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See detailAxions et polarisation des quasars
Payez, Alexandre ULg

in Barillon, Pierre (Ed.) Journées Jeunes Chercheurs 2008 (2010)

[Français] Je présente rapidement l'objet de mes recherches et tente ensuite l'exercice consistant à exposer - le plus clairement possible - les idées et considérations physiques ayant amené à la ... [more ▼]

[Français] Je présente rapidement l'objet de mes recherches et tente ensuite l'exercice consistant à exposer - le plus clairement possible - les idées et considérations physiques ayant amené à la proposition de l'existence de l'axion. [less ▲]

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See detailThe psychology behind road pricing: Identification of socio-cognitive factors inducing changes in activity-travel behavior
Cools, Mario ULg; Brijs, Kris; Moons, Elke et al

in Proceedings of the 12 World Conference on Transport Research (2010)

The overall final objective of this study is to investigate the effect of road pricing on people’s tendency to adapt their current travel behaviour. In order to reach this goal, a two-stage hierarchical ... [more ▼]

The overall final objective of this study is to investigate the effect of road pricing on people’s tendency to adapt their current travel behaviour. In order to reach this goal, a two-stage hierarchical model is estimated, concentrated around the concept of public acceptability. The research was conducted in Flanders, the Dutch-speaking region of Belgium, by means of an interactive stated adaptation survey, administered on the internet, involving 300 respondents. It is found that behavioural changes themselves are not dependent on the perceived acceptability of road pricing. In addition, earlier findings concerning the acceptability of push measures are validated, and the relevance of using latent factors rather than aggregate indicators is illustrated. [less ▲]

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See detailEstimating the costs of collective treatment of wastewater: the case of Walloon Region (Belgium)
Dogot, Thomas ULg; Xanthoulis, Yanni; Fonder, Nathalie et al

in Water Science & Technology (2010), 62(3), 640-648

This paper contributes to a better understanding of costs for collective wastewater treatment in the Walloon Region (Belgium). Based on a large set of data, unit costs to population equivalents are ... [more ▼]

This paper contributes to a better understanding of costs for collective wastewater treatment in the Walloon Region (Belgium). Based on a large set of data, unit costs to population equivalents are modelled. Considering investment as well as exploitation costs, the model includes not only wastewater treatment plants but also collector and sewage networks in an integrated approach at the technical basin level. Beyond this modelling, each type of process is analyzed independently in order to explore the structure of investment costs and their variation factors. Then, the model was used to forecast the upcoming expenses for 36 areas which are not yet equipped with collective wastewater treatment facilities. In light of these results, strategic choices for decision makers are discussed. [less ▲]

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See detailRelationship between tree development, mean annual increment and internal wood decay in veteran Tilia trees
Campanella, Bruno ULg; Evlard, Aricia ULg; Toussaint, André ULg et al

in Annales de la Société Belge de Dendrologie = Jaarboek van de Belgische Dendrologische Vereniging (2010)

This study aimed at classifying nineteen veteran lime trees (Tilia cordata Mill., T. platyphyllos scop. and T. x europaea L.) in their development. Tilia spp. was chosen because it is long lived and ... [more ▼]

This study aimed at classifying nineteen veteran lime trees (Tilia cordata Mill., T. platyphyllos scop. and T. x europaea L.) in their development. Tilia spp. was chosen because it is long lived and widely present in Belgium. A classification in five steps (A to E) is proposed, based on crown and trunk status, quantity of decaying wood and mean annual girth increment (MAI) as an additionnal criterion. We tested the relationship between veteran tree development and MAI. Threshold values were determined to help distinguish steps A to E. The relationship between trunk growth dynamics, and crown and root development is also discussed. [less ▲]

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See detailEquivariant quantization of spin systems
Michel, Jean-Philippe ULg

in AIP Conference Proceedings (2010), 1307

We investigate the geometric and conformally equivariant quantizations of the super-cotangent bundle of a pseudo-Riemannian manifold (M,g), which is a model for the phase space of a classical spin ... [more ▼]

