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See detailWildflower strips: a help for crop protection ?
Hatt, Séverin ULg; Uyttenbroeck, Roel ULg; Bodson, Bernard ULg et al

Poster (2014, March 05)

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See detailWildflower strips: a help for crop protection ?
Hatt, Séverin ULg; Uyttenbroeck, Roel ULg; Bodson, Bernard ULg et al

Conference (2014, March 05)

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See detailSome Interesting Sources of Plant Seed Oil
Paul, Aman ULg; Danthine, Sabine ULg; Blecker, Christophe ULg et al

Poster (2014, March 05)

There is a growing realization worldwide that biodiversity is fundamental to agricultural production and food security, as well as a valuable ingredient of environmental conservation. Flowering strips ... [more ▼]

There is a growing realization worldwide that biodiversity is fundamental to agricultural production and food security, as well as a valuable ingredient of environmental conservation. Flowering strips around the border of the crops serves as an important function to improve the biodiversity, besides this they play a major role in the ruminant nutrition and serve as a source of numerous beneficial compounds. It is well known that seeds store their food reserves for next generation mainly in the form of lipids; some of the seeds from these flowering strips could be an interesting source of lipids. These seed oils could play important role in food, pharmaceutical, cosmetics and other industries. The extraction of seed oil from four such plant species in Belgium namely Oregano (Origanum vulgare), Yellow Bedstraw (Galium verum), Common Self-heal (Prunella vulgaris) & Purple loosestrife (Lythrum salicaria) was carried out. Extraction was done by a cold extraction technique using chloroform/methanol in 2:1 ratio as solvent. Amount of oil extracted from Oregano, Yellow Bedstraw, Common Self-heal and Purple loosestrife was 22.58±0.03 %, 3.28±0.01 %, 14.84±0.12 % & 20.32±0.15 %. The fatty acid profiles of these four species were determined by gas chromatography (using methyl esters of their fatty acids); Oleic acid and Linoleic acid were found in all the four species, Gamma-linolenic acid was found in Purple loosestrife & Alpha-linolenic acid was found in Oregano and Common Self-heal plant species. Thermal behaviour of these four plant seed oils were analyzed using Differential Scanning Calorimetry (DSC), while some other physicochemical properties of the seed oils were also analyzed. These plant seed oils can be of great commercial importance. [less ▲]

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See detailDevelopment of a quantitative approach using surface-enhanced Raman chemical imaging: First step for the determination of an impurity in a pharmaceutical model
De Bleye, Charlotte ULg; Sacre, Pierre-Yves ULg; Dumont, Elodie ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2014), 90

This publication reports, for the first time, the development of a quantitative approach using surface-enhanced Raman chemical imaging (SER-CI). A pharmaceutical model presented as tablets based on ... [more ▼]

This publication reports, for the first time, the development of a quantitative approach using surface-enhanced Raman chemical imaging (SER-CI). A pharmaceutical model presented as tablets based on paracetamol, which is the most sold drug around the world, was used to develop this approach. 4-Aminophenol is the main impurity of paracetamol and is actively researched in pharmaceutical formulations because of its toxicity. As its concentration is generally very low (<0.1%, w/w), conventional Raman chemical imaging cannot be used. In this context, a SER-CI method was developed to quantify 4-aminophenol assessing a limit of quantification below its limit of specification of 1000 ppm. Citrate-reduced silver nanoparticles were used as SERS substrate and these nanoparticles were functionalized using 1-butanethiol. Different ways to cover the tablets surface by butanethiol-functionalized silver nanoparticles were tested and a homogeneity study of the silver nanoparticles covering was realized. This homogeneity study was performed in order to choose the best way to cover the surface of tablets by silver colloid. Afterwards, the optimization of the SER-CI approach was necessary and different spectral intensity normalizations were tested. Finally, a quantitative approach using SER-CI was developed enabling to quantify 4-aminophenol from 0.025% to 0.2% in paracetamol tablets. This quantitative approach was tested on two different series of tablets using different batches of silver nanoparticles. [less ▲]

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See detailUsing active and passive acoustics to assess O2 production of a Posidonia oceanica meadow
Felisberto, P; Zabel, F; Rodriguez, O et al

Poster (2014, March 04)

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See detailAn efficient standard error formula for the weighted likelihood estimator of ability
Magis, David ULg

Scientific conference (2014, March 04)

The weighted likelihood estimator (WLE; Warm, 1989) has become a very popular ability estimator in item response theory. It was developed to basically cancel the estimation bias of the maximum likelihood ... [more ▼]

