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See detailA polarity reversal in the large-scale magnetic field of the rapidly rotating sun HD 190771
Petit, Pascal; Dintrans, Boris; Morgenthaler, Audrey et al

in Astronomy and Astrophysics (2009), 508

Aims. We investigate the long-term evolution of the large-scale photospheric magnetic field geometry of the solar-type star HD 190771. With fundamental parameters very close to those of the Sun except for ... [more ▼]

Aims. We investigate the long-term evolution of the large-scale photospheric magnetic field geometry of the solar-type star HD 190771. With fundamental parameters very close to those of the Sun except for a shorter rotation period of 8.8 d, HD 190771 provides us with a first insight into the specific impact of the rotation rate in the dynamo generation of magnetic fields in 1 M_sun stars. Methods: We use circularly polarized, high-resolution spectra obtained with the NARVAL spectropolarimeter (Observatoire du Pic du Midi, France) and compute cross-correlation line profiles with high signal-to-noise ratio to detect polarized Zeeman signatures. From three phase-resolved data sets collected during the summers of 2007, 2008, and 2009, we model the large-scale photospheric magnetic field of the star by means of Zeeman-Doppler imaging and follow its temporal evolution. Results: The comparison of the magnetic maps shows that a polarity reversal of the axisymmetric component of the large-scale magnetic field occurred between 2007 and 2008, this evolution being observed in both the poloidal and toroidal magnetic components. Between 2008 and 2009, another type of global evolution occured, characterized by a sharp decrease of the fraction of magnetic energy stored in the toroidal component. These changes were not accompanied by significant evolution in the total photospheric magnetic energy. Using our spectra to perform radial velocity measurements, we also detect a very low-mass stellar companion to HD 190771. [less ▲]

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See detailRapport sur les essais de traçage dans le bassin du Néblon réalisés en août 2010
Brouyère, Serge ULg; Gesels, Julie ULg; Thomas, Laurent et al

Report (2009)

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See detailInsect prenyltransferases: Characterization, roles in insect biology, and evolution
Cusson, Michel; Vandermoten, Sophie ULg; Barbar, Aline et al

Conference (2009, December)

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See detailFred D'Aguiar visits the English Department
Tunca, Daria ULg

in Le Journal de BabeLg 28 (2009)

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See detailControlled Synthesis of AB2 amphiphilic triarm star-shaped block copolymers by ring-opening polymerization
Petrova, Svetla; Riva, Raphaël ULg; Jérôme, Christine ULg et al

in European Polymer Journal (2009), 45(12), 3442-3450

This paper describes the synthesis of a novel amphiphilic AB2 triarm star-shaped copolymer with A = non-toxic and biocompatible hydrophilic poly(ethylene oxide) (PEO) and B = biodegradable and hydrophobic ... [more ▼]

This paper describes the synthesis of a novel amphiphilic AB2 triarm star-shaped copolymer with A = non-toxic and biocompatible hydrophilic poly(ethylene oxide) (PEO) and B = biodegradable and hydrophobic poly(ε-caprolactone) (PCL). A series of AB2 triarm star-shaped copolymers with different molecular weights for the PCL block were successfully synthesized by a three-step procedure. α-methoxy-ω-epoxy-poly(ethylene oxide) (PEO-epoxide) was first synthesized by the nucleophilic substitution of α-methoxy-ω-hydroxy-poly(ethylene oxide) (MPEO) on epichlorohydrin. In a second step, the α-methoxy-ω,ω’-dihydroxy-poly(ethylene oxide) (PEO(OH)2) macroinitiator was prepared by the selective hydrolysis of the ω-epoxy end-group of the PEO-epoxide chain. Finally, PEO(OH)2 was used as a macroinitiator for the ring-opening polymerization (ROP) of ε-caprolactone (εCL) catalyzed by tin octoaote (Sn(Oct)2). PEO-epoxide, PEO(OH)2 and the AB2 triarm star-shaped copolymers were assessed by 1H NMR spectroscopy, size exclusion chromatography (SEC) and MALDI-TOF. The behavior of the AB2 triarm star-shaped copolymer in aqueous solution was studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). [less ▲]

