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See detailUniversal amorphous-amorphous transition in GexSe100−x glasses under pressure
Yildirim, Can ULg; Micoulaut, Matthieu; Boolchand, Punit et al

in Scientific Reports (2016), 6

Pressure induced structural modifications in vitreous GexSe100−x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments ... [more ▼]

Pressure induced structural modifications in vitreous GexSe100−x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. Universal changes in distances and angle distributions are observed when scaled to reduced densities. All compositions are observed to remain amorphous under pressure values up to 42 GPa. The Ge-Se interatomic distances extracted from XAS data show a two-step response to the applied pressure; a gradual decrease followed by an increase at around 15–20 GPa, depending on the composition. This increase is attributed to the metallization event that can be traced with the red shift in Ge K edge energy which is also identified by the principal peak position of the structure factor. The densification mechanisms are studied in details by means of AIMD simulations and compared to the experimental results. The evolution of bond angle distributions, interatomic distances and coordination numbers are examined and lead to similar pressure-induced structural changes for any composition. [less ▲]

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See detailAménorhhée primaire : le point de vue endocrinien
VALDES SOCIN, Hernan Gonzalo ULg

Scientific conference (2016, June 07)

Aménorhhée primaire : le point de vue endocrinien Dr Hernan Valdés-Socin Chef de Clinique. Service d’Endocrinologie. CHU de Liège Résumé L’alternance de la phase folliculaire et lutéale ovarienne ... [more ▼]

Aménorhhée primaire : le point de vue endocrinien Dr Hernan Valdés-Socin Chef de Clinique. Service d’Endocrinologie. CHU de Liège Résumé L’alternance de la phase folliculaire et lutéale ovarienne, s’accompagne d’une variation de la sécrétion oestroprogestative déterminant le cycle menstruel de l’utérus. Les différentes perturbations pouvant toucher les circuits hypothalamiques (neurones à kisspeptines, neurones a GnRH), le fonctionnement hypophysaire et son contrôle des différentes glandes endocrines, les anomalies acquises et génétiques des ovaires (syndrome de Turner, insuffisance ovarienne primaire,etc) et de l’utérus (syndrome d’Asherman, Syndrome de Rokytanski, etc) peuvent déterminer selon les cas une aménorrhée primaire ou secondaire. L’aménorrhée primaire est définie par l’absence de ménarche chez une fille arrivée à l’âge de 16 ans alors que l’aménorrhée secondaire est l’absence de menstruation depuis plus de 3 mois, chez une patiente antérieurement bien réglée. Nous discutons et résumons ici les différentes étiologies d’aménorrhée primaire et secondaire, ainsi que leur prise en charge. La disponibilité récente au CHU de Liège d’un panel de 16 gènes responsables d’hypogonadisme hypogonadotrope nous a permis d’approfondir la recherche sur les causes du syndrome de Kallmann et de l’hypogonadisme hypogonadotrope normosmique. Références H. Valdes-Socin , F.G. Debray, A.S. Parent, M.C. Lebrethon, J.P. Bourguignon, V. Bours A. Beckers. Comment je diagnostique un hypogonadisme hypogonadotrope congénital isolé? Rev Med Liège 2010 Nov;65(11):634-41 Valdes-Socin H, Rubio Almanza M, Tomé Fernández-Ladreda M, Debray FG, Bours V, Beckers A. Reproduction, Smell and Neurodevelopmental disorders: Genetic defects in different hypogonadotropic hypogonadal syndromes. Frontiers in Endocrinology 2014 (5) 109 1-8. Valdes-Socin H, Beckers A. El síndrome de Pasqualini. Medicina (B Aires). 2015;75(1):53-8. B. González Aguilera, P. Syrios, R. Gadisseur, F. Luyckx, E. Cavalier, A. Beckers, H. Valdes-Socin. Persistent low levels of serum hCG due to heterophilic mouse antibodies: an unrecognized pitfall in the diagnosis of trophoblastic disease. Gynecology Endocrinology 2015 Jun;32(6):439-41. H. Valdes-Socin, Fg. Debray, C. Libioulle, A. Pintiaux, As. Parent, V. Corman, K. Gellner, V. Geenen, L. Vroonen, V. Dideberg, V. Bours, A. Beckers. Caractérisation clinique, neuroendocrinienne, génétique et résultats thérapeutiques dans le syndrome de Kallmann et de l’hypogonadisme normosmique idiopathique: expérience liégeoise. Annales d'Endocrinologie - 32ème congrès de la société Française d'Endocrinologie 2016. Bordeaux. France. H. Valdes-Socin (Dr), A. Verloesb , Fg. Debrayc , C. Libioullec , A. Pintiauxd , P. Maquet, A. Beckers) Le Syndrome de De Morsier : une cause congénitale méconnue d’hypopituitarisme. Annales d'Endocrinologie - 32ème congrès de la société Française d'Endocrinologie 2016. Bordeaux. France [less ▲]

