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See detailUnderstanding variable importances in forests of randomized trees
Louppe, Gilles ULg; Wehenkel, Louis ULg; Sutera, Antonio ULg et al

in Advances in Neural Information Processing Systems 26 (2013, December)

Despite growing interest and practical use in various scientific areas, variable importances derived from tree-based ensemble methods are not well understood from a theoretical point of view. In this work ... [more ▼]

Despite growing interest and practical use in various scientific areas, variable importances derived from tree-based ensemble methods are not well understood from a theoretical point of view. In this work we characterize the Mean Decrease Impurity (MDI) variable importances as measured by an ensemble of totally randomized trees in asymptotic sample and ensemble size conditions. We derive a three-level decomposition of the information jointly provided by all input variables about the output in terms of i) the MDI importance of each input variable, ii) the degree of interaction of a given input variable with the other input variables, iii) the different interaction terms of a given degree. We then show that this MDI importance of a variable is equal to zero if and only if the variable is irrelevant and that the MDI importance of a relevant variable is invariant with respect to the removal or the addition of irrelevant variables. We illustrate these properties on a simple example and discuss how they may change in the case of non-totally randomized trees such as Random Forests and Extra-Trees. [less ▲]

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See detail« Dozon, Jean-Pierre. Une anthropologie en mouvement. L’Afrique miroir du contemporain. Versailles. Éditions Quae, 2008, 272 p.»
Melice, Anne ULg

in Cahiers d'Etudes Africaines (2013), 212(LIII (4)), 951-954

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See detailReorientation of the helix of the tryptophan-rich gp41W peptide from HIV-1 at interfaces
Matar, Gladys; Benichou, Emmanuel; Nasir, Mehmet Nail ULg et al

in Journal of Chemical Physics (2013), 139

The glycoprotein gp41 from the Human Immunodeficiency Virus type 1 (HIV-1) has an amino acid sequence enriched in tryptophan residues, the so-called gp41W peptide (i.e., KWASLWNWFNITNWLWYIK) and plays a ... [more ▼]

The glycoprotein gp41 from the Human Immunodeficiency Virus type 1 (HIV-1) has an amino acid sequence enriched in tryptophan residues, the so-called gp41W peptide (i.e., KWASLWNWFNITNWLWYIK) and plays a crucial role in HIV-1 host cell infection. Using the coupling of Second Harmonic Generation targeting the tryptophan residues with lateral surface tension measurements, we investigate the interaction of gp41W with a neat air/water and a lipid/water interfaces. At the air/water interface, gp41W presents a well-defined orientation and this orientation is strongly modified at the lipid/water interface, depending on the surface pressure. These results show that this strategy is well suited to monitor tryptophan containing α-helices orientation at lipid/water interfaces. [less ▲]

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See detailEBP : grille de mots croisés
Durieux, Nancy ULg; Martinez Perez, Trecy ULg

in Cahiers de l'ASELF (2013), 10(4), 30-3136

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See detailQue pouvons-nous attendre du sommet européen de décembre 2013 ?
Dumoulin, André ULg

E-print/Working paper (2013)

Hypothèses autour des décisions attendues du sommet UE spécial défense prévu en décembre 2013 avec les différentes écoles de pensée

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See detailMacrophytes: Limitations of Using Them to Assess Reservoir Status According to the Water Framework Directive
Sossey Alaoui, Khadija ULg; Galoux, Daniel; Rosillon, Francis ULg

in International Journal of Water Sciences (2013)

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural lakes. The use of macrophytes in reservoir ... [more ▼]

