HAL Portal UPF (Université de la Polynésie française)
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Equivalence of the Empirical Risk Minimization to Regularization on the Family of f-Divergences
No full textInternational audienceThe solution to empirical risk minimization with f-divergence regularization (ERM-fDR) is presented under mild conditions on f. Under such conditions, the optimal measure is shown to be unique. Examples of the solution for particular choices of the function f are presented. Previously known solutions to common regularization choices are obtained by leveraging the flexibility of the family of f-divergences. These include the unique solutions to empirical risk minimization with relative entropy regularization (Type-I and Type-II). The analysis of the solution unveils the following properties of f-divergences when used in the ERM-fDR problem: i) f-divergence regularization forces the support of the solution to coincide with the support of the reference measure, which introduces a strong inductive bias that dominates the evidence provided by the training data; and ii) any f-divergence regularization is equivalent to a different f-divergence regularization with an appropriate transformation of the empirical risk function
Freshwater fish otoliths record signals from both water and physiological processes: new insights from Sr/Ca and Ba/Ca ratios
No full textInternational audienceUsing strontium (Sr) and barium (Ba) in otoliths to determine natal origins and understand patterns of fish movements is based on the fundamental assumption that otoliths record water chemistry signals without any major alterations. Although prior studies highlighted that fish physiology can modify the water signal in otoliths, studies for freshwater fish are scarce. We exposed different groups of Atlantic salmon parr Salmo salar to different scenarios of ambient-level variations in Sr/Ca and Ba/Ca ratios and then combined otolith chemical profiles with environmental data (water chemistry and temperature), Fulton's index, and otolith growth rates to assess what factors explain/influence the elemental ratios of Sr and Ba in otoliths. Generalized additive mixed models (GAMMs) using water-based otolith composition, temperature, Fulton's index, and “individual” as explanatory variables allow to demonstrate that water chemistry alone cannot fully explain measured ratios in otoliths, except in scenarios involving significant changes in water chemistry. Other factors (physiological effects) should be accounted for reproducing short and minimal seasonal variations in water composition, considering that inter-individual variability contributes quite significantly in most scenarios
L’œil des puissances impériales en Polynésie française : l’espionnage du Centre d’expérimentation du Pacifique et des essais nucléaires atmosphériques de la France (1963-1974)
No full textInternational audienceCette intervention montrera de quelle manière les puissances impériales, c’est-à-dire les États dotés de la bombe réalisant leurs essais nucléaires dans leurs « marges » impériales, espionnent le Centre d’expérimentation du Pacifique (CEP) et les essais d’armes nucléaires en atmosphère de la France réalisés en Polynésie française entre 1963, date de l’implantation du CEP, et 1974, année de la dernière campagne de tir aérien. L’espionnage entourant le CEP et les expérimentations nous conduit à considérer la complexité et à nuancer le secret de cette pratique : l’espionnage est à la fois assumé et constaté, et permet à la France de montrer sa puissance auprès de ses alliés comme de ses adversaires, malgré les multiples faiblesses scientifiques et techniques que Paris tente de pallier en espionnant par ailleurs ses propres alliés. Ainsi, la dimension transnationale de la circulation des savoirs et des acteurs dépasse le cadre polynésien et prend toute sa place dans cette intervention. Une analyse multiscalaire de ces dynamiques est donc nécessaire, dans la mesure où certains Polynésiens, à l’échelle très locale, constatent cet espionnage, eux-mêmes soumis à une surveillance étroite de Paris
Quitter la politique. Fins de carrière politique en France (20e-21e siècle)
No full textInternational audienceÀ rebours des récits courants sur l’ascension de certains personnages politiques médiatisés, cet ouvrage collectif apporte une contribution importante à la compréhension des sorties et fins de carrières politiques en France à l’époque contemporaine. Il étudie de manière synthétique les fins de parcours soudaines ou progressives, désirées ou contraintes, de ces hommes et femmes (présidents, premiers ministres, parlementaires...) qui ont activement participé à la vie politique de la nation. Au croisement de l’histoire, de la science politique et de la sociologie, il s’appuie sur des études de cas et des analyses statistiques pour montrer les causes et la chronologie de ces départs, leurs raisons, leurs enjeux, leurs perceptions, les modalités de leur gestion et les éventuelles reconversions professionnelles consécutives
