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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
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
Growth and phosphorus uptake of micropropagated southern highbush blueberry plants inoculated with ericoid endophytic and mycorrhizal fungi in varied growth substrates
No full textInternational audiencePhosphorus (P) acquisition and use by southern highbush blueberry Vaccinium corymbosum L. plants is critical during early stages of development and impair root development, especially for growth substrates with poor nutrient contents. However, inoculation of blueberry plants with ericoid mycorrhizal fungi (ErMF) or dark septate endophytes (DSE) can improve P during the plants acclimation stages and reduce plant mortality, especially in dry northern Mediterranean climate conditions. Herein, we grew southern highbush blueberry micro-cuttings in conditions without inoculation (control) or in inoculated with four strains: two Ericoid mycorrhizal sp. (D01), and (C01), E. endophyte (C31), and Phialocephala fortinii Wang & Wilcox in sandy (S), fresh field (FF), and FF+S soil mix substrates for 10 months before harvest. At harvest, root colonization levels, plant height, leaf area, the fresh matter of roots and shoots, root-to-shoot ratio, P content, and P utilization efficiency (PUE) were measured. We found that the root colonization levels were inhibited in the S for the different inoculated F treatments, owing to the elevated carbonate and salt concentrations present. The average P uptake responses from the different F inoculated strains were 52.2 %, 29.6 %, and 22.4 % in the S, FF, and FF+S substrates. Inoculation of blueberry plants with C31 strain exhibited the highest (59.1 %) P uptake average response, inoculation with P. fortinii strain showed the lowest (15.8 %) response. The root growth responses were inhibited in the FF+S (-0.2 %), increased in the S (8.4 %), and FF (6.2 %) substrates. Our findings therefore describe responses under controlled nursery conditions with single-strain inoculation and three substrate types. Because blueberry roots in the field are commonly co-colonized by multiple ericoid and endophytic fungi, interactions among partners may amplify or dampen the effects observed here; future work should test coinoculation consortia and validate performance under field conditions.</div
IPVS Consensus Statement on The Natural History of Cervical Human Papillomavirus Infection
No full textInternational audienceBackground: Changes in cervical type-specific human papillomavirus (HPV) detection may reflect both natural variation in detectability and recent infection or clearance.Methods: The Policy Committee of the International Papillomavirus Society (IPVS) convened a multidisciplinary working group to review scientific evidence and terminology related to the natural history of cervical type-specific HPV infections.Results: The group proposes an updated model that distinguishes 3 cervical states: no HPV infection, undetectable HPV infection, and detectable HPV infection. An undetectable HPV infection refers to either a state of low viral genome load below the cutoff of the assay used or to a particular state of viral latency. These 2 states are virtually indistinguishable, and viral latency remains a topic of ongoing research and debate. The transition from HPV not detected to HPV detected is consistent with several possible events, including (i) acquisition from a partner, (ii) autoinoculation, (iii) transition from undetected to detected HPV infection, and (iv) transient deposition of viral material. Conversely, the transition from HPV detected to HPV not detected is consistent with (i) viral clearance, (ii) transition from detected to undetected HPV infection, and (iii) inadequate sampling. The likelihood of each possible explanation depends on context, including screening history, exposure, age, and immune status.Conclusions: By distinguishing true cervical states from observed test results, the updated model acknowledges uncertainties that complicate the interpretation of HPV test result patterns in research and practice. Adopting this model may improve clarity and ensure consistency in scientific and clinical communication about cervical HPV infections
Comparative Analysis of Irradiation Technologies on High-Density Polyethylene (HDPE) for Biopharmaceutical Applications
No full textInternational audienceThe impacts of e-beam and X-ray irradiation on medical-grade high-density polyethylene (HDPE) are compared with that of gamma irradiation to evaluate their potential effects on pharmaceutical applications. An extensive suite of analytical techniques was employed to evaluate the chemical and physical transformations of irradiated HDPE. Key findings indicated that irradiation did not significantly alter the mechanical properties, as tensile strength and elongation at break remained stable across all irradiation types and doses. Thermal analysis via Differential Scanning Calorimetry (DSC) revealed a slight decrease in melting temperature at higher doses, with an equivalent melting temperature peak observed for all three irradiation technologies. Electron Spin Resonance (ESR) detected alkyl and allyl radicals, which decreased over time, showing no significant differences attributable to irradiation type or dose. Colorimetric analysis indicated yellowing in the samples, linked to specific additives. The quantification of methionine oxidized byproducts by High-Performance Liquid Chromatography (HPLC) demonstrated that the oxidation potential was equivalent for the three irradiation technologies for HDPE. The study concluded that there was a lack of significant impact of irradiation technologies on several physical, chemical and mechanical properties of HDPE
