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Euclid Quick Data Release (Q1). Quenching precedes bulge formation in dense environments but follows it in the field
No full textInternational audience(Abridged) The bimodality between star-forming discs and quiescent spheroids requires the existence of two main processes: the galaxy quenching and the morphological transformation. In this paper, we aim to understand the link between these processes and their relation with the stellar mass of galaxies and their local environment. Taking advantage of the first data released by the Euclid Collaboration, covering more than 60 deg2 with space-based imaging and photometry, we analyse a mass-complete sample of nearly one million galaxies in the range 0.2510^{9.5} M_\odot$. We divide the sample into four sub-populations of galaxies, based on their star-formation activity and morphology. We then analyse the physical properties of these populations and their relative abundances in the stellar mass vs. local density plane. Together with confirming the passivity-density relation and the morphology-density relation, we find that quiescent discy galaxies are more abundant in the low-mass regime of high-density environment. At the same time, star-forming bulge-dominated galaxies are more common in field regions, preferentially at high masses. Building on these results and interpreting them through comparison with simulations, we propose a scenario where the evolution of galaxies in the field significantly differs from that in higher-density environments. The morphological transformation in the majority of field galaxies takes place before the onset of quenching and is mainly driven by secular processes taking place within the main sequence, leading to the formation of star-forming bulge-dominated galaxies as intermediate-stage galaxies. Conversely, quenching of star formation precedes morphological transformation for most galaxies in higher-density environments. This causes the formation of quiescent disc-dominated galaxies before their transition into bulge-dominated ones
Flooding the Feed: The Politics of Social Media Sharing Among Defensive Publics
No full textInternational audienceWhat political significance do widely-shared sources on social media carry? Efforts at documenting media content have produced useful insights about political phenomena, including right-wing populist movements that have recently been theorized as comprising defensive publics which seek to preserve social, economic, and cultural hierarchies that privilege white "nationals." In France, the concept of defensive publics is particularly useful for understanding how rightwing identitarian and nationalist actors use social media to mobilize publics to defend hierarchies framed as under siege by immigration, multiculturalism, and global liberal elites. Building on literature about illiberal communication and the illiberal public sphere, we argue that patterns of sources' visibility -not just content -also serve defensive purposes. Using computational analysis of 1.16 million French language immigration-related posts on Twitter/X and ideological embeddings of 44,810 of these users, we show how far-right-leaning users flood feeds with hyper-partisan sources, particularly on immigration, although they also share ideologically varied sources. Then, interviews with 13 high-profile far-right-affiliated posters who include senior French politicians reveal how these practices support defensive political aims. Sharing hyper-partisan sources outside the "elitist" mainstream redresses perceived censorship by mainstream media, while sharing mainstream sources signals credibility and respectability, even as these actors maintain critiques of the very same media. Meanwhile, reposting sources with statistical and quantitative evidence serves to obscure overtly white supremacist ideologies while advancing antiimmigration agendas. We conclude that sharing practices themselves function as rhetorical resources that highly-visible members of defensive publics use to reassert symbolic and political dominance in a contested media environment
Méthodologie d'optimisation de la configuration matérielle-logicielle pour la détection d'objets dédiée aux véhicules autonomes
No full textIn recent years, integrating artificial intelligence (AI) into embedded systems has opened new horizons for real-time applications, including autonomous vehicles, smart surveillance, and robotics. However, deploying AI models in these embedded environments presents notable challenges, particularly the trade-offs between computational performance, energy efficiency, and model accuracy. This thesis, titled "Methodology for optimizing the hardware/software configuration of a system embedding artificial intelligence," proposes a comprehensive methodology for optimizing both the hardware and software configurations of embedded systems that implement AI technologies.The research focuses on object detection models, notably the YOLOv4 algorithm, tailored for resource-constrained architectures such as the Nvidia Jetson Xavier AGX and Jetson Nano. Key objectives include enhancing real-time processing capabilities, ensuring