Portail HAL du Collège de France
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Entanglement growth in the dark intervals of a locally monitored free-fermion chain
No full textWe consider a free fermionic chain with monitoring of the particle density on a single site of the chain and study the entanglement dynamics of quantum jump trajectories. We show that the entanglement entropy grows in time towards a stationary state which display volume law scaling of the entropy, in stark contrast with both the unitary dynamics after a local quench and the noclick limit corresponding to full post-selection. We explain the extensive entanglement growth as a consequence of the peculiar distribution of quantum jumps in time, which display superpoissonian waiting time distribution characterised by a bunching of quantum jumps followed by long dark intervals where no-clicks are detected, akin to the distribution of fluorescence light in a driven atom. We show that the presence of dark intervals is the key feature to explain the effect and that by increasing the number of sites which are monitored the volume law scaling gives away to the Zeno effect and its associated area law.</div
Genetics of prelingual isolated deafness and Usher syndrome in the Maghreb and Jordan: Harnessing the potential of homozygosity
No full textInternational audienceThe molecular genetic diagnosis of prelingual sensorineural hearing impairment (HI) is essential for genetic counseling and patient management. Effective diagnosis requires a knowledge of the genetic architecture of HI, which is often lacking. We established a cohort of 450 unrelated patients with familial (at least two affected relatives) severe-to-profound bilateral prelingual HI in five countries with high consanguinity rates: Tunisia, Jordan, Algeria, Morocco, and Mauritania (the TJAMM cohort). Recessive and dominant inheritance were observed in 92% and 8% of cases, respectively; 14% were syndromic. Genome analysis detected 211 different mutations (36% not reported before) in 49 deafness genes, and fully resolved 90% of cases of autosomal recessive isolated deafness (DFNB forms), 89% of the mutations being homozygous. The deafness genes involved were similar in different countries, but their mutations, except a few in GJB2 and LRTOMT , differed considerably, suggesting an overrepresentation of private mutations. Biallelic missense mutations in MYO7A , CDH23 , PCDH15 , USH1C cause either DFNB forms or Usher syndrome type 1 (USH1) ( USH1/DFNB genes). Such mutations were overrepresented (13% of patients), highlighting the importance of distinguishing between these two mutation classes. We hypothesized that current difficulties might stem from the misclassification of certain mutations. By studying the 65 USH1/DFNB missense mutations reported to cause DFNB in the homozygous state, we identified some that, when associated with a loss-of-function mutation, resulted in USH1, a characteristic pattern of some recessive hypomorphic mutations. This reappraised classification of USH1/DFNB mutations has the potential to improve molecular diagnosis and patient management significantly
First observation of quantum oscillations by transport measurements in semi-destructive pulsed magnetic fields up to 125 T
No full textInternational audienceHigh magnetic fields have proven instrumental in exploring the physical properties of condensed matter, leading to groundbreaking discoveries, such as the quantum Hall effect in 2D heterostructures and quantum oscillations in cuprate superconductors. The ability to conduct precise measurements at progressively higher magnetic fields continues to push the frontiers of knowledge and enable new discoveries. In this work, we present the development of a microwave technique for performing two-point transport measurements in semi-destructive pulsed magnetic fields (up to 125 T) and at low temperatures (down to 1.5 K) with unprecedented sensitivity. This new setup was tested on a variety of samples. We present results on the metal–insulator transition in InAs and we report notably the first observation of Shubnikov–de Haas oscillations in WTe2 at magnetic fields beyond 100 T
Fluvial dynamics in a deltaic environment under Little Ice Age intense climatic forcing (Bras de Fer, Rhône delta, France)
No full textInternational audienceThis study reconstructs the fluvial dynamics of the Bras de Fer distributary in the Rhône Delta (France) during the Little Ice Age (LIA) in response to short-term climatic forcing. A multiproxy approach combining historical cartography, sedimentology, geochemistry, magnetic susceptibility, and hydrological archives reveals accelerated meander migration and extensive overbank accretion between the late seventeenth and early eighteenth centuries CE. Increased flood frequency, coinciding with positive phases of the Atlantic Multidecadal Oscillation (AMO+), promoted rapid lateral channel shifts and the formation of crevasse splay complexes along the outside bank of the Grande Ponche meander. The results demonstrate that, despite stable relative sea levels, deltaic morphology remained highly sensitive to decadal-scale climatic variability, highlighting the dominant role of hydrological extremes in shaping fluvial-deltaic environments of Rhône delta during the late LIA
