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See detailThe determinants of tropical forest deciduousness: disentangling the effects of rainfall and geology in central Africa
Ouedraogo, Dakis-Yaoba ULg; Fayolle, Adeline ULg; Gourlet-Fleury, Sylvie et al

in Journal of Ecology (2016)

1. Understanding the environmental determinants of forests deciduousness i.e. proportion of deciduous trees in a forest stand, is of great importance when predicting the impact of ongoing global climate ... [more ▼]

1. Understanding the environmental determinants of forests deciduousness i.e. proportion of deciduous trees in a forest stand, is of great importance when predicting the impact of ongoing global climate change on forests. In this study, we examine (i) how forest deciduousness varies in relation to rainfall and geology, and (ii) whether the influence of geology on deciduousness could be related to differences in soil fertility and water content between geological substrates. 2. The study was conducted in mixed moist semi-deciduous forests in the northern part of the Congo basin. We modelled the response of forest deciduousness to the severity of the dry season across four contrasting geological substrates (sandstone, alluvium, metamorphic and basic rocks). For this, we combined information on forest composition at genus level based on commercial forest inventories (62 624 0.5 ha plots scattered over 6 million of ha), leaf habit, and rainfall and geological maps. We further examined whether substrates differ in soil fertility and water-holding capacity using soil data from 37 pits in an area that was, at the time, relatively unexplored. 3. Forest deciduousness increased with the severity of the dry season, and this increase strongly varied with the geological substrate. Geology was found to be three times more important than the rainfall regime in explaining the total variation in deciduousness. The four substrates differed in soil properties, with higher fertility and water-holding capacity on metamorphic and basic rocks than on sandstone and alluvium. The increase in forest deciduousness was stronger on the substrates that formed resource-rich clay soils (metamorphic and basic rocks) than on substrates that formed resource-poor sandy soils (sandstone and alluvium). 4. Synthesis. We found evidence that tropical forest deciduousness is the result of both the competitive advantage of deciduous species in climates with high rainfall seasonality, and the persistence of evergreen species on resource-poor soils. Our findings offer a clear illustration of wellknown theoretical leaf carbon economy models, explaining the patterns in the dominance of evergreen versus deciduous species. And, this large-scale assessment of the interaction between climate and geology in determining forest deciduousness may help to improve future predictions of vegetation distribution under climate change scenarios. In central Africa, forest is likely to respond differently to variation in rainfall and/or evapotranspiration depending on the geological substrate. [less ▲]

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See detailBiotechnologies algales: état actuel et perspectives de valorisation de la biomasse
Franck, Fabrice ULg

Scientific conference (2016, May 12)

Detailed reference viewed: 14 (1 ULg)
Peer Reviewed
See detailCombined Centralized and Local Voltage correction in Active Distribution Network
Soleimani Bidgoli, Hamid ULg

in Combined Centralized and Local Voltage correction in Active Distribution Network (2016, May 12)

This paper presents a two-level real-time voltage control scheme to address the voltage violations in distribution grids hosting a significant number of Dispersed Generation Units (DGUs). The proposed ... [more ▼]

This paper presents a two-level real-time voltage control scheme to address the voltage violations in distribution grids hosting a significant number of Dispersed Generation Units (DGUs). The proposed scheme consists of a centralized and a local reactive power control. The local control provides fast response after a disturbance, reducing its impact and enhancing voltage quality. The centralized control relies on Model Predictive Control (MPC). It uses measurements collected throughout the network to bring the voltages inside desired limits. To do so, it adjusts in a coordinated way the reactive power set-points of the DGUs taking into account the local controls. The control method effectiveness has been evaluated on a 75-bus 11-kV test system hosting 22 DGUs. [less ▲]

Detailed reference viewed: 27 (7 ULg)
See detailLa cristallurie
GADISSEUR, Romy ULg

Conference (2016, May 12)

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See detailMédecine et philosophie dans l'Anonyme de Londres
Ricciardetto, Antonio ULg

Scientific conference (2016, May 12)

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See detailLa légistation REACH: une opportunité d’innovation pour l’économie biobasée
Schmetz, Quentin ULg; Istasse, Thibaut ULg; Jacquet, Nicolas ULg et al

Scientific conference (2016, May 12)

Cet exposé fait le point sur les tendances en cours dans ce secteur au travers de divers cas concrets tels que la substitution de retardateur de flamme, plastifiant et surfactant par des alternatives ... [more ▼]

