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See detailDesign of Photoreactive Orthosteric GABAA Ligands Potentially Useful for Studying Localization and Function of GABAA Receptors
Francotte, Pierre ULg; Nielsen, Birgitte; Krogsgaard Larsen, Povl et al

Poster (2011, May 08)

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See detailHigh-resolution measurements of an upwelling filament during the CAIBEX survey
Troupin, Charles ULg; Sangrà, Pablo; Arístegui, Javier et al

Poster (2011, May 02)

Upwelling filaments have been studied for several years. We aim to explain the general process in terms of potential vorticity: An injection of positive vorticity north of the Cape forces the jet to turn ... [more ▼]

Upwelling filaments have been studied for several years. We aim to explain the general process in terms of potential vorticity: An injection of positive vorticity north of the Cape forces the jet to turn offshore, in virtue of the principle of vorticity conservation. The Regional Ocean Modeling System (ROMS) is implemented in the Cape Ghir region, with horizontal resolution lower than 1 km. A set of process-oriented experiments has been designed in order to determine the mechanisms at the origin of the filament. [less ▲]

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See detailSpatial dynamics of wild boar population: Insights from a hunters' survey
Morelle, Kevin ULg; Lejeune, Philippe; Mengal, Coralie ULg

Poster (2011, May 02)

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See detailKynurenine administration suppresses cortical spreading depression in rat and the effect size is sex hormone dependent
Chauvel, Virginie ULg; Vamos, Eniko; Pardutz, Arpat et al

Poster (2011, May)

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See detailCaractérisation physicochimique et évaluation de la qualité des dattes des cultivars de palmier dattier de la région de Figuig
Hasnaoui, A.; ElHoumaizi, M. A.; Hakkou, A. et al

Poster (2011, May)

Detailed reference viewed: 157 (14 ULg)
See detailOxygen, a tool for assessing ocean tracer transport models
Mouchet, Anne ULg; Campin, Jean-Michel

Poster (2011, May)

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
See detailEffect of benzoic acid analogs on myeloperoxidase activity measured by a new technique to study their direct interaction with the enzyme.
Franck, Thierry ULg; Mazloum, Ali; Mouithys-Mickalad, Ange ULg et al

Poster (2011, May)

Myeloperoxidase (MPO) plays a key role in inflammatory response and constitutes a target for new drug development. The effects of some benzoic acid analogs were studied on the specific activity of human ... [more ▼]

Myeloperoxidase (MPO) plays a key role in inflammatory response and constitutes a target for new drug development. The effects of some benzoic acid analogs were studied on the specific activity of human MPO measured by SIEFED (“Specific Immunologic Extraction Followed by Enzymatic Detection”), an original method that consists of incubation of the compound with MPO, followed by capture of the enzyme by specific antibodies, washing (elimination of the compounds) and enzymatic detection of the immunocaptured enzyme. The compounds tested at 10-4, 10-5 and 10-6 M were studied in terms of structure activity relationship. Gallic acid (3,4,5-trihydroxybenzoic acid) with 3 hydroxyl groups had an important dose dependent inhibitory effect on MPO activity. Other molecules with less or without hydroxyl groups [3,4-dihydroxybenzoic acid, 2-hydroxybenzoic acid (salicylic acid) and benzoic acid] had rather an activator effect at 10-5 and 10-6 M. 2,4,6-Trihydroxybenzoic acid, with two hydroxyl groups adjacent to the carboxyl group, had a less efficient inhibitory effect. Caffeic acid (3,4-dihydroxycinnamic acid) with a propenoic acid group presented a dose dependent inhibitory effect on MPO activity contrary to its analog 3,4-dihydroxybenzoic acid. The esterification of the carboxyl group of gallic acid to obtain propyl gallate induced an activation of MPO at 10-5 and 10-6 M. Finally, the substitution of one or two hydroxyl groups by methoxyl ones (ferulic and syringic acids) decreased the efficiency of the molecules on the enzyme inhibition. The SIEFED technique appears as an innovative pharmacological tool to study the direct interaction of compounds with MPO. Number and position of hydroxyl groups and the extension of the carboxyl group of benzoic acid play a crucial role in the inhibition of MPO activity probably by facilitating the interaction with the active site or another elements of the enzyme structure. [less ▲]

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See detailAssessing the World Ocean ventilation timescales with simple analogs - the leaky funnel model
Mouchet, Anne ULg; Deleersnijder, Eric

Poster (2011, May)

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See detailWhen the nursing workload measurement among comatose patients becomes a reality …
THONON, Olivier ULg; BOULANGER, Jean-Marie ULg; BAKAY, Tahar ULg et al

Poster (2011, May)

The neurologic unit of the Academic Hospital of Liège is composed of 30 beds. This is one of reference's centers for detection and differentiation of the comatose patients. With the mediatization of the ... [more ▼]

The neurologic unit of the Academic Hospital of Liège is composed of 30 beds. This is one of reference's centers for detection and differentiation of the comatose patients. With the mediatization of the Pr S. Laureys's findings, our reference's center accommodate more and more comatose patients from different European countries. With the arrival and the increase of these comatose patients, the nurses had the feeling of an increase workload by report to all others neurologic patients. The purpose of this overview is initially to be able to measure the nursing workload among comatose patients and to demonstrate that this one, within a neurology unit of an academic Belgian hospital, is heavier than that of other patients suffering from neurologic affections. [less ▲]

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See detailRadiation-induced malignant peripheral nerve sheat tumors – a report of 2 cases
PHAN BA, Remy ULg; BELACHEW, Shibeshih ULg; JEDIDI, Zayd ULg et al

Poster (2011, May)

We discuss the case of two patients who developped delayed malignant peripheral nerve sheath tumor (MPNST) following radiotherapy. Case report: the first patient is a sixty year-old woman with a 2 years ... [more ▼]

We discuss the case of two patients who developped delayed malignant peripheral nerve sheath tumor (MPNST) following radiotherapy. Case report: the first patient is a sixty year-old woman with a 2 years history of right cervicobrachial pain and weakness. The neurological examination depicted severe weakness, atrophy and loss of sensation in the right C5 and C6 territories. A subclavicular hardened and enlarged lymph node was noted. Her past medical history was notable for a Hodgkin’s disease (HD) treated with radiation therapy (>40Gy) 35 years earlier. Brachial plexus MRI revealed a tumoral mass arising from the right brachial plexus. Biopsy of the subclavicular mass revealed a poorly differentiated malignant tumour consisting of spindle cells showing moderate polymorphism and a high mitotic index. Immunohistochemistry showed positivity for the S-100 protein, the CD56 and for the epithelial membrane antigen (EMA) and a diagnosis of MPNST of the brachial plexus was proposed. The second case is a 36 year-old man referred for a history of right sciatic neuralgia that appeared 3 years earlier. The medical history of the patient was notable for a right seminoma, treated by orchidectomy and prophylactic radiotherapy (24 Gy) 5 years earlier. The neurologic examination revealed right L5 and S1 radicular territories involvement, and the CT of the pelvis demonstrated a nodular mass at the level of the greater sciatic foramen. A surgical biopsy was performed and the neuropathological findings were consistent with a diagnosis of low-grade MPSNT. Discussion: MPNSTs are rare tumors accounting for 3 to 10% of all tissues sarcomas. Half of the cases described are sporadic, while the other half tend to appear in patients suffering from tumor prone conditions, such as neurofibromatosis type 1. Although secondary neoplasms are known complications of radiotherapy, descriptions of peripheral nerve sheath tumors (PNST) are scarce. The exact pathophysiology of radiation-induced PNSTs remains unclear but vascular alterations, direct damages to axon or Schwann cell and nerve compression by soft tissue fibrosis are thought to play a role. Although surgical removal sometimes followed by chemotherapy is the mainstay of MPNSTs, they usually carry a poor prognosis. Our 2 cases emphasize that the possibility of radiation-induced MPNST has to be kept in mind when investigating a localized neuropathy in a previously irradiated area. [less ▲]

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See detailTreatment of a case of trichurosis (Trichuris suis) in pigs
Caron, Yannick ULg; Delleur, Valery; De Bock, Bart et al

Poster (2011, May)

Trichuris suis infection was identified in a pig herd during an investigation into persistent diarrhea and weight loss in 10 recently introduced gilts. Eggs of the parasite were identified in faeces of ... [more ▼]

