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See detailApproximate Bayes Optimal Policy Search using Neural Networks
Castronovo, Michaël ULg; François-Lavet, Vincent ULg; Fonteneau, Raphaël ULg et al

in Proceedings of the 9th International Conference on Agents and Artificial Intelligence (ICAART 2017) (2017, February)

Bayesian Reinforcement Learning (BRL) agents aim to maximise the expected collected rewards obtained when interacting with an unknown Markov Decision Process (MDP) while using some prior knowledge. State ... [more ▼]

Bayesian Reinforcement Learning (BRL) agents aim to maximise the expected collected rewards obtained when interacting with an unknown Markov Decision Process (MDP) while using some prior knowledge. State-of-the-art BRL agents rely on frequent updates of the belief on the MDP, as new observations of the environment are made. This offers theoretical guarantees to converge to an optimum, but is computationally intractable, even on small-scale problems. In this paper, we present a method that circumvents this issue by training a parametric policy able to recommend an action directly from raw observations. Artificial Neural Networks (ANNs) are used to represent this policy, and are trained on the trajectories sampled from the prior. The trained model is then used online, and is able to act on the real MDP at a very low computational cost. Our new algorithm shows strong empirical performance, on a wide range of test problems, and is robust to inaccuracies of the prior distribution. [less ▲]

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

Poster (2017, February)

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See detailMegaloolithid dinosaur eggs: scrambled parataxonomy and nesting strategies
Jentgen, Benjamin ULg; Stein, Koen; Fischer, Valentin ULg

Poster (2017, February)

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See detailLa notion d’attention virtuelle dans la philosophie médiévale
Dubouclez, Olivier ULg

Scientific conference (2017, February)

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See detailChez Froidmont au Nord : lectures polyphoniques d’une quête identitaire
Baiwir, Esther ULg; Adams, Juliette; Demonchaux, Chloé et al

in Tortue verte. Revue en ligne des littératures francophones (2017)

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See detailVoyage[s] à travers le thymus
Geenen, Vincent ULg

in Science et Culture (2017), (465), 14-15

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See detailAn App-based Algorithmic Approach for Harvesting Local and Renewable Energy Using Electric Vehicles
Dubois, Antoine; Wehenkel, Antoine; Fonteneau, Raphaël ULg et al

in Proceedings of the 9th International Conference on Agents and Artificial Intelligence (ICAART 2017) (2017, February)

The emergence of electric vehicles (EVs), combined with the rise of renewable energy production capacities, will strongly impact the way electricity is produced, distributed and consumed in the very near ... [more ▼]

The emergence of electric vehicles (EVs), combined with the rise of renewable energy production capacities, will strongly impact the way electricity is produced, distributed and consumed in the very near future. This position paper focuses on the problem of optimizing charging strategies for a fleet of EVs in the context where a significant amount of electricity is generated by (distributed) renewable energy. It exposes how a mobile application may offer an efficient solution for addressing this problem. This app can play two main roles. Firstly, it would incite and help people to play a more active role in the energy sector by allowing photovoltaic (PV) panel owners to sell their electrical production directly to consumers, here the EVs’ agents. Secondly, it would help distribution system operators (DSOs) or transmission system operators (TSOs) to modulate more efficiently the load by allowing them to influence EV charging behaviour in real time. Finally, the present paper advocates for the introduction of a two-sided market-type model between EV drivers and electricity producers. [less ▲]

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See detailResidential heat pump as flexible load for direct control service with parametrized duration and rebound effect
Georges, Emeline ULg; Cornélusse, Bertrand ULg; Ernst, Damien ULg et al

in Applied Energy (2017), 187

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service consists of a power modulation, upward or downward, that is ... [more ▼]

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service consists of a power modulation, upward or downward, that is activated at a given time period over a fixed number of periods. The service modulation is relative to an optimized baseline that minimizes the energy costs. The load modulation is directly followed by a constrained rebound effect, consisting of a delay time with no deviations from the baseline consumption and a payback time to return to the baseline state. The potential amount of modulation and the constrained rebound effect are computed by solving mixed integer linear problems. Within these problems, the thermal behavior of the building is modeled by an equivalent thermal network made of resistances and lumped capacitances. Simulations are performed for different sets of buildings typical of the Belgian residential building stock and are presented in terms of achievable modulation amplitude, deviations from the baseline and associated costs. A cluster of one hundred ideal buildings, corresponding to retrofitted freestanding houses, is then chosen to investigate the influence of each parameter defined within the service. Results show that with a set of one hundred heat pumps, a load aggregator could expect to harvest mean modulation amplitudes of up to 138 kW for an upward modulation and up to 51 kW for a downward modulation. The obtained values strongly depend on the proposed flexibility service. For example, they can decrease down to 2.6 kW and 0.4 kW, respectively, if no rebound effect is allowed. [less ▲]

