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See detailUtilisation de la méthode LQRT (Lecture / Questions - Réponses / Test) -- SAFE (Système Adulte de Formation et d'Évaluation) en médecine vétérinaire.
Castaigne, Jean-Loup ULg

in Actes du 19ème Colloque de l'AIPU : Les méthodes actives dans l'enseignement supérieur : Regards pluriels et critiques sur les pratiques. (2002, May)

Suite aux résultats d’une évaluation des enseignements par les étudiants, nous avons décidé de mettre en place une nouvelle stratégie de formation centrée sur l’étudiant. La méthode des LQRT (Lecture ... [more ▼]

Suite aux résultats d’une évaluation des enseignements par les étudiants, nous avons décidé de mettre en place une nouvelle stratégie de formation centrée sur l’étudiant. La méthode des LQRT (Lecture, Questions-Réponses, Test) - SAFE (Système Adulte de Formation et d’Évaluation) a été choisie pour dispenser 5 cours portant sur des matières dont la compréhension est importante pour la réussite de l’examen oral de fin d’année. La conclusion directe de l’utilisation de ce système d’enseignement a été une participation plus active des étudiants au cours mais également une responsabilisation de l’apprenant dans le processus de formation par la définition des performances cognitives. Les tests pratiqués durant l’année constituent une évaluation diagnostic pour l’enseignant qui a pu remédier dès le cours suivant aux problèmes de compréhension mis en évidence par le test. Les retombées indirectes comme les gains métacognitifs et l’acquisition d’autres compétences ne sont pas mesurables. Une nouvelle évaluation de l’enseignement a montré que les étudiants ont apprécié l’instauration des LQRT-SAFE en médecine vétérinaire. [less ▲]

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See detailClosure of "a unified approach to transient stability contingency filtering, ranking, and assessment"
Ernst, Damien ULg; Ruiz-Vega, Daniel; Pavella, Mania ULg et al

in IEEE Transactions on Power Systems (2002), 17(2), 528-529

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See detailLa sténose d'artère rénale: cause possible de décompensation cardiaque aiguë
Krzesinski, Jean-Marie ULg

in Revue Médicale de Liège (2002), 57(5), 253-257

Among the different causes of pulmonary edema, there are all the clinical situations with hydrosaline overload. A significant (> 70%) bilateral renal artery stenosis or a unilateral stenosis in the ... [more ▼]

Among the different causes of pulmonary edema, there are all the clinical situations with hydrosaline overload. A significant (> 70%) bilateral renal artery stenosis or a unilateral stenosis in the presence of a solitary kidney is one possibility. Recurrent acute pulmonary edema not fully explained on a cardiac basis is rather typical for such a disease in a cardiac patient with moderate renal failure aggravated when angiotensin converting enzyme inhibitors are used. [less ▲]

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See detailPreventive control of voltage security margins: A multicontingency sensitivity-based approach
Capitanescu, Florin ULg; Van Cutsem, Thierry ULg

in IEEE Transactions on Power Systems (2002), 17(2), 358-364

This paper addresses the problem of changing the operating point of a power system in order to keep voltage security margins with respect to contingencies above some minimal value. Margins take on the ... [more ▼]

This paper addresses the problem of changing the operating point of a power system in order to keep voltage security margins with respect to contingencies above some minimal value. Margins take on the form of maximum pre-contingency power transfers either between a generation and a load area or between two generation areas. They are determined by means of a fast time-domain method. We will first discuss the use of a general optimal power flow, in which linear voltage security constraints are added. The simultaneous control of several (possibly conflicting) contingencies is considered. Then, we will focus on the minimal control change objective. Among the possible controls, emphasis is put on generation rescheduling and load curtailment. Examples are presented on an 80-bus test system as well as on a real system. [less ▲]

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See detailL'allocation pour l'aide d'une tierce personne et son indexation
Michiels, Olivier ULg

in Lexius Actua (2002), 5

L'article fait le point sur l'aide d'une tierce personne en accident du travail et sur l'indexation de cette allocation.

