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See detailVers une démarche structurée de gestion forestière intégrée et participative
Rondeux, Jacques ULg

Learning material (2005)

This paper is aiming at presenting the main guidelines of a structured approach to an integrated forest management. Such a type of management that can be defined as being a concerted multipurpose ... [more ▼]

This paper is aiming at presenting the main guidelines of a structured approach to an integrated forest management. Such a type of management that can be defined as being a concerted multipurpose management takes into account numerous objectives that forest should be able to fulfil as well as the opinions of the actors involved in the forestry world. This approach consists of an evaluation and a subsequent multicriteria comparison of possible management alternatives. These management options and the expected consequences of their application on the future forest in terms of structure, composition and ability to meet all the expectations must be analyzed. In this respect scenario modellings are built, using simulations that suppose a good and very large knowledge of species autecology, site quality, level of biological quality. Various criteria and indicators are then used to assess the capacity of each alternative to achieve each defined and concerted objective. This is the starting point for comparisons between the management alternatives, based on the multicriteria decision-making technique, the so called ELECTRE III. This promising method has been tested in the context of a belgian pilot forest covering nearly 800 hectares in which foresters, private and public forest owners, hunters, naturalists, walkers and some other stakeholders are deeply involved. [less ▲]

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See detailAssessing the effects of compositional heterogeneity on phylogenomic analyses
Baurain, Denis ULg; Beiko, Robert G.; Ragan, Mark A.

Conference (2005, November 04)

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See detailFrançais de Belgique et travaux belges dans le TLF
Boutier, Marie-Guy ULg

Scientific conference (2005, November 04)

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See detailMédecine familiale et approche communautaire
Vanmeerbeek, Marc ULg

Conference (2005, November 02)

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

Article for general public (2005)

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See detailStars in the eyes, birth of a vocation ?
Nazé, Yaël ULg

in Astrophysics, and How to Attract Young People into Physics (2005, November 01)

It is generally difficult to interest people to sciences, especially physics. However, astronomy has a great power of fascination, and can thus be used to attract people into the scientific world. Here in ... [more ▼]

It is generally difficult to interest people to sciences, especially physics. However, astronomy has a great power of fascination, and can thus be used to attract people into the scientific world. Here in Liège, we are trying to develop several different aspects of astro-education: they will be detailed in this paper. For example, we organize interactive activities for primary schools, and also help high school students to consider a scientific career. Our undergraduate students also benefit from our experience: for example, they have the possibility to observe at a real observatory, they can train at ESA facilities,... The general public is also invited to discover astronomy and, through it, physics, thanks to several specific events. Finally, media, the links between the public and the researchers, are not forgotten: our astro-news service was specifically created for this purpose. [less ▲]

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See detailSignature of Saturn's auroral cusp: Simultaneous Hubble Space Telescope FUV observations and upstream solar wind monitoring
Gérard, Jean-Claude ULg; Bunce, Emma J; Grodent, Denis ULg et al

in Journal of Geophysical Research. Space Physics (2005), 110

Model simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the ... [more ▼]

Model simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the possibility that the FUV bright emissions sometimes observed near noon are associated with reconnection occurring at the dayside magnetopause, possibly pulsed, analogous to flux transfer events seen at the Earth. Pulsed reconnection at the low-latitude dayside magnetopause when the IMF is directed northward (antiparallel to Saturn's magnetic field lines) is expected to give rise to pulsed twin-vortical flows in the magnetosphere and hence to bipolar field-aligned currents centered in the vortical flows closing in ionospheric Pedersen current. In the case of southward IMF and high-latitude lobe reconnection the model predicts that the vortical flows are displaced poleward of the open-closed field line boundary with reversed field-aligned currents compared with the former case. During January 2004, a unique campaign took place during which magnetic field and plasma instruments on board the Cassini-Huygens spacecraft measured the in situ solar wind and embedded interplanetary magnetic field while the Hubble Space Telescope simultaneously observed the far ultraviolet aurora in Saturn's southern hemisphere. The IMF was highly structured during this interval. The electric potential at Cassini is estimated from solar wind magnetic field and velocity measurements for the case of low-latitude or lobe reconnection. We show that a dayside FUV signature of intense electron precipitation is found poleward of or along the main oval during a period of minor compression period when the dayside reconnection voltage is estimated to be ~30-100 kV. Overall, we find that the conceptual model of Bunce et al. (2005a) provides a good estimate of the UV brightness and power for the case of northward IMF but somewhat underestimates the power for the southward IMF case, except if the speed of the vortical flow is larger than its value in the nominal model. [less ▲]