We investigate the geometric and conformally equivariant quantizations of the super-cotangent bundle of a pseudo-Riemannian manifold (M,g), which is a model for the phase space of a classical spin particle. This is a short review of our previous works. [less ▲]

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See detailInterpretation of serum parathyroid hormone concentrations in dialysis patients: what do the KDIGO guidelines change for the clinical laboratory?
Souberbielle, Jean-Claude; Cavalier, Etienne ULg; Jean, Guillaume

in Clinical Chemistry & Laboratory Medicine (2010), 48(6), 769-774

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See detailBuilding and tracking root shapes.
Jacq, Jean-Jose; Schwartz, Cédric ULg; Burdin, Valerie et al

in IEEE Transactions on Biomedical Engineering (2010), 57(3), 696-707

An algorithm aiming at robust and simultaneous registrations of a sequence of 3-D shapes was recently presented by Jacq et al. [IEEE Trans. Biomed. Eng., vol. 55, no. 5, 2008]. This algorithm has to carry ... [more ▼]

An algorithm aiming at robust and simultaneous registrations of a sequence of 3-D shapes was recently presented by Jacq et al. [IEEE Trans. Biomed. Eng., vol. 55, no. 5, 2008]. This algorithm has to carry out an implicit representation of their common root shape (RS). A particular emphasis was put on the median consensus shape, which is a specific type of RS. Unlike this previous study, mainly focusing on the algorithm foundations while dealing with very specific applications examples, this paper attempts to show the versatility of the RS concept through a set of three problems involving a wider scope of application. The first problem copes with the design of prosthetic cortical plates for the hip joint. It shows how an explicit reconstruction of the RS, coming with its consensus map, could bring out an intermediary anatomical support from which pragmatic choices could be made, thereby performing a tradeoff between morphological, surgical, and production considerations. The second problem addresses in vivo real-time shoulder biomechanics through a miniature 3-D video camera. This new protocol implicitly operates through RS tracking of the content of virtual spotlights. It is shown that the current medical-oriented protocol, while operating within expert offices through low-cost equipments, could challenge high-end professional equipments despite some limitations of the 3-D video cameras currently available. The last problem deals with respiratory motions. This is an auxiliary measurement required by some medical imaging systems that can be handled as a basic application case of the former new protocol. [less ▲]

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See detailCalibrating Activity-Based Models with External OD Information: Overview Of Different Possibilities
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

Many practitioners question the advantages of activity-based models over conventional four-step models in terms of replication of traffic counts. Therefore, in this paper, a framework is highlighted that ... [more ▼]

Many practitioners question the advantages of activity-based models over conventional four-step models in terms of replication of traffic counts. Therefore, in this paper, a framework is highlighted that actively links travel demand models in general, and activity-based models in particular, with traffic counts. Two approaches are presented that calibrate activity-based models with traffic counts, namely an indirect and a direct approach. The indirect approach tries to incorporate findings, based on the analysis of traffic counts, into the model components of the activity-based models. The direct approach calibrates the parameters of the travel demand model in such a way that the model replicates the observed traffic counts (quasi-)perfectly. A practical example is provided to illustrate the direct approach. The study area for this practical example is Hasselt, a Belgian city of about 70,000 residents, and its surrounding municipalities. The practical examples revealed that there is not a single roadway to success in calibrating activity based models, but that different options exist in fine-tuning the activity-based model. Notwithstanding, it is important to recognize some open issues and avenues for further research. First, it is not always appropriate to assume that traffic counts are completely correct. Setting up some belief-structure might increase the responsiveness of the activity-based model. In addition, the OD-matrix calibration that optimizes the correspondence between estimated and observed screen-line counts could negatively impact the correspondence to other measures such as vehicle miles traveled. To conclude, formulation of a multi-objective calibration method is a key challenge for further research. [less ▲]

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See detailModelling Shortest Path Decisions Using an Activity-Based Segmentation
Ramaekers, Katrien; Cools, Mario ULg; Reumers, Sofie et al

in Janssens, Gerrit K.; Ramaekers, Katrien; Caris, An (Eds.) ESM '2010 The European Simulation and Modeling Conference (2010)

