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See detailLong-term XMM-Newton investigation of two particle-accelerating colliding-wind binaries in NGC6604: HD168112 and HD167971
De Becker, Michaël ULg

in Monthly Notices of the Royal Astronomical Society (2015), 451(1), 5589-5599

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking ... [more ▼]

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking into account recent information about their multiplicity and orbital parameters. The two targets, HD168112 and HD167971 appear to be overluminous in X-rays, lending additional support to the idea that a significant contribution of the X-ray emission comes from colliding-wind regions. The variability of the X-ray flux from HD168112 is interpreted in terms of varying separation expected to follow the 1/D rule for adiabatic shocked winds. For HD167971, marginal decrease of the X-ray flux in September 2002 could tentatively be explained by a partial wind eclipse in the close pair. No long-term variability could be demonstrated despite the significant difference of separation between 2002 and 2014. This suggests the colliding-wind region in the wide orbit does not contribute a lot to the total X-ray emission, with a main contribution coming from the radiative shocked winds in the eclipsing pair. The later result provides evidence that shocks in a colliding-wind region may be efficient particle accelerators even in the absence of bright X-ray emission, suggesting particle acceleration may operate in a wide range of conditions. Finally, in hierarchical triple O-type systems, thermal X-rays do not necessarily constitute an efficient tracer to detect the wind-wind interaction in the long period orbit. [less ▲]

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See detailSelective top-down control of epiphytic biomass by amphipods from Posidonia oceanica meadows: implications for ecosystem functioning
Michel, Loïc ULg; Dauby, Patrick ULg; Dupont, Alessandra et al

in Belgian Journal of Zoology (2015), 145(2), 83-93

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional ... [more ▼]

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the dominant taxa of the amphipod community (Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp.) could exert top-down control on seagrass leaf epiphytes. Influence of amphipod activity on nutrient availability for the host species was also investigated. All grazer taxa significantly reduced biomasses of erect macroalgae and erect sessile animals present on leaves. None of them consumed encrusting epiflora or epifauna. This selective top-down control could have important implications for the structure of the epiphytic community of P. oceanica leaves, which is one of the most diverse and abundant of all seagrass species. Grazing activity of all taxa caused higher N content of seagrass leaves, likely through amphipod excretion and/or sloppy feeding. Since P. oceanica meadows often grow in oligotrophic zones where plant growth can be nutrient-limited, this N enrichment could enhance seagrass production. Overall, the ecological interaction between P. oceanica and amphipods could be seen as a facultative mutualistic relationship. Our results suggest that amphipod mesograzers are key-elements in some of the functional processes regulating these complex and yet endangered ecosystems, which are essential components of Mediterranean coastal zones. [less ▲]

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See detailSpectroscopic survey of Kepler stars. I. HERMES/Mercator observations of A- and F-type stars
Niemczura, E.; Murphy, S. J.; Smalley, B. et al

in Monthly Notices of the Royal Astronomical Society (2015), 450

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally ... [more ▼]

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally important to have accurate stellar physical parameters. Therefore, supplementary ground-based data are needed. We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field, which were obtained with the HERMES spectrograph on the Mercator telescope. We determined spectral types, atmospheric parameters and chemical abundances for a sample of 117 stars. Hydrogen Balmer, Fe I, and Fe II lines were used to derive effective temperatures, surface gravities, and microturbulent velocities. We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique. The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue (KIC), confirming that the KIC effective temperatures are underestimated for A stars. Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis. The analysed sample comprises stars with approximately solar chemical abundances, as well as chemically peculiar stars of the Am, Ap, and Lambda Boo types. The distribution of the projected rotational velocity, Vsini, is typical for A and F stars and ranges from 8 to about 280 km/s, with a mean of 134 km/s. [less ▲]

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See detailReinforcement Learning of Heuristic EV Fleet Charging in a Day-Ahead Electricity Market
Vandael, Stijn; Claessens, Bert; Ernst, Damien ULg et al

in IEEE Transactions on Smart Grid (2015), 6(4), 1795-1805

This paper addresses the problem of defining a day-ahead consumption plan for charging a fleet of electric vehicles (EVs), and following this plan during operation. A challenge herein is the beforehand ... [more ▼]

