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See detailA quantitative study of O stars in NGC 2244 and the Monoceros OB2 association
Martins, F.; Mahy, Laurent ULg; Hillier, D. J. et al

in Astronomy and Astrophysics (2012), 538

<BR /> Aims: Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the ... [more ▼]

<BR /> Aims: Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the mass loss rates of O stars. They allow us to both check the validity of rotational mixing in massive stars and to better understand the effects of the ionizing flux and wind mechanical energy release on the surrounding interstellar medium and its influence on triggered star formation. <BR /> Methods: We collected optical and UV spectra of the target stars that we analyzed by means of atmosphere models computed with the code CMFGEN. The spectra of binary stars were disentangled and the components studied separately. <BR /> Results: All stars have an evolutionary age less than 5 million years, with the most massive stars being among the youngest. Nitrogen surface abundances show no clear relation with projected rotational velocities. Binaries and single stars show the same range of enrichment. This is attributed to the youth and/or wide separation of the binary systems in which the components have not (yet) experienced strong interaction. A clear trend toward greater enrichment in higher luminosity objects is observed, consistent with what evolutionary models with rotation predict for a population of O stars at any given age. We confirm the weakness of winds in late O dwarfs. In general, mass loss rates derived from UV lines are lower than mass loss rates obtained from Hα. The UV mass loss rates are even lower than the single-line driving limit in the latest type dwarfs. These issues are discussed in the context of the structure of massive stars winds. The evolutionary and spectroscopic masses are in agreement above 25 M[SUB]&sun;[/SUB], but the uncertainties are large. Below this threshold, the few late-type O stars studied here indicate that the mass discrepancy still seems to hold. Appendix A is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailHigh-resolution X-ray spectroscopy of the magnetic Of?p star HD148937
Nazé, Yaël ULg; Zhekov, S. A.; Walborn, N. R.

in Astrophysical Journal (2012), 746

High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the ... [more ▼]

High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800km/s), i.e. narrower than the O line recorded by RGS, which possibly indicates that the hot plasma is multi-thermal and has several origins. These data further indicate a main plasma temperature of about 0.6keV and a formation of the X-ray emission at about one stellar radius above the photosphere. From the spectral fits and the H-to-He line ratios, the presence of very hot plasma is however confirmed, though with a smaller relative strength than for the prototype magnetic oblique rotator $\theta^1$\,Ori\,C. Both stars thus share many similarities, but HD148937 appears less extreme than $\theta^1$\,Ori\,C despite having also a large magnetic confinement parameter. [less ▲]

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See detailMicrolensing Binaries Discovered through High-magnification Channel
Shin, I.-G.; Choi, J.-Y.; Park, S.-Y. et al

in Astrophysical Journal (2012), 746

Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected ... [more ▼]

Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a 3σ confidence level for three events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretical prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is q ~ 0.1, making the companion of the lens a strong brown dwarf candidate. [less ▲]

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See detailFirst results for the solar neighborhood of the Asiago Red Clump Survey
Valentini, Marica ULg; Munari, U.; Saguner, T. et al

in European Physical Journal Web of Conferences (2012, February 01)

The Asiago Red Clump Spectroscopic Survey (ARCS) is an ongoing survey that provides atmospheric parameters, distances and space velocities of a well selected sample of Red Clump stars distributed along ... [more ▼]

The Asiago Red Clump Spectroscopic Survey (ARCS) is an ongoing survey that provides atmospheric parameters, distances and space velocities of a well selected sample of Red Clump stars distributed along the celestial equator. We used the ARCS catalog for a preliminary investigation of the Galactic disk in the Solar Neighborhood, in particular we focused on detection and characterization of moving groups. [less ▲]

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See detailProceedings of the 7th International Conference on Si Epitaxy and Heterostructures (ICSI-7)
Hartmann, Jean-Michel; Loo, Roger; Nguyen, Ngoc Duy ULg et al

Book published by Elsevier (2012)

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See detailTransiting exoplanets from the CoRoT space mission Resolving the nature of transit candidates for the LRa03 and SRa03 fields
Cavarroc, C.; Moutou, C.; Gandolfi, D. et al

in Astrophysics & Space Science (2012), 337

CoRoT is a space telescope which aims at studying internal structure of stars and detecting extrasolar planets. We present here a list of transits detected in the light curves of stars observed by CoRoT ... [more ▼]

