Portail HAL UPEC
Not a member yet
55480 research outputs found
Sort by
Understanding the role of turbulence and biofilm on low density microplastic dynamics: An experimental approach towards natural conditions
No full textInternational audienc
Normal approximation for partial sums: general convex costs
No full textWe provide non-asymptotic bounds and asymptotic limits for convex transport costs between the distribution of partial sums of independent and identically distributed square integrable and centered random variables and the normal distribution with mean zero and the same variance. The proof relies on controlling the transport cost by an appropriate ideal distance, combined with an adaptation of Lindeberg's method. The numerical constants and the asymptotic constants are explicit
Impact of RNAi therapeutics on cardiac parameters in patients with hereditary transthyretin amyloidosis initially treated with stabilizers: A French real-world study
No full textInternational audienceBackground: Cardiomyopathy in hereditary transthyretin amyloidosis (ATTRv) is increasingly reported due to improved diagnostic techniques and increased clinician awareness. Optimal therapeutic strategies for mixed phenotypes remain challenging.Aims: To describe the changes in cardiac parameters among patients with ATTRv and cardiac involvement who had switched from stabilizer monotherapy to ribonucleic acid interference (RNAi) therapeutics or added RNAi to stabilizer monotherapy (switching/adding RNAi).Methods: Data from patients with ATTRv and confirmed cardiomyopathy who had started tafamidis monotherapy between 2010 and 2022 and switched to/added RNAi therapeutics (patisiran or vutrisiran) between 2018 and 2023 were retrospectively collected from October 2023 to May 2024. Functional, laboratory and imaging parameters were collected, and progression assessed according to the 2021 expert consensus on transthyretin amyloidosis with cardiomyopathy monitoring.Results: Fifty patients (median [interquartile range] age 63 [58-70] years; 66% male) from 10 French centres were included. Mean±standard deviation follow-up durations on treatment were 3.8±2.7 years for tafamidis monotherapy and 2.5±1.9 years for RNAi (±tafamidis). Switching/adding RNAi was mainly for neurological progression (n=40; 80%). Under tafamidis monotherapy, 24% of patients worsened with simultaneous declines in clinical, laboratory and imaging parameters, while 76% were stable. After switching/adding RNAi, 90% of patients were stable, none worsened and 10% improved.Conclusion: This real-world French study is the first switch/add-on study in mixed phenotypes of ATTRv. It highlights the potential benefits of early switching/adding of RNAi in patients with insufficient cardiac response under tafamidis
Neural network hyperreduction for parameterized computational models in nonlinear stochastic dynamics
No full textInternational audienceHighly efficient hyperreduction methods have been proposed to reduce the computational cost of parameterized high-dimensional models in nonlinear dynamics. Unlike hyperreduced models, the parameterized reduced-order models still scale with the dimension of the high-dimensional model for the computation of the projected nonlinear forces. As an alternative to traditional hyperreduction methods, this work presents a neural-network-based hyperreduction strategy. It is embedded within the framework of parameterized reduced-order models in nonlinear stochastic dynamics. The proposed approach achieves hyperreduction by entirely removing such a dependence on the high-dimensional model dimension. In particular, the costly computation and projection of nonlinear forces in the high-dimensional physical space is bypassed: the neural network directly outputs the reduced forces from the reduced displacements and system parameters. It is trained on data collected during the offline stage required for constructing the parameterized reduced-order model. The resulting hyperreduced model enables substantial computational savings, particularly suited for large-scale Monte Carlo simulations in the stochastic dynamics framework. Numerical results show that the method provides highly accurate approximations of the nonlinear response and its statistics, with a performance gain of two orders of magnitude with respect to the parameterized reduced-order model
Symposium : les séries télé à l’université : temps d’évasion, lieu de contrainte ou nouvel espace d’apprentissage
No full textInternational audienc
Did the 2019 Notre-Dame Cathedral Fire impact the lead contamination of sediment in the Seine River in Paris, France?
No full textInternational audienceThe fire that affected Notre-Dame Cathedral in Paris in 2019 has reignited concerns about metal contamination including lead (Pb) in the city. The current research investigated the potential contribution of this event to the contamination of sediment transiting the Seine River. To this end, sediment deposits were collected in Paris just after floods in 2016 (i.e. before the fire), as well as in 2020 and 2021 (i.e. after the fire). They were analysed for fallout radionuclides, organic matter, metal concentrations and Pb isotopic ratios. Results showed that the material deposited by the flood exhibited contrasted characteristics and contamination levels depending on the flood. The major flood event that took place in June 2016 mainly consisted of surface recent material from the upper reaches of the river. This likely explains the large homogeneity of sediment across Paris and the relatively low metal contamination. Then, the occurrence of a lower magnitude flood event in 2020 led to the deposition of a large majority of older subsurface material, likely resuspended from the channel or eroded from the banks. This material showed higher contamination levels than in 2016. Pb levels were particularly significantly higher around Notre-Dame Cathedral. Some samples displayed Pb isotopic signatures that may coincide with those of dust from the Notre-Dame Fire ( 206 Pb/ 207 Pb: 1.1669-1.1685). Finally, in 2021, another winter flood depositing a majority of subsurface material occurred. Overall, the metal contamination levels measured in the material deposited in 2021 were lower than in 2020, except for the sample collected near the Eiffel Tower. These results demonstrate the negligible impact of the Notre-Dame fire on the Pb contamination. In the future, sediment should continue to be monitored to avoid any potential mistrust from the general public, as three bathing sites have been reopened to the public in summer 2025
Quand la pratique du formateur rencontre l’invention mathématique. Trois démarches pour une racine...
