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See detailContribution à l’élaboration d’un espace commun de représentation pour l’analyse morpho-fonctionnelle du membre supérieur : application à l’articulation glénohumérale
Schwartz, Cédric ULg

Doctoral thesis (2009)

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion ... [more ▼]

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion analysis systems provide dynamic measures. However, these measures may be distorted by the presence of soft tissues between the bones and the skin surface. First, we study a new method for correcting soft tissues artifacts when using external markers for motion estimation. This method is based on a surfacic approach and aims to follow the deformation created by the scapula on the skin surface. A robust registration algorithm, called IMCP, is used. This algorithm, developed in previous works, has been modified and adapted to be more specific to the study context: motion analysis using external markers. The improvements concern post-processing so as to make the most of the information mutualization properties of the IMCP, a way to take into account the influence of the edges of the markers clusters, and finally the optimization of the processing time thanks to multi-threading developments. In a second time, a specific MRI protocol is developed in order to allow morpho-functional analysis. Moreover, articular coherence indicators are proposed for the glenohumeral joint. These indicators are adapted to the case of errors in motion estimation. The results show that the use of a markers cluster covering all the scapula do not allow to follow the scapula print at skin surface. Thanks to simulation studies, two hypotheses are proposed to explain these results: the noise created by the soft tissues is too significant, and / or the available skin resolution is not sufficient. The relevance of proposing markerless analysis is so emphasized. Our morpho-functional study on the glenohumeral joint shows the significant influence of the motion analysis protocol on joint coherence during bones animation. The placement of the markers on the scapula and on the humerus as well as the choice of the motion estimation algorithm have a large influence on the bony structures motion estimation. [less ▲]

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See detailEnvironmental Changes and Migration Flows. Normative Frameworks and Policy Responses.
Gemenne, François ULg

Doctoral thesis (2009)

Depuis quelques années, d’importants déplacements de populations sont régulièrement annoncés comme l’une des conséquences les plus dramatiques du changement climatique. Plusieurs dizaines de ... [more ▼]

