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See detailRégénération de Phaseolus vulgaris L. et P. polyanthus Greenm. à partir d'embryons immatures en vue de leur hybridation interspécifique
Toussaint, André ULg; Geerts, P.; Clément, F. et al

in Actes des VIIIèmes Journées Scientifiques du Réseau "Biotechnologies, Amélioration des plantes et Sécurité alimentaire" (2002)

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See detailGlacial-interglacial changes of continental weathering: estimates of the related CO2 and HCO3- flux variations and their uncertainties
Munhoven, Guy ULg

in Global and Planetary Change (2002), 33(1-2), 155-176

A range of estimates for the glacial-interglacial variations in CO, consumption and HCO3- production rates by continental weathering processes were calculated with two models of continental weathering ... [more ▼]

A range of estimates for the glacial-interglacial variations in CO, consumption and HCO3- production rates by continental weathering processes were calculated with two models of continental weathering: the Gibbs and Kump Weathering Model (GKWM) [Paleoceanography 9(4) (1994) 529] and an adapted version of Amiotte Suchet and Probst's Global Erosion Model for CO2 Consumption (GEM-CO2) [C. R, Acad. Sci. Paris, Ser. 11317 (1993) 615; Tellus 47B (1995) 273]. Both models link CO2 consumption and HCO3- production rates to the global distributions of lithology and runoff. A spectrum of 16 estimates for the runoff distribution at the Last Glacial Maximum (LGM) was constructed on the basis of two different data sets for present-day runoff and climate results from eight GCM climate simulation experiments carried out in the framework of the Paleo Modelling Intercomparison Project (PMIP). With these forcings, GKWM produced 3.55-9.0 Tmol/year higher and GEM-CO2 4.7-13.25 Tmol/year higher global HCO3- (1 Tmol=10(12) mol) production rates at the LGM, Mean variations (plus/minus one standard error of the mean with 7 df) were 6.2+/-0.6 and 9.4+/-1.0 Tmol/year, respectively. The global CO2 consumption rates obtained with GKWM were 1.05-4.5 Tmol/year (mean: 2.8+/-0.4 Tmol/year) higher at the LGM than at present. With GEM-CO2 this increase was 1.95-7.15 Tmol/year (mean: 4.8+/-0.6 Tmol/year). The large variability in the changes obtained with each weathering model was primarily due to the variability in the GCM results. The increase in the CO2 consumption rate due to continental shelf exposure at the LGM was always more than 60% larger than its reduction due to ice cover. For HCOT production rates, the increase related to shelf exposure was always more than twice as large as the decrease due to ice cover. Flux variations in the areas exposed both now and at the LGM were, in absolute value, always more than 3.5 times lower than those in the shelf environment. The calculated CO2 consumption rates by carbonate weathering were consistently higher at the LGM, by 2.45-4.5 Tmol/year (mean: 3.4+/-0.2 Tmol/year) according to GKWM and by 2.75-6.25 Tmol/year (mean: 4.6+/-0.4 Tmol/year) according to GEM-CO, For silicate weathering, GKWM produced variations ranging between a 1.9 Tmol/year decrease and a 0.4 Tmol/year increase for the LGM (mean variation: -0.7+/-0.2 Tmol/year); GEM-CO, produced variations ranging between a 0.8 Tmol/year decrease and a 1.05 Tmol/year increase (mean variation: +0.2+/-0.2 Tmol/year). In the mean, the calculated variations of CO2 and HCO3- fluxes would contribute to reduce atmospheric p(CO2) by 5.7+/-1.3 ppmv (GKWM) or 3 12.1+/-1.7 ppmv (GEM-CO2), which might thus represent a non-negligible part of the observed glacial interglacial variation of similar to 75 ppmv. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailHydrothermal Synthesis of Alluaudite in the Na-Mn-Fe2+-Fe3+-P-O System
Hatert, Frédéric ULg

in Journal of Conference Abstracts (2002), 7(1), 44

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See detailMembrane Destabilization Induced By Beta-Amyloid Peptide 29-42: Importance Of The Amino-Terminus
Mingeot-Leclercq, Mp.; Lins, Laurence ULg; Bensliman, M. et al

in Chemistry and Physics of Lipids (2002), 120(1-2), 57-74

Increasing evidence implicates interactions between Abeta-peptides and membrane lipids in Alzheimer's disease. To gain insight into the potential role of the free amino group of the N-terminus of Abeta29 ... [more ▼]

