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See detailORBi : pari tenu ?
Thirion, Paul ULg

Scientific conference (2012, October 19)

Detailed reference viewed: 591 (24 ULg)
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See detailORBi, archive ouverte de l'Université de Liège et PoPuPS, publications en open access de l'Université de Liège
Thirion, Paul ULg

Scientific conference (2010, September 22)

Présentations des initiatives en Open Access de l'Université de Liège (ULg) et de son Réseau des Bibliothèques : - PoPuPS : portail de publications de périodiques scientifique en Open Access - BICTEL/ e ... [more ▼]

Présentations des initiatives en Open Access de l'Université de Liège (ULg) et de son Réseau des Bibliothèques : - PoPuPS : portail de publications de périodiques scientifique en Open Access - BICTEL/ e : répertoire des thèses de doctorat en Open Access - ORBi : open repository and bibliography Présentation des projets, du "mandat ULg" (obligation de dépôt) et des résultats notamment en terme de bénéfices pour les chercheurs [less ▲]

Detailed reference viewed: 440 (68 ULg)
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See detailORBi, the open repository of Ulg and the geographers: first statistics analyzed
Stirbu, Simona ULg

Conference (2010, October 22)

Set up by the University of Liège, ORBi (Open Repository and Bibliography) knew a lightning increase of the deposits since its creation in 2008. The official launch took place on November 26th, 2008 and ... [more ▼]

Set up by the University of Liège, ORBi (Open Repository and Bibliography) knew a lightning increase of the deposits since its creation in 2008. The official launch took place on November 26th, 2008 and after considerable efforts on behalf of the team which manages the tool and researchers who introduce themselves their publications, the contents of the repository managed to reach a value of fifty thousand seven hundred references among which thirty thousand four hundred with full text. Working for the library of Geography of the University of Liège, I found interesting to bend over the "statistics" supplied by ORBi, concerning the number of visualizations and downloads of the references deposited by the geographers of Liège. On base of the statement of various "statistical" data and the analysis of these data, I try to determine if the deposit of the scientific works in ORBi increases - or may increase the visibility of the scientific works of the geographers from Liège. [less ▲]

Detailed reference viewed: 85 (45 ULg)
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See detailORBi@ULg: An exciting self archiving adventure
Thirion, Paul ULg

Scientific conference (2010, October 19)

Detailed reference viewed: 88 (25 ULg)
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See detailORBi@ULg: Are you crazy?
Thirion, Paul ULg

Scientific conference (2012, May 10)

Detailed reference viewed: 82 (31 ULg)
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See detailOrbit Determination for Gaia Spectroscopic Binaries
Jancart, Sylvie ULg; Pourbaix, D.

in O'Flaherty, K.S.; Perryman, M.A.C (Eds.) The Three-Dimensional Universe with Gaia (2005, January 01)

Synthetic radial velocities for a population of 2300+ known spectroscopic binaries are generated according to the present scanning law. The effect of the distribution of the observations and of the noise ... [more ▼]

Synthetic radial velocities for a population of 2300+ known spectroscopic binaries are generated according to the present scanning law. The effect of the distribution of the observations and of the noise on the orbit fitting is investigated. According to our preliminary results short periods, below one day, will be hard to identify among the many aliases, even in the absence of noise. Requirements in terms of computing power for this shell task are estimated in conjunction with the adopted algorithm for the period search part of the orbit reconstruction. These results are for binaries detected in the Radial Velocity Spectrometer only. [less ▲]

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See detailOrbital dynamics characteristics of a QB50 CubeSat performing atmospheric reentry
Asma, C.; Naviaux, J.; Kerschen, Gaëtan ULg et al

in Proceedings of the AIAA Atmospheric Flight Mechanics Conference (2010)

The QB50 mission has the scientific objective to study the temporal and spatial variations of a number of key parameters in the lower thermosphere with a network of 50 CubeSats, each performing identical ... [more ▼]