Depuis quelques années, d’importants déplacements de populations sont régulièrement annoncés comme l’une des conséquences les plus dramatiques du changement climatique. Plusieurs dizaines de millions de personnes pourraient ainsi être contraintes à l’exil en raison des impacts du réchauffement global, selon les estimations les plus alarmistes. Ces prédictions, pourtant, relèvent d’une logique largement déterministe, qui simplifie souvent la relation entre dégradation environnementale et migrations à une causalité directe, et néglige l’importance des cadres normatifs. Cette thèse prend le contre-pied de l’approche déterministe dominante, et soutient que l’ampleur et la nature de ces flux migratoires ne dépendent pas uniquement des impacts du changement climatique, mais également – et surtout – des politiques qui seront mises en place pour limiter ces impacts et encadrer ces migrations. Elle adopte une posture constructiviste, et s’interroge sur la manière dont les réponses politiques apportées jusqu’ici aux mouvements de population provoqués par des dégradations environnementales influencent la conceptualisation du phénomène de ‘migrations environnementales’. Afin d’analyser le processus politique de mise en place de cadres normatifs et de réponses politiques en place au niveau international, la thèse utilise le modèle théorique de l’Advocacy Coalition Framework (ACF), mis au point par Sabatier et Jenkins-Smith. Dans un premier temps, la thèse analyse l’émergence du concept de ‘migrations environnementales’ dans la littérature et à l’agenda politique. La littérature sur le sujet est traversée par une opposition entre deux courants de pensée, que j’ai qualifiés respectivement de ‘sceptique’ et d’ ‘alarmiste’. Le courant sceptique, composé essentiellement de spécialistes des migrations, soutient que toute migration est multi-causale, et que l’environnement n’est pas un facteur migratoire plus déterminant qu’un autre. Ainsi, les sceptiques estiment que le concept de ‘migration environnementale’, considéré comme un type spécifique de migration, n’a guère de sens. A l’inverse, les alarmistes, qui sont essentiellement des spécialistes de l’environnement, affirment que les dégradations de l’environnement constituent un facteur croissant de migrations forcées, qui ont déjà commencé. Ces deux courants de pensée, qui trouvent leur origine dans un fossé disciplinaire, peuvent être analysés comme de véritables coalitions, qui pénètrent le processus politique. Le rôle des chercheurs dans la définition des politiques publiques est dès lors mis en avant, et la thèse émet l’hypothèse que cette opposition entre ‘alarmistes’ et ‘sceptiques’ a dépassé le champ académique pour traverser également le champ politique. La thèse entreprend alors de décrire et d’analyser le développement de normes et de politiques s’appliquant aux déplacements de populations liés à des dégradations de l’environnement dans deux sphères politiques distinctes : les politiques environnementales d’une part, et migratoires d’autre part. Dans les politiques environnementales, la thèse examine en particulier la gestion des catastrophes naturelles au niveau international, et les questions d’adaptation dans les négociations sur un nouveau traité international sur le changement climatique. Le domaine de la gestion des catastrophes naturelles s’est considérablement transformé au cours des dernières, et les personnes déplacées par les catastrophes sont au centre de plusieurs débats, ateliers et recommandations. Pour autant, ce sont négociations sur le changement climatique qui sont devenues, au fil des ans, le réceptacle premier des discussions et revendications sur les ‘migrations climatiques’. Les politiques migratoires, par contre, ont évolué dans un sens très différent. Le régime international de l’asile n’a guère évolué depuis la Convention de Genève de 1951 et son Protocole additionnel de 1967, et n’a guère pris en charge les nouvelles configurations des migrations forcées dans le monde, comme l’importance croissante aux dégradations de l’environnement. Les politiques d’asile et de mobilité n’ont pas non plus véritablement intégré la question, se cantonnant à des formes de protection complémentaires et/ou non contraignantes, dont pourraient se prévaloir ceux qui sont déplacés par une catastrophe naturelle. La thèse cherche à expliquer cette évolution différente par les différentes coalitions qui dominent ces sphères politique : les politiques migratoires sont dominées par les sceptiques, tandis que les politiques environnementales sont dominées par les alarmistes. Depuis le milieu des années 2000, les alarmistes dominent les débats sur les migrations environnementales, et ces débats se sont dès lors déplacés dans la sphère des politiques environnementales, et plus particulièrement dans celles des négociations sur le futur régime climatique. L’apparente réconciliation récente entre les deux coalitions marquent en réalité un glissement vers le terrain des politiques environnementales. Ce glissement révèle que le phénomène de ‘migrations environnementales’ reste largement conceptualisé de manière déterministe, et comme une migration forcée, inéluctable conséquence de l’échec de l’adaptation. Or, des illustrations empiriques, provenant de terrains effectués à La Nouvelle-Orléans après l’ouragan Katrina et à l’archipel de Tuvalu menacé par la montée des eaux, démontrent que cette conceptualisation ne correspond pas à la réalité des flux migratoires liés à des changements de l’environnement. La thèse souligne donc le caractère socialement construit des migrations environnementales, et l’importance du rôle joué par les politiques publiques. [less ▲]

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See detailBiogeochemical study of coccolithophorid blooms in the context of climate change
Harlay, Jérôme ULg

Doctoral thesis (2009)

Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania ... [more ▼]

Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania huxleyi, are mainly found in the sub-polar and temperate oceans, where they produce huge blooms visible from space. Coccolithophores are sensitive to ocean acidification that results from the ongoing accumulation of anthropogenic carbon dioxide (CO2) in the atmosphere. The response of these organisms to global change appears to be related to the reduction of their ability to produce calcium carbonate at the cellular level. At the community levels, one anticipates changes in the carbon fluxes associated to their blooms as calcification is reduced. However, the consequences of such environmental changes on this species are speculative and require improvements in the description of the mechanisms controlling the organic and inorganic carbon production and export. The first aspect of this work was to study the response of these organisms to artificially modified CO2 concentrations representative of the conditions occurring in the past (glacial) and those expected by the end of the century (2100). Two different levels were examined: the continuous monospecific cultures (chemostats) allowed us to work at the cellular level while the mesocosms gave light to the mechanisms taking place in an isolated fraction of the natural community. The second aspect of this work consisted of field studies carried out during four cruises (2002, 2003, 2004 and 2006) in the northern Bay of Biscay, where the occurrence of E. huxleyi blooms were observed in late spring. I describe the vertical profiles of biogeochemical variables (nutrients, chlorophyll-a, dissolved inorganic carbon chemistry, particulate carbon, transparent exopolymer particles (TEP)) and study processes such as primary production, calcification and bacterial production. The properties of these blooms are compared with those reported in the literature and enriched with original measurements such as the abundance and concentration of TEP that could play an important role in carbon export to the deep ocean, modifying the properties of the settling ballasted aggregates. [less ▲]

