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See detailFirst-principles and experimental studies of hexagonal YMnO3 single crystals and epitaxial films
Prikockyte, Alina ULg

Doctoral thesis (2012)

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk ... [more ▼]

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk and in thin film forms. Yttrium manganite belongs to the class of ABO3 compounds. Most theoretical studies of ferroelectricity to date were concentrated on cubic perovskite ABO3. Yttrium manganite is hexagonal and is an improper ferroelectric. We were interested to study theoretically and experimentally how these two features behave in thin film form. Our study is organized as follows. [less ▲]

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See detailLe nationalisme algérien et ses diverses expressions dans l'immigration en France métropolitaine entre 1945 et 1965
Abssi, Marion ULg

Doctoral thesis (2012)

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des ... [more ▼]

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des différentes organisations nationalistes algériennes représentées en métropole, et des conflits ayant opposés les Algériens aux Européens mais aussi et surtout les Algériens entre eux durant toute la période considérée. [less ▲]

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See detailDevelopment of a transmission model of Murid herpesvirus 4
François, Sylvie ULg

Doctoral thesis (2012)

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural ... [more ▼]

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural condition has been limited by the fact that no experimental transmission model exists. Establishment and characterization of a model of transmission are therefore critical points to evaluate strategies of interference with the epidemiological cycle of gammaherpesviruses. We are studying Murid herpesvirus 4 (MuHV-4) which has originally been isolated from naturally infected bank voles (Myodes glareolus). Although serological data indicate that closely related strains are present in wood mice (Apodemus sylvaticus) and domestic mice (Mus musculus), no experimental transmission of MuHV-4 has been demonstrated in laboratory mice, the classically used in vivo model. The objective of this work was therefore to fill this gap. In a first study, we performed a comparative characterization of the infection by MuHV-4 in mice and bank voles. Our results showed that the infectious process, the pathology and the latency establishment are similar in the two species, even if replication is quantitatively lower in bank voles than in mice. It therefore appeared that, Mus musculus represents a suitable host for studying gammaherpesvirus pathogenesis with MuHV-4. These results have been published in Journal of General Virology (J Gen Virol. 2010 Oct;91(Pt 10):2553-63). In a second study, thanks to in vivo imaging, we have been able to observe, for the first time, transmission of MuHV-4 in mice. We firstly showed that MuHV-4 reexcretion occurs in the genital tract of female mice at a period by which latency is considered as established. Ex vivo imaging, histology and PCR allowed us to demonstrate the presence of viral genomes in vaginal tissues and to localize viral replication at the external border of the vagina. We also demonstrated the transient and repetitive presence of infectious viruses in the vaginal cavity. Secondly, we demonstrated the implication of sexual steroid hormones in this re-excretion process. Indeed, we analyzed the infection of untreated mice, ovariectomized mice and ovariectomized mice complemented with estrogens and/or progesterone. These analyses revealed a positive role of estrogens in the observed re-excretion. Finally, based on these results, we tested MuHV-4 transmission in mice by creating different epidemiological conditions. In the conditions tested, vertical transmission did not occur, nor did horizontal transmission between individuals of the same gender. In contrast, we were able to observe sexual transmission to naïve males by serology, in vivo imaging and quantitative PCR. In conclusion, this work has on one hand demonstrated the quality of mice as an in vivo model for MuHV-4 studies and, on the other, it has shown for the first time the existence of re-excretion and sexual transmission of MuHV-4 amongst laboratory mice. The results of this work should therefore have implications for the study of gammaherpesviruses, but also more generally for the study of sexually transmissible infections. [less ▲]

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See detailIonosphere Modelling for Galileo Single Frequency Users
Bidaine, Benoit ULg

Doctoral thesis (2012)

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ... [more ▼]

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ionospheric effect affecting the signal propagation from the satellites. This propagation is delayed by the free electrons in the atmosphere so that the navigation signals appear to travel distances larger than actual ones by 7 m on average. Hence this delayed propagation deteriorates the positioning accuracy deemed on a 10−m level for mass-market applications mainly involving single frequency users. Tomorrow the European navigation system Galileo will offer a new mitigation strategy to single frequency users. This strategy will rely on the NeQuick ionospheric model and associated broadcast information. To be properly implemented, it must be extensively described to future Galileo users. These users will also wonder about its effectiveness in accounting for the ionospheric delay. The PhD research covered by the present thesis has built on Belgian expertise in ionosphere monitoring to investigate the NeQuick model and its use for Galileo. It began with the collection and handling of ionosphere measurements including GPS data. It analysed various situations at different places in the world encompassing a whole year (2002). This PhD thesis provides the ins and outs of the Galileo Single Frequency Ionospheric Correction Algorithm. It gathers an algorithm description, a performance evaluation and a variant investigation. In the shape of a paper collection, it discloses many figures as visual entry-points into the juxtaposed text and includes many references allowing to dig into the details. The algorithm performances are usefully characterised both in terms of delay mitigation and positioning accuracy. On the one hand, the residual ionospheric delay reaches 31% for the chosen sites and year. On the other hand, the positioning accuracy amounts to 6 m horizontally and 9.3 m vertically. The performance evaluation allowed to emphasise several aspects of the Galileo ionospheric correction. This correction depends largely on the modelling of the topside, the upper part of the ionosphere, which hosts more complex physical processes. It owes its good performances to data ingestion, the model adaptation technique to actual measurements underlying the Galileo algorithm. It does not necessarily provide highly correlated correction levels in terms of delay on the one hand and positioning on the other. It enables the definition of alternative regional procedures following a compatible design but coping with its weaknesses. The present thesis paves the way for future work related to ionosphere modelling for Galileo single frequency users. It supplies comparative information for the algorithm assessment in the framework of successive phases of Galileo deployment. It establishes a conceptual basis for an Assisted Ionospheric Correction Algorithm (A-ICA) disseminating more flexible ionospheric information thanks to the integration of Global Navigation Satellite Systems and telecommunications. [less ▲]

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See detailEtude hydrogéologique du système aquifère du horst de Diass en condition d’exploitation intensive (bassin sédimentaire sénégalais) : apport des techniques de télédétection, modélisation, géochimie et isotopie
Madioune, Diakher Hélène ULg

Doctoral thesis (2012)

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante ... [more ▼]

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante destinée à l’Approvisionnement en Eau Potable (AEP) de la ville de Dakar et des localités de Sébikotane, Pout, Mbour ainsi que leurs besoins industriels et agricoles. La configuration géométrique du système est caractérisée par quatre failles majeures délimitant un horst où affleure la nappe du Maastrichtien gréso-calcaire et sablo-gréseux du compartiment de Diass encadrée par les compartiments calcaires affaissés de Sébikotane et de Pout qui hébergent la nappe captive à libre du Paléocène. L’exploitation de ce système a progressivement évoluée pour atteindre actuellement plus de 109000 m3/j environ avec cinq principaux centres de captage. Cette exploitation intensive a provoquée une baisse continue du niveau des nappes, un changement dans le régime des flux et une salinisation dans les zones de Sébikotane et de Mbour. Ainsi donc, il est nécessaire d’étudier les caractéristiques des aquifères notamment, leurs relations hydrauliques verticales et latérales. Cependant, cette étude reste difficile en raison de la complexité de la configuration géométrique du système et des pompages intensifs. La présente étude vise à contribuer à une meilleure compréhension du fonctionnement hydrodynamique du système pour une bonne gestion durable des ressources en eau. Plus précisément, il vise à déterminer : (1) le comportement spatio-temporel de l’hydrodynamisme et de l’hydrochimisme du système en rapport avec les pompages, (2) la recharge actuelle des eaux souterraines, (3) les zones potentielles de recharge nécessaires au calcul du bilan. Pour atteindre ces objectifs, une approche multidisciplinaire comportant une étude piézométrique, hydrogéochimique, d’estimation de la recharge spatialement distribuée et de modélisation a été utilisée. Les variations spatio-temporelles de la piézométrie depuis les années 1960 en rapport avec la configuration hydrogéologique combinées aux données chimiques et isotopiques ont été considérées pour fournir une meilleure compréhension du fonctionnement hydrodynamique du système et établir le modèle conceptuel de circulation des eaux. Les méthodes de Thornthwaite et Penman sont utilisées pour estimer la recharge qui a été spatialement distribuée sur les zones potentielles de recharge. Les enseignements clés tirés de ces différentes approches sont utilisés comme paramètre d’entrée du modèle hydrogéologique 3D développé et calibré en régime permanent et transitoire pour les périodes 1960-1971 et 1971-2009 respectivement. Les résultats montrent l’influence prépondérante des pompages sur le niveau piézométrique favorisant ainsi la drainance verticale et latérale vers les captages. Les données chimiques et isotopiques reflètent la dynamique du système. Les faibles teneurs en tritium et en 14C montrent une absence de recharge actuelle et une prédominance d’eaux anciennes dans le système. Cependant, la présence d’eau tritiée au droit de quelques forages indique un mélange avec des eaux récentes par drainance verticale descendante et/ou par écoulement latéral. Le fonctionnement hydrodynamique dérivé de ces résultats montre que le réservoir fonctionne comme un système aquifère multicouche avec des compartiments interconnectés par des failles qui favorisent des échanges de flux. L’aquifère du Quaternaire est alimentée par l’infiltration des eaux de pluie particulièrement dans la zone de Mbour (1) ; cette aquifère est drainé par les nappes profondes du Paléocène et du Maastrichtien (2) ; ce dernier draine le Paléocène (3), les écoulements latéraux se font du Maastrichtien de Diass vers le compartiment de Pout Sud et à partir du compartiment de Thiès vers le compartiment de Pout à travers les failles de Pout et de Thiès respectivement (4). [less ▲]

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See detailAdaptations structurales et fonctionnelles aux températures extrêmes au sein de la famille des alpha-amylases chlorure-dépendantes
Cipolla, Alexandre ULg

Doctoral thesis (2012)

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été ... [more ▼]

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été initiées et publiées. La première est basée sur la "mésophilisation" de l’α-amylase psychrophile AHA, issue de la bactérie Antarctique Pseudoalteromonas haloplanktis. L’ajout d’interactions faibles et d’un pont disulfure présents chez son homologue mésophile PPA de Sus scrofa et absents chez AHA ont permis de construire deux mutants multiples stabilisés, Mut5 et Mut5CC. Ces quatre enzymes ont été étudiées sur base de leur stabilité, de leur activité et de la perméabilité de leur structure protéique. L’étude des cinétiques de renaturation/dénaturation d’AHA, Mut5 et Mut5CC a permis de déterminer l’origine cinétique du gain de stabilité liée à l’ajout d’interactions faibles et du pont disulfure chez AHA. Il en résulte que Mut5 et Mut5CC ont effectivement été stabilisés mais en contrepartie ils ont perdu l’optimalisation de l’activité à basse température observée chez AHA. De plus, la perméabilité de leur structure protéique s’est réduite, se rapprochant de celle de PPA. L’origine du gain de stabilité est liée à une diminution des cinétiques de dépliement sans modification des cinétiques de repliement. Non seulement ces résultats démontrent l’importance du rôle des interactions faibles dans l’adaptation thermique des protéines mais de plus, ils démontrent la synergie entre celles-ci. La seconde étude a pu être développée par la découverte d’une α-amylase chlorure-dépendante thermophile TFA issue de l’actinomycète Thermobifida fusca et par la production de l’α-amylase chlorure-dépendante mésophile ectotherme DMA de Drosophila melanogaster. Ainsi avec AHA et PPA respectivement comme représentants psychrophile et mésophile homéotherme, nous pouvions couvrir l’ensemble des températures physiologiques/environnementales connues. Nous avons pu mettre en évidence le continuum des propriétés physico-chimiques observées (activité, stabilité, affinité pour le substrat…) mais aussi que l’énergie thermique de l’environnement influence grandement l’activité enzymatique qui ne serait pas contrebalancée par les mécanismes adaptatifs. L’influence de la température sur l’activité a mis en évidence la plus faible dépendance d’AHA par rapport à TFA. Ces travaux ont permis d’améliorer notre compréhension des mécanismes moléculaires liés à l’adaptation thermique des protéines et du rôle joué par les interactions faibles dans cette adaptation. Ils ouvrent aussi la voie à de futures recherches visant à analyser par d’autres méthodes la flexibilité de la structure protéique et à cristalliser TFA pour étudier d’un point de vue structural le continuum des propriétés physico-chimiques mis en évidence au cours de ce travail. [less ▲]

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See detailPresent and future Greenland ice sheet surface energy balances with the help of the regional climate MAR model
Franco, Bruno ULg

Doctoral thesis (2012)

See enclosed abstract-and-contents.pdf

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See detailStructure and Lattice Dynamics of Thermoelectric Complex Chalcogenides
Bauer Pereira, Paula Beatriz Lee ULg

Doctoral thesis (2012)

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe ... [more ▼]

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe, SnTe and GeTe. Synchrotron radiation studies including high energy X-ray di raction and nuclear inelastic scattering, and macroscopic measurements of heat capacity and elastic constants were performed. A new resonant ultrasound spectroscopy setup with capable of performing measurements from room temperature to 1073K was built for mechanical characterization of the thermoelectric alloys at their working temperatures. The rst chapter presents a brief review of relevant information on thermoelectricity and on the materials under study. The characterization methods including heat capacity, resonant ultrasound spectroscopy, X-ray di raction and nuclear inelastic scattering are introduced. Not as an exhaustive review, but rather in order to give the reader a basic level of understanding and a sense of the acessible information. The introduction is followed by three chapters which address the experimental studies of lattice dynamics in chalcogenide alloys. Chapter 2 describes the lattice dynamics in the compounds GeTe, SnTe and PbTe studied by 119Sn and 125Te nuclear inelastic scattering. The obtained partial density of phonon states were compared with published theoretical calculations, and the resulting vibrational properties were found to be in good agreement with these reports. Additionally, the phase purity and structure were characterized by high energy X-ray di raction. The atomic arrangement, rhombohedral for GeTe and cubic for SnTe and PbTe, is seem to a ect the density of phonon states, with the NaCl-type structure having a softer character in comparison with the rhombohedral structure. In Chapter 3, the lattice dynamics of a polycrystalline AgSbTe2 sample was investigated by 121Sb and 125Te nuclear inelastic scattering, at low temperatures. For this compound, the phonon modes have energies below 25meV and a sound velocity of vs =1490(30) m/s was determined. A simple temperature independent estimation of the lattice thermal conductivity of AgSbTe2 yielded L =0.50 0.05Wm􀀀1K􀀀1. The low Debye temperature, D =150(15)K combined with the short phonon lifetime and the low sound velocity are found to be key factors for the low thermal conductivity in AgSbTe2 and are related to the good thermoelectric performance in AgSbTe2 and AgSbTe2containing systems. Chapter 4 is dedicated to the study of the average and local structure in bulk AgPb18SbTe20 alloy, by a combined Rietveld and Pair Distribution Function analysis. The strong in uence of the synthesis conditions on the lattice parameters and on the composition and the concentration of nanoclusters in LAST-18 is con- rmed. Moreover, the 121Sb and 125Te partial density of phonons states were obtained by nuclear inelastic scattering in order to separately characterize the lattice dynamics from the matrix and the nanoinclusions. Additional characterization of the elastic properties and lattice governed properties were performed by resonance ultrasound spectroscopy, heat capacity and thermal expansion measurements. The nal chapter is dedicated to the resonant ultrasound spectroscopy technique, and the process of building up this bu er-rods high-temperature measurement system are presented. Advantages and disadvantages, as well as limitations and di culties are discussed. Using the \mode-tracking" method, the mechanical behavior of a PbTe and a Niobium sample, from room temperature to 523K and from room temperature to 973 K, respectively, were investigated. [less ▲]

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See detailA multiaxial constitutive model for concrete in the fire situation including transient creep and cooling down phases
Gernay, Thomas ULg

Doctoral thesis (2012)

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need ... [more ▼]

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need for proper concrete model remains a very challenging task in structural (fire) engineering because of the complexity of the concrete mechanical behavior characterization and the severe requirements for the material models raised by the development of performance-based design. Methodology - The thesis opted for a phenomenological approach for modeling the thermo-mechanical behavior of concrete. The specifications of the model are based on the study of published experimental data of concrete samples tests and on the specific needs related to the applications in structural fire engineering. With these specifications in mind, a state of the art review of concrete models is conducted in order to choose the general theoretical framework that best fits the criteria for the development of the new model. The thesis presents the theoretical development of the model and its numerical implementation in a finite elements software. Numerical simulations of experimental tests are then performed to verify that the model satisfy the specifications. Findings - The combination of elastoplasticity theory and damage theory allows to develop a phenomenological model suitable for concrete behavior modeling within the pragmatic and robust theoretical framework of continuum constitutive models based on smeared crack approach. The state of damage in concrete, assumed isotropic, is modeled by means of a fourth order damage tensor to capture the unilateral effect. When complex performance-based situations are considered, the effect of transient creep strain at high temperature must be taken into account by an explicit term in the strain decomposition. A generic transient creep model is therefore developed based on experimental data and the model is calibrated to yield the same results as the Eurocode implicit model in simple prescriptive situations. The concrete model comprises a limited number of parameters that can be identified by three simple tests; besides, a standard set of values to be used in predictive calculations is clearly defined for these parameters. Numerical simulations can deal with all stress states as the model is developed as fully three-dimensional. A large number of examples highlight the capabilities of the model that range from the modeling of sample tests to the modeling of large scale composite structures developing membrane action. Limitations – Due to the assumption that damage and plasticity are driven by the same internal variables in the model, a limitation appears for capturing the concrete post-peak behavior in highly confined stress states. This assumption allows for reducing the number of parameter but it restrains the domain of applicability of the model; it is suggested to adopt a different approach if the behavior in multiaxial compression at high confinement level has to be accurately captured. Another limitation of the model is related to the localization issue, which is only partly addressed in this work by means of the regularization of the crack energy. Further works should bring a more elaborated response while considering the case of reinforced concrete structures, in which numerous cracks develop. Finally, several simplifying assumptions have been adopted to restrain the scope of the research; for instance, the phenomenon of spalling has not been considered. Practical implications - The thesis includes implications for the development of advanced numerical tools for the simulation of concrete structures at ambient temperature and at high temperature. The use of such advanced tools in the design may lead to significant reduction in the building costs and to improved robustness of the structures. Value – The thesis contributes to fulfil an identified need to make available proper constitutive concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. Special care is given to the numerical robustness of the model and to the clear definition of the material parameters as the model is intended to be used by structural (fire) engineers in real applications. [less ▲]

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See detailThe Unharnessed World: Janet Frame and Buddhist Thought
Gabrielle, Cindy ULg

Doctoral thesis (2012)

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage ... [more ▼]

