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See detailEvaluation of Non-negative matrix Factorization of grey matter in age prediction
Varikuti, Deepthi; Genon, Sarah ULiege; Sotiras, Aristeidis et al

Poster (2017, June)

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such ... [more ▼]

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such brain-based prediction of phenotypical characteristics to counter the curse of dimensionality associated with voxel-wise analysis. While previous age-predictions have employed PCA based compression, non-negative matrix factorization (NNMF) has recently been suggested as a plausible factorization of high-dimensional VBM data [4]. Non-negativity and sparsity of the components obtained from NNMF facilitate relatively more optimal solution than the PCA based compression [4]. Here, we evaluate, i) whether NNMF compression allows predictions of biological age that reproduce those from previously reported analyses [2], ii) the impact of the NNMF’s granularity on the prediction accuracy, iii) the possible effect of the factorizations derived from different datasets on the prediction, and iv) whether explicit adjustment can address the model bias inherent to many brain-based predictions. Methods: VBM8 preprocessing (using only non-linear modulation and 8 mm FWHM smoothing [3]) was used to compute voxel-wise GM volumes for two datasets, 1) 693 healthy older adults (age: 55-75 years) scanned at a single site (“1000BRAINS) [1], 2) 1084 healthy adults (age: 18-81 years), scanned at multiple sites (“Mixed”) (Fig 1A). NNMF solutions for both groups were derived at different levels of granularity. Age prediction was performed by fitting LASSO regression models either on the coefficient matrix from the respective NNMF or by those that were derived from projecting a group’s data on the respective other groups components. Model generalization was evaluated by 10-fold cross-validation replicated 25 times. To address the known bias towards the mean, i.e., overestimation of young and underestimation of older subjects, we additionally tested models that explicitly fitted the regression-slope between the real and predicted training set and used this to adjust the expected slope of the test set to 45 degrees. Results: In both datasets, NNMF components resembled neurobiologically reasonable patterning of the brain (Fig 1B). Prediction accuracy based on the projection of data on the components from either group was virtually identical (Fig 2A). For both datasets, mean absolute errors (MAE) declined with higher granularity of the components and reached values well comparable to previous approaches even when using components derived from an independent sample (MAE: 3.6 years for 1000BRAINS; 6.4 years for Mixed). Plotting the prediction error relative to the biological age of the subjects revealed the bias towards the mean across both datasets (Fig 2B). Adjusting for the slope estimated in the training set allows removing this bias, though it needs to be noted that this comes at the cost of reduced precision, i.e., unbiased estimates yield a slightly higher MAE. Conclusion: NNMF allows the definition of co-variation patterns in VBM data. Due to the non- negativity and sparseness, NNMF enable substantially easier and higher biological interpretation than other methods for data compression such as PCA [4]. We showed that NNMF compression of VBM data over the lifespan allows predicting previously unseen subjects’ age with a precision that is comparable to earlier reports using PCA for data compression [2], while offering the potential for neurobiological interpretation. Importantly, accuracy seems to be independent of whether the components were derived from the same dataset or from a dataset that is not only independent but also different in age distribution. We note that accuracies tend to continuously decrease with higher granularity, although performance tends to plateau at about 300 components. Finally, adjusting the inherent bias of sparse regression models yields unbiased out-of-sample predictions but comes at the expense of slightly higher mean errors. [less ▲]

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See detailProfiling inferior left dorsal premotor cortex: when Area 55b meets Premotor Eye-Field
Genon, Sarah ULiege; Reid, Andrew; Langner, Robert et al

Poster (2017, June)

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See detailRegistered partnerships
Wautelet, Patrick ULiege

in Basedow, Jürgen; Ferrari, Franco; de Miguel Asensio, Pedro (Eds.) et al EUROPEAN ENCYCLOPEDIA OF PRIVATE INTERNATIONAL LAW (2017)

This entry in the European Encyclopedia of Private International Law attempts to present the current state of the law in relation to registered partnerships. After an overview of the relevant sources ... [more ▼]

This entry in the European Encyclopedia of Private International Law attempts to present the current state of the law in relation to registered partnerships. After an overview of the relevant sources, attention is paid to the issue of characterization. The law applicable to the access to partnerships and effects of such partnerships is also covered. [less ▲]

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See detailA decision support tool for transient stability preventive control
Pertl, Michael; Weckesser, Johannes ULiege; Rezkalla, Michel et al

in Electric Power Systems Research (2017), 147

The paper presents a decision support tool for transient stability preventive control contributing to increased situation awareness of control room operators by providing additional information about the ... [more ▼]

