HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Physiological effects of nasal high flow therapy during exercise in patients with chronic obstructive pulmonary disease: A crossover randomised controlled trial
No full textInternational audienceNo abstract availabl
Démonstration de la percolation d'invasion par une expérience de coin de table
No full textInternational audienceThis paper highlights in an historical perspective a seminal "table-top" experiment [1] which, in the 80's, was one of the first experimental demonstrations of the relevance of invasion percolation to describe quasi-static drainage of a porous medium. This experiment involves the invasion of a crushed glass packing by molten Wood metal with a large influence of gravity. To account for it, data are compared to predictions of the gradient invasion percolation model in which the effect of buoyancy is modeled by a gradient of the percolation parameter. Experimental results agree well with 3D numerical simulations [2] based on this model. This demonstrates that such simple experiments using limited equipment may validate complex physical mechanisms. It is argued that while the availability of refined new techniques may seem to make this approach obsolete, such experiments remain needed to obtain pioneering results and to open new research fields. This conclusion aligns with Etienne Guyon's tireless action to initiate table-top experiments providing fundamental physics results
Ammonium-based polymers as clay swelling inhibitors to improve water resistance of earthen plasters
No full textInternational audienceRaw earth can be a sustainable and low-impact alternative to conven-tional building materials, but its vulnerability to water remains a critical limita-tion, particularly in regions subject to variable climate conditions. Biopolymers have shown promise in improving the mechanical properties of earthen materials, but their impact on water resistance is often inconsistent and poorly understood. In this study, we explored a new approach combining biopolymers with ammo-nium-based compounds to stabilize earthen plasters by inhibiting clay swelling. Using model clay systems (montmorillonite and kaolinite), we evaluated the ef-fects of several amine-based polymers, including polyethyleneimine, chitosan and ε-polylysine. X-ray diffraction (XRD) and Dynamic Vapor Sorption (DVS) measurements revealed that polymers of low molecular mass significantly reduce both crystalline and macroscopic swelling, with oligoethyleneimine proving more effective than its longer-chain counterparts. Similarly, short chains chitosan and ε-polylysine demonstrated effective swelling inhibition and reduced water affinity. This work highlights the potential of using ammonium-based polymers to enhance the durability and long-term stability of earthen constructions subject to environmental moisture variations
Détection photothermique améliorée par plasmon grâce à des nanodisques VO2/Au couplés
No full textInternational audienceVanadium dioxide (VO2 ) exhibits a remarkable insulator to metal transition at 68°C, accompanied by a significant change in electrical resistivity by several orders of magnitude. This distinctive property has led to proposals for its application as photodetectors or bolometers, leveraging the sensitivity of its resistance to temperature variations induced by absorbed photons. In this study, we demonstrate that the insulator to metal transition in VO2 thin film is facilitated by orderly arrays of Au nanodisks embedded within the material. Direct optical visualization at the submicron scale when the nanodisks are illuminated near their plasmon resonance with a lambda = 1.5 µm laser beam shows that the laser power required to induce the transition is reduced by 30% in the presence of Au nanodisks. With the aid of numerical simulations, we consider the mechanisms driving the transition finding that the localized dipolar pattern of the electromagnetic field surrounding the nanodisks penetrates deeply inside the VO2 , thereby being the primary cause of the modifications in the transition conditions
Enhancing Signal Purity in Josephson Structure Measurements
No full textInternational audienceSuperconducting Josephson structures play a significant role in quantum-state engineering. Achieving high-fidelity quantum state measurements in superconducting Josephson structures requires ultra-low noise environments and robust signal purification techniques. Here, the advanced low-noise signal measurement system designed for dilution refrigerators is presented, integrating multi-stage cryogenic filtering and electromagnetic shielding strategies to suppress noise sources across a broad frequency spectrum. The effectiveness of low-pass RC filters is demonstrated, silver-epoxy microwave absorbers, and optimized ground isolation to achieve an unprecedented noise reduction, enabling sub-nanoampere switching current distribution measurements superior to commerical systems at mK temperatures. The system is optimized for precision studies of superconductor-insulator-superconductor, superconductor-ferromagnet-superconductor, and superconductor-normal metal-superconductor Josephson junctions with low critical currents. This approach establishes a reliable framework for next-generation quantum electronic experiments, ensuring that observed switching phenomena are governed by intrinsic device physics rather than environmental perturbations
Irreversible swap algorithms for soft sphere glasses
