Apport des isotopes de la molécule d'eau à la détermination de l'altitude de recharge des principales sources du Moyen Atlas calcaire (Maroc).

International audienceLa présente étude est menée au Maroc sur le Moyen Atlas calcaire à caractère karstique. Son objectif est de contribuer à la caractérisation des aquifères moyens atlasique et à la détermination des altitudes de recharge des principales sources issues des calcaires dolomitiques liasiques afin d'aider à la détermination de leurs zones d'alimentation pour leur protection. La méthodologie utilisée est basée sur l'utilisation des isotopes stables de la molécule d'eau. La caractérisation chimique des eaux de ces sources montre que leur composition est le reflet de celle des roches-réservoirs qu'elles drainent d'une part et de l'évolution qu'elles subissent au cours de leur transit au sein de ces réservoirs d'autre part. L'analyse de l'évolution du deutérium en fonction de l'oxygène 18 permet de tracer une droite locale similaire à celle des pluies analysées au sein de la station de Fès, ce qui montre que les aquifères concernés se rechargent par une infiltration rapide, sans évaporation notable des eaux de pluie. Le gradient altimétrique pour l'oxygène 18 est établi à -0.27‰ par 100m. L'application de ce gradient aux teneurs isotopiques des autres sources analysées permet de remonter aux altitudes de recharge de ces sources. La confrontation de ces résultats aux données hydrogéologiques locales et régionales montre une concordance notable pour les sources dont les bassins versants étaient connus, et une orientation précieuse pour les sources dont les bassins étaient mal connus, avec des altitudes de recharge qui peuvent être 1090m plus élevées que les zones d'émergence. Ces résultats aident d'une manière certaine à déterminer les zones de recharge des sources, et donc à définir une stratégie de protection de cette ressource. The present study contributes to the characterisation of Middle Atlas limestone karst aquifers by implementing water stable isotopic techniques to determine the recharge altitudes of major springs issuing from Liassic dolomitic limestone, helping to delineate protection areas for the springs. Chemical analyses of spring waters show a composition that reflects both reservoir lithology and a chemical evolution over the course of flow within the reservoir. Analysis of the evolution of deuterium as a function of oxygen-18 suggests a local water line similar to that derived for rainwater at a station in Fez, indicating that the aquifers in question are recharged through rapid infiltration, without appreciable evaporation of the rainwater. Application of the established -0.27‰ per 100m altimetric gradient for oxygen 18 to the isotopic signatures of other analyzed sources allows us to backtrack recharge altitudes for these springs. Comparison of these results with local and regional hydrogeologic data shows a notable agreement among springs for which the drainage basin is known, and allows for more precise localization of springs for which the drainage basin is poorly known, with recharge altitudes reaching 1090m higher than emergence zones. To a certain extent, these results help to determine recharge zones for Middle Atlas springs and thus aid in strategizing protection for this resource

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

A Novel Approach Based on Machine Learning, Blockchain, and Decision Process for Securing Smart Grid

Smart Grids (SGs) rely on advanced technologies, generating significant data traffic across the network, which plays a crucial role in various tasks such as electricity consumption billing, actuator activation, resource optimization, and network monitoring. This paper presents a new approach that integrates Machine Learning (ML), Blockchain Technology (BT), and Markov Decision Process (MDP) to improve the security of SG networks while ensuring accurate storage of events reported by various network devices through BT. The enhanced version of the Proof of Work (PoW) consensus mechanism ensures data integrity by preventing tampering and establishing the reliability of known and unknown attack detection. The proposed versions of PoW, namely GPoW 1.0 and GPoW 2.0, aim to make the consensus process more environmentally friendly