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage point of its indebtedness to Eastern epistemologies, and to Buddhism in particular. Even though it is possible to establish links between an author and a given system of thought (Heidegger’s for instance) without necessarily buttressing the comparison from a factual perspective, in this case, the author’s (auto-)biography, her fiction and letters, as well as the circles of Buddhists or Buddhist-sympathizers in which she evolved at a given time, all testify to the fact that a direct encounter between Janet Frame and Buddhism did occur. It can thus be affirmed that, just like W.B. Yeats, C.G. Jung, Heidegger and many others before her, one of the most striking personalities of the 20th century was drawn eastward. The relevance of this study to Janet Frame scholarship resides not only in its politicized angle of approach but also, more importantly, in the fresh light it sheds on entire segments of the Framean corpus which have tended to remain obdurately mysterious; this includes passages centering on e.g. the existence of a non-dual world, a reality un-harnessed by the partial categories of empirical thinking, on a character’s sudden embrace of a non-ego-like self, or on the jolting back of distracted individuals into an awareness of their physical reality in ‘this’ profane world. On the whole, and despite this apparent profusion of themes, my concern is to show that these obscure passages, as well as many other key moments in the narratives, all coalesce into a systematic deconstruction of empirical thinking and its point of anchorage in a discriminating kind of consciousness, both notions forming excellent points of entry into virtually all the texts produced by Frame. Through a careful mapping of the impact of discriminating habits of thought on the self’s place of being in the world and perception thereof, this work clarifies, or rather reconstructs, the narratological architecture of the studied texts – especially the novels – quite apart from the somewhat restrictive view, held in some circles of literary criticism, that they are mazes of random turnabouts and dead-ends where narrotological playfulness is valorized for its own sake. To provide just one example of how a study of Janet Frame via Buddhist thought facilitates the navigation of the author’s intricate novels, the idea in Buddhism that the artist is the bow that shoots the arrows, but then s/he is the target also, is a useful starting point for analyzing the seminal “Jan Godrey” (one of Frame’s best known short stories) in which a terrified author-figure finally allows her creature of words, described as an alien inside, to take full control of the speaking position. A contrario, Thora Pattern’s willingness in The Edge of the Alphabet to trap her creation within neat academic cages of words (as she calls them) spawns images of a hellish self-scape of containment which translate in an endless regression of framed frames since her attitude is paralleled by some of her own creatures of words and by the Christian God Himself – each at his or her level of being and of influence. But that is not all for, in a last turn of the screw, and pace the critics who diminish their roles in the narrative, Thora’s characters rebel against their creator, and they succeed in jamming her creative incarcerating mechanisms so that, by the end of the novel, the author-figure is no longer able to exist without the not-self. This dialectics of un/framing, in which a discriminating consciousness battles against the invading otherness of the non-dual, unharnessed world in all its manifestations, is one which typically informs the Framean corpus although, of course, the architecture of enactments it gives birth to is as varied as it is unpredictable. The idea, which Frame shares with Buddhism or with Nietzsche (who, incidentally, owes an intellectual debt to Buddhism), that most of the human existence is characterized by the “will to power,” i.e. by the drive to take full possession of one’s chosen place of being, is rather unflattering for her fellow human beings. In another sense, the author’s conception of our (in-)humanity as being made up of an accretion of egotistic habits that can be unlearned certainly explains why, in her oeuvre, a liberation from totalizing structures demands an encounter with the negative of place, of identity, of vision, of sound, of fullness, of shape, of well-worn mind-routes and, as we saw in the last chapter, with the negation of negation. Often, it takes no less than a rebellion of the supposedly harnessed reality to disorient a protagonist’s dualistic bearings or to jam an artist’s incarcerating mechanisms; and this, in part, accounts for the extreme physicality encoded in a fiction replete with moments of thumping or bashing – indeed with the promise of a cut finger. Still pondering the centrality of ‘unframed’ or ‘ego-less’ modes of being, each of the nine chapters that constitute this work aims at countering the oft-recurring claim that Frame’s oeuvre is studded with traces of a ‘beyond’ which no character can ever approach because ‘one cannot explore beyond’. By this definition, each of the questing selves that clutters the author’s haunting universe is condemned to failure beforehand, as it were, while concomitantly the Framean text itself is deemed to be bleak, defeatist, even nihilistic. Therefore, it is of the utmost significance that a Buddhist navigation of Frame’s texts should lead one to the conclusion that this unharnessed world which human beings are often unable to apprehend and embrace has always been right under their nose so that, between ‘this’ world of limited perceptions and ‘that’ world of the beyond, the boundary is as thick or as thin as the walls of a self-made conceptual prison. Indeed, whenever the aspect of the intellect that filters perceptions into mutually excluding categories fails to function, or is willingly jettisoned by a protagonist, s/he finds a place of subjective arrival in, and sees, this supposedly unknowable ‘beyond’. Thus, possibly against the grain of mainstream criticism, this study argues that Janet Frame constantly seeks ways through which the infinite and the Other can be approached, though not corrupted, by the perceiving self, and that she found in the Buddhist epistemology a pathway towards grasping such alterity. [less ▲]

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See detailSubstrats cérébraux des processus moteurs automatiques et inconscients
D'Ostilio, Kevin ULg

Doctoral thesis (2012)

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See detailLe terrorisme à motif religieux en Turquie : Recrutement, profils et motivations des membres du Hizbullah turc
Gülver, Murat ULg

Doctoral thesis (2012)

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance ... [more ▼]

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance. Plus de dix organisations terroristes, se basant sur une idéologie religieuse, ce sont organisées sur le territoire turc dans le but de changer le système politique et pour fonder un État islamique. Dans cette recherche, nous avons examiné le cas du Hizbullah turc, en tant que la plus grande et la plus violente organisation terroriste à motif religieux en Turquie. Cette étude a exploré d’abord les méthodes de recrutement du Hizbullah, ensuite les profils de ses militants et enfin les motivations individuelles et les facteurs, qui se trouvent à la base de la radicalisation religieuse en Turquie. Pour ce faire, l’examen quantitatif et qualitatif de données originales comble les principales lacunes dans la recherche sur le terrorisme à motif religieux et donne des indications pour de futures recherches criminologiques et de politiques de sécurité préventives. Dans cette étude, pour examiner et comprendre le recrutement, les profils et les motivations des membres du Hizbullah, nous avons utilisé essentiellement deux sources : les autobiographies des militants eux-mêmes et les entretiens semi-structurés avec des policiers spécialistes du terrorisme à motif religieuse, ainsi que des desservants du culte islamique, qui ont une expérience dans les régions où le Hizbullah était actif. Cette recherche entend apporter une contribution significative à la compréhension des motivations individuelles des militants du Hizbullah, à l’identification des caractéristiques des membres, et à la définition des méthodes de recrutement de l’organisation. Elle propose en outre de nombreuses informations aux organisations de sécurité pour la lutte antiterroriste. [less ▲]

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See detailLa protéine JNKBP1 agit comme un régulateur négatif de la signalisation de NOD2 en inhibant son processus d’oligomérisation
Lecat, Aurore ULg

Doctoral thesis (2012)

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui ... [more ▼]

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui induit les différentes cascades de signalisation conduisant à l'activation de NF-κB, des MAPKs et de l'autophagie. Ces voies contribuent à une réponse immunitaire innée et adaptative efficace. La perte de fonction des mutants NOD2 a été associée à une plus grande susceptibilité à la maladie de Crohn, ce qui souligne l'importance physiologique de la régulation de l'activité de NOD2. Nous avons effectué une étude par une approche protéomique pour rechercher de nouveaux régulateurs de NOD2. Nous avons généré un modèle cellulaire pour cette étude, les cellules HEK293GNV. Nous avons identifié plusieurs nouveaux partenaires de NOD2, dont la protéine JNKBP1 (c-Jun N-terminal kinase binding protein 1), une protéine scaffold caractérisée par un domaine WD40 en amino-terminal. Nous avons aussi débuté la caractérisation d’autres protéines appartenant aux complexes NOD2 purifiés comme ROCK2 (Rho activated kinase 2) et HDAC5 (Histone deacetylase 5). Au vu de nos premiers résultats, les protéines ROCKs sembleraient être des activateurs de la voie NOD2. Nous nous sommes principalement consacrés à l’étude de JNKBP1 qui a été identifiée, en 1999, comme un partenaire et un régulateur positif de JNK. Nous avons montré que JNKBP1 via son domaine WD40, se lie à NOD2 suite à l’activation par le MDP. Cette interaction atténuait l'activation de NF-κB dépendante de NOD2, la synthèse de l'IL-8 et l’activité antibactérienne de NOD2. JNKBP1 exerçait son effet répresseur en perturbant l’oligomérisation NOD2 et la phosphorylation de la tyrosine de RIP2 : deux étapes nécessaires à la signalisation en aval. En outre, nous avons montré que JNKBP1 et NOD2 étaient exprimées dans l'épithélium intestinal humain et dans les cellules immunitaires recrutées dans la lamina propria, ce qui suggère que JNKBP1 contribuerait au maintien de l'homéostasie intestinale dépendante de NOD2. [less ▲]

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See detailStructure and Lattice Dynamics of Bismuth Telluride Nanostructures
Bessas, Dimitrios ULg

Doctoral thesis (2012)

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics ... [more ▼]

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics of bulk and nanostructured bismuth telluride, a chapter on lattice instabilities observed in bulk EuTiO3 around room temperature, and a chapter on the development of a resonant ultrasound spectrometer for small samples. First, the lattice dynamics in bulk Bi2Te3 and Sb2Te3 were investigated by nuclear inelastic scattering, diffraction of high energy synchrotron radiation and calorimetry. In combination with earlier inelastic neutron scattering data, the element specific density of phonon states was extracted not only for Te and Sb but also for Bi. The Bi-Te bonding in Bi2Te3 is fundamentally different than the Sb-Te bonding in Sb2Te3. It appears that the Te specific density of phonon states is mostly unaffected upon substitution of Sb with Bi. Phonon polarization analysis was conducted in a Bi2Te3 single crystal. The observed low lattice thermal conductivity in bulk Bi2Te3 and Sb2Te3 results essentially from the small acoustic cut off energy. Second, the lattice dynamics in elemental modulated Sb2Te3 films were studied by nuclear inelastic scattering and diffraction of high energy synchrotron radiation. These studies reveal that the main features in the Sb specific density of phonon states arise from the layered structure. The extracted average speed of sound is practically the same as in bulk Sb2Te3. The impact of the acoustic cut off energy is further highlighted. Third, the phonon confinement in a Bi2Te3 nanowire array was studied by nuclear inelastic scattering, diffraction of high energy synchrotron radiation, scanning as well as transmission electron microscopy. For the first time the element specific density of phonon states was measured on nanowires in two perpendicular orientations. The much lower than in bulk average speed of sound measured in 56 nm diameter nanowires is directly related to the confined dimensions. The related 50 % decrease in macroscopic thermal conductivity is in line with macroscopic measurements on similar nanowires. Fourth, a detailed structural and lattice dynamical investigations of the bulk cubic perovskite EuTiO3 revealed a lattice instability close to room temperature. The low temperature phase is associated with anharmonic europium displacement and has a significant impact in the lattice dynamics. Last, a resonant ultrasound spectrometer for measurements on small samples and thin films was developed. Successful measurements versus temperature of the elastic constants were carried out with sub-percentage accuracy on oriented single crystals smaller than 1 mm3. [less ▲]

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See detailThe role of sleep in the consolidation of rewarded and relational memory
Gaggioni, Giulia Alice ULg

Master's dissertation (2012)

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See detailBiologie et Ecologie du Martin- pêcheur huppé (Alcedinidae : Alcedo cristata, PALLAS 1764) de la région de Kinshasa: habitat, tactique alimentaire et reproduction.
Kisasa Kafutshi, Robert ULg

Doctoral thesis (2012)

Pour expliquer la rareté de sites de nidification du Martin-pêcheur huppé dans la région de Kinshasa, trois hypothèses ont été successivement testées au cours de ce travail. Une première hypothèse ... [more ▼]

Pour expliquer la rareté de sites de nidification du Martin-pêcheur huppé dans la région de Kinshasa, trois hypothèses ont été successivement testées au cours de ce travail. Une première hypothèse suggérait que le choix de son habitat de reproduction résulterait d’un compromis entre le taux de survie de ses nids, de son succès reproducteur et de la qualité des sols utilisés pour la construction des nids. Le résultat obtenu a révélé qu’un sol propice à l’excavation est constitué de 10,8 ± 6,1% de limon, 7,5 ± 6,6% d’argile et de 81,4 ± 11,4% de sable. Par contre les falaises dont les sols sont constitués en moyenne de 8,5±5,6% de limon ; 11,6±6,5% d’argile et de 78,9±13% de sable, étaient soit abandonnées, soit non occupées. Il semble que la teneur en argile pour un sol favorable chez la plupart des oiseaux nichant dans le terrier est généralement inférieure à 10%. Une différence d’environ 1% de teneur en argile, en comparaison avec les falaises abandonnées ou sans nids dans la région, nous a paru inconcevable pour relier l’absence des nids dans certains habitats naturels avec la dureté des sols. La seconde hypothèse confirme le rôle de la relation structure fonction à partir des suivis réguliers de 138 poussins de l’éclosion à la sortie des nids. Le résultat obtenu montre que la croissance et le développement des organes expliquent le patron de consommation de l’espèce et les paramètres plus ou moins importants à la survie de l’espèce en milieux urbanisés (Kisasa Kafutshi sous presse). Et enfin, la troisième hypothèse suggère que le choix de proies à capturer par les adultes dépendrait des exigences des poussins et leur disponibilité dans le site. Pour toute la durée d’élevage, la consommation d’une nichée a été estimée à environ 17 proies. Il s’agissait des insectes, des grenouilles et de poissons de tailles variant de 2-6,5cm. Nous avons montré que le Martin-pêcheur huppé module le choix de son habitat de reproduction non seulement en fonction de la texture du sol des falaises (Kisasa Kafutshi & Aloni Kumanda 2011), de la disponibilité des proies (Kisasa Kafutshi 2012a), mais surtout de la chance de survie de ses nids d’une année à l’autre (Kisasa Kafutshi 2012b). [less ▲]

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See detailLes iguanodons de Bernissart: leur évolution diagénétique et les processus de dégradation
Leduc, Thierry ULg

Doctoral thesis (2012)

About thirty complete articulated skeletons of iguanodons have been excavated from Bernissart. This unique collection is conserved at the RBINS. The bones excavated were the object of diverse physical and ... [more ▼]

About thirty complete articulated skeletons of iguanodons have been excavated from Bernissart. This unique collection is conserved at the RBINS. The bones excavated were the object of diverse physical and chemical treatments to protect them from their degradation. These bones were not the object of detailed mineralogical analyses allowing to understand either diagenetic mechanisms involved or to understand the specific mechanisms of their change. This work thus aims at filling this lack. It integrates petrographic (POM, SEM), mineralogical (DRX, Raman Spectroscopy) and chemical (EDS, X-ray fluorescence, microprobe) techniques. By these methods, 30 different minerals were identified. The diagenesis of Iguanodon bones is the result of cumulative physical, chemical and biological processes that will modify the original chemical and/or structural properties of this organic object. Bone diagenesis is a complex process that includes the degradation of organic matter, the dissolution and recrystallization of bone apatite, the enrichment in trace elements, the precipitation of new minerals in the bone cavities (permineralisation), the fracturation process. A plan is proposed positioning in a relative timescale minerals formed during 3 diagenetic stages and the degradation processes engaged following the bones exhumation. During burial variable recrystallisation took place: the slightly crystallized carbonated hydroxylapatite (the mineral phase of fresh bone tissue) was replaced by well crystallized carbonated fluorapatite currently present in the Iguanodon bones. Whereas some minerals infiltrated in the bone during cavity filling by the sediment (“mainly” quartz, “argillaceous” phyllosilicates), others are authigenic and precipitated in the cavities during burial (pyrite, barite, sphalerite, celestine, iron oxi-hydroxides, authigenic apatite, calcium sulfate and to a lesser extent vivianite). Pyrite is the most abundant authigenic mineral in the Iguanodon fossil bones. It occurs in different morphologies (crystals, framboids, sticks, fibroradial structure, thin coating…). Four kind of pyrite were determined according to the diagenesis phase during which they were formed and the source of iron and sulfur. Besides pyrite barite is the second most abundant phase. When both minerals are present pyrite has been formed first. The distribution of these minerals within bones is more controlled by micro-environments than by particular structure of the bone. Since their discovery the Iguanodon fossil bones were treated for conservation in several ways. This however did not prevent the alteration of pyrite into an assemblage of 16 different secondary minerals. The ferrous sulfates (szomolnokite and rozenite) are the most abundant of these minerals and can be found in nearly all samples sulfatized. Other sulfates were formed as the result of alteration of the wealdian shale by acid produced by pyrite oxidation: e.g. tschermigite, natrojarosite and halotrichite. Gypsum, anhydrite, iron phosphate and diadochite are the result of dissolution of bone apatite. The variations of relative humidity in collections and in showrooms are responsible for the pursuit of the bones degradation (sulfatation of the residual sulfides ; fracturing by dilation / contraction). The relative humidity, conjugated to the temperature variations are the parameters to be controlled for a better preservation of these invaluable fossils. Techniques implementing some chemicals products proposed in the literature are applicable only to certain objects of limited size. [less ▲]

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See detailAux origines de la métaphysique : l'interprétation par Alexandre d'Aphrodise de la "Métaphysique" d'Aristote
Guyomarc'h, Gweltaz ULg

Doctoral thesis (2012)

Le terme de « métaphysique » ne se lit pas chez Aristote. Les livres rassemblés sous ce titre ne cessent d'interroger leurs lecteurs quant à leur unité. La science ainsi désignée, enfin, semble ... [more ▼]

Le terme de « métaphysique » ne se lit pas chez Aristote. Les livres rassemblés sous ce titre ne cessent d'interroger leurs lecteurs quant à leur unité. La science ainsi désignée, enfin, semble contrevenir aux règles communes de la scientificité aristotélicienne. Désigner Aristote comme le « fondateur de la métaphysique » fait dès lors problème. L'hypothèse du présent travail est que cette fondation engage l'œuvre des commentateurs d'Aristote, au premier chef desquels se situe Alexandre d'Aphrodise. L'Exégète par excellence ouvre la possibilité de « faire de la métaphysique » sans que cela signifie seulement commenter Aristote. Alexandre travaille en effet à faire de la Métaphysique un livre et à instituer la métaphysique une science une. Selon l'Aphrodisien, la métaphysique est cette science à la fois universelle et première, à la fois science modèle et fondatrice des autres sciences. Elle s'articule en trois programmes principaux : l'étude générale de l'étant en tant qu'étant, celle de la substance et celle enfin de la cause première. Ces trois programmes sont distincts, mais coordonnés et suffisamment proches pour ne pas pouvoir être étudiés par une autre science, ni éclatés entre diverses sciences. Ils progressent à chaque fois par un passage d'une généralité à son maximum et sa cause. Ainsi la substance est-elle cause de l'être des autres étants et étant au maximum. Ainsi la cause première est-elle intelligible au plus haut point et cause de l'intelligibilité du monde. L'Exégète offre une interprétation forte de l'unité de la Métaphysique et de celle de la science correspondante. C'est dans et par cette reprise que les écrits du Stagirite sont devenus proprement fondateurs. [less ▲]

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See detailDownmodulator role of SHIP-1 in NOD2 signaling
Condé, Claude ULg

Doctoral thesis (2012)

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See detailCatchment modelling and sensitivity analysis to spatial interpolation methods of daily rainfall
Ly, Sarann ULg

Doctoral thesis (2012)

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to ... [more ▼]

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to continuous surfaces. The objective of this dissertation is to confront the performances of the several spatial interpolation methods, in particular the geostatistics for daily rainfall data in the nested catchments to realize a sensitivity analysis on discharges modelled at the outlets to the daily rainfall input in the modelling. The previous studies in the literature emphasized a requirement of novel investigation on the essential means to recover the rainfall data and eventually, the quality of the hydrological modelling. This study leaned on 30-year daily rainfall data of 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km²). Two common deterministic methods are employed here. The Thiessen Polygon (THI) assigns the value from the nearest observation to a certain grid cell. The Inverse Distance Weighting (IDW) is an advanced nearest neighbour approach that allows including more observations than only the nearest points. The value at a certain grid cell is obtained from a linear combination of the surrounding locations. In the geostatistical algorithms, the spatial variation may be better described by a stochastic function. Four versions of kriging are used. The Ordinary Kriging (ORK) is the basic form of Kriging that the prediction is also a linear combination of the measured values. But the spatial correlation between the data, as described by the variogram, determines the weights, assuming that the mean is constant but unknown. The Universal Kriging (UNK) is based on the hypothesis that this mean is a polynomial function of spatial coordinates. So, this type of kriging is not stationary with regard to the mean. The Kriging with External Drift (KED) supposes that the mean of the interest variable depends on auxiliary variables; the theory of this kriging is in fact the same as the theory of UNK, which also contains a non-constant mean. The drift is defined externally through some auxiliary variables. The Ordinary Cokriging (OCK) suggests estimating the variable of interest by weighted linear combination of its observations and the observations of the auxiliary variables. This technique requires the study of the spatial dependence between variables besides the study of the simple spatial dependences. All types of kriging use a variogram model to characterise spatial correlation. A variogram describes in terms of variances how spatial variability changes as a function of distance. Seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) were fitted to daily sample semi-variogram on a daily basis. These seven variogram models were also adopted to avoid negative interpolated rainfall. The elevation, extracted from a digital elevation model, was incorporated into multivariate geostatistics. Seven validation raingages and cross validation were used to compare the interpolation performance of these algorithms applied to different densities of raingages. The areal rainfalls are calculated for the catchment area and used for analysis of extreme rainfall. The effects of the interpolation methods on the extreme rainfall are analysed. The interpolated rainfalls are also used as rainfall input of the physically-based and distributed EPIC-GRID model. The long series of model results are analysed by comparison with the observed discharges at the different outlets of the catchments. Then, the extreme discharges at the outlets are computed. All of these investigations always take into account of the raingage density and the raingage position for very sparse raingage cases. The main results show that among the methods based on the only rainfall data, the geostatistics and IDW are the best ones. The performances change according to the density of the raingages. For the extreme rainfall and long term modelling results, no big difference is found for a high density of raingage but large difference are found for the case of the scattered raingage. For the latter case, UNK and KED are very sensitive to the position of the raingages. IDW, ORK and OCK are found to be the best performance. However for the extreme flow, KED and OCK is the best whereas IDW is not better for the high density of the raingages. For the case of the scattered raingages, the difference in extreme discharge between the interpolation methods is very large and larger than shown in the extreme rainfall and the long term modelling results. IDW, ORK and OCK always perform better. UNK and KED still are sensitive to the positions of raingages. The index of position is used to describe the form of polygon defined by the four raingages. This index is defined as the relation between the polygon perimeter and a circle perimeter having an area equivalent to that of the polygon. The best raingage position for all interpolation methods used in this research should be arround the catchment area, its index should be close to one. [less ▲]

