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See detailBinaries in the Hipparcos data: keep digging II. Modeling the IAD of known spectroscopic systems
Pourbaix, D.; Jancart, Sylvie ULg; Jorissen, A.

in Hensberge, H.; Pavlovski, K.; Hilditch, R. W. (Eds.) Spectroscopically and Spatially Resolving the Components of the Close Binary Stars (2004, December 01)

We reprocess the Hipparcos Intermediate Astrometric Data of know spectroscopic binaries (retrived from the 9th catalogue of spectroscopic binary orbits, http://sb9.astro.ulb.ac.be) to see whether the ... [more ▼]

We reprocess the Hipparcos Intermediate Astrometric Data of know spectroscopic binaries (retrived from the 9th catalogue of spectroscopic binary orbits, http://sb9.astro.ulb.ac.be) to see whether the orbital inclination, and thus the mass of the secondary, can be derived. Several statistical tests (Pourbaix & Arenou 2001) are used to ensure the reliability of the fit. About 70 systems (originally processed as single stars) out of 863 benefit from the orbital model. [less ▲]

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See detailFUV remote sensing of the isotropic boundary and magnetotail stretching
Blockx, Caroline ULg; Gérard, Jean-Claude ULg; Meurant, M. et al

Conference (2004, December 01)

Several studies attempted to identify the Isotropic Boundary (IB) defining the limit between the adiabatic and non-adiabatic trajectories of the trapped protons along closed magnetic field lines. This ... [more ▼]

Several studies attempted to identify the Isotropic Boundary (IB) defining the limit between the adiabatic and non-adiabatic trajectories of the trapped protons along closed magnetic field lines. This boundary is an indicator of the amount of magnetic field lines' stretching in the magnetotail. These studies are based on in situ measurements, resulting in spatially and temporally restricted samples. To avoid this limitation, we propose to use global data obtained with the FUV-SI12 proton imager on board IMAGE spacecraft. We determine at each magnetic local time the position of an optical boundary equivalent to IB and thereby the stretching of the magnetic field lines. We show that the correspondence between the latitude of the maximum proton precipitation observed by SI12 and the IB measured by DMSP satellites is statistically established and depends on the magnetic local time. The relation between the position of the maximum proton precipitation as well as the intensity of this maximum and the magnetic field's distortion is determined by comparison with GOES-8 data. We thus suggest that SI12 can be used as a tool for the global determination of the isotropic boundary and to monitor the amount of stretching in the magnetotail. [less ▲]

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See detailThe PEGASE project: characterisation of "Pegasi planets" and Brown Dwarfs
Baudoz, P.; Rouan, D.; Schneider, J. et al

in Combes, F.; Barret, D.; Contini, T. (Eds.) et al SF2A-2004: Semaine de l'Astrophysique Francaise (2004, December 01)

I will present the PEGASE project proposed within the framework of the CNES call for idea on flights in formation. This ambitious project, gathering a dozen laboratories, proposes an interferometry ... [more ▼]

I will present the PEGASE project proposed within the framework of the CNES call for idea on flights in formation. This ambitious project, gathering a dozen laboratories, proposes an interferometry mission in infrared I(1.5 to 6 µm) with spectroscopic capabilities. The bases of the interferometer will reach up to 500m, giving to PEGASE a resolution higher than the milli-arcsecond. The interferometric recombination includes a very simple mode, measurement of the visibility by excursion of the optical path difference and a mode in black fringe or nulling. The very high angular resolution of the instrument and high dynamical range with the nulling mode will allow to consider exciting scientific objectives: the characterization of Pegasids or hot Jupiters, the study of the internal structure and the atmospheres of brown dwarfs and the analysis of the internal areas of proto-planetary disks. I will first of all describe the basic configuration of the mission and will show that its simplicity ensures the feasibility of the project. I will explain then the relevance of such an instrument for the characterization of Pegasids. I will detail finally the various possible technical options to be attached to the initial version, in order to increase the effectiveness of the mission and to extend its scientific objectives. [less ▲]

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See detailComparison of intense nightside shock induced aurora and substorms activity
Meurant, M.; Gérard, Jean-Claude ULg; Blockx, Caroline ULg et al

Conference (2004, December 01)

