Science & Mathematics

Nous sommes face à un moment charnière pour l’agriculture française. L'installation, clé de voûte du renouvellement des générations connaît des évolutions qui interrogent l’accompagnement : profils des candidats diversifiés et peu familiarisés du secteur, aspirations différentes par rapport à nos aînés, nécessaire adaptation aux enjeux écologiques… Ces bouleversements mettent au défi les outils et dispositifs portés par les acteurs historiques de l’accompagnement à l'installation. Au moyen d’un traitement de données qualitatives issues d’entretiens menés auprès des acteurs de l’installation (PAI, Chambres d’agriculture, Adear, institutions de formation, conseil régional, banques, etc.), puis complétées grâce à la littérature existante, ce travail a pour but d’identifier les freins et leviers à l’installation en agriculture. Il a permis de constater le manque de coordinations entre d’un côté une action publique sur plusieurs niveaux et de l’autre une profusion de structures investies à la fois de certaines missions publiques et proposant des prestations relevant du secteur privé concurrentiel. Partant d’une commande de Fermes En ViE, entreprise dont la mission est de faciliter l’installation en agroécologie grâce à un financement solidaire, cette recherche a permis de faire évoluer le contenu de la plateforme La Grange. Il s’agit à la fois de l’enrichir d’outils supplémentaires permettant au candidat d’expérimenter et consolider la structuration technico-économique de son projet, et de créer de nouveaux contenus en coordination avec d’autres acteurs de l’accompagnement.

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24x36 mm, gélatine plan-film.

We introduce a regularization loss based on kernel mean embeddings with rotation-invariant kernels on the hypersphere (also known as dot-product kernels) for self-supervised learning of image representations. Besides being fully competitive with the state of the art, our method significantly reduces time and memory complexity for self-supervised training, making it implementable for very large embedding dimensions on existing devices and more easily adjustable than previous methods to settings with limited resources. Our work follows the major paradigm where the model learns to be invariant to some predefined image transformations (cropping, blurring, color jittering, etc.), while avoiding a degenerate solution by regularizing the embedding distribution. Our particular contribution is to propose a loss family promoting the embedding distribution to be close to the uniform distribution on the hypersphere, with respect to the maximum mean discrepancy pseudometric. We demonstrate that this family encompasses several regularizers of former methods, including uniformity-based and information-maximization methods, which are variants of our flexible regularization loss with different kernels. Beyond its practical consequences for state-of-the-art self-supervised learning with limited resources, the proposed generic regularization approach opens perspectives to leverage more widely the literature on kernel methods in order to improve self-supervised learning methods.

This paper presents the objectives and the research work carried out in the frame of the ANEMOS project on short-term wind power forecasting. The aim of the project is to develop accurate models that substantially outperform current state-of-the-art methods, for onshore and offshore wind power forecasting, exploiting both statistical and physical modeling approaches. The project focus on prediction horizons up to 48 hours ahead and investigates predictability of wind for higher horizons up to 7 days ahead useful i.e. for maintenance scheduling. Emphasis is given on the integration of high-resolution meteorological forecasts. For the offshore case, marine meteorology is considered as well as information by satellite-radar images. Specific modules are also developed for on-line uncertainty and prediction risk estimation. An integrated software platform, 'ANEMOS', is developed to host the various models. This system will be installed by several end-users for on-line operation at onshore and offshore wind farms for prediction at a local, regional and national scale. The applications include different terrain types and wind climates, on-and offshore cases, and interconnected or island grids. The on-line operation by the utilities will allow validation of the models and an analysis of the value of wind prediction for a competitive integration of wind energy in the developing liberalized electricity markets in the EU.

L’ENS "Marais et coteau de Voulangis" est situé sur la rive gauche du Grand Morin. Il recouvre 47 ha de boisements et d’espaces ouverts sur le versant nord et le lit majeur de la rivière. La diversité des habitats et des espèces du site répond aux enjeux du SDENS pour la préservation des vallées, des marais et des éléments de continuités écologiques. Le site abrite la plus forte richesse végétale parmi les sites évalués de la Brie boisée. Au total, 30 types de végétation et 279 espèces végétales ont été identifiés. On dénombre 10 espèces végétales à surveiller dont une espèce vulnérable à l’échelle régionale, une espèce protégée régionale, et neuf espèces très rares à rares dont deux sont déterminantes ZNIEFF. La zone humide et les praires de fauche constituent les principaux enjeux du site. Les orientations de gestion proposées permettront de maintenir et d’optimiser la richesse écologique du site. Cependant, c’est la gestion de la qualité des eaux et des sols du bassin versant qui détermineront, à long terme, la capacité à maintenir ou pas la zone humide fonctionnelle et diversifiée. De même, la consolidation d’un réseau de prairie de fauche en bon état de conservation doit être une priorité pour permettre la circulation et la survie des animaux inféodés à ces milieux.

