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High-temperature measurements of acetylene VUV absorption cross sections and application to warm exoplanet atmospheres
No full textInternational audienceContext. Most observed exoplanets have high equilibrium temperatures (Teq > 500 K). Understanding the chemistry of their atmospheres and interpreting their observations requires the use of chemical kinetic models including photochemistry. The thermal dependence of the vacuum ultraviolet (VUV) absorption cross sections of molecules used in these models is poorly known at high temperatures, leading to uncertainties in the resulting abundance profiles.Aims. The aim of our work is to study experimentally the thermal dependence of VUV absorption cross sections of molecules of interest for exoplanet atmospheres and provide accurate data for use in atmospheric models. This study focuses on acetylene (C2H2).Methods. We measured absorption cross sections of C2H2 at seven temperatures ranging from 296 to 773 K recorded in the 115–230 nm spectral domain using VUV spectroscopy and synchrotron radiation. These data were used in our 1D thermo-photochemical model, to assess their impact on the predicted composition of a generic hot Jupiter-like exoplanet atmosphere.Results. The absolute absorption cross sections of C2H2 increase with temperature. This increase is relatively constant from 115 to 185 nm and rises sharply from 185 to 230 nm. The abundance profile of C2H2 calculated using the model shows a slight variation, with a maximum decrease of 40% near 5 × 10−5 bar, when using C2H2 absorption cross sections measured at 773 K compared to those at 296 K. This is explained by the absorption, higher in the atmosphere, of the actinic flux from 150 to 230 nm due to the increase in the C2H2 absorption in this spectral range. This change also impacts the abundance profiles of other by-products such as methane (CH4) and ethylene (C2H4).Conclusions. We present the first experimental measurements of the VUV absorption cross sections of C2H2 at high temperatures. Similar studies of other major species are needed to improve our understanding of exoplanet atmospheres
Vaccination in patients with heart failure in practice
No full textInternational audienceAbstract This narrative review underscores the pivotal role of vaccination in mitigating respiratory infections and associated acute decompensations in heart failure (HF) patients. It highlights the necessity for heightened awareness and proactive engagement among healthcare providers to bridge vaccination gaps and enhance preventive care for HF patients. Respiratory pathogens, such as influenza, pneumococcus, SARS-CoV2, and Herpes zoster virus (VZV), instigate systemic inflammation and increase cardiovascular events, markedly elevating the risk of HF and strokes, especially in individuals with preexisting conditions. Respiratory infections further amplify the risk of thrombotic events in HF patients through mechanisms involving a heightened procoagulant status due to inflammation. Systemic inflammation often accompanies HF, contributing to its progression, complications, and acute episodes, particularly during respiratory infections. While promising therapeutic approaches are under development, the review aims to provide a comprehensive overview of the pathophysiology linking inflammation, infection, and HF. The review then explores current clinical knowledge on the protective effects of vaccines against respiratory diseases (influenza, pneumococcal infection, SARS-CoV2, RSV, and emerging pathogens) in HF patients, along with the key applicable guidelines. It also offers strategies to enhance vaccination coverage in HF patients, highlighting practical issues pertinent to daily clinical practice
Can increasing environmental policy stringency promote financial development? Evidence from developed economies.
No full textInternational audienceDespite extensive research to explore the channels through which environmental policy stringency can affect economy, to our best knowledge, current literature has not yet studied its impact on financial development in the long term. To fill this lacuna, this study empirically examines the effect of environmental policy stringency index on financial development index and its components, which are financial institutions development index and financial markets development index, in 27 OECD countries during the period 1990-2015. We found a positive association between environmental policy stringency index and financial development. The results also revealed that the past values of environmental policy stringency index can help to predict financial development index and financial institutions development index. These results imply that financial development is a new channel through which increasing environmental policy stringency could promote economic growth. Moreover, these findings show that environmental policy stringency forms a new positive determinant of financial institutions development in OECD countries
Fintech entrepreneur financing decision: Does the Pecking Order Theory still apply?
