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See detailTransiting exoplanets from the CoRoT space mission . VI. CoRoT-Exo-3b: the first secure inhabitant of the brown-dwarf desert
Deleuil, M.; Deeg, H. J.; Alonso, R. et al

in Astronomy and Astrophysics (2008), 491

Context: The CoRoT space mission routinely provides high-precision photometric measurements of thousands of stars that have been continuously observed for months. Aims: The discovery and characterization ... [more ▼]

Context: The CoRoT space mission routinely provides high-precision photometric measurements of thousands of stars that have been continuously observed for months. Aims: The discovery and characterization of the first very massive transiting planetary companion with a short orbital period is reported. Methods: A series of 34 transits was detected in the CoRoT light curve of an F3V star, observed from May to October 2007 for 152 days. The radius was accurately determined and the mass derived for this new transiting, thanks to the combined analysis of the light curve and complementary ground-based observations: high-precision radial-velocity measurements, on-off photometry, and high signal-to-noise spectroscopic observations. Results: CoRoT-Exo-3b has a radius of 1.01 ± 0.07 R_Jup and transits around its F3-type primary every 4.26 days in a synchronous orbit. Its mass of 21.66 ± 1.0 M_Jup, density of 26.4 ± 5.6 g cm[SUP]-3[/SUP], and surface gravity of logg = 4.72 clearly distinguish it from the regular close-in planet population, making it the most intriguing transiting substellar object discovered so far. Conclusions: With the current data, the nature of CoRoT-Exo-3b is ambiguous, as it could either be a low-mass brown-dwarf or a member of a new class of ``superplanets''. Its discovery may help constrain the evolution of close-in planets and brown-dwarfs better. Finally, CoRoT-Exo-3b confirms the trend that massive transiting giant planets (M >= 4 M_Jup) are found preferentially around more massive stars than the Sun. The CoRoT space mission, launched on December 27th 2006, has been developed and is operating by CNES, with the contribution of Austria, Belgium, Brasil, ESA, Germany and Spain. The first CoRoT data will be available to the public in February 2009 from the CoRoT archive: http://idoc-corot.ias.u-psud.fr/ Table of the COROT photometry is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/491/889 [less ▲]

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See detailProblems and prospects in stellar physics
Dupret, Marc-Antoine ULg

in Communications in Asteroseismology (2008), 157

Main difficulties and uncertainties in stellar physics originate in the modelling of convection, microscopic and macroscopic transport mechanisms and rotation. I consider each of these physical aspects ... [more ▼]

Main difficulties and uncertainties in stellar physics originate in the modelling of convection, microscopic and macroscopic transport mechanisms and rotation. I consider each of these physical aspects, with a particular attention to their possible probe by asteroseismology. Another important question about opacities is considered by Montalban & Miglio (2008). [less ▲]

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See detailElaboration of Magnetic Nanodots by Nanosphere Lithography : a Computerized Method for Order Quantification
Colson, Pierre ULg; Cloots, Rudi ULg; Henrist, Catherine ULg

Conference (2008, December 01)

Nanosphere lithography (NSL) is an ideal inexpensive fabrication tool for producing regular, nearly homogenous arrays of nanoparticules with different sizes. There are many different methods for the ... [more ▼]

Nanosphere lithography (NSL) is an ideal inexpensive fabrication tool for producing regular, nearly homogenous arrays of nanoparticules with different sizes. There are many different methods for the fabrication of the latex monolayer based on electrophoresis, the controlled evaporation of a solvent from the suspension containing latex particles, spincoating etc… We focused our work on this last method. The main problem with formation of 2D latex monolayers is that there are always a high number of different structural defects such as: point defects (vacancies), line defects (dislocations) and also many disordered areas. The influence of the different spincoating parameters on the amount of defects was determined by image analysis of SEM micrographies from the different samples. FePt and Co films were deposited onto quartz substrates through the polystryrene monolayers by magnetron sputtering. The nanopsheres were removed by sonication in toluene. Post-deposition annealing treatment was performed under reductive atmosphere for the FePt nanodots in order to transform the as-deposited chemically disoredered face-centered cubic (fcc) structure into the chemically ordered face-centered tetragonal (fct) phase (L10-phase). DRX , SEM and MFM analysis were performed on the different samples. [less ▲]

