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Henri Daras_Philippe Boisnard, “IA AUTO STOP-® la fin du jour“
No full textFor La Nuit Européenne des Musées 2025, Philippe Boisnard is producing an AI-generated work, based on Henri Daras's painting “Femme pleurant à la fin du jour”, painted around 1918 (-! Oil on canvas, canvas, 71 x 65 cm, frame: 91.5 x 82.8 cm !-), housed at the Musée des Beaux-Arts in Angoulême, Charente (France). His work, “The Latentspace of the Off-screen” - which I'm inclined to ®-NOMMER “IA AUTO STOP-® la fin du jour” - questions the off-screen nature of painting...À l'occasion de La Nuit Européenne des Musées 2025, Philippe Boisnard produit une œuvre générée par IA, à partir de la peinture de Henri Daras, “Femme pleurant à la fin du jour“, peinte vers 1918 (-! Huile sur toile, toile, 71 x 65 cm, cadre : 91,5 x 82,8 cm !-), conservée au Musée des Beaux-Arts d'Angoulême, Charente (France). Son œuvre, “The Latentspace of the Off-screen“ — que j'aurai tendance à ®-NOMMER “IA AUTO STOP-® la fin du jour“ interroge ce hors-champ de la peinture..
Zurbarán, Painter of Spirituality?
No full textInternational audienceWas Zurbarán a Painter of Spirituality, and in what way? Can we say his painting was mystic? On the occasion of the exhibition (Supernatural) Zurbarán, held at the Museu Nacional d'Art de Catalunya in March-June 2025, this article of the catalogue discusses the religiosity of the Master born in Extremadura in 1598. He has long been presented as an interpret of the Counter-Reformation
Les professeurs d'école normale et l'universitarisation de la formation des maitres en France
No full textUne publication des actes est en préparationInternational audienceTeacher training college teachers originally came from the primary education system and were trained at the primary teacher training colleges in Fontenay and Saint-Cloud. There, they interacted with academics, but until the mid-twentieth century, their target audience consisted solely of primary school teachers.During the 1960s, a dual requirement emerged: the university-based training of primary school teachers and the professionalization of secondary school teacher training.In the 1980s, the recruitment of primary school teachers increased from post-baccalaureate to baccalaureate plus two years of university. Meanwhile, primary teacher training colleges had competed for a university degree: the DEUG (first-level university diploma).However, during the creation of the University Institutes for Teacher Training (IUFM), the integration of teacher training college teachers into the new institutes was hotly debated.Les professeurs d'école normale sont à l'origine issus de la filière primaire et formés dans les écoles normales supérieures primaires de Fontenay et Saint-Cloud. Ils y sont en contact avec des universitaires, mais leur public est jusqu'au milieu du vingtième siècle uniquement constitué d'enseignants du primaire. Durant la, décennie des années 1960 une double exigence apparait : l'universitarisation de la formation des enseignants du premier degré et la professionnalisation de la formation des enseignants du secondaire.Dans les années 1980, le recrutement des enseignants du premier degré s'élève de post-bac à bac plus 2 années à l'université, entre temps les écoles normales primaires avaient concouru à un diplôme universitaire : le DEUG premier degré.Pourtant lors de la création des Instituts universitaires de formation des maitres (IUFM), l'intégration des professeurs d'école normale dans les nouveaux instituts a été âprement discutée
Seasonality Alters Soil Organic Matter Properties in Alpine and Subalpine Grasslands
No full textInternational audienceAlpine and subalpine grasslands experience strong seasonal climatic variations, with snow cover for over six months maintaining steady soil temperature and moisture. This seasonal structure limits plant growth and strongly influences microbial activity, which together control key ecosystem functions like soil organic matter (SOM) inputs, mineralization, and greenhouse gas fluxes, ultimately influencing the composition and quantity ofSOM. In our study, we monitored soil pedoclimate (temperature and moisture) and net ecosystem exchange (CO2 flux) at both plot and local footprint scales, using discrete measurements and flux tower, to characterize the seasonal context of alpine and subalpine grasslands. Meanwhile, we investigated the seasonal properties of topsoil organic matter (SOM) at six key times throughout the hydrological year: before snow cover, beforesnowmelt, after snowmelt, during the growing season, at vegetation peak, and during senescence. SOM properties were analyzed through the combination of methods including DRIFT spectroscopy, RockEval