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See detailThe Old Halo metallicity gradient: the trace of a self-enrichment process
Parmentier, Geneviève ULg; Jehin, Emmanuel ULg; Magain, Pierre ULg et al

in Astronomy and Astrophysics (2000), 363

Based on a model of globular cluster self-enrichment published in a previous paper, we present an explanation for the metallicity gradient observed throughout the galactic Old Halo. Our self-enrichment ... [more ▼]

Based on a model of globular cluster self-enrichment published in a previous paper, we present an explanation for the metallicity gradient observed throughout the galactic Old Halo. Our self-enrichment model is based on the ability of globular cluster progenitor clouds to retain the ejecta of a first generation of Type II Supernovae. The key point is that this ability depends on the pressure exerted on the progenitor cloud by the surrounding protogalactic medium and therefore on the location of the cloud in the protoGalaxy. Since there is no significant (if any) metallicity gradient in the whole halo, we also present a review in favour of a galactic halo partly built via accretions and mergers of satellite systems. Some of them bear their own globular clusters and therefore ``contaminate'' the system of globular clusters formed ``in situ'', namely within the original potential well of the Galaxy. Therefore, the comparison between our self-enrichment model and the observational data should be limited to the genuine galactic globular clusters, the so-called Old Halo group. [less ▲]

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See detailAmplitude equations and thermoconvective rolls far from the threshold
Dauby, Pierre ULg; Desaive, Thomas ULg

in Proceedings of the 53rd annual meeting of the division of fluid dynamics of the American physical society (2000, November 01)

Amplitude equations are used to show that third order harmonics of a basic roll convective pattern can appear in the highly nonlinear régime of Rayleigh-Bénard thermoconvection. The phenomenon is induced ... [more ▼]

Amplitude equations are used to show that third order harmonics of a basic roll convective pattern can appear in the highly nonlinear régime of Rayleigh-Bénard thermoconvection. The phenomenon is induced by the nonlinear interaction of the roll pattern with its second order harmonics, which were first generated by the quadratic nonlinearity due to the convective terms of the time derivatives in the field equations. Good qualitative agreement with experimental data is obtained with only 4 amplitude equations. More precise quantitative results are deduced by increasing the number of amplitude equations. Comparison with purely numerical calculations is also discussed. [less ▲]

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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 ▲]

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See detailAn Optical Time Delay Estimate for the Double Gravitational Lens System B1600+434
Burud, I.; Hjorth, J.; Jaunsen, A. O. et al

in Astrophysical Journal (2000), 544

We present optical I-band light curves of the gravitationally lensed double QSO B1600+434 from observations obtained at the Nordic Optical Telescope (NOT) between 1998 April and 1999 November. The ... [more ▼]

We present optical I-band light curves of the gravitationally lensed double QSO B1600+434 from observations obtained at the Nordic Optical Telescope (NOT) between 1998 April and 1999 November. The photometry has been performed by simultaneous deconvolution of all the data frames, involving a numerical lens galaxy model. Four methods have been applied to determine the time delay between the two QSO components, giving a mean estimate of Deltat=51+/-4 days (95% confidence level). This is the fourth optical time delay ever measured. Adopting a Omega=0.3, Lambda=0 universe and using the mass model of Maller et al., this time delay estimate yields a Hubble parameter of H[SUB]0[/SUB]=52[SUP]+14[/SUP][SUB]-8[/SUB] km s[SUP]-1[/SUP] Mpc[SUP]-1[/SUP] (95% confidence level), where the errors include time delay as well as model uncertainties. There are time-dependent offsets between the two (appropriately shifted) light curves that indicate the presence of external variations due to microlensing. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. [less ▲]

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See detailCoordinated monitoring of the eccentric O-star binary Iota Orionis: the X-ray analysis
Pittard, Julian M; Stevens, Ian R; Corcoran, Michael F et al

in Monthly Notices of the Royal Astronomical Society (2000), 319

We analyse two ASCA observations of the highly eccentric O9 III+B1 III binary Iota Orionis obtained at periastron and apastron. Based on the assumption of a strong colliding-wind shock between the stellar ... [more ▼]