Trichuris suis infection was identified in a pig herd during an investigation into persistent diarrhea and weight loss in 10 recently introduced gilts. Eggs of the parasite were identified in faeces of gilts. Further investigations failed to detect other causes of diarrhea but, in all production stages, they allowed the detection of eggs of Trichuris suis that could explain pasty faeces sometimes observed in weaned sows and frequent diarrhea found in the early fattening period. The administration of levamisole (intramuscular injection) to gilts allowed the excretion of adult parasites, the treatment of diarrhea and the reduction of the number of eggs per gram of faeces. Taking into account the success obtained with levamisole in gilts, the equipment of the farm and the wish of the farmer no to inject finishing pigs, an unsuccessful treatment was tried based on levamisole in drinking water every 8 and then 5 weeks. Flubendazole was finally administrated in drinking water every 3 and then 5 weeks, reducing significantly the number of eggs per gram of faeces. [less ▲]

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See detailInvolvement of z-MMP-2 in Zebrafish lymphangiogenesis
Paupert, Jenny ULg; Pendeville, Hélène; Detry, Benoît ULg et al

Poster (2011, May)

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See detailAnnotating optical images from ROVs or towed cameras in Vulnerable Marine Ecosystems studies
Guillaumont, Brigitte; Carré, Cyril ULg; Van Den Beld et al

Poster (2011, May)

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Peer Reviewed
See detailThe antiangiogenic 16K prolactin disturbs functional tumor neovascularization by affecting vessel maturation
Nguyen, Ngoc-Quynh-Nhu ULg; Castermans, Karolien; Berndt, Sarah et al

Poster (2011, May)

16K hPRL, the antiangiogenic 16-kDa N-terminal fragment of human prolactin was shown to prevent tumor growth and metastasis by modifying tumor vessel morphology. Here we investigated the effect of 16K ... [more ▼]

16K hPRL, the antiangiogenic 16-kDa N-terminal fragment of human prolactin was shown to prevent tumor growth and metastasis by modifying tumor vessel morphology. Here we investigated the effect of 16K hPRL on tumor vessel maturation and on the related signaling pathways. We show that 16K hPRL treatment leads, in a murine B16-F10 tumor model, to a dysfunctional tumor vasculature with reduced pericyte coverage, and disruption of the PDGF-B/PDGFR-B, Ang/Tie2, and Delta/Notch pathways. In an aortic ring assay, 16K hPRL impairs endothelial cell and pericyte outgrowth from the vascular ring. In addition, 16K hPRL prevents pericyte migration to endothelial cells. This event was independent of a direct inhibitory effect of 16K hPRL on pericyte viability, proliferation, or migration. In endothelial cell-pericyte cocultures, we found 16K hPRL to disturb Notch signaling, this being the first time such an effect is observed with an endogenous antiangiogenic agent. These findings provide new insights into the mechanisms of 16K hPRL action and highlight its potential for use in anticancer therapy. [less ▲]

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See detailAcaricidal activities of Santolina Africana and Hertia Cheirifolia, two endemic plants of north Africa, on the two spotted spider mite (Tetranychus urticae)
Attia, Sabrine; Grissa, Kaouthar Lebdi; Le Goff, Guillaume et al

Poster (2011, May)

The two-spotted spider mite, Tetranychus urticae Koch, is a worldwide pest which feeds on a large variety of plant families. Because its resistance to acaricides is spreading rapidly, the development of ... [more ▼]

The two-spotted spider mite, Tetranychus urticae Koch, is a worldwide pest which feeds on a large variety of plant families. Because its resistance to acaricides is spreading rapidly, the development of new biological control tactics for population management is crucial. Plant extracts, such as Santolina africana and Hertia cheirifolia (Asteraceae), may represent viable alternatives, since they are currently considered to be minimumrisk pesticides. Although these two plants are known for their biocidal properties, the extract concentration that provides the most efficient control has not yet been precisely determined. In this study, we conducted a series of laboratory experiments to determine the susceptibility of adult females to different concentrations of S. africana and H. cheirifolia extract. These plants were steam-distilled and sprayed using a Potter spray tower. Mortality and fecundity were measured upon treatment with extract concentrations ranging from 0.07 to 6.75 mg/L. Female mortality increased with concentration, with LD50 values of 2.35 mg/L for S. africana and 3.43 mg/L for H. cheirifolia, respectively Reduced fecundity was previously observed at concentrations of 0.07, 0.09 and 0.29 mg/L .The chemical composition of the two oils were characterised by GC-MS. The most abundant components of the S. africana oil were terpinen-4-ol (44%), α- terpineol (11.31%) and borneol (6.73%). Camphor (15.11%), terpinen-4-ol (14.2%), α- terpineol (9.3%) were characteristic of the Hertia oil. [less ▲]

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See detailEstablishment of an interactomic map of the Ets factors family: Towards a better understanding of their roles in oncogenic processes
Rambout, Xavier ULg; Simonis, Nicolas; Demoitié, Pauline et al

Poster (2011, April 29)

Ets transcription factors have been involved in several cancers such as leukemia, prostate cancer and Ewing’s sarcoma. They regulate the expression of genes controlling important biological processes such ... [more ▼]

Ets transcription factors have been involved in several cancers such as leukemia, prostate cancer and Ewing’s sarcoma. They regulate the expression of genes controlling important biological processes such as cellular proliferation, differentiation, apoptosis, metastasis, and transformation. This family of transcription factors is characterized by its highly conserved DNA-binding domain called the ETS domain and members are classified into subfamilies based on sequence homology criterion. We built a protein-protein interaction (PPI) network of the 27 Ets proteins and of their individual functional domains using a high-throughput yeast-two hybrid (Y2H) screening method. That Y2H network was expanded with confident literature-curated PPIs to obtain a comprehensive Ets interaction network. By considering connectivity between Ets interaction partners, we were able to segregate highly connected clusters of proteins from that network. Analysis of ontologies enrichment of those clusters enabled to confirm well-established roles and regulations of Ets factors, but also to suggest new ones. Biological validation of one precise cluster could be used as a rule of a thumb to globally confirm the bioinformatic analysis of our Ets PPI network and the potential physiological or pathological roles and regulation of Ets factors. [less ▲]

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See detailNew fluorinated surfactant for nanogels preparation in supercritical CO2
Alaimo, David ULg; Beigbeder, Alexandre; Dubois, Philippe et al

Poster (2011, April 29)

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See detailNuclear Magnetic Resonance and Nuclear Waste Reprocessing.
Vidick, Geoffrey ULg; Bouslimani, Nouri; Desreux, Jean-François ULg

Poster (2011, April 29)

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See detailChitosan-based wound dressings produced by electrospinning
Croisier, Florence ULg; Sorlier, Pierre; Jérôme, Christine ULg

Poster (2011, April 29)

Detailed reference viewed: 35 (2 ULg)
See detailNovel amphiphilic copolymers and design of smart nanoparticles for drug delivery systems
Cajot, Sébastien ULg; Danhier, F.; Lautram, N. et al

Poster (2011, April 29)

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See detailFat analysis in muscle samples from horses affected with atypical myopathy
Van Galen, Gaby ULg; Deby-Dupont, G; Serteyn, Didier ULg et al

Poster (2011, April 15)

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See detailVariability of methane in the epilimnion of Lake Kivu
Borges, Alberto ULg; Abril, G.; Delille, Bruno ULg et al

Poster (2011, April 08)

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See detailParticipatory valuation and modelling of ecosystem services under land use change
Jacquemin, Ingrid ULg; Fontaine, Corentin M.; De Vreese, Rik et al

Poster (2011, April 08)

Ecosystem service (ES) is a conceptual linkage between biodiversity and human well-being. In a context of increased urbanization combined with the effects of climate change, the level of biodiversity is ... [more ▼]

