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See detailBiodiversity and ecosystem services: think functional!
Uyttenbroeck, Roel ULg; Hatt, Séverin ULg; Paul, Aman ULg et al

Poster (2014, February 07)

During the last years, several studies and reviews have considered the relation between biodiversity and ecosystem functioning or the provision of ecosystem services. Many studies found that plant ... [more ▼]

During the last years, several studies and reviews have considered the relation between biodiversity and ecosystem functioning or the provision of ecosystem services. Many studies found that plant functional traits and plant functional diversity (FD) are key drivers in this relation in terrestrial ecosystems. Researchers used different methods to obtain a gradient in plant FD to examine the effect on ecosystem services, going from observational studies of natural communities to synthetic assemblages. Furthermore, different methods exist to quantify plant FD going from simple functional trait richness to indices, distance-based frameworks and the division into FD components. In the AgricultureIsLife project, we set up a field experiment aiming to examine the biodiversity – ecosystem service relation in agricultural context. The experiment consists of perennial wildflower strips with different plant functional diversities in an arable field with conventional crop production. The wildflower strips were sown as synthetic assemblages but are subject to natural succession during the following years. We monitor the evolution of FD from the sowing to the establishment of a typical wildflower strip using Rhao’s quadratic entropy index to quantify FD. In addition, the flower strips will be monitored for four ecosystem services they are expected to provide: pollination, pest control, biodiversity support and provision of valuable compounds. [less ▲]

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See detailLa malédiction de Cassandre. Histoire d'une plateforme distribuée d'analyse qualitative de textes et d'images
Lejeune, Christophe ULg

Scientific conference (2014, February 07)

Le logciel Cassandre fait partie de la plateforme Hypertopic d'annotation collaborative de textes et d'images. Du point de vue de la recherche en informatique, le développement de cette plateforme s ... [more ▼]

Le logciel Cassandre fait partie de la plateforme Hypertopic d'annotation collaborative de textes et d'images. Du point de vue de la recherche en informatique, le développement de cette plateforme s'insère dans le courant du Web socio-sémantique. Du point de vue des sciences humaines, la plateforme fournit des outils de recherche qualitative. Christophe Lejeune fait le récit de son expérience de développement (de 2005 à aujourd'hui). Ce faisant, il illustre des notions abordées dans les séances précédentes, telles que les questions de gestionnaire de versions, les services Web RESTful, les centres de calcul, les nuages, les collaborations inter-universitaires, les communautés Open Source et la relation avec les utilisateurs. [less ▲]

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See detailContribution to the study of alliinase, the active principle of garlic
DETHIER, Bérénice ULg; Ponchaux, Julien; Laloux, Morgan et al

Poster (2014, February 07)

Alliinase is a crucial enzyme in the Allium genus. The conversion of its substrates, cysteine sulfoxides, into volatile thiosulfinates is an important mechanism in the defence of the plant. It also ... [more ▼]

Alliinase is a crucial enzyme in the Allium genus. The conversion of its substrates, cysteine sulfoxides, into volatile thiosulfinates is an important mechanism in the defence of the plant. It also provides the typical pungent flavour of garlic. As a matter of fact, the thiosulfinates decompose in a range of organosulfur compounds (OSC) known for their biological activities (antioxidant, anticancer, anti-diabetes properties, etc.). The environment of the decomposition of the thiosulfinates determines the type and amount of products released. A deeper knowledge of the conditions that form each OSC could help us in the preparation of garlic-based nutraceutics in the perspective of healthier food consumption. This study aims to improve the extraction and purification the enzyme alliinase in order to perform the reaction between the enzyme and its substrates and assess the potentialities of garlic preparations. Three methods have been applied to evaluate the efficiency of the extractions and purifications of the enzyme. A first idea of the purity of the enzyme is given by an electrophoresis separation of each sample on a polyacrylamide gel (SDS-PAGE). The protein content is then measured by UV-vis spectrometry with Lowry-Folin reagent for the coloration and BSA as an external standard. Finally, the specific activity is assessed by an indirect measure of the pyruvate (released as a co-product): the addition of NADH and lactate dehydrogenase turns the pyruvate in lactate, and the disappearance of NADH is measured by UV-vis spectrometry at 340 nm. The extraction of the enzyme from garlic was performed either by PEG 8000 precipitation or by ammonium sulphate precipitation. Two purifications were tested: affinity chromatography (on ConA) and size-exclusion chromatography. The combination of the ammonium sulphate process with the ConA chromatography provided the purest enzyme, with the best activity but a lower yield than the size-exclusion process. Finally the stability of the enzyme has been assessed at 4, -20 and -80 °C, showing that the enzyme could be kept at -80 °C for over 4 months without deterioration, while activity loss was observed at higher temperature. [less ▲]

