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See detailEncourager un vieillissement cognitif sain par un travail adapté (work shop)
Grotz, Catherine ULg; Adam, Stéphane ULg

Conference (2015, February 12)

L'objectif du workshop est d'apporter des éléments pratiques/cliniques en faveur d'un vieillissement cognitif de qualité, y compris une discussion des mesures à mettre en place en ce qui concerne l ... [more ▼]

L'objectif du workshop est d'apporter des éléments pratiques/cliniques en faveur d'un vieillissement cognitif de qualité, y compris une discussion des mesures à mettre en place en ce qui concerne l'employabilité de la population active plus âgée. [less ▲]

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See detailAn Alternative to Semantics?
Gauvry, Charlotte ULg

Conference (2015, February 12)

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See detailRisk of emergence of a hyperpathogenic bovine leukemia virus by mutation of a single envelope N-linked glycosylation site
De Brogniez, Alix ULg; Bouzar, Amel-Baya; Jacques, Jean-Rock ULg et al

Poster (2015, February 11)

- Introduction : Pathogens have co-evolved with their host to ensure efficient replication and transmission without inducing excessive pathogenicity that would indirectly impair their persistence. This is ... [more ▼]

- Introduction : Pathogens have co-evolved with their host to ensure efficient replication and transmission without inducing excessive pathogenicity that would indirectly impair their persistence. This is exemplified by the bovine leukemia virus (BLV) system in which lymphoproliferative disorders develop in ruminants after latency periods of several years. Infection of sheep and cattle with BLV is a model system for the related human T-lymphotropic virus type 1 (HTLV-1) responsible for Adult T-cell Leukemia (ATL). - Aims : The goal of this work is to investigate the role of N-glycans of the viral envelope protein during viral replication and pathogenesis. - Methods and results : Using glycosylation inhibitors and lectins, we showed that N-glycosylation is involved in viral infection (i.e. cell-to-cell fusion). Using reverse genetics of an infectious molecular provirus, we next demonstrated that a particular N-linked envelope glycosylation site (N230) limits viral replication and pathogenicity in vitro and in vivo. We have thus generated a viral mutant that is more pathogenic than the wild type strain. - Conclusions : To our knowledge, this is the first time that a hyperpathogenic BLV has been identified. This unexpected observation has important consequences in terms of disease control and managing. Indeed, during evolution, pathogens and their hosts should achieve an equilibrium allowing the coexistence of the two species. Occurrence of this particular mutation may thus represent a potential threat associated with emergence of hyperpathogenic BLV strains and possibly of new variants of the related HTLV-1. [less ▲]

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See detailQuand la clinique bouscule les concepts
Englebert, Jérôme ULg

Scientific conference (2015, February 11)

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See detailLa pérennisation des partenariats publics-privés dans le champ de l’emploi : entre application, interprétation et ajustement du cadre réglementaire
Remy, Céline ULg; Gérard, Julie ULg; Beuker, Laura ULg

Conference (2015, February 07)

Dans une perspective de gestion mixte du marché du travail, les services publics de l’emploi sont invités, par la Convention 181 de l’OIT de 1997, à déléguer et à confier l’exploitation et la gestion de ... [more ▼]

Dans une perspective de gestion mixte du marché du travail, les services publics de l’emploi sont invités, par la Convention 181 de l’OIT de 1997, à déléguer et à confier l’exploitation et la gestion de leurs activités à des opérateurs privés de service, dans le cadre d’une entente contractuelle. Alors que les modalités de la collaboration (telles que le public-cible, le type et le nombre d’accompagnements dispensés, les résultats à atteindre, etc.) sont fixées, initialement, par les services publics de l’emploi, elles sont ensuite mises en pratique par les diverses parties-prenantes du partenariat. Les acteurs publics et privés exploitent la part de latitude inhérente à leur fonction pour interpréter et ajuster les termes du contrat ou pour pouvoir réaliser leur mission d’accompagnement des demandeurs d’emploi. Partant du postulat que la règle est incomplète, notre objectif est d’analyser la mise en œuvre du partenariat en saisissant les arguments avancés par les acteurs pour justifier et légitimer leurs actions. À partir de cette analyse, nous montrerons que les acteurs du partenariat doivent interpréter les règles – écart entre le travail prescrit et le travail effectivement presté – dans leurs pratiques quotidiennes. Agissant comme des « pseudo » street-level bureaucrats, ces derniers usent de leur pouvoir pour ajuster les règles. En outre, il semblerait que ces pratiques d'indiscipline permettent, en réalité, de maintenir les relations partenariales entre services publics de l’emploi et opérateurs privés, et d’œuvrer, in fine, à la pérennisation de celles-ci dans le champ de l’emploi. Nous appuierons notre analyse sur un matériau empirique composé d’observations participantes et d’entretiens semi-directifs réalisés auprès des parties-prenantes des PPP, situés en Belgique francophone. [less ▲]

