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See detailOrder reduction in time integration caused by velocity projection
Arnold, Martin; Cardona, Alberto; Bruls, Olivier ULg

in Proceedings of the 3rd Joint International Conference on Multibody System Dynamics and the 7th Asian Conference on Multibody Dynamics (2014, July)

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may ... [more ▼]

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may formally be obtained from time derivatives of the original holonomic constraints. A numerical solution that satisfies hidden constraints as well as the original constraint equations may be obtained considering both types of constraints simultaneously in each time step (stabilized index-2 formulation) or using projection techniques. Both approaches are well established in the time integration of differential-algebraic equations. Recently, we have introduced a generalized- alpha Lie group time integration method for the stabilized index-2 formulation that achieves second order convergence for all solution components. In the present paper, we show that a separate velocity projection would be less favourable since it may result in an order reduction and in large transient errors after each projection step. This undesired numerical behaviour is analysed by a one-step error recursion that considers the coupled error propagation in differential and algebraic solution components. This one-step error recursion has been used before to prove second order convergence for the application of generalized-alpha methods to constrained systems. As a technical detail, we discuss the extension of these results from symmetric, positive definite mass matrices to the rank deficient case. [less ▲]

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See detailSentence repetition task as a powerful diagnostic tool in French children with SLI
Leclercq, Anne-Lise ULg

Poster (2014, July)

Sentence repetition is considered as a psycholinguistic marker of specific language impairment (SLI) (i.e., Redmond et al., 2011). However, little is known about specificity and sensitivity for most ... [more ▼]

Sentence repetition is considered as a psycholinguistic marker of specific language impairment (SLI) (i.e., Redmond et al., 2011). However, little is known about specificity and sensitivity for most language tests, especially in French (Thordardottir et al., 2011). This study aims at assessing the specificity and sensitivity of a sentence repetition task frequently used in clinical evaluations (Chevrie-Muller et al., 2010). This task could be especially interesting because clinicians can compute separate linguistic scores depending on the answers produced by the children, enabling them to get a glimpse of the areas of language difficulties in these children. Fourty-four school-age children with SLI, and 34 age-and-IQ-matched controls participated in this study. Children with SLI were diagnosed by certified speech-language pathologists and attained specific language classes in special needs schools from at least one year. Moreover, they scored more than -1.25 SD below expected normative performance in at least 2 language areas on other standardised tests used in previous studies including French children with SLI. Results show that both sensitivity and specificity of general scores were high (over 80%) at three cut-off points widely used in clinical practice: -1SD, -1.25 SD, -2 SD. Moreover, an exploratory factorial analysis indicates that two distinct factors can be dissociated in children productions: a morphosyntactic factor and a lexico-semantic factor, together explaining 96.48% of the variance in production scores. These results reveal that the sentence repetition task is a powerful diagnostic tool in French children with SLI. [less ▲]

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See detailGay and Lesbian Families Well-Beeing: Respectively Ten and Seven years after the legalization of Same-sex Marriage and Same-sex Adoption in Belgium, understanding heterosexual adults' attitudes.
Scali, Thérèse ULg; D'Amore, Salvatore ULg; Green, Robert-Jay

Conference (2014, July)

Belgium is one of the first European country to legalize marriage and adoption for same-sex couples (respectively in 2003 and 2006) and to state anti-discrimination laws (2008). Despite the legalization ... [more ▼]

