles du Pacifique font face à des mutations profondes. La variabilité climatique accrue, notamment en lien avec la ressource en eau, impose des défis majeurs aux systèmes agroalimentaires locaux, soulevant des questions d’adaptation, de résilience et de transmission des savoirs. Quelles sont les stratégies développées par les communautés locales pour s’adapter à ces transformations environnementales ? Quels sont les limites et les défis futurs pour l’agriculture face à ces nouvelles contraintes hydriques ?Afin d’explorer ces enjeux, l’IRD et Météo-France organisent une soirée de médiation scientifique ouverte au grand public. Cet événement a proposé un regard croisé entre sciences sociales et climatologie à travers plusieurs temps forts :Une restitution visuelle du ressenti des enfants calédoniens face au changement climatique, illustrant la perception intergénérationnelle de ces transformations ;Une mise en lumière des performances oratoires de jeunes engagés pour leur territoire, témoignant des dynamiques de mobilisation sociale face aux enjeux environnementaux ;Une discussion avec un panel de chercheurs en sciences sociales et en sciences du climat, partageant leurs résultats récents ;La projection du documentaire Paradis en péril, qui analyse la compréhension des phénomènes climatiques en Nouvelle-Calédonie et l’évolution des modes de vie face à ces bouleversements
Marine heatwaves imperil emblematic reef fishes by altering the energetic landscape of coral reefs
No full textInternational audienceMarine heatwaves are increasingly common due to human‐induced climate change. Under prolonged thermal stress on coral reefs, corals can undergo bleaching, leading to mass coral mortality and large‐scale changes in benthic community composition. While coral mortality has clear, negative impacts on the body condition and populations of coral‐dependent fish species, the mechanisms that drive these changes remain poorly resolved. Specifically, little is known about the effects of coral bleaching on (1) the nutritional quality of corals, (2) nutrient acquisition in coral‐feeding butterflyfishes and (3) fish dietary selectivity and potential supplementary consumption of non‐coral prey. Here, we evaluate the response of obligate coral‐feeding butterflyfishes to a mass coral bleaching event in French Polynesia, which resulted in high coral mortality and a 50% decline in obligate corallivore density. We examine benthic and butterflyfish community composition over two decades, including a mass bleaching event in 2019 and multiple prior disturbances. We couple these data with surveys of butterflyfish feeding selectivity, high‐resolution molecular assays of gut contents and nutrient acquisition before, during and after the bleaching event. Contrary to previous studies, obligate corallivores did not strongly alter their feeding preferences for different coral genera in response to bleaching. They did not increase their consumption of non‐corals in response to coral mortality, and hard corals continued to dominate their diets (>90%). Instead, butterflyfishes targeted partially bleached corals that were likely releasing nutrient‐rich mucus, and they avoided fully bleached and dead corals that were likely nutrient‐depleted. Moreover, after bleaching, butterflyfishes exhibit reduced nitrogen assimilation, indicating that coral stress may adversely impact butterflyfish nutrient acquisition. Coupled with the increasing frequency of recurrent bleaching events, severe, long‐term nutritional impacts of coral bleaching on butterflyfish populations may jeopardize the persistence of coral‐feeding fishes in the future
Construction et (dé)légitimation des savoirs et des représentations dans la gouvernance évolutive du “risque requin” (La Réunion)
No full textThis interdisciplinary study explores humanities and social sciences expertise commissionedand later contested by the State regarding shark risk in Réunion Island. The appointed expertimplemented a participatory framework with transformative aims and authored a novel toexpose power dynamics while circumventing institutional pressures. The dual communicationapproach (scientific expertise and literary narrative) is discussed with both the expert-authorand the state commissioning authority. Referring to the theory of evolutionary governance,this study illustrates how power-knowledge forms related to risk management are contestedand reconfigured in a context of public controversy.Cette étude interdisciplinaire porte sur une expertise en sciences humaines et socialescommanditée puis contestée par l’État, sur le risque requin à La Réunion. L’expert mandaté adéployé un dispositif participatif à visée transformative et rédigé un roman pour y révéler desrapports de pouvoir en contournant les pressions institutionnelles. Le double dispositifcommunicationnel (expertise scientifique et récit littéraire) est discuté avec l’expert-auteur etle commanditaire étatique. Se référant à la théorie de la gouvernance évolutive, cette étudeillustre comment des formes de pouvoir-savoir sur la gestion des risques sont contestées etreconfigurées dans un contexte de controverse publique