Ecosystem service (ES) is a conceptual linkage between biodiversity and human well-being. In a context of increased urbanization combined with the effects of climate change, the level of biodiversity is expected to be reduced, and from the point of view of the ES, the loss of biodiversity is not only an environmental problem for itself, but is also a major issue for society’s sustainable development. Thus, it is necessary to identify adaptations of ecosystem use and management that will minimize the biodiversity loss while maintaining the production of ES for the society. To achieve this goal, ES must be valuated, but this valuation needs to consider a broad set of goals that include ecological sustainability and social fairness, along with the traditional economic goal of efficiency. Participatory approaches should be used in all ES valuation steps. Indeed, local stakeholders and end-users have a central role in the valuation process, as they are the direct beneficiaries of the provision of services. Moreover, biodiversity management must be focused onto human needs to deliver more integrated policy and management at a landscape-scale and be more firmly directed towards human well-being. Here, we present the framework developed within the VOTES (Valuation Of Terrestrial Ecosystem Services in a multifunctional peri-urban space) project for integrating all these factors in a quantitative tool designed for a sustainable landscape management, as well as for the evaluation and the monitoring of ES for policy designers. The originality is that this framework will provide an integrated valuation of ES in a spatially and temporally explicit way, based on the following steps: social valuation, biophysical valuation, economic valuation, landscape modelling & dynamics and finally integration of ecosystem service indicators. The biophysical assessment and landscape modelling steps rest on the combined use of two spatial models: a dynamic vegetation model (CARAIB DVM) and an agent-based model (ABM). These models will be used to construct future (dynamic) scenarios that include the major driving forces of the system (e.g., global socio-economic context, urbanization pressure, climate change, etc) together with adapted management. The computed scenarios will provide the changes in the biophysical system consistent with the socio-economic evolution, including changes in land use, crop productivity, carbon sequestration, or more generally ecosystem structure and function. This will allow an estimate of a change in the provision of ES through time, so that the sustainability of ES under the studied scenarios can be assessed. The framework is meant to be applicable to any given landscape, but here it is applied to a case study area in central Belgium, known for its strong periurban character, due to the proximity to Brussels. [less ▲]

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See detailSeasonal and inter-annual variability of air-sea CO2 fluxes and seawater carbonate chemistry in the Southern North Sea
Gypens, N.; Lacroix, G.; Lancelot, C. et al

Poster (2011, April 08)

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See detailFirst assessment of the biogeochemistry of the Congo River and tributaries
Darchambeau, François ULg; Bouillon, S.; Wabakanghanzi, J. N. et al

Poster (2011, April 08)

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See detailCarbon exchange in a Belgian grassland with cattle
Jerome, Elisabeth ULg; Beckers, Yves ULg; Bodson, Bernard ULg et al

Poster (2011, April 08)

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See detail2500 years record of trace element metal in the Misten peat bog (Hautes Fagnes), Belgium
Allan, Mohammed ULg; Fagel, Nathalie ULg; Le Roux, Gael et al

Poster (2011, April 08)

The Misten peat bog provides a record of atmospheric deposition in the Hautes Fagnes Plateau (East Belgium). A composite 185cm core (W01/01b) was studied for its trace metal content (TM) and its lead ... [more ▼]

The Misten peat bog provides a record of atmospheric deposition in the Hautes Fagnes Plateau (East Belgium). A composite 185cm core (W01/01b) was studied for its trace metal content (TM) and its lead isotopic signature. The peat bog accumulation allows following the history of atmospheric TM deposition during the last 2500 years. TM enrichment factors coupled with a continuous decrease in 206Pb/204Pb, 207Pb/204Pb,208Pb/204Pb isotopic ratios from 494-732AD to1969-1977 AD evidence the increasing importance of TM released by anthropogenic activities. The highest concentrations of TM are found near the surface of the bog; at depths from 30 to 19 cm. Historical records of Cu, Zn, As, Sb, and Pb atmospheric flux during the Industrial Revolution and pre-industrial periods were derived. Maximum fluxes (up to 7.3, 89, 2.4, 1.5, and 116 mg.m-2.y-1, respectively) occurred in peat layers dated from 1619-1877AD to 1992-2000AD, reflecting anthropogenic emissions from diverse sources such as mining, coal combustion, and emissions from the use of leaded gasoline. The TM enrichment factors also increased significantly during the Industrial Revolution until a reduction at the end of the 70’S due to the progressive abolition of the leaded gasoline. [less ▲]

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See detailThe interglacial carbon cycle
Kleinen, Thomas; Brovkin, Victor; Munhoven, Guy ULg et al

Poster (2011, April 07)

Explaining the difference in carbon cycle dynamics (and hence atmospheric CO2) between various interglacials is an elusive issue. Several biogeochemical mechanisms of different origin are involved in ... [more ▼]

Explaining the difference in carbon cycle dynamics (and hence atmospheric CO2) between various interglacials is an elusive issue. Several biogeochemical mechanisms of different origin are involved in interglacial CO2 dynamics, leading to a CO2 release from the ocean (carbonate compensation, coral growth) compensated by a land carbon uptake (biomass and soil carbon buildup, peat accumulation). The balance between these fluxes of CO2 is delicate and time-dependent, and it is not possible to provide firm constraints on these fluxes from proxy data. The best framework for quantification of all these mechanisms is an Earth System model that includes all necessary physical and biogeochemical components of the atmosphere, ocean, and land. To perform multi-millennial model integrations through the Holocene, Eemian, and MIS11, we use an earth system model of intermediate complexity, CLIMBER-2, coupled to the dynamic global vegetation model LPJ with a recently implemented module for boreal peatland dynamics. During glacial-interglacial cycles, the carbon cycle never is in complete equilibrium due to a number of small but persistent fluxes such as terrestrial weathering. This complicates setting up interglacial experiments as the usual approach to start model integrations from an equilibrium state is not valid any more. In order to circumvent the problem of non-equilibrium initial conditions, the model is initialised with the oceanic biogeochemistry state taken from a transient simulation through the last glacial cycle with CLIMBER-2 only. In this simulation, the CLIMBER-2 model was run through the last glacial cycle with carbon cycle in “offline mode” as interactive components of the physical climate system (atmosphere, ocean, ice sheets) were driven by concentration of greenhouse gases reconstructed from ice cores. Using these initial conditions, we performed coupled climate carbon cycle experiments for the Holocene, the Eemian and MIS11, driven by orbital forcing. Contrary to the results we published previously (Kleinen et al. 2010), peat accumulation was not prescribed, but rather determined dynamically, making this model setup applicable to previous interglacials as well. For the Holocene, our results resemble the carbon cycle dynamics as reconstructed from ice cores quite closely, both for atmospheric CO2 and delta13CO2. These experiments will be presented, analysing the role of different forcing mechanisms. The land surface appears to be an overall sink for CO2, due to carbon accumulation in the soil, as well as peat accumulation, and oceanic contributions due to temperature and circulation changes are quite small. Finally, results for MIS11 and the Eemian will be shown. [less ▲]

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See detailIsoprene and monoterpene emissions from a mixed temperate forest
Laffineur, Quentin ULg; Heinesch, Bernard ULg; Amelynck, Crist et al

Poster (2011, April 07)

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See detailOrgano-mineral imprints in fossil cyanobacterial mats of an Antarctic lake
Lepot, Kevin ULg; Deremiens; Namsaraev, Zorigto ULg et al

Poster (2011, April 07)

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See detailStudy of viability of Pseudomonas fluorescens BTP1 freeze-dried during storage at 4 and 20°C
Mputu Kanyinda, Jean-Noël ULg; Thonart, Philippe ULg

Poster (2011, April 05)

The drying of bacteria remains a major alternative in order to keep them long term. After centrifugation, the bacterial pellet of Pseudomonas fluorescens BTP1 was divided in two fractions one with and one ... [more ▼]

The drying of bacteria remains a major alternative in order to keep them long term. After centrifugation, the bacterial pellet of Pseudomonas fluorescens BTP1 was divided in two fractions one with and one without cryoprotectants (2% glycerol and 5% maltodextrine) and freeze-dried. After freeze drying, powders were sealed in aluminium bag under vacuum and storage at 4 or 20°C. The storage stability of freeze-dried powders was studied by parameters such as loss of viability on the Plate Count Agar (PCA) (e.g. Concentration of Cells with glycerol (PG) at CFU/g before storage 109 and after 7 month, 108 at 4°C and 107 at 20°C) and evolution in membrane composition by measuring the ratio of unsaturated/saturated fatty acid. These ratios decrease in function of time (e.g. at 4°C the ratios of C18:3 and C18:2 by C16:0 decreases respectively of 0,013 to 0,001 and 0,05 to 0,03 after 60 days of storage). Viability (%) and concentration (CFU/g) of bacterial during storage at 4 or 20°C with aw = 0,32 was determined using a procedure published by (Kurtmann et al., 2009). In the present study, flow cytometric analysis was applied to evaluate the state in which are the cells at the end of storage time. Furthermore, we compared result the survival of bacteria as obtained by plate count with the flow cytometric analysis results. [less ▲]

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See detailEvaluation of the present and future general circulation over Greenland simulated by the IPCC AR5/CMIP5 GCMs with the help of a circulation type classification
Belleflamme, Alexandre ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

Poster (2011, April 05)

Future projections of the Greenland ice sheet melt are based on General Circulation Model (GCM) simulations. In particular, the reliability of downscaling methods forced by these simulations depends on ... [more ▼]