No full textInternational audienceWe extend to soft repulsive interaction potentials a recently proposed irreversible swap algorithm originally designed for polydisperse hard spheres. The original algorithm performs rejection-free, irreversible, collective swap moves. We show that event-driven cluster updates of particle diameters can also be performed in continuous potentials by introducing a factorised Metropolis probability. However, the Metropolis factorisation needed to deal with continuous potentials decreases the efficiency of the algorithm and mitigates the benefits of breaking detailed balance. This leads us to propose another irreversible swap algorithm using the standard Metropolis probability that accelerates the relaxation of soft sphere glasses at low temperatures, compared to the original swap algorithm. We apply these efficient swap algorithms to produce very stable inherent structures with vibrational density of states lacking the quasi-localised excitations observed in conventional glasses
Seafoam avoidance is driven by both chemosensory and contact cues and points towards the presence of soft-surface thigmotaxis in the intertidal gastropod Littorina littorea
No full textInternational audienceSeafoam accumulation in coastal waters has long been acknowledged as ecologically, socially and economically relevant. However, its putative effects on the intertidal biota have been alarmingly under-researched despite the ubiquitous nature of onshore foam formation. This study examines the behavioural responses of the common periwinkle, Littorina littorea, exposed to two types of seafoam: a fresh seafoam (freshly formed) and an aged seafoam (collected after three hours of exposure in the field), using experimental assays carried out under controlled laboratory conditions. L. littorea consistently avoid seafoam, and exhibit a stronger aversion for fresh seafoam. They avoid crossing both seafoam, suggesting that contact cues play a crucial role in this avoidance behaviour. In this context, we introduce the concept of soft-surface thigmotaxis, by which L. littorea is able to follow soft physical discontinuities. Snails exhibited more tortuous movements and reduced speed before actually getting into physical contact with the fresh seafoam, suggesting that chemosensory influence foam avoidance, probably due to repellent volatile compounds requiring further identification. Observations suggest that snails show differential responses potentially influenced by variations in foam properties, such as phytoplankton content and the physical properties of the seafoam. Seafoam avoidance by L. littorea could have wider ecological implications by disrupting the snails' ability to find refuges, increasing their vulnerability to other environmental stresses. Investigating surfactants and pollutants in seafoam is crucial due to their toxicity to aquatic life. The study highlights the need for interdisciplinary research to fully understand and mitigate seafoam's effects on intertidal organism
High-risk human papillomavirus cervical infection prevalence: a nationwide retrospective study comparing opportunistic and organised screening, France, 2020 to 2023
No full textInternational audienceBACKGROUND In France, cervical cancer screening for females aged 30–65 years primarily tests for high-risk (HR) human papillomavirus (HPV) infections. AIM We aimed to map the prevalence of cervical infections caused by HPV16 and/or 18, or by any of 12 other carcinogenic HPV genotypes and compare prevalence estimates from tests from spontaneous medical visits (opportunistic screening) or the national screening programme (organised screening). METHODS We extracted data from a large network of biology laboratories, containing all available results from HR HPV tests performed between 1 January 2020 and 30 November 2023 in metropolitan France. A full hierarchical Bayesian model was used to compute spatially resolved expected prevalence maps at the postcode level. RESULTS The analytic sample contained results of 362,963 HR HPV tests. Among samples positive for HPV16 and/or 18, 2.9% and 3.8% were from organised and opportunistic screening, respectively. Samples positive for other genotypes were 6.9% and 9.4%, respectively. During the last week of the study (week 48 2023), among females aged 30 years, opportunistic screening was associated with a greater expected prevalence of HPV16 and/or 18 and other genotypes in 97.2% and 99.9% of postcodes, respectively. The probability this percentage was lower among females aged 66 years was below 95% for both genotype groups. For organised screening, a pronounced north-west/south-east gradient in infection prevalence was found across France for both genotype groups, with hotspots located at the border with Italy, Spain and Switzerland.CONCLUSION Opportunistic screening is associated with systematic inflation of HR HPV infection prevalence
Quantitative polarimetric wavefront imaging
No full textInternational audienceImaging both the polarization and the wavefront of a light beam is a complex task that typically demands several intensity acquisitions. Furthermore, sequential acquisition solutions are incompatible with the monitoring of ultra-fast processes. As a possible solution for single-shot wavefront and full-Stokes polarimetric imaging, we propose here a vector-beam lateral shearing interferometer. The device, composed of a patterned polarization-modulating Hartmann mask placed in close vicinity to a camera, encodes all the information in the fringe pattern of a single-image acquisition. By extending lateral shearing interferometry to vector beams, this work opens avenues for characterizing complex metasurfaces and biological samples.</div