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See detailInfluence of the cardiac cycle on time-intensity curves using multislice dynamic magnetic resonance perfusion
NCHIMI LONGANG, Alain ULg; MANCINI, Isabelle; BROUSSAUD, Thomas K. Y.

in International Journal of Cardiovascular Imaging (The) (2014), 30

Flow and pressure variations cause potential changes in magnetic resonance imaging (MRI) signal intensity across the cardiac cycle. Nevertheless, cardiac dynamic contrast-enhanced (perfusion) MRI is ... [more ▼]

Flow and pressure variations cause potential changes in magnetic resonance imaging (MRI) signal intensity across the cardiac cycle. Nevertheless, cardiac dynamic contrast-enhanced (perfusion) MRI is performed and analyzed regardless of the cardiac phase. We investigate whether the cardiac phase impacts myocardial and left ventricle (LV) cavity time intensity curves (TICs) at rest and during vasodilatation. Fifteen healthy volunteers (seven females, eight males; mean age: 32.5 ± 9.3 years; age range: 19–49 years) were included in this prospective study. They underwent four separate short-axis multislice (apical, mid and basal) LV perfusion MRI, with different electrocardiogram-triggering during normal vasotone and adenosine-stress. TIC parameters were extracted from the myocardium and the LV cavity. General linear mixed model analyses were used to evaluate their variability according to vasotone, cardiac phase and slice-position. Maximal enhancement and normalized Steepest slopes were higher at stress than at rest (p values <0.001). A similar trend towards higher inflow was shown on systole versus diastole in the LV cavity and diastole versus systole in the myocardium (p < 0.05).These TIC parameters were slice-position dependent, as the inflow decreased from the base to the apex in the LV, and peaked on the mid-slice for the myocardium. There are significant variability of both the LV and the myocardial TICs, with respect to the cardiac cycle phase and the slice position where imaging actually takes place. These appeal to measurement standardization for a better intra- and inter-study reproducibility. [less ▲]

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See detailThe grassland model intercomparison of the MACSUR (Modelling European Agriculture with Climate Change for Food Security) European knowledge hub
Ma, Shaoxiu; Acutis, Marco; Barcza, Zoltan et al

in Proceedings of the 7th International Congress on Environmental Modelling and Software (iEMSs) June 15-19, 2014, San Diego, California, USA (2014, June)

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See detailSynthèse bibliographique sur la mobilité des éléments traces dans les sols et l’utilisation de la stabilisation physico-chimique comme technique de gestion in situ des sites contaminés
Liénard, Amandine ULg; Colinet, Gilles ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(2), 273-289

Industrial activities have deeply impacted the quality of biophysical environment at places. This review focuses on consequences of soil contaminations by metallic trace elements: what conditions the ... [more ▼]

Industrial activities have deeply impacted the quality of biophysical environment at places. This review focuses on consequences of soil contaminations by metallic trace elements: what conditions the mobility of contaminants in soils and what are the remediation practices based upon physico-chemical stabilization? This technique is an in situ remediation which aims at limiting the dispersion of metals in the environment by use of soil conditioners and amendments in contaminated sites. First of all, we reviewed the concepts of mobility of trace elements and their indicators. Then, we compiled the different kinds of amendments applied to stabilize contaminants in soils and the processes involved. [less ▲]

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See detailL'épidémie au cinéma : de l'infiniment grand à l'infiniment petit
De Re, Margaux ULg

Master's dissertation (2014)

« You know where this comes from, shaking hands? It was a way of showing a stranger you weren't carrying a weapon in the old days. » Contagion, Steven Soderbergh, 2011 For decades film directors, inspired ... [more ▼]

« You know where this comes from, shaking hands? It was a way of showing a stranger you weren't carrying a weapon in the old days. » Contagion, Steven Soderbergh, 2011 For decades film directors, inspired by numerous novelists, have exploited the epidemic in various ways: as a general historical context to tell another story (Isle of the Dead, Robson, 1945), as a medical topic at the heart of an investigation (Medical Investigation, Horwitch, 2004), or as a process allowing the proliferation of zombies (Resident Evil, Anderson, 2000) or even vampires (Daybreakers, Spierig, 2010). This work aims at theorising a fascinating and surprising topic – which goes as far as haunting public restrooms with the “Stop Germs: Wash Your Hands” signs – and to offer an overview of films that are very present on our screens and yet absent from scholarly works about cinema. By combining the analysis of photography with that of narrative, this research tries to address issues which may seem, at first sight, plain and transparent (showing the epidemic is showing contaminated individuals) but prove to be, in practice, much more complex (how can contamination be represented since this microscopic phenomenon is invisible to the eye?). The developed method leans on science and the ties between epidemic, contagion and contamination in order to establish an approach going from the more general (epidemic, which belongs to the global and is illustrated as far as the film’s synopsis) to the more particular (contamination, which falls under the interpersonal and is represented only in precise sequence of the film). Beyond questions about cinema or narrative in the strict sense, this final dissertation aims at exploring the other side of epidemic: the collective imaginary it creates. Indeed, the way cinema represents these phenomena indicates a certain conception of epidemic, which spreads from a film to the other, from a viewer to the other. [less ▲]

