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See detailDynamique des flux de carbone entre l'atmosphère et des écosystèmes ouest-africains: cas des forêts et savanes sous climat soudanien au Bénin
Ago, Expédit Evariste ULg

Doctoral thesis (2016)

In West Africa as elsewhere in other parts of the world, natural and anthropogenic ecosystems are the main sources for energy, building poles and livestock fodder. They probably behave like some nets ... [more ▼]

In West Africa as elsewhere in other parts of the world, natural and anthropogenic ecosystems are the main sources for energy, building poles and livestock fodder. They probably behave like some nets carbon sinks, but there are only few studies that have focused on their carbon exchanges with the atmosphere. Preserving terrestrial ecosystems has proven essential to any emissions mitigation policy of green house gases, notably CO2. This thesis focuses on the analysis of the CO2 fluxes in three contrasting types of the ecosystem under a Sudanian climate in Benin. Specifically, it was a cultivated forest, a protected forest and a cultivated savannah. Turbulent CO2 fluxes were measured by an eddy-covariance system placed above the ecosystems. The measurements were made during variable periods of 17 months (cultivated forest), 18 months (protected forest) and 29 months (cultivated savannah). The three studied sites have been equipped by the hydro-meteorological observatory AMMA-CATCH and the national project Ouémé 2025. The CO2 fluxes data were completed by some meteorological measurements and by an inventory of dominating species the three sites. Fluxes were examined on the basis of the two main seasons imposed by the cycle of West African Monsoon. The spatial (local and regional) and temporal (hour, seasonal, annual and inter-annual) scales were considered according to the sites. Water was the main factor controlling the dynamic of the terrestrial West African ecosystems. At the daily scales, the radiation was the main driving variable of the net CO2 fluxes. Besides that radiation control, a clear relationship was observed between the net CO2 fluxes and the canopy conductance. A limited impact of saturation deficit was observed, notably during the afternoon. The soil moisture was the main factor governing the ecosystem respiration. However, no clear dependency of the ecosystem respiration on the temperature was observed at hourly scale. After long dry periods, the ecosystem respiration increased immediately in response to the first significant rains. The CO2 fluxes and the characteristics of the protected forest were always higher than those of the cultivated savannah at the daily and seasonal scales. At the annual scale, while the protected forest (Bellefoungou) and cultivated savannah (Nalohou) sequestered an average of 640 ± 50 and 232 ± 27 g C m-2, respectively considering the period of the measurements, the cultivated forest was in equilibrium with 29 ± 16 g C m-2. Overall, the three studied ecosystems were more efficient during morning and wet season than during afternoon and dry season. Finally, this study revealed that the inter-annual variability of the carbon sequestration by the cultivated savannah was mainly controlled by the ecosystem respiration variability in relation to the soil water content variation. [less ▲]

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See detailForaging wireworms are attracted to root-produced volatile aldehydes
Barsics, Fanny ULg; Delory, Benjamin M.; Delaplace, Pierre ULg et al

in Journal of Pest Science (2016)

Soil-dwelling insects are known to react to chemical cues they encounter in the rhizosphere. Whether wireworms (Coleoptera, Elateridae) use root-emitted volatile organic chemicals to localize their host ... [more ▼]

Soil-dwelling insects are known to react to chemical cues they encounter in the rhizosphere. Whether wireworms (Coleoptera, Elateridae) use root-emitted volatile organic chemicals to localize their host plant remains, however, poorly understood. Here, we aimed at identifying chemical cues released by barley roots that attract Agriotes sordidus. In a first behavioral experiment, we assessed the ability of wireworms to orient towards live barley roots, using dual-choice olfactometers suitable for belowground insects. Then, we collected the volatile organic compounds (VOC) produced by barley roots using a dynamic head-space sampling approach. VOC were quantified and identified using gas chromatography—mass spectrometry (GC–MS). The odorant blend is composed of four aldehydes, namely hexanal, (E)-hex-2-enal, (E)-non-2-enal, and (E,Z)-nona-2,6-dienal. In a second set of dual-choice bioassays, wireworms were attracted towards a synthetic blend of these four major compounds. However, the synthetic blend was not as attractive as live roots, which is partially explained by the absence of CO2, commonly known as a strong attractant for soil-dwelling insects. While CO2 indicates the presence of living material in the vicinity, we hypothesize that additional VOC inform about the plant suitability. A better understanding of these belowground signals would contribute to the development of new integrated control strategies against wireworms. [less ▲]

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See detailPrésentation de "Fleurs d'équinoxe" de Yasujiro Ozu
Tomasovic, Dick ULg

Conference given outside the academic context (2016)

Présentation du film "Fleurs d'équinoxe" de Yasujiro Ozu (1958). Analyse des thématiques de l'oeuvre et de l'art de la mise en scène du cinéaste.