thermal analysis, water-extractable organic carbon and permanganate-oxidizable carbon (POxC). Finally, soil incubations were conducted to assess microbial respiration sensitivity to temperature and moisture across these six periods,enhancing our understanding of seasonality’s impact on microbial features. Our study integrates in situ and in vitro measurements across multiple scales (soil sample, plot, and landscape), traditionally analyzed separately. This approach bridges microbial mechanisms with SOM quality and links them to ecosystem-scale carbon exchanges. Our findings highlighted a clear seasonality in SOM properties, offering valuable insights into thefunctioning of these grasslands. We identified a labile seasonal pool of SOM that persists through the winter due to low temperatures and low-carbon outputs, maintaining its availability for mineralization at the onset of the growing season—when primary producers have the highest nutrient demand. This labile pool decreases over the growing season, as microbial activity peaks and organic matter inputs decline. Additionally, seasonal shifts in microbial responses to temperature and humidity indicate functional acclimations: enhanced cold tolerance in winter, waterlogged tolerance during snowmelt, and increased capacity to degrade complex organic molecules during the growing season
Multispecies expression of coccolithophore vital effects with changing CO2 concentrations and pH in the laboratory with insights for reconstructing CO2 levels in geological history
No full textInternational audienceThe coccolith sedimentary and micropalaeontological archive has fostered great interest in palaeoclimate applications. Indeed, the geochemistry of coccolith calcite has the potential to reconstruct both palaeo-CO2 concentrations and palaeo-temperature of seawater. Studying coccolith geochemistry aims at better understanding the changes in the vital effect of coccoliths with changes in environmental parameters, especially the carbonate chemistry of seawater. To this aim, we need to deconvolve the biological imprint from the environmental signals recorded in the composition of coccoliths. We have undertaken culture experiments of four coccolithophore strains with various sizes and growth rates, grown under eight CO2/pH conditions typifying the CO2 evolution of the Cenozoic era. We propose an assessment of the expression of the vital effects for Emiliania huxleyi, Gephyrocapsa oceanica, Helicosphaera carteri and Coccolithus braarudii with simultaneous changes in dissolved inorganic carbon (DIC) and pH in the medium resulting in variations in dissolved CO2 (CO2 aq) availability to the cells. We have identified a distinct isotopic response of C. braarudii to pCO2 levels on both sides of the 600 ppmv (pH 7.89) condition. We propose that this discrepancy is the result of a modification of the proton efflux across the plasma membrane through voltage-dependent proton channels. We further show that as the CO2 level rises and pH decreases (from 200 to 500 ppmv and from 8.29 to 7.96 pH units, respectively), a significant increase in δ13Ccoccolith of C. braarudii is expressed, along with a coeval decrease in δ13Corg. The constant physiological parameters of C. braarudii (growth rate, particulate inorganic carbon (PIC) and particulate organic carbon (POC)) across the 200 to 500 ppmv interval support the idea that the change in δ13Ccoccolith is the consequence of a lower fractionation between dissolved CO2 and organic matter. Meanwhile, the small cells of E. huxleyi and G. oceanica are less carbon-limited and do not exhibit any change in their carbon vital effects with changes in carbonate chemistry of the environment across the whole CO2 spectrum. Using this biogeochemical framework, we have established a calibration between CO2 aq concentration and the differential vital effect (Δδ13C) between isotopically invariant small G. oceanica and large coccoliths C. braarudii, whose vital effect is CO2-dependent at low CO2. The CO2–Δδ13C transfer equation allows palaeo-pCO2 reconstructions based on isotope changes explained by physiological processes, especially at low and medium CO2 levels
Euclid. IV. The NISP Calibration Unit
