The Logic of Proof of Concept Research

International audienceProof of Concept Research (PoCR) is a prevalent facet of scientific inquiry, yet its epistemic features remain poorly understood. While novelty has been highlighted as a key characteristic, projectability—understood as the likelihood of being applicable to a broader range of contexts—is another. This study endeavours to construct a formal model that elucidates the implicit ampliative reasoning inherent in PoCR. Our model hinges on probability assumptions for target objects to simultaneously exhibit three properties: one that is a defining characteristic of these target objects; a second that is desired of them and whose demonstration is the empirical aim of PoCR; and a third that is promised in the background. Depending on assumptions about when these properties jointly obtain, we delineate paradigmatic, alternative, and tangential modes of reasoning. This classification and associated decision tree unveil distinct argumentative strategies that, despite not being deductively valid, may be employed to motivate PoCR and justify subsequent inferences upon successful proof of concept demonstration. The model and decision tree together provide a framework with which to better understand the general structure of widely used inferences in PoCR, and with which researchers and evaluators can more precisely design and assess PoCR projects

Prognosis of pediatric restrictive cardiomyopathy: more severe in sarcomeric variants

International audienceRestrictive cardiomyopathy (RCM) is the most severe type of cardiomyopathy in children with a very poor prognosis. RCM is often diagnosed between 6 and 10 years old and is predominantly of genetic origin. We conducted a retrospective study of 53 patients. The aim of our study was to determine whether outcomes are associated with the type of genetic variant. We compared the prognosis of patients with sarcomeric variants (n = 26) to those with non sarcomeric variants (n = 27). Our results showed no significant differences between the two groups at diagnosis in terms of heart failure symptoms, NT-proBNP levels, or hemodynamic parameters. However, survival without transplantation was significantly worse in the sarcomeric group (p = 0.003), which also exhibited greater disease severity. Furthermore, thrombotic events were more frequent in the sarcomeric group (p = 0.05). In conclusion, RCM caused by sarcomeric variants is associated with a poorer prognosis and a higher incidence of thrombotic events compared to non-sarcomeric RCM

Directed percolation transition to active turbulence driven by non-reciprocal forces

We numerically study the collective dynamics of dense particle assemblies driven by non-reciprocal pairwise forces of amplitude κ. At a critical value κc, the system undergoes a dynamical phase transition from an absorbing state (κ < κc) to a chaotic steady state (κ > κc). The chaotic phase is marked by nontrivial spatiotemporal velocity correlations and mixing, reminiscent of active turbulence in self-propelled systems. The sharp onset of chaos shows critical scaling consistent with the universality class of directed percolation. We argue that this transition is generic to a broad class of locally-driven, dense disordered materials.7 pages, 4 figure

QMCkl: A Kernel Library for Quantum Monte Carlo Applications

International audienceQuantum Monte Carlo (QMC) methods deliver highly accurate electronic structure calculations but are computationally intensive. The quantum Monte Carlo kernel library (QMCkl) provides a modular, portable collection of high-performance kernels implementing the core building blocks of QMC calculations. It offers a C-compatible API, supports the TREXIO standard for input, and covers essential QMC kernels including atomic and molecular orbitals, cusp corrections, Jastrow factor, and the necessary derivatives also to perform variational and structural optimization. QMCkl separates algorithmic development from hardware-specific tuning by combining human-readable reference implementations with performance-optimized kernels that produce identical numerical results. The library enables consistent, efficient, and reproducible simulations across different QMC codes and architectures, and achieves substantial speedups in the evaluation of the energy and its derivatives. Beyond QMC, QMCkl can accelerate deterministic quantum chemistry workflows and visualization tools, promoting cross-code interoperability and simplifying high-performance scientific software development

Targeting the cell membrane in established and emerging model organisms

International audienceTransgenic markers and tools have revolutionised how we study cells and developing organisms. Some elements needed to construct those tools are universally applicable (e.g. fluorescent proteins), while others are species specific (e.g. cis-regulatory elements driving transcription). Membrane-localising signals that target proteins to the plasma membrane have been identified in some organisms, but their efficacy varies across species. To address this problem, we generated a toolkit of 11 membrane-localising tags that can be screened rapidly in diverse organisms. The toolkit includes tags targeting the plasma membrane through different mechanisms, including signal peptides, lipid attachments or fusion with lipid-binding domains. Each tag was fused to the fluorescent protein mScarlet3 and placed downstream of a T7 promoter, to produce mRNA that can be delivered in a wide range of embryos and cells. Through a collaborative effort, we tested this toolkit in ten animals spanning diverse phyla, including chordates, echinoderms, arthropods, nematodes, annelids, flatworms and cnidarians. We identify robust membrane-localising tags in each of these animals, and in the animals’ closest relatives, the choanoflagellates. Three tags (KRas, GAP43 and Src64B) work in all the species we tested

