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See detailIntegration of near-surface geophysical, geological and hydrogeological data with multiple-point geostatistics in alluvial aquifers
Hermans, Thomas ULg

Doctoral thesis (2014)

Alluvial plains constitute essential geological bodies for environmental studies such as contaminated sites remediation, low-enthalpy geothermal energy or groundwater resources. The heterogeneity of these ... [more ▼]

Alluvial plains constitute essential geological bodies for environmental studies such as contaminated sites remediation, low-enthalpy geothermal energy or groundwater resources. The heterogeneity of these deposits governs flow processes and needs to be quantified. A proper description of such complex deposits requires an integrated approach combining geological, geophysical and hydrogeological data. Solving such spatial inverse problems in the Earth Sciences remains a considerable challenge given the large number of parameters to invert for, the non-linearity of forward models and, as a result, the ill-posedness of the problem. Geostatistics is therefore needed to specify prior models, more particularly, information to control the spatial features of the inverse solutions. Two-point geostatistical approaches have been developed to describe the heterogeneity of one geological formation but fail to reproduce the heterogeneity of fluvial deposits with multiple facies. Multiple-point statistics (MPS) introduced the training image (TI) concept to replace the variogram within an extended sequential simulation framework. The use of geophysics to constrain such simulations has been studied in the petroleum industry with wave-based methods (seismic reflection), but little research has been done to assess the use of near-surface potential methods to condition MPS in environmental studies. In this work, we propose to integrate geological (borehole logs), geophysical (electrical resistivity tomography (ERT) profiles) and hydrogeological (hydraulic heads) data within MPS models on the alluvial plain of the Meuse River, Belgium. Potential-based geophysical methods being integrative, they suffer from a relatively poor resolution. We first study how we can improve the informative content of geophysical inversion by including prior information in the ERT inverse problem. Three methods are tested and compared in several field cases, namely the reference model inversion, the structural inversion and the regularized geostatistical inversion. If every method has advantages and drawbacks, the best suited method for the considered problem is the regularized geostatistical method. Electromagnetic borehole logs enable to derive the vertical correlation length of electrical resistivity in the deposits and to subsequently use it to constrain the inversion. In addition to the knowledge of the bedrock position, it enables to retrieve an electrical resistivity distribution of the deposits close to direct observations. This ensures that geophysical models will be informative to constrain MPS simulations. Given the lack of geological and sedimentological data to build accurate TIs, a data base of TIs is built using several different parameters and scenarios. They are all based on a three facies description: clay/loam, sand and gravel corresponding to low, intermediate and high hydraulic conductivity. Then, we develop a methodology to verify the consistency of independently-built TIs with geophysical data. Our methodology starts by creating subsurface models with each TI. From these models we create synthetic geophysical data and from this synthetic data, synthetic inverted models. These models are now compared with a single inverted model obtained from the field survey, allowing for our definition of what is ``consistent''. To that extent, we calculate the Euclidean distance between any two inverted models as well as field data and visualize the results in a 2D or 3D space using multidimensional scaling (MDS). With this technique, it is possible to verify if field cases fall in the distribution represented by synthetic cases, and thus are consistent with them. In a second step, we present a cluster analysis on the MDS-map to highlight which parameters are the most sensitive for the construction of TI. Based on this analysis, a probability of each geological scenario is computed through kernel smoothing of the densities in reduced projected metric space. The integration of hydrogeological data is made through a stochastic inversion method: the probability perturbation method (PPM), using MPS constrained with geophysical data to generate models. The PPM algorithm automatically seeks solutions fitting both hydrogeological data and training-image based geostatistical constraints. Only geometrical features of the model are affected by the perturbation, i.e. we do not attempt to directly find the optimal value of hydrogeological parameters (chosen a priori), but the optimal spatial distribution of facies whose prior distribution is quantified in a training image. Tracing experiments may be used to further constrain hydrogeological models. ERT has proven its ability to monitor salt tracer tests, but few studies have investigated its performances in thermal tracing experiments. In this study, we demonstrate the ability of surface and crosshole ERT to image quantitatively temperature changes during heat injection experiments. Such resistivity data provides important information to improve hydrogeological models. Our study proves that ERT, especially crosshole ERT, is a reliable tool to follow thermal tracing experiments. It also confirms that ERT should be included to in situ techniques to characterize heat transfer in the subsurface and to monitor geothermal resources exploitation. [less ▲]

