Publications ORBi OA
Bookmark and Share    
Full Text
Peer Reviewed
See detailDiscrete-time synchronization on the N-torus
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg; Leonard, Naomi

in Proceedings of the 17th MTNS Symposium, Kyoto 2006 (2006, August)

In this paper, we study the behavior of a discrete-time network of N agents, each evolving on the circle. The global convergence analysis on the N-torus is a distinctive feature of the present work with ... [more ▼]

In this paper, we study the behavior of a discrete-time network of N agents, each evolving on the circle. The global convergence analysis on the N-torus is a distinctive feature of the present work with respect to previous synchronization results that have focused on convergence in the Euclidean space (R^n)^N. We address the question from a control perspective, but make several connections with existing models, including the Hopfield network, the Vicsek model and the (continuous-time) Kuramoto model. We propose two different distributed algorithms. The first one achieves convergence to equilibria in shape space that are the local extrema of a potential U_L built on the graph Laplacian associated to a fixed, undirected interconnection topology; it can be implemented with sensor-based interaction only, since each agent just relies on the relative position of its neighbors. The second one achieves synchronization under varying and/or directed communication topology using local estimates of a consensus variable that are communicated between interacting agents. Both algorithms are based on the notion of centroid and can be interpreted as descent algorithms. The proposed approach can be extended to other embedded compact manifolds. [less ▲]

Detailed reference viewed: 59 (7 ULg)
Full Text
See detailTest comparatif de récepteur GPS
Lejeune, Philippe ULg; Rondeux, Jacques ULg

Poster (2006, July 31)

Des tests, en conditions d'utilisation réelles, ont été réalisés en vue de comparer les performances de différents récepteurs GPS "compact"

Detailed reference viewed: 90 (6 ULg)
Full Text
See detailInteractive comment on “On the application and interpretation of Keeling plots in paleo climate research – deciphering d13C of atmospheric CO2 measured in ice cores” by P. Köhler et al.
Munhoven, Guy ULg

in Biogeosciences Discussions (2006), 3

The paper "On the application and interpretation of Keeling plots in paleo climate research – deciphering delta13C of atmospheric CO2 measured in ice cores" by P. Köhler et al. is reviewed and commented.

Detailed reference viewed: 25 (2 ULg)
Full Text
Peer Reviewed
See detailFemale sexual maturation and reproduction after prepubertal exposure to estrogens and endocrine disrupting chemicals: A review of rodent and human data
Rasier, Gregory; Toppari, Jorma; Parent, Anne-Simone ULg et al

in Molecular & Cellular Endocrinology (2006), 254-255

Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of ... [more ▼]

Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing fetus or neonate to environmentally relevant concentrations of some among these endocrine disrupters induces morphological, biochemical and/or physiological disorders in brain and reproductive organs, by interfering with the hormone actions. The impact of such exposures on the hypothalamic-pituitary-gonadal axis and subsequent sexual maturation is the subject of the present review. We will highlight epidemiological human studies and the effects of early exposure during gestational, perinatal or postnatal life in female rodents. (c) 2006 Elsevier Ireland Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 27 (1 ULg)
Full Text
See detailThe inner debris disc of Vega as seen by CHARA/FLUOR
Absil, Olivier ULg

Scientific conference (2006, July 21)

Using the FLUOR near-infrared beam combiner installed at the CHARA Array (Mt Wilson, CA), we have obtained high-precision interferometric measurements of Vega, a prototypical debris-disk star known to be ... [more ▼]