Adaptive communication between cell assemblies and “reader” neurons shapes flexible brain dynamics
No full textInternational audienceCell assemblies are considered fundamental units of brain activity, underlying diverse functions ranging from perception to memory and decision-making. Cell assemblies have generally been studied in relation to specific stimuli or actions, but this approach does not readily extend to more abstract constructs. An alternative approach is to assess cell assemblies without making reference to external variables, and instead focus on internal brain processes—by assessing assemblies by their endogenous ability to effectively elicit specific responses in downstream (“reader”) neurons. However, this compelling idea currently lacks experimental support. Here, we provide evidence for assembly–reader communication. Large-scale cross-structural recordings in rats revealed that reader activation was genuinely collective, functionally selective, yet flexible, implementing both pattern separation and completion. These processes occurred at the time scale of membrane integration, synaptic plasticity, and gamma oscillations. Finally, assembly–reader couplings were selectively modified upon associative learning, indicating that they were plastic and could become bound to behaviorally relevant variables. These results support cell assemblies as an endogenous mechanism for brain function
Self-Supervised Z-Slice Augmentation for 3D Bio-Imaging via Knowledge Distillation
No full textThree-dimensional biological microscopy has significantly advanced our understanding of complex biological structures. However, limitations due to microscopy techniques, sample properties or phototoxicity often result in poor z-resolution, hindering accurate cellular measurements. Here, we introduce ZAugNet, a fast, accurate, and self-supervised deep learning method for enhancing z-resolution in biological images. By performing nonlinear interpolation between consecutive slices, ZAugNet effectively doubles resolution with each iteration. Compared on several microscopy modalities and biological objects, it outperforms competing methods on most metrics. Our method leverages a generative adversarial network (GAN) architecture combined with knowledge distillation to maximize prediction speed without compromising accuracy. We also developed ZAugNet+, an extended version enabling continuous interpolation at arbitrary distances, making it particularly useful for datasets with nonuniform slice spacing. Both ZAugNet and ZAugNet+ provide high-performance, scalable z-slice augmentation solutions for large-scale 3D imaging. They are available as open-source frameworks in PyTorch, with an intuitive Colab notebook interface for easy access by the scientific community
Mishima revisité: Envers et malgré lui
No full textInternational audienceRomancier, dramaturge, essayiste, mais aussi acteur, modèle, metteur en scène... De nombreuses facettes de l’artiste Mishima Yukio restent encore ignorées. Les textes réunis dans ce volume revisitent des ouvrages inédits ou méconnus de l’écrivain japonais, déchiffrent ses performances, analysent son style, interrogent enfin le contrôle que Mishima Yukio exerça sur son image publique. Mishima revisité renouvelle ainsi le regard que nous portons sur cet auteur et contribue à nous sortir du biographisme qui a longtemps figé son portrait
Perspectives mécanistiques sur la valorisation du CO₂ via les paires de Lewis frustrées, les porphyrines et les polyoxométallates : une approche computationnelle
No full textThe catalytic reduction of carbon dioxide (CO₂) stands as a pivotal challenge and opportunity in the pursuit of sustainable energy and carbon-neutral technologies. This thesis addresses this challenge by investigating two distinct types of molecular systems capable of promoting CO₂ conversion under mild conditions: Frustrated Lewis Pairs (FLPs) and two polyoxometalate (POM)-containing systems. Chapter 2 explores the reactivity of molecular FLPs toward CO₂ hydrogenation, emphasizing the key step of H₂ activation. We constructed a comprehensive dataset of 112 intramolecular B/N FLPs, systematically varying electronic and structural features. Using Density Functional Theory (DFT), we computed thermodynamic (∆G) and kinetic (∆G‡) parameters associated with H2 splitting and CO₂ hydrogenation. A multivariate regression analysis was employed to identify chemically meaningful descriptors, such as acid/base strength, donor-acceptor distance (d), and molecular distortion (λ), that govern reactivity trends. The resulting structure-activity models provide actionable insights for the rational design of FLPs, enabling predictive strategies for both H₂ activation and downstream CO₂ valorization. In the subsequent chapter 3, we shift focus to the photocatalytic conversion of CO2 using POM-containing systems. These redox-active metal-oxo clusters exhibit high structural versatility and are well-suited for mediating multi-electron transformations. We apply a computational approach to investigate the CO₂ activation and reduction mechanisms on experimentally studied POM-based