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Sliding and Burrowing Blocks of CO <sub>2</sub> Create Sinuous “Linear Dune Gullies” on Martian Dunes by Explosive Sublimation‐Induced Particle Transport
No full textInternational audienceMartian linear dune gullies are landforms consisting of parallel and often sinuous channels with distinct levees and pit-shaped endings that occur in the mid-latitudes on Mars. Recent observations link their formation to sublimating CO 2 -ice blocks that slide downslope in early spring. Here we combine laboratory experiments in which we release CO 2 -ice blocks on sandy slopes under Martian atmospheric pressure with observations of linear dune gullies on Russell crater mega dune to test this hypothesis. We show that, on steep slopes (>22.5°in our experiments) sublimating CO 2 -ice blocks slide down-slope, creating straight, shallow channels with indistinct levees. On more gentle slopes (<22.5°in our experiments), sublimating CO 2 -ice blocks burrow themself into the sand and slowly migrate downslope by excavating their surroundings by explosive gasdriven sediment transport. The burrowing movement helps explain the formation of unique characteristics of linear dune gullies; high levees, deep channels, channel sinuosity, and pit-shaped channel endings.Plain Language Summary On some of the dune fields on Mars, parallel channels, called linear dune gullies, are found. Contrary to their name these gullies are often highly sinuous. In the past, it was believed that these linear dune gullies were formed by debris flow processes driven by liquid water. However, new evidence from satellite images shows that these channels are active in local spring by a process driven by CO 2 ice. The CO 2 ice forms on the Martian dunes in local winter and breaks off at the top of the dune at the beginning of spring. With laboratory experiments in a Mars chamber, we show that linear dune gullies are being formed by blocks of CO 2 -ice that slide or burrow themselves into the sandy slope of the dune and move themselves downslope by violently ejecting the surrounding sand. This excavation process is caused by powerful gas flows, created by the sublimation of the CO 2 -ice, when CO 2 ice is turned into CO 2 gas. While sliding blocks of CO 2 ice explain the formation of shallow channels, burrowing CO 2 -ice explains the creation of the deep, and sinuous channels on the dunes of Mars.</div
Les pratiques familiales jouent un rôle dans l’acquisition des compétences mathématiques chez les jeunes enfants
No full textInternational audienceHow can family activities help to shape early mathematical skills in young children? This article explores the impact of a home intervention on the development of early numeracy skills. We recruited over a hundred children aged 4 to 5 and their parents. After six weeks of activities, we observed a significant improvement in children’s numeracy skills, notably in ordinality.Our results highlight the substantial effect of simple and playful home activities with mathematical content on children’s learning. We propose that such findings should support the integration of mathematical home practices into educational policies and early learning support programmes.Comment les pratiques familiales peuvent-elles participer à façonner les compétences précoces en mathématiques chez le jeune enfant ? Cet article explore l’impact d’une intervention familiale sur le développement des compétences mathématiques précoces. Nous avons recruté plus d’une centaine d’enfants âgés de 4 à 5 ans et leurs parents. Après six semaines d’activités, nous avons constaté une amélioration significative des compétences des enfants en numératie (notamment en ordinalité). Nos résultats mettent en avant l’effet substantiel des activités familiales avec du contenu mathématique, simples et ludiques, sur l’apprentissage des enfants. Nous proposons que de tels résultats doivent soutenir l’intégration des pratiques familiales mathématiques dans les politiques éducatives et les programmes de soutien à l’apprentissage précoce
Enquêter sur les forêts alpines par la transdisciplinarité : participer, confronter et transmettre
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Recovery of Fatigue, Cardiorespiratory Fitness, and Neuromuscular Function in COVID-19 ICU Patients: A 6-Month Follow-Up Study
No full textInternational audiencePurpose: Although most patients recover well from Covid-19 infection, this may not be the case of those who experienced severe dysfunction after being admitted to intensive care unit (ICU). This study aimed to assess the recovery of patients who experienced severe multiple dysfunctions after being admitted to intensive care unit (ICU) for Covid-19 infection.Methods: Forty-seven patients hospitalized and mechanically ventilated in ICU for SARS-CoV-2 infection underwent evaluations at 4-8 weeks (T1) and 6 months (T2) post ICU discharge. Evaluations included questionnaires, lung function tests, incremental cardiopulmonary exercise testing, and neuromuscular function tests.Results: From T1 to T2, the percentage of patients classified as fatigued decreased from 56% to 21% whereas forced vital capacity and the forced expiratory volume in one second increased by 13% and 8% (p<0.05) to reach 93% and 95% of predicted values at T2, respectively. Peak work rate also increased from 97 to 135 W (+35±32%, p<0.001). Likewise, V ̇O2 peak increased from 18.3 to 21.6 ml/min/kg (+18±27%, p<0.001) to reach 72% of predicted values. Maximal strength and the number of contractions during the fatigability test increased between T1 and T2 by 41% and 39%, respectively (both p<0.001).Conclusions: Six months of recovery improved patients' physical function and reduced fatigue
Articulating while listening: The perception-production link in early infancy
No full textThere is a growing body of work in infant speech perception proposing that the auditory analysis of speech is coupled with articulatory information involved in speech production. These studies show that the link between perception and production emerges early in infancy, and before infants have some experience with speech production. However, the mechanisms behind the development of this link are not well understood. Importantly, research has not yet addressed whether infants produce linguistically-driven articulatory movements when perceiving speech. To address this question, we employed ultrasound imaging to record the tongue shapes of 6-month-old infants while listening to vowel-consonant-vowel sequences that differed in the articulatory configuration of the consonant. If tongue shape varied as a function of the speech token heard, listening to a dental sound like /t/, and to a velar sound like /k/, would trigger differences in tongue shape. The results confirmed this prediction, showing that infants produced articulatory movements by placing the tongue more to the front or back in the direction of the sounds they heard. Our findings are the first to suggest that infants engage in speech driven oral-motor responses modulated by the sounds perceived, advancing our understanding of the mechanisms for the emerging perception-production link