Future projections of the Greenland ice sheet melt are based on General Circulation Model (GCM) simulations. In particular, the reliability of downscaling methods forced by these simulations depends on the quality of the atmospheric circulation simulated by GCMs. Therefore, it is essential to analyse and evaluate the GCMs modelled general circulation for current climate (1961-1990). Atmospheric circulation type classifications offer a very interesting approach for evaluating the GCM-based circulation at a daily time scale compared to the most used methods based only on monthly means. Indeed, the circulation type classification allows a precise and detailed analysis of each circulation type and so, it gives much more information on the ability of GCMs to simulate the different circulation types and consequently the climatic variability of a region. In fact, exceptional circulation events over Greenland, which cannot be taken into account by the monthly mean approach, have much more impact on the melt than the mean atmospheric state. Thus, an automated correlation-based atmospheric circulation type classification (CTC) is used for evaluating the new GCM outputs (available on http://cmip-pcmdi.llnl.gov/cmip5/) computed for the upcoming IPCC report (AR5). The daily geopotential height at 500 hPa simulations of the GCMs for current climate are compared to the NCEP-NCAR 1 and the ECMWF reanalysis data for the summer months (JJA), when melt is the most important. To achieve this, the classification is first done for the reanalysis data over 1961-1990 and afterwards, the types of the reanalysis based CTC are imposed for classifying the GCM datasets over 1961-1990 (from the historical experiment) to allow a direct type per type comparison based on the frequency distribution of each dataset. This approach also gives the opportunity to study the intraclass repartition differences between the reanalysis and the GCMs. After the evaluation of the GCM simulations for current climate, the future projections driven by RCP concentrations or emissions (2011-2040, 2041-2070 and 2071-2100) from the best matching GCMs are analysed in the same way. For current climate, it clearly appears that only a few GCMs are able to reproduce reliably the variability of the atmospheric circulation over Greenland during summer. The differences of frequency between the GCMs and the reanalysis are mainly due to biases of the geopotential height which is systematically over or underestimated by most GCMs and to the underestimation of the variability of the circulation by most GCMs. For future projections, no new circulation types are detected, but rather a general increase of the mean geopotential height regardless of the circulation type. It is also important to note that for many GCMs, the uncertainty of the current climate simulations (given by the differences of the classification results between the GCM simulations for current climate and the reanalysis data for the same time) are of the same order than the projected changes for future climate. Therefore, these projections may be questionable. [less ▲]

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See detailInput of 12CO2 and 13CO2 soil concentration measurements to understand trends in soil carbon production and emission.
Longdoz, Bernard ULg; Plain, Caroline; Parent, Florian et al

Poster (2011, April 05)

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See detailImpact of the spatial resolution on the Greenland Ice Sheet Surface Mass Balance modelling using the regional climate model MAR with the aim to force an ice sheet model.
Franco, Bruno ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

Poster (2011, April 05)

By using the regional climate model MAR (Modèle Atmosphérique Régional), validated for Greenland at 25km resolution and forced every 6 hours with the ERA-INTERIM reanalysis (Fettweis 2007, Fettweis et al ... [more ▼]

By using the regional climate model MAR (Modèle Atmosphérique Régional), validated for Greenland at 25km resolution and forced every 6 hours with the ERA-INTERIM reanalysis (Fettweis 2007, Fettweis et al. 2010), we have modelled the Greenland Ice Sheet (GrIS) Surface Mass Balance (SMB) at 20, 25, 30, 40 and 50km resolution to assess the impact of the spatial resolution. As part of the ICE2SEA project, the 25km-resolution SMB outputs of the MAR model are used as forcing fields for ice sheet models, in order to produce future projections of the GrIS contribution to sea-level rise over the next 200 years. Although the current spatial resolution of the MAR model (25km) is much higher than the general circulation models (GCM) resolution (150-300km), the ice sheet models often run at a higher resolution (typically 5-10km). Nevertheless, such higher-resolution runs of the MAR model on the same integration domain generate a significant additional computing time and are not doable until now. Moreover, conventional linear interpolations of the SMB outputs onto a higher-resolution grid, generally induce biases because ice sheet masks at different spatial resolutions do not match and the SMB is a very complex function of the spatial resolution and the topography . That is why several enhanced SMB interpolations are tested here in order to reduce biases when interpolating the MAR outputs onto higher resolution, in the framework of the ICE2SEA project. [less ▲]

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See detailEvolution of wind behaviour and of its potential for wind power production in Belgium during the last 30 years.
Doutreloup, Sébastien ULg; Fettweis, Xavier ULg; Sacré, Bernard ULg et al

Poster (2011, April 04)

The number of wind turbines in the world grows significantly every year due to politics proposing green energy productions as solutions to mitigate climate change effects. However, this kind of energy is ... [more ▼]

The number of wind turbines in the world grows significantly every year due to politics proposing green energy productions as solutions to mitigate climate change effects. However, this kind of energy is dependent on the weather. This implies that the wind production is irregular at a very short time scale. But the short time scale availability of the wind-based energy is important to the producers of energy as well as to the electric grid managers because the wind energy production can rise or fall rapidly which creates some financial and voltage variations. For these reasons, we study the past evolution of the availability of the wind quantity by analysing the intermittence of the wind speed in Belgium during the last 30 years. To reach this goal, we use the regional model WRF (Weather and Research Forecast model) developed by the UCAR community users. The WRF model is forced by the NCEP2 Reanalysis model to obtain a regionalisation of the weather conditions over a domain centred on Belgium at a spatiotemporal resolution of 10 km and 1 min. This resolution allows to capture the minute-based time scale variability of wind speed and consequently the irregular behaviour of the wind power production. To obtain a value of the wind intermittence, we calculate the persistence of a wind blowing continuously with a minimum speed of 1 ms-1, then the persistence of a wind blowing continuously with a minimum speed of 2 ms-1, etc. The persistence of the wind speed and its evolution over 30 years are characterised by : (a) the mean wind speed over a fixed period (monthly, seasonally, … ), (b) the mean duration of a wind speed above x ms-1 over the same fixed period and (c) the evolution of (a) and (b) during the studied period. This study will show the evolution during the last decades of the wind behaviour in Belgium and its potential for electricity production. [less ▲]

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See detailParticulate carbon export during a bloom of Emiliania huxleyi in the Northwest European continental margin (northern Bay of Biscay)
Schmidt, Sabine; Harlay, Jérôme ULg; Borges, Alberto ULg et al

Poster (2011, April 03)

Coccolithophores, the dominant pelagic calcifiers in the oceans, play a key role in the marine carbon cycle through calcification, primary production and carbon export, the main drivers of the biological ... [more ▼]

Coccolithophores, the dominant pelagic calcifiers in the oceans, play a key role in the marine carbon cycle through calcification, primary production and carbon export, the main drivers of the biological CO2 pump. Massive blooms of Emiliania huxleyi are observed each year at the continental margin of the Bay of Biscay. The BG02/11 cruise (RV Belgica), supported by near-real time remote sensing data, was conducted in early May 2002, along a transect on the outer shelf of the Northern Bay of Biscay between the La Chapelle Bank (southern region of the transect) and Goban Spur (northern region of the transect) (47.0°-50.5°N, 5.0°-11.0°W). Biogeochemical variables including primary production, calcification, partial pressure of CO2 (pCO2), chlorophyll-a (Chl-a), particle load, particulate organic and inorganic carbon (POC, PIC), Th-234 were measured in surface waters to assess particle dynamics, and carbon export in relation to the development of a coccolithophore bloom. We observed a marked northward decrease in water irradiance, Chl-a concentration and calcification rates: the bloom exhibited lower values and may have been less well developed in the Goban Spur area. There was also a large northward decrease in particulate 234Th settling fluxes along the transect from La Chapelle Bank to Goban Spur. The export fluxes of POC and PIC from the top 80 m, determined using the ratios of POC and PIC to Th-234 of particles, ranged from 81 to 323 mgC m-2 d-1 and from 30 to 128 mgC m-2 d-1, respectively. The highest fluxes were observed in waters presenting a well-developed coccolithophore bloom, as shown by high reflectance of surface waters. Despite the high calcification rates at the southernmost stations, surface waters were a net sink of atmospheric CO2 during this cruise. These results tend to demonstrate the enhancement of coccolithophore blooms on the efficiency of the surface community to export carbon to deep ocean. However, improvements in the estimation of POC and PIC export during coccolithophore blooms are needed to not only understand the present calcification to primary production (C:P) ratio, but also to help understand future sequestration of organic and inorganic carbon to the deep ocean. [less ▲]

