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See detailAccurate Non-Iterative Modelling and Inference of Longitudinal Neuroimaging Data
Guillaume, Bryan ULg

Doctoral thesis (2015)

Despite the growing importance of longitudinal data in neuroimaging, the standard analysis methods make restrictive or unrealistic assumptions. For example, the widely used SPM software package assumes ... [more ▼]

Despite the growing importance of longitudinal data in neuroimaging, the standard analysis methods make restrictive or unrealistic assumptions. For example, the widely used SPM software package assumes spatially homogeneous longitudinal correlations while the FSL software package assumes Compound Symmetry, the state of all equal variances and equal correlations. While some new methods have been recently pro- posed to more accurately account for such data, these methods can be difficult to specify and are based on iterative algorithms that are generally slow and failure- prone. In this thesis, we propose and investigate the use of the Sandwich Estimator method which first estimates the parameters of interest with a (non-iterative) Ordinary Least Square model and, second, estimates variances/covariances with the “so-called” Sandwich Estimator (SwE) which accounts for the within-subject covariance structure existing in longitudinal data. We introduce the SwE method in its classic form, and review existing and propose new adjustments to improve its behaviour, specifically in small samples. We compare the SwE method to other popular methods, isolating the combination of SwE adjustments that provides valid and powerful inferences. While this result provides p-values at each voxel, it does not provide spatial inferences, e.g. voxel- or cluster-wise family-wise error-corrected p-values. For this, we investigate the use of the non-parametric inference approach called Wild Bootstrap. We again identify the set of procedures and adjustments that provide valid inferences. Finally, in the third and fourth projects, we investigate two ideas to improve the statistical power of the SwE method, by using a shrinkage estimator or a covariance spatial smoothing, respectively. For all the projects, in order to assess the methods, we use intensive Monte Carlo simulations in settings important for longitudinal neuroimaging studies and, for the first two projects, we also illustrate the methods by analysing a highly unbalanced longitudinal dataset obtained from the Alzheimer’s Disease Neuroimaging Initiative. [less ▲]

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See detailL'enseignement-apprentissage du néerlandais en Fédération Wallonie-Bruxelles: objectifs, méthodes, résultats
Rasier, Laurent ULg; Hiligsmann, Philippe

Conference (2015, September 30)

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See detailLa forma diagrammatica tra matematica e arti
Dondero, Maria Giulia ULg

in Rivista Italiana di Filosofia del Linguaggio (2015), numéro spécial

This paper aims to compare the theory of diagram presented in Peirce’s philosophy of mathematics and the reflections on the work of art formulated by Henry Van Lier and René Thom. The Peircean Theory of ... [more ▼]

This paper aims to compare the theory of diagram presented in Peirce’s philosophy of mathematics and the reflections on the work of art formulated by Henry Van Lier and René Thom. The Peircean Theory of diagram states that a diagram is a configuration characterized as a totality (form) that is necessary and at the same time dynamic and experimental. In his lectures about the relation between the local and the global in art (Apologie du logos, 1990), Thom traces a theory of forms that can be compared to the conception of diagram in Peirce’s semiotics. For Thom, beauty is the result of strategies of framing and of composing parts in a dynamic totality. Van Lier’s develops the idea of a perfect totality characterized by a syntax of traits that are at the right place and that couldn’t be organized in any other way, without which the work of art would have no efficacy. For my part, I explore these conceptions of a necessary totality in the arts (aesthetic necessity) and in mathematical diagrams (the demonstration through perceptual forms) in order to describe the differences and the similarities between the theories and the domains of application. [less ▲]

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See detailSuivre la main du scribe Amennakhte dans la documentation hiératique de la XXe dynastie
Dorn, Andreas; Polis, Stéphane ULg

Scientific conference (2015, September 30)

Le scribe Amennakhte, fils d’Ipuy, fut un personnage central de la communauté de Deir el-Médineh à la 20e dynastie : élevé au rang de Scribe de la Tombe en l’an 16 de Ramsès III, il occupa ce poste durant ... [more ▼]

