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See detailTaller trees, denser stands and greater biomass in semi-deciduous than in evergreen lowland central African forests
Fayolle, Adeline ULg; Loubota Panzou, Grâce Jopaul ULg; Drouet, Thomas et al

in Forest Ecology & Management (2016), 374

Accurate height-diameter allometry is crucial for the estimation of forest biomass and carbon stocks. Tree height measurements over a large range of diameters and species are urgently needed in the ... [more ▼]

Accurate height-diameter allometry is crucial for the estimation of forest biomass and carbon stocks. Tree height measurements over a large range of diameters and species are urgently needed in the tropics, specifically in central Africa, for the development of locally derived height-diameter allometric equations and the conversion of forest inventory data into biomass estimates, and for the validation of remotely sensed canopy height that mostly rely on a few specific field sites. In this study, we aimed to identify the variation in height-diameter allometry of tropical trees between forest types and among species in central Africa, and we examined the consequences for biomass estimation. Height and diameter were measured for a total of 521 trees over a large range of diameters in two forest types in southern Cameroon, 10–240 cm in the evergreen forest and 11–182 cm in the semi-deciduous forest. A total of ten allometric models including asymptotic and non-asymptotic models were fitted to the heightdiameter data. Measured tree diameters, grouped into 10 cm wide diameter classes up to 150, from commercial forest inventory data (0.5 ha plots, n = 2101 and n = 5152, respectively in the evergreen and in the semi-deciduous forests) were converted into biomass estimates using general allometric models with and without including our site-specific height-diameter allometry. Though debated in the literature, our results supported a saturation of tree height with tree diameter both at site and species level, with asymptotic models better depicting the height-diameter allometry. Height-diameter allometry significantly differed between forest types and these local height-diameter equations also differed from published equations. For a given diameter, trees tended to be taller in the semi-deciduous forest than in the evergreen forest, as already reported between moist and wet forests in pantropical studies. Similar trends were reported within species for the three species shared by both forest types, suggesting an environmental control of tree allometry. Because of the low performance of the bioclimatic stress variable to predict tree height and of the slight soil differences between the two forest types, the environmental determinants of height-diameter allometry remain to be explored. In addition to tree allometry variation, structural differences (basal area and density) were also identified between the two forest types using commercial forest inventory data at genus level, and both allometry and forest structure (taller trees and denser stands) contributed to the greater biomass per hectare of the semi-deciduous forest. [less ▲]

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See detailInfluence of plant roots on electrical resistivity measurements of cultivated soil columns
Maloteau, Sophie ULg; Blanchy, Guillaume ULg; Javaux, Mathieu et al

Poster (2016, April)

The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil ... [more ▼]

The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil column. For this research, it is assumed that roots system affect the electrical properties of the rhizosphere. Indeed the root activity (by transporting ions, releasing exudates, changing the soil structure,…) will modify the rhizosphere electrical conductivity (Lobet G. et al, 2013). This experiment is included in a bigger research project about the influence of roots system on geophysics measurements. Measurements are made on cylinders of 45 cm high and a diameter of 20 cm, filled with saturated loam on which seeds of Brachypodium distachyon (L.) Beauv. are sowed. Columns are equipped with electrodes, TDR probes and temperature sensors. Experiments are conducted at Gembloux Agro-Bio Tech, in a growing chamber with controlled conditions: temperature of the air is fixed to 20°C, photoperiod is equal to 14 hours, photosynthetically active radiation is equal to 200 µmol m-2s-1, and air relative humidity is fixed to 80 %. Columns are fully saturated the first day of the measurements duration then no more irrigation is done till the end of the experiment. [less ▲]

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See detailExposition "Magie et raison. Elisa von der Recke et l'affaire Cagliostro"
Leyh, Valérie ULg

in Culture, le Magazine Culturel de l'Université de Liège (2016)

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See detailUnderground Pumped Storage Hydropower using abandoned open pit mines: influence of groundwater seepage on the system efficiency
Pujades, Estanislao ULg; Bodeux, Sarah ULg; Orban, Philippe ULg et al

Poster (2016, April)

Pumped Storage Hydropower (PSH) plants can be used to manage the production of electrical energy according to the demand. These plants allow storing and generating electricity during low and high demand ... [more ▼]