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See detailApprentissages automatiques supervisés pour le monitoring environnemental et énergétique d'une chaudière de régénération
Sainlez, Matthieu ULg

Doctoral thesis (2012)

The broad objective of this thesis is to apply and compare supervised learning techniques for prediction of nitrogen oxide pollutant emission from the recovery boiler of a Kraft pulp mill. In this task ... [more ▼]

The broad objective of this thesis is to apply and compare supervised learning techniques for prediction of nitrogen oxide pollutant emission from the recovery boiler of a Kraft pulp mill. In this task, we want to highlight a technique that is most suited and self-adapted to boiler transient operating conditions. The Kraft process is an alkaline process to produce chemical pulp; cellulose fibers are dissociated from lignin by cooking the chips in a solution of sodium hydroxide (NaOH) and sodium sulfide (Na2S), called white liquor. The residual black liquor is concentrated and burned in a recovery furnace to yield an inorganic smelt of sodium carbonate (Na2CO3) and Na2S. The recovery boiler both regenerates the cooking chemicals and produces high pressure steam to the pulp mill, but the boiler is a major source of atmospheric pollutants in the mill. In particular nitrogen oxide formation is very complex because of several chemicals and dynamic mechanisms: thermal NOx, prompt NOx and fuel NOx. Nowadays, there is an increasing demand in such industries for efficient data analysis tools, especially for pollutant monitoring and/or energy management. Literature reviews refer mainly on numerical solutions where a complete description of the process is needed and where stationary condition is often a working hypothesis. This is the case with the advanced data validation and reconciliation techniques that we evaluate. This technique is based on thermodynamic models, chemical and physical relationships within process parameters and equipment. This is helpful to highlight some lack of information about the process, but this approach failed to model accurately steam and fumes utilities operating points. Indeed, in a Kraft recovery boiler, the total nitrogen oxide emission is dependent on several operating factors and heterogeneous conditions, e.g. operating fuels (black liquor or heavy fuel), furnace load, droplet size, air system operation, retention time, biomass characteristics,... For such a complex problem, machine learning techniques may be used as alternative methods in engineering analysis and predictions. They involve algorithms that improve automatically through experience collected in historical databases. Among supervised learning techniques, we focus mainly on neural networks methods (static and dynamic architectures) and additionally on tree-based (regression tree and random forests) and linear ones. For each method, we evaluate its ability to predict NOx pollutant emission in varying conditions. A random forest is a collection of uncorrelated regression trees, induced from bootstrap samples of the training data. Its internal estimates are also used to measure variable importance and allow us to classify relevant variables for a model inputs selection task. Note that we need some additional a priori knowledge to select the final inputs set. Among static neural network structures, the multilayer perceptron is the most widely used, particularly the two-layer structure in which the input units and the output layer are interconnected with an intermediate hidden layer. The model of each neuron in the network includes a nonlinear activation function that is differentiable; this network can perform static mapping between an input space and an output space. Within dynamic architectures, we distinguish those that have only feed-forward connections and those that have feedback (recurrent) connections. In this work, we focus mainly on NARX network (Nonlinear AutoRegressive model with eXogenous inputs) and additionally on Elman recurrent neural network. This last one incorporates an additional layer, called context layer, the nodes of which are the one-step delay elements embedded into the local feedback paths. Nevertheless, Elman's approach has some drawbacks associated with learning parameters scheme and temporal gradient approximation. Particularly, the NARX network is used for input-output modeling of nonlinear dynamical systems. It is a recurrent model: model inputs are applied to a tapped-delay-line memory of n units and outputs are fed back to the input layer through another line of m units. The total model order s=n+m is therefore a key parameter and the method of Lipschitz numbers is a tool for estimating it. An advantage of NARX is that we can use standard backpropagation algorithm for neural network learning scheme. Furthermore, to increase model robustness, we average neural predictions over a set of individual neural predictors, this is helpful for reducing variance prediction across trials. Despite the fact that generalization is done on the worst case configuration possible, we see that ensemble of NARX networks perform well on predicting NOx emissions during transient operations and Lipschitz numbers are very helpful for system orders estimations. We illustrate the potential of a dynamic neural approach compared to the others in the nitrogen oxide prediction task. It is more suited to practical modeling needs and offers a modeling of time and memory. It allows us to monitor NOx pollution and possibly adjusting control variables and performing diagnostics. The thesis is divided into seven chapters covering several publications. Chapter 1 is about the Kraft process and its recovery boiler. We start with a short description of the Kraft pulp mill. Then we describe the Kraft recovery boiler, some chemical reactions in the furnace, the steam production equipments and the atmospheric pollutants. Finally we discuss about nitrogen oxide formation in the furnace, the effects of several operating conditions on its production. Chapter 2 is about data mining, on what it is, on what it is used for and which are the main modeling cultures. This chapter deals with system identification, modeling approaches (white box, grey box, black box), some definitions about learning and modeling, and finally some links between modeling and optimization techniques. Chapter 3 starts with a state-of-the-art about numerical simulation of a Kraft recovery boiler, then we apply and evaluate a data validation scheme for steam and fumes utilities modeling. Finally we discuss the application of artificial intelligence techniques within the framework of a recovery boiler. Chapter 4 aims at selecting model inputs, starting with a supervised selection approach based on random forests. We introduce some methodological insights about tree-based methods, from a simple regression tree to random forests. Random forests internal estimates are used to measure the relative importance of each input variable in predicting a response, i.e. nitrogen oxide emission or high pressure steam production. Finally we discuss about some useful extra knowledge to take in account for the selection of final inputs. Chapter 5 is about neural networks modeling, we introduce the perceptron, the multilayer perceptron, and the associated backpropagation algorithm. We discuss about static and dynamic architectures, especially the Elman recurrent neural network. Finally, we apply a multilayer perceptron and an Elman recurrent neural network for predicting the high pressure steam flow rate from the Kraft recovery boiler. Chapter 6 presents some insights about input-output modeling of nonlinear dynamical systems, especially with NARX network. At the end, we explain the Lipschitz method that is applied for system orders estimation. Chapter 7 summarizes some comparison results about supervised learning techniques applied to predict nitrogen oxide pollutant emission from the recovery boiler. This comparison involves neural network techniques, tree-based methods and multiple linear regression. Finally, some research perspectives are presented and some conclusions are drawn. [less ▲]

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See detailLorsque les limites des sciences et les sentiers de chasse s’entrecroisent: Une ethnographie des laboratoires scientifiques amazoniens en partenariat avec les communautés autochtones locales
Escobar Jimenez, Kelly ULg

Doctoral thesis (2012)

Currently, protected areas and protected natural species are in a state of proliferation all over the world. Landscapes, flagship species, peoples in voluntary isolation, ecosystems, and “biological ... [more ▼]

Currently, protected areas and protected natural species are in a state of proliferation all over the world. Landscapes, flagship species, peoples in voluntary isolation, ecosystems, and “biological corridors” are all protected. In order to achieve this, categories of protection at different geographical levels have been mobilized. The processes that allow any one of these categories to become operational within a precise territory are more or less well standardized and have in common, amongst others things, two components that have caught my attention: Firstly, the central role of previous scientific and technical studies, and secondly, the desire to ensure the participation of the populations concerned. How are relations between scientists and the non-scientific public in participatory environmental management? This thesis seeks to answer this question, from the starting point of an analysis of the cognitive dimension of participatory environmental management, i.e. how the production of knowledge affects the modes of existence within protected areas (and consequently their human and nonhuman inhabitants). Building upon the study of daily activities that bring scientists and indigenous peoples into contact in and around the scientific field stations “Yasuní” and “Juri Juri Kawsay” (in the Ecuadorian Amazon), this research describes the relationship between ways of knowing a conflicting object (for example a natural species, a territorial boundary, an isolated people) and the consequences in terms of configuration of that object (in terms of identity, value, and fragility) and its management (administration, use, protection, recovery or abandonment). By mobilizing the approach of Actor-Network theory, this dissertation attempts to outline how mediation between humans and nonhumans, non-scientific and scientific, occurs. It also offers a reflection on how the Agency of an entity (the competence to make make distributed in the humans and nonhumans actors) comes to influence the joint actions. This research can capture the ambiguity, instability, resistance and complexity that still exist in the Amazon, with some unexpected findings along the way, by showing the changes among things and people throughout development projects, land management initiatives, and conservation and science programs. After describing the trajectory of four entities (laboratories, species conservation, territories and subjects), which meet at the Amazonian interfaces where science, conservation and development are in competition, the findings of this dissertation have met two ambitions: to consider the importance of taking into account the complexity and historicity of scientific data and to answer a broader question: What are the relevant factors to take into account when considering the possibilities for joint action between scientists and indigenous populations? [less ▲]

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See detailEvénements de santé et transition à la retraite des seniors en Belgique. Une approche biographique
Banturiki, Yannick Védaste ULg

Doctoral thesis (2012)

La thèse de Mr. Banturiki porte sur une analyse socio-démographique réalisée dans une perspective biographique mettant en relation des événements vécus dans le parcours de vie et la transition à la ... [more ▼]

La thèse de Mr. Banturiki porte sur une analyse socio-démographique réalisée dans une perspective biographique mettant en relation des événements vécus dans le parcours de vie et la transition à la retraite des seniors en Belgique. L’une des approches novatrices de ce travail est la conceptualisation d’un événement de santé en vue de sa collecte dans les biographies individuelles. S’appuyant sur le paradigme des parcours de vie, ce travail se veut une contribution dans la compréhension de l’incidence que peuvent avoir des événements vécus tout au long de la vie sur le risque de connaître une sortie d’une activité salariée chez les seniors. [less ▲]

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See detailElectrografting on nanoparticles: A new way toward polymer stabilized nanoparticle suspensions
Serwas, Harry ULg

Doctoral thesis (2012)

Abstract: Nowadays, nanomaterials keep sparking interest tremendously because of the unique properties materials exhibit at the nanoscale. However, the stabilization of nanoparticles against aggregation ... [more ▼]

Abstract: Nowadays, nanomaterials keep sparking interest tremendously because of the unique properties materials exhibit at the nanoscale. However, the stabilization of nanoparticles against aggregation is a prerequisite to exploit their remarkable properties, since they are very prone to aggregation. Moreover, even if many synthetic methods have been reported to prepare nanoparticles, achieving an efficient and convenient stabilization, without an alteration of the properties nanoparticles remains a challenge up to now. Therefore, a novel approach toward polymer stabilized metal based nanoparticles was developed using sonoelectrochemistry combined to electrografting to form a protective polymer layer in-situ directly on the generated particles. Nanopaticles prepared using this new approach were characterized. The influence of major experimental parameters on the characteristics of the produced polymer coated particles was also studied. [less ▲]

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See detailEtude de trois souches entomopathogènes de champignons Hyphomycètes dans la lutte contre les moustiques (Diptères : Culicidae)
Bawin, Thomas ULg

Master's dissertation (2012)

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. The prospects for the use of three Hyphomycetes fungi (Aspergillus clavatus Desm., Metarhizium anisopliae (Metsch ... [more ▼]

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. The prospects for the use of three Hyphomycetes fungi (Aspergillus clavatus Desm., Metarhizium anisopliae (Metsch.) Sorokin, and Metarhizium sp.) towards an important vector species (Culex quinquefasciatus Say) are discussed. 1. Culture tests were performed in flasks to assess the spore productivity of the fungal strains on wheat bran (an agricultural by-product) and husked rice (a food product that is classically used) in solid, semi-solid and liquid-state media. Regardless of the substrate, solid-state media showed the highest productivity. The observations suggested that culture tests could be carried out in solid-state or sequential fermentation with wheat bran. 2. Classical toxicity tests using aqueous suspensions of spores were performed to assess their larvicidal potential against C. quinquefasciatus. The LD50 and LD90 were estimated after 72 hours of treatment with 1.35 x 10^8 and 5 x 10^8 spores/ml for Aspergillus clavatus, 1.3 x 10^8 and 4 x 10^8 spores/ml for Metarhizium anisopliae, 1.75 x 10^8 and 9.9 x 10^8 spores/ml for Metarhizium sp. Mycelial filaments appeared from dead larvae and produced spores in the case of each strain. Spores were also found in the gut of emerged adults from surviving larvae. In comparison, the LC50 and LC90 of a commercial formulation based on the bacterium Bacillus thuringiensis var. israelensis (Vectobac ®, serotype H14) were estimated after 48 hours to 0.043 mg/l and 0.115 mg/l. The results showed that the fungi tested cannot be effective control agents at the tested doses and the applied protocol. Different axes of research are suggested. 3. The potentialities of the injection of spore suspensions into mosquito larvae in order to assess their pathogenicity have been considered. The percentages of corrected mortality were obtained after 72 hours for Aspergillus clavatus (62%), Metarhizium anisopliae (53%) and Metarhizium sp. (57%). Additional experiments would be needed to make sure whether it is well a direct response linked to the toxic effect of these fungi. 4. Optical and electron microscopy observations were conducted to study the mode of action of A. clavatus on C. quinquefasciatus larvae. Histological sections revealed that the lethal effect observed in toxicity tests is due to the ingestion of spores. An analysis of toxins produced at the beginning of germination, their contribution to larval mortality and their impact on non-target organisms should be carried out. 5. Finally, the specificity of the pathogenicity of A. clavatus and M. anisopliae against mosquitoes has been evaluated by considering another biological model: the aphid Acyrthosiphon pisum Harris. No link between the range of tested doses and (1) mortality of adults, (2) the decline of their offspring was found. Additional experiments should be carried out. The application of these fungi to other insects of agricultural, veterinary or medical interest should also be tested. [less ▲]

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See detailDétection de signes de conscience chez des patients sévèrement cérébro- lésés avec le contrôle volontaire de la respiration.
Charland-Verville, Vanessa ULg

Master's dissertation (2012)

Suite à un accident cérébral grave, les patients peuvent évoluer d’un coma (patient non-éveillable et inconscient), vers un état végétatif/syndrome d’éveil non-répondant (patient éveillé mais inconscient ... [more ▼]

Suite à un accident cérébral grave, les patients peuvent évoluer d’un coma (patient non-éveillable et inconscient), vers un état végétatif/syndrome d’éveil non-répondant (patient éveillé mais inconscient), vers un état de conscience minimale (patient éveillé et conscient, mais non-communiquant), ou un locked-in syndrome (patient éveillé, conscient, mais ne pouvant exprimer sa conscience que par le biais de mouvements oculaires). L’attribution d’un diagnostic différentiel suite aux évaluations cliniques à l’aide d’échelles comportementales peut se révéler extrêmement complexe avec un taux d’erreurs diagnostiques pouvant toucher plus de 4 patients sur 10 (Childs, Mercer, & Childs, 1993; Schnakers, Vanhaudenhuyse, Giacino, Ventura, Boly et al., 2009c). Ce diagnostic aura un impact tant au niveau éthique que clinique, influant sur les décisions de fins de vie comme sur les soins et traitements prodigués au patient (Demertzi, Schnakers, Ledoux, Chatelle, Bruno et al., 2009; Johnson, 2011). Afin d’affiner le diagnostic des états de conscience altérée, un vaste champ de recherche s’est créé ayant pour but le développement d’outils objectifs complémentaires à l’examen comportemental clinique. Le but de ce travail s’inscrit donc dans le cadre de la mise au point de techniques permettant de détecter des signes de conscience chez ces patients incapables de communiquer et d’exprimer leur conscience par les voies classiques. En effet, nous avons proposé l’utilisation du sniff controller, une toute nouvelle technique permettant de répondre à la commande par la respiration. Notre paradigme, utilisé pour la première fois auprès de patients atteints de trouble de la conscience, avait pour but de demander aux patients de moduler volontairement leur respiration afin de dépasser un seuil prédéfini. Selon les résultats obtenus, il semble que le sniff controller, moyennant plus d’essais et certaines modifications à apporter au système et au paradigme, pourrait se révéler être un outil complémentaire dans l’évaluation para-clinique de ces patients. En effet, l’utilisation de ce système pourrait se révéler comme plus sensible à la détection de réponse à la commande que les évaluations comportementales. De plus, il s’agit d’une interface peu dispendieuse, relativement simple d’utilisation, transportable au chevet du patient et tout à fait non-invasive. Par ailleurs, en ne reposant pas directement sur l’activité cérébrale, cette technique n’est pas sensible aux artéfacts cérébraux inhérents aux lésions cérébrales rencontrées chez les patients. [less ▲]

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See detailCaractérisation des exoplanètes en transit WASP-34b, WASP-35b et WASP-44b à l'aide du télescope TRAPPIST
Delrez, Laetitia ULg

Master's dissertation (2012)

Les Jupiters chauds sont des exoplanètes très intéressantes à étudier du fait des conditions extrêmes auxquelles elles sont soumises (forte irradiation, champs gravitationnel et magnétique intenses ... [more ▼]

Les Jupiters chauds sont des exoplanètes très intéressantes à étudier du fait des conditions extrêmes auxquelles elles sont soumises (forte irradiation, champs gravitationnel et magnétique intenses). Lorsque ces planètes transitent devant leur étoile, elles nous offrent une opportunité unique de pouvoir étudier leur structure, leur composition chimique ainsi que les mécanismes physiques à l’œuvre dans de telles conditions extrêmes. Dans ce mémoire, nous avons procédé à la caractérisation des trois Jupiters chauds en transit WASP-44b, WASP-35b et WASP-34b sur base de courbes de lumière de haute précision de leurs transits obtenues à l’aide du télescope TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope). Pour chacun des systèmes, ces courbes de lumière ont été combinées à des mesures de vitesse radiale de l’étoile hôte dans une analyse MCMC (Monte Carlo Markov Chain) globale afin de contraindre efficacement les paramètres de la planète et de l’étoile. Les résultats que nous obtenons confirment globalement ceux des articles de découvertes des trois exoplanètes. Par ailleurs, nos résultats améliorent considérablement les contraintes sur les paramètres du système WASP-44. Nous mettons également en évidence le fait que les rayons des trois exoplanètes ne peuvent pas (ou assez difficilement dans le cas de WASP-44b) être expliqués par les modèles classiques d’évolution de planètes irradiées. Suite à cette constatation, nous explorons la possibilité d’un éventuel chauffage récent de l’intérieur des planètes par effets de marée comme explication possible de ces rayons trop importants. Nous montrons que les trois exoplanètes pourraient effectivement avoir subi dans le passé un important chauffage par effets de marée. Ce chauffage pourrait avoir contribué aux rayons observés actuellement pour WASP-44b et WASP-35b, parallèlement à d’autres mécanismes. Nous montrons qu’il semble en revanche fort peu probable que le rayon anormalement élevé de WASP-34b soit lié à un tel chauffage. Enfin, nous obtenons une probabilité de 89.3% que les transits de l’exoplanète WASP-34b soient rasants. Cette probabilité est plus élevée que celle donnée dans l’article de découverte mais reste cependant inférieure au seuil 3-σ à partir duquel on pourrait raisonnablement conclure à des transits rasants pour cette exoplanète. [less ▲]

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See detailLe sommeil chez les patients en état de conscience altéré
Cologan, Victor ULg

Doctoral thesis (2012)

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de ... [more ▼]

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de conscience minimale. Les conclusions supportent l'intérêt neurophysiologique mais aussi diagnostique et pronostique de l'examen du sommeil chez ces patients. [less ▲]

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See detailApproche écologique du neuston en baie de Calvi
Collard, France ULg

Master's dissertation (2012)

Le neuston, à l’inverse du plancton sous-jacent, est un milieu peu connu. Son importance écologique est pourtant réelle : il constitue d’une part une zone d’accumulation de bactéries, de molécules ... [more ▼]