The gravity model for tourism flows: considering the nonhomothetic nature of demand
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The Update of ABS system in French Polynesia: A New Disappointement.: Reflection on Law n° 2023-11 of23 January 2023 amending the provisions relating to access to resources and the sharing of the benefits arisingfrom their development and various amendments to the French Polynesia Environment Code
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Bioactivity-Based Molecular Networking for the comparison of Calophyllum inophyllum (tamanu) oil obtained via three ecofriendly extraction processes
No full textInternational audienceTamanu oil, obtained from the seeds of Calophyllum inophyllum L. (Calophyllaceae), was traditionally used to cure various skin problems and ailments in French Polynesia (Pétard P, 1986). Nuts and especially oil are also used for skin care (Raharivelomanana et al., 2018). It was reported to treat different kinds of skin affections as well as conjunctivitis and used as natural cosmetic ingredient. Aiming to produce high quality tamanu oil from an eco-friendly process, ecological extraction of this oil from nuts had been carried out using different methods such as ultrasound- assisted and microwave-assisted extractions as well Soxhlet extraction using agro-solvents. Bioactivity-Based Molecular Networking was performed in order to compare their eco-extracts chemical composition and cytotoxic properties. Ultrasound assisted extraction seemed to be an innovative and interesting process to extract tamanu oil yielding a rich extract within bioactive compounds being responsible of its cytotoxic activity shown on different cancer cell lines (IC50< 0.1%V/V): HuH7 (liver), CaCo-2 (colon), MDA-MB-231 (breast), MDA-MB-468 (breast), HCT116 (colon), PC3 (prostate), MCF-7 (breast). The obtained results indicated that the tamanu eco-extracts can be used as an interesting source of natural ingredient for potential nutraceutical and cosmetic applications
Le droit de l'usufruitier de parts sociales de contester les délibérations susceptibles d'avoir une incidence directe sur son droit de jouissance
No full textInternational audienceNote sous Cour de cassation, civ. 3e, 11 juillet 2024, no 23-10.013 (no 418 FS-B
New insights into population structure, demographic history, and effective population size of the critically endangered blue shark Prionace glauca in the Mediterranean Sea
No full textInternational audienceThe blue shark, Prionace glauca, is the most abundant pelagic shark in the open ocean but its vulnerability remains poorly understood while being one of the most fecund sharks. In the Mediterranean Sea, the blue shark is listed as Critically Endangered (CR) by the International Union for Conservation of Nature. The species is facing a strong decline due to fishing, and scientific data regarding its genetic structure and vulnerability are still lacking. Here, we investigated the genetic diversity, demographic history, and population structure of the blue shark within the Mediterranean Sea, from samples of the Gulf of Lion and Malta, using sequences of the mtDNA control region and 22 microsatellite markers. We also compared our mitochondrial data to previous studies to examine the Atlantic-Mediterranean population structure. We assessed the blue shark's genetic vulnerability in the Mediterranean basin by modelling its effective population size. Our results showed a genetic differentiation between the Atlantic and the Mediterranean basins, with limited gene flow between the two areas, and distinct demographic histories making the Mediterranean population an independent management unit. Within the Mediterranean Sea, no sign of population structure was detected, suggesting a single population across the Western and Central parts of the sea. The estimated effective population size was low and highlighted the high vulnerability of the Mediterranean blue shark population, as the estimated size we calculated might not be sufficient to ensure the long-term persistence of the population. Our data also provide additional evidence that the Gulf of Lion area acts as a nursery for P. glauca, where protection is essential for the conservation strategy of the species in the Mediterranean