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See detailOn modular decompositions of system signatures
Marichal, Jean-Luc; Mathonet, Pierre ULg

in Journal of Multivariate Analysis (2015), 134

Considering a semicoherent system made up of $n$ components having i.i.d. continuous lifetimes, Samaniego defined its structural signature as the $n$-tuple whose $k$-th coordinate is the probability that ... [more ▼]

Considering a semicoherent system made up of $n$ components having i.i.d. continuous lifetimes, Samaniego defined its structural signature as the $n$-tuple whose $k$-th coordinate is the probability that the $k$-th component failure causes the system to fail. This $n$-tuple, which depends only on the structure of the system and not on the distribution of the component lifetimes, is a very useful tool in the theoretical analysis of coherent systems. It was shown in two independent recent papers how the structural signature of a system partitioned into two disjoint modules can be computed from the signatures of these modules. In this work we consider the general case of a system partitioned into an arbitrary number of disjoint modules organized in an arbitrary way and we provide a general formula for the signature of the system in terms of the signatures of the modules. The concept of signature was recently extended to the general case of semicoherent systems whose components may have dependent lifetimes. The same definition for the $n$-tuple gives rise to the probability signature, which may depend on both the structure of the system and the probability distribution of the component lifetimes. In this general setting, we show how under a natural condition on the distribution of the lifetimes, the probability signature of the system can be expressed in terms of the probability signatures of the modules. We finally discuss a few situations where this condition holds in the non-i.i.d. and nonexchangeable cases and provide some applications of the main results. [less ▲]

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See detailExperimental demonstration of a 3D-printed nonlinear tuned vibration absorber
Grappasonni, Chiara ULg; Habib, Giuseppe ULg; Detroux, Thibaut ULg et al

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

Engineering structures are designed to be lighter and more flexible, hence reducing the extent of application of linear dynamic models. Concurrently, vibration mitigation is required for enhancing the ... [more ▼]

Engineering structures are designed to be lighter and more flexible, hence reducing the extent of application of linear dynamic models. Concurrently, vibration mitigation is required for enhancing the performance, comfort or safety in real-life applications. Passive linear vibration absorbers are purpose-built, often designed using Den Hartog's equal-peak strategy. However, nonlinear systems are known to exhibit frequency-energy-dependent oscillations which linear absorbers cannot effectively damp out. In this context, the paper introduces a new nonlinear tuned vibration absorber (NLTVA) whose nonlinear functional form is tailored according to the frequency-energy dependence of the nonlinear primary structure. The NLTVA design aims at ensuring equal peaks in the nonlinear receptance function for an as large as possible range of forcing amplitudes, hence generalizing Den Hartog's method to nonlinear systems. Our focus in this study is on experimental demonstration of the NLTVA performance using a primary structure consisting of a cantilever beam with a geometrically nonlinear component at its free end. The absorber is implemented using a doubly-clamped beam fabricated thanks to 3D printing. The NLTVA performance is also compared with that of the classical linear tuned vibration absorber. [less ▲]

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See detailGeräusch, Gerücht, Gerede. Formen und Funktionen der Fama in Erzähltexten Theodor Storms und Arthur Schnitzlers
Leyh, Valérie ULg

Doctoral thesis (2015)

Dans sa représentation allégorique de Fama, le poète latin Ovide évoque trois phénomènes précis : son aspect acoustique (le bruit), sa forme discursive (les racontars) et son lien au récit (la rumeur ... [more ▼]

Dans sa représentation allégorique de Fama, le poète latin Ovide évoque trois phénomènes précis : son aspect acoustique (le bruit), sa forme discursive (les racontars) et son lien au récit (la rumeur). Alors que ces phénomènes ont très souvent fait l'objet d’études sociologiques et anthropologiques, il s’agit ici de les étudier en tant qu’objets d’un processus d’esthétisation. La thèse vise ainsi à décrire une « poétique de Fama » par l’analyse d’un choix de textes narratifs des auteurs germanophones Theodor Storm (1817 – 1888) et Arthur Schnitzler (1862 – 1931). En effet, les recherches récentes sur l’anticipation de la psychologie et sur les questions de perception chez Storm soulignent l’importance de stratégies narratives au caractère indirect, voilé et mettant à mal la plausibilité ; elles révèlent la nécessité d’étudier la rumeur comme élément thématique mais aussi structurel et formel. Les nombreux aspects de Fama intimement liés aux processus narratifs (polyphonie, psychologisation, contournement de la censure) permettent ensuite de confronter les textes de Storm à ceux de Schnitzler et d'y préciser les interactions subtiles entre bruit, racontars et rumeur. Dans ce traitement littéraire de Fama, il s’avère en outre primordial de mettre en lumière ses multiples fonctions selon les différents niveaux textuels (personnages, narrateur, auteur) et d’accorder une place au lecteur qui, dans une approche interactionnelle du récit, prend souvent part à la communication rumorale. Ces distinctions permettent de mettre en exergue la dimension poétologique de Fama dans ses différentes formes : si celle-ci participe à la création d’effets paradoxaux et de structures équivoques au sein des textes, c’est parce que la rumeur, en tant que forme de narration à caractère ambivalent et protéiforme, est fortement autoréflexive. L’instabilité et la contingence, l’indétermination de seuils et de frontières sont autant de traits qui caractérisent non seulement la rumeur et les racontars mais aussi les textes d’une époque marquée par de grandes mutations et par la mise en doute de valeurs et données acquises jusque-là. [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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See detailUsing shear strain localisation to model the fracturing around gallery in unsaturated Callovo-Oxfordian claystone
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

