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See detailKlemtoon in het Nederlands van Franstalige immersie- en niet-immersieleerlingen
Rasier, Laurent ULg; Bui-Anh, Vu ULg; Jouniaux, Anthony et al

in Degand, Liesbeth; Hiligsmann, Philippe; Rasier, Laurent (Eds.) et al In het teken van identiteit. Taal en cultuur van de Nederlanden (2014)

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See detailDesign of a reliable processing pipeline for the non-intrusive measurement of feet trajectories with lasers
Pierard, Sébastien ULg; Azrour, Samir ULg; Van Droogenbroeck, Marc ULg

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP) (2014, May)

Reliable measurements of feet trajectories are needed in some applications, such as biomedical applications. This paper describes the data processing pipeline used in GAIMS, which is a non-intrusive ... [more ▼]

Reliable measurements of feet trajectories are needed in some applications, such as biomedical applications. This paper describes the data processing pipeline used in GAIMS, which is a non-intrusive system that measures feet trajectories based on multiple range laser scanners. Our processing pipeline relies on a new tracking paradigm, and it is based on two innovative algorithms: the first algorithm localizes the feet directly from the observed point cloud without any clustering, and the other algorithm identifies the feet. After reviewing the various types of noise affecting the point cloud, this paper explains the limitations of the classical processing approach and gives an overview of our new pipeline. The effectiveness of the proposed approach is established by discussing the results that have been obtained in several studies based on GAIMS. [less ▲]

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See detailPerformances of low-level audio classifiers for large-scale music similarity
Osmalsky, Julien ULg; Van Droogenbroeck, Marc ULg; Embrechts, Jean-Jacques ULg

in International Conference on Systems, Signals and Image Processing (2014, May)

This paper proposes a survey of the performances of binary classifiers based on low-level audio features, for music similarity in large-scale databases. Various low-level descriptors are used individually ... [more ▼]

This paper proposes a survey of the performances of binary classifiers based on low-level audio features, for music similarity in large-scale databases. Various low-level descriptors are used individually and then combined using several fusion schemes in a content-based audio retrieval system. We show the performances of the classifiers in terms of pruning and loss and we demonstrate that some combination schemes achieve a better performance at a minimum computational cost. [less ▲]

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See detailA generic approach for solving nonlinear-discrete security-constrained power flow problems in large-scale systems
Platbrood, Ludovic; Capitanescu, Florin; Crisciu, Horia et al

in IEEE Transactions on Power Systems (2014), 29(3), 1194-1203

This paper proves the practicality of an iterative algorithm for solving realistic large-scale SCOPF problems. This algorithm is based on the combination of a contingency filtering scheme, used to ... [more ▼]

This paper proves the practicality of an iterative algorithm for solving realistic large-scale SCOPF problems. This algorithm is based on the combination of a contingency filtering scheme, used to identify the binding contingencies at the optimum, and a network compression method, used to reduce the complexity of the post-contingency models included in the SCOPF formulation. We show that by combining these two complementary ideas, it is possible to solve in a reasonable time SCOPF problems on large power system models with a large number of contingencies. Unlike most results reported for large-scale SCOPF problems, our algorithm uses a non-linear AC network model in both pre-contingency and post-contingency states, optimizes both active/reactive powers flows jointly, and treats the discrete variables. The proposed algorithm is implemented with state-of-the-art solvers and applied to two systems: a national grid with 2563 buses and 1297 contingencies, and a model of the European transmission network with 9241 buses and 12000 contingencies. [less ▲]

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See detailCacahuète céleste
Nazé, Yaël ULg

Article for general public (2014)

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See detailEntre recettes du Soi et recettes de l'Autre. Ethnographie de pratiques culinaires marocaines à Sesto San Giovanni (Milan, Italie)
Mescoli, Elsa ULg

Doctoral thesis (2014)

La thèse porte sur les processus de subjectivation d’un groupe de femmes marocaines résidant dans la ville de Sesto San Giovanni, dans le nord de l’Italie. Elsa Mescoli considère les habitudes ... [more ▼]

