Combined use of seismic, isotopic and piezometrics data to reduce uncertainty in models

International audienceTo improve modelling of complex multi-aquifer systems, a better understanding of To improve modelling of complex multi-aquifer systems, a better understanding of reservoirs’s geometry and an improvement of calibration are required. Combining seismic data, isotopic analysis and piezometrics measurements is a way to improve flow simulation.In Gironde (France), many hydrodynamics models have been developed to guide choices in groundwaters exploitation. They put into evidence a lack of knowledge on the Villagrains-Landiras structure corresponding to a potential recharge area for the aquifers of the region. To correct these shortcomings, a detailed study of this area was undertaken to measure its potential for exploitation.Three exploratory wells reaching depths ranging from 200 to 350 m have been drilled to refine the structural vision of the region and to delimitate the various erosional gaps.To improve significantly the knowledge of the reservoirs’s geometry, seismic reflection has been used to obtain a high-resolution image of the subsoil. A total of 15 seismic lines have been used, representing a total length of 248 km. At first, 13 old lines, coming from oil prospecting, have been reprocessed to maximize the definition of hydrostratigraphic units in the first 300 meters. Then, two news high-resolution seismic lines have been achieved in September 2007 on a total length of 17.5 km. This geological survey has helped us to constrain the pattern of the various aquifers of the structure. It has also enabled us to adjust the elevation of the tops and bottoms used in the hydrodynamic model.The aim of the hydrogeological study was to characterize the hydrodynamic mechanisms affecting the Villagrains-Landiras structure. The design of water level maps allowed us to study the distribution of hydraulic heads in comparison to the structure and to measure its potential influence on the recharge of groundwaters. The analysis of the piezometrics fluctuations underlined many similar variations which characterize locals behaviour. Isotopic analysis (18O, 2H, 3H, 13C, 14C), allow us to study the recharge, to confirm the influence of the structure in this process and to constrain residence time in the model. This important part of the study involves the interpretation of analysis coming from 4 different aquifers, sampled in 21 wells located on the structure and its near vicinity.This multidisciplinary approach, based on the interpretation of seismic, isotopic and piezometric data, helped us to improve the knowledge of the structural arrangement of the aquifers and the understanding of the hydrodynamic processes to simulate more efficiently flows in the model

La Corse enjeu géostratégique en Méditerranée et les marins Cap Corsins

La Corse a été tenue à l’écart des enjeux méditerranéens jusqu’au XVIe siècle. Par nature le Corse tourne le dos à la mer, sauf dans la région du Cap Corse grâce à l’existence des ports Centuri et Macinaggio. Les Corses présents dans l’histoire maritimes de l’île sont issus de cette région. Cet article analyse les vies de marins célèbres : Sampiero, Lenche, Negroni, etc., leurs activités tant militaires que commerciales, à Marseille et dans le monde musulman.Corsica has been kept out of the way of mediterranean stakes untill XVIth century. By nature Corsica turns its back to the sea except in the area of Corsica Cape owing to the existence of harbours as Centuri and Macinaggio. Corsicans present in the naval history of the island are descended from this place. This study shows us life of famous sailors : Sampiero, Lenche, Negroni... thier military activities so far as business relations, to Marseille and to the moslem world

