References of "1998"
     in
Bookmark and Share    
See detailDépopulation de la Ville de Liège et diffusion périurbaine : quels processus pour quelles pistes de solutions ?
Halleux, Jean-Marie ULg

Conference given outside the academic context (1998)

Detailed reference viewed: 13 (0 ULg)
Peer Reviewed
See detailDecreased Protein Levels of the C-Cbl Protooncogene in Murine Aids
Trebak, Mohamed; Lambert, Charles A; Rahmouni, Souad ULg et al

in Cellular Immunology (1998), 188(2), 151-7

Murine acquired immunodeficiency syndrome (MAIDS) can be viewed as a lymphoproliferative disease which involves B cells as well as T cells from spleen and lymph nodes while thymus and Peyer's patches do ... [more ▼]

Murine acquired immunodeficiency syndrome (MAIDS) can be viewed as a lymphoproliferative disease which involves B cells as well as T cells from spleen and lymph nodes while thymus and Peyer's patches do not participate in the process. The 120-kDa protooncogene product c-Cbl was initially cloned from the murine Cas NS-1 B cell lymphoma. It is a main target of immunoreceptor (TCR and BCR)-mediated protein tyrosine kinase activity. Moreover, recent data suggest that c-Cbl might play a crucial role in the regulation of cell proliferation through regulation of GTP-binding proteins. Therefore, the involvement of c-Cbl was evaluated in the lymphoproliferative disease induced by the MAIDS virus. The expression of the c-Cbl protein was dramatically reduced in the lymph node of infected mice while it remained normal in the thymus. In contrast, the expression of actin, TCR-zeta chain, ZAP-70, and p59(fyn) remained similar in controls and infected mice. Identical results were obtained with sorted B cells and T cells. Surprisingly, a B cell lymphoma line derived from late stage MAIDS mice displayed a normal level of c-Cbl. [less ▲]

Detailed reference viewed: 29 (3 ULg)
Full Text
Peer Reviewed
See detailSimultaneous Determination of Methylphenobarbital Enantiomers and Phenobarbital in Human Plasma by on-Line Coupling of an Achiral Precolumn to a Chiral Liquid Chromatographic Column
Ceccato, Attilio ULg; Boulanger, Bruno ULg; Chiap, Patrice ULg et al

in Journal of Chromatography. A (1998), 819(1-2), 143-53

A fully automated liquid chromatographic (LC) method for the simultaneous determination of methylphenobarbital enantiomers and phenobarbital in human plasma has been developed. The method is based on the ... [more ▼]

A fully automated liquid chromatographic (LC) method for the simultaneous determination of methylphenobarbital enantiomers and phenobarbital in human plasma has been developed. The method is based on the use of a precolumn packed with an internal-surface reversed-phase packing material (LiChrospher ADS) for sample clean-up coupled to LC analysis on a cellulose tris(4-methylbenzoate) based chiral stationary phase (Chiralcel OJ-R). A 100-microliter plasma sample was injected directly on the precolumn packed with LiChrospher RP-18 ADS using a mixture of pH 5.0 phosphate buffer-methanol (97:3, v/v) as washing liquid. The analytes were then eluted in the back-flush mode with the LC mobile phase. The enantiomeric separation of methylphenobarbital was achieved on Chiralcel OJ-R). The retention times were modelled using a D-optimal design with ten experimental points in order to optimise the LC mobile phase for the separation of phenobarbital from the enantiomers of mephobarbital. The factors selected were the acetonitrile content, the pH and the sodium perchlorate concentration in the mobile phase. A Derringer's desirability function was used to find an optimal and robust solution within the experimental domain. The mobile phase selected consisted of a mixture of pH 7.0 phosphate buffer-acetonitrile (60:40, v/v). The elution profiles of phenobarbital, methylphenobarbital and blank plasma samples on the precolumn and the time needed for analyte transfer from the precolumn to the analytical column were then determined. Finally, the method developed was validated. [less ▲]

Detailed reference viewed: 21 (1 ULg)
See detailSimulations calibrées sur des essais de traçages en vue de la détermination de zones de protection
Dassargues, Alain ULg

Scientific conference (1998, September 11)