CoRoT is a space telescope which aims at studying internal structure of stars and detecting extrasolar planets. We present here a list of transits detected in the light curves of stars observed by CoRoT in two fields in the anti-center direction: the LRa03 one observed during 148 days from 3 October 2009 to 1 March 2010 followed by the SRa03 one from the 5 March 2010 to the 29 March 2010 during 25 days. 5329 light curves for the LRa03 field and 4169 for the SRa03 field were analyzed by the detection team of CoRoT. Then some of the selected exoplanetary candidates have been followed up from the ground. In the LRa03 field, 19 exoplanet candidates have been found, 8 remain unsolved. No secured planet has been found yet. In the SRa03 field, there were 11 exoplanetary candidates among which 6 cases remain unsolved and 3 planets have been found: CoRoT-18b, CoRoT-19b, CoRoT-20b. [less ▲]

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See detailLa production de viande par les bovins
Beckers, Yves ULg

Conference given outside the academic context (2012)

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See detailTraitement à la source d'eaux usées hospitalières par boues activées: faisabilité et impact sur la biomasse
Alrhmoun, Moussab; Louvet, Jean-Noël ULg; Stalder, Thibault et al

Conference (2012, February 01)

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See detailModelling a high-mass red giant observed by CoRoT
Baudin, F.; Barban, C.; Goupil, M. J. et al

in Astronomy and Astrophysics (2012), 538

Context. The advent of space-borne photometers such as CoRoT and Kepler has opened up new fields in asteroseismology. This is especially true for red giants as only a few of these stars were known to ... [more ▼]

Context. The advent of space-borne photometers such as CoRoT and Kepler has opened up new fields in asteroseismology. This is especially true for red giants as only a few of these stars were known to oscillate with small amplitude, solar-like oscillations before the launch of CoRoT. <BR /> Aims: The G6 giant HR 2582 (HD 50890) was observed by CoRoT for approximately 55 days. We present here the analysis of its light curve and the characterisation of the star using different observables, such as its location in the Hertzsprung-Russell diagram and seismic observables. <BR /> Methods: Mode frequencies are extracted from the observed Fourier spectrum of the light curve. Numerical stellar models are then computed to determine the characteristics of the star (mass, age, etc.) from the comparison with observational constraints. <BR /> Results: We provide evidence for the presence of solar-like oscillations at low frequency, between 10 and 20 μHz, with a regular spacing of (1.7 ± 0.1) μHz between consecutive radial orders. Only radial modes are clearly visible. From the models compatible with the observational constraints used here, We find that HR 2582 (HD 50890) is a massive star with a mass in the range (3-5 M[SUB]&sun;[/SUB]), clearly above the red clump. It oscillates with rather low radial order (n = 5-12) modes. Its evolutionary stage cannot be determined with precision: the star could be on the ascending red giant branch (hydrogen shell burning) with an age of approximately 155 Myr or in a later phase (helium burning). In order to obtain a reasonable helium amount, the metallicity of the star must be quite subsolar. Our best models are obtained with a mixing length significantly smaller than that obtained for the Sun with the same physical description (except overshoot). The amount of core overshoot during the main-sequence phase is found to be mild, of the order of 0.1 H[SUB]p[/SUB]. <BR /> Conclusions: HR 2582 (HD 50890) is an interesting case as only a few massive stars can be observed due to their rapid evolution compared to less massive red giants. HR 2582 (HD 50890) is also one of the few cases that can be used to validate the scaling relations for massive red giants stars and its sensitivity to the physics of the star. The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES with participation of the Science Programs of ESA; ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain. [less ▲]

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See detailLe droit des marchés publics et les écoquatiers
Durviaux, Ann-Lawrence ULg

Conference given outside the academic context (2012)

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See detailEducational orientation and social heritage. The choice of working-class students
Andre, Géraldine ULg

Conference (2012, February 01)

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See detailRutherford backscattering analysis of porous thin TiO2 films
Mayer, Matej; von Toussaint, Udo; Dewalque, Jennifer ULg et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2012), 273

The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones ... [more ▼]

The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones expected from a Poisson distribution of the number of traversed pores are taken into account. These deviations are due to the interaction of pores at higher pore concentrations by overlap or blocking. The skewnesses of the energy distributions are approximated by two-piece normal distributions with identical first three moments. Propagation of porosity-induced energy spread in thick layers is taken into account. Calculated results are compared to experimental data obtained with thin TiO2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry. [less ▲]

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See detailContribution à l’optimalisation du support nutritionnel et de la croissance des prématurés de très faible poids à la naissance
SENTERRE, Thibault ULg

Doctoral thesis (2012)

Postnatal growth restriction (PNGR) is a common finding during neonatal hospitalization in very low birth weight (VLBW) infants. Insufficient nutritional support during the first weeks of life is ... [more ▼]