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See detailComprendre les programmes électoraux : comparaison des méthodes d’encodage manuel et automatique
Piet, Grégory ULg; Dandoy, Régis; Joly, Jeroen

Conference (2015, February 06)

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See detailLo “stratega” delle immagini. Cosimo I de’ Medici e gli artisti della Firenze ducale
Geremicca, Antonio ULg

Conference given outside the academic context (2015)

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See detailSuppression of Limit Cycle Oscillations using the Nonlinear Tuned Vibration Absorber
Habib, Giuseppe ULg; Kerschen, Gaëtan ULg

in Proceeding IMAC XXXIII A Conference and Exposition on Structural Dynamics, Orlando 2-5 February 2015 (2015, February 03)

The objective of the present study is to mitigate, or even completely eliminate, the limit cycle oscillations in mechanical systems using a passive nonlinear absorber, termed the nonlinear tuned vibration ... [more ▼]

The objective of the present study is to mitigate, or even completely eliminate, the limit cycle oscillations in mechanical systems using a passive nonlinear absorber, termed the nonlinear tuned vibration absorber (NLTVA). An unconventional aspect of the NLTVA is that the mathematical form of its restoring force is not imposed a priori, as it is the case for most existing nonlinear absorbers. The NLTVA parameters are determined analytically using stability and bifurcation analyses, and the resulting design is validated numerically using the MATCONT software. The proposed developments are illustrated using a Van der Pol-Du ng primary system. [less ▲]

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See detailEconomics of a decision-support system for managing the main fungal diseases of winter wheat in the Grand-Duchy of Luxembourg
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

in Field Crops Research (2015), 172(2), 32-41

We evaluated the cost effectiveness of a decision-support system (DSS) developed for assessing in real time the risk of progression of the main fungal diseases (i.e., Septoria leaf blotch, powdery mildew ... [more ▼]

We evaluated the cost effectiveness of a decision-support system (DSS) developed for assessing in real time the risk of progression of the main fungal diseases (i.e., Septoria leaf blotch, powdery mildew, leaf rusts and Fusarium head blight) of winter wheat in the Grand-Duchy of Luxembourg (GDL). The study was conducted in replicated field experiments located in four agricultural locations (representative of the main agro-ecological regions of the country) over a 10-year period (2003-2012). Three fungicide spray strategies were compared: a single DSS-based system and two commonly used spray practices in the GDL, a double- (2T)- and a triple- spray (3T) spray treatment; there was also a non-treated control. In years with a high disease pressure, the DSS-based recommendation resulted in protection of the three upper leaves comparable to that achieved with the 2T and 3T treatments, with significant grain yield increases (P > 0.05) compared to the control (a 4 to 42% increase, depending on the site and year). Overall, the financial gain in treated plots compared with the control ranged from 3 to 16% at the study sites. Furthermore, in seasons when dry weather conditions precluded epidemic development, no the DSS-basedDSS recommended no fungicide spray was recommended, reducing use of fungicide, and thus saving the cost of the product. The gain in yield for the 2T and 3T plots (compared with control) did not necessarily result in a financial gain during the duration of the experiment. This study demonstrates the potential advantages and profitability of using a DSS -based approach for disease management. [less ▲]

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See detailA comparison between visual estimates and image analysis measurements to determine Septoria leaf blotch severity in winter wheat
El Jarroudi, Moussa ULg; Kouadio, Louis; Mackels, Christophe et al

in Plant Pathology (2015)