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See detailContributions to decision tree induction: bias/variance tradeoff and time series classification
Geurts, Pierre ULg

Doctoral thesis (2002)

Because of the rapid progress of computer and information technology, large amounts of data are nowadays available in a lot of domains. Automatic learning aims at developing algorithms able to produce ... [more ▼]

Because of the rapid progress of computer and information technology, large amounts of data are nowadays available in a lot of domains. Automatic learning aims at developing algorithms able to produce synthetic high-level information, or models, from this data. Learning algorithms are generally evaluated according to three different criteria: interpretability (how well the model helps to understand the data), predictive accuracy (how well the model can predict unseen situations), and computational efficiency (how fast is the algorithm and how it scales to large databases). This thesis explores two issues in automatic learning: the improvement of the well-known decision tree induction method and the problem of learning classification models for time series data. Decision tree induction method is an automatic learning algorithm which focuses on the modeling of input/output relationships. While this algorithm is among the fastest and most interpretable methods, its accuracy is not always competitive with respect to other algorithms. It is commonly admitted that this suboptimality is due to the excessive variance of this method. We first carry out an empirical study which shows quantitatively how important this variance is, i.e. how strongly decision trees depend on the random nature of the database used to infer them. These experiments confirm that this variance is detrimental not only from the point of view of accuracy but also from the point of view of interpretability. With the goal of improving both interpretability and accuracy, we consider three variance reduction techniques for decision trees. First, in the goal of improving mainly interpretability, we propose several methods which try to stabilize the parameters chosen during tree induction. While these methods succeed in reducing the variability of the parameters, they produce only a slight improvement of the accuracy. Then, we consider perturb and combine algorithms (e.g. bagging, boosting) which consist in combining the predictions of several models obtained by randomizing in some way the learning process. Inspired by the high variance of the parameters defining a decision tree, we propose an extremely randomized decision tree induction algorithm, called extra-tree, which chooses all parameters at random during induction. The aggregation of several of these extra-trees gives an important reduction of variance and this algorithm compares favorably in terms of accuracy and computational efficiency with both bagging and boosting. Because of the randomization of the parameters, the resulting method is also competitive with classical decision tree induction in terms of computational efficiency. In addition to these two approaches, we propose a ``dual'' perturb and combine algorithm which delays the perturbation at the prediction stage and hence requires only one model. In combination with decision tree, this method actually bridges the gap between single decision trees and perturb and combine algorithms. Of the first, it saves the interpretability (by using only one model), and with perturb and combine algorithm, it shares some of the accuracy (by reducing the variance). The second topic of the thesis is the problem of time series classification. The most direct way to solve this problem is to apply existing learning algorithms on low-level variables which correspond to the values of a time series at several time points. Experiments with the tree-based algorithms studied in the first part of the thesis shows that this approach is limited. A variance reduction techniques is then proposed specifically for this kind of data which consists in aggregating the prediction given by a classification model for subsequences of time series. Since this method does not provide interpretable models, we propose a second method which extends decision tree tests by allowing them to detect local shift invariant properties, or patterns, in time series. The study proposed in this part of the thesis is only a first step in the domain but our conclusions give some future work directions for handling complex type of data with automatic learning methods. [less ▲]

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See detailFinite Element Analysis of the Electro-Mechanical Coupling in MEMS
Rochus, Véronique ULg; Duysinx, Pierre ULg; Golinval, Jean-Claude ULg

Conference given outside the academic context (2002)

This paper concerns the modelling of the strong electro-mechanical coupling appearing in micro-electro-mechanical systems (MEMS). These systems are very small devices (typical size of a few microns), in ... [more ▼]

This paper concerns the modelling of the strong electro-mechanical coupling appearing in micro-electro-mechanical systems (MEMS). These systems are very small devices (typical size of a few microns), in which electric phenomena as well as mechanical and dynamical phenomena exist. The coupling between the electric and mechanical fields induce non-linear terms in the dynamic equilibrium equations of these microscopic structures so that instability may occur. In this paper, the finite element method (FEM) is used to perform modal analysis around non-linear equilibrium positions, taking into account large displacements. [less ▲]

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See detailSelection of approximation schemes in topology optimization
Bruyneel, Michaël ULg; Duysinx, Pierre ULg

in Hogge, Michel (Ed.) Proceedinsg of the ACOMEN 2002, 2nd International Conference on Advanced Computational Methods in Engineering (2002, May)

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See detailNestin expression in cultivated mesenchymal stem cells: Regulation and potential role in their neural differentiation
Wislet-Gendebien, Sabine ULg; Leprince, Pierre ULg; Moonen, Gustave ULg et al

in Glia (2002, May), (Suppl. 1), 87

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural ... [more ▼]

