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Entre la recherche aveugle et la recherche éclairée : une formation innovante sur les différentes postures en recherche qualitative (accepté)
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Actes du colloque, Masculin/féminin dans la poésie latine, colloque d'Octobre 2023, à paraître 2025.
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The General Supersymmetric Solution of Minimal Massive Supergravity
No full textInternational audienceMinimal massive supergravity is the supersymmetric extension of minimal massive gravity in three dimensions. The theory admits a supersymmetric anti-de Sitter vacuum around which the propagating modes of spin 2 and 3/2 combine into a supermultiplet. In this letter, we determine the most general supersymmetric solution of the theory by analyzing its Killing spinor equations. Just as for topologically massive supergravity, the general supersymmetric solution is a plane wave with a null Killing vector field. As a particular subclass we find null-warped AdS3 spaces and, with proper periodic identifications, null-warped AdS3 black holes
Les intérêts des femmes et intérêts des hommes sont-ils fongibles dans la souveraineté nationale ? De quelques discours sur la représentation des femmes "en tant que telles"
No full textInternational audienceDans un contexte français de lois électorales familialistes et d’une doctrine de la représentation politique qui interdit toute idée d’intérêts intermédiaires ou particuliers, qu’en est-il des propositions alternatives qui défendent la nécessité d’une représentation des femmes en tant que telles ? Par « représentation des femmes en tant que telles », on entend la contestation de la doctrine universaliste, quelle que soit la manière dont celle-ci est interprétée et mise en application à l’époque : soit par les défenseurs d’un droit de vote des femmes en tant qu’individus indifférenciés, comme Condorcet et Guyomar, soit par les lois électorales établissant la capacité du seul paterfamilias à parler au nom de la nation tout entière. Il s’agit ici d’examiner les rares alternatives exprimées en faveur d’un vote pour les femmes « en tant que femmes », porteuses d’intérêts spécifiques, c’est-à-dire non représentables par des hommes vus comme porteurs d’intérêts particuliers, un quasi-non-sens dans la doctrine française de la représentation politique. Ces rares alternatives, dont on trouve des exemples dans le corpus en langue française de la décennie révolutionnaire, ont en commun, malgré leurs divergences, d’ouvrir une brèche dans la pensée et les pratiques dominantes, y compris dans la pensée universaliste pour laquelle, jusqu’à aujourd’hui, il n’existe pas d’intérêts particuliers représentables dans la nation souveraine
Free cumulants and freeness for unitarily invariant random tensors
No full textInternational audienceWe address the question of the asymptotic description of random tensors that are local-unitary invariant, that is, invariant by conjugation by tensor products of independent unitary matrices. We consider both the mixed case of a tensor with inputs and outputs, and the case where there is a factorization between the inputs and outputs, called pure, which includes the random tensor models extensively studied in the physics literature. The finite size and asymptotic moments are defined using correlations of certain invariant polynomials encoded by -tuples of permutations, up to relabeling equivalence. Finite size free cumulants associated to the expectations of these invariants are defined through invertible finite size moment-cumulants formulas. Two important cases are considered asymptotically: pure random tensors that scale like a complex Gaussian, and mixed random tensors that scale like a Wishart tensor. In both cases, we derive a notion of tensorial free cumulants associated to first order invariants, through moment-cumulant formulas involving summations over non-crossing permutations. The pure and mixed cases involve the same combinatorics, but differ by the invariants that define the distribution at first order. In both cases, the tensorial free-cumulants of a sum of two independent tensors are shown to be additive. A preliminary discussion of higher orders is provided. Tensor freeness is then defined as the vanishing of mixed first order tensorial free cumulants. The equivalent formulation at the level of asymptotic moments is derived in the pure and mixed cases, and we provide an algebraic construction of tensorial probability spaces, which generalize non-commutative probability spaces: random tensors converge in distribution to elements of these spaces, and tensor freeness of random variables corresponds to tensor freeness of the subspaces they generate
Semaglutide exacerbates stunting in growth-impaired juvenile male mice via reduced energy metabolism
