Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
See detailLes Poissons de la Marchette (Eau d'Heure)
Philippart, Jean-Claude ULg; Rimbaud, Gilles ULg

Conference given outside the academic context (2011)

Après un bref rappel des principales caractéristiques hydroécologiques de la Marchette et du R. d’Heure, est présentée une analyse des résultats de deux pêches à l’électricité exécutées pour le compte du ... [more ▼]

Après un bref rappel des principales caractéristiques hydroécologiques de la Marchette et du R. d’Heure, est présentée une analyse des résultats de deux pêches à l’électricité exécutées pour le compte du SPW-DGARNE-DEMNA en juin 2010 dans la Marchette aval, dans le camp militaire. Ces résultats sont confrontés à ceux obtenus lors d’études réalisées par l’ULg en 1976-1979. Les captures en 2010 sur une distance de 392 m et une superficie de 0,2211 ha s’élèvent à 3 949 poissons et 16,625 kg (densité de 17 860 ind./ha et 75,2 kg/ha) appartenant à 17 espèces indigènes. Près de 94,2 % des captures en nombre (58,8 % en biomasse) sont formés par 3 espèces (vairon, loche franche et goujon) de petite taille (< 18 cm) et assez peu exigeantes pour la qualité de l’eau et du milieu physique (espèces ubiquistes et polluorésistantes). La présence de l’épinoche en effectif assez important reflète un état de pollution chronique. Les poissons indicateurs d’un meilleur niveau de qualité de l’eau sont représentés mais en faibles effectifs et biomasses par des cyprins d’eau vive (chevaine, vandoise, ablette spirlin ainsi que barbeau et hotu moins nombreux), par la truite commune de rivière toutefois très rare et provenant surtout de repeuplements et, fait encourageant, par deux espèces Natura 2000, le chabot et la petite lamproie. Il faut aussi signaler la capture de carnassiers représentés en faible effectif par le brochet, la perche fluviatile et l’anguille européenne. L’interprétation de ces résultats nécessite de distinguer les trois milieux bien différenciés que sont le R. d’Heure (RE) de bonne qualité écologique, la Marchette en amont du RE fort dégradée (= masse d’eau fortement modifiée selon la Directive Cadre sur l’Eau) et la Marchette en aval du RE de qualité moyenne (effet du mélange). Il faut aussi tenir compte du fait que les cours d’eau famenniens sont naturellement peu favorables (faible pente + courant lent + substrat faiblement caillouteux) au développement des Salmonidés (truite, ombre) et des autres poissons pondeurs sur gravier (barbeau, chabot). Enfin, les repeuplements (diversité et intensité) en poissons d’élevage influencent aussi la composition de la communauté des poissons. Dans la Marchette aval étudiée en 2010, on trouve une bonne diversité piscicole (17 espèces) mais la communauté d’une ‘zone à barbeau’ présente d’importants déséquilibres structurels résultant de la pollution de l’eau venant de l’amont (Indice biotique Invertébrés benthiques souvent mauvais=8/20 en 1996-2008). Les Indices de qualité de l’eau d’après les poissons varient de ‘médiocre’ à ‘moyen/bon’ selon les méthodes et les lieux. La biomasse piscicole totale est nettement (3-4 fois) inférieure à ce qu’elle devrait être dans ce type de rivière en l’absence de pollution. En matière de gestion durable de la qualité écologique et piscicole des milieux quelques propositions générales peuvent être formulées : * Accorder une priorité absolue à l’amélioration de la qualité de l’eau par des actions sur la Marchette en amont du R. d’Heure (contrôle des rejets, épuration) sans négliger le R. d’Heure lui-même * Améliorer l’habitat physique des poissons (notamment frayères et nurseries pour le brochet) et développer des opérations appropriées de repeuplement (truite fario, cyprins d’eau vive, civelles). * Préserver et, si nécessaire, rétablir la libre circulation des poissons en remontée dans le bassin Marchette/R. d’Heure et encadrer les éventuels projets hydro-électriques [less ▲]

