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Livre de la Nature, Nature du livre : Pratiques des femmes botanistes
No full textInternational audienc
2D numerical model for gas mass transfers in modified atmosphere packaging systems
No full textInternational audienceThe complexity of some food-packaging systems requires mathematical models of mass transfers to accurately predict the evolution of headspace gas composition during storage and better anticipate food shelf-life. In this study, a numerical 2D model of O 2 /CO 2 transfer in a cheese packaging system was proposed. The results showed significant involvement of gas sorption/desorption in food and permeation through the tray in evolution of gases in headspace. In this context, only a 2D model provided a good fit to experimental results, as gas permeation at the food/tray interface was non-negligible, limiting 1D approaches. This validated 2D model was then used in a global sensitivity analysis employing the Morris method to quantitatively identify the most influential mass transfer parameters affecting prediction accuracy. The results revealed a significant impact of O 2 and CO 2 permeability of the tray and their activation energies, as well as O 2 and CO 2 solubility and diffusivities in food. Therefore, to obtain a robust model of a food packaging system, it is recommended to integrate gas transfers between food and tray when the food-tray interface area is significant (2D model) and to precisely evaluate the gas permeability of the tray. These transfers can be neglected when this interface area is minimal (1D model).</div
Benzoxaborole drugs in therapy: successful cases of Tavaborole and Crisaborole
No full textInternational audienc
Deciphering pro‐arrhythmogenic mechanisms of EPAC in human atrial cardiomyocytes
No full textInternational audienceExchange protein directly activated by cAMP (EPAC) 1 and EPAC2 are involved in electrophysiological modulation in ventricular cardiomyocytes. Their putative contribution in supra‐ventricular arrhythmogenic processes has been suggested in animal models. However, nothing is known about the electrophysiological remodelling and the underlying signalling pathway regulated by EPACs in human atrial cardiomyocyte. Action potentials (AP) and K + currents ( I K ) were recorded with the patch‐clamp technique in enzymatically freshly isolated human atrial cardiomyocytes. Acute EPAC activation with the EPAC agonist 8‐(4‐chlorophenylthio)‐2′‐ O ‐methyl‐cAMP acetoxymethyl ester (8‐CPTAM; 10 µmol/l) lengthened APs by inhibition of the repolarizing K + currents in myocytes obtained from sinus rhythm (SR) patients. The selective EPAC1 pharmacological blocker AM‐001 (20 µmol/l) or the EPAC2 inhibitor ESI‐05 (25 µmol/l) prevented the effect of 8‐CPTAM on APs and I K , indicating that both EPAC isoforms participate in this electrophysiological regulation. Mechanistically, the effects of EPAC1 and EPAC2 proteins on the inhibition of three major components of K + currents, I to , I KDR, and I KUR , were Ca 2+ ‐independent but involved Ca 2+ /calmodulin‐dependent protein kinase II (CaMKII) and the AMP‐activated protein kinase (AMPK)–nitric oxide synthase (NOS)–protein kinase G (PKG) axis. Interestingly, immunoblot analysis showed that EPAC1 but not EPAC2 was overexpressed in the atria of atrial fibrillation (AF) patients. Finally, the application of AM‐001 consecutively to the 8‐CPTAM treatment significantly corrected the EPAC‐dependent downregulation of I K in AF cardiomyocytes. Our results uncover that EPAC activation influences I K by CaMKII and the AMPK–NOS–PKG signalling pathways in human atrial cardiomyocytes. Moreover, our findings suggest that EPAC1 over‐activation in AF cardiomyocytes promotes the electrophysiological remodelling underlying the initiation of AF. image Key points Activation of exchange proteins directly activated by cAMP (EPAC) lengthens action potentials (AP) in human atrial cardiac myocytes. This AP duration increase is mediated by an inhibition of the repolarizing K + current. Using EPAC1 and EPAC2 pharmacological inhibitors (AM‐001 and ESI‐05, respectively), we show that both EPAC1 and EPAC2 isoforms are involved in these electrophysiological effects. Mechanistically, EPAC‐induced K + current inhibition signalling involves both CaMKII and AMPK–NOS–PKG pathways. EPAC1 but not EPAC2 is overexpressed in atrial samples of patients with atrial fibrillation (AF). A selective pharmacological inhibitor of EPAC1, AM‐001 prevents the downregulation of K + current in cardiomyocytes from AF patients. Our results suggest that over‐activation of EPAC1 and its signalling represent a cellular mechanism for atrial arrythmia and might be a potential target for the treatment of AF
Phi-FEM-FNO: a new approach to train a Neural Operator as a fast PDE solver for variable geometries
No full textInternational audienceIn this paper, we propose a way to solve partial differential equations (PDEs) by combining machine learning techniques and the finite element method called phi-FEM. For that, we use the Fourier Neural Operator (FNO), a learning mapping operator. The purpose of this paper is to provide numerical evidence to show the effectiveness of this technique. We will focus here on the resolution of two equations: the Poisson-Dirichlet equation and the non-linear elasticity equations. The key idea of our method is to address the challenging scenario of varying domains, where each problem is solved on a different geometry. The considered domains are defined by level-set functions due to the use of the phi-FEM approach. We will first recall the idea of -FEM and of the Fourier Neural Operator. Then, we will explain how to combine these two methods. We will finally illustrate the efficiency of this combination with some numerical results on three test cases. In addition, in the last test case, we propose a new numerical scheme for hyperelastic materials following the phi-FEM paradigm