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See detailLa littérature panoramique par ses éditeurs
Stienon, Valérie ULg

Conference (2016, February 13)

Phénomène de société et de mode, la littérature panoramique identifiée rétrospectivement par Walter Benjamin constitue surtout une entreprise éditoriale majeure. Elle mobilise un grand nombre d’acteurs ... [more ▼]

Phénomène de société et de mode, la littérature panoramique identifiée rétrospectivement par Walter Benjamin constitue surtout une entreprise éditoriale majeure. Elle mobilise un grand nombre d’acteurs (libraires, illustrateurs, graveurs, imprimeurs) à l’échelle européenne et prépare de nouveaux statuts pour la fonction même d’éditeur, qui voit naître un discours spécifique à son propos, dans une époque qui précède de peu sa professionnalisation et dans un contexte de circulation médiatique accrue de l’imprimé sous ses formes les plus variées. La communication se centrera sur deux éditeurs panoramiques français importants, Curmer et Aubert, pour mettre en évidence la nature de leurs projets, l’originalité de leurs méthodes et l’identité de leurs personnels. On reviendra sur le rôle de passeur culturel du premier et de rassembleur d’une équipe d’artistes du second, deux caractéristiques à l’origine du rayonnement de la littérature panoramique. On examinera aussi les particularités de certaines de leurs productions, entre texte et image, journal et livre, ouvrage de collection et fascicule éphémère, jouant sur les matériaux et les circuits de diffusion. [less ▲]

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See detailNitrous oxide dynamics in sea ice
Kotovitch, Marie ULg; Fripiat, François; Moreau, Sebastien et al

Poster (2016, February 12)

Fluctuations in greenhouse gases (GHGs) concentration alter the energetic budget of the climate system. There is high confidence that natural systems related to snow, ice and frozen ground (including ... [more ▼]

Fluctuations in greenhouse gases (GHGs) concentration alter the energetic budget of the climate system. There is high confidence that natural systems related to snow, ice and frozen ground (including permafrost) are affected. Nitrous oxide (N2O) is one of the potent GHG naturally present in the atmosphere, but witch has seen his concentration growing since industrial era. N2O has a lifetime in the atmosphere of 114 years and a global warming potential (GWP) of 298 to be compared to carbon dioxide that has a GWP of 1. N2O is also describe as the dominant ozone-depleting substance emitted in the 21st Century. Yet, there are still large uncertainties and gaps in the understanding of the cycle of this compound through the ocean and particularly in sea ice. Sources and sinks of N2O are therefore still poorly quantified. The main processes (with the exception of transport processes) involved in the N2O cycle within the aquatic environment are nitrification and denitrification. To date, only one study by Randall et al. present N2O measurements in sea ice. Randall et al. pointed out that sea ice formation and melt has the potential to generate sea-air or air-sea fluxes of N2O, respectively. Study on ammonium oxidation and anaerobic bacterial cultures shows that N2O production can potentially occur in sea ice. Denitrification can act as a sink or a source of N2O. In strictly anaerobic conditions, N2O is removed by denitrification. However, denitrification can also occur in presence of O2 at trace level concentrations (<0.2 mg L-1), and in these conditions there is a large N2O production. Recent observations of significant nitrification in Antarctic sea ice shed a new light on nitrogen cycle within sea ice. It has been suggested that nitrification supplies up to 70% of nitrate assimilated within Antarctic spring sea ice. Corollary, production of N2O, a by-product of nitrification, can potentially be significant. This was recently confirmed in Antarctic land fast ice in McMurdo Sound, where N2O release to the atmosphere was estimated to 4 µmol.m-2.yr-1. This assessment is probably an underestimate since it only accounts for dissolved N2O while a significant amount of N2O is likely to occur in the gaseous form like N2, O2 and Ar. Finally, nitrification produces little N2O in oxygenated waters but the N2O production yield from nitrification strongly increases as O2 levels decrease. Hence, it is not possible to distinguish the sources of N2O solely based on bulk N2O concentrations or environmental conditions, while deepened knowledge of processes is needed to well understand N2O emissions. [less ▲]