Cet exposé fait le point sur les tendances en cours dans ce secteur au travers de divers cas concrets tels que la substitution de retardateur de flamme, plastifiant et surfactant par des alternatives issues du végétale. Il aborde également les différents programmes de recherche réalisés au laboratoire de Chimie Biologique Industrielle de Gembloux Agro-Bio Tech qui ont permis le développement de nouvelles substances biobasées en accord avec une chimie plus durable et répondant aux exigences de REACH. [less ▲]

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See detailCentralized Model Predictive Control of Multi-Terminal Direct Current Grids
Papangelis, Lampros ULg

in Proc. of the 8th IEEE Benelux Young Researchers Symposium 2016 (2016, May 12)

This work describes a centralized control for Multi-Terminal Direct Current (MTDC) grids. It is based on Model Predictive Control (MPC) whose aim is to satisfy a desired schedule, while avoiding or ... [more ▼]

This work describes a centralized control for Multi-Terminal Direct Current (MTDC) grids. It is based on Model Predictive Control (MPC) whose aim is to satisfy a desired schedule, while avoiding or correcting any system limit violation. The central controller collects voltage and power measurements from the converters of the system in regular intervals and sends back converter power setpoints. The latter are calculated by solving a quadratic programming problem subject to linear constraints and using a simplified model for the DC system. In addition, the overall MTDC grid control structure including the local and the centralized controllers is described. [less ▲]

Detailed reference viewed: 22 (10 ULg)
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See detailModelling nitrogen incorporation by primary producers of a Mediterranean coastal area
Elkalay, Khalid; Frangoulis, Constantin; Richir, Jonathan ULg et al

Conference (2016, May 11)

The aim of this study was to simulate the uptake flow of nitrogen (gN m-2) of P. oceanica meadow for 4 primary producers of the bay of Calvi (Corsica, France) (phytoplankton, macro-algae, the Posidonia ... [more ▼]

The aim of this study was to simulate the uptake flow of nitrogen (gN m-2) of P. oceanica meadow for 4 primary producers of the bay of Calvi (Corsica, France) (phytoplankton, macro-algae, the Posidonia oceanica leaves and their epiphytes). The model developed for this purpose simulates the evolution of nitrogen incorporation. The effect of the light intensity, and the water column temperature and concentration in internal and external nitrogen on nitrogen incorporation by the 4 primary producers is modeled. Thus, the incorporation rate of both NO3-and NH4+by phytoplankton was more important than for benthic producers. Macro-algae incorporations had intermediate incorporation rates between the ones of, the phytoplankton and P. oceanic leaves and their epiphytes. The incorporation of NH4+ by the phytoplankton is higher than the incorporation of NO3-. The model appears well adapted to establish the main environmental factors that determine the incorporation of inorganic nitrogen by the various primary producers. It is also able to represent the relative importance of nitrogen incorporation by the various producers. [less ▲]

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See detailAudition à la Chambre des représentants sur les aspects constitutionnels du droit de grève
Behrendt, Christian ULg

Report (2016)

Audition publique en Commission des affaires sociales de la Chambre des Représentants, Bruxelles, 11 mai 2016

Detailed reference viewed: 59 (3 ULg)
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See detailImpact de l’ancrage sur les herbiers de posidonie
Abadie, Arnaud ULg

Scientific conference (2016, May 11)

La posidonie (Posidonia oceanica), forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers jouent un rôle écologique essentiel en oxygénant le ... [more ▼]

La posidonie (Posidonia oceanica), forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers jouent un rôle écologique essentiel en oxygénant le milieu grâce à la photosynthèse et en séquestrant du CO2 au sein de leur complexe racinaire dans le sédiment (ou "matte"). Ces activités métaboliques entraînent une importante modification des conditions biogéochimiques du substrat qui favorisent le maintien de la plante. Les herbiers de posidonie se développant dans les zones côtières, ils sont impactés par les activités anthropiques (urbanisation, pollution, fermes aquacoles, ancrage) qui peuvent entraîner d’importantes destructions et des régressions de leur zone de recouvrement. L’ancrage intensif dans les herbiers à faible profondeur y génère des trouées, ou "intermattes". Les destructions engendrées par les navires de petite taille (< 10 m) peuvent, dans certaines conditions, être recolonisées par la posidonie. Cependant certaines zones sont soumises à l’ancrage intensif de navires de plaisance de grande taille (> 20m), qui est susceptible de générer des intermattes d’une étendue plus importante. Ce phénomène d’expansion ne peut s’expliquer par la seule destruction mécanique. L’arrachage de la strate foliaire de la posidonie par les ancres semble entraîner de profondes modifications physiques et chimiques dans le sédiment. Un milieu anoxique défavorable à son développement paraît se créer. Des composés toxiques pour la plante, tel que le sulfure d’hydrogène (H2S), pourraient alors s’introduire dans ses tissues entraînant une limitation de son développement, voire sa disparition menant ainsi à une amplification des dégâts mécaniques de l’ancrage. [less ▲]