Le scribe Amennakhte, fils d’Ipuy, fut un personnage central de la communauté de Deir el-Médineh à la 20e dynastie : élevé au rang de Scribe de la Tombe en l’an 16 de Ramsès III, il occupa ce poste durant plus de trente années, jusqu’à sa mort sous le règne de Ramsès VI. Fait exceptionnel, ce lettré ne nous est pas seulement connu comme rédacteur de textes documentaires afférents à la gestion de l’Institution de la Tombe, mais également comme auteur d’une série de textes relevant de la sphère littéraire au sens large, allant de l’enseignement à la satire en passant par des hymnes et eulogies. Après avoir brièvement présenté l’environnement dans lequel vivait Amennakhte — dont on pense connaître à la fois l’habitation dans le village, la tombe et une hutte qu’il occupa dans la Vallée des Rois — nous axerons notre présentation sur la dimension paléographique du personnage et présenterons les difficultés rencontrées lorsque l’on entend suivre la main du scribe dans la documentation hiératique de la 20e dynastie. Ce sera l’occasion d’un parcours diachronique entre une variété de supports (graffiti incisés, dipinti, ostraca et papyri) et de genres textuels, qui nous permettra d’observer les variations de formes et de ductus potentiellement attribuables à un même scribe. En nous appuyant essentiellement sur le matériel du Museum de Turin et de l’Institut Français d’Archéologie Oriental du Caire, cet exposé sera donc l’occasion de présenter les derniers progrès réalisés dans l’identification des mains de scribes de la communauté de Deir el-Médineh. [less ▲]

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See detailImplication of adamalysin proteases in mesothelioma
Sepult, Christelle ULg; Rocks, Natacha ULg; Bekaert, Sandrine et al

Conference (2015, September 30)

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See detailNumerical modeling of the cardiac mechano-electric feedback within a thermo-electro-mechanical framework. Study of its consequences on arrhythmogenesis.
Collet, Arnaud ULg

Doctoral thesis (2015)

This doctoral study characterizes, for simple geometries, the cardiac autonomous electrical activity induced by the mechanical deformations of the myocardium via the mechano-electric feedback within a ... [more ▼]

This doctoral study characterizes, for simple geometries, the cardiac autonomous electrical activity induced by the mechanical deformations of the myocardium via the mechano-electric feedback within a thermo-electro-mechanical framework. The underlying fundamental mechanisms are highlighted and discussed in detail. In a healthy heart, the mechano-electric feedback acts as a regulator able to damp mechanical perturbations undergone by the heart, by appropriately modulating electrical activity shortly after these perturbations. In this way, a new healthy electromechanical situation is recovered. However, under certain conditions, this feedback can be a generator of dramatic cardiac arrhythmias by inducing local electrical depolarizations resulting from abnormal cardiac muscle tissue deformations. These local perturbations can then propagate in the whole heart and, thus, lead to global cardiac dysfunctions. The one- and two-dimensional models developed in this work to study the arrhythmogenic consequences of the mechano-electric feedback within a thermo-electro-mechanical framework account for three couplings: the excitation-contraction coupling, the mechano-electric feedback, and the thermo-electric coupling. The excitation-contraction coupling allows the mechanical contraction of cardiac muscle cells resulting from the electrical excitation of these cells, triggered by a propagating action potential initially generated by the sino-atrial node in a healthy heart. The mechano-electric feedback takes into account the influence of mechanical deformations on the electrical activity, both at the cell and the macroscopic level. The thermo-electric coupling then modulates certain electrical properties due to a temperature change. The excitation-contraction coupling is modeled in a phenomenological way by combining the Aliev-Panfilov model and the Rogers-McCulloch model. The propagation of the electrical excitation through cardiac muscle tissue is modeled by using the monodomain approach. The mechano-electric feedback is taken into account by considering two different contributions, namely the physiological contribution (physiological feedback) and the geometric contribution (geometric feedback). The physiological feedback consists in the onset of stretch-activated currents due to the deformations of the cardiac muscle tissue via specific mechanosensitive channels. Regarding the geometric feedback, it simply reflects that the propagation of the depolarization waves is altered by the deformations of the geometry. The thermo-electric coupling is modeled via a dependence with respect to the temperature which is exponential for the gating kinetics of ion channels, exponential for the kinetics of the active tension development in cardiomyocytes, and linear for the ionic conductances. This study shows that the mechano-electric feedback can be arrhythmogenic under specific conditions. In particular, this work clearly reveals that the size of the domain and the importance of stretch-activated currents are key factors in the behavior of the autonomous electrical activity induced by the mechano-electric feedback. This doctoral study also shows that temperature variations such as those undergone by the heart during therapeutic hypothermia or hyperthermia play a central role in the cardiac electromechanical behavior. Moreover, this work emphasizes the influence of the initial conditions on the electromechanical behavior of cardiac tissue. In the one-dimensional framework, an important result of this work is that the disappearance of the autonomous electrical activity induced by the deformations of the cardiac muscle can be associated with different types of bifurcation phenomena, depending on the values of the parameters. These bifurcations, which correspond in fact to different ways for the AEA to vanish, are emphasized and discussed in detail. [less ▲]

