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L'usage des données empiriques dans le cadre de la recherche en matière de réparation du dommage corporel
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Combining N-coordinated copper single atoms and copper clusters for CO2 electrochemical reduction
No full textInternational audienceThe shift toward a clean and sustainable energy landscape is essential for advancing beyond fossil fuel dependency. Among various approaches, the electrocatalytic reduction of CO₂, when integrated with renewable energy sources, represents one of the most effective pathways for producing clean fuels and high-value chemicals, including hydrocarbons and alcohols. Copper remains the only metal-based electrocatalyst capable of converting CO₂ into C1 and C2+ products, such as hydrocarbons, methane, ethylene, and ethanol at decent selectivity and productivity. However, this metal exhibits limited selectivity for a single product, and is prone to electrode deactivation, primarily due to carbonaceous deposits formed by reaction intermediates [1], and morphological alterations arising from its inherent dynamic behavior of dissolution and restructuration. Considering that Cu2+ species suffers partial in-situ reduction to metallic copper clusters at low potentials [2], one can intentionally explore the CO2 reduction on N-coordinated copper Cu2+ and Cu0 species in substrates that primarily retain Cu ions and metallic copper clusters within their structure [3]. The hypothesis raised in this work is based on the principle that a material labeled Cu-N-C such as single copper atoms embedded in a highly rich nitrogen doped carbon matrix, demonstrates the ability to anchor copper ions and clusters, simultaneously, thus performing a Tandem electrocatalysis process of the CO2 electrochemical reduction Herein, by combining the techniques of Transmission Electron Microscopy (TEM), On-line Differential Electrochemical Mass Spectrometry (DEMS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) coupled to electrochemical flow cell, we show that the selectivity of CO2 electrochemical reduction depends on the stability of the N-coordinated Cu ions (single-atoms) and Cu clusters formed during the cathodic regime. Furthermore, by using a Rotating Ring-Disk Electrode (RRDE) with IrOx electrodeposited on the ring as a local pH probe, it was demonstrated that the cooper dissolution is function of the interfacial pH changing due to protons consumption from the electrolyte by both CO2 reduction and the competitive Hydrogen Evolution Reaction (HER). This was ascribed to the formation of CuOxHy species, which are soluble in the electrolyte, as evidenced by the nature of the high alkaline metal species on the electrode surface post-electrolysis evidenced by means of the X-ray Photoelectron Spectroscopy (XPS). Quantitative Gas Chromatography (GC) analysis further demonstrated the stability of the Cu-N-C catalyst for CO formation at -1.0 V vs. RHE, achieving a high Faradaic efficiency of 80%
Beyond the surface: Investigating hydrogen absorption and strain in palladium nanoparticles with BCDI
No full textInternational audiencePalladium hydrides (PdHx) are a model system for studying phase transitions and hydrogen (H) absorption in materials. Well-studied in the gas phase, they are also relevant in electrochemistry, particularly electrocatalysis, where the H:Pd ratio can be controlled though electrochemical potential. PdHx hydrides exhibit a slightly expanded lattice at low H content (x < 0.05), known as the α-phase, which transforms into a lattice-expanded β-phase at higher H content. While wide-angle X-ray scattering can be used to monitor the in situ absorption of H into commercial Pd nanoparticles (NPs) 3.6 nm in size [1] as well as related phenomena such as H trapping, crucial aspects of the mechanism and kinetics of PdHx formation remain elusive. Specifically, it is unclear whether the α- and β-phases coexist, and if the Pd NPs undergo isotropic H insertion, following a core-shell model, or if preferential H absorption pathways exist, as suggested by a spherical cap model. Furthermore, the small size of the facets makes it difficult to determine the distribution of strain fields across different facets, as well as at the edges and corners of the NPs.In this study, employing Bragg Coherent X-ray Diffraction Imaging (BCDI) and focusing on the 111 Bragg reflection, we obtained information on the morphology, projected strain, displacement fields, and d-spacing of single 300 nm Pd NPs at various electrode potentials relevant to H adsorption, H absorption, and H2 evolution [2]. We examined changes in lattice constants for both α and β phases and reconstructed the Pd NPs in each individual phase. The reconstructions revealed a continuous increase in the Pd lattice parameter, indicating an isotropic dilatation/expansion of the NP. Additionally, we observed heterogeneous strain in the reconstructed Pd NPs, with tensile strain accumulating on the {111} and {100} facets, while the lattice in the edges and corners of the atoms appeared compressed. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement HERMES No 952184 and grant agreement CARINE No. 818823
Transcription of the workshop Speech Production Models and Empirical Evidence from Typical and Pathological Speech
