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See detailConception of a near-IR spectrometer for ground-based observations of massive stars
Kintziger, Christian ULg; Desselle, Richard ULg; Loicq, Jerôme ULg et al

Poster (2016, June 27)

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships ... [more ▼]

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships from the scientific requirements and telescope characteristics, the entire optical design of the spectrograph is presented. Specific optical elements, such as a toroidal lens, are introduced to improve the instrument’s performances. Then, the verification of predicted optical performances is investigated through optical analyses such as resolution checking. Eventually, the star positioning system onto the central fiber core is explained. [less ▲]

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See detailAnalysis of the temporal dynamics of suspended sediment fluxes using discrete sampling and continuous turbidity measurements in the Meuse and Scheldt watersheds (Wallonia, Belgium)
Van Campenhout, Jean ULg

Conference (2016, June 27)

Soil erosion may be apprehended at different scales and different time intervals in order to quantify the transport of suspended sediment at the outlet of large watersheds. In the Walloon region, several ... [more ▼]

Soil erosion may be apprehended at different scales and different time intervals in order to quantify the transport of suspended sediment at the outlet of large watersheds. In the Walloon region, several projects were conducted to estimate the erosion rates in watersheds ranging from 16 to 2900 km². Both discrete sampling methods (allowing the coverage of a large area through field campaigns during major floods or moderate hydrological events) and continuous turbidity measurements devices (studying a small number of locations with a small sampling interval and a wide range of sampled flow rates) were tested in these projects. At the region scale (Figure 1), the mean annual sediment erosion rate reaches several hundreds of tons per square kilometre and per year in the loess belt (Senne, Dyle and Gette watersheds) with a huge sensibility to extreme hydrological events while the mean annual sediment transport value reaches 20 t.km-2.yr-1 in Lorraine, 34 t.km-2.yr-1 in Ardenne and 69 t.km-2.yr-1 in Entre-Vesdre-et-Meuse. The aims of our researches are 1) the determination of the effect of the sampling frequency on the annual sediment transport rate estimation ; 2) the definition of the prerequisites to perform efficient turbidity measurements in rivers with high suspended load concentrations ; 3) the identification of the sources of errors due to the interpolation methods through a comparison of several methods proposed in the literature allowing the quantification of long-term erosion rates using a small number of discrete samples ; 4) the observation and explanation of clockwise and anti-clockwise hysteresis loops in relationship with the sequence of floods occurring in large watersheds and 5) the highlighting of the regional differentiation in the erosion rates, particle size and proportion of organic matter in the suspended load samples due to spatial variations of the soil substrate and the land cover characteristics. [less ▲]

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See detailPhysical education and leisure: What’s the link?
Cloes, Marc ULg

Conference (2016, June 27)

All around the world, practitioners and researchers point out that people are becoming less and less physically active and adopt more and more sedentary behaviours. Such changes in the Human lifestyle ... [more ▼]

All around the world, practitioners and researchers point out that people are becoming less and less physically active and adopt more and more sedentary behaviours. Such changes in the Human lifestyle could have dramatic consequences as pointed out by the ‘Designed to move’ movement (Morris, 2013). To fight against that irresistible evolution, the need of a multisectorial approach is illustrated by the complexity of the socio-ecological model (Sallis et al., 2006). It underlines the large array of variables that play in the physical activity that someone is able to integrate into his/her life. Nevertheless, school has been identified as one major pillar of the promotion of an active lifestyle (van Sluijs et al., 2007). According to the knowledge and specific competences that they acquire during their studies, physical education (PE) teachers are considered as the potential cornerstones of such action (Tappe & Burgeson, 2004). While it was traditionally focused on the development of the youth’s physical, motor, and social competences of the students, since two decades, PE is increasingly more associated to the preparation of physically educated citizens. It means that what the students learn during their PE lessons should be useful outside the school and for a lifelong term. This concept is become a determining pedagogical principle: the physical literacy (Whitehead, 2013). In parallel, PE teachers are now requested to play a role on the health of their students despite if few evidence confirm that they can be successful in influencing the future behaviours of the children/adolescents to who they teach (Green, 2014). New pedagogical approaches are proposed nowadays in order to increase the effectiveness of the PE teachers’ intervention. This is linked to another pedagogical principle: accountability. Leisure activities enter progressively in the PE curriculum. Students benefit of more experiences that they could operate in their community. This requires more partnerships between school and leisure actors in order to implement original projects. Students must learn to become autonomous and smart decision makers able to identify the way to integrate PA in their leisure. [less ▲]