Methods to estimate disease severity vary in accuracy, reliability, ease of use and cost. Severity of Septoria leaf blotch (SLB, caused by Zymoseptoria graminicola) was estimated by four raters and by ... [more ▼]

Methods to estimate disease severity vary in accuracy, reliability, ease of use and cost. Severity of Septoria leaf blotch (SLB, caused by Zymoseptoria graminicola) was estimated by four raters and by image analysis (assumed actual values) on individual leaves of winter wheat in order to explore accuracy and reliability of estimates, and to ascertain whether there were any general characteristics of error. Specifically, (i) we determined the accuracy and reliability of visual assessments of SLB over the full range of severity from 0 to 100%, and we investigated (ii) whether certain 10% ranges in actual disease severity between 0 and 100% were more prone to estimation error compared with others, and (iii) whether leaf position affected accuracy within those ranges. Lin's concordance correlation analysis of all severities (0 to 100%) demonstrated that all raters had estimates close to the actual values (agreement: ρc = 0.92-0.99). However, agreement between actual SLB severities and estimates by raters was less good when compared over short 10% subdivisions within the 0-100% range (ρc = -0.12 to 0.99). Despite common rater imprecision at estimating low and high SLB severities, individual raters differed considerably in their accuracy over the short 10% subdivisions. There was no effect of leaf position on accuracy or precision of severity estimate on separate leaves (L1-L3). Pursuing efforts in understanding error in disease estimation should aid in improving the accuracy of assessments, making visual estimates of disease severity more useful for research and applied purposes. [less ▲]

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See detailA Review of Pharmaceutical Extrusion: Critical Process Parameters and Scaling-up
Thiry, Justine ULg; Krier, Fabrice ULg; Evrard, Brigitte ULg

in International Journal of Pharmaceutics (2015), 479(1), 227-240

Hot melt extrusion has been a widely used process in the pharmaceutical area for three decades. In this field, it is important to optimize the formulation in order to meet specific requirements. However ... [more ▼]

Hot melt extrusion has been a widely used process in the pharmaceutical area for three decades. In this field, it is important to optimize the formulation in order to meet specific requirements. However, the process parameters of the extruder should be as much investigated as the formulation since they have a major impact on the final product characteristics. Moreover, a design space should be defined in order to obtain the expected product within the defined limits. This gives some freedom to operate as long as the processing parameters stay within the limits of the design space. Those limits can be investigated by varying randomly the process parameters but it is recommended to use design of experiments. An examination of the literature is reported in this review to summarize the impact of the variation of the process parameters on the final product properties. Indeed, the homogeneity of the mixing, the state of the drug (crystalline or amorphous), the dissolution rate, the residence time, can be influenced by variations in the process parameters. In particular, the impact of the following process parameters: temperature, screw design, screw speed and feeding, on the final product, has been reviewed. [less ▲]

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See detailSelf-assembly of a triblock terpolymer mediated by hydrogen-bonded complexes
Guerlain, Claire; Piogé, Sandie; Detrembleur, Christophe ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2015), 53(3), 459-467

A poly(methyl methacrylate)-block-poly(4-vinylpyridine)-block-polystyrene (PMMA-b-P4VP-b-PS) triblock terpolymer is synthesized by ATRP to study its self-assembly with PAA in organic solvents. The self ... [more ▼]

A poly(methyl methacrylate)-block-poly(4-vinylpyridine)-block-polystyrene (PMMA-b-P4VP-b-PS) triblock terpolymer is synthesized by ATRP to study its self-assembly with PAA in organic solvents. The self-assembly behavior of this system is compared with the one of a mixture of two diblocks, namely polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and poly(methyl methacrylate)-block-poly(methacrylic acid) (PMMA-b-PMAA). For both systems, formation of hydrogen-bonded complexes between the P4VP and PMAA or PAA blocks occurs. These complexes become insoluble in the solvent used and micelles with a P4VP/P(M)AA complexes core surrounded by PS and PMMA coronal chains are obtained in both cases. These micelles are analyzed by DLS and TEM. Spherical micelles are formed for both systems but the hydrodynamic radii obtained for the two types of micelles are different. Indeed, the micelles formed by the PMMA-b-P4VP-b-PS + PAA system are smaller than those observed for the PS-b-P4VP + PMMA-b-PMAA system. Finally, the effect of the molar ratio of the P4VP/PMAA complexing blocks is investigated. [less ▲]