high precision, and minimizing resource consumption. The methodology incorporates model compression techniques, such as pruning and quantization, to reduce computational complexity while maintaining significant detection accuracy for critical objects, including cars, bicycles, and pedestrians, essential for autonomous driving applications.The proposed approach was validated through extensive experimental evaluations on the Jetson AGX Xavier and Jetson Nano platforms, demonstrating the feasibility of real-time performance under different optimization strategies. Specifically, the pruning method applied on the AGX achieved a 75 % accuracy at an inference speed of 31.3 FPS, while on the Jetson Nano it reached 5 FPS with an accuracy of 70.62 %. In parallel, post-training quantization (INT8) led to a significant speedup on the AGX, achieving 62.5 FPS, with a trade-off in accuracy reduced to 56.69 %. On the Jetson Nano, the same quantization strategy maintained a stable mean accuracy of 68.5 % at 5 FPS, highlighting its robustness in resource-constrained environments.This work contributes to the state-of-the-art by providing a scalable and systematic framework for AI optimization, paving the way for more intelligent and responsive embedded systems in real-world applications. The findings are particularly significant for developing safe and efficient autonomous vehicles, resonating with global efforts to enhance road safety and advance intelligent transportation systems.Ces dernières années, l'intégration de l'intelligence artificielle (IA) dans les systèmes embarqués a ouvert de nouveaux horizons pour les applications en temps réel, notamment les véhicules autonomes, la surveillance intelligente et la robotique. Cependant, le déploiement de modèles d'IA dans ces environnements embarqués présente des défis notables, en particulier les compromis entre la performance de calcul, l'efficacité énergétique et la précision du modèle. Cette thèse, intitulée « Méthodologie d'optimisation de la configuration matérielle-logicielle pour la détection d'objets dédiée aux véhicules autonomes », propose une méthodologie complète pour optimiser les configurations matérielles et logicielles des systèmes embarqués qui mettent en œuvre des technologies d'IA.La recherche se concentre sur les modèles de détection d'objets, notamment l'algorithme YOLOv4, adaptés aux architectures à ressources limitées telles que le Nvidia Jetson Xavier AGX et Jetson Nano. Les principaux objectifs sont l'amélioration des capacités de traitement en temps réel, la garantie d'une grande précision et la minimisation de la consommation de ressources. La méthodologie intègre des techniques de compression de modèles, telles que le pruning et la quantification, afin de réduire la complexité de calcul tout en maintenant une précision de détection significative pour les objets critiques, y compris les voitures, les vélos et les piétons, essentiels pour les applications de conduite autonome.L'approche proposée a été validée par une série d'évaluations expérimentales approfondies sur les plateformes Jetson AGX Xavier et Jetson Nano, démontrant la faisabilité d'un traitement en temps réel selon différentes stratégies d'optimisation. En particulier, la méthode d'élagage appliquée sur l'AGX a permis d'atteindre un taux de précision de 75 % à une fréquence d'inférence de 31.3 FPS, contre 5 FPS avec une précision de 70.62 % sur le Jetson Nano. En parallèle, la quantization post-entraînement (INT8) a offert un gain considérable en vitesse sur l'AGX, atteignant 62.5 FPS, au prix d'une réduction de précision à 56.69 %. Sur le Jetson Nano, la même méthode a permis de conserver une précision moyenne stable de 68.5 % à 5 FPS, ce qui souligne sa robustesse dans des contextes à fortes contraintes de ressources.Ce travail contribue à l'état de l'art en fournissant un cadre évolutif et systématique pour l'optimisation de l'IA, ouvrant la voie à des systèmes embarqués plus intelligents et plus réactifs dans les applications du monde réel. Les résultats sont particulièrement importants pour le développement de véhicules autonomes fiables et efficaces, et s'inscrivent dans le cadre des efforts mondiaux visant à améliorer la sécurité routière et à faire progresser les systèmes de transport intelligents
Large scale identification of pellicle and cell-free liquid phase associated proteins in Bacillus amyloliquefaciens L-17
No full textInternational audienceBacillus amyloliquefaciens is a soil-associated and plant growth-promoting bacterium. It is the focus of numerous studies due to its ability to sporulate, form biofilms, produce antimicrobial peptides and commercial enzymes. The ability of B. amyloliquefaciens L-17 to form floating biofilm at the air-liquid interface "pellicle" was previously demonstrated. This pellicle exhibits a highly structured architecture which is provided by loosely and tightly matrix bound polysaccharides and proteins. In this study, a first large scale proteomic investigation of both the pellicle and the cell-free liquid phase of L-17 strain was performed. An approach based on physical and chemical extraction of the pellicular matrix combined with protein analysis by mass spectrometry