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See detailPrivileging late dressing on winter wheat increases recovery and efficiency (yield and quality) of fertilizer N results of 3 years field experiments using stable 15N
Boulelouah, Nadia; Destain, Jean-Pierre ULg; Falisse, André et al

in Haneklaus, S.; Hera, Ch.; Hofman, G. (Eds.) et al Fertilizers and Fertilization: Stewardship for Food Security, Food Quality, Environment and Nature Conservation (2006, January 22)

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See detail2006, année internationale de la lutte contre la désertification
Ozer, Pierre ULg

Article for general public (2006)

La désertification est considérée comme l'une des problématiques environnementales les plus préoccupantes du XXIe siècle. Par désertification, on entend la dégradation des terres dans les zones arides ... [more ▼]

La désertification est considérée comme l'une des problématiques environnementales les plus préoccupantes du XXIe siècle. Par désertification, on entend la dégradation des terres dans les zones arides, semi-arides et sub-humides sèches par suite de divers facteurs, parmi lesquels les variations climatiques et les activités humaines. Cette dégradation environnementale affecte directement un milliard d'hectares et menace près de 35 % des terres de la planète ainsi que les moyens de subsistance de deux milliards d'individus. Les estimations des pertes financières mondiales dues à la désertification sont colossales, de l'ordre de 40 milliards d'euros par an. [...] [less ▲]

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See detailPour 80 milliards de dollars de catastrophes naturelles
Ozer, Pierre ULg; De Longueville, Florence ULg

Article for general public (2006)

Début 2006, nous y sommes. Les sociétés de réassurances, la «Swiss Re» et la «Munich Re» en fer de lance, ont bouclé leurs comptes. Et l'heure est grave: les catastrophes naturelles de 2005 leur auront ... [more ▼]

Début 2006, nous y sommes. Les sociétés de réassurances, la «Swiss Re» et la «Munich Re» en fer de lance, ont bouclé leurs comptes. Et l'heure est grave: les catastrophes naturelles de 2005 leur auront coûté plus de 80 milliards de dollars. Record battu, non, pulvérisé, comme l'effet d'une bombe à fragmentation américaine tombée malencontreusement sur un hôpital irakien ou, moins polémique, comme un séisme qui balaye toute une génération d'écoliers au Cachemire lors d'un tremblement de terre, pourtant attendu, faute de constructions parasismiques... [...] [less ▲]

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See detailDéveloppement durable et théorie des parties prenantes : une même vision de la place du citoyen ?
Semal, Nathalie ULg

in Développement Durable et Territoires [= DDT] (2006)

Sustainable development aims to integrate stakeholder negotiation into economical reasoning and acting models. The stakeholder theory translates this approach in the economics field. Some tools like ISO ... [more ▼]

Sustainable development aims to integrate stakeholder negotiation into economical reasoning and acting models. The stakeholder theory translates this approach in the economics field. Some tools like ISO 14001 standard crystallise this theory. But the practical ways of its implementation do not allow a balanced integration of the hole range of stakeholders views. Stakeholder dialog, which aims to build a consensus about enterprises “environmental quality”, is mostly negotiated inside the economic space. ISO 14001 standardisation system is not likely to allow stakeholder negotiation rights integration while citizens do not organise an environmental quality watching over network. [less ▲]

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See detailLangage et pratique de l'APP
VIERSET, Viviane ULg

Conference (2006, January 05)

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See detailConvection-pulsation interaction: theories and applications
Dupret, Marc-Antoine ULg; Grigahcene, A.; Gabriel, Maurice ULg et al

in Communications in Asteroseismology (2006), 147

The problem of the interaction between convection and pulsations is considered. A precise modeling of this interaction is required for the seismic study of stars with non-negligible convective envelope ... [more ▼]

The problem of the interaction between convection and pulsations is considered. A precise modeling of this interaction is required for the seismic study of stars with non-negligible convective envelope. After a short introduction to the Time-Dependent Convection theory of Gabriel (1996) and Grigahcene et al. (2005), we give a summary of the main results obtained with this treatment for delta Sct, gamma Dor and solar-like stars. [less ▲]

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See detailSeismic study of the Herbig Ae star HD 104237
Dupret, Marc-Antoine ULg; Böhm, T.; Goupil, Marie-José et al

in Communications in Asteroseismology (2006), 147

HD 104237 is the brightest Herbig Ae star, and as such a pre-main sequence (PMS) star. It is also a spectroscopic binary with determined orbital parameters. It was observed in 1999-2000 at SAAO and Mt ... [more ▼]