We analyse two ASCA observations of the highly eccentric O9 III+B1 III binary Iota Orionis obtained at periastron and apastron. Based on the assumption of a strong colliding-wind shock between the stellar components, we expected to see significant variation in the X-ray emission between these phases. The observations proved otherwise: the X-ray luminosities and spectral distributions were remarkably similar. The only noteworthy feature in the X-ray data was the hint of a proximity effect during periastron passage. Although this `flare' is of relatively low significance, it is supported by the notable proximity effects seen in the optical, and the phasing of the X-ray and optical events is in very good agreement. However, other interpretations are also possible. In view of the degradation of the SIS instrument and source contamination in the GIS data we discuss the accuracy of these results, and also analyse archival ROSAT observations. We investigate why we do not see a clear colliding-wind signature. A simple model shows that the wind attenuation to the expected position of the shock apex is negligible throughout the orbit, which poses the puzzling question of why the expected 1/D variation (i.e. a factor of 7.5) in the intrinsic luminosity is not seen in the data. Two scenarios are proposed: either the colliding-wind emission is unexpectedly weak such that intrinsic shocks in the winds dominate the emission, or, alternatively, the emission observed is colliding-wind emission but in a more complex form than we would naively expect. Complex hydrodynamical models are then analysed. Despite strongly phase-variable emission from the models, both are consistent with the observations. We find that if the mass-loss rates of the stars are low then intrinsic wind shocks could dominate the emission. However, when we assume higher mass-loss rates of the stars, we find that the observed emission could also be consistent with a purely colliding-wind origin. A summary of the strengths and weaknesses of each interpretation is presented. To distinguish between the different models X-ray observations with improved phase coverage will be necessary. [less ▲]

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See detailGeneva photometry of HDE 318107 (Manfroid+, 2000)
Manfroid, Jean ULg; Mathys, G.

Report (2000)

File table1 contains the individual photometric measurements of HDE 318107 in the Geneva system. (1 data file).

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See detailMicro-adénomes à prolactine : le traitement par cabergoline
Beckers, Albert ULg; Valdes Socin, Hernan Gonzalo ULg

in Médecine Thérapeutique Endocrinologie (2000), 2(6), 496-500

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See detailLes hyperparathyroidies primaires: étiologies, diagnostic et traitement.
Janssens, L.; Verbeke, V.; Petrossians, Patrick ULg et al

in Revue Médicale de Liège (2000), 55(11), 977-985

L'hyperparathyroïdie primaire est une maladie trop souvent méconnue. Son incidence est estimée à 28/100.000, soit environ 2.800 nouveaux cas par an en Belgique. La fréquence de l'hyperparathyroïdie ... [more ▼]

L'hyperparathyroïdie primaire est une maladie trop souvent méconnue. Son incidence est estimée à 28/100.000, soit environ 2.800 nouveaux cas par an en Belgique. La fréquence de l'hyperparathyroïdie augmente avec l'âge. En effet, 50 % des cas sont rencontrés après l'âge de 70 ans et 3 à 4 % des femmes au-delà de 70 ans sont touchées par l'affection. Cette affection peut être sporadique ou survenir dans un cadre étiologique plus complexe tel que les polyendocrinopathies ou la neurofibromatose. L'attention vers ce diagnostic doit être attirée par une symptomatologie, souvent bâtarde, de fatigue (parfois isolée), de polyurie, de polydipsie, d'hypertension artérielle ou la présence de lithiases rénales. Lorsque le diagnostic d'hyperparathyroïdie est renteu, il convient de localiser la ou les glande(s) pathologique(s) et de définir le contexte étiologique qui pourra déterminer le choix thérapeutique le plus approprié. Une étude biologique simple sera réalisée devant toute suspicion d'hyperparathyroïdie. Dans certains cas, le diagnostic sera aidé par la réalisation d'un test de surcharge calcique qui peut permettre de confirmer l'hyperparathyroïdie et d'apprécier son degré d'autonomisation. [less ▲]

