Approche hydrogéochimique et structurale des circulations dans un réservoir du domaine alpin (massif d'Allevard, France)

Les caractéristiques hydrogéochimiques des réservoirs profonds du domaine alpin occidental sont abordées par le biais du système hydrominéral d'Allevard (France). Le volume des données et la variabilité des caractéristiques qui en découle, permettent de considérer cette source comme un exemple représentatif des sources thermominérales du domaine alpin occidental. L'étude combinée de ces données relatives à l'hydrochimie, à la géochimie isotopique, à la présence de gaz et d'éléments traces, confrontées au contexte fissural et structural des réservoirs, permet une approche cohérente des circulations profondes.On propose en conclusion un modèle qui pourrait être généralisé aux systèmes thermominéraux situés dans un contexte structural comparable (front de chevauchement des massifs cristallins externes; front de chevauchement briançonnais) et présentant un faciès semblable (eaux chloro-sulfatées). Ce modèle tient compte de mélanges entre eaux d'origine superficielle et/ou semi-profondes et d'eaux d'origine profonde.Investigations of the hydrogeochemical and structural characteristics of groundwater flows in an Alpine hydrothermal reservoir (Allevard Massif, French Western Alps) are carried out in order to define the origin and genesis of thermal and mineral waters.The geological formations constituting the Allevard Massif consist of a Hercynian basement and a continuous sedimentary cover from Carboniferous to Middle Jurassic. The basement is composed mainly of micaschists, the sedimentary cover of Paleozoic clastic deposits : Triassic formations (evaporites, dolomites, limestones); Liassic calcareous marls, schistics marls and Limestones. A groundwater outlet (Allevard Spring) from this reservoir is located in the calcareous terrains of Lias.The basement-cover contact is a major N40 subvertical fault. Faulting tectonics and subsequent rock fracturing is important for the hydrogeology of the area under study since the geological formations are initially impermeable (except for the Triassic terrains). Observations of underground galleries in the neighbourhood of the spring showed the presence of water outflows located on N40 strike-slip faults affecting both the basement and the Liassic terrains. The role of faulting tectonics in groundwater occurrence is indeed clearly emphasized by the position of the Allevard Spring at the intersection of two major faults with N60 and N140 trends.Available data cover nearly a hundred years (1888-1930) and emphasize the great variability of the chemical features of the spring water. This is related to the tact that the water outflowing from the spring is a mixture in varying proportions of waters from different sources. Combined interpretation of the structural characteristics, isotopical (3H; 18O; 2H; 34S) and chemico-physical (major and trace elements, gases, temperature, ...) data provides the basis of a working assumption on a flow and mixing model in which three different hydrogeological subsystems were distinguished : a surface subsystem comprising cold infiltration waters of a bicarbonate-calcium and a sulfate-calcium type; a subsurface subsystem constituted by the fissured Liassic calcareous terrains comprising part of the infiltrated waters which intermingle with much warmer waters of a sodium-chloride type originating from a subsystem located at a great depth. By means of geochemical indicators, a depth of nearly 4000 m has been estimated.Such a model, in agreement with geological evidence and reported by some recent works showing that halite deposits are probable at great depths, could be generalized to other hydrothermal systems occurring within the framework of the French Western Alps in a comparable structural context (thrust front of the external metamorphic massifs; "Briançonnais" thrust front)

Contamination nitratée des eaux souterraines d'un bassin versant agricole hétérogène: 1. Évaluation des apports à la nappe (modèle Agriflux)

