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See detailObjets réels et objets idéaux. Sur les objets d’ordre supérieur II
Zincq, Aurélien ULg

Conference (2014, September 23)

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See detailVers une vision plus positive de la maladie d'Alzheimer: Enjeux cliniques et éthique
Adam, Stéphane ULg

Conference given outside the academic context (2014)

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See detailBilan de carbone d'une prairie pâturée en Région wallonne: effets du climat et de la gestion du pâturage
Jerome, Elisabeth ULg

Doctoral thesis (2014)

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – ... [more ▼]

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – CH4), this PhD investigates the C balance of an intensively managed grazed grassland in the temperate climate of southern Belgium. It analyses more particularly impact of climatic conditions and management practices on the C balance. The research site is a permanent grassland, covering 4.22 ha, intensively used for more than 50 years for Belgian Blue cattle grazing with the application of organic and inorganic fertilizers. Management practices but also climatic conditions are representative of livestock production systems developed in southern Belgium. Over a three years study period, soil C stock variations are determined indirectly by measuring the balance of C fluxes at the system boundaries. This approach not only takes into account CO2 and CH4 exchanged with the atmosphere but also organic C imports (manures, complementary feedings), exports (harvests, animal products) and C lost through leaching. CO2 fluxes are measured by eddy covariance while other C fluxes are estimated from data provided directly by the farmer, from punctual measurements and from aboveground herbage mass measurements. Considering only assimilation and respiration, the ecosystem behaves, on average, as a weak CO2 source, although the interannual variability is large. Interannual variability seems not to be significantly correlated with the main environmental drivers but rather influenced by fertilization management. Taking other C fluxes into account, the site appears as being at equilibrium. Management (organic fertilization), as well as climatic conditions that dictated them (complementary feeds), are the principal factors influencing the C balance. Finally, results show that management practices were the key control of the C flux variability at this grassland. Grazing impact on CO2 fluxes appears not explicitly at the seasonal and annual scale. It is therefore quantified by developing innovative eddy covariance data analyses and experiments. For that, indirect and direct grazing impacts are separated. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle modifying CO2 exchanges. To quantify it, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalised dark respiration (Rd,10) is analysed. On average, GPPmax decreases during grazing periods and increases during non-grazing periods. This could respectively be explained by aboveground biomass reduction and re-growth. In addition, GPPmax variations are negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 is found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. Direct impact results from livestock CO2 emissions through respiration that adds to the total ecosystem respiration. It is emphasized through specific designed livestock confinement experiments. Net CO2 exchange is compared on successive days with similar climatic conditions, livestock being confined (≈ 26 livestock units ha-1), or not, in the main wind direction area of the eddy covariance set-up. Results obtained are corroborated by independent estimates based on the C ingested by cattle during confinement. Finally, the C balance analysis of this particular grazed grassland in southern Belgium reveals that, taking into account the climatic conditions observed and the management practices developed over the three study years, the site is C neutral. This means that GHG emissions linked to fertilization (N2O) and grazing (CH4) are not partly mitigated by soil C sequestration. However, we conclude that, management practices being the main factor controlling the C balance, strategies to enhance soil C sequestration exist. If those kinds of management practices are studied, a global approach, taking into consideration both the C fluxes and other GHG fluxes, would be required to see if they do not induce supplementary N2O and CH4 emissions. [less ▲]

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See detailComplexions et relations. Sur les objets d’ordre supérieur I
Zincq, Aurélien ULg

Conference (2014, September 22)

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See detailThermo-responsive gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) core–corona nanoparticles as a drug delivery system
Liu, Ji ULg; Detrembleur, Christophe ULg; Hurtgen, Marie et al

in Polymer Chemistry (2014), 5(18), 5289-5299

Core–corona gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) nanoparticles (gold@PVOH-b-PNVCL NPs) were fabricated via an in situ method, where a gold salt was reduced within the macromolecular aqueous ... [more ▼]