Le neuston, à l’inverse du plancton sous-jacent, est un milieu peu connu. Son importance écologique est pourtant réelle : il constitue d’une part une zone d’accumulation de bactéries, de molécules organiques (lipides, protéines mais aussi plastiques et polluants organiques), de débris terrestres et d’autre part, il est le lieu d’échange des gaz air-océan. Il subit les conditions météorologiques de plein fouet (précipitations, vent, lumière) tout comme les organismes qui y vivent. La diversité neustonique est importante : une trentaine d’espèces de copépodes ont été déterminées et tous les groupes marins planctoniques en baie de Calvi se retrouvent dans le neuston. Parmi les organismes retrouvés en surface, certains sont spécifiques du neuston. C’est le cas des copépodes de la famille des Pontellidae qui sont dominés par des juvéniles. L’abondance neustonique de la plupart des groupes rencontrés varie de manière saisonnière et journalière. L’hiver est très différent de l’été en termes de diversité tandis que le biovolume ne présente pas de variabilité saisonnière marquante. Les Pontellidae, les copépodes du genre Temora, les cladocères, l’ichtyoplancton sont des groupes estivaux tandis que les copépodes du genre Candacia et les isopodes sont hivernaux. La variation à court terme s’explique généralement par la variation de la direction du vent. Lorsqu’il amène des eaux du large, les copépodes (dont les Pontellidae) sont plus abondants, ainsi que les œufs de poisson entre autres. La turbulence, les précipitations et la concentration en chlorophylle a semblent avoir moins d’importance. Une comparaison entre le neuston et le plancton révèle que les Pontellidae sont 200 fois plus abondants dans le neuston. Les copépodes en général, les siphonophores, l’ichtyoplancton semblent y être plus nombreux. A contrario, certains groupes sont plus abondants dans le plancton sous-jacent que dans le neuston (cladocères, mollusques, …). Parmi les débris associés au neuston, on trouve des (micro)plastiques. On comptabilise en moyenne 7,2 fragments sur 100 m² avec un maximum de 78,8 fragments par 100 m². Généralement ils ont la taille du microplancton ou du mésoplancton et sont de couleurs différentes. Leur concentration est influencée par la direction du vent et non par la turbulence. Un vent de nord-nord-est ou d’est-nord-est apporte des plastiques dans la baie. Le neuston est un milieu complexe car beaucoup de paramètres influencent sa dynamique et son écologie. Il est différent du plancton à certains égards, c’est un écosystème à part entière. En baie de Calvi, le vent a une grande importance sur l’abondance des espèces neustoniques ainsi que sur la concentration en débris. [less ▲]

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See detailUse of intercropping and infochemical releasers to control aphids in wheat
Zhou, Haibo ULg

Doctoral thesis (2012)

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See detailAltération hydrothermale du béryl et formation de ses minéraux secondaires dans la pegmatite de Prà della Munega (Sondrio, Italie)
de Marchin, Stéphanie ULg

Master's dissertation (2012)

Beryl crystals have been found in the pegmatite of Prà della Munega rich in feldspars, quartz, muscovite and garnet. This pegmatite outcrops near Chiavenna, in Sondrio Province, Lombardy, Italy. These ... [more ▼]

Beryl crystals have been found in the pegmatite of Prà della Munega rich in feldspars, quartz, muscovite and garnet. This pegmatite outcrops near Chiavenna, in Sondrio Province, Lombardy, Italy. These beryls show different degrees of alteration according to their localization in the pegmatite. Electron microprobe analyzes and X-ray diffraction mesurments (powder and four circles diffractometer) allowed to identify several silicates produced by the alteration of beryl: bavenite, bertrandite, chiavennite, milarite. Chemical analyzes of these minerals show substitution mechanisms which affect beryl and bavenite. Crystal structures of bavenite, chiavennite and milarite were also resolved. These structures are in accordance to structures described in literature, except milarite which Na’s site occupies a slightly shifted position compared with mirror plan. Petrographic observations and the Rietveld methodology allowed to define asequence of alteration. During the alteration, the shape of original beryl is conserved. Bavenite crystallizes in the shape of original beryl, bertrandite and chiavennite crystallize in the shape of original beryl and out of this, and milarite crystallizes out of the shape of original beryl due to a mobilization of Be by pegmatitic fluids. Bavenite and bertrandite are the first minerals to crystallize with an input of Ca, Mn, K, Si, Li, Be and Rb which results of the metasomatism of Na (albitization). These fluids, with a temperature of 350°C, destabilize the beryl and allow the crystallization of these alteration-induced minerals. Chiavennite and milarite are the last minerals who crystallize in the system with an input of K and Mn. These fluids, reaching low temperature and rich in K and Mn, could originate from late metamorphic fluids or residual fluids in pegmatites. [less ▲]

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See detailCalcul de l’aléa sismique pour une région dans le Tien-Shan Central, étude in situ et modélisation numérique dynamique de la réponse sismique de sites de bassin de retenue.
Lamair, Laura ULg

Master's dissertation (2012)

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is ... [more ▼]

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is essential, not only at regional scale but also at local scale. First, this work presents a detailed analysis of seismic hazard in the Central Tien Shan. Several seismic hazard map have been made but none of them include paleoseismic data. Our maps are based on previous studies of probabilistic seismic hazard of the Kyrgyz Tien Shan (Abdrakhmatov et al., 2003). We integrate in our calculation the palaeoseismicity of the Talas Fergana Fault. It allows us to take into consideration strong earthquakes with high return periods. The final results are presented as maps with different return periods (100, 200, 475, 1000, 2000, 5000 and 10000 years). The outcomes are discussed in comparison with previous results, with GSHAP predictions (Ulomov et al., 1999) and with probabilistic seismic hazard map (Abdrakhmatov et al., 2003). The purpose of the second part of this study is the assessment of local seismic hazard of Tuyuk-Suu and Taldy-Bulak "D" tailings, both located in the Minkush valley. First, seismic wave amplifications are determined by means of spectral ratios of the horizontalto- vertical (H/V) components acquired through ambient noise measurements. Secondly, a dynamic modeling of the two tailings is performed. It is based on peak ground acceleration calculated previously for a return period of 1000 years. The dynamic modeling gives Fourier spectra for several histories. Spectral ratios obtained from dynamic modeling are compared with H/V measurement in order to estimate site effects. [less ▲]

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See detailL'expérience de travail dans une organisation autogérée : Le cas de l'asbl Barricade
Croquet, Alice ULg

Master's dissertation (2012)

La recherche part du constat désormais largement démontré qu’un travail, bien plus qu’un moyen de se procurer un revenu, fait sens pour les individus (Ferreras, 2007). À cet égard, le mode de ... [more ▼]

La recherche part du constat désormais largement démontré qu’un travail, bien plus qu’un moyen de se procurer un revenu, fait sens pour les individus (Ferreras, 2007). À cet égard, le mode de fonctionnement autogestionnaire que les salariés de l’asbl Barricade expérimentent chaque jour au regard d’un ambitieux idéal démocratique semble particulièrement privilégié : leur implication dans la gestion de l’organisation entend combattre l’aliénation et cultiver l’émancipation de tout un chacun. Dans l’optique de réfléchir sur ce qui fait réellement sens pour les travailleurs, cette recherche interroge le mode de fonctionnement autogestionnaire adopté par l’association pour en saisir les impacts sur l’expérience des travailleurs. [less ▲]

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See detailEtude longitudinale des besoins psychosociaux des conjoints de personnes atteintes d'un cancer - Evaluation de l'efficacité de méthodes d'action : hiérarchisation des besoins psychosociaux et résolution de problème
Wagener, Aurélie ULg

Master's dissertation (2012)

Introduction. Le cancer, une maladie chronique, a indéniablement un impact sur les patients qui en sont atteints mais aussi sur les membres de leur famille. Les conjoints, plus particulièrement ... [more ▼]

Introduction. Le cancer, une maladie chronique, a indéniablement un impact sur les patients qui en sont atteints mais aussi sur les membres de leur famille. Les conjoints, plus particulièrement, adopteront généralement le rôle de proche aidant principal et ressentiront de nombreux besoins psychosociaux et de la détresse émotionnelle. Méthodologie. Notre recherche-action compare l’efficacité de la combinaison de méthodes d’action « Hiérarchisation + Résolution de problème » à l’utilisation de la « Hiérarchisation » seule. Pour ce faire, 37 conjoints, répartis aléatoirement dans deux groupes (expérimental vs contrôle), ont répondu à divers questionnaires évaluant à trois reprises (T0, T1 et T2) les variables dépendantes suivantes : les besoins psychosociaux, la détresse émotionnelle, les réactions quant à la position de proche aidant principal et le sentiment d’auto-efficacité. D’autres variables dépendantes n’étaient évaluées qu’au T0 : les données sociodémographiques, l’ajustement conjugal, les services d’aide et la perception d’iniquité. Lors du T0, tous les participants réalisent la hiérarchisation. Entre le T0 et le T1, le groupe expérimental pratique la résolution de problème alors que le groupe contrôle n’y aura accès qu’entre le T1 et le T2. Hypothèses. Nous pensons que la combinaison des méthodes d’action aura un impact plus important et plus bénéfique que l’utilisation de la « Hiérarchisation » seule. Résultats. Entre le T0 et le T1, l’amélioration des scores sur les variables dépendantes est plus marquée au sein du groupe expérimental. Entre le T1 et le T2, les scores du groupe contrôle s’améliorent aussi : l’amplitude de changement est d’ailleurs plus élevée. Par contre, les scores que le groupe expérimental avait obtenus lors du T1 ne se maintiennent pas en T2. Par ailleurs, l’ensemble des données qualitatives récoltées mettent en évidence de hauts niveaux de satisfaction des participants quant aux méthodes utilisées. Conclusion. Les résultats obtenus mettent en évidence une plus grande efficacité de la combinaison des méthodes d’action proposées. Ainsi, il s’agit, premièrement, de réfléchir à la façon d’améliorer le protocole utilisé et, deuxièmement, à la façon de l’implanter au sein des services d’oncologie. [less ▲]

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See detailPortfolio professionnel
Hanzen, Christian ULg

Master of advanced studies dissertation (2012)

Ce portfolio a été rédigé dans le cadre du master complémentaire en pédagogie de l'enseignement supérieur (FORMASUP). Ce master visait l'acquisition de trois compétences : concevoir, enseigner et réguler ... [more ▼]

Ce portfolio a été rédigé dans le cadre du master complémentaire en pédagogie de l'enseignement supérieur (FORMASUP). Ce master visait l'acquisition de trois compétences : concevoir, enseigner et réguler. Le portfolio présente les divers aspects et preuves de l'acquisition de ces compétences. [less ▲]

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See detailPortfolio professionnel Formasup
Jérôme, Françoise ULg

Master of advanced studies dissertation (2012)

Analyse de pratiques : Régulation des stratégies d’évaluation mises en œuvre dans le cadre d’un cours de traduction littéraire par le biais de la récolte et de l’analyse de données objectives et ... [more ▼]

Analyse de pratiques : Régulation des stratégies d’évaluation mises en œuvre dans le cadre d’un cours de traduction littéraire par le biais de la récolte et de l’analyse de données objectives et subjectives. [less ▲]

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See detailSymmetries of the scalar sector of multi-Higgs-doublet models
Keus, Venus ULg

Doctoral thesis (2012)

In pursuit of the origin of the masses of particles in the Standard Model, the Brout- Englert-Higgs Mechanism predicts the existence of a scalar boson, whose discovery has been the main goal of the Large ... [more ▼]

In pursuit of the origin of the masses of particles in the Standard Model, the Brout- Englert-Higgs Mechanism predicts the existence of a scalar boson, whose discovery has been the main goal of the Large Hadron Collider. However, introducing this scalar boson does not provide the answer to all inadequacies of the Standard Model. Many different Beyond Standard Model theories have been proposed in order to explain these anomalies. Multi-Higgs-doublet models are among these models. We restrict ourselves to the scalar sector of multi-Higgs-doublet-models. The huge number of free parameters in the scalar potential in these models, makes it impossible to study the most general case for any N. In order to reduce the number of free parameters, one could impose symmetries on the scalar potential. Therefore, it is important to explore which symmetries can be implemented in the scalar sector, how these symmetries are broken, how they could be encoded in the Yukawa sector and what the resulting properties of the fermions are. Classifying these symmetries in the scalar sector is the main focus of this thesis. We have found certain symmetries that are always broken in models with more than two doublets, which we name ”frustrated symmetries”. Examples of such symmetries are presented in 3HDM, and one particular symmetry, the octahedral symmetry, is studied further. This symmetry seems to be the largest realizable discrete symmetry that can be imposed on the scalar sector in 3HDM, and interestingly results in a 2HDM-like mass spectrum. In the attempt towards the classification of possible symmetries in the scalar sector of the NHDM, we find that these symmetry groups are either subgroups of the maximal torus, or certain finite Abelian groups which are not subgroups of maximal tori. For the subgroups of the maximal torus, we present an algorithmic strategy that gives the full list of possible realizable Abelian symmetries for any given N . We extend this strategy to include Abelian antiunitary symmetries (with generalized CP transformations) in NHDM. We also show that multi-Higgs-doublet models can naturally accommodate scalar dark matter candidates protected by the group Zp , since these groups are realizable in NHDM. These models do not require any significant fine-tuning and can lead to a variety of forms of microscopic dynamics among the dark matter candidates. [less ▲]

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See detailLes Mesures de l’Efficacité d’un Système TVA
Bougnouch, Mehdi ULg

Master's dissertation (2012)

Detailed reference viewed: 19 (6 ULg)
See detailApprocher la médiation par ses usages professionnels. Le cas de l'art-thérapie
Vandeninden, Elise ULg

Doctoral thesis (2012)

La médiation est une notion aujourd’hui centrale dans de nombreuses recherches en SIC : elle est mobilisée en tant que concept permettant de décrire la spécificité de dispositifs communicationnels ... [more ▼]

La médiation est une notion aujourd’hui centrale dans de nombreuses recherches en SIC : elle est mobilisée en tant que concept permettant de décrire la spécificité de dispositifs communicationnels tripartites mais aussi comme problématique susceptible d’interroger autrement certains objets. Les domaines d’étude privilégiés par les chercheurs relèvent traditionnellement des champs de la culture ou des médias et techniques. Dans le premier, la notion de médiation désigne le réseau d’intermédiaires reliant l’œuvre au public ; le travail des analystes consiste alors à faire apparaître « les médiations » auparavant invisibles. Dans le second, le terme renvoie à un « objet intermédiaire » qui s’insère dans les relations humaines et substitue le rapport objectal au rapport intersubjectif. Dans ces deux domaines, il est question d’un contact différé, espacé. Les usages professionnels de la médiation - ceux qui renvoient, par exemple, aux divers métiers de « médiateurs » - sont, en revanche, très peu interrogés par les chercheurs en SIC. Ils se caractérisent par un recours au terme de médiation comme stratégie de communication. Son processus renvoie à l’insertion d’un « tiers humain » dans des relations intersubjectives souvent décrites comme conflictuelles. Ce qui distingue ces derniers usages de ceux traditionnellement investigués en SIC, c’est donc ce tiers « incarné » et la confrontation directe des sujets. Cette recherche s’attache à comprendre d’une part les raisons de ce désintérêt des chercheurs en SIC pour des pratiques professionnelles pourtant reconnues socialement, d’autre part la spécificité de l’activité du « tiers humain ». Afin d’explorer le fonctionnement de cette dernière, nous avons opté non pour l’étude d’un médiateur « nommé » tels que ceux qui exercent dans les domaines juridique, familial, entrepreneurial ou encore scolaire mais pour le « cas » des psychothérapies médiatisées dont « l’art-thérapie » fait partie. Si cet objet d’étude nous a semblé intéressant, c’est que son articulation avec la notion de médiation « fait problème ». C’est à un texte de Jean-Claude Passeron et de Jacques Revel (2005) qu’il faut se référer pour décrire la particularité de notre travail : « Penser par cas. Raisonner à partir de singularités ». Ils y décrivent cette démarche qui consiste à s’appuyer sur la richesse d’un objet pour mettre des outils théoriques à l’épreuve, non pas pour illustrer la théorie (cela reviendrait alors à mobiliser le « cas » comme « exemple ») mais pour l’interroger : « c’est, à dire vrai, l’ensemble des questions dont on l’investit – et dont il est susceptible d’être investi – qui fait le cas » (p. 11). Ainsi, nous envisageons la façon dont le « cas » de l’art- thérapie interroge la définition de la médiation : comment les visions des professionnels mettent en cause les conceptions des chercheurs en SIC mais aussi de quelle façon les différents modes d’appréhension possibles (approche à partir des discours ou des situations) appellent l’instauration d’un cadre de perception nouveau, apte à mettre en relation les éléments disjoints révélés par l'étude du cas. [less ▲]

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See detailPortfolio FORMASUP
Colaux, Catherine ULg

Thèse d’agrégation de l’enseignement supérieur (2012)

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See detailComment définissons-nous nos souvenirs lors d'un témoignage oculaire ?
Schroyen, Sarah ULg

Master's dissertation (2012)

Lorsque nous sommes amenés à définir notre souvenir, on distingue classiquement deux processus : - Un processus de recollection, faisant référence au rappel conscient de détails épisodiques - Un processus ... [more ▼]

Lorsque nous sommes amenés à définir notre souvenir, on distingue classiquement deux processus : - Un processus de recollection, faisant référence au rappel conscient de détails épisodiques - Un processus de familiarité, désignant un sentiment de déjà-vu Lors de ce mémoire, nous nous basons sur une vision graduelle tant pour le processus de recollection que de familiarité, un processus n’excluant par l’autre. Nous utilisons un paradigme de témoignage oculaire : les sujets visionnent l’extrait d’un film et doivent ensuite répondre à une série de détails. Pour chaque proposition, un jugement « souvenir » (correspondant au processus de recollection) et un jugement « familiarité » leur sera demandé sur une échelle de 1 à 4. Une série de questions sur chaque item (à propos de détails visuels, sonores…) leur est ensuite posée. Dans un premier temps, nous essayons de reproduire les résultats obtenus par Bodner et Richardson-Champion (2007) sur l’influence du contexte sur le jugement : notre hypothèse étant un plus haut taux de réponses souvenirs pour les items de difficulté moyenne lorsqu’ils sont mélangés à des items difficiles plutôt que des items faciles. Ensuite, nous comparons deux groupes d’âge : des sujets entre 20 et 26 ans et des sujets entre 60 et 69 ans. Nous nous attendons à observer une diminution du taux de jugement souvenir accordé aux items correctement reconnu et une augmentation des fausses alarmes avec un jugement souvenir avec l’avancée en âge. L’effet du contexte sur le jugement phénoménologique accordé aux items n’a pas été vérifié chez les sujets âgés. Par contre, le nombre de détails associés à chaque item montre un effet du contexte dans les deux groupes d’âge. À propos de l’effet de l’âge, comme attendu nous montrons une augmentation des fausses alarmes jugées comme souvenir chez les sujets âgés comparativement aux sujets jeunes. Par contre, le jugement souvenir accordé aux items correctement reconnus est plus élevé avec l’âge. Des pistes pour expliquer ces différents résultats sont ensuite proposées. [less ▲]

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See detailL'étude de l'impact de l'activité professionnelle et de l'âge de départ à la retraite sur le développement de la maladie d'Alzheimer.
Grotz, Catherine ULg

Master's dissertation (2012)

Contexte : Le vieillissement s'accompagnerait de modifications cérébrales entrainant des répercussions sur certaines fonctions cognitives. Cependant, il existerait une grande hétérogénéité ... [more ▼]

