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See detailModelling total soil respiration in agricultural soils.
Buysse, Pauline ULg; Goffin, Stéphanie; Carnol, Monique ULg et al

Poster (2010, January 12)

Soil respiration is a process which results in CO2 release from the soil to the atmosphere. It comprises two main components. The first one is heterotrophic respiration: CO2 is produced by soil ... [more ▼]

Soil respiration is a process which results in CO2 release from the soil to the atmosphere. It comprises two main components. The first one is heterotrophic respiration: CO2 is produced by soil microorganisms while decomposing the substrate. The second one is autotrophic respiration in which CO2 originates from roots and rhizospheric organisms. All the CO2 is then transported to the surface by diffusion (see Goffin et al., this session). Many biotic and abiotic factors play a role in soil respiration, making this process complex to analyze and understand. Temperature often appears as the most important driving variable. Besides that, interest in the future CO2 emissions from agricultural soils has been growing. Indeed, these ecosystems are a major concern from environmental, economic and social points of view. In particular, the choice of cultural practices and residue management techniques has a strong influence on CO2 emissions from agricultural systems. This work aims at getting to a better understanding of soil respiration in agricultural soils. To reach this goal, many semi-mechanistic models have been previously developed at very different spatio-temporal scales. We intend to adapt such an existing model to crop soils, within a spatial scale of a cultivated field and an annual temporal scale. The model will be validated by using flux measurements carried out at three different crop sites situated in the Hesbaye region in Belgium (Lonzée) and in the South West of France (Lamasquère, Auradé). The study was focused first on soil heterotrophic respiration. Within this part, short term sensitivity of this component to temperature was studied by means of a laboratory incubation experiment. This one was performed with soil samples taken at the Lonzée site. Among the many interesting results we got, it showed a clear sensitivity of soil heterotrophic respiration to short term temperature changes. In parallel, the soil heterotrophic model was calibrated on soil chamber measurements taken at the Lonzée site (Belgium). Next steps in this part of the work will be to calibrate the model using the data from the French sites, and finally to validate the model on the three sites. Afterwards, an autotrophic respiration submodel will be implemented and the results compared to field measurements carried out at the three sites. A further development could consist in simulating agricultural practices to take their impacts on CO2 emissions from crops into account. [less ▲]

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See detailCan an Electronic Nose Assess the Biomethanation Process?
Adam, Gilles ULg; Nicolas, Jacques ULg

Poster (2010, January 12)

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See detailElectrical resistivity tomography and self-potential methods as a tool for fractured aquifer characterization and monitoring
Robert, Tanguy ULg; Nguyen, Frédéric ULg

Poster (2010, January 12)

Electrical resistivity tomography (ERT) and self-potential (SP) investigations are currently conducted in carboniferous limestones in Belgium. The aims of this study are (1) to characterize and (2) to ... [more ▼]

Electrical resistivity tomography (ERT) and self-potential (SP) investigations are currently conducted in carboniferous limestones in Belgium. The aims of this study are (1) to characterize and (2) to monitor the groundwater flow in fractured or karstic area and (3) to use these geophysical data as a help for groundwater flow model conceptualisation and inverse calibration. Large ERT profiles (320 meters) allow us to image the electrical resistivity distribution of the first 60 meters of the subsurface and to detect and characterize (in terms of direction, width and depth) some fractured and/or karstic zones expected to be less resistive. Data errors as well as indicators of resolution (resolution matrix, sensitivity matrix and DOI index) are analysed in order to calculate the depth of investigation of ERT and to avoid the misinterpretation of the resulting images. Self-potential measurements are performed along the electrical profiles and permit us to find some negative anomalies possibly related with groundwater preferential flow pathways. Since SP signals are related with the groundwater flow when taking into account the electrokinetic effect, we are able to estimate a first distribution of the water table along our profiles. These geophysical data concurrently with ‘ground truth’ geological and hydrogeological data give us a way to better understand the groundwater flow in limestone synclines of the Dinant Synclinorium geological structure. Still, further efforts are needed (1) to fully cover the syncline area and (2) to couple the SP, ERT and hydrogeological data through a more complex forward model of the electrokinetic effect of the self-potential method. [less ▲]

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See detailImage Appraisal Tools for Electrical Resistivity Tomography
Caterina, David ULg; Beaujean, Jean ULg; Robert, Tanguy ULg et al

Poster (2010, January 12)

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See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium)
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

Poster (2010, January 12)

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests ... [more ▼]