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See detailNeuropathies proximales du membre supérieur
WANG, François-Charles ULg

Conference (2014, April 01)

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See detailPrise de risque et zéro-mort
Dumoulin, André ULg

Scientific conference (2014, April 01)

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See detailSoil organic carbon assessment by field and airborne spectrometry in bare croplands: accounting for soil surface roughness
Denis, Antoine ULg; Stevens, Antoine; Van Wesemael, Bas et al

in Geoderma (2014), 226-227(August 2014), 94102

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC ... [more ▼]

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC assessment (SOCa) is usually done by using calibration samples and multivariate models. However one of the major constraints of this technique, when used in field conditions is the spatial variation in surface soil properties (soil water content, roughness, vegetation residue) which induces a spectral variability not directly related to SOC and hence reduces the SOCa accuracy. This study focuses on the impact of soil roughness on SOCa by outdoor VIS-NIR-SWIR spectroscopy and is based on the assumption that soil roughness effect can be approximated by its related shadowing effect. A new method for identifying and correcting the effect of soil shadow on reflectance spectra measured with an Analytical Spectral Devices (ASD) spectroradiometer and an Airborne Hyperspectral Sensor (AHS-160) on freshly tilled fields in the Grand Duchy of Luxembourg was elaborated and tested. This method is based on the shooting of soil vertical photographs in the visible spectrum and the derivation of a shadow correction factor resulting from the comparison of “reflectance” of shadowed and illuminated soil areas. Moreover, the study of laboratory ASD reflectance of shadowed soil samples showed that the influence of shadow on reflectance varies according to wavelength. Consequently a correction factor in the entire [350–2500 nm] spectral range was computed to translate this differential influence. Our results showed that SOCa was improved by 27% for field spectral data and by 25% for airborne spectral data by correcting the effect of soil relative shadow. However, compared to simple mathematical treatment of the spectra (first derivative, etc.) able to remove variation in soil albedo due to roughness, the proposed method, leads only to slightly more accurate SOCa. [less ▲]

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See detailEpoch-dependent absorption line profile variability in lambda Cep
Uuh-Sonda, J. M.; Rauw, Grégor ULg; Eenens, P. et al

in Revista Mexicana de Astronomia y Astrofisica (2014), 50

We present the analysis of a multi-epoch spectroscopic monitoring campaign of the O6 Ief star lambda Cep. Previous observations reported the existence of two modes of non-radial pulsations in this star ... [more ▼]

We present the analysis of a multi-epoch spectroscopic monitoring campaign of the O6 Ief star lambda Cep. Previous observations reported the existence of two modes of non-radial pulsations in this star. Our data reveal a much more complex situation. The frequency content of the power spectrum considerably changes from one epoch to the other. We find no stable frequency that can unambiguously be attributed to pulsations. The epoch-dependence of the frequencies and variability patterns are similar to what is seen in the wind emission lines of this and other Oef stars, suggesting that both phenomena likely have the same, currently still unknown, origin. [less ▲]

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See detailHaplotype information combined with iterative pruning PCA (ipPCA) to improve population clustering
Chaichoompu, Kridsadakorn ULg; Fouladi, Ramouna; Wangkumhang, Pongsakorn et al

Scientific conference (2014, April 01)

Single Nucleotide Polymorphisms (SNPs) are commonly used to capture variations between populations. Often genome-wide SNP data are pruned based on linkage disequilibrium (LD) patterns or small subsets of ... [more ▼]

