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See detailPrélèvement d'organes après euthanasie: expérience belge
Ysebaert, Dirk; Detry, Olivier ULg; Squifflet, Jean-Paul ULg et al

Conference (2008, October 10)

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See detailThe blue man: an anusual happy end of a spontaneous rupture of a coronary artery
Moonen, Marie ULg; Hanssen, Michel ULg; Radermecker, Marc ULg et al

in European Journal of Cardio - Thoracic Surgery (2008), 34(6), 1265-1267

We reported the case of spontaneous rupture of a coronary artery. It was a 56-year-old man admitted for dyspnoea and anterior thoracic pain. The most striking feature on physical examination was the ... [more ▼]

We reported the case of spontaneous rupture of a coronary artery. It was a 56-year-old man admitted for dyspnoea and anterior thoracic pain. The most striking feature on physical examination was the marked cyanosis of his face, upper part of the thorax and the upper limb. The patient was haemodynamically unstable with tachycardia and hypotension. Cardiac tamponade was confirmed by echocardiography and computed tomography of the thorax. The patient was transferred for surgery. Emergency sternotomy revealed pericardial bloody effusion and a continuous bleeding around the posterior interventricular artery. No other per-operative findings could explain the haemopericardium. Haemostasis was obtained by a suture of the bleeding coronary artery. [less ▲]

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See detailBiogeochemical Investigations of Coccolithophore Blooms along the Continental Margin of the Northern Bay of Biscay: Highlights of the PEACE Project
Chou, Lei; Harlay, Jérôme ULg; De Bodt, Caroline et al

Poster (2008, October 06)

Recent studies have demonstrated that changing ocean chemistry due to ocean acidification poses a growing threat for marine organisms such as corals, coccolithophores and many others that form calcareous ... [more ▼]

Recent studies have demonstrated that changing ocean chemistry due to ocean acidification poses a growing threat for marine organisms such as corals, coccolithophores and many others that form calcareous skeletons. Its biogeochemical feedbacks and impact on the oceanic carbon cycle are yet to be quantified. Coccolithophores are the major calcifying phytoplankton in the sub-polar and temperate regions of the world’s ocean. They produce furthermore transparent exopolymer particles (TEP), which are known to promote aggregate formation. Combined with the CaCO3 ballast effect, large-scale coccolithophore blooms could thus contribute to the export of organic carbon to deep waters on relatively short time scales. During the Belgian PEACE project, we have conducted yearly interdisciplinary biogeochemical surveys, assisted by remote sensing, along the continental margin of the northern Bay of Biscay where coccolithophore blooms dominated by Emiliania huxleyi are frequently and recurrently observed (Figure 1). Rates of various processes governing the coccolithophore ecosystem dynamics have been determined and associated biogeochemical parameters analysed. The overall objective is to evaluate the role in climate regulation of calcification, primary production and export processes during coccolithophore blooms. Here we report the principal results obtained during the 2006 campaign. [less ▲]

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See detailShakespeare à l'école
Delrez, Marc ULg

Speech/Talk (2008)

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See detailAnalysis of climatic conditions of wildfires in Belgium with an automatic daily atmospheric circulation patterns classification
Erpicum, Michel ULg; Fettweis, Xavier ULg; Mabille, Georges ULg

Conference (2008, October 02)

An automatic daily atmospheric circulation patterns classification was built using the geopotential heights of 850 hPa level from the ECMWF (re)analysis over the period 1958-2007. The classification is ... [more ▼]

An automatic daily atmospheric circulation patterns classification was built using the geopotential heights of 850 hPa level from the ECMWF (re)analysis over the period 1958-2007. The classification is based on a similarity index between two 850hPa geopotential maps centred on Belgium, taking into account the slope difference between both daily geopotential surfaces as well as the absolute geopotential difference between both surfaces. Wildfire occurrences are analysed in April and September together with monthly frequencies and persistences of daily atmospheric circulation patterns types as well as with monthly variability of weather climate conditions. [less ▲]