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests management: (i) the progression of research in applied autecology, (ii) the development of software for the management and the analysis of georeferenced data (GIS technologies) and, (iii) the awareness of the potential negative impacts of climate change on forests. To answer to this request, this research aims to model the autecology of the main forest tree species at the Walloon Region scale (Beech, Oak, Norway Spruce, Douglas-fir and valuable broadleaves species). The results will be used to update current practical tools to assess the adequacy of forest tree species on sites, especially in the climate change context. The research is built into three main steps: • update the autecology knowledge for the targeted forest tree species through a state of the art; • compile and create different ecological parameters that can explain the major part of trees growth such as climatic, topographic, geologic, edaphic and phytosociological data gathered from forest plots or geodatabases. In the context of climate change, a particular attention will be brought on bioclimatic and soil moisture conditions because of their narrow link with the potential risk of trees ecophysiological stress; • model tree species reaction to environmental conditions with tree growth indicators. Three types of indicators with different spatio-temporal scales are foreseen: stand site index (30-50 years), periodic diameter growth (5-10 years) and tree-ring growth (1-3 years). The use of these three scales is justified by the interest presented by their cross-validations which are necessary for an accurate extrapolation of results to the entire region. Results should indicate the tree species behaviour, especially towards stress conditions. The integration of climatic data, provided by global climate models based on IPCC's climate scenarios, in autecological models could be used to assess the behaviour of forest stands in future climate conditions. From those results, we expect to identify and assess accurately the risky “sites-species pairs” to avoid in the context of a sustainable silviculture. Finally, results will be used to provide autecological synthesis and practical tools to help forest managers and foresters to identify the best “site-species pairs” (tree-site adequacy maps, sites catalogue and computer platform). [less ▲]

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See detailHarmonia axyridis (Pallas) secondary metabolites quantification in relation with aposematism : Part I : Harmonine quantification
Fischer, Christophe ULg; Heuskin, Stéphanie ULg; Laurent, Pascal ULg et al

Poster (2010, January)

These last few years, the multicoloured Asian ladybird, Harmonia axyridis Pallas (Insects: Coleoptera: Coccinellidae), an invasive species, has swiftly spread out in Europe. This aposematic and highly ... [more ▼]

These last few years, the multicoloured Asian ladybird, Harmonia axyridis Pallas (Insects: Coleoptera: Coccinellidae), an invasive species, has swiftly spread out in Europe. This aposematic and highly polymorphic insect is problematic in several ways. It seems to outcompete native coccinellid species; they can group on fruits in vineyards and spoil wine when crushed with grapes; they can aggregate by hundreds in houses to winter. This study aims to investigate the relations between the chemical defences of H. axyridis and warning signals expressed by this bug. To achieve this goal, two original quantification methods of H. axyridis secondary metabolites have been undertaken. The first one allows Fast-GC quantifying harmonine, its main defence alkaloid. The other one permits to determine its emission rate of 2-isopropyl-3-methoxypyrazine, a highly odorous compound probably involved in the communication between individuals and in the aposematism of this insect. This last point will be detailed in another poster. Firstly, a method of extraction, acetylation and purification of harmonine from H. axyridis has been devised to obtain a calibration standard because this molecule is not commercially available. The identity of the extracted compound has been confirmed by mass spectrometry and multidimensional NMR. The GC purity of this N,N-diacetylharmonine is of 100%. During the experiments, its stability in acetone solution at 4°C has been verified. Using this purified molecule, an original method of harmonine quantification has been developed by fast gas chromatography and validated using accuracy profile. The method has been validated for concentrations ranging from 28µg/ml to more than 264µg/ml, with a maximal error risk of 20%. From about 100µg/ml, peaks symmetry decreased, but did not influence the quantification. That accuracy profile validation has been compared with a more classical validation using AOAC (2006) norm, which confirmed the first validation. This method allows quantifying harmonine in one single insect. Harmonine has been quantified in 80 H. axyridis divided into four groups of at least 15 individuals on basis of the morph type and the elytra hue. Males and females harmonine contents did not significantly differ. The mean harmonine content was of 106.6µg/individual with a standard deviation of 80.2µg/individual. The results distribution obtained was not normal and a strong variability between individuals was observed, which explains the high standard deviation. These results and those of the pyrazine and colour analysis have been statistically analyzed in order to show potential correlations between these factors. It would appear that elytra colour is linked with the insect harmonine content. Individuals with a non-melanic orange colour presented harmonine content significantly higher than other studied colours. The harmonine content does not seem linked to the pyrazine emission rate. [less ▲]

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See detailADDICTION AU MMORPG : QUAND LE REEL EST SOUS L’EMPRISE DU VIRTUEL
Bataille, Stéphanie; Triffaux, Jean-Marc ULg

Poster (2010, January)

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See detailHarmonia axyridis (Pallas) secondary metabolites quantification in relation with aposematism : Part II : Pyrazine quantification
Fischer, Christophe ULg; Heuskin, Stéphanie ULg; Marlet, Christelle ULg et al

Poster (2010, January)

The main objective of this study is to investigate the presence of links between chemical defences and warning signals presented by Harmonia axyridis (Pallas), the multicoloured Asian ladybird (Insects ... [more ▼]