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural lakes. The use of macrophytes in reservoir monitoring is still limited and further studies are needed on their inter-calibration and sources of variation. Many status assessment methods based on macrophyte <br />communities have been defined for lakes. Nevertheless, few of them have been tested for reservoirs. The purpose of the study is to highlight the limitations of using macrophytes to assess reservoir status according to the Water Framework Directive. <br />An assessment of macrophyte composition and abundance and of water quality was carried out in nine Walloon reservoirs between 2010 and 2012. The main limitations of the macrophyte approach for assessing these reservoirs were: i) geographical features; ii) physical variables; iii) lack of ecological information on the various macrophytic groups, such as helophytes, algae and mosses. We used two assessment methods to test the relevance of using macrophyte communities to assess reservoir status: the Flanders (Belgium) method (BE-FL method) and the United Kingdom method (UK method). The relationships between macrophyte metrics for both methods and nutrient enrichment were examined. Highly significant correlations were found between the chemical variables O-P [mg P/l]), Total P (µg P/l), Conductivity (µS/cm) and the trophic UK-metric (Lake Macrophyte Nutrient) (LMNI), as well as between such variables and the abundance of Bl-FL "disturbance indicators" metric(V). The UK "group of macrophyte species" metric provided limited information on the quality or degrees of degradation in the environment from which the sample was taken. [less ▲]

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See detailJeux sérieux : présentation
Hurel, Pierre-Yves ULg

Article for general public (2013)

Si vous n'avez pas encore entendu parler des « Serious Games », ça ne devrait plus tarder tant le phénomène prend de l'ampleur. À la différence des jeux vidéo, ils ont une finalité autre que l'amusement ... [more ▼]

Si vous n'avez pas encore entendu parler des « Serious Games », ça ne devrait plus tarder tant le phénomène prend de l'ampleur. À la différence des jeux vidéo, ils ont une finalité autre que l'amusement. Au contraire des logiciels pédagogiques des années 1990, ils n'oublient pas d'être ludiques. Présentation de ces objets en vogue. [less ▲]

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See detailLa physiognomonie au XIXe siècle. Transpositions esthétiques et médiatiques
Stienon, Valérie ULg; Wicky, Érika

Book published by revue Etudes Françaises (2013)

Dès les premières traductions françaises des traités de Johann Kaspar Lavater à la fin du XVIIIe siècle, la physiognomonie a pris une place prépondérante dans l’iconographie et la pensée de l’époque. Très ... [more ▼]

Dès les premières traductions françaises des traités de Johann Kaspar Lavater à la fin du XVIIIe siècle, la physiognomonie a pris une place prépondérante dans l’iconographie et la pensée de l’époque. Très tôt renforcée par la diffusion des traités de phrénologie de Franz Josef Gall, cette théorie paramédicale a suscité une émulation telle qu’elle a contribué à poser les bases de la morphopsychologie, qu’elle a participé au développement de l’anthropométrie et s’est ramifiée en d’innombrables branches parmi lesquelles figurent la physiognomonie zoologique, la physiognomonie ethnologique ou encore la « pathognomonie ». En outre, reposant sur la conviction qu’il est possible d’atteindre les profondeurs de l’intériorité humaine par l’observation d’éléments conçus comme autant de signes à déchiffrer, cette théorie relève du raisonnement par induction qui a pris, dans la fiction littéraire, la forme spécifique d’une recherche d’indices et a participé, dans les disciplines médicales, à la méthode diagnostique. Le postulat selon lequel une connaissance de l’être humain est possible par l’observation minutieuse de ses traits extérieurs – conviction renforcée, à la moitié du siècle, par les possibilités techniques de la photographie – a contribué à enrichir la description, à affiner l’art du portrait et à aiguiser le trait incisif de la caricature. Ayant offert de riches moyens cognitifs et esthétiques d’exploration du monde social au peintre, à l’illustrateur, à l’homme de lettres et à l’historien, ces théories paramédicales ont durablement marqué l’histoire des conceptions et des représentations sociales. Envisager l’influence de la physiognomonie en termes de diffusion d’un paradigme scientifique permettra de saisir les modalités et de mesurer les enjeux non seulement de la transposition de ce paradigme d’un médium à un autre, mais aussi de sa circulation entre différentes aires géographiques, disciplinaires ou sociales. L’étude des vecteurs suivant lesquels la physiognomonie investit les représentations fera intervenir des corpus variés, issus de contextes culturels allant de la France romantique à la blogosphère actuelle en passant par l’Allemagne nazie de l’entre-deux-guerres. À l’observation attentive des sources primaires (documents historiques, traités médicaux, gravures d’époque, œuvres picturales, textes littéraires), s’ajoutera une réflexion sur la postérité de ces développements théoriques par l’analyse des discours distanciés, dubitatifs, voire explicitement critiques à leur égard, et ce dès leur toute première diffusion. Ce dossier propose une réflexion susceptible d’apporter des éléments de réponse à la double question suivante : de quelle postérité épistémique le modèle d’interprétation et de représentation hérité de la physiognomonie bénéficie-t-il, entre dépréciation et application effective, à partir de la seconde moitié du XIXe siècle ? Comment cette influence s’est-elle répandue ? [less ▲]