photocatalyitic systems, in collaboration with the Institut Lavoisier de Versailles. Particular attention is paid to the interplay between molecular structure, supramolecular interactions, and catalytic activity. Together, these studies offer a dual perspective, thermochemical and photochemical, on CO₂ reduction, providing mechanistic understanding and predictive tools for the development of next-generation catalysts. The insights gained lay a foundation for generalizable design principles in sustainable molecular catalysis.La réduction catalytique du dioxyde de carbone (CO₂) représente à la fois un défi majeur et une opportunité stratégique dans la quête de technologies durables et neutres en carbone. Cette thèse aborde ce défi en étudiant deux types distincts de systèmes moléculaires capables de promouvoir la conversion du CO₂ dans des conditions douces : les paires de Lewis frustrées (FLPs) et deux systèmes contenant des polyoxométallates (POM). Le chapitre 2 explore la réactivité des FLPs moléculaires vis-à-vis de l'hydrogénation du CO₂, en mettant l'accent sur l'étape clé de l'activation de H₂. Nous avons construit un ensemble de données complet de 112 FLPs intramoléculaires B/N, en faisant varier systématiquement les caractéristiques électroniques et structurales. Grâce à la théorie de la fonctionnelle de la densité (DFT), nous avons calculé les paramètres thermodynamiques (∆G) et cinétiques (∆G‡) associés à la coupure de H₂ et à l'hydrogénation du CO₂. Une analyse de régression multivariée a été utilisée pour identifier des descripteurs chimiquement significatifs, tels que la force acide/base, la distance donneur-accepteur (d), et la distorsion moléculaire (λ), qui gouvernent les tendances de réactivité. Les modèles de relation structure-activité obtenus fournissent des pistes concrètes pour la conception rationnelle de FLPs, permettant de développer des stratégies prédictives tant pour l'activation de H₂ que pour la valorisation ultérieure du CO₂. Dans le chapitre 3, l'attention se porte sur la conversion photocatalytique du CO₂ à l'aide de systèmes contenant des POM. Ces clusters métal-oxo redox-actifs présentent une grande polyvalence structurale et sont particulièrement adaptés pour des transformations multi-électroniques. Nous adoptons une approche computationnelle pour étudier les mécanismes d'activation et de réduction du CO₂ sur des systèmes photocatalytiques à base de POM étudiés expérimentalement, en collaboration avec l'Institut Lavoisier de Versailles. Une attention particulière est portée à l'interaction entre la structure moléculaire, les interactions supramoléculaires et l'activité catalytique. Ensemble, ces travaux offrent une double perspective — thermochimique et photochimique — sur la réduction du CO₂, apportant une compréhension mécanistique et des outils prédictifs pour le développement de catalyseurs de nouvelle génération. Les enseignements tirés jettent les bases de principes de conception généralisables en catalyse moléculaire durable
HAL au service des projets de recherche: Rendre visible l'ensemble de ses données
No full textNational audienceCo-organisé par le consortium DISTAM, la BULAC et le CCSD, cet événement poursuivait un double objectif. Tout d'abord, il a offert aux chercheurs en études aérales un exemple concret d'utilisation de l'archive ouverte HAL grâce à un retour d'expérience issu du projet ERC-DHARMA. Ce retour permet de voir comment HAL peut soutenir toutes les étapes de la recherche de la collecte des données à leur partage en libre accès. Ensuite, cet événement a fournir aux chercheurs un soutien personnalisé pour les aider à tirer le meilleur parti de l'archive ouverte HAL et à rendre visible l'ensemble des données de la recherche
Perinatal Maturation of Drug Transporters and Claudin‐5 at the Blood–Brain Barrier
No full textInternational audienceABSTRACT Aim Cerebral capillary endothelial cells (EC) form the blood–brain barrier (BBB), which regulates molecular exchange between the blood and the brain. Understanding their function during brain development is essential for optimizing treatments in neonates, children, as well as pregnant and breastfeeding women. Methods P‐glycoprotein (P‐gp/ABCB1) expression during brain development was assessed by immunohistochemistry in human cortical samples. In mice, postnatal brain microvessels were analyzed using qPCR and Western Blot, and BBB function was evaluated in vivo using [ 14 C]sucrose to assess barrier integrity, and [ 3 H]verapamil or [ 3 H]rosuvastatin to assess transport activity. Results In humans, P‐gp reached mature levels in the early postnatal period. In mice, BBB integrity was established by postnatal day 5 (P5), but the expression of claudin‐5, P‐gp, and Oatp1a4 increased until P30. Brain transport of verapamil and rosuvastatin significantly decreased between P15 and P30, indicating enhanced efflux capacity. Conclusions Although BBB integrity is established at birth, BBB continues maturing throughout the postnatal period, with a predominant efflux transport. Our findings underscore the critical role of P‐gp in the acquisition of BBB gatekeeper properties. The immature BBB may result in a higher brain susceptibility to P‐gp substrates in preterm infants