The main objective of this study is to investigate the presence of links between chemical defences and warning signals presented by Harmonia axyridis (Pallas), the multicoloured Asian ladybird (Insects: Coleoptera: Coccinellidae). This second part describes an original quantification method for 2-isopropyl-3-methoxypyrazine (IPMP) by active sampling on thermally desorbed adsorbent (TD) coupled with GC-MS analysis. This highly odorous compound is supposed to be implicated in intra- and interspecific communication. In order to allow harmonine quantification (a defence alkaloid, see Part 1), this method avoid any hemolymph loses by the ladybird (Coccinellids can emit hemolymph when stressed). This method is non-lethal and applicable on one single insect. The quantification method has been validated from 37,5pg to 10 000 pg per adsorbent cartridge. On this range, there is no breakthrough and desorption is complete (>99.4%). At the LOQ (37.5pg/cartridge), the bias is of 20%, but rapidly decreased to less than 5% on the rest of the validated range (100 to 10 000 pg/cartridge). According to AOAC (2006) norm, this method is repeatable but not reproducible. The IPMP emission rate following a stress has been quantified on 80 H. axyridis grouped in four classes on basis of the morph type and the elytra hue. Males and females emission rates did not significantly differ. The mean emission rate is of 707 pg/4h with an extremely high standard deviation of 1766pg/4h due to a great individual variability and a strongly asymmetric distribution of the results. These results and those of the harmonine and colour analysis have been statistically analyzed in order to show potential correlations between these factors. It seems that elytra colour is linked with the insect IPMP emission rate. Individuals with a melanic red colour presented IPMP emission rate significantly lower than other studied colours. The harmonine content does not seem linked to the pyrazine emission rate. [less ▲]

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See detailAnalysis of aldehydes relaesed by rice flour using sorbent adsorption and thermal desorption - gas chromatography/mass spectrometry: Development and validation
Mertens, Cécile ULg; Marlet, Christelle ULg; Blecker, Christophe ULg et al

Poster (2010, January)

Odor is an essential characteristic and a quality marker in baby foodstuff, like a partially hydrolyzed and pregelatinized rice flour. The rice flour study by active sampling and TD-GC/MS highlighted the ... [more ▼]

Odor is an essential characteristic and a quality marker in baby foodstuff, like a partially hydrolyzed and pregelatinized rice flour. The rice flour study by active sampling and TD-GC/MS highlighted the presence of three aldehydes: Hexanal, Octanal, Nonanal. These compounds are known to be caused by lipid oxidation, one of the major alteration reactions in food. The Method was developed and valited on a large range for the three aldehydes. It was then applied to the rice fllour to determine if it can be used to follow the effect of ageing on the aldehydes production. [less ▲]

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See detailA fast gas chromatographic method for the study of semiochemical slow release formulations
Heuskin, Stéphanie ULg; Lorge, Stéphanie; Leroy, Pascal ULg et al

Poster (2010, January)

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See detailIDENTIFICATION OF METABOLITES IN A HUMAN PLASMA STANDARD REFERENCE MATERIAL BY MULTIPLE GC/MS APPROACHES
Eppe, Gauthier ULg; Benner, Bruce; White, Edward et al

Poster (2010, January)

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See detailLow detection HPLC – DAD analysis of aldehydes and ketones in indoor air : Development and validation by accuracy profile
Marlet, Christelle ULg; Haesen, Charlotte ULg; Lognay, Georges ULg

Poster (2010, January)

Aliphatic aldehydes and ketones like formaldehyde are reactive volatile compounds and common indoor pollutants. The main sources are tobacco smoke, combustion gases, painting and materials. Theses ... [more ▼]

Aliphatic aldehydes and ketones like formaldehyde are reactive volatile compounds and common indoor pollutants. The main sources are tobacco smoke, combustion gases, painting and materials. Theses compounds also arise from the reaction between unsaturated compounds and oxidative agents. The toxic potential of formaldehyde and other aliphatic/aromatic carbonyl compounds requires the determination of even low amounts of these compounds in indoor air. The present method for indoor monitoring uses adsorption at 2,4-dinitrophenylhydrazine (DNPH)-coated sorbents followed by HPLC-UV/DAD analysis of the extract. Detection limits of 0.1μg/m3 were reached by this method which is sufficient for indoor air monitoring. Three DNPH-derivatives could be separated well on a RP-Amide column followed by UV/DAD-detection at 360 nm. Recovery rates of 70-100 % were determined using liquid spiking method. Validation strategy was intentionally oriented towards the ease of use in routine and the liability of the method rather than extreme performances. For that, the validation by accuracy profile was chosen. The accuracy profile, based on the concept of total error (bias + standard deviation), allows to correctly conclude about the validity of a procedure and thus, guarantees that a known proportion of future results obtained with the method will be included within acceptance limits. For the three tested compounds, formaldehyde, acetaldehyde and acetone, the accuracy profile gave the guarantee that at least 95% of the future results obtained with the validated method will be within the ±25% acceptance limits over the whole concentration range defined. The HPLC parameters were also determinated. The performance of the method was finally evaluated by the analysis of indoor air from new timber frame construction. [less ▲]

