Portail HAL du Collège de France
Not a member yet
22122 research outputs found
Sort by
Variations en anthropologie (&) linguistique offertes à Aurore Monod Becquelin ; 1 : Polyphonies amérindiennes
No full textInternational audienceL'ouvrage réunit un ensemble de travaux consacrés aux discours et aux langues d'Amazonie et du monde maya, rédigés par des spécialistes de renommée internationale. Les analyses abordent des thématiques phares de l'anthropologie linguistique, à partir d'études de cas issues d'enquêtes de terrain ou d'archives. Des aspects structurels de certaines langues amérindiennes – portant notamment sur l'espace, le temps ou l'agentivité – sont examinés dans une approche discursive et pragmatique. Différentes formes orales, en particulier celles de registres rituels, mais aussi mythiques ou conversationnels, sont étudiées tant pour leurs qualités poétiques que pour leurs modes spécifiques de significations et d'efficacité. La polyphonie énonciative ainsi que l'intertextualité de ces paroles sont mises en lumière, de même que les usages de la vocalité, de la gestualité et d'autres modes co-expressifs de la communication. L'ouvrage met en valeur les paroles étudiées dans leur langue originale et s'interroge, dans une perspective réflexive à la fois contemporaine et historique, sur les révélations et effets produits par la traduction de langues si éloignées des nôtres. Le livre est dédié à Aurore Monod Becquelin, américaniste et ethnolinguiste dont les contributions essentielles aux différents domaines abordés constituent une source d'inspiration pour les auteurs. L'introduction et le chapitre final offrent une présentation historique inédite du parcours de cette chercheuse et du champ des études qu'elle a largement contribué à fonder et à animer en France, en dialogue constant, depuis plus de cinquante ans, avec ses terrains et ses collègues du proche et du lointain
Production and Stabilization of a Spin Mixture of Ultracold Dipolar Bose Gases
No full textInternational audienceMixtures of ultracold gases with long-range interactions are expected to open new avenues in the study of quantum matter. Natural candidates for this research are spin mixtures of atomic species with large magnetic moments. However, the lifetime of such assemblies can be strongly affected by the dipolar relaxation that occurs in spin-flip collisions. Here we present experimental results for a mixture composed of the two lowest Zeeman states of 162Dy atoms, that act as dark states with respect to a light-induced quadratic Zeeman effect. We show that, due to an interference phenomenon, the rate for such inelastic processes is dramatically reduced with respect to the Wigner threshold law. Additionally, we determine the scattering lengths characterizing the s-wave interaction between these states, providing all necessary data to predict the miscibility range of the mixture, depending on its dimensionality
Targeting the cell membrane in established and emerging model organisms
No full textInternational audienceTransgenic markers and tools have revolutionised how we study cells and developing organisms.Some of the elements needed to construct those tools are universally applicable (e.g. fluorescentproteins), while others are species-specific (e.g. cis-regulatory elements driving transcription).Membrane-localising signals that target proteins to the plasma membrane have been identified inseveral model organisms. Unfortunately, the efficacy of these signals varies greatly across species. Toaddress this problem, we generated a toolkit of 11 membrane-localising tags that can be screenedrapidly in diverse organisms. The toolkit includes tags that target the plasma membrane throughdifferent mechanisms, including signal peptides, the attachment of lipids, and fusion withlipid-binding domains. Each tag has been fused to the red fluorescent protein mScarlet3 and placeddownstream of a T7 promoter, allowing the in vitro production of mRNA that can be readily deliveredin a wide range of embryos and cells of interest. Through a collaborative effort, we tested this toolkitin ten species of animals spanning diverse phyla, including chordates, echinoderms, arthropods,nematodes, annelids, flatworms and cnidarians. We identify robust membrane-localising tags in eachof these animals, and in one of animals' closest relatives, the choanoflagellates. Three tags (KRas,GAP43 and Src64B) work in all of the species tested
Effective Energy, Interactions And Out Of Equilibrium Nature Of Scalar Active Matter
No full textEstimating the effective energy, of a stationary probability distribution is a challenge for non-equilibrium steady states. Its solution could offer a novel framework for describing and analyzing non-equilibrium systems. In this work, we address this issue within the context of scalar active matter, focusing on the continuum field theory of Active Model B+. We show that the Wavelet Conditional Renormalization Group method allows us to estimate the effective energy of active model B+ from samples obtained by numerical simulations. We investigate the qualitative changes of as the activity level increases. Our key finding is that in the regimes corresponding to low activity and to standard phase separation the interactions in are short-ranged, whereas for strong activity the interactions become long-ranged and lead to micro-phase separation. By analyzing the violation of Fluctuation-Dissipation theorem and entropy production patterns, which are directly accessible within the WCRG framework, we connect the emergence of these long-range interactions to the non-equilibrium nature of the steady state. This connection highlights the interplay between activity, range of the interactions and the fundamental properties of non-equilibrium systems
What drives the growth of black holes : a decade of progress
No full textInternational audienceThe last decade has witnessed significant progress in our understanding of the growth of super-massive black holes (SMBHs). It is now clear that an Active Galactic Nucleus (AGN: the observed manifestation of a growing SMBH) is an "event" within the broader lifecycle of a galaxy, which can significantly influence the shape and evolution of the galaxy itself. Our view of the obscuring medium that affects the observed properties of an AGN has also undergone a revolution, and we now have a more physical understanding of the connection between the fuelling of (and feedback from) the SMBH and the broader host-galaxy and larger-scale environment. We have a greater understanding of the physics of SMBH accretion, can identify AGNs out to z = 8-10 witnessing the very earliest phases of SMBH growth, and have a more complete census of AGN activity than ever before. This great progress has been enabled by new innovative facilities, an ever-increasing quantity of multi-wavelength data, the exploitation and development of new techniques, and greater community-wide engagement. In this article we review our understanding of AGNs and the growth of SMBHs, providing an update of the earlier Alexander and Hickox (2012) review. Using citation-network analyses we also show where this review fits within the broader black-hole research literature and, adopting the previous article as a snapshot of the field over a decade ago, identify the drivers that have enabled the greatest scientific progress
L’ombre en soi qui écrit: leçon inaugurale prononcée au Collège de France le jeudi 6 février 2025
No full textInternational audience« Tout héros qu'il est, Ulysse demande à être attaché au mât du navire pour résister au chant des sirènes. De même, le poète oppose une résistance farouche à l'attraction du savoir. Non pas qu’il soit contre le savoir, au contraire, mais obstinément, avec entêtement, il cherche à garder inaccessible un fragment qui échappe depuis toujours au savoir. Si chaque objet a une ombre portée, le savoir aussi a la sienne qu’il lui est, par définition, impossible d’éclairer de ses lumières. Pour s’aventurer dans cette ombre, il faut impérativement un stalker. Certaines choses ne s’enseignent pas. Non seulement elles ne s’enseignent pas, mais l’acte de vouloir les enseigner les annule aussitôt. Elles doivent leur présence à l’effacement de la raison. Peut-être à une folie, à une transe, une perte, une dérive. Peut-être aussi, sans doute même, au sang, qui y est pour beaucoup dans l’ardeur d’une ombre qui trouve ses origines dans les profondeurs de nos violences et de nos barbaries.
GATOS. VIII. On the Physical Origin of the Extended Mid-infrared Emission in Active Galactic Nuclei
No full textInternational audienc