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See detailBiogeochemistry and carbon mass balance of a coccolithophore bloom in the northern Bay of Biscay (June 2006)
Harlay, Jérôme ULg; Chou, Lei; De Bodt, Caroline et al

Poster (2011, April 03)

Primary production (PP), calcification (CAL), bacterial production (BP) and dark community respiration (DCR) were measured along with a set of various biogeochemical variables, in early June 2006, at ... [more ▼]

Primary production (PP), calcification (CAL), bacterial production (BP) and dark community respiration (DCR) were measured along with a set of various biogeochemical variables, in early June 2006, at several stations at the shelf break of the northern Bay of Biscay. The cruise was carried out after the main spring diatom bloom that, based on the analysis of a time-series of remotely sensed chlorophyll-a (Chl-a), peaked in mid-April. Remotely sensed sea surface temperature (SST) indicated the occurrence of enhanced vertical mixing (due to internal tides) at the continental slope, while adjacent waters on the continental shelf were stratified, as confirmed by vertical profiles of temperature acquired during the cruise. The surface layer of the stratified water masses (on the continental shelf) was depleted of inorganic nutrients. Dissolved silicate (DSi) levels probably did not allow significant diatom development. We hypothesize that mixing at the continental slope allowed the injection of inorganic nutrients that triggered the blooming of mixed phytoplanktonic communities dominated by coccolithophores (Emiliania huxleyi) that were favoured with regards to diatoms due to the low DSi levels. Based on this conceptual frame, we used an indicator of vertical stratification to classify the different sampled stations, and to reconstruct the possible evolution of the bloom from the onset at the continental slope (triggered by vertical mixing) through its development as the water mass was advected on-shelf and stratified. We also established a carbon mass balance at each station by integrating in the photic layer PP, CAL and DCR. This allowed computation at each station of the contribution of PP, CAL and DCR to CO2 fluxes in the photic layer, and how they changed from one station to another along the sequence of bloom development (as traced by the stratification indicator). This also showed a shift from net autotrophy to net heterotrophy as the water mass aged (stratified), and suggested the importance of extracellular production of carbon to sustain the bacterial demand in the photic and aphotic layers. [less ▲]

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See detailNursing care after Transcatheter Aortic Valve Implantation with the Medtronic CoreValve Revalving® system
ERPICUM, Marie ULg; RADERMECKER, Marc ULg; DEFRAIGNE, Jean ULg et al

Poster (2011, April 02)

The risks, complications and results of the transcatheter aortic valve implantation (TAVI) are widely described. But to our knowledge, no one has yet defined the nursing cares required after this ... [more ▼]

The risks, complications and results of the transcatheter aortic valve implantation (TAVI) are widely described. But to our knowledge, no one has yet defined the nursing cares required after this procedure and their effects on the TAVI results. The aims of this review are to describe the nursing cares required after TAVI and to determine which aspects of the management could be optimized to improve the results of the procedure. [less ▲]

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See detailModelling the migration of a mid-Pleistocene erosion wave in the Ardennes (western Europe) drainage network: approach and first implications
Beckers, Arnaud ULg; Bovy, Benoît ULg; Demoulin, Alain ULg

Poster (2011, April)

Model parameterization through adjustment to field data is a crucial step in the modelling and the understanding of the drainage network response to tectonic or climatic perturbations. Using a data set of ... [more ▼]

Model parameterization through adjustment to field data is a crucial step in the modelling and the understanding of the drainage network response to tectonic or climatic perturbations. Using a data set of 18 knickpoints that materialize the migration of a 0.7-Ma-old erosion wave in the Ourthe catchment of northern Ardennes (western Europe) as a test case, we explore the impact of various data fitting on the calibration of the detachment-limited stream power model of river incision, from which a simple knickpoint celerity equation is derived. Our results show that statistical least squares adjustments (or misfit functions) based either on the stream-wise distances between observed and modelled knickpoint positions at time t = 0.7 Ma or on differences between observed (0.7 Ma) and modelled time at the actual knickpoint locations yield significantly different values for the m (more exactly, m/n) and K parameters of the model. As there is no physical reason to prefer one or the other approach, we suggest that an intermediate least rectangles adjustment might be the best compromise. In the Ourthe case, this leads to a m/n value lower than that obtained from the classical distance adjustment (0.79 against 0.86), leading to an increase in the non linear character of the dependence of knickpoint celerity on discharge. If we now recall that m/n = c(1-b) (Whipple & Tucker, 1999, JGR 104B: 17661-17674), where c and b are the exponents of the power law relations respectively linking discharge to drainage area and channel width to discharge, we can compare the calculated m/n value with that derived from field measurements of channel width, discharge and drainage area in the presently graded sections of the rivers. Such data taken from Petit et al. (2005, BSGLg 46: 37-50) allow us to derive m/n = 0.48 at equilibrium. As c may be considered constant, the higher m=n value obtained from the knickpoint retreat modelling must be ascribed to a lower b, i.e., to a channel narrowing associated with the transient phase of knickpoint migration. [less ▲]

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See detailEtude préliminaire sur la biologie de la mineuse des fruits du safoutier Dacryodes edulis (G. Don.) H.J. Lam. ;Burseraceae) dans le Haut-Ogooué, Gabon.
Poligui, René Noël ULg; Mouaragadja, Isaac; Francis, Frédéric ULg et al

Poster (2011, April)

Le monitoring de l’entomofaune du safoutier (Dacryodes edulis (G. Don.) H.J.Lam. (Burseraceae) a été réalisé dans le Haut-Ogooué (Gabon) sur deux années successives (2009-2010), du mois d’août au mois ... [more ▼]

Le monitoring de l’entomofaune du safoutier (Dacryodes edulis (G. Don.) H.J.Lam. (Burseraceae) a été réalisé dans le Haut-Ogooué (Gabon) sur deux années successives (2009-2010), du mois d’août au mois décembre. Cette période correspond à la phase de production des fruits (safou) de cet arbre. Parmi les insectes nuisibles inventoriés, la mineuse (Lepidoptera ; Tortricidae) des safou constitue le ravageur majeur causant la chute de 25% des fruits sur grappes. La femelle pond sur les fruits dès la première semaine suivant leur nouaison. Les larves roses, à tête brune, creusent une petite galerie à l’intérieur du fruit dont elles dévorent le noyau. Avant la chute du fruit, la larve sort et nymphose au sol dans un cocon en soie, et l’imago, un petit papillon gris, émerge après deux semaines. Un Ichneumonidae a été reconnu comme parasitoïde de ses larves. Pseudopsondias microcarpa(A.Rich) Engl.(Anacardiaceae) a été identifié comme un autre arbre fruitier hôte de cet insecte. Des études ultérieures approfondiront la connaissance de ce ravageur et pourront permettre d’envisager une stratégie de lutte biologique contre cette mineuse. [less ▲]

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See detailProfils de liaison et mécanismes d’internalisation des norovirus bovins de génotype 2
Mauroy, Axel ULg; Gillet, Laurent; Mathijs, Elisabeth et al

Poster (2011, April)

Appartenant à la famille des Caliciviridae genre Norovirus, les norovirus (NoV) sont des virus non enveloppés dont le génome est composé d’un ARN monocaténaire de polarité positive d’approximativement 7,5 ... [more ▼]