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See detailUn siècle de physiognomonie
Stienon, Valérie ULg; Wicky, Érika

in Etudes Françaises (2013), 49(3), 5-14

Produit syncrétique et protéiforme d’une très longue histoire, la physiognomonie remonte au moins au Pseudo-Aristote (IVe-IIIe siècle av. J.-C.). Très tôt, l’essentiel est déjà posé : il s’agit de ... [more ▼]

Produit syncrétique et protéiforme d’une très longue histoire, la physiognomonie remonte au moins au Pseudo-Aristote (IVe-IIIe siècle av. J.-C.). Très tôt, l’essentiel est déjà posé : il s’agit de considérer les manifestations physiques de l’âme. À la faveur des XVIe et XVIIe siècles, cette étude se précise avec l’association de telle détermination somatique à telle spécificité de caractère, fondant l’explication des moeurs des hommes par des traits corporels considérés comme autant de signes à interpréter. Une distinction vient ensuite faire le départ entre les caractéristiques fixes du corps et du caractère, et leurs aspects mutables. À la fin du XVIIIe siècle, sous l’influence du sensualisme et après l’étude des passions qui avait occupé le siècle classique, cette distinction fonde la séparation entre une physiognomonie au sens restreint et une pathognomonie consacrée à l’étude des signes physiques traduisant le caractère en mouvement et les signes fugitifs de l’expression humaine. La suite de cette histoire, au XIXe siècle, fait l’objet du présent numéro d’Études françaises, qui remet en perspective les formes et les influences de la physiognomonie à ce moment stratégique de son développement. Le bouleversement des hiérarchies socio-culturelles et l’industrialisation des objets socialement distinctifs (vêtements, bijoux, cannes, ombrelles, etc.) ont certainement contribué à accentuer l’intérêt pour la physiognomonie en rendant indispensable la maîtrise d’un certain savoir social. Mais l’engouement qu’elle suscite se caractérise surtout, à ce moment, par la création de foyers institutionnels spécifiques qui la dotent d’un ancrage dans des associations scientifiques, des cercles intellectuels et des organes de presse. Il s’agira donc, indissociablement, de comprendre les raisons d’un succès et d’examiner les reconfigurations d’un héritage. [less ▲]

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See detailRECOMMANDATIONS EUROPÉENNES POUR LA PRISE EN CHARGE DU DIABÈTE, DU PRÉ-DIABÈTE ET DES MALADIES CARDIO-VASCULAIRES 2ème partie. Gestion des complications cardiaques, cérébro-vasculaires et artériopathiques périphériques
SCHEEN, André ULg; LANCELLOTTI, Patrizio ULg

in Revue Médicale de Liège (2013), 68(12), 617-624

Summary : Patients with prediabetes (dysglycaemia) or diabetes present accelerated atherosclerosis that predisposes them to multiple cardiovascular complications. We summarize here the joint ... [more ▼]