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See detailAnnual dynamics of pCO2 within bulk sea ice and related CO2 fluxes at Cape Evans (Antarctica)
Van Der Linden, Fanny ULg; Champenois, Willy ULg; Heinesch, Bernard ULg et al

Poster (2016, February 12)

Sea ice is a biome actively participating in the regional cycling of CO2 as both a source and a sink at different times of the year. In the frame of the YROSIAE project (Year-Round Ocean-Sea-Ice ... [more ▼]

Sea ice is a biome actively participating in the regional cycling of CO2 as both a source and a sink at different times of the year. In the frame of the YROSIAE project (Year-Round Ocean-Sea-Ice-Atmosphere Exchanges), annual dynamics of sea ice pCO2 was compared with CO2 fluxes measured by automated accumulation chambers at Cape Evans (Ross Island, Antarctica). Results confirmed a general trend of brine pCO2 supersaturation with respect to the atmosphere during the late winter (concentration of dissolved inorganic carbon - DIC - in brine and brine expulsion in the brine skim) leading to CO2 degassing, and undersaturation during the spring (carbon-uptake by autotrophs and brine dilution) leading to atmospheric CO2 uptake. Despite high primary production at the bottom of the ice in spring, DIC profiles suggest that sea ice as a whole appears to be net heterotrophic. Still, sea ice absorbs CO2 from the atmosphere, as a result of physical processes. Some variability in the CO2 fluxes (both in magnitude and sign) could not be explained by variability in sea ice pCO2 but rather seemed driven by variability in atmospheric conditions and sea ice surface properties. For instance, in late spring, CO2 fluxes showed a diurnal variability (from CO2 degassing to uptake) related to atmospheric temperature variations. Large and episodic CO2 fluxes were systematically positively correlated with strong wind events, and large CO2 degassing was observed over thin, wet and salty snow cover. [less ▲]

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See detailThermally induced magnetization switching in Gd/Fe multilayers
Xu, Chudong; Ostler, Thomas ULg; Chantrell, Roy

in Physical Review B (2016), 93

A theoretical model of Gd/Fe multilayers is constructed using the atomistic spin dynamics formalism. By varying the thicknesses and number of layers we have shown that a strong dependence of the energy ... [more ▼]

A theoretical model of Gd/Fe multilayers is constructed using the atomistic spin dynamics formalism. By varying the thicknesses and number of layers we have shown that a strong dependence of the energy required for thermally induced magnetization switching (TIMS) is present;with a larger number of interfaces, lower energy is required. The results of the layer resolved dynamics show that the reversal process of the multilayered structures, similar to that of a GdFeCo alloy, is driven by the antiferromagnetic interaction between the transition-metal and rare-earth components. Finally, while the presence of the interface drives the reversal process, we show here that the switching process does not initiate at the surface but from the layers furthest from it, a departure from the alloy behavior which expands the classes of material types exhibiting TIMS. [less ▲]

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See detailMercury and persistent organic pollutant concentrations in free-ranging bottlenose dolphins from Lower Keys and Coastal Everglades (South Florida)
Damseaux, France ULg; Kiszka, Jeremy; Heithaus, Michael et al

Poster (2016, February 12)

The bottlenose dolphin (Tursiops truncatus) is a major apex predator and the most common cetacean species found in nearshore waters of South Florida, including the Lower Florida Keys (LFK) and the Florida ... [more ▼]

The bottlenose dolphin (Tursiops truncatus) is a major apex predator and the most common cetacean species found in nearshore waters of South Florida, including the Lower Florida Keys (LFK) and the Florida Coastal Everglades (FCE). The objective of this study was 1) to assess contamination levels of total mercury (T-Hg) in skin and persistent organic pollutants (PCBs, PBDEs, DDT, HCH, HCB, DLCs and PCDD/Fs) in blubber samples of bottlenose dolphins from the LFK (8 males and 16 females) and from the FCE (13 males and 9 females). Pollutants were analysed by the mean of Direct Mercury analyser (for T-Hg), GC-ECD (POPs) and GC-MS (DLCs and PCDD/Fs). The PCBs were the main compounds found in bottlenose dolphins from the LFK and FCE. The most present congeners where the CB no. 28, 52, 101, 138, 153 and 180 (ΣPCBs LFK males: 13420.5 ng.g-1 lipids, ΣPCBs LFK females: 9683.4 ng.g-1 lipids, ΣPCBs FCE males: 5637.9 ng.g-1 lipids, ΣPCBs FCE females: 1426.9 ng.g-1 lipids). PCBs concentrations were significantly higher in individuals from the LFK than those from the FCE but significantly lower than those from other locations in the south-eastern US. Unlike organic pollutants, T-Hg concentrations were significantly higher in FCE male dolphins (LFK: 2936.0 ng.g-1 dw, FCE: 10048.3 ng.g-1 dw). These high concentrations were the highest recorded in the south-eastern US and are most likely due to the presence of mangrove ecosystems. This study highlights the complexity of contaminant dynamics (inorganic vs. organic), even at small spatial scales. [less ▲]

