Last 7 days
Bookmark and Share    
Full Text
See detailMeasuring and modelling the intra-day variability of the CO2 & CO2 vertical soil profile production in a Scots pine forest
Longdoz, Bernard; Goffin, Stéphanie; Parent, Florian et al

in Geophysical Research Abstracts (2015, April), 17

Detailed reference viewed: 10 (0 ULg)
Full Text
See detailThe CROSTVOC project – an integrated approach to study the effect of stress on BVOC exchange between agricultural crops and grassland ecosystems and the atmosphere
Amelynck, Crist; Heinesch, Bernard ULg; Aubinet, Marc ULg et al

in Geophysical Research Abstracts (2015, April), 17

Global changes in atmospheric composition and climate are expected to affect BVOC exchange between terrestrial vegetation and the atmosphere through changes in the drivers of constitutive BVOC emissions ... [more ▼]

Global changes in atmospheric composition and climate are expected to affect BVOC exchange between terrestrial vegetation and the atmosphere through changes in the drivers of constitutive BVOC emissions and by increases in frequency and intensity of biotic or abiotic stress episodes. Indeed, several studies indicate changes in the emission patterns of constitutive BVOCs and emission of stress-induced BVOCs following heat, drought and oxidative stress, amongst others. Relating changes in BVOC emissions to the occurrence of one or multiple stressors in natural environmental conditions is not straightforward and only few field studies have dealt with it, especially for agricultural crop and grassland ecosystems. The CROSTVOC project aims to contribute in filling this knowledge gap in three ways. Firstly, it aims at performing long-term BVOC emission field measurements from maize (Zea mays L.) and wheat (Triticum aestivum L.), two important crop species on the global scale, and from grassland. This should lead to a better characterization of (mainly oxygenated) BVOC emissions from these understudied ecosystems, allowing a better representation of those emissions in air quality and atmospheric chemistry and transport models. BVOC fluxes are obtained by the Disjunct Eddy Covariance by mass scanning (DEC-MS) technique, using a hs-PTR-MS instrument for BVOC analysis. Secondly, the eddy covariance BVOC flux measurements (especially at the grassland site) will be accompanied by ozone flux, chlorophyll fluorescence, photosynthesis and soil moisture measurements, amongst others, to allow linking alterations in BVOC emissions to stress episodes. Simultaneously, automated dynamic enclosures will be deployed in order to detect specific abiotic and biotic stress markers by PTR-MS and identify them unambiguously by GC-MS. Thirdly, the field measurements will be accompanied by laboratory BVOC flux measurements in an environmental chamber in order to better disentangle the responses of the BVOC emissions to driving factors that co-occur in field conditions and to determine the influence of single abiotic stressors on BVOC emissions. Next to a general presentation, some preliminary results of the project will be shown. [less ▲]

Detailed reference viewed: 15 (1 ULg)
Full Text
See detailImproving energy partitioning and the nighttime energy balance by implementation of a multi-layer energy budget in ORCHIDEE-CAN
Chen, Yiying; Ryder, James; Naudts, Kim et al

in Geophysical Research Abstracts (2015, April), 17

Canopy structure is one of the most important vegetation characteristics for land-atmosphere interactions as it determines the energy and scalar exchanges between land surface and overlay air mass. In ... [more ▼]

