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See detailAn Arbitrary Lagrangian Eulerian Formulation for the Numerical Simulation of Forming Processes
Boman, Romain ULg; Papeleux, Luc ULg; Ponthot, Jean-Philippe ULg

in International Workshop 2007: Advancements in Design Optimization of Materials, Structures and Mechanical Systems (2007, December)

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See detailProgresse-t-on en enseignement des langues étrangères?
Defays, Jean-Marc ULg

Scientific conference (2007, December)

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See detailStabilization of Collective Motion in Three Dimensions : A Consensus Approach
Scardovi, Luca; Leonard, Naomi; Sepulchre, Rodolphe ULg

in Proceedings of 46th IEEE Conference on Decision and Control (2007, December)

This paper proposes a methodology to stabilize relative equilibria in a model of identical, steered particles moving in three- dimensional Euclidean space. Exploiting the Lie group structure of the ... [more ▼]

This paper proposes a methodology to stabilize relative equilibria in a model of identical, steered particles moving in three- dimensional Euclidean space. Exploiting the Lie group structure of the resulting dynamical system, the stabilization problem is reduced to a consensus problem on the Lie algebra. The resulting equilibria correspond to parallel, circular and helical formations. We rst derive the stabilizing control laws in the presence of all-to-all communication. Providing each agent with a consensus estimator, we then extend the results to a general setting that allows for unidirectional and time-varying communication topologies. [less ▲]

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See detailAutonomous rigid body attitude synchronization
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg; Leonard, Naomi

in Proceedings of the 46th IEEE Conference on Decision and Control (2007, December)

This paper studies some extensions to the decentralized attitude synchronization of identical rigid bodies. Considering fully actuated Euler equations, the communication links between the rigid bodies are ... [more ▼]

This paper studies some extensions to the decentralized attitude synchronization of identical rigid bodies. Considering fully actuated Euler equations, the communication links between the rigid bodies are limited and the available information is restricted to relative orientations and angular velocities. In particular, no leader nor external reference dictates the swarm's behavior. The control laws are derived using two classical approaches of nonlinear control - tracking and energy shaping. This leads to a comparison of two corresponding methods which are currently considered for distributed synchronization - consensus and stabilization of mechanical systems with symmetries. [less ▲]

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See detailCaractérisation physiologique et biochimique du processus de vieillissement du tubercule de pomme de terre (Solanum tuberosum L.)
Delaplace, Pierre ULg

Doctoral thesis (2007)

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the ... [more ▼]

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the biochemical processes underlying ageing, potato seed tubers (cv. Bintje and Désirée) were stored at 4°C for 7 months and regularly sampled to assess both physiological and biochemical parameters. Physiological age markers (PAI, incubation period) evolution was measured and allowed us to define a reference frame more accurate than the chronological age. A correlation has also been established with the growth parameters (number of stems, duration before emergence). In parallel, two biochemical approaches allowed us to assay proteome and antioxidant system modifications occurring during ageing. Protein pattern evolution was assessed by DIGE after hot SDS extraction. During ageing, 93 spots were strictly up- or down- regulated while 4 others exhibited an abundance curve with a transient maximum. After manual picking of 43 selected spots based on their expression profile, 32 proteins were identified by MS/MS. Differentially expressed proteins are mainly involved in patatin catabolism, stress response, glycolysis, protein turn-over and lipid oxidation. A complementary targeted approach has then been set up based on the free radical ageing theory. SOD, CAT, APX and POX activities as well as ascorbate, glutathione, carotenoid and phenolic compound contents were measured during ageing. These data seem to indicate that the antioxidant system undergoes marked changes in response to an increased production of reactive oxygen species. However, no accumulation of oxidative damages has been observed on lipids and proteins. All these kinetic data allowed us to build an integrated ageing model. These results are discussed in the above-mentioned theoretical context. [less ▲]

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See detailPredatory boreholes in Tournaisian (Lower Carboniferous) spiriferid brachiopods
Mottequin, Bernard ULg; Sevastopulo, George

in Budd, G. E.; Streng, M.; Daley, A. C. (Eds.) et al Programme with abstracts of the 51st Palaeontological Association Annual Meeting (2007, December)

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See detailObservations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456
Randall, Suzanna K.; Green, Elizabeth M.; Van Grootel, Valérie ULg et al

in Astronomy and Astrophysics (2007), 476

Aims:The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to ... [more ▼]