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See detailLes bénéfices de l'apprentissage d'application web 2.0 pour un public fragilisé
Géron, Stéphanie ULg; Jacquet, Maud ULg

Conference (2008, October 02)

Application web 2.0 et public fragilisé : présentation d'un module sur le traitement de texte en ligne dans le cadre du projet PMTIC

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See detailIntegration of Accurate 2D Inundation Modelling, Vector Land Use Database and Economic Evaluation
Ernst, Julien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

Poster (2008, October 02)

Within the global framework of the climate change, according to most Regional Climate Mod-els the maximum peak discharges in river will increase in importance and frequency. Therefore the people will have ... [more ▼]

Within the global framework of the climate change, according to most Regional Climate Mod-els the maximum peak discharges in river will increase in importance and frequency. Therefore the people will have to face worst inundation conditions. In order to protect themselves from the increasing flood risk, the communities have to draw up suitable flood protection measures. The selection and the evaluation among the different possible flood mitigation measures requires developing decision-support system (DSS). This sys-tem has to take into consideration parameters such as hydraulic, economic, social or environmental. This pa-per focuses on the integration between two components of the DSS, namely the evaluation of the economic impacts of floods and the hydrodynamic modelling. The hydraulic simulations are conducted by means of WOLF 2D flow modelling system and provide as an output high resolution flood maps detailing the distribu-tion of water depth and flow velocity in the floodplains. The integration is ensured by the use of very accurate geographic databases and an automated procedure which makes the most of geomatic methods. The paper de-tails the application of the integrated assessment procedure for a case study along the river Ourthe located in the Meuse basin (Belgium). Moreover, possibilities of validation of the economic damage evaluation proce-dure are investigated by comparing computation results with real damage data recorded by the Belgian Disas-ter Fund after several major flood events (2003, 2002, 1995, and 1993). [less ▲]

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See detailCoRoT Measures Solar-Like Oscillations and Granulation in Stars Hotter Than the Sun
Michel, Eric; Baglin, Annie; Auvergne, Michel et al

in Science (2008), 322

Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the ... [more ▼]

Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars. [less ▲]

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See detailDriving and damping mechanisms in hybrid pressure-gravity modes pulsators
Dupret, Marc-Antoine ULg; Miglio, Andrea ULg; Montalban Iglesias, Josefa ULg et al

in Journal of Physics: Conference Series (2008), 118

We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid beta Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity ... [more ▼]

We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid beta Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity of the driving mechanism to the heavy elements mixture (mainly the iron abundance), we show that the characteristics of the propagation and evanescent regions play also a major role, determining the extension of the stable gap in the frequency domain between the unstable low order pressure and high order gravity modes. Finally, we consider the case of hybrid delta Sct-gamma Dor pulsators. [less ▲]

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See detailModeling pulsations in hot stars with winds
Noels-Grötsch, Arlette ULg; Dupret, Marc-Antoine ULg; Godart, Mélanie ULg

in Journal of Physics: Conference Series (2008), 118

The interaction pulsation/mass loss takes different aspects. Pulsations can trigger mass loss as in LBVs and Miras; on the other hand, mass loss can modify the driving conditions within the stars. But the ... [more ▼]

The interaction pulsation/mass loss takes different aspects. Pulsations can trigger mass loss as in LBVs and Miras; on the other hand, mass loss can modify the driving conditions within the stars. But the most spectacular aspect is the effect on stellar models which, in turn, opens a royal way to asteroseismology to test physical conditions inside massive stars, such as the extent of convective cores or the appearance of new driving mechanisms. We start with a discussion on MS stars and their strange mode instabilities. We then move on to the excitation of the LBV phenomenon. WR stars and the newly observed MOST period in WR123 are discussed in view of the power of asteroseismology. We then turn to B supergiants, in particular HD163899, and show how asteroseismology can really probe convection, semiconvection and mass loss. [less ▲]