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See detailCohesive band model: a triaxiality-dependent cohesive model for damage to crack transition in a non-local implicit discontinuous Galerkin framework
Leclerc, Julien ULg; Wu, Ling ULg; Noels, Ludovic ULg et al

Conference (2016, June 07)

Numerical modelling of the complete ductile failure process is still a challenge. On the one hand, continuous approaches, described by damage models, succeed in the initial diffuse damage stage but are ... [more ▼]

Numerical modelling of the complete ductile failure process is still a challenge. On the one hand, continuous approaches, described by damage models, succeed in the initial diffuse damage stage but are still unable to represent physical discontinuities. On the other hand, discontinuous approaches, such as the cohesive zone models, are able to represent the crack propagation behaviour. They are suited for local damaging processes as crack initiation and propagation, and so, fail in diffuse damage prediction of ductile materials. Moreover, they do not usually capture triaxiality effects, mandatory for accurate ductile failure simulations. To describe the ductile failure process, the numerical scheme proposed here combines both approaches [1] in order to beneficiate from their respective advantages: a non-local damage model combined with an extrinsic cohesive law in a discontinuous Galerkin finite element framework. An application example of this scheme is shown on the attached figure. The initial diffuse damage stage is modelled by an implicit nonlocal damage model as suggested by [2]. Upon damage to crack transition, a cohesive band [3] is used to introduce in-plane stretch effects inside the cohesive law or in other words, a triaxiality-dependent behaviour. Indeed, these in-plane strains play an important role during the ductile failure process and have to be considered. Concretely, when crack appears in the last failure stage, all the damaging process is assumed to occur inside a thin band ahead of the crack surface. Thanks to the small but finite numerical band thickness, the strains inside this band can be obtained from the in-plane strains and from the cohesive jump. Then, the stress-state inside the band and the cohesive traction forces on the crack lips are deduced from the underlying continuum damage model. The band thickness is not a new material parameter but is computed to ensure the energetic consistency during the transition. [1] Wu L, Becker G, Noels L. Elastic damage to crack transition in a coupled non-local implicit discontinuous Galerkin/extrinsic cohesive law framework. Comput. Methods Appl. Mech. Eng. 279 (2014): 379–409 [2] Peerlings R., de Borst R., Brekelmans W., Ayyapureddi S. Gradient-enhanced damage for quasi-brittle materials, Int. J. for Num. Methods in Eng. 39 (1996): 3391-3403 [3] Remmers J. J. C., de Borst R., Verhoosel C. V., Needleman A. The cohesive band model: a cohesive surface formulation with stress triaxiality. Int. J. Fract. 181 (2013): 177–188 [less ▲]

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See detailDe l'avatar au personnage : regards croisés entre game studies et études littéraires
Dozo, Björn-Olav ULg; Delbouille, Julie ULg

Conference (2016, June 07)

Si les game studies se sont développées en prenant appui, dans un premier temps, sur les études littéraires et en particulier sur la narratologie (Ryan 2004, Atkins et Krzywinska 2007) pour interroger la ... [more ▼]

Si les game studies se sont développées en prenant appui, dans un premier temps, sur les études littéraires et en particulier sur la narratologie (Ryan 2004, Atkins et Krzywinska 2007) pour interroger la notion de récit appliquée au jeu vidéo, elles ont ensuite fait appel à d’autres disciplines (psychologie et sociologie en particulier) pour construire leur approche de certaines notions, dont celle d’avatar qui nous paraît utile dans le cadre de recherches sur le personnage en littérature. Confrontées à des objets irréductibles à leur textualité (l’étude de la composante « play » du jeu a pris le pas sur celle du « game », surtout en francophonie – voir à ce sujet Triclot, 2011), les game studies se sont dotées d’outils et de théories propres, réélaborant pragmatiquement certaines notions à partir de théories antérieures (les « univers fictionnels », voir Barnabé, 2014) ou forgeant des concepts spécifiques (l’« impératif d’action », voir Genvo, 2005). Dans cette communication, nous souhaitons mobiliser une série de réflexions récentes sur la notion d’avatar vidéoludique pour les étendre à l’étude des personnages au sein de la littérature contemporaine. [less ▲]