Single Nucleotide Polymorphisms (SNPs) are commonly used to capture variations between populations. Often genome-wide SNP data are pruned based on linkage disequilibrium (LD) patterns or small subsets of SNPs are selected (e.g. PCA-correlated SNPs) to reproduce the genomic structure of the complete data set. Identifying and differentiating between subpopulations using such a reduced set can become challenging, especially when similar geographic regions are involved or when spurious patterns are likely to exist. Although PCA-based methods can resolve structure, they cannot infer ancestry. On the other hand, the structure of haplotypes in unrelated individuals can reveal useful information about genetic ancestry. Notably, haplotype composition and the pattern of LD between markers may vary between larger populations but may also play a role within more confined geographic regions. In addition, iterative pruning principal component analysis (ipPCA) has been shown to be a powerful tool to cluster subpopulations based on SNP profiles. Despite the complexities that are associated with haplotype inference, we argue that added value can be obtained when the LD structure between SNPs is exploited in the search for relevant population strata. In this work, we propose to combine an LD-based novel haplotype encoding scheme with the ipPCA machinery to retrieve fine population substructures. The approach is compared to state-of-the-art methods in the context of population substructure and admixture analysis. [less ▲]

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See detailMetabolically healthy overweight and obesity
Esser, Nathalie ULg; SCHEEN, André ULg; PAQUOT, Nicolas ULg

in Annals of Internal Medicine (2014), 160(7), 514

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See detailMolecular evidence of Anaplasma phagocytophilum in wild boar (Sus scrofa) in Belgium
Nahayo, Adrien; Bardiau, Marjorie ULg; Volpe, Rosario ULg et al

in BMC Veterinary Research (2014), 10(80),

Anaplasma phagocytophilum is a tick-borne pathogen of veterinary and human importance. Both ticks as vectors and vertebrates as reservoir hosts are essential for the cycle maintenance of this bacterium ... [more ▼]

Anaplasma phagocytophilum is a tick-borne pathogen of veterinary and human importance. Both ticks as vectors and vertebrates as reservoir hosts are essential for the cycle maintenance of this bacterium. Currently, the whole range of animal species reservoirs for A. phagocytophilum in natural environment is still unknown. Therefore, the aim of this study was to estimate the prevalence of infection with A. phagocytophilum in the wild boar population in southern Belgium. [less ▲]

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See detail“Fairebel” fair milk: a multi-level innovation
Feyereisen, Marlène ULg; Melard, François ULg

Conference (2014, April)

The research focuses on the case study of the Belgian fair-trade milk “Fairebel”, which was created by dairy farmers a few months after the 2009 European milk crisis. This innovation is overseen by the ... [more ▼]

The research focuses on the case study of the Belgian fair-trade milk “Fairebel”, which was created by dairy farmers a few months after the 2009 European milk crisis. This innovation is overseen by the “Fair Milk” programme set up by the European Milk Board (EMB), a European organization of dairy farmers, which has established five fair-trade milk labels in European countries (Austria, the Netherlands, Belgium, Luxembourg, and France). At the Belgian level, the case study of the “Fairebel” project shows how the dairy system is institutionally, politically, and technically locked in. In such an irreversible system, the developers of “Fairebel” have had to use cunning and espouse some contradictions (even inconsistencies) in order to build their idea of fair-trade milk and to achieve its commercialization in the real world of commodities. Also, the “Fairebel” project is trying to increase the market power of dairy farmers and by-passes entirely the dairy industry in Belgium, which refused to support the project. For example, the developers of “Fairebel” stock up on the spot market and the Fairebel” milk cartons are produced and filled by the Luxembourg co-operative dairy Luxlait. On this level, the “Fairebel” project is more a “reorientation of trajectories” than a radical transition of the system: It uses internal resources of the main system to try to change some of its detrimental consequences, such as the prices paid to dairy farmers, without forcing through associated structural transitions. On the European level of the EMB, in which “Fairebel” participates, the transition of the system is radicalized by changing the character and the structure of the regime itself (e.g. CAP): reversal of the balance of power between dairy farmers and dairy processors, re-appropriation of the means of production by the farmers, and modification of the economic and trade rules of the dairy products (e.g., monitoring agency). Taken together, these two levels of this fair-milk innovation strengthen each other, so that the transition that “Fairebel” has inspired is more radical than it would seem when the Belgian level is considered alone. [less ▲]