Canopy structure is one of the most important vegetation characteristics for land-atmosphere interactions as it determines the energy and scalar exchanges between land surface and overlay air mass. In this study we evaluated the performance of a newly developed multi-layer energy budget (Ryder et al., 2014) in a land surface model, ORCHIDEE-CAN (Naudts et al., 2014), which simulates canopy structure and can be coupled to an atmospheric model using an implicit procedure. Furthermore, a vertical discrete drag parametrization scheme was also incorporated into this model, in order to obtain a better description of the sub-canopy wind profile simulation. Site level datasets, including the top-of-the-canopy and sub-canopy observations made available from eight flux observation sites, were collected in order to conduct this evaluation. The geo-location of the collected observation sites crossed climate zones from temperate to boreal and the vegetation types included deciduous, evergreen broad leaved and evergreen needle leaved forest with maximum LAI ranging from 2.1 to 7.0. First, we used long-term top-of-the-canopy measurements to analyze the performance of the current one-layer energy budget in ORCHIDEE-CAN. Three major processes were identified for improvement through the implementation of a multi-layer energy budget: 1) night time radiation balance, 2) energy partitioning during winter and 3) prediction of the ground heat flux. Short-term sub-canopy observations were used to calibrate the parameters in sub-canopy radiation, turbulence and resistances modules with an automatic tuning process following the maximum gradient of the user-defined objective function. The multi-layer model is able to capture the dynamic of sub-canopy turbulence, temperature and energy fluxes with imposed LAI profile and optimized parameter set at a site level calibration. The simulation result shows the improvement both on the nighttime energy balance and energy partitioning during winter and presents a better Taylor skill score, compared to the result from single layer simulation. The importance of using the multi-layer energy budget in a land surface model for coupling to the atmospheric model will also be discussed in this presentation. [less ▲]

Detailed reference viewed: 20 (0 ULg)
Full Text
See detailModelling carbon fluxes of forest and grassland ecosystems in Western Europe using the CARAIB dynamic vegetation model: evaluation against eddy covariance data.
Henrot, Alexandra-Jane ULg; François, Louis ULg; Dury, Marie ULg et al

in Geophysical Research Abstracts (2015, April), 17

Eddy covariance measurements are an essential resource to understand how ecosystem carbon fluxes react in response to climate change, and to help to evaluate and validate the performance of land surface ... [more ▼]

Eddy covariance measurements are an essential resource to understand how ecosystem carbon fluxes react in response to climate change, and to help to evaluate and validate the performance of land surface and vegetation models at regional and global scale. In the framework of the MASC project (« Modelling and Assessing Surface Change impacts on Belgian and Western European climate »), vegetation dynamics and carbon fluxes of forest and grassland ecosystems simulated by the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) are evaluated and validated by comparison of the model predictions with eddy covariance data. Here carbon fluxes (e.g. net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (RECO)) and evapotranspiration (ET) simulated with the CARAIB model are compared with the fluxes measured at several eddy covariance flux tower sites in Belgium and Western Europe, chosen from the FLUXNET global network (http://fluxnet.ornl.gov/). CARAIB is forced either with surface atmospheric variables derived from the global CRU climatology, or with in situ meteorological data. Several tree (e.g. Pinus sylvestris, Fagus sylvatica, Picea abies) and grass species (e.g. Poaceae, Asteraceae) are simulated, depending on the species encountered on the studied sites. The aim of our work is to assess the model ability to reproduce the daily, seasonal and interannual variablility of carbon fluxes and the carbon dynamics of forest and grassland ecosystems in Belgium and Western Europe. [less ▲]

Detailed reference viewed: 25 (5 ULg)
Full Text
Peer Reviewed
See detailAnisotropy and tension-compression asymmetry modeling of the room temperature plastic response of Ti-6A1-4V
Tuninetti, Victor; Gilles, Gaëtan ULg; Pardoen, Thomas et al

in International Journal of Plasticity (2015), 67

The mechanical behavior of the alloy Ti-6A1-4V is characterized using uniaxial tension, uniaxial compression, simple shear and place strain tests in three orthogonal material directions. The experimental ... [more ▼]

