Hal - Université Grenoble Alpes
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Density dependence of measured line intensities for O2 transitions
No full textInternational audienceWe report predictions and measurements of O2 absorption spectra that exhibit line intensity depletion with increasing gas density. This effect, which is attributed to the finite duration of collisions, alters the line shape by redistributing a portion of the intensity from a relatively narrow spectrum that can be described by an impact-approximation-based profile to a broad pedestal with a width that is inversely related to the collision duration. Using classical molecular dynamics simulations (CMDS), we predicted details regarding this mechanism for O2 with four collision partners: O2, N2, Ar, and He at a temperature of 296 K. These simulations were validated by comparisons with experimental intensity depletion coefficients obtained from absorption spectra of the 1.27 μm band of O2 in air; Ar and He acquired over a wide pressure range up to 120 kPa. All experimental spectra were recorded using high-precision cavity ring-down spectroscopy (CRDS) apparatuses at NIST (United States of America) and LIPhy (France). For air-broadened O2, more specifically, a mean depletion value of ∼0.3% amagat−1 was observed, with almost no resolvable rotational dependence. The temperature dependence of the intensity depletion in this system was also investigated by CMDS at 250 and 296 K and by CRDS spectra of air at 250, 275, and 296 K. The theoretical results suggest a nearly 1/T2 temperature dependence of the intensity-weighted depletion coefficient, which over the limited temperature range considered, was only slightly greater than the measurement precision. Finally, simulations of atmospheric solar absorption spectra were implemented to quantify the impact of neglecting this depletion effect on the retrieved surface pressure, resulting in a negatively biased measurement of ∼0.14%, with a spread of ∼0.02% caused by seasonal variations in gas temperature
Évaluation de la proportion des patients prêts à accepter une écoprescription proposée par leur médecin traitant dans le cas d’une rhinopharyngite
No full textStudy objective: This study aims to assess the proportion of patients willing to accept an eco-prescription proposed by their general practitioner for rhinopharyngitis. Introduction: Climate change, fueled by greenhouse gas emissions, constitutes a fundamental threat to health according to the WHO. In France, the healthcare system accounts for 8% of national emissions, more than half of which is linked to the purchase of medications and medical devices. Added to this are significant volumes of waste, particularly related to treatments and healthcare procedures. Faced with these challenges, eco-prescribing, which aims to integrate environmental impact into therapeutic choices, including waste management, appears to be a relevant approach. Rhinopharyngitis, an acute, common, and benign condition, thus provides a relevant example to illustrate eco-prescribing. Here, eco-prescribing involves prioritizing a non-pharmacological approach through the use of a reusable nasal irrigation device. This approach helps to limit prescriptions not recommended by the High Authority for Health (HAS), and reduces waste and greenhouse gas emissions associated with the use of products commonly used in the case of rhinopharyngitis. Methodology: A quantitative study was conducted in two medical practices, one multidisciplinary health centers and two pharmacies in the Rhône-Alpes region, and three multidisciplinary health centers and three pharmacies in the Nouvelle-Aquitaine region, from mid-May to mid-September 2025. A self-administered questionnaire assessed the primary objective: the proportion of patients willing to accept an eco-prescription for rhinopharyngitis. Several secondary objectives were also assessed: the typical patient profile, potential barriers, and patients' knowledge of medication packaging waste and impact of the healthcare system on the environment. Results: From 368 questionnaires analyzed, 83% of patients accepted an eco-prescription for rhinopharyngitis. Typical patient profiles could not be identified due to insufficient statistical power. Several barriers were highlighted, and patients appear to be aware of the environmental impact of medications. Discussion: A majority of patients are ready to accept eco-prescribing. The identified obstacles could be overcome through appropriate therapeutic education. Doctors, pharmacists, and patients all have a role to play in the shift towards eco-prescribing practices, not forgetting legislators and industry.But de l’étude : Cette étude a pour objectif d’évaluer la proportion des patients prêts à accepter une écoprescription proposée par leur medecin traitant dans le cas d’une rhinopharyngite. Introduction : Le changement climatique, alimenté par les émissions de gaz à effet de serre, constitue une menace fondamentale pour la santé selon l’OMS. En France, le système de santé représente 8 % des émissions nationales, dont plus de la moitié est liée à l’achat de médicaments et de dispositifs médicaux. À cela s’ajoutent d’importants volume de déchets, notamment liés aux traitements et actes de soins. Face à ces enjeux, l’écoprescription, visant à considérer l’impact environnemental dans les choix thérapeutiques, apparaît comme une approche pertinente. La rhinopharyngite, affection aiguë, fréquente et bénigne, constitue ainsi un exemple