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See detailTransient Fokker-Planck-Kolmogorov equation solved with smoothed particle hydrodynamics method
Canor, Thomas ULg; Denoël, Vincent ULg

in International Journal for Numerical Methods in Engineering (2013), 94(6), 535553

Probabilistic theories aim at describing the properties of systems subjected to random excitations by means of statistical characteristics such as the probability density function (pdf). The time ... [more ▼]

Probabilistic theories aim at describing the properties of systems subjected to random excitations by means of statistical characteristics such as the probability density function (pdf). The time evolution of the pdf of the response of a randomly excited deterministic system is commonly described with the transient Fokker-Planck-Kolmogorov equation (FPK). The FPK equation is a conservation equation of a hypothetical or abstract fluid, which models the transport of probability. This paper presents a generalized formalism for the resolution of the transient FPK equation using the well-known mesh-free Lagrangian method, Smoothed Particle Hydrodynamics (SPH). Numerical implementation shows notable advantages of this method in an unbounded state space: (i) the conservation of total probability in the state space is explicitly written, (ii) no artifact is required to manage far- eld boundary conditions , (iii) the positivity of the pdf is ensured and (iv) the extension to higher dimensions is straightforward. Furthermore, thanks to the moving particles, this method is adapted for a large kind of initial conditions, even slightly dispersed distributions. The FPK equation is solved without any a priori knowledge of the stationary distribution; just a precise representation of the initial distribution is required. [less ▲]

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See detailPerformance evaluation of methods for correcting ocular artifacts in electroencephalographic (EEG) recordings
Kirkove, Murielle ULg; François, Clémentine ULg; Libotte, Aurélie et al

Scientific conference (2013, February)

The presence of ocular artifacts (OA) due to eye movements and eye blinks is a major problem for the analysis of electroencephalographic (EEG) recordings in most applications. A large variety of methods ... [more ▼]

The presence of ocular artifacts (OA) due to eye movements and eye blinks is a major problem for the analysis of electroencephalographic (EEG) recordings in most applications. A large variety of methods (algorithms) exist for detecting or/and correcting OA’s. We identified the most promising methods, implemented them, and compared their performance for correctly detecting the presence of OA’s. These methods are based on signal processing “tools” that can be classified into three categories: wavelet transform, adaptive filtering, and blind source separation. We evaluated the methods using EEG signals recorded from three healthy persons subjected to a driving task in a driving simulator. We performed a thorough comparison of the methods in terms of the usual performances measures (sensitivity, specificity, and ROC curves), using our own manual scoring of the recordings as ground truth. Our results show that methods based on adaptive filtering such as LMS and RLS appear to be the best to successfully identify OA’s in EEG recordings. [less ▲]

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See detailPyrosequencing of epizootic rabbit enteropathy inocula and rabbit caecal samples.
Huybens, N.; Houeix, J.; Licois, D. et al

in Veterinary Journal (2013), 196

The aetiological agent of epizootic rabbit enteropathy (ERE) is still unknown although a bacterial infection seems the most likely hypothesis. In this study, amplification of the V5 and V6 regions of ... [more ▼]

The aetiological agent of epizootic rabbit enteropathy (ERE) is still unknown although a bacterial infection seems the most likely hypothesis. In this study, amplification of the V5 and V6 regions of 16SrDNA from four virulent and two non-virulent caecal samples was performed using a pyrosequencing platform. The virulent samples did not group in the same cluster. The bacterial flora identified was both different and richer than the cultivable bacterial flora. These findings highlight the need for biomolecular techniques to identify the aetiological agent of ERE. [less ▲]

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See detailMeasurement of serum albumin by protein electrophoresis and bromocresol green methods in canine and equine patients
Ramery, Eve ULg; Bureau, Fabrice ULg

in Veterinary Clinical Pathology (2012, December), 41(4), 5

Background: Bromocresol green method (BCG) is routinely used in veterinary laboratories to measure albumin. A good agreement between BCG and electrophoresis (SPE) in healthy domestic animals is reported ... [more ▼]

Background: Bromocresol green method (BCG) is routinely used in veterinary laboratories to measure albumin. A good agreement between BCG and electrophoresis (SPE) in healthy domestic animals is reported. However, in human medicine, at low albumin and high globulin concentrations, BCG also binds to α- and β-globulins fractions. Surprisingly, there is no recent literature evaluating the BCG method in diseased domestic animals. Objective: The purpose of the present study was therefore to compare the serum albumin values obtained by SPE and BCG in canine and equine patients. Methods: Albumin measured by BCG and SPE was compared in the serum from 30 canine and 30 equine patients. Results: Good correlation was found (Spearman´s rho rs = 0.91 in dogs and 0.84 in horses). However, Altman and Bland analysis of results showed a positive bias of BCG with SPE (3.41 g/l in horses and 0.41 g/l in dogs) that increased when only hypoalbuminemic patients were considered (4.17 g/l in horses and 1.31 g/l in dogs). Conclusion: Results confirm that, despite good correlation, BCG method tends to overestimate albumin, especially in hypoalbuminemic patients. This is particularly evident in horses. [less ▲]