Variations of the solar wind dynamic pressure induce perturbation of magnetospheric processes. These perturbations frequently induce dayside enhancements of activity with particular features such as low ... [more ▼]

Variations of the solar wind dynamic pressure induce perturbation of magnetospheric processes. These perturbations frequently induce dayside enhancements of activity with particular features such as low latitude proton flash, low latitude arcs and aurora propagating eastward and westward from noon to the night sector. In some cases, these shocks may also induce an enhancement of the nightside activity during which the power precipitated in the night sector may reach values as high as observed during substorms. Various studies have shown that high precipitated powers are more likely during period of negative values of the North - South IMF components. Liou et al (2003) have shown that substorm-like activity is not frequent after a shock and they concluded that a shock may not be considered as a substorm trigger. The question addressed in this study is to know up to what point the substorm like nightside activity triggered by a shock is comparable to a classical substorm. For this purpose, we analyze four events presenting nightside activity morphologically similar to substorms and occurring within a short time (less than 20 minutes) after the arrival of a pressure pulse on the front of the magnetosphere. Different features of these events such as the mean energy of precipitated electrons, the motion of boundaries before and after onset and the power precipitated in the nightside region are compared to typical substorms. Except for the absence of southward motion of activity before onset, shock induced substorms appear very similar to isolated substorms. We investigate the ability of a shock to trigger a substorm during periods characterized by particular conditions. We suggest that the sign of B[SUB]z[/SUB] plays an important role as well as the history of solar wind and interplanetary magnetic field and the resulting state of the magnetosphere. [less ▲]

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See detailAsteroseismology of the β Cephei star ν Eridani: massive exploration of standard and non-standard stellar models to fit the oscillation data
Ausseloos, M.; Scuflaire, Richard ULg; Thoul, Anne ULg et al

in Monthly Notices of the Royal Astronomical Society (2004), 355

We present the results of a detailed seismic modelling of the β Cephei star ν Eridani with the Liège evolution and pulsation codes. We selected four clearly detected, well-identified and independent ... [more ▼]

We present the results of a detailed seismic modelling of the β Cephei star ν Eridani with the Liège evolution and pulsation codes. We selected four clearly detected, well-identified and independent pulsation modes from the frequency spectrum obtained from a recent five-month multisite, multitechnique campaign, while previous modelling work only took into account three frequencies. We show by means of a massive exploration of the parameter space that no standard stellar model both matches and excites these four observed modes, in contrast to the conclusion reached when considering only three frequencies. Therefore, we have considered stellar models with different metal mixtures and different initial hydrogen abundance values. We show that an increase in the relative number fraction of iron throughout the whole star or a large decrease in the initial hydrogen abundance make the stellar models matching the four selected modes satisfy all observational constraints and we provide the general properties of the best such physical models. [less ▲]

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See detailFemmes d’Afrique confrontées au sida, stratégies individuelles et collectives
Demart, Sarah ULg

Scientific conference (2004, December 01)

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See detailLimits for the application of spectroscopic mode ID methods
Zima, W.; Kolenberg, K.; Briquet, Maryline ULg et al

in IAU Symposium, No. 224, The A-Star Puzzle, held in Poprad, Slovakia, July 8-13, 2004. (2004, December 01)

Spectroscopic mode identification techiques, which monitor intensity variations across an absorption line, provide the possibility of determining the quantum numbers l and m, the inclination and the ... [more ▼]

Spectroscopic mode identification techiques, which monitor intensity variations across an absorption line, provide the possibility of determining the quantum numbers l and m, the inclination and the intrinsic pulsation amplitude of a star. Of course, the uncertainties of the mode identification are dependent on the quality of the observations and the identification method applied. We have focused on the Pixel-by-pixel method/Direct line profile fitting (Mantegazza 2000) and the Moment method (Balona 1987, Briquet & Aerts 2003) for pinpointing mode parameters and tested the impact of various observational effects and stellar properties on the identification. [less ▲]

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See detailOn the Characteristics and Source Regions of Dayside Proton Precipitation
Chua, D. H.; Dymond, K. F.; Budzien, S. A. et al

Conference (2004, December 01)

The source regions of precipitating protons on the dayside and their dependence on solar wind conditions are studied using far-ultraviolet (FUV) spectral observations and imaging. The High-resolution ... [more ▼]