The QB50 mission has the scientific objective to study the temporal and spatial variations of a number of key parameters in the lower thermosphere with a network of 50 CubeSats, each performing identical in-situ measurements. One of these 50 CubeSats, the von Karman Institute Atmospheric Re-Entry CubeSat, will further be equipped by a thermal protection system and a dedicated sensor pack to study the atmospheric re-entry. This paper is devoted to the orbital dynamics analysis performed for the QB50 mission and the atmospheric re-entry trajectory analysis for a double unit CubeSat. The main focus is on the sensitivity of the results on atmospheric models, drag coefficient and the launch date. Typical atmospheric re-entry trajectories, including the stagnation point heat flux values are calculated using three different methods for three different scenarios. The predicted heat flux values will be used in the preliminary design of the thermal protection system of the VKI atmospheric re-entry CubeSat, which is to be the first CubeSat to be used as an atmospheric re-entry demonstrator. [less ▲]

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See detailAn orbital period of 0.94days for the hot-Jupiter planet WASP-18b
Hellier, Coel; Anderson, D. R.; Cameron, A Collier et al

in Nature (2009), 460

The `hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which ... [more ▼]

The `hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only ~0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94days and a mass of ten Jupiter masses (10M[SUB]Jup[/SUB]), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 10[SUP]6[/SUP], as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System. [less ▲]

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See detailOrbital rendez-vous using differential drag in the QB50 constellation
Dell'Elce, Lamberto ULg; Kerschen, Gaëtan ULg

in Proceedings of the AIAA/AAS Astrodynamics Specialist Conference (2012)

Detailed reference viewed: 26 (11 ULg)
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See detailLes orbites quasi elliptiques, les potentiels riemanniens et les forces centrales
Swings, Polydore ULg

in Bulletin de la Classe des Sciences. Académie Royale de Belgique (1927), XIII(2), 88-89

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See detailOrbitofrontal cortex involvement in chronic analgesic-overuse headache evolving from episodic migraine
Fumal, Arnaud ULg; Laureys, Steven ULg; Di Clemente, Laura et al

in Brain (2006), 129(Pt 2), 543-550

The way in which medication overuse transforms episodic migraine into chronic daily headache is unknown. To search for candidate brain areas involved in this process, we measured glucose metabolism with ... [more ▼]

The way in which medication overuse transforms episodic migraine into chronic daily headache is unknown. To search for candidate brain areas involved in this process, we measured glucose metabolism with 18-FDG PET in 16 chronic migraineurs with analgesic overuse before and 3 weeks after medication withdrawal and compared the data with those of a control population (n = 68). Before withdrawal, the bilateral thalamus, orbitofrontal cortex (OFC), anterior cingulate gyrus, insula/ventral striatum and right inferior parietal lobule were hypometabolic, while the cerebellar vermis was hypermetabolic. All dysmetabolic areas recovered to almost normal glucose uptake after withdrawal of analgesics, except the OFC where a further metabolic decrease was found. A subanalysis showed that most of the orbitofrontal hypometabolism was due to eight patients overusing combination analgesics and/or an ergotamine-caffeine preparation. Medication overuse headache is thus associated with reversible metabolic changes in pain processing structures like other chronic pain disorders, but also with persistent orbitofrontal hypofunction. The latter is known to occur in drug dependence and could predispose subgroups of migraineurs to recurrent analgesic overuse. [less ▲]

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See detailOrbitofrontal dysfunction related to both apathy and disinhibition in frontotemporal dementia
Peters, Frederic; Perani, Daniela; Herholz, Karl et al

in Dementia & Geriatric Cognitive Disorders (2006), 21(5-6), 373-379

Orbitofrontal metabolic impairment is characteristic of the frontal variant of frontotemporal dementia (fv-FTD), as are early changes in emotional and social conduct. Two main types of behavioral ... [more ▼]