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See detailQuantification of nitrogen stress on winter wheat by multispectral vision based on reflectance measurements and textural descriptors
Marlier, Guillaume ULg; Gritten, Fanny; Fraipont, Guillaume ULg et al

Conference (2016, June 27)

Hand-held sensors (SPAD meter, N-Tester, …) are used for detecting the leaves nitrogen concentration (Nc) on the basis of an optical detection of the chlorophyll concentration. These devices are active ... [more ▼]

Hand-held sensors (SPAD meter, N-Tester, …) are used for detecting the leaves nitrogen concentration (Nc) on the basis of an optical detection of the chlorophyll concentration. These devices are active sensors: an internal radiation source emits light and transmission through a leaf is measured in the red (650 nm) and in the near-infrared (920 nm) spectral regions. These devices present several drawbacks. The nitrogen concentration is gained by an indirect way through the chlorophyll concentration and the leaves have to be fixed in a defined position for the measurements. These drawbacks could be overcome by an imaging device that measures the canopy reflectance. In this context, the objective of the paper is to analyse the potential of different image parameters for estimating nitrogen concentration. The tests were carried out on parcels submitted to total nitrogen inputs of 180 kg N.ha-1 but with different fertilization modalities. Reference Nc measurements were obtained by the Kjeldahl method and a Hydro N-Tester (Yara). The developed imaging system comprised a CMos camera and a set of 22 interference filters ranging from 450 to 950 nm mounted on a wheel steered by a stepper motor. The image acquisition and the motor rotation were controlled by a program written in C++. The crop was imaged vertically at one meter height. The raw images presented 1280x1024 pixels covering an area of approximately 0.5x0.4 m and were recorded with a 12-bit luminance resolution. To deal with the natural irradiance variability of the scene, a white reference was used and the integration time was automatically adjusted for each image. The image treatment included the segmentation of Photosynthetically Active Leaves (PAL) by using Bayes theorem and the computation of the mean PAL reflectance after correction of background and illumination fluctuations. Nc was estimated on the basis of the 22 filters by Partial Least Square (PLS) method and by four filters selected by Best Subset Selection (BSS). In comparison with the Kjeldahl method, the estimation of Nc by the Hydro N-Tester, the PLS and the BSS (filters 600-80, 950-100, 650-40 and 450-80 nm) gave determination coefficient and standard error respectively equal to of 0.53, 0.29 %; 0.67, 0.21%; 0.56 and 0.25%. This indicated that the full multi-spectral approach gave significantly better Nc estimation than a portable device and suggested that a camera equipped with four filters would give similar results. In addition to these promising results, the Nc measurement were correlated to leaf area measurements and textural descriptors. For this purpose, image analysis based on Grey Level Co-occurrence Matrix (GLCM), Fourier transform and spatial autocorrelation were performed to characterize the nitrogen state of the crop. [less ▲]

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See detailInteractions between calcium channels and SK channels in midbrain dopamine neurons and their impact on pacemaker regularity: Contrasting roles of N- and L-type channels.
de Vrind, V.; Scuvée-Moreau, Jacqueline ULg; Drion, Guillaume ULg et al

in European Journal of Pharmacology (2016)

Although small-conductance Ca2+-activated K+ (SK) channels and various types of voltage-gated Ca2+ (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is ... [more ▼]

Although small-conductance Ca2+-activated K+ (SK) channels and various types of voltage-gated Ca2+ (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is unclear. More particularly, the role of various Cav channel types in either promoting irregularity of firing (by generating an inward current during SK channel blockade) or promoting regularity of firing (by providing the source of Ca2+ for the activation of SK channels) has not been systematically explored. We addressed this question using intracellular and extracellular recordings from substantia nigra, pars compacta (SNc), dopaminergic neurons in rat midbrain slices. Neurons were pharmacologically isolated from their differences. When examining the ability of various Cav channel blockers to inhibit the SK-mediated afterhyperpolarization (AHP), we found that only the N-type Cav channel blocker ω-conotoxin-GVIA was able to reduce the apamin-sensitive AHP, but only partially (~40%). Specific blockers of L, P/Q, T or R channels had no effect on this AHP. Combining ω-conotoxin-GVIA and other specific blockers did not yield greater block and even the broad Cav blocker Cd2+ induced a submaximal (~75%) effect. Extracellular recordings examining firing regularity yielded congruent results: none of the specific blockers was able to increase firing irregularity to the extent that the specific SK blocker apamin did. The irregularity of firing observed with apamin could only be reversed by blocking L-type Ca2+ channels. Thus various sources of Ca2+ appear to be required for SK channel activation in SNc neurons (some of them still unidentified), ensuring robustness of pacemaking regularity. [less ▲]

