Last 7 days
Bookmark and Share    
Full Text
See detailSubspace and maximum likelihood identification of nonlinear mechanical systems
Noël, Jean-Philippe ULg; Schoukens, Johan; Kerschen, Gaëtan ULg

Conference (2014, March)

The present work focuses on a recent nonlinear generalisation of the existing (linear) frequency-domain, discrete-time subspace methods applicable to mechanical systems. The proposed estimator, termed ... [more ▼]

The present work focuses on a recent nonlinear generalisation of the existing (linear) frequency-domain, discrete-time subspace methods applicable to mechanical systems. The proposed estimator, termed FNSI method, is interesting because it benefits from the numerical robustness and efficacy of subspace algorithms, while maintaining an acceptable computational burden. However, it derives estimates of the model parameters, namely the modal properties of the underlying linear system and the coefficients of the nonlinearities, based on deterministic arguments and one has thus no guarantee that the estimates still behave well in the presence of disturbing noise. A possible alternative is to embed the identification problem in a stochastic framework through the minimisation of a well-chosen cost function incorporating noise information. In particular, the maximum likelihood cost function is attractive because it yields estimates of the model parameters with optimal stochastic properties, and simplifies to a weighted least-squares expression in the frequency domain. However, the maximum likelihood suffers from issues typically encountered in optimisation problems, especially related to initialisation. The contribution of this work lies in the utilisation of the model parameter estimates provided by the FNSI method to serve as starting values for the minimisation of the maximum likelihood cost function. This initialisation strategy possesses the important advantage that the FNSI method generates a fully nonlinear model of the system under test, while classical approaches commonly use a linear model of the nonlinear system as starting point. This ensures that the resulting maximum likelihood model performs at least as good as the nonlinear subspace model. The complete methodology is demonstrated using experimental data measured on the Silverbox benchmark, an electronic circuit emulating the behaviour of a mechanical system with cubic nonlinearity. [less ▲]

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailEpidemiological tools for effective surveillance of porcine cysticercosis in Africa
Goussanou, J.S.E; Kpodekon, M.T.; Youssao, A.K.I. et al

in Veterinary World (2014), 7(3), 125-134

Detailed reference viewed: 12 (1 ULg)
Full Text
Peer Reviewed
See detailTGF-B induced protein IG-H3 is essential for the growth of human liver metastases
Castronovo, Vincenzo ULg; Blomme, Arnaud; Delvenne, Philippe ULg et al

in Acta Gastro-Enterologica Belgica (2014, March), 77(1), 05

Detailed reference viewed: 10 (2 ULg)
Full Text
Peer Reviewed
See detailOrganized proteomic heterogeneity in colorectal liver metastases and implications for therapies
Turtoi, Andrei ULg; Blomme, A; Debois, Delphine ULg et al

in Acta Gastro-Enterologica Belgica (2014, March), 77(1), 07

Detailed reference viewed: 7 (1 ULg)
Full Text
See detailLaTeX, un peu, beaucoup (3. Le béhaba)
Dupont, Pascal ULg

in Losanges (2014)

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailThe Ultraviolet Spectrograph on NASA’s Juno Mission
Gladstone, G Randal; Persyn, Steven C.; Eterno, John S. et al

in Space Science Reviews (2014)

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These ... [more ▼]

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS. [less ▲]

Detailed reference viewed: 29 (6 ULg)
Full Text
Peer Reviewed
See detailClimatological study of ionospheric irregularities over the European mid-latitude sector with GPS
Wautelet, Gilles ULg; Warnant, René ULg

in Journal of Geodesy (2014), 88(3), 223-240

High-frequency variability of the ionosphere, or irregularities, constitutes the main threat for real-time precise positioning techniques based on Global Navigation Satellite Systems (GNSS) measurements ... [more ▼]

High-frequency variability of the ionosphere, or irregularities, constitutes the main threat for real-time precise positioning techniques based on Global Navigation Satellite Systems (GNSS) measurements. Indeed, during periods of enhanced ionospheric variability, GNSS users in the field – who cannot verify the integrity of their measurements – will experience positioning errors that can reach several decimeters, while the nominal accuracy of the technique is cm-level. In the frame of this paper, a climatological analysis of irregularities over the European mid-latitude region is presented. Based on a ten year GPS dataset over Belgium, the work analyzes the occurrence rate (as a function of the solar cycle, season and local time) as well as the amplitude of ionospheric irregularities observed at a single GPS station. The study covers irregularities either due to space weather events (solar origin) or of terrestrial origin. If space weather irregularities are responsible for the largest effects in terms of ionospheric error, their occurrence rate highly depends on solar activity. Indeed, the occurrence rate of ionospheric irregularities is about 9% during solar maximum, whereas it drops to about 0% during medium or low solar activity periods. Medium-Scale Ionospheric Disturbances (MSTIDs) occurring during daytime in autumn/winter are the most recurrent pattern of the time series, with yearly proportions slightly varying with the solar cycle and an amplitude of about 10% of the TEC background. Another recurrent irregularity type, though less frequent than MSTIDs, is the noise-like variability in TEC observed during summer nighttime, under quiet geomagnetic conditions. These summer nighttime irregularities exhibit amplitudes ranging between 8 and 15% of the TEC background. [less ▲]