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See detailAccurate measurement of radius evolution as a function of direction in 3D images
Plougonven, Erwan ULg; Hubert, Julien ULg; Collin, Frédéric ULg et al

Poster (2016, May 11)

Very often the reason for using of X-Ray tomography in a research project is to measure the evolution of some geometrical characteristic. The sought characteristic may be explained in simple words like ... [more ▼]

Very often the reason for using of X-Ray tomography in a research project is to measure the evolution of some geometrical characteristic. The sought characteristic may be explained in simple words like size, shape, or distance, but in practice measures based on these notions can have a complex implementation. We present a simple problem, measuring the evolution of radius in a cylindrical sample (a common shape for sample preparation for tomography) and how this value differs according the direction in which we look, when such evolution is known to be anisotropic. The solution is not unique, but we show that a naïve manual approach are not accurate enough, and how even a simple geometric notion such as radius needs a thorough definition in relation to its applicability to 3D image analysis. We extend the argument to how a good understanding of the notions and algorithms used in the quantification of geometrical characteristics can directly affect the pertinence and representativity of the results. [less ▲]

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See detailOzone concentration and CO2 flux monitoring in a belgian forest
Hurdebise, Quentin ULg; Bergmans, Benjamin; Aubinet, Marc ULg

Poster (2016, May 11)

Temperate forests, as other ecosystems and oceans, mitigate the accumulation in the atmosphere of CO2, the main responsible for the current climate change. It is, therefore, a necessity to understand how ... [more ▼]

Temperate forests, as other ecosystems and oceans, mitigate the accumulation in the atmosphere of CO2, the main responsible for the current climate change. It is, therefore, a necessity to understand how these forests react and will react in a changing environment. That requires long-term monitoring of the environment. Tropospheric ozone is one parameter to monitor as it affects the forest by inducing oxidative stress once inside the leaves. Using 16 years of continuous data from an air quality monitoring station managed by the ISSeP (Institut Scientifique de Service Public) located in a mixed forest in east Belgium, we identified ozone concentration extreme events and we investigated their occurrence frequency as well as their relation with climatic variables and air components. As variables are subjected to daily, yearly and inter-annual dynamics, anomalies were used to detect extreme events. To obtain anomalies, we removed the previously mentioned dynamics from half-hourly raw data. Daily and yearly dynamics were removed first and explained 40% of the variability observed in half-hourly ozone concentrations. Then, the inter-annual dynamic was obtained by computing the yearly mean of the residuals, it accounted for 2% of the variability observed. A significant (p<0.01) decreasing trend was observed for these residuals. Determining if that trend is site specific or regionally observed can be done by applying the same analysis to the other sites from the network managed by the ISSeP. No significant trend in the yearly frequency and intensity of extreme events was observed. We used a stepwise regression to identify the variables that explain these extreme events. Significant relations were found between ozone concentration and climatic variables (vapor pressure deficit, temperature, radiation and wind direction) as well as other air components concentration (NO2, NO, NOX, CO). The next step will be to estimate the forest capacity to uptake ozone in order to predict ozone-induced damage and compared it to the CO2 uptake and H2O emissions measured in an ICOS site, the Vielsalm Terrestrial Observatory, located in the same forest at less than 300 meters from the air quality monitoring station. [less ▲]

Detailed reference viewed: 24 (1 ULg)
See detailRecollection and Familiarity in Normal Aging
Simon, Jessica ULg; Gilsoul, Jessica ULg; Bastin, Christine ULg

Conference (2016, May 11)

Detailed reference viewed: 19 (2 ULg)
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See detailSynthèse des présentations et perspectives futures sur la qualité des services éducatifs pendant la petite enfance dans une optique de collaborations internationales
Pirard, Florence ULg

Scientific conference (2016, May 11)

Cette conférence de clôture propose une synthèse des différentes contributions sur "la qualité des services éducatifs pendant la petite enfance: un bilan de dix ans de recherche et d'intervention" ainsi ... [more ▼]

