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See detailMercury immune toxicity in harbour seals: Links to in vitro toxicity
Das, Krishna ULg; Siebert, Ursula; Gillet, Audrey et al

in Environmental Health : A Global Access Science Source (2008), 7

Background Mercury is known to bioaccumulate and to magnify in marine mammals, which is a cause of great concern in terms of their general health. In particular, the immune system is known to be ... [more ▼]

Background Mercury is known to bioaccumulate and to magnify in marine mammals, which is a cause of great concern in terms of their general health. In particular, the immune system is known to be susceptible to long-term mercury exposure. The aims of the present study were (1) to determine the mercury level in the blood of free-ranging harbour seals from the North Sea and (2) to examine the link between methylmercury in vitro exposure and immune functions using seal and human mitogen-stimulated peripheral blood mononuclear cells (T-lymphocytes). Methods Total mercury was analysed in the blood of 22 harbour seals. Peripheral blood mononuclear cells were isolated from seals (n = 11) and from humans (n = 9). Stimulated lymphocytes of both species were exposed to functional tests (proliferation, metabolic activity, radioactive precursor incorporation) under increasing doses of methylmercury (0.1 to 10 µM). The expression of cytokines (IL-2; IL-4 and TGF-beta was investigated in seal lymphocytes by RT-PCR and by real time quantitative PCR (n = 5) at methylmercury concentrations of 0.2 and 1 µM. Finally, proteomics analysis was attempted on human lymphocytes (cytoplasmic fraction) in order to identify biochemical pathways of toxicity at concentration of 1 µM (n = 3). Results The results showed that the number of seal lymphocytes, viability, metabolic activity, DNA and RNA synthesis were reduced in vitro, suggesting deleterious effects of methylmercury concentrations naturally encountered in free-ranging seals. Similar results were found for human lymphocytes. Functional tests showed that a 1 µM concentration was the critical concentration above which lymphocyte activity, proliferation and survival were compromised. The expression of IL-2 and TGF-beta mRNA was weaker in exposed seal lymphocytes compared to control cells (0.2 and 1 µM). Proteomics showed some variation in the protein expression profile (e.g. vimentin). [less ▲]

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See detailMercury in blood of free-ranging seals Phoca vitulina from the North Sea: Time-trend and association with environmental factors
Das, Krishna ULg; Brochoire, Charlène ULg; Chambosse, Mélanie et al

Conference (2012, March 27)

The harbour seal (Phoca vitulina) population from the North Sea has experienced various fluctuations these last decades due to habitat loss, prey fluctuation and pollution of the marine environment ... [more ▼]

The harbour seal (Phoca vitulina) population from the North Sea has experienced various fluctuations these last decades due to habitat loss, prey fluctuation and pollution of the marine environment. Recently, development of monitoring programs and non-invasive sampling techniques, including seal catches allowed blood sampling on a regular basis together with measurements of blubber thickness, body mass, sex and body length. Concentrations of total mercury (T-Hg) and other trace elements (Cd, Pb, Zn, Cu, Fe) as well as ∂13C and ∂15N values were determined by mass spectrometry in blood of 75 wild harbour seals caught in the German Wadden Sea between 1997 and 2011. ∂13C and ∂15N mean values (-17.5‰ and 18.1 ‰ respectively) were strongly similar to that measured previously in the muscle of stranded harbour seals from the Wadden Sea. In contrast, ∂15N mean value was strikingly higher than that recorded in grey seals (Halichoerus grypus) from Scotland (14.1 ‰ respectively; Habran et al. submitted.) while ∂13C values remained similar between the two seal species. These values confirmed the high trophic position of the harbour seal in the North Sea. In contrast to Cd and Pb, T-Hg in blood harbour seals reached concentrations as high as 2.1 μg.g-1 dry weight (10 times higher than the 0.21 μg.g-1 dry weight recorded for grey seals from Scotland) but depended on several factors including ∂15N values, age group and the body mass. T-Hg was detected in juveniles confirming maternal transfer to offspring and time-trend revealed no decrease of T-Hg in blood of harbour seals these last 15 years. [less ▲]

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See detailMercury in the blood of free ranging pinnipeds: levels, sources of variation, toxicocinetic and potential impact using an in vitro model
Das, Krishna ULg; Gillet, Marie-Claire ULg; Habran, Sarah ULg et al

Conference (2007)

Despite 30 years of international regulations, Hg levels in marine mammals have not decreased. Various environmental models even suggest a rise of mercury in the biota during the next decades, linked to ... [more ▼]