The paper presents a decision support tool for transient stability preventive control contributing to increased situation awareness of control room operators by providing additional information about the state of the power system in terms of transient stability. A time-domain approach is used to assess the transient stability for potentially critical faults. Potential critical fault locations are identified by a critical bus screening through analysis of pre-disturbance steady-state conditions. The identified buses are subject to a fast critical contingency screening determining the actual critical contingencies/buses. These two screenings aim at reducing the computational burden of the assessment, since only contingencies considered as critical are taken into account. The critical clearing times for the critical contingencies are determined. A preventive re-dispatch of generators to ensure a predefined minimum critical clearing time for faults at all buses is proposed, while costs are minimized. The results of the assessment are presented to the control room operator, who decides to accept the suggested dispatch or to repeat the assessment considering additional user-specific constraints. The effectiveness of the proposed method is demonstrated on a standard nine-bus and the New England test system. [less ▲]

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See detailInitiatives et mécanismes correcteurs
Guisset, AL; Dispas, H; Meunier, P et al

in Santé Conjuguée (2017), 79

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See detailNumerical modelling of micro-plasto-hydrodynamic lubrication in plane strip drawing
Carretta, Yves ULiege; Bech, Jakob; Legrand, Nicolas et al

in Tribology International (2017), 110

This paper presents a new finite element model capable of predicting the onset of micro-plasto-hydrodynamic (MPH) lubrication and the amount of lubricant escaping from surface pockets in metal forming ... [more ▼]

This paper presents a new finite element model capable of predicting the onset of micro-plasto-hydrodynamic (MPH) lubrication and the amount of lubricant escaping from surface pockets in metal forming. The present approach is divided in two steps. First, a simulation at the macroscopic level is conducted. Then, a second simulation highlighting microscopic liquid lubrication mechanisms is achieved using boundary conditions provided by the first model. These fluid-structure interaction computations are made possible through the use of the Arbitrary Lagrangian Eulerian (ALE) formalism. The developed methodology is validated by comparison to experimental measurements conducted in plane strip drawing. The effect of physical parameters like the drawing speed, the die angle and the strip thickness reduction is investigated. The numerical results show good agreement with experiments. [less ▲]

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See detailApproche intégrée de l’éthique et l’intégrité scientifique à l’Université de Liège
Halleux, Isabelle ULiege

Scientific conference (2017, June)

This talk was presented to the boards of French universities in order to share the Ulg model and good practices in ethics. The integrated approach includes actions coordinated by the Council for Ethics ... [more ▼]

This talk was presented to the boards of French universities in order to share the Ulg model and good practices in ethics. The integrated approach includes actions coordinated by the Council for Ethics and Scientific Integrity (CEIS) which are developed simultaneously through 5 axes. Researchers are involved at all levels of the process, directly or as representative of their group. 1. Training: Sensitization and education to ethics; development of professional capacities, incl. data analysis & open data; seminaries with supervisors and PhDs ("duos") 2. Forum: ethics on the public space – Seminaries, conference, round tables, intervision, discussion and exchange on questions, dilemma, case-studies, with the help of external experts 3. Research appraisal: requirement for an ethics appraisal of each research project, with a special focus on human and social sciences, with the help of disciplinary ethics committees 4. Ethics analysis: Analysis of special questions, complains, problems, and decision making in case of violation of integrity 5. Regulation: Writing of procedures, dissemination of documents, recommendations and case-studies, link to the HR Strategy for researchers and the Charter and Code. This presentation aimed to exchange about what was done, the actual and expected impact of actions, what is going right and wrong, and how ULg is managing this dynamics as part of the HR Strategy for researchers project. [less ▲]

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See detailChallenges of Trace Mineral Diagnosis
Guyot, Hugues ULiege

in ACVIM Forum Proceedings (2017, June)

Trace elements deficiencies are commonly seen in cattle herds in Europe and in some parts of the USA. Many reasons are involved: economics of the cattle industry, nutrients formulation and legislation ... [more ▼]

Trace elements deficiencies are commonly seen in cattle herds in Europe and in some parts of the USA. Many reasons are involved: economics of the cattle industry, nutrients formulation and legislation, depletion of soil and roughages quality. The clinical signs of the deficiencies are rarely pathognomonic but loss of production, impaired reproduction performances or increased morbidity/mortality rates are mostly observed. In a European critical economic context, especially for milk production, it is not easy to convince the farmer to invest in diagnosis and/or trace mineral supplementation. Nevertheless, it is important to investigate the nutritional status of the herd to improve global herd health. This presentation aims to present the interest of the diagnosis of trace mineral deficiencies as well as the different manners to investigate this nutrition trouble at a herd level. Trace mineral supplementation solutions will be briefly discussed. [less ▲]