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See detailSorting of crop residues and fossil bones from soil by NIR Hyperspectral Imaging
Vincke, Damien; Eylenbosch, Damien ULg; Fernández Pierna, Juan Antonio et al

Conference (2014, June)

The scope of this paper is to present two applications using Near Infrared Hyperspectral Imaging (NIR-HSI) combined with chemometrics to sort constituents of soil and assess their qualitative parameters ... [more ▼]

The scope of this paper is to present two applications using Near Infrared Hyperspectral Imaging (NIR-HSI) combined with chemometrics to sort constituents of soil and assess their qualitative parameters. In the first application, the feasibility of using NIR-HSI to sort crop residues such as roots and straws in soil has been demonstrated. In the second application the potential of such instrumentation and method to assess the level of collagen preservation in fossil bones has been proved. [less ▲]

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See detailPosterior Cingulate Cortex-Related Co-Activation Patterns: A Resting State fMRI Study in Propofol-Induced Loss of Consciousness
Amico, Enrico ULg; Gomez, Francisco; Di Perri, Carol et al

in PLoS ONE (2014), 9

Background: Recent studies have been shown that functional connectivity of cerebral areas is not a static phenomenon, but exhibits spontaneous fluctuations over time. There is evidence that fluctuating ... [more ▼]

Background: Recent studies have been shown that functional connectivity of cerebral areas is not a static phenomenon, but exhibits spontaneous fluctuations over time. There is evidence that fluctuating connectivity is an intrinsic phenomenon of brain dynamics that persists during anesthesia. Lately, point process analysis applied on functional data has revealed that much of the information regarding brain connectivity is contained in a fraction of critical time points of a resting state dataset. In the present study we want to extend this methodology for the investigation of resting state fMRI spatial pattern changes during propofol-induced modulation of consciousness, with the aim of extracting new insights on brain networks consciousness-dependent fluctuations. Methods: Resting-state fMRI volumes on 18 healthy subjects were acquired in four clinical states during propofol injection: wakefulness, sedation, unconsciousness, and recovery. The dataset was reduced to a spatio-temporal point process by selecting time points in the Posterior Cingulate Cortex (PCC) at which the signal is higher than a given threshold (i.e., BOLD intensity above 1 standard deviation). Spatial clustering on the PCC time frames extracted was then performed (number of clusters = 8), to obtain 8 different PCC co-activation patterns (CAPs) for each level of consciousness. Results: The current analysis shows that the core of the PCC-CAPs throughout consciousness modulation seems to be preserved. Nonetheless, this methodology enables to differentiate region-specific propofol-induced reductions in PCC-CAPs, some of them already present in the functional connectivity literature (e.g., disconnections of the prefrontal cortex, thalamus, auditory cortex), some others new (e.g., reduced co-activation in motor cortex and visual area). Conclusion: In conclusion, our results indicate that the employed methodology can help in improving and refining the characterization of local functional changes in the brain associated to propofol-induced modulation of consciousness. [less ▲]

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See detailÉtude des changements de circulation au-dessus de l'océan Austral en été
Belleflamme, Alexandre ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIème colloque de l'Association de Climatologie - Climat : système & interactions (2014, June)

Over the five last decades, the reanalyses (ERA and NCEP/NCAR) show a strengthening of the pressure gradient between the southern hemisphere subtropical anticyclone belt and the southern circumpolar lows ... [more ▼]

Over the five last decades, the reanalyses (ERA and NCEP/NCAR) show a strengthening of the pressure gradient between the southern hemisphere subtropical anticyclone belt and the southern circumpolar lows during summer. With the help of an automatic circulation type classification, we show that the strengthening of the pressure gradient is generalised to all circulation types and, paradoxically, it does not cause circulation changes. It is probably implied by the strengthening of the temperature gradient between the tropics and the South Pole, without consequences on the general circulation. Our classification also allows a successful comparison between the two reanalyses in a region where the observation data are rare. [less ▲]

