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See detailDual approach using a variant perimeter constraint and efficient sub-iteration scheme for topology optimization
Zhang, Weihong; Duysinx, Pierre ULg

in Computers & Structures (2003), 81(22-23), 2173-2181

To prevent numerical instabilities associated with the mesh-dependence, checkerboards and grey regions in topology optimization, a variant perimeter-constrained version of the SIMP algorithm is proposed ... [more ▼]

To prevent numerical instabilities associated with the mesh-dependence, checkerboards and grey regions in topology optimization, a variant perimeter-constrained version of the SIMP algorithm is proposed using a smooth and quadratic function. In order to have an efficient implementation and to make sure the strict satisfaction of such an upper-bound perimeter constraint, a diagonal quadratic approximation of the perimeter constraint is used in the construction of each explicit optimization subproblem. The latter is then solved by a dual sub-iteration scheme. Numerical results show that the incorporation of such a sub-iteration scheme leads to a convergent solution without needs of move-limits or artificial control parameters. In addition to this, it is found that successive relaxations of the perimeter constraint by increasing the upper-bound tend to regularize the topology solution and result in a checkerboard free and satisfactory design solution without grey regions. [less ▲]

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See detailL'image du mois. Hématome hépatique après une réanimation cardio-pulmonaire
Delanaye, Pierre ULg; De Fooz, Geoffroy; NCHIMI LONGANG, Alain ULg et al

in Revue Médicale de Liège (2003), 58(7-8, Jul-Aug), 463-464

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See detailMarine mammals from the southern North Sea: feeding ecology data from delta C-13 and delta N-15 measurements
Das, Krishna ULg; Lepoint, Gilles ULg; Leroy, Yann et al

in Marine Ecology. Progress Series (2003), 263

The harbour porpoise Phocoena phocoena, grey seal Halichoerus grypus, harbour seal Phoca vitulina and white-beaked dolphin Lagenorhynchus albirostris are regularly found stranded along southern North Sea ... [more ▼]

The harbour porpoise Phocoena phocoena, grey seal Halichoerus grypus, harbour seal Phoca vitulina and white-beaked dolphin Lagenorhynchus albirostris are regularly found stranded along southern North Sea coasts. Occasionally, offshore species such as the fin whale Balaenoptera physalus, the white-sided dolphin L. acutus and the sperm whale Physeter macrocephalus are also found stranded. In order to trace their diet, we measured delta(13)C and delta(15)N in their muscles as well as in 49 invertebrate and fish species collected from the southern North Sea. The delta(15)N data indicate that the harbour seal, grey seal and white-beaked dolphin occupy the highest trophic position, along with ichtyophageous fishes such as the cod Gadus morhua (mean muscle values of 18.7, 17.9, 18.8 and 19.2parts per thousand respectively). The harbour porpoise occupies a slightly lower trophic position (mean delta(15)N value of 16.2parts per thousand), reflecting a higher amount of zooplanktivorous fishes in its diet (mean delta(15)N of 14.7parts per thousand); 2 suckling harbour porpoises displayed a significant delta(15)N enrichment of 2.2parts per thousand compared to adult females. Adult females are delta(15)N-enriched compared to adult male harbour porpoises. Fin whales, sperm whales and white-sided dolphins are C-13-depleted compared to southern North Sea particulate organic matter and species, suggesting that despite regular sightings, they do not feed within the southern North Sea area. [less ▲]

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See detailMagnetotransport study of MgB2 superconductor
Mucha, Jan ULg; Pekala, Marek; Szydlowska, Jadwiga et al

in Superconductor Science and Technology (2003), 16(10), 1167-1172

Precise magnetotransport studies of heat and charge carriers in polycrystalline MgB2 show that magnetic fields up to 8 T remarkably influence electrical resistivity, thermoelectric power and thermal ... [more ▼]

Precise magnetotransport studies of heat and charge carriers in polycrystalline MgB2 show that magnetic fields up to 8 T remarkably influence electrical resistivity, thermoelectric power and thermal conductivity. The superconducting transition temperature shifts from 39 K to 19 K at 8 T as observed on electric signals. The temperature transition width is weakly broadened. Electron and phonon contributions to the thermal conductivity are separated and discussed. The Debye temperature calculated from a phonon drag thermoelectric power component is inconsistent with values derived through other effects. [less ▲]