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See detailDe Barcelone à Amsterdam : l'émergence de la conservation intégrée à travers les colloques internationaux du Conseil de l'Europe et de l'ICOMOS
Houbart, Claudine ULg

Conference (2017, January 31)

En 1975, la notion de conservation intégrée est consacrée par la Charte européenne du Patrimoine architectural, adoptée par le Comité des Ministres du Conseil de l’Europe avant d’être solennellement ... [more ▼]

En 1975, la notion de conservation intégrée est consacrée par la Charte européenne du Patrimoine architectural, adoptée par le Comité des Ministres du Conseil de l’Europe avant d’être solennellement proclamée et développée au Congrès d’Amsterdam (21-25 octobre 1975). Renouvelant fondamentalement les pratiques de rénovation des centres anciens avec l’ambition de créer un dialogue entre aménageurs et conservateurs, cette approche résulte de dix années de réflexions nourries par des échanges entre experts principalement européens, initiés non seulement par le Conseil de l’Europe (Confrontations de Barcelone (1965), Bath (1966), La Haye (1967) et Avignon (1968)), mais également par l’ICOMOS, dès sa fondation en 1965 (Colloques de Cacérès (1965), Tunis (1966), Leningrad et Graz (1969), Lausanne (1973), Rothenburg et Bruges (1975)). Si un regard macroscopique révèle le rôle central joué par Piero Gazzola et Raymond Lemaire, respectivement président et secrétaire général de l’ICOMOS et auteurs, avec François Sorlin, d’une étude de synthèse préalable à la Charte européenne, cette contribution se propose d’augmenter la focale afin de révéler, à travers l’étude des actes des colloques, le rôle des réseaux d’acteurs en présence dans l’élaboration de la nouvelle politique. [less ▲]

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See detailDEVELOPMENT OF FUNCTIONAL MICELLES FROM BIODEGRADABLE AMPHIPHILIC BLOCK COPOLYMERS FOR DRUG DELIVERY AND TUMOUR THERAPY
Gulfam, Muhammad ULg

Doctoral thesis (2017)

Drug delivery systems in the size range of ~ 10-250 nm are enabling tools for the site-specific targeting and controlled release applications. To take advantage of these capabilities, various nanocarriers ... [more ▼]

