Publications ORBi OA
Bookmark and Share    
Full Text
Peer Reviewed
See detailMorphology of the ultraviolet Io footprint emission and its control by Io's location
Gérard, Jean-Claude ULg; Saglam, Adem ULg; Grodent, Denis ULg et al

in Journal of Geophysical Research. Space Physics (2006), 111(A4),

[1] A total of 74 images of the ultraviolet footprint of the Io flux tube (IFT) on Jupiter's upper atmosphere made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope have ... [more ▼]

[1] A total of 74 images of the ultraviolet footprint of the Io flux tube (IFT) on Jupiter's upper atmosphere made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope have been analyzed to characterize their location, morphology, and brightness distribution. The observations cover a wide range of central meridian Jovian longitudes and Io orbital positions and include north and south footprint emissions. Comparing the location of the IFT with that expected from the VIP4 model of the Jovian magnetic field, we find that the lead angle is generally not significantly different from zero in the System III longitude sector 125 degrees - 195 degrees. Instead, the lead angles reach about 8 degrees in the 50 degrees sector, coinciding with a region of possible magnetic anomaly. We observe that the brightness of the main footprint shows intrinsic intensity changes that appear to be controlled by the system III longitude of Io and its position above or below the center of the torus. The size of the primary spot magnetically maps into a region varying from 1 to over 10 Io diameters in Io's orbital plane. Multiple footprints are observed with varying brightness relative to the mean spot. The number of spots is found to increase as Io gets closer to the torus outer edge facing the spots. The separation between the first and second spots is typically 1 degrees-3 degrees of longitude and increases when Io is displaced from the torus center in the direction of the IFT signature. These features confirm that Alfven waves play an important role and generate energization of precipitated electrons. However, the observed variation of the FUV spot structure with Io's position appears inconsistent with models where reflections of Alfven wings occur between the torus boundary and Jupiter's ionosphere. Instead, the multiple spots apparently correspond to electron precipitation generated by Alfven waves reflected inside the plasma torus. [less ▲]

Detailed reference viewed: 27 (1 ULg)
Full Text
Peer Reviewed
See detailMulti-wavelength study of the gravitational lens system RXS J113155.4-123155. I. Multi-epoch optical and near infrared imaging
Sluse, Dominique ULg; Claeskens, Jean-François ULg; Altieri, B. et al

in Astronomy and Astrophysics (2006), 449

Aims.RXS J113155.4-123155 (z=0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly ... [more ▼]

Aims.RXS J113155.4-123155 (z=0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly accurate astrometry and photometry. These observational constraints constitute a mandatory ingredient for the precise determination of the lens mass profile, the derivation of the Hubble constant H[SUB]0[/SUB] from time delay measurements and investigations on the presence of massive substructures in the lensing galaxy.Methods.Visible and near-infrared imaging observations of RXS J113155.4-123155 were carried out at various epochs using several ground based telescopes and the HST. The frames have been deconvolved using the MCS algorithm. A Singular Isothermal Ellipsoid (SIE) + external shear has been used to model the lensing galaxy potential. Results. MCS deconvolution enables us to separate the flux of the QSO (point-like images) from that of its host galaxy and to accurately track the flux variations of the point-like images in various filters. The deconvolved frames unveil several multiply imaged structures in the Einstein ring and an unidentified object in the vicinity of the lensing galaxy. We discuss the lightcurves and the chromatic flux ratio variations and deduce that both intrinsic variability and microlensing took place during a span longer than one year. We demonstrate that microlensing may easily account for the so called anomalous flux ratios presented in the discovery paper. However, the observed flux ratios are still poorly reproduced when modeling the lens potential with a SIE+shear. We argue that this disagreement can hardly be explained by milli-lensing caused by substructures in the lensing galaxy. A solution proposed in Paper II consists in a more complex lens model including an octupole term to the lens gravitational potential. [less ▲]

Detailed reference viewed: 33 (20 ULg)
Full Text
Peer Reviewed
See detailEpilepsie chez des enfants infirmes moteurs-cérébraux
Peduzzi, M.; Defontaine, E.; Misson, Jean-Paul ULg

in Revue Médicale de Liège (2006), 61(4), 237-239

The incidence of epilepsy in 110 patients with cerebral palsy (the majority with spastic tetraplegia) was 46,4%. Almost half of the patients with spastic tetraplegia (45%) and hemiplegia (52%) had ... [more ▼]