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See detailPlatelet-rich plasma to treat patellar tendinopathies: a 1 year follow-up.
Kaux, Jean-François ULg; Croisier, Jean-Louis ULg; Bruyère, Olivier ULg et al

in Clinical Chemistry & Laboratory Medicine (2014, June), 52(Special Suppl), 1285

Background: Jumper’s knee is a frequent chronic overuse syndrome of the upper part of the patellar tendon. Platelets contain lots of growth factors which could enhance the healing process of tendons ... [more ▼]

Background: Jumper’s knee is a frequent chronic overuse syndrome of the upper part of the patellar tendon. Platelets contain lots of growth factors which could enhance the healing process of tendons. Infiltration of Platelet Rich Plasma (PRP) may be considered as a recent therapeutic option for chronic tendinopathies. The aim of the current study is to evaluate the clinical status and the return to sports activities in patients with chronic upper patellar tendinopathies up to 1 year after 1 infiltration of PRP. Methods: Twenty patients with chronic upper patellar tendinopathy were enrolled. Assessments were made before infiltration of PRP, and 6 weeks and 3 months and 1 year after the infiltration, using a 10-point Visual Analogic Scale and algofunctional scores (IKDC and VISA-P). Moreover, they had to answer an information questionnaire concerning their life and sports activities. The PRP was obtained with an apheresis system (COM.TEC, Fresenius). Six millilitres of PRP were injected without local anaesthetic. One week after infiltration, patients started a standardised sub-maximal eccentric reeducation. Results: Pain during daily activities significantly decreased with time. VAS has significantly dropped, IKDC and VISA-P significantly improved over the follow-up of 1 year. Seventy percents of patients reported a favourable evolution with decrease of pain, 15% did never report any improvement and 15% were treated surgically. Seventy percents returned to sports activities, 64,3% without any pain, and 50% of them recovered the same sport level. Younger patients seemed to be more susceptible to have an improvement of pain by the PRP infiltration. Conclusions: This study demonstrates that a local infiltration of PRP associated with a submaximal eccentric protocol can improve, at 1 year, symptoms of chronic jumper’s knee in patients non-responsive to classical conservative treatments. [less ▲]

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See detailLes demeures patriciennes à entrée cochère de la paroisse Saint-Martin-en-Île au XVIIIe siècle
Gilles, Isabelle ULg

in Trésor de Liège : Bulletin Trimestriel (2014), 39

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See detailConnaître le passé pour appréhender l'avenir
RADERMECKER, Régis ULg

in Revue de l'Association Belge du Diabète (2014)

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See detailLe potentiel touristique du RAVeL en Wallonie
Evrard, Julien ULg

Master's dissertation (2014)

* Mise en évidence des rôles touristiques et de loisirs des voies vertes, et compréhension des attentes des utilisateurs quant à celles-ci. * Mise en évidence de tronçons RAVeL pouvant être supports ... [more ▼]

* Mise en évidence des rôles touristiques et de loisirs des voies vertes, et compréhension des attentes des utilisateurs quant à celles-ci. * Mise en évidence de tronçons RAVeL pouvant être supports d’activités touristiques par méthodes géomatiques. * Analyse de corrélations entre les fréquentations des RAVeL et ses caractéristiques environnementales : discussion. * Implication : poursuivre la stratégie de développement et la récolte de données statistiques. [less ▲]

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See detailMaison Berhaut-Streel Marchal
Folville, Xavier ULg

in Charlier, Sebastien; Moor, Thomas (Eds.) Guide. Architecture moderne et contemporaine. 1895-2014. Liège (2014)

Notice sur la maison unifamiliale personnelle des architectes Laurent Berhaut-Streel et Florence Marchal. Construction en 1998 à Liège.

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See detailComputational homogenization of cellular materials
Nguyen, Van Dung ULg; Noels, Ludovic ULg

in International Journal of Solids and Structures (2014), 51(11-12), 2183-2203

In this work we propose to study the behavior of cellular materials using a second–order multi–scale computational homogenization approach. During the macroscopic loading, micro-buckling of thin ... [more ▼]