Contexte : Le vieillissement s'accompagnerait de modifications cérébrales entrainant des répercussions sur certaines fonctions cognitives. Cependant, il existerait une grande hétérogénéité interindividuelle pouvant s’expliquer par des différences de réserve cognitive, concept très récent et complexe, qui suggère que toutes les activités entreprises durant la vie feraient que l’individu se construise une réserve, lui permettant de différer les effets du vieillissement sur le cerveau. Objectif : Le but de cette étude est, en partant de l’âge de la retraite comme facteur de réserve, de déterminer si la retraite exerce une influence sur le développement de la maladie d’Alzheimer ainsi que sur son décours temporel. Méthode : Les données ont été recueillies sur 32 patients (Alzheimer probable/Mild Cognitive Impairment) de plus de 50 ans. La cognition des sujets a été évaluée via une courte batterie de tests cognitifs (mémoire épisodique et fonctions exécutives). D’autres données relatives à la maladie ont été récoltées via le dossier médical. Un entretien semi structuré (e.g., questions relatives au parcours professionnel, à la retraite) et des questionnaires ont été administrés aux sujets. Résultats : Aucune relation n’a été mise en évidence entre l’âge de début de la maladie, certaines mesures cognitives et l’âge de la retraite. Par contre, l’âge de cessation de l’activité professionnelle serait négativement lié au MMSE, lors du 1er bilan, et à la tâche du Stroop. La relation Retraite/Cognition serait, cependant, influencée par le type de profession, et dans une moindre mesure, par le nombre d’activités de loisirs. Enfin, la vitesse d’évolution de la maladie ne serait pas liée à l’âge de la retraite. Conclusion : Ces résultats ne confirment que partiellement nos hypothèses et ne permettent pas d’apporter beaucoup d’arguments en faveur du concept de réserve cognitive. Néanmoins, cette étude souligne qu’à un stade d’évolution léger, l’effet protecteur de la réserve peut continuer à se manifester. [less ▲]

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See detailEvolution des herbiers à Posidonia oceanica (L.) Delile dans la baie de Calvi (Corse, France) et influence de l’ancrage dans la baie de l’Alga
Abadie, Arnaud ULg

Master's dissertation (2012)

In the framework of the STARE-CAPMED program we studied the impact of human activities on Posidonia oceanica meadows in Calvi Bay (Corsica, France). We mostly focused on the consequences of boats ... [more ▼]

In the framework of the STARE-CAPMED program we studied the impact of human activities on Posidonia oceanica meadows in Calvi Bay (Corsica, France). We mostly focused on the consequences of boats anchoring in Alga Bay. The map of the marine habitats realized during this study shows that P. oceanica meadows cover a surface of 4.94 km2 in 2010 and have declined of 26 % since 1997. Advances in the data acquisition techniques allow a better identification of the habitats and a map reliability improvement. In several places in the bay, especially near the waste waters rejection site, the lower limit of the meadow is shallower than in the past. The diminution of the meadow surface in the 21-30 m bathymetric section is more important in the Alga site than in the rest of Calvi Bay. The ecological state of the water surrounding the meadow in Alga was assessed as "good" with a PREI index of 0.685. However, big units anchoring in this area lead to the creation of dead “mattes” whose compactness are medium. In this area, the generation of dead mattes seems to favor the settlement of the invasive Chlorobionta Caulerpa racemosa var. cylindracea, of which anchoring is known to be one of the introduction vectors. [less ▲]

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See detailTrace elements and stable isotopes during lactation and post-weaning fast in phocids
Habran, Sarah ULg

Doctoral thesis (2012)

Haul-out periods in most phocids are particularly intense from a physiological point of view since they involve extended fasting periods associated with behaviours or processes resulting in considerable ... [more ▼]

Haul-out periods in most phocids are particularly intense from a physiological point of view since they involve extended fasting periods associated with behaviours or processes resulting in considerable energy expenditure (e.g., combat, mating, lactation, moulting). The substantial tissue reorganization during these key periods can entail the mobilization of potentially associated contaminants, such as trace elements and persistent organic pollutants. The main objectives of this study were firstly to investigate the effects of fasting, lactational, and developmental phases on trace element concentrations (Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) in the northern elephant seal (Mirounga angustirostris) and the grey seal (Halichoerus grypus), and on the other hand, to assess the maternal transfer of trace elements to the offspring. Changes in the diet indicators – the carbon and nitrogen stable isotopes (δ13C and δ15N) – were also investigated throughout lactation and post-weaning fast, and their implications were developed. Different tissue samples (blood, blubber, hair, and milk) were collected repeatedly in mother-pup pairs and weaned pups in northern elephant seals and grey seals during three longitudinal fieldworks in the breeding season. Related to the remobilization of resources during lactation and pup development, short-term variations in blood concentrations of trace elements were highlighted in this study. The results imply a careful consideration of the physiological status of marine mammals when using blood in the framework of biomonitoring of trace element contamination. Although the total body burdens of trace elements decreased over lactation in adult females, circulating concentrations of some metals, like Hg, increased significantly, drawing attention to the potential adverse effects on the immune, endocrine or nervous systems in adults. Northern elephant seals and grey seals are exposed to trace elements from the first stages of development through the placenta and through the milk. Indeed, concentrations in pup hair of both species revealed a large accumulation of all assayed trace elements during the foetal development. The maternal transfer of trace elements adds to lactational transfer of others chemicals such PCBs, PBDEs, and OCPs reported in recent studies. Immunotoxic and endocrine risks related to chemical mixtures remain unclear until now and may therefore affect phocids at a crucial period of their immune development. [less ▲]

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See detailL'architecture textuelle de l'oeuvre romanesque de Boris Vian : entre construction et destruction. Analyse des macro-, méso- et microstructures.
Bertrand, Charlotte ULg

Master's dissertation (2012)

Intitulé "L’architecture textuelle de l’œuvre romanesque de Boris Vian : entre construction et destruction. Analyse des macro-, méso- et microstructures", le mémoire a déterminé un mode de composition ... [more ▼]

Intitulé "L’architecture textuelle de l’œuvre romanesque de Boris Vian : entre construction et destruction. Analyse des macro-, méso- et microstructures", le mémoire a déterminé un mode de composition, une double logique constructive et destructive – l’architecture textuelle – dans un ensemble romanesque choisi (six romans de Boris Vian). Il a également examiné l’interaction entre cette structure romanesque et des normes préexistantes (littéraires, langagières, sociales, etc.). À cette fin il a été nécessaire de délimiter trois niveaux textuels : (1) la macrostructure, (2) la mésostructure, (3) la microstructure. [less ▲]

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See detailTailor-made degradable copolymers for the design of advanced drug delivery systems
Cajot, Sébastien ULg

Doctoral thesis (2012)

Over the last decades, polymer micelles have attracted an increasing interest in drug pharmaceutical research because they could be used as efficient drug delivery systems. The goal of this thesis was ... [more ▼]

Over the last decades, polymer micelles have attracted an increasing interest in drug pharmaceutical research because they could be used as efficient drug delivery systems. The goal of this thesis was centered on the design of new smart nanocarriers and more particularly on the basis of reversibly redox-cross-linked polymer micelles. The first part of that work was dedicated to the synthesis of new macromolecular architectures associating biodegradable hydrophobic polymers such as polyester (e.g. PCL), polycarbonate (e.g. PTMC) or also polyphosphate (e.g. PBODOP) and the water soluble poly(ethylene oxide) (PEO) frequently used due to its biocompatible properties. Well-defined block copolymers have been synthesized by ring-opening polymerization. The second part of that work focused on the cross-linking of the hydrophobic block in order to obtain well stabilized micelles. The copolymerization of α-chloro-ε-caprolactone (αClεCL) allows to easy functionalize the hydrophobic block in order to reversibly cross-link the future micelle core by the addition of a disulfide bearing cross-linker. The self assembly of theses copolymers and redox-dependent micellization behaviours have been studied by diffusion light scattering and transmission electronic microscopy. Finally, the potential of these redox-sensitive micelles as active drug delivery system has been analysed by investigating their stealthy behaviours using the complement activation (CH50) test, their cytotoxicity, their cellular internalization and also the redox-sensitive profile of a hydrophobic dye. [less ▲]

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See detailUn milieu graphico-cinématique pour l’apprentissage des dérivées dans une praxéologie "modélisation" : potentialités et limites
Gantois, Jean-Yves ULg

Doctoral thesis (2012)

Ce travail concerne l’apprentissage du calcul des dérivées tel qu’étudié chez des élèves de 16-17 ans aux prises avec des questions mobilisant des mouvements rectilignes, leurs vitesses variables ou non ... [more ▼]

Ce travail concerne l’apprentissage du calcul des dérivées tel qu’étudié chez des élèves de 16-17 ans aux prises avec des questions mobilisant des mouvements rectilignes, leurs vitesses variables ou non et les graphiques de leurs lois de position.
On y analyse ces questions comme composantes d’un milieu et les formes embryonnaires que prend le savoir construit dans ce contexte. Cette recherche illustre en outre en quoi consiste une praxéologie de type « modélisation » et le type particulier de discours technologique susceptible de justifier les techniques mises au point à ce stade. [less ▲]

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See detailEtude génétique de la distance de dispersion du tali (Erythrophleum suaveolens (Guill& Perr.) Brenan) en forêt dense humide tropicale
Gillet, Pauline ULg

Master's dissertation (2012)

The study of the regeneration of tropical timber species is intended to design appropriate conservation strategies and to enable the sustainable exploitation of their populations. This study based on ... [more ▼]

The study of the regeneration of tropical timber species is intended to design appropriate conservation strategies and to enable the sustainable exploitation of their populations. This study based on sample collection made in Cameroon and Gabon in two forest contexts with different population densities, has allowed us to characterize gene flow from tali (Erythrophleum suaveolens) using molecular markers. Direct methods based on analyzes of kinship and proceeding by maximum likelihood, as well as indirect methods based on the heterogeneity of the pollen pool and on the spatial structure of the population, allowed the reconstruction of the events of seed and pollen dispersal. The results show that the species present an exponential distribution of pollen and seeds, the average distance of pollen dispersal would be 240 meters and that of seeds would be 135 meters. We also defined a minimum effective density of 0.09 to 0.2 individuals per hectare depending on the forest context studied. The tali has a rate of inbreeding of 25% to 30 % coupled with strong inbreeding depression. These two features are most likely to affect the regeneration of the species in case of overexploitation. [less ▲]

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See detailCaractérisation de la dynamique d'occupation du sol de la ville de Kisangani (R.D. Congo) et sa périphérie entre 2002 et 2010
Maréchal, Justine ULg

Master's dissertation (2012)

L’évolution démographique des pays du sud sans cesse croissante et les nombreux changements qu’elle provoque sont à la source d’un grand nombre de questions d’étude. Ce sont en particulier les changements ... [more ▼]

L’évolution démographique des pays du sud sans cesse croissante et les nombreux changements qu’elle provoque sont à la source d’un grand nombre de questions d’étude. Ce sont en particulier les changements d’occupation du sol résultant de l’extension d’une ville du sud qui nous ont intéressés dans ce travail de fin d’études, dont l’objectif était de quantifier l’urbanisation et la déforestation à Kisangani (R. D. Congo) entre 2002 et 2010. Des cartes d’occupation du sol ont été réalisées sur la base de deux images SPOT 5 et grâce à une sortie terrain en mars-avril 2012. Les classifications ont été effectuées sur base de l’approche orientée-objet et les méthodes non supervisée et supervisée ont été comparées. Les résultats montrent une meilleure précision des classifications supervisées (K = 0,42 et K = 0,71) par rapport aux classifications non supervisées (K = 0,32 et K = 0,53). Un taux d’extension urbaine de 16 % et une déforestation de 7 % ont pu être mis en évidence suite aux classifications supervisées. Le calcul d’indices de structure spatiale du paysage a permis de segmenter le gradient urbain-périurbain-rural-forêt associé à Kisangani que ce soit en classification non supervisée ou supervisée. Les milieux périurbain et rural sont ainsi caractérisés par une hétérogénéité forte, contrairement aux milieux forestier et urbain qui sont caractérisés par une homogénéité du milieu. La supériorité de la méthode supervisée sur la méthode non supervisée a été démontrée dans la caractérisation de plusieurs aspects de l’étude. [less ▲]

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See detailEtude longitudinale de la motivation d'étudiants universitaires de 1ère année
Mignon, Jacques ULg

Doctoral thesis (2012)

This research is supported by socio-cognitive theories such as the self-determination theory (Deci & Ryan, 1985, 1991). It aims to study the relationship between gender, performance and academic ... [more ▼]

This research is supported by socio-cognitive theories such as the self-determination theory (Deci & Ryan, 1985, 1991). It aims to study the relationship between gender, performance and academic motivation of university students. The first part presents concepts and theories of motivation. Then, it looks at sex inequalities in motivation, especially at the university level. The second part begins with a presentation of the different types of motivation and the tool to measure them: the Motivation Scale in Education - University Studies (Vallerand et al. 1989). This section proposes four different surveys in the framework of the longitudinal study of the academic motivation, which was carried out on three successive cohorts in first year at university. The first exploration is devoted to the evolution of different types of motivatio n during the year. It confirms the existence of variations in the types of motivation and the influence of gender on these fluctuations. The second exploration uses correlation analysis to investigate reciprocal relationships between academic motivation and academic performances. The relationship between motivation and final performances are clearly established from December. Gender differences have been observed but significant variations between cohorts restrict the scope of the results. The third exploration consists of a group-based semiparametric method to estimate academic motivation trajectories. This original approach has confirmed some assumptions made by the self-determination theory of Deci and Ryan (1985). The final exploration of our collected data is based on the possibility to conduct multilevel analyses on repeated measurements. Surprisingly, neither the gender nor the performance of the students can explain the interindividual variance of motivation. Results are discussed with reference to the four different statistical devices used and to the strong cohort effect. [less ▲]

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See detailTerrestrialization and evolutionary radiation of basal embryophytes on the Gondwana
Gonez, Paul ULg

Doctoral thesis (2012)

The conquest of land is one of the most important evolutionary steps in embryophyte evolution. It allowed plants to reach an outstanding level of diversity, conquer a variety of new ecological niches and ... [more ▼]

The conquest of land is one of the most important evolutionary steps in embryophyte evolution. It allowed plants to reach an outstanding level of diversity, conquer a variety of new ecological niches and dominate almost all terrestrial ecosystems. The early floras of Laurussia are well studied. Numerous localities have been known and studied for about two centuries; the scientific literature about those is abundant. On the contrary, the early floras from Gondwana are poorly known, even though this continent gathers the two thirds of the emerged lands in the Pridoli-Lochkovian ages. This work attempts to demonstrate the relevance of the study of Gondwanan early floras for understanding the terrestrialization processes and adaptive radiation of the embryophytes during the Pridoli-Lochkovian. Firstly, we describe two assemblages from South Africa and Brazil. These localities are located on the western margin of Gondwana during the Pridoli-Lochkovian. Six new taxa are described from the Brazilian locality. The latter assemblage demonstrates a diversity equivalent to that of the most diverse assemblage from the Lochkovian of Wales, which was part of Laurussia. Some of the morphological characters described from the latter assemblages allow inferring phylogenetical hypotheses. All these hypotheses are confirmed by a cladistic analysis. Hence the study of Gondwanan early floras also permits to decipher the affinities of some plants of rhyniophytoid architectures The Gondwanan floras also allow drawing some hypothesis about the ecology of rhyniophytoid polysporangiophytes. On the basis of architectural characters (long proximal axes and non-isotomous branchings), we postulate that the early land plants of rhyniophytoid architecture were in competition with each other for sunlight collection and spore dispersal. This implies that the rhyniophytoid communities formed rather dense vegetal mats. It is therefore likely that they were structured as a minute canopy: the long proximal axes are analogous to the tree trunk stratum and the branching crowns are analogous to the canopy. Finally, the study of the oldest South China block plant assemblage demonstrates that the flora from the equatorial belt of Gondwana is radically different from that of its western edge. Contrarily, the study of the Brazilian locality confirms the floral similarities between western Gondwanan and South Laurussian floras. This suggests… [less ▲]

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See detailÉtude de la réponse au changement climatique de Bromus tectorum L., plante invasive de l'Ouest américain, au sein de la mixed-grass prairie
Ortmans, William ULg

Master's dissertation (2012)

This master thesis focused on the effects of climate change on an invasive plant of the Western United States, the cheatgrass (Bromus tectorum L.), in a particular invaded ecosystem: the mixed-grass ... [more ▼]

This master thesis focused on the effects of climate change on an invasive plant of the Western United States, the cheatgrass (Bromus tectorum L.), in a particular invaded ecosystem: the mixed-grass prairie. This annual grass invaded the United States, more than one century ago, and leads to various damages, from a biodiversity loss to huge wildfires with abnormal intensity and range. I had the opportunity to join a Colorado scientific team, working for the United States Department of Agriculture (U.S.D.A.). On the field, I could get data from a large scale experiment: The Prairie heating and CO₂ enrichment experiment (P.H.A.C.E.). One of the aims of this experiment was to study the development of cheatgrass plants, in different treatments: irrigation, native species influence, elevated ambient temperature, and CO₂ enrichment. I measured several growth traits, and could also use last year similar measurements. The analysis of these datasets leads to interesting observations: B. tectorum doesn’t act like most invasive plants, with a bad response to CO₂ enrichment. In contrast, I observed a strong positive effect of the temperature. Considering the current situation, and the results of the experiment, cheatgrass invasion will probably increase with climate change. [less ▲]

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See detailOn the development of an integrated bone remodeling law for orthodontic tooth movements models using the Finite Element Method.
Mengoni, Marlène ULg

Doctoral thesis (2012)

One of the guiding principles in orthodontics is to gradually impose progressive and irreversible bone deformations due to remodeling using specific force systems on the teeth. Bone remodeling leads the ... [more ▼]

One of the guiding principles in orthodontics is to gradually impose progressive and irreversible bone deformations due to remodeling using specific force systems on the teeth. Bone remodeling leads the teeth into new positions with two tissues having a major influence: the periodontal ligament and the alveolar bone. Their mechanical and biological/physiological reactions to orthodontic forces are tightly linked. This mechanical biological coupling can be treated in biomechanical models, focusing on the mechanics and considering the phenomenological aspects of the biology/physiology. The development of such a model for bone tissue within a Finite Element framework is the core of this work. We propose to reconcile two approaches of bone modeling (small strains linear elasticity for remodeling problems and complex constitutive models for other applications) by writing a constitutive model for trabecular bone at macroscopic level, built on morphological parameters to describe the anisotropy, and accounting for effects such as plasticity of the trabeculae. The continuum parameters such as the stiffness can evolve with morphology as remodeling occurs in the tissue. For this, we extend and enhance Doblaré and Garcia's remodeling phenomenological model. The remodeling process corresponds to an evolution of a damage tensor representing the bone morphology. To do so, we propose an integration method for an anisotropic Continuum Damage model coupled to plasticity. Adapting Doblaré and Garcia's remodeling law to our constitutive model, we extend it so that it can be used in the specific case of orthodontic tooth movement, still following Frost's mechanostat theory. We propose to include the hydrostatic pressure dependency of remodeling, due to the presence of the periodontal ligament, within the bone remodeling law. We finally present a validation method for the mechanical representation of the bone matrix through the knowledge of its morphology, both on engineered cellular solids with bone-like morphology (aluminum and polymeric foams) and on bone (Deer antler) samples. Applying the model on the benchmark problem of the proximal femur remodeling, leads to results that are comparable to other models of the literature. We can therefore assume the way the remodeling model is built is valid. We finally apply the developed model to orthodontic tooth movement simulations. First we propose a model accounting for the non-linear mechanical response of the PdL through either bilateral contact conditions or spring models. We then present applications of orthodontic tooth movement, either displacement driven or force driven, both 2D and 3D. We thus show we can qualitatively represent the tooth movement, however outlining some of the drawbacks of the models (an unphysiological density distribution can arise due to the poor representation of the actual loads and a strong dependence on the boundary conditions is pointed out). However, we can represent the formation and resorption of hyaline areas, the non-linearity of the force/displacement relationship, and that applying a stepwise increasing force leads to higher displacements than a high initial force as there is no hyaline zone to resorb. [less ▲]

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See detailÉtude de l’origine des populations d’Ayous (Triplochiton scleroxylon K. SCHUM) dans les forêts du sud-est du Cameroun
Gorel, Anaïs ULg

Master's dissertation (2012)

Triplochiton scleroxylon K. SCHUM (ayous) est une espèce tropicale héliophiles pionnière à haute valeur commerciale. Comme la plupart des espèces de ce tempérament, T. scleroxylon présente actuellement un ... [more ▼]