HD 104237 is the brightest Herbig Ae star, and as such a pre-main sequence (PMS) star. It is also a spectroscopic binary with determined orbital parameters. It was observed in 1999-2000 at SAAO and Mt Stromolo and 1888 Echelle spectra were obtained. From these observations, 8 pulsation frequencies were detected among which 5 with very high confidence (Böhm et al. 2004). We present here a preliminary seismic study based on these observations. We also consider the problem of the excitation of the observed modes and show, as an important result of our study, that HD 104237 is not a delta Sct type pulsator. [less ▲]

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See detailAnalysis of MERCATOR data - Part I: variable B stars
De Cat, P.; Briquet, Maryline ULg; Aerts, C. et al

in Communications in Asteroseismology (2006), 147

We re-classified 31 variable B stars which were observed more than 50 times in the Geneva photometric system with the p7 photometer attached to the MERCATOR telescope (La Palma) during its first 3 years ... [more ▼]

We re-classified 31 variable B stars which were observed more than 50 times in the Geneva photometric system with the p7 photometer attached to the MERCATOR telescope (La Palma) during its first 3 years of scientific observations. HD 89688 is a possible beta Cephei/slowly pulsating B star hybrid and the main mode of the COROT target HD 180642 shows non-linear effects. The Maia candidates are re-classified as either ellipsoidal variables or spotted stars. Although the mode identification is still ongoing, all the well-identified modes so far have l <= 2. [less ▲]

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See detailNon-local time-dependent treatments of convection in A-G type stars
Dupret, Marc-Antoine ULg; Samadi, R.; Grigahcene, A. et al

in Communications in Asteroseismology (2006), 147

Time-Dependent Convection (TDC) models obtained by combining the local treatment of Gabriel (1996) and Grigahcene et al. (2005) and the non-local prescriptions of Spiegel (1963) are presented. We show ... [more ▼]

Time-Dependent Convection (TDC) models obtained by combining the local treatment of Gabriel (1996) and Grigahcene et al. (2005) and the non-local prescriptions of Spiegel (1963) are presented. We show that in the stationary unperturbed case, these non-local treatments can be constrained by the results of 3D hydrodynamic simulations (Stein & Nordlund 1998). We consider here the case of solar-type stars with a large convective envelope and A-F type stars with two very thin surface convection zones. [less ▲]

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See detailInstability strip for pre-main-sequence stars
Grigahcene, A.; Dupret, Marc-Antoine ULg; Garrido, R. et al

in Communications in Asteroseismology (2006), 147

We apply the Time Dependent Convection (TDC) treatment presented in Grigahcene et al. (2005) to the study of Pre-main sequence pulsating stars. The stabilization of the p-modes at the red edge of the ... [more ▼]

We apply the Time Dependent Convection (TDC) treatment presented in Grigahcene et al. (2005) to the study of Pre-main sequence pulsating stars. The stabilization of the p-modes at the red edge of the Instability Strip (IS) is obtained by our models. The theoretical IS obtained with Mixing Length (ML) parameter alpha=1.8 is compared to observations and a good agreement is obtained. [less ▲]

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See detailThe epsilon-mechanism in PMS and MS delta Scuti stars
Lenain, G.; Scuflaire, Richard ULg; Dupret, Marc-Antoine ULg et al

in Communications in Asteroseismology (2006), 147

Delta Scuti type stars are known to pulsate in nonradial low-order p and g modes. These oscillation modes are driven by the so-called kappa-mechanism involving the second helium ionization zone. However ... [more ▼]

Delta Scuti type stars are known to pulsate in nonradial low-order p and g modes. These oscillation modes are driven by the so-called kappa-mechanism involving the second helium ionization zone. However, since g modes have significant amplitudes near the stellar core, their excitation might be influenced by the epsilon-mechanism which is associated to the nuclear energy production. We investigate the effect of the epsilon-mechanism on the stability of oscillation modes in 1.5 M(solar) pre-main sequence and main sequence stars. [less ▲]

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See detailPolytropes as simple models of beta Cephei stars
Godart, Mélanie ULg; Scuflaire, Richard ULg; Thoul, Anne ULg et al

in Communications in Asteroseismology (2006), 147

Beta Cephei stars have a simple structure: a convective core surrounded by a radiative envelope. It is therefore worth trying to describe beta Cephei stars with composite polytropes which are useful to ... [more ▼]

Beta Cephei stars have a simple structure: a convective core surrounded by a radiative envelope. It is therefore worth trying to describe beta Cephei stars with composite polytropes which are useful to retrieve structure parameters from frequency spectra. We show that the structure of beta Cephei models can relatively well be described with two-zone polytropic models. However this description is not convincing to depict oscillations of beta Cephei models. [less ▲]