La thèse porte sur les processus de subjectivation d’un groupe de femmes marocaines résidant dans la ville de Sesto San Giovanni, dans le nord de l’Italie. Elsa Mescoli considère les habitudes alimentaires et les pratiques culinaires de ces femmes et de leurs familles, facteurs qui agissent dans la construction de soi à plusieurs niveau : celui intime, en contexte domestique ; celui partagé/contesté, en contexte publique. L’étude se situe au croisement entre l’anthropologie de l’alimentation, l’anthropologie de la culture matérielle et l’anthropologie des migrations. En fait, ces processus sont analysés en adoptant une perspective praxéologique, c’est-à-dire en portant l’attention sur la matérialité. La thèse met en évidence les « ingrédients » concrets de la définition de soi des femmes considérées, ainsi que de leurs rapports interpersonnels et « interculturels ». [less ▲]

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See detailMoyens et fins: de Gramsci à Lefort
Mancuso, Eva ULg

Scientific conference (2014, April 30)

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See detailA new analysis of the optical polarisation alignments of quasars
Pelgrims, Vincent ULg

Poster (2014, April 30)

Introduction of a new statistical method dedicated to the analysis of polarisation orientations and presentation of some results of its application to the sample of optical polarisation measurements of ... [more ▼]

Introduction of a new statistical method dedicated to the analysis of polarisation orientations and presentation of some results of its application to the sample of optical polarisation measurements of 355 quasars. [less ▲]

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See detailEstimation and approximation in nonlinear dynamic systems using quasilinearization
Frasso, Gianluca ULg; Jaeger, Jonathan ULg; Lambert, Philippe ULg

E-print/Working paper (2014)

Nonlinear (systems of) ordinary differential equations (ODEs) are common tools in the analysis of complex one-dimensional dynamic systems. In this paper we propose a smoothing approach regularized by a ... [more ▼]

Nonlinear (systems of) ordinary differential equations (ODEs) are common tools in the analysis of complex one-dimensional dynamic systems. In this paper we propose a smoothing approach regularized by a quasilinearized ODE-based penalty in order to approximate the state functions and estimate the parameters defining nonlinear differential systems from noisy data. Within the quasilinearized spline based framework, the estimation process reduces to a conditionally linear problem for the optimization of the spline coefficients. Furthermore, standard ODE compliance parameter(s) selection criteria are easily applicable and conditions on the state function(s) can be eventually imposed using soft or hard constraints. The approach is illustrated on real and simulated data. [less ▲]

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See detailLe cheminement vers un Empire napoléonien (1800-1804)
Genin, Vincent ULg

Conference given outside the academic context (2014)

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See detailRetrieval of HCHO from MAX-DOAS measurements at the high-altitude alpine station of Jungfraujoch (46.5°N, 8.0°E)
Hendrick, François; Fayt, Caroline; Franco, Bruno ULg et al

Conference (2014, April 30)

Formaldehyde (HCHO) plays an important intermediate role in the atmospheric photo-oxidation pathways. It is produced during the oxidation of methane and many non-methane volatile organic compounds (NMVOCs ... [more ▼]

Formaldehyde (HCHO) plays an important intermediate role in the atmospheric photo-oxidation pathways. It is produced during the oxidation of methane and many non-methane volatile organic compounds (NMVOCs) which participate to the formation of tropospheric ozone and secondary organic aerosols. HCHO is also directly released by biomass burning and fossil fuel combustion and to a lesser extent by vegetation. Measuring this species is therefore of major importance for air quality and climate change monitoring. In this presentation, HCHO near-surface concentrations and vertical column densities are retrieved from MAX-DOAS measurements performed at the high-altitude station of Jungfraujoch (3580m asl) in the Swiss Alps from July 2010 till December 2012. Although being most of the time located in the free troposphere, this station can be temporarily affected by pollution events originating from the valley, leading to a local increase of air pollutant concentrations. The capability of the MAX-DOAS technique to retrieve HCHO in such high-altitude location is investigated. The spatial representativeness and the impact of cloud cover on the measurements is also discussed. For verification purpose, our retrievals are compared to collocated FTIR observations, taking into account the difference in vertical resolution between both techniques. Simulations from the 3D-CTM IMAGES are also used to further assess the observed seasonal and diurnal cycles of HCHO surface concentration and vertical column. [less ▲]

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See detailEtude des propriétés des variants amyloïdogéniques du lysozyme humain à l’aide de fragments d’anticorps à chaînes lourdes comme sondes structurales
Dumont, Janice ULg

Doctoral thesis (2014)

Les fibres amyloïdes sont des agrégats de protéines hautement organisés qui sont associés à une trentaine de maladies appelées amyloses, dont les maladies d'Alzheimer et de Parkinson et la maladie de la ... [more ▼]

