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See detailThe Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705
Tautvaišienė, G.; Drazdauskas, A.; Mikolaitis, Š. et al

in Astronomy and Astrophysics (2015), 573

Context. The Gaia-ESO Public Spectroscopic Survey will observe a large sample of clusters and cluster stars, covering a wide age-distance-metallicity-position-density parameter space. <BR /> Aims: We aim ... [more ▼]

Context. The Gaia-ESO Public Spectroscopic Survey will observe a large sample of clusters and cluster stars, covering a wide age-distance-metallicity-position-density parameter space. <BR /> Aims: We aim to determine C, N, and O abundances in stars of Galactic open clusters of the Gaia-ESO survey and to compare the observed abundances with those predicted by current stellar and Galactic evolution models. In this pilot paper, we investigate the first three intermediate-age open clusters. <BR /> Methods: High-resolution spectra, observed with the FLAMES-UVES spectrograph on the ESO VLT, were analysed using a differential model atmosphere method. Abundances of carbon were derived using the C[SUB]2[/SUB] band heads at 5135 and 5635.5 Å. The wavelength interval 6470-6490 Å, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [O i] line at 6300 Å. <BR /> Results: The mean values of the elemental abundances in Trumpler 20 as determined from 42 stars are: [ Fe/H ] = 0.10 ± 0.08 (s.d.), [ C/H ] = -0.10 ± 0.07, [ N/H ] = 0.50 ± 0.07, and consequently C/N = 0.98 ± 0.12. We measure from five giants in NGC 4815: [ Fe/H ] = -0.01 ± 0.04, [ C/H ] = -0.17 ± 0.08, [ N/H ] = 0.53 ± 0.07, [ O/H ] = 0.12 ± 0.09, and C/N = 0.79 ± 0.08. We obtain from 27 giants in NGC 6705: [ Fe/H ] = 0.0 ± 0.05, [ C/H ] = -0.08 ± 0.06, [ N/H ] = 0.61 ± 0.07, [ O/H ] = 0.13 ± 0.05, and C/N = 0.83 ± 0.19. The C/N ratios of stars in the investigated open clusters were compared with the ratios predicted by stellar evolutionary models. For the corresponding stellar turn-off masses from 1.9 to 3.3 M[SUB]⊙[/SUB], the observed C/N ratio values are very close to the predictions of standard first dredge-up models as well as to models of thermohaline extra-mixing. They are not decreased as much as predicted by the recent model in which the thermohaline- and rotation-induced extra-mixing act together. The average [O/H] abundance ratios of NGC 4815 and NGC 6705 are compared with the predictions of two Galactic chemical evolution models. The data are consistent with the evolution at the solar radius within the errors. <BR /> Conclusions: The first results of CNO determinations in open clusters show the potential of the Gaia-ESO Survey to judge stellar and Galactic chemical evolution models and the validity of their physical assumptions through a homogeneous and detailed spectral analysis. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey, PIs G. Gilmore and S. Randich). [less ▲]

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See detailThe Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
Smiljanic, R.; Korn, A. J.; Bergemann, M. et al

in Astronomy and Astrophysics (2014), 570

Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10[SUP]5[/SUP] stars and high-resolution UVES ... [more ▼]

Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10[SUP]5[/SUP] stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars. <BR /> Aims: These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO second internal release and will be part of its first public release of advanced data products. Methods: The final parameter scale is tied to the scale defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. In addition, a set of open and globular clusters is used to evaluate the physical soundness of the results. Each of the implemented methodologies is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted medians of those from the individual methods. Results: The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected T[SUB]eff[/SUB]-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for T[SUB]eff[/SUB], 0.13 dex for log g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for T[SUB]eff[/SUB], 0.10-0.25 dex for log g and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex. Conclusions: The Gaia-ESO sample of high-resolution spectra of FGK-type stars will be among the largest of its kind analyzed in a homogeneous way. The extensive list of elemental abundances derived in these stars will enable significant advances in the areas of stellar evolution and Milky Way formation and evolution. Based on observations made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey, PIs Gilmore and Randich). Appendices are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201423937/olm">http://www.aanda.org</A> [less ▲]

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See detailGAIMS: A Reliable Non-Intrusive Gait Measuring System
Pierard, Sébastien ULg; Azrour, Samir ULg; PHAN BA, Remy ULg et al

in ERCIM News (2013), 95

Gait observation and analysis can provide invaluable information about an individual [1]. Studies that have interpreted gait using traditional imaging devices have demonstrated that it is difficult to ... [more ▼]

Gait observation and analysis can provide invaluable information about an individual [1]. Studies that have interpreted gait using traditional imaging devices have demonstrated that it is difficult to make reliable measurements with colour cameras. GAIMS, our new system resulting from a multidisciplinary project born from collaboration between engineers and neurologists, aims at developing non-intrusive and reliable tools to provide quantitative measures of gait and interpretations of the acquired data. Following a current trend in imaging, it takes advantage of imaging sensors that measure distance instead of colour. While its principles are general, GAIMS is currently used for the diagnosis of multiple sclerosis (MS) and the continued evaluation of disease progression [2]. It is the first available system to fully satisfy the clinical routine and its associated constraints. [less ▲]