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See detailSet theory and foundational mereology as logical tools for descriptive psychology
Leclercq, Bruno ULg

Conference (2016, June 07)

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See detailL’abus de droit et le manque de réelle substance économique : Belgique
Bourgeois, Marc ULg

Conference given outside the academic context (2016)

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See detailPolitique internationale de la culture: patrimoine culturel et industries culturelles
Vlassis, Antonios ULg

Scientific conference (2016, June 06)

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See detailMOISTURE CONTENT DETERMINATION OF FREEZE-DRIED PRODUCTS BY NEAR-INFRARED SPECTROSCOPY: A CASE STUDY FOR UNIVERSAL REGRESSION MODEL
Clavaud, Matthieu ULg; Roggo, Yves; Degardin, Klara et al

Poster (2016, June 06)

Karl Fischer titration is the reference method for moisture content determination in the pharmaceutical industry. Near-infrared spectroscopy is considered the most suitable alternative technique. Indeed ... [more ▼]

Karl Fischer titration is the reference method for moisture content determination in the pharmaceutical industry. Near-infrared spectroscopy is considered the most suitable alternative technique. Indeed, NIRS is a safe and fast method which does not require sample preparation. Nevertheless, the development and validation phases are time-consuming. In addition, the NIRS methods presented so far were mostly product specific. The main objective of this study is to highlight that an universal calibration model can be validated for several freeze-dried products in order to speed up the validation time. This objective was led in two steps. A universal model was first evaluated. A calibration set and a validation set were built up with three freeze-dried products. An antibody drug conjugate, a large molecule and a small molecule all packed in sealed vials were used to introduce more variability. Regression methods were then compared in order to optimize the prediction values. [less ▲]

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See detailImprinting superconducting vortex footsteps in a magnetic layer
Brisbois, Jérémy ULg; Motta, Maycon; Avila Osses, Jonathan ULg et al

in Scientific Reports (2016), 6

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit ... [more ▼]

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit cards and computer hard drives. Here we experimentally show that a similar principle can be applied for imprinting the trajectory of quantum units of flux (vortices), travelling in a superconducting film (Nb), into a soft magnetic layer of permalloy (Py). In full analogy with the magnetic drawing board, vortices act as tiny magnetic scribers leaving a wake of polarized magnetic media in the Py board. The mutual interaction between superconducting vortices and ferromagnetic domains has been investigated by the magneto-optical imaging technique. For thick Py layers, the stripe magnetic domain pattern guides both the smooth magnetic flux penetration as well as the abrupt vortex avalanches in the Nb film. It is however in thin Py layers without stripe domains where superconducting vortices leave the clearest imprints of locally polarized magnetic moment along their paths. In all cases, we observe that the flux is delayed at the border of the magnetic layer. Our findings open the quest for optimizing magnetic recording of superconducting vortex trajectories. [less ▲]

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See detailOn the α-polarization of bacterial suspensions: SIP measurements on four bacterial strains
Pilawski, Tamara ULg; Tappe, Wolfgang; Zimmermann, Egon et al

Poster (2016, June 06)

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See detailA Stochastic Multi-scale Model For Predicting MEMS Stiction Failure
Hoang Truong, Vinh ULg; Paquay, Stéphane; Golinval, Jean-Claude ULg et al

in Proceedings of the SEM XIII International Congress and Exposition on Experimental and Applied Mechanics. (SEMXIII 2016) (2016, June 06)

Adhesion is an important phenomenon in the context of MEMS for which the surface forces become dominant in comparison with the body forces. Because the magnitudes of the adhesive forces strongly depend on ... [more ▼]

Adhesion is an important phenomenon in the context of MEMS for which the surface forces become dominant in comparison with the body forces. Because the magnitudes of the adhesive forces strongly depend on the surface interaction distances, which in turn evolve with the roughness of the contacting surfaces, the adhesive forces cannot be determined in a deterministic way. To quantify the uncertainties on the structural stiction behavior of a MEMS, this work proposes a “stochastic multi-scale methodology”. The key ingredient of the method is the evaluation of the random meso-scale apparent contact forces, which homogenize the effect of the nano-scale roughness and are integrated into a numerical model of the studied structure as a random contact law. To obtain the probabilistic behavior at the structural MEMS scale, a direct method needs to evaluate explicitly the meso-scale apparent contact forces in a concurrent way with the stochastic multi-scale approach. To reduce the computational cost, a stochastic model is constructed to generate the random meso-scale apparent contact forces. To this end, the apparent contact forces are parameterized by a vector of parameters before applying a polynomial chaos expansion in order to construct a mathematical model representing the probability of the random parameters vector. The problem of miro-beam stiction is then studied in a probabilistic way. [less ▲]