Despite 30 years of international regulations, Hg levels in marine mammals have not decreased. Various environmental models even suggest a rise of mercury in the biota during the next decades, linked to climate change. The objective of this study is (1) to assess Hg levels in blood samples of free-ranging pinnipeds, (2) to understand level variation during different periods of life (gestation, lactation, fasting) and potential impact on lymphocytes using a preliminary in vitro model (peripheral blood mononuclear cells, PBMC). Blood samples were collected from harbour seals (Phoca vitulina n= 22) from the North Sea and from elephant seals from the Californian coast (Mirounga angustirostris 12 females and 12 pups). Harbour seal PBMC were isolated, set in medium culture and contaminated with methyl-Hg (1 µM). Biological tests and proteomic assay were realized on control and contaminated PBMC. Hg levels were from the same order of magnitude for the two species despite two different lifestyles and habitats: from 40 to 590 ng.g-1 fw in harbour seal and from 63 to 919 ng.g-1 fw in elephant seal. Hg concentrations in the blood depend upon several factors such as body weight, fasting and lactation duration for mothers and pups. After 21 days of lactation, female elephant seals doubled their blood Hg levels (from 308 to 593 ng.g-1fw) while a decrease is observed for pups. This increase is linked to mobilization from blubber and muscle during fasting associated to lactation. Cell model revealed an in vitro effect of Hg even at low concentration (1µM). Number of PBMC, viability, metabolic activity, DNA and RNA synthesis were reduced in vitro suggesting deleterious effects of Hg in concentrations encountered in free-ranging pinnipeds. Knowing that Hg methylation in the ocean is linked to temperature, one can wonder on Hg levels (and effects) in pinnipeds during the next decades. [less ▲]

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See detailMercury porosimetry applied to low density xerogels
Pirard, René ULg; Heinrichs, Benoît ULg; Pirard, Jean-Paul ULg

in Characterization of Porous Solids IV (1997)

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See detailMercury porosimetry applied to low density xerogels
Pirard, René ULg; Heinrichs, Benoît ULg; Van Cantfort, Olivier et al

Poster (1997)

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See detailMercury porosimetry applied to low density xerogels; relation between structure and mechanical properties
Pirard, René ULg; Heinrichs, Benoît ULg; Van Cantfort, Olivier et al

in Journal of Sol-Gel Science and Technology (1998), 13(1-3), 335-339

Samples of low density xerogels were submitted to mercury porosimetry at pressures up to 200 MPa. These samples show an unusual behavior: they are first crushed by the isostatic mercury pressure without ... [more ▼]

Samples of low density xerogels were submitted to mercury porosimetry at pressures up to 200 MPa. These samples show an unusual behavior: they are first crushed by the isostatic mercury pressure without mercury intrusion and are then intruded by the mercury above a certain pressure. This transition allows the easy determination of the one constant found in the buckling model that is used to interpret the crushing part of the mercury porosimetry experiment. The relation between this constant and the structure of the xerogels determined by TEM and nitrogen adsorption is discussed. [less ▲]

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See detailMercury porosimetry applied to porous silica materials: successive buckling and intrusion mechanisms
Alié, Christelle ULg; Pirard, René ULg; Pirard, Jean-Paul ULg

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (2001), 187

Some silica low-density xerogels exhibit two successive volume variation mechanisms, compaction and intrusion when submitted to mercury porosimetry. The position of the pressure of transition P-t between ... [more ▼]

Some silica low-density xerogels exhibit two successive volume variation mechanisms, compaction and intrusion when submitted to mercury porosimetry. The position of the pressure of transition P-t between the two mechanisms is characteristic of the tested material and allows to compute the buckling constant used to determine the pore size distribution in the compaction part of the experiment. The analysis of the mercury porosimetry data of a low-density xerogel wrapped in a tight membrane by the buckling law (intrusion is prevented and the sample is crushed during the whole porosimetry experiment) leads to a continuous unimodal distribution similar to the distribution of the unwrapped sample obtained by applying the buckling law below P-t and the intrusion law above P-t. This experiment confirms the validity of the use of the buckling law. The behaviour of the low-density xerogels can be related to one of their morphological characteristics. As the size of the aggregates of silica particles increases, the strength towards crushing increases and the change of mechanism from crushing to intrusion takes place at a lower pressure. (C) 2001 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMercury porosimetry: applicability of the buckling-intrusion mechanism to low-density xerogels
Alié, Christelle ULg; Pirard, René ULg; Pirard, Jean-Paul ULg

in Journal of Non-Crystalline Solids (2001), 292(1-3), 138-149

Mineral materials can be either crushed or invaded by mercury during mercury porosimetry experiments. It has been shown here that many low-density xerogels exhibit the two volume variation mechanisms ... [more ▼]