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See detailProjet de développement d'un système de relevé numérique des documents archéologiques en trois dimensions par des procédés optoélectroniques
Laboury, Dimitri; Baré, Marie; Renotte, Yvon et al

Poster (2000, November)

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See detailLes déchirures des muscles ischio-jambiers chez le footballeur : évaluation, prévention, entraînement
Croisier, Jean-Louis ULg

in Actes du 2ème Congrès Européen Olympique de la Kinésithérapie et de la Médecine du Sport (2000, November)

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See detailA radio-tracking study on the impact of small dams on the conservation of salmonid fish in Southern Belgium.
Ovidio, Michaël ULg; Lambot, Francis; DeBast, Benoît et al

Conference (2000, November)

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See detailSerotype distribution of invasive Streptococcus agalactiae isolated from neonates and adults in Belgium over a 4-year period (1995-1999)
MELIN, Pierrette ULg; De Mol, Patrick ULg

in Martin, Diana R.; Tagg, John R. (Eds.) Streptococci and Streptococcal Diseases Entering the New Millenium - Proceeding of the XIV LISSSD (2000, November)

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See detailUtilisation de la télédétection pour le suivi des parcours en zone agro-pastorale sahélienne
Djaby, Bakary ULg

Master of advanced studies dissertation (2000)

L'importance des terres de parcours au Sahel a depuis les sécheresses, favorisées l'observation des ressources pastorales par la télédétection basse résolution. Parmi les indices de végétation issus des ... [more ▼]

L'importance des terres de parcours au Sahel a depuis les sécheresses, favorisées l'observation des ressources pastorales par la télédétection basse résolution. Parmi les indices de végétation issus des images fournies par les différents senseurs, le NDVI est le plus couramment utilisé. Plusieurs travaux ont montré que cet indice est affecté par les variations des propriétés spectrales des sols. Cette caractéristique limite la détection de la végétation dans les milieux à couvert végétal faible comme en zone agropastorale sahélienne. Afin de pallier cette insuffisance du NDVI, plusieurs autres indices ont vu le jour comme le TSAVI dont les caractéristiques se sont montrées performantes en milieu expérimental pour le suivi de la végétation éparse. Au cours de ce travail, le TSAVI est élaboré et utilisé en mode opérationnel en comparaison avec le NDVI. Les deux indices utilisés sont issus des images de SPOT-VEGETATION, le nouveau senseur européen opérationnel depuis 1998. Cette comparaison est faite à travers l'évolution au cours de la saison des deux indices et l'évaluation de la phytomasse herbacée dans un milieu où l'occupation des sols est connue. Les résultats obtenus montrent que le TSAVI diffère très peu du NDVI au cours de la période de végétation active. Les différences observées résident dans la capacité du TSAVI à identifier les zones d'émergence précoce de la végétation, en début de saison des pluies. Dans une classification supervisée avec la signature indiciaire des sols de la région du Fakara, le TSAVI se montre plus performant avec une erreur d'omission inférieure de 10% à celle du NDVI. Dans l'évaluation de la phytomasse herbacée, les relations obtenues montrent que le NDVI est plus indiqué que le TSAVI. Malgré l'utilisation de données sur l'occupation des sols, les relations obtenues entre les indices et les masses végétales sont faibles. Cette faiblesse des relations est en partie liée au morcellement du territoire en milieu agropastoral sahélien. En revanche, dans les zones qui apparaissent homogènes, les résultats indiquent des liaisons fortes entre les indices et la masse végétale des mauvaises herbes. Les zones agropastorales du Sahel semblent plus indiquées dans un suivi qualitatif avec la télédétection basse résolution. La complexité de l'occupation des sols liée à plusieurs facteurs peut cependant être abordée avec une combinaison télédétection haute résolution et basse résolution pour une amélioration de l'information sur la sécurité alimentaire au Sahel. [less ▲]

