3D geoelectrical monitoring to follow hydric soil behaviour during rainfall

RESUME Durant les dernières années, les méthodes électriques ont souvent été utilisées pour l'investigation des structures de subsurface. L'imagerie électrique (Electrical Resistivity Tomography, ERT) est une technique de prospection non-invasive et spatialement intégrée. La méthode ERT a subi des améliorations significatives avec le développement de nouveaux algorithmes d'inversion et le perfectionnement des techniques d'acquisition. La technologie multicanale et les ordinateurs de dernière génération permettent la collecte et le traitement de données en quelques heures. Les domaines d'application sont nombreux et divers: géologie et hydrogéologie, génie civil et géotechnique, archéologie et études environnementales. En particulier, les méthodes électriques sont souvent employées dans l'étude hydrologique de la zone vadose. Le but de ce travail est le développement d'un système de monitorage 3D automatique, non- invasif, fiable, peu coûteux, basé sur une technique multicanale et approprié pour suivre les variations de résistivité électrique dans le sous-sol lors d'événements pluvieux. En raison des limitations techniques et afin d'éviter toute perturbation physique dans la subsurface, ce dispositif de mesure emploie une installation non-conventionnelle, où toutes les électrodes de courant sont placées au bord de la zone d'étude. Le dispositif le plus approprié pour suivre les variations verticales et latérales de la résistivité électrique à partir d'une installation permanente a été choisi à l'aide de modélisations numériques. Les résultats démontrent que le dispositif pôle-dipôle offre une meilleure résolution que le dispositif pôle-pôle et plus apte à détecter les variations latérales et verticales de la résistivité électrique, et cela malgré la configuration non-conventionnelle des électrodes. Pour tester l'efficacité du système proposé, des données de terrain ont été collectées sur un site d'étude expérimental. La technique de monitorage utilisée permet de suivre le processus d'infiltration 3D pendant des événements pluvieux. Une bonne corrélation est observée entre les résultats de modélisation numérique et les données de terrain, confirmant par ailleurs que le dispositif pôle-dipôle offre une meilleure résolution que le dispositif pôle-pôle. La nouvelle technique de monitorage 3D de résistivité électrique permet de caractériser les zones d'écoulement préférentiel et de caractériser le rôle de la lithologie et de la pédologie de manière quantitative dans les processus hydrologiques responsables d'écoulement de crue. ABSTRACT During the last years, electrical methods were often used for the investigation of subsurface structures. Electrical resistivity tomography (ERT) has been reported to be a useful non-invasive and spatially integrative prospecting technique. The ERT method provides significant improvements, with the developments of new inversion algorithms, and the increasing efficiency of data collection techniques. Multichannel technology and powerful computers allow collecting and processing resistivity data within few hours. Application domains are numerous and varied: geology and hydrogeology, civil engineering and geotechnics, archaeology and environmental studies. In particular, electrical methods are commonly used in hydrological studies of the vadose zone. The aim of this study was to develop a multichannel, automatic, non-invasive, reliable and inexpensive 3D monitoring system designed to follow electrical resistivity variations in soil during rainfall. Because of technical limitations and in order to not disturb the subsurface, the proposed measurement device uses a non-conventional electrode set-up, where all the current electrodes are located near the edges of the survey grid. Using numerical modelling, the most appropriate arrays were selected to detect vertical and lateral variations of the electrical resistivity in the framework of a permanent surveying installation system. The results show that a pole-dipole array has a better resolution than a pole-pole array and can successfully follow vertical and lateral resistivity variations despite the non-conventional electrode configuration used. Field data are then collected at a test site to assess the efficiency of the proposed monitoring technique. The system allows following the 3D infiltration processes during a rainfall event. A good correlation between the results of numerical modelling and field data results can be observed since the field pole-dipole data give a better resolution image than the pole-pole data. The new device and technique makes it possible to better characterize the zones of preferential flow and to quantify the role of lithology and pedology in flood- generating hydrological processes.

Purification and activity standardisation of a (166m)Ho solution.

As part of a project to use the long-lived (T(1/2)=1200a) (166m)Ho as reference source in its reference ionisation chamber, IRA standardised a commercially acquired solution of this nuclide using the 4pibeta-gamma coincidence and 4pigamma (NaI) methods. The (166m)Ho solution supplied by Isotope Product Laboratories was measured to have about 5% Europium impurities (3% (154)Eu, 0.94% (152)Eu and 0.9% (155)Eu). Holmium had therefore to be separated from europium, and this was carried out by means of ion-exchange chromatography. The holmium fractions were collected without europium contamination: 162h long HPGe gamma measurements indicated no europium impurity (detection limits of 0.01% for (152)Eu and (154)Eu, and 0.03% for (155)Eu). The primary measurement of the purified (166m)Ho solution with the 4pi (PC) beta-gamma coincidence technique was carried out at three gamma energy settings: a window around the 184.4keV peak and gamma thresholds at 121.8 and 637.3keV. The results show very good self-consistency, and the activity concentration of the solution was evaluated to be 45.640+/-0.098kBq/g (0.21% with k=1). The activity concentration of this solution was also measured by integral counting with a well-type 5''x5'' NaI(Tl) detector and efficiencies computed by Monte Carlo simulations using the GEANT code. These measurements were mutually consistent, while the resulting weighted average of the 4pi NaI(Tl) method was found to agree within 0.15% with the result of the 4pibeta-gamma coincidence technique. An ampoule of this solution and the measured value of the concentration were submitted to the BIPM as a contribution to the Système International de Référence.