Flying shape and aerodynamics of a full-scale flexible Olympic windsurf sail

International audienceThe introduction of hydrofoils in windsurfing has fundamentally changed the aerodynamic loads on modern rigs. While past studies including recent ones in windsurfing or sailing aerodynamics have relied on reduced-scale rigid sail models and numerical simulations, there is a lack of experimental data on the full-scale flying shape of deformable sails. In particular, iQFOil class - new Olympic windsurf class - still lacks of direct measurements to potentially validate Fluid Structure Interaction model, in order to improve the accuracy of Velocity Program Prediction. The 3D flying shape of a real-scale 8 m$^2$ iQFOiL class windsurf sail is measured in steady state sailing configurations. The outdoor conditions are simulated in a large-scale wind tunnel and the flying shape is reconstructed with a stereo camera imaging technique. Together with the sail shape, we measure simultaneously the aerodynamic forces and moments applied to the sail. With the measured forces and moments, the lift, drag and roll coefficients are determined for wind velocities ranging from 4 to 8 m/s. A systematic decrease of these coefficients is observed as compared to previous studies on reduced-scale rigid sail model, because of the rigging deformation due to wind loading. We thus establish experimentally benchmark data for the iQFOiL sail and more generally for compliant rigging

Dimensionality Control in Superlattices from Copper Sulfide Nanocrystals

International audienceThree-dimensional nanocrystal superlattices have garnered considerable research interest due to their remarkable collective properties and promising applications. The control of the dimensionality of superlattices remains a significant challenge, with no established synthetic protocol to tune the shape of superlattices. The present article manifests a straightforward and efficient single-step chemical synthesis route for modulating the dimensionality of Cu1.8S nanocrystals superlattices. The resulting superlattices exhibit distinct stability within several solvents (hexane, toluene and benzene) over an extended period of several months. Furthermore, we unveil the growth mechanism of these superlattices through comprehensive small-angle X-ray scattering (SAXS) experiments. This method addresses several drawbacks (multi step synthesis, structural fragility, reproducibility, long-range order instability, etc) associated with previously reported self-assembly methods, the superlattices generated by this technique are efficient to fabricate devices in the future.</div

Lipid droplet-based passive tracking to probe tissue dynamics in lymph node slices

International audienceThis protocol describes a method to measure the microrheological properties of lymph node tissue. Lymph nodes, the primary organs of adaptive immune responses, remodel across multiple spatio temporal scales: at the cellular (and minute) scale through immune cell motility, such as that of B and T lymphocytes and dendritic cells, and at the organ (and day) scale through cell proliferation and restructuring of the fibroblastic stromal network.By tracking exogenous lipid droplets (used as passive tracers) in live lymph node slice explants, across different regions and conditions, we infer local tissue activity, immune cell motility, and the functional state of the organ. This approach offers a powerful tool for probing lymph node biomechanics at the scale of individual cells and provides a framework for studying the interplay between tissue mechanics and immune function

Elasto-Goutte Minces Modulables

We present an experimental method to fabricate centimetric thin elastic capsules with highly uniform thickness and negligible bending stiffness using silicone elastomers. In our experiments, the capsules thickness is tunable at fabrication, while internal pressure and hoop (circumferential) stress are adjustable via hydrostatic inflation once the capsules are filled and immersed in water. Capsules mechanics are probed through hydro-elastic waves generated by weak mechanical perturbations at the capsule interface. By analyzing the surface wave dynamics in the Fourier domain, we extract the in-plane stress and demonstrate that the hydro-elastic waves are exclusively governed by hoop stress. This \reponse{provides a controllable macroscopic analogue of liquid drops} characterised by an effective surface tension, allowing the capsules to be modeled as large-scale ``elasto-drops'' with an inflation and thickness tunable effective surface tension. \reponse{In this limit, bending stiffness is negligible over the experimentally relevant wavelengths, so that the shell dynamics are governed primarily by in-plane tension.} Our work demonstrates that elasto-drops serve as a robust model system for parametric studies of large-scale \reponse{analogues of} liquid drops with experimentally adjustable surface tension

Supplementary Material – Video 2 accompanying the article “Cymbal Playing in Late Antiquity: Resonances between Romano-Byzantine and Late Sasanian Iconographies,” published in Greek and Roman Musical Studies (BRILL, 2026). Dancer: Laetitia Cuellar

In the Sasanian period of Persia, the fascination of the upper classes with Romano- Byzantine iconography led to the production of luxury silver vessels featuring a western-inspired Bacchic-style iconography. This study demonstrates that these objects constitute valuable sources for archaeomusicology. The case of cymbal playing techniques is examined through a comparative iconographic approach. Sasanian silverware depicts numerous cymbal playing techniques also visible in Romano-Byzantine art. Sasanian representations of hand cymbals and frontal cymbal tongs are consistent with the abundant western iconography and preserved ancient instrument specimens. This confirms the value of Sasanian silverware in the study of late antique cymbal playing techniques. Additionally, Sasanian silverware provides testimony regarding lateral cymbal tongs and ankle cymbals, which are poorly documented in Romano-Byzantine sources. An experimental reconstruction confirms that the postures of ankle cymbals players in Romano-Byzantine and Sasanian imageries are compatible with effective cymbal striking, thereby supporting the plausibility that this playing technique existed in Late Antiquity