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See detailThe Use of Inflammatory Markers in Field Cattle Medicine
Guyot, Hugues ULiege

in ACVIM Forum Proceedings (2017, June)

Numerous cow-side diagnostic tests are available for bovine practitioners. Many of these tests serve etiologic purposes such as quick test for diarrhea or measures of metabolites directly linked to ... [more ▼]

Numerous cow-side diagnostic tests are available for bovine practitioners. Many of these tests serve etiologic purposes such as quick test for diarrhea or measures of metabolites directly linked to pathologies (BOH or ions Ca++, Na+, K+, etc.). Beside these interesting elements, inflammation, which is either a cause or a consequence of a specific disease, is often forgotten. This presentation will refresh the practitioner’s knowledge on the assessment of inflammation in cattle by using inflammatory markers assayed with laboratory and cow-side tests. The interpretation of these markers can be sometimes delicate (bias) and might not necessarily lead to a prognosis. Depending on the age of the animal, some inflammatory markers can also serve as diagnosis for other purposes such as the evaluation of passive immunity transfer in calves. [less ▲]

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See detailEnvironmental Protection and Tax Law: Belgian approach to the development of renewable energy and sustainable transport
Vanrykel, Fanny ULiege

Scientific conference (2017, June)

In the relation between human kind and nature, humans are often the strong and the environment the weak. Humans destroy animals’ habitat, affect biodiversity and cause climate change. By their behaviors ... [more ▼]

In the relation between human kind and nature, humans are often the strong and the environment the weak. Humans destroy animals’ habitat, affect biodiversity and cause climate change. By their behaviors, they also threaten future generations. Progressively, the law has started to regulate this relation and environmental law has emerged. Quickly, taxes and tax incentives have been considered a useful mean to achieve environmental protection. This contribution tells the story of how taxes and tax incentives have been used in Belgium to influence human behaviors towards a greater protection of the environment. In particular, it addresses the issue of climate change, by focusing on two aspect of this question: the development of renewable energy and sustainable transport. It is divided in two parts. The first one presents the current tax measures in relation with this question while the second one deals with their ability to achieve their goal. [less ▲]

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See detailNew data on the Mesozoic radiation of chelonioids
Scavezzoni, Isaure ULiege; Fischer, Valentin ULiege

Poster (2017, June)

"Turtles" (Testudines) form a successful group of reptiles with several terrestrial, marine and fresh-water species. Their peculiar and somewhat constrained morphology (i. e. : carapace incorporating ribs ... [more ▼]

"Turtles" (Testudines) form a successful group of reptiles with several terrestrial, marine and fresh-water species. Their peculiar and somewhat constrained morphology (i. e. : carapace incorporating ribs, curved limbs, anapsid skull exempt of temporal fenestrae) and ecology has often obscured their relationships and, hence, their evolutionary history, notably in marine turtles (chelonioids). Modern chelonioids are divided in two clades (i. e. : shoft-shelled turtles and hard-shelled turtles) supported by distinct morphological and embryological characters. Their origin is traced back up to the Cretaceous, along with a series of extinct forms, many of which being collectively known as Protostegidae. Fossil evidence show that at least five clades of marine turtles were roaming the seas at the end of the Cretaceous. In fact, chelonioids appeared during the first stages of the Early Cretaceous and quickly exploded to reach a high level of disparity at the lowermost part of the late Cretaceous. Therefore, the Mesozoic radiation of chelonioids must have happened during the "middle" Cretaceous (especially the Aptian-Albian interval). However this radiation is poorly understood as the phylogenetic relationships of marine turtles are not resolved yet. Bringing new data may help resolve these issues, and it is the exact reason why the genus Rhinochelys is being investigated. [less ▲]

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See detailHic Sunt NATs: Uncovering Address Translation with a Smart Traceroute
Zullo, Raffaele; Pescapé, Antonio; Edeline, Korian ULiege et al

in IEEE/IFIP Workshop on Mobile Network Measurement (MNM) (2017, June)

Middleboxes are pervasive in today's Internet as they are deployed for an increasing number of reasons. An example is the network address translation (NAT), one of the first task to be performed to cope ... [more ▼]