The mechanical behavior of the alloy Ti-6A1-4V is characterized using uniaxial tension, uniaxial compression, simple shear and place strain tests in three orthogonal material directions. The experimental results reveal tension/compression asymmetry, anisotropic yielding and anisotropic strain-hardening. These features are incorporated into an elasto-plastic constitutive law based on the macroscopic orthotropic yield criterion "CPB06" adapted to hexagonal metals. A new identification method for the yield criterion parameters is proposed by inverse modeling of the axial strain field compression specimens in the three orthogonal directions of the material. The sensitivity of different sets of material parameters to the identification method is also analysed and the capacity of the model to accurately predict the forces and displacement field is discussed. A validation of the best set of identified CPB06material parameters is performed by comparing the load-displacement curves in different loading directions for tensile tests on notched round bars with different levels of stress triaxiality and for compression tests on elliptical cross-section specimens, both tests involving multiaxial strain fields and large deformations. [less ▲]

Detailed reference viewed: 30 (10 ULg)
Full Text
Peer Reviewed
See detailTracking Middleboxes in the Mobile World with TraceboxAndroid
Thirion, Valentin; Edeline, Korian ULg; Donnet, Benoît ULg

in 7th International Workshop on Traffic Monitoring and Analysis (TMA) (2015, April)

Middleboxes are largely deployed over cellular networks. It is known that they might disrupt network performance, expose users to security issues, and harm protocols deployability. Further, hardly any ... [more ▼]

Middleboxes are largely deployed over cellular networks. It is known that they might disrupt network performance, expose users to security issues, and harm protocols deployability. Further, hardly any network measurements tools for smartphones are able to infer middlebox behaviors, specially if one cannot control both ends of a path. In this paper, we present TraceboxAndroid a proof-of-concept measurement application for Android mobile devices implementing the tracebox algorithm. It aims at diagnosing middlebox-impaired paths by detecting and locating rewriting middleboxes. We analyze a dataset sample to highlight the range of opportunities offered by TraceboxAndroid. We show that TraceboxAndroid can be useful for mobile users as well as for the research community. [less ▲]

Detailed reference viewed: 49 (2 ULg)
Full Text
Peer Reviewed
See detailThe words of prevention, part II: ten terms in the realm of quaternary prevention
Jamoulle, Marc ULg; Gavilan, Enrique; Cardoso, Raquel Val et al

in Revista Brasileira de Medicina de Família e Comunidade (2015)

ABSTRACT Objective: This part II article about the ‘words of prevention’ presents in a terminological way the content of ten current concepts used in the prevention domain which are closely linked to ... [more ▼]

ABSTRACT Objective: This part II article about the ‘words of prevention’ presents in a terminological way the content of ten current concepts used in the prevention domain which are closely linked to quaternary prevention: (1) overinformation, (2) overdiagnosis, (3) medically unexplained symptoms, (4) overmedicalisation, (5) incidentaloma, (6) overscreening, (7) overtreatment, (8) shared decision making, (9) deprescribing, and (10) disease mongering. Methods: with the support of the laboratory team of the University of Rouen, France, which is dedicated to medical terminology and semantic relationships, it was possible to utilize a graphic user interface (called DBGUI) allowing the construction of links for each of chosen terms, and making automatic links to MeSH, if any. Those concepts are analyzed in their environment in current literature, as well as in their MeSH counterparts, if any, and related semantic online terminologies. Results and Discussion: The rules in terminological development aspire to cover the whole field of a concept and in the meantime, it helps to avoid the noise due to proxy and not exactly related issues. This refers to exhaustivity and specificity in information retrieval. Our finds show that referring to MeSH only in information retrieval in General Practice/Family medicine can induce much noise and poor adequacy to the subject investigated. Conclusion: Gathering concepts in specially prepared terminologies for further development of ontologies is a necessity to enter in the semantic web area and the era of distributed data. [less ▲]

Detailed reference viewed: 206 (7 ULg)
Full Text
Peer Reviewed
See detailThe words of prevention, part I: changing the model
Jamoulle, Marc ULg; Gavilan, Enrique; Cardoso, Raquel Val et al

in Revista Brasileira de Medicina de Família e Comunidade (2015)