No full textInternational audienceThe near-infrared calibration unit (NI-CU) onboard Euclid's Near-Infrared Spectrometer and Photometer (NISP) is the first astronomical calibration lamp based on light-emitting diodes (LEDs) to be operated in space. Euclid is a mission in ESA's 'Cosmic Vision 2015-2025' framework, to explore the dark universe and provide a next-level characterisation of the nature of gravitation, dark matter, and dark energy. Calibrating photometric and spectrometric measurements of galaxies to better than 1.5% accuracy in a survey homogeneously mapping ~14000 deg^2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties, as well their constant monitoring in flight. To cover two of the main contributions - relative pixel-to-pixel sensitivity and non-linearity characteristics - as well as support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (<12% variations) and temporally stable illumination (0.1%-0.2% over 1200s) over the NISP detector plane, with minimal power consumption and energy dissipation. NI-CU is covers the spectral range ~[900,1900] nm - at cryo-operating temperature - at 5 fixed independent wavelengths to capture wavelength-dependent behaviour of the detectors, with fluence over a dynamic range of >=100 from ~15 ph s^-1 pixel^-1 to >1500 ph s^-1 pixel^-1. For this functionality, NI-CU is based on LEDs. We describe the rationale behind the decision and design process, describe the challenges in sourcing the right LEDs, as well as the qualification process and lessons learned. We also provide a description of the completed NI-CU, its capabilities and performance as well as its limits. NI-CU has been integrated into NISP and the Euclid satellite, and since Euclid's launch in July 2023 has started supporting survey operations
La visibilité des mémoires déposés sur DUMAS : une question de discipline
No full textInternational audienceWhile they are usually not considered as important for the advancement of science, well-written electronic dissertations of Master students can prove useful for researchers, since they often cover hot topics and can foster the work of more advanced scholars. However, there must exist incentives to share one’s document. We hereby propose to explore through the social exchange theory one of the mechanisms that is likely to drive students to share their dissertation : its visibility, measured through the number of downloads. DUMAS, a French archive, gained momentum in the late 2000s. In 2023, it hosted more than 50 000 manuscripts. We scraped the metadata associated with the entire database, in order to better assess which disciplines were the more likely to attract attention. We show that dissertations from the management sciences scholarly consistently get the highest number of downloads, as the archive users seem to look for documents that are likely to be used in an applied manner. We analyze through the prism of Engeström’s activity theory the contradictions that can emerge from the possibility for students to acquire visibility via DUMAS within the academic environment as well as outside it.S’ils ne sont généralement pas considérés comme des écrits scientifiques de premier plan, les mémoires de Master de bonne qualité peuvent néanmoins se révéler utiles à la recherche, notamment car ils traitent souvent de sujets d’actualité et peuvent ce faisant accélérer le travail de chercheurs plus confirmés. Encore faut-il qu’il existe des leviers de motivations susceptibles d’inciter les étudiants à mettre à disposition leur travail. Nous nous proposons ici d’explorer au prisme de la théorie de l’échange social l’un des mécanismes qui poussent les étudiant.es à mettre en ligne leur mémoire dans des archives dédiées : la visibilité du travail partagé, mesurée sur la base du nombre de téléchargements du document. DUMAS, site français qui avait pris son essor à la fin des années 2000, centralisait en 2023 les manuscrits de plus de 50 000 étudiant.es. Via une technique de web scraping, nous avons collecté les métadonnées de l’ensemble ces manuscrits, pour mieux identifier les éléments qui déterminent la visibilité en ligne de ces travaux, tout en portant la focale sur les disciplines. Nous montrons que les travaux relevant des sciences de gestion, bien que minoritaires dans la base, sont ceux qui attirent le plus l’attention des internautes au fil des ans, qui, au sein du répertoire, semblent rechercher avant tout des écrits à visée praxéologique. Nous analysons au prisme de la théorie de l’activité d’Engeström les contradictions qui peuvent émerger de la possibilité pour les étudiants d’acquérir via DUMAS de la visibilité au sein du milieu académique comme en dehors de celui-ci
Weakening induced by phase nucleation: from experiments to numerical models