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See detailIs the noxious Ambrosia artemisiifolia L. going to invade Belgium?
Ortmans, William ULg; Chauvel, Bruno; Mahy, Grégory ULg et al

Poster (2014, February 07)

Ambrosia artemisiifolia L. is an invasive species from North America, causing a health crisis in Europe due to its highly allergenic pollen. In France, there is a zone where the A. artemisiifolia ... [more ▼]

Ambrosia artemisiifolia L. is an invasive species from North America, causing a health crisis in Europe due to its highly allergenic pollen. In France, there is a zone where the A. artemisiifolia populations are naturalized and invasive. Outside this area, populations are more rare and do not seem to expand. We tested if the performances of A. artemisiifolia are varying with competition level, and among geographical zones. The results show that populations from Belgium and Netherlands are not less efficient than invasive populations for the measured traits. [less ▲]

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See detailUse of GC-MS in SIM-Scan mode for a selective quantification of polluting volatile organic compounds (VOC) in food industries
Eloundou Mballa, Pierre ULg; DETHIER, Bérénice ULg; Fauconnier, Marie-Laure ULg

Poster (2014, February 07)

The control of atmospheric emission discharges by food industries is classically achieved in two phases. The first one consists of sampling the target atmosphere followed by concentrating the volatile ... [more ▼]

The control of atmospheric emission discharges by food industries is classically achieved in two phases. The first one consists of sampling the target atmosphere followed by concentrating the volatile organic compounds (VOC) contained in a defined volume of this atmosphere on an adsorbing agent. These compounds are then thermally desorbed (TD) or desorbed with a solvent. In the second phase, the gas phase chromatogram (GC) will be coupled with mass spectrometry (MS) or flame ionization detector (FID) for compounds analysis. Quantitative analysis are usually achieved with solvent desorption followed by GC-FID. However, this mode imposes the dilution of the sample by a solvent and consequently may cause high detection thresholds as well as important matrix effect and possible interferences due to chemical reactions between analytes and the solvent. Besides, a preliminary qualitative analysis (GC-MS identification) is necessary. Combining TD-GC-MS allows very low detection thresholds to be reached, and the matrix effect and the interferences caused by products of the reactions between analytes and the solvent to be eliminated. The use of this combination in selected ion monitoring (SIM) mode allows targeting analytes via their characteristic ions, increasing their sensitivity and repeatability insuring more accuracy for simultaneous qualitative and quantitative analysis. This technique was experimented for seeking VOC in the atmosphere around food industries. [less ▲]

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See detailInteractions of a potential plant elicitor mannolipid with plant model membranes
Polo Lozano, Damien ULg; Lins, Laurence ULg; Ongena, Marc ULg et al

Poster (2014, February 07)

The use of chemical pesticides causes problems for human health and environment. In this context, there is an increasing interest for alternative products such as biopesticides. Among them, elicitors act ... [more ▼]

The use of chemical pesticides causes problems for human health and environment. In this context, there is an increasing interest for alternative products such as biopesticides. Among them, elicitors act on the plants by inducing systemic resistance against diseases caused by fungal, viral, bacterial agents and insects. The target of the elicitors is supposed to be the plant plasma membranes (PPM). The main mechanisms of interaction of many elicitors involve proteic receptors but lipid-based elicitors (LBE) may preferably interact with the lipidic fractions of PPM. However there is no detailed information at the molecular level on the PPM-LBE interactions. Our work is focused on a original synthetic LBE composed of a mannoside linked to a myristic acid. It has potential elicitor activities as shown by the assays on tobacco root cells. These activities could be related to its interaction with the lipidic phase of PPM. Since PPM are complex entities, the analyses of the PPM- molecule interactions are quite difficult. In this context, these interactions were carried out using biomimetic membranes of PPM such as Langmuir monolayers and multilayers. The effects of our molecule on these membranar systems were investigated by biophysical and in silico approaches. [less ▲]

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See detailConsequences of Selection for Environmental Impact Trait in Dairy Cows
Kandel, Purna Bhadra ULg; Vanderick, Sylvie ULg; Vanrobays, Marie-Laure ULg et al

Scientific conference (2014, February 07)

Environmental sustainability is gaining importance in dairy industry due to enteric methane (CH4) emission from dairy cows. We predicted CH4 indicator trait (CH4 intensity: CH4 g/kg of milk) from Mid ... [more ▼]