Using the FLUOR near-infrared beam combiner installed at the CHARA Array (Mt Wilson, CA), we have obtained high-precision interferometric measurements of Vega, a prototypical debris-disk star known to be surrounded by large amounts of cold dust at 80-100 AU in a ring-like structure. The combination of short and long baselines has allowed us to separately resolve the stellar photosphere and its immediate neighbourhood inside by the FLUOR field-of-view of 1’’ (~8 AU at the distance of Vega). Our observations show a significant deficit in visibility at short baselines with respect to the expected visibility of a simple uniform disk stellar model, suggesting the presence of an extended source of emission around Vega. We propose that the visibility deficit is most likely due to the presence of hot circumstellar dust in the inner part of the debris disk, with a flux ratio of 1.29+/-0.19% between the integrated dust emission and the stellar photosphere in K band (2.15 microns). Using this piece of information together with archival photometric and interferometric data in the near- and mid-infrared, we derive the expected physical properties of the dust grains by modelling their infrared Spectral Energy Distribution. Small, highly refractive grains are suspected to be located at only a few 0.1 AU from Vega, with a total mass of about 1e-7 Earth mass. Their presence is thought to be an indicator of major dynamical perturbations currently ongoing in the Vega system. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailSCM : clé essentielle de la performance
Nondonfaz, Robert ULg

Article for general public (2006)

La nécessité de mettre en oeuvre une gestion performante de la Supply Chain afin d'améliorer les performances de l'entreprise et des entreprises liées dans une même Supply Chain

Detailed reference viewed: 13 (1 ULg)
Full Text
Peer Reviewed
See detailThe locus ceruleus is involved in the successful retrieval of emotional memories in humans
Sterpenich, Virginie ULg; D'Argembeau, Arnaud ULg; Desseilles, Martin ULg et al

in Journal of Neuroscience (2006), 26(28), 7416-7423

Emotional memories are better remembered than neutral ones. The amygdala is involved in this enhancement not only by modulating the hippocampal activity, but possibly also by modulating central arousal ... [more ▼]

Emotional memories are better remembered than neutral ones. The amygdala is involved in this enhancement not only by modulating the hippocampal activity, but possibly also by modulating central arousal. Using functional magnetic resonance imaging, we analyzed the retrieval of neutral faces encoded in emotional or neutral contexts. The pupillary size measured during encoding was used as a modulator of brain responses during retrieval. The interaction between emotion and memory showed significant responses in a set of areas, including the amygdala and parahippocampal gyrus. These areas responded significantly more for correctly remembered faces encoded in an emotional, compared with neutral, context. The same interaction conducted on responses modulated by the pupillary size revealed an area of the dorsal tegmentum of the ponto-mesencephalic region, consistent with the locus ceruleus. Moreover, a psychophysiological interaction showed that amygdalar responses were more tightly related to those of the locus ceruleus when remembering faces that had been encoded in an emotional, rather than neutral, context. These findings suggest that the restoration of a central arousal similar to encoding takes part in the successful retrieval of neutral events learned in an emotional context. [less ▲]

Detailed reference viewed: 36 (2 ULg)
Full Text
See detailBulletin agrométéorologique - Juin 2006
Tychon, Bernard ULg; Ozer, Pierre ULg; De Longueville, Florence ULg et al

in Bulletin Agrométéorologique (2006), 5(3), 1-7

Le mois de juin fut chaud permettant à la plupart des cultures de bénéficier de très bonnes conditions de croissance. Le retard de croissance observé depuis le début du suivi des cultures a quasi ... [more ▼]

Le mois de juin fut chaud permettant à la plupart des cultures de bénéficier de très bonnes conditions de croissance. Le retard de croissance observé depuis le début du suivi des cultures a quasi complètement disparu. La faible pluviométrie constatée au mois de juin n’a pour l’instant que peu de conséquences pour les cultures bien installées vu les réserves en eau accumulées le mois précédent. La situation des cultures est globalement favorable, laissant entrevoir des rendements généralement supérieurs à la moyenne des cinq années précédentes. Toutefois, cette prévision pourrait être revue à la baisse si la période sèche observée en juin se prolongeait en juillet. [less ▲]

Detailed reference viewed: 20 (3 ULg)
Full Text
See detailPotential antimalarial activity of indole alkaloids
Angenot, Luc ULg

Conference (2006, July 06)