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See detailEtude d’un concentrateur solaire basé sur une combinaison optique diffractive/réfractive pour applications spatiales
Michel, Céline ULg

Doctoral thesis (2015)

Continued demand for new applications from spacecrafts leads to larger power needs. For most of them, the primary energy sources are solar panels. However, these solar panels are heavy and expensive ... [more ▼]

Continued demand for new applications from spacecrafts leads to larger power needs. For most of them, the primary energy sources are solar panels. However, these solar panels are heavy and expensive, mainly due to solar cells and their coverglass. The power need increase requires thus new concepts of solar panels. Furthermore, space environment is highly constraining: the vacuum limits heat trans- fer since convection is not allowed, there is contamination modifying the light spectrum reaching cells, ultraviolet light induces a yellowing of silicone glue, radiations degrade pho- tovoltaic cells, etc. Usually, multi-junctions (MJ) cells are used, that are strongly sensitive to spectral modification in their incident spectrum due to their series connected structure (the worst cell defines the whole output performance). The power dimensioning of solar panels is then based on end of life (EOL) PV cells expected performance. Reducing the sensitivity to increase EOL output power is then another challenge for space applications. This thesis aims to answer to both problems, by the proposition and study of a new lightweight solar concentrator with spectral splitting. This conceptual concentrator is composed of a Fresnel lens for sunlight concentration, coupled to a surface relief diffraction grating to spectrally split incident light, forming a single optical element in silicone. The concentration behavior allows a reduction of solar cells area (including its coverglass), replaced by a lightweight silicone lens, reducing the global cost and mass. The lateral spectral separation will permit other types of cells than the usual MJ cells. To demonstrate the concept, two single junctions (SJ) solar cells are placed side by side, the first collecting visible light, the second collecting near IR light. Since cells are electrically independent, sensitivity is lower and EOL output power can surpass standard MJ cells systems. Moreover, cells combination is nearly free: all photovoltaic technology can be used and combined, opening the solar concentration field to other technologies than MJ. This work studies and evaluates the pros and cons of diffraction grating/Fresnel lens combinations as solar concentrator with spectral splitting. The analysis includes the choice of material, optical developments and optimizations (grating selection, freeform lenses, grating period optimization along the lens, etc.), electrical modeling and methods to find the best cells combination as well as the modeling of expected output power, a thermal simulation, weight and deployment considerations, and approaches of sensitivity with spectral modifications. Some experimental results complete the study. Two main configurations were developed: a first with a blazed grating, and a second with a symmetrical lamellar grating. Both configurations, after optimization, show similar performances: a global geometrical concentration ratio around 5-6× (ratio between lens width and the total width of the two cells), a tracking error tolerance up to 0.7◦, no drastic degradation with respect to deformations, fabrication errors, etc., an output power at begin of life (BOL) better than a classical concentrator focusing on a SJ cell or a planar solar panel composed of SJ cells. Both configurations present also a BOL specific mass [kg/W] lower than a classical planar solar panel covered by MJ cells, and a lower sensitivity to space environment, with theoretical larger EOL output power depending on chosen PV cells combinations. Existing deployment systems are proposed and discussed. Also, an experimental prototype of the optical element was realized, with optical results close to simulations. Some adaptations to terrestrial concentrators, other spectra, or using more than 2 different SJ cells are also introduced, highlighting the versatility of our concept. Results demonstrate thus the coherence of the concept, leading to experimentally feasible and quite tolerant concentrator, with interesting cost reduction thanks to concentration and specific weight reduction. However, optical losses due to the non-perfect spectral splitting of the grating is too high to be able to surpass MJ cells systems BOL up to now, and the lower sensitivity of our concentrator cannot completely compensate this lack of performance at EOL. To reach better performances than MJ systems, from cost, mass, radiation resistance, etc. point of view and to exploit the obvious gain in sensitivity, the concentrator needs thus further investigations mainly related to cells combinations. Especially as our concept opens a lot of opportunities thanks to the complete independence of cells: other technologies are allowed, specific coatings can improve performances, ... Applications for Earth or places with different/changing incident spectra is another plausible perspective. Our concentrator with spectral splitting can also be a major advantage for specific scientific space missions like deep space missions. [less ▲]