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See detailGAIMS: a tool specifically developed for the clinical gait analysis of patients with multiple sclerosis
Pierard, Sébastien ULg; Phan-Ba, Rémy; Giet, Amaury et al

Poster (2015, April)

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See detailGain baro-réflexe calculé lors d’un test d’orthostatisme (« squatting ») : reproductibilité et effet de l’âge dans une population normale
PHILIPS, Jean-Christophe ULg; MARCHAND, Monique ULg; Estrella, F. et al

in Archives des Maladies du Coeur et des Vaisseaux (2004), 97(suppl), 5392

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See detailGain-scheduled, model-based anti-windup for LPV systems
Forni, Fulvio ULg; Galeani, Sergio

in Automatica (2010), 46(1), 222-225

The aim of this paper is to show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem ... [more ▼]

The aim of this paper is to show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem for linear parameter varying systems, for which the time varying parameters are measured online. The proposed technique is minimally conservative with respect to the size of the resulting operating region (which coincides, up to an arbitrarily small quantity, with the largest set on which asymptotic stability can be guaranteed for the considered plant with the given saturation level and uncertainty characteristics), and is not limited to plants having only small uncertainties or being open-loop stable. [less ▲]

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See detailGaining speed in molecular dynamics simulations by implicit representation of water and membrane molecules
Steinhauer, Sven ULg; Crowet, Jean-Marc ULg; Brasseur, Robert ULg et al

Poster (2013, June 19)

Molecular dynamics (MD) is an appropriate method for investigation of peptide-membrane systems and helps in analyzing results from experiments. In many cases, the ability of viral fusion proteins and ... [more ▼]

Molecular dynamics (MD) is an appropriate method for investigation of peptide-membrane systems and helps in analyzing results from experiments. In many cases, the ability of viral fusion proteins and toxins for destabilizing the membrane is due to their hydrophobic profile, leading to particular membrane insertion. By now, many relevant processes for drug design, toxicological studies and other fields of application, are not feasible by MD simulations, when each atom is represented over time. Processes such as protein folding, often take place above the time scales reachable by MD simulations, which are of the order of micro seconds. The necessary time effort for carrying out such simulations stays considerable and depends mainly on (1) the complexity of the simulated system (2) the simulated time scale (3) the simulation method (4) the efficiency of used hardware and software algorithms. Nowadays, MD simulations can still take weeks of calculation on high end computers. Impala is an implicit water and lipids forcefield, initially developed by our laboratory. Implicit forcefields replace water and/or lipid molecules by a couple of simple and partially precalculable equations. Using this method, thousands of water and lipid molecules can be replaced in MD simulations using Gromacs software. This leads to a considerable reduction of system complexity. The original Impala algorithm based on the assumption of rigid peptides and used a Monte Carlo algorithm with the aim of finding the insertion characteristics of these molecules in membranes. Our current work is the integration of the Impala forcefield into Gromacs, a freely accessible MD software. Replacing the aqueous and lipid phase atomic description in Gromacs MD by an implicit forcefield is supposed to lead to a gain of speed compared to full atomistic simulations. A gain of precision compared to Impala is expected, too. This will be achieved by turning molecules flexible, when implementing Impala into Gromacs. [less ▲]

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See detailGains d’efficience : La Cour AELE, peu sensible à l’approche économique, rejette le pourvoi de la poste norvégienne, condamnée à 12 millions d’euros d’amendes pour avoir empêché l’accès d’entreprises concurrentes au marché de la distribution de colis aux particuliers
Sibony, Anne-Lise ULg

in Concurrences : Revue des Droits de la Concurrence (2012), 4

Cour AELE, 18 avril 2012, Posten Norge/Autorité AELE, aff. E-15/10 Gains d’efficience : La Cour AELE, peu sensible à l’approche économique, rejette le pourvoi de la poste norvégienne, condamnée à 12 ... [more ▼]

Cour AELE, 18 avril 2012, Posten Norge/Autorité AELE, aff. E-15/10 Gains d’efficience : La Cour AELE, peu sensible à l’approche économique, rejette le pourvoi de la poste norvégienne, condamnée à 12 millions d’euros d’amendes pour avoir empêché l’accès d’entreprises concurrentes au marché de la distribution de colis aux particuliers. [less ▲]

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See detailGaio, l'insegnamento e il Belgio
Gerkens, Jean-François ULg

Conference (2012, June 11)

What was the impact of the discovery of the Veronese Palimpsest on the teaching methods in Belgium?