Detailed reference viewed: 48 (12 ULg)
Full Text
Peer Reviewed
See detailPrecision design of ethylene- and polar-monomer-based copolymers by organometallic-mediated radical polymerization
Kermagoret, Anthony ULg; Debuigne, Antoine ULg; Jérôme, Christine ULg et al

in Nature Chemistry (2014), 6(3), 179-187

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry ... [more ▼]

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry, free-radical polymerization is used to make a large proportion of such copolymers, but the forcing conditions result in a lack of fine control over the architecture of the products. Herein we introduce a synthetic tool, effective under mild experimental conditions, for the precision design of unprecedented ethylene- and polar-monomer-based copolymers. We demonstrate how an organocobalt species can control the growth of the copolymer chains, their composition and the monomer distribution throughout the chain. By fine tuning the ethylene pressure during polymerization and by exploiting a unique reactive mode of the end of the organometallic chain, novel block-like copolymer structures can be prepared. This highly versatile synthetic platform provides access to a diverse range of polymer materials. [less ▲]

Detailed reference viewed: 70 (18 ULg)
Full Text
See detailL'ENMG…C'est le pied
WANG, François-Charles ULg

in Neurologies (2014), 17(166), 108-113

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailOARSI guidelines for the non-surgical management of knee osteoarthritis
McAlindon; Henrotin, Yves ULg

in Osteoarthritis and Cartilage (2014), 22(3), 363-388

This paper presents concise, up-to-date, patient-focused, evidence-based, expert consensus guidelines for the management of knee osteoarthritis, intended to inform patients, physicians and allied ... [more ▼]

This paper presents concise, up-to-date, patient-focused, evidence-based, expert consensus guidelines for the management of knee osteoarthritis, intended to inform patients, physicians and allied healthcare professionnal worlwide. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
See detailLa touche germanophone
Grandjean, Geoffrey ULg

Article for general public (2014)

Detailed reference viewed: 23 (2 ULg)
Full Text
See detailStudy of the multi-decadal evolution of the Black Sea hydrodynamics and biogeochemistry using mathematical modelling
Capet, Arthur ULg

Doctoral thesis (2014)

This thesis addresses the biogeochemical cycles in the Black Sea (BS) during the shifting environmental context that affected the BS during the last decades of the 20th century. The study is based on ... [more ▼]

This thesis addresses the biogeochemical cycles in the Black Sea (BS) during the shifting environmental context that affected the BS during the last decades of the 20th century. The study is based on sophisticated data analysis tools and on the development and implementation of a coupled 3D biogeochemical model on the BS domain. The long term variability of the BS hydrodynamical structure was first examined on the basis of in-situ profiles (1950-2012), satellite imagery (1985-2000) and 3D modelling (1960-2000). Profiles of temperature and salinity were used to derive vertical characteristics of the BS structure: the mixed layer depth and the cold content of the Cold Intermediate Layer. To untangle the spatial and temporal trends from this heterogeneous dataset, a general methodology was proposed and embedded in the data analysis software DIVA. The detrended climatologies and long-term time series provided by this approach were used to assess statistical relationships with local atmospheric conditions. Satellite data (sea surface temperature and altimetry) and model results were then analyzed to relate observable surface dynamics to internal hydrodynamic properties. The main multivariate modes of variability of the BS hydrodynamic structure were highlighted on the basis of Empirical Orthogonal Function analysis. Their temporal evolution was explained by the occurrences of specific atmospheric patterns, identified on the basis of neural algorithm analysis and related to the phases of well known teleconnection systems (i.e. the North Atlantic and East Asia/West Russia oscillations). To study the dynamics of eutrophication in the shallow Black Sea NorthWestern Shelf (BS-NWS), a benthic model component was developed that considers the environmental control on diagenetic processes and the bottom shear stress restriction on organic matter deposition. The model accurately reproduced the seasonal and spatial variability depicted by in-situ estimates of benthic nutrients and oxygen fluxes in the BS-NWS. Outputs were used to review the role of the benthic component in BS biogeochemical cycles. The multi-decadal simulations, enabled by the low computational requirements of the benthic-pelagic coupling approach, revealed an inertial component in the dynamics of eutrophication resulting from the accumulation of organic matter during the years of important nutrient loads. This refined resolution of the BS-NWS biogeochemistry allowed us to study the phenomenon of seasonal hypoxia, which is believed to have played a part in the sudden collapse of the fisheries stocks in the late 80s. An index H, combining the spatial and temporal extension of the seasonal hypoxic event, was proposed to quantify the annual intensity of hypoxia as a pressure on benthic communities. We have shown that hypoxia was first triggered in the late 70s by high nitrogen loads, and sustained by sedimentary organic matter accumulation after a rapid reduction of these loads in the 90s. After 2000, warmer summers again led to a increase of the H-index, by entraining hypoxic events of smaller spatial extension but increased duration. A practical relationship distinguishing the impacts of eutrophication and climatic drivers was proposed to assess the effect of their projected values on the future intensity of hypoxia. [less ▲]