The weighted likelihood estimator (WLE; Warm, 1989) has become a very popular ability estimator in item response theory. It was developed to basically cancel the estimation bias of the maximum likelihood estimator (MLE) with short tests. However, some uncertainty remains about its standard error formula. Warm (1989) established the asymptotic equivalence of the standard errors of both MLE and WLE, but there exists actually various practical formulas for the latter (Magis & Raîche, 2012; Nydick, 2013; Partchev, 2012; Warm, 2007), leading obviously to confusion. The purpose of this talk is to briefly sketch a general approach to derive a first-order approximation of the standard error of the WLE. Based on asymptotic adjustments of the law of large numbers and central limit theorem, a simple formula is derived. The efficiency of the latter is compared to aforementioned formulas by means of a simulation study under Rasch modeling. Preliminary results indicate that the derived formula has lower bias and RMSE than any other competing formula, especially with short tests. All formulas behave similarly with longer tests, as expected. [less ▲]

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See detailHistoire des musiques africaines-américaines; partim LE BLUES après 1945
Sacré, Robert ULg

Conference given outside the academic context (2014)

Après 1945: multiplication des petites compagnies de disques indépendantes- Electrification des instruments ; migrations noires Sud-Nord; maintien des styles ruraux (en léthargie) - développement des ... [more ▼]

Après 1945: multiplication des petites compagnies de disques indépendantes- Electrification des instruments ; migrations noires Sud-Nord; maintien des styles ruraux (en léthargie) - développement des styles urbains (Memphis, Chicago, Houston, New Orleans,...Louisiane, Californie,...) Désaffection des noirs US pour le blues; blues revival en Europe; le blues aujourd'hui [less ▲]

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See detailSmall impact of surrounding oceanic conditions on 2007–2012 Greenland Ice Sheet surface mass balance
Noel, Brice; Fettweis, Xavier ULg; van de Berg, W.J. et al

in Cryosphere Discussions (The) (2014), 8

During recent summers (2007–2012), several surface melt records were broken over the Greenland Ice Sheet (GrIS). The extreme summer melt resulted in part from a persistent negative phase of the North ... [more ▼]

During recent summers (2007–2012), several surface melt records were broken over the Greenland Ice Sheet (GrIS). The extreme summer melt resulted in part from a persistent negative phase of the North-Atlantic Oscillation (NAO), favouring warmer than normal conditions over the GrIS. In addition, it has been suggested that significant anomalies in sea ice cover (SIC) and sea surface temperature (SST) may partially explain recent anomalous GrIS surface melt. To assess the impact of 2007–2012 SIC and SST anomalies on GrIS surface mass balance (SMB), a set of sensitivity experiments was carried out with the regional climate model MAR. These simulations suggest that changes in SST and SIC in the seas surrounding Greenland do not significantly impact GrIS SMB, due to the katabatic winds blocking effect. These winds are strong enough to prevent oceanic near-surface air, influenced by SIC and SST variability, from penetrating far inland. Therefore, the ice sheet SMB response is restricted to coastal regions, where katabatic winds are weaker. However, anomalies in SIC and SST could have indirectly affected the surface melt by changing the general circulation in the North Atlantic region, favouring more frequent warm air advection to the GrIS. [less ▲]

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See detailHow do we perceive vocal pitch accuracy during singing?
Larrouy, Pauline ULg; Pfordresher, Peter Q

Conference (2014, March 03)

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See detailHubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
Knutson, Heather A.; Dragomir, Diana; Kreidberg, Laura et al

E-print/Working paper (2014)

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets ... [more ▼]

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's scanning mode to measure the wavelength-dependent transit depth in thirty individual bandpasses. Our averaged differential transmission spectrum has a median 1 sigma uncertainty of 19 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 17 sigma level. They are a good match for flat models corresponding to either a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of a mbar or higher. [less ▲]

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See detailThe yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase
Chesneau, O.; Meilland, A.; Chapellier, E. et al

in Astronomy and Astrophysics (2014), 563

Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer ... [more ▼]

Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer phase. Aims: We initiated long-term optical interferometry monitoring of the diameters of massive and unstable yellow hypergiants (YHG) with the goal of detecting both the long-term evolution of their radius and shorter term formation of a possible pseudo-photosphere related to proposed large mass-loss events. Methods: We observed HR 5171 A with AMBER/VLTI. We also examined archival photometric data in the visual and near-IR spanning more than 60 years, as well as sparse spectroscopic data. Results: HR 5171 Aexhibits a complex appearance. Our AMBER data reveal a surprisingly large star for a YHG R∗ = 1315 ± 260R⊙ (or ~6.1 AU) at the distance of 3.6 ± 0.5 kpc. The source is surrounded by an extended nebulosity, and these data also show a large level of asymmetry in the brightness distribution of the system, which we attribute to a newly discovered companion star located in front of the primary star. The companion's signature is also detected in the visual photometry, which indicates an orbital period of Porb = 1304 ± 6 d. Modeling the light curve with the NIGHTFALL program provides clear evidence that the system is a contact or possibly over-contact eclipsing binary. A total current system mass of 39^+40_-22 M⊙ and a high mass ratio q ≥ 10 is inferred for the system. Conclusions: The low-mass companion of HR 5171 is very close to the primary star that is embedded within its dense wind. Tight constraints on the inclination and vsini of the primary are lacking, which prevents us from determining its influence precisely on the mass-loss phenomenon, but the system is probably experiencing a wind Roche-Lobe overflow. Depending on the amount of angular momentum that can be transferred to the stellar envelope, HR 5171 A may become a fast-rotating B[e]/luminous blue variable/Wolf-Rayet star. In any case, HR 5171 A highlights the possible importance of binaries for interpreting the unstable YHGs and for massive star evolution in general. [less ▲]