Detailed reference viewed: 4 (0 ULg)
Full Text
Peer Reviewed
See detailL'immersion linguistique en milieu scolaire : De l'utilité de l'apprentissage précoce des langues étrangères
Comblain, Annick ULg

in Comblain, Annick (Ed.) Proceedings des Entretiens de Bichat partim Ortophonie (1998, September 11)

Il est superflu, aujourd’hui, d’insister sur la nécessité tant individuelle que culturelle mais surtout économique de connaître une ou plusieurs langues étrangères. Face à cet état de fait, il est ... [more ▼]

Il est superflu, aujourd’hui, d’insister sur la nécessité tant individuelle que culturelle mais surtout économique de connaître une ou plusieurs langues étrangères. Face à cet état de fait, il est souhaitable de fournir aux jeunes enfants les meilleures opportunités d’apprendre une seconde langue de manière intensive dans leur cursus scolaire. Les préoccupations scientifiques sur les divers aspects du bilinguisme ne sont pas neuves. Depuis plusieurs décennies, les psychologues, les éducateurs et les sociologues s’interrogent sur les effets individuels et sociaux de la pratique de plusieurs langues. Ce n’est cependant que récemment qu’une réflexion sérieuse sur les méthodes et les contextes de cet apprentissage linguistique est née. La raison en est, sans nul doute, le sentiment généralement partagé de l’inefficacité de l’apprentissage traditionnel des langues. Sur le modèle de ce qui se fait au Canada depuis plus d'un quart de siècle, la Belgique est un des rares pays a avoir, du moins à titre expérimental, introduit l’immersion dans son système scolaire et ce depuis 10 ans maintenant. Les avantages de l’enseignement immersif sont évidents : précocité et intensité d’exposition à la langue cible, caractère motivant et fonctionnel de la pratique linguistique. Les inconvénients, avec des enfants normaux sont nuls ainsi que l’attestent un grand nombre d'études canadiennes. La pratique immersive n’est un embarras ni pour le développement des capacités et des connaissances en langue maternelle, ni pour la maîtrise des matières inscrites au programme scolaire . Au terme de la scolarité secondaire, les enfants immergés présentent d’impressionnantes capacités discursives en langue seconde tant d’un point de vue réceptif que productif. Ces capacités discursives, bien qu’encore inférieures à celle de locuteurs natifs du même âge, sont très nettement supérieures à celles des enfants ayant suivi un enseignement traditionnel. Les résultats obtenus par la méthode immersive semblent donc de nature à améliorer de manière considérable les capacités linguistiques des enfants. Un certain nombre de recherches sont cependant encore nécessaires afin de préciser les modalités optimales de l’apprentissage des langues étrangères dans les contextes éducatifs. [less ▲]

Detailed reference viewed: 521 (54 ULg)
See detailLe froment d'hiver
Couvreur, Luc; Bodson, Bernard ULg; Herman, Jean-Luc et al

in Fumure et protection phytosanitaire des céréales: Informations avant les semis des céréales (1998, September 10)

Detailed reference viewed: 5 (0 ULg)
See detailEscourgeon et Orge d'hiver fourragère
Bodson, Bernard ULg; Herman, Jean-Luc; Monfort, Bruno et al

in Fumure et protection phytosanitaire des céréales: Informations avant les semis des céréales (1998, September 10)

Detailed reference viewed: 8 (0 ULg)
Full Text
See detailCloches et carillons dans les Principautés de Liège et Stavelot-Malmedy: problèmes et voies de recherche
Marganne, Marie-Hélène ULg; Mélard, Marc

Conference given outside the academic context (1998)

Detailed reference viewed: 22 (6 ULg)
See detailLe traitement des infections artérielles. Apport de l’allogreffe
LAVIGNE, Jean-Paul ULg

Doctoral thesis (1998)

Detailed reference viewed: 17 (0 ULg)
See detailObservation of short and long timescale variability of the jovian UV aurora
Grodent, Denis ULg; Gérard, Jean-Claude ULg; Dols, V. et al

in Bulletin of the American Astronomical Society (1998, September 01)