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See detailI-see-3D! An Interactive and Immersive System that dynamically adapts 2D projections to the location of a user’s eyes
Pierard, Sébastien ULg; Pierlot, Vincent ULg; Lejeune, Antoine ULg et al

in International Conference on 3D Imaging (IC3D) (2012, December)

This paper presents a system that gives the illusion of a 3D immersive and interactive environment with 2D projectors. The user does not need to wear glasses, nor to watch a (limited) screen. The virtual ... [more ▼]

This paper presents a system that gives the illusion of a 3D immersive and interactive environment with 2D projectors. The user does not need to wear glasses, nor to watch a (limited) screen. The virtual world is all around him, drawn on the floor. As the user is himself immersed in the virtual world, there is no need for a proxy like an avatar; he can move inside the virtual environment freely. Moreover, the Isee-3D system allows a user to manipulate virtual objects with his own body, making interactions with the virtual world very intuitive. Giving the illusion of 3D requires to render images insuch a way that the deformation of the image projected on thefloor is taken into account, as well as the position of the user’s “eye” in its virtual world. The resulting projection is neither perspective nor orthographic. Nevertheless, we describe how thiscan be implemented with the standard OpenGL pipeline, without any shader. Our experiments demonstrate that our system is effective in giving the illusion of 3D. Videos showing the results obtained with our I-see-3D system are available on our website http://www.ulg.ac.be/telecom/projector [less ▲]

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See detailReconstitution of the Journeys to Crime and Location of Their Origin in the Context of a Crime Series. A Raster Solution for a Real Case Study
Kasprzyk, Jean-Paul ULg; Trotta, Marie ULg; Donnay, Jean-Paul ULg et al

in Leitner, Michael (Ed.) Crime Modeling and Mapping Using Geospatial Technologies (2012)

In the region of Charleroi (Belgium), a series of criminal acts were committed by the same group, using the same vehicle. The events were located in space and time. The car used during these criminal ... [more ▼]

In the region of Charleroi (Belgium), a series of criminal acts were committed by the same group, using the same vehicle. The events were located in space and time. The car used during these criminal activities was stolen (first event) and was later retrieved (last event) after a period of 4 days of offences. Police recorded a crucial clue: the total mileage covered by the vehicle between the first and the last event was estimated with an admissible approximation. Thanks to this information, we were able to choose the most probable journey-to-crime among several scenarios. These depended on the combination of cost surfaces built with distance propagation algorithms starting from each criminal event in raster mode. The distance propagations were limited to the road network and the combinations of the cost surfaces had to respect the chronology of the facts. The most plausible scenario suggested that the criminals hided the car into a withdrawal site between their activities. In order to improve the precision of the location of this withdrawal site, we used a multi-criteria analysis taking account of the journey of the vehicle and other environment variables. At the end of these treatments, the small stretch of road that we isolated actually included the withdrawal site, as confirmed by the police later [less ▲]

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See detailWhy bother ?
Nazé, Yaël ULg; Bouquiaux, Laurence ULg

Poster (2012, November 27)

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See detailHippocrate dans un monde de chrétiens : la réception des traités hippocratiques dans la chôra égyptienne à la période byzantine (284-641)
Marganne, Marie-Hélène ULg

Conference (2012, November 09)

Dans le cadre d'une recherche sur la réception des œuvres des auteurs de l’antiquité classique dans l’Égypte christianisée, on examine les témoignages papyrologiques de la période byzantine relatifs aux ... [more ▼]

Dans le cadre d'une recherche sur la réception des œuvres des auteurs de l’antiquité classique dans l’Égypte christianisée, on examine les témoignages papyrologiques de la période byzantine relatifs aux traités hippocratiques, leur texte, leur mise en texte et leur contexte, en vue, non seulement de définir leur spécificité par rapport aux autres papyrus grecs médicaux et aux papyrus iatro-magiques de la même époque, mais aussi d’y déceler des traces éventuelles de copie ou d’utilisation en contexte chrétien. [less ▲]

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See detailIs there a relationship between perseverations and spatial short-term memory deficits in unilateral neglect?
Wansard, Murielle ULg; Bartolomeo, Paolo; Gillet, Sophie ULg et al

in Abstract Book Belgian Brain Congress (2012, October 27)

Introduction Spatial neglect is a multicomponent syndrome characterized by an inability to orient or to respond to stimuli arising in the hemispace contralateral to a brain lesion. According to many ... [more ▼]