ABSTRACT Objective: This part I article explores the different meanings of relevant keywords for General Practice/Family Medicine (GP/FM) in the prevention domain. The aim is to contribute to information ... [more ▼]

ABSTRACT Objective: This part I article explores the different meanings of relevant keywords for General Practice/Family Medicine (GP/FM) in the prevention domain. The aim is to contribute to information process in GP/FM by keeping in line with the main terms used in health care organization. Methods: Important keywords for GP/FM in the prevention domain were selected. Then, a search was carried out on the main sources in GP/FM databases, as well as in Medical Subject Heading and major terminological databases available online. Results and Discussion: There is discrepancy between the conceptual contents of major prevention models amongst the usual bibliographic sources of knowledge in GP/FM in particular and medicine in general. Conclusion: For GP/FM, distribution of preventive activities is now firmly established on a new constructivist model, privileging the doctor-patient relationships and introducing a cybernetic thinking on the health care activities with a special commitment to ethics and the positive duty of beneficence. [less ▲]

Detailed reference viewed: 65 (5 ULg)
Full Text
Peer Reviewed
See detailPrevenção quaternária: primeiro não causar dano - Editorial
Jamoulle, Marc ULg

in Revista Brasileira de Medicina de Família e Comunidade (2015)

Detailed reference viewed: 22 (1 ULg)
Full Text
Peer Reviewed
See detailQuaternary prevention: first, do not harm - Editorial
Jamoulle, Marc ULg

in Revista Brasileira de Medicina de Família e Comunidade (2015)

Detailed reference viewed: 54 (0 ULg)
Full Text
See detailManuels de langues et risques d'inégalités
Simons, Germain ULg; Delbrassine, Daniel ULg; Van Hoof, Florence ULg

in Didactiques en pratique (2015), (1),

Dans cet article synthétique, les auteurs relèvent quelques caractéristiques de certains manuels de langues contemporains et démontrent en quoi celles-ci présentent des risques d'inégalités pour les ... [more ▼]

Dans cet article synthétique, les auteurs relèvent quelques caractéristiques de certains manuels de langues contemporains et démontrent en quoi celles-ci présentent des risques d'inégalités pour les apprenants [less ▲]

Detailed reference viewed: 22 (10 ULg)
Full Text
See detailEditorial du n°1 de la revue "Didactiques en pratique"
Simons, Germain ULg; Beckers, Jacqueline ULg; Poffé, Corentin ULg

in Didactiques en pratique (2015)

Ce premier éditorial de la nouvelle revue du Cifen :"Didactique en pratique" présente le contenu de ce numéro et propose une mise en perspective théorique de la problématique abordée lors de l'Université ... [more ▼]

Ce premier éditorial de la nouvelle revue du Cifen :"Didactique en pratique" présente le contenu de ce numéro et propose une mise en perspective théorique de la problématique abordée lors de l'Université d'été 2014 : "Outils didactiques et (in)égalités". Ce premier numéro est principalement consacré à la publication des Actes de l'Université d'été 2014, mais il évoque aussi la première journée de rencontre officielle entre le Cifen et les maitres de stages. [less ▲]

Detailed reference viewed: 11 (2 ULg)
Full Text
Peer Reviewed
See detailThe Fish Migrate and so Must We': the Relationship between International and Internal Environmental Mobility in a Senegalese Fishing Community
Zickgraf, Caroline ULg

Conference (2015, April)

In 2008, the UN designated Saint-Louis “the city most threatened by rising sea levels in the whole of Africa”. The people of Guet Ndar, a densely populated fishing quarter, are coping with environmental ... [more ▼]