Three sets of Hubble Space Telescope far-ultraviolet images of Jupiter's North pole aurora have been obtained with the Wide Field and Planetary Camera 2 in June 1996, May 1997 and August 1997. The ... [more ▼]

Three sets of Hubble Space Telescope far-ultraviolet images of Jupiter's North pole aurora have been obtained with the Wide Field and Planetary Camera 2 in June 1996, May 1997 and August 1997. The exposure time was limited to 160 seconds in order to reveal short timescale auroral features that are normally averaged during longer exposures and blurred by the rapid jovian rotation. The 3 sets of images show the aurora in a comparable (quiet) activity level, exhibiting long term persistent features such as : (i) a stable thin morning arc, (ii) a morning-afternoon emission dichotomy, (iii) a minimum of low latitude emission around CML=175 deg, (iv) bright localized afternoon structures. The equatorward boundary of the arc closely follows but is not coincident with the footprint of the 20 RJ magnetic field line given by the VIP4 model. These stable structures contrast with rapidly changing features like small size spots blasting in one single image, bright regions connecting trans-auroral structures, and the inner diffuse emission. The question of temporal variability and spatial extent of the auroral features is of major importance in understanding the origin and acceleration mechanisms of the auroral particles exciting the jovian UV aurora. In particular, short timescale processes can be related to field aligned currents generating acceleration structures and discrete aurora. [less ▲]

Detailed reference viewed: 14 (1 ULg)
See detailFUV spectroscopy of the H_2 emission in the Jovian aurora: model update and results
Gérard, Jean-Claude ULg; Dols, V.; Colignon, David ULg et al

in Bulletin of the American Astronomical Society (1998, September 01)

The Jovian aurora exhibits bright emissions mainly due the bright Lyman-alpha line and to radiation from excited singlet states to the ground electronic state extending from 800 to 1600 Angstroms. Above ... [more ▼]

The Jovian aurora exhibits bright emissions mainly due the bright Lyman-alpha line and to radiation from excited singlet states to the ground electronic state extending from 800 to 1600 Angstroms. Above 1200 Angstroms, the molecular spectrum is dominated by the Lyman (B-X) bands and continuum and the Werner (C-X) bands. These transitions have been observed with the Goddard High Resolution Spectrometer (GHRS) and the Space Telescope Imaging Spectrometer (STIS) at various spectral and spatial resolutions. To analyze these spectra, a model synthetic auroral spectrum has been constructed and applied to the analysis of the ro-vibrational temperature of H_2 and a search for non-H_2 emission features. It has been recently updated to include the latest singlet state excitation and cascading cross sections, self-absorption in optically thick lines and to account for the energy distribution of the secondary electrons which cause additional excitation. We illustrate these effects in a few study cases and apply the model to high resolution (0.5 Angstroms) GHRS spectra and low resolution STIS spectra of the entire H_2 spectrum at wavelengths longer than Lyman-alpha. We determine the methane column overlying the auroral emission peak and find that a better fit is obtained with additional absorption by acetylene. [less ▲]

Detailed reference viewed: 22 (4 ULg)
See detailHST-STIS Observations of Jupiter's Aurora
Clarke, J. T.; Ajello, J.; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1998, September 01)

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an ... [more ▼]

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an order of magnitude higher sensitivity than possible with earlier cameras, and improved angular resolution from shorter exposures. Images have been obtained at 4 epochs since Sept. 1997, and reveal several new features of the auroral emission pattern. These include i) faint auroral emissions extending roughly 60 deg. in the wake or plasma flow direction beyond Io's magnetic footprint, ii) systematic motions of the main auroral oval both toward the pole and toward the equator at different local times and longitudes, and iii) clear identification of an auroral emission feature with Ganymede's magnetic footprint, from the relative motion of the feature remaining underneath Ganymede in a time series of images. Preliminary interpretations of these features will be presented. Spectra have also been obtained of auroral emission features including the northern and southern main ovals, the diffuse emission poleward of the main oval, and the northern and southern Io footprints. These spectra will be presented with estimates of the overlying hydrocarbon columns, the energy of the exciting electrons, the rotational temperature of the emitting hydrogen, and the overlying column of atomic hydrogen. This work was supported by NASA under grants GO-6743.01-95A and GO-7308.01-96A to the University of Michigan. [less ▲]