No full textInternational audienceThis article examines how three mathematics education researchers and teacher educators elucidate an algorithm for computing square roots. Drawing on Hadamard’s (1945) model of the phases of mathematical invention (preparation, incubation, illumination, validation) and on the concept of practical epistemology (Sensevy, 2007), the study highlights the diversity of frameworks mobilized to tackle a non-routine task. The analysis reveals both generic features and specificities closely tied to each participant’s professional trajectory and training practices. The article concludes by discussing the relevance, for initial and continuing teacher education, of acknowledging and working with this plurality of ways of “doing mathematics.”Cet article rend compte de la manière dont trois formatrices-chercheuses en didactique des mathématiques élucident un algorithme de calcul de la racine carrée. En articulant le modèle des phases de l’invention mathématique (préparation, incubation, illumination, vérification-finition) selon Hadamard (1945/1975) et le concept d’épistémologie pratique (Sensevy, 2007), la recherche met en lumière la diversité des cadres mobilisés pour traiter une tâche non routinière. L’analyse met en évidence des généricités mais aussi des spécificités étroitement liées à leurs parcours et pratiques de formation. L’article discute enfin de l’intérêt, pour la formation initiale et continue, de reconnaitre et de travailler cette pluralité de manières de « faire des mathématiques »
Additive Manufacturing of real-scale carotid artery models: The content–container interaction in sickle cell disease-related cerebral vasculopathy
No full textAbstract Sickle cell disease–related cerebral vasculopathy depends on patient-specific vascular geometry and hemodynamics that are not captured by conventional experimental systems or animal models. To address this limitation, we developed an additively manufactured artery scaffold representing the container and integrated it into a controlled fluidic circuit reproducing physiological flow profiles, pressures, and viscosities, the content. Validation with clinical imaging confirmed the anatomical accuracy and flow fidelity of the additively manufactured models. Mechanosensitive cells, including endothelial cells and platelets, were incorporated into the model for biological analysis. This study serves as a proof of concept demonstrating how the Container–Content model can enhance the mechanistic understanding of vascular biology under physiologically relevant conditions. The ethically responsible platform bridges computational simulations and in vitro experimentation, offering a versatile foundation for investigating cerebrovascular complications in sickle cell disease and advancing the field of personalized medicine
Serum procalcitonin: A novel tumor biomarker for diagnosis and disease monitoring in fibrolamellar hepatocellular carcinoma
No full textInternational audienceIntroductionFibrolamellar carcinoma (FLC) is a rare primary liver cancer that predominantly affects young patients with normal known serum tumor biomarkers. An observation of an elevated procalcitonin (PCT) in one patient prompted us to investigate PCT as a biomarker in a larger cohort of FLC.MethodsWe measured serum PCT levels in 34 samples from 18 patients with FLC and in 64 patients with hepatocellular carcinoma (HCC), 24 with cholangiocarcinoma (CCA), and 20 with cirrhosis. Using RNA sequencing, we analyzed CALCA expression, encoding PCT, in 27 FLC tumors, 331 HCC tumors, 39 CCA tumors, 71 hepatoblastomas, 34 hepatocellular adenomas, and 55 non-tumor livers. Spatial transcriptomics was performed on three FLC and PCT immunohistochemistry on 13 FLC and 34 other primary or secondary liver cancers.ResultsIn 8 FLC from the European cohort, median serum PCT was significantly elevated (55.2 μg/l) compared to patients with HCC (0.14 μg/l), CCA (0.16 μg/l), and cirrhosis (0.11 μg/l; P=0.0005). It was validated in a U.S. cohort of 10 FLC patients compared to HCC and CCA (P=0.0002). Across these cohorts, elevated serum PCT was observed in 83% of FLC cases versus 3% of HCC and CCA (P<0.0001). In four patients, changes in serum PCT levels correlated with radiologic response according to RECIST 1.1. RNA sequencing demonstrated significant overexpression of CALCA in FLC compared to other primary liver tumors (P<0.0001), and spatial transcriptomics localized CALCA expression specifically to tumor cells. Immunohistochemistry confirmed PCT overexpression in 77% of FLC but not in other liver cancers.ConclusionProcalcitonin is a sensitive and specific serum biomarker for FLC among primary liver cancers, with potential utility in diagnosis and monitoring of treatment response.Impact and implicationsThis study is justified by the lack of reliable serum biomarkers for fibrolamellar carcinoma and demonstrates that procalcitonin is specifically overexpressed by FLC tumor cells and detectable in the blood of the patients with FLC. These findings are important for clinicians and researchers, as they identify a readily available biomarker that may facilitate diagnosis, improve disease monitoring, and support clinical trial design in a rare cancer that predominantly affects young patients. In clinical practice, serum PCT measurement could be incorporated as a non-invasive adjunct to imaging for the diagnosis and longitudinal assessment of FLC, although prospective studies in larger and more diverse cohorts are needed to refine diagnostic cut-offs and confirm specificity