HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
Not a member yet
13939 research outputs found
Sort by
Learning general pair interactions between self-propelled particles
No full textInternational audienceInference of general pair interactions between self-propelled particles from experimental trajectories.Synthetic active matter systems, such as active colloids, often have complex interactions, which can be of hydrodynamic, chemical or electrostatic origin and cannot be computed from first principles. Here, we use stochastic force inference to learn general pair interactions, including transverse forces and torques, between self-propelled Janus particles from experimental trajectories. We use data from two experiments: one where the particles flock, and one where the system remains disordered. The learned interactions are then fed to numerical simulations, which reproduce all the experimental observables and could be extrapolated to different densities. Overall, we find that the radial interaction is mostly repulsive and isotropic, while the angular interaction has a richer angular dependence, which controls the behavior of the system; the transverse interaction is negligible. Finally, testing the symmetry relations obeyed by the inferred interactions allows us to show that they cannot come from electrostatics only, so that they must have a hydrodynamic component
Flow-Induced Lateral Migration and Droplet Segregation in Flexible Rectangular Microchannels
No full textInternational audienc
Asymmetric bending boundary layer: The λ-test
No full textInternational audienceWe investigate the mechanics of two asymmetric ribbons bound at one end and pulled apart at the other ends. We characterize the elastic junction near the bonding and conceptualize it as a bending boundary layer. While the size of this junction decreases with the pulling force, we observe the surprising existence of the binding angle as a macroscopic signature of the bending stiffnesses. Our results thus challenge the standard assumption of neglecting bending stiffness of thin shells at large tensile loading. In addition, we show how the rotational response of the structure exhibits a nonlinear and universal behavior regardless of the ratio of asymmetry. Leveraging the independence of the binding angle to the pulling force, we finally introduce the λ-test — a visual measurement technique to characterize membranes through simple mechanical coupling
Detection of COPD exacerbations with continuous monitoring of breathing rate and inspiratory amplitude under oxygen therapy
No full textInternational audienceAbstract Background Chronic Obstructive Pulmonary Disease (COPD) is one of the main causes of morbidity and mortality worldwide. Its management represents real economic and public health burdens, accentuated by periods of acute disease deterioration, called exacerbations. Some researchers have studied the interest of monitoring patients’ breathing rate as an indicator of exacerbation, although achieving limited sensitivity and/or specificity. In this study, we look to improve the previously described method, by combining breathing variables, using multiple daily measures, and using an artificial intelligence-based novelty detection approach. Methods Patients with COPD were monitored with a telemedicine device during their stay in a rehabilitation care center. Daily measures are compared to individually trained reference models based on: i. oxygen therapy duration ii. mean breathing rate, iii. mean inspiratory amplitude, iv. mean breathing rate and mean inspiratory amplitude, v. average distribution of breathing rate and inspiratory amplitude, vi. hidden Markov model (HMM) from a time series of breathing rate and inspiratory amplitude. Results A set of 16 recordings with exacerbation and 23 recordings without exacerbation was obtained. When using a daily measure of breathing rate, pre-exacerbation periods were identified with a specificity of 50% and a sensitivity of 55.6%. The method based on daily oxygen therapy usage and the method based on time series obtain a sensitivity of 76.8% and 73.2%, respectively, for a fixed specificity of 50%. Conclusion A single daily measure of breathing rate alone is not sufficient for the detection of pre-exacerbation periods. More complete models also achieve limited performance, equivalent to models based on changes in the duration of therapy usage
Patch antenna enhanced charge-sensitive infrared phototransistors
No full textInternational audienceCharge-sensitive infrared phototransistors (CSIP) constitute an outstanding technology for mid-infrared detection with sensitivities demonstrated at the single photon level. Here, we report on the performances of CSIP detectors operating at a wavelength λ = 8.9 μm that are integrated into double-metal patch antenna resonators. In order to build such devices, we have developed a fabrication protocol that allows accommodating the phototransistor architecture with the double-metal geometry providing very strong electromagnetic field confinement. We observe minimal photon fluxes in the order of 7000 photons/s.μm2 that are 103 smaller with respect to previous realizations of devices with similar absorbing regions in a mesa geometry. This work opens additional perspectives for building ultra-small area devices, as required for single photon counters, while keeping high quantum absorption efficiencies
Hexaphyrin-Cyclodextrin Hybrids: Switching between Möbius and Hückel Aromatic Systems in Chiral Environment
No full textInternational audienc
Ultrasharp, Cavity Enhanced, Broadly Tunable Infrared Detection Using Colloidal Quantum Dots
No full textInternational audienceAfter the success of semiconductor nanocrystals as light sources for displays in the visible range, the infrared range now offers a complementary playground. Applications requiring chemical contrast in images and applications to LIDAR technology incentivize the development of devices with narrow spectral responses. However, the solutions that rely on introducing notch filters still suffer from imperfect transmission at the wavelength of interest in a spectral range where their detection is already difficult. Here, we explore the integration of a short-wave infrared detector directly into a dielectric microcavity. Our approach simultaneously achieves ultranarrow absorption lines below 30 cm -1 at a telecom wavelength, together with a broadband, continuous, postfabrication spectral tunability over 1200 cm -1 . By taking advantage of the field magnification inside the cavity, we demonstrate that the spectral shaping properties can be obtained while maintaining performances on par with an uncoupled device, stressing the benefit of this method compared to filter-only approaches
Development of hepatobiliary 3D models displaying heterotypic connections
No full textSelected on abstractInternational audienc
An untargeted data mining strategy for extracting chemical exposome signatures from LC-HRMS data: Application to meconium for early-life exposure assessment
No full textInternational audienceBackground: Exposome research has expanded rapidly in recent years, driven by advances in analytical techniques such as liquid chromatography-high-resolution mass spectrometry (LC-HRMS), which enable broad and sensitive chemical coverage. Targeted methods focus on known compounds, while untargeted metabolomic approaches provide a more holistic view and may reveal exposure biomarkers, but they are not specifically designed to detect exogenous chemicals. Identifying relevant exposure markers within the vast and complex datasets generated by untargeted LC-HRMS data remains a significant analytical and computational challenge, requiring innovative data mining strategies.</div
Impact of focused ultrasound on the cellular network of liver tissue: a new perspective for thermal lesion detection
No full textInternational audienceObjective. The noninvasive characterization of soft tissue microstructure remains challenging and has a significant clinical impact on diagnosis and therapy monitoring. During high-intensity focused ultrasound (HIFU) treatments, coagulation necrosis is accompanied by mechanical changes. The objective of this work is to use the anisotropy arising at the cellular level as a new biomarker for treatment evaluation. Approach. We demonstrate that HIFU induces anisotropic alterations in the cellular architecture of liver tissue, which are detectable through the angular dependence of the backscattering coefficient (BSC). Also, in vivo experiments reveal a distinct anisotropic histological pattern localized in the HIFU-treated region. Main results. We show that the degree of anisotropy deduced from BSC measurements is correlated with the histological observations. Moreover, anisotropy increases with delivered energy, providing a quantitative link between treatment parameters and tissue response. Significance. These findings establish BSC anisotropy as a previously unexplored signature of thermal lesions, offering a promising approach for monitoring and feedback in thermal therapeutic ultrasound applications. This breakthrough could open the door to next-generation imaging tools, accelerating the widespread adoption of this highly effective therapeutic modality