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See detailThe Nociception Coma Scale to assess nociception in disorders of consciousness
Chatelle, Camille ULg; Schnakers, Caroline; VANHAUDENHUYSE, Audrey ULg et al

Poster (2010)

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See detailComparison of two drainage flow situations on a gentle forested slope
Heinesch, Bernard ULg; Yernaux, Michel ULg; Aubinet, Marc ULg

Poster (2010)

Drainage flows generated on a gentle slope in stable conditions were analysed at the forested site of Vielsalm (Belgium). Two distinct situations were encountered, one corresponding to vertical ... [more ▼]

Drainage flows generated on a gentle slope in stable conditions were analysed at the forested site of Vielsalm (Belgium). Two distinct situations were encountered, one corresponding to vertical convergence, characterised by a negative vertical velocity at the canopy top, the other corresponding to an equilibrium situation without any vertical movement. The causes of these two distinct flow patterns were analysed. Moreover, combined measurements of vertical velocity above the canopy and horizontal velocity divergence below the canopy were found to comply with the continuity equation: an acceleration of the horizontal flow was indeed observed in the trunk-space in convergence situations while not in equilibrium conditions. These measurements combined with those of the horizontal [CO2] gradient below the canopy were found to met the dilution hypothesis suggested by Aubinet et al.(2003): the horizontal [CO2] gradient was negative in convergence situations while slightly positive in equilibrium conditions. The existence of such patterns allows us to confirm the coherence of advection observations made at the site and help to better understand the mechanisms responsible of night flux exchanges at work in stable conditions in complex terrains. Nevertheless, difficulties were met when trying to obtain reliable estimates of the advection transport terms. The estimation of the vertical velocity in the trunk-space obtained by using the divergence measurements refuted the hypothesis of linearity of the vertical profile of vertical velocity, assumption usually used when computing vertical advection. This problem resulted in a great uncertainty on vertical advection which did not allowed to improve the night-flux estimation by adding advection terms to the turbulent flux and the storage. [less ▲]

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See detailMutliproxy investigation of climatic and anthropogenic changes in a Baltic bog (N. Poland) during the last millennium
De Vleeschouwer, François; Fagel, Nathalie ULg; Piotrowska, Natalia et al

Poster (2010)

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See detailRestauration des campos rupestres, une physionomie du biome Cerrado menacé par le changement d’usage des terres
Le Stradic, Soizig ULg; Buisson, Elise; Fernandes, Geraldo Wilson

Poster (2010)

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See detailStudy of mechanical, physical and chemical properties of a-C:H films deposited by reactive magnetron sputtering in DC pulsed mode
Colaux, J. L.; Dumont, D.; Delwigne, T. et al

Poster (2010)

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See detailNovel HDAC/DNMT twin inhibitors interfere with angiogenesis
Shiva Shankar, Thammadihalli Veerasangaiah ULg; Sulka, Béatrice; Blacher, Silvia ULg et al

Poster (2010)

DNA methylation and histone deacetylation are two key epigenetic modifications that play central role in regulation of gene expression. Several studies have shown that histone deacetylases (HDAC) and DNA ... [more ▼]

DNA methylation and histone deacetylation are two key epigenetic modifications that play central role in regulation of gene expression. Several studies have shown that histone deacetylases (HDAC) and DNA methyltransferases (DNMT) inhibitors are potent antiangiogenic compounds. Though combination of HDAC and DNMT inhibitors are now being examined in clinical trials of hematological malignancies, very little work has been done to understand the effect of this combination on normal and tumoral angiogenesis. We have designed and tested a family of twin drugs with intrinsic HDAC and DNMT inhibitory activities in relevant models of angiogenesis in vitro (endothelial cells, pericytes and the 3D aortic ring assay) and in vivo (the chick chorioallantoic membrane assay). We have identified a lead compound having quantifiable antiangiogenic effect without cytotoxicity associated with increased global acetylation and decreased DNA methylation levels. This compound is presently used to develop effective approaches to treat cancer by modulating the process of angiogenesis. [less ▲]

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See detailModeling of the longitudinal modulation of the Io interaction
Hess, S.; Bonfond, Bertrand ULg; Delamere, P. A. et al

Poster (2010)

The Io interaction with the Jovian magnetosphere is the best known case of moon-magnetosphere interaction. It leads to bright emissions from radio to UV, which are mostly due to the acceleration of ... [more ▼]