The aim of this research is to identify the relationship between activity patterns and route choice decisions. The focus is turned to the relationship between the purpose of a trip and whether or not the ... [more ▼]

The aim of this research is to identify the relationship between activity patterns and route choice decisions. The focus is turned to the relationship between the purpose of a trip and whether or not the shortest path is chosen for the relocation. The data for this study were collected in 2006 and 2007 in Flanders, the Dutch speaking and northern part of Belgium. To estimate the relationship between the choice for the shortest path or not and the corresponding activity-travel behaviour a logistic regression model is developed. The results point out that, when analyzing the relationship between the activities of the people and whether or not the shortest path is chosen, there is no significant influence by the activity-based segmentation. However, when the deviation from the shortest path is related to the activities people perform, a significant relationship is found. Furthermore, next to trip-related attributes (trip distance), also socio-demographic variables and geographical differences play an important role. [less ▲]

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See detailInternational genomic co-operation; Who, what, when, where, why and how?
Cromie, A. R.; Berry, D. P.; Wickham, B. et al

in Interbull Bulletin (2010), 42

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See detailChanges in Travel Behavior in Response to Weather Conditions: Do Type of Weather and Trip Purpose Matter
Cools, Mario ULg; Moons, Elke; Creemers, Lieve et al

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

Weather events can affect traffic in various ways; it can influence travel demand, traffic flows and traffic safety. This paper focuses on the impact of weather conditions on travel demand. The main ... [more ▼]

Weather events can affect traffic in various ways; it can influence travel demand, traffic flows and traffic safety. This paper focuses on the impact of weather conditions on travel demand. The main objectives of this paper are to test the hypothesis that the type of weather determines the likelihood of a change in travel behavior and to assay whether the changes in travel behavior due to weather conditions are dependent on the trip purpose. To this end, a stated adaptation study was conducted in Flanders (Dutch speaking region of Belgium). In total 586 respondents completed the survey, which was administered both on the Internet and via a traditional paper and-pencil questionnaire. To ensure an optimal correspondence between the survey sample composition and the Flemish population, the observations in the sample are weighted. To test the main hypotheses Pearson chi-square independence tests will be performed. Both the results from the descriptive analysis and the independence tests confirm that the type of weather matters, and that the changes in travel behavior in response to these weather conditions are highly dependent on the trip purpose. This dependence of behavioral adjustments on trip purposes provides policy makers with a deeper understanding of how weather conditions affect traffic. Further generalizations of the findings are possible by shifting the scope towards revealed travel behavior. Triangulation of both stated and revealed travel behavior on the one hand, and traffic intensities on the other hand, is certainly a key challenge for further research. [less ▲]

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See detailAssessing Quality of Origin-Destination Matrices Derived from Activity and Travel Surveys: Results from a Monte Carlo Experiment
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

To support policy makers combating travel-related externalities, quality data is required for the design and management of transportation systems and policies. To this end, large amounts of money have ... [more ▼]

To support policy makers combating travel-related externalities, quality data is required for the design and management of transportation systems and policies. To this end, large amounts of money have been spent on collecting household and person-based data. The main objective of this paper is to assess the quality of origin-destination matrices derived from household activity/travel surveys. To this purpose, a Monte Carlo experiment is set up to estimate the precision of OD-matrices given different sampling rates. The Belgian 2001 census data, containing work/school-related travel information for all 10,296,350 residents, are used for the experiment. For different sampling rates, 2000 random stratified samples are drawn. For each sample, three origin-destination-matrices are composed: one at municipality level, one at district level, and one at provincial level. The correspondence between the samples and the population is assessed by using the Mean Absolute Percentage Error (MAPE) and a censored version of the MAPE (MCAPE). The results show that no accurate OD-matrices can be directly derived from these surveys. Only when half of the population is queried, an acceptable OD-matrix is obtained at provincial level. Therefore, it is recommended to use additional information to better grasp the behavioral realism underlying destination choices and to collect information about particular origin-destination pairs by means of vehicle intercept surveys. In addition, the results suggest using the MCAPE next to traditional criteria to examine dissimilarities between different OD matrices. An important avenue for further research is the investigation of the effect of sampling proportions on travel demand model outcomes. [less ▲]

