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A method to estimate absolute odorant concentration of olfactory stimuli
No full textInternational audienceThe accurate quantification and delivery of odorant concentrations remain a significant challenge. Traditional methods estimate stimulus intensity based on the amount of odorant in the source, but this does not reflect the actual concentration sent due to variable evaporation rates and delivery devices. This leads to inconsistencies in stimulus delivery, complicating cross-laboratory comparisons, threshold evaluations, and the replication of natural olfactory conditions in the lab. To address this, we present a model based on mass transfer theory to predict the concentration of odorants delivered by a simple and versatile odor delivery system commonly used in insect electrophysiological experiments. The present model, built with adaptable compartments, accounts for airflow, source size, and the physicochemical properties of odorants. It helps to better design and use odor delivery systems, especially for stimuli required to mimic natural odor environments. Calibration uses known partition coefficients. The model also considers the dynamic shape of odor stimuli, which affects neuronal responses and must be carefully interpreted, especially when using tools like photoionisation detectors (PID). This approach was applied to study the impact of a plant volatile known to activate pheromone-sensitive neurons, (Z)-3-hexenyl acetate, on pheromone detection in Agrotis ipsilon moths. While interference occurs in laboratory conditions at 160 ppb, such concentrations are unlikely in natural settings, suggesting these effects are less relevant ecologically
Dissipative Solutions to a Compressible Non-Newtonian Korteweg System with Density-Dependent Viscous Stress Tensor
No full textThe main objective of this paper is to prove that if capillarity effect is taken into account then there exist dissipative solutions to a system describing viscoplastic compressibleflows with density dependent viscosities in a periodic domain \T^d with . We calculate the relative entropy inequality and in consequence show existence of dissipative solutions and the weak-strong uniqueness for this system. Our result extends the recent result concerning the link between Euler--Korteweg and Navier--Stokes--Korteweg systemsfor Newtonian flows (when the viscosity depends on the density) [See D.~Bresch, M. Gisclon, I. Lacroix-Violet, {\it Arch. Rational Mech. Anal.} (2019)] to non-Newtonian flows
Soil-to-river Cesium-137 transfer in a catchment coupling the SWAT model and a mass balance equation
No full textInternational audienceNuclear accidents and atmospheric tests have released large quantities of radionuclides into the environment. Among them, Cesium-137 ( 137 Cs) is of major concern due to its long-term persistence. To support post-accidental management, predictive tools are needed to assess its environmental transfers. This study presents a novel approach to simulate the transfer of 137 Cs from soils to the river outlet in a watershed impacted by radioactive atmospheric fallout. The Soil and Water Assessment Tool (SWAT) was coupled with a trace metal transfer equation to simulate daily concentrations of 137 Cs in suspended sediments in the Ardèche watershed (2138 km 2 , France). The total 137 Cs stock in soils was estimated at 7.7 TBq based on a soil sampling campaign. Modelled 137 Cs concentrations range from 0 to 43.0 Bq kg -1 , whereas measured values range from 3.5 to 20.1 Bq kg -1 . The discrepancies are mainly due to limitations in SSC observations used for model calibration, as well as the particle-trap sampling method, which tends to underestimate the actual concentrations. Moreover, results indicate that 83 % of the annual 137 Cs transport occurs in the particulate phase with 75 % of the total annual 137 Cs flux at the outlet exported during the top 10 % highest flow days. On average, 263.0 GBq y -1 of 137 Cs are eroded from the watershed soils, the river exports 1.62 GBq y -1 of 137 Cs at the outlet and stores 256.0 GBq y -1 within the river itself and floodplain. This corresponds to an annual export of only 0.02 % of the total 137 Cs soil stock
Platinum and Rare Earth Elements distribution in costal sediments from French western Mediterranean Sea
No full textInternational audienc
Environmental consequences of genetic improvements of growth and fillet yield in gilthead seabream: A life cycle assessment from breeding to plate
No full textInternational audienceSelective breeding plays a key role in the sustainable development of aquaculture by improving productivity and efficiency. While breeding programs have initially focused on growth traits, their potential to mitigate the environmental footprint of fish farming remains poorly explored. Here, we present a case-study on the environmental consequences of selective breeding during five generations (15 years) for growth and fillet yield in gilthead sea bream Sparus aurata by integrating genetic gain projections into a full supply chain Life Cycle Assessment (LCA), extending from hatchery to final consumer. The potential impacts were calculated in terms of 1 tonne of fish produced at the farm level and were also expressed per tonne of flesh consumed. Performance data and genetic parameters from families in a seabream breeding program were used to estimate breeding values under different selection scenarios. Selection for growth significantly shortened the production cycle, while selection for fillet yield increased the proportion of edible product. Although environmental gains at the farm level were modest (<1 %), substantial reductions (up to 7 % in climate change impacts and cumulative energy demand) were observed when impacts were expressed per tonne of fillet consumed. Feed production and consumption remained the dominant source of environmental burden across all scenarios. By explicitly accounting for post-farm stagesprocessing, distribution, consumption, and waste management -our study demonstrates that genetic improvement, particularly for fillet yield, can meaningfully reduce the environmental footprint of aquaculture products delivered to the consumer. This case study underlines the importance of integrating full supply chain assessments into genetic selection strategies to drive sustainable breeding in aquaculture
Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon
No full textInternational audienceZircon (ZrSiO4) is the oldest-known mineral of Earth and an ubiquitous silicate in geochronology. More specifically, the accumulation of alpha decay damage in zircon over time significantly affects its physical and chemical properties, and can lead to a disturbance of the ages measured in this mineral. Therefore, analytical tools that enable comprehensive structural and chemical information at the nanoscale in this compound are highly sought after. In this context, we explore the electron energy-loss fine structures resulting from the excitation of O1s and Si2p core electrons in zircon, which are interpreted from ab initio calculations in a single-particle framework. An excellent agreement is obtained between the experimental and calculated fine structures, emphasizing the large distortion of the final electronic states induced by the core-hole potential. The O-K edge is particularly rich in information, with intense peaks dominated by O2p - Zr4d and O2p - Si3sp hybrids. This work suggests that the near-edge structures from the O1s and Si2p excitations accessible from electron energy-loss spectroscopy or X-ray absorption spectroscopy could be used as tools to follow, interpret and understand structural and chemical modifications in zircon subject to natural radiation damage. We illustrate the potential of this approach through the evolution of near-edge fine structures in a zircon sample that exhibits a locally amorphized zone formed by ultrafast laser excitation
Exner diagnosis method for two-fluid morphodynamics simulations
No full textInternational audienceMass balance in sediment transport is often associated with single-phase flow model through the resolution of the Exner equation. In this contribution, the mass balance is derived from the two-phase flow, two-fluid, model equations and compared with the conventional single-phase flow approach. Five terms are identified from the two-phase flow formulation: the bed evolution, the storage evolution, the lateral flux, the bed flux and the top flux. Three different flow configurations with increasing complexity are tested, namely a one dimensional pure sedimentation, a two dimensional scour downstream an apron and a three dimensional scour around a vertical square cylinder. The mass balance formulation identifies the driving process of an erosion or a deposition process in each case. This approach can be applied on other configurations related with sediment flux and morphology bed evolution such as scour process
Growth, metabolic, and immune responses of lean and fat rainbow trout lines during a starvation-refeeding cycle
No full textInternational audienceUnderstanding how fish with divergent energy reserve profiles respond to feed deprivation is critical for optimizing aquaculture feeding strategies. In this study, we compared two rainbow trout (Oncorhynchus mykiss) lines selected for low (lean, L) or high (fat, F) muscle lipid content. Both lines underwent a 3-week starvation period followed by 3 weeks of refeeding using self-feeders. The L line exhibited faster post-refeeding growth, higher post-refeeding weight gain, and earlier feeding activity concentrated in the morning. Conversely, the F line showed greater weight loss during starvation, reduced haematocrit and innate immune parameters, and limited metabolic recovery. Starvation induced distinct changes in lipid and protein metabolism, hydromineral regulation, and immune responses, with the F line being more metabolically and immunologically impacted. Plasmatic concentrations of calcium and sodium decreased, while chlorides concentrations increased transiently. Principal Component Analysis revealed stronger physiological disruption in the F line during starvation. These findings highlight how fat reserves influence recovery from nutritional stress, offering perspectives for genotype-specific feed management in aquaculture
Monitoring tropical forests with light drones: ensuring spatial and temporal consistency in stereophotogrammetric products
No full textInternational audienceThis study benefited from an "Investissement d'Avenir" grant managed by the Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01), via project PHENOBS. We also acknowledge the support of the UE Biodiversa+ BiodivMon program (Project Coforfunc). We are thankful to Ilona Clocher, Jean-Louis Smock, Jean-Yves Goret, Florian Jeanne and Julien Engel for their help with drone data acquisition and/or processing. Access to the Paracou site and infrastructure (https://paracou.cirad.fr) was granted by CIRAD/Ecofog, and we thank Géraldine Derroire and all Phenobs project participants. We are grateful to Raphaël Pélissier for helping in the initial shaping of the Phenobs project and for his continued support
Co-circulation and co-infection: parasite interactions across scales
No full textInternational audienceClimate change and human activities are shifting parasite distributions, and thus causing novel parasite co-occurrences</div