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See detailBiologie, sociologie, philosophie. Le fait moral entre Durkheim et Bergson
Caeymaex, Florence ULg

Conference (2016, February 12)

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See detailThe secret life of a Mediterranean seagrass litter macrofauna community : a history of oxygen
Remy, François ULg; Michel, Loïc ULg; Sturaro, Nicolas ULg et al

Conference (2016, February 12)

Most of the foliar primary production of Posidonia oceanica, a major Mediterranean seagrass, sheds in autumn and is exported from the meadow to adjacent areas to form "Exported Macrophytodetritus ... [more ▼]

Most of the foliar primary production of Posidonia oceanica, a major Mediterranean seagrass, sheds in autumn and is exported from the meadow to adjacent areas to form "Exported Macrophytodetritus Accumulations", EMAs. These EMAs are a habitat, shelter and feeding place for an abundant and diverse community of macrofauna. Being very dynamic places and potentially playing a role of transition compartment between water column and sediment, EMAs present high variability in term of physicochemical conditions and more specifically in term of oxygen concentration. Mild to severe hypoxic periods (2 - 0.01 mL O2.L-1) can be observed in situ at different moments of the year, and this variability thus potentially play a structuring role on the macrofauna community. During this study, our main specific questions were (1) Does oxygen stratification occur inside EMAs? (2) If present, how long does it take to observe this stratification? (3) Is the macrofauna impacted and do the dominant species occupy defined positions inside the different micro-habitats? To assess the importance of this impact, an experimental study was conducted in October 2014 near the STARESO oceanographic station (Calvi, Corsica) using an original "layer-sampling" design. The experimental construction was put underwater inside an EMA for 48 hours at a depth of 8m. Samples were collected (N=8) in a 20cm thick EMA using "sealed" boxes to sample every 5cm, from the sediment, to the water column. Oxygen, nutrients and of course the litter itself (containing the macrofauna) were sampled carefully to make sure no exchange occurred between the 4 different layers. After data analysis, the assessment was clear: oxygen stratification occurred in less than 48h and oxygen level inside the layer close to the sediment experienced a fast decrease below the hypoxia threshold (2 mL O2.L-1). Diversity was highly impacted, showing a clear positive link with oxygen concentration. Macrofauna also appeared to follow this oxygen stratification but this response was very species specific. Some species didn't follow oxygen and are present in every layer and most of them were strongly positively linked to oxygen concentration. But a few (Nebalia strausi and Athanas nitescens) were strongly negatively linked to oxygen concentration and were present only in the more hypoxic layers. This experimentation thus confirmed our in situ observations. Oxygen stratification occurred quickly (< 48h) when EMAs were experiencing calm weather. This stratification observed from the water column to the sediment was very marked. Diversity and abundance of most abundant macrofauna species were drastically influenced by this stratification, showing the importance of these micro-habitats in structuring of this macrofauna community. [less ▲]

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See detailTrophic plasticity of Antarctic echinoids under contrasted environmental conditions
Michel, Loïc ULg; David, Bruno; Dubois, Philippe et al

Poster (2016, February 12)

Echinoids are common members of Antarctic zoobenthos, and different groups can show important trophic diversity. As part of the ANT-XXIX/3 cruise of RV Polarstern, trophic plasticity of sea urchins was ... [more ▼]