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See detailAssessing the Impact of Public Holidays on Travel Time Expenditure: Differentiation by Trip Motive
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

The impact of public holidays on the underlying reasons of travel behavior, namely the activities people perform and the trips made, is seldom investigated. Therefore, in this paper the impact of public ... [more ▼]

The impact of public holidays on the underlying reasons of travel behavior, namely the activities people perform and the trips made, is seldom investigated. Therefore, in this paper the impact of public holidays on travel time expenditure in Flanders, differentiated by trip motive, is examined. The data used for the analysis stem from a household travel survey that was carried out in 2000. The main modeling approach that is employed is the zero-inflated Poisson regression approach, which explicitly takes into account the inherent contrast between travelers and non-travelers. The zero-inflated Poisson regression models yield findings that are harmonious with international literature: socio-demographic variables, temporal effects and transportation preferences contribute significantly in unraveling the variability of travel behavior. In particular it is shown that public holidays have a non-ignorable impact on daily travel behavior. Triangulation of both quantitative and qualitative techniques seems a solid roadway for further illumination of the underpinnings of travel behavior. [less ▲]

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See detailOn the use of posture verbs by French-speaking learners of Dutch : A corpus-based study
Lemmens, Maarten; Perrez, Julien ULg

in Cognitive Linguistics (2010)

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See detailFamilial aggregation and antimicrobial response dose-dependently affect the risk for Crohn's disease.
Joossens, Marie; Van Steen, Kristel ULg; Branche, Julien et al

in Inflammatory Bowel Diseases (2010), 16(1), 58-67

BACKGROUND:: An increased risk of Crohn's disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in ... [more ▼]

BACKGROUND:: An increased risk of Crohn's disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in innate immunity and/or antibody responses to microbial antigens may be valuable in identifying healthy relatives at risk. METHODS:: We investigated 86 families from Belgium and northern France, 45 with at least 3 first-degree relatives with CD, 24 with a single case, and 17 control families without inflammatory bowel disease (IBD). The cohort consisted of 186 CD patients, 290 healthy relatives, and 142 controls (total 618). Genetic (NOD2, NOD1, TLR4, CARD8) and serologic markers (ASCA, ACMA, ALCA, ACCA, ASigmaMA, OmpC, CBir1, I2) were determined in all subjects. All Belgian families were prospectively followed up for 54 months. RESULTS:: In multiple-affected families, an increment of affected first-degree relatives and of positive antibodies were additive risks factors for CD (P < 0.0001), independent of NOD2 mutations. When comparing subjects from multiple-affected families, having 3 additional first-degree relatives with CD and 1 additional positive antibody increased the odds for CD to 9.19 (95% confidence interval [CI]: 4.07-20.80). After a follow-up of 54 months among all Belgian families, a total of 4 new diagnoses of IBD were confirmed in the multiple-affected families only, resulting in a 57-fold increase in incidence within multiple-affected families compared to the known incidence of IBD in our region. CONCLUSIONS:: We found an additive risk increment for CD in subjects from multicase families per additional affected relative and per additional positive antibody, independent of NOD2. Furthermore, a very high disease incidence was observed in these multiple-affected families. Inflamm Bowel Dis 2010. [less ▲]

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See detailGenetic evaluation for body condition score in the Walloon region of Belgium
Bastin, Catherine ULg; Gillon, Alain ULg; Massart, Xavier et al

in Interbull Bulletin (2010), 42

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See detailPost-face : Vers un deuxième âge de la nébuleuse des OSC au Sud?
Poncelet, Marc ULg

in Comhaire, Gaël (Ed.) Société civile et éducation (2010)

The growing number of education (school) hybrid institutions in Africa is supported by transnational trends in education power. A lot of private schools appears but also many "associations" and NGO as ... [more ▼]

The growing number of education (school) hybrid institutions in Africa is supported by transnational trends in education power. A lot of private schools appears but also many "associations" and NGO as parents committees... The paper try to identify some new dimensions in social and political concern. [less ▲]