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See detailExperimental comparison of cavity sealing ability of five dental adhesive systems after thermocycling
Cao, L.; Geerts, Sabine ULg; Gueders, Audrey ULg et al

in Journal of Adhesive Dentistry (2003), 5(2, Summer), 139-144

Purpose: To evaluate the cavity sealing obtained after thermocycling with five adhesive systems in which one all-in-one adhesive was compared to three one-bottle adhesives, and to observe the effect of a ... [more ▼]

Purpose: To evaluate the cavity sealing obtained after thermocycling with five adhesive systems in which one all-in-one adhesive was compared to three one-bottle adhesives, and to observe the effect of a low-charged resin layer added to a one-bottle adhesive. Materials and Methods: Twenty-five recently extracted teeth were randomly allocated to five experimental adhesive systems (n = 5 each): Optibond Solo (OS), Scotchbond 1 (SB1), PQ 1, Prompt-L-Pop (PLP), SB1+Revolution (R). On each tooth, two rectangular cavities at the cementoenamel junction were filled with a microhybrid composite (Z100) and the tested adhesives. Teeth were thermocycled and stained with AgNO3 + vitamin C. Leakage was evaluated on a 6-point (0-5) severity scale and the highest score was selected for each restoration. Results were treated by ordinal logistic regression and considered to be significant at p < 0.05. Results: No significant difference was found between leakage values for enamel and dentin interfaces. Leakage scores never exceeded 2 for OS, SB1 and SB1+R, while they reached a maximum of 5 in 20% of PLP cases. OS was significantly better than the other adhesive systems, which were statistically equivalent. The addition of a flowable composite layer on SB1 did not yield a significant difference, but tended to give better results mainly at the dentin interface. Conclusion: The all-in-one adhesive PLP because of quite variable results, seems less reliable than the one-bottle adhesives, of which OS provides significantly the best results. Addition of a flowable composite on SB1 appears to yield slightly better results. [less ▲]

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See detailFaire mentir les prédictions en 1ère candidature : comment ? Avec quel résultat ? L'opération RESSAC (Résultats d'Epreuves Standardisées au Service de l'Apprentissage en Candis)
Leclercq, Dieudonné ULg; Dupont, Chantal ULg; Detroz, Pascal ULg et al

in L'école, dans quel(s) sens ? Actes du 2e congrès des chercheurs en éducation, Louvain-la-Neuve, 12-13 mars 2002 (2003)

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See detailFormer des étudiants de première candidature universitaire à des compétences transversales : lesquelles et comment ?
Leclercq, Dieudonné ULg

in L'école, dans quel(s) sens ? Actes du 2e congrès des chercheurs en éducation, Louvain-la-Neuve, 12-13 mars 2002 (2003)

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See detailHow ergodic is the fragmentation of the pyridine cation? A maximum entropy analysis
Gridelet, E.; Locht, Robert ULg; Lorquet, Andrée ULg et al

in International Journal of Mass Spectrometry (2003), 228(2-3), 389-402

The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the ... [more ▼]

The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the reaction threshold. This extends our previous study limited to the metastable domain [Int. J. Mass Spectrom. Ion Process. 185/186/187 (1999) 155]. Retarding potential curves resulting from dissociative photoionization using the He(I), Ne(I), and Ar(II) resonance lines have been analyzed by the maximum entropy method. The comparison between the experimentally measured curves and those calculated for the prior (i.e., most statistical) situation reveals the existence of dynamical constraints that prevent phase space from being fully explored. The "ergodicity index" F(E) that measures the efficiency of phase space sampling as a function of the internal energy E of the molecular ion is found to decrease steadily as a function of E and to level off at a value of about 50% when E greater than or equal to 2.5 eV At these high internal energies where phase space exploration no longer decreases, spontaneous intramolecular vibrational energy redistribution (i.e., resulting from the anharmonicity of the molecular vibrations) is thought to contribute to internal energy randomization to a limited extent only. When the lifetime is short, phase space exploration is believed to result instead from the relaxation of the electronic energy via a cascade of non-radiative transitions, which leads to a great diversity of initial conditions, and thus, contributes to statisticity. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailIterating transducers in the large
Boigelot, Bernard ULg; Legay, A.; Wolper, Pierre ULg

in Lecture Notes in Computer Science (2003), 2725

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the reachable set of states of a system ... [more ▼]

