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See detailLa démarche expérimentale comme référent externe à l'autorité du professeur ... ou quand le bruit et l'action sont synonymes d'apprentissage et de compétences
Hindryckx, Marie-Noëlle ULg; Daussogne, Christine

in Puzzle (2007, December), 23

Que signifie mener une démarche expérimentale en sciences? En partant d'une mise en situation concrète, nous avons voulu essayer de répondre à quelques questions : que fait-on quand on expérimente en ... [more ▼]

Que signifie mener une démarche expérimentale en sciences? En partant d'une mise en situation concrète, nous avons voulu essayer de répondre à quelques questions : que fait-on quand on expérimente en classe? quel est le rôle de l'élève? de l'enseignant? Quels sont les avantages de travailler par cette méthode? Qui fait "autorité" quand on travaille de telle manière? Les échanges ont été étayés par des résultats d'une recherche-action menée au fondamental. [less ▲]

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See detailOn the Construction of WiMAX Mesh Tree
Nahle, Salim; Iannone, Luigi,; Donnet, Benoît ULg et al

in IEEE Communications Letters (2007), 11(12),

The IEEE 802.16 protocol, also known as WiMAX, has been designed to support long-range communications with high bitrates, using two operation modes: Point-to-Multi-Point (PMP) and Mesh. In the mesh mode ... [more ▼]

The IEEE 802.16 protocol, also known as WiMAX, has been designed to support long-range communications with high bitrates, using two operation modes: Point-to-Multi-Point (PMP) and Mesh. In the mesh mode, Subscriber Stations (SSs) can directly communicate with each other, thus forming a tree, and can be used to forward other's data packets in a multi-hop fashion. On the contrary, in the PMP mode only one hop communication toward the Base Station (BS) is allowed. In this paper, we investigate the performance of the mesh mode by proposing an algorithm for constructing the WiMAX mesh tree. Our algorithm increases routes' effective throughput by splitting long links into multiple shorter ones. We show through simulations that this approach leads to improving the throughput capacity of WiMAX-based wireless mesh networks. [less ▲]

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See detailInternet Topology Discovery: a Survey
Donnet, Benoît ULg; Friedman, Timur

in IEEE Communications Surveys and Tutorials (2007), 9(4), 2-15

Since the beginning of the nineties, the internet has undergone impres- sive growth. This growth can be appreciated in terms of the equipment, such as routers and links, that has been added, as well as in ... [more ▼]

Since the beginning of the nineties, the internet has undergone impres- sive growth. This growth can be appreciated in terms of the equipment, such as routers and links, that has been added, as well as in the numbers of users and the value of commerce that it supports. In parallel to this expansion, over the past decade the networking research community has shown a growing interest in discovering and analyzing the internet topology. Some researchers have developed tools for gathering network topology data while others have tried to understand and model the internet’s properties. These efforts have brought us to a crucial juncture for toplogy measurement infrastructures: while, previously, these were both small (in terms of number of measurement points) and monolithic, we are starting to see the deployment of large-scale distributed systems composed of hundreds or thousands of monitors. As we look forward to this next generation of systems, we take stock of what has been achieved so far. In this survey, we discuss past and current mechanisms for discovering the internet topology at various levels: the IP interface, the router, the AS, and the PoP level. In addition to discovery techniques, we provide insights into some of the well- known properties of the internet topology. [less ▲]

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See detailImplementation and Preliminary Evaluation of an ISP-Driven Informed Path Selection
Saucez, Damien; Donnet, Benoît ULg; Bonaventure, Olivier

in ACM CoNEXT conference (2007, December)

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See detailLa personnalité borderline: clinique d'une psychopathologie "sans limites"
Debabeche, Cécile ULg; Lebas, Maud ULg; Triffaux, Jean-Marc ULg

in Revue Médicale de Liège (2007), 62(12), 730-5

The borderline personality disorder is a common psychiatric entity, which is characterized by a varied symptomatology and a significant comorbidity. It seems that its etiologic is heterogeneous ... [more ▼]

