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See detailGeneralized Shape And Topology Optimization: Recent Developments And Application Perspectives To Automotive Structures
Duysinx, Pierre ULg; Van Miegroet, Laurent ULg; Remouchamps, Alain et al

in New Advances in Body Engineering - Lightweight design, passive safety, pedestrian protection, and numerical optimization (2006, December)

More than 15 years after the seminal work by Bendsøe and Kikuchi, topology optimization of structures has taken advantage of my research efforts and has now become a commercial available tool (e.g ... [more ▼]

More than 15 years after the seminal work by Bendsøe and Kikuchi, topology optimization of structures has taken advantage of my research efforts and has now become a commercial available tool (e.g. OptiStruct by Altair, Topol by Samtech, etc.). These software tools are daily used in automotive industry and provide engineers with a rational tool for preliminary design of efficient structural components. This paper presents the status of available topology optimization tools and introduces the recent developments that extend their capabilities in order to handle stress constraints, manufacturing constraints, etc. The communication also presents a novel approach of generalized shape optimization that has been introduced to circumvent the difficulties of parametric shape optimization and to complement topology optimization. The approach is based on the eXtended Finite Element Method (XFEM) and the Level Set Description of the geometry. The Level Set description introduces smooth curve descriptions and allows modifying the connectivity of the wholes. The XFEM works with a fixed mesh as in topology optimization, which makes the method very convenient for engineers. Thus the novel approach is likely to bring the next future evolution of structural optimization. Impressive capabilities of this new generation approach will be demonstrated. Application examples from automotive and aerospace engineering will illustrate the different possibilities offered by two approaches. [less ▲]

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See detailTreating gliomas with glucocorticoids: from bedside to bench
Piette, Caroline ULg; Munaut, Carine ULg; Foidart, Jean-Michel ULg et al

in Acta Neuropathologica (2006), 112(6), 651-664

Glucocorticoids are used in the treatment of gliomas to decrease tumour-associated oedema and to reduce the risk of acute encephalopathy associated with radiotherapy. However, the mechanisms by which ... [more ▼]

Glucocorticoids are used in the treatment of gliomas to decrease tumour-associated oedema and to reduce the risk of acute encephalopathy associated with radiotherapy. However, the mechanisms by which glucocorticoids work are still largely unknown. In this paper, we survey the experimental and clinical evidence for the effects of glucocorticoids on tumour cell proliferation, apoptosis and sensitivity to chemotherapy, angiogenesis and vascular permeability. We then review current guidelines on the choice of molecule, dose and duration of glucocorticoid treatment for gliomas. [less ▲]

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See detailComment construire l'identité professionnelle dans les métiers de l'humain ?
Beckers, Jacqueline ULg; Jardon, Dorothée

in Puzzle (2006), 21

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See detailSound field modeling in architectural acoustics using a diffusion equation
Picaut, Judicaël; Valeau, Vincent; Billon, Alexis ULg et al

Conference (2006, December)

A numerical approach is proposed to model the reverberated sound field in rooms. The model is based on the numerical implementation of a diffusion model enabling spatial variations of the sound energy ... [more ▼]

A numerical approach is proposed to model the reverberated sound field in rooms. The model is based on the numerical implementation of a diffusion model enabling spatial variations of the sound energy within a room, unlike the statistical theory. The proposed method allows to take into account most of complex phenomena encountered in room acoustics, like mixed reflections on walls (diffuse and specular), low and high absorption on walls, atmospheric attenuation, fitted zones. Moreover, the model can be applied to complex geometries, like multiple coupled rooms of different sizes. In this paper, the model and its numerical implementation are first detailed. Then, an application is proposed for a complex geometry defined by multiple coupled rooms with fitting objects, including low and high absorption on walls, in terms of sound level and reverberation times. The main interest of the model is that such approach requires less computational time in comparison with common approaches like ray-tracing simulations. [less ▲]