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See detailMéthodes historiques de recherche en architecture
Frankignoulle, Pierre ULg

Scientific conference (2016, June 06)

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See detailL’hypothèse d’une Pax Persiana. L’Iran et ses rapports avec l’Occident des années 1850 à 2016
Genin, Vincent ULg

Conference given outside the academic context (2016)

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See detailScreening study of SFC critical method parameters for the determination of pharmaceutical compounds
Dispas, Amandine ULg; Lebrun, Pierre ULg; Sacre, Pierre-Yves ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2016), 125

Nowadays, supercritical fluid chromatography is commonly presented as a promising alternative technique in the field of separation sciences. Nevertheless the selection of chromatographic conditions and ... [more ▼]

Nowadays, supercritical fluid chromatography is commonly presented as a promising alternative technique in the field of separation sciences. Nevertheless the selection of chromatographic conditions and sample preparation of pharmaceutical compounds remain a challenge and peak distortion was previously highlighted. The main objective of the present work was to evaluate the impact of different critical method parameters (CMPs), i.e. stationary phase, mobile phase composition and injection solvent nature. The experiments were performed considering two groups of antimalarial molecules: one group with neutral/apolar compounds and the other one with salt form of polar compounds. In this context, another objective was to propose a suitable sample solvent for quantitative analysis. The interest of new generation stationary phase to obtain good peak shape and the interest to tune the mobile phase composition were demonstrated. During this study, design of experiments and desirability function approach enabled to highlight optimal chromatographic conditions in order to maximise peak capacity and to get acceptable value of symmetry factor. Regarding sample injection solvent composition, some counterintuitive results were observed: solvents closer to the mobile phase polarity (i.e heptane or 2-propanol/heptane mixture) did not provide best results in terms of peak symmetry. In addition, acetonitrile and short aliphatic alcohols offered an interesting alternative as injection solvent: toxicity of solvents used is clearly reduced and better quantitative performances could be expected while keeping high peak capacity and symmetric sharp peaks. Finally, the quantitative performances were evaluated by the method validation for the quantitative determination of quinine sulfate in a pharmaceutical formulation. These better understandings on critical method parameters led SFC to be an even more promising technique in the field of the analysis of pharmaceutical compounds. [less ▲]

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See detailRewriting History in the Time of Late Capitalism: Uses and Abuses of Built Heritage : introduction to the session
Houbart, Claudine ULg; Dawans, Stéphane ULg

Conference (2016, June 05)

With his expression ceci tuera cela, Hugo established almost two centuries ago a strong link between words and stones as transmission vehicles of human memory. We heritage experts would be inclined to ... [more ▼]

With his expression ceci tuera cela, Hugo established almost two centuries ago a strong link between words and stones as transmission vehicles of human memory. We heritage experts would be inclined to consider stones as more reliable than words, what semiology seems to confirm : stones are clues, and clues are, according to Roland Barthes, tangible proves of “what has been”. But the inspector Columbo has often shown how we can play with these clues, and Umberto Eco would easily forgive us this incursion into mass culture to agree on the idea that we can rewrite history using false justified clues, that is also, tangible heritage. Since the emergence of the restoration discipline, experts have been aware of the danger of falsification : Ruskin’s texts, Boito’s philological restoration, Brandi’s historical instance or the Venice charter are so many illustrations of this concern. But since the 1990’s in Europe, a growing number of restoration and reconstruction projects very clearly depart from this fundamental idea. Of course, the collapse of the Soviet bloc has created a particular political context in which (re-)emerging nations attempted to (re-)build their identity through architectural symbols (leading to the writing of the Riga charter). But more generally, this phenomenon is closely linked to the cultural context : on the one hand, the postmodern movement has deeply questioned the idea of “sincerity”, with a tendency to blur the limits between true and false and, as a consequence, between original and copy. And on the other hand, in the heritage sphere, the globalisation of the debate progressively rattled european certitudes about concepts as essential as authenticity, leading to the replacement of the self-confidence expressed by the Venice charter by a careful relativism, illustrated by the Nara document thirty years later. These contemporary phenomenons have important side effects. In the context of late capitalism, heritage has become a major economic issue, especially as many cities have well understood its potentialities in terms of city branding. This could of course be seen as a positive opportunity for heritage conservation ; nevertheless, a rich scientific literature has shown that tourism can deeply transform our representation of the past. The tourist is a client rather than an amateur, and his quest of authenticity is often satisfied by what the French philosopher Yves Michaud has called “adulterated authenticity”, the one from over-restored monuments, reconstructed city centres, eco-museums, and, why not, theme parks. More than authentic built remains, the “tourist gaze” shapes more and more our representation of “what has been”, and the arguments developed by heritage experts in response to globalisation and identity issues are seized upon by city marketing specialists willing to meet a mostly commercial demand, sometimes tinged with dubious political motivations. What we intend to question in this session is the limit between uses and abuses of heritage and heritage discourse and more particularly whether, as suggested by Theodore Scaltsas’ inspiring paper “Identity, origin and spatiotemporal continuity” (1981), the intentions underpinning restoration and reconstruction projects affect the very essence of restored or reconstructed objects. Besides architectural history and conservation theory, we welcome contributions in the fields of sociology, anthropology, philosophy, history, political sciences, geography, tourism economy and even psychology. [less ▲]