Cette conférence de clôture propose une synthèse des différentes contributions sur "la qualité des services éducatifs pendant la petite enfance: un bilan de dix ans de recherche et d'intervention" ainsi qu'une une mise en perspective internationale. Elle interroge la notion de qualité de l’accueil des jeunes enfants et de leur famille et celle d'accompagnement professionnel qui lui est associée. Elle souligne l'importance des fonctions de leadership orienté par des visées de qualités d'accueil dans les services. [less ▲]

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See detailLa médecine du futur en question(s): les objets connectés
Coucke, Philippe ULg

in Healthcare Executive (2016)

Detailed reference viewed: 40 (2 ULg)
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See detailLa gestion des ressources humaines au sein des ONG internationales: les relations siège-filiale dans un contexte instable (le cas du Burundi)
Hakizumukama, Alexis ULg

Doctoral thesis (2016)

Executive summary Applied to different contexts, the approach to management and HRM practices initially operative, considered by some as the essential and universal key to organizational success, may face ... [more ▼]

Executive summary Applied to different contexts, the approach to management and HRM practices initially operative, considered by some as the essential and universal key to organizational success, may face some contextual constraints and lead to conflicting results. Now, the local context brings to the subsidiary of international organizations little or no opportunities for the Headquarters. At the same time, the local context adds specific constraints. The consideration of these opportunities and constraints by the officials of the subsidiary is a real managerial challenge for them. This implies much more than a simple transfer of what has always worked well elsewhere. This questioning of the success of the universalist perspective pushes us to diagnose other possible ways to suggest for the approach to management and HRM practices that could better accommodate the local management. Our study is particularly concerned with international NGOs operating in sub-Saharan Africa and Burundi in particular. Our theoretical argument mobilizes universalist, culturalist and institutionalist approaches. Our study concerns only the subsidiaries of international NGOs and not their Headquarters. Note that throughout our work, the word "Siège" means the Headquarters and not the local management of the subsidiary. To mark this distinction, we opt to write it with a capital "S". Based on a contextualist analysis of five case studies of subsidiaries of international NGOs, we find that, upon their arrival or within the first years of implementation of the subsidiary, the leaders of these international subsidiaries almost always opt for a relational or even paternalistic model of management. Indeed, this model allows a gain in confidence and the establishement of strong relationships between the expats and the locals, and between volunteers and employees. The latter model also helps to react or deal with the complexity of an unstable local context (civil war, hatred and ethnic conflicts, distrust versus foreigners, oral tradition culture, lack of separation between work and family life, lack of some skills in the labor market and poverty of the population). Beyond the local constraints, pressure from the Headquarters, and the donors' requirements often result in the evolution of the business model implemented during the establishment period. But toward what model is moving the subsidiary, why, how and what are the implications for HRM practices? This is the series of questions we try to answer throughout this work. To get there, we pay special attention to the power games, the identification of the most influential players, the relationships, the mechanisms of prevention and / or of conflict management and the mobilization around the common goal. Our study shows that the managers of subsidiaries have two possible choices of a position: control logic or adaptation logic. The results of our research argue for the second option to be the most favorable to take into consideration the local context and to contribute to the emergence of consistent and very innovative HRM practices. Our work shows that the model based on the adaptation logic is more effective when the appropriation of the Headquarters rule by the members of the subsidiary is dominated by joint regulation mechanisms, and when the management of the subsidiary is polyphonic for what concerns managing the evolution of contextual factors. In fact, the latter mechanisms lead to the organization, in due time, to a genuine process of organizational change. The polyphonic style is generally characterized by flexibility, autonomy, accountability, collaboration, cooperation within teams and the search for compromise to satisfy the essential interests of the different stakeholders, including those at Headquarters. However, we note that some managers, guided by rational mimicry derived from the culture of their country of origin and their experience elsewhere, tried control-based management resulting in the domination of regulatory mechanisms either autonomous or controlled. Our observation is that the control-based management model leads the subsidiary in a logic of submission or circumvention of the rules and practices developed by the parent company. This management model quickly faces major resistance from certain groups of stakeholders who feel that their interests are threatened. For example, internal conflicts occur in these subsidiaries at the expense of the cooperation and the achievement of desired results. Highlighting the importance of the local context and the relationships Headquarters- subsidiaries together with the role of the management style in the evolution of HRM practices in the local management of international NGOs working in unstable and specific context (land and sector insufficiently studied up to now), this study brings a great contribution to international management and intercultural management theory in general and sub-Saharan Africa in particular. [less ▲]

Detailed reference viewed: 44 (7 ULg)