Hidden diversity of Palaeogene metatherians: a new family of polydolopimorphian marsupials from Peruvian Amazonia
No full textInternational audienceSouth American marsupials are widely dominated by opossums and their kin today. Nevertheless, metatherian high-level taxonomic diversity was much higher before Pleistocene times. Here we describe two new species and a new genus documenting the extinct order Polydolopimorphia, based on extensive material from Eocene–Oligocene localities of Peruvian Amazonia. Wamradolops telloi Stutz sp. nov. and Pozodolops manuelorum Stutz gen. et sp. nov. are morphologically close to the early Oligocene Wamradolops tsullodon Goin and Candela, 2004 from the same area. Parsimony analyses performed here strongly suggest that these three taxa document a new early-diverging clade of Polydolopimorphia, Wamradolopidae Stutz fam. nov., restricted to tropical-equatorial lowlands and falling outside the suborders Bonapartheriiformes and Polydolopiformes. These phylogenetic affinities further point to a Paleocene–early Eocene ghost lineage for Wamradolopidae Stutz fam. nov., most likely at low latitudes of South America. Dental dimensions suggest that representatives of Wamradolopidae Stutz fam. nov. were extremely small, with estimated body masses ranging 3–55 g. With cranial dimensions comparable to those of the living long-tailed planigale and Etruscan shrew, Wamradolops telloi Stutz sp. nov. counts among the smallest mammals ever described
Bulletin de veille du réseau d'écotoxicologie terrestre et aquatique N°81
No full textINRAE, réseau ECOTOX → A paraîtreBulletin de veill
Mid-Holocene wet optimum and Early-Late Holocene arid phases shaped steppe-forest vegetation and human societies of Uzbekistan: Multi-proxy evidences from Lake Fazilman
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Benthic ecological changes in response to fish farming waste deposition in tropical environment: combining field and modelling approaches
No full textInternational audienceWhile substantial progress has been made in evaluating the ecological carrying capacity (ECC) for fish farming in temperate regions, studies in tropical environment remain scarce, and benthic ecological thresholds are still lacking. This study combines spatial measurements of waste deposition (quantified with sediment traps and depositional modelling approaches), with measurements of sediment physical and biogeochemical properties and macrobenthic community structure at a shallow, non-dispersive site in Martinique. Despite minimal changes in sediment physical and biogeochemical properties, pronounced effects were observed on macrobenthic communities structure. At farm sites, benthic communities were highly perturbed (extremely low diversity and abundance of individuals) and dominated by few individuals of second-order opportunistic species. At sites located between 25 and 150 m from the farm, benthic communities were similar and characterised by higher diversity and abundance, with the presence of sensitive species to OM enrichment. The benthic response was strongly driven by organic waste deposition, which was elevated directly beneath and adjacent to the fish cages. The benthic response to depositional fluxes was best described by M-AMBI index. Notably, the transition from ‘Moderate’ to ‘Poor’ ecological status occurred within a depositional range of 1.2–3.0 kg m−2 year−1 for POM and 0.6–1.1 kg m−2 year−1 for TOC, with model predictions suggesting that these effects may extend up to 30 m from the farm. This study represents a step forward in defining benthic ecological thresholds for tropical fish farming and will help decision makers in fostering the sustainable development of aquaculture in these regions
Eco-epidemiological thresholds for malaria transmission in multi-species, phenotypically structured mosquito populations
No full textUnderstanding how vector richness influences malaria transmission remains a critical challenge in disease ecology and public health. We develop a mathematical model that integrates both interspecific and intraspecific phenotypic diversity within mosquito populations, structured by chronological age and continuous phenotypic traits. Our framework couples these diverse mosquito populations with a human host population to analyze the eco-epidemiological dynamics of malaria transmission. We conduct a detailed analysis of the mosquito population's asymptotic behavior and invasibility analysis. Additionally, we identify an eco-epidemiological threshold parameter that synthesizes mosquito vectorial capacity, intrinsic fitness differences, and ecological competition to predict whether the addition of a new mosquito species amplifies or dilutes epidemic risk. Through this approach, we show that vector species abundance alone is insufficient to determine malaria transmission potential; rather, the interplay between phenotypic variation and ecological interactions governs epidemic outcomes. Our results generalize and extend previous theoretical studies by incorporating structured population dynamics and continuous trait variation, providing a mechanistic basis for anticipating how changes in mosquito community composition may impact malaria transmission risk