identified 87 weakly matrix-bound proteins and 62 tightly bound proteins. A total of 131 pellicle-associated proteins were identified, including (i) the conserved proteins TasA and TapA, involved in biofilm formation and cohesion (ii) BslA, important for biofilm hydrophobicity (iii) several enzymes that make nutrients available and protect the biofilm from competitors (iv) flagellin and (v) proteins involved in the sporulation process. Proteomic characterization of the cell-free liquid phase underlying the analyzed pellicle allowed the identification of 423 proteins including 118 proteins yet identified in the matrix of the pellicle. The proteins identified specifically in the liquid phase include enzymes involved in the biosynthesis process of non-ribosomal peptides and a variety of commercial enzymes such as proteases, lipases, aminotransferases, peroxidases and phytases. This provides valuable clues to promote the industrial and agricultural application of the cell-free liquid phase of B. amyloliquefaciens L-17.</div
Forward modelling of passive microwave emissivities over snow-covered areas at continental scale
No full textInternational audienceTo assimilate passive microwave data in numerical weather prediction, a comprehensive understanding of the components of the radiative transfer equation is essential. Given the significant variability of emissivity in snow-covered regions — affected by frequency, polarisation, and the macro- and microstructural properties of snow — attention must be paid to the design of a forward model. However, existing physical models are unsuitable for global-scale studies due to their reliance on numerous inputs, such as snow grain size across different layers, which are typically unavailable at larger scales. In this study, we propose a method that utilises geophysical properties accessible at the continental scale to derive accurate emissivity values for frequencies ranging from 1 GHz to 90 GHz, in both vertical and horizontal polarisations, with a focus on the incident angles of conical scanners (approximately 50°). Our approach employs neural networks to obtain a robust forward model using geophysical variables as input data. A training dataset was developed based on satellite-derived surface emissivity from the SMOS and AMSR2 instruments by subtracting atmospheric components and surface temperature modulation. The results, which accounts for the actual geophysical state of the surface and its temporal variability, outperform the emissivity climatologies. We achieved snow-covered surface emissivities at the continental scale with a correlation coefficient above 0.9 and a RMSE below 0.02 for frequencies up to 18.7 GHz, and around 0.03 for higher frequencies. Additionally, we demonstrate that, in a typical tundra snowpack where the macro- and microstructural properties of snow can be obtained, the emissivities retrieved by our neural network-based forward model are consistent with results from the physical model (SMRT). This proposed model will also support preparations for the CIMR mission
Auto-calibration and performance monitoring of GRAVITY+ Adaptive Optics system with physics-based methods and inverse problem approaches
No full textInternational audienceIn 2024/2025, the GRAVITY+ Adaptive Optics (GPAO) project installed four extreme AO systems on the 8-meter UTs of the Very Large Telescope: 43x43 deformable mirrors (DM, 1432 actuators), 40x40 (1240 sub-apertures (SA)) visible and 30x30 (704 SA) laser guide star Shack-Hartmann wavefront sensors (SH-WFS) with 9x9 (60 SA) infrared or 2x2 (12 SA) visible SH-WFSs for low order sensing. These subsystems are distributed across the entire infrastructure (pupil in M2 rotating with elevation ; DM in Coudé train wobbling and rotating with azimuth ; WFSs fixed on the ground ; science focal plane in the interferometric laboratory 150 meters away). GPAO’s complexity prefigures that of the AO systems of future giant telescopes: numerous modes, many moving components, and the need to operate robustly in a broad range of magnitudes and turbulence conditions. GPAO successfully achieved these goals thanks to a complete re-design of the tools available in the Standard Platform for Adaptive optics Real Time Applications (SPARTA, from ESO) and the development of new, versatile methods based on physical modelling and inverse problem approaches. In this work we present the five main modules and their on-sky performances: (i) the Pseudo-Synthetic Interaction Matrix (PSIM) module, in charge to numerically (and quickly) compensate the system rotation, which includes a physical model of the ALPAO DM influence functions, (ii) the innovative estimators of WFS/DM lateral mis-registrations for the instrument bootstrapping through the turbulence in open loop and its auto-alignment in closed loop, (iii) a robust spot monitor for faint star detection and centering during the automatic acquisition sequence and for the update of the weighted center of gravity in closed loop, (iv) the atmospheric and performance monitor made versatile to the different GPAO modes and augmented with an innovative multi-layer profiler for wind estimation, and (v) a pupil monitor that offers a fine positioning of the photometric pupil, its orientation and magnification