approprié pour illustrer l’écoprescription. L’écoprescription correspond ici à privilégier une approche non médicamenteuse via l’utilisation du dispositif réutilisable de lavage de nez. Cette approche permet de limiter les prescriptions non recommandées par la Haute Autorité de Santé (HAS), et réduit les déchets et les émissions de gaz à effet de serre associés à l’utilisation de produits couramment employés dans le cas d’une rhinopharyngite. Methodologie : Une étude quantitative a été réalisée auprès de deux cabinets médicaux, une maison de santé pluridisciplinaire et deux pharmacies en région Rhône-Alpes ainsi que trois maisons de santé pluridisciplinaire et trois pharmacies en région Nouvelle-Aquitaine, de mi-mai à mi-septembre 2025. Un questionnaire auto-administré évaluait la part des patients prêts à accepter une écoprescription dans le cas d’une rhinopharyngite. Plusieurs objectifs secondaires étaient également étudiés, à savoir le profil type des patients favorables à l’écoprescription, les freins éventuels, et les connaissances des patients sur les déchets des emballages médicamenteux ainsi que sur l’impact du système de santé sur l’environnement. Résultats : Sur 368 questionnaires analysés, 83% des patients acceptaient une écoprescription dans le cas de la rhinopharyngite. Les profils types de patients n’ont pas pu être identifiés par manque de puissance statistique. Différents freins ont été mis en évidence et les patients semblaient avoir conscience de l’impact des médicaments sur l’environnement. Discussion : Une majorité des patients est prête à accepter l’écoprescription. Les freins identifiés pourraient être levés par une éducation thérapeutique adaptée. Le médecin, le pharmacien, et l’usager ont un rôle dans l’évolution des pratiques vers l’écoprescription, sans oublier le législateur et l’industriel
Theories with no superluminal signaling have greater information-processing power than theories with no superluminal causation
No full textInternational audienceA central goal in the foundations of physics is to understand the structure of physical theories, such as quantum theory, from physical principles. This is often explored by considering various information-theoretic principles. Here, we initiate a similar approach considering relativistic causality principles. No superluminal causation (NSC) and no superluminal signaling (NSS) are distinct relativistic principles, requiring respectively that causal influence/the ability of agents to signal are within the future lightcone. After formalizing their distinction, we investigate how well theories constrained by NSC and NSS perform in a task that involves generating nonclassical correlations. We find a spacetime configuration in which this task cannot be achieved in any theory (classical, quantum, or postquantum) satisfying NSC. However, we show that theories violating NSC but satisfying NSS can perfectly achieve the task. We give a protocol that would, in a world allowing superluminal causation, enable its operational certification without violating NSS, in general spacetimes. In the case of (1 + 1)-dimensional Minkowski spacetime, the task remains achievable in a configuration where measurement outcomes occur arbitrarily earlier in time than the settings, allowing a form of certifiable retrocausality without violating NSS. We illustrate our results by linking two different types of nonclassical postquantum resources: PR boxes and jamming. Our work offers insights into the role of different relativistic causality principles in fundamental physics and paves the way for characterizing the information-theoretic structure of theories obeying such principles
Association Between Metabolic Syndrome, Obesity, and Cognitive Performances in Individuals With Bipolar Disorders: Cross‐Sectional and Longitudinal Analyses in the FACE ‐ BD Cohort
No full textInternational audienceIntroduction: Metabolic syndrome (MetS) has been suggested to be associated with cognitive impairments in bipolar disorder (BD); however, studies are limited by small sample sizes or cross-sectional design. Our objective is to evaluate the cross-sectional and longitudinal associations between MetS and cognitive performances in a large cohort of individuals with BD.Methods: 1175 individuals with a DSM-IV diagnosis of BD were included from the FACE-BD cohort, assessed with a standardized battery of clinical and neuropsychological tests and followed up with a cognitive retest at 2 years for a subsample (n = 367). A global cognitive index was created by using a Principal Component Analysis. Associations between MetS and cognitive performances at baseline were explored using multiple analyses of covariance and linear mixed models were used for longitudinal data.Results: The prevalence of MetS was 21.5% in this sample. Multivariable analyses identified associations between MetS and poorer cognitive performance in the cross-sectional analysis, independently of age, gender, education level, psychotropic treatments, and comorbidities. Specifically, individuals with MetS showed poorer results (global cognitive index, cognitive flexibility, inhibition, and verbal memory). After adjustment, the longitudinal analysis showed no change in the global cognitive index at year 2 and no time × metabolic syndrome interaction.Conclusions: Our results suggest that MetS is cross-sectionally, but not longitudinally, associated with poorer cognitive performances in BD. This study highlights the importance of systematically and accurately screening for metabolic abnormalities in individuals with BD, and screening for cognitive deficit especially in individuals with MetS. Our results suggest that MetS is not a risk factor for cognitive decline during the follow-up, but further longitudinal studies are required
