Détermination de la structure tectonique de l'aquifère crayeux du littoral Nord Pas-de-Calais par prospection géophysique couplée à des observations par forage. Conséquence sur la répartition d'eau salée

Sur le littoral du Nord - Pas-de-Calais (France), la Craie d'âge Crétacé supérieur constitue l'aquifère le plus exploité régionalement pour l'alimentation en eau tant potable qu'industrielle. Sur la frange la plus littorale, l'aquifère crayeux, semi-captif est affecté par de nombreuses failles. Dans certains secteurs, la profondeur de la craie et la localisation des failles, restent aléatoires suite au manque de forages et d'affleurements. Afin de palier à ces lacunes, trois méthodes géophysiques (sondages électriques et sismiques, profilage électromagnétique) ont été appliquées.La synthèse des données obtenues a permis de démontrer que la craie est découpée en une série de compartiments par des accidents tectoniques présentant un affaissement vers le Sud et vers l'Ouest. L'interprétation des données géophysiques a également permis d'obtenir des informations sur la répartition de l'interface eau douce - eau salée au sein de l'aquifère crayeux.Dans la région, le concept classique de biseau salé ne permet pas d'expliquer l'irrégularité spatiale des intrusions. L'étude semble démontrer que la répartition et l'extension des intrusions d'eau salée peuvent être corrélées avec la localisation des accidents tectoniques, les intrusions les plus éloignées du rivage se faisant au droit des zones faillées.Ceci amène à proposer une nouvelle approche concernant l'extension des intrusions d'eau salée : elles seraient directement tributaires de la géométrie et des caractéristiques hydrodynamiques de l'aquifère crayeux, ces dernières étant fortement influencées par la présence des failles.Along the North Pas-de-Calais coast between a point south of Boutonnière du Boulonnais and the Authie River, Cretaceous rocks are limited to the east by a paleocliff that overlooks the Quaternary coastal and dune deposits. The chalk aquifer is connected to the Quaternary aquifers and further west to the sea water. Close to the seashore the top of the chalk plateau falls rapidly from 20 m above sea level to 20 m below sea level, causing the aquifer to grade from being unconfined in the east to confined in the west. This chalky aquifer is cut by several faults. A structural survey (LOUCHE et al., 1997) based on borehole data was carried out to evaluate whether the rate and direction of groundwater flow are controlled by the different faults. Two major fault groups striking N030° and N110° have been revealed by the structural map, with a third minor group (N 160- 170°) to the north of the Canche. The two major groups, created during tectonic activity from the Palaeozoic to the present, are composed respectively of structures with general faulting directions of N 100-110° and N 020-040°, previously described by COLBEAUX et al. (1993). Chalk depth and fault location are unknown in certain areas due to the lack of bore holes and outcrops. With the aim of overcoming these deficiencies, three traditional geophysical techniques (electrical sounding, seismic logging and electromagnetic profiling) were carried out between the Canche and Authie rivers in the coastal area, west of the chalky cliffs.The interpretation of the geophysical results allows us to confirm the presence of previously located faults and identify new ones in the area where the chalk is overlain by Quaternary cover. The chalky aquifer is hence divided by the faults into a series of compartments that are inclined to the south or to the west. In addition, anomalies have been recorded in the fresh water - salt water interface on the Picardy continental shelf (MERCIER & BACROT, 1990). These anomalous zones are aligned along the northern extension of the sub N-S faults proposed by MENNESSIER & BEUN (1980), located a few kilometres to the south. Based on indirect evidence, these latter authors interpreted these faults as being responsible for considerable displacement of a major part of the Quaternary deposits. Given the lack of direct observations on salt-water distribution, geophysical results, and more specifically the electrical soundings, are required to provide supplementary information in order to better understand this phenomenon. Furthermore, the study of the salt water location, using electrical soundings, points out the juxtaposition of deep saline intrusions, demonstrating that the concept of a homogeneous wedge-shaped body parallel to the seashore can no longer be used to describe this chalky aquifer.In the Bas-Champs area, electromagnetic profiling and three electrical soundings provided additional information on the relation between tectonic events and saline water intrusion (Fig. 3). The electromagnetic profiling shows the presence of two faults (Fig. 6). The vertical faults have an apparent low electrical resistivity (2.5 Ω.m) indicating the presence of brackish or salt water. Electrical sounding carried out to the south of the electromagnetic profile (SE9) shows a decrease in the electrical resistivity from 12.5 m depth, also confirming the presence of salt water. The results of an electrical sounding located to the north of the electromagnetic profile (SE10) show that the ground is saturated with fresh water up to at least 27.2 m (resistivity of 90 Ω.m). At 1 km distance, there is a juxtaposition of three sectors separated by faults filled up with salt water. However, an electrical sounding (SE2, Fig. 2) located near the sea showed that the ground is saturated with fresh water up to at least 52.7 m deep.Using geological, hydrogeological and geophysical data correlations, between structural context and saltwater intrusion could be established and a new hypothesis for saltwater intrusion for this study area could be proposed. Intrusion is directly dependent on the geometry and the hydrodynamic characteristics of the chalky aquifer, as reflected by its heterogeneous nature.Salt water seems to follow preferential intrusion directions corresponding to faults rather than the classic model of a salt wedge. These results suggest the hypothesis that the seawater intrusion distribution relates to the tectonic configuration of the aquifer. The chalky series is cut into hydrogeological compartments individualised by tectonic accidents, which are preferential axes for sea intrusion. The presence of a saltwater front located far from the coast, as indicated by electrical soundings, could be explained by the geological history of the maritime plain, where the Pleistocene and Holocene seas covered the maritime plain up to the fossil cliff (LOUCHE et al., 1998)