Introduction Spatial neglect is a multicomponent syndrome characterized by an inability to orient or to respond to stimuli arising in the hemispace contralateral to a brain lesion. According to many authors, spatial neglect can be explained by an attentional deficit, and more specifically by a lateral attentional bias towards the right (magnetic attraction) and/or difficulties in disengaging attention from items to the right side. However, attentional theories are not sufficient to explain some behaviors such as revisiting and perseverations. Recently, it has been suggested that revisiting and perseveration behaviors in visual search tasks shown in parietal neglect could be related to impairments in visuo-spatial working memory (Husain et al., 2001; Malhotra et al., 2005; Malhotra, Mannan, Driver, & Husain, 2004). This hypothesis is supported by studies (1) in which a contrast is made between cancellation tasks with and without visual control, the absence of visual feedback increasing left neglect (omissions) and repeated cancellations (perseverations) towards the ipsilesional space, and (2) in which the Corsi test is administrated in a vertical way. However, Ronchi et al. (2009) did not confirm the link between impairments in spatial short-term memory and perseverations. Indeed, these authors found no correlation between perseverations in star cancellation and spatial memory performance in the Corsi test. Nevertheless, they did not use a condition without visual feedback, which is considered as involving more spatial short-term memory than a condition with visual feedback. This methodological choice could explain the lack of relationship between short-term memory and perseverations in the Ronchi et al.’s study. The purpose of our study was to test the hypothesis of a spatial short-term memory deficit being an explanatory factor of perseverations in unilateral neglect. Methods We assessed twenty right-damaged patients suffering from left neglect. Neglect signs were evaluated with the Batterie d’Evaluation de la Négligence (BEN) (Azouvi et al., 2002). Twenty healthy older participants matched for age and sociocultural level served as controls. In order to explore the relationship between perseverations and spatial short-term memory, two different tasks were administrated: a computerized version of the Corsi test and a cancellation task. All tests were computerized and presented on a touchscreen. The subject’s spatial span corresponded to the longest sequence in which at least three out of four sequences were correctly reproduced. The cancellation task consisted of 32 “O” presented in two conditions: with (visible) and without (invisible) visual feedback. Patients were instructed to cancel out all targets only once. The number of omissions and perseverations was calculated for each participant in both conditions. Results Control participants performed better than neglect patients in the Corsi test; eleven neglect patients showed a deficit in spatial short-term memory. In the cancellation tasks, Wilcoxon matched-pairs signed ranks tests highlighted that perseverations and omissions were greater in the invisible condition for each group. In this condition, neglect patients made more omissions and perseverations (all ps <.05) than control subjects, while in the visible condition there was only a significant difference for the omissions. However, spatial short-term memory did not explain perseverations in invisible condition (R² = .17, F(1,18) = 3.66, p = .07). Discussion These findings suggest that a spatial short-term memory deficit cannot be considered as an explanatory factor for the perseveration behavior in unilateral neglect. Moreover, perseverations and omissions were greater in the invisible condition than in the visible one; therefore, the hypothesis of the magnetic attraction is not confirmed either. In the neglect patients’ group, the visual feedback decreases, and even eliminates the neglect symptoms (omissions and perseverations) compared to the invisible condition. In other words, the presence of visual feedback can help patients to explore their visual environment. We propose that, in the invisible condition, difficulties to plan a visual search could exacerbate both omissions and perseverations, leading to recursive search towards the right side of the space and thus promote failure to explore left space. However, further investigations will be necessary to confirm this hypothesis. [less ▲]

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See detailA computationally efficient algorithm for the provision of a day-ahead modulation service by a load aggregator
Mathieu, Sébastien ULg; Karangelos, Efthymios ULg; Louveaux, Quentin ULg et al

Poster (2012, October 08)

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service ... [more ▼]

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service consisting of a load modulation option, which can be called by the TSO once per day. The option specifies the maximum amplitude of a potential modification on the demand of the loads within a certain time interval. We consider the specific case where the loads can be modeled by a generic tank model whose inflow depends on the power consumed by the load and outflow is assumed to be known the day before for every market period. The level of the reservoir at the beginning of the market day is also assumed to be known. We show that, under these assumptions, the problem of maximizing the amplitude of the load modulation service can be formulated as a mixed integer linear programming problem (MILP). In order to solve this problem in a computationally efficient manner we introduce a novel heuristic-method. We test this method on a set of problems and demonstrate that our approach is orders of magnitude faster than CPLEX - a state-of-the-art software for solving MILP problems - without considerably compromising the solution accuracy. [less ▲]

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See detailThe x-ray microcalorimeter spectrometer onboard Athena
den Herder, J. W.; Bagnali, D.; Bandler, S. et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2012, September 01)