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See detailBehaviour of single sided composite joints at room temperature and in case of fire after an earthquake
Demonceau, Jean-François ULg; Hanus, François ULg; Jaspart, Jean-Pierre ULg et al

in International Journal of Steel Structures (2009), 9(4), 329-342

In 2003, a European research program entitled “PRECIOUS - Prefabricated composite beam-to-concrete filled tube or partially reinforced-concrete-encased column connections for severe seismic and fire ... [more ▼]

In 2003, a European research program entitled “PRECIOUS - Prefabricated composite beam-to-concrete filled tube or partially reinforced-concrete-encased column connections for severe seismic and fire loadings” and funded by the Research Fund for Coal and Steel (RFCS) was initiated for three years (Bursi et al, 2008). The objective of this project was to develop fundamental data, design guidelines and prequalification tools for two types of composite beam-to-column joints able to ensure a suitable behaviour during an earthquake and its eventual subsequent fire. At the University of Liege, as part of this project, analytical and numerical investigations were conducted mainly on single-sided beam-to-column composite joints at room and at elevated temperatures. The present paper summarizes the activities developed within this project and presents the main achievements. [less ▲]

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See detailAnalysis of regional wall motion during contrast-enhanced dobutamine stress echocardiography: effect of contrast imaging settings.
Cosyns, Bernard; Van Camp, Guy; Droogmans, Sophie et al

in European Journal of Echocardiography (2009), 10(8), 956-60

Aims: Myocardial contrast perfusion echocardiography (MCE) allows simultaneous assessment of perfusion and function. However, low frame rate during MCE may reduce the viewer's ability to discern ... [more ▼]

Aims: Myocardial contrast perfusion echocardiography (MCE) allows simultaneous assessment of perfusion and function. However, low frame rate during MCE may reduce the viewer's ability to discern contractile dysfunction. This study sought to compare MCE and left ventricular opacification (LVO) settings with regard to wall motion abnormalities (WMA) at rest and during dobutamine stress echocardiography (DSE). Methods and results: In 50 patients scheduled for coronary angiography and with poor baseline image quality, MCE and LVO were performed during DSE. Regional wall motion was assessed and inter-observer agreement was determined for each imaging modality. The endocardial border score index was similar for both modalities. The wall motion score index (WMSCI) at peak stress using MCE was well correlated with WMSCI obtained with LVO (r2 = 0.9, P < 0.001). However, WMSCI at peak stress was underestimated by MCE (1.66 ± 0.58 with DSE-LVO vs. 1.535 ± 0.50 with DSE-MCE; P < 0.001). Inter-observer agreement on the presence of WMA was 0.65 for MCE and 0.67 for LVO at peak stress. Conclusion: Myocardial contrast perfusion echocardiography provides equal endocardial border delineation compared with LVO modality. Although the inter-observer agreement is slightly higher with LVO compared with MCE, it is not significantly different with MCE at peak stress. Despite the similar improvement in endocardial border delineation, LVO settings allow the detection of more WMA than MCE at peak stress, leading to a significantly higher accuracy for the detection of ischaemia in patients suspected of coronary artery disease when only wall motion is taken into account. [less ▲]

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See detailPre-flight calibration of LYRA, the solar VUV radiometer on board PROBA2
Benmoussa, Ali; Dammasch, Ingolf; Hochedez, Jean-François et al

in Astronomy and Astrophysics (2009), 508(2), 1085-1094

Aims. LYRA, the Large Yield Radiometer, is a vacuum ultraviolet (VUV) solar radiometer, planned to be launched in November 2009 on the European Space Agency PROBA2, the Project for On-Board Autonomy ... [more ▼]

Aims. LYRA, the Large Yield Radiometer, is a vacuum ultraviolet (VUV) solar radiometer, planned to be launched in November 2009 on the European Space Agency PROBA2, the Project for On-Board Autonomy spacecraft. Methods: The instrument was radiometrically calibrated in the radiometry laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the Berlin Electron Storage ring for SYnchroton radiation (BESSY II). The calibration was done using monochromatized synchrotron radiation at PTB's VUV and soft X-ray radiometry beamlines using reference detectors calibrated with the help of an electrical substitution radiometer as the primary detector standard.<BR /> Results: A total relative uncertainty of the radiometric calibration of the LYRA instrument between 1 and 11 was achieved. LYRA will provide irradiance data of the Sun in four UV passbands and with high temporal resolution down to 10 ms. The present state of the LYRA pre-flight calibration is presented as well as the expected instrument performance. [less ▲]