The threat of reintroduction of natural transmission of Chagas' disease in Bambuí, Minas Gerais state, Brazil, due to Panstrongylus megistus

In the Epidemiological Surveillance Program in the county of Bambuí, Minas Gerais, between August 1986 and December 1988, 154 Panstrongylus megistus were captured by the local population in both peridomicile and intradomicile environments. Fifteen (9.8%) of the P. megistus harboured Trypanosoma cruzi. Preciptin tests showed that the most frequent triatomine blood meal sources were birds, but other sources were dogs, men and cats. The isoenzyme characterization of 13 T. cruzi strains showed that six belonged to zymodeme Z1, corresponding to the wild parasites, and seven belonged to zymodeme Z2, corresponding to parasites isolated from chronic chagasic patients (domestic cycle). As P. megistus were found to be naturally infected by parasites from both cycles, they are cleary able to transmit T. cruzi from the wild cycle to the domestic cycle. Furthermore the capacity of P. megistus in colonizing houses was observed in one residence, vacant for several years, in wich 153 triatomines were captured. The data show the possibility of P. megistus reintroducing transmission of Chaga's disease in the county if Epidemiological Surveillance is interrupted.

Angiotensin-converting enzyme inhibitor versus calcium antagonist in the treatment of hypertension.

Sixteen patients with essential hypertension were treated for 2 consecutive 6-week periods with either the angiotensin-converting enzyme (ACE) inhibitor enalapril (20 mg once daily) or the calcium antagonist diltiazem (120 mg twice daily). The sequence of the treatment phases was randomly allocated. Blood pressure decreased from 154/102 +/- 5/2 mm Hg (mean +/- SEM) to 135/96 +/- 4/2 and 140/98 +/- 3/2 mm Hg during treatment with enalapril and diltiazem, respectively. It was impossible in the individual hypertensive patient to predict the long-term blood pressure response to one of the agents studied based on the long-term blood pressure response to the other agent.

Evaluation of a colorimetric Babesia bigemina-DNA probe within an epidemiological survey

An epidemiological survey was conducted in south east Mexico, in an effort to establish the serological reactivity and carrier status to Babesia bigemina of an indigenous cattle population. The prevalance was obtained through the Indirect Fluorescent Antibody Test (IFAT), using an in vitro culture-derived B. bigemina antigen. A specific, digoxigenin-coupled, ~6kb B. bigemina-DNA probe (BBDP), was used to indicate the presence of the parasite. Serum samples from 925 animals of all ages, were obtained within the three regions (I, II, III) of the state of Yucatan and tested by IFAT. In addition, whole blood samples draw from 136 of the same animals of region II were analyzed using the BBDP. Positive IFAT (IFAT+) reactions were observed in 531 sera for a 57% overall prevalence. Regional values were: I = 157 + (56%), II = 266 + (68%) and III = 108 + (42%). Only 32 (23%) of the blood samples tested with BBDP showed distinctive hybridization signal, in contrast with 100 (73%) IFAT + animals. The responses distribution for IFAT vs. BBDP was: +/+ 23, +/- 77, -/+ 9 and -/- 27 respectively. It was found that the analytical sinsitivity of BBDP appears to be low for its utilization is widespread epidemiological surveys. It was considered, however, that the colorimetric probe mifht to be useful to safely detect transmission prone carriers, since it is able to detect parasitemias as low as 0.001%.

Anàlisi de radiació en vaixells i disseny d'una antena en la banda d'HF

El projecte està dividit en dues parts, per una banda l’anàlisi de radiació en vaixells i per altra banda el disseny d’una antena en la banda d’ HF. La primera part s’inicia amb un estudi de l’escenari marítim a nivell de comunicacions, vaixells i antenes i, a continuació, s’estudia el camp proper sobre les superfícies del vaixell per al posicionament d’antenes amb el màxim aïllament. La segona part tracta el disseny d’una antena en HF a 6 MHz partint d’una antena tipus ranura, de baix perfil. Per validar el seu funcionament es construeix i mesura un prototipus en la banda d’UHF (2 GHz).