Elimination of turbidity and bacterial contamination in natural water sources (Ubangi river, Central Africa)

Having access to a natural source of water of sufficiently high quality for human consumption has become a strategic concern for the entire world. In fact, drinking water resources in developing countries are almost non-existent, as they are overused or polluted by intense human activity. Our study aims to develop a natural filter that reduces turbidity and eliminates human pathogens. The process developed should be inexpensive and minimize the use of chemical reagents, and should not be labor intensive. In this context, horizontal sand filtration that uses the natural process of water purification occurring in an aquifer can be regarded as the most suitable water treatment process for developing countries.Disposer d’une source d’eau naturelle de bonne qualité, pour la consommation humaine, est devenu maintenant une préoccupation stratégique pour le monde entier. En effet, les ressources en eaux potables dans les pays en voie de développement sont quasi-inexistantes, car surexploitées ou souillées par une activité humaine intense. L’étude que nous proposons a pour objectif : de mettre au point un filtre naturel qui diminue la turbidité et élimine les agents pathogènes pour l’homme. Le procédé développé peu onéreux devra réduire au maximum l’utilisation de réactifs chimiques, et minimiser toutes interventions humaines. La filtration horizontale sur sable qui utilise le processus naturel de purification de l’eau se produisant dans une nappe aquifère, peut être considéré comme le procédé de traitement de l’eau le plus approprié aux pays en voie de développement et répond aux objectifs fixés.Disponer de una fuente de agua natural de buena calidad, apta para el consumo humano, se ha convertido actualmente en una preocupación estratégica en todo el mundo. En efecto, los recursos de agua potable en los países en vías de desarrollo son prácticamente inexistentes, por exceso de explotación o por contaminación a causa de una actividad humana intensa.El estudio que proponemos tiene por objetivo: desarrollar un filtro natural que reduzca la turbidez y elimine los agentes patógenos perjudiciales para el hombre. El procedimiento desarrollado, de bajo coste, debería reducir al máximo el uso de sustancias químicas reactivas y minimizar cualquier intervención humana. Como la filtración horizontal sobre arena que utiliza el proceso natural de purificación del agua tiene lugar en una capa acuífera, se puede considerar como el procedimiento de tratamiento del agua más adecuado a los países en vías de desarrollo y responde a los objetivos fijados

Investigating the impact of remote neuroanatomy education during the COVID-19 pandemic using online examination performance in a National Undergraduate Neuroanatomy Competition

Neuroanatomy is a notoriously challenging subject for medical students to learn. Due to the coronavirus disease-19 (COVID-19) pandemic, anatomical education transitioned to an online format. We assessed student performance in, and attitudes toward, an online neuroanatomy assessment compared to an in-person equivalent, as a marker of the efficacy of remote neuroanatomy education. Participants in the National Undergraduate Neuroanatomy Competition (NUNC) 2021 undertook two online examinations: a neuroanatomically themed multiple-choice question paper and anatomy spotter. Students completed pre- and post-examination questionnaires to gauge their attitudes toward the online competition and prior experience of online anatomical teaching/assessment. To evaluate performance, we compared scores of students who sat the online (2021) and in-person (2017) examinations, using 12 identical neuroradiology questions present in both years. Forty-six percent of NUNC 2021 participants had taken an online anatomy examination in the previous 12?months, but this did not impact examination performance significantly (p?>?0.05). There was no significant difference in examination scores between in-person and online examinations using the 12 neuroradiology questions (p?=?0.69). Fifty percent of participants found the online format less enjoyable, with 63% citing significantly fewer networking opportunities. The online competition was less stressful for 55% of participants. This study provides some evidence to suggest that student performance is not affected when undertaking online examinations and proposes that online neuroanatomy teaching methods, particularly for neuroradiology, may be equally as effective as in-person approaches within this context. Participants perceived online examinations as less stressful but raised concerns surrounding the networking potential and enjoyment of online events.Peer reviewe