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the reachable set of states of a system requires acceleration techniques that can finitely compute the effect of an unbounded number of transitions. Among the acceleration techniques that have been proposed, one finds both specific and generic techniques. Specific techniques exploit the particular type of system being analyzed, e.g. a system manipulating queues or integers, whereas generic techniques only assume that the transition relation is represented by a finite-state transducer, which has to be iterated. In this paper, we investigate the possibility of using generic techniques in cases where only specific techniques have been exploited so far. Finding that existing generic techniques are often not applicable in cases easily handled by specific techniques, we have developed a new approach to iterating transducers. This new approach builds on earlier work, but exploits a number of new conceptual and algorithmic ideas, often induced with the help of experiments, that give it a broad scope, as well as good performance. [less ▲]

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See detailLes feedbacks des check-up Mohican aux étudiants et aux enseignants
Leclercq, Dieudonné ULg; Gilles, Jean-Luc ULg; Pirson, Marc ULg et al

in Leclercq, Dieudonné (Ed.) Diagnostic cognitif et métacognitif au seuil de l'université : le projet Mohican menée par les 9 universités de la Communauté française Wallonie-Bruxelles (2003)

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See detailLiens entre caractéristiques de départ (dont les résultats aux check-up) et les réussites en première candidature
Detroz, Pascal ULg; Leclercq, Dieudonné ULg

in Leclercq, Dieudonné (Ed.) Diagnostic cognitif et métacognitif au seuil de l'université : le prjet MOHICAN mené par les 9 universités de la Communauté française Wallonie Bruxelles (2003)

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See detailL'immersion linguistique dans l'enseignement fondamental en Communauté française de Belgique
Blondin, Christiane ULg

in Journal de l'Immersion (2003), 25(2), 19-31

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See detailL'information des feedbacks pour les professeurs : l'opération VOCA profs à l'ULg : estimation par les professeurs des résultats des étudiants au check-up de vocabulaire
Leclercq, Dieudonné ULg; Gilles, Jean-Luc ULg; Dupont, Chantal ULg

in Leclercq, Dieudonné (Ed.) Diagnostic cognitif et métacognitif au seuil de l'université : le projet Mohican menée par les 9 universités de la Communauté française Wallonie-Bruxelles (2003)

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See detailL'intérêt de la cystatine C dans l'évaluation de la fonction rénale
Delanaye, Pierre ULg; Chapelle, Jean-Paul ULg; Gielen, Jacques et al

in Nephrologie (2003), 24(8), 457-68

Glomerular filtration rate (GFR) is the best indicator of renal function. GFR is usually estimated by serum creatinine or the creatinine clearance calculated on urine collected over 24 hours or with the ... [more ▼]

Glomerular filtration rate (GFR) is the best indicator of renal function. GFR is usually estimated by serum creatinine or the creatinine clearance calculated on urine collected over 24 hours or with the Cockcroft formula. These methods are however limited. Serum creatinine has a very poor sensitivity and urine collection is difficult. Cystatin C is a protease inhibitor produced in a constant manner by nucleated cells. This molecule is freely filtrated by the glomerule and quite completely catabolized in the proximal tubules. Its plasmatic concentration might thus be used to estimate GFR. Presently available data allow to conclude that plasmatic cystatin C is at least as good as serum creatinine to estimate GFR. It is less sensible to changes in body mass. Its determination appears more sensitive to detect early mild changes in GFR. Reference values are presently available for the different methods of determination. Cystatin C plasma level determination is more expensive than routine creatinine plasma determination. In the absence of very significant advantages, this might explain its limited use in daily clinical practice. [less ▲]

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See detailMagneto-transport study of nb-doped Bi/Pb2223 superconductor
Pekala, Marek; Mucha, Jan ULg; Cloots, Rudi ULg et al

in Physica C: Superconductivity (2003), 387(1-2), 191-197

The magneto-transport properties of Bi1.5Pb0.4Nb0.1Sr2Ca2Cu3O10-x polycrystalline, superconducting ceramic are reported. The material was found to be chemically homogeneous and partially textured. The ... [more ▼]

