HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Oxytocin Gα signaling-induced amygdala astrocytes processes retraction shapes behavioral stress response
No full textAnticipated reactions to stressful situations are vital for the survival and well-being of organisms, and abnormal reactions are involved in stress-related disorders. The neuropeptide oxytocin is a key modulator ensuring well-adapted stress responses. Oxytocin acts on both neurons and astrocytes, but the molecular and cellular mechanisms mediating stress response remain poorly understood. Here, we focus on the amygdala, a crucial hub that integrates and processes sensory information through oxytocin- dependent mechanisms. Using an acute stress paradigm in mice, genetic and pharmacological manipulations combined with proteomic, morphological, electrophysiological and behavioral approaches, we reveal that oxytocinergic modulation of the freezing response to stress is mediated by transient Gαi-dependent retraction of astrocytic processes, followed by enhanced neuronal sensitivity to extracellular potassium in the amygdala. Our findings elucidate a pivotal role for astrocytes morphology- dependent modulation of brain circuits that is required for proper anticipated behavioral response to stressful situations
Boosting effect of encapsulated polyoxometalates in the photocatalytic CO2 reduction by MOF-545
No full textInternational audienc
Volumetric Estimation of the Backscatter Coefficient with a Matrix Probe
No full textInternational audienceEvaluation of the backscatter coefficient (BSC) from soft tissues has many applications for medical diagnosis. However, electronic noise and spatial variations often affect BSC estimation, requiring spatial averaging inside a region of interest (ROI) that reduces spatial resolution compared to the B-mode images. This study explores 3D BSC estimation using a matrix probes to address this trade-off by allowing narrower ROIs without losing robustness. A comparison study between a 1024-element matrix probe (V8) and two linear probes (L12-5, L22-8) was made on homogeneous agar-based phantoms with Orgasol particles (5, 10, and 20 µm). BSC was computed using the reference phantom method, and robustness was assessed via the BSC standard deviation across ROIs. Results showed that, despite the lower B-mode resolution and longer correlation length between A-lines, volumetric estimation with a matrix probe offered comparable accuracy while enhancing robustness and resolution in the BSC map compared to the standard 2D estimation. These results could be beneficial for the analysis of complex heterogeneous media.</div
Breakup cascade in gas filament
No full textInternational audienceDespite its importance in both geophysical and industrial contexts, the inertial fragmentation of gas filaments has received much less attention than their liquid counterparts. Yet, gas filaments produce the smallest bubble sizes, which drive gas dissolution, critical to ocean-atmosphere exchange such as carbon dioxide and oxygen, as well as marine aerosols emission, serving as nuclei for cloud condensation and ice particle production.Here, we unravel the fundamental physics governing the splitting of a single filament in a model geometry by combining numerical simulations, laboratory experiments and theory.We show that the splitting of a single filament generates a power-law bubble size distribution following with the volume equivalent bubble diameter, suggesting the existence of a self-similar breakup mechanism, absent in liquid ligament fragmentation.We propose a deterministic model, based on the capillary fragmentation of a filament with power-law shape, which quantitatively captures the bubble size distribution.We demonstrate that the filament shape at breakup sets the size distribution of a first generation of bubbles. This distribution is then reproduced at smaller and smaller scales by latter breakups in a self-similar manner.The -distribution coincides with the size distribution of small bubbles observed in dilute turbulent flow, such as below breaking waves. We argue that the turbulent bubble size distribution observed in nature arises as the superposition of many individual filament splittings. The turbulence nature of the flow only sets the initial conditions of each splitting dynamics, and play no role in the bubble size selection
Actualités de 2024 en santé du sommeil
No full textInternational audienceRecent studies emphasize sleep as a pivotal public health priority on par with diet and exercise. Global data are limited, but the development of standardized measures (e.g., Sleep Health Index) can help assess population-level sleep duration and quality. Digital tools supported by artificial intelligence now enable personalized behavioral recommendations for improved sleep. Nonetheless, social and environmental factors (including racial and socioeconomic disparities) strongly shape sleep experiences, highlighting the necessity of viewing sleep health through both an individual and collective lens. Integrating technology with broader social initiatives and ensuring equitable access remain paramount in advancing sleep health on a global scale.Des études récentes soulignent l’importance du sommeil comme priorité de santé publique, au même titre que l’alimentation et l’exercice physique. Les données mondiales sont limitées, mais la mise en place de mesures standardisées (par exemple l’Indice de santé du sommeil) peut aider à évaluer la durée et la qualité du sommeil à l’échelle de la population. Les outils numériques, soutenus par l’intelligence artificielle, permettent désormais de formuler des recommandations comportementales personnalisées pour améliorer le sommeil. Néanmoins, les déterminants sociaux et environnementaux (y compris les disparités raciales et socio-économiques) influencent fortement l’expérience du sommeil, soulignant la nécessité d’envisager la santé du sommeil à la fois à l’échelle individuelle et collective. L’intégration de la technologie à de plus vastes initiatives sociales et la garantie d’un accès équitable demeurent primordiales pour faire progresser la santé du sommeil à l’échelle mondiale
