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Ultrasonic signals support a large-scale communication landscape in wild mice
No full textInternational audienceCommunication is central to mammalian social life, enabling group coordination and individual interactions, and often involves a trade-off between reach and privacy.1 While signals resisting environmental attenuation reach distant audiences, they risk interception by predators or eavesdroppers; conversely, short-range signals ensure private exchanges.2 Rodents frequently utilize ultrasonic vocalizations,3,4,5 which, due to rapid environmental attenuation,6 are generally considered a private channel for close-contact interactions within social groups.5,7 Although laboratory studies revealed that rodents' ultrasonic vocalizations encode rich information like emotions,5,8 identity,9,10 sex,11,12,13 and strain,12,13 the role of these physically constrained signals in organizing broader social landscapes remains largely unexplored in the wild.14,15,16,17 Here, we investigated the communication system of the African striped mouse (Rhabdomys pumilio), a highly social and territorial rodent, combining propagation experiments, passive acoustic monitoring, and playback in the field. We show that striped mice emit ultrasonic calls within family groups and at territorial boundaries, using different types of vocalizations depending on the location. Furthermore, these signals carry group-specific information, allowing mice to discriminate between group members, neighbors, and strangers. By vocalizing at key locations, striped mice extend the functional range of their short-range signals to support a large-scale communication landscape mediating complex territorial dynamics
Twisted light from topological chiral exceptional points in a nanolaser array
No full textWe propose and experimentally demonstrate an orbital angular momentum (OAM) nanolaser array arranged in a ring geometry on an InP-based photonic crystal membrane. The device realizes a non-Hermitian extension of the Rice-Mele model, featuring alternating coupling strengths and imaginary on-site detunings. This configuration supports a symmetry-protected zero mode stabilized by non-Hermitian particle-hole symmetry, which enforces a uniform phase shift between adjacent nanolasers, establishing a coherent phase winding around the array. By adjusting the gain/loss contrast in a parity-time (PT)-like pumping scheme, the system can be tuned to a chiral exceptional point, where energy flows unidirectionally between nanocavities despite their reciprocal coupling. This symmetry-enforced, directional tunneling leads to far-field emission carrying non-zero OAM, providing a direct signature of the phase-structured lasing mode. Our results demonstrate a robust and scalable strategy for engineering compact, phase-locked laser arrays with controllable angular momentum output, and open new avenues for structured light generation in integrated photonic platforms
Observation of entanglement in a cold atom analog of cosmological preheating
No full textInternational audienceWe observe entanglement between collective excitations of a Bose-Einstein condensate in a configuration analogous to particle production during the preheating phase of the early universe. In our setup, the oscillation of the inflaton field is mimicked by the transverse breathing mode of a cigar-shaped condensate, which parametrically excites longitudinal quasiparticles with opposite momenta. After a short modulation period, we observe entanglement of these pairs which demonstrates that vacuum fluctuations seeded the parametric growth, confirming the quantum origin of the excitations. As the system continues to evolve, we observe a decrease in correlations and a disappearance of non-classical features, pointing towards future experimental probes of the less understood interaction-dominated regime.Nous observons l’intrication entre des excitations collectives d’un condensat de Bose-Einstein dans une configuration analogue à la production de particules durant la phase de preheating de l’Univers primitif. Dans notre dispositif, l’oscillation du champ d’inflaton est imitée par le mode de respiration transverse d’un condensat en forme de cigare, qui excite de manière paramétrique des quasi-particules longitudinales de moments opposés. Après une courte période de modulation, nous observons l’intrication de ces paires, révélant le rôle joué par les fluctuations du vide dans l’amorçage de la croissance paramétrique. Cela confirme l’origine quantique des excitations. À mesure que le système continue d’évoluer, nous constatons une diminution des corrélations et une disparition des caractéristiques non-classiques. Ces observations ouvrent la voie à de futures explorations expérimentales du régime non linéaire qui suit, où d’autres analogies pourront être établies avec le reheating, c’est-à-dire la thermalisation de l’Univers post-inflationnaire
Photo-induced plasma confinement in ultrashort laser-excited nanostructures