This paper addresses the problem of defining a day-ahead consumption plan for charging a fleet of electric vehicles (EVs), and following this plan during operation. A challenge herein is the beforehand unknown charging flexibility of EVs, which depends on numerous details about each EV (e.g., plug-in times, power limitations, battery size, power curve, etc.). To cope with this challenge, EV charging is controlled during opertion by a heuristic scheme, and the resulting charging behavior of the EV fleet is learned by using batch mode reinforcement learning. Based on this learned behavior, a cost-effective day-ahead consumption plan can be defined. In simulation experiments, our approach is benchmarked against a multistage stochastic programming solution, which uses an exact model of each EVs charging flexibility. Results show that our approach is able to find a day-ahead consumption plan with comparable quality to the benchmark solution, without requiring an exact day-ahead model of each EVs charging flexibility. [less ▲]

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See detailLate Holocene history of the Fuji Five Lakes (Japan)
Lamair, Laura ULg; Hubert, Aurelia ULg; Boes, Evelien et al

Conference (2015, July)

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See detailEtude de l'évolution de l'enneigement dans les Hautes Fagnes (Belgique) au cours des cinquante dernières années à l'aide du modèle climatique régional MAR
Wyard, Coraline ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

in Erpicum, Michel (Ed.) Actes du XXVIIIe colloque annuel de l’Association Internationale de Climatologie : Modélisations et variabilités (2015, July)

The “Modèle Atmosphérique Régionale” MAR is a regional climate model originally developed to study the polar ice sheets. In this study, the MAR model has been adapted to Belgium in order to study the snow ... [more ▼]

The “Modèle Atmosphérique Régionale” MAR is a regional climate model originally developed to study the polar ice sheets. In this study, the MAR model has been adapted to Belgium in order to study the snow cover evolution of the High Fens (east of Belgium), a region covered by snow on average one to two months per year. As validation, we have sucessfully compared MAR based daily snow heights with snowcam-based and/or laser sensor-based observations over the period 2008-2013. Then, the model has been forced by ERA-Interim since 1958 to study the snow cover evolution during the last fifty years at the summit of Belgium. The results show no significant trend despite global warming. [less ▲]

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See detailGlucosinolates and by-products in rapeseed meal related to hydrothermal processing
Quinsac, A.; Carré, P.; Fauconnier, Marie-Laure ULg et al

Poster (2015, July)

Background: For safety reasons, rapeseed meal (RSM) is usually desolventized with strong hydrothermal treatments, leading to various levels of residual glucosinolates (GSL), and protein solubility. The ... [more ▼]

Background: For safety reasons, rapeseed meal (RSM) is usually desolventized with strong hydrothermal treatments, leading to various levels of residual glucosinolates (GSL), and protein solubility. The RSM nutritional quality may be then lowered for monogastrics, due to GSL breakdown products whose reliable and “easy to use” indicators lack. [less ▲]

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See detailiPot: Industrial Potato monitoring for the Belgian potato sector using remote sensing and crop growth modelling
Wellens, Joost ULg

in Qu, Dongyu (Ed.) Develop Together for a Better Future (2015 Beijing World Potato Congress) (2015, July)

The Belgian potato processing industry has known a spectacular growth during the last decades. The companies active in this sector (most of them family owned enterprises) have succeeded – together with ... [more ▼]