The incidence of epilepsy in 110 patients with cerebral palsy (the majority with spastic tetraplegia) was 46,4%. Almost half of the patients with spastic tetraplegia (45%) and hemiplegia (52%) had epilepsy. The incidence was lower in patients with spastic diplegia (32%). Half of epilepsy in spastic hemiplegia were partial seizures and the other half consisted of generalized seizures, while generalized tonic-clonic episodes predominated in all other forms of C.P. A high incidence of West syndrome was observed in patients with spastic tetraplegia. Etiological factors of C.P. were perinatal in 75%. 16,65% had neonatal antecedents of convulsions; most of them had spastic tetraplegia (75%) and a significant mental retardation. A low intelligence quotient (I.Q.) was seen in most of the children with epilepsy, and patients with tetraplegia had significantly lower intelligence quotient than other groups. [less ▲]

Detailed reference viewed: 133 (10 ULg)
Full Text
See detailAnalysis of Code Procedures for Seismic Assessment of Existing Buildings: Italian Seismic Code, EC8, ATC-40, FEMA356, FEMA440
Mihaylov, Boyan ULg

Master of advanced studies dissertation (2006)

It is widely recognized that ground shaking may induce unacceptable levels of damage in existing buildings located in seismic regions. This vulnerability has been attributed to several reasons, such as ... [more ▼]

It is widely recognized that ground shaking may induce unacceptable levels of damage in existing buildings located in seismic regions. This vulnerability has been attributed to several reasons, such as insufficient strength and stiffness, poor detailing, irregularities in plan and elevation, domination of brittle failure modes over ductile ones, etc. On account of that, seismic assessment of existing buildings is adopted as a problem which needs specific treatment in building codes. The present study analyzes five codes for assessment of existing buildings: the Italian seismic code, EC8, FEMA356, ATC-40 and FEMA440. The analysis of each code is performed within a common theoretical frame. The code assumptions and simplifications are pointed out together with their possible inconsistencies and weaknesses. Comparisons between the different procedures are performed as well. The most important outcomes stress insufficiencies in the analysis procedures as well as in the criteria for choice of model dimension and analysis type, consideration of dynamic P-Δ effects, in non-linear modeling, shear resistance evaluation, and application of force-based procedures. [less ▲]

Detailed reference viewed: 77 (7 ULg)
Full Text
See detailVingt cerises sur le gâteau
Habrand, Tanguy ULg

Article for general public (2006)

Detailed reference viewed: 21 (1 ULg)
Full Text
Peer Reviewed
See detailMolecular phylogeny of the Cricetinae subfamily based on the mitochondrial cytochrome b and 12S rRNA genes and the nuclear vWF gene
Neumann, K.; Michaux, Johan ULg; Lebedev, V. et al

in Molecular Phylogenetics and Evolution (2006), 39(1), 135-148

Despite some popularity of hamsters as pets and laboratory animals there is no reliable phylogeny of the subfamily Cricetinae available so far. Contradicting views exist not only about the actual number ... [more ▼]

Despite some popularity of hamsters as pets and laboratory animals there is no reliable phylogeny of the subfamily Cricetinae available so far. Contradicting views exist not only about the actual number of species but also concerning the validity of several genera. We used partial DNA sequences of two mitochondrial (cytochrome b, 12S rRNA) and one partial nuclear gene (von Willebrand Factor exon 28) to provide a first gene tree of the Cricetinae based on 15 taxa comprising six genera: According to our data, Palaearctic hamsters fall into three distinct phylogenetic groups: Phodopits, Mesocricetus, and Cricetus-related species which evolved during the late Miocene about 7-12 MY ago. Surprisingly, the genus Phodopus, which was previously thought to have appeared during the Pleistocene, forms the oldest clade. The largest number of extant hamster genera is found in a group of Cricetus-related hamsters. The genus Cricetulus itself proved to be not truly monophyletic with Cricetulus migratorius appearing more closely related to Tscherskia, Cricetus, and Allocricetulus. We propose to place the species within a new monotypic genus. Molecular clock calculations are not always in line with the dating of fossil records. DNA based divergence time estimates as well as taxonomic relationships demand a reevaluation of morphological characters previously used to identify fossils and extant hamsters. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

Detailed reference viewed: 28 (1 ULg)
Full Text
See detailSeconde campagne de mesure des odeurs sur le CET de Happe- Chapois Estimation des nuisances olfactives
Nicolas, Jacques ULg; Denne, Pierre; Cobut, Pierre

Report (2006)

The study is conducted in the frame of a programme of monitoring of all landfill sites in Wallonia. The "odour" part is assigned to ULg. The present report concerns more particularly a second campaign on ... [more ▼]