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See detailEffect of timing of surgery on survival after preoperative hyperfractionated accelerated radiotherapy (HART) for locally advanced rectal cancer (LARC): Is it a matter of days?
Coucke, Philippe ULg; Notter, Markus; Matter, Maurice et al

in Acta Oncologica (2006), 45(8), 1086-1093

We intend to analyse retrospectively whether the time interval ("gap duration" = GD) between preoperative radiotherapy and surgery in locally advanced rectal cancer (LARC) has an impact on overall ... [more ▼]

We intend to analyse retrospectively whether the time interval ("gap duration" = GD) between preoperative radiotherapy and surgery in locally advanced rectal cancer (LARC) has an impact on overall survival (OS), cancer specific survival (CSS), disease free survival (DFS) and local control (LC). Two hundred seventy nine patients with LARC were entered in Trial 93-01 (hyperfractionated accelerated radiotherapy 41.6 Gy/26 Fx BID) shortly followed by surgery. From these 250 patients are fully assessable. The median GD of 5 days was used as a discriminator. The median follow-up for all patients was 39 months. GD > 5 days was a significant discriminator for actuarial 5-years OS (69% vs 47%, p = 0.002), CSS (82% vs 57%, p = 0.0007), DFS (62% vs 41%, p = 0.0003) but not for LC (93% vs 90%, p = non-significant). In multivariate analysis, the following factors independently predict outcome; for OS: age, GD, circumferential margin (CM) and nodal stage (ypN); for CSS: GD, ypN and vascular invasion (VI); for DFS: CEA, distance to anal verge, GD, ypN and VI; for LC: CM only. Gap duration predicts survival outcome but not local control. The patients submitted to surgery after a median delay of more than 5 days had a significantly better outcome. [less ▲]

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See detailPredictable disruption tolerant networks and delivery guarantees
François, Jean-Marc; Leduc, Guy ULg

Report (2006)

This article studies disruption tolerant networks (DTNs) where each node knows the probabilistic distribution of contacts with other nodes. It proposes a framework that allows one to formalize the ... [more ▼]

This article studies disruption tolerant networks (DTNs) where each node knows the probabilistic distribution of contacts with other nodes. It proposes a framework that allows one to formalize the behaviour of such a network. It generalizes extreme cases that have been studied before where (a) either nodes only know their contact frequency with each other or (b) they have a perfect knowledge of who meets who and when. This paper then gives an example of how this framework can be used; it shows how one can find a packet forwarding algorithm optimized to meet the 'delay/bandwidth consumption' trade-off: packets are duplicated so as to (statistically) guarantee a given delay or delivery probability, but not too much so as to reduce the bandwidth, energy, and memory consumption. [less ▲]

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See detailExperimental tests for the Babu-Zee two-loop model of Majorana neutrino masses
Aristizabal Sierra, Diego ULg; Hirsch, M.

in Journal of High Energy Physics [=JHEP] (2006), 0612

The smallness of the observed neutrino masses might have a radiative origin. Here we revisit a specific two-loop model of neutrino mass, independently proposed by Babu and Zee. We point out that current ... [more ▼]

The smallness of the observed neutrino masses might have a radiative origin. Here we revisit a specific two-loop model of neutrino mass, independently proposed by Babu and Zee. We point out that current constraints from neutrino data can be used to derive strict lower limits on the branching ratio of flavour changing charged lepton decays, such as μ→eγ. Non-observation of Br(μ→eγ) at the level of 10^(−13) would rule out singly charged scalar masses smaller than 590 GeV (5.04 TeV) in case of normal (inverse) neutrino mass hierarchy. Conversely, decay branching ratios of the non-standard scalars of the model can be fixed by the measured neutrino angles (and mass scale). Thus, if the scalars of the model are light enough to be produced at the LHC or ILC, measuring their decay properties would serve as a direct test of the model as the origin of neutrino masses. [less ▲]