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See detailA survey for gamma-ray emission from OB associations with INTEGRAL: some preliminary results
Leyder, Jean-Christophe ULg; Rauw, Grégor ULg

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

Recent studies indicated that there might be a correlation between OB associations and unidentified gamma-ray sources from the 3EG catalogue. Moreover, when extrapolating the fluxes measured by EGRET at ... [more ▼]

Recent studies indicated that there might be a correlation between OB associations and unidentified gamma-ray sources from the 3EG catalogue. Moreover, when extrapolating the fluxes measured by EGRET at energies higher than 100 MeV with a power-law down to the energy range of ISGRI, the expected count rates should be large enough to be detected with INTEGRAL. As most of these OB associations are located within the Galactic plane, they are being observed by INTEGRAL as part of the Core Program (CP) during both the Galactic Plane Scans (GPS) and the Galactic Center Deep Exposure (GCDE). Combining public and CP data, we have performed a survey for gamma-ray emission from OB associations and the first results are presented in this paper. [less ▲]

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See detailNon-adiabatic seismic study of the triple system DG Leo
Grigahcène, A.; Suárez, J. C.; Dupret, Marc-Antoine ULg et al

in Tidal Evolution and Oscillations in Binary Stars (2005, November 01)

The interest in studying multiple systems comes from the fact that they give a good number of constraints on their components. From the multiplicity we have constraints on mass and age. Moreover, if one ... [more ▼]

The interest in studying multiple systems comes from the fact that they give a good number of constraints on their components. From the multiplicity we have constraints on mass and age. Moreover, if one or more components of the system show oscillating properties as the DG Leo triple system, additional constraints provided by seismology can be obtained once the modes are identified. In this work, we consider an equilibrium model of the DG Leo system constrained by its multiplicity properties, we attempt to check our new Time Depending Convection treatment on the modes identification of the DG Leo system. [less ▲]

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See detailA spectroscopic investigation of the young open cluster IC 1805
De Becker, Michaël ULg; Rauw, Grégor ULg

in Rauw, Grégor; Nazé, Yaël; Blomme, R. (Eds.) et al Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile ... [more ▼]

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile variability of its brightest massive members. We present new results concerning the line profile variability of He II 4686 and H-beta for HD 15570 and HD 15629. For these two stars, our radial velocity analysis does not reveal any variations compatible with a binary motion. We also significantly improve the orbital parameters of the long period binary HD 15558. For this latter system, we present for the first time evidence for the detection of the secondary, leading to spectral types of O5.5 and O7 respectively for the two components. [less ▲]

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See detailThe peculiar Of?p stars HD 108 and HD 191612
Nazé, Yaël ULg; Rauw, Grégor ULg; Walborn, N. R. et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

The Of?p spectral category was introduced by Walborn in 1972 to describe peculiar stars which possess intense emission lines of C III 4647,4650,4651. Recently, two of them, HD 108 and HD 191612, were ... [more ▼]

The Of?p spectral category was introduced by Walborn in 1972 to describe peculiar stars which possess intense emission lines of C III 4647,4650,4651. Recently, two of them, HD 108 and HD 191612, were found to display spectacular line profile variations in the visible domain: these stars apparently alternate between two different spectral states (O6-O8). To discover the origin of this intriguing behaviour, a multiwavelength campaign was undertaken. In this context, the analysis of the X-ray emission is especially important since it provides crucial information for constraining the nature of these peculiar objects and testing conflicting models. We are therefore carrying out high-quality XMM-Newton observations of these stars and we present the results of the data obtained up to now. [less ▲]