The borderline personality disorder is a common psychiatric entity, which is characterized by a varied symptomatology and a significant comorbidity. It seems that its etiologic is heterogeneous, comprising psychosocial factors as much as biological and genetic. So the best approach of the borderline personality disorder would be a multidisciplinary bio-psycho-social one. Through a clinical case, we illustrate this disorder and its treatment in outpatient clinic. [less ▲]

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See detailCaractérisation physiologique et biochimique du processus de vieillissement du tubercule de pomme de terre (Solanum tuberosum L.)
Delaplace, Pierre ULg

Doctoral thesis (2007)

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the ... [more ▼]

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the biochemical processes underlying ageing, potato seed tubers (cv. Bintje and Désirée) were stored at 4°C for 7 months and regularly sampled to assess both physiological and biochemical parameters. Physiological age markers (PAI, incubation period) evolution was measured and allowed us to define a reference frame more accurate than the chronological age. A correlation has also been established with the growth parameters (number of stems, duration before emergence). In parallel, two biochemical approaches allowed us to assay proteome and antioxidant system modifications occurring during ageing. Protein pattern evolution was assessed by DIGE after hot SDS extraction. During ageing, 93 spots were strictly up- or down- regulated while 4 others exhibited an abundance curve with a transient maximum. After manual picking of 43 selected spots based on their expression profile, 32 proteins were identified by MS/MS. Differentially expressed proteins are mainly involved in patatin catabolism, stress response, glycolysis, protein turn-over and lipid oxidation. A complementary targeted approach has then been set up based on the free radical ageing theory. SOD, CAT, APX and POX activities as well as ascorbate, glutathione, carotenoid and phenolic compound contents were measured during ageing. These data seem to indicate that the antioxidant system undergoes marked changes in response to an increased production of reactive oxygen species. However, no accumulation of oxidative damages has been observed on lipids and proteins. All these kinetic data allowed us to build an integrated ageing model. These results are discussed in the above-mentioned theoretical context. [less ▲]

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See detailDes villes qui marchent
Frankignoulle, Pierre ULg

Report (2007)

Etat de l'art + bibliographie sur le thème de la marche en ville

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See detailObservations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456
Randall, Suzanna K.; Green, Elizabeth M.; Van Grootel, Valérie ULg et al

in Astronomy and Astrophysics (2007), 476

Aims:The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to ... [more ▼]

Aims:The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to constrain the internal characteristics of hot B subdwarfs with the long-term goal of differentiating between the various formation scenarios proposed for these objects. So far, a detailed asteroseismic interpretation has been carried out for 6 such pulsators, with apparent success. First comparisons with evolutionary theory look promising, however it is clear that more targets are needed for meaningful statistics to be derived. Methods: The observational pulsation periods of PG 0911+456 were extracted from rapid time-series photometry using standard Fourier analysis techniques. Supplemented by spectroscopic estimates of the star's mean atmospheric parameters, they were used as a basis for the “forward modelling” approach in asteroseismology. The latter culminates in the identification of one or more “optimal” models that can accurately reproduce the observed period spectrum. This naturally leads to an identification of the oscillations detected in terms of degree ℓ and radial order k, and infers the structural parameters of the target. Results: The high S/N low- and medium resolution spectroscopy obtained led to a refinement of the atmospheric parameters for PG 0911+456, the derived values being T_eff = 31 940 ± 220 K, log g = 5.767 ± 0.029, and log He/H = -2.548 ± 0.058. From the photometry it was possible to extract 7 independent pulsation periods in the 150-200 s range with amplitudes between 0.05 and 0.8% of the star's mean brightness. There was no indication of fine frequency splitting over the 68-day time baseline, suggesting a very slow rotation rate. An asteroseismic search of parameter space identified several models that matched the observed properties of PG 0911+456 well, one of which was isolated as the “optimal” model on the basis of spectroscopic and mode identification considerations. All the observed pulsations are identified with low-order acoustic modes with degree indices ℓ = 0,1,2 and 4, and match the computed periods with a dispersion of only 0.26%, typical of the asteroseismological studies carried out to date for this type of star. The inferred structural parameters of PG 0911+456 are T_eff = 31 940 ± 220 K (from spectroscopy), log {g} = 5.777 ± 0.002, Mast/Msun = 0.39 ± 0.01, log{M_env/Mast} = -4.69 ± 0.07, R/Rsun = 0.133 ± 0.001 and L/Lsun = 16.4 ± 0.8. We also derive the absolute magnitude MV = 4.82 ± 0.04 and a distance d = 930.3 ± 27.4 pc. [less ▲]