in Chau, Kam Tim; Zhao, Jidong (Eds.) Bifurcation and Degradation of Geomaterials in the New Millennium (2015, January 28)

Galleries drilling leads to damage propagation, fracturing and properties modifications in the surrounding medium. The prediction of the damaged zone behaviour is an important matter and needs to be ... [more ▼]

Galleries drilling leads to damage propagation, fracturing and properties modifications in the surrounding medium. The prediction of the damaged zone behaviour is an important matter and needs to be properly assessed. To do so the fractures can be modelled using shear strain localisation. The coupled local second gradient model is used under unsaturated conditions to correctly model the strain localisation behaviour. The permeability evolution and the rock desaturation due to air ventilation in galleries are considered. Finally, a hydro-mechanical modelling of a gallery excavation in Callovo-Oxfordian claystone is performed leading to a fairly good representation of the damaged zone. [less ▲]

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See detailLe testing adaptatif informatisé : une brève introduction
Magis, David ULg

Conference (2015, January 27)

L’objet de cet exposé est de présenter les grands principes et concepts du testing adaptatif informatisé (TAI). Les éléments abordés sont : le TAI face au test fixe (papier-crayon), les principes généraux ... [more ▼]

L’objet de cet exposé est de présenter les grands principes et concepts du testing adaptatif informatisé (TAI). Les éléments abordés sont : le TAI face au test fixe (papier-crayon), les principes généraux du TAI (banque d’items, estimation provisoire et finale de la compétence, sélection des items à administrer, règles d’arrêt), les principes spécifiques au TAI (contrôle de l’exposition des items, équilibrage du contenu des tests). L’exposé se veut didactique et général afin de dessiner les contours du TAI. Il se termine par un état de l’art sur les recherches actuelles sur le TAI. [less ▲]

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See detailSimplified analytical methods for the crashworthiness and the seismic design of lock gates
Buldgen, Loïc ULg

Doctoral thesis (2015)

The PhD dissertation aims to provide simplified tools based on analytical formulations in order to ease the pre-design of lock gates. The first part of the thesis is devoted to ship collisions. The ... [more ▼]

The PhD dissertation aims to provide simplified tools based on analytical formulations in order to ease the pre-design of lock gates. The first part of the thesis is devoted to ship collisions. The resistance of the impacted gate is evaluated by combining global and local deforming modes. In the second part of the dissertation, an analytical solution is proposed to estimate the total hydrodynamic pressure acting on a lock gate during a seism, with due consideration for the fluid-structure coupling. Numerical validations are proposed for both ship collisions and earthquakes. [less ▲]

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See detailÉtude du Typus mélancholicus au sein d’une population de dépressifs unipoalires
ramackers, Amélia; Englebert, Jérôme ULg

Poster (2015, January 21)

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See detailLa personnalité Borderline à travers le test de Rorschach
Rommes, Jennifer; Englebert, Jérôme ULg

Poster (2015, January 21)

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See detailÉtude du récit de vie de l’adulte à haut potentiel
Mormont, Elodie; Gauthier, Jean-Marie ULg; Englebert, Jérôme ULg

Poster (2015, January 21)

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See detailEspace, temps et psychopathologie en prison
Englebert, Jérôme ULg

Scientific conference (2015, January 19)

L’analyse du cas de Nathan, sorte d’épisode princeps de notre analyse de l’univers carcéral, nous permettra d’étudier les notions de temps et d’espace. Ces deux coordonnées sont fondamentales, tant pour ... [more ▼]

L’analyse du cas de Nathan, sorte d’épisode princeps de notre analyse de l’univers carcéral, nous permettra d’étudier les notions de temps et d’espace. Ces deux coordonnées sont fondamentales, tant pour la considération anthropologique de l’homme situation d’enfermement que pour la compréhension psychopathologique. À partir de cette analyse, dans laquelle nous évoquerons notamment un texte peu connu de Sartre sur les Visages ainsi que la philosophie des émotions de Scheler, c’est la problématique fondamentale du corps que nous évoquerons. L’épisode psychopathologique du Gate fever (la « fièvre de la porte ») vécu par Nathan nous permettra également d’évoquer le vécu émotionnel paradoxal de l’expérience psychotique. [less ▲]