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See detailWIND-STORM: A Decision Support System for the Strategic Management of Windthrow Crises by the Forest Community
Riguelle, Simon ULg; Hebert, Jacques ULg; Jourez, Benoît ULg

in Forests (2015), 6

Storms are one of the most damaging agents for European forests and can cause huge and long-term economic impacts on the forest sector. Recent events and research have contributed to a better ... [more ▼]

Storms are one of the most damaging agents for European forests and can cause huge and long-term economic impacts on the forest sector. Recent events and research have contributed to a better understanding and management of destructive storms, but public authorities still lack appropriate decision-support tools for evaluating their strategic decisions in the aftermath of a storm. This paper presents a decision support system (DSS) that compares changes in the dynamics of the regional forest-based sector after storm events under various crisis management options. First, the development and implementation of a regional forest model is addressed; then, the potential application of the model-based DSS WIND-STORM is illustrated. The results of simulated scenarios reveal that this DSS type is useful for designing a cost-effective regional strategy for storm-damage management in the context of scarce public resources and that public strategies must encompass the whole forest-based sector to be efficient. Additional benefits of such a DSS is to bring together decision-makers and forest stakeholders for a common objective and therefore to enhance participatory approaches to crisis management. [less ▲]

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See detailDynamics of the active region in Jupiter’s aurorae
Bonfond, Bertrand ULg; Grodent, Denis ULg; Badman, Sarah et al

Conference (2015, September 29)

The Far-UV aurorae at Jupiter variety on a wide range of timescales. This study focuses on the dynamics of the active region on timescales of a few minutes. Up to now, only the time-tag mode of the Space ... [more ▼]

The Far-UV aurorae at Jupiter variety on a wide range of timescales. This study focuses on the dynamics of the active region on timescales of a few minutes. Up to now, only the time-tag mode of the Space Telescope Imaging Spectrograph provides access to such fast variations with a high spatial resolution. This active region, located on the dusk flank of the area inside the main auroral oval, is the locus of particularly bright (up to several mega Reyleighs) and sudden (a few tens of seconds) enhancements called flares. A previous study also showed that these flare could reoccur quasi-periodically every 2-3 minutes and propagate from dusk to dawn. Here we use data obtained in 2013 and 2014 to show that this quasi-periodic behavior is only present on half of the cases and that the affected region could either cover the whole active region or a much smaller area (∼5000km^2). We also found areas that were still during part of the observation sequence and then began to blink (see Figure 1). We also show that there no systematically preferred propagation direction. Finally, sequences acquired successively in the two hemispheres show that the quasi-periodic flares can be in phase [less ▲]

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See detailLes mains de l'Enseignement d'Amennakhte. Reconnecter le littéraire au documentaire
Polis, Stéphane ULg

Scientific conference (2015, September 29)

Dans cet exposé, je décris la redécouverte par les égyptologues de l'Enseignement d'Amennakhte en accordant une attention particulière aux mains hiératiques des scribes qui ont rédigé les témoins connus ... [more ▼]

Dans cet exposé, je décris la redécouverte par les égyptologues de l'Enseignement d'Amennakhte en accordant une attention particulière aux mains hiératiques des scribes qui ont rédigé les témoins connus de ce texte majeur de la 20e dynastie. Cette approche permet d'aboutir à trois conclusions principales. (1) Il n'est pas possible de montrer l'existence d'une véritable "école de mains" qui imiteraient celle du scribe de la Tombe Amennakhte (e.g. Eyre 1979 : 87). (2) Il est possible d'attribuer différents témoins du texte de l'Enseignement à une même main. (3) On peut établir le lien ferme entre des mains ayant copiés l'Enseignement d'Amennakhte et des mains documentaires connues de la première moitié de la 20e dynastie. Ce dernier point permet de revenir sur le mythe égyptologique d'une césure significative entre mains littéraires et mains documentaires : malgré certaines différences, la possibilité de suivre la main d'un scribe entre textes littéraires et documentaires est réelle. Cela n'est évidemment pas sans conséquences pour l'histoire culturelle de la Communauté de Deir el-Médineh. [less ▲]

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See detailStatistical analysis and multi-instrument overview of the quasi-periodic 1-hour pulsations in the Saturn's outer magnetosphere
Palmaerts, Benjamin ULg; Roussos, Elias; Krupp, Norbert et al

Poster (2015, September 29)

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See detailHull Optimization of Medium-Speed Monohull Passenger Ferries
Hetharia, Wolter Roberth ULg