Les fibres amyloïdes sont des agrégats de protéines hautement organisés qui sont associés à une trentaine de maladies appelées amyloses, dont les maladies d'Alzheimer et de Parkinson et la maladie de la vache folle. L'amylose systémique à lysozyme est une amylose non-neuropathique héréditaire associée à sept variants de la protéine (Y54N, I56T, F57I, W64R, D67H, F57I/T70N et W112R/T70N). Ces protéines forment des fibres amyloïdes extracellulaires qui se déposent dans de nombreux tissus et organes tels que le foie, la rate et les reins. Il a été montré que les mutations I56T et D67H diminuent la stabilité et la coopérativité globale de la protéine. Ainsi, dans des conditions proches des conditions physiologiques, ces variants forment, in vitro, transitoirement un état intermédiaire dans lequel le domaine β et l'hélice C se déplient de manière coopérative, alors que le reste du domaine α conserve sa structure native. La formation d'interactions intermoléculaires entre les régions dépliées serait à l'origine du processus d'agrégation qui conduit à la formation et au dépôt de fibres amyloïdes dans les tissus des patients porteurs de ces mutations. Il a également été montré que la liaison de trois fragments d'anticorps à chaînes lourdes de camélidés (VHH), dirigés contre le lysozyme humain de sauvage, inhibe in vitro la formation de fibres amyloïdes par les variants D67H et I56T. Ces trois VHH se lient à des régions différentes du lysozyme et inhibent la formation de fibres amyloïdes selon différents mécanismes. Au cours de ce doctorat, seize nouveaux VHH spécifiques du lysozyme humain ont été générés. Des expériences de liaisons compétitives suivies par résonnance plasmonique de surface ont montré que les 16 VHH se lient à cinq épitopes distincts à la surface du lysozyme. Quatre d’entre eux sont capables de se lier au lysozyme dans les conditions utilisées in vitro pour induire la formation de fibres amyloïdes par les variants du lysozyme. Leur site de liaison a été déterminé par RMN. Deux d'entre eux reconnaissent des épitopes différents de ceux des trois VHH caractérisés précédemment. Des expériences d’échange H/D analysés par spectrométrie de masse ont montré que les 4 VHH ont des capacités différentes à restaurer la coopérativité globale du variant D67H du lysozyme. L’analyse de l’ensemble des résultats nous a permis d’identifier qu'elles sont les régions du lysozyme qui doivent être affectées par la liaison d'un VHH afin de restaurer la coopérativité globale de la protéine. La liaison simultanée aux deux domaines (i.e. α et β) semble être le dénominateur commun de tous les VHH restaurant la coopérativité globale du variant D67H. La liaison aux hélices B et C, ainsi que de l'interface des deux domaines semble aussi contribuer à la restauration de la coopérativité globale. A l'inverse, une liaison qui perturbe la partie N-terminale ne permet pas de restaurer la coopérativité globale de la protéine. La liaison d’un VHH, cAb-HuL9a, au variant D67H du lysozyme inhibe de manière similaire la formation de l’intermédiaire partiellement déplié, l'élongation de fibres amyloïdes préformées et la formation de fibres amyloïdes in vitro. Cette observation est en accord avec l’hypothèse selon laquelle, la formation de cet intermédiaire est à l’origine de l’amyloïdogénicité des variants du lysozyme. Afin d'étudier les effets des mutations amyloïdogéniques récemment identifiées sur les propriétés du lysozyme et ainsi obtenir une meilleure connaissance du mécanisme de formation des fibres amyloïdes, il est nécessaire de produire ces variants en grande quantité. Les variants D67H, I56T et F57I sont produits dans Aspergillus niger. L'expression des variants dans ce micro-organisme est toutefois particulièrement chronophage alors que les rendements de production sont relativement faibles. Les tentatives d'utiliser d'autres systèmes de production tels que Pichia pastoris ou le système bacculovirus n'ont pas été concluantes. Aussi, dans le cadre de mon doctorat, j’ai étudié la possibilité de produire le variant D67H sous forme de corps d'inclusion dans Escherichia. coli. Un protocole permettant de produire 20 mg de protéine sous forme de corps d’inclusion par litre de culture a été développé. Différents stratégies ont été testées pour replier la protéine à partir des corps d’inclusion. Cette approche a permis d’obtenir une protéine ayant 90% d’activité spécifique du lysozyme. Le rendement massique obtenu après repliement est néanmoins très faible. [less ▲]

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See detailMigration in post-socialist China: cultural struggles, narration and the shaping of identities
Florence, Eric ULg