The Belgian potato processing industry has known a spectacular growth during the last decades. The companies active in this sector (most of them family owned enterprises) have succeeded – together with primary producers and traders – to grow from 500.000 tons of processed potatoes in 1990 till 3.650.000 tons of raw material in 2012. When considering the production (in tons) per habitant, Belgium is ranked on the 4th place with a production of 395 tons per 1.000 inhabitants. Nowhere in the world are higher yields obtained than in Belgium. To keep up its position on the forefront of innovation, the potato processing industries are continuously looking at promising novel technologies that could improve business processes at any stage of growth. The close follow up of parcels on the land as form above is becoming an important tool to improve the quantity and the quality of the potato crop, and reduce the risks in order to plan the storage, packaging or processing and as such to strengthen the competiveness of the Belgian potato in a global market. The iPot project, financed by the Belgian Science Policy Office (BELSPO), aims to provide the Belgian potato sector, represented by Belgapom, with near real time information on field condition (weather-soil) and crop development, and with early yield estimates, derived from a combination of satellite images and crop growth models. Satellite images are used since long for crop monitoring at regional level by the public sector. Traditionally, low to medium resolution images, with pixel sizes from 250m to 1km are used for providing information on crop growth and development, and on yield at regional scale. However, the recent launch of constellations of high resolution optical sensors (DMC, Sentinel-2) offering spatially detailed information (20m pixel size) at high frequency (every 2 to 3 days) and at low cost, is creating a (r)evolution in the world of crop monitoring. Automatic processing chains have been developed to derive vegetation indices (NDVI) and biophysical parameters (fAPAR, LAI, fCover). Maps are being derived on a regular basis with for each pixel the actual development stage of the potato crop. This on-line scanning of the growth (phenology) is expected to result in an increased performance of crop growth models and better yield predictions. Once the data for crop phenology are incorporated into the model (B-CGMS), the yield data collected at the parcel level will be assimilated into the model using optimization algorithms to minimize the discrepancies between observed and simulated yield time series in order to improve further yield estimations. The combination of these new earth observation and modelling techniques arose the interest of a new type of users, mainly from the private sector (agro-industry, agricultural insurers, etc.). The iPot project aims to bridge the gap between the latest research efforts regarding crop growth monitoring and the industry. An intuitive web based geo-information platform is being developed to allow both the Belgian potato industry and research centers to access, analyze and combine the data with their own field observations in closed collaboration with the farmers, for improved decision-making. [less ▲]

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See detailMetal bioavailability and bioaccumulation in the polychaete Nereis virens (Sars): the effects of site-specific sediment characteristics
Pini, Jennifer; Richir, Jonathan ULg; Watson, Gordon

in Marine Pollution Bulletin (2015), 95(2), 565575

The present study investigates the relationships between copper (Cu) and zinc (Zn) concentrations in sediment, pore water and their bioaccumulation in the polychaete Nereis (Alitta) virens, as well as the ... [more ▼]

The present study investigates the relationships between copper (Cu) and zinc (Zn) concentrations in sediment, pore water and their bioaccumulation in the polychaete Nereis (Alitta) virens, as well as the importance of site-specific sediment characteristics in that process. Sediment, pore water and N. virens were sampled from seven sites with different pollution histories along the English Channel coast. Results showed that site-specific metal levels and sediment characteristics were important in determining the bioavailability of metals to worms. Significant correlations were found between Cu in the sediment and in the pore water and between Zn in the pore water and in N. virens. Zn from the pore water was thus more readily available from a dissolved source to N. virens than Cu. Data also showed that metal concentrations in N. virens were lower than those found in other closely related polychaetes, indicating that it may regulate tissue concentrations of Cu and Zn. [less ▲]

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See detailUsing 2D-PIV measurements to compute unsteady aerodynamic loads on a flat plate at high angle of attack
Guissart, Amandine ULg; Bernal, Luis; Dimitriadis, Grigorios ULg et al

in Proceedings of the 16th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2015 (2015, June 30)

This work exposes and discusses results obtained for aerodynamic forces using an indirect calculation based on Particle Image Velocimetry (PIV) measurements. The methodology used is based on the integral ... [more ▼]

This work exposes and discusses results obtained for aerodynamic forces using an indirect calculation based on Particle Image Velocimetry (PIV) measurements. The methodology used is based on the integral formulation of the Navier-Stokes equations and is applied to spatio-temporal data for different flows around a plate with a 16:1 chord-to-thickness ratio at high angle of attack. Experimental data are obtained in a water channel for both a static and a pitching plate. In addition to PIV data, direct measurements of aerodynamic loads are carried out to assess the quality of the indirect calculation. It is demonstrated that this indirect method is able to compute the mean and the temporal evolution of the lift and drag coefficients with a reasonable accuracy. It is also shown that the noise sensitivity of the method can be partly alleviated through the use of Dynamic Mode Decomposition (DMD) as a pre-processing step to smooth the spatio-temporal data. [less ▲]

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See detailBilan bactériologique des mammites dans les troupeaux Zébu Azawak à la station expérimentale sahélienne de Toukounous (Niger) et épidémiologie moléculaire des Staphylococcus aureus isolés entre 2009 et 2012
Issa Ibrahim, Abdoulkarim ULg

Doctoral thesis (2015)

