Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
See detailLa diffusion des idées nouvelles dans la principauté de Liège au XVIIIe siècle
Droixhe, Daniel ULg

in Bulletin du Crédit communal (1981), 138

Detailed reference viewed: 23 (4 ULg)
See detailLa diffusion du livre italien en langue vulgaire dans les pays wallons de 1500 à 1630
Adam, Renaud ULg; Bingen, Nicole

Scientific conference (2013, November 15)

Detailed reference viewed: 19 (3 ULg)
See detailDiffusion du WOCCQ : le temps de l’évaluation
Peters, Stéphanie ULg; Bracci, Elisa; Hansez, Isabelle ULg

Conference given outside the academic context (2005)

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailDiffusion et réception des théories du mouvement moderne à Liège de 1928 à 1939
Charlier, Sébastien ULg

in Bulletin d'Information de l'Association Belge d'Histoire Contemporaine = Mededelingenblad van de Belgische Vereniging voor Nieuwste Geschiedenis (2011), XXXIII(4), 23-26

Detailed reference viewed: 49 (8 ULg)
See detailDiffusion of copper in the animal kingdom
Fredericq, Léon ULg

in Nature (1880), XXXI

Detailed reference viewed: 6 (2 ULg)
Full Text
Peer Reviewed
See detailDiffusion Tensor Imaging to Predict Long-term Outcome after Cardiac Arrest. A Bicentric Pilot Study
Luyt, Charles-Edouard; Galanaud, Damien; Perlbarg, Vincent et al

in Anesthesiology (2012), 117(6), 1311-1321

Detailed reference viewed: 13 (0 ULg)
Full Text
Peer Reviewed
See detailDiffusion Tensor Imaging to Predict Long-term Outcome after Cardiac Arrest: A Bicentric Pilot Study.
Luyt, Charles-Edouard; Galanaud, Damien; Perlbarg, Vincent et al

in Anesthesiology (2012), 117(6), 1311-1321

BACKGROUND:: Prognostication in comatose survivors of cardiac arrest is a major clinical challenge. The authors' objective was to determine whether an assessment with diffusion tensor imaging, a brain ... [more ▼]

BACKGROUND:: Prognostication in comatose survivors of cardiac arrest is a major clinical challenge. The authors' objective was to determine whether an assessment with diffusion tensor imaging, a brain magnetic resonance imaging sequence, increases the accuracy of 1 yr functional outcome prediction in cardiac arrest survivors. METHODS:: Prospective, observational study in two intensive care units. Fifty-seven comatose survivors of cardiac arrest underwent brain magnetic resonance imaging. Fractional anisotropy (FA), a diffusion tensor imaging value, was measured in predefined white matter regions, and apparent diffusion coefficient was assessed in predefined grey matter regions. Prediction of unfavorable outcome at 1 yr was compared using four prognostic models: FA global, FA selected, apparent diffusion coefficient, and clinical classifiers. RESULTS:: Of the 57 patients included in the study, 49 had an unfavorable outcome at 12 months. Areas under the receiver operating characteristic curve (95% CI) to predict unfavorable outcome for the FA global, FA selected, clinical, and apparent diffusion coefficient models were 0.92 (0.82-0.98), 0.96 (0.87-0.99), 0.78 (0.65-0.88), and 0.86 (0.74-0.94), respectively. The FA selected model had the best overall accuracy for predicting outcome, with a score above 0.44 having 94% (95% CI, 83-99%) sensitivity and 100% (95% CI, 63-100%) specificity for the prediction of unfavorable outcome. CONCLUSION:: Quantitative diffusion tensor imaging indicates that white matter damage is widespread after cardiac arrest. A prognostic model based on FA values in selected white matter tracts seems to predict accurately 1 yr functional outcome. These preliminary results need to be confirmed in a larger population. [less ▲]

Detailed reference viewed: 16 (0 ULg)
Full Text
Peer Reviewed
See detailDiffusion-based models for predicting sound fields in rooms with mixed specular and diffuse reflection
Foy, Cédric; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2007, September)

A diffusion model, based on the numerical solution of a diffusion equation, was developed in the past to give accurate predictions of the sound-pressure level and of the sound decay at any location in a ... [more ▼]

A diffusion model, based on the numerical solution of a diffusion equation, was developed in the past to give accurate predictions of the sound-pressure level and of the sound decay at any location in a single enclosure or in coupled rooms. However, this model is limited to rooms with diffusely reflecting walls. In this study, two methods are presented to extend this model to rooms with mixed specular and diffuse reflections, defined by the classical room-acoustics scattering coefficient. The first method models the reverberant field by using a modified diffusion process, with an empirical diffusion constant departing from the theoretical one based on the mean free path. The set of these coefficients, which depend on the scattering coefficient, has been found empirically to fit the results given by a ray-tracing program. The second method is a hybrid approach. The reverberant sound field due to the diffuse reflections is first obtained with the original diffusion model. Then the sound field due to the specular reflections is modelled with an image-source model. The results given by the two approaches are compared to experimental data obtained for several types of rooms (a classroom, an office and some long rooms). [less ▲]