No full textInternational audienceAnimals rely on linear growth to attain their full adult size. The regulators of this multifactorial process, including environmental and endocrine cues, are still incompletely understood. Notably, GLP-1 has emerged as a potential player in this process. Here, we employ semaglutide, a pharmaceutical GLP-1R agonist as a tool to mechanistically dissect the interplay between GLP-1 receptor activation, energy metabolism, and linear growth during the juvenile period, independent of its clinical applications. Using a juvenile mouse model, we show that chronic semaglutide treatment lowers blood glucose without affecting food intake or weight gain in juveniles with normal growth pattern. However, in growth-stunted juveniles, semaglutide treatment exacerbates linear growth impairment through at least two concomitant mechanisms: a moderate reduction in food intake, and a decreased catabolic activity incompatible with tissue growth. These data suggest a complex interplay between GLP-1 signaling, energy metabolism, and growth during juvenile development. Overall, these findings highlight the value of semaglutide as a mechanistic tool for understanding how GLP-1 receptor activation modulates growth and metabolism in juveniles, emphasizing the importance of developmental context for interpreting its effects
Non-local quench spectroscopy of fermionic excitations in 1D quantum spin chains
No full textInternational audienceThe elementary excitations of quantum spin systems have generally the nature of weakly interacting bosonic quasi-particles, generated by local operators acting on the ground state. Nonetheless in one spatial dimension the nature of the quasiparticles can change radically, since many relevant one-dimensional Hamiltonians can be exactly mapped onto models of spinless fermions with local hopping and interactions. Due to the non-local nature of the spin-to-fermion mapping, observing directly the fermionic quasiparticle excitations is impossible using local probes, which are at the basis of all the forms of spectroscopy (such as neutron scattering) traditionally available in condensed matter physics. Here we show theoretically that \emph{quench spectroscopy} for synthetic quantum matter -- which probes the excitation spectrum of a system by monitoring the nonequilibrium dynamics of its correlation functions -- can reconstruct accurately the dispersion relation of fermionic quasiparticles in spin chains. This possibility relies on the ability of quantum simulation experiments to measure non-local spin-spin correlation functions, corresponding to elementary fermionic correlation functions. Our analysis is based on new exact results for the quench dynamics of quantum spin chains; and it opens the path to probe arbitrary quasiparticle excitations in synthetic quantum matter
Euclid: Early Release Observations -- Programme overview and pipeline for compact- and diffuse-emission photometry
No full textInternational audienceThe Euclid ERO showcase Euclid's capabilities in advance of its main mission, targeting 17 astronomical objects, from galaxy clusters, nearby galaxies, globular clusters, to star-forming regions. A total of 24 hours observing time was allocated in the early months of operation, engaging the scientific community through an early public data release. We describe the development of the ERO pipeline to create visually compelling images while simultaneously meeting the scientific demands within months of launch, leveraging a pragmatic, data-driven development strategy. The pipeline's key requirements are to preserve the image quality and to provide flux calibration and photometry for compact and extended sources. The pipeline's five pillars are: removal of instrumental signatures; astrometric calibration; photometric calibration; image stacking; and the production of science-ready catalogues for both the VIS and NISP instruments. We report a PSF with a full width at half maximum of 0.16" in the optical and 0.49" in the three NIR bands. Our VIS mean absolute flux calibration is accurate to about 1%, and 10% for NISP due to a limited calibration set; both instruments have considerable colour terms. The median depth is 25.3 and 23.2 AB mag with a SNR of 10 for galaxies, and 27.1 and 24.5 AB mag at an SNR of 5 for point sources for VIS and NISP, respectively. Euclid's ability to observe diffuse emission is exceptional due to its extended PSF nearly matching a pure diffraction halo, the best ever achieved by a wide-field, high-resolution imaging telescope. Euclid offers unparalleled capabilities for exploring the LSB Universe across all scales, also opening a new observational window in the NIR. Median surface-brightness levels of 29.9 and 28.3 AB mag per square arcsec are achieved for VIS and NISP, respectively, for detecting a 10 arcsec x 10 arcsec extended feature at the 1 sigma level