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See detailGrassed Buffer Strips as Nitrate Diffuse Pollution Remediation Tools: Management Impact on the Denitrification Enzyme Activity
Cors, Marie; Tychon, Bernard ULg

in Water Science & Technology (2007), 55(3), 25-30

The management of grassed buffer strips proved to be an efficient remediation technique in controlling nitrogen losses to surface water. In south Belgium, agri-environmental policies have encouraged ... [more ▼]

The management of grassed buffer strips proved to be an efficient remediation technique in controlling nitrogen losses to surface water. In south Belgium, agri-environmental policies have encouraged farmers to seed buffer strips along rivers, in zones where the soil was previously devoted to agricultural production. We wanted to assess how important denitrification is in a buffer strip in comparison with a cropped field. The study investigated the denitrifiying enzyme activity (DEA) of two contiguous buffer strips with different management stories. The eastern part of the buffer strip was seeded in 1999. The western part of the buffer strip is a piece of crop field abandoned by the farmer 20 years ago and not managed for the last 10 years. This experimental study demonstrates that the denitrification enzyme activity in a riparian buffer strip is significantly higher than in the adjacent cropped field (3.67 and 2.12 mgNkg(-1)d(-1) respectively). The DEA was significantly different between the two buffer strips under comparison, assessing that the management of the buffer strips has a dominant effect on DEA. The old unmown buffer strip is potentially more efficient in the nitrate removal process than the 6-year-old seeded buffer strip. [less ▲]

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See detailGrasshoppers: Food Security & Nutrition
Paul, Aman ULg; Danthine, Sabine ULg; Frederich, Michel ULg et al

Scientific conference (2013, December)

Rising economies and rapid urbanization in developing countries, particularly in Asia, are creating shifts in the composition of global food demand, so it is necessary to explore new sources of food with ... [more ▼]

Rising economies and rapid urbanization in developing countries, particularly in Asia, are creating shifts in the composition of global food demand, so it is necessary to explore new sources of food with better nutritional profile. Among the alternative food that exists are the grasshoppers, about 80 species of which are consumed worldwide. Grasshoppers are not only rich source of proteins and lipids but also some important minor component like vitamins and minerals. Apart from being nutritionally superior to most conventional meats their production results in lower emission of greenhouse gases & ammonia, risk of zoonotic infections in humans is much lower, water requirement for production is much less and have higher feed conversion ratio. Edible species of grasshopper in Belgium were identified, attempts were made for the lab rearing of meadow grasshopper (Chorthippus parallelus) and fat as well as protein contents of meadow grasshopper (Chorthippus parallelus) & long winged conehead (Conocephalus discolor) were investigated. [less ▲]

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See detailThe grassland model intercomparison of the MACSUR (Modelling European Agriculture with Climate Change for Food Security) European knowledge hub
Ma, Shaoxiu; Acutis, Marco; Barcza, Zoltan et al

in Proceedings of the 7th International Congress on Environmental Modelling and Software (iEMSs) June 15-19, 2014, San Diego, California, USA (2014, June)

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See detailA Grassmann-Rayleigh quotient iteration for computing invariant subspaces
Absil, P.-A.; Mahony, R.; Sepulchre, Rodolphe ULg et al

in SIAM Review (2002), 44(1), 57-73

The classical Rayleigh quotient iteration (RQI) allows one to compute a one-dimensional invariant subspace of a symmetric matrix A. Here we propose a generalization of the RQl which computes a p ... [more ▼]

The classical Rayleigh quotient iteration (RQI) allows one to compute a one-dimensional invariant subspace of a symmetric matrix A. Here we propose a generalization of the RQl which computes a p-dimensional invariant subspace of A. Cubic convergence is preserved and the cost per iteration is low compared to other methods proposed in the literature. [less ▲]

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See detailLe grattoir-herminette dans le Groupe de Blicquy : approche expérimentale
Caspar, Jean-Paul; Burnez-Lanotte, Laurence; Rots, Veerle ULg

in INTERNEO (1998), 2

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See detailGraulichite-(Ce), a new arsenate mineral from the Stavelot Massif, Belgium
Hatert, Frédéric ULg; Pasero, Marco; Fransolet, André-Mathieu ULg et al

in European Journal of Mineralogy (2003), 15(4, JUL-AUG), 733-739

Graulichite-(Ce), ideally CeFe33+(AsO4)(2)(OH)(6), is a new mineral species from Hourt, Stavelot Massif, Belgium. It occurs in the most altered parts of a Devillian quartzite (Lower to Middle Cambrian ... [more ▼]