Core–corona gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) nanoparticles (gold@PVOH-b-PNVCL NPs) were fabricated via an in situ method, where a gold salt was reduced within the macromolecular aqueous solution. Arrangement of macromolecular chains on the surface of gold cores was studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy and infrared spectroscopy. The responsiveness to temperature and the preserved colloidal stability of the gold@PVOH-b-PNVCL NPs above the lower critical solution temperature (LCST) were confirmed by dynamic light scattering and turbidity measurements. The drug loading capacity (DLC of ca. 1.3–2.8 wt%) of the gold@PVOH-b-PNVCL NPs as a drug delivery system (DDS) was tested with Nadolol®, a hydrophilic drug, and the release behaviours were studied at several temperatures. PVOH-b-PNVCL copolymers with an LCST of a few degrees above the biological temperature (37 °C), for example, PVOH180-b-PNVCL110 (LCST of 41 °C), are preferential, due to the slower release at 37 °C, but a faster release at temperatures that are a few degrees higher. The cytocompatibility of the gold@PVOH-b-PNVCL NPs against mouse fibroblastic L929 cells was evaluated via the MTS assay. Cellular uptake within MEL-5 human melanoma cells was studied by confocal laser scanning microscopy, fluorescence-activated cell sorting and TEM techniques and it showed that gold@PVOH-b-PNVCL NPs preferably accumulated within the cellular cytoplasm, with an incubation concentration and period-dependent uptake process. All these results corroborated a general utility of these thermo-responsive gold@PVOH-b-PNVCL NPs for drug delivery and controlled drug release. [less ▲]

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See detailBlock, random and palm-tree amphiphilic fluorinated copolymers: controlled synthesis, surface activity and use as dispersion polymerization stabilizers
Alaimo, David ULg; Beigbeder, Alexandre; Dubois, Philippe et al

in Polymer Chemistry (2014), 5(18), 5273-5282

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See detailDes activités pour les patients souffrant de la maladie d'Alzheimer? Oui! Mais pas n'importe lesquelles!
Adam, Stéphane ULg

Conference given outside the academic context (2014)

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See detailHuman cortical excitability depends on time spent awake and circadian phase
Ly, Julien ULg; Chellappa, Sarah Laxhmi ULg; Gaggioni, Giulia ULg et al

Conference (2014, September 17)

At any point in time, human performance results from the interaction of two main factors: a circadian signal varying with the time of the day and the sleep need accrued throughout the preceding waking ... [more ▼]

At any point in time, human performance results from the interaction of two main factors: a circadian signal varying with the time of the day and the sleep need accrued throughout the preceding waking period. But what’s happen at the cortical cerebral level? We used a novel technique coupling transcranial magnetic stimulation with electroencephalography (TMS/EEG) to assess the influence of time spent awake and circadian phasis on human cortical excitability. Twenty-two healthy young men underwent 8 TMS/EEG sessions during a 28 hour sleep deprivation protocole. We found that cortical excitability depends on both time spent awake and circadian phasis. [less ▲]

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See detailLes effets de la retraite sur la mémoire
Adam, Stéphane ULg

Conference (2014, September 16)

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See detailDevelopping a physically based groundwater vulnerability concept in a DPSIR framework
Beaujean, Jean ULg; Brouyère, Serge ULg; Lemieux, Jean-Michel et al

Conference (2014, September 15)

A general physically based method is presented to assess vulnerability of groundwater to external pressures with respect to quality and/or quantity issues. In the vulnerability assessments, many ... [more ▼]

A general physically based method is presented to assess vulnerability of groundwater to external pressures with respect to quality and/or quantity issues. In the vulnerability assessments, many scientific authors agree nowadays that ‘physically based’ methods must be preferred to traditional approaches based on empirical overlay and index methods where physical attributes are often mixed with implicitly embedded conventional priorities. Results from one or another of these last methods can consequently be very dissimilar for a given case study and decision makers are losing confidence in these tools. A methodology is proposed to reframe the groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The DPSIR framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as water, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The concept of groundwater vulnerability assessment considered here is based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘falling below a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis will be given to the illustration of the general methodology on a simple case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold. The framework is general and, when applied to water, can include states that are not limited to quality such as, for example, water quantity and availability. [less ▲]

