How informative are single well tracing experiments? : an assessment using Bayesian evidential learning

ATHEN

Heat as a proxy to image dynamic processes with 4D electrical resistivity tomography

Since salt cannot always be used as a geophysical tracer (because it may pollute the aquifer with the mass that is necessary to induce a geophysical contrast), and since in many contaminated aquifer salts (e.g., chloride) already constitute the main contaminants, another geophysical tracer is needed to force a contrast in the subsurface that can be detected from surface geophysical measurements. In this context, we used heat as a proxy to image and monitor groundwater flow and solute transport in a shallow alluvial aquifer (< 10 m deep) with the help of electrical resistivity tomography (ERT). The goal of our study is to demonstrate the feasibility of such methodology in the context of the validation of the efficiency of a hydraulic barrier that confines a chloride contamination to its source. To do so, we combined a heat tracer push/pull test with time-lapse 3D ERT and classical hydrogeological measurements in wells and piezometers. Our results show that heat can be an excellent salt substitution tracer for geophysical monitoring studies, both qualitatively and semi-quantitatively. Our methodology, based on 3D surface ERT, allows to visually prove that a hydraulic barrier works efficiently and could be used as an assessment of such installations

Assessment of short-term aquifer thermal energy storage for demand-side management perspectives : experimental and numerical developments

In the context of demand-side management and geothermal energy production, our proposal is to store thermal energy in shallow alluvial aquifers at shorter frequencies than classical seasonal aquifer thermal energy storage. We first conducted a one-week experiment in a shallow alluvial aquifer, which is characterized by a slow ambient groundwater flow, to assess its potential for thermal energy storage and recovery. This experiment has shown that up to 90% of the stored thermal energy can be recovered and would therefore suggest that aquifer thermal energy storage could be considered for demand-side management applications. We then conceptualized, developed, and calibrated a deterministic 3D groundwater flow and heat transport numerical model representing our study site, and we simulated 77 different scenarios to further assess this potential. This has allowed us to demonstrate that low-temperature aquifer thermal energy storage (temperature differences of −4 K for precooling and 3, 6, and 11 K for preheating) is efficient with energy recovery rates ranging from 78 to 87%, in a single aquifer thermal energy storage cycle. High-temperature aquifer thermal energy storage (temperature differences between 35 and 65 K) presents lower energy recovery rates, from 53 to 71%, with all other parameters remaining equals. Energy recovery rates decrease with increasing storage duration and this decrease is faster for higher temperatures. Retrieving directly useful heat (without upgrading with a groundwater heat pump) using only a single storage and recovery cycle appears to be complicated. Nevertheless, there is room for aquifer thermal energy storage optimization in space and time with regard to improving both the energy recovery rates and the recovered absolute temperatures

Neutralizing anti-Tat antibodies prolonged HAART interruption in vaccines in a prospective structured interruption study

Anti-Tat therapeutic vaccination has been clinically investigated by different groups [1-4], given that 1) extracellular Tat protein induces T cell apoptosis and cellular immune suppression, 2) epidemiological data showed that LTNP exhibit high level of serum anti-Tat Ab, negatively correlated with p24 antigenemia, 3) in Tat immunized macaques, viremia decreased following SHIV challenge. Anti-Tat therapeutic vaccination using Tat Toxoid adjuvanted either with Seppic [1,2] or with alum or DcChol (Aventis Pasteur) proved to be safe. A prospective structured treatment interruption study (STI) monitored according to EU guidelines was conducted at Hospital St-Pierre, Brussels (Pr. N. Clumeck) on 31 vaccinees who received a DcChol adjuvanted Tat Toxoid (n = 12), a DcChol placebo (n = 8) or non adjuvanted Tat toxoid (n = 11). The 2 year study follow-up showed that vaccinees developing high titer of Abs neutralizing Tat bioactivity prolonged HAART-interruption.info:eu-repo/semantics/publishedOral presentation. From 2006 International Meeting of The Institute of Human VirologyBaltimore, USA. 17–21 November, 200