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See detailTrou Al'Wesse, Belgium
Miller, Rebecca ULg; Stewart, John

in Mesolithic Miscellany (2006), 18(1), 2

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See detailFeedback Control of Impact Dynamics: the Bouncing Ball Revisited
Ronsse, Renaud; Sepulchre, Rodolphe ULg

in Proceedings of the 45th IEEE Conference on Decision and Control (2006, December)

We study the the design of a tracking controller for the popular bouncing ball model: the continuous-time actuation of a table is used to control the impacts of the table with a bouncing ball. The ... [more ▼]

We study the the design of a tracking controller for the popular bouncing ball model: the continuous-time actuation of a table is used to control the impacts of the table with a bouncing ball. The proposed control law uses the impact times as the sole feedback information. We show that the acceleration of the table at impact plays no role in the stability analysis but is an important parameter for the robustness of the feedback system to model uncertainty, in particular to the uncertainty on the coefficient of restitution. [less ▲]

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See detailNF-kappa B activation by reactive oxygen species: Fifteen years later
Gloire, Geoffrey ULg; Legrand-Poels, Sylvie ULg; Piette, Jacques ULg

in Biochemical Pharmacology (2006), 72(11), 1493-1505

The transcription factor NF-kappa B plays a major role in coordinating innate and adaptative immunity, cellular proliferation, apoptosis and development. Since the discovery in 1991 that NF-kappa B maybe ... [more ▼]

The transcription factor NF-kappa B plays a major role in coordinating innate and adaptative immunity, cellular proliferation, apoptosis and development. Since the discovery in 1991 that NF-kappa B maybe activated by H(2)o(2), several laboratories have put a considerable effort into dissecting the molecular mechanisms underlying this activation. Whereas early studies revealed an atypical mechanism of activation, leading to I kappa B alpha Y42 phosphorylation independently Of I kappa B kinase (IKK), recent findings suggest that H2O2 activates NF-kappa B mainly through the classical IKK-dependent pathway. The molecular mechanisms leading to IKK activation are, however, cell-type specific and will be presented here. In this review, we also describe the effect of other ROS (HOCl and O-1(2)) and reactive nitrogen species on NF-kappa B activation. Finally, we critically review the recent data highlighting the role of ROS in NF-kappa B activation by proinflammatory cytokines (TNF-alpha and IL-1 beta) and lipopolysaccharide (LPS), two major components of innate immunity. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

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See detailStructural and electrical properties of tellurovanadate glasses containing Li2O
Krins, Natasha ULg; Rulmont, André ULg; Grandjean, Jean ULg et al

in Solid State Ionics (2006), 177(35-36 Sp. Iss. SI), 3147-3150

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition ... [more ▼]

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition metal ions can present mixed ionic-electronic conductivity and are therefore potential candidates for application as cathode material in Li-ion batteries. The present work is devoted to the ternary system xLi(2)O-(1-x)[0.3V(2)O(5)-0.7TeO(2)] with 0 <= x <= 0.4. These compounds were prepared by heat treatment in air at 800 degrees C followed by traditional quenching. Raman spectroscopy and V-51 nuclear magnetic resonance measurements were performed in order to highlight the structural short range order modifications induced by the introduction of the Li2O network modifier. These structural effects can be related to the electrical behaviour, as studied by complex impedance spectroscopy measurements. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailPotentiation of cyclophosphamide chemotherapy using the anti-angiogenic drug thalidomide: Importance of optimal scheduling to exploit the ‘normalization’ window of the tumor vasculature
SEGERS, Jérôme; DI FAZIO, Vincent; ANSIAUX, Réginald et al

in Cancer Letters (2006), 244(1), 12935

The aim of this work was to study how administration schedule affects potentiation of cyclophosphamide, an alkylating agent, by thalidomide, an anti-angiogenic agent. Tumor oxygenation after thalidomide ... [more ▼]

