Estimating pCO2 from remote sensing in the Belgian Coastal Zone

Poster (2012, April 22)

Feasibility of scanning fetal anatomy in the first trimester of gestation

in European Federation of Societies for Ultrasound in Medicine and Biology (2012, April 22)

Objectives: This study aims to evaluate the feasibility of performing an anatomy scanned for fetal abnormalities at the time of nuchal translucency (NT) measurement in Vietnamese population Material and ... [more ▼]

Objectives: This study aims to evaluate the feasibility of performing an anatomy scanned for fetal abnormalities at the time of nuchal translucency (NT) measurement in Vietnamese population Material and methods: In a prospective study, 2500 singleton pregnancies measured fetal NT and scanned structural anatomy in the first trimester; then checked fetal morphology systematically at 18-24 weeks and followed up to their delivery. According to ultrasonographic abnormalities and amniocentesis, we evaluated the detection rate of ultrasound for aneuploidy in the first and second trimester of gestation. Results: The sensitivity and specificity of ultrasound for aneuploidy was 17.2% and 99.7%, respectively. All 13 cases of fetal ultrasonographic anomalies related significantly with an increased NT (≥ 2.4mm) (p < 0.001). 30.8% of these abnormalities that included cystic hygroma, omphalocele and holoprosencephaly were detected at 11-13.6 weeks’ gestation. In the second trimester scanning, 69.2% of major structural anomalies found and the detection rate of central nervous system malformation, abnormal heart, abdominal wall defect, face anomaly and skeletal deformities were 85.7%, 100%, 66.7%, 50% and 75%, alternatively. Conclusion: Scanning of fetal anatomy at the time of NT measuring is useful to detect fetal abnormalities, especially aneuploidy in Vietnamese pregnancies. [less ▲]

Les élections présidentielles et législatives françaises : aperçu des règles du jeu

Conference given outside the academic context (2012)

Cette conférence donne un bref aperçu des principales règles juridiques qui sont applicables aux élections présidentielles et législatives françaises.

Variability of methane in the epilimnion of Lake Kivu

Poster (2012, April 22)

Historical changes in carbon dioxide (CO2) and dimethyl sulphide (DMS) emissions in the eutrophied Southern North Sea

Conference (2012, April 22)

Alfred Hitchcock, du soupçon au suspens

Conference given outside the academic context (2012)

Arthur a un cancer: pour nous, frères et soeurs, pas facile à vivre

Conference (2012, April 21)

Une épée pour saint Pierre ? Les princes français et le Grand Schisme d’Occident

Conference (2012, April 20)

Reflections on the notion of 'consumer behaviour'

Conference (2012, April 20)

Today, consumer behavior has become a key concept in scientific publications and in international public health strategies. Both 'behavior' and the 'consumer' are in the title of the 3rd annual conference ... [more ▼]

Today, consumer behavior has become a key concept in scientific publications and in international public health strategies. Both 'behavior' and the 'consumer' are in the title of the 3rd annual conference of the Belgian Nutrition Society. This paper proposes a reflection on these concepts, and invites for further discussion. Firstly, the 'consumer' and his attributes will be briefly explored through an analysis of the Health Claims Regulation EC No 1924/2006. This document, intended to protect consumers from misleading information, uses a model of the consumer rooted in rational choice theory. Secondly, as medical sociologist David Armstrong (2009) has shown, the term 'behavior' has been brought in relation to health outcomes only relatively recently in medicine and public health. As such, it has come to be defined as a modifiable risk factor. I argue that European public health strategies have integrated this definition of behavior and the related idea of 'lifestyle' into rational choice theory. As such, 'behavior' and 'lifestyle' frame problems of health and disease in a specific way. The third section of this paper will confront this model of problem-framing with different understandings of 'behavior' coming from historical and contemporary sociological research. [less ▲]

Geophysical identification, characterization, and monitoring of preferential groundwater flow paths in fractured media

Doctoral thesis (2012)

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to ... [more ▼]

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to identify, characterize, monitor, and finally model preferential flow in hydraulically-active fractured zones at a scale representative of real world applications. From an experimental point of view, we first identified the magnitude of self-potential signature, a -15 mV anomaly that could be associated with preferential groundwater flow in a shallow quartzite aquitard whereas the streaming potential theory was originally developed for porous media. This signature was confirmed experimentally in limestone aquifers at greater depths. The joint use of surface ERT and SP allowed the identification of water-bearing fractured areas which were electrically more conductive, presenting contrasts from 1 to 10 and which were hydraulically-active presenting negative SP anomalies ranging from -10 to -30 mV. We were also able to correlate hydraulic heads and SP gradients during a low and a high groundwater level period leading to interesting perspectives in understanding the dynamics of complex groundwater flow systems. Finally, a preferential flow and rapid transport path, over 10 m/h, was highlighted in a 20 m deep fractured and karstified limestone valley by monitoring a salt tracer test with only surface ERT. This methodology was being mostly used for relatively shallow and homogeneous aquifers up to now. Such information is crucial to set up new monitoring wells or to define the sampling rates of classic tracer test. From a methodological point of view, we quantitatively assessed the efficiency of blocky and minimum-gradient-support regularizations in electrical imaging to recover sharp interfaces on numerical benchmarks and with field data. The usefulness of resolution indicators such as the cumulative sensitivity matrix and the resolution matrix were also assessed in this context. We demonstrated that noise characterization is crucial in time-lapse inversion and may supplant the choice of the time-lapse inversion scheme, calling for a systematic analysis of reciprocal measurements (or a subset of them). We also showed that, when using data differences in an inversion scheme, the data error, as estimated by time-lapse reciprocal measurements, depends on the mean measured resistance. These error characterization studies should always be performed if one wants to avoid wrong interpretations about the hydrodynamics. We further showed that focused inversion techniques (blocky inversion, minimum-gradient-support) may offer great perspectives when recovering model changes in time-lapse inversion. Finally, ERT and SP were jointly used to conceptualize a physically-based and spatially distributed hydrogeological model, in particular to characterize the preferential flow paths. Predicted hydraulic heads and SP-derived hydraulic heads using the water table model showed a clear correlation, leading to perspectives in terms of hydrogeological model calibration. Further experiments are however needed to fully estimate the streaming potential apparent coupling coefficient, but the use of the full SP signals for hydrogeological model calibration is a clear perspective to this work. [less ▲]