Performative Work: Bridging Performativity and Institutional Theory in the Responsible Investment Field

Callon’s performativity thesis has illuminated how economic theories and calculative devices shape markets, but has been challenged for its neglect of the organizational, institutional and political context. Our seven-year qualitative study of a large financial data company found that the company’s initial attempt to change the responsible investment field through a performative approach failed because of the constraints posed by field practices and organizational norms on the design of the calculative device. However, the company was subsequently able to put in place another form of performativity by attending to the normative and regulative associations of the device. We theorize this route to performativity by proposing the concept of performative work, which designates the necessary institutional work to enable translation and the subsequent adoption of the device. We conclude by considering the implications of performative work for the performativity and the institutional work literatures

The effect of age and unilateral leg immobilisation for 2 weeks on substrate ulilisation during moderate-intensity exercise in human skeletal muscle

Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate-intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two-legged isolated knee-extensor exercise at 20±1W(_50% maximalwork capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins.Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratoryquotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl-CoA carboxylase 2 and AMP-activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane-associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate exercise, but the whole-leg and molecular differences in fatty acid mobilization could explain the age- and immobilization-induced IMTG accumulation

Dendritic Cells Crosspresent Antigens from Live B16 Cells More Efficiently than from Apoptotic Cells and Protect from Melanoma in a Therapeutic Model

Dendritic cells (DC) are able to elicit anti-tumoral CD8+ T cell responses by cross-presenting exogenous antigens in association with major histocompatibility complex (MHC) class I molecules. Therefore they are crucial actors in cell-based cancer immunotherapy. Although apoptotic cells are usually considered to be the best source of antigens, live cells are also able to provide antigens for cross-presentation by DC. We have recently shown that prophylactic immunotherapy by DC after capture of antigens from live B16 melanoma cells induced strong CD8+ T-cell responses and protection against a lethal tumor challenge in vivo in C57Bl/6 mice. Here, we showed that DC cross-presenting antigens from live B16 cells can also inhibit melanoma lung dissemination in a therapeutic protocol in mice. DC were first incubated with live tumor cells for antigen uptake and processing, then purified and irradiated for safety prior to injection. This treatment induced stronger tumor-specific CD8+ T-cell responses than treatment by DC cross-presenting antigens from apoptotic cells. Apoptotic B16 cells induced more IL-10 secretion by DC than live B16 cells. They underwent strong native antigen degradation and led to the expression of fewer MHC class I/epitope complexes on the surface of DC than live cells. Therefore, the possibility to use live cells as sources of tumor antigens must be taken into account to improve the efficiency of cancer immunotherapy

Status and future development of Heating and Current Drive for the EU DEMO

The European DEMO is a pulsed device with pulse length of 2 hours. The functions devoted to the heating and current drive system are: plasma breakdown, plasma ramp-up to the flat-top where fusion reactions occur, the control of the plasma during the flat-top phase, and finally the plasma ramp-down. The EU-DEMO project was in a Pre-Concept Design Phase during 2014-2020, meaning that in some cases, the design values of the device and the precise requirements from the physics point of view were not yet frozen. A total of 130 MW was considered for the all phases of the plasma: in the flat top, 30 MW is required for neoclassical tearing modes (NTM) control, 30 MW for burn control, and 70 MW for the control of thermal instability (TI), without any specific functions requested from each system, Electron Cyclotron (EC), Ion Cyclotron (IC), or Neutral Beam (NB) Injection. At the beginning of 2020, a strategic decision was taken, to consider EC as the baseline for the next phase (in 2021 and beyond). R&D on IC and NB will be risk mitigation measures. In parallel with progresses in Physics modelling, a decision point on the heating strategy will be taken by 2024. This paper describes the status of the R&D development during the period 2014-2020. It assumes that the 3 systems EC, IC and NB will be needed. For integration studies, they are assumed to be implemented at a power level of at least 50 MW. This paper describes in detail the status reached by the EC, IC and NB at the end of 2020. It will be used in the future for further development of the baseline heating method EC, and serves as starting point to further develop IC and NB in areas needed for these systems to be considered for DEMO