Understanding complex volcanic hydrosystems using a multi-tracer approach

International audienceClimate change affects groundwater availability and residence times, necessitating a thorough understanding of aquifer characteristics to define sustainable yields, particularly in regions where water is heavily exploited. This study focuses on the Volvic volcanic aquifer (Chaîne des Puys, France), where groundwater recharge has decreased due to climate change, raising concerns about water use sustainability. To address these challenges, this work proposes a multi-tracer approach, based on hydrogeological monitoring, including the estimation of groundwater ages, major elements chemistry and water stable isotopes to better characterise this resource decrease and more peculiarly its origin and its impact on the environment that has never been addressed. Relative fractions of ancient and modern water contributions (up to 20 %) to the aquifer have been thus estimated as well as the apparent ages of groundwaters (34 years). We highlight the complementarity of tracers used, allowing a better definition of recharge sources and transit times of groundwaters within the aquifer. These results led to the proposal of a hydrogeological conceptual model, highlighting a bi-modal recharge, distinguishing between a long-term recharge upon 30 years, supplemented by a recent component (≃ 1 year) related to annual precipitation. This study provides valuable information on groundwater circulation and the response of volcanic aquifers systems to climate change, while highlighting the importance of assessing residence times. By addressing the challenges posed by systems with contrasting permeability and recharge gradients, it improves understanding of volcanic hydrology and provides a basis for the development of (numerical) hydrological models to assess the impacts of global change

Les processus d’acclimatation des arbres face aux stress mécaniques : la gravité et le vent

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Techniques d’identification microbienne

MasterDescription de l'ensemble des techniques d'analyse microbienne, leur intérêts, limites et choix en fonction des besoins et du type d'échantillons.Focus particulier sur l'outil Maldi TOF, principe, protocole, intérêts et limite

Improved Degradation of Phenanthrene in Soil Washing Eluent byPhoto-Fenton Like Process with Citric Acid

International audienceHerein, improved degradation of phenanthrene (PHE), one of the common polycyclic aromatic hydrocarbons (PAHs), was explored in a citric acid (CA) photo-Fenton like system under UVB irradiation. Degradation of PHE in soil washing (SW) eluent by the nonionic surfactant Tween 80 (TW80) using Fe(III)-CA complex was compared with other iron complexes showing a faster degradation with a rate constant of 3.07 × 10−2 min−1. The stability as well as photochemical transformation of Fe(III)-CA under UVB radiation was evaluated, followed by comparison of PHE oxidation with traditional Fenton or Fenton like process. Fe(III)-CA complex was found to be stable in dark but quickly photo dissociated under irradiation. The system using Fe(III)-CA was proved oxidizing PHE more efficiently than traditional Fenton reaction with a rate constant of 3.92 × 10−3min−1 and Fe(II)-CA involved system with a rate constant of 1.74 × 10−2 min−1. A two-stage pattern of PHE decay was observed in the UVB/H2O2/Fe(III)-CA system. The effects of operational factors including Fe(III)-CA dosage, Fe(III)/CA ratio, H2O2 and TW80 dosage on PHE degradation were explored. The checked parameters exhibited different influence on PHE degradation. This work provided a cost-effective strategy for remediating soil pollutants in SW effluent with the presence of surfactant

"Retour sur les principales dispositions répressives de la loi SREN : deepfake et bannissement numérique"

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« Ah ! Je t’arracherai cette langue importune. » Parole et violence dans La Place Royale, Le Menteur et La Suite du Menteur

https://www.fabula.org/colloques/document13462.ph

Fairness-Aware Demodulator Allocation in LoRa Multi-Gateway Networks

International audienceThe literature has shown the drastic decrease of the achievable LoRa network throughput, due to the limited number of demodulators that are supported by LoRaWAN gateways. Unlike existing approaches, in this work, we design fairnessaware algorithms under this stringent constraint. By taking the efficient demodulation time ratio as a fairness metric, our algorithms enable to prioritize frames with larger spreading factors, while increasing the total demodulation time thanks to collaboration among gateways. Numerical results demonstrate that our proposed methods largely outperform LoRaWAN baselines, while closely approaching their performance upper bounds

Who Pays Whom? Anonymous EMV-Compliant Contactless Payments

International audienceEMV is the de-facto worldwide payment system used by Mastercard, Visa, American Express, and such. In-shop EMV contactless payments are not anonymous or private: the payers’ long-term identification data leaks to Merchants or even to observers. Anti-Money Laundering (AML), Know Your Customer (KYC) and Strong Customer Authentication (SCA) are payment regulations protecting us from illegal activities, but –in so doing– contribute chiefly to this lack of privacy in EMV payments. Threading the tightrope of AML, KYC and SCA regulations, we provide two privacy-enhancing, EMV-compatible, law-abiding and practicable contactless-payments protocols: PrivBank and PrivProxy. We do not use privacy-enhancing technology, like homomorphic encryption, that would break backwards-compatibility with current EMV, but rather we do privacy by engineering design, adhering to the existing EMV infrastructure, as is. So, PrivBank and PrivProxy provably achieve strong notions of payers and merchant privacy, anonymity and unlinkability as seen in e-cash or shopping vouchers, whilst being implementable in EMV as it stands

Causalités

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