Postnatal growth restriction (PNGR) is a common finding during neonatal hospitalization in very low birth weight (VLBW) infants. Insufficient nutritional support during the first weeks of life is responsible of major cumulative protein and energy deficit that has been considered as malnutrition. VLBW infants are frequently described small-for-gestational age (SGA) at discharge. The insufficient nutritional support is the primary aetiology of the PNGR observed in VLBW infants. Furthermore, both insufficient nutritional intakes and poor growth have been associated with adverse short and long-term outcomes. Particularly, they impair neurodevelopment and favor disorders in adulthood like obesity, type 2 diabetes, hypertension and cardiovascular diseases. Despite the immaturity of VLBW infants, some authors have proposed to increased nutritional intakes from birth onwards and consider this early ‘‘aggressive’’ nutrition as more optimal. This concept has been translated in the recent recommendations that advocate a minimum of 40 kcal/kg/day and 2.0 g/kg/day of protein from the first day of life that need to be increased to 120 kcal/kg/day and 3.8 g/kg/day of protein by the end of the first week of life. A significant variation has been observed regarding nutritional practices among neonatal intensive care units with many studies still reporting insufficient postnatal nutritional intakes and severe PNGR. Some authors have questioned the feasibility and the adequacy of current nutritional recommendations. Indeed, there are still some concerns that increased nutritional intakes may disturb infant’s condition. Common fears include hyperglycemia, uremia, metabolic acidosis, hyperammoniemia and necrotizing enterocolitis. The aim of this study was to evaluate postnatal growth, cumulative nutritional deficit and metabolic tolerance after optimizing our nutritional policy to recent recommendations. The study is a prospective, observational, non interventional, and single-center cohort study in VLBW infants <1250g. All consecutive infants admitted in the NICU during a 2-year period were included in the study (N=102). Severely ill infants and infants with congenital anomalies were not excluded from the analysis. This study is the first to demonstrate nutritional intakes in the range of current recommendations. It suggests that it is possible to optimize nutritional intakes routinely in real clinical practice. The use of an adequate standardized ready-to-use parenteral solution appears to contribute to improve the early nutritional supply. Optimizing the energy and protein intakes significantly reduced the cumulative nutritional deficit, even in extremely preterm infants <28 weeks’ gestational age. In the majority of infants, PNGR could even be prevented. In our cohort, only 6% of appropriate-for-gestational age infants became SGA at discharge. Moreover, 20% of SGA infants became appropriate for gestational age at discharge. No major metabolic disturbances were observed and, even more, biological perturbations seem to decline compared to most recent studies. Additionally, we evaluate the first commercially manufactured parenteral nutrition developed for preterm infants. Theses studies confirm that the first week of life is a critical period to promote growth. This study is an important step in neonatal intensive care. It demonstrates that malnutrition may be avoided in VLBW infants and that postnatal growth may be enhanced with little restriction by the time of discharge. It is an important contribution to the development of VLBW infants. [less ▲]

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See detailOn different types of adjustment usable to calculate the parameters of the stream power law
Demoulin, Alain ULg; Beckers, Arnaud ULg; Bovy, Benoît ULg

in Geomorphology (2012), 138(1), 203-208

Model parameterization through adjustment to field data is a crucial step in the modeling and the understanding of the drainage network response to tectonic or climatic perturbations. Using as a test case ... [more ▼]

Model parameterization through adjustment to field data is a crucial step in the modeling and the understanding of the drainage network response to tectonic or climatic perturbations. Using as a test case a data set of 18 knickpoints that materialize the migration of a 0.7-Ma-old erosion wave in the Ourthe catchment of northern Ardennes (western Europe), we explore the impact of various data fitting on the calibration of the stream power model of river incision, from which a simple knickpoint celerity equation is derived. Our results show that statistical least squares adjustments (or misfit functions) based either on the streamwise distances between observed and modeled knickpoint positions at time t or on differences between observed and modeled time at the actual knickpoint locations yield significantly different values for the m and K parameters of the model. As there is no physical reason to prefer one of these approaches, an intermediate least-rectangles adjustment might at first glance appear as the best compromise. However, the statistics of the analysis of 200 sets of synthetic knickpoints generated in the Ourthe catchment indicate that the timebased adjustment is the most capable of getting close to the true parameter values. Moreover, this fitting method leads in all cases to an m value lower than that obtained from the classical distance adjustment (for example, 0.75 against 0.86 for the real case of the Ourthe catchment), corresponding to an increase in the non-linear character of the dependence of knickpoint celerity on discharge [less ▲]