Detailed reference viewed: 82 (9 ULg)
See detailPoissons migrateurs : objectif Meuse.
Hanon, L.; Philippart, Jean-Claude ULg; Poncin, Pascal ULg

Article for general public (2007)

Detailed reference viewed: 30 (2 ULg)
See detailPolar lipids analysis from the MFGM by SPE and HPLC-ELSD
Bodson, Pascal ULg; Danthine, Sabine ULg; Blecker, Christophe ULg et al

Poster (2008, January 23)

Detailed reference viewed: 30 (9 ULg)
Full Text
See detailPolar Microoganisms and Biotechnology
Feller, Georges ULg; Margesin, Rosa

in Miller, R. V.; Whyte, L. G. (Eds.) Polar Microbiology: Life in a Deep Freeze (2012)

Detailed reference viewed: 77 (23 ULg)
Peer Reviewed
See detailPolar overdominance at the ovine callipyge locus
Cockett, N.; Jackson, S.; Shaw, T. et al

in Science (1996), 273(5272), 236-238

An inheritable muscular hypertrophy was recently described in sheep and shown to be determined by the callipyge gene mapped to ovine chromosome 18. Here, the callipyge phenotype was found to be ... [more ▼]

An inheritable muscular hypertrophy was recently described in sheep and shown to be determined by the callipyge gene mapped to ovine chromosome 18. Here, the callipyge phenotype was found to be characterized by a nonmendelian inheritance pattern, referred to as polar overdominance, where only heterozygous individuals having inherited the callipyge mutation from their sire express the phenotype. The possible role of parental imprinting in the determinism of polar overdominance is envisaged. [less ▲]

Detailed reference viewed: 19 (7 ULg)
Full Text
Peer Reviewed
See detailPolar stratospheric descent of NOy and CO and Arctic denitrification during winter 1992-1993
Rinsland, C. P.; Salawitch, R. J.; Gunson, M. R. et al

in Journal Of Geophysical Research. Atmospheres (1999), 104(D1), 1847-1861

Observations inside the November 1994 Antarctic stratospheric vortex and inside the April 1993 remnant Arctic stratospheric vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform ... [more ▼]

Observations inside the November 1994 Antarctic stratospheric vortex and inside the April 1993 remnant Arctic stratospheric vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer are reported. In both instances, elevated volume mixing ratios (VMRs) of carbon monoxide (CO) were measured. A peak Antarctic CO VMR of 60 ppbv (where 1 ppbv = 10(-9) per unit volume) was measured at a potential temperature (Theta) of 710 K (similar to 27 km), about 1 km below the altitude of a pocket of elevated NOy (total reactive nitrogen) at a deep minimum in N2O (<5 ppbv). The Arctic observations also show a region of elevated vortex CO with a peak VMR of 90 ppbv at 630-670 K (similar to 25 km) but no corresponding enhancement in NOy, perhaps because of stronger dynamical activity in the northern hemisphere polar winter and/or interannual variability in the production of mesospheric NO. By comparing vortex and extravortex observations of NOy obtained at the same N2O VMR, Arctic vortex denitrification of 5 +/- 2 ppbv at 470 K (similar to 18 km) is inferred. We show that our conclusion of substantial Arctic winter 1992-1993 denitrification is robust by comparing our extravortex observations with previous polar measurements obtained over a wide range of winter conditions. Correlations of NOy with N2O measured at the same Theta by ATMOS in the Arctic vortex and at midlatitudes on board the ER-2 aircraft several weeks later lie along the same mixing line. The result demonstrates the consistency of the two data sets and confirms that the ER-2 sampled fragments of the denitrified Arctic vortex following its breakup, An analysis of the ATMOS Arctic measurements of total hydrogen shows no evidence for significant dehydration inside the vortex. [less ▲]

Detailed reference viewed: 15 (3 ULg)
Full Text
Peer Reviewed
See detailA polar+equatorial wind model for broad absorption line quasars. I. Fitting the C IV BAL profiles
Borguet, Benoît ULg; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (2010), 515

Context. Despite all the studies, the geometry of the wind at the origin of the blueshifted broad absorption lines (BAL) observed in nearly 20% of quasars still remains a matter of debate. <BR /> Aims: We ... [more ▼]