Scientific conference (2014, April 30)

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See detailRecords of human activity during the late-Holocene in the soils of the African dense humid forest
Morin-Rivat, Julie ULg; Biwolé, Achille; Bourland, Nils ULg et al

Conference (2014, April 30)

Recently, several authors gathered data about the presence of past human populations in tropical regions covered by dense forest nowadays. In central Africa, there is a growing body of evidence for past ... [more ▼]

Recently, several authors gathered data about the presence of past human populations in tropical regions covered by dense forest nowadays. In central Africa, there is a growing body of evidence for past human settlements along the Atlantic coast, but very little information is available further inland. In this perspective, soil records seem to be the most appropriated so as to appraise the spatial and temporal extent of human activity in the African dense humid forest. In this paper, we thus aimed to present a synthesis of the archaeological and archaeobotanical data obtained during several fieldwork campaigns in an archaeologically unexplored area of 200,000 km² located in southern Cameroon and the northern Republic of Congo. A total of 275 test pits, among them 30 pedological pits up to 150 cm deep, were excavated in the study area. So as to get a long temporal scale as well as a fine resolution spatial scale, we quantified wood charcoal and charred endocarps in soil samples by layers of 10 cm taken for 100 pits located along transects of systematic sampling. Spatial projections were performed using statistics together with multivariate analyses. AMS radiocarbon dating allowed interpreting the temporal framework. Evidence of past human activities through either artifacts or charred botanical remains was observed in all pits, in particular with the ubiquitous presence of charcoal at each site. Main charcoal peaks were interpreted as fields (slash-and-burn agriculture) in the vicinity of ancient villages, the later marked by the presence of both potsherds and oil palm endocarps. The dichotomy of these kinds of activities may have impacted differentially the environment during the past. The set of 73 radiocarbon dates extending from 15,000 BP to the present time provided more dates in the late-Holocene showing a bimodal distribution which was interpreted as two phases of human expansion with an intermediate phase of population crash. The 2300–1300 BP phase is correlated with the migrations of supposed farming populations from northwestern Cameroon. Between 1300 and 670 BP, less material could be dated. Following that population collapse, the 670–20 BP phase corresponds to a new period of human expansion known as the Late Iron Age. The dates obtained support the established chronology reported for whole central Africa. This study underlines the necessity of fieldwork efforts and of the usefulness of archives sealed in soil records so as to bring new, extensive and precise evidence of human activities in the Congo Basin. [less ▲]

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See detailTRAPPIST detection of the light from a bloated hot Jupiter at the edge of tidal disruption
Delrez, Laetitia ULg; Gillon, Michaël ULg; Lendl, Monika ULg et al

Poster (2014, April 30)

Abstract : We present here the discovery by the WASP-­South survey, in close collaboration with the Euler and TRAPPIST telescopes, of the transiting planet WASP-­121b as well as the measurement of its ... [more ▼]

Abstract : We present here the discovery by the WASP-­South survey, in close collaboration with the Euler and TRAPPIST telescopes, of the transiting planet WASP-­121b as well as the measurement of its thermal emission at 0.9 microns. WASP-­121b is a very inflated (1.76 RJup) Jupiter-­mass (1.02 MJup) planet that transits every 1.27 days a bright F6V star. It is remarkable as its orbital radius is only ~10% larger than its Roche limit, suggesting that it might experience mass loss through Roche-­lobe overflow. Thanks to its large size and extreme irradiation (~7 10^9 erg s-1 cm-­2), it was predicted to display a thermal emission of ~0.1% of the stellar flux in the near-­infrared. Using the TRAPPIST robotic telescope, we could detect this thermal emission signal at ~5 sigma in the z'-­band. This measurement, a first for a ground-­based 60cm telescope, allows to place preliminary constraints on the atmospheric properties of this very special hot Jupiter. [less ▲]

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See detailSpatio-Temporal Analysis of Equatorial Ionospheric Scintillations in the Frame of Absolute GNSS Positioning Algorithms
Lonchay, Matthieu ULg; Cornet, Yves ULg; Aquino, Marcio et al

Conference (2014, April 30)

The ionosphere has always been a major limitation for GNSS positioning applications. Free electrons in the ionosphere perturb the propagation of GNSS radio signals involving both refraction and ... [more ▼]