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See detailRecent results from HST and ground-based observations of Saturn's aurora
Grodent, Denis ULg; Stallard, T.; Gérard, Jean-Claude ULg et al

Conference (2008, December 01)

Current observations of Saturn's aurora performed from Earth-orbit with HST and ground based instruments more than complement the in situ measurements obtained by the Cassini spacecraft. These remote ... [more ▼]

Current observations of Saturn's aurora performed from Earth-orbit with HST and ground based instruments more than complement the in situ measurements obtained by the Cassini spacecraft. These remote observations focus on two spectral windows revealing different facets of the same auroral phenomenon. The auroral photons captured in the ultraviolet bandwidth result from direct impact excitation of H and H2 by charged particles accelerated along magnetic field lines, while the thermal infrared emission involves additional steps in order to produce hot H3+ from the auroral energy. Each spectral window presents its own advantages. The high spatial and temporal resolution of the recent UV images obtained with HST make it possible to discriminate auroral sub-structures, such as short lived arcs and spots, and to map them into the magnetosphere where they can be associated with in situ observations. Infrared high resolution spectroscopy and emission-line imaging from ground observatories (IRTF, UKIRT) have more modest spatial resolution; however they recently pinned down emissions barely observed in the UV. Furthermore, they offer a direct measurement of the ion wind velocities in the auroral ionosphere. These ion flow patterns might then be used to untangle the origin of the auroral particles. The complementarity of observations obtained in the UV and IR bandwidths provides a powerful tool to study the auroral mechanisms in the Kronian magnetosphere and the atmospheric response to the auroral input. [less ▲]

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See detailThe variation of different components of Jupiter's auroral emission
Nichols, J.; Clarke, J.; Gérard, Jean-Claude ULg et al

Conference (2008, December 01)

In this paper we use the extensive HST data set obtained over two month-long campaigns in 2007 to determine the long term variability of the different components of Jupiter's auroras. We define three ... [more ▼]

In this paper we use the extensive HST data set obtained over two month-long campaigns in 2007 to determine the long term variability of the different components of Jupiter's auroras. We define three regions on the planet's disc, i.e. the main oval, the low latitude, and high latitude auroras, and extract the UV auroral power emitted therefrom. The high latitude region was also further divided into the polar inner and polar outer regions. We discuss the temporal variation of these parameters with reference to the auroral morphology and estimated solar wind conditions projected to Jupiter's orbit from data obtained at Earth orbit. We show that the auroral morphology was very different between the first and second campaigns. In the first campaign the emitted power originated mainly from the main oval and the high latitude regions, which roughly correlated, and exhibited enhancements that are suggested to be associated with compression regions. In the second campaign the high latitude and main oval auroras were generally dimmer overall and less variable, while the low latitude region was populated with bright, patchy emission. We show that a particular auroral morphology is probably associated specifically with compression regions, i.e. over longitudes greater than approx. 180 degrees the main oval is bright and located approx. 1 degree poleward of its previous location, while over smaller longitudes the main oval is not bright or well defined. Instead there is bright emission originating from the contiguous poleward region in the afternoon/dusk sector where bright, sometimes multiple arcs form. It remains unclear, however, whether this state is a response to the initial shock or some other event within the rapidly-varying compression regions. We also show that the dawn storm events, typically associated with intense dawn side main oval auroras also result in the brightening of the high latitude auroras, even to the very highest latitude components, which presumably map to a very different region of the magnetosphere. However, apart from the dawn storms and bright poleward arcs in the afternoon/dusk sector, the power emitted from the poleward auroras is generally uncorrelated with that of the main oval. [less ▲]

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See detailDynamique de la végétation d'altitude en Afrique centrale atlantique depuis 17 000 ans BP. Analyses préliminaires de la carotte de Bambili (Nord-Ouest du Cameroun).
Assi Kaudjhis, Chimène Cloche M ULg; LEZINE, ANNE - MARIE; Roche, Emile ULg

in Geo-Eco-Trop : Revue Internationale de Géologie, de Géographie et d'Ecologie Tropicales (2008), 32