Echinoids are common members of Antarctic zoobenthos, and different groups can show important trophic diversity. As part of the ANT-XXIX/3 cruise of RV Polarstern, trophic plasticity of sea urchins was studied in three neighbouring regions (Drake Passage, Bransfield Strait and Weddell Sea) featuring several depth-related habitats offering different trophic environments to benthic consumers. Three families with contrasting feeding habits (Cidaridae, Echinidae and Schizasteridae) were studied. Gut content examination and stable isotopes ratios of C and N suggest that each of the studied families showed a different response to variation in environmental and food conditions. Schizasteridae trophic plasticity was low, and these sea urchins were bulk sediment feeders relying on sediment-associated organic matter in all regions and/or depth-related habitats. Cidaridae consumed the most animal-derived material. Their diet varied according to the considered area, as sea urchins from Bransfield Strait relied mostly on living and/or dead animal material, while specimens from Weddell Sea fed on a mixture of dead animal material and other detritus. Echinidae also showed important trophic plasticity. They fed on various detrital items in Bransfield Strait, and selectivity of ingested material varied across depth-related habitats. In Weddell Sea, stable isotopes revealed that they mostly relied on highly 13C-enriched food items, presumably microbially-reworked benthic detritus. The differences in adaptive strategies could lead to family-specific responses of Antarctic echinoids to environmental and food-related changes. [less ▲]

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See detailDroit international et pacifisme en Belgique de 1870 à 1940 : une cohabitation complexe
Genin, Vincent ULg

Conference (2016, February 12)

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See detailLe projet DEMETER. Quelles transférabilités ?
Georges, François ULg

Scientific conference (2016, February 12)

Dans cette conférence de clôture du projet Tempus DEMETER, nous abordons trois thématiques : l’approche par compétences, l’enseignement en ligne et la pédagogie de l’enseignement supérieur. Ces trois ... [more ▼]

Dans cette conférence de clôture du projet Tempus DEMETER, nous abordons trois thématiques : l’approche par compétences, l’enseignement en ligne et la pédagogie de l’enseignement supérieur. Ces trois thématiques participent au développement d’un apprentissage de qualité. Nous les fondons théoriquement et abordons les conditions de leur déploiement dans l’enseignement supérieur. [less ▲]

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See detailBenevolent Ideology and Women’s Economic Decision-Making: When Sexism Is Hurting Men’s Wallet
Silvestre, Aude ULg; Sarlet, Marie; Huart, Johanne ULg et al

in PLoS ONE (2016), 11(2),

Can ideology, as a widespread “expectation creator,” impact economic decisions? In two studies we investigated the influence of the Benevolent Sexism (BS) ideology (which dictates that men should provide ... [more ▼]

Can ideology, as a widespread “expectation creator,” impact economic decisions? In two studies we investigated the influence of the Benevolent Sexism (BS) ideology (which dictates that men should provide for passive and nurtured women) on women’s economic decision- making. In Study 1, using a Dictator Game in which women decided how to share amounts of money with men, results of a Generalized Linear Mixed Model analysis show that higher endorsement of BS and contextual expectations of benevolence were associated with more very unequal offers. Similarly, in an Ultimatum Game in which women received monetary offers from men, Study 2’s Generalized Linear Mixed Model’s results revealed that BS led women to reject more very unequal offers. If women’s endorsement of BS ideology and expectations of benevolence prove contrary to reality, they may strike back at men. These findings show that BS ideology creates expectations that shape malefemale relationships in a way that could be prejudicial to men. [less ▲]

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See detailAnimation des Rencontres de la webcréation #5 spécial animation et BD pendant le festival Anima
Dozo, Björn-Olav ULg

Conference given outside the academic context (2016)

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See detailWitnessing Fukushima Secondhand: Collage, Archive and Travelling Memory in Jacques Ristorcelli’s Les Écrans
Crucifix, Benoît ULg

in The Comics Grid: Journal of Comics Scholarship (2016), 6

Cultural memory in comics studies mostly seems to revolve around nonfictional graphic novels tackling major historical events. Drawing on recent trends in cultural memory studies, this paper focuses on ... [more ▼]

Cultural memory in comics studies mostly seems to revolve around nonfictional graphic novels tackling major historical events. Drawing on recent trends in cultural memory studies, this paper focuses on Jacques Ristorcelli‘s Les Écrans (2014) as an experimental counterpoint where memory is animated by the author’s use of collage. Delving into an ‘archive’ of heterogeneous elements, Les Écrans borrows from old war comics in a way that reflexively constructs a discourse on the past of the medium and its memory. Through the analysis of Ristorcelli’s book, this paper highlights how collage can function in comics as a work of memory that reaches back to appropriative practices common to both readers and fine artists. [less ▲]

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