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Composition et préservation du carbone organique dans les sédiments de zones humides côtières macrotidales : apports des biomarqueurs et des signatures isotopiques
No full textInternational audienceCoastal wetlands store high amounts of organic carbon (OC) in their sediments, but long-term preservation of this carbon depends on habitat type, sediment depth, and the molecular characteristics of organic matter (OM). This study explores the dynamics of OC deposition and preservation across vertical profiles (0–30 cm) in two adjacent coastal habitats—mudflat, and salt-marsh—within the macrotidal system of the Aiguillon Bay (France). A multi-tracer approach was applied, combining stable isotopes δ13C, C/N ratios, lignin phenols, and fatty acids. Sediment OC content ranged from 13.4 to 23.2 mgC g−1, with the highest concentrations found in the salt-marsh. δ13C and C/N signatures revealed dominant marine source in the mudflat, with a secondary contribution from microphytobenthos, and mixed marine–C₃ plant inputs in the salt-marsh. Fatty acids and lignin compositions supported this partitioning, with surface mudflat layers enriched in labile microbial and algal-derived compounds, whereas deeper salt-marsh sediments retained more resistant, C3 plant-derived signatures resembling those of terrestrial OM source. OM degradation rates were closely linked to source composition and depth. Degradation was concentrated within the top 5 cm of salt-marsh and the top 10 cm of mudflat. Below these depths, biomarker profiles changed minimally, delineating a transition to longer-term preservation. First-order degradation constants were three times higher in mudflat (0.53 yr−1) than in salt-marsh (0.17 yr−1), despite similarly high sedimentation rates (1.8 and 2.2 cm yr−1, respectively). This reflects differences in OM lability, with even minor contributions from microphytobenthos enhancing reactivity in mudflats. Salt-marshes, with their intermediate OM reactivity and high sedimentation rates, emerged as hotspots of carbon accumulation (366 gC m−2 yr −1), while mudflats also contributed substantially to coastal carbon sequestration (239 gC m−2 yr −1). These results highlight the value of depth-resolved, biomarker-based approaches to identify habitat-specific degradation dynamics; ultimately better understanding carbon accumulation in coastal ecosystems
Expanding the C3H6O2 isomeric interstellar inventory: Discovery of lactaldehyde and methoxyacetaldehyde in G+0.693-0.027
No full textInternational audienceAims. The tentative detection of 3-hydroxypropanal (HO(CH2)2C(O)H) toward the Galactic center molecular cloud G+0.693-0.027 prompts a systematic survey in this source aimed at detecting all C3H6O2 isomers with available spectroscopy.Methods. We used an ultra-deep broadband spectral survey of G+0.693-0.027, carried out with the Yebes 40 m and IRAM 30 m telescopes, to conduct the astronomical search.Results. We report the first interstellar detection of lactaldehyde (CH3CH(OH)C(O)H) and methoxyacetaldehyde (CH3OCH2C(O)H), together with the second detections (i.e., confirmation) of methyl acetate (CH3C(O)OCH3) and hydroxyacetone (CH3C(O)CH2OH), and new detections in this source of both anti - and g auche - conformers of ethyl formate (CH3CH2OC(O)H; the latter being tentative). For these species, we derived a fractional abundance relative to H2 of ~(0.81, 0.24, 16, 1.6, 1.3, 1.4) × 10−10, respectively. In contrast, neither propionic acid, CH3CH2C(O)OH, nor glycidol, c-CH2OCHCH2OH (i.e., the most and the least stable species within the C3H6O2 family, respectively) were detected, and we provide upper limits on their fractional abundances of ≤1.5 × 10−10 and ≤3.7 × 10−11. Interestingly, all C3H6O2 isomers can be synthesized through radical-radical reactions on the surface of dust grains, ultimately tracing back to CO as the parent molecule. We suggest that formation of the detected isomers is mainly driven by successive hydrogenation of CO, producing CH3OH and CH3CH2OH as the primary parent species. Conversely, propionic acid is thought to originate from the oxygenation of CO via the HOCO intermediate, which help us rationalize its non-detection. Overall, our findings notably expand the known chemical inventory of the interstellar medium and provide direct observational evidence that increasingly complex chemistry involving O-bearing species occurs in space
The COVID-19 pandemic influence on French-speaking occupational therapists' occupational identity and competence