This article presents the preliminary results of pollen analyses carried out on a 13.5m long core taken from the shore of the crater lake of Bambili, Cameroon (05°56'11.9N; 10°14' 31.6E; 2273m alt.). This ... [more ▼]

This article presents the preliminary results of pollen analyses carried out on a 13.5m long core taken from the shore of the crater lake of Bambili, Cameroon (05°56'11.9N; 10°14' 31.6E; 2273m alt.). This allows us to reconstruct the history of montane forest ecosystems from Atlantic Central Africa since 17 000 years BP. Well diversified microflora, show several changes. At the base of the pollen sequence, the vegetation is dominated by herbaceous plant populations such as Poaceae, associated with “dry” plant types from Amaranthaceae/ Chenopodiaceae families and tree and shrub plant types from savannas and open forest formations types such as Gnidia, Lannea, Combretaceae, Cussonia… The montane forest expansion started from 14 080cal BP with the appearance of the pioneer taxon Myrica. This taxon is followed by Schefflera, Podocarpus, Olea, Syzygium… which widely expanded in the immediate surroundings of the lake from 12 310 to 4 590 cal BP. After this date, the montane forest was strongly reduced. However a short phase of forest regrowth is recorded around 2000 BP during which Schefflera dominated the forest assemblage. [less ▲]

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See detailThe Ultraviolet Spectrograph (UVS) on Juno
Gladstone, G. R.; Persyn, S.; Eterno, J. et al

Conference (2008, December 01)

Juno, a NASA New Frontiers mission, plans for launch in August 2011, a 5-year cruise (including a flyby of Earth in October 2013 for a gravity boost), and 14 months around Jupiter after arriving in August ... [more ▼]

Juno, a NASA New Frontiers mission, plans for launch in August 2011, a 5-year cruise (including a flyby of Earth in October 2013 for a gravity boost), and 14 months around Jupiter after arriving in August 2016. The spinning (2 RPM), solar-powered Juno will study Jupiter from a highly elliptical orbit, in which the spacecraft (for about 6 hours once every 11 days) dives down over the north pole, skims the outermost atmosphere, and rises back up over the south pole. This orbit allows Juno avoid most of the intense particle radiation surrounding the planet and provides an excellent platform for investigating Jupiter's polar magnetosphere. Part of the exploration of Jupiter's polar magnetosphere will involve remote sensing of the far-ultraviolet H and H2 auroral emissions, plus gases such as methane and acetylene which add their absorption signature to the H2 emissions. This hydrocarbon absorption can be used to estimate the energy of the precipitating electrons; since more energetic electrons penetrate deeper into the atmosphere and the UV emissions they produce will show more absorption. Juno will carry an Ultraviolet Spectrograph (UVS) to make spectral images of Jupiter's aurora. UVS is a UV imaging spectrograph sensitive to both extreme and far ultraviolet emissions in the 70-205~nm range that will characterize the morphology and spectral nature of Jupiter's auroral emissions. Juno UVS consists of two separate sections: a dedicated telescope/spectrograph assembly and a vault electronics box. The telescope/spectrograph assembly contains a telescope which feeds a 0.15-m Rowland circle spectrograph. The telescope has an input aperture 40à 40~mm2 and uses an off-axis parabolic primary mirror. A flat scan mirror situated at the front end of the telescope (used to target specific auroral features at up to ±30° perpendicular to the Juno spin plane) directs incoming light to the primary. The light is then focused onto the spectrograph entrance slit, which has a 'dog- bone' shape 6° long, in three 2° sections of 0.2°, 0.05°, and 0.2° width (projected onto the sky). Light entering the slit is dispersed by a toroidal grating which focuses the UV bandpass onto a curved microchannel plate (MCP) cross delay line (XDL) detector with a solar blind UV- sensitive CsI photocathode, which makes up the instrument's focal plane. Tantalum shielding surrounds the detector assembly to protect the detector and the adjacent detector electronics from high-energy electrons. The main electronics box is located in the Juno vault. Inside are two redundant high-voltage power supplies (HVPS), two redundant low-voltage power supplies, the command and data handling (C&DH) electronics, heater/actuator activation electronics, scan mirror electronics, and event processing electronics. An overview of the UVS design and scientific performance will be presented. [less ▲]