Detailed reference viewed: 18 (0 ULg)
Full Text
See detailGlances at the EC Nitrate Directive implementation in the Walloon Region of Belgium
Marcoen, Jean Marie ULg

Scientific conference (2006, July 04)

Detailed reference viewed: 22 (3 ULg)
Full Text
See detailPegase: a space-based nulling interferometer
Le Duigou, J. M.; Ollivier, M.; Léger, A. et al

in Mather, John C.; MacEwen, Howard A.; de Graauw, Mattheus W. M. (Eds.) Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter (2006, July 01)

The space based mission Pegase was proposed to CNES in the framework of its call for scientific proposals for formation flying missions. This paper presents a summary of the phase-0 performed in 2005. The ... [more ▼]

The space based mission Pegase was proposed to CNES in the framework of its call for scientific proposals for formation flying missions. This paper presents a summary of the phase-0 performed in 2005. The main scientific goal is the spectroscopy of hot Jupiters (Pegasides) and brown dwarfs from 2.5 to 5 mum. The mission can extend to other objectives such as the exploration of the inner part of protoplanetary disks, the study of dust clouds around AGN,... The instrument is basically a two-aperture (D=40 cm) interferometer composed of three satellites, two siderostats and one beam-combiner. The formation is linear and orbits around L2, pointing in the anti-solar direction within a +/-30° cone. The baseline is adjustable from 50 to 500 m in both nulling and visibility measurement modes. The angular resolution ranges from 1 to 20 mas and the spectral resolution is 60. In the nulling mode, a 2.5 nm rms stability of the optical path difference (OPD) and a pointing stability of 30 mas rms impose a two level control architecture. It combines control loops implemented at satellite level and control loops operating inside the payload using fine mechanisms. According to our preliminary study, this mission is feasible within an 8 to 9 years development plan using existing or slightly improved space components, but its cost requires international cooperation. Pegase could be a valuable Darwin/TPF-I pathfinder, with a less demanding, but still ambitious, technological challenge and a high associated scientific return. [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
See detailALADDIN: an optimized nulling ground-based demonstrator for DARWIN
Coudé du Foresto, V.; Absil, Olivier ULg; Swain, M. et al

in Monnier, John; Schöller, Markus; Danchi, William (Eds.) Advances in Stellar Interferometry (2006, July 01)

The ESA Darwin space mission will require a ground based precursor to i/ demonstrate nulling interferometry in an operational context and ii/ carry out some precursor science, such as the characterization ... [more ▼]

The ESA Darwin space mission will require a ground based precursor to i/ demonstrate nulling interferometry in an operational context and ii/ carry out some precursor science, such as the characterization of the level of exozodiacal light around the main Darwin targets. These are the stated objectives of the GENIE nulling instrument that was studied for the VLTI. We argue here that the same objectives can be met in a more efficient way by an antarctic-based nulling experiment. The ALADDIN mission concept is an integrated L-band nulling breadboard with relatively modest collectors (1m) and baseline (40m). Because of its privileged location, this is suffcient to achieve a sensitivity (in terms of detectable zodi levels) which is 1.6 to 3.5 times better than GENIE at the VLTI, bringing it below the 20-zodi threshold value identified to carry out the Darwin precursor science. The integrated design enables top-level optimization and full access to the light collectors for the duration of the experiment, while reducing the complexity of the nulling breadboard. [less ▲]

Detailed reference viewed: 8 (3 ULg)
Full Text
See detailConceptual design of the ALADDIN Antarctic nulling interferometer
Barillot, Marc; Courteau, Pascal; Absil, Olivier ULg et al

in Monnier, John; Schöller, Markus; Danchi, William (Eds.) Advances in Stellar Interferometry (2006, July 01)

It is commonly accepted that highly challenging planet finding missions such as Darwin and TPF need precursors on the ground, for both technological demonstration and study of the exozodiacal clouds ... [more ▼]