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See detailInhibition of tumor growth and metastasis establishment by adenovirus-mediated gene transfer delivery of the antiangiogenic factor 16K hPRL
Nguyen, Ngoc-Quynh-Nhu ULg; Cornet, Anne ULg; Blacher, Silvia ULg et al

in Molecular Therapy : The Journal of the American Society of Gene Therapy (2007), 15(12), 2094-2100

Tumor metastases, the most fearsome aspect of cancer, are generally resistant to conventional therapies. Angiogenesis is a crucial aspect of tumor growth and metastatic dissemination. Antiangiogenic ... [more ▼]

Tumor metastases, the most fearsome aspect of cancer, are generally resistant to conventional therapies. Angiogenesis is a crucial aspect of tumor growth and metastatic dissemination. Antiangiogenic therapy, therefore, holds potential as an attractive strategy for inhibiting metastasis development. Human 16K PRL (16K hPRL), a potent inhibitor of angiogenesis, has been demonstrated to prevent tumor growth in two xenograft mouse models, but whether it also affects tumor metastasis is unknown. In this study we will investigate the ability of 16K hPRL to prevent the establishment of metastasis. We demonstrate that 16K hPRL administered via adenovirus-mediated gene transfer, inhibits tumor growth by 86% in a subcutaneous (SC) B16-F10 mouse melanoma model. Computer-assisted image analysis shows that 16K hPRL treatment results in a reduction of tumor-vessel length and width, leading to a 57% reduction of average vessel size. In a pre-established tumor model, moreover, 16K hPRL can significantly delay tumor development. Finally, for the first time, we provide evidence that 16K hPRL considerably reduces the establishment of B16-F10 metastasis in an experimental lung metastasis model. Both the number and size of metastases are reduced by 50% in 16K hPRL-treated mice. These results highlight a potential role for 16K hPRL in anticancer therapy for both primary tumors and metastases. [less ▲]

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See detailBiofilms endodontiques et infections tardives des prothèses totales de hanche
Goffart, Joseph ULg; Gillet, Philippe ULg

in Revue Médicale de Liège (2007), 62(12), 736-42

Biofilms are well recognised in different settings. Endodontic biofilms containing bacteria responsible for bacteraemia and secondary infection of total hip arthroplasties (THA) represent a diagnostic ... [more ▼]

Biofilms are well recognised in different settings. Endodontic biofilms containing bacteria responsible for bacteraemia and secondary infection of total hip arthroplasties (THA) represent a diagnostic challenge because they are often asymptomatic. Their treatment is difficult and inadequate management of such unrecognised sources of systemic infection can lead to the devastating situation of an infected arthroplasty necessitating implant removal, long term antibiotic treatment and secondary implantation of a new prosthesis. Since about ten percent of secondary infected THA can have a dental origin, this article is intended to give guidelines to all intervening care providers: general practitioner, orthopaedic surgeon and dentist. [less ▲]

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See detailG_CUBE
Lejeune, Philippe ULg; Gheysen, Thibaut ULg

Software (2007)

G-Cube est un logiciel de cubage d'arbres sur pieds ou abattus fonctionnant dans l'environnement Microsoft® Excel. Il donne accès aux principaux barèmes de cubage (défilement, décroissance), ainsi qu'aux ... [more ▼]