No full textInternational audienceIntense ultrashort lasers modify transient optical properties of transparent materials, converting them into cold plasma non-equilibrium state of matter. This electron-hole plasma can be confined to subwavelength nanoscale dimensions by tightly focused laser beams but remains challenging to control due to complexity of ultrashort pulse propagation in nonlinear medium and is mainly associated with laser material damage in laser processing [1]. Subwavelength nanostructures and their periodic planar arrangements (metasurfaces) enable not only plasma confinement on record nanoscales by ultrashort laser excitation [2] but also better control over the nonlinear optical response while resisting to material damage [3], which is promising for new-generation optical devices for light manipulation and modulation.Modeling of the involved physical processes remains challenging, as it requires coupling non-paraxial full-vector light propagation in nonlinear medium with a comprehensive model for electronic excitation and material ionization at high intensities. Laser interaction with subwavelength nanostructures is discussed in the frame of 3D plasma fluid model coupled with nonlinear Maxwell propagation solver. Simulation results elucidate the spatio-temporal aspects of the electron-hole plasmas and their influence on ultrashort pulse propagation and harmonic generation.Apart from numerous applications relying on transient optical properties, plasma nanoconfinement in nanostructured transparent materials opens new opportunities for controlling thermal gradients, melt flow, and ablation at the nanoscale, with the ultimate objective to develop new strategies for nanofabrication and adjustment of metasurfaces.Références[1] A. Rudenko, J. V. Moloney, and P. Polynkin, Phys. Rev. Appl., Vol. 20, 064035 (2023)[2] A. Rudenko, K. Ladutenko, S. Makarov, and T. E. Itina, Adv. Opt. Mater., Vol. 7, 12306 (2018)[3] A. Rudenko, A. Han, and J. V. Moloney, Adv. Opt. Mater., Vol. 11, 2, 2201654 (2023
Ultrashort laser-driven compressible fluid dynamics in nanostructured targets
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Ultrashort Carbon Nanotubes with Luminescent Color Centers Are Bright NIR-II Nanoemitters
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A versatile microfluidic extrusion-based hydrogel platform for self-organization and long-term maintenance of engineered 3D lymphatic endothelium
No full textInternational audienceLymphatic endothelium is essential for interstitial fluid drainage, immune surveillance, and macromolecular transport. Existing in vitro models that accurately recapitulate its three-dimensional structure, barrier properties, and long-term stability are still limited. In this study, we propose a robust, adaptable, and scalable platform designed to generate engineered three-dimensional lymphatic endothelium using primary human dermal lymphatic endothelial cells (HDLECs). This system combines microfluidic extrusion-based fabrication allowing precise control of the tubular geometry with custom-optimized extracellular matrix–derived hydrogel. The capability to tune dimensions enables the creation of constructs that encompass physiologically relevant size ranges. Through a systematic matrix screen, we identified a unique four-component formulation—gelatin, Matrigel, hyaluronic acid, and fibrinogen—that supports the rapid self-assembly of HDLECs into stable, lumen-forming monolayers within one week. These engineered structures maintain viability and structural integrity for a minimum of 30 days under static culture conditions. Functional permeability assays demonstrated selective tracer uptake characteristics of lymphatic transport. Comparative studies with blood vascular endothelial cells indicate that the proposed platform preserves maintenance of lineage-specific expression profiles, junctional organization, and permeability properties under identical fabrication parameters. Altogether, this approach offers a reproducible and controlled system for studying three-dimensional endothelial architecture, transport mechanisms, and extracellular matrix remodeling across diverse endothelial phenotypes, thereby addressing a pivotal gap in the modeling of lymphatic vasculature. Highlights A microfluidic extrusion platform allows primary human lymphatic endothelial cells to self-organize into 3D hollow tubes. The internal dimensions of the hybrid cell/hydrogel constructs can be precisely controlled by tuning the flow rates. A custom-defined four-component extracellular matrix provides essential biochemical cues for stable monolayer formation and for the in vitro organization of lymphatic endothelial vessels. Matrix composition significantly influences cell proliferation and migration, thereby impacting on the spatial arrangement of the tissue. The three-dimensional lymphatic tissue configuration sustains cell viability, consistent expression of lineage-specific markers, and barrier function which lasts for at least 30 days. The system maintains morphological and functional properties not only for lymphatic endothelial cells, but also for blood endothelial cells in long-term culture conditions
Very High Precision Astrometry for Exoplanets and Dark Matter with the Habitable Worlds Observatory
No full textInternational audienceAstrometry, one of the oldest branches of astronomy, has been revolutionized by missions like Hipparcos and especially Gaia, which mapped billions of stars with extraordinary precision. However, challenges such as detecting Earth-like exoplanets in nearby habitable zones and probing the influence of dark matter in galactic environments require sub-microarcsecond accuracy.With a 6–8 meter large-aperture telescope operating across at visible wavelengths, the Habitable Worlds Observatory by NASA can combine astrometry and direct imaging to detect rocky exoplanets within 10 parsecs and study their atmospheres. We consider here the scientific requirements and present a concept for a dedicated astrometric instrument on HWO. It is capable to produce diffraction-limited images of large fields, achieving a point-spread function (PSF) precision of 20 milliarcseconds. Equipped with a detector calibration system, HWO can perform high precision astrometry, and, detect and measure the orbit of Earth-mass planets in the habitable zone of Nearby Solar-type stars. HWO can dramatically improve current constraints on the self- interaction cross-section of heavy dark matter particles (WIMPs) and on the masses of ultra-high dark matter particles, through the study of stellar motions in galactic environments.The visible channel of the instrument features a large CMOS-based focal plane with stitched pixel arrays, enabling a large field of view. The “Detector Calibration Unit” system uses interferometric laser fringes to calibrate pixel positions. Using differential astrometry and pointed observations with a stable telescope design enables extended integration times, enhancing sensitivity to sub-microarcsecond precision for detecting exoplanets and studying dark matter through stellar motion