1720-1721 : la peste ravage Toulon

Toulon connaît les épidémies depuis toujours : 1348, 1581, 1587, 1664. D’où la création de Bureaux de Santé à Marseille et Toulon, ce dernier dès 1576. Celui-ci instaura à Lagoubran – à l’ouest de Toulon –, un lazaret qui devait permettre de faire accoster les bateaux dans un abri jusqu’à la fin de leur mise « en quarantaine » ; néanmoins ce lazaret fut plus un mouroir qu’un établissement de soin. La peste de 1720-1721 le prouva. Début octobre 1720, les premiers cas de peste apparaissent à Toulon. Mi-octobre, les premiers morts. En février 1721, les morts remplissent un tombereau quotidien : cinquante places. En mars, deux tombereaux deviennent nécessaires pour évacuer les cadavres : cent morts par jour. La Marine organise son périmètre de sécurité et prend une décision originale puisqu’elle décide d’enfermer les « jeunes », c’est-à-dire les gardes de la marine au « Jardin du Roi ». Tous survivront à l’exception d’un Moscovite, envoyé à Toulon par Pierre le Grand, et imprudemment sorti du « Jardin du Roi ». En avril, quatre tombereaux quotidiens s’avèrent nécessaires : deux cent soixante et dix morts sont à déplorer pour le 30 avril. Début mai, huit tombereaux quotidiens deviennent indispensables : quatre cents morts quotidiens. L’épidémie culmine. En vain, on cherche des remèdes. On pend quelque galérien et quelques filles de joie pour tenter d’exorciser le mal. Ici, un capucin multiplie les prêches. Là, l’évêque de Toulon voue Toulon au Sacré-Coeur. Le 10 mai, la « serrade » est levée. Le 30 octobre, un Te Deum réunit les survivants : environ 10 000 habitants sur 25 000. La peste fut une vraie catastrophe ; démographique, culturelle, quantités de « savoirs » ayant été emportés. Toulon est au plus bas : le commerce ruiné, l’artisanat en déroute. La ruine est autant morale qu’économique. Il fallut attendre quarante années pour que la population toulonnaise « récupère » ses effectifs de 1720 décimés par la peste.Toulon has always experienced epidemics. Such was the case in 1348, 1581, 1587 and 1664 hence the setting up of boards of health in Marseilles and Toulon. The latter boasted one as early as 1576. A lazaretto was established in Lagoubran, west of Toulon. It was supposed to have allowed ships to berth in a shelter until their quarantine had come to an end but that lazaretto was more of a place where people were left to die than a medical care institution. The plague of 1720-1721 gave proof of it. In early October 1720, the first cases of plague appeared in Toulon. By mid October, there were the first dead. In February 1721 the dead filled a fifty-body tip cart on a daily basis. In March, two tip carts became necessary to get rid of corpses : one hundred people died every day. The Navy planned its safety zone and made an original decision since it decided to confine the “young ones”, that is the navy guards to “the King’s Garden”. All of them were to survive except for one Muscovite who had been sent to Toulon by Peter the Great and had recklessly left the “King’s Garden”. In April, four daily tip carts proved to be necessary: sadly, there were two hundred and seventy dead by April 30th. In early May, eight tip carts became indispensable: there were four hundred dead each day. The epidemic then reached its peak. Remedies were looked for but to no avail. A few galley slaves and a few ladies of the night were hanged to try and exorcize evil. Here, a Capuchin friar read repeated sermons. There, the Bishop of Toulon vowed Toulon to the Sacred Heart. On May 10th, the quarantine (“serrade”) was lifted. On October 30th, a Te Deum gathered the survivors: roughly 10 000 inhabitants out of 25 000. The plague was a real catastrophe both demographically and culturally speaking. A great deal of “know-how” had been taken away. Toulon was at a very low ebb: its trade was ruined; its crafts had collapsed. The ruin was both moral and economic. Forty years elapsed before the population of Toulon was able to recover the numbers of 1720 which had been decimated by the plague

Pauli Blockade in a Few-Hole PMOS Double Quantum Dot limited by Spin-Orbit Interaction

We report on hole compact double quantum dots fabricated using conventional CMOS technology. We provide evidence of Pauli spin blockade in the few hole regime which is relevant to spin qubit implementations. A current dip is observed around zero magnetic field, in agreement with the expected behavior for the case of strong spin-orbit. We deduce an intradot spin relaxation rate $\approx$120\,kHz for the first holes, an important step towards a robust hole spin-orbit qubit

La "Zone minéralisée de l'Entre-deux-Mers" : Caractérisation hydrogéologique, géochimique et isotopique - CARISMEAU 2.

Au nord du Bassin Adour-Garonne, la ressource en eau principalement exploitée pour l'alimentation en eau potable est l'aquifère Eocène (masse d'eau 5071). Le projet de recherche CARISMEAU 2, initié début 2009 s'inscrit étroitement dans le cadre de la Directive Cadre sur l'Eau. Il vise à mieux comprendre les hétérogénéités et les interconnections au sein de la masse d'eau 5071. En effet, cet aquifère présente des teneurs anomaliques en sulfates et fluor qui induisent des difficultés d'exploitation de la ressource. L'origine de ces minéralisations excessives, réparties de façon hétérogène, n'est pas encore connue. Le projet CARISMEAU 2, auquel est associée la thèse " Zone minéralisée de l'Entre-deux-Mers ", met en application une approche couplée hydrogéologique, géochimique et isotopique. Les objectifs sont de mieux connaître l'origine de la salinité et de définir les circulations de ces eaux minéralisées dans l'aquifère Eocène, lui-même compris au sein du système aquifère multicouche du Bassin aquitain. Afin de mieux caractériser cette masse d'eau, une cinquantaine de points ont été suivis fin 2009. Des méthodes de géochimie et de géochimie isotopique classiques sont utilisées, mais aussi des méthodes isotopiques innovantes et/ou expérimentales. Les premiers résultats des analyses géochimiques et multi-isotopiques sont présentés dans l'objectif de mieux comprendre l'origine de ces éléments, leur comportement et leur migration dans les aquifères