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See detailEffects of low dose endosulfan exposure on brain neurotransmitter levels in the African clawed frog Xenopus laevis
Preud'Homme, Valérie; Milla, Sylvain; Gillardin, Virginie et al

in Chemosphere (2015), 120(2), 357-364

Understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. Among pesticides, endosulfan belongs to one of the potential sources of danger because of ... [more ▼]

Understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. Among pesticides, endosulfan belongs to one of the potential sources of danger because of its wide use and known effects, particularly neurotoxic, on a variety of organisms. However, the effect of endosulfan was not yet evaluated on amphibians at levels encompassing simultaneously brain neurotransmitters and behavioural endpoints. In this context, tadpoles of the African clawed frog Xenopus laevis were submitted to four treatments during 27 d: one control, one ethanol control, and two low environmental concentrations of endosulfan (0.1 and 1 μg L−1). Endosulfan induced a significant increase of brain serotonin level at both concentrations and a significant increase of brain dopamine and GABA levels at the lower exposure but acetylcholinesterase activity was not modified by the treatment. The gene coding for the GABA transporter 1 was up-regulated in endosulfan contaminated tadpoles while the expression of other genes coding for the neurotransmitter receptors or for the enzymes involved in their metabolic pathways was not significantly modified by endosulfan exposure. Endosulfan also affected foraging, and locomotion in links with the results of the physiological assays, but no effects were seen on growth. These results show that low environmental concentrations of endosulfan can induce adverse responses in X. laevis tadpoles. At a broader perspective, this suggests that more research using and linking multiple markers should be used to understand the complex mode of action of pollutants. [less ▲]

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See detailAntoine Galland et l'épigraphie
Famerie, Etienne ULg

in Bauden, Frédéric; Waller, Richard (Eds.) Colloque international A. Galland (2015, February)

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See detailLa démocratie sous expertise. Médias, think tanks et privatisation du débat européen (en préparation, parution début 2015)
Geuens, Geoffrey ULg

Book published by Éditions du Croquant, collection "Savoir / Agir" (2015)

L’ouvrage questionne la genèse des think tanks eurofédéralistes participant à la fabrication et à la légitimation des politiques d’intégration, avant de s’intéresser à ces autres agents sociaux de ... [more ▼]

L’ouvrage questionne la genèse des think tanks eurofédéralistes participant à la fabrication et à la légitimation des politiques d’intégration, avant de s’intéresser à ces autres agents sociaux de production et de diffusion de la pensée européenne que sont notamment les correspondants bruxellois et éditorialistes de quelques grands médias européens. L’ouvrage montre combien le discours journalistique sur l’Europe et le discours de certains « spécialistes » des questions européennes, qui trouve aussi à s’exprimer dans l’espace médiatique, sont la plupart du temps limités à quelques expressions stéréotypées et argumentaires clichés s’expliquant autant par la position occupée dans le champ du pouvoir par les agents qui s’en font les relais que par les dispositions de ces mêmes agents sociaux à l’égard du « projet européen ». [less ▲]

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See detailExperimental modal analysis of nonlinear structures using broadband data
Noël, Jean-Philippe ULg; Renson, Ludovic ULg; Grappasonni, Chiara ULg et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXIII (2015, February)

The objective of the present paper is to develop a rigorous identification methodology of nonlinear normal modes (NNMs) of engineering structures. This is achieved by processing experimental measurements ... [more ▼]