Pumped Storage Hydropower (PSH) plants can be used to manage the production of electrical energy according to the demand. These plants allow storing and generating electricity during low and high demand energy periods, respectively. Nevertheless, PSH plants require a determined topography because two reservoirs located at different heights are needed. At sites where PSH plants cannot be constructed due to topography requirements (flat regions), Underground Pumped Storage Hydropower (UPSH) plants can be used to adjust the electricity production. These plants consist in two reservoirs, the upper one is located at the surface (or at shallow depth) while the lower one is underground (or deeper). Abandoned open pit mines can be used as lower reservoirs but these are rarely isolated. As a consequence, UPSH plants will interact with surrounding aquifers exchanging groundwater. Groundwater seepage will modify hydraulic head inside the underground reservoir affecting global efficiency of the UPSH plant. The influence on the plant efficiency caused by the interaction between UPSH plants and aquifers will depend on the aquifer parameters, underground reservoir properties and pumping and injection characteristics. The alteration of the efficiency produced by the groundwater exchanges, which has not been previously considered, is now studied numerically. A set of numerical simulations are performed to establish in terms of efficiency the effects of groundwater exchanges and the optimum conditions to locate an UPSH plant. [less ▲]

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See detailA first database for landslide studies in densely urbanized areas of the intertropical zone: Abidjan, Côte d’Ivoire
Gnagne, Lorng Frédéric ULg

Conference (2016, April)

A detail first database for landslide studies in densely urbanized areas have been produced in two prone-areas which are mainly affected. During rain season, landslides occurred in Abobo and Attecoube ... [more ▼]

A detail first database for landslide studies in densely urbanized areas have been produced in two prone-areas which are mainly affected. During rain season, landslides occurred in Abobo and Attecoube causing social and economic damages. Studies on landslides have been restricted or often simply lacking. Landslides were located by GPS and tentatively dated through inquiries during the survey. While 12 landslides were accurately dated that way from the main rain seasons of 2013 to 2015, newspapers analysis and municipal archive consultation allowed us to assign a part of the rest to the last decade. Field inquiries were also used to collect information about fatalities and the local conditions of landsliding. This first landslide inventory in Attecoube provides clues about the main potential controls on landsliding, natural and anthropogenic, and will help define adequately anthropogenic variables to be used in the susceptibility modelling. [less ▲]

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See detailExperimental Tests and Numerical Modelling on Slender Steel Columns at High Temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Journal of Structural Fire Engineering (2016), 7(1), 30-40

Purpose The purpose of this paper is to gain from experimental tests an insight into the failure mode of slender steel columns subjected to fire. The tests will also be used to validate a numerical model ... [more ▼]

Purpose The purpose of this paper is to gain from experimental tests an insight into the failure mode of slender steel columns subjected to fire. The tests will also be used to validate a numerical model. Design/methodology/approach A series of experimental fire tests were conducted on eight full-scale steel columns made of slender I-shaped Class 4 sections. Six columns were made of welded sections (some prismatic and some tapered members), and two columns were made of hot rolled sections. The nominal length of the columns was 2.7 meters with the whole length being heated. The load was applied at ambient temperature after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. Heating was applied by electrical resistances enclosed in ceramic pads. Numerical simulations were performed with the software SAFIR® using shell elements. Findings The tests have allowed determining the appropriate method of application of the electrical heating system for obtaining a uniform temperature distribution in the members. Failure of the columns during the tests occurred by combination of local and global buckling. The numerical model reproduced correctly the failure modes as well as the critical temperatures. Originality/value The numerical model that has been validated has been used in subsequent parametric analyses performed to derive design equations to be used in practice. This series of test results can be used by the scientific community to validate their own numerical or analytical models for the fire resistance of slender steel columns. [less ▲]

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See detailEntretenir le souvenir de Charlemagne en Belgique. Regards croisés de médiévistes et de contemporanéistes
Close, Florence ULg; Lanneau, Catherine ULg

Book published by Société pour le progrès des études philologiques et historiques - extrait de la Revue Belge de Philologie et d'Histoire, t. 93 (2015/3-4) (2016)

À l’heure des grandes revendications identitaires d’inspiration romantique, le jeune état belge a fermement bataillé pour asseoir et renforcer un sentiment national propre. Il a cherché dans le passé le ... [more ▼]

