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Sameness of mode of presentation
No full textInternational audienceAccording to the Fregean ‘criterion of difference’ for modes of presentation, if it is possible for a rational subject to believe an object o to be F and, at the same time, to believe o not to be F, then there are distinct modes of presentation m and m’ such that the subject believes o to be F under m and disbelieves o to be F under m’. Several authors object that the criterion is unduly restricted to the point of view of a single subject at a single time. A new criterion is offered, which makes room for modes of presentation shared across times or across subjects
Inhibiting the JAK-STAT3 pathway in nucleus accumbens astrocytes alleviates cocaine-induced motor hyperactivity
No full textInternational audienceCocaine use disorder is a significant global health issue, and despite its widespread impact, effective treatments are lacking. While research has largely focused on the underlying neuronal mechanisms, the role of astrocytes, key regulators of synaptic transmission and plasticity, remains underexplored. Using a multidisciplinary approach that combines immunohistochemistry, electron microscopy, 3D cell reconstruction, viral gene transfer, and behavioral assays, we investigated the early adaptive responses of astrocytes to repeated cocaine administration. We report that cocaine administration induces astrocyte reactivity in the nucleus accumbens, characterized by structural remodeling, reduced synaptic coverage, and upregulation of reactivity-associated markers, including STAT3. Furthermore, we demonstrated that the JAK/STAT3 signaling pathway plays a critical role in the pathological structural astrocytic responses and in the cocaine-induced motor behavior. Our findings highlight astrocytes as pivotal players in the initial neural adaptations underlying cocaine-induced behavior. These data may provide a basis for the development of novel therapeutic strategies targeting astrocytes to address the structural and functional disruptions associated with cocaine exposure
Coccoliths as Recorders of Paleoceanography and Paleoclimate over the Past 66 Million Years
No full textInternational audienceCoccolithophores are a major group of oceanic calcifying phytoplankton, and their calcite skeletal remains, termed calcareous nannofossils, are a major component of deep-sea sediments accumulating since the Jurassic. Coccolithophores play a role in both the biological pump and the carbonate pump, exporting organic and inorganic carbon, respectively, out of the surface ocean. This means that they are key responders to and recorders of ocean carbon cycle and climate changes over geological and shorter timescales, and studying these responses can help elucidate the uncertain fate of calcifying phytoplankton under projected climate change scenarios. Here, we review established and emerging approaches for reconstructing ( a ) mixed-layer ocean temperature, ( b ) marine productivity, and ( c ) aspects of the ocean carbon cycle, using calcareous nannofossils from deep-sea sediments. For each parameter, we discuss the different proxies that have been proposed, based on abundance or species composition, inorganic geochemistry, and/or coccolith morphology, and explore their applications and limitations in Cenozoic paleoceanography
Corrigendum à « Taux de retour énergétique du bouquet électrique : l’impact des sources intermittentes » [C. R. Chim. 28 (2025), pp. 465-480. doi : 10.5802/crchim.396]
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Kinematics of mountain-building of the Central Andes, from structural geology to analogue modeling
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- Un psaume pour témoignage, le paume 73. Situation d’énonciation et effet perlocutoire du psaume 73 »: Situation d’énonciation et effet perlocutoire du psaume 73
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Compte rendu de Peter Franz Mittag: Geschichte des Hellenismus. Berlin/Boston: De Gruyter 2023. XIV, 334 S. (Oldenburg Grundriss der Geschichte 51).
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« Une possibilité de « noir » dans la littérature japonaise de l’entre-deux-guerres ? »
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Développement de nouvelles méthodes pour l'étude des biomarqueurs dans les sédiments - vers une analyse durable des archives archéologiques et climatiques
No full textInternational audienceThe ecoSCience project, collaboration between CEREGE, the M2P2 laboratory at Aix-Marseille University and Innovation Fluides Supercritiques, aims to develop ecological methods for studying organic biomarkers in sediments. In the field of paleoenvironmental science, their characterization helps to better understand climate change. In archaeology, the organic matter preserved in cave sediments is also essential for reconstructing the lifestyles of ancient populations. However, it is often preserved in very small quantities and trapped in a predominantly inorganic substrate. It may also have undergone significant diagenetic processes over time, making it particularly difficult to extract and characterize. Traditionally, the analysis of organic matter preserved in sediments has relied on extractions using large quantities of organic solvents, followed by analysis by chromatography and mass spectrometry. Although efficient, the use of toxic solvents remains a major ecological problem for these analytical approaches. Faced with these challenges, the use of supercritical fluids, in particular CO2, represents a promising alternative. Indeed, supercritical CO2 has unique solvation properties. Technologies such as supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) can therefore help reduce the ecological footprint of analyses. While SFE has already found applications in the study of sediments, SFC remains little exploited.This paper presents the methodologies that have been implemented using supercritical fluids to extract organic matter preserved in archaeological sediments from the Portel-Ouest site (Ariège), as well as the initial results of the characterization of these extracts by SFC-MS.Le projet ecoSCience, fruit d'une collaboration entre le CEREGE, le laboratoire M2P2 à Aix-Marseille Université et Innovation Fluides Supercritiques, vise à développer des méthodes écologiques pour étudier les biomarqueurs organiques dans les sédiments. Dans le domaine des sciences paléoenvironnementales, leur caractérisation permet de mieux comprendre les changements climatiques. Dans le domaine archéologique, la matière organique préservée dans les sédiments de grottes est également essentielle pour reconstruire les modes de vie des populations anciennes. Cependant, elle est souvent préservée en très faible quantité et piégée dans un substrat majoritairement inorganique. Elle peut également avoir subi d’importants processus diagénétiques au cours du temps, rendant son extraction et sa caractérisation particulièrement difficiles. Traditionnellement, l’analyse de la matière organique préservée dans les sédiments repose sur des extractions utilisant d’importantes quantités de solvants organiques, suivies d’analyses par chromatographie et spectrométrie de masse. Bien que performantes, l’usage de solvants toxiques reste un problème écologique important pour ces approches analytiques. Face à ces défis, l’utilisation de fluides supercritiques, notamment le CO2, représente une alternative prometteuse. En effet, le CO2 supercritique présente des propriétés de solvatation uniques. Les technologies telles que l’extraction par fluide supercritique (SFE) et la chromatographie par fluide supercritique (SFC) permettent donc de réduire l’empreinte écologique des analyses. Alors que la SFE a déjà trouvé des applications dans l’étude des sédiments, la SFC reste encore peu exploitée.Cette communication présente les méthodologies qui ont été mises en œuvre grâce aux fluides supercritiques pour extraire la matière organique préservée dans les sédiments archéologiques du site du Portel-Ouest (Ariège) ainsi que les premiers résultats de la caractérisation de ces extraits par SFC-MS