The source regions of precipitating protons on the dayside and their dependence on solar wind conditions are studied using far-ultraviolet (FUV) spectral observations and imaging. The High-resolution Ionospheric and Thermospheric Spectrograph (HITS) aboard the Advanced Research and Global Observation Satellite (ARGOS) observes Doppler-shifted H Lyman-α emissions from precipitating protons with a spectral resolution of 1.5 Angstroms. The shapes of these Doppler spectra are indicative of the energy and pitch angle distributions of the proton precipitation. Global images of H Lyman-α emissions obtained by the SI-12 instrument on the IMAGE spacecraft are examined to relate the spectral observations to the dayside morphology of the proton aurora. During periods of sustained southward interplanetary magnetic field (IMF), the dayside proton aurora spectra exhibit broad Doppler shifts and are similar to those observed on the nightside with inferred mean energies typical of plasma sheet protons of magnetospheric origin. Global images of proton aurorae under these conditions show continuous regions of H Lyman-α emissions across the dayside extending from the nightside. In contrast, during periods of northward or variable IMF, proton aurora emissions on the dayside often appear in an isolated spot in the noon to late afternoon MLT sector. The Doppler-spectra of the proton emissions in these regions are narrow, indicating precipitation with low mean energies and from a different origin than that observed in the southward IMF cases. These spectra may be indicative of magnetosheath protons that have direct access to the ionosphere through high-latitude dayside reconnection. This study further quantifies the characteristics of dayside proton precipitation under various states of the magnetosphere and highlights the importance of IMF orientation on the coupling between the high-latitude, dayside ionosphere and its plasma sources at higher altitudes. [less ▲]

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See detailBinaries in the Hipparcos data: Keep digging, I. Search for binaries without `a priori' knowledge of their orbital elements: Application to barium stars
Jorissen, A.; Jancart, Sylvie ULg; Pourbaix, D.

in Hensberge, H; Pavlovski, K.; Hilditch, R.W. (Eds.) Spectroscopically and Spatially Resolving the Components of the Close Binary Stars (2004, December 01)

This work makes use of Hipparcos data to test the algorithms of (i) binary detection and (ii) orbital-parameters determination, which could possibly be used in the GAIA pipeline. The first item is ... [more ▼]

This work makes use of Hipparcos data to test the algorithms of (i) binary detection and (ii) orbital-parameters determination, which could possibly be used in the GAIA pipeline. The first item is addressed in this paper, whereas the second one is addressed in a companion paper by Pourbaix, Jancart, & Jorissen (2004, this volume). Here we test the ability of the algorithm to detect binaries from scratch, i.e., from the astrometric data without any a priori knowledge of the orbital elements. The Hipparcos Intermediate Astrometric Data of a complete sample of 163 barium stars (supposed to be all members of binary systems from theoretical considerations) are used as a test bench. When \varpi > 5 mas and P < 4000 d, the binary detection rate is close to 100%, but it falls to 22% when considering the whole sample, because many barium stars have small parallaxes or very long periods. [less ▲]

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See detailA search for radial magnetic field gradients in Ap atmospheres
Nesvacil, N.; Hubrig, S.; Jehin, Emmanuel ULg et al

in Zverko, J. (Ed.) The A-Star Puzzle (2004, December 01)

For the first time the possible presence of radial gradients of magnetic fields in the atmospheres of three magnetic Ap stars has been critically examined by measurements of the mean magnetic field ... [more ▼]

For the first time the possible presence of radial gradients of magnetic fields in the atmospheres of three magnetic Ap stars has been critically examined by measurements of the mean magnetic field modulus from spectral lines resolved into magnetically split components lying on the different sides of the Balmer jump. A number of useful diagnostic lines below and above the Balmer discontinuity, only slightly affected by blends, with simple doublet and triplet Zeeman pattern have been identified from the comparison between synthetic spectra computed with the SYNTHMAG code and the high resolution and S/N spectra obtained in unpolarized light with the ESO-VLT UVES spectrograph. For all three stars of our sample, HD 965, HD 116114 and 33 Lib (HD 137949), an increase of the magnetic field strength of the order of a few hundred Gauss has been detected bluewards of the Balmer discontinuity. These results should be taken into account in future modelling of the geometric structure of Ap star magnetic fields and the determination of the chemical abundances in Ap stars with strong magnetic fields. [less ▲]