Orbitofrontal metabolic impairment is characteristic of the frontal variant of frontotemporal dementia (fv-FTD), as are early changes in emotional and social conduct. Two main types of behavioral disturbances have been distinguished in fv-FTD patients: apathetic and disinhibited manifestations. In this study, we searched for relationships between brain metabolism and presence of apathetic or disinhibited behavior. Metabolic activity and behavioral data were collected in 41 fv-FTD patients from European PET centers. A conjunction analysis of the PET data showed an expected impairment of metabolic activity in the anterior cingulate, ventromedial and orbital prefrontal cortex, the dorsolateral prefrontal cortex and the left anterior insula in fv-FTD subjects compared to matched controls. A correlation was observed between disinhibition scores on the Neuropsychiatric Inventory scale and a cluster of voxels located in the posterior orbitofrontal cortex ( 6, 28, - 24). Comparison of brain activity between apathetic and nonapathetic fv-FTD patients from two centers also revealed a specific involvement of the posterior orbitofrontal cortex in apathetic subjects ( 4, 22, - 22). The results confirm that the main cerebral metabolic impairment in fv-FTD patients affects areas specializing in emotional evaluation and demonstrate that decreased orbitofrontal activity is related to both disinhibited and apathetic syndromes in fv-FTD. Copyright (C) 2006 S. Karger AG, Basel. [less ▲]

Detailed reference viewed: 76 (5 ULg)
See detailOrbits of Hipparcos metal-poor stars with well-defined spectroscopic abundances.
Bancken, F.; Jehin, Emmanuel ULg; Ferraz-Mello, S.

in Impact of Modern Dynamics in Astronomy (1998, July)

We investigate the orbits of metal-poor stars in a modified Ostriker and Caldwell Galactic mass model. These stars have well-determined spectroscopic abundances and our objective is to search for a ... [more ▼]

We investigate the orbits of metal-poor stars in a modified Ostriker and Caldwell Galactic mass model. These stars have well-determined spectroscopic abundances and our objective is to search for a relationship between these abundances and the characteristics of orbits such as excentricity, chaoticity... [less ▲]

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See detailOrbits of language operations: finiteness and upper bounds
Charlier, Emilie ULg

Scientific conference (2011, August)

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See detailThe order Herpesvirales.
Davison, Andrew J; Eberle, Richard; Ehlers, Bernhard et al

in Archives of Virology (2009), 154(1), 171-7

The taxonomy of herpesviruses has been updated by the International Committee on Taxonomy of Viruses (ICTV). The former family Herpesviridae has been split into three families, which have been ... [more ▼]

The taxonomy of herpesviruses has been updated by the International Committee on Taxonomy of Viruses (ICTV). The former family Herpesviridae has been split into three families, which have been incorporated into the new order Herpesvirales. The revised family Herpesviridae retains the mammal, bird and reptile viruses, the new family Alloherpesviridae incorporates the fish and frog viruses, and the new family Malacoherpesviridae contains a bivalve virus. Three new genera have been created in the family Herpesviridae, namely Proboscivirus in the subfamily Betaherpesvirinae and Macavirus and Percavirus in the subfamily Gammaherpesvirinae. These genera have been formed by the transfer of species from established genera and the erection of new species, and other new species have been added to some of the established genera. In addition, the names of some nonhuman primate virus species have been changed. The family Alloherpesviridae has been populated by transfer of the genus Ictalurivirus and addition of the new species Cyprinid herpesvirus 3. The family Malacoherpesviridae incorporates the new genus Ostreavirus containing the new species Ostreid herpesvirus 1. [less ▲]

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See detailOrder reduction in time integration caused by velocity projection
Arnold, Martin; Cardona, Alberto; Bruls, Olivier ULg

in Proceedings of the 3rd Joint International Conference on Multibody System Dynamics and the 7th Asian Conference on Multibody Dynamics (2014, July)

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may ... [more ▼]

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may formally be obtained from time derivatives of the original holonomic constraints. A numerical solution that satisfies hidden constraints as well as the original constraint equations may be obtained considering both types of constraints simultaneously in each time step (stabilized index-2 formulation) or using projection techniques. Both approaches are well established in the time integration of differential-algebraic equations. Recently, we have introduced a generalized- alpha Lie group time integration method for the stabilized index-2 formulation that achieves second order convergence for all solution components. In the present paper, we show that a separate velocity projection would be less favourable since it may result in an order reduction and in large transient errors after each projection step. This undesired numerical behaviour is analysed by a one-step error recursion that considers the coupled error propagation in differential and algebraic solution components. This one-step error recursion has been used before to prove second order convergence for the application of generalized-alpha methods to constrained systems. As a technical detail, we discuss the extension of these results from symmetric, positive definite mass matrices to the rank deficient case. [less ▲]

Detailed reference viewed: 9 (2 ULg)