Mineral materials can be either crushed or invaded by mercury during mercury porosimetry experiments. It has been shown here that many low-density xerogels exhibit the two volume variation mechanisms successively, compaction followed by intrusion. when submitted to mercury porosimetry and that a unimodal pore size distribution can be obtained by applying Pirard's collapse model below the pressure of transition P-1 and Washburn's intrusion theory above P-t. To confirm the validity of the use of the buckling law, one low-density xerogel was wrapped in a tight membrane (intrusion is prevented and the sample is crushed during the whole porosimetry experiment). The analysis of the mercury porosimetry data of the wrapped sample by the buckling law leads to a continuous unimodal distribution similar to the distribution of the unwrapped sample obtained by applying the buckling law below P-t and the intrusion law above P-t. The position of P-t is characteristic of the tested material: when submitted to mercury pressure. aerogels and low-density xerogels only collapse in case of very small aggregates whereas they are crushed and then intruded in case of larger silica aggregates. The fact that compacted slabs of monodisperse non-aggregated silica spheres (of the same size range as the xerogels and aerogels) show only intrusion during mercury porosimetry experiments implies that the particles need to be aggregated so that the compaction mechanism takes place. The position of the change of mechanism from crushing to intrusion is not directly related to the size of the elementary particles but is linked to the size of the aggregates of silica particles. (C) 2001 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMercury, polychlorobiphenyls and stable isotopes in the blood of harbour seals (Phoca vitulina) from the southern North Sea
Das, Krishna ULg; Lepoint, Gilles ULg; Fonfara, Sonja et al

Poster (2005)

The harbor seal (Phoca vitulina) is one of the most widely distributed seal species and the North Sea contains around 10 % of the world population. The harbour seal population in the North Sea was ... [more ▼]

The harbor seal (Phoca vitulina) is one of the most widely distributed seal species and the North Sea contains around 10 % of the world population. The harbour seal population in the North Sea was estimated at 36 000 individuals between 1994 and 1996). However, recurrent Phocine Distemper Virus (PDV) epizooties have affected the North Sea seal population. Recently, 21 500 harbor seals were killed by PDV in the North Sea and adjacent waters in 2002. Some intriguing questions about the interaction between PDV and immunotoxic contaminants, such as mercury (Hg) and polychlorinated biphenyls (PCBs) remain unanswered. In this framework, circulating levels of Hg and PCBs (PCBs 28, 52, 101, 118, 138, 153, 180) were measured in the blood of 24 harbour seals captured on a sandbank between 2001 and 2004 (Schleswig-Holstein, Germany). As pollutant level may be linked to the trophic position in the food web, carbon and nitrogen isotopic ratios (δ13C and δ15N) were measured in clotted blood cells. The average concentration of mercury in these living seals did not differ significantly from those observed previously in stranded harbour seals (94 ± 41 vs 146 ± 71 µg.l-1 respectively). Mean blood concentrations of total PCBs (∑PCBs) were 11 ng/ml. CB 153 clearly dominated the mix (45%) followed by PCB 138 (31%). The average isotopic composition measured in the blood cells was –15.6 ± 0.3 0/00 and 18.7 ± 0.6 0/00 for δ13C and δ15N respectively, similar to that obtained previously in muscle of stranded individuals, confirming the high position of the harbour seal in the North Sea trophic chain. Further investigations are obviously needed on a larger sampling but our preliminary results suggest that blood is an interesting substrate for both trophic and pollutant long-term monitoring of the harbour seal in the North Sea. [less ▲]

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See detailMere exposure effect : a consequence of direct and indirect fluency-preference links
Willems, Sylvie ULg; Van der Linden, Martial ULg

in Consciousness & Cognition (2006), 15(2), 323-341

In three experiments, picture quality between test items was manipulated to examine whether subjects' expectations about the fluency normally associated with these different stimuli might influence the ... [more ▼]