The objective of the present paper is to develop a rigorous identification methodology of nonlinear normal modes (NNMs) of engineering structures. This is achieved by processing experimental measurements collected under broadband forcing. The use of such a type of forcing signal allows to excite multiple NNMs simultaneously and, in turn, to save testing time. A two-step methodology integrating nonlinear system identification and numerical continuation of periodic solutions is proposed for the extraction of the individual NNMs from broadband input and output data. It is demonstrated using a numerical cantilever beam possessing a cubic nonlinearity at its free end. The proposed methodology can be viewed as a nonlinear generalization of the phase separation techniques routinely utilized for experimental modal analysis of linear structures. The paper ends with a comparison between this new nonlinear phase separation technique and a previously-developed nonlinear phase resonance method. [less ▲]

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See detailExperimental nonlinear identification of an aircraft with bolted connections
De Filippis, Giovanni; Noël, Jean-Philippe ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXIII (2015, February)

Aircraft structures are known to be prone to nonlinear phenomena, especially as they constantly become lighter and hence more flexible. One specific challenge that is regularly encountered is the modeling ... [more ▼]

Aircraft structures are known to be prone to nonlinear phenomena, especially as they constantly become lighter and hence more flexible. One specific challenge that is regularly encountered is the modeling of the mounting interfaces between aircraft subcomponents. Indeed, for large amplitudes of vibration, such interfaces may loosen and, in turn, trigger complex mechanisms such as friction and clearances. In this context, the present work intends to investigate the nonlinear dynamics of the Morane–Saulnier Paris aircraft, accessible at ONERA. This aircraft possesses multiple bolted connections between two external fuel tanks and wing tips. The objective of the paper is specifically to carry out an adequate identification of the numerous nonlinearities affecting the dynamics of this full-scale structure. Nonlinearity detection and the subsequent subspace-based parameter estimation have been performed on experimental data, collected during an on-ground test campaign. Nonlinearity detection is first achieved by the comparison of frequency response functions estimated at low excitation level, with those obtained at high amplitude level, yielding insight towards accurately characterizing the behavior of the bolted connections. Then, a nonlinear subspace identification method is applied to measured data to estimate the linear and nonlinear parameters of the structure and novel strategies and tools that overcome specific arisen problems are developed. [less ▲]

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See detailNonlinear generalization of Den Hartog׳s equal-peak method
Habib, Giuseppe ULg; Detroux, Thibaut ULg; Viguié, Régis et al

in Mechanical Systems & Signal Processing (2015), 52-53

This study addresses the mitigation of a nonlinear resonance of a mechanical system. In view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the ... [more ▼]

This study addresses the mitigation of a nonlinear resonance of a mechanical system. In view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the nonlinear tuned vibration absorber (NLTVA), is introduced in this paper. An unconventional aspect of the NLTVA is that the mathematical form of its restoring force is tailored according to the nonlinear restoring force of the primary system. The NLTVA parameters are then determined using a nonlinear generalization of Den Hartog׳s equal-peak method. The mitigation of the resonant vibrations of a Duffing oscillator is considered to illustrate the proposed developments. [less ▲]

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See detailBridging the gap between Nonlinear Normal Modes and Modal Derivatives
Sombroek, Cees; Renson, Ludovic ULg; Tiso, Paolo et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXIII (2015, February)

Nonlinear Normal Modes (NNMs) have a clear conceptual relation to the classical linear normal modes (LNMs), yet they offer a solid theoretical framework for interpreting a wide class of non-linear ... [more ▼]

Nonlinear Normal Modes (NNMs) have a clear conceptual relation to the classical linear normal modes (LNMs), yet they offer a solid theoretical framework for interpreting a wide class of non-linear dynamical phenomena with no linear counterpart. The main difficulty associated with NNMs is that their calculation for large-scale models is expensive, particularly for distributed nonlinearities. Repeated direct time integrations need to be carried out together with extensive sensitivity analysis to reproduce the frequency-energy dependence of the modes of interest. In the present paper, NNMs are computed from a reduced model obtained using a quadratic transformation comprising LNMs and Modal Derivatives (MDs). Previous studies have shown that MDs can capture the essential dynamics of geometrically nonlinear structures and can greatly reduce the computational cost of time integration. A direct comparison with the NNMs computed from another standard reduction technique highlights the capability of the proposed reduction method to capture the essential nonlinear phenomena. The methodology is demonstrated using simple examples with 2 and 4 degrees of freedom. [less ▲]

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