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See detailNumerical Properties of a Discontinuous Galerkin formulation for electro-thermal coupled problems
Homsi, Lina; Geuzaine, Christophe ULg; Noels, Ludovic ULg

in Papadrakakis, M.; Papadopoulos, V.; Stefanou, G. (Eds.) et al Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering, Crete Island, Greece, 5–10 June 2016 (2016, June 05)

Discontinuous Galerkin (DG) methods are attractive tools to integrate several PDEs in engineering sciences, due to their high order accuracy and their high scalability in parallel simulations. The main ... [more ▼]

Discontinuous Galerkin (DG) methods are attractive tools to integrate several PDEs in engineering sciences, due to their high order accuracy and their high scalability in parallel simulations. The main interest of this work is to derive a constant and stable Discontinuous Galerkin method for two-way electro-thermal coupling analyses. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations which are discretized using the Discontinuous Galerkin method. Toward this end, the weak form is written in terms of energetically conjugated fields gradients and fluxes. In order to validate the effectiveness of the formulation and illustrate the algorithmic properties, a numerical test for composite materials is performed. [less ▲]

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See detailLe cadre et l'oubli : Mallarmé après Mallarmé
Durand, Pascal ULg

Conference (2016, June 04)

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See detailHydrogeological assessment of non-linear underground enclosures
Pujades, Estanislao ULg; Jurado Elices, Anna ULg; Carrera, Jesus et al

in Engineering Geology (2016), 207

Excavations below the water table are usually undertaken by combining the protection of retaining walls with dewatering by pumping wells. Severe difficulties may arise if the retaining walls have defects ... [more ▼]

Excavations below the water table are usually undertaken by combining the protection of retaining walls with dewatering by pumping wells. Severe difficulties may arise if the retaining walls have defects. Therefore, their state must be determined and, if needed, the defects repaired or the dewatering system redesigned. The state of underground retaining walls can be evaluated using hydrogeological methods, but these methods are well-established only for linear excavations. The objective of this work is to propose a procedure to evaluate the state of non-linear underground enclosures by analyzing the groundwater response to pumping inside the enclosure. The proposed method, which is based on diagnostic plots (derivative of drawdown with respect to the logarithm of time), allows (1) determining if an underground non-linear enclosure has isolated openings or numerous defects and (2) computing its effective conductance or effective hydraulic conductivity. The methodology is tested with data collected during the excavation of a shaft required for the construction of the high speed train (HST) tunnel in Barcelona, Spain. The procedure can be applied using the wells drilled for dewatering. Although a test before the excavation is recommended to evaluate the underground retaining walls (Watertightness Assessment Test), the method can be applied using data collected at the beginning of the dewatering stage. [less ▲]

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See detailUnveiling the Room-Temperature Magnetoelectricity of Troilite FeS
Ricci, Fabio ULg; Bousquet, Eric ULg

in Physical Review Letters (2016), 116

We report on a first-principles study of the troilite phase of iron sulfide (FeS). We show that even if, a few decades ago, this material was thought to be ferroelectric, the structural transition from ... [more ▼]

We report on a first-principles study of the troilite phase of iron sulfide (FeS). We show that even if, a few decades ago, this material was thought to be ferroelectric, the structural transition from the high P63/mmc to the low P6¯2c symmetry phase does not involve polar instabilities, though the space inversion center symmetry is broken. Our calculations and symmetry analysis nevertheless reveal that FeS is magnetoelectric at room temperature with a response larger than the prototypical room-temperature magnetoelectric crystal Cr2O3. We also show that the spin channel decomposition of the polarization exhibits nonzero values in the opposite direction in FeS, which is actually a general hint of the presence of a magnetoelectric monopole in diagonal magnetoelectrics. [less ▲]

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