L’élevage est la seconde activité principale après l’agriculture au Niger. Cependant, ce secteur est confronté à d’énormes problèmes, notamment la faible productivité des animaux, le faible investissement ... [more ▼]

L’élevage est la seconde activité principale après l’agriculture au Niger. Cependant, ce secteur est confronté à d’énormes problèmes, notamment la faible productivité des animaux, le faible investissement, des problèmes d’alimentation et d’accès aux points d’eau, et divers problèmes sanitaires récurrents. Depuis l’indépendance du pays en 1960, plusieurs politiques ont été mises en œuvre pour améliorer la productivité des espèces et races domestiques locales. C’est ainsi que, la station expérimentale sahélienne de Toukounous a vu le jour, avec comme objectifs la sélection et la diffusion de la race Zébu Azawak auprès des producteurs ruraux. Les efforts de sélection ont abouti à l’obtention d’un animal standard bien adapté au contexte sahélien avec un niveau de production en lait acceptable. Le bétail laitier à travers le monde souffre énormément des problèmes sanitaires liés aux infections de la glande mammaire. La situation est la même à Toukounous malgré la proximité de services vétérinaires et para-vétérinaires. Cependant, au Niger de manière générale, les données sur les mammites sont rares et très peu de publications scientifiques sont disponibles. Une des possibles explications est la prévalence élevée de mammites sub-cliniques, mais faible de mammites cliniques. La présente étude est dès lors centrée sur les problèmes de mammites au sein de la station sahélienne expérimentale de Toukounous afin d’identifier : (i) les vaches souffrant de mammites cliniques et/ou subcliniques ; (ii) les principales bactéries pathogènes responsables ; et (iii) les virulotypes et profils de résistance aux antibiotiques des souches de Staphylococcus (S.) aureus isolées ; et afin de démontrer l’impact positif de l’application de mesures simples d’hygiène lors de la traite manuelle sur la prévalence de vaches avec mammite. De 2009 à 2012, l’ensemble des vaches en lactation des trois troupeaux de la station, à savoir « élites », « non-élites » et « primipares » ont été testées avec le « California Mastitis Test » (CMT). Ensuite, le lait de tous les quartiers des vaches ayant réagi positivement au test CMT a été prélevé pour réaliser des analyses bactériologiques au Niger. Les espèces bactériennes pré-identifiées au Niger ont ensuite été importées en Belgique (ULg-FMV) afin de procéder à une identification complète par des galeries API®. Les souches confirmées de S. aureus ont par la suite été étudiées pour leurs virulotypes (i) phénotypiquement pour la production de biofilm par mesure de la densité optique après croissance en milieu liquide en plaque de microtitration et pour la synthèse d’une capsule par un test ELISA ; et (ii) génétiquement par PCR ciblant des gènes codant pour différentes propriétés de virulence (adhésines, leucotoxines, entérotoxines, biofilm, et capsule) ; ainsi que pour leurs profils de résistance aux antibiotiques par le test de diffusion en gélose, ou antibiogramme. Ces mêmes souches ont été comparées par leurs empreintes génétiques après « Pulsed Field Gel Electrophoresis » (PFGE), ou pulsotypes, pour en étudier la clonalité au cours des 4 années de l’enquête et dans les 3 troupeaux. Enfin, l’impact de mesures d’hygiène (lavage et désinfection du pis, des trayons et des mains des trayeurs avant et/ou après chaque traite) a été évalué en 2011 et en 2012, en comparant la prévalence de vaches positives au test CMT et l’identité des bactéries isolées en présence ou en absence de ces mesures. Au cours de la première étude en 2009 sur la prévalence des vaches positives au test CMT et l’identité des bactéries mammopathogènes, 104 des 265 vaches (39%) testées dans l’ensemble des 3 troupeaux étaient positives au test CMT, bien qu’aucune mammite clinique n’ait été diagnostiquée. Les analyses bactériologiques ont identifié 55 souches bactériennes: la moitié (51%) appartient au genre Staphylococcus, essentiellement à l’espèce S. aureus (42%). Les autres bactéries identifiées appartiennent à la famille des Enterobacteriaceae (26%) et aux genres Enterococcus (13%), Bacillus (9%) et Acinetobacter (2%). Des résultats similaires ont été obtenus en 2010, 2011 et 2012, bien que les pourcentages respectifs puissent varier selon l’année et le troupeau. Les résultats des tests phénotypiques et génétiques du virulotypage (études 1 et 3) des 122 souches de S. aureus isolées de 2009 à 2012 dans les trois troupeaux n’ont permis d’effectuer aucun regroupement. Par contre, les résultats des empreintes génétiques par PFGE sur ces mêmes souches ont montré qu’elles appartiennent à 16 pulsotypes différents, dont trois sont plus fréquents, A (33%), D (23%) et B (21%). Ces différents pulsotypes se distinguent, dans une certaine mesure, par la présence plus fréquentes des gènes icaA, spa et cap5H dans les souches des pulsotypes A et B ; des gènes cap8H, seg, sei et seb dans celles du pulsotype D ; et du gène luks-PV dans celles des pulsotypes B et D. Pour ce qui concerne les antibiogrammes des mêmes 122 souches (études 1 et 2 + résultats non publiés), des pourcentages élevés de souches résistantes de S. aureus, particulièrement aux -lactamines, ont été relevés. Ainsi, 41% des souches testées étaient résistantes à la pénicilline et 7%, à l’oxacilline. Mais, aucune souche résistante à la méticilline (SARM) ne possède le gène mecA. Les pourcentages de souches résistantes atteignaient 11% pour la tétracycline et la gentamicine, mais restaient inférieurs à 5% pour la clindamycine, l’association trimétoprime-sulfaméthoxazole et l’enrofloxacine. Pour la 4ème étude en 2011 et 2012, les mesures d’hygiène ont été appliquées pendant 6 mois : lavage du pis avant la traite, trempage des trayons avec de la chlorhexidine après la traite, et lavage et désinfection des mains des trayeurs avec une solution antiseptique à base d’hypochlorite de sodium. L’application de ces mesures a diminué de manière statistiquement significative les pourcentages de vaches positives au test CMT en comparaison avec les résultats dans les troupeaux et au cours des années sans application de ces mêmes mesures d’hygiène. En 2012, par exemple, les pourcentages de vaches positives au CMT dans les troupeaux « élite » et « non-élite » ont diminué de 65% et 62%, à 44% et 41% après trois mois d’application, puis à 20% et 24% après 6 mois d’application, respectivement. Par contre, ces mesures d’hygiène n’ont eu aucun effet statistiquement significatif sur les pourcentages relatifs des différents pathogènes identifiés. En conclusion, les mammites bovines sévissent essentiellement sous forme sub-clinique à la station sahélienne de Toukounous. Le genre Staphylococcus et l’espèce S. aureus sont les bactéries mammopathogènes les plus fréquemment identifiées. Les souches de S. aureus appartiennent à différents virulotypes et pulsotypes, bien que trois de ces derniers soient plus fréquents dans les trois troupeaux et au cours des quatre années de l’étude. Ces mêmes souches présentent différents profils de résistance aux antibiotiques, avec près de la moitié d’entre elles résistantes à des membres de la famille de -lactames. Enfin, l’application de mesures d’hygiène (lavage et désinfection du pis, des trayons et des mains des trayeurs) avant et/ou après la traite manuelle permet de réduire la prévalence des vaches positives au test CMT de manière statistiquement significative, mais n’a pas d’influence sur les fréquences relatives des bactéries pathogènes identifiées dans les laits. [less ▲]