This database supporting critical research into the history and media of fascism, is part of the REDIRE (Recorded Sound Propaganda of the Italian Fascist Regime) project, which has received funding from the European Union's Horizon 2022 research and innovation program under Marie Skłodowska-Curie grant agreement no. 101105514. The REDIRE database gathers information on over 900 records produced during the 20 years of the Italian Fascist regime (1922–1943) by record companies based in Italy. It is part of a research project into the use of the record by Fascist propaganda, which expressed the totalitarianism, imperialism, racism, political violence and cult of the leader, of the State that benefited from it. A tool for scientific investigation and the result of critical research into the history of the Italian Fascist regime (particularly its violent and criminal dimension), the REDIRE database is not intended to exist as a remembrance site for those nostalgic for this regime and the political movements that preceded or followed it. Texts explaining the connection of the records and their contents with the fascist imagination are offered as often as possible within the datasets, in order to better understand the construction and political aims of these propaganda recordings. The REDIRE database exhibits a surprisingly vast corpus of discs. By bringing this corpus to light, its aim is to better understand the history and functioning of Fascist sound propaganda. Firstly, it shows that the major international and Italian record companies, many of which continued to exist after the fall of the regime, participated massively in Fascist propaganda. Secondly, it questions what recorded sound propaganda is when it is conceived in a totalitarian context. In the REDIRE database, we find not only explicit recordings of political songs, but also implicit ones that accompany fascist policies or the fascist imaginary, without actually referring to them. These recordings testify to fascism's ability to invade all aspects of life in an attempt to shape it strictly according to its ideological framework. The REDIRE database thus shows the thematic scope of Fascist sound propaganda, or rather the declension of the same imaginary in the fields of schooling, the First and Second World Wars, the wars in Ethiopia and Spain, the founding of the Empire (Italian East Africa), Italian civilization, and so on. The REDIRE database is not exhaustive (some records have disappeared or been missed), and may contain errors, particularly as concerns dates. Its sources (record catalogs, newspapers, library catalogs) are sometimes vague. Yet it opens up a perspective on how records were used to infuse politics into Italian mass sound culture. This is already the case through the style of propaganda songs; music that is often light, joyful, mixed with military accents, sung by men with proven lyrical skills and accompanied by fine orchestras. This is also the case with records featuring one of these propaganda songs on one side, and a non-political song on the other: as both are presented on the record as equivalent, the non-political song naturalizes the political song and, in turn, naturalizes fascism. The REDIRE database and the project it is part of therefore aim to better consider the record and phonographic practices in research on Italian fascism and its mode of existence, as well as the political agentivity of sound and sound media. The database is freely accessible, and is open to suggestions and corrections from those who consult it.

The reactivities of olivine and serpentine towards mixture of chlorine in air, nitrogen and carbon monoxide were studied in non-isothermal conditions up to 1000°C. The samples were also chlorinated in a horizontal reactor over 2 h between 500° and 1000°C, under oxidizing and reducing atmospheres. The chlorination products were examined by XRD and SEM. The iron-bearing compounds contained in the natural olivine and serpentine samples can be eliminated through chlorination or oxychlorination of these solids at temperatures lower than 900°C. Carbochlorination of olivine and serpentine is incomplete even at 1000°C for a reaction time of 2 h. Pure magnesium chloride can be recovered by cooling the gas phase at ca. 500°C.

The evolution of the airflow instantaneous structure over an unsteady breaking wave propagating in a group is measured in detail using the digital particle image velocimetry technique. It is found that the boundary-layer over a breaking wave, the steepest in the group, separates at a point close to the sharp crest and reattaches in the front slope of the following wave. During breaking, the evolution of the turbulent vorticity is essentially unsteady and the recirculation zone of the separated flow takes the form of a large well-organized vortex. Links between the wave-crest geometry and geometrical features of the separation bubble have been established.

This paper aims at providing a reconstruction of a general theory of reciprocity from Smith's works which provides both a descriptive and a normative account of reciprocity, and explains reciprocal behavior in bilateral relationships as well as the origin and evolution of social rules of reciprocity. I will show that this "Smithian" theory of reciprocity can explain several experimental results, generate previsions for new experiments and offer an interesting alternative to existing models of reciprocity and social preferences in economics. Smith offers a non-utilitarian, emotion-based and moral theory of reciprocity. We conclude in underlining how the idea of reciprocity is at the heart of Smith's theory of morality and of his moral egalitarianism.

Diatom production is mainly supported by the dissolution of biogenic silica (bSiO2) within the first 200 m of the water column. The upper oceanic layer is enriched in dissolved and/or colloidal organic matter, such as exopolymeric polysaccharides (EPS) and transparent exopolymeric particles (TEP) excreted by phytoplankton in large amounts, especially at the end of a bloom. In this study we explored for the first time the direct influence of TEP-enriched diatom excretions on bSiO2 dissolution. Twelve dissolution experiments on fresh and fossil diatom frustules were carried out on seawater containing different concentrations of TEP extracted from diatom cultures. Fresh diatom frustules were cleaned from the organic matter by low ash temperature, and fossil diatoms were made from diatomite powder. Results confirm that newly formed bSiO2 dissolved at a faster rate than fossil diatoms due to a lower aluminum (Al) content. Diatom excretions have no effect on the dissolution of the newly formed bSiO2 from Chaetoceros muelleri. Reversely, the diatomite specific dissolution rate constant and solubility of the bSiO2 were positively correlated to TEP concentrations, suggesting that diatom excretion may provide an alternative source of dSi when limitations arise.

Les Born Global sont des entreprises qui, dès leur inception, sont poussées à s’internationaliser rapidement. À travers une revue de littérature et une étude de terrain, ce mémoire de recherche M2 tentera de répondre à la question suivante : en quoi les entrepreneurs « Born Global » diffèrent-ils de leurs homologues « non Born Global » (conventionnels) pour ce qui est de la réussite du processus d’internationalisation ?

L'article aborde la problématique d'un SSO web en décrivant les apports de ce type d’architecture du point de vue de l’utilisateur et du point de vue du système d’information. Nous détaillerons le fonctionnement d’un SSO et le cas particulier des architectures multi tiers. Nous décrirons brièvement les spécificités de quelques projets de SSO développés par des universités. Enfin nous aborderons plus généralement la problématique de gestion des identités numériques interétablissement.