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See detailInvestigating apical adverse effects of four endocrine active substances in the freshwater gastropod Lymnaea stagnalis
Giusti, Arnaud ULg; Lagadic, Laurent; Barsi, Alpar et al

in Science of the Total Environment (2014), 493

The hermaphroditic gastropod Lymnaea stagnalis is proposed as a candidate species for the development of OECD guidelines for testing of the reprotoxicity of chemicals, including endocrine active ... [more ▼]

The hermaphroditic gastropod Lymnaea stagnalis is proposed as a candidate species for the development of OECD guidelines for testing of the reprotoxicity of chemicals, including endocrine active substances (EASs). Up to now, only a few putative EASs have been tested for their reproductive toxicity in this species. In this study, we investigate the effects of four EASs with different affinities to the vertebrate estrogen and androgen receptors (chlordecone as an estrogen; cyproterone acetate, fenitrothion and vinclozolin as anti-androgens) on the reproduction of L. stagnalis in a 21-day semi-static test. Testosterone and 17α-ethinylestradiol (EE2) were used as the reference compounds. The tested EASs had no significant effect on growth and survival at the tested concentration ranges (ng to μg/L). Classical reproduction endpoints (i.e., oviposition and fecundity) were not responsive to the tested chemicals, except for chlordecone and 17α-ethinylestradiol, which hampered reproduction from 19.6 μg/L and 17.6 μg/L, respectively. The frequency of polyembryonic eggs, used as an additional endpoint, demonstrated the effects of all compounds except EE2. The molecular pathways, which are involved in such reproduction impairments, remain unknown. Our results suggest that egg quality is a more sensitive endpoint as compared to other reproductive endpoints commonly assessed in mollusk toxicity tests. [less ▲]

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See detailInteractions discursives et graphiques en conception architecturale à distance
Joachim, Guillaume ULg

in Leclercq, Pierre (Ed.) Communication multimodale et collaboration instrumentée. Regards croisés sur Énonciations, Représentations, Modalités (2014, September 15)

Cet article présente une analyse qualitative de la conception architecturale à distance outillée par un dispositif de communication multimodale synchrone. À partir d’une transcription et d’un codage de ... [more ▼]

Cet article présente une analyse qualitative de la conception architecturale à distance outillée par un dispositif de communication multimodale synchrone. À partir d’une transcription et d’un codage de vidéos d’architectes qui collaborent en dessinant et discourant simultanément, nous étudions comment ces professionnels utilisent différentes ressources graphiques et verbales pour élaborer collectivement des connaissances. [less ▲]

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See detailLes Mooc : étude énonciative d’une pédagogie multimodale
Dondero, Maria Giulia ULg; Eléni, Mouratidou

in Leclercq, Pierre (Ed.) Communication multimodale et collaboration instrumentée. Regards croisés sur Énonciations, Représentations, Modalités (2014, September 15)

Cette contribution interroge les pratiques de pédagogie multimodale instrumentée des Massive Open Online Courses au travers d’une étude énonciative. Partant du principe que la communication multimodale ... [more ▼]

Cette contribution interroge les pratiques de pédagogie multimodale instrumentée des Massive Open Online Courses au travers d’une étude énonciative. Partant du principe que la communication multimodale instrumentée utilise différentes médiations sémiotiques (vidéo, peinture, dessin à la main, graphique, schéma, sonorité, musique etc.) nous nous proposons d’observer et d’analyser ces types de modalités communicationnelles telles que mises en place par les mooc. Ce, dans l’objectif de saisir la variété des pratiques multimodales auxquelles recourent les Massive Open Online Courses. Nous tentons également de souligner ce qui définit la spécificité de ces pratiques et la manière dont l’étude sémiotique des stratégies énonciatives peut-elle contribuer aux questionnements actuels en sciences de la communication. Nous répondons à ces questions à travers l’analyse de deux mooc issus de deux plateformes différentes : The Future of Storytelling de la plateforme Iversity et Scientific Humanities de la plateforme France Université Numérique. [less ▲]

