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Weak protein–bicelle binding quantification via surface-based DNA nanolevers
No full textInternational audienceTo investigate how human dystrophin associates with biomimetic phospholipid bicelles, we applied switchSENSE®, a fluorescence-based biosensing technology that employs dynamic DNA nanolevers in a microfluidic environment with minimal material requirements. We show that switchSENSE® enables real-time kinetic analysis of weak and transient interactions, offering a clear advantage over classical biophysical methods that often fail to capture low-affinity protein-lipid binding. Focusing on two functionally relevant central-domain dystrophin fragments (R1-3 and R11-15), we quantified binding to zwitterionic and anionic bicelles using two complementary assay orientations: proteins immobilized with bicelles as analytes, and the reverse. Both yielded consistent micromolar affinities, in line with prior microscale thermophoresis results, but uniquely provided kinetic rate constants. This represents the first kinetic characterization of dystrophin-bicelle interactions, revealing that weak affinity is largely driven by rapid dissociation. Notably, R11-15 exhibited faster association and slower dissociation than R1-3, indicating a more stable and sustained lipid interaction. Beyond advancing mechanistic insight into dystrophin’s reversible membrane association – a process thought to stabilize sarcolemmal integrity during muscle contraction and elongation -, our study highlights switchSENSE® as a versatile platform for quantifying weak protein-lipid interactions. By enabling kinetic resolution of interactions at the edge of conventional detection limits, switchSENSE® provides a powerful tool for dissecting the dynamic interplay between structural proteins and lipid assemblies
Magnetostaltic pumping in an ex vivo extracorporeal membrane oxygenation model
No full textInternational audienceBackground Extracorporeal membrane oxygenation (ECMO) is a critical rescue therapy for severe respiratory or cardiac failure. However, current blood pumps generate high shear stresses that can damage blood components, leading to hemolysis, loss of von Willebrand factor multimers, and increased risks of bleeding, thrombosis, and organ injury. MethodsWe developed novel magnetostaltic pumps that use magnetic liquid interfaces instead of solid walls to transport blood, aiming to reduce mechanical stress on blood cells. Four magnetostaltic pump designs were tested in ex vivo ECMO circuits using human donor blood at clinically relevant flow rates and compared with standard centrifugal and peristaltic pumps.Results Across all flow rates, magnetostaltic pumps produced less hemolysis than conventional pumps. Under pediatric flow conditions (1 L/min for 48 h), the large-scale magnetostaltic pump (QR3) reduced hemolysis by approximately one-third compared with commercial centrifugal pumps and preserved high-molecular-weight von Willebrand factor multimers. Platelet function was unaffected. Small amounts of nanoparticle leakage from the magnetic fluid were detected but remained well below toxic thresholds.Conclusions Magnetostaltic pumping offers a promising alternative to current ECMO pumps by reducing blood damage. These results support further testing in animal models to evaluate the potential for clinical translation.</div
Unweighted Hardy Inequalities on the Heisenberg Group and in Step-Two Carnot Groups
No full textWe establish unweighted Hardy-type inequalities on step-two Carnot groups with one-dimensional vertical layer, with explicit lower bounds for the optimal Hardy constant. The approach is based on a quantitative integration-by-parts mechanism that replaces the non-horizontal Euler vector field by a suitably constructed horizontal vector field with controlled norm. As applications, we obtain fully explicit bounds in the Heisenberg group for both the Korànyi gauge and the Carnot--Carathéodory distance, and we extend the results to non-isotropic step-two structures through a generalized Korànyi-type homogeneous norm
Discretizing the Fokker-Planck equation with second-order accuracy: a dissipation driven approach
No full textInternational audienceWe propose a fully discrete finite volume scheme for the standard Fokker-Planck equation. The space discretization relies on the well-known square-root approximation, which falls into the framework of two-point flux approximations. Our time discretization is novel and relies on a tailored nonlinear mid-point rule, designed to accurately capture the dissipative structure of the model. We establish well-posedness for the scheme, positivity of the solutions, as well as a fully discrete energy-dissipation inequality mimicking the continuous one. We then prove the rigorous convergence of the scheme under mildly restrictive conditions on the unstructured grids, which can be easily satisfied in practice. Numerical simulations show that our scheme is second order accurate both in time and space, and that one can solve the discrete nonlinear systems arising at each time step using Newton's method with low computational cost
Substantial contribution of trees outside forests to above-ground carbon across China