Dementia, infections and vaccines: 30 years of controversy

This paper reports the proceedings of a virtual meeting convened by the European Interdisciplinary Council on Ageing (EICA), to discuss the involvement of infectious disorders in the pathogenesis of dementia and neurological disorders leading to dementia. We recap how our view of the infectious etiology of dementia has changed over the last 30 years in light of emerging evidence, and we present evidence in support of the implication of infection in dementia, notably Alzheimer’s disease (AD). The bacteria and viruses thought to be responsible for neuroinflammation and neurological damage are reviewed. We then review the genetic basis for neuroinflammation and dementia, highlighting the genes that are currently the focus of investigation as potential targets for therapy. Next, we describe the antimicrobial hypothesis of dementia, notably the intriguing possibility that amyloid beta may itself possess antimicrobial properties. We further describe the clinical relevance of the gut–brain axis in dementia, the mechanisms by which infection can move from the intestine to the brain, and recent findings regarding dysbiosis patterns in patients with AD. We review the involvement of specific pathogens in neurological disorders, i.e. SARS-CoV-2, human immunodeficiency virus (HIV), herpes simplex virus type 1 (HSV1), and influenza. Finally, we look at the role of vaccination to prevent dementia. In conclusion, there is a large body of evidence supporting the involvement of various infectious pathogens in the pathogenesis of dementia, but large-scale studies with long-term follow-up are needed to elucidate the role that infection may play, especially before subclinical or clinical disease is present

Microbial and diagenetic steps leading to the mineralisation of Great Salt Lake microbialites.

12 pagesInternational audienceMicrobialites are widespread in modern and fossil hypersaline environments, where they provide a unique sedimentary archive. Authigenic mineral precipitation in modern microbialites results from a complex interplay between microbial metabolisms, organic matrices and environmental parameters. Here, we combined mineralogical and microscopic analyses with measurements of metabolic activity in order to characterise the mineralisation of microbial mats forming microbialites in the Great Salt Lake (Utah, USA). Our results show that the mineralisation process takes place in three steps progressing along geochemical gradients produced through microbial activity. First, a poorly crystallized Mg-Si phase precipitates on alveolar extracellular organic matrix due to a rise of the pH in the zone of active oxygenic photosynthesis. Second, aragonite patches nucleate in close proximity to sulfate reduction hotspots, as a result of the degradation of cyanobacteria and extracellular organic matrix mediated by, among others, sulfate reducing bacteria. A final step consists of partial replacement of aragonite by dolomite, possibly in neutral to slightly acidic porewater. This might occur due to dissolution-precipitation reactions when the most recalcitrant part of the organic matrix is degraded. The mineralisation pathways proposed here provide pivotal insight for the interpretation of microbial processes in past hypersaline environments

Toward the sustainable use of groundwater springs: A case study from Namibia

-The water supply in drylands mainly relies on groundwater, making it a crucial resource. Springs in southern Africa are often underutilized, and are neither protected nor monitored. Thus, the aim of this study was to evaluate their quality in a sample area in northwestern Namibia and to propose solutions for the sustainable use of springs. In total, 35 springs and hot springs were evaluated in the study area located in the drier part of Namibia (Pmean = 150–400 mm/year), an area highly impacted by ongoing climate change with longer and more frequent drought seasons. The springs there are mostly uncaptured and the discharge is in the form of surface runoff, which is mainly lost to the atmosphere by evaporation. Most of the studied springs were perennial, despite a severe drought period. Local communities rely on the springs mainly for livestock and human consumption, as well as for irrigation. However, 71% of the springs do not have any protective measures. The temperature, pH, conductivity and alkalinity were tested in situ. In total, 20 samples were collected and analyzed for major ions (boron, fluoride, silica and strontium) and total dissolved solids (TDS). The physical and inorganic results mostly indicated good and excellent quality water for human consumption, while the hot springs tended to have poor water quality in terms of Namibian standards, indicating that the water was not fit for human consumption