No full textInternational audienceBackground The restrictive measures implemented during the COVID-19 pandemic affected the mental health and daily activities of occupational therapists (OT). Objectives To understand how the global environment, during the COVID-19 pandemic, influenced OTs' occupational identity and competence. Methodology Five French-speaking OTs per country (France, Belgium, Switzerland and Canada) were randomly recruited from the initial eCO3 (study on Occupational Competence during Confinement in the context of the COVID-19 pandemic) study. They took part in semi-structured interviews using the Occupational Performance History Interview-II (OPHI-II) between September and December 2021. Interviews were analysed using categorical content analysis, supported by a similarity analysis using IRAMUTEQ software. Results Few differences were established depending on the country. Maintaining stability while transforming one's occupations and developing social interactions was essential. At least one participant per country criticised their global environment. Conclusion During the pandemic, OTs took time to reflect on their occupational identity while remaining active to maintain a satisfying occupational competence. OTs, for whom adaptability has become essential, have strengthened their resilience during the crisis
Oral ivermectin versus 5% permethrin cream to treat children and adults with classic scabies: multicentre, assessor blinded, cluster randomised clinical trial
No full textInternational audienceObjective: To investigate whether oral ivermectin or topical 5% permethrin can clinically cure scabies in index cases and in members of their households.Design: Multicentre, assessor blinded, cluster randomised clinical trial.Setting: 28 French hospitals, 19 January 2016 to 16 December 2021.Participants: Index cases; adults and children weighing >15 kg with scabies, confirmed by dermoscopy.Interventions: Index cases were randomly assigned to the ivermectin group or permethrin group (1:1 ratio). Each member of the cluster, defined as the household of each index case, received the same treatment as the index case, except for children weighing 1 (0.67, 0.60 to 0.74 v 0.47, 0.37 to 0.56). Cutaneous adverse events were found in 11.9% and 15.6% of participants treated with ivermectin and permethrin, respectively.Conclusions: The results of this cluster randomised trial of classic scabies, confirmed by dermoscopy, did not show the non-inferiority of oral ivermectin compared with 5% permethrin cream, given on days 0 and 10, in achieving clinical cure of scabies on day 28 in index cases and their household members. Conversely, the trial showed the statistical superiority of 5% permethrin cream.Trial registration: NCT02407782
La pratique théâtrale : un moyen frugal et ralenti au service d’une formation au management respectueuse de la planète et plus efficace : le cas du projet collectif
No full textInternational audiencePROLOGUE : OBJECTIFS ET PROBLEMATIQUECe prologue tient lieu à la fois d’introduction générale du sujet, de présentation de la démarche de formation au management par la pratique théâtrale et aussi d’un court cadre conceptuel.Introduction générale. Compte tenu de la situation critique de la planète, nous sommes face à une impérieuse nécessité de faire évoluer nos pratiques managériales ainsi que les modèles pédagogiques qui les sous-tendent.Présentation du projet. C’est dans ce contexte que nous proposons une communication, dans un format alternatif, qui a pour objet de montrer en quoi la formation au management par la pratique théâtrale peut être, au-delà de ses qualités pédagogiques intrinsèques, un puissant vecteur pour aller vers plus de frugalité dans les comportements pédagogiques en management tout en intégrant la lenteur comme paramètre clé de ces formations. L’objectif final de ce format alternatif est la construction et la mise en œuvre (lors des journées MACCA) d’une formation destinée aux enseignants en management souhaitant s’inscrire dans l’animation de ce type de formation sans avoir pour autant d’expérience de la pratique théâtraleNotre questionnement est de nature empirique. Il s’agit d’une part, de montrer dans quelle mesure, une formation au management combinant projet collectif et pratique théâtrale permet de tendre vers plus de frugalité et une conception ralentie du temps. Nous souhaiterions d’autre part, que soit discuté collégialement les objectifs, la nature, les conditions et les résultats de formations qui font l’objet de la proposition de cet atelier. En guise de cadre conceptuel nous croiserons les travaux de l’anthropologue et Philosophe, Pierre Sansot (1998) dans « le bon usage de la lenteur » avec les réflexions du sociologue d’E. Goffman (1973) sur la métaphore dramaturgique, ainsi que les travaux des dramaturges de C. Stanislavski (1963) et Lavandier (2019)