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See detailCoordinated measurements of auroral processes at Saturn from the Cassini spacecraft and HST
Mitchell, D. G.; Kurth, William; Hospodarsky, G. B. et al

Conference (2008, December 01)

One of the primary Cassini mission objectives at Saturn is to characterize Saturn's aurora-its spatial morphology, associated particle energization, radio wave generation, and magnetospheric currents ... [more ▼]

One of the primary Cassini mission objectives at Saturn is to characterize Saturn's aurora-its spatial morphology, associated particle energization, radio wave generation, and magnetospheric currents, relationship with solar wind pressure and magnetic field, and its large scale mapping to the magnetosphere. By design, the Cassini orbital tour included high inclination and low periapsis orbits late in the prime mission specifically to address many of these topics. In this presentation, we will provide a snapshot of the current state of our investigation into the relationship between magnetospheric measurements of particles and fields, and the aurora. For in situ data, we will show measurements of upward traveling light ion conics (~30 keV to 200 keV), often accompanied by electron beams (<20 keV to ~1 MeV) and enhanced broadband noise (10 Hz to a few kHz), throughout the outer magnetosphere on field lines that nominally map from well into the polar cap (dipole L > 50) to well into the closed field region (dipole L < 10). Sometimes the particle phenomena and the broadband noise occur in pulses of roughly five-minute duration, separated by tens of minutes. At other times they are relatively steady over an hour or more. Magnetic signatures associated with some of the pulsed events are consistent with field aligned current structures. Correlative observations of solar wind (Cassini) and aurora (HST) have established a strong relationship between solar wind pressure and auroral activity (brightness) (Crary et al., Nature, 2005; Clarke et al., JGR, 2008). A similar correspondence between bright auroral arcs and ring current ion acceleration will be shown here. So while some auroral forms seem to be associated with the open/closed field boundary (i.e. in the cusp-Bunce et al., JGR, 2008), we also demonstrate that under some magnetospheric conditions for which protons and oxygen ions are accelerated once per Saturn magnetosphere rotation at a preferred local time between midnight and dawn, simultaneous auroral observations by the HST reveal a close correlation between these dynamical magnetospheric events and dawn-side transient auroral brightenings. Likewise, many of the recurrent energetic neutral atom enhancements coincide closely with bursts of Saturn kilometric radiation, again suggesting a linkage with high latitude auroral processes. Finally, we will show some intriguing results of auroral movie sequences from the Cassini UVIS instrument with corresponding ring current movies from the Magnetospheric Imaging Instrument Ion and Neutral Camera (MIMI/INCA). [less ▲]

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See detailFirst asteroseismic results from CoRoT
Michel, Eric; Baglin, A.; Weiss, W. W. et al

in Communications in Asteroseismology (2008), 156

About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first ... [more ▼]

About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first results to illustrate how these data of unprecedented quality shed a new light on the field of stellar seismology. [less ▲]

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See detailOpen magnetic flux and magnetic flux closure during sawtooth events
Hubert, Benoît ULg; Milan, S. E.; Grocott, A. et al

in Geophysical Research Letters (2008), 35

We use IMAGE-FUV observations of the polar aurora and measurements of the ionospheric convection from the SuperDARN radar network to study several sawtooth events previously reported in the literature. We ... [more ▼]

We use IMAGE-FUV observations of the polar aurora and measurements of the ionospheric convection from the SuperDARN radar network to study several sawtooth events previously reported in the literature. We estimate the amount of open magnetic flux in the Earth magnetosphere during a significant part of these sawtooth intervals as well as the magnetic flux opening and closure rates, that is, the dayside and nightside reconnection rates. We find that during the sawtooth intervals the magnetosphere is highly loaded with open flux as a result of the strongly southward IMF carried by the solar wind during these intervals. The magnetosphere tries to relax to a less loaded configuration through a sequence of substorm expansions. However, these substorms do not necessarily evolve to their end before reintensification of nightside reconnection occurs in response to continued loading of the magnetosphere on the dayside. [less ▲]

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See detailNeutral Ion Coupling Explorer satellite measurements of thermospheric composition, winds and temperatures.
Mende, S. B.; Immel, T. J.; England, S. et al

Conference (2008, December 01)