Context. Despite all the studies, the geometry of the wind at the origin of the blueshifted broad absorption lines (BAL) observed in nearly 20% of quasars still remains a matter of debate. <BR /> Aims: We want to see if a two-component polar+equatorial wind geometry can reproduce the typical BAL profiles observed in these objects. <BR /> Methods: We built a Monte Carlo radiative transfer code (called MCRT) to simulate the line profiles formed in a polar+equatorial wind in which the photons, emitted from a spherically symmetric core are resonantly scattered. Our goal is to reproduce typical C iv line profiles observed in BAL quasars and to identify the parameters governing the line profiles. <BR /> Results: The two-component wind model appears to be efficient in reproducing the BAL profiles from the P Cygni-type profiles to the more complex ones. Some profiles can also be reproduced with a pole-on view. Our simulations provide evidence of a high-velocity rotation of the wind around the polar axis in BAL quasars with non P Cygni-type line profiles. [less ▲]

Detailed reference viewed: 8 (5 ULg)
Full Text
See detailPolar-interferometry: what can be learnt from the IOTA/IONIC experiment
Le Bouquin, Jean-Baptiste; Rousselet-Perraut, Karine; Berger, Jean-Philippe et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late ... [more ▼]

We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late-type giants. Optical modeling of the array and dedicated laboratory measures allowed us to confirm the good accuracy obtained on the calibrated polarized visibilities and closure phases. However, no evidences for polarimetric features at high angular resolution have been detected. The simulations and the results presented here open several perspectives for polar-interferometry, especially in the context of fibered, single-mode combiners. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailPolarimetric Standard Stars Observed with FORS1 at ESO-VLT
Mason, E.; Bagnulo, S.; Szeifert, T. et al

in ASP Conference Series (2005, December 01), 343

A Paranal Observatory project aims to analyze all the polarimetric standard stars in use at FORS1 to both check they have a constant polarization signal and measure the instrumental polarization ... [more ▼]

A Paranal Observatory project aims to analyze all the polarimetric standard stars in use at FORS1 to both check they have a constant polarization signal and measure the instrumental polarization. Preliminary results for 3 standards in the FORS1 calibration plans are presented. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailPolarimetry and Spectropolarimetry of a Sample of Broad Absorption Line Quasars
Lamy, H.; Hutsemekers, Damien ULg

in Structure and Kinematics of Quasar Broad Line Regions. ASPC 175 (1999)

Optical polarimetric and spectropolarimetric observations of a sample of broad absorption line QSOs were recently carried out with the 3.6m telescope and EFOSC1 in La Silla, Chile. Some preliminary ... [more ▼]

Optical polarimetric and spectropolarimetric observations of a sample of broad absorption line QSOs were recently carried out with the 3.6m telescope and EFOSC1 in La Silla, Chile. Some preliminary results are presented here with emphasis on interesting correlations between polarization and other quantities characterizing the optical spectra of the objects. [less ▲]

Detailed reference viewed: 16 (0 ULg)
Full Text
Peer Reviewed
See detailPolarised light induced birefringence in azo dye doped polymer: a new model and polarised holographic experiments
Blanche, Pierre-Alexandre ULg; Lemaire, P. C.; Maertens, Christophe et al

in Optics Communications (1997), 139(1-3), 92-98

The photoinduced birefringence of azo dye DMNPAA (2,5-dimelthyl-4-(p-nitrophenylazo)anisole) in PVK (Poly(N-vinylcarbazole)) thin film is reported. A two-layer model of the film is proposed to take into ... [more ▼]