The aim of this work was to study how administration schedule affects potentiation of cyclophosphamide, an alkylating agent, by thalidomide, an anti-angiogenic agent. Tumor oxygenation after thalidomide administration was determined over time by EPR oximetry. Such measurements provide a surrogate marker for determining the timing of ‘normalization’ of tumor vasculature. Re-growth delays were measured using different combinations and schedules of treatments. Additionally, the uptake of the metabolite of cyclophosphamide (hydroxycyclophosphamide or OH-CP) into tumors was determined by high performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A significant increase in pO2 was observed after 2 and 3 days of treatment before eventually declining on day 4. Thalidomide potentiated the effect of cyclophosphamide only when cyclophosphamide was administered after 2 days of treatment with thalidomide (no significant benefit using other schedules). In this time frame, the HPLC/MS/MS measurements showed that the quantity of OH-CP penetrating into the tumor was about twice in mice treated by thalidomide compared to controls. In conclusion, the present study demonstrates that the benefit of combined therapy using an anti-angiogenic agent with a cytotoxic agent requires knowledge of the time window during which the vessels initially become normalized. [less ▲]

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See detailInfluence de la température de séchage sur les propriétés physicochimiques des amidons de maïs
Malumba Kamba, Paul ULg; Deroanne, Claude; Masimango, Thaddée et al

in Kechaou (Ed.) Actes du Séminaire d'animation régionale sur les Technologies douces et les procédés de séparation au service de la qualité et de l'innocuité des aliments (2006, November 27)

Les amidons extraits des grains de maïs séchés aux températures de l’air comprises entre 54 et 130°C ont été caractérisés par Analyse Calorimétrique Différentielle (ACD), par granulométrie laser, par ... [more ▼]

Les amidons extraits des grains de maïs séchés aux températures de l’air comprises entre 54 et 130°C ont été caractérisés par Analyse Calorimétrique Différentielle (ACD), par granulométrie laser, par microscopie sous lumière polarisée et par diffraction des rayons-X. Il ressort de cette étude que le séchage aux températures élevées induit une modification des propriétés intrinsèques des amidons sans pour autant induire leur gélatinisation complète [less ▲]

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See detailInnovations pédagogiques et utiliation des NTIC dans le cadre de la formulation des aliments complets
Malumba Kamba, Paul ULg; Masimango, Thaddée

in Kechaou, Mohamed (Ed.) Actes du séminaire régional sur les Technologies douces et procédés de séparation au service de la qualité et de l'innocuité des aliments ’ (2006, November 27)

Des nombreuses approches d’optimisation des formulations ont été développées ces dernières années et commercialisées sous forme de logiciels dont les bases d’application restent méconnues de nombreux ... [more ▼]

Des nombreuses approches d’optimisation des formulations ont été développées ces dernières années et commercialisées sous forme de logiciels dont les bases d’application restent méconnues de nombreux praticiens. Dans la présente étude des fondements de la formulation conceptuelle des aliments utilisant les NTIC sont présentés et appliqués à un cas de formulation d’un aliment de croissance pour pondeuse. La validation de la formulation conceptuelle est obtenue grâce à l’analyse de la composition d’un aliment réel préparé suivant le modèle défini. Cet aliment est comparé avec un aliment équivalent de commerce [less ▲]

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See detailNatural and projectively equivariant quantizations
Radoux, Fabian ULg

Conference (2006, November 25)

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See detailQuantifications naturelles projectivement équivariantes
Radoux, Fabian ULg

Doctoral thesis (2006)

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See detailEtude en temps réel du processus d'extraction de la tagitinine C en fonction des caractéristiques physico-chimiques du CO2 supercritique à l'aide de fibres optiques couplant un spectrophotomètre IRTF à un extracteur à fluide supercritique
Ziemons, Eric ULg

Doctoral thesis (2006)

L’extraction par fluide supercritique fait partie des nouvelles techniques de préparation d’échantillons solides qui ont émergé au cours de ces dernières années. Elle constitue une alternative ... [more ▼]