The Io interaction with the Jovian magnetosphere is the best known case of moon-magnetosphere interaction. It leads to bright emissions from radio to UV, which are mostly due to the acceleration of electrons by Alfvén waves along the magnetic field lines passing Io. We previously presented a model of the electron acceleration by the Iogenic Alfvén waves, which explains the average brightness of the emissions. We now present a study of the modulation of the Io-magnetosphere interaction with longitude, and compare our results with the observed brightness modulation of the auroral emissions. This study highlights how the satellite-magnetosphere interactions depend on the variation of the magnetic field, the equatorial plasma density,... A new model of the Jovian internal magnetic field, giving an accurate description of the longitudinal modulations of the Jovian magnetic field has been computed for this study, and is also presented. [less ▲]

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See detailThe HelpED Study: Degree of Agreement Between Patients, Partners, and Physicians on
Claes, Hubert; Andrianne, Robert ULg; Opsomer, Reinier

Poster (2010)

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See detailThe HelpED Study: Impact of Change in Erection Hardness on the Self-Esteem,
Opsomer, Reinier; Claes, Hubert; Andrianne, Robert ULg

Poster (2010)

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See detailCan Pleistocene refuge theory explain within-species patterns of genetic diversity in African lowland rainforest trees?
Heuertz, Myriam; Savolainen, Vincent; Budde, Katharina et al

Poster (2010)

Pleistocene refuge theory holds that regions which nowadays harbour high numbers of endemic species correspond to forest refuges, where rainforest persisted through periods of adverse climatic conditions ... [more ▼]

Pleistocene refuge theory holds that regions which nowadays harbour high numbers of endemic species correspond to forest refuges, where rainforest persisted through periods of adverse climatic conditions. In order to test this theory, we surveyed geographical patterns of genetic diversity based on chloroplast DNA sequences in 15 rainforest tree species from 12 plant families in Atlantic Equatorial Africa. We found frequent geographic structure in the data sets, but no consistent pattern of genetic structure due to refugia. Species with gravity-dispersed oily seeds display low polymorphism whilst those with divergent lineages or ancient species display high polymorphism. Phylogeographical signals often correspond to taxa with divergent lineages. [less ▲]

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See detailOperational multipartite entanglement classes for symmetric photonic qubit states
Kiesel, N.; Wieczorek, W.; Krins, Stéphanie ULg et al

Poster (2010)

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See detailPathogenicity of Pseudomonas cichorii isolates causing midrib rot on greenhouse butterhead lettuce
Pauwelyn, E.; Braekevelt, S.; Ongena, Marc ULg et al

Poster (2010)

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See detailAutomatic stimulus-induced medial premotor cortex activation without perception or action
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

Poster (2010)

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to ... [more ▼]

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to make the associated movement (Grezes & Decety, 2002). Here we investigated whether this automatic motor activation can also be elicited by visual stimuli that are not consciously perceived. However, previous subliminal masked experiments used supraliminal response-target in such a way that unconscious mechanisms were inferred from the accumulation of the effect of the subliminal masked stimulus and the motor response. Here, to investigate neural correlates of unconscious process induced by subliminal stimuli, we used event-related BOLD fMRI at 3T to record brain activity in 24 healthy volunteers (mean age: 21 ± 2 years) as they performed a subliminal priming task (see Eimer & Schlaghecken, 1998). In this visuomotor task, participants were asked to make speeded button presses with the left or right hand following double leftward (<< <<) or rightward (>> >>) pointing arrows, which were preceded by a masked subliminal prime of 17 ms (compatible/incompatible arrows or neutral stimulus). Reaction time analysis revealed the classical positive compatibility effect (PCE), mainly shorter reaction times for compatible (mean RT: 369±38 ms) than for incompatible (mean RT: 383± 30 ms) in comparison to neutral trials (mean RT: 375± 38 ms). In a prime identification task, subjects’ performance was at chance level for primes presented for 17 ms, suggesting that the prime was not consciously perceived in the main experiment. Theses behavioral results suggest an automatic and unconscious motor activation induced by the prime. The responded stimuli were randomly intermixed with non-responded stimuli (0 0) with the assumption that the subliminal arrow prime also elicited an automatic motor activation in these passive trials as in responded trials. Imaging analysis of these non-responded trials showed first that activation was mainly restricted to posterior brain areas when using a subliminal stimulus that has not been previously associated with a motor response. Second, when the subliminal stimulus has been strongly associated with a motor response, this activation extended to rostral brain regions classically involved in motor preparation as the SMA, the premotor cortex and the striatum (cluster level p< 0.05 corrected). This finding corroborates the involvement of a fronto-striatal network, especially of the SMA in automatic and unconscious motor activation. [less ▲]

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See detailThermodynamic and Kinetic Contributions to Stability Adaptation in a Psychrophilic Alpha-amylase
Cipolla, Alexandre; D'Amico, Salvino; Feller, Georges ULg

Poster (2010)

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See detailNanobodies as structural probes to investigate the mechanism of fibril formation by the amyloidogenic variants of human lysozyme.
Dumont, Janice ULg; Menzer, Linda ULg; Pardon, Els et al