ParAquaSeq, a Database of Ecologically Annotated rRNA Sequences Covering Zoosporic Parasites Infecting Aquatic Primary Producers in Natural and Industrial Systems
No full textInternational audienceAmplicon sequencing tools such as metabarcoding are commonly used for thorough characterisation of microbial diversity in natural samples. They mostly rely on the amplification of conserved universal markers, mainly ribosomal genes, allowing the taxonomic assignment of barcodes. However, linking taxonomic classification with functional traits is not straightforward and requires knowledge of each taxonomic group to confidently assign taxa to a given functional trait. Zoosporic parasites are highly diverse and yet understudied, with many undescribed species and host associations. However, they can have important impacts on host populations in natural ecosystems (e.g., controlling harmful algal blooms), as well as on industrial‐scale algae production, e.g. aquaculture, causing their collapse or economic losses. Here, we present ParAquaSeq, a curated database of available molecular ribosomal sequences belonging to zoosporic parasites infecting aquatic vascular plants, macroalgae and photosynthetic microorganisms, i.e. microalgae and cyanobacteria. These sequences are aligned with ancillary data and other information currently available, including details on their hosts, occurrence, culture availability and associated bibliography. The database includes 1131 curated sequences from marine, freshwater and industrial or artificial environments, and belonging to 13 different taxonomic groups, including Chytridiomycota, Oomycota, Phytomyxea, and Syndiniophyceae. The curated database will allow a comprehensive analysis of zoosporic parasites in molecular datasets to answer questions related to their occurrence and distribution in natural communities. Especially through meta‐analysis, the database serves as a valuable tool for developing effective mitigation and sustainable management strategies in the algae biomass industry, but it will also help to identify knowledge gaps for future research
Primacy of lattice distortion over strain in platinum fuel cell nanoalloy catalysts
No full textInternational audienceComprehensive wide-angle X-ray scattering analyses demonstrate that local lattice strain plays a key role in governing the activity and long-term stability of bimetallic Pt-based catalysts
Les institutions financières indiennes, organes au service du centralisme fiscal et financier fédéral
No full textInternational audienceDepuis 2015, l’Inde, État fédératif, connaît un phénomène de centralisation des pouvoirs financiers. Deux types d’outils sont utilisés afin de permettre cette tendance centripète : des institutions contrôlées par le pouvoir exécutif fédéral (le NITI Aayog et la Commission des finances) ainsi que des instruments financiers et fiscaux modifiés (l’accroissement des subventions conditionnelles) ou créés (la taxe sur les produits et les services)
Hydrogène électrolytique en Europe : progresser en intégrant les incertitudes
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Online/Operando Insights Into Cu-Al Bimetallic Catalysts For Efficient CO2 Electroreduction Toward Liquid Products
No full textInternational audienceThe CO2 electrochemical reduction (CO2RR) is a most promising technologies to mitigate CO2 emissions and generating value-added products. The formation of multi-carbon products involves a range of transient intermediates, the behavior of which critically influences the reaction pathway and product distribution [1]. Consequently, it is still a challenge to design a catalyst that can efficiently and rapidly reduce CO2 and obtain high-value products. Copper is the most promising key electrocatalyst, particularly in producing valuable hydrocarbons and alcohols, that hold substantial value in modern industries [2]. However, challenges such as weak *CO adsorption, high C–C coupling barriers, and competition with e.g hydrogen evolution reaction (HER) lead to complex product distributions [3]. To address these limitations, researchers have explored various strategies, including heteroatom doping, surface engineering, surface oxidation tuning, size control, and alloying. Among these, alloying stands out as it enhances active site diversity and enables electronic structure modulation via intermetallic interactions, offering a promising route to improve catalytic activity and selectivity.In the present work, we demonstrate that Cu–Al bimetallic electrocatalysts, fabricated via physical vapor deposition onto gas diffusion electrodes Cu90Al10, exhibit excellent performance in the electrocatalytic reduction of CO2 to C2+ products. Notably, the bimetallic catalysts achieved a C₂⁺ Faradaic efficiency exceeding 60% at elevated current densities above 450 mA cm⁻² in a flow cell configuration, significantly outperforming their monometallic Cu counterparts prepared under identical sputtering conditions. These results, supported by operando synchrotron-based spectroscopic analyses, online inductively coupled plasma mass spectrometry (ICP-MS) and advanced density functional theory (DFT) calculations, reveal the distinctive catalytic advantages of Cu–Al systems. Theoretical insights further demonstrate that incorporation of Al into the Cu matrix modulates the electronic structure of Cu, facilitating the C-C coupling in key intermediates shared by both ethylene and ethanol pathways. This electronic tuning preferentially accelerates the C2 formation pathway, highlighting the synergistic effect of alloying and electronic modulation in directing product selectivity during CO₂ electroreduction.1. Seh, Z.W., et al., Combining theory and experiment in electrocatalysis: Insights into materials design. Science, 2017. 355(6321).2. Wu, H., et al., Selective and energy-efficient electrosynthesis of ethylene from CO2 by tuning the valence of Cu catalysts through aryl diazonium functionalization. Nature Energy, 2024. 9(4): p. 422-433.3. Lei, H., W. Zhang, and J. Yang, Theoretical Insights into Enhancing Catalytic Performance of Al–Cu Alloy for CO2 Electroreduction toward Ethene Production. The Journal of Physical Chemistry Letters, 2024. 15(21): p. 5643-5653