Aims:The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to constrain the internal characteristics of hot B subdwarfs with the long-term goal of differentiating between the various formation scenarios proposed for these objects. So far, a detailed asteroseismic interpretation has been carried out for 6 such pulsators, with apparent success. First comparisons with evolutionary theory look promising, however it is clear that more targets are needed for meaningful statistics to be derived. Methods: The observational pulsation periods of PG 0911+456 were extracted from rapid time-series photometry using standard Fourier analysis techniques. Supplemented by spectroscopic estimates of the star's mean atmospheric parameters, they were used as a basis for the “forward modelling” approach in asteroseismology. The latter culminates in the identification of one or more “optimal” models that can accurately reproduce the observed period spectrum. This naturally leads to an identification of the oscillations detected in terms of degree ℓ and radial order k, and infers the structural parameters of the target. Results: The high S/N low- and medium resolution spectroscopy obtained led to a refinement of the atmospheric parameters for PG 0911+456, the derived values being T_eff = 31 940 ± 220 K, log g = 5.767 ± 0.029, and log He/H = -2.548 ± 0.058. From the photometry it was possible to extract 7 independent pulsation periods in the 150-200 s range with amplitudes between 0.05 and 0.8% of the star's mean brightness. There was no indication of fine frequency splitting over the 68-day time baseline, suggesting a very slow rotation rate. An asteroseismic search of parameter space identified several models that matched the observed properties of PG 0911+456 well, one of which was isolated as the “optimal” model on the basis of spectroscopic and mode identification considerations. All the observed pulsations are identified with low-order acoustic modes with degree indices ℓ = 0,1,2 and 4, and match the computed periods with a dispersion of only 0.26%, typical of the asteroseismological studies carried out to date for this type of star. The inferred structural parameters of PG 0911+456 are T_eff = 31 940 ± 220 K (from spectroscopy), log {g} = 5.777 ± 0.002, Mast/Msun = 0.39 ± 0.01, log{M_env/Mast} = -4.69 ± 0.07, R/Rsun = 0.133 ± 0.001 and L/Lsun = 16.4 ± 0.8. We also derive the absolute magnitude MV = 4.82 ± 0.04 and a distance d = 930.3 ± 27.4 pc. [less ▲]

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See detailLa circonscription fédérale : un placebo administré à un malade incurable?
Bouhon, Frédéric ULg

E-print/Working paper (2007)

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See detailNoël en famille ou 15 litres de pétrole
Ozer, Pierre ULg; Perrin, Dominique ULg

Article for general public (2007)

La semaine précédant Noël, j’ai décortiqué les publicités de mon hypermarché le plus proche pour préparer le repas familial tant attendu. Et voici ce que j’ai pu concocter pour huit personnes avec, entre ... [more ▼]

La semaine précédant Noël, j’ai décortiqué les publicités de mon hypermarché le plus proche pour préparer le repas familial tant attendu. Et voici ce que j’ai pu concocter pour huit personnes avec, entre parenthèses, les kilomètres parcourus entre le pays de production et la Belgique ainsi que les kilogrammes de CO2 émis uniquement pour le transport aérien intercontinental de ces produits achetés. L’analyse se focalise sur le transport par voie aérienne puisque celui-ci émet, en moyenne, 60 fois plus de CO2 que le transport par voie maritime. [less ▲]

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See detailNoms de lieux du Grand-Bornand
Delorme, Jérémie ULg

Conference given outside the academic context (2007)

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See detailIntussen aan de kersttafel...
Ozer, Pierre ULg; Perrin, Dominique ULg

Article for general public (2007)

De afgelopen weken heb ik de reclamefolders van mijn dichtstbijzijnde hypermarkt uitgeplozen om een fijn dineetje samen te stellen. Hierna volgt het resultaat voor acht personen, met tussen haakjes het ... [more ▼]

De afgelopen weken heb ik de reclamefolders van mijn dichtstbijzijnde hypermarkt uitgeplozen om een fijn dineetje samen te stellen. Hierna volgt het resultaat voor acht personen, met tussen haakjes het aantal kilometers dat elk ingrediënt heeft afgelegd om naar België te komen en de hoeveelheid CO2 in kilogram die het transport geproduceerd heeft. Ik heb vooral ingrediënten gekozen die met het vliegtuig worden aangevoerd, want luchttransport produceert gemiddeld zestig keer meer CO2 dan vervoer over zee. [less ▲]