In three experiments, picture quality between test items was manipulated to examine whether subjects' expectations about the fluency normally associated with these different stimuli might influence the effects of fluency on preference or familiarity-basea recognition responses. The results showed that fluency due to pre-exposure influenced responses less when objects were presented with high picture quality, suggesting that attributions of fluency to preference and familiarity are adjusted according to expectations about the different test pictures. However, this expectations influence depended on subjects' awareness of these different quality levels. Indeed, imperceptible differences seemed not to induce expectations about the test item fluency. In this context, fluency due to both picture quality and pre-exposure influenced direct responses. Conversely, obvious, and noticed, differences in test picture quality did no affect responses, suggesting that expectations moderated attributions of fluency only when fluency normally associated with these different stimuli was perceptible but difficult to assess. (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailThe mere exposure effect without recognition can depend on the way you look!
Willems, Sylvie ULg; dedonder, jonathan; Van der Linden, Martial ULg

in Experimental Psychology (2010), 57(3), 185-192

In line with [Whittlesea, B. W. A., & Price, J. R. (2001). Implicit/Explicit memory versus analytic/nonanalytic processing: Rethinking the mere exposure effect. Memory and Cognition, 26, 547-565], we ... [more ▼]

In line with [Whittlesea, B. W. A., & Price, J. R. (2001). Implicit/Explicit memory versus analytic/nonanalytic processing: Rethinking the mere exposure effect. Memory and Cognition, 26, 547-565], we investigated whether the memory effect measured with an implicit memory paradigm (mere exposure effect) and an explicit recognition task depended on perceptual processing strategies, regardless of whether the task required intentional retrieval. We found that manipulation intended to prompt functional implicit-explicit dissociation no longer had a differential effect when we induced similar perceptual strategies in both tasks. Indeed, the results showed that prompting a nonanalytic strategy ensured performance above chance on both tasks. Conversely, inducing an analytic strategy drastically decreased both explicit and implicit performance. Furthermore, we noted that the nonanalytic strategy involved less extensive gaze scanning than the analytic strategy and that memory effects under this processing strategy were largely independent of gaze movement. [less ▲]

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See detailThe Mere Exposure Effects Depends on the Way You Look!
Willems, Sylvie ULg; Dedonder, Jonathan

Poster (2008, May)

Detailed reference viewed: 4 (2 ULg)
See detailLa mère Julie Billart
Kurth, Godefroid ULg

in Almanach belge illustré (1885)

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See detailMerging academic libraries: An opportunity for a face-lift?
Durieux, Nancy ULg; Vandenput, Sandrina ULg; Brouwir, Christine ULg et al

Conference (2008, June 26)

Although the decision to merge libraries generates stress, it is also a great opportunity to start a global reflection on the functioning of libraries. In 2003, the University of Liège decided to create a ... [more ▼]

Although the decision to merge libraries generates stress, it is also a great opportunity to start a global reflection on the functioning of libraries. In 2003, the University of Liège decided to create a new physical and functional structure by combining the previously independent libraries of Medicine, Veterinary Medicine, Botany, Zoology, Psychology and Educational Sciences. The initial phase included a plan to remove the collections and standardise the academic teaching of IT literacy in the various disciplines. We now want to question our missions and evaluate our present working procedures in order to optimise our services, eventually develop new ones, and make them visible through a new website or any other types of support. The different populations of users need to be clearly identified, evaluated and anticipated. Staff competences must be evaluated to guarantee that users' expectations are met, and possibly to envisage any new services that may need to be created. In addition, staff competences must be improved through adapted education and tailored professional training. At the same time, the library involvement in academic teaching deserves to be properly highlighted. We are aware that there is not anything new in such an approach, but the pieces of evidence are scattered, outdated or not adapted to our present situation. As a consequence, we propose an overview of the literature concerning the marketing of academic libraries, conducted according to the principles of Evidence-Based Library and Information Practice. We shall select the most important publications providing strong theoretical support, and we shall collect existing tools, evaluation grids and procedure rules that might be useful during any step of the project. We shall organise them into a structured and pragmatic working strategy that could be used by any library interested in a marketing approach. It should integrate the different topics previously mentioned such as the library’s missions, the evaluation and optimisation of services, as well as the visibility of the teaching activities and the professional education programmes developed by academic libraries. [less ▲]

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See detailMerging multi-camera data to reduce motion analysis instrumental errors using Kalman filters
Schwartz, Cédric ULg; Denoël, Vincent ULg; Forthomme, Bénédicte ULg et al

in Computer Methods in Biomechanics and Biomedical Engineering (2013)

In motion capture systems, markers are often seen by multiple cameras. All cameras do not measure the position of the markers with the same reliability because of environmental factors such as the ... [more ▼]