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See detailImpact of tree species on the distribution of alkaliextractable Si in a Cambisol
Cornelis, Jean-Thomas ULg; Ranger, Jacques; Delvaux, Bruno

Poster (2010)

Abstract : In terrestrial ecosystems, silicon (Si) uptake by higher plants induces biogenic silica (BSi) deposits in leaves, which contribute to the amorphous silica (ASi) pool in soil through litter-fall ... [more ▼]

Abstract : In terrestrial ecosystems, silicon (Si) uptake by higher plants induces biogenic silica (BSi) deposits in leaves, which contribute to the amorphous silica (ASi) pool in soil through litter-fall. In forests, the ASi pool, including BSi, is ubiquitous and a substantial component of soils, which might influence the Si mass-balance at watershed scale. Here, we examined the distribution of ASi pool, estimated by alkaline dissolution (alkali-extractable Si), in an acid brown soil under three common European tree species in identical soil and climate conditions in order (i) to study how the Si recycling by tree species impacts the ASi pool in soil, and (ii) to identify the different constituents of the alkali-extractable Si pool in soil. We therefore quantified the ASi concentration with alkaline extraction (Na2CO3, 0.1M), the Si adsorbed onto poorly crystalline Fe oxides by oxalate extraction and the “plant-available Si” by CaCl2 extraction. In humus layer, the alkali-extractable Si concentration (mg SiO2 g-1) significantly decreases in the sequence: Douglas fir (14.5±0.65) > European beech (11.8±0.30) > Black pine (5.4±0.31). Below 15 cm soil depth, the alkali-extractable Si concentration is not significantly different between tree species. For each tree species, the alkali-extractable Si concentration in soil decreases from the humus layer to 15 cm depth and then slightly increases from 15 to 75 cm depth. Our data clearly show that tree species can impact the ASi content in topsoil (humus layer - 15 cm) through different Si uptake rates. Indeed, various Si recycling by forest vegetation imply different rates of BSi accumulation in leaves and then, different rates of BSi restitution on topsoil. In mineral layers, pedogenic processes play an important role in the ASi distribution given the alkali-extractable Si pool is mostly influenced by BSi dissolution, stable BSi preservation/translocation and secondarily by Si adsorption onto active amorphous Fe oxide surface. [less ▲]

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See detailDescriptive study of 32 cases of doxycycline-overdosed calves.
Brihoum, Mounir ULg; Amory, Hélène ULg; Desmecht, Daniel ULg et al

in Journal of Veterinary Internal Medicine (2010), 24(5), 1203-10

BACKGROUND: Reports of doxycycline-induced toxicity are limited despite common use of this antibiotic to treat infectious respiratory disorders in calves. OBJECTIVE: To describe previously unreported ... [more ▼]

BACKGROUND: Reports of doxycycline-induced toxicity are limited despite common use of this antibiotic to treat infectious respiratory disorders in calves. OBJECTIVE: To describe previously unreported kidney lesions and diagnostic test results in doxycycline-overdosed calves and to compare these results with other findings reported previously. ANIMALS: Thirty-two calves that presented with adverse effects after receiving high doses of doxycycline as a treatment for mild respiratory disorders. METHOD: Retrospective review of medical records. RESULTS: Clinical examination identified mainly lethargy, dyspnea, cough, tongue paresia or paralysis associated with dysphagia and sialorrhea, tachycardia, tachypnea, and signs of myopathy. Blood analysis indicated increases in creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and sorbitol dehydrogenase activities and increased serum creatinine and urea concentrations. ECG recordings and Doppler echocardiography examination identified ventricular premature beats and a decrease in left ventricular global and systolic function, respectively. Necropsy and histopathology disclosed necrosis of the myocardium, tongue, and some striated muscles, acute renal tubular necrosis, and fatty degeneration or congestion of the liver. CONCLUSIONS: Most of these findings corroborate previous observations made in doxycycline-overdosed calves, and further suggest myocardial and striated muscular toxicity as well as renal toxicity in doxycycline-overdosed calves. [less ▲]

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