Graulichite-(Ce), ideally CeFe33+(AsO4)(2)(OH)(6), is a new mineral species from Hourt, Stavelot Massif, Belgium. It occurs in the most altered parts of a Devillian quartzite (Lower to Middle Cambrian), in close association with arsenopyrite, scorodite, mimetite, pharmacosiderite, and goethite. Graulichite-(Ce) forms 80 to 150 mum spherical aggregates of rhombohedral crystals, 50 to 80 mum length, which show the forms {10 (1) over bar2} and {10 (11) over bar}. The mineral is transparent and exhibits a light-green to brownish colour, with a resinous lustre. It is non-fluorescent and shows an irregular fracture, without any perceptible cleavage. The calculated density is 4.42 g/cm(3). Graulichite-(Ce) is uniaxial negative, with a mean refractive index close to 1.97(1) (lambda=590 nm), pleochroic from light green to yellowish. Electron microprobe analyses gave As2O5 31.20, P2O5 0.03, SO3 0.06, SiO2 0.03, Al2O3 3.09, Fe2O3 30.65, SrO 0.24, PbO 0.07, BaO 3.95, CaO 0.03, La2O3 2.26, Ce2O3 15.73, Nd2O3 2.08, H2O (calc.) 8.37, total 97.79 wt. %. The resulting empirical formula, calculated on the basis of 6 cations, is (Ce0.67Ba0.18La0.10Nd0.09Sr0.02)(Sigma1.06) (Fe2.683+Al0.42)(Sigma3.10)[(As(1.89)S(.001)square(0.10))(Sigma2.00)O-8][(OH)(5.57)(H2O)(0.43)](Sigma6.00). The single-crystal unit-cell parameters are a=7.288(2) and c=16.812(9) Angstrom, space group R (3) over barm. The seven strongest lines in the X-ray powder-diffraction pattern [d(in Angstrom)(I)(hkil)] are: 3.052(100)(11 (2) over bar3), 3.636(40)(11 (2) over bar0), 2.239(35)(10 (1) over bar7), 1.817(35)(22 (4) over bar0), 2.792(30)(0006), 5.906(25)(10 (1) over bar1), 1.968(25)(30 (3) over bar3). Graulichite-(Ce) is the iron analogue of arsenoflorencite-(Ce), and belongs to the crandallite mineral group, with the alunite-type structure. The crystal structure of graulichite-(Ce) has been refined, based on single-crystal X-ray diffraction data, to R=0.048. [less ▲]

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See detailGrave Soils Analysis by TD-GCxGC-TOFMS
Stefanuto, Pierre-Hugues ULg; Scotsmans, E. M.J.; Wilson, A. S. et al

Conference (2012, August)

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See detailLe Gravettien de Moldavie (30.000-23.000 BP)
Noiret, Pierre ULg

in Paléo. Revue d'Archéologie préhistorique (2007), 19

In Moldavia, three sequences serve as the basis for the chronological context for Gravettian (and Epigravettian) occupations. Two technological phases have been identified, showing independent development ... [more ▼]

In Moldavia, three sequences serve as the basis for the chronological context for Gravettian (and Epigravettian) occupations. Two technological phases have been identified, showing independent development, homogenous in both technological and typological attributes. The Gravettian is characterized by large retouched blades, followed by shouldered points (29,500-23,000 BP), succeeded by the Early Epigravettian (13,500-11,000 BP). [less ▲]

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See detailLe Gravettien du Nord-ouest de l'Europe
Otte, Marcel ULg; Noiret, Pierre ULg

in Paléo. Revue d'Archéologie préhistorique (2007), 19

Around 30 sites have yielded Gravettian assemblages in Belgium. Present fairly early (28,000 BP), the Gravettian appears in trios distinct facies. The earliest includes large pointed blades and tanged ... [more ▼]

Around 30 sites have yielded Gravettian assemblages in Belgium. Present fairly early (28,000 BP), the Gravettian appears in trios distinct facies. The earliest includes large pointed blades and tanged tools; the most recent is marked by microlithic backed elements (truncated elements, microgravettes). These facies likely correspond to regional groups, for which the first can also be found fairly easily in neighbouring regions (England, Wales and northern France). In Rhenania, some 15 sites correspond to two facies (with Font Robert points and with microgravettes), similar but not identical to the Belgian facies. [less ▲]

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See detailGraviers de la Meuse (alluvions modernes et anciennes) en Wallonie
Dassargues, Alain ULg; Wildemeersch, Samuel ULg; Rentier, Céline