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See detailIn Vitro Study of the Antioxidant Properties of Nimesulide and 4-Oh Nimesulide: Effects on Hrp- and Luminol-Dependent Chemiluminescence Produced by Human Chondrocytes
Zheng, S. X.; Mouithys-Mickalad, Ange ULg; Deby-Dupont, G. P. et al

in Osteoarthritis and Cartilage (2000), 8(6), 419-25

OBJECTIVES: Reactive oxygen species (ROS) are now recognized to play an important role in the pathogenesis of rheumatic diseases and constitute an interesting therapeutic target for drugs. This in vitro ... [more ▼]

OBJECTIVES: Reactive oxygen species (ROS) are now recognized to play an important role in the pathogenesis of rheumatic diseases and constitute an interesting therapeutic target for drugs. This in vitro study was designed to evaluate the antioxidant properties of nimesulide (NIM), a nonsteroidal antiinflammatory drug of the sulfonanilide class, and its main metabolite 4-OH nimesulide (4-OHNIM). METHODS: The scavenging effects of NIM and 4-OH NIM on hydroxyl radical ((.)OH) and superoxide anions (O(minusd)(2)) were investigated by electron spin resonance (ESR), using 5, 5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. The quenching properties of these drugs on hypochlorite anion was studied by luminol enhanced chemiluminescence. Finally, the effects of NIM and 4-OHNIM on the reactive oxygen species production by human articular chondrocytes were recorded by HRP and luminol-enhanced chemiluminescence. RESULTS: By this method it has been demonstrated that NIM and 4-OHNIM, at concentrations ranging from 10 to 100 microM, are potent scavengers of(.)OH whereas only 4-OHNIM was capable to scavenge O(minusd)(2). Chemiluminescence generated by HOCl was also significantly and dose-dependently inhibited by both NIM and 4-OHNIM. Nevertheless, at each concentration tested, the inhibitory effect of 4-OHNIM was significantly more marked, even at the highest concentration (100 microM). Furthermore, when chondrocytes were pre-incubated for 48-96 h with NIM or 4-OHNIM, the luminol- and HRP-dependent CL produced by the cells was significantly inhibited in a dose-dependent manner. CONCLUSIONS: NIM and 4-OHNIM may protect cartilage against oxidative stress, not only by scavenging ROS but also by inhibiting their production by chondrocytes. [less ▲]

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See detailDifferences in Experimental Virulence of Bovine Viral Diarrhoea Viral Strains Isolated from Haemorrhagic Syndromes
Hamers, C.; Couvreur, B.; Dehan, Pierre ULg et al

in Veterinary Journal (2000), 160(3), 250-8

In the late 1980s, a new hypervirulent and epidemic form of bovine viral diarrhoea virus (BVDV) infection appeared in North America. A similar but sporadic syndrome was later reported in Europe. To ... [more ▼]

In the late 1980s, a new hypervirulent and epidemic form of bovine viral diarrhoea virus (BVDV) infection appeared in North America. A similar but sporadic syndrome was later reported in Europe. To compare the pathogenic characters of the North American and European hypervirulent strains, we inoculated BVDV naive calves with BVDV strains isolated from haemorrhagic syndromes originating in Belgium, France and the USA. The experimental procedure comprised daily clinical examination and measurement of blood and virological parameters.The American BVD890/256 strain induced severe thrombocytopaenia, profuse diarrhoea and pneumonia in all calves, indicating that hypervirulent BVDV could be the primary infectious agent of pneumonia. Interestingly, a strong correlation was observed between the intense viraemia and a decreased platelet count. None of the European strains tested induced significant pathological signs, although isolated from cases presenting haemorrhagic syndrome. [less ▲]

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See detailMesure de vibrations par holographie dynamique multi-expositions
Georges, Marc ULg; Thizy, Cédric ULg; Lemaire, Philippe et al

in Actes du Premier colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2000, November)