The ionosphere has always been a major limitation for GNSS positioning applications. Free electrons in the ionosphere perturb the propagation of GNSS radio signals involving both refraction and diffraction effects. The ionospheric refraction mainly results in a modification of the propagation speed of the GNSS electromagnetic signals, inducing an error (propagation delay or phase advance depending on the observable) in GNSS measurements. In the frame of absolute positioning techniques, single-frequency algorithms usually exploit an ionospheric model to mitigate the ionospheric error while dual-frequency algorithms, such as the well-known Precise Point Positioning (PPP), take the benefit of the availability of two frequencies and the fact that the ionosphere is a dispersive medium to construct an ionosphere-free mathematical model. But these two strategies are not able to counteract the effect of the ionospheric diffraction which is due to small-scale irregularities in the free electron density. By scattering GNSS signals, these irregularities generate rapid fluctuations (scintillations) in the amplitude and phase of GNSS signals with critical consequences for GNSS applications: cycle slips, signal power fading, receiver loss of lock and poor resulting satellite geometry. The goal of our research is to develop a strategy to mitigate the effect of ionospheric scintillations on absolute GNSS positioning techniques, in particular the SPP (Standard Point Positioning) and the PPP (Precise Point Positioning). The strategy is based on the adjustment of the stochastic model. In order to construct the stochastic model (diagonal and non-diagonal elements) and study the correlation between observables, we adopted a “spatial” and an “empirical” approach. The spatial approach consists in a study of the spatial autocorrelation existing in scintillations effects on GNSS signals. The spatial autocorrelation is detected by using specific spatial analysis techniques applied on data from a network of ISMR (Ionospheric Scintillation Monitoring Receiver) stations located at equatorial and polar latitudes, where scintillations effects are most severe. The knowledge of how scintillation effects are spatially correlated is helpful for determining a coherent stochastic model. The empirical approach does not take into account the phenomenon spatiality and the locations of the measurements but only the observation data. Its objective is to determine the statistical correlation which exists between GNSS measurements during a scintillation event by using a moving filter applied on GNSS observation and scintillation data. The spatial approach exploits data and data locations while the empirical approach is based only the data itself. [less ▲]

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See detailLD-based haplotype encoding scheme with iterative pruning principal component analysis (ipPCA) to retrieve population substructures
Chaichoompu, Kridsadakorn ULg; Fouladi, Ramouna ULg; Wangkumhang, Pongsakorn et al

Poster (2014, April 29)

Objective To identify and differentiate between subpopulations using a rich set of genetic markers, as using reduced sets of genetic markers for these purposes can become challenging, especially when ... [more ▼]

Objective To identify and differentiate between subpopulations using a rich set of genetic markers, as using reduced sets of genetic markers for these purposes can become challenging, especially when similar geographic regions are involved or when spurious patterns are likely to exist. Method Single Nucleotide Polymorphisms (SNPs) are commonly used to capture variations between populations and often genome-wide SNP data are pruned based on linkage disequilibrium (LD) patterns. Notably, haplotype composition and the pattern of LD between markers may vary between larger populations but may also play a role within more confined geographic regions. Indeed, knowledge about haplotypes in unrelated individuals can reveal useful information about genetic ancestry. Here, we use iterative pruning principal component analysis (ipPCA) [1] to identify and characterize subpopulations in an unsupervised way. As input data, either pruned genome-wide SNP data are used (using PLINK 1.9 with the "indep-pairwise" option, window size = 100k, r2 < 0.25) or multilocus haplotype information derived from the genome-wide SNP panel (using BEAGLE 3.3.2 to infer haplotype). These approaches are applied to real-life data from 992 Thai individuals [2]. Result Preliminary results indicate that ipPCA applied to pruned SNP data or ipPCA that explicitly uses multilocus information (haplotypes) give complementary information about population substructure for geographically confined populations such as the Thai samples in this study. Both methods address different aspects of population structure. Detailed simulation studies are needed to identify the optimal scenarios for haplotype-based ipPCA. Conclusion In this work, we propose to combine an LD-based haplotype encoding scheme with the ipPCA machinery to retrieve fine population substructures. Despite the complexities that are associated with haplotype inference, added value can be obtained when the LD structure between SNPs is exploited in the search for relevant population strata. References 1. Intarapanich, A., et al., Iterative pruning PCA improves resolution of highly structured populations. BMC Bioinformatics, 2009. 10: p. 382. 2. Wangkumhang, P., et al., Insight into the peopling of Mainland Southeast Asia from Thai population genetic structure. PLoS One, 2013. 8(11): p. e79522. [less ▲]

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