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural cells in appropriate in vivo experimental conditions (Kopen and al.,PNAS,96, 10711,1999, Brazelton and al, Science, 290,1175, 2000, Mezey and al, Science, 290,1179, 2000). In neurological disorders, such as Alzheimer's and Parkinson's diseases, auto-transplantation of neural cell types derived from mesenchymal stem cells offers the potential of replacing lost cells and recovering lost functions. Nestin is an intermediate filament protein predominantly expressed by neural stem cells and is used to identify neural progenitor. In this study, we demonstrate that cultured rat mesenchymal stem cells (rMSC) can express nestin in appropriate conditions. Two factors contribute to the regulation of nestin expression by rMSC : 1) the presence of serum-derived components in the culture medium which repress nestin expression and 2) the cell’s number of passages. LPA and thrombin mimic this serum effect. Furthermore, when nestin- positive cells are trypsinized and resuspended into culture conditions used for neural stem cells (NSC), sphere formation is observed. Likewise, by co-cultivating nestin-positive rMSC with NSC derived from green mouse, heterogenous spheres were obtained. When those heterogenous spheres are placed on polyornithine-coated surfaces, a differentiation of some rMSC into GFAP-positive cells occurs. These results indicate that nestin expression might be a pre-requisite for the acquisition by rMSC of the capacity to differentiate into some neural cell types. [less ▲]

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See detailThe application of EIA/SEA procedures to the urban cultural heritage active conservation
Teller, Jacques ULg; Dupagne, Albert ULg

in Proc. of 5th European Commission Conference on Research for Protection, Conservation and Enhancement of Cultural Heritage (2002)

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See detailEvaluation de l'huile de chaîne à base végétale
Debouche, Charles ULg; Novak, Marie Hélène; Sonneville, G.

in Forêt Wallonne (2002), 58

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See detailComputer-Aided Design of Redundant Sensor Networks
Heyen, Georges ULg; Dumont, Marie-Noëlle ULg; Kalitventzeff, Boris ULg

Poster (2002, May)

A systematic method to design sensor networks able to identify key process parameters with a required precision at a minimal cost is presented. The procedure is based on a linearised model, derived ... [more ▼]

A systematic method to design sensor networks able to identify key process parameters with a required precision at a minimal cost is presented. The procedure is based on a linearised model, derived automatically from a rigorous non-linear data reconciliation model. A genetic algorithm is used to select the sensor types and locations. [less ▲]

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See detailpH-Dependence of the morphology of micelles formed by poly(2-vinylpyridine)-block-poly(ethylene oxide) copolymers in water
Gohy, Jean-François; Mores, Sandrine; Varshney, Sunil K et al

in e-Polymers (2002), (21), 1-8

The morphology of micelles formed by two poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphate-buffered water by dynamic light scattering and transmission ... [more ▼]

The morphology of micelles formed by two poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphate-buffered water by dynamic light scattering and transmission electron microscopy. Spherical micelles are observed when the P2VP block is the minor component of the diblock copolymer. When P2VP dominates the composition, transition from spheres-to-rods-to-vesicles takes place in a narrow pH range that straddles the pKa of P2VP. This transition is controlled by the degree of protonation of the P2VP blocks. At high pH, the copolymer precipitates from the solution. [less ▲]

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See detailThe concept of "Economic Added Result", a new tool to prevent bankruptcy ?
Van Caillie, Didier ULg; Dighaye, Andrée

in European Accounting Association (Ed.) Proceedings of the 25th European Accounting Association Congress (2002, April 25)

Business failure has been one of the most investigated topics in the finance and the strategic literature during the last seven decades. However, most of this literature has been heavily focused on ... [more ▼]

Business failure has been one of the most investigated topics in the finance and the strategic literature during the last seven decades. However, most of this literature has been heavily focused on business failure prediction (with a clear focus on short-term prediction) and, simultaneously, only a few studies have investigated business failure prevention, focusing on understanding how a company may fail through "failure paths" and on the identification of very early warning financial and non-financial signals and symptoms. This may be explained by a conceptual difficulty to exactly represent what business failure prevention may mean and by a practical difficulty to build a financial indicator really allowing to announce a bankruptcy at least three years or more in advance, giving then time to potential corporate recovery. With this paper, we then propose an investigation of this concept of "Business Failure Prevention" and we test on a sample of 6 250 Belgian SMEs the ability of a specific financial indicator (referred as "Economic Added Result" and based on the amount of accounting value added which remains within a company when it has paid for its internal and external production factors) to effectively predict a business failure at least three years before it happens. [less ▲]