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See detailPropriété intellectuelle : vers une exception à l’épuisement communautaire?
Munoz, Rodolphe ULg

in Journal des Tribunaux Droit Européen (2000), 73

La théorie de l’épuisement empêche une entreprise de s’opposer à la commercialisation d’un produit qui a été écoulé sur un autre marché. L’épuisement est dit "communautaire" ou régional: la protection ne ... [more ▼]

La théorie de l’épuisement empêche une entreprise de s’opposer à la commercialisation d’un produit qui a été écoulé sur un autre marché. L’épuisement est dit "communautaire" ou régional: la protection ne peut être invoquée dans un Etat membre lorsque le produit a déjà été mis sur le marché dans un autre pays de la Communauté. La jurisprudence analysée dans cet article indique que l’épuisement pourrait devenir mondial. Aucune firme ne pourrait alors empêcher l’écoulement d’un produit commercialisé dans un pays tiers. Les vendeurs pourraient écouler dans la Communauté des produits achetés moins cher à l’étranger. Cela serait particulièrement intéressant pour les produits électroniques, qui sont traditionnellement chers en Europe. Le processus entraînerait, à moyen terme, une diminution des prix sur le continent européen. [less ▲]

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See detailComment je traite ... le myelome multiple refractaire par thalidomide
Scerbo, F.; Matus, G.; Sautois, Brieuc ULg et al

in Revue Médicale de Liège (2000), 55(11), 970-3

Despite the use of high-dose chemotherapy with autologous hematopoietic stem cell transplantation, multiple myeloma remains largely uncurable. Indeed complete remission rate is about 50% and median ... [more ▼]

Despite the use of high-dose chemotherapy with autologous hematopoietic stem cell transplantation, multiple myeloma remains largely uncurable. Indeed complete remission rate is about 50% and median survival reaches 5 years without plateau. Recently thalidomide has been identified as a promising agent. We report the clinical story of 2 patients with refractory myeloma that we treated successfully with thalidomide. [less ▲]

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See detailMMP-2 and MMP-9-Linked Gelatinolytic Activity in the Sputum from Patients with Asthma and Chronic Obstructive Pulmonary Disease
Cataldo, Didier ULg; Munaut, Carine ULg; Noël, Agnès ULg et al

in International Archives of Allergy & Immunology (2000), 123(3), 259-67

BACKGROUND: The course of asthma and chronic obstructive pulmonary disease (COPD) is associated with bronchial morphological changes. Metalloproteinases are thought to play a role in these structural ... [more ▼]

BACKGROUND: The course of asthma and chronic obstructive pulmonary disease (COPD) is associated with bronchial morphological changes. Metalloproteinases are thought to play a role in these structural changes. METHODS: We studied the gelatinolytic activity present in the induced sputum from 20 patients with asthma, 20 with COPD and 19 healthy controls. The assessment of gelatinolytic activity was performed by quantitative zymography, and gelatinolytic species were identified by Western blot analysis. Tissue inhibitor of metalloproteinase-1 (TIMP-1) was detected by reverse zymography and ELISA. RESULTS: From zymography, we found significantly higher gelatinolytic activity linked to pro-matrix metalloproteinase-9 (pro-MMP-9) in the sputum from asthmatics (p < 0.0001) and COPD patients (p < 0.0001) compared to the control group. Furthermore, the activated form of MMP-9 (85 kD) was found in the sputum from 60% of asthmatics and 85% of COPD patients, but was absent in that of control subjects (p < 0.0001). Importantly, although less frequently detectable than pro-MMP-9, pro- MMP-2 (72 kD) was found more frequently in asthmatics (50%) than in control subjects (5%) (p < 0. 005). We also described two unusual gelatinolytic species of 45 and 120 kD and showed that they derived from MMP-9 according to their ability to bind gelatin and anti-MMP-9 antibody. Levels of TIMP-1 were higher in asthmatics (p < 0.05) and COPD patients (p < 0.05) than in controls. CONCLUSION: Asthmatics and COPD patients display an increased gelatinolytic activity linked to MMP-2 and MMP-9 and higher levels of TIMP-1 in their sputum. [less ▲]

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