Drug delivery systems in the size range of ~ 10-250 nm are enabling tools for the site-specific targeting and controlled release applications. To take advantage of these capabilities, various nanocarriers e.g., micelles, dendrimers, liposomes, nanoparticles, nanocapsules, nanotubes, and nanogels have been designed for drug delivery. Specifically, micelle-based drug carrier systems have emerged as promising tools for site-specific delivery and controlled release applications. Despite several advantages over conventional drugs, some limitations of micelle-based drug delivery have also been reported. These drawbacks include low stability in vivo, poor penetration, modest accumulation in tumor tissues, and inadequate control over drug release. To overcome these limitations, stimuli-responsive or smart polymeric nanocarriers have been developed for drug delivery and tumour therapy, previously. The most well-known internal stimuli in cancerous regions include higher acidity associated with dysregulated metabolism in tumour tissues, elevated levels of glutathione in the cytosol and nucleus of cancer cells, and altered degradative enzymes in the lysosomes, and reactive oxygen species in the mitochondria. These intrinsic microenvironments can be exploited as internal stimuli to attain active drug release in the tumor tissues or cancer cells. Particularly, the reducing potential inside the cancer cells is considerably higher than found in the extracellular environment and bloodstream. Therefore, such varying redox potential can be exploited for tumor specific drug delivery and controlled release applications. Various types of redox-responsive micelles have been developed previously. Generally, redox responsive micelles have disulfide linkages that undergo rapid cleavage in the presence of reducing agents in the intracellular components, however, are stable at oxidizing extracellular environment. The redox-responsive disulfide bridges can be incorporated into nanocarriers by placing multiple disulfide bonds in the hydrophobic backbone or by conjugating therapeutic agents to the side chain of the polymer via a disulfide linker. Another strategy to construct redox-responsive linkages is to crosslink the polymeric nanocarriers with a disulfide crosslinker. It has been studied that polymeric micelles can dissociate, especially upon administration when they are diluted below their critical micelle concentration. The stability of polymeric micelles can be enhanced by chemical crosslinking. Various types of crosslinked micelles can be prepared subjected to the localisation of the crosslinking, e.g. shell crosslinked micelles, and core crosslinked micelles. Introducing redox-responsive bridges by disulfide crosslinker may not only provide stability to nanocarriers against dilutions during circulation, but also render them responsive to reduction conditions. Specifically, redox-responsive core-crosslinked micelles have demonstrated good stability and better ‘stealth’ properties, however, the hydrophobic cores of most of the existing core-crosslinked micelles have been based on non-degradable polymers such as polyacrylamide or polyacrylate. The non-degradable constituent of the block copolymer may cause complications in clinical applications. Therefore, reduction-responsive core-crosslinked micelles comprising entirely of biologically inert or biocompatible and biodegradable polymers would be better candidates for drug delivery and controlled release application. To overcome these limitations, micelles based on polyesters (a class of aliphatic biodegradable polymers) can used for drug delivery application. In the last few decades, various FDA approved aliphatic polyesters e.g. poly(lactic-co-glycolic acid) (PLGA), poly(ε-caprolactone), and poly(lactic acid), have been intensively studied to exploit their potential in drug, gene and protein delivery and controlled release applications. However, most of these polyesters lack functional groups which make it difficult to incorporate redox-responsive linkages to core-crosslink their micelles. To address these issues, we have synthesized functional biodegradable and biocompatible block copolymers based on mPEG-b-poly(εCL-co-αClεCL). The pendent chloro groups of the block copolymer were converted into azides using nucleophilic substitution reaction to produce mPEG-b-poly(εCL-co-αN3CL) block copolymer as a precursor of reactive polymeric micelles. The synthesized polymers were characterized by NMR, FT-IR and size exclusion chromatography (SEC). Micelles were prepared using dialysis method and methotrexate (an anticancer drug) was loaded into the hydrophobic core of the reactive micelles. Micelles were subsequently crosslinked by a redox-responsive bis-alkyne ethyl disulfide crosslinker. The size distributions and morphology of core-crosslinked micelles were assessed using dynamic light scattering (DLS) and transmission electron microscopy. The drug release studies were performed under simulated non-reducing and reducing conditions. Cellular uptake studies in human breast cancer cells (MCF7 cells) were performed using Oregon-green loaded core-crosslinked micelles. The MTX-loaded core-crosslinked micelles were assessed for their cytotoxicity in human breast cancer cells by MTT assays. The apoptosis inducing potential of MTX-loaded core-crosslinked micelles was analysed using Hoechst/PI assays and was further probed by annexin-V/PI assays. The data from these studies indicate that drug release from these cross-linked micelles can be controlled and that the redox-responsive micelles are more effective carriers for MTX than non-cross-linked analogues in the cell-lines tested. In another strategy, a multifunctional amphiphilic block copolymer based on α-amine-PEG-b-poly(εCL-co-αN3εCL) was synthesized and subsequently was used to conjugate methotrexate on the hydrophilic block for receptor mediated targeting of breast cancer cells. Cellular uptake studies revealed 2.3-fold higher uptake of MTX-conjugated micelles as compared with un-conjugated micelles. The blank micelles showed low cytotoxicities in breast cancer cells, however, MTX-conjugated micelles exhibited greater antitumor activities in contrast to free-MTX. We hypothesize that these functional micelles could be potentially powerful nanocarriers for stimuli-responsive controlled release, active tumour targeting and therapy. [less ▲]

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See detailDépolution des sédiments d’une mangrove de l’estuaire du Wouri : évaluation du potentiel de microflores.
Semboung Lang, Firmin ULg

Doctoral thesis (2017)

L’importance des écosystèmes de mangroves n’est plus à démontrer dans l’équilibre naturel des côtes des régions tropicales. Elles constituent un écosystème particulier et jouent un rôle important dans la ... [more ▼]