Appartenant à la famille des Caliciviridae genre Norovirus, les norovirus (NoV) sont des virus non enveloppés dont le génome est composé d’un ARN monocaténaire de polarité positive d’approximativement 7,5 kb. Les NoV infectent l’homme et les animaux (bovins, porcins, murins). Chez l’homme, ils sont des agents majeurs de gastroentérite sporadique ou épidémique d’origine souvent alimentaire. Chez le bovin, ils causent également une entérite bénigne et les souches mises en cause sont classées génétiquement dans deux génotypes au sein du génogroupe III du genre Norovirus. La voie d’infection des NoV est oro-fécale, ils sont très résistants dans l’environnement et une infection peut survenir même avec une très faible dose infectieuse. Les NoV humains et animaux sont relativement proches génétiquement et coexistent parfois de manière très étroite en Europe du Nord. Il est donc logique d’envisager le risque zoonotique lié aux NoV animaux et plus particulièrement celui lié aux norovirus bovins (BoNoV). Différents systèmes d’expression protéique ont permis d’obtenir des pseudoparticules virales (VLPs) morphologiquement et antigéniquement semblables à certaines souches de NoV, difficilement cultivables en culture de cellules. Les objectifs du travail étaient d’étudier les types de structures pouvant être impliquées dans la liaison de BoNoVLP aux cellules, ainsi que les mécanismes entrant en jeu pour leur internalisation. Dans une première étude, des VLP d’une souche BoNoV obtenues précédemment ont permis d’investiguer le spectre de liaison des BoNoV de génotype 2 par immunofluorescence indirecte sur des cultures cellulaires bovines d’origines tissulaires différentes. Les VLP ont été capables de se fixer sur chacune des lignées testées tandis que la fluorescence diminuait d’intensité après traitement des cellules par le periodate de sodium. Au cours d’une deuxième étude, les structures permettant l’attachement des BoNoV de génotype 2 ont été investiguées quantitativement en cytométrie en flux avec les VLP. Parmi les enzymes et substances utilisées pour traiter les cellules, le periodate de sodium, l’α-galactosidase, la trypsine, la chymotrypsine et la phospholipase C ont très significativement diminué l’intensité du signal tandis que la neuraminidase a également permis de le réduire modérément. Les sulfates d’héparane ou de chondroïtine n’étaient par contre pas impliqués. Une troisième étude, toujours réalisée en cytométrie en flux, a permis d’évaluer les voies d’internalisation des VLP. Au cours de cette étude, il a été montré que les voies liées aux radeaux lipidiques et de la macropinocytose étaient impliquées. Les trois études menées ont permis de montrer que la structure impliquée dans la liaison des BoNoV de génotype 2 est un saccharide présent sur de nombreux types cellulaires bovins ; que cette structure comprend un résidu α-galactose ; qu’un résidu acide neuraminique peut être aussi impliqué dans cette liaison ou peut la faciliter ; que les sulfates d’héparane et de chondroïtine ne le sont pas ; que des voies alternatives peuvent être utilisées pour l’internalisation de la VLP. Les différents résultats peuvent être intégrés dans le profil de risque zoonotique associé aux BoNoV. [less ▲]

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See detailGold and silver nanomaterials based biosensors : a comparative study
Dreesen, Laurent ULg; Lismont, Marjorie ULg

Poster (2011, April)

Noble metal nanoparticles (NPs) are intensively studied due to their particular optical properties, mainly high optical absorption and diffusion yields, leading to interesting applications in biochemical ... [more ▼]

Noble metal nanoparticles (NPs) are intensively studied due to their particular optical properties, mainly high optical absorption and diffusion yields, leading to interesting applications in biochemical sensing, molecular tracking and imaging, drug delivery and photothermal therapies [1]. These unique optical properties arise from a physical process named surface plasmon resonance (SPR) which is a resonant coupling of incident light to the collective motion of electrons along the nanoparticles surface [2]. Optical SPR biosensors are able to measure complex formation in real time. Indeed, the SPR absorption spectrum band of the NPs is sensitive to the shape, size, inter-particle distance and composition of the NP as well as the dielectric properties of the surrounding medium [2]. Due to the sensitivity of SPR to the local dielectric environment, plasmonic NPs can thus act as transducers that convert small changes in the local refractive index or in the inter-particle distance into spectral shifts and broadenings of the absorption spectral bands [3]. Among metals, silver and gold NPs have received considerable interest for many reasons. For instance, they are stable in ambient atmosphere and exhibit good biocompatibility even if particular surface treatments are sometimes required. The Ag and Au NPs are also relatively easy to fabricate with different sizes and shapes allowing the tuning of the SPR optical absorption band from the near ultraviolet (400 nm) to the near infrared (1000 nm) wavelengths. In this study, our aim is to characterize two biosensors based on silver and gold spherical NPs in order to detect which one seems the best. Both NPs have a diameter close to 15 nm. We use the well-known biocytin-avidin complex as a model system because the bonding of avidin with biocytin is extremely strong with a dissociation constant three order of magnitude higher than the typical constants of antigen-antibody interactions. More precisely, we compare the intensities, the band shapes and the spectral locations of the SPR adsorption bands before and after the biomolecular recognition of avidin by biocytin molecules adsorbed on the Ag and Au NPs. The kinetic of the interaction is also discussed. Before surface treatment with biocytin, the NPs SPR bands are located around 390 and 520 nm for Ag and Au NPs, respectively. The SPR band intensity is higher for silver than for gold. Biocytin adsorption does not significantly modify the SPR spectral features. NPs do not therefore form aggregates and the local refraction index has not significantly changed. After avidin addition, a SPR red-shift and a broadening of the SPR bands are observed with both NPs as shown on Figure 1. These parameters evolved with time and reach their final values after around 45 min for each system. The aforementioned spectral changes arise from the biomolecular recognition process between biotin and avidin which leads to the NPs aggregation. The recognition process also induces a variation of the local refractive index around these NPs which contributes to the red-shift. The maximum SPR shifts are equal to 25 nm and 12 nm for silver NPs and gold NPs, respectively. Our results highlight the smaller dielectric sensitivity of gold NPs compared to the silver NPs one for a same particles’ size and for an equivalent concentration of avidin. The detection limit, described as the lowest concentration for clear identification of wavelength shift due to biomolecular recognition, is equal to 4 nM for both silver and gold NPs. With this protein concentration, 3 nm is the typical wavelength shift. The specificity of the biocytin - avidin biosensors is verified by replacing avidin by Bovine Serum Albumina (BSA). When BSA is added, we observe a SPR band shift which is smaller than the detection limit of 3 nm attesting the biosensor selectivity. Our work demonstrates the superiority of Ag over Au NPs for the elaboration of biosensors based on SPR. However, it is well-known that Ag NPs are less biocompatible than gold. This problem can be circumvented by an appropriate coating of the NPs surface prior ligand adsorption. [less ▲]

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See detailCombustion control and performance of household condensing boilers
Makaire, Danielle ULg; Ngendakumana, Philippe ULg

Poster (2011, April)

The present work presents a model that is composed of a conventional boiler model with a main counterflow gas-water heat exchanger at which a condensing heat exchanger is added. Prior to the second heat ... [more ▼]

The present work presents a model that is composed of a conventional boiler model with a main counterflow gas-water heat exchanger at which a condensing heat exchanger is added. Prior to the second heat exchanger the exhaust gas are converted to equivalent wet air as the wet heat exchanger is simulated by a cooling coil used in air treatment. Six parameters are needed for calculation and these parameters are fitted with experimental data: one test in dry regime and one test in wet regime. Steady-state tests have been performed on two household boilers (a gas-fired and a fuel oil boiler), whose nominal outputs are 24 kW in order to fit the model parameters and check the model behaviour. It seems that the model gives the correct trend for the thermal efficiency prediction. Besides, combustion controls sensors (non nernstian sensors) have been tested by varying the excess of air. In the range tested (from =1.05 to =1.25), the increase in the boiler efficiency is around 1% as the excess of air decreases. However that increase is lower than the measurement uncertainty. The developed model predicts very well that trend. The pollutants emissions have also been measured and the results show that the NOx emissions decrease as the excess air increases. [less ▲]

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See detailHomoparentality and Family Alliances: Studying Triadic Interactions
D'Amore, Salvatore ULg; Scarciotta, Lidia; Miscioscia, Marina ULg

Poster (2011, April)

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See detailSeaDataNet regional climatologies: an overview
Troupin, Charles ULg; Ouberdous, Mohamed ULg; Barth, Alexander ULg et al

Poster (2011, April)

In the frame of the SeaDataNet project, a set of regional climatologies for temperature and salinity has been developed by the different regional groups. The data used for these climatologies are ... [more ▼]

In the frame of the SeaDataNet project, a set of regional climatologies for temperature and salinity has been developed by the different regional groups. The data used for these climatologies are distributed by the SeaDataNet data centers. These climatologies have several uses: 1. The detection of outliers by comparison of the in situ data with the climatological fields; 2. The the optimization of locations of new observations; 3. The initialization of numerical hydrodynamic model; 4. The definition of a reference state to identify anomalies and to detect long-term climatic trends. These climatologies are produced with the help of the Data Interpolating Variational Analysis (DIVA) software. Here we present the latest developments in the regional climatologies along with the choice of parameters by the different groups. [less ▲]

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See detailSimulating the Holocene re-colonization of Europe by tree species using dynamic vegetation models
Dury, Marie ULg; Lehsten, Dörte; Dullinger, Stefan et al

Poster (2011, April)

At the beginning of the Holocene (10.000 BP) started a progressive re-colonization of Europe by temperate tree species from a limited number of glacial refugia. To reconstruct the speed, seemingly species ... [more ▼]