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See detailWaveguides for walking droplets
Filoux, Boris ULg; Hubert, Maxime ULg; Schlagheck, Peter ULg et al

E-print/Working paper (2016)

When gently placing a droplet onto a vertically vibrated bath, a drop can bounce without coalescing. Upon increasing the forcing acceleration, the droplet is propelled by the wave it generates and becomes ... [more ▼]

When gently placing a droplet onto a vertically vibrated bath, a drop can bounce without coalescing. Upon increasing the forcing acceleration, the droplet is propelled by the wave it generates and becomes a walker with a well defined speed. We investigate the confinement of a walker in different rectangular cavities, used as waveguides for the Faraday waves emitted by successive droplet bounces. By studying the walker velocities, we discover that 1d confinement is optimal for narrow channels of width of D≃1.5λF. We also propose an analogy with waveguide models based on the observation of the Faraday instability within the channels. [less ▲]

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See detailNappe Vibration Mitigation Techniques for Free-overfall Structrures
Lodomez, Maurine ULg; Crookston, Brian M.; Tullis, Blake P. et al

in Full Proceedings: Hydraulic Structures and Water System Management (2016, June 27)

Nappe vibration is a phenomenon that has been witnessed in the field for a variety of different free overflow hydraulic structures operating at low heads, such as fountains, crest gates, and weirs. This ... [more ▼]

Nappe vibration is a phenomenon that has been witnessed in the field for a variety of different free overflow hydraulic structures operating at low heads, such as fountains, crest gates, and weirs. This phenomenon is visually characterized by oscillations in the thin nappe cascading downstream of the control structure. These oscillations can produce a significant level of noise and acoustic pressure waves, which can increase the environmental and societal impacts of the hydraulic structure. As a result, a detailed investigation has been undertaken to identify practical and effective mitigation solutions for free-overfall structures where nappe vibration may be of concern. Research is being performed with a prototype-scale linear weir (weir length of 3.5 m and fall height of 3 m) located at the Engineering Hydraulics laboratory of the University of Liège, to assess the effectiveness of various crest modifications and any corresponding impacts to hydraulic efficiency (i.e., flow rate). The test matrix includes the optimization (position and spacing of elements) of three mitigation solutions which are projecting bolts, deflectors and step. In addition, a high-speed camera and audio equipment have been used to evaluate effectiveness of the configurations in reducing nappe vibration. Finally, this practical study has identified countermeasures suitable for retrofits and new construction, easy to construct, durable, hydraulically efficient, and with minimal potential for debris collection. [less ▲]

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See detailLa joie qui vient après l'attente. Retour sur la parution de J.-M. Mouillie et J.-P. Narboux, Sartre. L'Être et le néant. Nouvelles lectures, Paris, Les Belles Lettres, 2015, 212 p.
Recchia, Fabio ULg

in Année Sartrienne (L') (2016)

Cette publication consiste en une recension des "Nouvelles lectures" de "L'Être et le Néant", publiées à l'occasion de la sélection de ce texte à l'agrégation externe de philosophie 2015. Il s'agit de ... [more ▼]

Cette publication consiste en une recension des "Nouvelles lectures" de "L'Être et le Néant", publiées à l'occasion de la sélection de ce texte à l'agrégation externe de philosophie 2015. Il s'agit de faire retour sur cet événement que constitue la parution d'un tel recueil proposant, selon nous, une "relecture franche" de l'Essai de 1943 - un texte longtemps tenu pour le parent pauvre de la philosophie de Sartre, dans la mesure où cet ouvrage compte peu de monographies spécialisées à son sujet. Identifiant par ailleurs que ces "Nouvelles lectures" renvoient à nouvelle génération de chercheurs, cette recension souligne de quelle manière ce recueil apporte un commentaire lumineux de l'appareillage ontologique de l'Essai de 1943, témoigne en outre d'une attention particulièrement vive à l'égard des thématiques de l'individuation ainsi que de l'intersubjectivité chez Sartre, et articule enfin un dialogue entre les champs des "Études sartriennes" et celui de la philosophie de l'esprit contemporaine. [less ▲]

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See detailMarijan Molé à l'aube du nouveau comparatisme indo-iranien
Swennen, Philippe ULg

Conference (2016, June 24)

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See detailHealth Literacy: Eduquer pour mieux soigner
Bragard, Isabelle ULg