No full textThis unpublished document can be cited as: Fougeron C., Goldstein L., Guenther F., Lœvenbruck H., Mefferd A., Mücke D., Niziolek C., Parrel B., Perrier P., Ziegler W., Laganaro M. (unpublished manuscript) Transcription of the workshop Speech Production Models and Empirical Evidence from Typical and Pathological Speech. 13 May 2024, Grenoble, France. doi: 10.26037/yareta:cvlb5qujzzc3ti3pgxq62y76ui.This manuscript is an edited version of the fruitful discussions which took place during the workshop “Speech production models and empirical evidence from typical and pathological speech”, organized in the context of the ChaSpeePro project (financed by the Swiss National Science Foundation) on May 13th, 2024 in Grenoble (France). Discussions are organized in four round-tables, each preceded by a summary: (1) Speech production processes and units, with Pascal Perrier (moderator), Louis Goldstein, Frank Guenther, Ben Parrell, Caroline Niziolek ; (2) Neurotypical versus impaired speech, with Doris Mücke (moderator), Louis Goldstein, Frank Guenther, Antje Mefferd, Caroline Niziolek, Pascal Perrier, Wolfram Ziegler ; (3) Short-term adaptations and speech modes/styles, with Hélène Lœvenbruck (moderator), Frank Guenther, Doris Mücke, Ben Parrell, Pascal Perrier ; (4) Learning, changing, adapting speech, with Wolfram Ziegler (moderator), Louis Goldstein, Frank Guenther, Hélène Lœvenbruck, Pascal Perrier. This unpublished document can be cited as: Fougeron C., Goldstein L., Guenther F., Lœvenbruck H., Mefferd A., Mücke D., Niziolek C., Parrel B., Perrier P., Ziegler W., Laganaro M. (unpublished manuscript) Transcription of the workshop Speech Production Models and Empirical Evidence from Typical and Pathological Speech. 13 May 2024, Grenoble, France. doi: 10.26037/yareta:cvlb5qujzzc3ti3pgxq62y76ui
The Algebraic Cost of a Boolean Sum
No full textIt is a well-known fact that the permanent polynomial is complete for the complexity class VNP, and it is largely suspected that the determinant does not share this property, despite its similar expression. We study the question of why the VNP-completeness proof of the permanent fails for the determinant. We isolate three fundamental properties that are sufficient to prove a polynomial sequence is VNP-hard, of which two are shared by both the permanent and the determinant. We proceed to show that the permanent satisfies the third property, which we refer to as the "cost of a boolean sum," while the determinant does not, showcasing the fundamental difference between the polynomial families. We further note that this differentiation also applies in the border complexity setting and that our results apply for counting complexity
Inverse Stefan problem from indirect measurements, application to zircon crystallization
No full textInternational audienceThe growth of zircon crystals in cooling magmas is modelled by the one-phase Stefan problem, with the growth rate that depends on the magma cooling rate. Some rare elements (like e.g. U, Th, Hf) are incorporated in the crystal at trace concentration. These elements have different temperature-dependent diffusion and partition coefficients. As a consequence their final spatial repartition in the crystal depends on the temperature evolution of the magma during the cooling. The present work proposes to reconstruct the temperature evolution from the measurements of trace elements concentration in natural zircon. This inverse problem is solved by minimizing the misfit between calculated and measured trace element concentrations. The tangent model to the one-phase Stefan problem provides the sensitivity matrix, and the quadratic cost-function is minimized using Gauss–Newton method. The identifiability and the error on the retrieved parameters are studied in the framework of BLUE (Best Linear Unbiased Linear Estimator). The algorithm is tested on two synthetic datasets, and on real data obtained in a zircon crystal from early Fish Canyon tuff eruption. Reconstructed temperature ranges and cooling duration are in good agreement with available petrological interpretation
An integrated multi-instrument methodology for studying marginal ice zone dynamics and wave-ice interactions
No full textWave-driven fragmentation is the key mechanism shaping the Marginal Ice Zone (MIZ). Capturing this process is therefore essential for improving sea ice models, which currently do not fully capture the complex interactions between the forcing imposed by waves and the nonlinear dynamics of the resulting sea ice breakup and deformation. To investigate these interactions, we introduce a comprehensive multi-instrument dataset from a field campaign in the MIZ of the St. Lawrence Estuary, Canada, designed to characterize wave propagation and mechanical properties of sea ice under natural forcing conditions. The dataset integrates synchronized measurements from geophone arrays, wave buoys, smartphones configured as motion sensors, and unmanned aerial vehicles (UAVs), all collected during coordinated deployments across diverse ice types and sea states. Seismic data, recorded with geophone arrays, enable estimation of the ice thickness and elastic properties via active and passive wavefield analyses. Concurrently, wave buoys and smartphones capture ocean wave characteristics including amplitude, wavelength, and attenuation near ice edges. UAV imagery is processed with advanced methods to detect vertical ice displacements with sub-centimetre sensitivity, allowing extraction of wave dispersion relations in different ice conditions. Preliminary analyses demonstrate strong agreement between independent measurement methods, validating the dataset’s quality. This multi-sensor approach offers unique opportunities to improve our understanding of wave-ice interactions, wave attenuation, and fracture dynamics in situ, thus offering a valuable resource for the sea ice and oceanographic research community to gain insight in wave-induced ice break-up mechanisms under natural conditions
Neurobehavioral Changes in Macular Degeneration: Spatial Frequency Use in Scene Recognition