The study is conducted in the frame of a programme of monitoring of all landfill sites in Wallonia. The "odour" part is assigned to ULg. The present report concerns more particularly a second campaign on the site of Happe-Chapois. Besides the usual field inspection technique, the research group has used dynamic olfactometry to estimate the odour flux emitted by the tipping area, through a sample collected by a dynamic flux chamber. The report presents also a critical discussion about the advantages and limits of the field inspection technique. [less ▲]

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailFinancing of Women-Owned Ventures: The Impact of Gender and Other Owner- and Firm-Related Variables
Constantinidis, Christina ULg; Cornet, Annie ULg; Asandei, Simona

in Venture Capital (2006), 8(2), 133-157

While women-owned ventures represent an increasing proportion of new businesses in most western countries, most of them have particular financing patterns and encounter barriers in their access to ... [more ▼]

While women-owned ventures represent an increasing proportion of new businesses in most western countries, most of them have particular financing patterns and encounter barriers in their access to financing. Recent research on the question argues that barriers to financing are mainly dependent on factors other than gender, such as owner- and firm-related characteristics. This quantitative and qualitative study, through descriptive statistics and interview analysis, examines the relationship between financing patterns and barriers and gender from the woman entrepreneur’s viewpoint. It explores the behaviours and representations of women entrepreneurs towards financing, and considers to what extent the women see their own approaches as being different from those of men. Our study suggests that a gender effect still exists, and tries to identify its location and the corresponding implications for further research and action. [less ▲]

Detailed reference viewed: 98 (10 ULg)
Full Text
Peer Reviewed
See detailPsychrophilic microorganisms: challenges for life
D'Amico, Salvino ULg; Collins, T.; Marx, J. C. et al

in EMBO Reports (2006), 7(4), 385-389

The ability of psychrophiles to survive and proliferate at low temperatures implies that they have overcome key barriers inherent to permanently cold environments. These challenges include: reduced enzyme ... [more ▼]

The ability of psychrophiles to survive and proliferate at low temperatures implies that they have overcome key barriers inherent to permanently cold environments. These challenges include: reduced enzyme activity; decreased membrane fluidity; altered transport of nutrients and waste products; decreased rates of transcription, translation and cell division; protein cold- denaturation; inappropriate protein folding; and intracellular ice formation. Cold- adapted organisms have successfully evolved features, genotypic and/ or phenotypic, to surmount the negative effects of low temperatures and to enable growth in these extreme environments. In this review, we discuss the current knowledge of these adaptations as gained from extensive biochemical and biophysical studies and also from genomics and proteomics. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
See detailImpacts de la mise en service d'une microcentrale hydroélectrique sur les populations de poissons de la Lhomme à Poix Saint-Hubert
Ovidio, Michaël ULg; Philippart, Jean-Claude ULg; Paquer, Frédéric ULg et al

Report (2006)

Ce rapport présente une partie des résultats des recherches menées dans le cadre d’une convention d’études 2005-2007 entre le Ministère de la Région Wallonne (Division de l’Eau, Direction des Cours d’Eau ... [more ▼]

Ce rapport présente une partie des résultats des recherches menées dans le cadre d’une convention d’études 2005-2007 entre le Ministère de la Région Wallonne (Division de l’Eau, Direction des Cours d’Eau Non Navigables) et l’Université de Liège (Laboratoire de Démographie des Poissons et d’Hydroécologie, Unité de Biologie du Comportement). L’objet particulier de la recherche évoquée est le suivi biologique de la population piscicole de la Lhomme à Poix Saint-Hubert après la construction et la mise en service en fin 2002 d’une microcentrale hydroélectrique par la société S.A. Hydroval. La réalisation de cette étude correspond à une étude d’impact a posteriori, dont la réalisation conditionnait l’octroi du permis d’exploitation. Cette recherche très ciblée est une composante d’une convention d’études générale intitulée « Définition de bases biologiques et éco-hydrauliques pour la libre circulation des poissons dans les cours d'eau non navigables de Wallonie ». [less ▲]

Detailed reference viewed: 66 (9 ULg)
Full Text
Peer Reviewed
See detailIFFT-equivariant quantizations
Boniver, Fabien; Mathonet, Pierre ULg

in Journal of Geometry and Physics (2006), 56(4), 712-730

The existence and uniqueness of quantizations that are equivariant with respect to conformal and projective Lie algebras of vector fields were recently obtained by Duval, Lecomte and Ovsienko. In order to ... [more ▼]