G-Cube est un logiciel de cubage d'arbres sur pieds ou abattus fonctionnant dans l'environnement Microsoft® Excel. Il donne accès aux principaux barèmes de cubage (défilement, décroissance), ainsi qu'aux équations de cubage adaptées à la Région wallonne. Il accepte différentes modalités de mesures de grosseurs des arbres (diamètre ; circonférence ; 1,3m ; 1,5m ; …) et de présentation des données (arbres individuels, listes par classes de grosseur, listes par classes de grosseur et de hauteur). Il intègre également un module simplifié de traitement de données d'inventaire par échantillonnage [less ▲]

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See detailColliding-wind binaries as non-thermal X-ray emitters: an observational investigation from XMM-Newton to next generation X-ray observatories
De Becker, Michaël ULg

Poster (2007, December)

The investigation of massive stars in the radio domain revealed about 25 years ago that some of them are synchrotron emitters, showing that these objects are able to accelerate particles up to ... [more ▼]

The investigation of massive stars in the radio domain revealed about 25 years ago that some of them are synchrotron emitters, showing that these objects are able to accelerate particles up to relativistic velocities. In this context, non-thermal emission processes such as inverse Compton scattering are expected to be at work in the high-energy domain. For this reason, an observational campaign devoted to the X-ray investigation of non-thermal radio emitters has been carried out with XMM-Newton. However, considering the rather strong thermal X-ray emission from these systems below 10 keV, XMM-Newton does not appear to be the ideal observatory to detect their putative non-thermal X-rays. As a consequence, the advent of next generation X-ray observatories with a bandpass extending significantly above 10 keV (SIMBOL-X, XEUS, NEXT) is expected to provide important results related to the non-thermal high-energy emission from colliding-wind binaries and their capability to accelerate particles. [less ▲]

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See detailLes troubles de la marche de la personne agee
Warzee, Emmanuelle ULg; Petermans, Jean ULg

in Revue Médicale de Liège (2007), 62(12), 713-8

Falls are frequent in the elderly and are responsible for an increased morbi-mortality. The elderly who has a tendency to fall is at higher risk of repeated hospitalisation and of institutionalisation. A ... [more ▼]

Falls are frequent in the elderly and are responsible for an increased morbi-mortality. The elderly who has a tendency to fall is at higher risk of repeated hospitalisation and of institutionalisation. A link between cognitive and gait disorders is put forward by several recent studies. This paper is concerned with the various gait abnormalities encountered in the elderly, especially seriale gait, and the means to detect them. [less ▲]

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See detailLe cas clinique du mois. Aspergillose pulmonaire: un cas d'aspergillose necrosante chronique
Golinval, Olivier ULg; Louis, Renaud ULg

in Revue Médicale de Liège (2007), 62(12), 704-6

Pulmonary aspergillosis are uncommon diseases. The clinical expression of which are depending on the immunological status. The spectrum of pulmonary aspergillosis goes from hypersensitization to the ... [more ▼]

Pulmonary aspergillosis are uncommon diseases. The clinical expression of which are depending on the immunological status. The spectrum of pulmonary aspergillosis goes from hypersensitization to the invasive and disseminated aspergillosis. We report here the clinical history of a patient with severe COPD and receiving regular oral corticoids who had a persistent lung infiltration. The infiltration became cavitary and proved to be a chronic necrotizing pneumonia due to Aspegillus fumigatus. The outcome was favourable thank to a treatment with voriconazole. [less ▲]

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See detailModel of electrostatic actuated deformable mirror using strongly coupled electro-mechanical finite element
Rochus, Véronique ULg; Golinval, Jean-Claude ULg; Mendez, C. et al

in Analog Integrated Circuits and Signal Processing (2007), 53(2-3), 129-135

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well ... [more ▼]