Middleboxes are pervasive in today's Internet as they are deployed for an increasing number of reasons. An example is the network address translation (NAT), one of the first task to be performed to cope with the lack of IPv4 addresses. Recently the landscape for NATs has become even more crowded, especially in mobile networks, mainly due to the impossibility of IPv6 to be a large-scale solution to addressing issues. In this paper, we present a novel methodology for detecting NATs embodied in Mobile Tracebox, a measurement tool for Android smart devices that detects a wide range of middleboxes. It analyzes ICMP time-exceeded messages received during \traceroute and points at IP and transport checksum inconsistencies in the embedded packets to uncover address translation along a path. We deployed Mobile Tracebox through a crowdsourcing approach and used the collected dataset to validate our methodology. Results showed that, in absence of middleboxes breaking \traceroute, it can help to detect and locate NATs in the majority of the cases. [less ▲]

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See detailReal-time capture of the folding-unfolding transitions in a single oligorotaxane foldamer
Sluysmans, Damien ULiege; Hubert, Sandrine ULiege; Bruns, Carson et al

Poster (2017, June)

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See detailLe cas clinique du mois. Embolie pulmonaire compliquée d’un œdème laryngé angioneurotique.
LOPEZ IGLESIAS, Raphaelle ULiege; CUPPENS, Benoit ULiege; ROBINET, Sébastien ULiege et al

in Revue Médicale de Liège (2017), 72(6), 275-280

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See detailTowards a Renewed Alias Resolution with Space Search Reduction and IP Fingerprinting
Grailet, Jean-François ULiege; Donnet, Benoît ULiege

in Network Traffic Measurement and Analysis Conference (TMA) (2017, June)

Since the early 2000's, the Internet Topology has been frequently described and modeled from the perspective of routers. To this end, alias resolution mechanisms have been developed in order to aggregate ... [more ▼]

Since the early 2000's, the Internet Topology has been frequently described and modeled from the perspective of routers. To this end, alias resolution mechanisms have been developed in order to aggregate all IP interfaces of a router, collected with traceroute, into a single identifier. So far, many active measurement techniques have been considered, often taking advantage of specific features from network protocols. However, a lot of these methods have seen their efficiency decrease over time due to security reinforcements across the Internet. In this paper, we introduce a generic methodology to conduct efficient and scalable alias resolution. It combines the space search reduction of TreeNET (a tool for efficiently discovering subnets) with a fingerprinting process used to assess the feasibility of several state-of-the-art alias resolution methods, using a small, fixed amount of probes. We validate our method along MIDAR on an academic groundtruth and demonstrate that our methodology can achieve similar accuracy while using less probes and discovering subnets in the process. We further evaluate our method with measurements made on PlanetLab towards several distinct ASes of varying sizes and roles in the Internet. The collected data shows that some properties of our fingerprints correlate with each other, hinting some observed profiles could be linked with equipment vendors. Both TreeNET (which implements our methodology) and our dataset are freely available. [less ▲]

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See detailShallow water model with anisotropic porosity for flood modelling on Cartesian grids
Bruwier, Martin ULiege; Archambeau, Pierre ULiege; Erpicum, Sébastien ULiege et al

Conference (2017, June)

Detailed topographic data have become widely available for inundation mapping. While the use of such high-resolution data enables the computation of flow variables at a fine scale, the computation time ... [more ▼]

Detailed topographic data have become widely available for inundation mapping. While the use of such high-resolution data enables the computation of flow variables at a fine scale, the computation time remains too high for many practical applications. In contrast, models solving the shallow-water equations with porosity provide a useful tool to improve the computational efficiency, while preserving to some extent the detailed topographic information through porosity parameters. In this study, we present a new model solving the fully dynamic shallow water equations with anisotropic porosity based on Cartesian grids. Using a Cartesian grid leads to specific challenges, particularly as regards the definition of the conveyance porosities at the cell edges. Moreover, the presented model is further improved by a merging method so as to increase the computational efficiency without affecting the overall accuracy. The performance of the model has been evaluated based on a wide range of test cases, which confirm the validity of the model and the benefits of such a modelling framework. [less ▲]

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See detailOn the transition between symmetric ans asymmetric flow in rectangular shallow reservoirs - a case of maximum energy dissipation?
Westhoff, M.C.; Erpicum, Sébastien ULiege; Archambeau, Pierre ULiege et al

Conference (2017, June)

Shallow reservoirs are often used in hydraulic engineering as sediment traps or storage basins. For short rectangular reservoirs, the main jet flows straight from the inlet to the outlet with on both sides ... [more ▼]