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailGravimetric exploration applied to the detection of faults in the area of Mol - Turnhout (Belgium)
Dassargues, Alain ULg; Halleux, Lucien ULg; Monjoie, Albéric ULg et al

in Annales de la Société Géologique de Belgique (1989), 112(2), 431-441

A gravimetrical exploration has been realized in the area of Mol and Turnhout (province of Antwerp, Belgium) to localize steep dipping faults in the Paleozoic bed rock and the Meso- to Cenozoic overburden ... [more ▼]

A gravimetrical exploration has been realized in the area of Mol and Turnhout (province of Antwerp, Belgium) to localize steep dipping faults in the Paleozoic bed rock and the Meso- to Cenozoic overburden. With a 600 to 1000m thick overburden consisting of sand and clay, 10m high steps in the bed rock result in significant gravimetrical anomalies. The interpretation is based upon comparison with theoretical anomalies computed for various density contrasts and depths. After the classical corrections, the Bouguer anomaly has been smoothed and horizontal derivatives computed to reduce the effect of shallow heterogeneities and regional gradients. The results confirm the presence of several faults already detected by other methods and enable a more accurate positionning. [less ▲]

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See detailGravitational lens simulator : a didactical experiment
Surdej, Jean ULg; Pospieszalska-Surdej, Anna ULg

Learning material (2007)

A large concentration of mass may act as a kind of lens, called a gravitational lens. A simple educational experience makes it possible to simulate such effects, see also (http://www.aeos.ulg.ac.be/GL ... [more ▼]

A large concentration of mass may act as a kind of lens, called a gravitational lens. A simple educational experience makes it possible to simulate such effects, see also (http://www.aeos.ulg.ac.be/GL/didactics.php). [less ▲]

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See detailGravitational lens studies with a LMT
Surdej, Jean ULg; Claeskens, Jean-François ULg

in Ferrari, M. (Ed.) Proceedings of the International workshop “Science with Liquid Mirror Telescopes” (1998)

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See detailGravitational lenses
Refsdal, S.; Surdej, Jean ULg

in Reports on Progress in Physics (1994), 57

According to Einstein's general theory of relativity, a gravitational field bends electromagnetic waves in much the same way as low atmospheric air layers curve the trajectory of a propagating light ray ... [more ▼]

According to Einstein's general theory of relativity, a gravitational field bends electromagnetic waves in much the same way as low atmospheric air layers curve the trajectory of a propagating light ray. Large mass concentrations in the universe can thereby act as a type of lens, a gravitational lens. After briefly reviewing the history of gravitational lensing since the early thoughts of Newton in 1704 until the serendipitous discovery of the first gravitational lens system in 1979, the authors recall the basic principles of atmospheric and gravitational lensing. They then describe a simple optical gravitational lens experiment which has the merit of accounting for all types of image configuration observed among currently known gravitational lens systems. Various types of gravitational lens models are described in detail as well as the resulting image properties of a distant source. An updated list as well as colour illustrations of the best known examples of multiply imaged quasars, radio rings and giant luminous arcs and arclets are presented. Some of these observations are discussed in detail. Finally, the authors show how it is possible to use gravitational lensing as a cosmological and astrophysical tool, the most interesting applications being the determination of the Hubble parameter H[SUB]0[/SUB], the mass of very distant lensing galaxies as well as the distribution of luminous and dark matter in the universe. They also show how to determine the size and structure of distant quasars from observations of micro-lensing effects. [less ▲]

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See detailGravitational Lenses Among Highly Luminous Quasars: Large Optical Surveys
Claeskens, Jean-François ULg; Jaunsen, A. O.; Surdej, Jean ULg

in Kochanek, C. S.; Hewitt, Jacqueline N (Eds.) Astrophysical applications of gravitational lensing: proceedings of the 173rd Symposium of the International Astronomical Union (1996)

Not Available

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See detailGravitational Lenses and Damped Ly-alpha Systems
Smette, A.; Claeskens, Jean-François ULg; Surdej, Jean ULg

in Kochanek, C. S.; Hewitt, Jacqueline N (Eds.) Astrophysical applications of gravitational lensing: proceedings of the 173rd Symposium of the International Astronomical Union (1996)

Not Available

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See detail'Gravitational lenses in the Universe', The proceedings of the 31st Liège International Astrophysical Colloquium
Surdej, Jean ULg; Fraipont-Caro, D.; Gosset, Eric ULg et al

Book published by Université de Liège (1993)

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See detailGravitational lenses: observations
Surdej, Jean ULg

in invited talk delivered during the first general meeting of the European Astronomical Society "The impact of space research on astronomy" (1992)

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