Doctoral thesis (2015)

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See detailLes sols, richesses cachées de la planète
Garré, Sarah ULg; Carnol, Monique ULg; Cornelis, Jean-Thomas ULg

Speech/Talk (2015)

Toute forme de vie sur terre doit beaucoup aux sols. Aussi discrets que dynamiques, vitaux que complexes, les sols sont des réacteurs bio-physico-chimiques, situés à l’interface entre les roches, la ... [more ▼]

Toute forme de vie sur terre doit beaucoup aux sols. Aussi discrets que dynamiques, vitaux que complexes, les sols sont des réacteurs bio-physico-chimiques, situés à l’interface entre les roches, la végétation, l’air et l’eau. L’étude de cette ressource non renouvelable, soumise à des pressions croissantes, requiert une approche interdisciplinaire, indispensable pour une gestion raisonnée et durable des écosystèmes. Comment sont définis les sols, comment les étudions-nous, comment aborder leur diversité et leurs fonctionnalités ? Quels secrets ont-ils à nous livrer ? La leçon inaugurale abordera la formation des sols, leur diversité ainsi que leurs fonctions écologiques. La variété des organismes au sein des sols et la notion de qualité des sols seront évoquées à travers la triangulation biodiversité – fonctions – services écosystémiques. Des techniques innovantes, permettant d’étudier cette interface extrêmement complexe et diversifiée, seront présentées et le fonctionnement ainsi que l’intérêt des sols seront illustrés par des exemples concrets issus de recherches récentes. [less ▲]

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See detailExperimental and in silico approaches to study the interaction of Remorin with plant plasma membrane : specific interaction of the C-term domain with lipids
Deleu, Magali ULg; Nasir, Mehmet Nail ULg; Gronnier, Julien et al

Conference (2015, September 29)

The function of Remorins, a diverse family of plant-specific proteins (1) is far to be fully elucidated. One of them, StREM1.3 (for Solanum tuberosum Remorin from group 1, homolog 3) has been reported to ... [more ▼]

The function of Remorins, a diverse family of plant-specific proteins (1) is far to be fully elucidated. One of them, StREM1.3 (for Solanum tuberosum Remorin from group 1, homolog 3) has been reported to regulate cell-to-cell propagation of the potato virus X (2). It was also shown to be localized to the inner leaflet of plasma membranes (PMs) and along plasmodesmata, bridges connecting neighbor cells essential for cell-to-cell communication in plants (3). The mechanisms driving StREM1.3 association with PM is still an open question. It was shown recently that a domain of 28 residues at the C-terminus of the potato (RemCA) is required and sufficient for anchoring to the PM (4). Here we combined experimental and in silico biophysics to unravel the molecular bases of RemCA membrane binding. Biomimetic membrane models of plant PM such as monolayers and liposomes were used with various biophysical techniques (Langmuir monolayer technique, Fourier-transformed infrared spectroscopy, circular dichroïsm) and modeling tools (home-made methods and molecular dynamics) (5) to answer to three questions: (i) What is the conformation adopted by RemCA within a membrane?, (ii) Is there any membrane lipid specificity in the RemCA-membrane binding? (iii) What is the role of the two different RemCA domains in the interaction? Results show that RemCA displays a preference for plant phosphoinositide and sitosterol-enriched inner leaflet plasma membrane rafts. Within the membrane, the C-terminal and the N-terminal domains adopt a random coil and a -helical conformation respectively. The C-terminal domain acts as a driver to bind RemCA to the membrane while the N-terminal domain stabilizes the peptide at the membrane. Lysine residues have a crucial importance in this interaction. References (1) Raffaele et al., Plant Physiol., 2007, 145: 593–600 (2) Raffaela et al., Plant Cell, 2009, 21: 1541–1555. (3) Maule, Curr. Opin. Plant Biol., 2008, 11: 680–686. (4) Perraki et al., Plant Physiology, 2012, 160 : 624-637. (5) Deleu et al., Biochim. Biophys. Acta – Biomembranes, 2014, 1838 : 3171-3190. [less ▲]

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See detailHyporeactivity of Alveolar Macrophages and Higher Respiratory Cell Permissivity Characterize DBA/2J Mice Infected by Influenza A Virus Hyporeactivity of Alveolar Macrophages and Higher Respiratory Cell Permissivity Characterize DBA/2J Mice Infected by Influenza A Virus.
Casanova Bustos, Tomas Ronaldo ULg; Van de Paar, Els; Desmecht, Daniel ULg et al

in JOURNAL OF INTERFERON & CYTOKINE RESEARCH (2015), 35(10), 808-820

Influenza A virus remains a major public health problem. Mouse models have been widely used to study influenza infection in mammals. DBA/2J and C57BL/6J represent extremes in terms of susceptibility to ... [more ▼]