No full textInternational audienceAccurately quantifying canopy height and above-ground carbon across diverse land-cover types is crucial for understanding carbon storage dynamics and guiding climate-mitigation strategies. Yet existing maps often overlook non-forest ecosystems. Here we present a deep learning framework based on a U-Net architecture that combines radar, optical, elevation and slope data to produce a 10 m canopy height map across China. The model is trained with laser measurements from NASA's GEDI mission validated using unmanned aerial vehicle lidar data ( MAE = 2.39 m ). We then estimate the above-ground biomass and carbon from these heights using a Random Forest model ( MAE = 37.71 Mg ha-1 ). By deriving carbon from canopy height, we take advantage of U-Net's ability to capture trees in non-forest ecosystems such as croplands, grasslands and urban areas. Our nationwide 30 m carbon map reveals that trees outside forests contribute 20.8-32.9% of China's above-ground carbon in 2019 (3.62-5.72 Pg C), underscoring their importance
RÔLE DES ARTEFACTS SYMBOLIQUES DANS L’INNOVATION À L’HÔPITAL :LES ENSEIGNEMENTS DE TROIS CAS
No full textInternational audienceHospitals seek to respond to the multiple tensions they face through organizational innovation. This article examines the practical modalities of such innovation and explores an aspect often overlooked in the literature: the role of symbolic artifacts. This research is based on a multiple, quasi-ethnographic casestudy of three hospitals in France and Brazil. While acknowledging the specificities of each case, the analysis reveals significant convergences. The findings highlight that symbolic artifacts serve as communicative agents through their use. Thus, they play a pivotal role in the innovation processLes hôpitaux tentent de répondre aux nombreuses tensions auxquelles ils sont confrontés par de l’innovation organisationnelle. Le présent article s’intéresse à ses modalités pratiques et à un aspect souvent négligé dans la littérature, le rôle des artefacts symboliques. Il s’appuie pour cela sur l’étude de cas multiple quasi ethnographique de trois établissements hospitaliers, situés en France et au Brésil. Au-delà des singularités propres à ces cas, leur analyse révèle de fortes convergences. Elle montre que ces artefacts symboliques sont communicationnels par l’usage qui en est fait et qu’ils jouent ainsi un rôle clé dans le processus d’innovation
Quasiparticle interference and spectral function of the UTe2 superconductive surface band
No full textInternational audienc
What is the carbon footprint of a 100% digital pathology scenario in France?
No full textInternational audienceHealthcare systems contribute to 5-10% of annual greenhouse gas (GHG) emissions and must reduce them to meet the 2016 Paris Agreement targets. Workflows in many areas of medicine are digitised, including surgical pathology. This is the case in France, the second most populous country in the European Union (68 million inhabitants/ 0•8% of world population) with an energy supply that is primarily sourced from nuclear power. We aimed to evaluate the carbon footprint (CF) in a theoretical scenario where all French surgical pathology laboratories implement full digitisation. Data on annual surgical pathology activities were obtained from the French National College of Pathologists. We defined the steps required by histological slide digitisation (scanning, image management software (IMS), data workflow, desktop tools, and storage) and inventoried the tools and their CF using a specific database and bibliography. This study was extrapolated to a national digitisation scenario without artificial intelligence (AI). Digitisation of a single French laboratory was also compared to the same laboratory, nondigitised. In 2021, 28,932,624 slides were generated, corresponding to more than 43PB (1•5 GB per whole-slide image (WSI)) shared by 250 surgical pathology laboratories using 500 scanners (i.e., two per laboratory working 12 hours per day). Digitising pathology resulted in 1,103 to 1,259 tons of carbon dioxide equivalent (CO2eq) for three months compared to 2,116 to 2,923 t CO2eq for one year of digital storage. This is equivalent to the GHG emissions of a combustion-powered car travelling around the Earth 145 times and 336 times, respectively. Data storage was the main contributor to the CF, regardless of storage type and duration (local or external for three months or one year). The other contributors included in decreasing order were desktop tools, scanners, and IMS. Finally, for one French surgical pathology laboratory, the CF of full digitisation increased by 4% to 8% (three months to one year of digital storage) compared to the current non-digitised CF. Such additional impact was equivalent to adding 13 to 26 minus 80-degree freezers in the laboratory. Full digitisation of surgical pathology has a significant environmental impact on global warming, even without the use of AI. Reducing storage duration and increasing the lifespan of digital equipment are the main strategies to mitigate these impacts
Optimizing fertilizer use for sustainable crops with Agrivoltaics in Mediterranean climates
No full textInternational audienceAgrivoltaics (AV), a fast-growing technology integrating photovoltaic panels with agriculture, can offer the dual benefit of clean energy and crop yield gains, especially in the Mediterranean basin. However, its interaction with fertilizers -key for crops productivity but major contributors to environmental degradation- remains unexplored. This study applies a regional AV model over the Iberian Peninsula (1991–2020) using the ORCHIDEE land surface model to assess AV under varying synthetic fertilizers scenarios. We examine its effects on crop productivity, nitrogen and water use efficiency, and fertilizer-induced greenhouse gas emissions. Results show that AV can enhance productivity and reduce environmental costs, particularly in water-scarce conditions. However, trade-offs arise at critical fertilizer levels varying by crop type and climate. A region-specific strategy that considers climate, crop responses, and environmental impacts is essential to optimize AV sustainability potential