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microRNA blood signature for localized radiation injury
No full textInternational audienceA radiological accident, whether from industrial, medical, or malicious origin, may result in localized exposure to high doses of ionizing radiations, leading to the development of local radiation injury (LRI), that may evolve toward deep ulceration and necrosis of the skin and underlying tissues. Early diagnosis is therefore crucial to facilitate identification and management of LRI victims. Circulating microRNAs (miRNA) have been studied as potential diagnostic biomarkers of several diseases including hematological defects following whole-body irradiation (WBI). This study aims to identify a blood miRNA signature associated with LRI in a preclinical C57BL/6J mouse model of hindlimb irradiation using different 10-MV X-ray doses that lead to injuries of different severities. To this end, we first performed broad-spectrum plasma miRNA profiling, followed by a targeted validation step, on two independent animal cohorts. Using a multivariate sparse partial least square discriminant analysis, we identified a panel of eight circulating miRNAs able to segregate mice according to LRI severity. Interestingly, these miRNAs were previously associated with WBI (miR-150-5p, miR-342-3p, miR-146a-5p), inflammation (miR-18a-5p, miR-148b-3p, miR-532-5p) and skin diseases (miR-139-5p, miR-195-5p). Our results suggest the use of circulating miRNAs as suitable molecular biomarkers for LRI prognosis and diagnosis
Delayed deformation of confinement buildings: 30-years in-situ measured data and prediction with the next-generation Eurocode-2
No full textInternational audienceBiaxially prestressed large concrete structures of the confinement building in nuclear power plants should meet the safety requirement for the extension of the service time. Long-term delayed strains of concrete are one of the key factors determining the safety factor in these structures. This article presents 30-year long in-situ measurement results of strain evolution of confinement buildings in four different nuclear power plants. The delayed strains are predicted at a material level using the next-generation Eurocode 2, and the influence of temperature as proposed by the fib model code 2010, making use of delayed strain characteristics of the corresponding concrete from a previous study. We found that the default law given in Eurocode underestimates the delayed strain. However, with provided possibility of adjusting the shrinkage and creep laws, the prediction results fit with a good accuracy the in-situ measurement
Accurate deep learning-based filtering for chaotic dynamics by identifying instabilities without an ensemble
No full textInternational audienceWe investigate the ability to discover data assimilation (DA) schemes meant for chaotic dynamics with deep learning. The focus is on learning the analysis step of sequential DA, from state trajectories and their observations, using a simple residual convolutional neural network, while assuming the dynamics to be known. Experiments are performed with the Lorenz 96 dynamics, which display spatiotemporal chaos and for which solid benchmarks for DA performance exist. The accuracy of the states obtained from the learned analysis approaches that of the best possibly tuned ensemble Kalman filter and is far better than that of variational DA alternatives. Critically, this can be achieved while propagating even just a single state in the forecast step. We investigate the reason for achieving ensemble filtering accuracy without an ensemble. We diagnose that the analysis scheme actually identifies key dynamical perturbations, mildly aligned with the unstable subspace, from the forecast state alone, without any ensemble-based covariances representation. This reveals that the analysis scheme has learned some multiplicative ergodic theorem associated to the DA process seen as a non-autonomous random dynamical system
Resource leveling: complexity of a unit execution time two-processor scheduling variant and related problems
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Degradation and Self-Healing of Halide Perovskites under X-ray Irradiation
No full textInternational audienceHalide perovskites have emerged as a highly promising class of materials across various optoelectronic applications, encompassing solar cell technology, light-emitting diodes (LEDs), lasers, and X-ray detection. However, the advancement of perovskite X-ray detector technology remains in its early stages, necessitating further research to comprehensively elucidate the properties of these materials and their responses to external stimuli. Furthermore, given the prevalent utilization of X-rays in fundamental chemical surface analysis techniques like X-ray photoelectron spectroscopy (XPS), a thorough understanding of the effects of X-ray exposure on halide perovskites is imperative for the accurate interpretation of surface characterizations via XPS and related methodologies. This imperative is accentuated in the context of operando experiments, wherein materials endure prolonged exposure to high doses of X-rays.We propose a comprehensive, multi-scale, and multi-technique approach by integrating X-ray photoelectron spectroscopy with steady-state photoluminescence imaging to investigate the detrimental effects and subsequent self-healing of Formamidinium Lead Bromide (FAPbBr3) under ion bombardment and X-ray irradiation 1 . We observed that short and low flux irradiation with synchrotron light causes local decomposition of FAPbBr3 into PbBr2. Concomitantly, metallic lead clusters are created in the decomposed sites by further decomposition of