Enhanced Lysosomal Glycogen Breakdown is associated with Liver Tumorigenesis in Glycogen Storage Disease Type III
No full textInternational audienceBackground & Aims: Glycogen storage disease type III (GSDIII) is a rare metabolic disorder caused by mutations in the glycogen debranching enzyme (AGL), leading to hepatic glycogen accumulation, fibrosis and increased hepatocellular carcinoma (HCC) risk. This study investigates the metabolic mechanisms driving liver tumorigenesis in an Agl-/- model of GSDIII. Methods: Liver and tumor samples from 14-month-old Agl-/- and Agl+/+ mice, and liver biopsies from GSDIII patients (n=4), were analyzed using histological, biochemical and molecular approaches. Results: Agl-/- mice recapitulated key features of GSDIII, including a 3.5-fold hepatic glycogen overload (p<0.001), and chronic liver disease. More than 30% of the animals developed liver tumors, associated to a 2.5-fold increase in α-fetoprotein levels (p<0.005). Despite marked reductions in glucose (7.5-fold, p<0.0001), glucose-6 phosphate (6.2-fold, p<0.0001), lactate (8-fold, p<0.005), cholesterol (1.9-fold, p<0.001) and triglyceride levels (6.2-fold, p<0.001) in the liver, glycaemia was maintained at around 87.0±9.6 mg/dl after 6h of fasting, through activated extrahepatic, but not hepatic, gluconeogenesis. Intriguingly, most tumors exhibited lower glycogen content than surrounding tissue (3.3-fold decrease, p<0.0001), associated with increased lysosomal α-acid glucosidase activity (19.5±5.5 in tumor vs 9.9±2.0 mmol/h/mg in Agl -/-liver; p<0.0005) and the presence of glycophagosomes. PAS-negative staining in GSDIII patient HCCs supported these observations. Although YAP nuclear staining varied between tumors, overall increased YAP nuclear localization and CTGF expression suggest that Hippo/YAP pathway inhibition could contribute to tumorigenesis in GSDIII hepatocytes.Conclusions: In GSDIII, liver metabolism is characterized by the accumulation of structurally abnormal glycogen and a significant reduction of key energy substrates. In this metabolic context, enhanced lysosomal glycogen degradation may support tumor growth, highlighting a mechanistic link between glycogen metabolism and the development of liver cancer
New Safe Screening Rule for Fast Optimal Transport on Tree, Cycle and Cactus Graphs
No full textExisting approaches to discrete balanced Optimal Transport (OT) face some important challenges. While the optimal transport problem can be solved in polynomial time on Euclidean spaces and graphs, the best known strongly polynomial algorithms require superlinear time complexity. Recent methods, Sliced-OT and Tree-Sliced OT, reduce this time complexity by approximating data points on Euclidean spaces using simple graphs such as paths and trees, where closed-form expressions for OT enable more efficient computations. However, these graph structures are too simple and cannot capture topological features such as loops.In this work, we address both limitations by studying OT on simple cactus graphs, a class of graphs with loops that includes trees and cycles as special cases. Our main technical tool is a new safe screening rule, inspired by sparse optimization, for identifying zero entries in the OT plan on graphs. This rule allows us to characterize the structure of OT on graphs and leads to efficient computational methods. First, it provides a purely combinatorial proof of the closed-form expression for OT on trees, previously derived using Kantorovich duality theory. Second, it allows OT on a single cycle to be reformulated as a weighted median problem on a line, enabling an efficient solving method. Finally, we derive a decomposition formula for OT on cactus graphs by reducing the problem to computations on tree and cycle components. All the results show that OT on cactus graphs can be computed in linear time
Representations: A meta-model for system analysis
No full textThe formal analysis of automated systems is an important and growing industry. This activity routinely requires new verification frameworks to be developed to tackle new programming features, or new considerations (bugs of interest). Often, one particular property can prove frustrating to establish: completeness of the logic with respect to the semantics. In this paper, we try and make such developments easier, with a particular attention on completeness. Towards that aim, we propose a formal (meta-)model of software analysis systems (SAS), the eponymous Representations. This model requires few assumptions on the SAS being modelled, and as such is able to capture a large class of such systems. We then show how our approach can be fruitful, both to understand how existing completeness proofs can be structured, and to leverage this structure to build new systems and prove their completeness