Poster (2010)

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These ... [more ▼]

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. The binding of three variable domain of camelid antibodies – also named nanobodies - (cAb-HuL 6 [2], cAb-HuL 5 and cAb-HuL 22 [3]) raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three nanobodies bind on different regions of lysozyme and act as Amyloid fibrils inhibitor through different mechanisms. On one hand, cAb-HuL 6 and cAb-HuL 22 stabilize the native state of the lysozyme variants thus restoring the global cooperativity characteristic of the wild-type protein. On the other, cAb-HuL 5 probably acts by binding soluble prefibrillar aggregates. In the present work, sixteen other nanobodies specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non overlapping epitopes. The effects of the binding of these nanobodies on the stability of the D67H variant of human lysozyme and on its aggregation into amyloid fibrils will be discussed. [less ▲]

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See detailA structural study of natural olivine-type phosphates
Hatert, Frédéric ULg

Poster (2010)

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See detailVapor phase doping for ultra shallow junction formation in advanced Si CMOS devices
Shimizu, Yasuo; Nguyen, Ngoc Duy ULg; Jiang, Sijia et al

Poster (2010)

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See detailThe Chandra Carina Complex Project: massive stars
Gagné, M.; Fehon, G.; Dickerson, K. et al

Poster (2010)

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See detailDesign, implementation, and tests of the architecture of the radiocommunication system of the OUFTI-1 CubeSat
Marchal, Nicolas; Broun, Valéry; Denis, Amandine ULg et al

Poster (2010)

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See detailCamelid single-domain antibody fragments as structural probes to study the mechanism of human lysozyme fibrils formation
Dumont, Janice ULg; Pardon, Els; Menzer, Linda ULg et al

Poster (2010)

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These ... [more ▼]

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. The binding of three variable domain of camelid antibodies – also named nanobodies - (cAb-HuL 6 [2], cAb-HuL 5 and cAb-HuL 22 [3]) raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three nanobodies bind on different regions of lysozyme and act as amyloid fibrils inhibitor through different mechanisms. On one hand, cAb-HuL 6 and cAb-HuL 22 stabilize the native state of the lysozyme variants thus restoring the global cooperativity characteristic of the wild-type protein. On the other, cAb-HuL 5 probably acts by binding soluble prefibrillar aggregates. In the present work, sixteen other nanobodies specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non overlapping epitopes. The effects of the binding of these nanobodies on the stability of the D67H variant of human lysozyme and on its aggregation into amyloid fibrils will be discussed. References [1] Dumoulin et al, (2006) Acc. Chem. Res, 39, 603-610. [2] Dumoulin et al, (2003) Nature, 424, 783-788. [3] Chan et al. (2008) Biochemistry, 47,11041-11054. [less ▲]

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See detailCellular engineering of Bacillus subtilis to enhance the biosynthesis of highly active anti fungal lipopeptides
Guy, J.; Guez, Jean-Sébastien; Coucheny, F. et al

Poster (2010)

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See detailEffet de la puissance micro-ondes sur la composition chimique de l'huile essentielle de l'Eucalyptus globulus
Ramdani, M.; Fadel, O.; Mouni, L. et al

Poster (2010)

Dans le but de mettre au point les conditions optimales d’extraction des huiles essentielles sous micro-ondes, nous avons effectué une série de travaux en contrôlant l’effet de plusieurs facteurs sur la ... [more ▼]

Dans le but de mettre au point les conditions optimales d’extraction des huiles essentielles sous micro-ondes, nous avons effectué une série de travaux en contrôlant l’effet de plusieurs facteurs sur la composition chimique des extraits : présence du solvant, quantité de solvant et puissance des micro-ondes. Dans le cas de l’Eucalyptus globulus récolté à Oujda, nous avons comparé la composition chimique de l’huile essentielle extraite par micro-ondes sous deux puissances différentes : 280W et 700W. 38 composés volatils ont été identifiés par GC/MS et GC/FID. La comparaison de la composition chimique, dans les deux cas de puissance d’extraction (280W et 700W), nous a permis de noter respectivement les résultats suivants : a-pinène (2,41%, 4,06%) ; transpinocarveol (2,94%, 3,28%) ; 1,8-cinéole (0,91%, 1,84%) ; (+)-aromadendrene (2,22%, 2,82) ; globulol (4,63%, 4%) ; g-eudesmol (4,66%, 4,2%) ; b-eudesmol (17,02%, 14,5%) ; 1,2,3,4-tetrahydro-2,3-methano-2,8-dimethoxynaphtalene (4,27%, 4,28%) ; anisole, p(m-chlorophenyl) (0 %, 0,24%). La puissance micro-ondes choisie a un effet direct sur la variation de la composition chimique de l’huile essentielle extraite par micro-ondes de point de vue quantitatif et qualitatif. [less ▲]