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See detailLow molecular weight poly (2-dimethylamino ethylmethacrylate) polymers with controlled positioned fluorescent labeling: Synthesis, characterization and in vitro interaction with human endothelial cells.
Flebus, Luca ULg; Lombart, François ULg; Sevrin, Chantal et al

in International journal of pharmaceutics (2015), 478(1), 278-287

Poly (2-dimethylamino ethylmethacrylate) (PDMAEMA) is an attractive non-degradable polymer studied as nonviral vector for gene delivery but it can be also adopted for delivery of other biopharmaceutical ... [more ▼]

Poly (2-dimethylamino ethylmethacrylate) (PDMAEMA) is an attractive non-degradable polymer studied as nonviral vector for gene delivery but it can be also adopted for delivery of other biopharmaceutical drugs. As a parenteral carrier, the PDMAEMA free form (FF) might interact with tissues and cells. Few data are available on its selective internalization and efflux from cells, while the majority of studies published have followed the distribution of DNA complexed with PDMAEMA. In order to address polycation safety, the first aim was to synthesize by atom transfer radical polymerisation (ATRP) fluorescent labeled PDMAEMA of low molecular weight (Mw) (below 15kDa), controlling the position and density of fluorescein. The second goal was to analyze the possible difference in uptake and subcellular distribution of this labeled FF polycation between human umbilical vein endothelial cells (HUVEC) and hCMEC/D3 cells. These two cell lines have been chosen in order to detect selectivity towards the blood-brain barrier (BBB). In both cases, polycation was detected along the plasma membrane followed by progressive migration to the peri-nuclear region, where it overlapped with lysosomal structures. The analysis by fluorescence-activated cell sorting (FACS) of the PDMAEMA uptake by hCMEC/D3 cells showed a significant (p<0.05) inhibition (40%) in presence of 2-dexoxy-d-glucose inhibitor, a result supporting an energy-dependence mechanism(s). Cytotoxicity study showed that low Mw PDMAEMA (10kDa) lead to a minor cytotoxicity compared to the higher ones. As main conclusion this study highlights the similitude in cell trafficking of FF PDMAEMA and data previously reported for PDMAEMA/DNA complexes. [less ▲]

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See detailIntroduction to item response theory (IRT) and computerized adaptive testing (CAT) with the R software
Magis, David ULg

Scientific conference (2015, January 13)

Item response theory (IRT) has become an important field of research for psychology and educational assessment. Recently, with the increase of computational power, several IRT-related topics have emerged ... [more ▼]

Item response theory (IRT) has become an important field of research for psychology and educational assessment. Recently, with the increase of computational power, several IRT-related topics have emerged, among others, computerized adaptive testing (CAT). The main aim of CAT is to provide a framework for individualized assessment by means of optimal item selection and administration to the test takers. CAT has several assets to linear (non-adaptive) testing: individualized assessment, limited risk of cheating or fraud, shorter tests providing the same amount of information as longer linear tests, automatic scoring and reporting at the end of the test. Practical use of CAT, however, remains limited so far due to several factors (lack of available large item banks, content validity and security, lack of suitable software for practical CAT assessment, ethical issues in administering different tests to estimate the same ability, etc.). The purpose of this workshop is threefold: (a) to provide a general overview of IRT and CAT, (b) to introduce the R software in a user-oriented way, as well as several IRT tools (including the package catR for CAT simulations), (c) to perform practical training sessions with the participants. The workshop will be a mix of oral presentations, demonstrations related to the R software, and practical sessions where participants will be invited to train with R and catR. The R software is an open-source platform for statistical inference and testing, graphical display and data visualization. It also holds several add-on packages for specific IRT purposes (item calibration, ability estimation, multidimensional scaling, equating, differential item functioning etc.). The R community is worldwide and proposes free exchanges of shared R packages through the CRAN (comprehensive R archive network). In this workshop, the R package catR will be examined and used in the practical sessions. [less ▲]

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See detailEffect of stress path on the miniaturizatio size effect for nickel polycrystals
Keller, Clement; Hug, Eric; Duchene, Laurent ULg et al

Conference (2015, January 04)

The mechanical behavior of mettalic materials deeply depends on the size of samples. For specimen dimensions de creasing from a few millimeters to a few micrometers, the general observed trend is a ... [more ▼]