One of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter ... [more ▼]

One of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high-spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor (TES) and absorbers that consist of metal and semi-metal layers and a multiplexed SQUID readout. The array (32 x 32 pixels) provides an energy resolution of < 3 eV. Due to the large collection area of the Athena optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. Compared to the requirements for the same instrument on IXO, the performance requirements have been relaxed to fit into the much more restricted boundary conditions of Athena. In this paper we illustrate some of the science achievable with the instrument. We describe the results of design studies for the focal plane assembly and the cooling systems. Also, the system and its required spacecraft resources will be given. [less ▲]

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See detailLocalisation des centres de radiothérapie : une analyse géographique exploratoire pour la Belgique
COTTEELS, C.; PEETERS, D.; COUCKE, Philippe ULg et al

in Cancer Radiotherapie (2012), 16(7), 604612

Purpose The distance between the patient's home and a radiotherapy department may represent a hurdle for the patient and influence treatment choice. Therefore, it is necessary to check whether the ... [more ▼]

Purpose The distance between the patient's home and a radiotherapy department may represent a hurdle for the patient and influence treatment choice. Therefore, it is necessary to check whether the geographical distribution of radiotherapy centers is in accordance with cancer incidence, taking also into account the cost of travelling to the radiotherapy department. The objective of this study is double; first, to map the current locations of radiotherapy centers across the country and second, to evaluate the observed spatial disparities with appropriate tools. Materials and methods A model of operational research (P-median) is used to suggest the optimal locations and allocations and to compare them with the current situation. This is an exploratory study with simple inputs. It helps to better understand the current geographical distribution of radiotherapy centers in Belgium as well as its possible limitations. Results–conclusion It appears that the current situation is on the average acceptable in terms of accessibility to the service and that the method presents huge potentialities for decision making so as to yield a spatial system that is both efficient and equitable. [less ▲]

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See detailImpact des déficits cognitifs dans les activités de la vie quotidienne des personnes souffrant de schizophrénie
Levaux, Marie-Noëlle ULg; Danion, Jean-Marie

in Annales Médico-Psychologiques (2011), 169

It is now well recognized that cognitive dysfonctions contribute to a decisive way to the difficulties of the everyday, social and professional life of the people with schizophrenia. The cognitive ... [more ▼]

It is now well recognized that cognitive dysfonctions contribute to a decisive way to the difficulties of the everyday, social and professional life of the people with schizophrenia. The cognitive variables would explain between 16 and 30 % of the variance in the functional status when assessed one to three and a half years later. However, the specificity of the complex relationships between the cognitive domains and the functional variables still remain to identify. To this end, it is necessary to carry out studies by respecting various principles: 1. Selecting not multi-determined cognitive tasks; 2. Investigating specific daily-life tasks (e.g. shopping, choosing a menu, preparing a meal), in particular by an observation in real situation in order to identify the problematic components; this has to be made by determining a priori hypotheses regarding the cognitive nature of the difficulties; 3. Taking into account the heterogeneity of the cognitive deficits and the functional difficulties of people with schizophrenia. It also remains to investigate the presence of mediator variables of the relationships, such as the potential of learning, the social cognition, the metacognitive processes and the intrinsic motivation. Besides, other personal or environmental factors can also play a role in the functional status as for example, the negative symptoms, the awareness that has the person of his(her) state and its consequences, or the critical attitude of relatives towards the person with schizophrenia. [less ▲]

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See detailRemédiation cognitive des patients schizophrènes dans les pays francophones
Levaux, Marie-Noëlle ULg; Laroi, Frank ULg; Danion, Jean-Marie et al

in EMC, Psychiatrie (2009)

La schizophrénie est associée à des déficits cognitifs variés qui affectent les capacités fonctionnelles des patients : relations sociales, insertion professionnelle, activités de la vie quotidienne. Les ... [more ▼]

La schizophrénie est associée à des déficits cognitifs variés qui affectent les capacités fonctionnelles des patients : relations sociales, insertion professionnelle, activités de la vie quotidienne. Les troubles cognitifs interviennent également dans le développement de certains types de symptômes cliniques (délires, hallucinations). Pour faire face à ces déficits, une prise en charge de type cognitif a vu le jour et différents programmes ont été développés. Cette revue de la littérature décrit les programmes de remédiation cognitive utilisés dans les pays francophones. Des résultats prometteurs en termes d’amélioration des fonctionnements cognitif et psychosocial ont été obtenus. Cependant, pour la plupart de ces programmes, des études de validation et d’évaluation de l’efficacité à long terme sont encore à réaliser. Plusieurs recommandations sont énoncées pour les études futures, en particulier dans le but d’améliorer la généralisation des effets de la remédiation cognitive au fonctionnement dans la vie quotidienne. [less ▲]

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