À l’heure des grandes revendications identitaires d’inspiration romantique, le jeune état belge a fermement bataillé pour asseoir et renforcer un sentiment national propre. Il a cherché dans le passé le plus lointain les arguments susceptibles de saper certaines accusations tendant à présenter la Belgique comme un état sans nation, une construction artificielle. Charlemagne fut l’un des maillons de la chaîne. Ce volume constitue les actes d'une journée d'étude organisée à l'occasion du 1200 anniversaire de sa mort en vue de confronter les recherches de spécialistes des temps récents aux remarques et questionnements de carolingianistes avertis. [less ▲]

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See detailLa figure de Charlemagne dans la vulgarisation historique belge. Exemples choisis
Lanneau, Catherine ULg

in Revue Belge de Philologie et d'Histoire (2016), 93(2015/3-4),

Common ancestor of the Belgians, civilizing Christian emperor, father of Europe: these are some of the political (polemical) ways used to describe Charlemagne in the Belgium. This contribution seeks to ... [more ▼]

Common ancestor of the Belgians, civilizing Christian emperor, father of Europe: these are some of the political (polemical) ways used to describe Charlemagne in the Belgium. This contribution seeks to decipher and interpret these descriptions. What do we remember, or want to remember, from the origins and actions of the Carolingian emperor to show to the Belgians? Without pretending to be complete, certain marked tendencies and manifest evolutions are pointed out, found in the popular historical books for adults and children. Two key periods are defined: the first decades of the Belgian independence and the period after 1945. The final results are mixed: Charlemagne was certainly an icon, but in each of his avatars, failed to convince or win the majority support. His best enduring memory seems to be found today in the Euregion Meuse-Rhine, mostly because of the commercial and touristic value. [less ▲]

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See detailMise au point d’une nouvelle méthode de diagnostic des allergènes du froment par Western blot 2D
BERTHOLET, Catherine ULg; GADISSEUR, Romy ULg; Quinting, Birgit

in Revue Française d'Allergologie (2016, April), 56(3), 284

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See detailClinically Relevant Optical Properties of Bifocal, Trifocal, and Extended Depth of Focus Intraocular Lenses
Gatinel, Damien; Loicq, Jerôme ULg

in Journal of Refractive Surgery (2016), 32(4), 273-280

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ... [more ▼]

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ZMB00 (bifocal; Abbott Medical Optics, Abbott Park, IL), TECNIS Symfony ZXR00 (extended depth of focus; Abbott Medical Optics), and FineVision GFree hydrophobic (trifocal; PhysIOL, Liège, Belgium). Their surface topography was analyzed by optical microscopy. Modulation transfer function (MTF) and spherical aberrations were determined on optical bench for variable pupil apertures and with two cornea models (0 μm and +0.28 μm). United States Air Force target imaging was analyzed for different focal points (near, intermediate, and far). Point spread function (PSF) and halos were quantified and compared. RESULTS: The three lenses presented step-like optic topography. For a pupil size of 3 mm or greater, clearly distinctive MTF peaks were observed for all lenses: two peaks for the extended depth of focus and bifocal lenses with +1.75 and +4.00 diopters (D) addition, respectively, and three peaks for the trifocal lens with +1.75 and +3.50 addition for intermediate and near vision, respectively. The extended depth of focus and bifocal lens had slightly higher MTF at best focus with the +0.28 μm cornea model than with the 0 μm model, whereas the trifocal lens was likely to be more independent of the corneal spherical aberrations.CONCLUSIONS: It appears that the three lenses rely on light diffraction for their optical performance, presenting halos with comparable intensities. For small pupil apertures (< 3 mm), the MTF peaks for the far and intermediate focal distances of the trifocal and extended depth of focus lenses overlap, but the trifocal lens presented an additional MTF peak for the near focal points. [less ▲]

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See detailÉgypte romaine. Les bébés du dépotoir
Ricciardetto, Antonio ULg

Article for general public (2016)

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See detailReset Inquiry!
Thoreau, François ULg; d'Hoop, Ariane; Amat, Amandine et al

in Latour, Bruno (Ed.) Reset Modernity (2016)

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See detailL'usage de la médiation scolaire entre contre-culture et nouveau mode d'exercice du pouvoir
Dethier, Baptiste ULg

in Ferréol, Gilles (Ed.) Médiations et Régulations (2016)