Belgium is one of the first European country to legalize marriage and adoption for same-sex couples (respectively in 2003 and 2006) and to state anti-discrimination laws (2008). Despite the legalization, what can we say about adults’ attitudes? This study is part of an international project, and aims at studying the attitudes towards different kind of same-sex constellations – single gays and lesbians, couples, and families – and at examining the correlates to those attitudes. Attitudes were assessed through self-report questionnaires in a cohort of 366 heterosexual participants resident in Belgium, 72% females and 28% males aged from 26 to 40 (age class corresponding to transition lifecycle and parenting choices). Participants were asked to answer socio-demographic questions and to self-report their contact with homosexual people (frequency and satisfaction). Then different scales assessed their attitudes toward homosexuality (General Attitudes Toward Homosexuality, Da Costa, 2011; ATLG, Herek), same-sex marriage (Katuzny Scale on Same-Sex Marriage, 2012) and different types of same¬-sex parenting – adoption, alternative insemination, in vitro, ovocyte donation (D’Amore & Green Homoparentality Scale, 2012). It is hypothesized that correlates to positive attitudes will be associated with female gender, lower religiosity, non-protestant religions, liberal political ideology, and higher education and socioeconomic status. This presentation contributes to a better understanding of Belgian’s attitudes toward same-sex couples and same-sex families, by measuring the predictive variables of positive and negative attitudes. [less ▲]

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See detailVibration analysis by speckle interferometry with CO2 lasers and microbolometers arrays
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Georges, Marc ULg

in OSA Technical Digest (online) (2014, July)

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than ... [more ▼]

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than what is achieved with visible wavelengths. [less ▲]

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See detailGalectin-3: a new promising cardiac biomarker in sports endurance?
LE GOFF, Caroline ULg; Devaux, Séverine; BREVERS, Eric ULg et al

in Cardiovascular Research (2014, July), 103(Supplement 1), 255

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See detailBoard attributes and accounting conservatism: Evidence from French firms
Boussaid, Nabila ULg; Sougné, Danielle ULg; Hamza, Taher

Conference (2014, July)

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See detailOverview and Benchmarking of Motion Detection Methods
Jodoin, Pierre-Marc; Pierard, Sébastien ULg; Wang, Yi et al

in Bouwmans; Porikli; Hoferlin (Eds.) et al Background Modeling and Foreground Detection for Video Surveillance (2014)

In this chapter, we provide an overview of the most highly cited motion detection meth- ods. We identify the most commonly used background models together with their features, the kind of updating scheme ... [more ▼]

In this chapter, we provide an overview of the most highly cited motion detection meth- ods. We identify the most commonly used background models together with their features, the kind of updating scheme they use, some spatial aggregation models as well as the most widely used post-processing operations. We also provide an overview of datasets used to validate motion detection methods. Please note that this literature review is by no means exhaustive and thus we provide a list of surveys that the reader can rely on for further details. [less ▲]

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See detailExperimental analysis of 2:1 modal interactions with noncommensurate linear frequencies in an aerospace structure
Noël, Jean-Philippe ULg; Renson, Ludovic ULg; Kerschen, Gaëtan ULg

in Proceedings of the 8th European Nonlinear Dynamics Conference (ENOC) (2014, July)

Nonlinear interactions between modes with noncommensurate linear frequencies are studied. It is experimentally evidenced that a strongly nonlinear, full-scale aerospace structure may exhibit such 2:1 ... [more ▼]

Nonlinear interactions between modes with noncommensurate linear frequencies are studied. It is experimentally evidenced that a strongly nonlinear, full-scale aerospace structure may exhibit such 2:1 interactions in typical testing conditions. The experimental observations are compared with numerical predictions. [less ▲]

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See detailNghiên cứu và thiết kế hai kiểu chuồng nuôi nhông cát Leiolepis guttata (Cuvier, 1829) phù hợp với điều kiện nuôi và vốn đầu tư tại huyện Bắc Bình, tỉnh Bình Thuận
Tran, Tinh ULg; Tran, Ngoc Nguyen Kim Dieu; Vo, Kim Thong et al

in Journal of Agriculture Sciences and Technology (2014), 1/2014

Building of an enclosure for rearing of the spotted butterfly lizard, Leiolepis guttata (Cuvier, 1829), by the first farmer in 2004 (in Hong Chinh commune, Hoa Thang ward, Bac Binh district, Binh Thuan ... [more ▼]