Detailed reference viewed: 48 (26 ULg)
Full Text
Peer Reviewed
See detailLes éléments de preuve recueillis à l'étranger : essai de synthèse
Michiels, Olivier ULg; Falque, Géraldine ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2014), 2014/9

L’origine des preuves provenant de l’étranger sont aussi diverses que variées. Pensons, par exemple, aux éléments probatoires obtenus à la suite d’une demande d’entraide judiciaire, aux preuves issues ... [more ▼]

L’origine des preuves provenant de l’étranger sont aussi diverses que variées. Pensons, par exemple, aux éléments probatoires obtenus à la suite d’une demande d’entraide judiciaire, aux preuves issues d’une enquête pénale menée dans un pays tiers ou encore aux preuves recueillies à l’étranger par les autorités nationales dans le cadre de leurs interventions transfrontalières . L’examen concret de la régularité de ces éléments probatoires soumis au juge national méritait que l’on s’y attarde. En effet, les traités d’entraide ne prévoient généralement pas la manière dont ces preuves étrangères doivent être contrôlées et, le cas échéant, sanctionnées. Aussi, ce sont la jurisprudence et le législateur nationaux qui se sont efforcés, au fil du temps, de poser des critères clairs en la matière . L’arrêt commenté se situe dans la droite ligne de cette problématique et a donné l’occasion aux auteurs de rappeler les quelques règles qui s’imposent en la matière. Après un bref résumé des faits de la cause, et avant d’envisager la question de la preuve recueillie à l’étranger à proprement parler, les auteurs ont égalemnet entrepris de faire un rapide détour par les principes qui régissent la preuve récoltée en Belgique. [less ▲]

Detailed reference viewed: 24 (4 ULg)
See detailLe schizophrène : du paradoxe évolutionniste à la psychopathologie éthologique
Englebert, Jérôme ULg

Conference (2014, February 28)

Detailed reference viewed: 42 (2 ULg)
See detailTextes, images, monuments. L'Histoire mise en troubles par le document visuel.
Servais, Amandine ULg

Scientific conference (2014, February 28)

La journée d’études « Logiques iconiques » invitait à réfléchir sur la manière dont le voir informe le savoir. Afin d’apporter des éléments de réponse depuis la discipline qui est la mienne, l’Histoire ... [more ▼]

La journée d’études « Logiques iconiques » invitait à réfléchir sur la manière dont le voir informe le savoir. Afin d’apporter des éléments de réponse depuis la discipline qui est la mienne, l’Histoire, je me suis livrée à l’étude d’un cas : Alphonse Dupront (particulièrement la centaine de pages consacrées aux images dans « Itinéraire », 1ère partie de l’ouvrage Du sacré. Croisades et pèlerinages. Images et langages). En raison de son excentricité, ce médiéviste a retenu mon attention. N’est-ce pas depuis les marges qu’on peut, le mieux, examiner le centre ? Contrairement à ce qu’on observe aujourd’hui dans la plupart des travaux historiens, Dupront ne produit pas, sur les images, un discours en surplomb ni un texte où l’image est prétextuelle. Il réalise une expérience : son texte est à la fois le lieu d’une pratique et l’endroit où se réfléchit cette pratique. Le récit de Dupront constitue un métadiscours et c’est par l’image que le récit historien est contraint de s’engager dans l’autoréflexivité. Chez Dupront, les catégories du temps et de l’image sont étroitement intriquées. Cette intrication des catégories vient de ce que la définition du temps (longue durée) engendre une conception de l’événement (le vécu qu’étudie l’historien) s’accordant à une certaine définition de l’image (l’image entendue comme agrégat d’hétérogènes et, par-là, possédant un potentiel d’actualisation). Dès lors, événement et image partagent une même propriété, celle d’être actualisables. Cette contiguïté catégorielle fonde le système dupronien. En cela, l’image occupe une place prépondérante ; elle détermine des modalités inédites du savoir historique. Grâce au travail de Dupront, nous constatons que l’image questionne le dispositif historien dans son ensemble. 1) Dans l’ordre des sources historiques, l’image remet en question la primauté du texte. 2) Et, par sa nature, elle trouble la distinction opérée entre document et monument. 3) Agrégat d’éléments hétérogènes, l’image échappe à un traitement linéaire. Elle souligne la relativité de la périodisation traditionnelle ; elle bouleverse l’ordre des factualités. Elle suscite alors un récit-limite. 4) Elle permet de renouveler des questionnements de grande envergure en matière d’interdisciplinarité et d’interprétation en Histoire. Bien sûr, l’image entendue comme lieu d’interrogation de l’historiographie et comme détermination de modalités inédites du savoir historien est une hypothèse à éprouver. Mais commençant par tirer sur le fil Dupront, je suis persuadée de pouvoir, peu à peu, délier certains nœuds de l’écriture contemporaine de l’Histoire. La marge où se tient Dupront révèle quelque chose de fort qui œuvre au sein de la pratique. Plus que d’offrir une simple évasion, la réalisation dupronienne nous place au cœur du problème. [less ▲]

