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Les crises politiques au prisme des trajectoires militantes dans le monde arabe et ses diasporas [dossier]
No full textQue font les crises politiques aux individus ? Comment les affectent-elles ? Le présent dossier dialogue avec les travaux sur le protagonisme et ceux sur les bifurcations et les reconversions militantes, pour étudier les incidences de tels moments sur les trajectoires biographiques. Qu’il s’agisse de militants « aguerris » ou d’individus ordinaires politisés dans et par l’évènement, les articles croisant histoire, sociologie et science politique, permettent tout aussi bien de saisir ce qui se joue dans ce moment de fluidité, que d’étudier comment celui-ci se traduit par la suite dans des réarrangements biographiques partiels ou globaux. Dans une perspective microsociologique attentive aux expériences, aux subjectivités et aux trajectoires, c’est le « je » du participant engagé dans la crise, et son inscription dans un « nous » collectif qui se prolonge au-delà de l’événement, qui sont mis en question ici. En entamant un dialogue entre la « petite » et la « grande » histoire, c’est la crise elle-même et son épaisseur sociale que nous proposons d’appréhender autrement
Showing the Patterns of Order: Framework and Method of Terashima Ryôan’s Illustrated Compendium of the Three Powers of Japan and China (Wakan sansai zue, c.1715)
No full textInternational audienc
Mithridate ou l'anamorphose d'un grand homme
No full textInternational audienceDans Mithridate, le dramaturge donne le spectacle d’une figure royale qui se décompose, rongée par une jalousie qui la pousse à faire un usage dévoyé de la ruse. Le roi du Pont suscite une forme de perplexité parce qu’il incarne une grandeur réelle, minée par des passions aux conséquences funestes. Si la tragédie instruit, c’est dès lors moins par des leçons de morale univoques que parce qu’elle propose le spectacle d’un monde complexe, sur lequel il faut exercer son esprit critique
Investigating Species Composition in the Early Aurignacian of Le Piage (France) Through Collagen Fingerprinting (ZooMS) of Screen-Recovered Small Bone Fragments
No full textInternational audienceIn the paleoproteomic field, ZooMS (Zooarchaeology by Mass Spectrometry) has been developed to identify morphologically non-diagnostic animal remains to taxon, offering insights into human subsistence practices. Here, we report new ZooMS analyses of 1,050 Early Aurignacian (ca. 37,000-34,000 cal BP) bone fragments from the site of Le Piage (Lot, France). The studied sample is heavily fragmented and was retrieved through water sieving. In our analysis, we compare the taxonomic identifications of bone remains using traditional morphological attributes with remains identified using ZooMS and discuss the implications of the taxonomic patterns. Our results indicate that the faunal spectrum identified through ZooMS differs from the species composition obtained through morphological analyses. While reindeer remains the dominant species, bovids and other cervids are better represented in the ZooMS fraction. Two rare taxa, a hare (Lepus sp.) and a previously unidentified carnivore (Pantherinae/Hyaenidae/Mustelidae), were also identified using ZooMS. We also observe an increase of Bos/Bison remains in the spongious assemblage that is possibly explained by the use of spongy portions of long bones as fuel. Our work adds new data on patterns of reindeer dominance during the Early Aurignacian and illustrates how ZooMS identifications of screen-recovered small bone fragments can enhance our understanding of Paleolithic site occupation and subsistence strategies
The Hund-metal path to strong electronic correlations
No full textInternational audienceA new type of metal has taken the scientific community by surprise. Classic concepts from atomic physics—the electrons’ orbitals and spin alignment—are key to understanding it
Frequency-dependent superconducting states from the two-time linear response theory: Application to Sr2RuO4
No full textInternational audienceWe investigate the possible superconducting instabilities of strongly correlated electron materials using a generalization of linear response theory to external pairing fields depending on frequency. We compute a pairing susceptibility depending on two times, allowing us to capture dynamical pairing and in particular odd-frequency solutions. We first benchmark this method on the attractive one-band Hubbard model and then consider the superconductivity of strontium ruthenate Sr2RuO4 within single-site dynamical mean-field theory, hence restricting ourselves to pairing states which are momentum independent in the orbital basis. The symmetry of the superconducting order parameter of this material is still debated, and local odd-frequency states have been proposed to explain some experimental discrepancies. In the temperature range studied, we find that the leading eigenvectors are odd-frequency intraorbital spin-triplet states, while the eigenvectors with the highest predicted transition temperature correspond to even-frequency intraorbital spin-singlet states. The latter include a state with d-wave symmetry when expressed in the band basis
Transport Equations and Flows with One-Sided Lipschitz Velocity Fields