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See detailGait analysis during an original walking test
Croisier, Jean-Louis ULg; Crielaard, Jean-Michel ULg; Chapelier, Dominique et al

in Parkinsonism & Related Disorders (2008), 14

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See detailGait analysis during an original walking test: application in fibromyalgia syndrome
Maquet, Didier ULg; Chapelier, Dominique; Bouquegneau, Adeline ULg et al

in Journal of Rehabilitation Medicine Supplement (2008, June), 47

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See detailGait analysis during an original walking test: Comparison between control subjects and patients with Parkinson’s disease
Maquet, Didier ULg; Croisier, Jean-Louis ULg; Robert, Fanny et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2010, June), 25(Suppl 2), 355

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See detailGait analysis in elderly adult patients with mild cognitive impairment and patients with mild Alzheimer’s disease: simple versus dual task: A preliminary report
Maquet, Didier ULg; Lekeu, Françoise ULg; Warzee, Emmanuelle ULg et al

in Clinical Physiology & Functional Imaging (2010), 30(1), 51-56

Background ⁄ Aims: The aim of this study was to assess gait characteristics during simple and dual task in patients with mild cognitive impairment (MCI) and compare them with those of healthy elderly ... [more ▼]

Background ⁄ Aims: The aim of this study was to assess gait characteristics during simple and dual task in patients with mild cognitive impairment (MCI) and compare them with those of healthy elderly subjects and mild Alzheimer s disease (AD) patients. Methods: We proposed a gait analysis to appreciate walking (simple task and dual task) in 14 MCI, 14 controls and six AD subjects who walked at their preferred speed. A 20-second period of stabilized walking was used to calculated stride frequency, stride length, symmetry and regularity. Speed walking was measured by electrical photocells. Results: Variables measured during simple and dual tasks showed an alteration of motor function as well in mild AD patients as in MCI patients. Conclusion: At the end of this preliminary study, we defined a specific gait pattern for each cognitive profile. Further researches appear necessary to enlarge the study cohort. [less ▲]

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See detailGait analysis using a wearable accelerometer system: Comparison between control subjects and patients with Parkinson’s disease
Maquet, Didier ULg; Croisier, Jean-Louis ULg; Robert, Fanny et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2010, June), 25(S2), 355

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See detailGait feature extraction in Parkinson's disease using low-cost accelerometers
Stamatakis, Julien; Cremers, Julien ULg; Maquet, Didier ULg et al

Poster (2011)

The clinical hallmarks of Parkinson’s disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity, limb tremor or gait disturbances. Parkinson’s gait include slowness, shuffling ... [more ▼]

The clinical hallmarks of Parkinson’s disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity, limb tremor or gait disturbances. Parkinson’s gait include slowness, shuffling, short steps, freezing of gait (FoG) and/or asymmetries in gait. There are currently no validated clinical instruments or device that allow a full characterization of gait disturbances in PD. As a step towards this goal, a four accelerometer-based system is proposed to increase the number of parameters that can be extracted to characterize parkinsonian gait disturbances such as FoG or gait asymmetries. After developing the hardware, an algorithm has been developed, that automatically epoched the signals on a stride-by-stride basis and quantified, among others, the gait velocity, the stride time,the stance and swing phases, the single and double support phases or the maximum acceleration at toe-off, as validated by visual inspection of video recordings during the task. The results obtained in a PD patient and an healthy volunteer are presented. The FoG detection will be improved using time-frequency analysis and the system is about to be validated with a state-of-the-art 3D movement analysis system. [less ▲]

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See detailGaius, professeur de droit et jurisconsulte
Gerkens, Jean-François ULg

in Van Orshoven, Paul; Geens, Koen; Lesaffer, Randall (Eds.) et al Ad amicissimum amici scripsimus. Vriendenboek Raf Verstegen (2004)

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See detailGaius, professeur de droit et jurisconsulte
Gerkens, Jean-François ULg

in Revue de la Faculté de Droit de l'Université de Liège (2004), (2004/3), 443-449

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See detailGalactic archaeology: mapping and dating stellar populations with asteroseismology of red-giant stars
Miglio, A.; Chiappini, C.; Morel, Thierry ULg et al

in Monthly Notices of the Royal Astronomical Society (2013), 429

Our understanding of how the Galaxy was formed and evolves is severely hampered by the lack of precise constraints on basic stellar properties such as distances, masses and ages. Here, we show that solar ... [more ▼]

Our understanding of how the Galaxy was formed and evolves is severely hampered by the lack of precise constraints on basic stellar properties such as distances, masses and ages. Here, we show that solar-like pulsating red giants represent a well-populated class of accurate distance indicators, spanning a large age range, which can be used to map and date the Galactic disc in the regions probed by observations made by the CoRoT and Kepler space telescopes. When combined with photometric constraints, the pulsation spectra of such evolved stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which are reliable proxies for the ages of the stars. As a first application, we consider red giants observed by CoRoT in two different parts of the Milky Way, and determine precise distances for ˜2000 stars spread across nearly 15 000 pc of the Galactic disc, exploring regions which are a long way from the solar neighbourhood. We find significant differences in the mass distributions of these two samples which, by comparison with predictions of synthetic models of the Milky Way, we interpret as mainly due to the vertical gradient in the distribution of stellar masses (hence ages) in the disc. In the future, the availability of spectroscopic constraints for this sample of stars will not only improve the age determination, but also provide crucial constraints on age-velocity and age-metallicity relations at different Galactocentric radii and heights from the plane. [less ▲]

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