No full textInternational audienceThe rise of fintech startups has transformed the financial landscape, offering innovative solutions that challenge traditional banking models. There is a nascent literature exploring their potential to revolutionize financial services. However, these ventures may also face significant challenges when it comes to accessing financing and launching their own operations. Contrary to previous studies, we investigate the Fintech entrepreneur financing decision by adopting a qualitative approach through in-depth semi-structured interviews and by focusing on the Pecking Order Theory
: Comprendre la gestion circulaire des déchets, du geste citoyen à l’infrastructure technique
No full textInternational audienceLes déchets sont au cœur d’un nouveau modèle économique dit d'économie circulaire où il s’agit autant de transformer les modes de conception, production et consommation des produits que de limiter la consommation des ressources et la production des déchets par la création de boucles créatrices de valeur économique, sociale et environnementale. Le premier chapitre de l’ouvrage expose les responsabilités et modes de gestion des collectivités et explicite le mouvement d’écologisation législative et règlementaire. Les trois chapitres qui suivent présentent trois types de tentatives pour sortir du vieux schéma in et out de la gestion des déchets (collectes-traitement-évacuation) et adopter une approche cyclique (matières et matériaux passent tour à tour de l’état de déchet à celui de ressource du fait de leur réemploi)
Prediction of elastic properties of polyethylene terephthalate after biaxial elongation using a multiscale approach
No full textInternational audienceAbstract. Poly(ethylene terephthalate) (PET) is widely used in packaging due to its mechanical properties, which are closely linked to its microstructure. To better understand how PET crystallizes under stretching, we studied its behavior during biaxial tensile test near the glass transition temperature (Tg). A biaxial testing machine with heating system was developed to perform in-situ tests under a synchrotron beam. Small-angle X-ray scattering (SAXS) analysis was conducted under constant width (CW) and equal-biaxial (EB) loading conditions to examine macromolecular orientation and crystallization. A two-step homogenization approach was developed to estimate the elastic properties of stretched PET based on the observed microstructural changes. This study highlights the relationship between the microstructure and mechanical properties of PET, particularly the effects of strain-induced crystallization and molecular orientation. Additionally, a parametric uncertainty study on the elastic properties of the oriented amorphous phase was carried out to test the sensitivity of the elastic moduli. Monte Carlo simulations confirmed the convergence of the model, supporting the robustness of the predictions in terms of both means and standard deviation statistical data
Recommandations pour la prise en charge des pneumonies d’inhalation – Société de Pathologie Infectieuse de Langue Française 2025
No full textInternational audienc
SARS-CoV-2 entry and fusion are independent of ACE2 localization to lipid rafts
No full textInternational audienceMembrane fusion occurs at the early stages of SARS-CoV-2 replication, during entry of the virus, and later during the formation of multinucleated cells called syncytia. Fusion is mediated by the binding of the viral Spike protein to its receptor ACE2. Lipid rafts are dynamic nanodomains enriched in cholesterol and sphingolipids. Rafts can act as platforms for entry of different viruses by localizing virus receptors, and attachment factors to the same membrane domains. Here, we first demonstrate that cholesterol depletion by methyl-beta-cyclodextrin inhibits Spike-mediated fusion and entry. To further study the role of ACE2 lipid raft localization in SARS-CoV-2 fusion and entry, we designed a GPI-anchored ACE2 construct. Both ACE2 and ACE2-GPI proteins were similarly expressed at the plasma membrane. Through membrane flotation assays, we show that in different cell lines, ACE2-GPI localizes predominantly to raft domains of the plasma membrane while ACE2 is non-raft associated. We then compare the ability of ACE2 and ACE2-GPI to permit SARS-CoV-2 entry, replication, and syncytia formation of different viral variants. We find little difference in the two proteins. Our results demonstrate that SARS-CoV-2 entry and fusion are cholesterol-dependent and raft-independent processes. IMPORTANCE Rafts are often exploited by viruses and used as platforms to enhance their entry into the cell or spread from cell to cell. The membrane localization of ACE2 and the role of lipid rafts in SARS-CoV-2 entry and cell-to-cell spread are poorly understood. The function of lipid rafts in viral fusion is often studied through their disruption by cholesterol-depleting agents. However, this process may have off-target impacts on viral fusion independently of lipid-raft disruption. Therefore, we created an ACE2 construct that localizes to lipid rafts using a GPI anchor. Conversely, wild-type ACE2 was non-raft associated. We find that the localization of ACE2 to lipid rafts does not modify the fusion dynamics of SARS-CoV-2
Deciphering the role of water in ethanol uptake within PIM-1 membranes
No full textInternational audienceMolecular interactions between solvents and membranes are a key factor for understanding the performance of organic solvent nanofiltration membranes. In this study, the behavior of pure water and ethanol as well as their mixtures confined in a PIM-1 membrane was investigated by means of molecular dynamics simulations. The nitrogen atom of PIM-1 was found to be the preferential interaction site for the various systems. The uptake of pure water and ethanol by the PIM-1 membrane was found similar. However, the ethanol uptake greatly increased in the presence of water, whatever the composition of the mixture. This intriguing behavior was further explained by molecular simulations, which revealed that water molecules create molecular bridges between the PIM-1 nitrogen atoms and ethanol molecules via hydrogen bonds, thus providing additional adsorption sites for ethanol. Simulations also highlighted that the translational dynamics of ethanol in the PIM-1 membrane was slowed down more than that of water due to the larger molecular size of ethanol (greater degree of confinement) and that it was more strongly impacted by the membrane confinement than by water-ethanol interactions. The same conclusion was drawn for rotational dynamics. However, for confined mixtures, the rotational dynamics of confined water were found to be imposed by ethanol, with similar relaxation times for both kinds of dipole
Réflexions sur l’attractivité du régime fiscal applicable à l’entreprenant en république démocratique du Congo
No full textEn 2010, l'Acte uniforme OHADA portant droit commercial général a connu des modifications dont la plus importante est l'institution du statut d'entreprenant. L'un des objectifs visés est de permettre à toute la masse d'acteurs économiques de petite taille dont les micros entreprises œuvrant dans le secteur informel de migrer vers le formel. Pour ce faire, les États devraient prendre des mesures attractives afin d'inciter ces acteurs à venir œuvrer dans le circuit formel. Cela étant, cette étude aborde le régime fiscal institué par l'État congolais afin d'apprécier s'il est incitatif à l'activité d'entreprenant. Ainsi, nous avons constaté que l'entreprenant est soumis au régime du paiement d'un impôt forfaitaire annuel de 50.000 Francs Congolais, qui nécessite pour acquérir ce caractère attractif, des mesures d'accompagnement comme l'amnistie fiscale, la création des guichets uniques de paiement des taxes dues par l'entreprenant, la numérisation de la déclaration et du paiement de cet impôt, etc. Lesquelles malheureusement tardent à venir. Mots clés : Secteur informel-Entreprenant-Acte uniforme OHADA portant droit commercial général-régime fiscal-mesures incitatives