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See detailImportance of synovitis in osteoarthritis: Evidence for the use of glycosaminoglycans against synovial inflammation.
Henrotin, Yves ULg; Lambert, Cécile ULg; Richette, Pascal

in Seminars in Arthritis & Rheumatism (2014), 43(5), 579-87

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See detailA geochemical and petrological study of the Late Cretaceous banatites from the Apuseni Mountains, Romania
Vander Auwera, Jacqueline ULg; Berza, Tudor; Dupont, Alain et al

Poster (2014, April)

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See detailPhysical Education Stimulating a Healthy Lifestyle and Critical Sports Consumption in Belgium
De Martelaer, Kristine; Seghers, Jan; Cardon, Greet et al

in Chin, Ming-Kai; Edginton, Christopher (Eds.) Physical Education and Health Global Perspectives and Best Practice (2014)

In this chapter, the authors describe the situation and challenges of Physical Education (PE) in Flanders and Wallonia in order to encourage young people to adopt a healthy lifestyle and to become ... [more ▼]

In this chapter, the authors describe the situation and challenges of Physical Education (PE) in Flanders and Wallonia in order to encourage young people to adopt a healthy lifestyle and to become critical sports consumers. In school-age children, about one out of six has problems with obesity/overweight. Compared with earlier measurements there is a trend of increasing sedentary time per day and not enough physical activity (PA) to reach international norms. Girls can be definitely considered as a public at risk regarding the physical activity component of their healthy lifestyle. In recent years, the emphasis has shifted from motor- and/or physical-testing towards the development of a positive attitude towards physical activity and being socially engaged. The main concern of the course-specific final attainment levels is teaching how to deal with the current movement culture of games, sports, fitness, and daily activity. In both regions, it is expected that children are taught to transfer movement and personally-related competencies learned in PE to other contexts. Initiatives to develop and enhance links between PE and other opportunities to be physically active in the wider community are receiving more attention during the last few years, but the situation is still far from ideal. Because of the complex role of promoting a healthy lifestyle during PE and in the whole school, there is a need to educate teachers during their teacher training and lifelong education on how to provide relevant choices, satisfying the need for autonomy. [less ▲]

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See detailBrown rust disease control in winter wheat: I. Exploring an approach for disease progression based on night weather conditions
El Jarroudi, Moussa ULg

in Environmental Science & Pollution Research (2014), 21(4), 4797-4808

An empirical approach for simulating the infection and progress of leaf rust (caused by Puccinia triticina) during stem elongation on winter wheat was analysed for the 2000 to 2006 growing seasons. The ... [more ▼]

An empirical approach for simulating the infection and progress of leaf rust (caused by Puccinia triticina) during stem elongation on winter wheat was analysed for the 2000 to 2006 growing seasons. The approach was elaborated based on night weather conditions (i.e., air temperature, relative humidity and rainfall) and leaf rust occurrences. Data from three consecutive cropping seasons (2000-2002) at four representative sites of the Grand-Duchy of Luxembourg were used in the set-up phase. The capability to correctly simulate the occurrence expression of P. triticina infections on the upper leaf layers was then assessed over the 2003-2006 period. Our study revealed that the development of leaf rust required a period of at least 12 consecutive hours with air temperatures ranging between 8 and 16 °C, a relative humidity greater than 60 % (optimal values being 12-16 °C and up to 80 % for air temperatures and relative humidity, respectively) and rainfall less than 1 mm. Moreover, leaf rust occurrences and infections were satisfactorily simulated. The false alarm ratio was ranged from 0.06 to 0.20 in all the study sites. The probability of detection and critical success index for WLR infection were also close to 1 (perfect score). [less ▲]

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See detailIncreasing meltwater discharge from the Nuuk region of the Greenland ice sheet and implications for mass balance (1960-2012)
Van As, D; Andersen, ML; Petersen, D et al

in Journal of Glaciology (2014), 60(220), 314-322

We assess the runoff and surface mass balance (SMB) of the Greenland ice sheet in the Nuuk region (southwest) using output of two regional climate models (RCMs) evaluated by observations. The region ... [more ▼]

