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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
Ambiguity-Aware Segmented Estimation of Mutual Coupling in Large RIS: Algorithm and Experimental Validation
No full textInternational audienceOptimizing a real-life RIS-parametrized wireless channel with a physics-consistent multiport-network model necessitates prior remote estimation of the mutual coupling (MC) between RIS elements. The number of MC parameters grows quadratically with the number of RIS elements, posing scalability challenges. Because of inevitable ambiguities, independently estimated segments of the MC matrix cannot be easily stitched together. Here, by carefully handling the ambiguities, we achieve a separation of the full estimation problem into three sequentially treated sets of smaller problems. We partition the RIS elements into groups. First, we estimate the MC for one group as well as the characteristics of the available loads. Second, we separately estimate the MC for each of the remaining groups, in each case with partial overlap with an already characterized group. Third, we separately estimate the MC between each distinct pair of groups. Full parallelization is feasible within the second and third sets of problems, and the third set of problems can furthermore benefit from efficient initialization. We experimentally validate our algorithm for a 4 × 4 MIMO channel parametrized by a 100-element RIS inside a rich-scattering environment. Our experimentally calibrated 5867-parameter multiport-network model achieves an accuracy of 40.5 dB, whereas benchmark models with limited or no MC awareness only reach 16.9 dB and 13.8 dB, respectively. Based on the experimentally calibrated models, we optimize the RIS for five wireless performance indicators. Experimental measurements with the optimized RIS configurations demonstrate only moderate benefits of MC awareness in RIS optimization in terms of the achieved performance. However, we observe that limited or no MC awareness markedly erodes the reliability of model-based predictions of the expected performance
Restricted Isometry for Variable-Density Continuous Frequency Sampling for Off-the-Grid Sparse Signals
No full textInternational audienceRestricted isometry-type guarantees for continuous random sampling of Fourier frequencies in off-the-grid sparse models observed through a known point-spread function (PSF) are established. Specifically, for spike trains convolved with a fixed kernel and sampled on a finite bandwidth according to an arbitrary probability density, it is proven that the empirical frequency-domain energy concentrates around its expectation with near-linear sample complexity in the sparsity level. The constants are governed by two simple summaries of the PSF and the sampling density: an in-band energy term and a bounded-variation penalty that captures the effect of spike separation. Our analysis yields a practical design principle for variable-density sampling and admits a convex discretization. Numerical experiments illustrate tangible gains in localization when the sampling density is optimized accordingly
Reclaiming Software Engineering as the Enabling Technology for the Digital Age
No full textInternational audienceSoftware engineering is the invisible infrastructure of the digital age. Every breakthrough in artificial intelligence, quantum computing, photonics, and cybersecurity relies on advances in software engineering, yet the field is too often treated as a supportive digital component rather than as a strategic, enabling discipline. In policy frameworks, including major European programmes, software appears primarily as a building block within other technologies, while the scientific discipline of software engineering remains largely absent. This position paper argues that the long-term sustainability, dependability, and sovereignty of digital technologies depend on investment in software engineering research. It is a call to reclaim the identity of software engineering
Controllability of wave-heat and heat-wave cascades
No full textWe study boundary controllability of one-dimensional coupled hyperbolic-parabolic cascades, focusing on the fine structure of reachable sets. The main model is a wave-heat cascade in which a boundary control acts on the wave equation and drives the heat equation through an internal coupling. We provide a sharp minimal time for the hyperbolic part (T > 2L) and a complete spectral characterization of exact controllability in weighted Hilbert spaces, whose definition depends explicitly on the coupling profile through a sequence of modal coefficients. In particular, internal couplings may generate nonstandard highly irregular controllability spaces and yield a generic (full measure) but non-robust controllability property. The analysis relies on Riesz basis decompositions and on an Ingham-Müntz inequality. We also prove that the exact controllability space is not invariant along Hilbert Uniqueness Method trajectories: even if both endpoints belong to the controllability space, the associated minimal-energy trajectory may leave it at intermediate times. Finally, we compare with the reversed (heat-wave) cascade and discuss how reversing the direction of the coupling transfers the loss of regularity between the parabolic and hyperbolic components
IA et IRM pour mieux comprendre le cerveau après un AVC - Retour d’expérience
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Frontiers of Combining Systems. 15th International Symposium, FroCoS 2025, Reykjavik, Iceland, September 29 – October 1, 2025, Proceedings
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Le langage simplifié pour le public FLE : des critères linguistiques à interroger
No full textInternational audienceLe langage simplifié est une variété de langue qui vise à rendre l'information plus compréhensible et, en fin de compte, plus accessible. Le contenu et la forme de cette variété peuvent être conçus conformément à un ensemble de recommandations publiées dans des guides d’écriture simplifiée. Toutefois, ces recommandations ne sont pas encore suffisamment étayées par des recherches empiriques ou expérimentales et les résultats ne sont pas encore généralisables (Gonzalez‑Sorde & Matamala, 2024). Dans cette perspective, ce chapitre s’intéresse au public dont le français n’est pas la langue première. Nous nous intéressons aux textes destinés aux personnes ayant un niveau de français compris entre A1 à B21, en les comparant avec des textes d’autres niveaux de complexité et technicité. Ainsi, notre objectif consiste à dégager les critères linguistiques adaptés aux besoins de ce public en comparant différents types, genres et sources de textes, en particulier des textes narratifs, informatifs et procéduraux
Validation methodology on real data of reversible Kalman Filter for state estimation with Manifold
No full textThis work extends a previous study that introduced an algorithm for state estimation on manifolds within the framework of the Kalman filter. Its objective is to address the limitations of the earlier approach. The reversible Kalman filter was designed to provide a methodology for evaluating the accuracy of existing Kalman filter variants with arbitrary precision on synthetic data. It has favorable numerical properties on synthetic data, achieving arbitrary precision without relying on the small-velocity assumption and depending only on sensor noise. However, its application to real data encountered difficulties related to measurement noise, which was mitigated using a heuristic. In particular, the heuristic involved an event detection step switching between reversible Kalman filter and classical Kalman variant at chosen moments. In the present work, we propose a study of this detection step and propose a methodology to prove at which moment the reversible Kalman approach improves on classical multiplicative variant