The existence and uniqueness of quantizations that are equivariant with respect to conformal and projective Lie algebras of vector fields were recently obtained by Duval, Lecomte and Ovsienko. In order to do so, they computed spectra of some Casimir operators. We give an explicit formula for those spectra in the general framework of IFFT-algebras classified by Kobayashi and Nagano. We also define tree-like subsets of eigenspaces of those operators in which eigenvalues can be compared to show the existence of IFFT-equivariant quantizations. We apply our results to prove the existence and uniqueness of quantizations that are equivariant with respect to the infinitesimal action of the symplectic (resp. pseudo-orhogonal) group on the symplectic (resp. pseudo-orthogonal) Grassmann manifold. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailProgramme d'action sur le lien entre santé et alimentation auprès des usagers des maisons médicales liégeoises
Lachaussée, Christine; Legrève, Christian; Miermans, Marie-Christine ULg

in Santé Conjuguée (2006), (36), 25-34

Detailed reference viewed: 54 (14 ULg)
Full Text
Peer Reviewed
See detailFasciites nécrosantes: stratégie diagnostique et thérapeutique
Smeets, Laurent ULg; Bous, Aurélie ULg; Lecoq, Jean-Pierre ULg et al

in Revue Médicale de Liège (2006), 61(4), 240-244

The necrotizing fasciitis is a medico-surgical emergency, characterized by the rapid speard of the infection in the subcutaneous tissue, involving fascia superficialis. Peaucity of cutaneous findings ... [more ▼]

The necrotizing fasciitis is a medico-surgical emergency, characterized by the rapid speard of the infection in the subcutaneous tissue, involving fascia superficialis. Peaucity of cutaneous findings early in the course of the disease makes diagnosis a challenge for physician. Pain out of proportion to clinical findings, fever and signs of systemic toxicity are the keys in identification of necrotizing fasciitis. Delayed diagnosis lead to sepsis syndrom and/or multiple organ failure and correlate with poor oucome. Radiolographs, CT-scan or MRI are main radiologic studies, but such procedures should never delay surgical intervention. Intravenous antibiotics, fluid and electrolyte management and analgesia are needed in addition to radical debridment. Clindamycin, hyperbaric oxygen therapy and intravenous immunoglobulins are discussed treatments. Only prompt recognition and immediat care warrant a lower mortality and morbidity for this life-threatening infection. [less ▲]

Detailed reference viewed: 122 (6 ULg)
Full Text
Peer Reviewed
See detailL'image du mois. Un cas inhabituel d'insuffisance aortique aigue
Quaniers, Janine ULg; Legrand, V.; Limet, Raymond ULg

in Revue Médicale de Liège (2006), 61(4), 211

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailOffline persistence of memory-related cerebral activity during active wakefulness
Peigneux, Philippe ULg; Orban, Pierre ULg; Balteau, Evelyne ULg et al

in PLoS Biology (2006), 4(4), 100

Much remains to be discovered about the fate of recent memories in the human brain. Several studies have reported the reactivation of learning-related cerebral activity during post-training sleep ... [more ▼]

Much remains to be discovered about the fate of recent memories in the human brain. Several studies have reported the reactivation of learning-related cerebral activity during post-training sleep, suggesting that sleep plays a role in the offline processing and consolidation of memory. However, little is known about how new information is maintained and processed during post-training wakefulness before sleep, while the brain is actively engaged in other cognitive activities. We show, using functional magnetic resonance imaging, that brain activity elicited during a new learning episode modulates brain responses to an unrelated cognitive task, during the waking period following the end of training. This post-training activity evolves in learning-related cerebral structures, in which functional connections with other brain regions are gradually established or reinforced. It also correlates with behavioral performance. These processes follow a different time course for hippocampus-dependent and hippocampus-independent memories. Our experimental approach allowed the characterization of the offline evolution of the cerebral correlates of recent memories, without the confounding effect of concurrent practice of the learned material. Results indicate that the human brain has already extensively processed recent memories during the first hours of post-training wakefulness, even when simultaneously coping with unrelated cognitive demands. [less ▲]

Detailed reference viewed: 48 (10 ULg)
Full Text
Peer Reviewed
See detailNouvelles frontières de l’entreprise et gestion de l’emploi, le cas des centres d’appels
Rorive, Brigitte; Naedenoen, Frédéric ULg

Conference (2006, April)

To understand the link between new corporate boundaries and employment management, we must take the heterogeneity of the call centers industry and its companies into account. Often described for the ... [more ▼]