Influenza A virus remains a major public health problem. Mouse models have been widely used to study influenza infection in mammals. DBA/2J and C57BL/6J represent extremes in terms of susceptibility to influenza A infection among inbred laboratory mouse strains. Several studies focused specifically on the factors responsible for the susceptibility of DBA/2J or the resistance of C57BL/6J and resulted in impressive lists of candidate genes or factors over- or underexpressed in one of the strains. We adopted a different phenotypical approach to identify the critical steps of the infection process accounting for the differences between DBA/2J and C57BL/6J strains. We concluded that both a dysfunction of alveolar macrophages and an increased permissivity of respiratory cells rendered DBA/2J more susceptible to influenza infection. [less ▲]

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See detailTrace metal speciation? An essential aspect of biomonitoring to avoid wrong conclusions
Richir, Jonathan ULg; Lepoint, Gilles ULg; Donnay, Annick et al

Poster (2015, September 29)

The Mediterranean mussel Mytilus galloprovincialis is widely used as a bioindicator species in active monitoring surveys. As a filter feeder artificially maintained in the water column, it bioaccumulates ... [more ▼]

The Mediterranean mussel Mytilus galloprovincialis is widely used as a bioindicator species in active monitoring surveys. As a filter feeder artificially maintained in the water column, it bioaccumulates trace metals from the surrounding water in their dissolved and particulate forms. However, most monitoring surveys don’t take into account that speciation aspect when studying trace metal accumulation kinetics in mussels. In the framework of the STARECAPMED project, we monitored trace metal concentrations in the flesh of mussels together with their “most bioavailable” dissolved and particulate fractions in the water column for almost 5 months (February-June 2011). Mussels were purchased from 2 little contaminated French shellfish farms (SARL Etang de Diane and ferme marine des Aresquiers), placed in several pouches to allow regular sampling, and immerged near the Oceanographic Research Station STARESO in the Calvi bay, northwestern Corsica. Mussels and water samples for suspended matter filtration were collected every week to two weeks, as were deployed DGTs. Seawater samples were filtered through 47 mm hydrophilic PTFE membrane filters with a 0.45 µm pore size until clogging. In the laboratory, mussel flesh and filters were digested in Teflon vessels with acids (HNO3/H202) in a closed microwave digestion lab station. DGT resins were eluted for 24h in 1.0 M HNO3. Trace metal concentrations (Cr, Mn, Co, Ni, Cu, Zn, Ag, Cd, Pb) were measured by DRC-ICP-MS. Analytical accuracy was checked by analyzing CRMs. All the studied metals except Pb and Zn were present in the water column to over 80% in their dissolved form. The contribution of the dissolved pathway was thus likely to be predominant in the oligotrophic Calvi bay. Dissolved trace metals showed little temporal variability of their levels, likely resulting from the integration over time of their levels in the DGT probes and the lack of seasonality of this fraction. In contrast, Zn showed great variability of its particulate fraction during the survey. Such temporal variability was also observed for Cr, more abundant in its particulate form at the end of the survey, and for Mn and Pb that conversely tended to decrease. The dynamic of trace metals in the mussel flesh is regulated by the environmental bioavailability of dissolved and particulate metals, the ecophysiological status of mussels and the trophic conditions of the water body. In the oligotrophic Calvi bay, showing background contamination levels by metals, the trophic conditions played a major role once out of the spring plankton bloom. It led to the increase of metal concentrations measured in the flesh of mussels undergoing starvation. However, some metals such as Cu and Co displayed only little temporal variations of their concentrations, these essential micronutrients being well regulated. The combined study of trace metal bioavailability and mussel ecophysiology in defined environmental conditions allows discriminating against biotic and abiotic factors regulating contaminant uptake in mussels, thus avoiding wrong conclusions about the observed dynamics of the studied contaminants. Mussels are a good proxy of coastal water quality, but their proper use notably requires adjustment of raw contaminant concentrations with trophic status of monitored sites. [less ▲]

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See detailBetter tests better care : Syndrome-based diagnostics for respiratory tract infections
MELIN, Pierrette ULg

Conference (2015, September 29)

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