The mechanical behavior of mettalic materials deeply depends on the size of samples. For specimen dimensions de creasing from a few millimeters to a few micrometers, the general observed trend is a softening of the mechanical behavior in tension which affects the stress level and the strain hardening. This effect is triggered by the derease of the number of grains across the thickness ( also called thickness"t" over grain size "d" ratio). The objective of this work is to provide new experimental results in order to analyse the miniaturization size effects for various stress paths without strain gradients across the thickness of the samples. To this aim, experimental tensil tests, large tensile tests and shear tests have been performed on Ni sheets ( 0.5mm) with various grain sizes ensuring different t/d ratios. Results show that the miniaturization softening is affected by triaxiality, the larger is this parameter, the lower is the mechanicval softening. These features seem to be linked to surface effects which are larger for low triaxiality stress paths. Attempts of numerical simulations using strain gradient crystal plasticity model are also performed to confirm the role played by surface effects. [less ▲]

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See detailBasin-scale partitioning of Greenland ice sheet mass balance components (2007–2011)
Andersen, M.L.; Stenseng, L.; Skourup, H. et al

in Earth and Planetary Science Letters (2015), 409

The current deficit in Greenland ice sheet mass balance is due to both a decrease in surface mass balance (SMB ) input and an increase in ice discharge (D ) output. While SMB processes are beginning to be ... [more ▼]

The current deficit in Greenland ice sheet mass balance is due to both a decrease in surface mass balance (SMB ) input and an increase in ice discharge (D ) output. While SMB processes are beginning to be well captured by observationally-constrained climate modeling, insight into D is relatively limited. We use InSAR-derived velocities, in combination with ice thickness observations, to quantify the mass flux (F ) across a flux perimeter around the ice sheet at ∼1700 m elevation. To quantify D , we correct F for SMB , as well as changes in volume due to ice dynamics, in the area downstream of the gate. Using a 1961–1990 reference climatology SMB field from the MAR regional climate model, we quantify ice sheet mass balance within eighteen basins. We find a 2007–2011 mean D of View the MathML source. We find a 2007–2011 mean total mass balance of View the MathML source, which is equal to a 0.73 mm yr−1 global sea level rise contribution. This mass loss is dominated by SMB, which accounts for 61% of mass loss in the basins where partitioning is possible. [less ▲]

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See detailFood provioning influences ranging patterns in northern pigtailed macaques (Macaca leonina)
Huynen, Marie-Claude ULg; Savini, Tommaso ULg; Asensio, Norberto et al

in International Journal of Primatology (2015, January)

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See detailMetabolic reprogramming in transformed mouse cortical astrocytes: a proteomic study.
Bentaib, Azeddine; De Tullio, Pascal ULg; Chneiweiss, Herve et al

in Journal of proteomics (2015), 113

Metabolic reprogramming is thought to play a key role in sustaining the survival and proliferation of cancer cells. These changes facilitate for example the uptake and release of nutrients required for ... [more ▼]

Metabolic reprogramming is thought to play a key role in sustaining the survival and proliferation of cancer cells. These changes facilitate for example the uptake and release of nutrients required for nucleotide, protein and lipid synthesis necessary for macromolecule assembly and tumor growth. We applied a 2D-DIGE (Two-Dimensional Differential in-Gel Electrophoresis) quantitative proteomic analysis to characterize the proteomes of mouse astrocytes that underwent in vitro cancerous transformation, and of their normal counterparts. Metabolic reprogramming effects on enzymatic and structural protein expression as well as associated metabolites abundance were quantified. Using enzymatic activity measurements and zymography, we documented and confirmed several changes in abundance and activity of various isoenzymes likely to participate in metabolic reprogramming. We found that after transformation, the cells increase their expression of glycolytic enzymes, thus augmenting their ability to use aerobic glycolysis (Warburg effect). An increased capacity to dispose of reducing equivalents through lactate production was also documented. Major effects on carbohydrates, amino acids and nucleotides metabolic enzymes were also observed. Conversely, the transformed cells reduced their enzymatic capacity for reactions of tricarboxylic acid oxidation, for neurotransmitter (glutamate) metabolism, for oxidative stress defense and their expression of astroglial markers. BIOLOGICAL SIGNIFICANCE: The use of a global approach based on a 2D DIGE analysis allows obtaining a comprehensive view of the metabolic reprogramming undergone by astrocytes upon cancerous transformation. Indeed, except for a few enzymes such as pyruvate carboxylase and glutaminase that were not detected in our initial analysis, pertinent information on the abundance of most enzymes belonging to pathways relevant to metabolic reprogramming was directly obtained. In this in vitro model, transformation causes major losses of astrocyte-specific proteins and functions and the acquisition of metabolic adaptations that favor intermediate metabolites production for increased macromolecule biosynthesis. Thus our approach appears to be readily applicable for the investigation of changes in protein abundance that determine various transformed cell phenotypes. It could similarly be applied to the evaluation of the effects of treatments aimed at correcting the consequences of cell transformation. [less ▲]

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