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See detailDépistage Néonatal de la Drépanocytose: Nouvelles Méthodologies
BOEMER, François ULg

Doctoral thesis (2009)

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See detailMéthode de Perturbation pour la Modélisation par Éléments Finis des Systèmes Électrostatiques en Mouvement - Application aux MEMS Électrostatiques
Boutaayamou, Mohamed ULg

Doctoral thesis (2009)

La modélisation par éléments finis des conducteurs en mouvement nécessite généralement des calculs successifs et le remalliage de certaines régions. Une modélisation 3D de géométries complexes par les ... [more ▼]

La modélisation par éléments finis des conducteurs en mouvement nécessite généralement des calculs successifs et le remalliage de certaines régions. Une modélisation 3D de géométries complexes par les techniques classiques nécessite dès lors de gros efforts en terme de temps de calcul. Dans cette thèse, une méthode originale basée sur une approche par sous-problèmes, appelée méthode de perturbation, a été développée. Utilisant la méthode des éléments finis, cette technique consiste à subdiviser un problème entier en sous-problèmes. La complexité du problème initial est par conséquent diminuée en ne se concentrant que sur les zones les plus pertinentes. Appliquée aux systèmes en mouvement, la méthode de perturbation permet d'exploiter les résolutions antérieures au lieu d'effectuer un nouveau calcul pour chaque position. L'analyse par la méthode de perturbation des microsystèmes électromécaniques (MEMS) électrostatiques comprenant des parties en déplacement ou en déformation est en outre considérée dans ce travail. Il est notamment question de démontrer l'implication naturelle de cette approche pour des simulations plus efficaces et plus précises des MEMS électrostatiques. [less ▲]

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See detailContribution à l'étude de la pathologie pleurale maligne.
DUYSINX, Bernard ULg

Doctoral thesis (2009)

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See detailEtude moléculaire des short-chain isoprényle diphosphate synthases chez les pucerons : Evaluation de leur potentiel d’utilisation comme cible de nouveaux bio-insecticides
Vandermoten, Sophie ULg

Doctoral thesis (2009)

Les pucerons sont considérés comme des ravageurs majeurs, d’une part en raison de leur action directe sur le végétal, mais également en tant que vecteurs de nombreux virus phytopathogènes. A l’heure ... [more ▼]

Les pucerons sont considérés comme des ravageurs majeurs, d’une part en raison de leur action directe sur le végétal, mais également en tant que vecteurs de nombreux virus phytopathogènes. A l’heure actuelle, la lutte contre certaines espèces de pucerons, au moyen d’insecticides de synthèse, devient extrêmement difficile en raison de l’apparition de populations résistantes. Le développement de nouveaux produits antiparasitaires, visant spécifiquement les pucerons, devient, par conséquent, hautement souhaitable. Dans ce contexte, nous avons choisi de nous intéresser aux enzymes de la famille des « short-chain » isoprényle diphosphate synthases (scIPPS). Ces enzymes constituent une classe de prényltransférases impliquées dans le métabolisme des isoprénoïdes. Cette classe comprend la géranyle diphosphate synthase, la farnésyle diphosphate synthase et la géranylgéranyle diphosphate synthase qui respectivement synthétise le géranyle diphosphate (GPP, C10), le farnésyle diphosphate (FPP, C15), et le géranylgéranyle diphosphate (GGPP, C20). Nous avons cloné chez le puceron un nouveau type de scIPPS. Contrairement à d'autres scIPPS connues, l’enzyme recombinante du puceron affiche une activité bifonctionnelle ; cette dernière étant capable de synthétiser à la fois le GPP, le précurseur commun des monoterpènes, mais également le FPP, le précurseur des sesquiterpènes. Chez les pucerons, ces deux précurseurs sont supposés jouer un rôle clé dans la biosynthèse de l'hormone juvénile et des phéromones d'alarme et sexuelle. Dans le but de fournir une explication structurelle à la bifonctionnalité observée chez la GPP/FPP synthase de puceron, nous avons entrepris de résoudre sa structure tridimensionnelle en se basant sur les structures cristallographiques du poulet. Plusieurs mutants ont été ensuite conçus et caractérisés. [less ▲]