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See detailLa surcharge pondérale chez l'enfant: un problème qui concerne toute la famille
Battisti, Oreste ULg

Conference (2002, April 22)

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See detailEtude sur le tassement du bois dans la construction de maison à ossature en bois massif (technique des bois empilés)
Franssen, Jean-Marc ULg

Report (2002)

This report covers several aspects:An Excel sheet for designing 68/218 mm² beams according to Eurocode 5 ENV 1995-1-1; design equations and experimental test made on a 5.14 m long main beam with a 140x350 ... [more ▼]

This report covers several aspects:An Excel sheet for designing 68/218 mm² beams according to Eurocode 5 ENV 1995-1-1; design equations and experimental test made on a 5.14 m long main beam with a 140x350 mm² section in which reservations have been cut to introduce the 68/218 transverse beams; a experimental test on a steel connection between two glue laminated timber beams; a fire resistance test on a 2.17x1.64 m² wall with a thickness of 86 mm. [less ▲]

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See detailSubdivision of the helix-turn-helix GntR family of bacterial regulators in the FadR, HutC, MocR, and YtrA subfamilies
Rigali, Sébastien ULg; Derouaux, Adeline ULg; Giannotta, F. et al

in Journal of Biological Chemistry (2002), 277(15), 12507-12515

Haydon and Guest (Haydon, D. J, and Guest, J. R. (1991) FEMS Microbiol Lett. 63, 291-295) first described the helix-turn-helix GntR family of bacterial regulators. They presented them as transcription ... [more ▼]

Haydon and Guest (Haydon, D. J, and Guest, J. R. (1991) FEMS Microbiol Lett. 63, 291-295) first described the helix-turn-helix GntR family of bacterial regulators. They presented them as transcription factors sharing a similar N-terminal DNA-binding (D-b) domain, but they observed near-maximal divergence in the C-terminal effector-binding and oligomerization (E-b/O) domain. To elucidate this C-terminal heterogeneity, structural, phylogenetic, and functional analyses were performed on a family that now comprises about 270 members. Our comparative study first focused on the C-terminal E-b/O domains and next on DNA-binding domains and palindromic operator sequences, has classified the GntR members into four subfamilies that we called FadR, HutC, MocR, and YtrA. Among these subfamilies a degree of similarity of about 55% was observed throughout the entire sequence. Structure/function associations were highlighted although they were not absolutely stringent. The consensus sequences deduced for the DNA-binding domain were slightly different for each subfamily, suggesting that fusion between the D-b and E-b/O domains have occurred separately, with each subfamily having its own D-b domain ancestor. Moreover, the compilation of the known or predicted palindromic cis-acting elements has highlighted different operator sequences according to our subfamily subdivision. The observed C-terminal E-b/O domain heterogeneity was therefore reflected on the DNA-binding domain and on the cis-acting elements, suggesting the existence of a tight link between the three regions involved in the regulating process. [less ▲]

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See detailL'évaluation de la mémoire épisodique
Adam, Stéphane ULg; Van der Linden, Martial; Membres du GREMEM

in Revue Neurologique (2002, April 03), 158(Supplément 1), 180

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See detailInfluence of non-adiabatic temperature variations on line profile variations of slowly rotating beta Cephei stars and SPBs. II. Simulations of line profile time series
De Ridder, J.; Dupret, Marc-Antoine ULg; Neuforge, C. et al

in Astronomy and Astrophysics (2002), 385

We investigate to what extent non-adiabatic temperature variations at the surface of slowly rotating non-radially pulsating beta Cephei stars and slowly pulsating B stars affect silicon line profile ... [more ▼]

We investigate to what extent non-adiabatic temperature variations at the surface of slowly rotating non-radially pulsating beta Cephei stars and slowly pulsating B stars affect silicon line profile variations. We use the non-adiabatic amplitudes of the effective temperature and gravity variation presented in Dupret et al. (\cite{Dupret02}), together with a Kurucz intensity grid, to compute time series of line profile variations. Our simulations point out that the line shapes do not change significantly due to temperature variations. We find equivalent width variations of at most two percent of the mean equivalent width. We confront our results with observational equivalent width variations and with photometrically obtained effective temperature variations. Based on observations obtained with the Swiss photometric telescope and with the ESO/CAT telescope, at La Silla in Chile. [less ▲]

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