In this work we propose to study the behavior of cellular materials using a second–order multi–scale computational homogenization approach. During the macroscopic loading, micro-buckling of thin components, such as cell walls or cell struts, can occur. Even if the behavior of the materials of which the micro–structure is made remains elliptic, the homogenized behavior can lose its ellipticity. In that case, a localization band is formed and propagates at the macro–scale. When the localization occurs, the assumption of local action in the standard approach, for which the stress state on a material point depends only on the strain state at that point, is no–longer suitable, which motivates the use of the second-order multi–scale computational homogenization scheme. At the macro–scale of this scheme, the discontinuous Galerkin method is chosen to solve the Mindlin strain gradient continuum. At the microscopic scale, the classical finite element resolutions of representative volume elements are considered. Since the meshes generated from cellular materials exhibit voids on the boundaries and are not conforming in general, the periodic boundary conditions are reformulated and are enforced by a polynomial interpolation method. With the presence of instability phenomena at both scales, the arc–length path following technique is adopted to solve both macroscopic and microscopic problems. [less ▲]

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See detailDouble Sweep Preconditioners for propagation problems solved by Optimized Schwarz Methods
Vion, Alexandre ULg; Geuzaine, Christophe ULg

in Proceedings of the 6th International Conference on Advanced COmputational Methods in ENgineering, ACOMEN 2014 (2014, June)

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See detailThe cyclic behaviour of sand, from the Prevost model to offshore geotechnics
Cerfontaine, Benjamin ULg

Doctoral thesis (2014)

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE ... [more ▼]

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE. The first step consists in summarising the salient features of the cyclic behaviour of sand observed in laboratory tests. Undrained monotonic and cyclic experiments are addressed. The phase transformation line is a key parameter in the description of its behaviour. The plasticity effects in both loading and unloading, the progressive pore pressure accumulation coupled with the degradation of the stiffness of the soil are of uttermost importance in the cyclic behaviour. The Prevost model is adopted for its conceptual simplicity and its physically related parameters. The basic equations of the model are described and its variants are illustrated. Calibration of the required parameters is carried out by means of simplified routines implemented in Matlab. A unique set of parameters is determined for each soil at a given relative density. Monotonic experiments are well reproduced. The model also replicates satisfactorily the trend of cyclic experiments. An implicit scheme is embraced in order to implement the model in the finite element code LAGAMINE. The implicit Prager translation rule is adopted for that purpose. It is ensured the discrete formulation reproduces exactly the analytical model. Accuracy, efficiency and robustness of the model are addressed throughout triaxial and multi-axial numerical examples. A hydro-mechanical interface finite element is developed. It consists in a three-node 1D isoparametric element. It is able to reproduce fluid flows across and along the interface. The unsticking of both walls of the interface is coupled with a suction effect due to the filling of the vacuum created. The behaviour of the element is illustrated by simple 1D examples of transient consolidation of a soil column. A final application consists in the modelling of a suction caisson, part of a tripod structure for wind turbines. An axisymmetric representation of this foundation is carried out. It is assumed embedded into dense Lund sand described by the Prevost model. Monotonic and cyclic simulations are performed in both drained and partially drained conditions. The salient features of the resistance of such foundations are highlighted. Their partially drained behaviour strongly increases their transient resistance. A storm including an extreme event is employed to simulate a cyclic loading. A pseudo-random short signal and its sinusoidal equivalent representation finally lead to an identical vertical settlement. This is confirmed by a long duration storm. Finally, a cyclic diagram summarising the final settlement attained for combinations of average and cyclic vertical loads is elaborated. Keywords [less ▲]

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See detailA New Three Object Triangulation Algorithm for Mobile Robot Positioning
Pierlot, Vincent ULg; Van Droogenbroeck, Marc ULg

in IEEE Transactions on Robotics (2014), 30(3), 566-577

Positioning is a fundamental issue in mobile robot applications. It can be achieved in many ways. Among them, triangulation based on angles measured with the help of beacons is a proven technique. Most of ... [more ▼]

Positioning is a fundamental issue in mobile robot applications. It can be achieved in many ways. Among them, triangulation based on angles measured with the help of beacons is a proven technique. Most of the many triangulation algorithms proposed so far have major limitations. For example, some of them need a particular beacon ordering, have blind spots, or only work within the triangle defined by the three beacons. More reliable methods exist; however, they have an increasing complexity or they require to handle certain spatial arrangements separately. In this paper, we present a simple and new three object triangulation algorithm, named ToTal, that natively works in the whole plane, and for any beacon ordering. We also provide a comprehensive comparison between many algorithms, and show that our algorithm is faster and simpler than comparable algorithms. In addition to its inherent efficiency, our algorithm provides a very useful and unique reliability measure, assessable anywhere in the plane, which can be used to identify pathological cases, or as a validation gate in Kalman filters. [less ▲]

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