Triplochiton scleroxylon K. SCHUM (ayous) est une espèce tropicale héliophiles pionnière à haute valeur commerciale. Comme la plupart des espèces de ce tempérament, T. scleroxylon présente actuellement un déficit de régénération. Afin de pérenniser son exploitation il est nécessaire de comprendre quelles sont les conditions à l’origine de la distribution de cette essence. Deux hypothèses ont été testées dans cette étude. Premièrement, une hypothèse anthropique : l’ayous pour se régénérer aurait besoin de trouées larges dans le couvert forestier ; de telles trouées ont probablement été dues par le passé à une activité anthropique en particulier : l’agriculture itinérante sur brûlis. Deuxièmement, une hypothèse édaphique : la distribution de l’ayous serait fonction de la fertilité du sol ; l’ayous serait présent uniquement sur les sols les plus fertiles. Afin de valider ou non ces hypothèses nous avons récolté des données botaniques, pédologiques, anthracologiques et archéologiques sur trois sites répartis le long d’un transect situé dans les concessions de la société forestière SFID au sud-est du Cameroun. Les résultats de notre étude démontrent une relation claire entre la distribution de T. scleroxylon et la richesse du sol : l’espèce se retrouve dans des sols à pH élevé, riches en plusieurs cations métalliques et fuit les sols à pH faible et toxicité importante en aluminium. Nous n’avons pu établir aucune relation entre la présence d’ayous et des perturbations anthropiques passées. Cela est peut-être dû à l’homogénéité de la fréquence des activités anthropiques dans la zone d’étude. [less ▲]

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See detailEvaluation of Macrolophus pygmaeus as biocontrol agent aginst aphids
De Backer, Lara ULg

Master's dissertation (2012)

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See detailGeneralized Shape Optimization using XFEM and Level Set Description
Van Miegroet, Laurent ULg

Doctoral thesis (2012)

CAD based shape optimization aims at finding the shapes of internal and external boundaries of a structural components. The method is able to improve the design of structures against var- ious criteria ... [more ▼]

CAD based shape optimization aims at finding the shapes of internal and external boundaries of a structural components. The method is able to improve the design of structures against var- ious criteria such as restricted displacements, stress criteria, eigenfrequencies, etc. However, this technique has been quite unsuccessful in industrial applications because of the mesh management problems coming from the large shape modifications. The main technical problems stems from the sensitivity analysis requiring the calculation of the so-called velocity field related to mesh modifications. If 2D problems are quite well mastered, 3D solid and shell problems are difficult to handle in the most general way. It turns out that shape optimization remains generally quite fragile and delicate to use in industrial context. To circumvent the technical difficulties of the moving mesh problems, a couple of methods have been proposed such as the fictitious domain approach, the fixed grid finite elements and the projection methods. The present work relies on the application of the extended finite element method (X-FEM) to handle parametric shape optimization. The X-FEM method is naturally associated with the Level Set description of the geometry to provide an efficient and flexible treatment of problems involving moving boundaries or discontinuities. On the one hand, the method proposed benefits from the fixed mesh approach using X-FEM to prevent from mesh management difficulties. On the other hand, the Level Set description provides a smooth curves representation while being able to treat topology modifications naturally. In this thesis, we focus on the material-void and bi-material X-FEM elements for mechanical structures. The representation of the geometry is realized with a Level Set description. Basic shapes can be modeled from simple Level Set such as plane, circle, ... NURBS curves and surfaces that can be combined together using a Constructive Solid Geometry approach to represent com- plex geometries. The design variables of the optimization problem are the parameters of basic Level Set features or the NURBS control points. Classical global (compliance, eigenfrequencies, volume) and local responses (such as stress constraint) can be considered in the optimization problem that is solved using a mathematical programming approach with the CONLIN optimizer. The problem of the computation of the shape sensitivity analysis with X-FEM is carefully ad- dressed and investigated using several original methods based on semi-analytical and analytical approaches that are developed. Academic examples are first considered to illustrate that the proposed method is able to tackle accurately shape optimization problems. Then, real life struc- tures including 2D and 3D complex geometries illustrate the advantages and the drawbacks of using X-FEM and Level Set description for generalized shape optimization. [less ▲]

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See detailRôle des gènes pax4 et arx au cours de la différenciation endocrine pancréatique chez le poisson zèbre
Djiotsa, Joachim ULg

Doctoral thesis (2012)

Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies β- and δ-cell fate at the expense of α-cell identity by ... [more ▼]

Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies β- and δ-cell fate at the expense of α-cell identity by repressing Arx gene expression and ectopic expression of PAX4 in α-cells is sufficient to convert them into β-cells. Surprisingly, no Pax4 orthologous gene can be found in chicken and xenopus tropicalis raising the question of the function of Pax4 gene in lower vertebrates such as in fish. In the present study, we have analysed the expression and the function of the orthologous pax4 gene in zebrafish. In zebrafish, pax4 is not required for the generation of pancreatic β- and δ-cells, unlike its crucial role in the differentiation of these cell types in mouse. On the other hand, the mutual repression between Arx and Pax4 is observed in both mouse and zebrafish. These data suggests that the main original function of Pax4 during vertebrate evolution was to modulate the number of pancreatic α-cells and its role in β-cells differentiation appeared later in vertebrate evolution. [less ▲]

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See detailAPPLICATION OF GEOMATICS FOR THE ASSESSMENT OF PASTORAL RESOURCES IN MOROCCO
Mahyou, Hamid ULg

Doctoral thesis (2012)

Rangeland or natural arid pastures of Morocco are defined as ecosystems where there is a natural or semi-natural vegetation composed of steppes, shrubs and grassland used mainly for livestock production ... [more ▼]

Rangeland or natural arid pastures of Morocco are defined as ecosystems where there is a natural or semi-natural vegetation composed of steppes, shrubs and grassland used mainly for livestock production as climate and soil are unsuitable to agriculture. The arid rangelands of Morocco occupy an area of over 33 million hectares between the isohyets of 100 and 400 mm. These areas represent livelihoods for thousands of people and protect the country from desertification. The main objective of this study is to provide scientific community and decision-makers methodological tools for assessing arid rangelands, based on geomatics and biophysics data. This study is divided in four parts: 1. The first part presents an overview of the threat of the desertification, emphasizes on the causes and consequences of rangeland degradation in Morocco, from literature sources, statistics, climate data and maps. Morocco rangelands are located in ten different pastoral zones that differ from each other by their floristic composition, soil and climatic conditions. According to Globcover map these rangelands are mainly composed by bare soil, herbaceous vegetation, shrubs and deciduous savanna mosaic / shrub or forest. The largest pastoral zones are: the Saharan zone, Pre-Saharan, the Oriental plateaus and the Valley of Moulouya. These zones are the most degraded with respectively 97, 89 and 69% of their total area. Available information on several pilot areas shows that the Moroccan rangelands are degraded due to many factors, which include overgrazing, cultivation, population increase and climate variation. 2. The second part of the study demonstrates the usefulness of remote sensing for assessing drought in arid rangelands of Morocco. Bi-weekly TERRA Moderate Resolution Imaging Spectroradiometer (MODIS 250 meters) data were used for this purpose. A Preliminary mapping by using Landsat TM5 of major land cover types was carried out to extract the pasture area. A comparison of annual and seasonal Normalised Difference Vegetation Indices (NDVI), Vegetation Condition Index (VCI) and rainfall during the time period of 2000–2008 were carried out. Results show significant correlations of either NDVI (r= 0.72**) or VCI (r=0.42*) with past season (3 months) rainfall. NDVI variation is a good indicator of vegetation changes and consequently can give a reliable indication on drought conditions in the study area. NDVI values lower than 0.2 are indicative of drought occurrence. NDVI values between 0.20 and 0.28 indicate average weather conditions and values higher than 0.28 correspond to humid conditions. 3. The third part presents an original knowledge-based approach for mapping the degradation of rangelands in North Africa. The study area is located in the high plateaus of eastern Morocco which include 3.5 million hectares of arid rangeland steppes. The approach consists in using datasets derived from Landsat TM satellite imagery, lithology, phytogeographic data and field indicators. The field indicators are: the steppes composition, perennial vegetation cover, annual perennial production, grazing level and the prevalence of rangeland cultivation. Results show that the knowledge-based approach is a valid method for evaluating rangeland degradation. The proposed knowledge-based approach discriminated between rangeland categories that would not have been discernible using only remote sensing. Overall classification accuracy of rangeland degradation obtained using this approach was 93%. This approach revealed that 11, 36 and 30% of the study area have shown very severe, severe and moderate degradation level, respectively. 4. The fourth part concerns the assessment of Alfa grass (Stipa tenacissima) tussocks at various degradation levels of Alfa grass steppes in the high plateaus of eastern Morocco, based on field hyperspectral data (350 – 2500 nm) and digital images during fall and spring seasons. Digital images of Alfa grass tussocks were taken using a digital camera to classify of the tussocks according to their proportion in green leaves (green, mixed and dry tussock). Assess software (Image Analysis Software for Plant Disease Quantification, APS 2002) was used to obtain the proportion of greenness in each tussock. Hyperspectral data of three states of tussocks (Green, Mixed and Dry tussock leaves) were collected within three degradation levels of Alfa grass steppes (Slight, Moderate and Severe degradation) with the ASD FieldSpec® 3 spectroradiometer. Paired t-test, Normalized difference spectral reflectance (NDSR) and Stepwise Discriminate Analysis were used to discriminate between various tussock status and different Alfa grass steppes. The results indicate that Alfa grass had shown an intraspecific variability in reflectance spectra. The proportion of green leaves in Alfa grass tussock strongly influences the spectral response. The discrimination of different Alfa grass tussock status was better during fall than spring. The spectral behavior of Alfa grass tussock is problematic for the mapping and the assessment of Alfa grass steppes by conventional remote sensing techniques. [less ▲]

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See detailRESEARCHES REGARDING COLLOIDAL AND OXIDATIVE STABILITY OF CONFECTIONERY PRODUCTS (HALVA) OBTAINED FROM SUNFLOWER
Muresan, Vlad ULg

Doctoral thesis (2012)

Prior to the experimental part of this work, a literature review related to the aim of this thesis was realized. Firstly, it describes the balanced nutritional composition of sunflower seeds and their ... [more ▼]

Prior to the experimental part of this work, a literature review related to the aim of this thesis was realized. Firstly, it describes the balanced nutritional composition of sunflower seeds and their applications as food industry raw materials. It follows the state of the art of sunflower halva manufacturing with emphasis on the main issues encountered during processing. Consequently, as the researches concerning sunflower halva type products are very limited, it was decided to consolidate the identified quality problems (i.e., oil separation problem and rancidity during storage) background by given basic principles concerning foods physical properties (e.g., rheology, particle size distribution), as well as food products colloidal and oxidative stability basics. Moreover, fundamentals of NIR spectroscopy and chemometrics give the background for a proposal of an alternative nondestructive and rapid method to assess lipid oxidation in sunflower halva type products. Firstly, the experimental part of this thesis focuses on comparing the physico-chemical properties of different particle size tahini prototypes including also the industrial reference in order to understand tahini behavior and structure. Studying the physico-chemical properties of different granulometries tahini samples allows, for the first time, the prediction of a schematic sunflower tahini structure – knowledge needed to understand physical and oxidative instability for this type of products. Moreover, the experimental work aimed to assess the influence of particle size distribution, storage time and temperature on sunflower tahini colloidal and oxidative stability. Furthermore, during this work there were developed two new methodologies, a laser diffraction method to determine particle size distribution of sunflower tahini, as well as a near infrared rapid method coupled with chemometrics to assess in situ sunflower tahini oxidative status. [less ▲]

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See detailEtude de l'hydrodynamique au sein d'un bioréacteur à cuve agitée utilisé pour la culture de cellules animales adhérentes sur microporteurs: Caractérisation expérimentale et théorique des écoulements via des outils eulériens et lagrangiens
Collignon, Marie-Laure ULg

Doctoral thesis (2012)

Cette thèse a été financée par le FNRS (Fonds National de Recherche Scientifique belge) via un mandat d’aspirant (1.1.2002.10.F, 78014). Elle a été réalisée au Laboratoire de Génie Chimique de ... [more ▼]

Cette thèse a été financée par le FNRS (Fonds National de Recherche Scientifique belge) via un mandat d’aspirant (1.1.2002.10.F, 78014). Elle a été réalisée au Laboratoire de Génie Chimique de l’Université de Liège sous la supervision des Professeurs Dominique Toye et Michel Crine. La thématique de recherche s’inscrit dans le cadre d’une collaboration scientifique entretenue depuis de nombreuses années entre le Laboratoire de Génie Chimique et la société pharmaceutique GlaxoSmithKline Biologicals. Elle concerne la culture de cellules animales adhérentes sur microporteurs en bioréacteur de type cuve agitée. Ce type de procédé est, en effet, largement utilisé dans l’industrie pharmaceutique pour produire des composés protéinés tels que des vaccins, des glycoprotéines et des anticorps monoclonaux. Le choix du design et des conditions d’agitation de ce type de bioréacteur est complexe car il doit répondre à deux objectifs antagonistes : maximiser le mélange du milieu de culture tout en minimisant les contraintes mécaniques qui peuvent agir sur les cellules animales, ces dernières étant réputées comme particulièrement sensibles à ces contraintes lorsqu’elles sont fixées à la surface de microporteurs. Pour aider à réaliser ce choix, nous avons développé dans cette thèse une méthodologie qui tente de décrire l’influence des conditions d’agitation sur l’environnement hydrodynamique local perçu par un élément de fluide en mouvement via une description combinée eulérienne et lagrangienne de l’écoulement turbulent au sein du bioréacteur. Le Chapitre I a pour but de présenter l’état de l’art relatif à la culture de cellules animales adhérentes dans des bioréacteurs à cuve agitée, ainsi que d’introduire l’essentiel des notions théoriques qui seront utilisées dans la suite de la thèse. Il est divisé en quatre parties. La première partie présente les spécificités de la culture de cellules animales de mammifères et les défis technologiques associés. La deuxième partie introduit, en se basant sur diverses études antérieures, le problème central de cette thèse. La troisième partie présente l’approche adoptée dans cette thèse pour répondre au problème posé. L’originalité de l’approche adoptée est également mise en évidence. Dans la quatrième partie, les hypothèses nécessaires à ce travail sont présentées et validées sur base de résultats issus d’autres études publiées dans la littérature. Le Chapitre II a pour but de sélectionner deux mobiles axiaux auxquels sera appliquée la méthodologie développée dans cette thèse. Pour ce faire, sept mobiles axiaux sont comparés sur base des contraintes mécaniques qu’ils génèrent, estimées à partir de la mesure de la puissance globale dissipée, lorsqu’ils tournent respectivement à leur vitesse minimale de maintien des microporteurs en suspension complète Njs. Cette comparaison permet de sélectionner les mobiles TTP 125 (d/T=0.4, Mixel) et EE 150 (d/T=0.5, Applikon). Le Chapitre III est consacré à l’étude eulérienne détaillée de l’écoulement turbulent généré par les deux mobiles sélectionnés au chapitre précédent. Sur base de mesures 3D P.I.V., les champs moyens de vitesse dans cinq plans axiaux sont établis et analysés. Ce même exercice est réalisé pour les grandeurs caractéristiques de la composante turbulente de l’écoulement que sont l’énergie cinétique turbulente et son taux de dissipation. Grâce à ces données, la répartition spatiale des contraintes mécaniques au sein de l’écoulement turbulent est établie ; ce qui permet d’identifier au sein de la cuve des zones labélisées comme potentiellement problématiques pour le développement des cellules cultivées sur les microporteurs. Dans le Chapitre IV, l’impact de gradients de concentration présents au sein de la cuve, suite à une injection de soude par exemple, est évalué. Dans ce but, le mélange au sein du bioréacteur a été étudié de manière globale par la mesure de temps de mélange et de manière locale par la mesure de l’évolution avec le temps de champs de concentration par la technique P.L.I.F. Ces mesures ont montré que le temps d’ « existence » des gradients de concentration est nettement inférieur aux temps caractéristiques relatifs à une modification du métabolisme cellulaire. Il en résulte que, dans la suite du travail, les champs de concentration seront supposés comme constants et uniformes au sein de la cuve agitée. Les hétérogénéités ponctuellement présentes après l’ajout de soude ne seront donc pas prises en compte dans la caractérisation Euler-Lagrange de l’écoulement. La première partie du Chapitre V présente le principe et les outils de modélisation nécessaires à la mise au point et au fonctionnement du dispositif de trajectographie optique conçu et développé dans le cadre de cette thèse. Cette installation, tout à fait originale et unique, permet de suivre la trajectoire d’une particule au sein de la cuve agitée pendant des temps très longs et permet donc d’accéder à l’étude lagrangienne de l’écoulement. La seconde partie du chapitre est consacrée à la caractérisation des trajectoires mesurées. L’isoprobabilité de présence de la particule dans tout volume élémentaire de la cuve agitée a pu être confirmée. La validité et la convergence des résultats obtenus par trajectographie ont pu être vérifiées par comparaison des champs de vitesse calculés à partir des trajectoires avec ceux mesurés par 3D P.I.V. Au Chapitre VI, les données eulériennes sont combinées aux données lagrangiennes afin de caractériser le lien entre la succession d’environnements hydrodynamiques perçus par des cellules fixées sur des microporteurs et les conditions d’agitation du bioréacteur. Cette caractérisation repose principalement sur l’analyse de la distribution de temps de séjour de la particule dans la zone labélisée comme problématique pour le développement cellulaire DTSzone , de la distribution de temps de séjour de la particule dans la zone non problématique DTShors zone ainsi que sur l’analyse des distributions de temps mis par la particule pour réaliser un cycle « visite de zone problématique-visite de zone non problématique » DTcycle. La taille des zones problématiques et non problématiques dépend de la valeur choisie pour le critère λK/dp, du type de mobile, ainsi que de sa vitesse de rotation. L’impact de ces trois grandeurs sur les distributions de temps a donc été analysé. Cette thèse se clôture bien naturellement par un chapitre de conclusion résumant les informations acquises et proposant diverses perspectives [less ▲]

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See detailLes manuscrits de la recension égyptienne des Mille et une Nuits. Étude codicologique, avec édition critique, traduction et analyse linguistique et littéraire du conte de Jānšāh
Franssen, Elise ULg

Doctoral thesis (2012)

The Thousand and One Nights have fascinated millions of readers and have spawned a variety of scholarly literature. Analyses of the tales are based on existing editions of the Arabic text, almost all ... [more ▼]

The Thousand and One Nights have fascinated millions of readers and have spawned a variety of scholarly literature. Analyses of the tales are based on existing editions of the Arabic text, almost all dating back to the 19th century, and none of them completely reliable. However, since Zotenberg’s classification of the manuscripts of the Nights in the 19th century, research on the manuscripts has not really progressed. One of the groups Zotenberg described, called now the ZER, “Zotenberg's Egyptian Recension”, gathers together the manuscripts containing exactly 1001 nights, copied in Egypt at the end of the 18th or at the beginning of the 19th century. All the manuscripts of the ZER are in four volumes and present the same distribution of nights; they also share many common codicological features. A precise codicological analysis of each of those manuscripts was carried out. The collected information was compared with the conclusions of the literary and philological study of each manuscript’s text in a complete approach to the manuscripts, seen as objects as well as texts. The Nights were written for the bourgeoisie, in their own language, Middle-Arabic. This level of language was deliberately used for certain literary productions, such as literature intended for entertainement. A close study of the language of the manuscripts provides information on this level of language still little known. The study was carried out on Jānšāh tale, and a synoptic critical edition —confronting the manuscripts to the ancient editions of Būlāq and Calcutta II, collated for the occasion— and French translation of the latter were prepared. In brief, codicological analyses provide useful information for the research in codicology and for the classification of the manuscripts, a prerequisite for the critical edition. The analysis of the text’s language makes an important contribution to a neglected field. The text of the critical edition constitutes a solid basis for the investigations into the contents of the story. [less ▲]

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See detailAmélioration du tri de semences de chicorée industrielle (Cichorium intybus L.) sur base d’attributs mesurés par vision artificielle
Ooms, David ULg

Doctoral thesis (2012)

The commercial production of industrial chicory seeds (cypselae) includes the postharvest elimination of nonviable seeds by non-destructive tools. For this purpose, two machine vision methods were set up ... [more ▼]