We assess the runoff and surface mass balance (SMB) of the Greenland ice sheet in the Nuuk region (southwest) using output of two regional climate models (RCMs) evaluated by observations. The region encompasses six glaciers that drain into Godtha ̊bsfjord. RCM data (1960–2012) are resampled to a high spatial resolution to include the narrow (relative to the native grid spacing) glacier trunks in the ice mask. Comparing RCM gridded results with automatic weather station (AWS) point measurements reveals that locally models can underestimate ablation and overestimate accumulation by up to tens of per cent. However, comparison with lake discharge indicates that modelled regional runoff totals are more accurate. Model results show that melt and runoff in the Nuuk region have doubled over the past two decades. Regional SMB attained negative values in recent high-melt years. Taking into account frontal ablation of the marine-terminating glaciers, the region lost 10–20 km3 w.e. a–1 in 2010–12. If 2010 melting prevails during the remainder of this century, a low-end estimate of sea-level rise of 5 mm is expected by 2100 from this relatively small section (2.6%) of the ice sheet alone. [less ▲]

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See detailChemical analyses of the seeds from Prunella vulgaris: A chemotaxonomic approach
Paul, Aman ULg; Frederich, Michel ULg; Cieckiewicz, Ewa ULg et al

Poster (2014, April)

Common self-heal (Prunella vulgaris) plants are traditionally sown along the border of crops to enhance the biodiversity. Besides enhancing the biodiversity, they can also be a source of interesting ... [more ▼]

Common self-heal (Prunella vulgaris) plants are traditionally sown along the border of crops to enhance the biodiversity. Besides enhancing the biodiversity, they can also be a source of interesting compounds which could be important for food, pharmaceutical and cosmetic industries. The seeds of Common Yarrow were investigated for proteins, fatty acid compositions and polyphenolic compounds. The protein content was analyzed according to Dumas method, the extraction of oil was done using a cold extraction technique employing 2:1 chloroform/methanol as solvent, the fatty acid composition was determined using the gas chromatography and the amount of polyphenolic compounds were estimated using the method as described in European Pharmacopoeia, 8th edition. Common self-heal seeds can be of great commercial importance. [less ▲]

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See detailThe rewriting ethos of the Vertigo imprint: critical perspectives on memory-making and canon formation in the American comics field
Dony, Christophe ULg

in Comicalités : Études de Culture Graphique (2014)

This essay investigates how and why strategies of rewriting have been central to Vertigo’s poetics and editorial project for over twenty years. Drawing notably on the works of Harold Bloom, Thierry ... [more ▼]

This essay investigates how and why strategies of rewriting have been central to Vertigo’s poetics and editorial project for over twenty years. Drawing notably on the works of Harold Bloom, Thierry Groensteen, and Geoffrey Klock, it first proceeds to establish the relevance of the concept of rewriting as it can be applied to comics (studies), particularly in showing how inter- and hypertextual relations are inherently connected to issues of nostalgia, memory as well as lineage, and therefore to processes of (self-)canonization and discourses of cultural legitimacy. It then moves on to identify some of the label's rewriting trends and discusses how they engage both intro- and retrospectively with the comics form, its history, and its (renewed) perception in the American context. More specifically, in recurrently paying homage to the DC archive, the pulp heritage, as well as to the Gothic tradition, it is my contention that Vertigo has participated in a critical logic of commemoration that distances itself from the mnemonic discourses championed by both the mainstream and alternative poles of the comics industry. In so doing, Vertigo may have attempted to create a canon of its own while certainly challenging Groensteen's claim that comics is an “art without memory”. But perhaps more importantly, the essay concludes that Vertigo's cherishing of specific rewriting strategies has helped it adopt a politics of demarcation in regards to the structuring forces of the American comics field, a politics that not only subverts the field's power relations dynamics but also “writes back” to its practices of domination and exclusion. [less ▲]

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