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See detailFinance et valeur(s): Liber Amicorum et Discipulorum
Corhay, Albert ULg; Hübner, Georges ULg; Muller, Aline ULg

Book published by Les Editions de l'Université de Liège (2009)

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See detailA PDE viewpoint on basic properties of coordination algorithms with symmetries
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg

in Proceedings of the 48th IEEE Conference on Decision and Control (2009, December)

Several recent control applications consider the coordination of subsystems through local interaction. Often the interaction has a symmetry in state space, e.g. invariance with respect to a uniform ... [more ▼]

Several recent control applications consider the coordination of subsystems through local interaction. Often the interaction has a symmetry in state space, e.g. invariance with respect to a uniform translation of all subsystem values. The present paper shows that in presence of such symmetry, fundamental properties can be highlighted by viewing the distributed system as the discrete approximation of a partial differential equation. An important fact is that the symmetry on the state space differs from the popular spatial invariance property, which is not necessary for the present results. The relevance of the viewpoint is illustrated on two examples: (i) ill-conditioning of interaction matrices in coordination/consensus problems and (ii) the string instability issue. [less ▲]

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See detailUnemployment and retirement in a model with age-specific heterogeneity
Lefebvre, Mathieu ULg

Conference (2009, December)

This paper presents a model where young and old workers compete for one type of jobs in the presence of retirement opportunity. Within this framework, we show that increased retirement opportunities (such ... [more ▼]

This paper presents a model where young and old workers compete for one type of jobs in the presence of retirement opportunity. Within this framework, we show that increased retirement opportunities (such as early retirement) has most of the time a depressing impact on the unemployment rate. Indeed the number of vacancies posted by fi rms is influenced by the probability that an old worker is going into retirement. We show that the degree to which younger workers are influenced by retirement of older workers depends on the relative productivity of young and older workers. It is only when older workers are much more productive than young workers that retirement may bene fit to unemployment. [less ▲]

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See detailPulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface
Lousberg, Grégory ULg; Fagnard, Jean-François ULg; Haanappel, Evert et al

in Superconductor Science and Technology (2009), (22), 125026

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse ... [more ▼]

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane as on the surface. This ratio is confirmed by modelling. [less ▲]

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See detailA deformation based blank design method for formed parts
Hammami, Walid ULg; Padmanabhan, R.; Oliveira, M. C. et al

in International Journal Mechanics and Materials in Design (2009), 5(4), 303-314

Blank design is an important task in sheet metal forming process optimization. The initial blank shape has direct effect on the part quality. This paper presents a deformation based blank design approach ... [more ▼]

Blank design is an important task in sheet metal forming process optimization. The initial blank shape has direct effect on the part quality. This paper presents a deformation based blank design approach to determine the initial blank shape for a formed part. The blank design approach is integrated separately into ABAQUS, and DD3IMP, a research purpose in-house FEA code, to demonstrate its compatibility with any FEA code. The algorithm uses FE results to optimize the blank shape for a part. Deep drawing simulation of a rectangular cup geometry was carried out with an initial blank shape determined empirically. The blank shape was iteratively modified, based on the deformation history, until an optimal blank shape for the part is achieved. The optimal blank shapes predicted by the algorithm using both FEA softwares were similar. Marginal differences in the shape error indicate that the deformation history based push/pull technique can effectively determine an optimal blank shape for a part with any FEA software. For the shape error selected, both procedures estimate the optimal blank shape for the part within five iterations. [less ▲]

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See detailDevelopment of an in vitro endotoxin test for monoolein-water liquid crystalline gel for use as an implant
Ouédraogo, Moustapha; Semdé, Rasmané; Somé, Issa T. et al

in Tropical Journal of Pharmaceutical Research [=TJPR] (2009), 8(6), 501-508

Purpose : Drugs that are administered by parenteral route must be apyrogenic. The aim of this study was to develop an in vitro endotoxin test for liquid crytalline gels for use as implants, using a ... [more ▼]