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

Article for general public (2004)

EF Phobos; L'astéroïde ivre; Bonne nouvelle pour Pluton; Titan; Uranus; Eclipse de lunes triple; IRS13E; J1148+5251; Distances cosmiques; Image gamma; Un impact de plus pour l'extinction K-T?; Un nouveau ... [more ▼]

EF Phobos; L'astéroïde ivre; Bonne nouvelle pour Pluton; Titan; Uranus; Eclipse de lunes triple; IRS13E; J1148+5251; Distances cosmiques; Image gamma; Un impact de plus pour l'extinction K-T?; Un nouveau compagnon pour la Voie Lactée; Supernovae de Lucy et de Tycho; Amas globulaire [less ▲]

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See detailNumber of iterations when comparing MLEM/OSEM with FBP
Seret, Alain ULg

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2004), 45(12), 2125-2125

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See detailOxytocin- and vasopressin-induced growth of human small-cell lung cancer is mediated by the mitogen-activated protein kinase pathway
Pequeux, Christel ULg; Keegan, B. P.; Hagelstein, M. T. et al

in Endocrine-Related Cancer (2004), 11(4), 871-885

Malignant growth of small-cell lung carcinoma is promoted by various neuroendocrine autocrine/paracrine loops. Therefore, to interfere with this mitogenic process, it is crucial to elucidate the ... [more ▼]

Malignant growth of small-cell lung carcinoma is promoted by various neuroendocrine autocrine/paracrine loops. Therefore, to interfere with this mitogenic process, it is crucial to elucidate the mechanisms involved. It is known that the oxytocin (OT) and vasopressin (VP) genes, normally transcriptionally restricted in their expression, are activated in small-cell lung cancer (SCLC), concomitantly with expression of their receptors (OTR, V1aR, V1bR/V3R and V2R). The aim of the present study was to characterize, in concentrations close to physiological and pharmacological conditions, intracellular signalling events triggered by OT and VP binding to their specific receptors in SCLC cells and to identify factors mediating OT- and VP-induced mitogenic effects on SCLC. Known agonists for OTR ([Thr(4),GlY(7)]OT) and V1aR (F180), in addition to OT and VP, were able to elicit increases in cytosolic Ca2+ levels and this effect could be blocked using an OTR antagonist (OVTA) or a V1aR antagonist (SR49059) respectively. There was no activation of the cAMP pathway detected after VP, dDAVP (a V2R agonist), or OT treatment. Stimulation of SCLC cells with OT and VP led to an increase of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation, maximal at 5 min, and the subsequent phosphorylation of its downstream target p90 ribosomal S6 kinase (p90(RSK)). Pre-incubation with OVTA and SR49059, and with inhibitors of phospholipase C (PLC), protein kinase C (PKC), mitogen-activated protein kinase/ERK kinase (MEK) 1/2 and a Ca2+ chelator significantly reduced OT- and VP-induced ERK1/2 phosphorylations. OVTA, SR49059 as well as MEK1/2 and PKC inhibitors also downregulated OT- and VP-induced p90RSK phosphorylation. In [H-3]thymidine-uptake 2, experiments, we subsequently observed that PLC, Ca2+, PKC and ERK1/2 are absolutely required for the OT- and VP-stimulated SCLC cellular growth process. In conclusion, the results presented here indicate that OT- and VP-induced mitogenic effects on SCLC are respectively mediated by OTR and V1aR signalling and that this mitogenic signalling passes through the phosphorylation of ERK1/2 and p90(RSK) in a PLC-, Ca2+-, PKC- and MEK1/2-dependent pathway. [less ▲]

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See detailStudy on the relationship between lineaments and borehole specific capacity in a fractured and karstified limestone area in Vietnam
Tam, V. T.; De Smedt, F.; Batelaan, Okke et al

in Hydrogeology Journal (2004), 12(6), 662-673

For a karstified limestone area in NW Vietnam, the relationship between the distribution of lineaments and borehole specific capacity is determined, resulting in the conclusion that not only the borehole ... [more ▼]