La reconnaissance des couples homosexuels. Enjeux juridiques, sociaux et religieux

Cet ouvrage propose de poser les questions éthiques que suscitent notamment l'instauration du PACS en France, le débat sur l'intégration des couples homosexuels dans les Eglises et plus largement l'évolution des moeurs en la matière. Fruit d'un colloque organisé par l'Institut romand d'éthique, cet ouvrage accueille des auteurs d'horizons et de nationalités divers, parmi lesquels on trouve notamment Dominique Fernandez et Irène Théry.

Higher arithmetic Chow groups

We give a new construction of higher arithmetic Chow groups for quasi-projective arithmetic varieties over a field. Our definition agrees with the higher arithmetic Chow groups defined by Goncharov for projective arithmetic varieties over a field. These groups are the analogue, in the Arakelov context, of the higher algebraic Chow groups defined by Bloch. The degree zero group agrees with the arithmetic Chow groups of Burgos. Our new construction is shown to be a contravariant functor and is endowed with a product structure, which is commutative and associative.

Total IgE and eotaxin (CCL11) contents in tears of patients suffering from seasonal allergic conjunctivitis.

BACKGROUND: To prospectively investigate patients with seasonal allergic conjunctivitis (SAC) during the pollen season and test associations between tears total IgE, eotaxin concentrations, and SAC severity. METHODS: Enrolled patients presented ocular symptoms and clinical signs of SAC at the time of presentation. Ocular itching, hyperaemia, chemosis, eyelid swelling, and tearing were scored, and the sum of these scores was defined as the clinical score. Conjunctival papillae were separately graded. We measured eotaxin concentration in tears by an enzyme-linked immunosorbent assay (ELISA) and total tear IgE by Lacrytest strip. RESULTS: Among thirty patients (30 eyes), 11 showed neither tear IgE nor tear eotaxin, while 15 out of 19 patients with positive IgE values presented a positive amount of eotaxin in their tears (Fisher's test: p < 0.001). The mean eotaxin concentration was 641 ± 154 (SEM) pg/ml. In patients with no amount of tear IgE, we observed a lower conjunctival papilla grade than in patients whose tears contained some amount of IgE (trend test: p = 0.032). In the 15 patients whose tear eotaxin concentration was null, tear IgE concentration was 5.3 ± 3.5 arbitrary units; in the other 15 patients whose eotaxin was positive, IgE reached 21 ± 4.3 arbitrary U (Mann-Whitney: p < 0.001). We measured 127 ± 47 pg/ml eotaxin in patients with no history of SAC but newly diagnosed as suffering from SAC, and 852 ± 218 pg/ml eotaxin in patients with a known SAC (p = 0.008). In contrast, tear IgE concentrations of both groups did not differ statistically significantly (p = 0.947). CONCLUSIONS: If IgE and eotaxin secreted in tears are major contributors in SAC pathogenesis, they however act at different steps of the process.

Impaired skin wound healing in peroxisome proliferator-activated receptor (PPAR)alpha and PPARbeta mutant mice.

We show here that the alpha, beta, and gamma isotypes of peroxisome proliferator-activated receptor (PPAR) are expressed in the mouse epidermis during fetal development and that they disappear progressively from the interfollicular epithelium after birth. Interestingly, PPARalpha and beta expression is reactivated in the adult epidermis after various stimuli, resulting in keratinocyte proliferation and differentiation such as tetradecanoylphorbol acetate topical application, hair plucking, or skin wound healing. Using PPARalpha, beta, and gamma mutant mice, we demonstrate that PPARalpha and beta are important for the rapid epithelialization of a skin wound and that each of them plays a specific role in this process. PPARalpha is mainly involved in the early inflammation phase of the healing, whereas PPARbeta is implicated in the control of keratinocyte proliferation. In addition and very interestingly, PPARbeta mutant primary keratinocytes show impaired adhesion and migration properties. Thus, the findings presented here reveal unpredicted roles for PPARalpha and beta in adult mouse epidermal repair.

Nucleic acid-binding properties of the RRM-containing protein RDM1.

RDM1 (RAD52 Motif 1) is a vertebrate protein involved in the cellular response to the anti-cancer drug cisplatin. In addition to an RNA recognition motif, RDM1 contains a small amino acid motif, named RD motif, which it shares with the recombination and repair protein, RAD52. RDM1 binds to single- and double-stranded DNA, and recognizes DNA distortions induced by cisplatin adducts in vitro. Here, we have performed an in-depth analysis of the nucleic acid-binding properties of RDM1 using gel-shift assays and electron microscopy. We show that RDM1 possesses acidic pH-dependent DNA-binding activity and that it binds RNA as well as DNA, and we present evidence from competition gel-shift experiments that RDM1 may be capable of discrimination between the two nucleic acids. Based on reported studies of RAD52, we have generated an RDM1 variant mutated in its RD motif. We find that the L119GF --> AAA mutation affects the mode of RDM1 binding to single-stranded DNA.