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Intérêts didactiques d’un modèle précurseur dans l’enseignement et l’apprentissage des sciences à l’école primaire
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Solving Systems of Fractional Differential Equations by Using Physics Informed Deep Learning methods and Application to a Fractional Order Bergman’s Minimal Type Model of Insulin Injection
No full textInternational audienceFractional differential equations have recently demonstrated their importance in a variety of fields, including medicine and applied sciences. The goal of this study is to propose a method based on Physics Informed Neural Network (PINN) for solving differential equations of Caputo fractional order. The proposed method allows to use the knowledge about dynamic of the considered system (governing equation, conservation of energy,...) while exploiting the power of neural networks to solve differential equations and learn the underlying physics of such a system. First, we define a global framework for representing a system of differential equations and how classical PINN’s algorithm works. Then we explain two modifications of this classical algorithm. Next, in order to validate our approach, we showcase the method in various models including the non-linear Van Der Pol oscillation system. Further, we consider problem of blood glucose dynamic for type 1 diabetes using fractional differential equations to model the glucose-insulin metabolism in order to observe the memory effects and gain more insights about the dynamics of system. This model is obtained by considering an adjustment of a modified minimal model of Bergman by converting the model into fractional order model by fitting the fractional order Caputo differential operator in this modified Bergman model. The treatment of type 1 diabetes is based on subcutaneous insulin injections to compensate for declining insulin production by the pancreas. Some preliminary numerical simulations are performed to illustrate the effect of fractional order derivative approach and behavior of model solutions. Lastly, the conclusion and future perspectives are presented
First French case of fatal NPS poly-consumption involving bromazolam and 2-MMC: insights from NMR and LC-HRMS
No full textInternational audienceIdentifying poorly documented molecules as new psychoactive substances (NPS) is essential in toxicologically induced death cases. We report here the case of a 42-year-old woman who died in a context of NPS poly-consumption. Near the body were 10 bags labeled as Research Chemicals. Three of them, identified as bromazolam and 2-MMC, were empty. The seven other bags, labeled 4 F-MPH, 4-FMA, 2-MMC and O-DSMT contained tablets of various shapes and colors. The tablets and post-mortem blood samples were collected and analyzed. 1H NMR analyses (500 MHz, Bruker spectrometer) were performed on the tablets extracts. NPS identification and quantification in blood were performed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) (Q-Exactive®, Thermo Scientific). The post-mortem peripheral blood results showed the following concentrations: bromazolam 308 ng/mL, 2-MMC 12,616 ng/mL, O-desmethyl-tramadol 1,410 ng/mL, 4-FMA 3,176 ng/mL and 4 F-MPH 121 ng/mL. 2-MMC concentrations were higher compared to usual “lethal” concentrations reported in the literature. This study represents the first documented case of bromazolam use in France. 1H NMR analysis allowed to correlate the tablets content to the bag labelling, except for the sample 4 F-MPH which corresponds to 4-FMA. The identification and quantification of the NPS mixture in the blood allow us to conclude the toxicological origin of the cause of death. This case emphasizes the forensic relevance of establishing lethal doses for various NPS and highlights the analytical value of integrating NMR and LC-HRMS techniques for tablet identification to discriminate structural isomers and mislabeled NPS bags
Competing effects of charge-carrier and impurity scattering limiting phonon heat conduction in heavily-doped silicon
No full textWith respect to undoped semiconductors, thermal transport by phonons is limited by two additional mechanisms when doping increases: charge-carrier and impurity scattering. Previous works provided contradicting conclusions on the dominant doping-induced scattering mechanism in silicon. In this work, we clarify the competing roles of impurity and charge-carrier scatterings of phonons in the reduction of the lattice thermal conductivity in n-and p-doped silicon, by comparing experimental results obtained with the 3ω method and predictive DFT-based calculations for a large set of doping concentrations and a wide temperature range. The analysis allows delimiting the doping and temperature ranges where (i) extrinsic scattering surpasses intrinsic (phonon-phonon and phonon-isotope) one and (ii) one of the two doping-induced mechanisms plays the dominant role. We observe that the experimental setup impacts both the thermal conductivity value and the critical doping concentration at which the thermal conductivity is reduced by half
Efeitos do suavizamento do lençol freático controlado pela resolução da grade topográfica no fluxo regional simulado de água subterrânea