Fused Filament Fabrication of silicon carbide parts: A strategy for producing high-strength components
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Techniques avancées d’attaques par injection de fautes sur circuits intégrés
No full textThe security of integrated circuits is evaluated through the implementation of attacks that exploit their inherent hardware vulnerabilities. Fault injection attacks represent a technique that is commonly employed for this purpose. These techniques permit an attacker to alter the nominal operation of the component in order to obtain confidential information. The principal techniques for localised fault injection are laser and electromagnetic injection. Recently, pioneering work has demonstrated that X-rays can also modify the behaviour of a circuit. The objective of this thesis is to assess the potential of fault attacks. This is achieved by advancing the existing state of the art, with a particular focus on laser and X-ray fault injection attacks on Flash memories of microcontrollers dedicated to the IoT. The aim of this study is twofold : firstly, to highlight the threat posed by these attacks and secondly, to gain insight into the associated mechanisms. These steps are crucial for the development of effective countermeasures. Firstly, after outlining the limitations of single-spot laser benches, we present a detailed analysis of the significant advantages offered by a new multispot laser bench, particularly in terms of spatial and temporal capacity. The study goes on to describe a number of concrete examplesof scenarios that are now achievable, and also carries out a theoretical exploration of the new possibilities offered by the laser bench. Secondly, we propose the utilisation of the thermal effect of an infrared laser bench for the injection of persistent faults into the Flash memory of unpowered components. This novel attack vector gives rise to the delineation of a comprehensive new fault model, encompassing both the physical and application levels. The outcomes obtained facilitate the reverse engineering of the Flash memory of the targeted component and the extraction of the encryption key for a software implementation of the AES encryption algorithm. The final section of the thesis describes the use of unfocused X-ray sources for the injection of faults into the Flash memories of both powered and unpowered components. Furthermore, the thermal and temporal recovery phenomena are also characterised. The design and characterisation of masks that enable the focused injection of faults are demonstrated.La sécurité physique des circuits intégrés est souvent évaluée en menant des attaques qui exploitent leurs vulnérabilités matérielles. Les attaques par injection de fautes sont une technique couramment utilisée dans cet objectif d’évaluation. Elles permettent à un attaquant d’altérer le fonctionnement nominal du composant afin d’obtenir des informations confidentielles. Les techniques principales d’injection de fautes localisées sont les injections laser et électromagnétique. Plus récemment, des travaux pionniers ont montrés que les rayons X pouvaient également modifier le comportement d’un circuit. L’objectif de cette thèse est d’évaluer le potentiel des attaques en fautes. Cela se fait en améliorant l’état de l’art existant, notamment sur les attaques par injection de fautes laser et rayons X, sur des mémoires Flash de microcontrôleurs dédiés à des applications IoT. La finalité de cette étude est de contribuer à la prise en compte de la menace que constituent ces attaques mais également de comprendre les phénomènes associés. Ces points constituent les premiers pas en vue de la conception de contre-mesures adaptées. Premièrement, après une description des limitations des bancs laser monospot, nous caractérisons les avantages significatifs, notamment d’un point de vue spatial et temporel, apportés par un nouveau banc laser multispot. Des exemples concrets de scénarios désormais atteignables sont décrits et une exploration théorique des nouvelles possibilités offertes par le banc laser est également réalisée. Deuxièmement, nous mettons en lumière la possibilité d’utiliser l’effet thermique d’un banc laser infrarouge afin d’injecter des fautes persistantes au sein de mémoires Flash de composants non alimentés. Ce nouveau vecteur d’attaque aboutit à la description d’un nouveau modèle de faute complet allant du niveau physique au niveau applicatif. Les résultats obtenus nous permettent d’une part, de réaliser l’ingénierie inverse de la mémoire Flash du composant ciblé et d’autre part, de retrouver la clé de chiffrement d’une implémentation logicielle de l’algorithme de chiffrement AES. Pour finir, l’utilisation de sources non focalisées de rayons X est décrite dans le but d’injecter des fautes dans des mémoires Flash de composants alimentés et non alimentés. Les phénomènes de récupération thermique et temporelle sont également caractérisés. La conception et la caractérisation de masques permettant, dans une certaine mesure, de focaliser l’injection de fautes est mise en pratique