Au cours des dernières décennies, la hausse de la productivité agricole s'est accompagnée d'une forte augmentation des fertilisations azotées qui a entraîné l'augmentation des concentrations en nitrates dans les eaux souterraines. Récemment, les études sur la gestion des pollutions diffuses agricoles ont intégré l'échelle du bassin versant hydrologique. Dans cet article, une approche basée sur un découpage en secteurs pédologiquement et agronomiquement homogènes a été élaborée pour permettre l'utilisation d'un modèle d'évaluation (AgriFlux), et obtenir les flux d'eau et de nitrates sortant de la zone racinaire sur l'ensemble d'un bassin. La modélisation du bassin de La Jannerie a porté sur une période de quatre ans impliquant 19 zones de simulation. L'influence du cycle végétatif des cultures et leur nature sur l'évolution des flux de nitrates a été mise en évidence par des simulations préliminaires, de même que l'influence du type de sol. L'évolution des concentrations moyennes saisonnières en nitrates sortant de la zone racinaire montre que les fertilisations minérales ne sont pas les seules sources importantes de nitrates dans les sols. Les pratiques culturales, comme le retournement des prairies, l'enfouissement des résidus de récoltes ou l'assolement, ont une forte influence sur la dynamique spatiale et temporelle des flux de nitrates percolant vers la nappe.In agricultural regions, groundwater contamination by nitrogen compounds originating from fertilizers is one of the most significant environmental problems. Along with in situ monitoring, simulation models have been developed for non point pollution (nitrates, pesticides) in order to evaluate both the level and the extent of the contamination. Simulation models, originally intended for research purposes in relation to the dynamics of agricultural systems, have been adapted and applied to environmental management in order to quantify water volumes and contaminant masses likely to reach groundwater systems. Recently, mechanistic models such as Agriflux (Banton et al., 1993) have been developed for use in the field. Agriflux is based on a mechanistic approach to the processes and incorporates a stochastic analysis that takes into account the spatial variability of the parameters. lt. calculates nitrate concentrations as well as water fluxes in the unsaturated zone. In the present study, environmental management principles integrating heterogeneity in soils and agricultural practices were applied to an agricultural watershed in Poitou (France). Preliminary simulations were carried out in order to estimate the influence of various parameters on the nitrate and water fluxes. First, a three-year wheat mono-crop was simulated using the same fertilization rate for each year. The calculated nitrate concentrations follow a trend opposite to that of the seasonal growing crop. To estimate the influence of the soil characteristics on the nitrate concentrations, the four types of soil in the watershed were simulated using the same three-year crop rotation. The results show that the soil type directly influences the amount of nitrate leaching. Under different soils types, the evolution of the concentrations over time follows the same pattern, but the concentration levels are significantly different. To quantify the impact of crops on the nitrate concentrations, the main crop rotations were simulated for the same type of soil. This set of simulations underlines the environmental differences between winter and spring crops. lt. also shows the differences induced by the presence of residues. The La Jannerie watershed was divided into homogeneous zones for soil and crop characteristics. During a four-year period, seasonal and annual nitrate concentrations were calculated for each homogeneous zone from the daily water and nitrate fluxes simulated with Agriflux. The results demonstrate the influence of the agricultural practices on the calculated concentrations. Overall, nitrate levels remain quasi-constant during the periods when the crops are active but vary considerably during the winter when the crops are absent or inactive. This winter period corresponds to a peak in nitrate leaching because of the excess rainfall and the absence of nitrogen uptake by the plants. The incorporation of crop residues in the soil in the autumn generates a high production of nitrates during winter due to the mineralization of the organic nitrogen.Two different environmental approaches can be used jointly to evaluate agricultural practices. The first consists of a comparison between the nitrate flux that can reach the saturated area and the fertilizer rate. This approach provides an estimate of the amount of nitrogen lost to the aquifer. Simulations with Agriflux show that the nitrate fluxes are highest during the autumn when plant uptake is non-existent, except in fields with winter crops. The second approach compares the calculated nitrate concentrations that may occur in the aquifer with recognized water quality criteria. lt. is interesting and important to note that, during the simulated period, the calculated concentrations in the leach were often much lower than the water quality criterion (50 mg NO3/L). This result indicates that the fertilization practices applied in the watershed during this period tended to approach the real crop requirements (minimal requirements) and were more environmentally adequate (environmental optimum) than those used previously

Parades, parties and pests: contradictions of everyday life in peacekeeping economies

Based on research studies conducted in the UN peacekeeping mission in Liberia in 2006, 2012 and 2013, this article argues that peacekeepers’ everyday experiences reflect a series of contradictory identities and performances with regard to nation, work and gender. Peacekeepers straddle paradoxical worlds simultaneously and manage oppositional demands and obligations, although it is often assumed that they inhabit peacekeeping economies in homogenous ways. Importantly, the experiences provide opportunities for peacekeepers to invest in, accumulate and deploy military capital; to consolidate their military identities; and to favourably and tactically position themselves as deserving and useful subjects within the peacekeeping landscape