Detailed reference viewed: 35 (3 ULg)
Full Text
See detailDiffusive equilibrium elements
Fraeijs de Veubeke, Baudouin ULg

Scientific conference (1973, July)

Equiliobrium models are characterized by an internal stress field in equilibrium and surface tractions that should obey the diffusivity requirement of reciprocity with adjacent elements at the interfaces ... [more ▼]

Equiliobrium models are characterized by an internal stress field in equilibrium and surface tractions that should obey the diffusivity requirement of reciprocity with adjacent elements at the interfaces. Thepaper discusses the construction of stiffness matices for such elements and the difficulties associated with the presence of mechanisms. The use of first order or second order stress functions is presented together with the possibility of solving the final equations by the force method through a direct flexibility method. Three methods are presented for getting rid of thre machanisms: the classical superelement technique, a method based on the discretization of rotational equilibrium and quasi-diffusivity. [less ▲]

Detailed reference viewed: 27 (6 ULg)
Full Text
Peer Reviewed
See detailDiffusive methane emissions to the atmosphere from Lake Kivu (Eastern Africa)
Borges, Alberto ULg; Abril, Gwenaël; Delille, Bruno ULg et al

in Journal of Geophysical Research. Biogeosciences (2011), 116(G03032),

We report a data-set of methane (CH4) concentrations in the surface waters of Lake Kivu obtained during four cruises (March 2007, September 2007, June 2008, April 2009) covering the two main seasons ... [more ▼]

We report a data-set of methane (CH4) concentrations in the surface waters of Lake Kivu obtained during four cruises (March 2007, September 2007, June 2008, April 2009) covering the two main seasons, rainy (October to May) and dry (June to September). Spatial gradients of CH4 concentrations were modest in the surface waters of the main basin. In Kabuno Bay (a small sub-basin), CH4 concentrations in surface waters were significantly higher than in the main basin. Seasonal variations of CH4 in the main basin were strongly driven by deepening of the mixolimnion and mixing of surface waters with deeper waters rich in CH4. On an annual basis, both Kabuno Bay and the main basin of Lake Kivu were over-saturated in CH4 with respect to atmospheric equilibrium (7330% and 2510%, respectively), and emitted CH4 to the atmosphere (39 mmol m-2 yr-1 and 13 mmol m-2 yr-1, respectively). The source of CH4 to atmosphere was two orders of magnitude lower than the CH4 upward flux. The source of CH4 to the atmosphere from Lake Kivu corresponded to ~60% of the terrestrial sink of atmospheric CH4 over the lake’s catchment. A global cross-system comparison of CH4 in surface waters of lakes shows that both Kabuno Bay and the main basin are at the lower end of values in lakes globally, despite the huge amounts of CH4 in the deeper layers of the lake. This is related to the strongly meromictic nature of the lake that promotes an intense removal of CH4 by bacterial oxidation. [less ▲]

Detailed reference viewed: 55 (5 ULg)
Full Text
Peer Reviewed
See detailDiffusive radical entry as the rate-determining step in amphiphilic block polyelectrolyte mediated emulsion polymerization
Leemans, Luc; Jérôme, Robert ULg; Teyssié, Philippe

in Macromolecules (1998), 31(17), 5565-5571

The amphiphilic water soluble block polyelectrolytes PMMA-b-SPGMA and PMMA-b-QPDMAEMA are efficient surfactants for the radical emulsion polymerization. Negatively charged, neutral, and positively charged ... [more ▼]

The amphiphilic water soluble block polyelectrolytes PMMA-b-SPGMA and PMMA-b-QPDMAEMA are efficient surfactants for the radical emulsion polymerization. Negatively charged, neutral, and positively charged entering radicals were used in combination with polyanionically and polycationically tailored PMMA latex particles. It was shown that the rate of polymerization was very high for systems wherein the entering radical species had an electrical charge sign identical with that of the polyelectrolyte corona around the latex particle. PMMA-b-SPGMA turned out to be 4 times as efficient as compared to SDS emulsified MMA polymerization at 0.6 wt %. Systems wherein polyelectrolyte block and entering radical were of opposite sign displayed strongly reduced polymerization rates. When the polyelectrolyte barrier became thick enough, as in the case of a Mn = 26 000 PMMA-b-QPDMAEMA, no more polymerization was observed. The observed polymerization rate effects are discussed in terms of repulsion of equal charge radicals, leading to enhanced mobility and counterion mobility restriction of the radicals of opposite sign to the polyelectrolyte block. In the latter case, this slowed counterion diffusion of radicals of opposite sign leads to premature aqueous phase termination of free radicals and consequently low flux of entering radicals with low rates of polymerization. The experimental results obtained are consistent with the theoretically predicted case, where the “control by aqueous phase growth” theory for the entry of free radicals in latex particles is invalid. [less ▲]