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See detailShort-term effects of an organochloride pesticide (endosulfan) on amphibian tadpoles
D'Hooghe, Bastien; Brasseur, Catherine ULg; Kestemont, Patrick et al

Poster (2010)

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See detailGeneration of all Symmetric and all Total Angular Momentum Eigenstates in Remote Qubits
Maser, A.; Schilling, U.; Bastin, Thierry ULg et al

Poster (2010)

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See detailNumerical simulations of the wind of magnetic massive star HD191612
ud-Doula, Asif; Nazé, Yaël ULg

Poster (2010)

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See detailA close look at the RGS spectra of the O4Ief star Zeta Pup
Rauw, Grégor ULg; Flores, A.; Nazé, Yaël ULg et al

Poster (2010)

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See detailCO2 culling with Influenza Containment Systems (ICS)
Kamers, B.; Everaert, Nadia ULg; Tona, K. et al

Poster (2010)

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See detailA 500-yr record of Northern Patagonian environmental changes: Lago Plomo and Lago Bertrand
Fagel, Nathalie ULg; Brix, J.; El Ouahabi, M. et al

Poster (2010)

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See detailSelf-Awareness Therapy (SAT) for Schizophrenic Patients
Boulanger, Marie ULg; Nachtergael, Hilde; Pauly, Marc et al

Poster (2010)

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See detailA mid-size city and IYA09: a case study
Nazé, Yaël ULg

Poster (2010)

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See detailModeling Microbial Cross-contamination in Quick Service Restaurants by Means of Experimental Simulations With Bacillus Spores
Baptista Rodrigues, Ana Lúcia ULg; Crevecoeur, Sébastien ULg; Dure, Remi et al

Poster (2010)

Cross contamination has been frequently mentioned as being in the origin of a wide range of food borne outbreaks. Handling of food is one of the ways through which cross contamination may occur. For many ... [more ▼]

Cross contamination has been frequently mentioned as being in the origin of a wide range of food borne outbreaks. Handling of food is one of the ways through which cross contamination may occur. For many different reasons, quick service restaurants are particularly at risk. Due to its importance, cross contamination via the hands should be taken into consideration when carrying out a quantitative risk assessment. The main goal of this study was to determine transfer rates of bacteria to and via the hands, reduction rates of two hand sanitizing procedures and to apply the results to a quantitative microbial risk assessment model. According to our results, handling of a portion of raw minced meat contaminated at 4.104 cfu leads to the presence of 24 cfu on both hands, 3 cfu on ready-to-eat product (RTE) manipulated with unwashed hands, 1 cfu on RTE manipulated with wiped hands and absence on RTE manipulated with washed hands. This study provides adequate quantitative data for quantitative microbial risk assessment. [less ▲]

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See detailResidual stress measurement in dental prostheses by hole-drilling.
Mainjot, Amélie ULg; Schajer, Gary; Vanheusden, Alain ULg et al

Poster (2010)

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See detailActivité antibactérienne et Technique d'extraction
Ramdani, M.; Benchat, N.; Fadel, O. et al

Poster (2010)

L’évaluation de l’activité antibactérienne fait l’objet de nombreuses études dans le domaine des plantes aromatiques et médicinales. Les résultats obtenus correspondent généralement à une technique ... [more ▼]

L’évaluation de l’activité antibactérienne fait l’objet de nombreuses études dans le domaine des plantes aromatiques et médicinales. Les résultats obtenus correspondent généralement à une technique d’extraction employée. Notre travail a pour objectif d’étudier l’effet de la technique d’extraction sur l’activité antibactérienne des huiles essentielles extraites à partir de certaines plantes aromatiques et médicinales. Nous avons préparé deux échantillons d’huiles essentielles par hydro-distillation conventionnelle et par hydro-distillation assistée par micro-ondes. Une série d’expériences a été effectuée sur un groupe de bactéries : E. coli, Staphylococcus, Klépsilla, Protéus, Bacillus. Les résultats obtenus ont montré que l’activité antibactérienne est nettement supérieur dans le cas du chauffage classique pour E. coli et Bacillus. Ceci montre que la composition chimique est différente pour les deux échantillons d’huiles essentielles. Les travaux effectués confirment que l’activité antibactérienne dépend directement de la technique d’extraction utilisée. [less ▲]

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See detailEpidemiologic study of pestivirus infection in both wild and domestic ruminants A survey in the Ubaye Valley (Alpine mountains, France)
Martin, Claire; Duquesne, Véronique; Adam, Gilbert et al

Poster (2010)

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See detailBacillomycin D and mycosubtilin, antimicrobial lipopeptides from Bacillus subtilis. A comparative analysis of their interfacial properties
Nasir, Mehmet Nail ULg; Besson, Françoise

Poster (2010)

Bacillus subtilis strains produce antimicrobial lipopeptides using non ribosomal peptide synthesis pathway. Among them, those belonging to iturinic family have an important place. This family is ... [more ▼]