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See detailAppropriation et gestion d’une activité collaborative distante. Le cas d’un atelier pédagogique de la conception architecturale
Dondero, Maria Giulia ULg; Shirkhodaei, Shima ULg

in Leclercq, Pierre (Ed.) Communication multimodale et collaboration instrumentée. Regards croisés sur Énonciations, Représentations, Modalités (2014, September 15)

Cette étude porte sur l’utilisation du dispositif SDC (Studio Digital Collaboratif) dans un projet collaboratif pédagogique de conception architecturale. Dans une perspective sémiotique, nous étudions le ... [more ▼]

Cette étude porte sur l’utilisation du dispositif SDC (Studio Digital Collaboratif) dans un projet collaboratif pédagogique de conception architecturale. Dans une perspective sémiotique, nous étudions le fonctionnement de la communication médiatisée dans les ateliers de formation par projet. Dans ces ateliers, les encadrants suivent l’avancement du projet de la conception architecturale des étudiants à travers les séances hebdomadaires de correction des documents. Ainsi, nous nous focalisons sur le rôle de l’opérateur — ici une des équipes collaboratrices — en adoptant le point de vue de la sémiotique des pratiques (J. Fontanille, Pratiques sémiotiques, Paris, PUF, 2008). Une perturbation dans l’activité collaborative des étudiants pendant l’atelier est au centre de notre propos et nous permettra de problématiser la question de l’appropriation, de la désappropriation et de la réappropriation de la pratique distante et simultanée. Cette perturbation nous permettra également de valoriser le rôle de l’opérateur dans la gestion d’une activité collaborative outillée en cours d’accomplissement. [less ▲]

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See detailIntegrated modelling and uncertainty analysis for assessment of climate change effects on groundwater resource
Goderniaux, Pascal; Wildemeersch, Samuel ULg; Dassargues, Alain ULg

Conference (2014, September 15)

Climate change will bring new pressure on surface and groundwater resources (e.g. Allen et al., 2004; Goderniaux et al., 2009; Van Roosmalen et al., 2009) in many parts of the world. Additional work is ... [more ▼]

Climate change will bring new pressure on surface and groundwater resources (e.g. Allen et al., 2004; Goderniaux et al., 2009; Van Roosmalen et al., 2009) in many parts of the world. Additional work is required to help water managers to plan for future changes. For example, most of studies provide projections for a stationary climate representative of the end of the century, although information is demanded for the near-future. A sophisticated transient weather generator (WG) in combination with an integrated surface-subsurface hydrological model (HydroGeoSphere) are used for producing a stochastic generation of large numbers of equiprobable climatic time series, representing transient climate change, and assess impacts on groundwater resources in a probabilistic way. This new methodology is applied for the unconfined chalky aquifer of Hesbaye (Geer basin in Belgium). The following uncertainty sources are studied : (1) the uncertainty linked to the calibration of the hydrological model, using 'UCODE_2005' (Poeter et al., 2005); (2) the uncertainty linked to the global and regional climatic models (GCMs and RCMs), by using a multi-model ensemble; (3) the uncertainty linked to the natural variability of the weather, by using stochastic climate change scenarios. 30 equiprobable climate change scenarios from 2010 to 2085 have been generated for each of 6 different RCMs. Results show that although the 95% confidence intervals calculated around projected groundwater levels remain large, the climate change signal becomes stronger than that of natural climate variability by 2085. Additionally, the WG ability to simulate transient climate change enabled the assessment of the likely timescale and associated uncertainty of a specific impact. This methodology constitutes a real improvement in the field of groundwater projections under climate change conditions as it enables water managers to analyse risks and take decisions with full knowledge of projected impact and their degree of confidence. [less ▲]

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See detailSleep homeostasis and the circadian timing system set the dynamics and excitability of neuronal ensembles
Vandewalle, Gilles ULg

in Journal of Sleep Research (2014, September 14), Suppl

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See detailBiologie de la reproduction et analyse du déterminisme et de la différenciation du sexe à des stades précoces chez le tilapia du Nil, Oreochromis niloticus
Gennotte, Vincent ULg