L’importance des écosystèmes de mangroves n’est plus à démontrer dans l’équilibre naturel des côtes des régions tropicales. Elles constituent un écosystème particulier et jouent un rôle important dans la production de la biomasse. Mais l’exploitation excessive du bois des palétuviers, les pollutions diverses suite à l’exploitation pétrolière et gazière, sont autant de facteurs qui contribuent à la dégradation des forêts de mangroves. Ainsi, entre 1980 et 2000, environ 35% de la superficie mondiale des mangroves a disparu. La pollution a entraîné une dégradation considérable des mangroves. Une quantité grandissante de déchets résultant des activités urbaines, industrielles et agricoles et de l’exploitation en mer du pétrole et du gaz est rejetée sans aucun traitement dans la mer et se retrouve au niveau des mangroves. Les déversements accidentels d’hydrocarbures en mer entraînent une grave pollution des mangroves et la pollution marine provenant des navires est une menace qui va sans doute s’accroître avec le développement de l’exploitation pétrolière. L’objectif de cette thèse était de mettre au point une méthode de dépollution par voie biologique des sédiments de mangroves pollués par les hydrocarbures. Il s’agissait plus précisément d’évaluer les capacités intrinsèques de dégradation de la microflore spécifique endogène, de comparer le potentiel de dégradation de cette microflore avec d’autres souches pures connues pour leur capacité à dégrader les hydrocarbures et enfin d’évaluer les différentes techniques de biodégradation adaptées pour l’élimination des hydrocarbures dans les sédiments de mangroves. Des procédés biologiques adaptés ont été mis en œuvre au cours de ce travail pour restaurer les écosystèmes de mangroves. Différentes techniques de traitements biologiques impliquant la microflore spécifique endogène ont été mises en œuvre. L’évaluation du potentiel de dégradation de cette microflore a été réalisée par rapport à trois souches pures exogènes. Les résultats obtenus ont montré que le potentiel de dégradation de la microflore spécifique est comparable à celui de Rhodococcus erythropolis lorsqu’on augmente sa concentration dans les sédiments (107 CFU.g-1 de matière sèche). La croissance de cette microflore est accélérée avec la présence des nutriments tels l’azote et le phosphore. Ce qui relève davantage le taux de dégradation des hydrocarbures. Le taux de dégradation obtenu en combinant les traitements par bioaugmentation de la microflore spécifique endogène et biostimulation (86%) nous ont amené à proposer cette méthode pour dépolluer les sédiments de mangroves. L’utilisation de la microflore spécifique endogène évite de travailler avec des souches exogènes qui nous exposent aux problèmes écologiques et éthiques liés à leur utilisation. [less ▲]

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See detailAdaptation et psychopathologie
Englebert, Jérôme ULg

Scientific conference (2017, January 26)

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See detailModélisation de la réponse au hasard dans les questionnaires à choix multiples : une approche par modèles de réponses aux items polytomiques
Magis, David ULg

Conference (2017, January 25)

Lorsque l’on doit évaluer les résultats d’un test à l’aide de questions à choix multiples (QCM), le traitement des réponses au hasard (« guessing ») est un enjeu crucial pour une évaluation fiable et non ... [more ▼]

Lorsque l’on doit évaluer les résultats d’un test à l’aide de questions à choix multiples (QCM), le traitement des réponses au hasard (« guessing ») est un enjeu crucial pour une évaluation fiable et non biaisée de la compétence testée. Divers mécanismes (comme l’application d’une correction pour le guessing) ont été proposées mais ne sont pas exemptes de problèmes méthodologiques. Une approche par modèles de réponses aux items (MRI) est aussi souvent considérée, mais revient à résumer les réponses des QCM en « vrai/faux » et appliquer des modèles dichotomiques (comme le modèle logistique à trois paramètres). Le but de cette présentation est double : (a) mettre en évidence les faiblesses d’une telle approche dichotomique, et (b) présenter une modification d’un modèle de réponses aux items polytomiques qui prend en compte le possible « guessing » des participants. Cette approche a l’avantage de modéliser chaque réponse possible (y compris les distracteurs) tout en autorisant une réponse au hasard pour les participants de compétence plus faibles. Une comparaison des approches dichotomique et polytomique est réalisée au moyen de données simulées selon un modèle de réponse au hasard plausible. Les avantages et inconvénients de l’approche polytomique, tant du point de vue technique que pédagogique, sont discutés. [less ▲]

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See detailLa détection des réponses inappropriées dans les examens: une étude de 3 indices corrigés selon la méthode de Snijders
Béland, Sébastien; Raîche, Gilles; Magis, David ULg

Conference (2017, January 25)