Passivity-based Trajectory Tracking Control in Frictional Oscillators with Set-valued Friction
No full textInternational audienceThis article is largely concerned with the trajectory tracking control of frictional oscillators, which are nonsmooth nonlinear dynamical systems. The trajectory tracking problem, which is studied under a passivity-based controller addresses three main cases: the nominal case with known friction coefficient, uncertain friction coefficient, and when the Coulomb friction model is enhanced by including Stribeck effects. Monotonicity (or hypomonotonicity) of the friction model is crucial for the stability analysis of the tracking error. It can be relaxed to hypomonotonicity to handle Stribeck model. The framework of linear complementarity systems is used for the analysis. The case of a twomass system is tackled as an extension of the standard one-mass oscillator. Theoretical results are supported by numerical simulations
Slug flow boiling in microchannels at high vapour volume fraction
No full textInternational audienceIn this work, we experimentally study the thermal performance and bubbly flow characteristicsof convective boiling inside a multi-microchannel exchanger operated in slug flow regime at highvapour volume fraction with CO2 as the working fluid. To that purpose, flow regime and heattransfer are characterised for a silicon/pyrex heat exchanger containing 16 parallel microchannelsof hydraulic diameter 183 μm, for saturation temperatures close to −35◦C, mass fluxes between258 kg/(m2s) and 537 kg/(m2s), heat fluxes range 12.7 − 69 kW/m2 and inlet vapour volumefraction ranging from 68% up to 85%. The investigated boiling flow is characterised by a laminarregime, a high confinement, a small Capillary number (Ca < 0.036) and a Jakob number rangeof 0.1 ≤ Ja ≤ 1. At high vapour volume fraction, the heat transfer is found to be monitored bythe heat transport in the liquid film forms between bubbles and the wall because the contact timewith bubbles (and liquid film) is much larger than the contact time with liquid slugs. In addition,since at wall the film velocity vanishes because of adherence, experimental Nusselt numbers arefound to be close to the one predicted by the pure heat conduction problem in the liquid film. Thisbehaviour explains why the experimental heat transfer coefficient is systematically degraded whenthe flow velocity and the liquid film thickness increase together. This study represents the firstmeasurement of heat transfer coefficients for CO2 boiling flow below −30◦C and for an hydraulicdiameter below 200 μm. Such a silicon exchanger design can be useful for the direct cooling ofCMOS sensors at negative temperatures without thermal interface between the refrigerant and thesubstrate
Flood pulse monitoring in wetlands with multi-temporal Sentinel-1 interferometric coherence data: Application to the Okavango Delta (Botswana)
No full textInternational audienceFlood-pulsed wetlands are characterized by significant seasonal water fluctuations, which play a critical role in the dynamics of these sensitive ecosystems. Among the growing number of existing remote sensing products, we explore the potential of interferometric (InSAR) coherence time series, derived from Sentinel-1 synthetic-aperture radar images, to characterize the hydrological dynamics of the Okavango Delta, a vast flood-pulsed wetland. Interferometric coherence reflects changes in surface conditions, making it a powerful tool for detecting flood propagation. By fitting harmonic functions, we produce parameters that quantify the seasonality of coherence time series with short isotemporal baselines (12 days). In particular, we developed a normalized seasonal index based on the ratio between the seasonal amplitude and the root-mean-square error of the fitted harmonic function, to map the seasonality of the coherence time series. A multi-annual analysis of coherence time series reveals a strong relationship between their seasonality, land cover, and flood frequency. Unsupervised clustering applied to statistical and seasonal metrics of coherence time series yields consistent classifications that map the variability of flood frequencies across wetland areas and clearly distinguish wetlands from dry zones. Similarly thresholds applied to normalized seasonal indices delineate the year-to-year extent of flood pulses with accuracy around 79 %. We show that coherence time series in never flooded areas exhibit a pronounced seasonal pattern driven by rainfall cycle, whereas this seasonality is disrupted by flood pulses in wetlands. Building on this, developed a change-detection approach to map the floods by identifying the date when coherence time series diverge from their seasonal pattern. The resulting flood arrival dates achieve 74–83 % accuracy compared to a reference dataset derived from optical data. Our results highlight the potential of coherence time series as a robust indicator of seasonal variations in inundation extent in flood-pulsed wetlands
Assessing radiofrequency safety of active implants by measuring induced radiofrequency currents using MRI