Doctoral thesis (2014)

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental ... [more ▼]

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental), ainsi que par une plasticité du contrôle génétique et endocrinien de la différenciation sexuelle incomparables parmi les autres vertébrés. Le tilapia du Nil (Oreochromis niloticus) est un cichlidé gonochorique possédant un système chromosomique de déterminisme sexuel à homogamétie femelle XX/XY, complété par un déterminisme environnemental, les hautes températures pouvant modifier le développement phénotypique du sexe. L’intérêt porté à cette espèce en aquaculture à conduit au développement de différentes techniques de contrôle du sexe (par traitement hormonal) permettant la production de poissons présentant différentes combinaisons de phénotype/génotype sexuels (mâles XX, XY, YY, femelles XX, XY et YY). Ces derniers constituent des outils majeurs de l’étude du déterminisme et de la différenciation du sexe et soulèvent de nombreuses questions concernant les interactions génotype/phénotype sexuels chez cette espèce. Au regard de ces considérations, nous nous sommes fixés 2 objectifs principaux : 1. Déterminer l’influence du génotype sexuel sur certains aspects liés à la biologie reproductive chez le tilapia du Nil tels que la qualité du sperme, les taux de stéroïdes sexuels (testostérone, T ; 17β-œstradiol, E2 ; 11-cétotestostérone, 11KT) et les comportements agressifs. Le génotype sexuel ne semble pas avoir d’influence sur la qualité gamétique des mâles, puisqu’aucune différence n’est observée entre les individus XX, XY et YY, alors que paradoxalement, les taux de 11KT sont plus élevés chez les mâles XX. De la même manière, les femelles présentent des taux croissants d’E2 chez les individus XX, XY et YY. Ces différences de taux de stéroïdes sexuels pourraient être liées aux taux d’agressivité (évalué par la quantification de huit comportements agonistiques dans des confrontations mâle-femelle) plus élevés des mâles XX et des femelles XY et YY et engendrer des perturbations des comportements reproducteurs. Des recherches complémentaires sont nécessaires d’une part, pour évaluer l’effet du génotype sur la qualité des gamètes des femelles et d’autre part, pour déterminer si les modifications phénotypiques observées sont liées à l’expression du génotype sexuel ou à des perturbations engendrées par les traitements hormonaux d’inversion sexuelle administrés durant la période de différenciation des gonades. 2. Explorer les mécanismes du déterminisme et de la différenciation à des stades précoces du développement. Grâce à la mise au point d’une technique d’inversion sexuelle ciblant les périodes embryonnaire et larvaire (avant 10 jpf) par des expositions courtes (4h) d’embryons âgés d’un jpf à des androgènes (11KT, 17α-méthyltestostérone), un inhibiteur de l’aromatase (Fadrozole) ou un œstrogène (17α-éthynylœstradiol), nous avons confirmé l’existence d’une période sensible de la différenciation sexuelle avant le développement des gonades. Les voies de différenciation phénotypique semblent être différentes en fonction du génotype, puisque la masculinisation des embryons XX est moins efficace (max 10%) que la féminisation d’embryons XY (max 91%). De la même manière, un probable effet chromosomique rend inefficace la féminisation d’embryons YY. La féminisation des individus XY est concomitante avec une augmentation des taux de T et d’E2 et d’expression de l’aromatase cérébrale à 4 jpf qui pourrait indiquer un rôle précoce du cerveau dans la différenciation sexuelle. Dans l’ensemble, nos résultats nous permettent de suggérer, d’une part, que les premiers événements moléculaires de la différenciation sexuelle du tilapia sont initiés avant la formation des gonades, et d’autre part, que chez les individus sexuellement inversés, des différences sexuelles peuvent apparaître dans le cerveau avant ou en même temps que le développement des gonades et induire des modifications comportementales à l’âge adulte. La question du rôle possible du cerveau dans la différenciation des gonades reste ouverte. [less ▲]

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