Increasing evidence implicates interactions between Abeta-peptides and membrane lipids in Alzheimer's disease. To gain insight into the potential role of the free amino group of the N-terminus of Abeta29-42 fragment in these processes, we have investigated the ability of Abeta29-42 unprotected and Abeta29-42 N-protected to interact with negatively-charged liposomes and have calculated the interaction with membrane lipids by conformational analysis. Using vesicles mimicking the composition of neuronal membranes, we show that both peptides have a similar capacity to induce membrane fusion and permeabilization. The fusogenic effect is related to the appearance of non-bilayer structures where isotropic motions occur as shown by 31P and 2H NMR studies. The molecular modeling calculations confirm the experimental observations and suggest that lipid destabilization could be due to the ability of both peptides to adopt metastable positions in the presence of lipids. In conclusion, the presence of a free or protected (acetylated) amino group in the N-terminus of Abeta29-42 is therefore probably not crucial for destabilizing properties of the C-terminal fragment of Abeta peptides. [less ▲]

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See detailComposite structures optimization using sequential convex programming
Bruyneel, Michaël ULg; Fleury, Claude ULg

in Advances in Engineering Software (2002), 33(7-10), 697-711

The design of composite structures is considered here. The approximation concepts approach is used to solve the optimization problem. The convex approximations of the MMA family are briefly described ... [more ▼]

The design of composite structures is considered here. The approximation concepts approach is used to solve the optimization problem. The convex approximations of the MMA family are briefly described. Several modifications of these approximations are presented. They are now based on gradient information at two successive iterations, avoiding the use of the expensive second-order derivatives. A two-point fitting scheme is also described, where the function value at the preceding design point is used to improve the approximation. Numerical examples compare these new purely non-monotonous schemes to the existing ones for the selection of optimal fibers orientations in laminates. It is shown how these two-point based approximations are well adapted to the problem and can improve the optimization task, leading to reasonable computational efforts. A procedure is also derived for considering simultaneously monotonous and non-monotonous structural behaviors. The resulting generalized approximation scheme is well suited for the optimization of composite structures when both plies thickness and fibers orientations are considered as design variables. It is concluded that the newly developed approximation schemes of the MMA family are reliable for composite structures optimization. All the studied approximations are convex and separable: the optimization problem can then be solved using a dual approach. (C) 2002 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailUne séquence didactique expérimentale sur les stratégies de communication (vidéogramme)
Doppagne, Véronique ULg; Hertay, Alain; Simons, Germain ULg

Learning material (2002)

Ce vidéogramme présente différentes stratégies de compensation utilisées par des élèves du secondaire confrontés à des problèmes de communication. Parmi ceux-ci, on trouve le mime, la demande d'assistance ... [more ▼]

Ce vidéogramme présente différentes stratégies de compensation utilisées par des élèves du secondaire confrontés à des problèmes de communication. Parmi ceux-ci, on trouve le mime, la demande d'assistance dans la langue étrangère, la circonlocution... La langue ciblée est l'anglais. [less ▲]

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See detailPinéalomes familiaux : Etudes biologiques et génétiques préliminaires
Allouch, A.; Valdes Socin, Hernan Gonzalo ULg; Hendrick, J. C. et al

in XXème Congrès de la Société Française d'Endocrinologie - Abstract book (2002)

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See detailGeneration of a finite element MESH from stereolithography (STL) files
Béchet, Eric ULg; Cuilliere, Jean-Christophe; Trochu, François

in Computer-Aided Design (2002), 34(1), 1-17

The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an ... [more ▼]

The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an object created with CAD software. First, we describe the boundary representation, which is composed of a simple triangulation of the surface of the object. Then we will show how to obtain a conforming size-adapted mesh. The size adaptation is made considering geometrical approximation and with respect to an isotropic size map provided by an error estimator. The mesh can be used "as is" for a finite element computation (with shell elements), or can be used as a surface mesh to initiate a volume meshing algorithm (Delaunay or advancing front). The principle used to generate the mesh is based on the Delaunay method, which is associated with refinement algorithms, and smoothing. Finally, we will show that not using the parametric representation of the geometrical model allows us to override some of the limitations of conventional meshing software that is based on an exact representation of the geometry. (C) 2001 Published by Elsevier Science Ltd. [less ▲]

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See detailThe Euler number as an index of spatial integrity of landscapes: evaluation and proposed improvement.
Bogaert, Jan ULg; Van Hecke, P; Ceulemans, R

in Environmental Management (2002), 29(5), 673-682

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See detailLiteratura e engajamento. De Pascal a Sartre
Denis, Benoît ULg

Book published by EDUSC (2002)

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See detailPurification and characterization of a pregnancy-associated glycoprotein (ovPAG-6) from sheep placenta removed between 66 to 100 days of gestation.
El Amiri, B.; Remy, B.; Melo de Sousa, Noelita ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2002), 6(1), 12-13

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See detailResonance-assisted tunneling
Brodier, O.; Schlagheck, Peter ULg; Ullmo, D.