Bacillus subtilis strains produce antimicrobial lipopeptides using non ribosomal peptide synthesis pathway. Among them, those belonging to iturinic family have an important place. This family is characterized by a peptide ring with a constant LDDLLDL chiral amino acid sequence cycled by a -fatty acid with a variable acyl chain. The iturinic lipopeptides exhibit their biological activities on the plasma membrane of the microbial cells. It has been demonstrated that they could be active on pathogenic strains which are resistant to currently-used therapeutic agents. Despite their interesting antimicrobial properties, there is limited number of works on their interactions with plasma membranes in order to understand their mode of action. Langmuir monolayers at the air-water interface are a useful tool to analyze the interactions between antimicrobial lipopetides and membranes. We therefore investigated iturinic lipopeptides-membrane interactions using Langmuir monolayers as membrane model. Our work focused on two iturinics, mycosubtilin and bacillomycin D, differing by their peptide ring (Figure 1). In the first step, we investigated their interfacial properties using tensiometry measurements and polarization modulation infrared reflexion absorption spectroscopy (PM-IRRAS). We found that the ability to form an interfacial film for two lipopeptides was different depending on the nature of the subphase. Moreover, their conformations at the air-water interface were determined as turns. In the second step, we investigated the insertion of the mycosubtilin and bacillomycin D in the lipid monolayers by determining their exclusion surface pressures. Our results showed that the insertion depends on the nature of the lipid film hence a membrane-compostion-dependant action of the two antimicrobial compounds could be explained. [less ▲]

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

Poster (2010)

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

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

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See detailComparison of hydrodynamic parameters obtained by 2D measurements in a flat rectangular column with X-ray radiography and data from literature on 3D columns
Calvo, Sébastien ULg; Beugre, Djomice Antoine ULg; Crine, Michel ULg et al

Poster (2010)

Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as ... [more ▼]

Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as with a gas-liquid counter-current flow. Hydrodynamic parameters are compared to experimental results obtained in 3D columns found in the literature, as well as to literature model predictions and to values computed using an in-house Lattice Boltzmann CFD simulation code. [less ▲]

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See detailApproaches for assessing potential impacts of thyroid hormone disrupting chemicals in wild sea bass (Dicentrarchus labrax)
Schnitzler, Joseph ULg; Klaren, Peter; Thomé, Jean-Pierre ULg et al

Poster (2010)

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring ... [more ▼]

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring pollutants in European coastal areas to disrupt the thyroid system in sea bass, a field study in the major European estuaries, namely, the Scheldt, the Seine, the Loire, the Charente and the Garonne has been conducted. Several thyroid endpoints were simultaneously examined. Diameter of follicles and the epithelial cell heights give an indication on the production and secretion activity of the thyroid gland. The activity of enzymes involved in the metabolism (deiodination, glucuronidation and sulfatation) of thyroid hormones was analyzed. Finally thyroxine (T4) and triiodothyronine (T3) concentrations were analyzed in muscle by radioimmunoassay. The combined use of all those endpoints gives us an overview of the complex thyroid hormone system. PCB concentration in wild fish varied from 10 to 100 ng g-1 wet weight (ww) depending on length and location. Each region has its own contamination levels and profiles reflecting the contribution of pollutants from rivers. The contamination levels were as follows: the highest concentrations were measured in individuals collected from the coastal region near the Scheldt > Seine > Loire > Charente and the lowest levels were observed in sea bass from coastal regions near the Garonne. Measurements of metabolic activity revealed an altered hepatic T4 outer ring deiodinase whereas T4 sulfatation and T4 glucuronidation were not affected. Owing to the extensive autoregulatory feedback at both central and peripheral levels, the thyroid hormone concentrations were preserved despite the PCB induced changes in thyroid hormone dynamics. [less ▲]

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See detailStudy of the surface and membrane properties of a bolaform surfactant issued from alkenyl D-xyloside
Deleu, Magali ULg; Damez, Céline; Gatard, Sylvain et al

Poster (2010)

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See detailFeasibility study of a Software Defined Radio and its adaptation to space
Heukemes, Mirko; Rainaut, Laurent; Denis, Amandine ULg et al

Poster (2010)

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See detailWater dynamics in the soil-plant continuum: which features regulate the uptake?
Lobet, Guillaume ULg; Javaux, M.; Pagès, L. et al

Poster (2010)

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See detailDecadal changes of carbon dioxide in the Scheldt estuary
Borges, Alberto ULg; Middelburg, J. J.

Poster (2010)

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See detailFirst man in the eastern Finland : an Early Mesolithic inland site with a red-ochre grave in Joensuu Rahakangas
Pesonen, Petro; Hertell, Esa; Nyholm, Mikael et al

Poster (2010)

Detailed reference viewed: 67 (0 ULg)