Sialyl Lewis X (sLex):Biological functions, synthetic methods and therapeutic implications
No full textInternational audienceCarbohydrates are shown to be crucial to several biological processes. They are essential mediators of cell-cell recognition processes. Among them, Sialyl Lewis X (sLe x ) is a very significant structure in the human body. It is a critical tetrasaccharide that plays a pivotal role in various biological processes, including cell adhesion, immune response, and cancer metastasis.Known as the blood group antigen, sLe x is also referred to as cluster of differentiation 15s (CD15s) or stage-specific embryonic antigen 1 (SSEA-1). sLe x is not only a prominent blood group antigen, but also involved in the attraction of sperm to the egg during fertilization, prominently displayed at the terminus of glycolipids on the cell surface. By describing the synthetic methods and biological functions of sLe x , this review underscores the importance of sLe x in both fundamental and applied sciences and its potential to impact clinical practice
Inductance measurement of YBCO strip-lines made by ion irradiation
No full textWe have investigated the electrodynamic properties of High-Tc strip-lines made by ion irradiation, in order to evaluate the potentialities of such a technology for RSFQ superconductor digital electronic. SQUID loops of different length and width have been fabricated by ion bombardment of 70 nm thick films through e-beam lithographied shadow masks, and measured at different temperatures. The voltage modulations have been recorded by direct injection of a control current in the SQUIDs arms. The corresponding line inductances have been measured and compared with 3D simulations. A quantitative agreement has been obtained leading to typical values of 0.4 pH/microns without ground plane
Weak non-linearities of amorphous polymer under creep in the vicinity of the glass transition
No full textInternational audienceThe creep behavior of an amorphous poly(etherimide) (PEI) polymer is investigated in the vicinity of its glass transition in a weakly non linear regime where the acceleration of the creep response is driven by local configurational rearrangements. From the time shifts of the creep compliance curves under stresses from 1 to 15 MPa and in the temperature range between T g -10K and T g , where T g is the glass transition, we determine a macroscopic acceleration factor. The macroscopic acceleration is shown to vary as e -(Σ/Y ) n with n = 2 ± 0.2, where Σ is the macroscopic stress and Y is a decreasing function of compliance. Because at the beginning of creep, the stress is homogeneous, the macroscopic acceleration is thus similar to the local one, in agreement with the recent theory of Long et al. (Phys. Rev. Mat. (2018) 2, 105601 ) which predicts n = 2. For larger compliances, the decrease of the of Y is interpreted as a signature of the development of stress disorder during creep.</div
Transmission interference microscopy of anterior human eye
No full textInternational audienceWe demonstrate that the fundamental ideas of E. Abbe about the interference nature of transmission microscopy are relevant for imaging of in vivo human eye. The transmission geometry in the eye is achieved by projecting illumination onto the posterior eye (sclera) and using the back-reflected light as a secondary illumination source for anterior eye structures. In particular, we show that the tightly localized illumination spot at the sclera acts as a closed condenser aperture in conventional microscopy, significantly enhancing interference contrast. In vivo cells and nerves are revealed with increased contrast across all corneal layers and within an extended 2 mm field of view, 7× larger than the clinical state-of-the-art. This transmission microscope presents the only modality, where the crystalline lens epithelial cells, fibers and sutures can be readily counted. In patients, Fuch's endothelial dystrophy, a major ophthalmic disease affecting 300 million people, is highlighted under a new transmission contrast. Finally, the instrument is built using consumer cameras, which opens opportunities for its wide adoption in the pre-screening and follow-up of cataract/refractive surgeries and the diagnosis of corneal infections in developing countries, where anterior eye diseases are most prevalent
The intriguing role of L-cysteine in the modulation of chiroplasmonic properties of chiral gold nano-arrows
No full textInternational audienceDeveloping chiral plasmonic nanostructures represents a significant scientific challenge due to their multidisciplinary potential. Observations have revealed that the dichroic behavior of metal plasmons changes when chiral molecules are present in the system, offering promising applications in various fields such as nano-optics, asymmetric catalysis, polarization-sensitive photochemistry and molecular detection. In this study, we explored the synthesis of plasmonic gold nanoparticles and the role of cysteine in their chiroplasmonic properties. Specifically, we synthesized chiral gold nano-arrows using a seed-mediated-growth synthesis method, in which gold nanorods are used as seeds while incorporating L-cysteine into growth solution as a chiral ligand. Our results show clearly that the chiral molecule transfers chirality to gold nanocrystals and the morphology is controlled through kinetic growth. In addition, we demonstrate that the chiroplasmonic properties, such as the sign of circular dichroism, can be modulated using only one enantiomeric form in the growth solution. To understand the origin of such an effect, we conducted theoretical modelling using density functional theory. Our results point to the intermolecular cysteine interactions as a key factor in the dichroic properties of surface-molecule chiral systems