No full textInternational audienceMetamorphic transformations are often associated with strain localization which can be observed in the field either as ductile zones, or brittle, and possibly seismogenic, structures. Deformation experiments in the laboratory not only replicate such features but also allow us to measure the associated weakening. In all these contexts, reaction overstepping and disequilibrium metamorphism appear to be the rule. Reaction rates are usually very fast once transformation initiates, in particular within highly stressed and strained volumes where the produced mechanical work is sufficient to overcome kinetic barriers. New very fine-grained and dense phases nucleate in conditions where mineral growth is impeded. Understanding how heterogeneous nucleation, along with changes in density and viscosity, affects the rock's strength during a metamorphic transformation appears therefore critical.In that prospect, results of a 2D numerical study in which reaction products preferentially nucleate in areas of high strain energy are presented. Special attention is given to the weakening or hardening effects induced by these transformations, as well as to the deformation patterns within the model. Results of our numerical study are then discussed in the light of experimental data obtained at comparable pressure-temperature-strain rate conditions.We show that rock weakening is not only linked to the strength of the reaction products. Indeed, (1) densification alone can generate sufficient stress to induce plastic yielding of the surrounding matrix, even when the nuclei are stronger, and (2) heterogeneous nucleation controlled by mechanical work has greater influence on the rock’s strength than the intrinsic properties of the reaction products. Weakening is primarily driven by the initiation and propagation of plastic shear bands between the closely spaced nuclei that generate significant stress concentration in their vicinity. This study highlights the importance of transformational weakening that results from fast heterogeneous nucleation in rocks close to their brittle-ductile transition
On the role of transformation-induced physical changes on eclogite propagation: insights from thermo-mechanical numerical models.
No full textInternational audienceIn convergence zones, metamorphic transformations that affect the subducting lithosphere as due to changes in pressure and temperature significantly influence the mechanical behavior of rocks. For instance, eclogitization of lower crustal rocks, characterized by a notable densification has been associated with strain localization and seismic activity in several localities around the world. However, the mechanisms governing the propagation of this transformation once initiated remain insufficiently understood. In that prospect, this study investigates the process of eclogitization through thermo-mechanical numerical modeling, focusing on the deformation of an inclusion within a reactive matrix of different viscosity. This matrix-inclusion system is deformed under pure shear boundary conditions, and the physical properties of the initial materials evolve toward those of the transformation product in areas of the model where the pressure of the transformation is reached.A parametric analysis is conducted to assess the influence of a heterogeneous pressure field generated by mechanical heterogeneities on the initiation and propagation of the transformation. Our results show that pressure overstepping and initial viscosity of the material are key factors to trigger the transformation. Other parameters such as (1) density variations during the transformation, (2) the initial viscosity contrast between the matrix and the inclusion, and (3) the shape/orientation of the inclusion instead enhance or inhibit the propagation of the transformation. Additionally, our results show that the direction of the eclogite propagation is systematically perpendicular to the shortening direction. These results show striking similarities with field observations and structural analyses of finger-shaped eclogite fronts on the island of Holsnøy (Norway)
Mantle Exhumation and Post‐Rift Magmatism at an Oblique Magma‐Poor Continental Margin
No full textInternational audienceContinental breakup is a fundamental tectonic process, which leads to seafloor spreading and the generation of oceanic crust. However, the current understanding of continental margins, based largely on 2‐D seismic transects, is inadequate to capture the spatial complexity of crustal evolution. Here we present a 3‐D seismic velocity model through a young, magma‐poor margin at the north‐eastern Gulf of Aden. Our results highlight the 45° obliquity between the strike of crustal thinning and extension direction, which is accommodated by two transfer zones during the formation of the Continent‐Ocean Transition (COT). This obliquity causes the margin to be segmented, which predates seafloor spreading. Along strike, we find a progressive eastward crustal thinning from 13 to 5 km, corresponding to a V‐shaped COT. This eastward variation is characterized by (a) an eastward increase of mantle exhumation due to detachment faulting, and (b) post‐rift magmatism emplaced onto serpentinized mantle in the west