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See detailWild boar movement ecology across scales: Insights from a population expanding into agroecosystems of Southern Belgium
Morelle, Kevin ULg

Doctoral thesis (2015)

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until ... [more ▼]

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until recently, ungulates have progressively adapted to these modi cations and are now able to cope with human-shaped environments, consequently their number and range have greatly and worryingly increased. More particularly, among ungulates species, the wild boar Sus scrofa raises important concerns due to its environmental, economic and social impacts on modern societies. Understanding the ecology of ungulates species and their ability to survive within highly dynamic and seasonal ecosystems, such as agricultural environment, is thus necessary to better mitigate their negative impacts and to sustainably manage growing and expanding populations. Although only recently studied, movement ecology of animal is an important species trait that allows animal to adapt to rapid environmental changes. Considering movement as the resulting interaction of the animal’s internal state, navigation and motion capacity as well as of the e ect of the surrounding environment (“external factors”), provides a clear conceptual framework enabling to study patterns, mechanisms and processes, such as coping with land-use changes. In this thesis, we study the case of an expanding wild boar population in Southern Belgium and consider the movement ecology of the species to understand how wild boar colonize and ourish in agroecosystems. More speci cally, the thesis aims at i) reviewing quantitatively and qualitatively the scienti c literature about wild boar movement ecology, and ii) analyzing the spatial response of wild boar to agroecosystems in terms of movement and habitat selection across three spatial and temporal scales. The literature review highlights that wild boar is the least studied ungulates species in terms of movement ecology.We suggest that this is likely due i) to the relative complexity of tting tracking devices to this species, and ii) to its generalist diet making the species not suitable to test foraging hypotheses. Among existing studies, a large part focuses on the role of external factors (e.g. hunting, landscape features) on movement while others components of the movement ecology framework (internal state, navigation and motion capacity) remain poorly studied. However, when assuming behavioral similarity between wild and domestic boars, experimental studies on captive animals show how wild boar can develop complex movement strategies by using their highly developed cognitive and sensory abilities, and spatial memory. The spatio-temporal analysis suggests a scale-speci c response of wild boar to agricultural habitat. At the intermediate scale (landscape, seasonal), wild boar uses seasonal habitat shift strategies towards agricultural areas, while at broader scale (regional, decades), wild boar avoids this habitat, preferring the forest habitat to spread and extend its occupancy range. This results in a contradiction with our preliminary hypothesis that increased area of cultivations providing cover (maize, rapeseed, cereals) facilitates wild boar population expansion. Furthermore, we show that besides the use of forest habitat, high population density is a major driving factor of the colonization of agroecosystems by wild boar. The ne-scale analysis (home range, daily), highlights the large variety of spatial behaviors (area restricted search, central place foraging, nomadism, dispersing) wild boar is able to use to cope with heterogeneous environments. In terms of management of the species, the results of this thesis suggest that it is required to lower the population density in order to limit the population spread into agroecosystems, not only at the margin of expansion but all over the species’ range. Furthermore, we recommend developing more exible control strategies taking into account both the spatial abilities of the species and the complexity and dynamics of the environment. For example, the creation of a seasonal landscape of fear could be promoted, i.e. reducing attractivity of agricultural lands by increasing risk sensation (e.g. hunting with dogs all along the growing season). However, in our opinion, the success of any management strategy requires rst to tackle the issue of the decreasing number of hunters observed in large part of Europe and to improve communication among the di erent stakeholders (hunting associations, farmers, public administration). Indeed, while ungulates have progressively adapted to human-induced changes, the capacity of humans to adapt to this new human-ungulate relation is questionable. [less ▲]

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See detailAssessment of climate change effects on groundwater resource in transient conditions
Goderniaux, Pascal; Wildemeersch, Samuel; Brouyère, Serge ULg et al

Conference (2015, June 27)

A sophisticated transient weather generator (WG) in combination with an integrated surface-subsurface hydrological model (HydroGeoSphere) are used for producing a stochastic generation of large numbers of ... [more ▼]

A sophisticated transient weather generator (WG) in combination with an integrated surface-subsurface hydrological model (HydroGeoSphere) are used for producing a stochastic generation of large numbers of equiprobable climatic time series, representing transient climate change, and assess impacts on groundwater resources in a probabilistic way. The modelling approach, involving the catchment-scale fully integrated surface-subsurface model, is described in Goderniaux et al. [2009]. Biased-corrected climate change scenarios are applied as input of the hydrological model to quantify their impact on groundwater resources. In Goderniaux et al. [2011], the integrated model is used in combination with a stochastic daily weather generator (WG). This WG allowed generating a large number of equiprobable climate change scenarios representative of a full transient climate between 2010 and 2085. These scenarios enabled to account for the transient nature of the future climate change, and to assess the uncertainty related to the weather natural variability. The downscaling method considers changes in the climatic means, but also in the distribution of wet and dry days. This new methodology is applied for the unconfined chalky aquifer of the Geer catchment in Belgium. A general decrease of the mean groundwater piezometric heads, has been calculated. The approach allowed also to assess different uncertainty sources: (1) the uncertainty linked to the calibration of the hydrological model, using 'UCODE_2005'; (2) the uncertainty linked to the global and regional climatic models (GCMs and RCMs), by using a multi-model ensemble; (3) the uncertainty linked to the natural variability of the weather, by using stochastic climate change scenarios. 30 equiprobable climate change scenarios from 2010 to 2085 have been generated for each of 6 different RCMs. Results show that although the 95% confidence intervals calculated around projected groundwater levels remain large, the climate change signal becomes stronger than that of natural climate variability by 2085. The WG ability to simulate transient climate change enabled the assessment of the likely timescale and associated uncertainty of a specific impact. This methodology constitutes a real improvement in the field of groundwater projections under transient climate change conditions as it enables water managers to analyse risks and take decisions with full knowledge of projected impact and their degree of confidence. [less ▲]