To understand the link between new corporate boundaries and employment management, we must take the heterogeneity of the call centers industry and its companies into account. Often described for the degradation of the employment and work conditions that it creates, the call center industry is nevertheless far to response to an unique logic of job management. Through four case studies, diversified according to 2 axes: the level of added value offered by the call centers and its organizational complexity, let emerge different kind of logics, influenced by the position of the studied company on these two axes. They show the existence of a link between the configuration of inter-organizational relationship and the internal politics of human resources and employment management. This link has an effect on the extreme difficulty to conciliate the worker’s and the organizations’s interests, particularly when the client heavily intervene in the call center internal management , or influence strongly its operations by contractual requirements. [less ▲]

Detailed reference viewed: 130 (10 ULg)
Full Text
Peer Reviewed
See detailINTEGRAL detection of hard X-rays from NGC 6334: nonthermal emission from colliding winds or an AGN?
Bykov, A. M.; Krassilchtchikov, A. M.; Uvarov, Y. A. et al

in Astronomy and Astrophysics (2006), 449(3), 917-923

Aims. We report the detection of hard X-ray emission from the field of the star-forming region NGC 6334 with the International Gamma-Ray Astrophysics Laboratory INTEGRAL. Methods. The JEM-X monitor and ... [more ▼]

Aims. We report the detection of hard X-ray emission from the field of the star-forming region NGC 6334 with the International Gamma-Ray Astrophysics Laboratory INTEGRAL. Methods. The JEM-X monitor and ISGRI imager aboard INTEGRAL and Chandra ACIS imager were used to construct 3-80 keV images and spectra of NGC 6334. Results. The 3-10 keV and 10-35 keV images made with JEM-X show a complex structure of extended emission from NGC 6334. The ISGRI source detected in the energy ranges 20-40 keV, 40-80 keV, and 20-60 keV coincides with the NGC 6334 ridge. The 20-60 keV flux from the source is (1.8 +/- 0.37) x 10(-11) erg cm(-2) s(-1). Spectral analysis of the source revealed a hard power-law component with a photon index about 1. The observed X-ray fluxes are in agreement with extrapolations of X-ray imaging observations of NGC 6334 by Chandra ACIS and ASCAGIS. Conclusions. The X-ray data are consistent with two very different physical models. A probable scenario is emission from a heavily absorbed, compact and hard Chandra source that is associated with the AGN candidate radio source NGC 6334B. Another possible model is the extended Chandra source of nonthermal emission from NGC 6334 that can also account for the hard X-ray emission observed by INTEGRAL. The origin of the emission in this scenario is due to electron acceleration in energetic outflows from massive early type stars. The possibility of emission from a young supernova remnant, as suggested by earlier infrared observations of NGC 6334, is constrained by the non-detection of Ti-44 lines. [less ▲]

Detailed reference viewed: 35 (1 ULg)
Full Text
Peer Reviewed
See detailImportance of risk stratification models in cardiac surgery
Kolh, Philippe ULg

in European Heart Journal (2006), 27(7), 768-769

This editorial refers to 'Comparison of 19 pre-operative risk strati. cation models in open-heart surgery'dagger by J. Nilsson et al., on page 867.

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
See detailLes céphalées par abus d'antalgiques et d'anti-migraineux
Fumal, Arnaud ULg; Magis, Delphine ULg; Schoenen, Jean ULg

in Revue Médicale de Liège (2006), 61(4), 217-22

Medication overuse headache (MOH) insidiously evolves from episodic migraine or tension-type headache because of overconsumption of analgesics, ergotamine or triptans. It affects 1-2% of the general ... [more ▼]

Medication overuse headache (MOH) insidiously evolves from episodic migraine or tension-type headache because of overconsumption of analgesics, ergotamine or triptans. It affects 1-2% of the general population, but 15-20% of patients attending specialized headache centers. The precise neurobiologic mechanisms underlying this complication of episodic headaches are not well understood. Abnormalities of central monoaminergic systems have been suggested and substance dependence is more frequent in personal and family histories of affected subjects. In a recent FDG-PET study of 16 migraineurs with MOH before and after analgesics withdrawal we found a persistent hypometabolism of the medial orbitofrontal cortex, comparable to the one described after withdrawal in substance abuse. The orbitofrontal cortex plays a pivotal role in drive, decision-making and drug dependence. We postulate that its hypoactivity predisposes certain migraineurs to MOH and to relapse after withdrawal. There is no unique management strategy for these patients, but medication withdrawal is a prerequisite for the effectiveness of preventive treatments and headache improvement. [less ▲]

Detailed reference viewed: 82 (4 ULg)