A new Small Explorer mission, the Neutral Ion Coupling Explorer (NICE) mission, was selected for study by NASA to specifically address neutral ion coupling in the Earth's atmosphere. The main goal of NICE ... [more ▼]

A new Small Explorer mission, the Neutral Ion Coupling Explorer (NICE) mission, was selected for study by NASA to specifically address neutral ion coupling in the Earth's atmosphere. The main goal of NICE is to study neutral-ion coupling at low latitudes where the densest plasma in geospace is created and where a number of remarkable interactions between the plasma and neutral gas occur even in the relative absence of high-latitude forcing. NICE will study this region from a ~24 degree inclination 550 km circular orbit, residing entirely on closed magnetic field lines. The relatively fast precession of low-inclination orbit is favorable for frequent sampling of all local times for the determination of tidal structures. It is now widely recognized that the neutral thermosphere has a strong influence on the ionosphere and that Earth's ionosphere at quiet times is actually tidally dominated. The NICE concept is unique in simultaneously providing measurements of the parameters relevant to ion production and motion across the entire altitude range of the low-latitude ionosphere. The science payload consists of 3 remote sensing instruments viewing the atmospheric limb (1) a dual Doppler Fabry-Perot Interferometer (FP), scanning in altitude to measure neutral wind vector and temperature altitude profiles in the E- and F-regions, (2) a Far Ultraviolet (FUV) imager to measure daytime neutral composition and image the nighttime F-layer intensity distributions, and (3) an Extreme Ultraviolet (EUV) altitude profiler to retrieve daytime F-layer properties. In addition, an Ion Velocity Meter (IVM) measures the in-situ ion drifts. NICE will take advantage of an elegant choice of orbit and instrument viewing geometries to make coordinated and complementary observations at all local times, with optimal conjunction of measurements occurring near the equator. The observations are accompanied by a suite of advanced numerical models and analysis techniques. [less ▲]

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See detailL'audit social. Evaluez les risques sociaux de votre entreprise !
Robert, Frédéric; Maréchal, Benoît ULg

Conference (2008, December 01)

This seminar introduce to the practice of the social audit with regard to compagnies. On basis of a list of social risks with regard to labour law and social security law, the Authors illustrated how ... [more ▼]

This seminar introduce to the practice of the social audit with regard to compagnies. On basis of a list of social risks with regard to labour law and social security law, the Authors illustrated how these risks could be examined and evaluated in the case of a social audit of the company. [less ▲]

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See detailModélisation numérique des courants et tensions de contact dans des habitations
Lorphèvre, Raoul; Dular, Patrick ULg; V Sabariego, Ruth ULg et al

in Actes de 6ème conférence européenne sur les méthodes numériques en électromagnétisme (NUMELEC 2008) (2008, December)

Un modèle d’installation électrique d’habitation avec une ligne à haute tension est développé avec la méthode "Partial Element Equivalent" (PEEC). Cette étude a pour but de déterminer l’existence des ... [more ▼]

Un modèle d’installation électrique d’habitation avec une ligne à haute tension est développé avec la méthode "Partial Element Equivalent" (PEEC). Cette étude a pour but de déterminer l’existence des courants et tensions induits dans une maison et d’évaluer leur amplitude. Ensuite, nous caractérisons l’influence d’un réseau d’habitations et du type de prise de terre sur ceux-ci. Cette partie du travail nous permet d’obtenir un ensemble de facteurs influençant le niveau des courants induits. Ce papier montre qu’il est possible de déterminer des configurations pour minimiser ces courants dans un réseau d’habitations. [less ▲]

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See detailRapport d'évaluation du réseau "Mieux manger à l'école" de la Fondation Roi Baudouin
Van Hoye, Aurélie; Vandoorne, Chantal ULg

Report (2008)

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See detailL'image du mois. Myofibrosarcome dufémur distal
Netten, Alexandre ULg; Kurth, William ULg

in Revue Médicale de Liège (2008), 63(12), 697-698

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See detailEpidemiology and genetics of pituitary tumours
Beckers, Albert ULg

in Chanson, Philippe (Ed.) Best Practice Research - Clinical Endocrinology and Metabolism (2008)

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See detailSystèmes d'information de gestion modernes
Schyns, Michael ULg

Scientific conference (2008, December)

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