L’extraction par fluide supercritique fait partie des nouvelles techniques de préparation d’échantillons solides qui ont émergé au cours de ces dernières années. Elle constitue une alternative intéressante aux techniques classiques d’extraction liquide-solide car le pouvoir solvant du fluide supercritique est ajustable, non seulement par la température, mais aussi par la pression. L’extraction par le CO2 supercritique de la tagitinine C, lactone sesquiterpénique photo sensible à l’activité anti-inflammatoire, anti-malarique et anticancéreuse à partir des parties aériennes de Tithonia diversifolia constituait une application intéressante de ce procédé et a été sélectionnée comme molécule cible dans le cadre de ce travail. Son optimisation a impliqué des dosages répétés de l’analyte dont la vibration d’élongation de la fonction diénone absorbe intensément à des fréquences particulières dans le domaine de l’infrarouge. Aussi, avons-nous tout d’abord développé et validé, dans la première partie de ce travail, une technique IRTF d’analyse en différé sélective, rapide, non destructrice et sensible fondée sur ses propriétés. Les différents paramètres (température, pression, quantité de CO2, granulométrie de l’échantillon) influençant le rendement d’extraction de l’analyte ont pu être étudiés à cette occasion. Dans les conditions optimales, nous avons montré que l’extraction par le CO2 supercritique extrayait rapidement et avec une meilleure sélectivité la tagitinine C tout en conservant un taux de récupération comparable aux techniques classiques d’extraction. Parallèlement à ces travaux et compte tenu de la photo-dégradation de la tagitinine C en tagitinine F, la formation de complexes d’inclusion avec la β, 2,6-di-O-méthyle-β et la γ-cyclodextrine a été investiguée. Différentes techniques ont été employées pour caractériser les complexes formés au niveau de la stœchiométrie, de la constante de formation et de la structure. Aucun effet photo-protecteur significatif n’a été démontré avec la β et la γ-cyclodextrine. En revanche, nous avons mis en évidence une diminution de la vitesse de la photo-dégradation en présence de la 2,6-di-O-méthyle-β-cyclodextrine. Malheureusement, celle-ci reste trop limitée pour envisager l’utilisation de cette cyclodextrine pour éviter la dégradation de la tagitinine C lors de son exposition à la lumière directe. Dans la dernière partie de notre travail, nous nous sommes plus particulièrement focalisés sur l’interfaçage EFSC/IRTF qui constituait un indéniable défi. Le développement de l’interfaçage a été réalisé à l’aide de fibres optiques en chalcogène d’arsenic entre un extracteur à fluide supercritique et un spectrophotomètre IR et a ainsi permis d’effectuer le dosage en ligne de la tagitinine C dans le CO2 supercritique après passage de celui-ci au travers d’une cartouche d’extraction contenant la matrice végétale. Par ailleurs, le développement de cet outil répond parfaitement aux nouvelles approches (Process and Analytical Technology) préconisées par la FDA. Le processus d’extraction de l’analyte a pu dès lors être étudié de manière approfondie et en temps réel en fonction des caractéristiques physico-chimiques du fluide supercritique et de la durée de l’extraction. L’utilisation de la vibration d’élongation CH comme marqueur a permis de mettre en évidence l’obtention d’extraits de composition variable qui pourront être utilisés directement dans des études d’efficacité thérapeutique. Enfin, la méthode d’extraction et de dosage en ligne de la tagitinine C a fait l’objet d’une validation poussée selon la nouvelle approche faisant appel aux profils d’exactitude dans un intervalle de dosage allant 500 à 2500 µg. Sur la base des différents profils d’exactitude obtenus, le modèle de régression linéaire a été choisi pour décrire la relation concentration-réponse. En effet, ce modèle présentait des valeurs de biais relatif inférieures à 2%, des valeurs de coefficient de variation ne dépassant pas 4% et des limites de tolérance comprises dans les limites d’acceptation de ±15% sur toute la gamme de concentration. De plus, le modèle de régression linéaire était en parfaite adéquation avec la méthode des ajouts dosés. [less ▲]

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