Building of an enclosure for rearing of the spotted butterfly lizard, Leiolepis guttata (Cuvier, 1829), by the first farmer in 2004 (in Hong Chinh commune, Hoa Thang ward, Bac Binh district, Binh Thuan province) is considered as a fortuitous discovery which was the initiator of the current expanding trend of its rearing. Because L. guttata is a wild animal, with strong disease resistance and adaptation capacity, livestock farmers are presently not very interested in important aspects: rearing techniques, enclosure’s types, sex ratio, diseases’ prevention, etc. Notably the building of enclosures not perfectly suitable breeds a noticeable loss of the number of lizards and a reduction in the profits for the farmers. To this end, the building of two types of enclosures adapted to local rearing conditions and the investing capital available in Bac Binh district, Binh Thuan province is presently essential. We descrite two types of enclosure: the first one surrounded by a bricks (or breeze blocks) wall, the second one fended by a fiber cement corrugated sheets wall. Moreover, we suggest to introduce plants in order to build a vegetal cover nearer to the natural environment of L. guttata: shrubs and a plant carpet becoming the preferential refuge area of the spotted butterfly lizard. [less ▲]

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See detailRecollection and familiarity in normal and pathological aging
Bastin, Christine ULg

Conference (2014, July)

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See detailBiological indicators of soil quality over landscape spatial scales: a case study in Southern Belgium
Krüger, Inken ULg; Chartin, Caroline; Van Wesemael, Bas et al

Poster (2014, July)

Biological indicators are organisms or biological processes whose values give quantitative information on the capacity of a soil to function. Their fast dynamic allows to detect changes on short ... [more ▼]

Biological indicators are organisms or biological processes whose values give quantitative information on the capacity of a soil to function. Their fast dynamic allows to detect changes on short timescales. Five biological indicators (basal respiration, nitrogen mineralisation, microbial carbon and nitrogen, earthworm abundance and biomass, functional microbial diversity) as well as two ecophysiological indices (microbial quotient and metabolic quotient) were tested for their power to characterize the biological soil quality on a landscape level at 60 sites in two South-Belgian landscape units were investigated. All biological indicators differed significantly between the two landscape units showing the biological indicators to be discriminatory on a landscape level. Within each landscape unit, no relationships between biological indicators were found, underlining the need to measure multiple biological indicators. The results represent the first data for a South-Belgian monitoring network of biological soil quality. [less ▲]

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See detailMcCune-Albright Syndrome: A Detailed Pathological And Genetic Analysis of Disease Effects in an Adult Patient.
Vasilev, Vladimir; Daly, Adrian ULg; THIRY, Albert ULg et al

in The Journal of clinical endocrinology and metabolism (2014)

Context: McCune Albright syndrome (MAS) is a clinical association of endocrine and non-endocrine anomalies caused by post-zygotic mutation of the GNAS1 gene, leading to somatic activation of the ... [more ▼]

Context: McCune Albright syndrome (MAS) is a clinical association of endocrine and non-endocrine anomalies caused by post-zygotic mutation of the GNAS1 gene, leading to somatic activation of the stimulatory alpha subunit of G protein (Gsalpha). Important advances have been made recently in describing pathological characteristics of many MAS-affected tissues, particularly pituitary, testicular and adrenal disease. Other rarer disease related features are emerging. Objective: To study pathological and genetic findings of MAS on a tissue-by-tissue basis in classically and non classically affected tissues. Design: A comprehensive autopsy and genetic analysis Setting: Tertiary referral University Hospital Patients: Adult male patient with MAS and severe disease burden including gigantism Intervention(s): Clinical, hormonal and radiographic studies; gross and microscopic pathology analyses, conventional PCR and droplet digital PCR analyses of affected and non affected tissues Main Outcome Measure: Pathological findings, presence of GNAS1 mutations Results: The patient was diagnosed with MAS syndrome at six years of age based on the association of cafe-au-lait spots and radiological signs of polyostotic fibrous dysplasia. Gigantism developed and hyperprolactinemia, hypogonadotropic hypogonadism and hyperparathyroidism were diagnosed throughout adult period. The patient died at the age of 39 from pulmonary embolism. A detailed study revealed mosaiscism for the p.R201C GNAS mutation distributed across many endocrine and non-endocrine tissues. These genetically implicated tissues included rare or previously undescribed disease associations including primary hyperparathyroidism, and hyperplasia of the thymus and endocrine pancreas. Conclusions: This comprehensive pathological study of a single patient highlights the complex clinical profile of MAS and illustrates important advances in understanding the characteristics of somatic GNAS1 related pathology across a wide range of affected organs. [less ▲]