Detailed reference viewed: 15 (1 ULg)
See detailJovian Auroral Lyalpha Self-Reversals: A Window on Jupiter's Auroral Electrojet?
Gladstone, G. R.; Waite, J H, Jr; Gérard, Jean-Claude ULg

in Bulletin of the American Astronomical Society (1998, September 01)

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed ... [more ▼]

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed line profiles, with the blue or red peak brighter depending on the target location in Jupiter's northern auroral region. The measured asymmetries are equivalent to Doppler velocities towards and away from the observer of several km/s. As suggested by Sommeria et al. (Icarus, 119, 2--24, 1995), electrojet velocities of ~ 10--20 km/s may be present at Jupiter. Here we investigate the possibility that the observed wavelength shifts of the auroral Lyalpha line are a result of multiple scattering by H atoms carried along in Jupiter's auroral electrojet. If this explanation is found to be viable, then HST/STIS mapping of the velocity shifts in the Lyalpha line may represent (as with ground-based high-resolution observations of jovian auroral H_3(+) emission lines) a means for determining the dynamics of Jupiter's upper atmosphere and ionosphere. [less ▲]

Detailed reference viewed: 5 (1 ULg)
See detailThe Jovian Aurora: Implications of Multiwavelength Auroral Spectra for Auroral Particle Identity and Auroral Microphysics
Waite, J. H.; Gladstone, G. R.; Bolton, S. J. et al

in Bulletin of the American Astronomical Society (1998, September 01)

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper ... [more ▼]

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper atmosphere. Both energetic heavy ions and electrons energized in the outer magnetosphere contribute to the auroral excitation, as indicated by the combination of x-ray and ultraviolet observations. Imaging with the HST in the ultraviolet and with the IRTF at infrared wavelengths reveals several distinct regions of interaction: 1) a dusk sector where turbulent auroral patterns extend well into the polar cap; 2) a morning sector generally characterized by a single spatially confined auroral arc originating in the outer magnetosphere of Jupiter; 3) diffuse emissions associated with the Io plasma torus; and 4) a distinct region associated with the Io Flux Tube footprint. Ultraviolet spectroscopy has provided important information about the thermal structure of the upper atmosphere and altitude distribution of the auroral particle energy deposition, while Lyman alpha line profiles offer clues to the nature of thermospheric dynamical effects. Galileo observations at visible wavelengths on the nightside have provided a new view of the jovian aurora with unprecedented spatial information. Infrared observations have added much to the understanding of thermal structure and morphology and may hold the key to understanding the role of Joule heating. Radio observations imply that energetic particle precipitation extends to low latitudes, a result that has been corroborated at x-ray wavelengths. Multispectral observations of jovian auroral emissions will be discussed within a theoretical/modeling framework that serves to provide some insight into magnetosphere-ionosphere coupling and its effect on the upper atmosphere. Particular emphasis will be placed on the use of auroral spectra to identify incident energetic particles and their energy spectra as a means of elucidating the microphysics of auroral processes. [less ▲]

Detailed reference viewed: 15 (1 ULg)
See detailFirst results on the evaluation of Haser scale lengths in comet Hale-Bopp (C/1995 O1) at R >= 3 AU
Helbert, J.; Rauer, H.; Arpigny, Claude ULg et al

in Bulletin of the American Astronomical Society (1998, September 01)

Due to its exceptional brightness, comet Hale-Bopp offered the possibility for unprecedented long-term monitoring. Medium resolution long-slit spectroscopic data and images were obtained using the Danish ... [more ▼]