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See detailEffect of mass loss on the driving of g-modes in B supergiant stars
Godart, Mélanie ULg; Noels-Grötsch, Arlette ULg; Dupret, Marc-Antoine ULg

in Journal of Physics: Conference Series (2008), 118

MOST has detected p and g-modes in the B supergiant star HD163899. Saio et al. (2006) have explained the driving of g-modes in a post main sequence star by the presence of a convective shell which ... [more ▼]

MOST has detected p and g-modes in the B supergiant star HD163899. Saio et al. (2006) have explained the driving of g-modes in a post main sequence star by the presence of a convective shell which prevents some modes from entering the damping radiative core. We show that this scenario depends on the evolution of the star, with or without mass loss. If the mass loss rate is high enough, the convective shell disappears and all the g-modes are stable. [less ▲]

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See detailA seismic approach to testing different formation channels of subdwarf B stars
Hu, Haili; Dupret, Marc-Antoine ULg; Aerts, C. et al

in Astronomy and Astrophysics (2008), 490

Context: There are many unknowns in the formation of subdwarf B stars. Different formation channels are considered to be possible and to lead to a variety of helium-burning subdwarfs. All seismic models ... [more ▼]

Context: There are many unknowns in the formation of subdwarf B stars. Different formation channels are considered to be possible and to lead to a variety of helium-burning subdwarfs. All seismic models to date, however, assume that a subdwarf B star is a post-helium-flash-core surrounded by a thin inert layer of hydrogen. Aims: We examine an alternative formation channel, in which the subdwarf B star originates from a massive (>~2 M[SUB]o[/SUB]) red giant with a non-degenerate helium-core. Although these subdwarfs may evolve through the same region of the log g-T_eff diagram as the canonical post-flash subdwarfs, their interior structure is rather different. We examine how this difference affects their pulsation modes and whether it can be observed. Methods: Using detailed stellar evolution calculations we construct subdwarf B models from both formation channels. The iron accumulation in the driving region due to diffusion, which causes the excitation of the modes, is approximated by a Gaussian function. The pulsation modes and frequencies are calculated with a non-adiabatic pulsation code. Results: A detailed comparison of two subdwarf B models from different channels, but with the same log g and T_eff, shows that their mode excitation is different. The excited frequencies are lower for the post-flash than for the post-non-degenerate subdwarf B star. This is mainly due to the differing chemical composition of the stellar envelope. A more general comparison between two grids of models shows that the excited frequencies of most post-non-degenerate subdwarfs cannot be well-matched with the frequencies of post-flash subdwarfs. In the rare event that an acceptable seismic match is found, additional information, such as mode identification and log g and T_eff determinations, allows us to distinguish between the two formation channels. [less ▲]

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See detailTime-dependent convection study of the driving mechanism in the DBV white dwarfs
Dupret, Marc-Antoine ULg; Quirion, P. O.; Fontaine, G. et al

in Journal of Physics: Conference Series (2008), 118

We apply for the first time time-dependent convection (TDC) models to the study of the driving mechanism of the Pulsating DB (V777 Herculis) white dwarfs. From the blue to the red edge of the instability ... [more ▼]

We apply for the first time time-dependent convection (TDC) models to the study of the driving mechanism of the Pulsating DB (V777 Herculis) white dwarfs. From the blue to the red edge of the instability strip of these stars, TDC appears to play a central role in the driving. Around the blue edge, the convection adapts quasi-instantaneously to the oscillations, so that TDC must be included in the models. For the first time, we show that the red edge of the DB instability strip is successfully obtained with a TDC treatment, especially thanks to the terms due to the turbulent pressure variations, while it is not reproduced with frozen convection models. [less ▲]

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See detailThe driving mechanism of roAp stars
Dupret, Marc-Antoine ULg; Théado, S.; Noels-Grötsch, Arlette ULg

in Journal of Physics: Conference Series (2008), 118

We analyse in detail the driving mechanism of roAp stars and present the theoretical instability strip predicted by our models with solar metallicity. A particular attention is given to the interpretation ... [more ▼]