Environmental sustainability is gaining importance in dairy industry due to enteric methane (CH4) emission from dairy cows. We predicted CH4 indicator trait (CH4 intensity: CH4 g/kg of milk) from Mid-infrared spectra of milk samples and recorded milk yield. Genetic correlations between CH4 intensity and milk production traits were estimated on Holstein cows from correlations of estimated breeding values. Genetic correlations between CH4 intensity and milk yield (MY) was -0.67, fat yield (FY) -0.13, protein yield (PY) -0.46, somatic cell score (SCS) 0.02, longevity -0.07, fertility 0.31, body condition score (BCS) 0.27 and average of confirmation traits -0.23. Currently, there is no CH4 emission trait in genetic evaluation selection index. Putting an hypothetical 25% weight on CH4 intensity on current Walloon genetic evaluation selection index and proportional reduction on other selection traits, the response to selection will be reduction of CH4 emission intensity by 24%, increase in MY by 30%, FY by 17%, PY by 29%, SCS by -15%, longevity by 24%, fertility by -11%, BCS by -13% and conformation traits by 24%. In conclusion, introduction of environmental traits in current selection index will affect selection responses. As there is no economic value of these traits presently alternative methods like putting correlated traits with clear economic value (e.g. feed efficiency) in the selection objective could generate appropriate index weights. [less ▲]

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See detailInteractions between new phenolic glycolipids and model membrane
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Crowet, Jean-Marc ULg et al

Poster (2014, February 07)

Model membrane based on phospholipids (PL) layers are useful to mimic properties of plasma membranes. The interactions between new synthesized phenolic glycolipids (PGL) and biological membrane are ... [more ▼]

Model membrane based on phospholipids (PL) layers are useful to mimic properties of plasma membranes. The interactions between new synthesized phenolic glycolipids (PGL) and biological membrane are crucial to determine their potential as drug candidates and their cytotoxicity . [less ▲]

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See detailUse of lipases for the kinetic resolution of lactic acid esters in heptane or in a solvent free system
Richard, Gaetan ULg; Nott, Katherine; Nicks, François et al

Poster (2014, February 07)

This poster illustrates the kinetic resolution of lactic acid esters using CAL-B as catalyst. The racemic mixture is resolved in heptane and even in a solvent free system.

Detailed reference viewed: 13 (3 ULg)
Peer Reviewed
See detailThe emergence of the possessive article pAy.f before the Amarna period
Sojic, Nathalie ULg

Conference (2014, February 07)

This presentation gives an overview of my research devoted to the Late Egyptian possessive article pAy.f. It aims at examining the uses of an element whose meaning evolved through time. Rather than ... [more ▼]

This presentation gives an overview of my research devoted to the Late Egyptian possessive article pAy.f. It aims at examining the uses of an element whose meaning evolved through time. Rather than looking for the very first occurrences of pAy.f in the Old Kingdom texts, my main concern is to analyze closely its progressive spread as well as to outline the gradual steps of its semantic evolution across the pre-amarnian corpus (15th-17th Dyn., c. 1650-1350 b.C.). On the one hand, I highlight the process by which this recent construction gradually encroaches on the older one, and on the other hand, I define the the meanings of pAy.f in relation to its distribution according to text genres. [less ▲]

Detailed reference viewed: 8 (1 ULg)
See detailSimulations of a beta amphiphilic peptide as potential surfactant of membrane proteins
Crowet, Jean-Marc ULg; Dony, Nicolas ULg; Deschamps, Antoine et al

Poster (2014, February 07)

The peptide studied here was designed to form beta amphiphilic films with the aim to stabilize purified membrane proteins. This interaction has notably been followed by FRET. Hydrophobic and hydrophilic ... [more ▼]

The peptide studied here was designed to form beta amphiphilic films with the aim to stabilize purified membrane proteins. This interaction has notably been followed by FRET. Hydrophobic and hydrophilic residues are alternate and positively and negatively charged residues place respectively at the start end the end of the peptide. The peptide has been studied by atomistic and coarse grained molecular dynamics in water, chloroform and mixed solutions. The peptide was observed to spontaniously form beta films at the chloroform water interface. Moreover, when we simulate the interaction of this peptide with a membrane protein and with a membrane protein in a micelle of dodecylphosphocholine. The peptide was observed to form beta films at the membrane protein surface and even remove surfactants from the membrane protein surface. The simulations confirms the behaviour of this peptide observed in vitro and shows that it could be used instead of detergents. [less ▲]