Shallow reservoirs are often used in hydraulic engineering as sediment traps or storage basins. For short rectangular reservoirs, the main jet flows straight from the inlet to the outlet with on both sides symmetric recirculation zones. In longer reservoirs, however, the main jet reattaches to the side of the reservoir leading to a small and a large recirculation zone. Previous studies have found an empirical geometric relation describing the switch between these two flow pattems. In this study, we demonstrate with a simple analytical model, that this switch in flow pattem coincides with a maximization of energy dissipation in the shear layer between the main jet and the recirculation zones. We show that for short reservoir lengths, energy dissipation is higher in the case of a symmetric fiow pattern, while for longer reservoir the energy dissipation is higher for asymmetric flow pattems. The simulated switch between the two flow patterns appears to be very close to the empirical relation. The strength of this approach lies in the fact that no detailed knowledge of small scale processes is needed, which may prove useful at an early stage of reservoir design. [less ▲]

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See detailFE modeling of the cooling and tempering steps of bimetallic rolling mill rolls
Neira Torres, Ingrid; Gilles, Gaëtan ULiege; Tchuindjang, Jérôme Tchoufack ULiege et al

in International Journal of Material Forming (2017), Volume 10,(Issue 3), 287305

Numerical simulations enable the analysis of the stress and strain histories of bimetallic rolling mill rolls. The history of rolling mill rolls is simulated by thermo-mechanical metallurgical finite ... [more ▼]

Numerical simulations enable the analysis of the stress and strain histories of bimetallic rolling mill rolls. The history of rolling mill rolls is simulated by thermo-mechanical metallurgical finite element code while considering two steps: post-casting cooling and subsequent tempering heat treatment. The model requires a notably large set of material parameters. For different phases and temperatures, Young modulus, yield limit and tangent plastic modulus are determined through compression tests. Rupture stresses and strains are obtained by tensile tests. Thermo-physical parameters are measured by such experimental methods as dilatometry, DSC (Differential Scanning Calorimetry) and Laser Flash methods. Such parameters as the transformation plasticity coefiicients for the ferrite, pearlite and martensite phases are identified through an inverse method. From the simulation results, the profile of the stresses evolution at different critical times is presented. An analysis of the potential damage is proposed by comparing the predicted axial stress \vith rupture stresses. The perspective of the Ghosh and McClintock damage criteria is also investigated. [less ▲]

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See detailMapping Soil Organic Carbon stocks and estimating uncertainties at the regional scale following a legacy sampling strategy (Southern Belgium, Wallonia)
Chartin, Caroline; Stevens, Antoine; Goidts, Esther et al

in Geoderma Regional (2017), 9

The quantification and the spatialisation of reliable SOC stocks (Mg C ha− 1) and total stock (Tg C) baselines and associated uncertainties are fundamental to detect the gains or losses in SOC, and to ... [more ▼]

The quantification and the spatialisation of reliable SOC stocks (Mg C ha− 1) and total stock (Tg C) baselines and associated uncertainties are fundamental to detect the gains or losses in SOC, and to locate sensitive areas with low SOC levels. Here, we aim to both quantify and spatialize SOC stocks at regional scale (southern Belgium) based on data from one non-design-based or model-based sampling scheme. To this end, we developed a computation procedure based on Digital Soil Mapping techniques and stochastic simulations (Monte-Carlo) allowing the estimation of multiple (here, 10,000) independent spatialized datasets. The computation of the prediction uncertainty accounts for the errors associated to both the estimations of i) SOC stocks and ii) parameters of the spatial model. Based on these 10,000 individuals, median SOC stocks and 90% prediction intervals were computed for each pixel, as well as total SOC stocks and their 90% prediction intervals for selected sub-areas and for the entire study area. Hence, a Generalised Additive Model (GAM) explaining 69.3% of the SOC stock variance was calibrated and then validated (R2 = 0.64). The model overestimated low SOC stock (below 50 Mg C ha− 1) and underestimated high SOC stock (especially those above 100 Mg C kg− 1). A positive gradient of SOC stock occurred from the northwest to the center of Wallonia with a slight decrease on the southernmost part, correlating to the evolution of precipitation and temperature (along with elevation) and dominant land use. At the catchment scale higher SOC stocks were predicted on valley bottoms, especially for poorly drained soils under grassland. Mean predicted SOC stocks for cropland and grassland in Wallonia were of 26.58 Tg C (SD 1.52) and 43.30 Tg C (2.93), respectively. The procedure developed here allowed to predict realistic spatial patterns of SOC stocks all over agricultural lands of southern Belgium and to produce reliable statistics of total SOC stocks for each of the 20 combinations of land use/agricultural regions of Wallonia. This procedure appears useful to produce soil maps as policy tools in conducting sustainable management at regional and national scales, and to compute statistics which comply with specific requirements of reporting activities. [less ▲]

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