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See detailLes sphères publiques dans les pays arabo-islamiques. Construction d’un cadre d’analyse pour l’étude de la situation actuelle
Nachi, Mohamed ULg

Scientific conference (2007, December)

Construction d’un cadre d’analyse pour l’étude des espaces publics au Maghreb

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See detailEndometrial vessel maturation in women exposed to levonorgestrel-releasing intrauterine system for a short or prolonged period of time
Ravet, Stéphanie ULg; Labied, Soraya ULg; Blacher, Silvia ULg et al

in Human Reproduction (2007), 22(12), 3084-3091

BACKGROUND: Levonorgestrel-releasing intrauterine system (LNG-IUS), although inserted to reduce heavy menstruation, causes irregular early transient bleeding. The objective of the study was to document ... [more ▼]

BACKGROUND: Levonorgestrel-releasing intrauterine system (LNG-IUS), although inserted to reduce heavy menstruation, causes irregular early transient bleeding. The objective of the study was to document quantitative changes in endometrial vessels of short- (< or =3 months) and long-term (> or =12 months) LNG users. The area, density and maturation of endometrial vessels were quantified in 19 endometrial biopsies of women with LNG-IUS and in 10 normally ovulating patients during mid-luteal phase. METHODS: Vessel maturation was evaluated by double immunostaining using anti-von Willebrand factor (endothelial cell marker) and anti-alpha Smooth Muscle Actin (vascular smooth muscle cells) antibodies. Vessel area, number and density were quantified with a novel computer-assisted image analysis system. RESULTS: Endometrium exposed to LNG-IUS for 1-3 months displayed a 11.5-fold increase in small naked vessel number. The partially mature vessel (alphaSMA partially positive) number increased six times. After long-term LNG-IUS treatment, the immature and partially mature vessel number remained four times higher than in the control group. Vessel area and density also increased dramatically in a time-dependent pattern with LNG-IUS use. CONCLUSIONS: Levonorgestrel affects blood vessel number, area, density and maturation in a time-dependent pattern that may explain the early transient increase in breakthrough bleeding with the LNG-IUS. [less ▲]

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See detailFolate receptor autoimmunity and cerebral folate deficiency in low-functioning autism with neurological deficits
RAMAEKERS, Vincent ULg; Blau, N.; Sequeira, J. M. et al

in Neuropediatrics (2007), 38(6), 276-281

Reduced folate transport to the CNS was identified in two autism spectrum disorders, i.e., Rett syndrome and infantile low-functioning autism with neurological abnormalities. Twenty-five patients with ... [more ▼]

Reduced folate transport to the CNS was identified in two autism spectrum disorders, i.e., Rett syndrome and infantile low-functioning autism with neurological abnormalities. Twenty-five patients with early-onset low-functioning autism with or without neurological deficits, were evaluated for serum folate, cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF), and serum FR autoantibodies of the blocking type to determine the significance of folate receptor (FR) autoantibodies with respect to folate transport across the blood-CSF barrier. In spite of normal serum folate, CSF 5MTHF was low in 23 of 25 patients. The reduced CSF folate in 19 of these 23 patients could be explained by serum FR autoantibodies blocking the folate binding site of the membrane-attached FR on the choroid epithelial cells. Oral folinic acid supplements led to normal CSF 5MTHF and partial or complete clinical recovery after 12 months. Serum FR autoimmunity appears to represent an important factor in the pathogenesis of reduced folate transport to the nervous system among children with early-onset low-functioning autism associated with or without neurological deficits. Early detection of FR autoantibodies may be a key factor in the prevention and therapeutic intervention among this subgroup of patients with autism. © Georg Thieme Verlag KG Stuttgart. [less ▲]

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See detailL'image du mois. Un syndrome d' Asherman
Desirotte, Gaëlle ULg; Foidart, Jean-Michel ULg; Nisolle, Michelle ULg

in Revue Médicale de Liège (2007), 62(12), 697-8

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See detailApproche ethnopharmacologique de plantes utilisées en médecine traditionnelle au Cambodge dans le traitement des maladies infectieuses, des fièvres et du paludisme
Cheng, S. K.; Chea, Aun; Hout, Sothera et al

in Ethnopharmacologia (2007), 40

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