No full textInternational audiencePurpose: During MRI in the presence of active wire-like implants, such as deep brain stimulation leads, there is a risk of thermal lesions in tissues adjacent to implant contacts due to radiofrequency currents induced in the wire. Currently, there is no established method to evaluate the radiofrequency (RF) safety of an implant in situ, due to complex interactions between the implant and the electric field inside the patient during MRI. This article presents a method to quantify the RF current in an implant using MRI acquisitions at very low SAR.Theory and Methods: To measure RF current in situ, a modified B1-mapping sequence is proposed to image the associated perturbation of the B + 1 field. A forward signal model links the RF current intensity to the MRI signal and is used to fit the RF current from acquired data. Electromagnetic simulations and experiments on a homogeneous phantom are presented for simplified and real implant wires to validate the method.Results: The presented model can correctly reconstruct RF current amplitudes from field maps obtained with detailed electromagnetic simulations, with a normalized RMS error of 4.7%. Phantom experiments show a good linearity between the square of the current measured by MRI and temperature increase (R 2 > 0.91), demonstrating that the RF current measurements quantitatively represent the effective heating.Conclusion: A method has been developed to quantify the RF current in situ from MRI signals. This method enables to predict the individual heating risk for other MRI sequences performed in the same scanning session
Across ancient oceans: Eocene dispersal routes of Asian terrestrial mammals to Europe, Afro-Arabia and South America
No full textInternational audienceDuring the middle and late Eocene, Asian terrestrial mammals dispersed to Europe, while primates and rodents dispersed across the 500-to-2000 km wide Neotethys Ocean and the 1500-to-2000 km wide Atlantic Ocean to colonize Afro-Arabia and South America. This study explores how these mammals have achieved such remarkable and enigmatic dispersals. We present high-resolution paleogeographic models for the middle to late Eocene based on updated plate kinematic reconstructions, paleo-bathymetry and paleo-topography data. With this, we evaluate landmass configurations and connectivity that may have facilitated faunal exchanges from Asia toward Europe, Afro-Arabia, and South America and discuss dispersal mechanisms between these biogeographic provinces. Our reconstructions reveal that during the Bartonian (~40–38 Ma), an overland dispersal corridor between Asia and Balkanatolia became available to terrestrial mammals and acted as a pivotal pathway for Asian faunas dispersing toward western Europe and Afro-Arabia. We identified two Balkanatolian island-hopping routes across the Western Neotethys potentially enabling the dispersal of small-bodied Asian primates, rodents and artiodactyls to Afro-Arabia. Alternatively, these taxa may have rafted across the Central Neotethys. By ~34 Ma, Balkanatolia fully connected with Western Europe, opening a southern “Grande Coupure” route for Asian faunas. In the Atlantic, we identify long-distance rafting as the most plausible mechanism for the 40–34 Ma transoceanic dispersal of the Asian-originated primates and rodents from Afro-Arabia to South America despite the likely presence of sparse islands along the Walvis Ridge and the Rio Grande Rise
Target trial emulation to replicate randomised clinical trials using registry data in multiple sclerosis
No full textInternational audienceBackground: Target trial emulation (TTE) offers a formal framework for causal inference using observational data, but its validity must be evaluated in each research domain by replicating randomised clinical trials (RCTs). We aimed to replicate eight RCTs evaluating the efficacy of disease-modifying therapies (DMTs) in multiple sclerosis (MS) using French registry data.Methods: This multicentre, retrospective, observational study was conducted using data extracted in December 2023 from the Observatoire Français de la Sclérose en Plaques (OFSEP) database. For each emulated trial, patients were included when they initiated one of the DMT evaluated in the corresponding RCT and met its inclusion criteria. Clinical outcomes were the annualised relapse rate and 3-month confirmed Expanded Disability Status Scale progression. Radiological outcomes were new/enlarged T2-lesions and new gadolinium-enhanced T1-lesions on a brain MRI. A targeted maximum likelihood estimator was used to estimate the treatment effect adjusted for confounding factors between groups and corrected for censoring and missing outcome assessment.Results: 14 111 patients were included in eight emulated trials: ASSESS (fingolimod vs glatiramer acetate), BEYOND (interferon beta vs glatiramer acetate), CONFIRM (dimethyl fumarate (DMF) vs glatiramer acetate), OPERA (ocrelizumab vs interferon beta), REGARD (interferon beta vs glatiramer acetate), RIFUND-MS (rituximab vs DMF), TENERE (teriflunomide vs interferon beta) and TRANSFORMS (fingolimod vs interferon beta). Treatment effects estimated in emulated trials were concordant with RCT findings in seven of eight trials for relapse rate, and in all six trials assessing disability progression. Radiological outcomes were more challenging to replicate; concordance was achieved in three of five trials for new T2-lesions, and one of four trials for new gadolinium-enhanced T1-lesions.Conclusion: The combined use of a TTE methodology and high-quality registry data is a valid tool to evaluate treatment effectiveness in MS