Variational autoencoder for inference of nonlinear mixed effect models based on ordinary differential equations
No full textInternational audienceWe propose a variational autoencoder (VAE) approach for parameter estimation in nonlinear mixed-effects models based on ordinary differential equations (NLME-ODEs) using longitudinal data from multiple subjects. In moderate dimensions, likelihood-based inference via the stochastic approximation EM algorithm (SAEM) is widely used,but it relies on Markov Chain Monte-Carlo (MCMC) to approximate subject-specific posteriors. As model complexity increases or observations per subject are sparse and irregular, performance often deteriorates due to a complex, multimodal likelihood surface which may lead to MCMC convergence difficulties. We instead estimate parameters by maximizing the evidence lower bound (ELBO), a regularized surrogate for the marginal likelihood. A VAE with a shared encoder amortizes inference of subject-specific random effects by avoiding per-subject optimization and the use of MCMC. Beyond pointwise estimation, we quantify parameter uncertainty using observed-information–based variance estimator and verify that practical identifiability of the model parameters is not compromised by nuisance parameters introduced in the encoder. We evaluate the method in three simulation case studies (pharmacokinetics,humoral response to vaccination, and TGF-β activation dynamics in asthmatic airways) and on a real-world antibody kinetics dataset, comparing against SAEM baselines
Prevention of secondary infections by interferon-gamma in ICU-acquired sustained immune suppression in France: study protocol of the PLATINIUM randomised trial
No full textInternational audienceIntroduction: Some intensive care unit (ICU) patients develop an extremely deep and sustained immunosuppression that increases the risk of secondary infections and can ultimately compromise survival. Thanks to an easily accessible and simplified immune monitoring to identify immunological failure, a personalised immune restoration approach is now feasible. Among the different therapeutic strategies in this field, interferon gamma (IFN-γ) is probably the most interesting drug to reduce the burden of secondary infections in the ICU.Methods and analysis: This is a two parallel group multicentre blinded add-on randomised trial comparing immunorestoration by subcutaneous injection of IFN-γ to standard of care in targeted ICU patients. The study will be performed in 23 ICUs in France. Patients hospitalised in the ICU for a week, with multiple organ failure defined by a sequential organ failure assessment score ≥6 during this first week, will be enrolled. If within 96 hours after inclusion, these patients express immunosuppressed features defined by a low absolute lymphocyte count (<1000/×109/L) and low expression of human leucocyte antigen-DR (HLA-DR) on monocytes (<8000 antibodies bound per cell [Ab/c]) they will be randomised (1:1) to receive either five subcutaneous injections of IFN-γ or placebo in addition to standard of care. The primary outcome will be the incidence of secondary infection episodes at day 90 validated by an independent adjudication committee based on the current definitions (Centers for Disease Control and Prevention surveillance definitions). Secondary outcomes will be all-cause ICU mortality at day 90, length of stay in the ICU and in the hospital at day 90, antibiotic and antifungal consumption at day 90, percentage of biological immune restoration (defined as a monocytic HLA-DR >13 500 antibodies bound per cell and an absolute lymphocyte count >1200 ×109/L) at day 10, healthcare costs at day 90 and rate of serious adverse reactions and suspected unexpected serious adverse reaction at day 90. We plan to randomise 326 patients.Ethics and dissemination: The study will be implemented in accordance with European regulations and was independently reviewed and approved by the French Ethics Committee Comité de Protection des Personnes Ile de France III (EUCT number: 2024-516780-93-00). The results will be reported in international peer-reviewed journals and presented at international and national conferences.Trial registration number: NCT06774235