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See detailRadiative forces and pulsation in beta Cephei stars
Bourge, P*-O; Alecian, G.; Thoul, Anne ULg et al

in Communications in Asteroseismology (2006), 147

Recently radiatively-driven diffusion in beta Cephei stars has been suggested as a possible explanation to account for excitation of the observed oscillation modes of the beta Cephei stars nu Eridani and ... [more ▼]

Recently radiatively-driven diffusion in beta Cephei stars has been suggested as a possible explanation to account for excitation of the observed oscillation modes of the beta Cephei stars nu Eridani and 12 Lacertae. Preliminary results (Bourge and Alecian 2006) show that microscopic diffusion of iron could indeed occur in a region situated just above the opacity bump of the iron group elements. This diffusion has little influence on the position of the star in the HR diagram and on the spectrum of low radial order eigenfrequencies. It does, however, increase the number of excited frequencies. We show here that the ratio between the number of p-modes to the number of g-modes could be used as a signature of this diffusion process. [less ▲]

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See detailThe new solar abundances - Part II: the crisis and possible solutions
Montalban Iglesias, Josefa ULg; Miglio, Andrea ULg; Theado, S. et al

in Communications in Asteroseismology (2006), 147

Recent 3D, NLTE analysis of the solar spectrum (Asplund et al. 2006, Part I; Asplund et al. 2005) have led to a significant reduction of the CNO and Ne abundances leading to a (Z/X) 30% smaller than the ... [more ▼]

Recent 3D, NLTE analysis of the solar spectrum (Asplund et al. 2006, Part I; Asplund et al. 2005) have led to a significant reduction of the CNO and Ne abundances leading to a (Z/X) 30% smaller than the previously recommended value. The corresponding decrease in opacity increases dramatically the discrepancies between the sound-speed derived from helioseismology and our new standard solar models (SSM). We present in this paper some numerical experiments trying to reduce this discrepancy. [less ▲]

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See detailEffects of extra-mixing processes on the periods of high-order gravity modes in main-sequence stars
Miglio, Andrea ULg; Montalban Iglesias, Josefa ULg; Noels-Grötsch, Arlette ULg

in Communications in Asteroseismology (2006), 147

In main-sequence stars, the chemical composition gradient that develops at the edge of the convective core is responsible for a non-uniform period spacing of high-order gravity modes. In this work we ... [more ▼]

In main-sequence stars, the chemical composition gradient that develops at the edge of the convective core is responsible for a non-uniform period spacing of high-order gravity modes. In this work we investigate, in the case of a 1.6 M(solar) star, the effects on the period-spacing of extra mixing processes in the core (such as diffusion and overshooting). [less ▲]

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See detailAngular Clustering of X-ray Point-Like Sources in the XMM Large Scale Structure Survey
Garcet, O.; Gandhi, P.; Gosset, Eric ULg et al

in Wilson, A. (Ed.) Proceedings of the ‘The X-ray Universe 2005’ (2006, January 01)

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See detailSynthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels
Job, Nathalie ULg; Panariello, Fabian; Marien, José ULg et al

in Journal of Non-Crystalline Solids (2006), 352(1), 24-34

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied ... [more ▼]

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 degrees C or 48 h at 70 C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 degrees C in the case of monolithic parts. At 70 degrees C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe Peculiar Of?p Stars HD 108 and HD 191612: The X-ray View
Nazé, Yaël ULg; Rauw, Grégor ULg; Walborn, N. R. et al

in The X-ray Universe 2005 (2006, January 01)

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

Article for general public (2006)

Contrails; Un télescope géant en quête de rayons cosmiques; Stardust; Titan dix mois après l'atterrissage réussi de la sonde Huygens; Geysers sur Encelade; Spirale autour de Saturne; Autre anomalie de l ... [more ▼]

Contrails; Un télescope géant en quête de rayons cosmiques; Stardust; Titan dix mois après l'atterrissage réussi de la sonde Huygens; Geysers sur Encelade; Spirale autour de Saturne; Autre anomalie de l'anneau F; Toujours l'anneau F; Une lune de plus pour 2003 EL61; Un KBO à  l'orbite exceptionnelle; Détection d'une exoplanète de la taille de Neptune; AMBER scrute l'environnement d'une étoile; Première détection du champ magnétique au coeur du disque d'accrétion d'une protoétoile; Collisions intergalactiques; Arpentage galactique [less ▲]

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