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See detailControlled synthesis of poly(vinylamine)-based copolymers by organometallic-mediated radical polymerization
Dréan, Mathilde ULg; Guégan, Philippe; Detrembleur, Christophe ULg et al

in Macromolecules (2016), 49(13), 4817-4827

iving/controlled polymerization methods have enabled the synthesis of numerous (co)polymers with defined compositions and architectures. However, the precision design of poly(vinylamine)-based copolymers ... [more ▼]

iving/controlled polymerization methods have enabled the synthesis of numerous (co)polymers with defined compositions and architectures. However, the precision design of poly(vinylamine)-based copolymers remains challenging despite their extensive use in various fields of applications and the clear benefits to finely tune their properties. Here, we report on a two-step strategy for the synthesis of tailor-made poly(vinylamine) derivatives through the organometallic- mediated radical (co)polymerization (OMRP) of N-vinyl- acetamide and/or N-methylvinylacetamide followed by acid hydrolysis of the acetamide groups. A series of well-defined homopolymers as well as statistical and block copolymers with pendant primary and/or secondary amines having controlled molar masses, compositions, and low dispersities were produced accordingly. The reactivity ratios of the comonomers as well as the composition drift along the chain were determined in order to have a precise idea of the polymer structures. These advances represent a significant step toward an efficient platform for synthesis of this important class of amino group-containing (co)polymers. [less ▲]

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See detailHolocene paleoclimate reconstructions from belgian continental archives
Allan, Mohammed ULg; VERHEYDEN, sophie; CRUCIFIX, Michel et al

Poster (2016, June 28)

Speleothems and peatbogs presented in Belgium are interesting archives for atmospheric pollution record and climate variability. Both archives are reliable continental environmental archives of high ... [more ▼]

Speleothems and peatbogs presented in Belgium are interesting archives for atmospheric pollution record and climate variability. Both archives are reliable continental environmental archives of high interest due to their dating possibilities and their possibility to preserve multi-proxy records of environmental and climatic dynamics. Combining studies on speleothems and peatbogs from the same area will provide an age-constrained reconstruction of climatic variability at annual resolution for key intervals of the Holocene. The reconstructed precipitation and temperature curves in NW European settings, as proposed in HOPES, are essential to better constrain the Northern Hemisphere climatic record and to test climate models. Our strategy is derived from a comparative study of two continental archives speleothems and peatbogs. Time series of elemental and stable isotope geochemistry will be established for the 2 archives. For peatbog, the reconstructions of temperature (derived from stable C and O isotope), precipitation (derived from humification) and dust flux (from elementary geochemical signature) would track climate changes with subdecadal resolution. As an innovative part, Laser Ablation analyse of elemental geochemistry on impregnated peat section will allow to reach an annual resolution in the dust flux. For speleothems, records of temperature (derived from oxygen and carbon isotopic composition of calcite) and effective rainfall (derived from geochemical ratios) would reach a seasonal resolution. [less ▲]

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See detailA Selective and Highly Sensitive MIR Photoacuostic Sensor for Trace Gas Monitoring
Lassen, M; Lamar, L; Balslev-Harder, D et al

Conference (2016, June 28)

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See detailTransparent superhydrophobic coatings from amphiphilic-fluorinated block copolymers synthesized by aqueous polymerization-induced self-assembly
Ouhib, Farid ULg; Dirani, Ali; Aqil, Abdelhafid ULg et al

in Polymer Chemistry (2016), 7(24), 3998-4003

Preparation of transparent and superhydrophobic coatings by co-deposition of an aqueous solution of an amphiphilic fluorinated block copolymer (FBC) with silica particles was developped. Spin- coating of ... [more ▼]

Preparation of transparent and superhydrophobic coatings by co-deposition of an aqueous solution of an amphiphilic fluorinated block copolymer (FBC) with silica particles was developped. Spin- coating of this aqueous solution onto glass followed by an appropriate thermal treatment promotes the self-assembly of the hybrid material with the formation of superhydrophobic, robust and transparent coatings. [less ▲]

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See detailL'acétonémie : un bien ou un mal nécessaire pour la vache laitière ?
Beckers, Yves ULg

Conference given outside the academic context (2016)

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See detailMapping and investigating phase anomalies in GPS data onboard Low Earth Orbiters
Wautelet, Gilles ULg; Bruinsma, Sean; Loyer, Sylvain et al

Poster (2016, June 28)

To face important societal challenges like sea level variations, climate change and natural hazards management (tsunami detection, earthquakes, crustal deformations…), modern science rely more and more on ... [more ▼]

To face important societal challenges like sea level variations, climate change and natural hazards management (tsunami detection, earthquakes, crustal deformations…), modern science rely more and more on precise geodesy. Precise Orbit Determination (POD) is of major concern in the frame of altimetry or gravity recovery missions like GOCE or GRACE. Using the GPS receiver onboard, orbits at cm-level accuracy are generally achieved in both kinematic and reduced-dynamic approaches using dual frequency code and phase measurements. GPS data processing generally uses the Ionospheric-Free (IF) combination to get rid of the ionospheric delay, which is varying with the season, latitude, local time and solar activity. However, large discrepancies in the orbit determination are still observed over polar and equatorial regions, which turn into artefacts and errors in the derived scientific products (gravity field, sea surface height…). More precisely, large RMS values are strongly correlated to phase anomalies occurring on GPS receivers: cycle slips, data unavailability or enhanced measurement noise, especially on L2 signal. Phase anomalies are generally observed when the satellite orbit crosses regions where ionospheric scintillations occur, which are defined as rapid fluctuations in phase and amplitude of the GNSS signals. The occurrence of scintillations exhibits large day-to-day variations and depends mainly on geomagnetic latitude, season and local time. At low latitudes, maximum occurrence of scintillations is observed 15-20° on either side of the geomagnetic equator. Scintillations also occur at auroral and polar latitudes, where their intensity increases with increasing geomagnetic activity. This paper aims at detecting, mapping and understanding the phase anomalies experienced by LEO satellites and analyzing their correlation with geomagnetic activity, latitude, season and local time. Several LEO satellites at different altitudes are analyzed (e.g. SWARM, GRACE or JASON), which allows a multi-layer analysis of the underlying ionospheric phenomenon, including scintillation. The latter are generally measured with several indices, like the amplitude index S4 or the phase index SigmaPhi (σφ), which are usually derived from 100Hz measurements performed by dedicated scintillation monitors. In this study, we compute a similar index (called pseudo-σφ) using GPS phase data at 1Hz coming from POD GNSS antenna. A detailed study of the occurrence rate and the severity of pseudo-σφ, together with cycle slips and other spurious phase data, will be performed for different LEO satellites. [less ▲]

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See detailAudition au Sénat sur une proposition de loi spéciale visant à modifier la loi spéciale sur la Cour constitutionnelle (proposition Doc. parl. 6-273/1)
Behrendt, Christian ULg

Report (2016)

Audition publique en Commission des affaires institutionnelles du Sénat, 3 juin 2016

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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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