In 2008, the UN designated Saint-Louis “the city most threatened by rising sea levels in the whole of Africa”. The people of Guet Ndar, a densely populated fishing quarter, are coping with environmental challenges on two fronts: 1) coastal erosion and intensifying storms have destroyed sea-front homes, and, 2) overfishing and climate change’s maritime impacts are making local fishing less feasible as a livelihood strategy. Based on a local case study, this paper examines Guet Ndarian migration as an adaptive response to environmental risks and more specifically climate change: 1) through the intensification of fishing migration to Mauritania, and 2) through home construction on the mainland away from the encroaching sea. Although these population movements respond to different environmental challenges, this paper identifies their enmeshment as the former facilitates the latter. Furthermore, it embeds these migratory dynamics in their socio-economic context and applies mobility and transnational paradigms to environmentally vulnerable areas. [less ▲]

Detailed reference viewed: 17 (3 ULg)
Full Text
See detailMise en perspective de l'après-midi de rencontre avec les maîtres de stages du Cifen
Simons, Germain ULg

in Didactiques en pratique (2015), 1

Ce texte est le discours du Président du Cifen qui a été prononcé à l'occasion de la première journée officielle de rencontre entre le Centre et les maitres de stages (5 novembre 2014). Ce discours ... [more ▼]

Ce texte est le discours du Président du Cifen qui a été prononcé à l'occasion de la première journée officielle de rencontre entre le Centre et les maitres de stages (5 novembre 2014). Ce discours succinct reprend la question qui a servi de fil rouge à cette journée : "Comment collaborer efficacement pour accompagner au mieux nos stagiaires ?" et en détaille chaque composante. [less ▲]

Detailed reference viewed: 24 (10 ULg)
Full Text
Peer Reviewed
See detailGAIMS: a tool specifically developed for the clinical gait analysis of patients with multiple sclerosis
Pierard, Sébastien ULg; Phan-Ba, Rémy; Giet, Amaury et al

Poster (2015, April)

Detailed reference viewed: 20 (3 ULg)
Full Text
See detailDoes the soil’s effective hydraulic conductivity adapt in order to obey the Maximum Entropy Production principle? A lab experiment
Westhoff, Martijn ULg; Zehe, Erwin; Erpicum, Sébastien ULg et al

Conference (2015, April)

The Maximum Entropy Production (MEP) principle is a conjecture assuming that a medium is organized in such a way that maximum power is subtracted from a gradient driving a flux (with power being a flux ... [more ▼]

The Maximum Entropy Production (MEP) principle is a conjecture assuming that a medium is organized in such a way that maximum power is subtracted from a gradient driving a flux (with power being a flux times its driving gradient). This maximum power is also known as the Carnot limit. It has already been shown that the atmosphere operates close to this Carnot limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state close to the Carnot limit, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells (e.g. wind). The aim of this study is to test if the soil’s effective hydraulic conductivity also adapts itself in such a way that it operates close to the Carnot limit. The big difference between atmosphere and soil is the way of adaptation of its resistance. The soil’s hydraulic conductivity is either changed by weathering processes, which is a very slow process, or by creation of preferential flow paths. In this study the latter process is simulated in a lab experiment, where we focus on the preferential flow paths created by piping. Piping is the process of backwards erosion of sand particles subject to a large pressure gradient. Since this is a relatively fast process, it is suitable for being tested in the lab. In the lab setup a horizontal sand bed connects two reservoirs that both drain freely at a level high enough to keep the sand bed always saturated. By adding water to only one reservoir, a horizontal pressure gradient is maintained. If the flow resistance is small, a large gradient develops, leading to the effect of piping. When pipes are being formed, the effective flow resistance decreases; the flow through the sand bed increases and the pressure gradient decreases. At a certain point, the flow velocity is small enough to stop the pipes from growing any further. In this steady state, the effective flow resistance of the sand bed will be compared with the theoretical optimal flow resistance obtained with the MEP principle. For this study, different magnitudes of the forcing will be tested, while also the effect of dry spells will be explored. [less ▲]