No full textInternational audienceWe study first- and second-order linear transport equations, as well as flows for ordinary and stochastic differential equations, with irregular velocity fields satisfying a one-sided Lipschitz condition. Depending on the time direction, the flows are either compressive or expansive. In the compressive regime, we characterize the stable continuous distributional solutions of both the first and second-order nonconservative transport equations as the unique viscosity solution, and we also provide new observations and characterizations for the dual, conservative equations. Our results in the expansive regime complement the theory of Bouchut et al. (Ann Sc Norm Super Pisa Cl Sci (5) 4:1-25, 2005), and we develop a complete theory for both the conservative and nonconservative equations in Lebesgue spaces, as well as proving the existence, uniqueness, and stability of the regular Lagrangian flow for the associated ordinary differential equation. We also provide analogous results in this context for second order equations with degenerate noise coefficients that are constant in the spatial variable, as well as for the related stochastic differential equation flows
Variational quantum simulation using non-Gaussian continuous-variable systems
No full textInternational audienceThis work introduces a novel approach to quantum simulation by leveraging continuous-variable systems within a photonic hardware-inspired framework. The primary focus is on simulating static properties of the ground state of Hamiltonians associated with infinite-dimensional systems, such as those arising in quantum field theory. We present a continuous-variable variational quantum eigensolver compatible with state-of-the-art photonic technology. We apply it to the study of static properties of the Bose--Hubbard model in 1+1 dimension and demonstrate its effectiveness and practicality, highlighting the potential of continuous-variable quantum simulations in addressing complex problems in quantum physics
VLPO astrocytes, key players in sleep regulation: Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]
No full textInternational audienceAstrocytes are glial cells of the central nervous system, whose role in brain physiology is increasingly well understood. Recently, their involvement in sleep regulation, particularly through the regulation of extracellular adenosine levels, has been extensively studied. This purine plays a central role in sleep regulation, especially in the ventrolateral preoptic nucleus (VLPO), a key brain region involved in the promotion of slow-wave sleep. By combining in situ enzymatic quantification of adenosine levels, infrared videomicroscopy measurements of vascular reactivity, and patch-clamp recordings of neuronal activity, it has been demonstrated that these VLPO astrocytes adjust extracellular adenosine levels in response to available glucose, prostaglandin D2 (PGD2) levels, and circadian timing. Extracellular adenosine activates A2A receptors located on endothelial cells of blood vessels and sleep-promoting neurons of the VLPO, simultaneously adjusting the increase in blood flow to neuronal activity. This ensures the necessary energy supply for neuronal activation, thereby allowing optimal activation of the VLPO and promoting sleep. This gliocentric mechanism is also integrative, adapting the adenosinergic response to circadian timing, with a greater impact when sleep pressure is high compared to when it is low. Thus, VLPO astrocytes do not merely provide structural support to neurons but also play a dynamic and integrative role in the regulation of vigilance states.Adénosine;Glucose; Prostaglandine D 2 (PGD 2 ); Couplage neurovasculaire (CNV); Hypothalamus Résumé Les astrocytes sont des cellules gliales du système nerveux central, dont le rôle dans la physiologie cérébrale est de mieux en mieux compris. Récemment, leur implication dans la régulation du sommeil, notamment via la régulation des taux extracellulaires d'adénosine, a été particulièrement étudiée. Cette purine joue en effet un rôle central dans la régulation du sommeil, en particulier au niveau du noyau préoptique ventrolatéral (VLPO), une région clé du cerveau impliquée dans la promotion du sommeil lent. En combinant des quantifications enzymatiques in situ des taux d'adénosine, des mesures en vidéomicroscopie infrarouge de la réactivité vasculaire, ainsi que des enregistrements en patch-clamp de l'activité neuronale, il a été démontré que ces astrocytes du VLPO ajustent les taux d'adénosine extracellulaires en réponse du glucose disponible, des taux de prostaglandine D 2 (PGD 2 ) et du moment circadien. L'adénosine extracellulaire active les récepteurs A 2A situés au niveau des cellules endothéliales des vaisseaux sanguins et des neurones promoteurs du sommeil du VLPO, afin d'ajuster simultanément l'augmentation du flux sanguin à l'activité neuronale. Ainsi, l'apport énergétique nécessaire à l'activation neuronale est assuré, ce qui permet ainsi une activation optimale du VLPO et le sommeil. Ce mécanisme gliocentrique est également intégratif, adaptant la réponse adénosinergique au moment circadien, plus important quand la pression de sommeil est élevée, que lorsqu'elle est faible. Les astrocytes du VLPO ne se contentent donc pas de soutenir structurellement les neurones, mais jouent également un rôle dynamique et intégratif dans la régulation des états de vigilance.</div