Purpose : Drugs that are administered by parenteral route must be apyrogenic. The aim of this study was to develop an in vitro endotoxin test for liquid crytalline gels for use as implants, using a monoolein-water liquid crystalline gel as a model. Methods : The gel-clot technique was used. The gel was dissolved first in isopropyl myristate, and the endotoxins were extracted with water for bacterial endotoxin test. Tests for the labelled lysate sensitivity and interfering factors were performed to validate the developed method. The limit of detection of endotoxin in the gel was also determined. Results : The labelled lysate sensitivity was confirmed. It was not influenced by the presence of extracts from the gels. Endotoxins in the contaminated test gels were completely extracted. Endotoxin concentration in the tested gels was below the calculated threshold endotoxin level. Conclusion : A method to perform in vitro endotoxins test of liquid crystalline gels was successfully developed and validated. Application of the technique to gels currently being developed in our laboratories indicate that the gels were apyrogenic. [less ▲]

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See detailCompte rendu de l'ouvrage de J.-M. Klinkenberg, Petites mythologies belges (2e édition)
Provenzano, François ULg

in Nouveaux Actes Sémiotiques (2009)

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See detailProper Orthogonal Decomposition of Unsteady Aerodynamic Flows
Andrianne, Thomas ULg; Ligot, Jerome; Dimitriadis, Grigorios ULg

Report (2009)

This work constitutes the final report for a project funded by the Fonds de la Recherche Scientifique. The objective of the project was to acquire and install Par- tical Image Velocimetry (PIV) hardware ... [more ▼]

This work constitutes the final report for a project funded by the Fonds de la Recherche Scientifique. The objective of the project was to acquire and install Par- tical Image Velocimetry (PIV) hardware in the University of Liege Wind Tunnel facility in order to carry out the Proper Orthogonal Decomposition (POD) of un- steady aerodynamic flows. The characteristics and installation of the PIV system are described in the present report. Furthermore, the application of POD analysis to three different visualized flow cases is detailed. The flow cases were: flow be- hind a circular cylinder and separated flow over a rectangular wing. In all cases, emphasis was given to the combination of unsteadiness caused by both boundary layer separation and movement of the wind tunnel model. It is shown that the de- composition of flowfields that combine these two sources of unsteadiness is possible and informative. [less ▲]

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See detailLa 11β-hydroxystéroïde déshydrogénase de type 1 – 2e partie Inhibition sélective pour traiter les anomalies métaboliques associées à l’obésité
Iovino, A.; Scheen, André ULg

in Médecine des Maladies Métaboliques (2009), 3(6), 595-600

La 11β-hydroxystéroïde déshydrogénase de type 1 (11HSD1), qui convertit la cortisone (inactive) en cortisol (actif) dans les tissus cibles, est surexprimée dans certains tissus en présence d’une obésité ... [more ▼]

La 11β-hydroxystéroïde déshydrogénase de type 1 (11HSD1), qui convertit la cortisone (inactive) en cortisol (actif) dans les tissus cibles, est surexprimée dans certains tissus en présence d’une obésité, surtout abdominale, et pourrait jouer un rôle dans les anomalies métaboliques associées. Des inhibiteurs non sélectifs de la 11HSD1 ont déjà été testés chez l’homme et se sont révélés peu efficaces. Le développement de nouveaux inhibiteurs, plus puissants et plus sélectifs, est en cours. Des résultats préliminaires obtenus avec divers inhibiteurs sont prometteurs, avec une diminution de l’insulinorésistance, une amélioration de la tolérance au glucose ou du contrôle glycémique et une correction de certaines anomalies liées au syndrome métabolique. Si ces résultats se confirment, les inhibiteurs sélectifs de la 11HSD1 pourraient représenter à l’avenir une nouvelle classe pharmacologique d’antidiabétiques oraux. Cet article donne au lecteur un aperçu des différentes étapes de réflexion et d’expérimentations humaines qui ont mené au développement d’inhibiteurs de la 11HSD1 à visée thérapeutique. [less ▲]

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