Detailed reference viewed: 13 (3 ULg)
Full Text
Peer Reviewed
See detailTeaching and learning Quaternary prevention
Gomes, Luis Enrique; Gusso, Gustavo; Jamoulle, Marc ULg

in Revista Brasileira de Medicina de Família e Comunidade (2015)

This article presents an overview of different techniques and skills required for teaching and learning quaternary prevention (P4). It adopts the Expertise Model that defines the competences required in ... [more ▼]

This article presents an overview of different techniques and skills required for teaching and learning quaternary prevention (P4). It adopts the Expertise Model that defines the competences required in P4 for each level: novice, competent, proficient, and expert. This should be used as a step-wise roadmap for teachers in order to achieve high standard levels of performance. This is complemented by a list of methods used in teaching and assessment of learners’ performance and competence. By covering a range of learning and teaching issues, those who aim to teach quaternary prevention can explore the proposed framework. Quaternary prevention is a research and teaching fertile medical field that requires the integration of different areas such as health service organization, epidemiology, communication skills, and andragogy either at the macro or the micro levels health related activities. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
Peer Reviewed
See detailClimatic risk assessment to improve nitrogen fertilisation recommendations : A strategic crop model-based approach
Dumont, Benjamin ULg; Basso, Bruno; Bodson, Bernard ULg et al

in European Journal of Agronomy (2015), 65(10-17),

Within the context of nitrogen (N) management, since 1950, with the rapid intensification of agriculture, farmers have often applied much larger fertiliser quantities than what was required to reach the ... [more ▼]

Within the context of nitrogen (N) management, since 1950, with the rapid intensification of agriculture, farmers have often applied much larger fertiliser quantities than what was required to reach the yield potential. However, to prevent pollution of surface and groundwater induced by nitrates, The European Community launched The European Nitrates Directive 91/6/76/EEC. In 2002, in Wallonia (Belgium), the Nitrates Directive has been transposed under the Sustainable Nitrogen Management in Agriculture Program (PGDA), with the aim of maintaining productivity and revenue for the country’s farmers, while reducing the environmental impact of excessive N application. A feasible approach for addressing climatic uncertainty lies in the use of crop models such as the one commonly known as STICS (simulateur multidisciplinaire pour les cultures standard). These models allow the impact on crops of the interaction between cropping systems and climatic records to be assessed. Comprehensive historical climatic records are rare, however, and therefore the yield distribution values obtained using such an approach can be discontinuous. In order to obtain better and more detailed yield distribution information, the use of a high number of stochastically generated climate time series was proposed, relying on the LARS-Weather Generator. The study focused on the interactions between varying N practices and climatic conditions. Historically and currently, Belgian farmers apply 180 kg N ha−1, split into three equal fractions applied at the tillering, stem elongation and flag-leaf stages. This study analysed the effectiveness of this treatment in detail, comparing it to similar practices where only the N rates applied at the flag-leaf stage were modified. Three types of farmer decision-making were analysed. The first related to the choice of N strategy for maximising yield, the second to obtaining the highest net revenue, and the third to reduce the environmental impact of potential N leaching, which carries the likelihood of taxation if inappropriate N rates are applied. The results showed reduced discontinuity in the yield distribution values thus obtained. In general, the modulation of N levels to accord with current farmer practices showed considerable asymmetry. In other words, these practices maximised the probability of achieving yields that were at least superior to the mean of the distribution values, thus reducing risk for the farmers. The practice based on applying the highest amounts (60–60–100 kg N ha−1) produced the best yield distribution results. When simple economical criteria were computed, the 60–60–80 kg N ha−1 protocol was found to be optimal for 80–90% of the time. There were no statistical differences, however, between this practice and Belgian farmers’ current practice. When the taxation linked to a high level of potentially leachable N remaining in the soil after harvest was considered, this methodology clearly showed that, in 3 years out of 4, 30 kg N ha−1 could systematically be saved in comparison with the usual practice. [less ▲]

Detailed reference viewed: 10 (0 ULg)