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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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See detailAdverbes de lieu, deixis et anaphore chez les historiens latins
Longrée, Dominique ULg

in De lingua latina (2010), 3

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See detailLes Zones Cynégétiques Villageoises du Nord de la République Centrafricaine : 15 ans déjà !
Bouché, Philippe ULg

in Parcs & Réserves (2010), 65(2), 1-8

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See detailWorking Group 3 Infrared interferometry at Dome C
Coudé Du Foresto; Surdej, Jean ULg

in Spinoglio, L.; Epchtein, N. (Eds.) ies 3rd ARENA Conference: An Astronomical Observatory at CONCORDIA (Dome C, Antarctica) (2010)

The goal of the working group was to define and realize a pre-feasibility study of an Antarctic interferometer dedicated to the characterization of exozodis with the sensitivity required (30 zodis 5 Ï ... [more ▼]

The goal of the working group was to define and realize a pre-feasibility study of an Antarctic interferometer dedicated to the characterization of exozodis with the sensitivity required (30 zodis 5 Ï detection) to discriminate sources suitable for future exoearth spectroscopic analysis. The engineering study was carried out at AMOS, based on a concept by Thalès Alenia Space derived from the GENIE instrument studied for ESA. Particular emphasis was put on the compatibility with Concordia logistic and operational constraints, for which input was provided by IPEV through long visits by a system engineer student, Xavier Daudigeos. The preliminary results are encouraging enough so that we recommend to move forward with a proposal for full industrial feasibility study that could be submitted to FP7 and/or to ESA. [less ▲]

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See detailAn update on the evolution of double parton distributions
Ceccopieri, Federico ULg

E-print/Working paper (2010)

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See detailTranscriptomic biomarkers of the response of hospitalized geriatric patients with infectious diseases
Duy Vo, Thi Kim; Godard, Patrice; de Saint-Hubert, Marie et al

in Immunity & Ageing : I & A (2010), 17

Background: Infectious diseases are significant causes of morbidity and mortality among elderly populations. However, the relationship between oxidative stress, immune function and inflammatory response ... [more ▼]

Background: Infectious diseases are significant causes of morbidity and mortality among elderly populations. However, the relationship between oxidative stress, immune function and inflammatory response in acute phase of the infectious disease is poorly understood. Results: Herein the abundance of a selection of 148 transcripts involved in immunosenescence and stress response was compared in total RNA of PBMC of 28 healthy aged probands and 39 aged patients in acute phase of infectious disease (day 2-4 after hospitalization) or in convalescence phase (day 7-10). This study provides a list of 24 differentially abundant transcript species in the acute phase versus healthy aged. For instance, transcripts associated with inflammatory and anti-inflammatory reactions (TNFRSF1A, IL1R1, IL1R2, IL10RB) and with oxidative stress (HMOX1, GPX1, SOD2, PRDX6) were more abundant while those associated with T-cell functions (CD28, CD69, LCK) were less abundant in acute phase. The abundance of seven of these transcripts (CD28, CD69, LCK, CTSD, HMOX1, TNFRSF1A and PRDX6) was already known to be altered in healthy aged probands compared to healthy young ones and was further affected in aged patients in acute phase, compromising an efficient response. Conclusion: This work provides insights of the state of acute phase response to infections in elderly patients and could explain further the lack of appropriate response in the elderly compared to younger persons. [less ▲]

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See detailMise au point de l’indice composition dans le cadre de l’indicateur phytoplancton - les indices de composition phytoplanctonique en eaux côtières : synthèse bibliographique
Goffart, Anne ULg

Report (2010)

Ce rapport rappelle brièvement pourquoi le phytoplancton est un excellent indicateur de l’état des eaux côtières et synthétise les limites adaptatives des communautés phytoplanctoniques en réponse aux ... [more ▼]

Ce rapport rappelle brièvement pourquoi le phytoplancton est un excellent indicateur de l’état des eaux côtières et synthétise les limites adaptatives des communautés phytoplanctoniques en réponse aux perturbations d’origine anthropique (essentiellement l’enrichissement en sels nutritifs). Il présente ensuite l’indicateur phytoplanctonique idéal et résume l’état des connaissances en matière d’indices de composition et d’indicateurs phytoplanctoniques intégrant la composition. Les méthodes de calcul des indices sont expliquées lorsque les informations disponibles sont suffisamment claires et détaillées. Le rapport se termine par la proposition de pistes à explorer pour la mise au point et la validation d’un indice de composition phytoplanctonique qui soit opérationnel et représentatif de la composition taxonomique d’une masse d’eau côtière et de son évolution temporelle. [less ▲]

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See detailL'inventaire forestier permanent de la Région wallonne : bilan de 15 ans d'un outil aux multiples fonctions* (Partie 1 - Fondements méthodologiques et nature des données récoltées)
Rondeux, Jacques ULg; Lecomte, Hugues; Latte, Nicolas ULg et al

in Silva Belgica (2010), 117ème année(2), 12-16

Avant l'exécution proprement dite de l'inventaire permanent, de 1980 à 1983, un premier inventaire couvrant tout le territoire wallon (à raison d'une placette temporaire installée par 50 hectares de forêt ... [more ▼]

Avant l'exécution proprement dite de l'inventaire permanent, de 1980 à 1983, un premier inventaire couvrant tout le territoire wallon (à raison d'une placette temporaire installée par 50 hectares de forêt) avait déjà permis de fournir une image de la situation forestière de l'époque et ouvert la voie à ce qui peut être considéré aujourd'hui comme étant non seulement un observatoire continu de la forêt wallonne mais aussi un tableau de bord des orientations et mesures de gestion qui la concernent. Observatoire, car il est le reflet de l'évolution de la forêt et de ses principaux éléments constitutifs au cours du temps. Tableau de bord, du fait de la possibilité d'en extraire non seulement des éléments pertinents d'aide à la décision en matière de gestion et de politique forestières, mais aussi des indicateurs de suivi ou de degré d'accomplissement d'objectifs ou de fonctions assignés à la forêt (Rondeux et Lecomte, 2005). S'il ne peut, compte tenu de l'échelle à laquelle il s'adresse et de la nature même des données récoltées, répondre à toutes les questions, il n'en demeure pas moins que l'inventaire comporte une gigantesque base de données multifonctionnelles géoréférencées essentiellement dendrométriques, écologiques et sylvicoles qui évolue au cours du temps et permet, de ce fait, un suivi de nos massifs et espaces forestiers. Sur plus de 15 ans, cet inventaire permanent a indéniablement joué un rôle important et sans cesse croissant en vue d'orienter et de définir une politique forestière appropriée aux caractéristiques de la forêt wallonne. Il a d'ailleurs été très souvent appelé à fournir quantité de données utiles à des prises de décision portant sur la gestion future des forêts. Aussi, il nous a paru opportun de faire le point sur les nombreux apports de cet outil d'autant qu'entre les objectifs ou missions qui lui avaient été fixés initialement et les domaines qu'il a progressivement abordés, il est vraisemblable que nombre d'acteurs du monde forestier n'ont pas forcément eu connaissance ou pris conscience de l'extrordinaire potentiel que revêt cet inventaire et des nombreuses sollicitations dont il a été l'objet depuis sa mise en oeuvre. Dans les lignes qui suivent nous ferons successivement le point sur les fondements méthodologiques de cet inventaire (paragraphe 1), les problématiques potentiellement couvertes par l'outil (paragraphe 2) et la nature des données récoltées (paragraphe 3). [less ▲]

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