Summary : Patients with prediabetes (dysglycaemia) or diabetes present accelerated atherosclerosis that predisposes them to multiple cardiovascular complications. We summarize here the joint recommendations recently published by the European Society of Cardiology and the European Society for the Study of Diabetes. The management of main risk factors, aiming to optimize primary or secondary prevention, has been developed in a first article. This second article is focusing on the management of cardiac, cerebrovascular and peripheral arteriopathic complications. The importance of an individualized patient-centered strategy is emphasized, including the management of microangiopathies and, ideally, within a multidisciplinary approach. [less ▲]

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See detailWhite Dwarf Stars: A Brief Overview
Fontaine, Gilles; Brassard, Pierre; Charpinet, Stephane et al

in Astronomical Society of the Pacific Conference Series (2013, December), 479

We present a brief summary of what is currently known about white dwarf stars, with an emphasis on their evolutionary and internal properties. As is well known, white dwarfs represent the end products of ... [more ▼]

We present a brief summary of what is currently known about white dwarf stars, with an emphasis on their evolutionary and internal properties. As is well known, white dwarfs represent the end products of stellar evolution for the vast majority of stars and, as such, bear the signatures of past events (such as mass-loss, mixing phases, loss and redistribution of angular momentum, and thermonuclear burning) that are of essential importance in the evolution of stars in general. In addition, white dwarf stars represent ideal testbeds for our understanding of matter under extreme conditions, and work on their constitutive physics (neutrino production rates, conductive and radiative opacities, interior liquid and solid equations of state, partially ionized and partially degenerate envelope equations of state, diffusion coefficients, line broadening mechanisms) is still being actively pursued. Given a set of constitutive physics, cooling white dwarfs can be used advantageously as cosmochronometers. Moreover, the field has been blessed by the existence of four distinct families of pulsating white dwarfs, each mapping a different evolutionary phase, and this allows the application of the asteroseismological method to probe and test their internal structure and evolutionary state. [less ▲]

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See detailg-Mode Oscillations in Hot B Subdwarf Stars
Charpinet, Stéphane; Van Grootel, Valérie ULg; Fontaine, Gilles et al

in Astronomical Society of the Pacific Conference Series (2013, December), 479

Observations from space with CoRoT and Kepler have revealed the rich pulsation spectra that characterize the long period hot B subdwarf (sdB) pulsators of the V1093 Her type. These evolved and compact ... [more ▼]

Observations from space with CoRoT and Kepler have revealed the rich pulsation spectra that characterize the long period hot B subdwarf (sdB) pulsators of the V1093 Her type. These evolved and compact helium core burning stars can develop low amplitude oscillations with periods in the range ∼ 1 − 4 hours that correspond to low degree, mid to high order g-modes. These modes have the property to penetrate deep inside the star, down to the boundary of the central convective core. They are consequently particularly interesting as asteroseismic probes. Here we briefly review how the g-modes behave in sdB stars, focusing in particular on the seismic signatures coming from the core itself. We also briefly summarize the first seismic results obtained from space data in pioneering efforts to exploit the potential of long period sdB pulsators as deep probes of the core structure. [less ▲]

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See detailActivité physique et maladies neuromusculaires
WANG, François-Charles ULg

in Lettre du Neurologue (La) : le Courrier du Spécialiste (2013)

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See detailThe instability strip of ZZ Ceti white dwarfs and its extension to the extremely low mass pulsators
Van Grootel, Valérie ULg; Fontaine, Gilles; Brassard, Pierre et al

in Astronomical Society of the Pacific Conference Series (2013, December), 479

The determination of the location of the theoretical ZZ Ceti instability strip in the log g − Teff diagram has remained a challenge over the years, due to the lack of a suitable treatment for convection ... [more ▼]

