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In Chad, hard-rock aquifers are the main source of drinking water for the population located on basement areas. In these basement aquifers, and in particular those of the Guéra region, water drilling failure rates remain high despite research on one- and two-dimensional electrical resistivity techniques and lineaments as a means to improve access to the resource, mainly because these techniques are only used on an observational and structural basis to locate fractures. This study combines electrical resistivity tomography (ERT) with geology, hydrogeology and geomorphology, in order to characterise the structure and geometry of the aquifer system, assess borehole productivity and determine the factors controlling it. After validating the large dataset and its representativeness, 315 high- and low-yield wells, of which 41 have complete geophysical datasets, were selected. This large dataset allows a multi-parameter approach to (1) better characterise each facies according to its electrical resistivity and (2) clearly identify the main formations constituting the local conceptual hydrogeological model. The most suitable areas for productive boreholes are characterised by the presence of an overburden of <20 m depth, well-developed weathered and fractured horizons of granites and biotite granites (preferably) containing little or no clay, and a nearby drainage network. The most substantial flow rates are found in the first 30 m of the fissured horizon, below the base of the alterites. The experience gained from the present study will guide future analysis of ERT sections in order to reduce the probability of drilling dry wells. [ABSTRACT FROM AUTHOR]

Abstract: Karst aquifers display a range of geologic and geomorphic characteristics in a wide range of climatic and land-use settings; identification of transport dynamics representative of karst aquifers in general could help advance our understanding of these complex systems. To this end, nutrient, turbidity, and major ion dynamics in response to storms were compared at multiple sites in two karst aquifers with contrasting characteristics and settings: the Chalk aquifer (Eure Department, Normandy, France) and the Barton Springs segment of the Edwards Aquifer (Texas, U.S.A.). The Chalk aquifer is typified by high matrix porosity, thick surficial deposits (up to 30 m thick), and agricultural land use; the Barton Springs segment is typified by low matrix porosity, outcropping limestone, and urban land use. Following one to three storms, from 5 to 16 samples from springs and wells were analyzed for major ions, and specific conductance and turbidity were monitored continuously. Comparison of the chemographs indicated some generalized responses, including an increase in turbidity and potassium concentrations and a decrease in major ion and nitrate concentrations with infiltrating storm runoff. Factor analysis of major ions and turbidity revealed strikingly similar behavior of the chemical variables for the two aquifers: The first two factors, explaining more than 75% of the variability, illustrate that dynamics of most major ions (including nitrate) are opposed to those of turbidity and of potassium. The results demonstrate that potassium and nitrate are effective tracers of infiltrating storm runoff and resident ground water, respectively, and the similar results for these two highly contrasting aquifers suggest that the dynamics identified might be applicable to karst systems in general. [Copyright &y& Elsevier]

Background and Aim: Fatty infiltration and fibrosis are major issues in chronic liver disease. Recent reports suggest a role for the endocannabinoid system in these processes. Aim: To characterize localization and expression of CB2 in normal liver and nonalcoholic fatty liver. Methods: We studied 64 liver biopsies: eight were considered normal; 56 had a diagnosis of nonalcoholic fatty liver disease (NAFLD); 32 with nonalcoholic steatosis and 24 nonalcoholic steatohepatitis (NASH). CB2 immunolocalization was studied in 38 samples in paraffin blocks using immunohistochemistry, and a computerized semiquantitative analysis was carried out. CB2 mRNA expression was assessed through RT-PCR in 26 frozen liver samples and the ratio CB2/β-actin was used to evaluate differences between groups. Statistical analysis was performed with central tendency measures and the Mann–Whitney U-test. We considered as significant differences those with a P-value <0.05. Results: Neither parenchymal nor nonparenchymal cells in normal liver tissue react towards anti-CB2 antibodies. All the samples from patients with steatosis and nonalcoholic steatohepatitis showed hepatocellular immunoreactivity. Cholangiocytes were positive only in the NAFLD group. Normal liver tissue showed a normalized CB2/β-actin ratio of 0.001±0.01, steatosis 6.52±17.3 ( P=0.05 vs normal) and NASH 6.49±12.2 ( P=0.06 vs normal and P=0.6 vs steatosis). Conclusion: CB2 receptors are expressed by hepatocytes in nonalcoholic fatty liver disease but not in normal liver. [ABSTRACT FROM AUTHOR]