La compréhension/interprétation de textes littéraires à l’école : approches interactives et théâtrales en formation initiale et continue des enseignants
No full textInternational audienceDans cette communication, concernant l’axe 3 du colloque, il s’agira de rendre compte de pratiques « théâtrales » menées en formation initiale et continue d’enseignants du premier degré en France afin de mettre au travail la compréhension de textes de différents genres (récits, albums, pièces de théâtre). On reviendra sur des propositions didactiques, déjà expérimentées dans ces formations, qui permettent de développer l’investissement subjectif de l’élève et ses performances de compréhension, d’interprétation et d’appréciation (Giasson, 2005), la réception du discours littéraire renvoyant à une dimension psychoaffective, tandis que le traitement diégétique ouvre sur le traitement distancié et analytique du texte.Parce que « la participation du lecteur requiert d’être stimulée autant que la distanciation » (Marlair et Dufays, 2014 : 108), il s’agira, par des biais de théâtralisation, d’engager la lecture littéraire comme activité de résolution de problème (Tauveron, 1999), mais aussi comme un espace qui permet aux élèves d’être « le partenaire actif du texte d’un jeu avec le texte qui a du jeu » (Tauveron, 1999 : 12). En effet, à l’instar du texte théâtral qui est un texte troué (Ubserfeld, 1996 : 19), tout texte littéraire présente des figures du silence (Tauveron, 2002 : 276), des blancs ou vides du texte (Iser, 1985), ellipses ou non-dits. Aussi, pour rentrer dans la complexité de ce texte littéraire en considérant l’importance à accorder à la compréhension de l’implicite (Belahdjin et Bishop, 2022), nous supposons le processus interprétatif inclus dans le processus de compréhension. Cette indissociabilité nous invite à aborder l’interprétation des textes selon des modalités de théâtralisation qui mettent en pédagogie des situations problèmes et « initient au jeu des hypothèses » (Dufays, Gemenne et Ledur, 2005).Le cadre cognitif sous-jacent ici se rapporte à la cognition incarnée, qui considère que l’esprit doit être compris dans le contexte de son corps, et de l’interaction de ce dernier avec l’environnement » (Rinaldi, 2017). Il s’agit donc d’apprendre en prenant appui sur son corps et celui des autres. Le corps, investi dans l’espace, sera un outil pour figurer, restituer, représenter, échanger, comprendre, associer.Deux scénarios qui mobilisent le cadre théorique exposé ci-devant seront présentés : -La réalisation de tableaux humains. Le corps immobile engage, suivant les contraintes pédagogiques émises, le registre des micro-processus, des processus d’intégration et/ou les macro-processus, voire les processus d’élaboration (Giasson, 2003). Un dispositif pédagogique éprouvé en formation continue fera état d’une progression possible qui amène le lecteur à un travail collectif d’élaboration de tableaux (Champain, 2025).-L’approche sensible dans les croisements disciplinaires. Lors de diverses actions de formation, il a été expérimenté comment l’engagement du corps (bruitage d’albums impliquant la voix, interprétation chorégraphique à partir d’albums, mise en voix et en espace) permet une entrée sensorielle dans les textes qui ouvre la voie à une interprétation décuplée du sens et modifie la conception didactique des enseignants sur la littérature. BibliographieBelhadjin, A. et Bishop, M.-F. (dir.). (2022). L’implicite et ses lectures [numéro thématique]. Le français aujourd’hui, 218. Paris : Armand Colin.Castagnet-Caignec, S. (2019) « Littérature, histoire des arts et PEAC : une approche interdisciplinaire et sensible en formation initiale et continue au service de l'ingénierie didactique », 2Oes Rencontres internationales des chercheuses et chercheurs en didactique de la littérature, Expérience et partage du sensible dans l'enseignement de la littérature, 12 > 14 juin 2019, CELLAM, Université Rennes 2 Champain, P. (2025). « Des tableaux humains pour travailler la compréhension ». In Les Cahiers Pédagogiques, N°599.Daunay, B. et Dufays, J. (dir.) (2014). Didactique du français : du côté des élèves. Comprendre les discours et les pratiques des apprenants. https://doi.org/10.3917/dbu.dauy.2014.01.Dufays, J., Gemenne, L. et Ledur, D. (2005). Pour une lecture littéraire Histoire, théories, pistes pour la classe. (2e éd.). De Boeck Supérieur. https://doi.org/10.3917/dbu.dufay.2005.01.Giasson, J. (2003). La compréhension en lecture. Bruxelles : De Boeck Université.Giasson, J. (2005). Les textes littéraires à l’école. Bruxelles : De Boeck.Iser, W. (1976/1985). L'acte de lecture, théorie de l'effet esthétique. Bruxelles : Pierre Mardaga Editeur, coll. «Philosophie et langage», trad. Evelyne Sznycer, 1985.Rinaldi, R. (2017). « La cognition incarnée ou quand la pensée vient du corps ». Cercle Psy, n°25 - Juin-juillet-août 2017. pp. 78-81.Soulé, Y., Tozzi, M. et Bucheton, D. (2008). La littérature en débat. Discussions à visées littéraires et philosophiques à l’école primaire. CRDP Académie de Montpellier. Tauveron, C. (1999). « Comprendre et interpréter le littéraire à l'école : du texte réticent au texte proliférant ». In: Repères, recherches en didactique du français langue maternelle, n°19, Comprendre et interpréter les textes à l'école. pp. 9-38.Tauveron, C. (dir). (2002). Lire la littérature à l'école. Hatier. Ubersfeld, A. (1996). Lire le théâtre I, Paris : Belin