It is commonly accepted that highly challenging planet finding missions such as Darwin and TPF need precursors on the ground, for both technological demonstration and study of the exozodiacal clouds around potential targets. A first instrument, GENIE, designed to be implemented in the interferometric laboratory of the VLTI, was studied by ESA and scientific/industrial teams. In this paper we present a concept for ALADDIN, an operational nulling instrument to be implemented at Dome C in Antarctica, and discuss the comparison with GENIE from the instrumental point of view. Our preliminary design involves moderate ~1m size telescopes mounted on a 40m long rotating beam allowing baselines up to 30m and feeding a 2-arm nulling beam combiner. When compared to GENIE, the rotating beam design has the advantage of removing the need for both long-stroke delay line and dispersion control equipments. As a side effect, the instrumental arrangement of ALADDIN finds itself more representative of what Darwin will be. Furthermore, critical issues like phase control, photometric balance and instrumental background suppression are expected to be relaxed by the improved atmospheric conditions, lower temperature, and simpler optical trains. Calibration of geometrical stellar leakage will make advantage of the continuously adjustable baseline. As results, a simpler instrument showing improved performance is expected. In conclusion, we see our ALADDIN concept as a valuable alternative to GENIE, with a quite stronger scientific potential and a considerably simplified instrumental design. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Full Text
See detailDetection of the inner-debris disk of Vega with CHARA/FLUOR
Absil, Olivier ULg; Di Folco, Emmanuel; Mérand, Antoine et al

in Monnier, John; Schöller, Markus; Danchi, Willian (Eds.) Advances in Stellar Interferometry (2006, July 01)

Using the FLUOR beam-combiner installed at the CHARA Array (Mt. Wilson, CA), we have obtained highprecision visibility measurements of Vega, one of the prototypic debris-disk stars, known to be surrounded ... [more ▼]

Using the FLUOR beam-combiner installed at the CHARA Array (Mt. Wilson, CA), we have obtained highprecision visibility measurements of Vega, one of the prototypic debris-disk stars, known to be surrounded by a large amount of cold dust in a ring-like structure at 80-100 AU. The combination of short and long baselines has allowed us to separately resolve the stellar photosphere and the close environment of the star (less than 8 AU). Our observations show a significant deficit in square visibility at short baselines with respect to the expected visibility of a simple UD stellar model (DeltaV2 equal or equivalent to 2%), suggesting the presence of an extended source of emission around Vega. The sparse (u, v) plane coverage does not allow the discrimination between a point source and an extended circumstellar emission as the source of the extended emission. However, we show that the presence of a point-like source within the FLUOR field-of-view (1" in radius, i.e., 7.8 AU at the distance of Vega) is highly unlikely. The excess emission is most likely due to the presence of hot circumstellar dust in the inner part of Vega's debris disk, with a flux ratio of 1.29 plus or minus 0.19% between the integrated dust emission and the stellar photosphere. Complementing this result with archival photometric data in the near- and mid-infrared and taking into account a realistic photospheric model for the rapidly rotating Vega, we derive the expected physical properties of the circumstellar dust by modelling its Spectral Energy Distribution. The inferred properties suggest that the Vega system could be currently undergoing major dynamical perturbations. [less ▲]

Detailed reference viewed: 15 (1 ULg)
Full Text
Peer Reviewed
See detailFirst Results from the CHARA Array. VII. Long-Baseline Interferometric Measurements of Vega Consistent with a Pole-On, Rapidly Rotating Star
Aufdenberg, J. P.; Mérand, A.; Coudé du Foresto, V. et al

in Astrophysical Journal (2006), 645

We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K' band at projected baselines between 103 and 273 m. The measured visibility ... [more ▼]