The magneto-transport properties of Bi1.5Pb0.4Nb0.1Sr2Ca2Cu3O10-x polycrystalline, superconducting ceramic are reported. The material was found to be chemically homogeneous and partially textured. The mixed state properties were investigated by measuring the electrical resistivity, longitudinal and transverse (Nernst effect) thermoelectric power, and thermal conductivity. The magnetization and AC susceptibility measurements were also performed. The variation of these characteristics for magnetic fields up to 5 T are discussed and compared to those of the zero field case. The transport entropy and thermal Hall angle are extracted and quantitatively compared to previously reported data of closely related systems. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMicroscopic spectral density in random matrix models for chiral and diquark condensation
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review D (2003), 67(8), 085016

We examine random matrix models of QCD which are capable of supporting both chiral and diquark condensation. A numerical study of the spectral densities near zero virtuality shows that the introduction of ... [more ▼]

We examine random matrix models of QCD which are capable of supporting both chiral and diquark condensation. A numerical study of the spectral densities near zero virtuality shows that the introduction of color in the interactions does not alter the one-body results imposed by chiral symmetry. A model with three colors has the spectral density predicted for the chiral ensemble with a Dyson index beta=2; a pseudoreal model with two colors exhibits the spectral density of the chiral ensemble with beta=1. [less ▲]

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See detailMMP-2 and MMP-9 synergize in promoting choroidal neovascularization
Lambert, Vincent ULg; Wielockx, B.; Munaut, Carine ULg et al

in FASEB Journal (2003), 17(15), 2290-2292

Matrix metalloproteinase 2 (MMP-2) and MMP-9 are increased in human choroidal neovascularization (CNV) occurring during the exudative most aggressive form of age-related macular degeneration (AMD), but ... [more ▼]

Matrix metalloproteinase 2 (MMP-2) and MMP-9 are increased in human choroidal neovascularization (CNV) occurring during the exudative most aggressive form of age-related macular degeneration (AMD), but their precise role and potential interactions remain unclear. To address the question of MMP-2 and MMP-9 functions, mice deficient in the expression of MMP-2 (MMP-2 KO), MMP-9 (MMP-9 KO), and both MMP-2 and MMP-9 (MMP-2,9 KO) with their corresponding wild-type mice (WT) underwent CNV induction by laser-induced rupture of the Bruch's membrane. Both the incidence and the severity of CNV were strongly attenuated in double deficient compared with single gene deficient mice or corresponding WT controls. The reduced neovascularization was accompanied by fibrinogen/fibrin accumulation. Furthermore, overexpression of the endogenous MMP inhibitors TIMP-1 or TIMP-2 (delivered by adenoviral vectors) in WT mice or daily injection of a synthetic and gelatinase selective MMP inhibitor (Ro 26-2853) significantly decreased the pathological reaction. These findings suggest that MMP-2 and MMP-9 may cooperate in the development of AMD and that their selective inhibition represents an alternative strategy for the treatment of choroidal neovascularization. [less ▲]

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See detailMultiscale texture characterization of wastewater sludges dried in a convective rig
Léonard, Angélique ULg; Blacher, Silvia ULg; Pirard, René ULg et al

in Drying Technology (2003), 21(8), 1507-1526

Secondary sludges from two different wastewater treatment plants are conditioned and dewatered in the same way before drying in a lab-scale convective rig at the same operating conditions. Several ... [more ▼]

Secondary sludges from two different wastewater treatment plants are conditioned and dewatered in the same way before drying in a lab-scale convective rig at the same operating conditions. Several techniques are used to characterize the texture of the dried materials over a wide range of scales from nm up to mm. Texture and porosity of the dried products are studied by SEM imaging, nitrogen absorption isotherms (0.5 < d(p) < 50 nm), mercury porosimetry (7.5 nm < d(p) < 150 mum) and X-ray microtomography (spatial resolution= 41 mum). The image analysis of cross-sections reconstructed by microtomography also allows following shrinkage and textural evolution during drying. [less ▲]

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