Certains étudiants peuvent répondre au hasard ou être inattentifs en situation d’examen. Les indices de détection de patrons de réponses inappropriés (person-fit index) sont prometteurs pour détecter ces ... [more ▼]

Certains étudiants peuvent répondre au hasard ou être inattentifs en situation d’examen. Les indices de détection de patrons de réponses inappropriés (person-fit index) sont prometteurs pour détecter ces types de réponse. Nous allons, dans le cadre de cette communication, nous pencher sur le cas de trois indices de détection populaires qui présentent des caractéristiques permettant d’en faciliter l’interprétation : lz, ZU et ZW. Par contre, des études antérieures ont montré que ces trois indices sont fortement affectés par le fait que l’habileté d’un étudiant est estimée plutôt que réelle (Molenaar et Hoijtink, 1990). Snijders (2001) a proposé une version corrigée de l’indice lz (nommée lz*) afin de tenir compte de cette difficulté. De leur côté, Magis, Béland et Raîche (2014) ont corrigé deux autres indices selon l’approche de Snijders (2001) : U* et W*. Il reste cependant à analyser plus en détails le comportement de la famille des indices corrigés, soit, lz*, U* et W*. Pour ce faire, nous effectuons une étude de simulation et une étude des données du test de classement en anglais, langue seconde (TCALS-II). Les résultats démontrent que les indices corrigés lz* et W* sont les plus intéressants à utiliser. De son côté, U* présente des résultats parfois inappropriés, ce qui relance la réflexion sur la pertinence des indices de détection basés sur les carré-moyens non-pondérés. [less ▲]

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See detailLes pathologies de l’adaptation et l'adaptation des pathologies
Englebert, Jérôme ULg

Scientific conference (2017, January 21)

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See detailPhotocleavable stabilizer for the preparation of PHEMA nanogels by dispersion polymerization in supercritical carbon dioxide
Alaimo, David; Grignard, Bruno ULg; Kuppan, Chandrasekar et al

in Polymer Chemistry (2017), 8(3), 581-591

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a ... [more ▼]

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a light sensitive o- nitrobenzyl group was successfully synthesized by RAFT polymerization and used as stabilizer for the free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in dispersion in ?,?,?-trifluorotoluene and supercritical carbon dioxide (scCO2). Thanks to this fluorinated stabilizer, well-defined particles of PHEMA down to 350 nm of diameter were produced in scCO2. Advantageously, the photocleavable group at the block junction of the stabilizer could be cleaved by exposing the particles to UV light so that the fluorinated block could be extracted in TFT or scCO2. As supported by X-ray photoelectron spectroscopy (XPS) analysis, up to 80 % of the fluorinated block of the stabilizer can be removed, leading to efficient swelling and dispersion of the resulting PHEMA nanogels in water. [less ▲]

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See detailCharacterization of High Altitude Clouds at the Martian Limb and Terminator Using MAVEN IUVS Observations
Deighan; Stiepen, Arnaud ULg; IUVS team

Conference (2017, January 20)

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See detailMars Ozone mapping with MAVEN IUVS
Lefèvre; Stiepen, Arnaud ULg; IUVS team

Conference (2017, January 20)

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See detailStatistical description of hydrogeological parameters for the main aquifer contexts in Wallonia
Briers, Pierre ULg; Dollé, Fabien ULg; Orban, Philippe ULg et al

Conference (2017, January 20)

The Walloon Region Soil decree proposes a series of guidance documents associated to the procedures for site remediation operations. Among others, one of these documents describes methodologies and tools ... [more ▼]

The Walloon Region Soil decree proposes a series of guidance documents associated to the procedures for site remediation operations. Among others, one of these documents describes methodologies and tools for risk assessment of pollutant leaching from soil to groundwater and for pollutant dispersion through groundwater. These tools require using estimates of hydrogeolocial parameters such as hydraulic conductivity, effective (transport) porosity etc. In this context, an inventory of hydrogeological studies (regional characterization studies, groundwater protection zones…) was performed to identify and collect available field-based measurements for a statistical description and analysis of such data. Complementary to that, a simple geodatabase has been developed to manage and process these data. As expected, these results show contrasted parameter distributions per geological contexts and regions. The objective of the presentation is to describe the methodology followed for the statistical treatment of hydrogeological data and to present the results and associated database. It is believed that such results can be very useful for different hydrogeological studies, in particular as a first referential for groundwater modelling applications and any other studies where statistical descriptions of hydrogeological data are relevant. [less ▲]

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