No full textInternational audiencePURPOSECentral vision loss in macular diseases severely affects visual perception and cognition, particularly scene recognition. A key question is whether observed impairments result solely from reduced input or reflect functional changes in spatial frequency processing. This study investigated how macular diseases affects this processing at both behavioral and brain levels.METHODSWe compared patients with macular diseases with age-matched controls using an artificial scotoma simulating each patient's central vision loss. Participants performed a scene categorization task with images filtered in high spatial frequencies (HSFs; fine details) or low spatial frequencies (LSFs; global shape). Patients fixated using their preferred retinal locus (PRL), whereas controls fixated on the location corresponding to the patient's fovea, within the artificial scotoma. Behavioral performance and functional magnetic resonance imaging (fMRI) responses were analyzed.RESULTSPatients performed worse than the healthy controls for both HSF and LSF scenes, with a more pronounced deficit for HSFs. These deficits were associated with reduced activation in occipital cortex and in the parahippocampal place area (PPA), particularly for HSF scenes. In contrast, LSF processing was relatively preserved and accompanied by increased recruitment of higher-level cognitive and oculomotor areas in patients.CONCLUSIONSThese findings demonstrate that macular diseases leads to altered spatial frequency processing within residual vision itself, particularly affecting fine-detail analysis. This perceptual degradation is accompanied by functional brain reorganization supporting partial compensation. The results highlight the importance of considering both degraded input and adaptive mechanisms when designing rehabilitation strategies based on residual peripheral vision
Photometric redshift estimation for Rubin observatory data preview 1 with redshift assessment infrastructure layers (RAIL)
No full textWe present the first systematic analysis of photometric redshifts (photo-z) estimated from the Rubin Observatory Data Preview 1 (DP1) data taken with the Legacy Survey of Space and Time (LSST) Commissioning Camera. Employing the Redshift Assessment Infrastructure Layers (RAIL) framework, we apply eight photo-z algorithms to the DP1 photometry, using deep ugrizy coverage in the Extended Chandra Deep Field South (ECDFS) field and griz data in the Rubin_SV_38_7 field. In the ECDFS field, we construct a reference catalog from spectroscopic redshift (spec-z), grism redshift (grism-z), and multiband photo-z for training and validating photo-z. Performance metrics of the photo-z are evaluated using spec-zs from ECDFS and Dark Energy Spectroscopic Instrument Data Release 1 samples. Across the algorithms, we achieve per-galaxy photo-z scatter of and outlier fractions around 10% in the 6-band data, with performance degrading at faint magnitudes and z>1.2. The overall bias and scatter of our machine-learning based photo-zs satisfy the LSST Y1 requirement. We also use our photo-z to infer the ensemble redshift distribution n(z). We study the photo-z improvement by including near-infrared photometry from the Euclid mission, and find that Euclid photometry improves photo-z at z>1.2. Our results validate the RAIL pipeline for Rubin photo-z production and demonstrate promising initial performance
The Freshwater Sounds Archive
No full textFreshwater ecosystems are full of underwater sounds produced by amphibians, aquatic arthropods, reptiles, plants, fishes, and methane bubbles escaping from the sediment. Although much headway has been made in recent years investigating the overall soundscapes of various freshwater ecosystems around the world, there remains a significant knowledge gap in our collective inability to accurately and reliably link recorded sounds with the species that produced them. Here, we present The Freshwater Sounds Archive, a new global initiative, which seeks to address this knowledge gap by collating species-specific freshwater sound recordings into a publicly available database. By means of metadata collection, we also present a snapshot of the species studied, the recording equipment, and recording parameters used by freshwater ecoacousticians globally. In total, 61 entries were submitted to the archive between the 4th of March 2023 and the 30th of April 2025, representing 16 countries and 6 continents. The most numerous taxonomic group was arthropods (29 entries), followed by fishes (14 entries), amphibians (10 entries), macrophytes (7 entries), and a freshwater mollusk (1 entry). The majority of the submissions were from European countries (27 entries), of which the United Kingdom was the most represented with 14 entries. The next most represented region was North America (11 entries), followed by South America (8 entries), Oceania and Asia (5 entries each), Africa (3 entries), and the Middle East and Central America with 1 entry each. The global south, polar regions, and areas with an elevation >500 m (asl) were underrepresented. The field of freshwater ecoacoustics to date has largely focused on the analysis of ‘sound types’ due to a current lack of knowledge of species-specific sounds. The Freshwater Sounds Archive presents an opportunity to move beyond the ‘sound type’ approach, and towards an approach with higher taxonomic resolution, ultimately resulting in species-specific descriptions. Furthermore, The Freshwater Sounds Archive will provide freshwater ecoacousticians with one of the main tools required to start creating annotated training datasets for machine learning models from soundscape recordings by referring to known species sounds present in the archive. In the long-term, this will result in the automatic detection and classification of species-specific freshwater sounds from soundscape recordings, such as indicator, invasive, and endangered species