Diagnostic yield of fine needle aspiration biopsy in HIV-infected adults with suspected mycobacterial lymphadenitis

Background. Fine needle aspiration biopsy (FNAB) has been shown to be the diagnostic procedure of choice for superficial lymphadenitis in tuberculosis endemic regions.Methods. We conducted a retrospective laboratory-based study to determine the bacteriological yield of clinically suspected mycobacterial tuberculous lymphadenitis following FNAB in adults, and specifically HIV-positive patients, to determine the need for the introduction of automated nucleic acid amplification tests (NAATs) such as the Xpert MTB/RIF assay as the initial diagnostic modality. Results. A diagnostic yield of 80% was achieved, significantly higher in HIV-positive v. HIV-negative patients (84% v. 52%, respectively; p<0.001). Conclusion. The results justify using automated NAATs such as the Xpert MTB/RIF assay as the initial diagnostic modality to expedite management in HIV-infected patients. 

Retelling racialized violence, remaking white innocence: the politics of interlocking oppressions in transgender day of remembrance

Transgender Day of Remembrance has become a significant political event among those resisting violence against gender-variant persons. Commemorated in more than 250 locations worldwide, this day honors individuals who were killed due to anti-transgender hatred or prejudice. However, by focusing on transphobia as the definitive cause of violence, this ritual potentially obscures the ways in which hierarchies of race, class, and sexuality constitute such acts. Taking the Transgender Day of Remembrance/Remembering Our Dead project as a case study for considering the politics of memorialization, as well as tracing the narrative history of the Fred F. C. Martinez murder case in Colorado, the author argues that deracialized accounts of violence produce seemingly innocent White witnesses who can consume these spectacles of domination without confronting their own complicity in such acts. The author suggests that remembrance practices require critical rethinking if we are to confront violence in more effective ways. Description from publisher's site: http://caliber.ucpress.net/doi/abs/10.1525/srsp.2008.5.1.2

The initial impact of the COVID-19 pandemic on the diagnosis of new cancers at a large pathology laboratory in the public health sector, Western Cape Province, South Africa

Background. The COVID-19 pandemic has disrupted cancer diagnostic services. A decline in the number of new cancers being diagnosed over a relatively short term implies a delay in diagnosis and subsequent treatment. This delay is expected to have a negative effect on cancerrelated morbidity and mortality. The impact of the pandemic on the number of new cancer diagnoses in our setting is unknown.Objectives. To assess the impact of COVID-19 on the number of new cancers diagnosed at our institution in the first 3 months following the implementation of lockdown restrictions, by focusing on common non-cutaneous cancers.Methods. A retrospective laboratory-based audit was performed at a large anatomical pathology laboratory in Western Cape Province, South Africa. The numbers of new diagnoses for six common cancers (breast, prostate, cervix, large bowel, oesophagus and stomach) from 1 April 2020 to 30 June 2020 were compared with the corresponding period in 2019.Results. Histopathological diagnoses for the six cancers combined decreased by 193 (–36.3%), from 532 new cases in the 2019 study period to 339 in the corresponding period in 2020. Substantial declines were seen for prostate (–58.2%), oesophageal (–44.1%), breast (–32.9%), gastric (–32.6%) and colorectal cancer (–29.2%). The smallest decline was seen in cervical cancer (–7%). New breast cancers diagnosed by cytopathology declined by 61.1%.Conclusions. The first wave of the COVID-19 pandemic and the associated response resulted in a substantial decline in the number of new cancer diagnoses, implying a delay in diagnosis. Cancer-related morbidity and mortality is expected to rise as a result, with the greatest increase in mortality expected from breast and colorectal cancer

"It's making contacts" : notions of social capital and implications for widening access to medical education

Acknowledgements Our thanks to the Medical Schools Council (MSC) of the UK for funding Study A; REACH Scotland for funding Study B; and Queen Mary University of London, and to the medical school applicants and students who gave their time to be interviewed. Our thanks also to Dr Sean Zhou and Dr Sally Curtis, and Manjul Medhi, for their help with data collection for studies A and B respectively. Our thanks also to Dr Lara Varpio, Uniformed Services University of the USA, for her advice and guidance on collating data sets and her comments on the draft manuscript.Peer reviewedPublisher PD