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See detailMultiscale Computational Modeling of Deformation Mechanics andIntergranular Fracture in Nanocrystalline Copper
Péron-Lührs, Vincent ULg; Sansoz, Frédéric; Jérusalem, Antoine et al

in Computational Materials Science (2014), 90

The material description is based on two constitutive elements, the grains (or bulk crystals) and the grainboundaries (GBs), both having their behavior determined atomistically using the quasicontinuum ... [more ▼]

The material description is based on two constitutive elements, the grains (or bulk crystals) and the grainboundaries (GBs), both having their behavior determined atomistically using the quasicontinuum (QC) method by simulating the plastic deformation of [110] tilt crystalline interfaces undergoing simple shear, tension and nano-indentation. Unlike our previous work [V. Péron-Lührs et al., JMPS, 2013] however, the GB thickness is here calibrated in the model, providing more accurate insight into the GB widths according to the interface misorientation angle. In this contribution, the new two-scale model is also validated against fullyatomistic NC simulations tests for two low-angle and high-angle textures and two grain sizes. A simplified strategy aimed at predicting the mechanical behavior of more general textures without the need to run more QC simulations is also proposed, demonstrating significant reduction in computational cost compared to full atomistic simulations. Finally, by studying the response of dogbone samples made of NC copper, we show in this paper that such a two-scale model is able to quantitatively capture the differences in mechanical behavior of NC metals as a function of the texture and grain size, as well as to accurately predict the processes of inter-granular fracture for different GB character distributions. This two-scale method is found to be an effective alternative to other atomistic methods for the prediction of plasticity and fracture in NC materials with a substantial number of 2-D grains such as columnar-grained thin films for micro-scale electro-mechanical devices. [less ▲]

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See detailCROSSROADS
Sacré, Robert ULg

Diverse speeche and writing (2014)

Programme radio hebdomadaire (chaque mercredi 18h-20h) sur Equinoxe FM 100.1 streaming www.equinoxefm.be

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See detailInformations sur la Continuité Ecologique - ICE -Evaluer le franchissement des obstacles par les poissons. Principes et méthodes
Baudoin, Jean-Marc; Burgun, Vincent; Chanseau, Matthieu et al

Book published by Onema (2014)

La fragmentation des milieux naturels est l’une des principales causes d’érosion de la biodiversité. L’impact des obstacles à l’écoulement se manifeste par une dégradation des milieux aquatiques et ... [more ▼]