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See detailDUSP3 Phosphatase Deficiency or Inhibition Limits Platelet Activation and Arterial Thrombosis
Tautz, Lutz; Rahmouni, Souad ULg; Oury, Cécile ULg et al

Conference (2015, June 27)

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See detailTime-domain simulation of large electric power systems using domain-decomposition and parallel processing methods
Aristidou, Petros ULg

Doctoral thesis (2015)

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. Over the last decades, they have become indispensable to anyone involved in power system ... [more ▼]

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. Over the last decades, they have become indispensable to anyone involved in power system planning, control, operation, and security. Transmission system operators depend on fast and accurate dynamic simulations to train their personnel, analyze large sets of scenarios, assess the security of the network in real-time, and schedule the day ahead operation. In addition, those designing future power systems depend on dynamic simulations to evaluate proposed reinforcements, whether these involve adding new transmission lines, increasing renewable energy sources, or implementing new control schemes. Even though almost all computers are now parallel, power system dynamic simulators are still based on monolithic, circuit-based, single-process algorithms. This is mainly due to legacy code, written in the 80's, that is still today in the core of the most important commercial tools and does not allow them to fully exploit the parallel computational resources of modern computers. In this thesis, two parallel algorithms belonging to the family of Domain Decomposition Methods are developed to tackle the computational complexity of power system dynamic simulations. The first proposed algorithm is focused on accelerating the dynamic simulation of large interconnected systems; while, the second algorithm aims at accelerating dynamic simulations of large combined transmission and distribution systems. Both proposed algorithms employ non-overlapping decomposition schemes to partition the power system model and expose parallelism. Then, “divide-and-conquer” techniques are utilized and adapted to exploit this parallelism. These algorithms allow the full usage of parallel processing resources available in modern, inexpensive, multi-core machines to accelerate the dynamic simulations. In addition, some numerical acceleration techniques are proposed to further speed-up the parallel simulations with little or no impact on accuracy. All the techniques proposed and developed in this thesis have been thoroughly tested on academic systems, a large real-life system, and a realistic system representative of the continental European synchronous grid. The investigations were performed on a large multi-core machine, set up for the needs of this work, as well as on two multi-core laptops computers. [less ▲]

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See detailInfluence of terroir on the fungal assemblages associated to common bean seed
Klaedtke, Stephanie ULg; Jacques, Marie-Agnès; Chable, Véronique et al

Conference (2015, June 25)

Plants have evolved in association with microbial assemblages, also known as microbiota, which can affect plant growth and health. In contrast with other plant habitats, microbiota associated to seeds ... [more ▼]

Plants have evolved in association with microbial assemblages, also known as microbiota, which can affect plant growth and health. In contrast with other plant habitats, microbiota associated to seeds have only recently become an object of research. First surveys reveal that seed-associated microbial assemblages are composed of 50 to 1000 bacterial and fungal operational taxonomic units (OTUs) (Barret et al., 2015), including plant pathogens. Common bean (Phaseolus vulgaris L.) is affected by several seed-borne pathogens representing a phytosanitary challenge for common bean seed production. In a participatory research project (Farm Seed Opportunities, a European FP6 project), small scale organic seed producers emitted the hypothesis that seed microbiota in their integrity, including pathogens, play a role in shaping the crop as it adapts to local environments, leading to more resilience (Döring et al., 2014). As a first step to investigating this hypothesis, we analyzed 27 bean seed samples to assess whether the seed microbiota are indeed site-dependant or in contrary transmitted from on plant generation to the next within each cultivar. [less ▲]

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