The commercial production of industrial chicory seeds (cypselae) includes the postharvest elimination of nonviable seeds by non-destructive tools. For this purpose, two machine vision methods were set up for the detection of nonviable seeds: color vision and fluorescence imaging. In addition, the appropriate criteria to estimate the efficiency of seed sorting were defined using a sorting optimization curve which describe the trade-off between the quality improvement of a seed lot and the loss of material. The analysis of color images of 1,500 seeds of the ‘Nausica’ variety allows only the recognition of desiccated and undeveloped seeds. This is caused by the large natural variability of seed color, shape and texture. Fluorescence imaging was set up in order to analyze the repartition of chlorophyll fluorescence (CF), a marker of seed maturity, on different areas of the seed (pericarp and pappus). It comprised a monochromatic light source, a highpass filter and a monochromatic CCD camera sensitive to red and infrared. With this device, blue light reflected by the seeds was blocked whilst red fluorescence was measured by the camera. A segmentation algorithm was designed to estimate separately the fluorescence intensities of the pappus, a crown of scales, and the main body of the pericarp. Experiments were carried out on five clones of cross-pollinated chicory plants used for seed production and four series of 30 plants from 2 common varieties grown in different weather conditions. The flower heads were labelled at flowering and harvested at different times during the maturation process expressed in "days after flowering" (DAF). Germination tests were performed according to the recommendations of the International Seed Testing Association to measure the germination percentage (GP) and the germination rate (GR), an indicator of seed vigour. The dry weight (DW), water content (WC), maturation duration, germination percentage (GP), and germination rate (GR) were measured to estimate seed quality. For all experiments, the chlorophyll fluorescence diminished mainly between 16 and 33 DAF during the filling phase of seed development. The correlations between CF and maturity parameters (DW, WC) were comprised between 0.25 and 0.75 in absolute value for seeds that matured 16 to 44 days on the stalk. Sorting simulations were made on the basis of CF alone or in combination with the achene area density (AD) (mg/mm²). The CF was efficient to select seeds produced outdoor or in the greenhouse with the aim of increasing GP or GR but AD was an even better sorting feature. In the greenhouse, where developing seeds were submitted to temperatures higher than 25 °C, the use of CF in combination with AD improved the sorting efficiency. [less ▲]

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See detailStudy of the effect of waxes on the biological activity of essential oils against Penicillium italicum Wehmer and P. digitatum Sacc, two postharvest pathogens of citrus fruits
Kouassi, Kouadio Hugues Sosthène ULg

Doctoral thesis (2012)

Control measures of postharvest fungal diseases of plants are principally based on the use of conventional chemical fungicides. However, in view of the problems associated with the use of these ones, as ... [more ▼]

Control measures of postharvest fungal diseases of plants are principally based on the use of conventional chemical fungicides. However, in view of the problems associated with the use of these ones, as well as the increasing demand for organically produced food, there is a need to replace chemical fungicides by alternative safer products, such as biological fungicides called "natural" or biofungicides. Among natural fungicides, essential oils (EOs) have been studied. EOs and their compounds present, among other things, antifungal properties and can be an interesting alternative to chemical fungicides. For this purpose, a screening of EOs according to intrinsic (yield in aromatic plant, toxicity) and extrinsic (availability, cost) criteria was carried out. Thirty EOs were selected and their inhibitory activity was tested on the in vitro growth of Penicillium italicum Wehmer, P. digitatum Sacc (pathogens of citrus fruits) and Colletotrichum musae (Berk. & M.A. Curtis) (pathogen of banana). Cinnamomum zeylanicum, C. verum and Eugenia caryophyllata proved to be the most effective at 100 ppm against the three pathogens. The biological activity of these three EOs against P. digitatum and P. italicum was evaluated on artificial infected orange fruits. EOs diluted in ethanol were able to either partially (at a concentration < 5%) or totally (at a concentration ≥ 5%) control disease incidence due to infections of both pathogens. Among the three EOs, C. zeylanicum was the most effective. In order to improve the efficiency of C. zeylanicum EO, a development of formulations consisting of this EO and Simulgel (thickening and emulsifying polymer) or waxes (shellac and / or carnauba, paraffin or polyethylene) were performed. The in vivo biological activity of the formulations was also evaluated against P. digitatum and P. italicum. In general, fungal disease control was improved in the case of fruits treated with C. zeylanicum EO supplemented with Simulgel or waxes compared to that supplemented with ethanol. The improvement was much higher with formulation consisting of C. zeylanicum-shellac (and / or carnauba) compared to the others. A SPME/GC-MS analysis of the headspace of EOs (C. zeylanicum, C. verum and E. caryophyllata) supplemented with shellac and / or carnauba (in vitro) or of oranges treated with such formulations (in vivo) highlighted the lack of some specific volatile compounds of EOs (oxygenated cyclic ones with a specific gravity superior to 0.934), in the vapor phase of the in vitro and in vivo tests, even after 7 days. While when these EOs were supplemented with ethanol, Simulgel, paraffin or polyethylene, all EO compounds were detected in the analyzed headspaces from 4 hours up to 7 days. Analysis of formulations by Fourier transform infrared spectroscopy (FTIR) revealed the formation of hydrogen bonds between such specific EO compounds and waxes (shellac and / or carnauba) This hydrogen bonds formation seems to be responsible of the non-volatilization of EO compounds and their maintaining on the fruit epidermis, thus improving citrus fruit protection. These hydrogen bonds are not observed between non-oxygenated or non-cyclic oxygenated EO compounds and none of the waxes. The present study may therefore allow a careful selection of appropriate EOs and waxes for the elaboration of effective biofungicide formulations. This application could be integrated into the packline procedure without significant modification. [less ▲]

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See detailIdentification des sirtuines en tant que nouvelles cibles thérapeutiques pour l'asthme allergique
Legutko, Agnieszka ULg

Doctoral thesis (2012)

Sirtuins comprise a unique class of NAD+-dependent deacetylases that regulate diverse biological functions including ageing, metabolism and stress resistance. Recently, it has been shown that sirtuins may ... [more ▼]

Sirtuins comprise a unique class of NAD+-dependent deacetylases that regulate diverse biological functions including ageing, metabolism and stress resistance. Recently, it has been shown that sirtuins may dampen the inflammatory response in vitro by inhibiting pro-inflammatory transcription factors such as NF-κB. We therefore sought to determine whether sirtuins play a role in allergic airway inflammation. To address this issue, we have assessed in OVA-sensitized mice the effects of selectively antagonizing sirtuins during OVA challenge. Sirtuin inhibition was achieved by treating mice with either cambinol or sirtinol, two selective pharmacological inhibitors. Surprisingly, sirtuin inhibition was associated with strong attenuation of allergic lung inflammation, airway hyperreactivity, production of mucus and Th2 cytokines. We furthermore showed that sirtuin inhibition altered maturation and migration of lung dendritic cells, thereby preventing dendritic cell-driven Th2 priming in the draining lymph nodes. In an attempt to elucidate the mechanisms responsible for these effects we used peroxisome proliferator-activated receptor-γ deficient cells to demonstrate that the effects of cambinol and sirtinol in dendritic cells were dependent on an increase in the activity of this anti-inflammatory transcription factor. Finally, using genetic engineering, we demonstrate that sirtuin 1 is the sirtuin responsible for repression of the activity of PPAR-γ- in dendritic cells, thereby favoring their maturation toward a pro-Th2 phenotype. This study reveals a previously unappreciated function of sirtuin 1 in the regulation of dendritic cell function and Th2 responses, thus shedding new light on our current knowledge on the regulation of inflammatory processes by sirtuins. [less ▲]

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See detailDecomposition, Localization and Time-Averaging Approaches in Large-Scale Power System Dynamic Simulation
Fabozzi, Davide ULg

Doctoral thesis (2012)

Present-day interconnected electric power systems are the largest machines in the world. Guaranteeing a stable supply of electric power is vital for modern societies: power systems must be able to ... [more ▼]

Present-day interconnected electric power systems are the largest machines in the world. Guaranteeing a stable supply of electric power is vital for modern societies: power systems must be able to withstand plausible disturbances. A certain number of simulations of the post-disturbance behavior are routinely executed by some transmission system operators to assess that the system is operated in a secure way. Usually this assessment has to be performed within a predefined time frame, using the available computing resources. Improving the simulation speed allows the operators to perform a wider assessment, thus making better use of the available computational power. A large part of this research took place in the context of the PEGASE project, supported by European Commission (Seventh Framework Programme) and has resulted in some novel algorithms for faster dynamic simulations, one of the PEGASE project main goals. First, this thesis revisits the Newton method used to solve the differential-algebraic model. Then, three original algorithmic improvements are presented, namely (i) decomposition, (ii) localization and (iii) time-averaging of the system response. Finally, the combination of these approaches is shown to provide a fast and reliable tool for dynamic security assessment. All the presented techniques have been thoroughly tested on an academic system, a large real-life system and a realistic system of unprecedented size, representative of the whole continental European synchronous grid. [less ▲]

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See detailImproving Overlay Routing scalability using an Internet Coordinate System
Cantin, François ULg

Doctoral thesis (2012)

Nowadays lots of real time applications are used over the Internet: voice over IP, online video games, etc. For these applications the performance of the path between two communicating nodes is critical ... [more ▼]

Nowadays lots of real time applications are used over the Internet: voice over IP, online video games, etc. For these applications the performance of the path between two communicating nodes is critical. Particularly, most of these applications require small delays between communicating nodes. For these applications, the problem is that the choice of the routes in the Internet is generally not very much guided by performance concerns. It is well known that for lots of node pairs the default Internet path is suboptimal and there exists an alternative path providing a smaller delay between these nodes. In this thesis, we mainly address the problem of finding these alternative paths. Replacing Internet's routing philosophy in order to obtain default paths providing the best performance possible should be a good theoretical solution. However, replacing Internet's routing philosophy by a brand new one is very difficult or even impossible in practice. Another solution is to leave the default routes as they are and to perform indirect routing. Consider a path AB between two nodes A and B. If a path ACB has a smaller delay than AB, then, instead of sending data directly to B, A can send them to C and C can relay them to B. This is called overlay routing because we manage the routing in an overlay network built on top of the Internet (i.e. at the application level). Overlay routing is a promising way to improve the quality of service in the Internet but its main drawback is its poor scalability: measuring the characteristics of the paths, exchanging the measurement results between the nodes and computing the best routes in the full mesh overlay network generally implies a high consumption of resources. In this thesis, our main contribution is the design of a lightweight one-hop overlay routing mechanism improving the latencies: we define criteria that rely on the information provided by an Internet Coordinate System (ICS) in order to provide a small set of potential one-hop shortcuts for any given path in the network with small costs. Our best criterion does not guarantee to find the best shortcut for any given path in a network but, even in networks with hundreds or thousands of nodes, it will restrict the search for potential shortcuts to about one or two percent of the total number of nodes. Even if the estimation-based approach of overlay routing is our main contribution, this thesis also presents general results about routing shortcuts and Internet Coordinate Systems. For an ICS, a routing shortcut is a Triangle Inequality Violation (TIV) and it is often a big problem. Indeed, a TIV will cause estimation errors since, in this particular case, nodes cannot be embedded into any metric space. In this thesis, we study TIVs existing in the Internet and their impact on the Vivaldi ICS. This analysis leads to two contributions. Firstly, we propose criteria to establish, with a high probability of success, if there exists a shortcut or not for a given path AB. Secondly, we propose a Two-Tier architecture for ICSes that mitigates the effect of TIVs on the estimations. Finally, this thesis also discusses the efficiency of two solutions proposed in the literature in order to obtain an ICS that can deal with TIVs. The first one consists in applying non-linear transformations to delays before trying to embed them in a metric space. The second one consists in modelling the estimation problem as a matrix completion problem in order to completely avoid the embedding in a metric space. [less ▲]

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See detailClimate-driven growth of croplands and grasslands: analysis and modeling at regional scale
Horion, Stéphanie ULg

Doctoral thesis (2012)

Comprehensive understanding of the interactions between climate and vegetation is a key issue in environmental sciences, and especially for researchers studying climate change impacts on terrestrial ... [more ▼]

Comprehensive understanding of the interactions between climate and vegetation is a key issue in environmental sciences, and especially for researchers studying climate change impacts on terrestrial ecosystems. Indeed in order to better predict changes in ecosystems productivity, scientists are investing time and e ort in assessing how environmental changes are influencing - and are going to influence in the near future - the vegetation distribution and dynamics. Temperature, precipitation and atmospheric CO2 are the key determinants of the distribution of vegetation on Earth. Over the last 150 years, it has been reported that the global surface temperature has increased on average by around 0:8 C. Several studies mentioned that this rapid warming has resulted in reduction of climatic constraints to biological activity and shift in growing season. However changes in vegetation dynamics are not uniform spatially. From a methodological point of view, annual and seasonal metrics were commonly used to assess the impact of climate variability on vegetation at global and continental scales. The studies therefore neglected that intra-annual variability in the response of terrestrial ecosystems to such changes may exist. This intra-annual variability can be seen as the difference in vegetation response to a given environmental change according to its phenological development. In this research we investigated the intra-annual variation of the climatic constraints over croplands and grasslands in 25 regions located in Europe and Africa. The central question was: how best can we identify the climate footprint on vegetation development during the growing season, using global datasets of Normalized Difference Vegetation Index (NDVI) and the JRC-MARS meteorological indicators? The structure of this study is as follows. First we provide an overview of major studies linking climate variability and vegetation dynamic at global, continental and regional scales. Then we describe the NDVI and meteorological datasets used in this research, as well as the methodology developed to select optimal regions of interest for the study of 'climate-vegetation' interactions at regional scale. Indeed external factors - such as land cover changes, landscape fragmentation, etc. - need to be minimized to ensure that the variations in the NDVI signal can be attributed to climate variability. Preliminary time series analyses are then performed to characterize the long-term climate and vegetation conditions in each region of interest. We further present the approach developed in this research to decompose and to analyse jointly time series of remote sensing derived observation and climate dataset. We focus specifically on the adjustment of the 'climate-vegetation' relationships for specific periods within the growing season. Indeed we demonstrate that the relationship between NDVI and the meteorological parameters is highly complex and vary significantly trough the phenological cycle of the plants. Hence, interactions between vegetation dynamics and climate variability need to be studied at a smaller time scale than the year or the growing season, in order to identify properly the limiting factors to vegetation growth. Our analysis revealed that, in most of the cases, the best correlations are obtained when we considered the vegetative phase (from green-up to maximum of NDVI) and the reproductive phase (from maximum of NDVI to maturity) separately. We also show that climatic constraints identified using yearly proxies of climate and vegetation do not depict correctly, or completely, the climate control on vegetation development. Finally we evaluate the performance of climate-driven growth models in two sites of croplands and two sites of grasslands. The models were adjusted per phenological phases and set to provide 1-month forecast of NDVI. Pure climatic models (CLIM) were compared to auto-regressive climatic model (CLIM-AR). Apart in the Irish grasslands, the CLIM-AR models were performing better than CLIM models during the vegetative phase. On the other hand, during the reproductive phase, the introduction of the auto-regressive term did not improve significantly the performance of the CLIM model. Moreover the autoregressive term did never appear as first predictor, demonstrating that, in the selected sites, short to medium atmospheric conditions were explaining most of the variance in the 1-month forecast NDVI. [less ▲]

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See detailLe consommateur mineur. Analyse juridique de la protection d'une personne doublement vulnérable
Nottet, Aurélie ULg

Doctoral thesis (2012)

La dissertation porte sur le statut juridique du consommateur mineur en Belgique, dans une vision intégrée mêlant droit des incapacités et droit de la consommation. Le mineur, personne vulnérable en ... [more ▼]

La dissertation porte sur le statut juridique du consommateur mineur en Belgique, dans une vision intégrée mêlant droit des incapacités et droit de la consommation. Le mineur, personne vulnérable en raison de son âge, est protégé par le droit. Notamment, il est soumis à un statut civil d’incapacité qui l’empêche de contracter valablement seul (art. 1124 C. civ.). Le consommateur, « personne physique qui acquiert ou utilise à des fins excluant tout caractère professionnel des produits mis sur le marché », est également protégé par le droit (règles consuméristes) en tant que partie faible au contrat conclu avec une entreprise. Le mineur consommateur s’impose comme une réalité (notamment avec l’avènement d’Internet). Destinataire de nombreux produits, cible privilégiée des annonceurs publicitaires, il devient un acteur économique à part entière. Comment le droit encadre cette réalité ? Quel statut réserve-t-il au consommateur mineur ? Ce statut est-il satisfaisant ? La thèse tend à répondre à ces questions. Elle brosse donc un portrait juridique précis du consommateur mineur, et propose quelques améliorations de lege ferenda. Elle comporte du reste une dimension de droit comparé: sur les points centraux, des solutions de droit français, néerlandais et allemand enrichissent l’analyse du droit belge. Elles en permettent une critique plus objective et/ou inspirent des solutions originales. [less ▲]

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See detailÉtude de la dissipation d'énergie sur un coursier en marches d'escalier en aval d'un évacuateur de crue de type PKW
Silvestri, Aurélien ULg

Master's dissertation (2012)

The present research follows a previous study led by Erpicum et al. in 20112. The main purpose of this study is to affirm by experiments the theory, which states that in some particular cases, using a ... [more ▼]

The present research follows a previous study led by Erpicum et al. in 20112. The main purpose of this study is to affirm by experiments the theory, which states that in some particular cases, using a piano key weir (PKW) at the top of a stepped spillway instead of a standard ungated spillway with an equal length would result in an increased dissipation of energy. Another way to present this theory is to show that specific geometrical dimensions of the piano key weir can be determined to reach an uniform flow for reduced dimensions of stepped spillways (compared to standard ungated weir). The second goal is to set up analytical methods enabling the evaluation of the energy dissipation on this kind of construction using basic data’s (ex. inclination and geometry of the spillway, geometry of the steps on the spillway, flow,…). In order to reach those objectives, a series of experiments has been executed on a facility at the HECE laboratory. The tests allowed us to acquire different hydraulic parameters that have been used to calculate the energy dissipation on the reduced bench test. It is important to notice that we used an experimental analyzing method for signals. First of all, we have been able to prove the validity of the initial theory using the results of the tests on the facility. Secondly, the analyze and interpretation of the results led us to define criteria’s indicating the apparition of the uniform or non uniform flow depending of the kind of weir used on the spillway. Finally, using the results of the tests we established some analytical formulas for each kind of flow on a free weir and a PKW. Those analytical formulas present a correlation with experiments moreless accurate depending on the interpolation choosen and the set of bench tests realized. [less ▲]

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See detailSimulacres et Futurs antérieurs: Contributions à une approche narrative du politique
Claisse, Frédéric ULg

Doctoral thesis (2012)

The thesis assembles five publications dealing with the role played by fiction in our experience and apprehension of the world. Can fiction convey contents of knowledge or even constitute a source of ... [more ▼]

The thesis assembles five publications dealing with the role played by fiction in our experience and apprehension of the world. Can fiction convey contents of knowledge or even constitute a source of knowledge in itself? This question is broken down into a series of studies about the implicit sociology of American writer William S. Burroughs; industrial music as a critical device; the configuration power of Nineteen Eighty-Four in the denunciation of new technologies of surveillance and social control; the deep homology between power and narrativity; as well as counter-fiction within “societies of control”. The general introduction preceding these publications aims at building two examples of “fictional forms of intelligibility” conceived as cognitive and pragmatic resources used by members of society: “simulacrum”, which consists in criticising a target, in a systematically ironical mode, so as to turn its language and mode of functioning against it; “future perfect”, which proposes the anticipation of a threat described as having already occurred, in order to demonstrate the urgency in taking action to thwart it. The thesis defends a minimalist and holist conception of fictional knowledge: it is as a means at the service of the mimetic modelling of social and political processes that fiction activates a sense of possibilities and exerts a cognitive function. In this way, these collected works intend to give the first elements of a research programme in social and political sciences around power of and as a narrative. Narrative appears not only as an object, but especially as a tool for analyzing politics. [less ▲]

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See detailLa vie boursière du premier fond de placement en Europe : Robeco, 1933-2010.
Lurkin, Virginie ULg

Master's dissertation (2012)

Si les fonds communs de placement sont devenus au fil des ans un choix populaire chez les investisseurs qui sont désormais prêts à investir dans des actifs différents avec un seul véhicule d ... [more ▼]