No full textInternational audienceThe assessment and management of groundwater often depend on large regional numerical models that predict hydrological stresses, such as those caused by climate change and resource exploitation. While regional and continental-scale models have been developed to evaluate these impacts, they typically use coarse grid cells that smooth land surface topography. This study investigates the impact of topography-controlled water table smoothing on simulated groundwater discharge to streams (baseflow) and associated groundwater age. A simplified 2D cross-sectional model of a topographically driven regional aquifer system was developed, under the assumption that the water table is a replica of the land surface topography. Scenarios with varying topography, derived from resampling digital elevation model (DEM) resolutions ranging from 30 to 10,000 m, were analyzed using a consistent, high-resolution numerical hydrogeological model mesh. Results show that baseflow rates decrease significantly as resolution declines, primarily due to reduced hydraulic gradients, with a flux dif- ference of an order of magnitude simulated between resolutions of 30 and 1000 m. Although shallow groundwater flows in more permeable aquifer layers are significantly affected, deeper regional flow remains stable across all scenarios. Regional groundwater flow paths and associated residence times are less sensitive to changes in resolution, particularly at depths greater than 50 m in the model used. The study thus demonstrates that low-resolution models need to overestimate hydraulic conductivity during calibration to accurately match fluxes to streams. This study highlights the critical importance of care- fully considering topographic resolution in regional models to ensure representative predictions of streamflow driven by subsurface–surface interactions
Use of mogamulizumab in cutaneous T-cell lymphomas among people living with HIV: insights from a nationwide French cohort
No full textInternational audienceWe report the first nationwide French cohort of people living with HIV (PLWH) treated with mogamulizumab for cutaneous T-cell lymphomas. Mogamulizumab demonstrated sustained efficacy and good tolerability, including in a patient treated continuously for over three years, with no opportunistic infections or HIV reactivation. Beyond clinical outcomes, our findings highlight the dual role of CCR4 in HIV persistence and immune regulation, warranting cardiovascular monitoring in this population
Self-employment, health, and health care: When the going gets tough, the tough get going?
No full textInternational audienceThis study provides a life-course analysis of the relationship between self-employment, health, and health care use among individuals aged 50 and older in Europe. Using data from the Survey of Health, Ageing, and Retirement in Europe (SHARE), we apply first-difference and dynamic panel data models that go beyond standard approaches in mitigating endogeneity concerns. Our findings show that the self-employed enjoy better health at younger ages, consistent with a selection effect. In addition, they experience a steeper decline in physical health over time. We also document two distinct phases of health care use: during working life, the self-employed are more likely to be hospitalised, suggesting delayed care until acute needs arise; after retirement, the number of medical visits increases, consistent with a lower opportunity cost of care
Surface energy engineering enables highly efficient antimony selenosulfide solar cells
No full textInternational audienceAntimony selenosulfide (Sb2(S,Se)3) is a competitive light-harvesting material, especially for solar cells. However, the interfacial nonradiative recombination and anisotropic carrier transport in the absorber impede the efficiency improvement. Herein, we propose a strategy for passivating interface defects and facilitating carrier transport by an effective surface energy engineering. In this regard, the surface energy of cadmium sulfide (CdS) electron transport layer (ETL) is selectively modulated via a dual-functional amorphous cadmium telluride oxide (CdTeO3) layer, causing more exposure of polar (002) facets with improved conductivity. Additionally, the amorphous CdTeO3 layer not only induces the desirable [211]-oriented Sb2(S,Se)3 with high-efficient carrier transport but also causes a benign band alignment with suppressed interface nonradiative recombination. As a result, the device delivers an efficiency of 10.31 %. This study suggests that modulating surface energy of CdS ETL with interfacial defect passivation and carrier transport amendment shines a new light on breaking the bottleneck in the development of Sb2(S,Se)3 solar cells
A structural and functional investigation of a thiosemicarbazone-derived ligand: Coordination behavior, heavy metal removal, and docking-based pharmacological insights
No full textInternational audienceThis study presents the design, synthesis, and detailed characterization of a novel thiosemicarbazone-based ligand, namely (2E)-2-[(4-hydroxy-3-methoxyphenyl)methylidene]hydrazine-1-carbothioamide (HMCT). The structural features of the ligand were elucidated using a combination of analytical techniques, including X-ray crystallography, infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR), and UV-Visible spectroscopy. The synthesized ligand was subsequently evaluated for its capacity to remove divalent heavy metal ions specifically copper (Cu2*), zinc (Zn2*), and nickel (Ni2*) from aqueous solutions. Remarkably, HMCT exhibited high removal efficiency, particularly for copper (Cu2*), reaching a maximum removal rate of 99.24 % within the first minutes of contact, even when applied to real wastewater samples. To further assess its pharmacological relevance, molecular docking simulations were conducted. These computational studies revealed significant binding affinities of HMCT toward three key biological targets: the main protease of SARS-CoV-2, Candida albicans, and Enterobacter aerogenes. The predicted interactions support the potential dual functionality of the HMCT ligand, indicating not only strong metal-chelating properties but also promising antimicrobial and antiviral capabilities. Overall, the findings highlight the versatile nature of HMCT, offering both environmental and biomedical applications