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See detailLe dosage des acides gras érythrocytaires : comparaison entre une population de référence et des sujets ayant présenté un infarctus aigu du myocarde
LE GOFF, Caroline ULg; Leroy, Ludovic; Kaux, Jean-François ULg et al

Poster (2012, February)

Introduction Un acide gras (AG) est un acide carboxylique avec une longue chaine aliphatique, qui peut être saturé ou insaturé. Récemment, le rôle des AG, particulièrement, celui des oméga-3 et oméga-6, a ... [more ▼]

Introduction Un acide gras (AG) est un acide carboxylique avec une longue chaine aliphatique, qui peut être saturé ou insaturé. Récemment, le rôle des AG, particulièrement, celui des oméga-3 et oméga-6, a émergé comme facteur de risque cardiovasculaire dans la littérature. Le but de ce travail était de comparer les taux d’AG mesurés dans une population saine avec ceux obtenus chez des patients admis aux urgences pour un infarctus du myocarde. Matériels et méthodes Cinquante quatre sujets sains (33±11ans, 31 femmes) ont été sélectionnés comme population de référence. Ces derniers ont été sélectionnés selon leur mode de vie (alimentation, tabac, etc). En parallèle, nous avons dosé les AG chez 33 patients (55±9 ans, 12 femmes) admis dans le service d’urgence de notre institution pour infarctus aigu du myocarde (AMI). Le sang était prélevé sur EDTA. Avant l’analyse, les échantillons étaient lavés et transméthylés. Le dosage des AG était réalisé par chromatographie gazeuse couplée à un détecteur à ionisation de flamme (GCFID). Après le dosage, nous avons réalisés une comparaison des taux, sommes et rapport entre les différents AG ainsi que l’index oméga-3 (somme de l’acide eicosapentaénoïque et docosahexaénoïque) obtenus dans les 2 groupes. Résultats. Des valeurs de référence ont été obtenues pour notre population de référence via le logiciel de statistique MedCalc. Dans le groupe AMI, les taux d’oméga-6 étaient significativement plus élevés (p<0.05) pour C18:2n6 (Figure 1) et C18:3n6 (Figure 2)comparés aux résultats obtenus dans la population de référence. Par contre les taux d’oméga-3 étaient significativement plus bas (p<0.01) par rapport aux sujets de référence pour le C22 :6n3 (Figure 3). L’index oméga-3 montrait une valeur plus basse et le rapport oméga-6/oméga-3 était plus élevé dans le groupe AMI comparé aux sujets de référence. Conclusion Le dosage des AG est un nouvel outil que le laboratoire peut proposer aux cliniciens afin de stratifier les patients présentant le plus de risque cardiovasculaire avant ou après un infarctus du myocarde. Ces patients pourraient ainsi être supplémenté en acides gras oméga-3 afin d’éviter les récidives d’infarctus du myocarde ou de diminuer la formation de la plaque d’athérosclérose avant le premier accident. [less ▲]

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See detailElectromagnetic absorption properties of carbon nanotube nanocomposite foam filling honeycomb waveguide structures
Quiévy, Nicolas; Bollen, Pierre; Thomassin, Jean-Michel ULg et al

in IEEE Transactions on Electromagnetic Compatibility (2012), 24(1), 43-51

Carbon nanotube reinforced polymer foams filling a metallic honeycomb were processed and characterized for the production of hybrid materials with high electromagnetic absorption potential ... [more ▼]

Carbon nanotube reinforced polymer foams filling a metallic honeycomb were processed and characterized for the production of hybrid materials with high electromagnetic absorption potential. Electromagnetic modeling and experimental characterization of the hybrids proved that the honeycomb, acting as a hexagonal waveguide, improves the absorption properties in the gigahertz range above the cutoff frequency. The electromagnetic absorption can be tuned by changing the hybrid material properties. The required levels of electrical conductivity are attained owing to the dispersion of low amounts (1–2 wt%) of carbon nanotubes inside the polymermatrix. The combination of the foam and honeycomb architecture contributes to decrease the real part of the relative effective permittivity Re{εr,eff }. Varying the cell shape of the honeycomb changes the frequency range for high absorption. An analytical model for the absorption has been developed, showing good agreement with the experimental results. [less ▲]

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See detailGenre et leadership
Cornet, Annie ULg

Speech/Talk (2012)

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See detailEuropean project, demo “NETFLEX” For large integration of renewables using DLR, PST and PMU.
Lilien, Jean-Louis ULg

Conference (2012, February)

forecasting ampacity as a need for power system operation

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See detailTowards a Dynamic Stakeholder Management framework for CSR Certifications
Abboubi, Manal; Cornet, Annie ULg

in International Journal of Business and Social Science (2012), 3(4),

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