Flood pulse monitoring in wetlands with multi-temporal Sentinel-1 interferometric coherence data: Application to the Okavango Delta (Botswana)
No full textInternational audienceFlood-pulsed wetlands are characterized by significant seasonal water fluctuations, which play a critical role in the dynamics of these sensitive ecosystems. Among the growing number of existing remote sensing products, we explore the potential of interferometric (InSAR) coherence time series, derived from Sentinel-1 synthetic-aperture radar images, to characterize the hydrological dynamics of the Okavango Delta, a vast flood-pulsed wetland. Interferometric coherence reflects changes in surface conditions, making it a powerful tool for detecting flood propagation. By fitting harmonic functions, we produce parameters that quantify the seasonality of coherence time series with short isotemporal baselines (12 days). In particular, we developed a normalized seasonal index based on the ratio between the seasonal amplitude and the root-mean-square error of the fitted harmonic function, to map the seasonality of the coherence time series. A multi-annual analysis of coherence time series reveals a strong relationship between their seasonality, land cover, and flood frequency. Unsupervised clustering applied to statistical and seasonal metrics of coherence time series yields consistent classifications that map the variability of flood frequencies across wetland areas and clearly distinguish wetlands from dry zones. Similarly thresholds applied to normalized seasonal indices delineate the year-to-year extent of flood pulses with accuracy around 79 %. We show that coherence time series in never flooded areas exhibit a pronounced seasonal pattern driven by rainfall cycle, whereas this seasonality is disrupted by flood pulses in wetlands. Building on this, developed a change-detection approach to map the floods by identifying the date when coherence time series diverge from their seasonal pattern. The resulting flood arrival dates achieve 74–83 % accuracy compared to a reference dataset derived from optical data. Our results highlight the potential of coherence time series as a robust indicator of seasonal variations in inundation extent in flood-pulsed wetlands
The role of hydrogen sulfide and trisulfur radical ion in molybdenum transport by hydrothermal fluids: implications for porphyry-epithermal Cu-Au-Mo deposits
No full textInternational audienceKnowledge of the chemical speciation of molybdenum in fluids under hydrothermal conditions is key to understanding the formation of porphyry Cu-Au-Mo deposits, which are the primary economic source of copper, molybdenum and rhenium. However, the chemical identity and thermodynamic stability of aqueous complexes of molybdenum and the role of different ligands on Mo metal transport yet remain inconsistent and incomplete, in particular for sulfur-bearing fluids typical of such environments. We have experimentally studied the role of hydrogen sulfide (H 2 S and HS -) and the trisulfur radical ion (S 3 •-) in the transport of molybdenum by hydrothermal fluids at 300 °C and 500 bar as a function of pH, redox conditions as well as sulfur speciation and concentration. We combined solubility measurements of molybdenite in hydrothermal reactors using fluid quenching or sampling, with in situ synchrotron X-ray absorption spectroscopy experiments and thermodynamic and molecular modeling. Our solubility and spectroscopic dataset is consistent with the formation of the tetrathiomolybdate complex, MoS 4 2-, in reduced, H 2 S/HS --dominated fluids of neutralto-alkaline pH. In contrast, a mixed-ligand complex with three sulfide ions and one trisulfur radical ion, MoS 3 (S 3 ) -, prevails in more oxidized and more acidic fluids at the sulfide-sulfate transition where S 3 •-is far more abundant. In both complexes, Mo is nominally hexavalent and in a first-shell tetrahedral coordination with sulfur atoms. The derived equilibrium constants of the formal solubility reactions (log 10 K):MoS 2(s) + 2 H 2 S 0 (aq) + 0.5 O 2(g) = MoS 4 2-+ 2 H + + H 2 O (liq) and MoS 2(s) + H 2 S 0 (aq) + S 3 •-+ 0.5 O 2(g) = MoS 3 (S 3 ) -+ H 2 O (liq) , at 300 °C and 500 bar are 0.5±0.4 and 14.6±0.4, respectively. The solubility of MoS 2(s) predicted using these constants aligns well with Mo concentrations measured in natural fluid inclusions in quartz that record S-rich fluids from porphyry-epithermal systems. In contrast, other types of Mo complexes invoked so far (molybdates, alkali ion pairs, oxy-chlorides or oxysulfides) are negligible at such conditions. Thus, trisulfur radical ion complexes may be important carriers of Mo in hydrothermal fluids and would require further systematic investigation across a wide range of temperature and pressure.</p