For a karstified limestone area in NW Vietnam, the relationship between the distribution of lineaments and borehole specific capacity is determined, resulting in the conclusion that not only the borehole geomorphological-hydrogeological position but also the lineament distribution influences the specific capacity. No significant spatial well yield patterns are evident in this highly fractured-karstified region. The supposition is that lineaments caused by geotectonic activities affect the local variability in borehole specific capacity. Sixteen pumping tests in conjunction with a comprehensive lineament analysis are used to prove this relationship. The boreholes and lineaments are classified into two groups according to their similarity in geomorphological-hydrogeological features. Lineaments tend to be less detectable in discharge areas (lowland, wide and flat valleys) in contrast to the high density in recharge areas (highland narrow-mountainous ravines). In addition, the presence of a stream network in the former can act as a recharge source to the underlain karstic groundwater system. Consequently, boreholes that are in the discharge areas with a lower density of lineaments often produce high yield. For recharge areas with a high density of lineaments, a good correlation is found between lineament density and borehole specific capacity. [less ▲]

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See detailInnovation dans l'efficacité de la gestion administrative du personnel
Lisein, Olivier ULg

Conference given outside the academic context (2004)

Ce workshop interroge la valeur ajoutée des innovations technologiques au niveau de l'efficacité de la gestion administrative du personnel. A partir de l'exemple concret d'une entreprise liégeoise, il est ... [more ▼]

Ce workshop interroge la valeur ajoutée des innovations technologiques au niveau de l'efficacité de la gestion administrative du personnel. A partir de l'exemple concret d'une entreprise liégeoise, il est montré comment le recours à des solutions informatiques dédiées permet d'offrir une nouvelle gamme de services aux salariés, de confier aux salariés eux-mêmes la gestion d'une série de tâches relatives à leur dossier administratif et d'ainsi permettre au service du personnel d'avoir plus de temps pour mener à bien des initiatives de gestion des ressources humaines plutôt que d'administration du personnel. L'atelier a aussi pour but de questionner les meilleurs moyens de recourir à de telles solutions technologiques, notamment en fonction des publics cibles et des utilisateurs concernés par ce type d'innovations: cadres, employés, ouvriers, département RH, etc. [less ▲]

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See detailLa carte des territoires paysagers de Wallonie
Droeven, Emilie ULg; Kummert, Magali

Poster (2004, December)

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See detailMarché de services en vue de simuler l’impact, sur le régime hydrologique de l’Ourthe, de l’implantation de bassins écrêteurs dans les vallées de l’Ourthe et de l’Amblève (MOHICAN)
Deliège, Jean-François ULg; Bourouag, Mohamed ULg; Dautrebande, Sylvia et al

Report (2004)

Le modèle MOHICAN (« Modèle hydrologique intégré pour le calcul des crues et l’amplitude des niveaux d’eau ») a été développé conjointement par l’Université de Liège (Laboratoire d’hydrodynamique ... [more ▼]

Le modèle MOHICAN (« Modèle hydrologique intégré pour le calcul des crues et l’amplitude des niveaux d’eau ») a été développé conjointement par l’Université de Liège (Laboratoire d’hydrodynamique appliquée, Laboratoire de Géologie de l’Ingénieur et d’Hydrogéologie, Centre d’Etude et de Modélisation de l’environnement) et la Faculté Universitaire des Sciences Agronomiques de Gembloux (Unité d’Hydraulique agricole) pour le compte et avec le support du Ministère de l’Equipement et des Transports, Service d’Etudes Hydrologiques (MET/SETHY) de la Région wallonne. En 2004, le SETHY a demandé aux développeurs du projet de simuler l’impact sur le régime hydrologique de l’Ourthe, de bassins écrêteurs dans les vallées de l’Ourthe et de l’Amblève. Plus spécifiquement, les objectifs de l’étude étaient d’estimer l’efficacité réelle de ces bassins écrêteurs (Les Combes, 16.3 Mm³, Ourthe ; Gran Han, 15.0 Mm³, Ourthe ; Stoumont, 5.7 Mm³, Amblève) pour la diminution des débits de pointe et des hauteurs d’eau, en particulier lors de très grandes crues. Dans le cas des grandes crues testée, les simulations montrent clairement la grande sensibilité des résultats aux différentes combinaisons possibles des bassins écrêteurs et surtout aux lois de gestion à utiliser pour ces bassins : il n’existe pas une loi générale qui donne un résultat maximal pour tous les types de grandes crues, et la gestion combinée des bassins est délicate. [less ▲]

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