We analyse in detail the driving mechanism of roAp stars and present the theoretical instability strip predicted by our models with solar metallicity. A particular attention is given to the interpretation of the role played by the different eigenfunctions in the stabilization of the modes at the red edge of the instability strip. The gradient of temperature in the H[SUB]I[/SUB] opacity bump appears to play a major role in this context. We also consider the particular and complex role played by the shape of the eigenfunctions (location of the nodes, ...). [less ▲]

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See detailModeling the excitation of acoustic modes in alpha Centauri A
Samadi, R.; Belkacem, Kevin ULg; Goupil, M. J. et al

in Astronomy and Astrophysics (2008), 489

From different seismic observations we infer the energy supplied per unit of time by turbulent convection to the acoustic modes of alpha Centauri A (HD 128620), a star that is similar but not identical to ... [more ▼]

From different seismic observations we infer the energy supplied per unit of time by turbulent convection to the acoustic modes of alpha Centauri A (HD 128620), a star that is similar but not identical to the Sun. The inferred rates of energy supplied to the modes (i.e. mode excitation rates) are found to be significantly higher than in the Sun. They are compared with those computed with an excitation model that includes two sources of driving, the Reynolds stress contribution and the advection of entropy fluctuations. The model also uses a closure model, the Closure Model with Plumes (CMP hereafter), that takes the asymmetry between the up- and down-flows (i.e. the granules and plumes, respectively) into account. Different prescriptions for the eddy-time correlation function are also compared to observational data. Calculations based on a Gaussian eddy-time correlation underestimate excitation rates compared with the values derived from observations for alpha Centauri A. On the other hand, calculations based on a Lorentzian eddy-time correlation lie within the observational error bars. This confirms results in the solar case. Compared to the helioseismic data, those obtained for alpha Centauri A constitute an additional support for our model of excitation. We show that mode masses must be computed taking turbulent pressure into account. Finally, we emphasize the need for more accurate seismic measurements in order to distinguish between the CMP closure model and the quasi-normal approximation in the case of alpha Centauri A, as well as to confirm or not the need to include the excitation by the entropy fluctuations. [less ▲]

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See detailNulling interferometry: performance comparison between space and ground-based sites for exozodiacal disc detection
Defrere, Denis ULg; Absil, Olivier ULg; Coudé Du Foresto, V. et al

in Astronomy and Astrophysics (2008), 490

Context: Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions ... [more ▼]

Context: Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions such as ESA's Darwin or NASA's terrestrial planet finder (TPF). Besides paving the technological way to Darwin/TPF, the space-based infrared interferometers Pegase and FKSI (Fourier-Kelvin Stellar Interferometer) will be valuable scientific precursors. Aims: We investigate the performance of Pegase and FKSI for exozodiacal disc detection and compare the results with ground-based nulling interferometers. Methods: We used the GENIEsim software (Absil et al. 2006, A&A, 448, 787) which was designed and validated to study the performance of ground-based nulling interferometers. The software has been adapted to simulate the performance of space-based nulling interferometers by disabling all atmospheric effects and by thoroughly implementing the perturbations induced by payload vibrations in the ambient space environment. Results: Despite using relatively small telescopes (<=0.5 m), Pegase and FKSI are very efficient for exozodiacal disc detection. They are capable of detecting exozodiacal discs 5 and 1 time respectively, as dense as the solar zodiacal cloud, and they outperform any ground-based instrument. Unlike Pegase, FKSI can achieve this sensitivity for most targets of the Darwin/TPF catalogue thanks to an appropriate combination of baseline length and observing wavelength. The sensitivity of Pegase could, however, be significantly boosted by considering a shorter interferometric baseline length. Conclusions: Besides their main scientific goal (characterising hot giant extrasolar planets), the space-based nulling interferometers Pegase and FKSI will be very efficient in assessing within a few minutes the level of circumstellar dust in the habitable zone around nearby main sequence stars down to the density of the solar zodiacal cloud. These space-based interferometers would be complementary to Antarctica-based instruments in terms of sky coverage and would be ideal instruments for preparing future life-finding space missions. [less ▲]