Detailed reference viewed: 24 (10 ULg)
Full Text
Peer Reviewed
See detailChitosan nanoparticles for siRNA delivery: Optimizing formulation to increase stability and efficiency
Ragelle, Héloïse; Riva, Raphaël ULg; Vandermeulen, G. et al

in Journal of Controlled Release (2014), 176

This study aims at developing chitosan-based nanoparticles suitable for an intravenous administration of small interfering RNA (siRNA) able to achieve (i) high gene silencing without cytotoxicity and (ii ... [more ▼]

This study aims at developing chitosan-based nanoparticles suitable for an intravenous administration of small interfering RNA (siRNA) able to achieve (i) high gene silencing without cytotoxicity and (ii) stability in biological media including blood. Therefore, the influence of chitosan/tripolyphosphate ratio, chitosan physicochemical properties, PEGylation of chitosan as well as the addition of an endosomal disrupting agent and a negatively charged polymer was assessed. The gene silencing activity and cytotoxicity were evaluated on B16 melanoma cells expressing luciferase. We monitored the integrity and the size behavior of siRNA nanoparticles in human plasma using fluorescence fluctuation spectroscopy and single particle tracking respectively. The presence of PEGylated chitosan and poly(ethylene imine) was essential for high levels of gene silencing in vitro. Chitosan nanoparticles immediately released siRNA in plasma while the inclusion of hyaluronic acid and high amount of poly(ethylene glycol) in the formulation improved the stability of the particles. The developed formulations of PEGylated chitosan-based nanoparticles that achieve high gene silencing in vitro, low cytotoxicity and high stability in plasma could be promising for intravenous delivery of siRNA. [less ▲]

Detailed reference viewed: 16 (5 ULg)
Full Text
See detailSCC-Optimiser la pertinence du parcours patient
WANG, François-Charles ULg

Conference (2014, February 28)

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailGlucose-, pH- and thermo-responsive nanogels crosslinked by functional superparamagnetic maghemite nanoparticles as innovative drug delivery systems
Liu, Ji ULg; Detrembleur, Christophe ULg; Debuigne, Antoine ULg et al

in Journal of Materials Chemistry B (2014), 2(8), 1009-1023

Reversibly crosslinked (RCL) nanogels made of thermo-responsive poly(vinyl alcohol)-b-poly(Nvinylcaprolactam) copolymers were combined with maghemite nanoparticles and developed as new drug delivery ... [more ▼]

Reversibly crosslinked (RCL) nanogels made of thermo-responsive poly(vinyl alcohol)-b-poly(Nvinylcaprolactam) copolymers were combined with maghemite nanoparticles and developed as new drug delivery systems (DDS). The crosslinking was formed via boronate/diol bonding from the surfacefunctionalized superparamagnetic maghemite nanoparticles, endowing the DDS with thermo-, pH- and glucose-responsiveness. The capability to load a hydrophobic drug model Nile red (NR) within the RCL nanogels was evaluated, and stimuli-triggered drug release behaviours under different conditions were tested. Zero premature release behaviour was detected at physiological pH in the absence of glucose, whereas triggered release was observed upon exposure to acidic pH (5.0) and/or in the presence of glucose. In light of the superparamagnetic properties of the maghemite nanoparticles and RCL nanogels, magnetically-induced heating, MR imaging performance, as well as remotely magnetically-triggered drug release under alternating magnetic field (AMF), were investigated. Cytotoxicity against fibroblast-like L929 and human melanoma MEL-5 cell lines was assessed via the MTS assay. In vitro stimuli-triggered release of tamoxifen, a chemotherapeutic drug, was also studied within MEL-5 cell cultures under different conditions. These innovative RCL nanogels, integrating different stimuli-responsive components, hydrophobic chemotherapeutic moieties and also diagnostic agents together via reversible crosslinking, are promising new theranostic platforms. [less ▲]

Detailed reference viewed: 39 (14 ULg)