Detailed reference viewed: 30 (1 ULg)
Full Text
See detailThe difR package, a toolbox for the identification dichotomous differential item functioning
Magis, David ULg

Conference (2011, February 25)

The purpose of this talk is to briefly introduce the R package difR to identify differential item functioning (DIF) among dichotomously scored items. The presentation is organized in three points. First ... [more ▼]

The purpose of this talk is to briefly introduce the R package difR to identify differential item functioning (DIF) among dichotomously scored items. The presentation is organized in three points. First, the general framework of DIF is outlined and the most known methods are presented succinctly. Second, the main functionalities of the difR package are described. Third, a practical application of difR is performed by a “live” analysis of a real example with several DIF methods. Future developments and objectives are discussed to conclude the talk. The difR package was jointly developed by Sébastien Béland (Université du Québec à Montréal, Canada), Francis Tuerlinckx (K. U. Leuven, Belgium) and Paul De Boeck (University of Amsterdam, The Netherlands). [less ▲]

Detailed reference viewed: 30 (5 ULg)
Full Text
Peer Reviewed
See detailDifunctional anionic initiator based on 1.3-diisopropenylbenzene. 5. Effect of polar additives and initiator seeding on the synthesis of poly(styrene-b-butadiene-b-styrene) copolymer
Yu, Y. S.; Dubois, Philippe ULg; Teyssié, Philippe et al

in Macromolecules (1997), 30(24), 7356-7362

The initiation of butadiene and styrene polymerization by a pure hydrocarbon soluble difunctional organolithium, 1,3-bis(1-lithio-1,3,3‘-trimethylbutyl)benzene, has been studied in a hydrocarbon solvent ... [more ▼]

The initiation of butadiene and styrene polymerization by a pure hydrocarbon soluble difunctional organolithium, 1,3-bis(1-lithio-1,3,3‘-trimethylbutyl)benzene, has been studied in a hydrocarbon solvent. The initiation occurs in such a way that part of the diadduct remains unreacted. When a second monomer feed along with tetrahydrofuran (THF) is added to the living chains, the residual diadduct is activated to the point where novel chains are formed. Weakly polar additives such as lithium alkoxides and aromatic ether can prevent part of the initiator from being inactive, although these additives are not effective enough to initiate the controlled synthesis of poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers. The seeding of the initiator which consists of butadiene oligomerization in the presence of anisole and tBuOLi in cyclohexane, has proved to be very efficient in providing SBS containing 85% 1,4-microstructure polybutadiene (PBD) and with high mechanical properties, e.g., ultimate tensile strength higher than 30 MPa and elongation at a break of 1000%. [less ▲]

Detailed reference viewed: 24 (4 ULg)
Full Text
Peer Reviewed
See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 2. Kinetics and mechanism of the sec-butyllithium/1,3-diisopropenylbenzne reaction
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1996), 29(5), 1753-1761

Kinetics of the addition of s-butyllithium (s-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied, and the activation energy has been found to be 17.5 kcal/mol. Addition of s-BuLi to 1,3-DIB in a ... [more ▼]

Kinetics of the addition of s-butyllithium (s-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied, and the activation energy has been found to be 17.5 kcal/mol. Addition of s-BuLi to 1,3-DIB in a 2/1 molar ratio results in an oligomer rather than the desired diadduct. This observation has to be compared to the anionic polymerization of 1,3-DIB (hydrocarbon solvent at 50 °C) which leads to a polymer bearing ca. one double bond per monomeric unit. Li-NMR analysis of the addition of s-BuLi to 1,3-DIB (2/1 molar ratio) confirms the nonequivalence of the lithium cations and shows that ca. 30% s-BuLi remains unreacted when 1,3-DIB has been completely consumed. In the early stage of the addition, the propagation rate is faster than depropagation and the average molecular weight increases. When a depropagation−propagation quasi-equilibrium is reached, the oligomer molecular weight remains constant. It finally decreases when no DIB is left, as a result of depropagation. When the s-BuLi/1,3-DIB adduct is used as an initiator for styrene polymerization in the presence of a polar solvent, such as THF, initiation by monofuntional, difunctional, trifunctional, and tetrafunctional species is observed. In an apolar solvent, however, polystyrene of a narrow molecular weight distribution and a functionality of 2 is formed. This experimental observation more likely indicates that depolymerization of the 1,3-DIB oligomers occurs upon the addition of styrene. A mechanism which accounts for this propagation−depropagation process has been proposed and experimentally supported. [less ▲]