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See detailErratum to "Accurate Spitzer infrared radius measurement for the hot Neptune GJ 436b"
Gillon, Michaël ULg; Demory, B*-O; Barman, T. et al

in Astronomy and Astrophysics (2008), 490

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See detailTW ;Hydrae: evidence of stellar spots instead of a Hot Jupiter
Huélamo, N.; Figueira, P.; Bonfils, X. et al

in Astronomy and Astrophysics (2008), 489

Context: TW Hya is a classical T Tauri star that shows significant radial-velocity variations in the optical regime. These variations have been attributed to a 10 M_Jup planet orbiting the star at 0.04 AU ... [more ▼]

Context: TW Hya is a classical T Tauri star that shows significant radial-velocity variations in the optical regime. These variations have been attributed to a 10 M_Jup planet orbiting the star at 0.04 AU. Aims: The aim of this letter is to confirm the presence of the giant planet around TW Hya by (i) testing whether the observed RV variations can be caused by stellar spots and (ii) analyzing new optical and infrared data to detect the signal of the planet companion. Methods: We fitted the RV variations of TW Hya using a cool spot model. In addition, we obtained new high-resolution optical & infrared spectra, together with optical photometry of TW Hya and compared them with previous data. Results: Our model shows that a cold spot covering 7% of the stellar surface and located at a latitude of 54° can reproduce the reported RV variations. The model also predicts a bisector semi-amplitude variation <10 m s[SUP]-1[/SUP], which is less than the errors of the RV measurements discussed in Setiawan et al. (2008, Nature, 451, 38). The analysis of our new optical RV data, with typical errors of 10 m s[SUP]-1[/SUP], shows a larger RV amplitude that varies depending on the correlation mask used. A slight correlation between the RV variation and the bisector is also observed although not at a very significant level. The infrared H-band RV curve is almost flat, showing a small variation (<35 m s[SUP]-1[/SUP]) that is not consistent with the published optical orbit. All these results support the spot scenario rather than the presence of a hot Jupiter. Finally, the photometric data shows a 20% (peak to peak) variability, which is much larger than the 4% variation expected for the modeled cool spot. The fact that the optical data are correlated with the surface of the cross-correlation function points towards hot spots as being responsible for the photometric variability. Conclusions: We conclude that the best explanation for the RV signal observed in TW Hya is the presence of a cool stellar spot and not an orbiting hot Jupiter. Based on observations taken at the VLT (Paranal), under programs 280.C-5064(A) and 075.C-0202(A), and with the CORALIE spectrograph and EulerCAM both at the Euler Swiss telescope (La Silla). [less ▲]

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See detailErratum: "the Transit Light Curve Project. VII. The Not-So Exoplanet HAT-P-1B" (2007, AJ, 134, 1707)
Winn, Joshua N; Holman, Matthew J; Bakos, Gaspar Á et al

in Astronomical Journal (The) (2008), 136

Two of the midtransit times that were given in Table 3 of Winn et al. 2007 (AJ, 134, 1707-1712) are incorrect. The first entry was incorrect because a trend in the out-of-transit flux had not been removed ... [more ▼]

Two of the midtransit times that were given in Table 3 of Winn et al. 2007 (AJ, 134, 1707-1712) are incorrect. The first entry was incorrect because a trend in the out-of-transit flux had not been removed as described in the text. The sixth entry gave an incorrect epoch, and a midtransit time that was too small by one orbital period, because of a rounding error in the computer code that generated the table. The corrected times are given below in a revised version of Table 3. With these revisions, the ephemeris parameters given in the text following Equation (4) are changed slightly, to T[SUB]c[/SUB] (0) = 2453997.79252(32) (HJD) and P = 4.46543(13) days, where the numbers in parentheses indicate the 1sigma uncertainty in the last two digits. We note that a more precise ephemeris has been calculated by Johnson et al. (2008), based on a combination of the data presented here and more recent transit observations. [less ▲]

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