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See detailImpacts of earthworms on soil components and dynamics. A review
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18

Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil ... [more ▼]

Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil fertility by participating to important processes in soil such as soil structure regulation and organic matter dynamics. Earthworms also modify the microbial communities through digestion, stimulation and dispersion in casts. Consequently, changes in the activities of earthworm communities, as a result of soil management practices, can also be used as indicators of soil fertility and quality. It is therefore important to understand how earthworm communities affect soil dynamics. This review adresses the current state of knowledge on earthworm’s impacts on soil structure and soil organic matter (carbon, nitrogen, and phosphorus) dynamics, with special emphasis on the effects of land management practices on earthworm communities. [less ▲]

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See detailLa «cospedalización» del que disiente
Ceballos Viro, Alvaro ULg

Article for general public (2014)

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See detailAn astronomical survey conducted in Belgium
Nazé, Yaël ULg; Fontaine, Sébastien ULg

in Physics Education (2014), 49

This article presents the results of the first survey conducted in Belgium about the interest and knowledge in astronomy. Two samples were studied, the public at large (667 questionnaires) and students ... [more ▼]

This article presents the results of the first survey conducted in Belgium about the interest and knowledge in astronomy. Two samples were studied, the public at large (667 questionnaires) and students (2589 questionnaires), but the results are generally similar in both samples. We evaluated people’s interest, main information source, and attitudes towards astronomy, as well as their supposed and actual knowledge of the subject. The main conclusion is that, despite a poor self-confidence, people do know the basic astronomical concepts. However, that knowledge is not deeply rooted, as reasoning questions show well-spread misconceptions and/or misunderstandings. [less ▲]

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See detailMode identification based on time-series spectrophotometry for the bright rapid sdB pulsator EC 01541-1409
Randall, Suzanna K; Fontaine, Gilles; Geier, Stephan et al

in Astronomy and Astrophysics (2014), 563

We present an analysis of time-resolved spectrophotometry gathered with FORS/VLT for the rapidly pulsating hot B subdwarf EC 01541-1409 with the aim of identifying the degree index ℓ of the larger ... [more ▼]

We present an analysis of time-resolved spectrophotometry gathered with FORS/VLT for the rapidly pulsating hot B subdwarf EC 01541-1409 with the aim of identifying the degree index ℓ of the larger amplitude modes. This mode identification can be extremely useful in detailed searches for viable asteroseismic models in parameter space, and can be crucial for testing the validity of a solution a posteriori. To achieve it, we exploit the ℓ-dependence of the monochromatic amplitude, phase, and velocity-to-amplitude ratio of a mode as a function of wavelength. We use the ℓ-sensitive phase lag between the flux perturbation and the radial velocity as an additional diagnostic tool. On this basis, we are able to unambiguously identify the dominant 140.5 s pulsation of our target as a radial mode, and the second-highest amplitude periodicity at 145.8 s as an ℓ = 2 mode. We further exploit the exceptionally high-sensitivity data that we gathered for the dominant mode to infer modal properties that are usually quite difficult to estimate in sdB pulsators, namely the physical values of the dimensionless radius, temperature, and surface gravity perturbations. [less ▲]

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See detailEmbodying the divine: herms in Greek vase-painting
Collard, Hélène ULg

Conference (2014, March)

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See detailThe Governance of Mixed Companies: Policy Implications for Local Governments
Marra, A; Cruz, N.F.; Marques, R.C. et al

in Annals of Public and Cooperative Economics (2014), 85(1), 1-164

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See detailLe redoublement en Fédération Wallonie-Bruxelles
Baye, Ariane ULg; Chenu, Florent ULg; Crahay, Marcel ULg et al

Learning material (2014)

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See detailJuan Gabriel Vásquez: découvrir pourquoi ce qui est obscur continue de l'être
Vanden Berghe, Kristine ULg

Article for general public (2014)

Detailed reference viewed: 14 (3 ULg)