At the beginning of the Holocene (10.000 BP) started a progressive re-colonization of Europe by temperate tree species from a limited number of glacial refugia. To reconstruct the speed, seemingly species-specific, and the routes of the postglacial spread of European tree species, fossil records collected from various localities in Europe are invaluable. However, the relative roles of climatic fluctuations, dispersal capacities of individual species, and inter-specific competition in controlling the re-colonization rates remain controversial. We investigate these different aspects with two dynamic vegetation models (DVM), LPJ-GUESS and CARAIB. Transient runs of both models were performed over the Holocene, using HadCM3 GCM-reconstructed climate. Large-scale species migration at 0.5◦ x0.5◦ is represented in these models using migration rates derived from a small-scale cellular automaton, CATS. Individual tree species migration rates were pre-calculated with CATS every 1000 years over each grid cell used by the DVMs in the climatic conditions reconstructed by the GCM. In the DVMs, these migration speeds were influenced by the response to competition from other species, expressed as a function of net primary production ratios. The DVMs were used to study the migration of one species, from its 10.000 BP refugia, within a landscape defined by a set of other species for which no dispersal limitations are assumed. Here, we illustrate the results obtained for wind-dispersed tree species and compare them to their past distributions reconstructed from pollen and macrofossil data. [less ▲]

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See detailEvidence of wind-induced temperature anomalies in the tropical and subtropical North Atlantic Ocean in winter-spring 2010
Troupin, Charles ULg; Machín, Francis

Poster (2011, April)

During the first months of 2010, the tropical and subtropical North Atlantic displayed anomalously high temperatures, with values seldom observed during the last decades. In situ and remote sensing data ... [more ▼]

During the first months of 2010, the tropical and subtropical North Atlantic displayed anomalously high temperatures, with values seldom observed during the last decades. In situ and remote sensing data are used to evaluate horizontal, vertical and temporal extensions of the anomalies. The repercussions on the seasonal evolution of the mixed layer are examined; in particular, it is shown that the northwest Africa coastal upwelling is significantly weakened in comparison to previous years. The consequences on the biological variables are examined by means of satellite-derived measurements. A simple mechanism related to changes in wind intensity is proposed in order to explain our observations. The wind weakening coincides with a strongly negative value of the North Atlantic Oscillation index. [less ▲]

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See detailAtmospheric mercury deposition during the last 1500 years in We Europe: The Misten peat bog record (Hautes Fagnes - Belgium)
Allan, Mohammed ULg; Fagel, Nathalie ULg; De Vleeschouwer, François et al

Poster (2011, April)

The current rate of global atmospheric Hg deposition is approximately three times higher than the preindustrial record and it even increased by a factor of 2-10 in the industrialized regions ... [more ▼]

The current rate of global atmospheric Hg deposition is approximately three times higher than the preindustrial record and it even increased by a factor of 2-10 in the industrialized regions.....()(Hylander and Meili 2003). To determine the extent of such increase, it is necessary to quantify the atmospheric mercury concentration and its temporal variation. For this purpose four 1m Wardenaar peat cores (MIS01W, 04W, 0W5 and 06W) were collected in 2008 in the ombrotrophic Misten bog (Hautes Fagnes Plateau, East Belgium). Mercury was measured using a DMA 80 at the Laboratory of Mechanisms and Transfers in Geology in Toulouse (LMTG, France). The strongest mercury concentrations are measured in the upper half peat record, in a depth interval corresponding to the Industrial Revolution period. Mercury accumulation rate was estimated by applying a coupled 210Pb- 14C age model. The mercury accumulation rate remains relatively small, ranging between 0.9 and 3.3 g.m 2.y 1 during periods corresponding to the decline of Roman Empire and during the Middle Ages. Hg accumulation rate starts to increase when 25 cm, reaching a maximum value (> 115 g.m 2.y 1) at 13.7 cm (i.e.; 1923-1938 AD). Then the values oscillate to reach 9 g.m 2.y 1 at the peat surface (2000-2007AD). In the Misten bog, the evolution of Hg accumulation rate is in agreement with the chronology of other European peat records .......()(Roos-Barraclough et al. 2002). [less ▲]

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See detailParameterizing the root system development of summer barley using minirhizotron data
Garré, Sarah ULg; Pagès, Loïc; Javaux, Mathieu et al

Poster (2011, April)

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See detailAdvanced Data Interpolating Variational Analysis. Application to climatological data
Troupin, Charles ULg; Sirjacobs, Damien ULg; Rixen, Michel et al

Poster (2011, April)

DIVA (Data Interpolating Variational Analysis) is a variational analysis tool designed to interpolate irregularly-spaced, noisy data onto any desired location, in most cases on regular grids. It is the ... [more ▼]

DIVA (Data Interpolating Variational Analysis) is a variational analysis tool designed to interpolate irregularly-spaced, noisy data onto any desired location, in most cases on regular grids. It is the combination of a particular methodology, based on the minimization of a functional, and a numerically efficient resolution method, based on a finite elements solver. The intrinsic advantages of DIVA are its natural way to take into account topographic and dynamic constraints (coasts, advection, ...) and its capacity to handle large data sets, frequently encountered in oceanography. In the present work, we describe various improvements to the variational analysis tool. The most significant advance is the development of a full error calculation, whilst until now, only an approximate error-field estimate was available. The key issue is the numerical determination of the real covariance function in DIVA, which is not formulated explicitly. This is solved by two concurrent executions of two DIVA, one providing the covariance for the other. The new calculation of the error field is now perfectly coherent with the inherent background covariance in all cases. The correlation length, which was previously set uniform over the computational domain, is now allowed to vary spatially. The efficiency of the tools for estimating the signal-to-noise ratio, through generalized cross-validation, has also been improved. Finally, a data quality-control method is implemented and allows one to detect possible outliers, based on statistics of the data-reconstruction misfit. The added value of these features are illustrated in the case of a large data set of salinity measured in the Mediterranean Sea. Several analyses are performed with different parameters in order to demonstrate their influence on the interpolated fields. In particular, we examine the benefits of using the parameter optimization tools and the advection constraint. The results are validated by means of a subset of data set apart for an independent validation. The corresponding errors fields are estimated using different methods and underline the role of the data coverage. [less ▲]

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See detailAssessing the impacts of present and future interannual climate variability on European ecosystems using a dynamic vegetation model
Dury, Marie ULg; Hambuckers, Alain ULg; Warnant, Pierre et al

Poster (2011, April)

Climate projections indicate changes in mean climate as well as in climate variability and frequency of extreme events for the end of the 21st century compared to present. Since many biological processes ... [more ▼]

Climate projections indicate changes in mean climate as well as in climate variability and frequency of extreme events for the end of the 21st century compared to present. Since many biological processes reach non-reversible thresholds (loss of ability to germinate, mortality, etc.) at some temperatures or soil water values, changes in climate variability have long-term consequences for ecosystem composition, functioning and carbon storage. The CARAIB dynamic vegetation model is used to evaluate and analyse how future climate variability will affect European ecosystems. We examine the impacts of climate change and associated drought episodes on primary productivity (NPP) as well as on fire intensity. CARAIB is driven by the ARPEGE/Climate model and three regional climate models from the European Union project ENSEMBLES (KNMI-RACMO2, DMI-HIRHAM5 and HC-HadRM3Q0 models) forced with the IPCC A1B emission scenario. We analyse the interannual climate variability simulated by those climate models and compare it with the observed climate variability (CRU TS 3.0 historical climate dataset) over the period 1961-1990. None of these climate models can reproduce accurately the present natural climate variability. Therefore, the present NPP interannual variability simulated by CARAIB using climate outputs from the climate models differs from the one obtained with observed climate. For instance, the NPP interannual variability obtained with the ARPEGE/Climate model is significantly overestimated in some parts of Europe, especially in the Mediterranean region, in France, in northern Germany and northern Poland, in the Balkans and in Ukraine. Since discrepancies between modelled and observed current climate variability may also affect NPP variability calculated for the future as well as the intensity and the frequency of severe drought periods and wildfires, comparing the terrestrial ecosystem evolutions obtained with a range of climate models allows to improve the assessment of climate change impacts on ecosystems in the future. Anyway the trend between the present and the future is expected to be more robust. The NPP interannual variability increases in the future with the four climate models as a result of more frequent and more severe soil water stress episodes in southern and Central Europe. The projected climate changes are also likely to induce increased fire risk in the Mediterranean region but also in Central Europe and Russia. [less ▲]