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well as mechanical and fluid phenomena appear and interact. Because of their microscopic scale, strong coupling effects arise between the different physical fields, and some forces, which were negligible at macroscopic scale, have to be taken into account. In order to accurately design such micro-electro-mechanical systems, it is of primary importance to be able to handle the strong coupling between the electric and the mechanical fields. In this paper, the finite element method (FEM) is used to model the strong coupled electro-mechanical interactions and to perform static and transient analyses taking into account large mesh displacements. These analyses will be used to study the behaviour of electrostatically actuated micro-mirrors. [less ▲]

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See detailNonlinear Aeroelastic vibrations and galloping of iced conductor lines under wind.
Shklyarchuk, Fedor; Danilin, Alexander; Lilien, Jean-Louis ULg et al

in Proceedings of the 7th International Conference on Cable Dynamics (2007, December)

galloping model for one span single conductor dead ended.

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See detailA kinematic model for hysteretic dissipation of vibration energy for torsional damper and detuner.
Danilin, Alexander; Vinogradov, Alexander; Lilien, Jean-Louis ULg

in Lilien, Jean-Louis (Ed.) Proceedings of the 7th International Conference on Cable Dynamics (2007, December)

A description of the damping properties and model of a low frequency damper for power lines galloping.

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See detailAutonomous rigid body attitude synchronization
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg; Leonard, Naomi

in Proceedings of the 46th IEEE Conference on Decision and Control (2007, December)

This paper studies some extensions to the decentralized attitude synchronization of identical rigid bodies. Considering fully actuated Euler equations, the communication links between the rigid bodies are ... [more ▼]

This paper studies some extensions to the decentralized attitude synchronization of identical rigid bodies. Considering fully actuated Euler equations, the communication links between the rigid bodies are limited and the available information is restricted to relative orientations and angular velocities. In particular, no leader nor external reference dictates the swarm's behavior. The control laws are derived using two classical approaches of nonlinear control - tracking and energy shaping. This leads to a comparison of two corresponding methods which are currently considered for distributed synchronization - consensus and stabilization of mechanical systems with symmetries. [less ▲]

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See detailIntussen aan de kersttafel...
Ozer, Pierre ULg; Perrin, Dominique ULg

Article for general public (2007)

De afgelopen weken heb ik de reclamefolders van mijn dichtstbijzijnde hypermarkt uitgeplozen om een fijn dineetje samen te stellen. Hierna volgt het resultaat voor acht personen, met tussen haakjes het ... [more ▼]

De afgelopen weken heb ik de reclamefolders van mijn dichtstbijzijnde hypermarkt uitgeplozen om een fijn dineetje samen te stellen. Hierna volgt het resultaat voor acht personen, met tussen haakjes het aantal kilometers dat elk ingrediënt heeft afgelegd om naar België te komen en de hoeveelheid CO2 in kilogram die het transport geproduceerd heeft. Ik heb vooral ingrediënten gekozen die met het vliegtuig worden aangevoerd, want luchttransport produceert gemiddeld zestig keer meer CO2 dan vervoer over zee. [less ▲]

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See detailNoël en famille ou 15 litres de pétrole
Ozer, Pierre ULg; Perrin, Dominique ULg

Article for general public (2007)

La semaine précédant Noël, j’ai décortiqué les publicités de mon hypermarché le plus proche pour préparer le repas familial tant attendu. Et voici ce que j’ai pu concocter pour huit personnes avec, entre ... [more ▼]

La semaine précédant Noël, j’ai décortiqué les publicités de mon hypermarché le plus proche pour préparer le repas familial tant attendu. Et voici ce que j’ai pu concocter pour huit personnes avec, entre parenthèses, les kilomètres parcourus entre le pays de production et la Belgique ainsi que les kilogrammes de CO2 émis uniquement pour le transport aérien intercontinental de ces produits achetés. L’analyse se focalise sur le transport par voie aérienne puisque celui-ci émet, en moyenne, 60 fois plus de CO2 que le transport par voie maritime. [less ▲]

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