PbBr2, causing pinning of the Fermi level close to the conduction band. Conversely, prolonged exposure to higher-flux irradiation prompts mechanisms akin to local self-healing, facilitating the restoration of optoelectronic characteristics. Ion migration is key to "heal" the surface as the lost Br atoms on the surface are replenished by Br atoms coming from the underlying material.Subsequently, our investigation extends to triple-cation double-halide Cs0.05(MA0.14, FA0.86)0.95 Pb(I0.84, Br0.16)3 perovskite thin films, employing a comparable experimental framework 2 . Employing an array of optical imaging techniques, including spectrally and temporally resolved methodologies such as hyperspectral imaging and time-resolved fluorescence imaging (TR-FLIM), in combination with surface chemistry analysis via XPS, we delineate two principal degradation pathways within the perovskite layer. At lower X-ray fluences, we observe minor alterations in surface chemistry composition alongside the emergence of electronic defects. Conversely, a second degradation route occurring at higher fluence leads to the evaporation of the organic cations and the formation of an iodine-poor perovskite showing a faster carrier decay time. Leveraging insights derived from localized variations in optoelectronic properties, we propose a kinetic model elucidating the underlying mechanisms governing these degradation phenomena
Consequences of global warming in the Rhône River on the physiology of Alburnoides bipunctatus
No full textInternational audienceNowadays, global warming is a real issue and scientists are trying to find ways to anticipate its effects on wildlife, especially ectotherms as there are the first in line to be impacted by temperature increase. Indeed, their body temperature directly depends on environmental temperature, which is a factor that drastically influences biochemical and physiological reaction rates and, in fine, body condition and behaviour. We chose to study two different populations of a pelagic fish, Alburnoides bipunctatus, that were caught mid-February 2024 upstream or downstream of the Bugey nuclear power plant, located along the Rhône River. Indeed, as the water is warmer downstream from the power plant, this river section can be regarded as a “future condition” considering global warming. So, we wondered whether downstream fish had different adaptations regarding thermal tolerance, thermal preference and swim performance compared to the upstream ones. Both populations were kept at 12°C before entering experimentation. 12 fish from each population were put through 3 experiments which were randomised in order for 3 weeks, so each fish had a week of recovery between each experiment. Our aim was to characterize the phenotypes of the two populations through different physiological and behavioural experimental protocols. We used CTmax (critical thermal maximum), which is a commonly used metric to measure an organism’s upper thermal tolerance limit and a Ucrit protocol, which is the most known method to measure swimming performance in fish and can be considered as a proxy of the fish’s general fitness and well-being. This protocol was also linked to MO2 measurement. The fish were also put in a shuttle box with dynamic temperature change to elucidate their thermal preference.We supposed that upstream fish would be in better condition than downstream ones, but that the latter would probably have a higher metabolism, higher CTmax and higher thermal preference as they live in a warmer environment. Indeed, downstream fish had a greater CTmax than upstream ones, indicating that their upper thermal limit is higher. Interestingly, both groups had a similar thermal preference but the variance among the downstream fish was high. Upstream fish had a greater Ucrit, indicating that they may be in better condition, and their metabolic rates were also higher. However, upstream fish were the smallest, so there is an effect of size on our results. Consequently, even though most of the fish are juveniles, our results could be driven by the metabolic theory of ecology
Embrittlement induced by oxidation in polyethylene: Role of initial bimodality
No full textInternational audienceHigh density polyethylene films (200 µm) with an initial bimodal chain length distribution were aged in ovens at 60°C, 70°C, and 80°C. Oxidation effects were characterized at the macromolecular scale to measure the chain length distribution, the amount of crystalline phase, the type of crystallites, and the thickness of the amorphous layer. Additionally, mechanical properties were measured using tensile tests. Regardless of the aging temperature, the same behavior was observed: bimodal chain length distribution became unimodal, the crystallinity ratio increased, the amorphous layer thickness decreased, and the polyethylene became brittle. The embrittlement of the polymer is discussed, and two criteria are proposed: a critical molar mass and a critical amorphous layer thickness. The latter appears to be independent of the initial chain length distribution of the polyethylene
Face à l’écran noir : comment reconstruire l’organisation et le sens du travail suite à une crise cyber ?
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Model-based Head Losses Estimation for Hydropower Plants
No full textInternational audienceIn this paper, we present multiple methods for estimating headl osses, relying on a state-space model of a hydropower plant and taking into account the available data and operating conditions. In addition, these methods can quantify any sensor bias. To assess these approaches, we conducted both simulations and operational validation using data gathered from an operating power plant