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See detailAllelopathic potential of sunflower against the great brome
Bouhaouel, Imen ULg; Gfeller, Aurélie; Fauconnier, Marie-Laure ULg et al

Poster (2014, February 06)

Control methods commonly used to suppress the great brome (Bromus diandrus Roth., syn. Bromus rigidus Roth. subsp. gussonii Parl.) in Tunisian cereal crop are essentially chemical, raising both efficacy ... [more ▼]

Control methods commonly used to suppress the great brome (Bromus diandrus Roth., syn. Bromus rigidus Roth. subsp. gussonii Parl.) in Tunisian cereal crop are essentially chemical, raising both efficacy and safety issues. The introduction of allelopathic species into the crop rotation or utilizing allelopathic plants as living/green mulches has been suggested as a cost-effective way to reduce the weed presence. Among these species, the sunflower (Helianthus annuus L.) has shown an allelopathic potential against some troublesome weed species. In this study, we analyzed the biological activities of water extract of different tissues (root, shoot, leaf and flower) of sunflower on the seedling establishment of the great brome. In a second experiment, the allelopathic influence of sunflower residues (leaf or flower) against this weed was also studied under glasshouse conditions at more advanced stages of growth using different concentrations (0, 6, 12 and 18g tissue dry weight / kg of soil). The first experiment showed an effect depending on the parts of the sunflower. Indeed, the roots seem to be the less allelopathic part (22% of root inhibition growth) as compared to the leaves and flowers (82% and 100%, respectively). This potential seems to simultaneously affect the radicle and the coleoptile growth of the great brome. In the second experiment, weed growth was inhibited in a dose-dependent manner, using increasing amounts of sunflower residues. The allelopathic potential of the leaves or flowers reduced both the root or shoot length and biomass accumulation of the weed. These results suggest that the sunflower can be a good previous crop for cereal cultivation by controlling the presence of some weeds, including the great brome. In this perspective, the inhibitory effects of sunflower residues on cultivated cereals in the field need to be assessed. [less ▲]

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See detailImpact of extraction procedures on the chemical, rheological and textural properties of ulvan from Ulva lactuca of Tunisia coast
Yaich, Hela; Garna, Haikel; Besbes, Souhail et al

in Food Hydrocolloids (2014), (40), 53-63

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained ... [more ▼]

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained after combining enzymatic and chemical extraction but the lowest yield results at the drastic conditions (pH 1.5 and 90 C). Besides, solvent acidity was an important parameter controlling the ulvan extraction efficiency. The different extraction processes affected chemical composition of ulvan extracts and in particular, sulphate, ash and sugar contents. Low proportions of galactose, glucose and protein were also found in sulphated polysaccharides. The extract, which is resulted from combined enzymatic and chemical extraction, was mainly composed of high peak molecular weight polysaccharides. Ulvan hy-drocolloids demonstrated a pseudoplastic behavior. Viscoelastic behavior was carried out at a concen-tration of 1.6% (w/v) in the presence of 7 mM sodium tetraborate and at pH 7.5. However, polysaccharides formed a gel. It was not the case for the extract at pH 1.5 and 90 C under the same conditions. The results showed that a significant effect of the conditions of extraction on the textural characteristic (firmness, springiness and adhesiveness) of ulvan gels. [less ▲]

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See detailExperimental investigation of meandering jets in shallow reservoirs
Peltier, Yann ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Environmental Fluid Mechanics (2014)

Meandering flows in rectangular shallow reservoirs were experimentally investi- gated. The characteristic frequency, the longitudinal wave length and the mean lateral exten- sion of the meandering jet ... [more ▼]

Meandering flows in rectangular shallow reservoirs were experimentally investi- gated. The characteristic frequency, the longitudinal wave length and the mean lateral exten- sion of the meandering jet were extracted from the first paired modes, obtained by a proper orthogonal decomposition of the surface velocity field measured by large scale PIV. The depth-normalised characteristic lengths and the Strouhal number were then compared to the main dimensionless numbers characterizing the experiments: Froude number, friction num- ber and reservoir shape factor. The normalised wave length and mean lateral extension of the meandering jet are neither correlated with the Froude number nor with the reservoir shape factor; but a clear relationship is found with the friction number. Similarly, the Strouhal num- ber is found proportional to a negative power of the friction number. In contrast, the Froude number and the reservoir shape factor enable to predict the occurrence of a meandering flow pattern: meandering jets occur for Froude number greater than 0.21 and for a shape factor smaller than 6.2. [less ▲]