The photoinduced birefringence of azo dye DMNPAA (2,5-dimelthyl-4-(p-nitrophenylazo)anisole) in PVK (Poly(N-vinylcarbazole)) thin film is reported. A two-layer model of the film is proposed to take into account the different results obtained in photoinduced birefringence experiments. According to this model, the sample exhibits intrinsic birefringence but the absorbed light can induce orientation of the optically active molecules contained in the first layer of the film, lending to photoinduced birefringence. Holographic experiments have been carried out in this media with recording at 514 nm and readout at 633 nm. Diffraction efficiency versus polarisation shows that these polymers can record polarisation states as well as intensity patterns. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
Peer Reviewed
See detailA polarity reversal in the large-scale magnetic field of the rapidly rotating sun HD 190771
Petit, Pascal; Dintrans, Boris; Morgenthaler, Audrey et al

in Astronomy and Astrophysics (2009), 508

Aims. We investigate the long-term evolution of the large-scale photospheric magnetic field geometry of the solar-type star HD 190771. With fundamental parameters very close to those of the Sun except for ... [more ▼]

Aims. We investigate the long-term evolution of the large-scale photospheric magnetic field geometry of the solar-type star HD 190771. With fundamental parameters very close to those of the Sun except for a shorter rotation period of 8.8 d, HD 190771 provides us with a first insight into the specific impact of the rotation rate in the dynamo generation of magnetic fields in 1 M_sun stars. Methods: We use circularly polarized, high-resolution spectra obtained with the NARVAL spectropolarimeter (Observatoire du Pic du Midi, France) and compute cross-correlation line profiles with high signal-to-noise ratio to detect polarized Zeeman signatures. From three phase-resolved data sets collected during the summers of 2007, 2008, and 2009, we model the large-scale photospheric magnetic field of the star by means of Zeeman-Doppler imaging and follow its temporal evolution. Results: The comparison of the magnetic maps shows that a polarity reversal of the axisymmetric component of the large-scale magnetic field occurred between 2007 and 2008, this evolution being observed in both the poloidal and toroidal magnetic components. Between 2008 and 2009, another type of global evolution occured, characterized by a sharp decrease of the fraction of magnetic energy stored in the toroidal component. These changes were not accompanied by significant evolution in the total photospheric magnetic energy. Using our spectra to perform radial velocity measurements, we also detect a very low-mass stellar companion to HD 190771. [less ▲]

Detailed reference viewed: 10 (0 ULg)
See detailPolarization and Intensity Effects on the Beam-Foil-Laser Interaction
Bastin, Thierry ULg; Krastev, T.; Garnir, Henri-Pierre ULg et al

Poster (1995)

Detailed reference viewed: 3 (2 ULg)
Full Text
Peer Reviewed
See detailPolarization correction of the electrostatic potential for aromatic-compounds - Study of the nucleophilic-attack
Dive, Georges ULg; Dehareng, Dominique ULg

in International Journal of Quantum Chemistry (1993), 46(1), 127-136

The electrostatic potential (EP) and the polarization correction (PL) on the EP were calculated for four aromatic compounds: benzene, chlorobenzene, phenol, and benzoic amide, at the ab initio SCF level ... [more ▼]

The electrostatic potential (EP) and the polarization correction (PL) on the EP were calculated for four aromatic compounds: benzene, chlorobenzene, phenol, and benzoic amide, at the ab initio SCF level within two basis sets: 6-31G** and MINI-1. One calculation was performed using the polarized MINI-1** basis set. The quantity total interaction energy (TEH) defined as -EP + PL can be used as an indicator of the nucleophilic attack preferential position. By reference to 6-31G**, MINI-I provides very satisfactory results. Moreover, the MINI-1** results are very similar to the MINI-I ones. It appears that -EP does not provide a reliable tool to study the nucleophilic attack susceptibility, whereas TEH seems to be very well adapted for this kind of approach. [less ▲]

Detailed reference viewed: 14 (4 ULg)
Full Text
Peer Reviewed
See detailPolarization correction to the electrostatic potential at the CNDO and the ab initio level. Influence of the basis set expansion
Dehareng, Dominique ULg; Dive, Georges ULg; Ghuysen, Jean-Marie ULg

in Theoretica Chimica Acta (1991), 79(2), 141-152

The influence of the basis set on the electrostatic potential corrected for polarization has been studied for H2S, CH3SH and COHCH2SH. The position and deepness of the minima and the height of the barrier ... [more ▼]