Karst aquifers are known for their wide distribution of water transfer velocities. From this observation, a multiple geochemical tracer approach seems to be particularly well suited to provide a significant assessment of groundwater flows, but the choice of adapted tracers is essential. In this study, several common tracers in karst aquifers such as physicochemical parameters, major ions, stable isotopes, and δ 13 C to more specific tracers such as dating tracers – 14 C, 3 H, 3 H– 3 He, CFC-12, SF 6 and 85 Kr, and 39 Ar – were used, in a fractured karstic carbonated aquifer located in Burgundy (France). The information carried by each tracer and the best sampling strategy are compared on the basis of geochemical monitoring done during several recharge events and over longer time periods (months to years). This study’s results demonstrate that at the seasonal and recharge event time scale, the variability of concentrations is low for most tracers due to the broad spectrum of groundwater mixings. The tracers used traditionally for the study of karst aquifers, i.e., physicochemical parameters and major ions, efficiently describe hydrological processes such as the direct and differed recharge, but require being monitored at short time steps during recharge events to be maximized. From stable isotopes, tritium, and Cl − contents, the proportion of the fast direct recharge by the largest porosity was estimated using a binary mixing model. The use of tracers such as CFC-12, SF 6 , and 85 Kr in karst aquifers provides additional information, notably an estimation of apparent age, but they require good preliminary knowledge of the karst system to interpret the results suitably. The CFC-12 and SF 6 methods efficiently determine the apparent age of baseflow, but it is preferable to sample the groundwater during the recharge event. Furthermore, these methods are based on different assumptions such as regional enrichment in atmospheric SF 6 , excess air, and flow models among others. 85 Kr and 39 Ar concentrations can potentially provide a more direct estimation of groundwater residence time. Conversely, the 3 H– 3 He method is inefficient in the karst aquifer for dating due to 3 He degassing. [ABSTRACT FROM AUTHOR]

The article presents abstracts of various studies on hernia care which includes component separation technique in large incisional abdominal hernia repair, reconstruction of abdominal wall in recurrent hernias and components separattion technique in the management of large ventral hernias. [ABSTRACT FROM AUTHOR]

Summary: In many places throughout the world, drinking water is frequently contaminated by turbidity. Such turbidity, however, as representative of particle transport, can be used as to trace certain features of particle transport properties. In order to investigate the relation between particle and dissolved species transport and hydrodynamics in karst systems, correlation and spectral analyses were performed on time series of rainfall (input signal), and water level, specific conductance, and turbidity (output signals) at a karst spring system in the chalk aquifer of the lower Seine valley, France. This system is composed of a spring connected to a sinkhole on the chalk plateau where a small creek enters the subsurface. The autocorrelation functions for water level and turbidity showed a short memory effect, demonstrating the short duration of the influence of flood events on these two parameters, whereas specific conductance (representing less-mineralized storm-derived water) had a much longer memory effect. These results were interpreted as reflecting the rapid reactivity of the spring to rain events, with storage of water in the fissured chalk explaining the longer memory effect for specific conductance than for particles. Energy spectra computed by fast Fourier transform of autocorrelation functions showed a strong structure in the output signals, whereas the input signal (rainfall) was random, thus allowing assessment and comparison of system behaviour regarding dissolved and solid transport, as well as hydraulics. Cross-correlation functions (which allow an assessment of impulse response functions) confirmed the low inertia of the system for water level and turbidity and the much higher inertia for specific conductance. In addition to the main peak, two secondary peaks in the cross-correlation functions suggest the existence of additional flowpaths that might involve the contribution of other point-source recharge and/or delayed infiltration through the clayey surficial formation and solution pipes, which could act as epikarst. Analysis using continuous wavelet spectra allowed a better investigation of the rainfall signal structure and highlighted a strong relationship between turbidity and rainfall, which could not be deduced from the energy spectra. Specific spectral components in water level were isolated and a time-domain reconstruction using inverse wavelet transform allowed separation of quick-flow and slow-flow components. [Copyright &y& Elsevier]