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See detailForecasting Daily Solar Energy Production Using Robust Regression Techniques
Louppe, Gilles ULg; Prettenhofer, Peter

Conference (2014, February 05)

We describe a novel approach to forecast daily solar energy production based on the output of a numerical weather prediction (NWP) model using non-parametric robust regression techniques. Our approach ... [more ▼]

We describe a novel approach to forecast daily solar energy production based on the output of a numerical weather prediction (NWP) model using non-parametric robust regression techniques. Our approach comprises two steps: First, we use a non-linear interpolation technique, Gaussian Process regression (also known as Kriging in Geostatistics), to interpolate the coarse NWP grid to the location of the solar energy production facilities. Second, we use Gradient Boosted Regression Trees, a non-parametric regression technique, to predict the daily solar energy output based on the interpolated NWP model and additional spatio-temporal features. Experimental evidence suggests that two aspects of our approach are crucial for its effectiveness: a) the ability of Gaussian Process regression to incorporate both input and output uncertainty which we leverage by deriving input uncertainty from an ensemble of 11 NWP models and including convidence intervals alongside the interpolated point estimates and b) the ability of Gradient Boosted Regression Trees to handle outliers in the outputs by using robust loss functions - a property that is very important due to the volatile nature of solar energy output. We evaluated the approach on a dataset of daily solar energy measurements from 98 stations in Oklahoma. The results show a relative improvement of 17.17% and 46.19% over the baselines, Spline Interpolation and Gaussian Mixture Models, resp. [less ▲]

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See detailIs dark matter made of mirror matter? Evidence from cosmological data
Ciarcelluti, Paolo; Wallemacq, Quentin ULg

in Physics Letters B (2014), 729

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We ... [more ▼]

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We consider scalar adiabatic primordial perturbations at linear scales in a flat Universe. The speed of the simulations allows us for the first time to use Markov Chain Monte Carlo analyses to constrain the mirror parameters. A Universe with pure mirror matter can fit very well the observations, equivalently to the case of an admixture with cold dark matter. In both cases, the analyses show a clear indication of the presence of a consistent amount of mirror dark matter, 0.05 < Ω_{mirror} h^2 < 0.12. [less ▲]

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See detailHors-cadres : des images qui manquent. Quand le documentaire ne peut pas tout montrer.
Hamers, Jérémy ULg

Conference given outside the academic context (2014)

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See detailTransnational modelling of the Meuse District with PegOpera simulation software
Grard, Aline ULg; Everbecq, Etienne ULg; MAGERMANS, POL ULg et al

in International Journal of River Basin Management (2014)

The environmental software PEGOPERA is a new tool resulting from the coupling of the PEGASE model (Planification Et Gestion de l’ASsainissement des Eaux, French acronym for planning and management of ... [more ▼]

The environmental software PEGOPERA is a new tool resulting from the coupling of the PEGASE model (Planification Et Gestion de l’ASsainissement des Eaux, French acronym for planning and management of water purification) with a friendly Graphical User Interface. PEGASE is an integrated and physically based river/basin model and is devoted to the characterisation of the physico-chemical state of surface water, at the scale of a whole watershed or basin, including International River Basin District (IRBD). The aim of the model is to simulate non stationary scenarios at various scales (from a few km² to hundreds of thousands km²) while handling the entire river tree (hundreds to thousands of water bodies). The purpose of PEGOPERA is to provide the stakeholders - as regards to surface water management - with a tool dedicated to the deterministic calculation of water quality of the rivers taking into account pollutant loads and discharges. In the context of the Water Framework Directive 2000/60/EC, the international coordination between neighbouring states and regions is required. The PEGOPERA software is adapted to simulate the IRBD Meuse. Indeed: i. An integrated transnational database relevant to the entire district is available; ii. The software is operational: the Meuse application has been calibrated and validated independently on most of regional sub-basins of the district; iii. The software could be used to simulate historical and future scenarios to assess water quality improvement that may be expected after applying basic and supplementary measures. The results demonstrate the relevance of the use of this software in this kind of transnational modelling. Some regions of the International District of the Meuse are validated on historical situations. Other parts still need to be improved in terms of consolidating the input databases. Prospective scenarios implementing measures from the WFD are carried out at this District scale. [less ▲]

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See detailOpinions, attitudes et comportements politiques. Tome 1. Notes provisoires
Grandjean, Geoffrey ULg

Learning material (2014)

Detailed reference viewed: 19 (4 ULg)