La référence à la notion de médiation dans différents pans de la société, notamment dans l’action publique, s’accompagne de nombreux discours et apports présumés. Toutefois, ceux-ci s’avèrent peu ... [more ▼]

La référence à la notion de médiation dans différents pans de la société, notamment dans l’action publique, s’accompagne de nombreux discours et apports présumés. Toutefois, ceux-ci s’avèrent peu opérationnalisables en situation, le travail de nouveaux agents s’exposant à une éventuelle instrumentalisation. Ces enjeux seront interrogés dans ce chapitre en trois parties prenant leur source dans une recherche doctorale consacrée à la médiation en milieu scolaire. D’abord, la notion de médiation sera contextualisée, dans un cadre sociétal large et dans la sphère éducative, en soulignant deux tendances contrastées. Ensuite, un aperçu du travail des médiateurs, principaux acteurs de la médiation scolaire en Belgique francophone, et de l’utilisation de leurs services sera proposé afin d’illustrer plus concrètement cette tension. Enfin, nous discuterons de ce contraste afin d’en pointer le lien fondamental avec la notion même de médiation. [less ▲]

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See detailEvidence for the alignment of quasar radio polarizations with large quasar group axes
Pelgrims, Vincent ULg; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (2016)

Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large quasar groups (LQG) to which they belong. This report was based on ... [more ▼]

Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large quasar groups (LQG) to which they belong. This report was based on observations made at optical wavelengths for two large quasar groups at redshift ~1.3. The correlation suggests that the spin axes of quasars preferentially align with their surrounding large-scale structure that is assumed to be traced by the LQGs. Here, we consider a large sample of LQGs built from the Sloan Digital Sky Survey DR7 quasar catalogue in the redshift range 1.0 -􀀀 1.8. For quasars embedded in this sample, we collected radio polarization measurements with the goal to study possible correlations between quasar polarization vectors and the major axis of their host LQGs. Assuming the radio polarization vector is perpendicular to the quasar spin axis, we found that the quasar spin axis is preferentially parallel to the LQG major axis inside LQGs that have at least 20 members. This result independently supports the observations at optical wavelengths. We additionally found that when the richness of an LQG decreases, the quasar spin axis becomes preferentially perpendicular to the LQG major axis and that no correlation is detected for quasar groups with fewer than 10 members. [less ▲]

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See detailCrossoads (avril 2016) - chaque mercredi de 18h à20h - rediffusion: samedis de 22h à minuit
Sacré, Robert ULg

Diverse speeche and writing (2016)

Programme radio hebdomadaire consacré aux musiques africaines-américaines streaming : www.equinoxefm.be - podcasts : www.mixcloud.com/robertsacre9

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See detailSemiotyka wizualna między tekstualnością a praktyką. Wokół wypowiadania
Dondero, Maria Giulia ULg

in Thiel-Jańczuk, Katarzyna (Ed.) Taktyki wizualne. Michel de Certeau i obrazy (2016)

Niniejszy artykuł stawia sobie dwa cele. Pierwszym jest porównanie semiotyki tekstu Algirdasa Juliena Greimasa i Louisa Marina z semiotyką praktyk Jacques’a Fontanille’a. Prace Michela de Certeau na temat ... [more ▼]

Niniejszy artykuł stawia sobie dwa cele. Pierwszym jest porównanie semiotyki tekstu Algirdasa Juliena Greimasa i Louisa Marina z semiotyką praktyk Jacques’a Fontanille’a. Prace Michela de Certeau na temat praktyk odbioru i użycia pozwolą wyjaśnić relację między pojęciem wypowiadania wypowiedzianego (énonciation énoncée) w paradygmacie tekstu i wypowiadania w akcie (énonciation en acte) w paradygmacie praktyk. Drugim celem jest problematyzacja pojęcia wypowiadania w ramach języka wizualnego. W oparciu o teorie i analizy Louisa Marina (Opacité en peinture – Nieprzejrzystość w malarstwie) ukazana zostanie użyteczność pojęcia wypowiadania wypowiedzianego w studiach nad obrazami i podjęta zostanie próba przetestowania znaczenia, które wypowiadaniu nadaje de Certeau (Wynaleźć codzienność 1. Sztuki działania) w ramach odbioru i interpretacji obrazów. [less ▲]

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