Scientific conference (2016, June 24)

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See detailEmerging Hybridities under Networked Agribusiness in Argentina
Delvenne, Pierre ULg

Conference (2016, June 24)

Science and Technology Studies (STS) are paying greater attention to the interactions between new technologies and politico-economic orders. Dynamics of promises and expectations with regard to ... [more ▼]

Science and Technology Studies (STS) are paying greater attention to the interactions between new technologies and politico-economic orders. Dynamics of promises and expectations with regard to technological developments, and their uptake, play a major role in shaping political-economic policies, institutional practices and wider societal mutations. Informed by the theoretical perspective of co-production (Jasanoff 2004), this paper addresses the political economy of GM soy agriculture in Argentina as both epistemic and social orders. We engage ‘micro’ perspectives looking at situated social experiments with farmers and their interrelations with ‘macro’ phenomena such as capital-labour relations and forms of ‘neoliberalism’. We find that the emerging hybridities in present time’s Argentina are caught between the promissory futures of agroindustrial innovation and the historical, political and material conditions of agricultural production that give rise to these presents in the first place. Looking at three of such hybridities (the blurring of boundaries between modern/national, agriculture/industry and leasing/ownership), we highlight the ways in which elements of political-economic structures and human agency got bound up with technoscientific advances (Jasanoff 2015). Our contribution reveals the importance of the concept of ‘network’ to make sense of the dominant logic of agribusiness and it amounts to ‘rugged’ approach to networks with due attention to the complex topographies of circulating power and morality. [less ▲]

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See detailResponse to droughts and heat waves of the productivity of natural and agricultural ecosystems in Europe within ISI-MIP2 historical simulations
François, Louis ULg; Henrot, Alexandra-Jane ULg; Dury, Marie ULg et al

Conference (2016, June 23)

According to the projections of climate models, extreme events such as droughts and heat waves are expected to become more frequent and more severe in the future. Such events are known to severely impact ... [more ▼]

According to the projections of climate models, extreme events such as droughts and heat waves are expected to become more frequent and more severe in the future. Such events are known to severely impact the productivity of both natural and agricultural ecosystems, and hence to affect ecosystem services such as crop yield and ecosystem carbon sequestration potential. Dynamic vegetation models are conventional tools to evaluate the productivity and carbon sequestration of ecosystems and their response to climate change. However, how far are these models able to correctly represent the sensitivity of ecosystems to droughts and heat waves? How do the responses of natural and agricultural ecosystems compare to each other, in terms of drought-induced changes in productivity and carbon sequestration? In this contribution, we use ISI-MIP2 model historical simulations from the biome sector. Eight dynamic vegetation models have participated in the biome sector intercomparison of ISI-MIP2: CARAIB, DLEM, JULES, LPJ-GUESS, LPJml, ORCHIDEE, VEGAS and VISIT. We focus the analysis on well-marked droughts or heat waves that occured in Europe after 1970, such as the 1976, 2003 and 2010 events. For most recent studied events, the model results are compared to the response observed at several eddy covariance sites in Europe, and, at a lager scale, to the drops in crop productivities reported in national statistics or to the drought impacts retrieved from satellite data (Terra MODIS instrument). [less ▲]

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See detailReceding-Horizon Control of Distributed Generation to Correct Voltage or Thermal Violations and Track Desired Schedules
Soleimani Bidgoli, Hamid ULg; Glavic, Mevludin ULg; Van Cutsem, Thierry ULg

in Proceedings of the 19th PSCC (2016, June 23)

This paper presents a real-time, centralized control system acting on the active and reactive powers of distributed generators when the network experiences voltage and/or thermal limits violation. The ... [more ▼]

This paper presents a real-time, centralized control system acting on the active and reactive powers of distributed generators when the network experiences voltage and/or thermal limits violation. The control resorts on multi-step receding-horizon optimization. The objective is to minimize the deviations of Dispersed Generation Units (DGU) active and reactive powers from reference values. The reactive power corrections have priority over the active ones. Furthermore, the formulation is such that DGU powers are restored to their desired schedule as soon as operating conditions allow doing so. Three modes of operation of the proposed controller are presented, involving dispatchable units as well as DGUs operated to track maximum power output. The effectiveness of the proposed control is illustrated through detailed simulations of a 75-bus, 11-kV system hosting 22 DGUs. [less ▲]

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See detailPublic Education Expenditures, Growth and Income Inequality
Artige, Lionel ULg; Cavenaile, Laurent

Conference (2016, June 23)

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