The influence of the basis set on the electrostatic potential corrected for polarization has been studied for H2S, CH3SH and COHCH2SH. The position and deepness of the minima and the height of the barrier between symmetric minima is discussed at both the deorthogonalized CNDO/2 and ab initio levels within STO-3G, 3-21G, 4-31G, 6-31G and 6-311G basis sets. The calculation of the electrostatic potential and corrected one using CNDO deorthogonalized coefficients including 3d orbitals has been applied at the first time on sulfur-containing molecules. The influence of polarization and diffuse functions has also been analysed and the incidence of the polarization correction on the relative proton affinity in NH2(CH2)3NHCH3 and in the adenine molecule has been investigated at the CNDO and ab initio levels. At both levels, the relative proton affinity of several basic sites in the same molecule can be qualitatively expressed without inclusion of the polarization correction except in the case of substituted amines. [less ▲]

Detailed reference viewed: 16 (2 ULg)
Peer Reviewed
See detailPolarization dependence of the exchange energy
Gonze, X.; Ghosez, Philippe ULg; Godby, R. W.

in Physical Review Letters (1997), 78(10), 2029-2029

Detailed reference viewed: 1 (0 ULg)
Full Text
See detailThe Polarization Evolution of the Optical Afterglow of GRB 030329
Greiner, J.; Klose, S.; Reinsch, K. et al

in GAMMA-RAY BURSTS: 30 YEARS OF DISCOVERY (2004, September 01)

We report 31 polarimetric observations of the afterglow of GRB 030329 with high signal-to-noise and high sampling frequency. The data imply that the afterglow magnetic field has small coherence length and ... [more ▼]

We report 31 polarimetric observations of the afterglow of GRB 030329 with high signal-to-noise and high sampling frequency. The data imply that the afterglow magnetic field has small coherence length and is mostly random, probably generated by turbulence. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailPolarization holography for vortex retarders recording
Piron, Pierre ULg; Blain, Pascal ULg; Mawet, Dimitri et al

in Applied Optics (2013), 52(28), 7040-7048

We present an original static recording method for vortex retarders (VRs) made from liquid crystal polymers (LCPs) using the superimposition of several polarized beams. VRs are birefringent plates ... [more ▼]

We present an original static recording method for vortex retarders (VRs) made from liquid crystal polymers (LCPs) using the superimposition of several polarized beams. VRs are birefringent plates characterized by a rotation of their fast axis about their center. The new method is based on polarization holography and photo-orientable LCP. Combining several polarized beams induces the polarization patterns required for the recording process of VRs without mechanical action. A mathematical description of the method, the outcomes of the numerical simulations, and the first experimental results are presented. [less ▲]

Detailed reference viewed: 33 (8 ULg)
Full Text
Peer Reviewed
See detailPolarization holography reveals the nature of the grating in polymers containing azo-dye
Blanche, Pierre-Alexandre ULg; Lemaire, P. C.; Maertens, Christophe et al

in Optics Communications (2000), 185(1-3), 1-12

To study the origin of reversible holographic recording in three polymers containing the same azo-dye, we have measured the diffraction efficiency and analyzed the gratings characteristics for various ... [more ▼]

To study the origin of reversible holographic recording in three polymers containing the same azo-dye, we have measured the diffraction efficiency and analyzed the gratings characteristics for various writing beams polarizations. The amplitude of the holographic grating, as well as the ratio between index and absorption modulations, have been investigated by gratings shifting. The total amount of diffracted power and the diffraction efficiency versus the reading beam polarization has been measured by non-degenerated four waves mixing. These experiments have revealed that the molecular mechanisms of holographic recording in the studied compounds are different. The photoinduced orientation of the chromophores is predominant for C6-C11-DMNPAA; so, in C11-C6-DMNPAA (DMNPAA: 2,5-dimethyl-4-(p-nitrophenylazo)anisole), the refractive index variation comes from the presence of both trans and cis populations generated by photoisomerization. The behavior of the PVK:DMNPAA is included between these extreme cases since both phenomena act. [less ▲]

Detailed reference viewed: 32 (1 ULg)