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See detailSpatio-temporal localization of the cytoskeleton during auditory organ development in mammalia
Johnen, Nicolas ULg; Thelen, Nicolas ULg; Cloes, Marie ULg et al

Poster (2011, March 31)

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary ... [more ▼]

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary for the sound perception. Theses cells are supported by supporting cells. Based on their morphology and physiology, at least four types of supporting cells (SC) can be identified in the OC: inner and outer pillar cells (PC), phalangeal cell and Deiter’s cells. Sensory and supporting cells possess characteristic cytoskeleton proteins in direct relation with their morphological features and their development. Indeed, this organ had morphological changes such as the setting up of the sensory epithelium after the birth or the openings of the Corti’s tunnel at P8 and of the Nuel’s spaces at P10. In the present study, by using confocal microscopy, we investigated the spatio-temporal localization of the three cellular cytoskeletal filaments : microtubules (β-1, 2, 3, 4-tubulin), microfilaments (cytoplasmic β- and γ-actin) and intermediate filaments (CK4, 5, 7, 8, CKpan and vimentin) during the development of the OC in rat from the embryonic day 18 (E18) to the post-natal day 25 (P25). The immunolabellings indicated clearly that β-1, 2, 3-tubulins were only present the SC and nervous fibers during development whereas β-4-tubulin was found firstly in the HC and then in the SC. The two actin-isotypes were detected in the HC apex but were also seen in the PC from P8 to P25 for β-actin isoform and in the basal membrane from E18 to P8 for the γ-actin isoform. All intermediate filament proteins were only found in the SC, especially between P8 and P12. Our results show that the localization of the cytoskeleton proteins during the auditory organ development depends on the cellular type and the developmental stage. A profound modification of cytoskeleton occurs between P8 and P12. [less ▲]

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See detailStructure spatiale et impact écologique des processus d'anthropisation des paysages terrestres: développement d'une instrumentation générique d'analyse
Vranken, Isabelle ULg; Bogaert, Jan ULg

Poster (2011, March 28)

The current research project aims to develop a generic set of analysis methods which enables to characterize quantitatively anthropogenic degradation of terrestrial ecosystems. This characterization will ... [more ▼]

The current research project aims to develop a generic set of analysis methods which enables to characterize quantitatively anthropogenic degradation of terrestrial ecosystems. This characterization will assist in landscape planning oriented towards a sustainable management of human impacts and towards a restoration of degraded ecosystems. The analysis methods will enable to detect landscape degradation and its anthropogenic drivers based on their spatial properties, a type of information that is less complex and less expensive to obtain than ecological data collected in situ. The project is composed of two parts: (1) methodological research and development, based on the principles of landscape ecology and combined with other disciplines like remote sensing, geographic information systems, sociology and agronomy; (2) application of the developed pattern metrics on new study cases for evaluation and validation. Using study cases of degradation situated worldwide, the development of a typology will enable to identify, classify and analyze the causes of degradation, their spatial properties and the ecosystems involved. These study cases will be chosen based on the types of ecosystems degraded, the spatial scale of degradation, the climatic zone, and the intensity and speed of landscape degradation. Every type will be analyzed with regard to its impact on spatial pattern. Afterwards, the different metrics will be evaluated statistically for comparison with regard to their potential to capture anthropogenic effects. The development of new metrics is hereby not excluded. Critical thresholds will be defined in order to detect critical degradation levels of the terrestrial ecosystems. The best metrics selected in this way will be calculated for new cases of anthropogenic impacts on landscapes, cases selected by application of the aforementioned typology, in order to validate the correlation between metric outcomes and in situ observations. [less ▲]

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Peer Reviewed
See detailTemporal evolution and extreme value analysis of precipitations in Burkina Faso
Bel, Liliane; Weiss, Jérôme; Boreux, Jean-Jacques ULg et al

Poster (2011, March 23)

Modeling of damaging extreme events is of great interest for the risk managers who want to implement some protections. It is based on the so-called generalized extreme values model. In the environmental ... [more ▼]

Modeling of damaging extreme events is of great interest for the risk managers who want to implement some protections. It is based on the so-called generalized extreme values model. In the environmental sciences, we need to model the extremes of two or more processes like the daily rainfall recorded in various points of a given region. Each individual process could be modeled using univariate technique, but this strategy could not take into account for dependence of extreme values. For instance, consider two sites A and B fairly close to one another. If we observe an extreme value of the daily rainfall at site A, this information impacts the probability to observe an extreme value at site B even if we never recorded such value at B. The basic modeling tool is formed by so-called max-stable processes which take into account the possible spatial dependence through so-called extremal coefficient. We illustrate with annual maximum daily rainfall values recorded in 41 stations in Burkina Faso. [less ▲]

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See detailAdvanced Data Interpolating Variational Analysis. Application to climatological data.
Troupin, Charles ULg; Sirjacobs, Damien ULg; Rixen, Michel et al

Poster (2011, March 21)

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Peer Reviewed
See detailReversal of acepromazine-induced hemodynamic alterations by norepinephrine in standing horses
pequito, Manuel; Amory, Hélène ULg; Peters, Fabrice et al

Poster (2011, March 18)

Acepromazine (ACP) is a phenothiazine commonly used to sedate horses. Additionally, ACP exerts strong anti-inflammatory effects, which might have a therapeutic potential in horses suffering from systemic ... [more ▼]

Acepromazine (ACP) is a phenothiazine commonly used to sedate horses. Additionally, ACP exerts strong anti-inflammatory effects, which might have a therapeutic potential in horses suffering from systemic inflammatory response syndrome (SIRS). However, the ACP-induced vasodilation precludes its use in horses with SIRS-related cardiovascular compromise. The objective of this study was to test if the hemodynamic effects of the administration of 0,1 mg/kg of ACP could be counteracted by an intravenous infusion of norepinephrine (NOR) at 1ug/kg/min in healthy horses. In 5 healthy adult horses, a 15 minutes NOR IV infusion was administered 45 minutes after an injection of 0,1 mg/kg of ACP IV. The systolic arterial blood pressure (SAP) was non-invasively measured by Doppler sphingometry at the tail. Hemodynamics of the median artery of the left forelimb were studied using Doppler ultrasonography, through calculation of the vessel’s surface (SURF), diameter (DIAM), circumference (CIRC), and peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (MV), volumetric flow (VF) and resistivity index (RI) of the flow. Both SAP and Doppler parameters were determined at regular intervals during the entire study. ACP induced a hypotension and a vasodilatation, that were evidenced by a significant rise of the SURF, DIAM, CIRC, PSV, EDV, MV and VF and reduction of the SAP and RI. During NOR infusion, all these ACP-induced hemodynamic changes were reversed. These findings suggest that a continuous IV NOR infusion at 1ug/kg/min is able to revert ACP-induced hypotension and vasodilation in healthy adult horses. [less ▲]

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See detailTwo-Dimensional, M-Mode and Pulsed Wave Doppler Echocardiographic Reference Values in Healthy Adult Saanen Goats
Leroux, Aurélia ULg; Moonen, Marie ULg; Farnir, Frédéric ULg et al

Poster (2011, March 18)

Echocardiography has become a routine non invasive cardiac diagnostic tool in most species. Accurate measurement of cardiac dimensions requires reference values, which are poorly documented in goats ... [more ▼]

Echocardiography has become a routine non invasive cardiac diagnostic tool in most species. Accurate measurement of cardiac dimensions requires reference values, which are poorly documented in goats. Goats are animals easy to handle with a body and heart size comparable to humans’. This makes goats an attractive candidate for the development of animal models for human cardiology research. The aim of this study was to test the repeatability and to establish the reference values of bi-dimensional (2D-), time-motion (M-) mode and pulsed wave (PW) Doppler echocardiographic variables in adult goats. Six healthy female adult Saanen goats were investigated three times by the same observer at one day interval using a standardized 2D-, M-mode and PW Doppler echocardiographic protocol. Calculation of the coefficient of variation for each variable measured within day and depending on the day allowed to evaluate their degree of variability. A single echocardiographic examination was performed in 6 other goats by the same observer, and the obtained values were added to these obtained on the third day of the 6 first goats. Then the observed mean, the standard deviation and the range of these measurements were calculated to establish the reference values of echocardiographic parameters in unsedated adult healthy female Saanen goats. Statistical analysis revealed a good inter-day repeatability of the 2D- and M-mode echocardiographic cardiac measurements, but PW Doppler parameters presented moderate to high variability, as documented in other species. Echocardiographic reference values obtained in healthy adult Saanen goats were similar to those reported in healthy adult sheep and in healthy adult humans. [less ▲]

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