La fragmentation des milieux naturels est l’une des principales causes d’érosion de la biodiversité. L’impact des obstacles à l’écoulement se manifeste par une dégradation des milieux aquatiques et consécutivement des biocénoses et des processus écologiques qu’ils abritent. Face aux exigences réglementaires (directive cadre sur l’eau, loi sur l’eau et les milieux aquatiques, grenelle de l’environnement, règlement européen de sauvegarde de l’anguille…) et à l'ensemble des enjeux environnementaux de la restauration de la continuité écologique des milieux aquatiques, l’Onema a souhaité développer un “outil ” permettant de diagnostiquer et quantifier les éventuels impacts des ouvrages hydrauliques sur la libre circulation de l'ichtyofaune. Le protocole ICE est une méthodologie nationale de production d’ “Informations sur la Continuité Ecologique” à destination des acteurs de l'environnement et de l'aménagement du territoire, des scientifiques, des enseignants, bureaux d’études et tout public intéressé. Il s'appuie sur une importante synthèse des connaissances scientifiques internationales actuelles et sur les productions scientifiques et techniques d’un groupe de travail composé d'experts français (Onema et Ecogea) et belge (Université de Liège). L'objectif de ce document est de présenter les enjeux de la continuité piscicole, les principes scientifiques qui ont prévalu à la construction de cette méthodologie d’évaluation, ainsi que le protocole standardisé qui a été développé. Il permet de diagnostiquer de manière simple et objective le risque d'entrave au déplacement de l'ichtyofaune en montaison, généré par les principaux types d'obstacles physiques à l’écoulement et pour les espèces communes des cours d'eau de France métropolitaine. Ce diagnostic repose sur la confrontation des caractéristiques typologiques, géométriques et hydrauliques des obstacles avec les capacités physiques de déplacement des espèces de poissons considérées. [less ▲]

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See detailInverting Hydraulic Heads In An Alluvial Aquifer Constrained With Electrical Resistivity Tomography Data Through Multiple-Point Statistics And Probability Perturbation Method: A Case Study
Hermans, Thomas ULg; Scheidt, Celine; Caers, Jef et al

Conference (2014, July)

Solving spatial inverse problems in the Earth Sciences remains a considerable challenge given the large number of parameters to invert for, the non-linearity of forward models and as a result the ill ... [more ▼]

Solving spatial inverse problems in the Earth Sciences remains a considerable challenge given the large number of parameters to invert for, the non-linearity of forward models and as a result the ill-posedness of the problem. Geostatistics is therefore needed to specify prior models, more particularly, information to control the spatial features of the inverse solutions. We used multiple-point statistics (MPS) to build models of pre-defined hydrofacies: clay, sand and gravel facies constrained to geological data (hard data) and geophysical data (soft data). The electrical resistivity tomography method was chosen to bring relevant spatially distributed information on the presence of the facies, given its sensitivity to variations in lithology and porosity. The comparison of the geophysical signature of the deposits with direct observations in boreholes enables to derive the conditional probability of observing a facies given its electrical resistivity. This is used to produce probability maps for each facies and constrain stochastic simulations of the alluvial aquifer. Then, the probability perturbation method (PPM) is used to integrate hydraulic heads data, using MPS to generate models. This process enables us to obtain calibrated models of the aquifer. The PPM algorithm will automatically seek solutions fitting both hydrogeological data and training-image based geostatistical constraints. Only geometrical features of the model are affected by the perturbation, i.e. we do not attempt to directly find the optimal value of hydrogeological parameters (chosen a priori), but the optimal spatial distribution of facies whose prior distribution is quantified in a training image. The methodology is first tested with a synthetic benchmark. The tests performed show that the choice of the training image is a major source of uncertainty. Therefore, one first needs to select those training images consistent with the geophysical data (and hence reject the inconsistent ones). Then, we proceed with them to hydrogeological inversions. Geophysical data (soft constraints) acts as an accelerator of convergence by reducing prior uncertainty. The hydraulic conductivity of each facies is a sensitive parameter, but it can be easily optimized prior to the PPM process. The stochastic method is then successfully applied within the context of an alluvial aquifer submitted to a pumping experiment. We show how the integration of various sources of data (borehole logs, geophysics, hydraulic heads) aids in calibrating hydrogeological models, locating high hydraulic conductivity zones and reducing uncertainty. The developed methodology proposes a common framework (multiple-point statistics) to integrate various information sources with variable resolutions relevant for hydrogeology: geological, geophysical and hydrogeological data. The method can be extended to integrate tracer tests to enable the calibration of transport parameters as well. The originality of the method is to use geophysical data both to refine the choice of the training image and to constrain the inversion of hydrogeological models. [less ▲]

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