We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K' band at projected baselines between 103 and 273 m. The measured visibility amplitudes beyond the first lobe are significantly weaker than expected for a slowly rotating star characterized by a single effective temperature and surface gravity. Our measurements, when compared to synthetic visibilities and synthetic spectrophotometry from a Roche-von Zeipel gravity-darkened model atmosphere, provide strong evidence for the model of Vega as a rapidly rotating star viewed very nearly pole-on. Our best-fitting model indicates that Vega is rotating at ~91% of its angular break-up rate with an equatorial velocity of 275 km s[SUP]-1[/SUP]. Together with the measured vsini, this velocity yields an inclination for the rotation axis of 5deg. For this model the pole-to-equator effective temperature difference is ~2250 K, a value much larger than previously derived from spectral line analyses. A polar effective temperature of 10,150 K is derived from a fit to ultraviolet and optical spectrophotometry. The synthetic and observed spectral energy distributions are in reasonable agreement longward of 140 nm, where they agree to 5% or better. Shortward of 140 nm, the model is up to 10 times brighter than observed. The model has a luminosity of ~37 L[SUB]solar[/SUB], a value 35% lower than Vega's apparent luminosity based on its bolometric flux and parallax, assuming a slowly rotating star. Our model predicts the spectral energy distribution of Vega as viewed from its equatorial plane, and it may be employed in radiative models for the surrounding debris disk. [less ▲]

Detailed reference viewed: 29 (1 ULg)
Full Text
Peer Reviewed
See detailLes grandes tailles: quelques grands syndromes et revue de la litterature
Gusbin, Natacha ULg; Verloes, Alain ULg; Daly, Adrian ULg et al

in Revue Médicale de Liège (2006), 61(7-8, Jul-Aug), 572-80

We describe the findings of XYY syndrome in the setting of encountering an individual with this particular condition in the endocrinology clinic. XYY syndrome is a relatively frequent if unfamiliar ... [more ▼]

We describe the findings of XYY syndrome in the setting of encountering an individual with this particular condition in the endocrinology clinic. XYY syndrome is a relatively frequent if unfamiliar condition, which is characterized by taller than average height. The extra Y chromosome may play a role in determining the height of these individuals. From this case, a differential diagnosis of tall stature is outlined, in addition to a description of the principal syndromes associated with gigantism. These primarily include Klinefelter syndrome, Marfan syndrome, androgen resistance and growth hormone excess. These various entities are described from the point of view of their symptomatology, biology, pathophysiology and therapeutic characteristics. [less ▲]

Detailed reference viewed: 123 (7 ULg)
Full Text
See detailPotential antimalarial activity of indole alkaloids
Angenot, Luc ULg

in 42nd International meeting on medicinal chemistry- Program and abstracts (2006, July)

Detailed reference viewed: 22 (0 ULg)
Full Text
Peer Reviewed
See detailA nation-wide pilot project for early rehabilitation of low back pain workers
Mairiaux, Philippe ULg; DELARUELLE D.; STRAUSS, Patrick

in IEA 2006 Proccedings (2006, July)

As a result of both a political and a scientific thinking, the Belgian Fund for Occupational Diseases (FOD) has launched, starting March 1st 2005, a pilot project for the nursing staff in the health care ... [more ▼]

As a result of both a political and a scientific thinking, the Belgian Fund for Occupational Diseases (FOD) has launched, starting March 1st 2005, a pilot project for the nursing staff in the health care sector in order to prevent the transition of low back pain (LBP) to chronicity through a program promoting an early return to work. Target workers are those being off work due to LBP for at least 4 weeks and maximum 3 months. The program involves a standardised multidisciplinary back rehabilitation program on the one hand, and on the other hand an ergonomics intervention in the health care institution. Depending on the context, the workplace intervention may involve an ergonomic analysis with the participation of the sicklisted worker, a larger group-based ergonomics redesign, or temporary change in the worker duty or work time in order to facilitate his/her return to work. The employer gets a financial incentive from the FOD when he agrees to such an intervention. Due to a lack of communication among the target population, this pilot project has had a slow start; the presentation gives a qualitative overview of the first 100 cases having entered the program. [less ▲]

Detailed reference viewed: 12 (3 ULg)