Si les fonds communs de placement sont devenus au fil des ans un choix populaire chez les investisseurs qui sont désormais prêts à investir dans des actifs différents avec un seul véhicule d'investissement, le phénomène de gestion collective est loin d’être un phénomène récent. Les premiers signes de gestion collective apparaissent dès 1822 au Pays-Bas où le roi, King William 1, aurait initié la pratique d'un tel fond en 1822. Similaires véhicules de fonds communs de placement ont alors vus le jour les uns après les autres à travers l’Europe : en Suisse d’abord, puis en Ecosse, en Grande-Bretagne ou encore France. Il faudra attendre 1890 pour que l’idée fasse son chemin vers les États-Unis. Dans ce paysage de fonds de placement, ROBECO tient un rôle prépondérant puisqu’il s’agit du plus ancien fond de placement existant sur les marchés à nos jours. Ce travail de fin d’étude a pour objet l’étude financière de la SICAV Robeco, née à la suite d’une vague d’innovation financière et encore en activité aujourd’hui, soit presque quatre-vingt ans d’analyse. Les objectifs de ce mémoire sont multiples. Le premier objectif est de comprendre et détailler le fonctionnement de la SICAV ROBECO ainsi que le contexte historique dans lequel ROBECO s’est développé et a évolué au fil des années. Le second objectif est d’analyser l’évolution boursière et les rentabilités de cette SICAV emblématique, tout en considérant l’impact que celle‐ci a eu sur son époque et sur ses actionnaires. Le premier chapitre de ce mémoire détaille le contexte historique dans lequel ROBECO a vu le jour il y a de cela 80 ans, de même que l’organisation au sein de ROBECO. Le chapitre suivant est consacré à la présentation des bases de données dans lesquelles figurent respectivement l’historique des valeurs liquidatives du fond, les distributions de dividendes effectuées au fil des ans et la répartition du portefeuille entre les différentes classes d’actifs. Le troisième chapitre présente, quant à lui, l’évolution de la valeur liquidative de ROBECO tout au long des 80 années étudiées, en parallèle avec les événements politiques, économiques ou propres à la société qui ont pu les influencer. Dans ce chapitre, nous abordons dans en premier temps, les notions importantes de stationnarité et de rupture. Nous portons ensuite notre attention sur la distribution des returns avec l’analyse des quatre caractéristiques usuelles : moyenne, volatilité, Skewness et Kurtosis. Finalement, nous analyserons les grandes crises boursières ayant eu lieu durant ces années. Le quatrième chapitre est quant à lui destiné à la compréhension de la gestion du portefeuille entre les différentes classes d’actifs : cash, obligations (hollandaises-étrangères), actions (hollandaises-étrangères). Finalement, le dernier chapitre de ce mémoire est consacré à l’analyse de la politique de distribution des dividendes et à l’impact de celle‐ci sur la rentabilité pour les actionnaires. [less ▲]

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See detailSimplification du chargement aérodynamique sur une toiture de stade
Hamra, Lotfi ULg

Master's dissertation (2012)

The stochastic analysis of a structure subjected to turbulent wind gives estimation of the extreme (or peak) responses necessary for the structural design. These extreme values are established for each ... [more ▼]

The stochastic analysis of a structure subjected to turbulent wind gives estimation of the extreme (or peak) responses necessary for the structural design. These extreme values are established for each response within the structure (displacements, internal forces, reactions, etc ...). Notwithstanding, engineers from design office are used to design structures under static wind loads. The major challenge is thus to compute equivalent static loads that take into account the dynamic behavior of the structure and by simple static analyses, reconstruct the most accurately the extreme responses obtained from a stochastic dynamic analysis. Equivalent static wind loads are determined by applying various methods and the aim of this work is to extract a reduced basis, the principal static wind loads. These principal static wind loads are well suited for combinations in order to have a minimum number of design cases. Focus is made on the responses of the structure which are composed of mean, quasi-static and resonant contributions and on the number of design static wind loads to provide an accurate reconstruction of all extreme responses. [less ▲]

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See detailEvidence-Based Model Calibration for Efficient Building Energy Services
Bertagnolio, Stéphane ULg

Doctoral thesis (2012)

Energy services play a growing role in the control of energy consumption and the improvement of energy efficiency in non-residential buildings. Most of the energy use analyses involved in the energy ... [more ▼]

Energy services play a growing role in the control of energy consumption and the improvement of energy efficiency in non-residential buildings. Most of the energy use analyses involved in the energy efficiency service process require on-field measurements and energy use analysis. Today, while detailed on-field measurements and energy counting stay generally expensive and time-consuming, energy simulations are increasingly cheaper due to the continuous improvement of computer speed. This work consists in the development of a simulation-based approach dedicated to whole-building energy use analysis for use in the frame of an energy efficiency service process. Focus is given to the development of a new simplified dynamic hourly building energy simulation tool adapted to energy use analysis of existing buildings, its calibration by means of available energy use data and to the integration of the calibration process into the Energy Service Process. The proposed evidence-based calibration methodology is deeply related to on-field inspection and data collection issues and is developed to fit with the audit/inspection process. After calibration, the model can be used to support the other steps of the Energy Services Process, such as ECOs selection and evaluation and continuous performance verification. The new systematic calibration methodology gives priority to the physical identification of the model’s parameters (i.e. to the direct measurement) and relies on the notion of hierarchy among the source of information (as a function of their reliability) used to identify the value of the parameters. The improved Morris’ sensitivity analysis method is used for “factor fixing” (i.e. distinction between non-influential model’s parameters) and “parameters screening” (i.e. classification of influential parameters by order of importance) in order to orient the data collection work and guide the parameters adjustment process. At the end of the calibration process, the Latin Hypercube Monte Carlo sampling is used to quantify the uncertainty on the final outputs of the calibrated model. The developed simulation tool and the associated calibration method are applied to a synthetic case (“Virtual Calibration Test Bed”) and to real case study building located in Brussels, Belgium. Both applications (real and synthetic cases) allow highlighting the complexity and the limits of calibration as it is used today. Calibration remains a highly underdetermined problem and a compromise has to be found between data collection and modeling efforts and model’s requirements in order to proceed to efficient energy use analysis. At the end of these applications, it is believed that partially manual methods remain more efficient and the best quality assurance when proceeding to calibration of a building energy simulation model. The use of an evidence-based method ensures sticking to reality and avoids bad representation and hazardous adjustment of the parameters. Moreover, it is shown that the intensive use of a sensitivity analysis method is of a great help to orient data collection and parameters adjustment processes. Defining confidence/uncertainty ranges for each parameter, in addition to a “best-guess” value, also allowed quantifying the uncertainty on the final outputs of the model and helped the user in evaluating the quality of the calibrated model. [less ▲]

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See detailInvestigation on placental lactogen in bovine foetus
Alvarez Oxiley, Andrea Vivian ULg

Doctoral thesis (2012)

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See detailAnalyse moléculaire d'encres d'impression à des fins forensiques
Heudt, Laetitia ULg

Doctoral thesis (2012)

Document examination is a forensics field focused on the analysis of a disputed document. One way to analyze a document is to focus on the composition of the ink used or the materials from which documents ... [more ▼]

Document examination is a forensics field focused on the analysis of a disputed document. One way to analyze a document is to focus on the composition of the ink used or the materials from which documents are produced. Nowadays, three major classes of inks are studied: pen inks, inkjet printer inks, and toner. If the analysis of pen inks is already well developed in the literature and in the forensic lab, the analysis of inkjet printer inks is reported only to a limited degree and is principally focused on color inks. Fraudulent-minded people use more and more inkjet printer technology to produce falsified documents. So, it is a necessity to develop an analytical method for inkjet-printed document examination. Due to the particular chemical composition of these inks, different or more complicated analytical methods could and must be reviewed. Four analytical methods are evaluated in this thesis as possible tools for the analysis of inkjet-printed documents in terms of discriminating power, chemical information quality, and nondestructive capability: Raman spectroscopy and mass spectrometry coupled with Laser Desorption Ionization (LDI), Matrix Assisted Laser Desorption Ionization (MALDI), and Desorption ElectroSpray Ionization (DESI). The results obtained from two color inkjet printer cartridges (either fresh or printed) show that Raman spectroscopy and MALDI (9-aminoacridin as matrix) are the two most powerful methods for the analysis of color inkjet inks. Both methods have the advantage to perform analysis of inks directly on paper. The complementarity of the Raman spectroscopy and the MALDI-MS techniques is demonstrated based on the analysis of 10 different inkjet cartridges. The Raman method is a nondestructive approach while MALDI mass spectrometry has a better discrimination power and can also lead to information about some ink additives and paper composition. If it is necessary to determine the spatial distribution of one compound, then molecular imaging can be performed using Raman and (MA)LDI mass spectrometry. These techniques have been used successfully on a banknote or a stamp. Black inks are also under investigation in this work. The discrimination of black inkjet-printed documents is more difficult because of the common use of carbon black as the principal black pigment. LDI mass spectra recorded on black-printed inks give polyethylene glycol (PEG) peaks that are characteristics of a particular brand. Moreover, unknown characteristic peaks are detected in the low mass range of these spectra, giving additional information for discrimination of black inks. A software has been developed for a rapid and objective comparison of the low mass range of these positive mode LDI spectra. [less ▲]

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See detailContribution à la modélisation du séchage du maïs en lit-fixe
Janas, Sébastien ULg

Doctoral thesis (2012)

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See detailCaractérisation et valorisation des matériaux argileux de la Province de Kinshasa (RD Congo)
Wetshondo Osomba, Dominique ULg

Doctoral thesis (2012)

A la suite de la promulgation du Code Minier en juillet 2002, la quasi-totalité des investissements des sociétés minières nationales ou multinationales œuvrant en RD Congo est orientée vers les métaux de ... [more ▼]

A la suite de la promulgation du Code Minier en juillet 2002, la quasi-totalité des investissements des sociétés minières nationales ou multinationales œuvrant en RD Congo est orientée vers les métaux de base (Cu, Co, Sn, Mn,…) et les substances minérales précieuses (or, diamant, ...). La filière de la céramique pourtant très prometteuse et qui utilise, comme matières premières, les substances minérales industrielles compte parmi les secteurs les moins développés et/ou inexistants dans la majeure partie du pays. Dans une perspective de développement local durable, la présente étude a l’avantage de contribuer à la promotion des matériaux locaux de construction tout en améliorant la qualité des briques artisanales produites et à inciter la création des PME dans la filière de la céramique en RD Congo. Elle constitue donc un apport scientifique important dans la connaissance et la caractérisation des substances minérales industrielles de la RD Congo et plus particulièrement les matériaux argileux de Kinshasa et environs. Les connaissances scientifiques acquises sur les matériaux naturels et sur les produits fabriqués permettent de justifier l’emploi des matériaux du site pilote de Kasangulu dans la filière grossière de la céramique ou céramique de construction ; ceux du deuxième site pilote, Kingabwa, dans le secteur des réfractaires silico-alumineux et dans la branche de la céramique fine, traditionnelle et industrielle. En effet, les matériaux de Kasangulu et plus particulièrement les lithofaciès des couches 2 et 3 sont des produits silico-argileux plastiques qui constituent des ressources minérales industrielles de bonne qualité pour la fabrication des produits variés dont les briques stabilisées ou cuites (creuses, perforées, pleines et de parement), les hourdis et les tuiles. La présence de la goethite associée à l’oxyde de titane dans ces produits naturels apporte une plus-value considérable dans la teinture rougeâtre et/ou jaunâtre des produits finis. Les argiles de Kingabwa, que nous qualifions « d’argiles nobles », sont utilisables dans la fabrication des produits à plus haute valeur ajoutée comme les porcelaines. Néanmoins, les produits cuits de Kingabwa ont présenté un retrait à la cuisson de 9 à 12% pour de températures allant de 1100 à 1150°C et une perte en poids à la cuisson de l’ordre de 14% en moyenne. Pour une bonne rentabilité industrielle, ces retraits peuvent être minimisés par l’ajout d’une quantité optimale de dégraissant ou en revoyant à la hausse la température du séchage pendant l’élaboration des produits. Il a été montré que l’évolution de la résistance mécanique à la compression dans les briquettes cuites n’est pas totalement fonction de la porosité ou des retraits à la cuisson ni de la simple quantité de mullite formée. La fissuration de la pâte et le développement des fissures linéaires, surtout celles en cercles concentriques autour des cristaux influencent beaucoup cette propriété. Les ressources minérales étudiées présentent un avantage environnemental de taille pour leur emploi comme matières premières dans l’industrie céramique. En effet, ces substances sont très pauvres en matières organiques et ne contiennent pas des éléments tels que le soufre, la pyrite ou les carbonates. [less ▲]

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See detailBayesian Design Space applied to Pharmaceutical Development
Lebrun, Pierre ULg

Doctoral thesis (2012)

Given the guidelines such as the Q8 document published by the International Conference on Harmonization (ICH), that describe the “Quality by Design” paradigm for the Pharmaceutical Development, the aim of ... [more ▼]

Given the guidelines such as the Q8 document published by the International Conference on Harmonization (ICH), that describe the “Quality by Design” paradigm for the Pharmaceutical Development, the aim of this work is to provide a complete methodology addressing this problematic. As a result, various Design Spaces were obtained for different analytical methods and a manufacturing process. In Q8, Design Space has been defined as the “the multidimensional combination and interaction of input variables (e.g., material attributes) and process parameters that have been demonstrated to provide assurance of quality” for the analytical outputs or processes involved in Pharmaceutical Development. Q8 is thus clearly devoted to optimization strategies and robustness studies. In the beginning of this work, it was noted that existing statistical methodolo- gies in optimization context were limited as the predictive framework is based on mean response predictions. In such situations, the data and model uncertainties are generally completely ignored. This often leads to increase the risks of taking wrong decision or obtaining unreliable manufactured product. The reasons why it happens are also unidentified. The “assurance of quality” is clearly not addressed in this case. To improve the predictive nature of statistical models, the Bayesian statistical framework was used to facilitate the identification of the predictive distribution of new outputs, using numerical simulations or mathematical derivations when possi- ble. By use of the improved models in a risk-based environment, separation analytical methods such as the high performance liquid chromatography were studied. First, optimal solutions of separation of several compounds in mixtures were identified. Second, the robustness of the methods was simultaneously assessed thanks to the risk-based Design Space identification. The usefulness of the methodology was also demonstrated in the optimization of the separation of subsets of relevant compounds, without additional experiments. The high guarantee of quality of the optimized methods allowed easing their use for their very purpose, i.e., the tracing of compounds and their quantification. Transfer of robust methods to high-end equipments was also simplified. In parallel, one sub-objective was the total automation of analytical method de- velopment and validation. Some data treatments including the Independent Com- ponent Analysis and clustering methodologies were found more than promising to provide accurate automated results. Next, the Design Space methodology was applied to a small-scale spray-dryer manufacturing process. It also allowed the expression of guarantees about the quality of the obtained powder. Finally, other predictive models including mixed-effects models were used for the validation of analytical and bio-analytical quantitative methods. [less ▲]

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See detailHow does the organizational context influence the Competitive Intelligence process among Walloon SMEs?
Gretry, Anaïs ULg

Master's dissertation (2012)

In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by ... [more ▼]

In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by which organizations gather information on competitors and the competitive environment [...]” (Wright, Eid & Fleisher, 2009, p.942), can contribute to do so by enabling managers to be aware of and respond to changes in their competitive environment. The CI process includes four steps: (a) planning and focus, (b) data collection, (c) data analysis and (d) communication. First, this paper assesses the level of deployment of CI among Walloon SMEs. Second, it examines the influence of context variables on the CI process. A questionnaire was distributed to 423 Walloon SMEs’ executives, of whom 81 answered. SMEs’ executives were surveyed about their companies’ CI practices as well as their perception of their company’s formal structure, employee involvement and organizational awareness. We found that Walloon SMEs are not very active to conduct CI effectively. Indeed, while Walloon SMEs have recognized that, theoretically, CI is a necessary activity for maintaining a competitive advantage, in practice, most of them do not have yet a well-established CI process in their company. Then, we established the influence of the context in which CI takes place on the success of the CI process. Specifically, we supported that better formal structure, employee involvement and organizational awareness improve the CI process. Finally, we examined the impact of two extra potential antecedents, namely the innovation orientation and the company’s size. We found that innovation-oriented companies tend to exploit CI more than followers. The results lead to several recommendations for SMEs. First, managers should be aware that CI is critical for their company’s survival since the context in which they operate is increasingly competitive. Second, businesses, especially those that are innovation-oriented, should note that an improvement in their formal infrastructure, organizational awareness and employee involvement processes could significantly enhance their CI efficiency. [less ▲]

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See detailInventaire électronique d'une série du fonds Nicolas Leclerc : l'église Saint-Jacques de Liège, conservé au Centre de Documentation et d'Archivage du Groupe d'Ateliers de Recherche asbl
Libois, Philippine ULg

Master's dissertation (2012)

This degree-conferring dissertation, intended for the 'Groupe d'Ateliers de Recherche asbl' in Liège, includes a catalogue of one part from the Nicolas Leclerc fund, kept in this same institution. Nicolas ... [more ▼]

This degree-conferring dissertation, intended for the 'Groupe d'Ateliers de Recherche asbl' in Liège, includes a catalogue of one part from the Nicolas Leclerc fund, kept in this same institution. Nicolas Leclerc was an architect in Liège and its area from the 1950's until his death in 1978. The treated part of the fund consists of 20 files over the restorations on the church of Saint James in Liège, led by Nicolas Leclerc; they contain his correspondences, plans and other personal documents. The first part of this work consists in the encoding of the entries created for every element of the 20 concerned files, in a Microsoft Access database. The second part consists in a history of the church of Saint James in Liège, with an emphasis on the diverse restorations and reparations carried out on this building. It is accompanied by a selective bibliography of the books on this church. [less ▲]

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See detailCreation of model proteins to investigate the mechanism of aggregation of expanded-polyglutamine proteins. Insertion of polyglutamine tracts into the ß-lactamase BlaP
Scarafone, Natacha ULg

Doctoral thesis (2012)

Polyglutamine (polyQ) diseases are characterized by the formation of intranuclear amyloid-like aggregates by proteins containing an expansion of a polyQ tract above a threshold length. These insoluble ... [more ▼]

Polyglutamine (polyQ) diseases are characterized by the formation of intranuclear amyloid-like aggregates by proteins containing an expansion of a polyQ tract above a threshold length. These insoluble aggregates and/or some of their soluble precursors are thought to play a role in the pathogenesis of the diseases. The only known common point between the causative proteins is the expanded polyQ tract, suggesting that their aggregation critically depends on the expansion of the polyQ tract above a threshold length. Several studies have however shown that the non-polyQ regions can also influence the aggregation behavior of polyQ proteins. In this work, polyQ chimeras were created by inserting different polyQ lengths in two positions (197-198 and 216-217) of the β-lactamase BlaP from Bacillus licheniformis 749/C. The structural and thermodynamic properties of the polyQ chimeras as well as their aggregating properties under native and denaturing conditions were investigated using a range of biophysical techniques including fluorescence, circular dichroism, absorbance, x-ray fiber diffraction and transmission electron microscopy. We have first created and characterized chimeras with 23, 30, 55 and 79Q inserted in position 197-198 (chimeras 197-198). None of these insertions modifies the structure of BlaP; they do, however, significantly destabilize the enzyme by 7.6-8.8 kJ/mol independently of the polyQ length. Similarly to the proteins associated with diseases, there is a threshold number of glutamines above which the BlaP chimeras aggregate into amyloid-like fibrils. It is comprised between 55 and 79Q and between 30 and 55Q under native and denaturing conditions, respectively. This threshold value therefore depends on the structural integrity of BlaP and thus on the steric and/or conformational constraints applied by BlaP to the polyQ tract. We have then compared the properties of these chimeras with those of the chimeras containing polyQ of the same lengths in position 216-217 (chimeras 216-217). The tertiary structure of BlaP is slightly perturbed in the chimeras 216-217 and these chimeras are less stable than the chimeras 197-198. However, the urea-induced equilibrium unfolding experiments suggest that chimeras 216-217 populate a series of discrete intermediate states between the native and unfolded states or that their unfolded state significantly differs from that of chimeras 197-198. Finally, the aggregating properties of the polyQ chimeras 216-217 differ from those of chimeras 197-198. First, the threshold number of glutamines above which chimeras 216-217 readily form fibrils under native conditions (between 30 and 55Q) is lower than that observed for chimeras 197-198 (between 55 and 79Q) suggesting that the steric and/or conformational constraints imposed on the polyQ tract are lower when it is inserted in position 216-217. Secondly, the results obtained under both native and denaturing conditions indicate that the BlaP moiety could assist fibril formation by chimeras 216-217 while it has an inhibiting effect and no effect on fibril formation by the chimeras 197-198 with 55 and 79 glutamines, respectively. Taken together, these results show that the aggregating properties of BlaP chimeras result from a very complex interplay between the propensity of the polyQ tract to mediate fibril formation and the modulating effect of the BlaP moiety. BlaP chimeras present therefore valuable models to investigate in details how the properties of the host protein influence the aggregation behavior of expanded polyQ proteins. [less ▲]

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