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See detailThe young open cluster NGC 6231: five years of investigations
Sana, H.; Rauw, Grégor ULg; Gosset, Eric ULg

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

In this contribution, we present an overview of the main results obtained by the Liège multiwavelength (in the X-ray and optical domains) campaign on the young open cluster NGC 6231. We probe the ... [more ▼]

In this contribution, we present an overview of the main results obtained by the Liège multiwavelength (in the X-ray and optical domains) campaign on the young open cluster NGC 6231. We probe the distribution of the O star properties, and especially their binary nature. In this regard, we revise the O-type binary fraction and we briefly discuss the distribution of the binary parameters. We then present the latest developments of the canonical L[SUB]X[/SUB]-L[SUB]bol[/SUB] relation. We discuss the causes of the observed deviations from this relation and of the X-ray variability among O-type stars. Probing the population of low mass pre-main sequence stars detected in the X-ray domain, we propose a scenario for the star formation history in NGC 6231. [less ▲]

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See detailCPD-41° 7742: an unusual wind interaction
Sana, H.; Gosset, Eric ULg; Rauw, Grégor ULg et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We summarize the results of a multiwavelength observing campaign on the massive eclipsing binary CPD-41° 7742, another remarkable object in the young open cluster NGC 6231. Our campaign relies on high ... [more ▼]

We summarize the results of a multiwavelength observing campaign on the massive eclipsing binary CPD-41° 7742, another remarkable object in the young open cluster NGC 6231. Our campaign relies on high resolution echelle spectroscopy, narrow-band optical photometry, and XMM-Newton X-ray observations. Combined with the spectroscopic analysis, the light curve analysis provides a direct measurement of the masses and sizes of the system components. However, the most outstanding results come from the XMM observations. Our 180 ks campaign towards NGC 6231, and CPD-41° 7742, provides an unprecedented phase coverage of such a close early-type binary. The EPIC-MOS light curves almost fully cover the 2.4 day period of the system and the brightness of the object is sufficient to yield a time resolution as tight as 1 ks. The X-ray flux presents clear variations along the orbit, that we interpret as the signature of an unusual wind interaction. We indeed expect that, in this O+B system, the dominant primary wind crashes into the secondary surface, leading to a wind-photosphere interaction. As a strong support to our interpretation, we provide a geometrical model that associates an extra X-ray emission to the secondary inner surface. Though quite simple, the present model matches the main features of the X-ray light curve. [less ▲]

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See detailPreliminary results of an observational campaign aiming at the study of the binary system LSS3074
Gosset, Eric ULg; Rauw, Grégor ULg; Manfroid, Jean ULg et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present preliminary results of an observational campaign aiming at the study of the binary system LSS3074. A new lightcurve clearly indicates that the system is in contact. Recent spectroscopy broadly ... [more ▼]

We present preliminary results of an observational campaign aiming at the study of the binary system LSS3074. A new lightcurve clearly indicates that the system is in contact. Recent spectroscopy broadly confirms the previous results and the rather low masses of both components (O4f[SUP]+[/SUP] and O6-7:(f):). We further analyse an XMM-Newton observation of the object that indicates a rather hard X-ray spectrum. This is partly due to the high interstellar extinction towards the object but also to the high plasma temperature (kT Ë 1.2-1.3 keV). [less ▲]

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See detailAre WC9 Wolf-Rayet stars in colliding-wind binaries?
Williams, P. M.; van der Hucht, K. A.; Rauw, Grégor ULg

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present results from a spectroscopic search for massive companions to dust-making Galactic WC9 stars as a step to testing the paradigm that dust formation in these systems requires colliding winds to ... [more ▼]