In motion capture systems, markers are often seen by multiple cameras. All cameras do not measure the position of the markers with the same reliability because of environmental factors such as the position of the marker in the field of view or the light intensity received by the cameras. Kalman filters offer a general framework to take the reliability of the various cameras into account and consequently improve the estimation of the marker position. The proposed process can be applied to both passive and active systems. Several reliability models of the cameras are compared for the Codamotion active system, which is considered as a specific illustration. The proposed method significantly reduces the noise in the signal, especially at long range distances. Therefore, it improves the confidence of the positions at the limits of the field of view. [less ▲]

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See detailMerging satellite and in situ sea surface temperature data using DINEOF
Alvera Azcarate, Aïda ULg; Barth, Alexander ULg; Beckers, Jean-Marie ULg

Conference (2011, April 05)

High quality sea surface temperature data sets are needed for various applications, including numerical weather prediction, ocean forecasting and climate research. The coverage, resolution and precision ... [more ▼]

High quality sea surface temperature data sets are needed for various applications, including numerical weather prediction, ocean forecasting and climate research. The coverage, resolution and precision of individual sea surface temperature observations is not sufficient for these applications, therefore merging of complementary data sets is needed to increase the coverage and to reduce the final data set error. DINEOF (Data Interpolating Empirical Orthogonal Functions) is an EOF-based technique to reconstruct missing information -due to clouds, for example in satellite data sets. A new development of this method consists in its capability to merge different data sources into one estimate. This development is tested using AVHRR data of the western Mediterranean Sea and in situ data from various international databases (World Ocean Database (WOD), MEDAR/Medatlas, Coriolis Data Center, International Council for the Exploration of the Sea (ICES) and International Comprehensive Ocean-Atmosphere Data Set (ICOADS)). An error assessment between the satellite and in situ data is performed first, in order to determine the error statistics between these two data sources. The error is calculated by database, platform type (CTD, XBT, drifters, bottles and ships) and depth. This error assessment is used to merge the in situ and satellite data. The impact of the sensor-specific errors on the quality of the final product will be assessed, and compared to the results obtained when the same error estimate is used for all sensors. The benefit of using in situ data in addition to satellite data will be also discussed. Additional information can be found at http://modb.oce.ulg.ac.be/mediawiki/index.php/DINEOF and http://gherdiva.phys.ulg.ac.be/DINEOF/ [less ▲]

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See detailMeridional reorganizations of marine and terrestrial productivity during Heinrich events,
Menviel, L.; Timmermann, A.; Mouchet, Anne ULg et al

in Paleoceanography (2008), 23

To study the response of the global carbon cycle to a weakening of the Atlantic Meridional Overturning Circulation (AMOC), a series of freshwater perturbation experiments is conducted both under ... [more ▼]

To study the response of the global carbon cycle to a weakening of the Atlantic Meridional Overturning Circulation (AMOC), a series of freshwater perturbation experiments is conducted both under preindustrial and glacial conditions using the earth system model of intermediate complexity LOVECLIM. A shutdown of the AMOC leads to substantial cooling of the North Atlantic, a weak warming of the Southern Hemisphere, intensification of the northeasterly trade winds, and a southward shift of the Intertropical Convergence Zone (ITCZ). Trade wind anomalies change upwelling in the tropical oceans and hence marine productivity. Furthermore, hydrological changes associated with a southward displacement of the ITCZ lead to a reduction of terrestrial carbon stocks mainly in northern Africa and northern South America in agreement with paleoproxy data. In the freshwater perturbation experiments the ocean acts as a sink of CO2, primarily through increased solubility. The net atmospheric CO2 anomaly induced by a shutdown of the AMOC amounts to about +15 ppmv and −10 ppmv for preindustrial and glacial conditions, respectively. This background state dependence can be explained by the fact that the glacial climate is drier and the terrestrial vegetation therefore releases a smaller amount of carbon to the atmosphere. This study demonstrates that the net CO2 response to large-scale ocean circulation changes has significant contributions both from the terrestrial and marine carbon cycle. [less ▲]

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See detailLe merisier : état de la ressource en Belgique
Claessens, Hugues ULg

in Boulet-Gercourt, Bruno (Ed.) Le Merisier (1997)

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See detailMerisier : les variétés multiclonales ont-elles un avenir ?
Curnel, Yanick; van de waele, Isabelle; Jacques, Dominique et al

in Silva Belgica (2001), 108(2), 32-37

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See detailMerits of the multivariate Dale model in genetic association studies
Van Steen, Kristel ULg; Molenberghs, G.; Tahri, N.

in Genetic Epidemiology (2002), 23

Detailed reference viewed: 8 (1 ULg)