Education et privatisation en Amérique latine: des processus équivoques pour un panorama contrasté
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Poly(sebacic anhydride) based microcarriers loaded with in situ hydrophobized aminoglycoside antibiotics to combat bacterial infections in the lungs: Abstracts TERMIS EU Freiburg, Germany May 20–23, 2025
No full textInternational audienceIntroduction/ObjectivesDry powder formulations for drug delivery to the lungs enable targeted treatment, reducing side effects and lowering therapeutic dosages. Patients with chronic obstructive pulmonary disease (COPD), one of the leading causes of death globally, are prone to exacerbations caused by bacterial infections, primarily from Pseudomonas aeruginosa, Streptococcus pneumoniae, and Staphylococcus aureus. Aminoglycoside antibiotics (AA) are frequently used in infection treatment, but their effectiveness is often limited by encapsulation challenges due to their hydrophilic nature incompatible with hydrophobic carrier matrices. To address these issues, we developed poly(sebacic anhydride) (PSA)-based microparticles (MPs) loaded with gentamicin (G) or tobramycin (T) hydrophobized in situ through ion-pairing with dioctyl sulfosuccinate sodium salt (AOT).MethodsPSA was modified by in situ hydrophobic ion pairing (HIP) of AA and AOT. MPs loaded with G or T ion-paired with AOT (PSA_GA or PSA_TA) were synthesized using a water-in-oil-in-water emulsification method. Encapsulation efficacy (EE) and drug loading (DL) were determined by the orto-phtaldialdehyde (OPA) assay. Successful HIP complex formation was confirmed through Fourier transform infrared spectroscopy (FTIR). The suitability of MPs as drug carriers to the lungs was evaluated by analyzing their size distribution in the form of dry powder using a laser particle size analyzer. The microstructure of the MPs was observed via scanning electron microscopy (SEM). Cytotoxicity was tested on L929 cells using the AlamarBlue assay and live/dead staining. Antimicrobial efficacy was assessed against S. aureus ATCC 25923 using the Kirby-Bauer disk diffusion method.ResultsEncapsulation of unmodified AA or after preformed HIP with AOT within MPs was not successful (EE was around 1%). However, after in situ HIP modification, EE increased to nearly 60% for both PSA_GA and PSA_TA. FTIR analysis confirmed the presence of a peak at 1620 cm−¹, corresponding to the bending vibrations of primary amine groups. According to the literature, this peak indicates the successful formation of an AA complex with AOT. PSA_GA and PSA_TA were cytocompatible up to the concentrations of 100 µg/ml. In antibacterial testing against S. aureus, inhibition zones for PSA_GA and PSA_TA were 20 mm and 15 mm, respectively. SEM observations revealed that the MPs were spherical but slightly agglomerated due to the presence of AOT on their surface, which has a sticky nature. This contributed to the fraction of particles within the optimal size range for inhalation (1-5 µm) being 5% for PSA_GA and 13% for PSA_TA.ConclusionsWe have successfully developed a delivery system with significantly enhanced EE and DL of AA, resulting in promising antibacterial properties against Gram-positive bacteria S. aureus ATCC 25923. However, additional evaluation against Gram-negative bacteria species, such as P. aeruginosa, is essential, as AA are primarily intended for effective bactericidal action against these bacteria. Since the deposition site of inhaled MPs in the respiratory tract strongly depends on particle size, further size optimization is crucial for maximizing delivery efficiency
Screw Symmetry, Chiral Hydrodynamics and Odd Instability in Active Cholesterics
No full textActive cholesterics are chiral in both their structure, which has continuous screw symmetry, and their active stresses, which include contributions from torque dipoles. Both expressions of chirality give rise to curl forces in the hydrodynamics, which we derive from the active Ericksen-Leslie equations using a geometric approach. This clarifies the hydrodynamics of continuous screw symmetry and provides an example of generalised odd elastic forces that originate from an equilibrium free energy. We discuss also the nonlinear structure of the active hydrodynamics in terms of the Eulerian displacement field of the cholesteric pseudolayers. For the active instability, screw symmetry generates a contribution of chiral activity to the linearised pseudolayer hydrodynamics that is absent in materials with chiral activity but achiral structure. When the two forms are sufficiently antagonistic, this term produces a new active instability with threshold and characteristic wavevector distinct from those of the active Helfrich-Hurault instability in chiral active smectics. Finally, we comment on the isotropic chiral hydrodynamics of materials with three-dimensional screw symmetry.</div