Detailed reference viewed: 28 (3 ULg)
Full Text
Peer Reviewed
See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 4. Synthesis and modification of poly(alkyl methacrylate-b-styrene-b-butadiene-b-styrene-b-alkyl methacrylate (MSBSM) thermoplastic elastomers
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1996), 34(11), 2221-2228

MSBSM five-block copolymers where B stands for butadiene, S for styrene, and M for either methyl methacrylate (MMA) or tert-butyl methacrylate (tBMA) have been synthesized by sequential anionic ... [more ▼]

MSBSM five-block copolymers where B stands for butadiene, S for styrene, and M for either methyl methacrylate (MMA) or tert-butyl methacrylate (tBMA) have been synthesized by sequential anionic polymerization in an apolar solvent by using a difunctional anionic initiator derived from 1,3-diisopropenylbenzene. These block copolymers show improved mechanical properties and an extended service temperature compared to traditional SBS thermoplastic elastomers. Upon hydrolysis and further neutralization of the PolytBMA end-blocks, the upper glass transition temperature (Tg) of the five-block copolymers has been raised up to about 150°C. A further increase in this service temperature (up to ca. 160°C) has resulted from the blending of sPMMA-SBS-sPMMA five-block copolymers with isotactic poly(methacrylate) (iPMMA), due to the formation of a stereocomplex. The tensile properties of these modified five-block copolymers have remained essentially unchanged. [less ▲]

Detailed reference viewed: 68 (14 ULg)
Full Text
Peer Reviewed
See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 6. Synthesis of methyl methacrylate-butadiene-methyl methacrylate triblock copolymers
Yu, Y. S.; Dubois, Philippe ULg; Teyssié, Philippe et al

in Macromolecules (1997), 30(15), 4254-4261

Synthesis of PMMA−PBD−PMMA (MBM) triblock copolymers with a 1,3-diisopropenylbenzene- (DIB-) based initiator is studied. Diethyl ether, tert-butyl methyl ether, N,N,N‘,N‘-tetramethylethylenediamine (TMEDA ... [more ▼]

Synthesis of PMMA−PBD−PMMA (MBM) triblock copolymers with a 1,3-diisopropenylbenzene- (DIB-) based initiator is studied. Diethyl ether, tert-butyl methyl ether, N,N,N‘,N‘-tetramethylethylenediamine (TMEDA) and THF were found to be efficient polar additives for obtaining PMMA−PBD−PMMA triblock copolymers, but these triblock copolymers displayed a high 1,2-microstructure of the PBD block. A combination of the initiator seeding technique and weakly polar additives has allowed MBM triblock copolymers with high 1,4-microstructure of PBD to be obtained. These copolymers exhibited a definitely higher upper service temperature than conventional thermoplastic elastomers, i.e. SBS or SIS Kratons. The influence of chain microstructure, copolymer composition and block length on the mechanical properties has been studied. Short polystyrene blocks of ca. Mn 2000 have been incorporated in between the PBD central block and the PMMA outer sequences. A higher tensile strength was observed for these MBM-like triblock coplymers. Contamination by a diblock structure expectedly had a very depressive effect on the bulk properties, and the stress−strain behavior mainly depended on the PMMA content and secondarily on molecular weight. [less ▲]

Detailed reference viewed: 12 (2 ULg)
See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 7. Mechanical and thermal properties of new butadiene-based thermoplastic elastomers
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Rubber Chemistry and Technology (1997, November), 70(5), 820-838

Mechanical and thermal properties of SBS thermoplastic elastomers, in which S stands for polystyrene and B for polybutadiene, can be remarkably improved through end-capping by syndiotactic poly(methyl ... [more ▼]

Mechanical and thermal properties of SBS thermoplastic elastomers, in which S stands for polystyrene and B for polybutadiene, can be remarkably improved through end-capping by syndiotactic poly(methyl methacrylate) sequences. Furthermore, the upper service temperature of these sPMMA teleblock copolymers can also be enhanced by blending with isotactic PMMA so that the rubbery PBD soft segments are connected to high-melting stereocomplexed hard segments. The factors which affect the mechanical and thermal properties of these novel thermoplastic elastomers have been extensively investigated. [less ▲]

Detailed reference viewed: 34 (4 ULg)