We present results from a spectroscopic search for massive companions to dust-making Galactic WC9 stars as a step to testing the paradigm that dust formation in these systems requires colliding winds to produce over densities. We find evidence for OB companions to the WC9 stars WR 59 and WR 65, but not WR 121 or WR 117. We identify lines of N III-V and possibly N II in the spectrum of WR 88, one of the few Galactic WC9 stars which do not make circumstellar dust, and suggest that WR 88 is a transitional WN--WC9 object and less evolved than the other WC9 stars. On the other hand, the possible identification of a strong emission line at 4176 in the spectrum of WR 117 with Ne I suggests that this star is more evolved than other WC9 stars studied. [less ▲]

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See detailThe XMM-Newton view of Plaskett's star and its surroundings
Linder, N.; Rauw, Grégor ULg

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

XMM data of Plaskett's star (HD 47129) are used in order to analyse its X-ray spectrum and variability and hence to derive further constraints on the wind interaction in this early-type binary (O6 I + O7 ... [more ▼]

XMM data of Plaskett's star (HD 47129) are used in order to analyse its X-ray spectrum and variability and hence to derive further constraints on the wind interaction in this early-type binary (O6 I + O7.5 I) system. Combining the information provided by the EPIC and RGS instruments, we find that the X-ray spectrum of Plaskett's star is dominated by thermal plasma at lower energies, whereas the higher energy part (> 3 keV) could probably best be represented by a featureless power law component since we do not detect a significant Fe-K line. Our tests also suggest that an overabundance in nitrogen by a factor Ë 6 might be indicated to best represent the RGS spectrum. On the other hand, 71 X-ray sources have been detected in Plaskett's star field of view and most of them have counterparts in near-IR colours that are consistent with slightly reddened main-sequence objects. Actually, a sizeable fraction of the X-ray sources in the EPIC images could be either foreground or background sources with no direct connection to HD 47129. [less ▲]

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See detailOn the potential of extrasolar planet transit surveys
Gillon, Michaël ULg; Courbin, F.; Magain, Pierre ULg et al

in Astronomy and Astrophysics (2005), 442

We analyse the respective benefits and drawbacks of ground-based and space-based transit surveys for extrasolar planets. Based on simple but realistic assumptions about the fraction of lower main sequence ... [more ▼]

We analyse the respective benefits and drawbacks of ground-based and space-based transit surveys for extrasolar planets. Based on simple but realistic assumptions about the fraction of lower main sequence stars harboring telluric and giant planets within the outer limit of the habitable zone, we predict the harvests of fictitious surveys with three existing wide field optical and near-IR cameras: the CFHT-Megacam, SUBARU-Suprime and VISTA-IR. An additional promising instrument is considered, VISTA-Vis, currently under development. The results are compared with the harvests predicted under exactly the same assumptions, for the space missions COROT and KEPLER. We show that ground-based wide field surveys may discover more giant planets than space missions. However, space surveys seem to constitute the best strategy to search for telluric planets. In this respect, the KEPLER mission appears 50 times more efficient than any of the ground-based surveys considered here. KEPLER might even discover telluric planets in the habitable zone of their host star. [less ▲]

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See detailOptimization of BaZrO3 sintering by control of the initial powder size distribution; a factorial design statistical analysis
Guillaume, Bernard ULg; Boschini, Frédéric ULg; Garcia-Cano, I. et al

in Journal of the European Ceramic Society (2005), 25(16), 3593-3604

A factorial design statistical analysis has been conducted in order to obtain the optimum conditions in the solid state sintering process of barium zirconate bulk materials, optimum with respect to ... [more ▼]

A factorial design statistical analysis has been conducted in order to obtain the optimum conditions in the solid state sintering process of barium zirconate bulk materials, optimum with respect to density, closed and open porosities. The optimized heat treatment permits to sinter a 99% dense barium zirconate sample at 1650 degrees C during only 2 h. When the temperature is higher than 1650 degrees C or when the heating time is longer than 2 h, a decrease in density is observed. (c) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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