The determination of the location of the theoretical ZZ Ceti instability strip in the log g − Teff diagram has remained a challenge over the years, due to the lack of a suitable treatment for convection in these stars. We report here a detailed stability survey over the whole ZZ Ceti regime, including the very low masses where three pulsators have recently been found. We computed to this aim 29 evolutionary sequences of DA models with various masses and chemical layering. These models are characterized by the so-called ML2/α=1.0 convective efficiency and take into account the important feedback effect of convection on the atmospheric structure. We pulsated these models with the Liege nonadiabatic pulsation code MAD, which is the only one to conveniently incorporate a full time-dependent convection treatment and, thus, provides the best available description of the blue edge of the instability strip. On the other hand, given the failure of all nonadiabatic codes to account properly for the red edge of the strip, including MAD, we tested the idea that the red edge is due to energy leakage through the atmosphere. Using this approach, we found that our theoretical ZZ Ceti instability strip accounts remarkably well for the boundaries of the empirical strip. [less ▲]

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See detailL’étude de la poterie en archéologie
Mas, Juliette ULg

Speech (2013)

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See detailLa "Commission nationale des sciences" et l’émergence d’un concept de politique scientifique en Belgique
Pirot, Pascal ULg

in MALPANGOTTO, Michela; JULLIEN, Vincent; NICOLAIDIS, Efthymios (Eds.) L’homme au risque de l’infini. Mélanges d’histoire et de philosophie des sciences offerts à Michel Blay (2013)

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See detailDynamiques écosystémiques co-évolutives : portance écologique du territoire wallon
Hendrickx, Sébastien ULg; Van Der Kaa, Claire ULg; Sérusiaux, Emmanuël ULg

in Notes de recherche - Conférence Permanente du Développement Territorial Région Wallonne (2013), 44

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See detailEviter des drames de type « Lampedusa »
Martiniello, Marco ULg; Martiniello, Marco ULg

Article for general public (2013)

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See detailBreeding sites and species association of the main Bluetongue and Schmallenberg virus vectors, the Culicoides species (Diptera: Ceratopogonidae), in northern Europe
Zimmer, Jean-Yves ULg; Losson, Bertrand ULg; Saegerman, Claude ULg et al

in Annales de la Société Entomologique de France (2013), 49(3), 335-344

Several species of Culicoides (Diptera: Ceratopogonidae) biting midges are biological vectors of bluetongue virus (BTV) and, as recently discovered, Schmallenberg virus (SBV) in northern Europe. Since ... [more ▼]

Several species of Culicoides (Diptera: Ceratopogonidae) biting midges are biological vectors of bluetongue virus (BTV) and, as recently discovered, Schmallenberg virus (SBV) in northern Europe. Since their recent emergence in this part of the continent, these diseases that affect domestic and wild ruminants have caused considerable economic losses to the sheep and cattle industries. The substrates that are suitable for larval development of the main vector species are still relatively unknown. This study assessed all the substrates present in the immediate surroundings of a Belgian cattle farm and aimed to highlight the main breeding sites of these midge species. A total of 1639 immature Culicoides and 1320 adult specimens belonging to 13 species were found in 15 out of the 43 substrates studied: maize silage residues for C. obsoletus/C. scoticus, old overwintered cattle dung in the meadow for C. chiopterus and C. dewulfi, ground of a flooded meadow, green filamentous algae and underlying substrate, silt from a pond, and ground of hollows caused by the crossing of machines on a dirt track for C. festivipennis, silt from a pond for C. nubeculosus, and ground of a flooded meadow for C. lupicaris. Identification of these micro-habitats and the associations among the species they contain could allow their localization and the development of new strategies of vector control, while preventing the creation of new Culicoides larval micro-habitats. Finally, measures designed to reduce larval populations could improve efficacy of vaccination campaigns against BTV in Europe. [less ▲]

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See detailModelling phytoplankton succession and nutrient transfer along the Scheldt estuary (Belgium, The Netherlands)
Gypens, N.; Delhez, Eric ULg; Vanhoutte-Brunier, A. et al

in Journal of Marine Systems (2013), 128

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