Due to its exceptional brightness, comet Hale-Bopp offered the possibility for unprecedented long-term monitoring. Medium resolution long-slit spectroscopic data and images were obtained using the Danish Faint Object Spectrograph (DFOSC) at the 1.54m Danish telescope and the Boller and Chivens spectrograph at the 1.52m ESO telescope, La Silla, Chile. Pre-perihelion, comet Hale-Bopp was monitored from 4.6 AU to 2.9 AU and post-perihelion, the monitoring yields data from 3 AU up to a heliocentric distance of 5 AU. Production rates are often derived by using a simple Haser model to approximate the coma density distribution. This requires knowledge of the destruction scale lengths of the observed daughter species and its parents. As the brightness of most comets diminishes quickly with heliocentric distance, scale lengths have been determined only in comets around 1 AU. Due to the lack of data for large heliocentric distances, production rates in distant comets can only be derived by extrapolating these scale lengths. In this preliminary analysis of our data we evaluate the scale-lengths of CN, C_3 C_2, and NH_2 at heliocentric distances greater than 3 AU post-perihelion. The differences of production rates derived by using these directly determined and the extrapolated scale lengths are discussed. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Peer Reviewed
See detailHubble Space Telescope imaging of Jupiter's UV aurora during the Galileo orbiter mission
Clarke, John T; Ben Jaffel, Lotfi; Gérard, Jean-Claude ULg

in Journal of Geophysical Research (1998), 103

Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 (WFPC 2) images of Jupiter's aurora have been obtained close in time with Galileo ultraviolet spectrometer (UVS) spectra and in situ particles ... [more ▼]

Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 (WFPC 2) images of Jupiter's aurora have been obtained close in time with Galileo ultraviolet spectrometer (UVS) spectra and in situ particles, fields, and plasma wave measurements between June 1996 and July 1997, overlapping Galileo orbits G1, G2, G7, G8, and C9. This paper presents HST images of Jupiter's aurora as a first step toward a comparative analysis of the auroral images with the in situ Galileo data. The WFPC 2 images appear similar to earlier auroral images, with the main ovals at similar locations to those observed over the preceding 2 years, and rapidly variable emissions poleward of the main ovals. Further examples have been observed of the equatorward surge of the auroral oval over 140-180° longitude as this region moves from local morning to afternoon. Comparison of the WFPC 2 reference auroral ovals north and south with the VIP4 planetary magnetic field model suggests that the main ovals map along magnetic field lines exceeding 15R[SUB]J[/SUB], and that the Io footprint locations have lead angles of 0-10° from the instantaneous magnetic projection. There was an apparent dawn auroral storm on June 23, 1996, and projections of the three dawn storms imaged with HST to date demonstrate that these appear consistently along the WFPC 2 reference oval. Auroral emissions have been consistently observed from Io's magnetic footprints on Jupiter. Possible systematic variations in brightness are explored, within factor of 6 variations in brightness with time. Images are also presented marked with expected locations of any auroral footprints associated with the satellites Europa and Ganymede, with localized emissions observed at some times but not at other times. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailSimultaneous Determination of Pirlindole Enantiomers and Dehydropirlindole by Chiral Liquid Chromatography
Ceccato, Attilio ULg; Hubert, Philippe ULg; De Tullio, Pascal ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (1998), 17(6-7), 1071-9

Liquid chromatography was employed for the determination of pirlindole enantiomers and its oxidation product dehydropirlindole (DHP). The direct separation of pirlindole enantiomers and DHP was achieved ... [more ▼]

Liquid chromatography was employed for the determination of pirlindole enantiomers and its oxidation product dehydropirlindole (DHP). The direct separation of pirlindole enantiomers and DHP was achieved on a cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase (Chiralcel OD-R). Acetonitrile was used as the organic modifier and sodium perchlorate was used as an ionic additive in the mobile phase. The influence of acetonitrile and sodium perchlorate concentrations on enantioselectivity and achiral selectivity towards DHP was investigated in order to find suitable conditions for the determination of low amounts of each analyte. The mobile phase selected consisted of a mixture of acetonitrile and phosphate buffer (pH 5.0) containing sodium perchlorate (0.05 M) (35:65, v/v) and the UV detector was set at 220 nm. The method developed was validated and was found to be linear in the 0.1-5 microg ml(-1) range (r2 = 0.999 for the three compounds). Repeatability and the intermediate precision for the three analytes at a concentration of 0.1 microg ml(-1) were about 3 and 4%, respectively. This concentration corresponds to the quantification of 0.1% for the minor enantiomer. Actual determinations of enantiomeric purity for single enantiomers of pirlindole were performed. [less ▲]

Detailed reference viewed: 15 (3 ULg)