in Annals of Physics (2002), 300(1), 88-136

We present evidence that tunneling processes in near-integrable systems are enhanced due to the manifestation of nonlinear resonances and their respective island chains in phase space. A semiclassical ... [more ▼]

We present evidence that tunneling processes in near-integrable systems are enhanced due to the manifestation of nonlinear resonances and their respective island chains in phase space. A semiclassical description of this "resonance-assisted" mechanism is given, which is based on a local perturbative description of the dynamics in the vicinity of the resonances. As an underlying picture, we obtain that the quantum state is coupled, via a succession of classically forbidden transitions across nonlinear resonances, to high excitations within the well, from where tunneling occurs with a rather large rate. The connection between this description and the complex classical structure of the underlying integrable dynamics is furthermore studied, giving ground to the general coherence of the description as well as guidelines for the identification of the dominant tunneling paths. The validity of this mechanism is demonstrated within the kicked Harper model, where good agreement between quantum and semiclassical (resonance-assisted) tunneling rates is found. (C) 2002 Elsevier Science (USA). [less ▲]

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See detailDMPO for quantitative measurements of singlet oxygen production?
Damoiseau, X.; Heyne, B.; Hoebeke, Maryse ULg

Conference (2002)

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See detailModelled glacial and non-glacial HCO3-, Si and Ge fluxes since the LGM: little potential for impact on atmospheric CO2 concentrations and a potential proxy of continental chemical erosion, the marine Ge/Si ratio
Jones, Ian W; Munhoven, Guy ULg; Tranter, Martyn et al

in Global and Planetary Change (2002), 33(1-2), 139-153

The runoff and riverine fluxes of HCO3-, Si and Ge that arise from chemical erosion in non-glaciated terrain, are modelled at six time steps from the Last Glacial Maximum (LGM) to the present day. The ... [more ▼]

The runoff and riverine fluxes of HCO3-, Si and Ge that arise from chemical erosion in non-glaciated terrain, are modelled at six time steps from the Last Glacial Maximum (LGM) to the present day. The fluxes that arise from the Great Ice Sheets are also modelled. Terrestrial HCO3- fluxes decrease during deglaciation, largely because of the reduction in the area of the continental shelves as sea level rises. The HCO3- fluxes. and the inferred consumption of atmospheric CO2 are used as inputs to a carbon cycle model that estimates their impact on atmospheric CO2 concentrations ((CO2)-C-atms). A maximum perturbation of (CO2)-C-atms by similar to 5.5 ppm is calculated, The impact of solutes from glaciated terrain is small in comparison to those from non-glaciated terrain. Little variation in terrestrial Si and Ge fluxes is calculated (< 10%). However, the global average riverine Ge/Si ratio may be significantly perturbed if the glacial Ge/Si ratio is high. At present. variations in terrestrial chemical erosion appear to have only a reduced impact on (CO2)-C-atms and only little influence on the global Si and Ge cycle and marine Ge/Si ratios during deglaciation. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailAttention disorders in neurodegenerative diseases
Collette, Fabienne ULg; Van der Linden, Martial ULg

in Leclerq, M.; Zimmerman, P. (Eds.) Applied neuropsychology of attention : theory, diagnosis and rehabilitation (2002)

A number of neuropsychological studies in recent years have shown that demented patients do not necessarily present a global deterioration and that the disease can impair some cognitive processes or ... [more ▼]

A number of neuropsychological studies in recent years have shown that demented patients do not necessarily present a global deterioration and that the disease can impair some cognitive processes or systems, while sparing others. Moreover, qualitatively different patterns of cognitive impairment have been identified in association with different types of neurodegenerative dementias, such as Alzheimer's disease, Huntington's disease, Parkinson's disease or frontotemporal dementia. [less ▲]

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See detailNonlinear thin shell finite element for steel and concrete structures subjected to fire: theoretical development
Talamona, Didier; Franssen, Jean-Marc ULg

in Journal of Applied Fire Science (2002), 11(4), 291-310

This article describes the features of a quadrilateral thin shell element, based on Marguerre's theory that has ben implemented in the finite element program SAFIR (from the University of Liege.) The ... [more ▼]

This article describes the features of a quadrilateral thin shell element, based on Marguerre's theory that has ben implemented in the finite element program SAFIR (from the University of Liege.) The element has four nodes (one at each corner) and each node has six degrees of freedom, i.e., three translations and three rotations (the sixth degree of freedom is a true one, which can be assimilated to the in-plane rotation.) This article presents some theoretical developments regarding the element formulation. The algorithm strategies for isotropic material (steel for example) and non-isotropic material 'concrete) and their modifications for elevated temperatures are described. Two verifications examples are presented (the patch test and Lee's frame at elevated temperatures). [less ▲]

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