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See detailModélisation et résolution du problème de contact mécanique et son application dans un contexte multiphysique
Bussetta, Philippe ULg

Doctoral thesis (2009)

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non ... [more ▼]

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non differentiability of the contact's equations (stick/unstick and the initiation of sliding). Until now, no method could be used to resolve all contact problems. This work is focused on the methods of calculation of the mechanical contact in a more general way. It could be separated in two parts. The first one concerns the creation of the systems of equations and the algorithm of resolution. The methods more used are the Penalty Method and Lagrangian Augmented Method. Although these methods are simple, they are very difficult to use because the choice of the value of penalty coefficients (normal and tangential). For this reason, a new method, the "Lagrangian Augmented Adapted Method" is proposed. This new method is based on the Lagrangian Augmented Method and on the adaptation of the penalty coefficients. With it, the user does not need to choose the value of penalty coefficients. In addition, this method has the speed of the Penalty Method and the reliability of the Lagrangian Augmented Method. The second part of this work deals with the calculation of the mechanical contact under a spatial disctretization. The method more used is the "Point-Surface" Method. The contact is calculated between every point of one surface and the other surface. This method has many limits, as the representativeness and the regularity of the solution when the boundaries are deformable and irregular. Many researches are done on another method, the "Surface-Surface" Method based on the Mortar Element Method. The mechanical contact is calculated on each node of one surface in function of the two surfaces. With this method the solution is more regular and reliable. But the calculation of the mechanical contact is more difficult, so it can not be used to the three dimensional problems. An adaptation of this method has been proposed to the two and three dimensional problems. All these methods are tested on some academics and industrials multi-physical problems. [less ▲]

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See detailSolute transport modelling at the groundwater body scale: Nitrate trends assessment in the Geer basin (Belgium)
Orban, Philippe ULg

Doctoral thesis (2009)

Water resources management is now recognized as a multidisciplinary task that has to be performed in an integrated way, within the natural boundaries of the hydrological basin or of the aquifers. Policy ... [more ▼]

Water resources management is now recognized as a multidisciplinary task that has to be performed in an integrated way, within the natural boundaries of the hydrological basin or of the aquifers. Policy makers and water managers express a need to have tools able at this regional scale to help in the management of the water resources. Until now, few methodologies and tools were available to assess and model the fate of diffuse contaminants in groundwater at the regional scale. In this context, the objective of this research was to develop a pragmatic tool to assess and to model groundwater flow and solute transport at the regional scale. A general methodology including the acquisition and the management of data and a new flexible numerical approach was developed. This numerical approach called Hybrid Finite Element Mixing Cell (HFEMC) was implemented in the SUFT3D simulator developed by the Hydrogeology Group of the University of Liège. A first application of this methodology was performed on the Geer basin. The chalk aquifer of the Geer basin is an important resource of groundwater for the city of Liège and its suburbs. The quality of this groundwater resource is threatened by diffuse nitrate contamination mostly resulting from agricultural practices. New field investigations were performed in the basin to better understand the spatial distribution of the nitrate contamination. Samples were taken for environmental tracers (tritium, CFC’s and SF6) analysis. The spatial distribution of environmental tracers concentrations is in concordance with the spatial distribution of nitrates. This allows proposing a coherent interpretative schema of the groundwater flow and solute transport at the regional scale. These new data and the results of a statistical nitrate trend analysis were used to calibrate the groundwater model developed with the HFEMC approach. This groundwater flow and solute transport model was used to forecast the evolution of nitrate concentrations in groundwater under a realistic scenario of nitrate input for the period 2008-2058. According to the modelling results, upward nitrate trends observed in the basin will not be reversed for 2015 as prescribed by the EU Water Framework Directive. The regional scale groundwater solute transport model was subsequently used to compute nitrate concentrations in groundwater under different scenarios of nitrate input to feed a socio-economic analysis performed by BRGM. These computed concentrations were used to assess the benefit, for the users, linked to the reduction of contamination resulting from the changes in nitrate input. These benefits were compared to the costs associated to the implementation of the considered agri-environmental schemes that allow reducing the nitrate input to groundwater. [less ▲]

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See detailGeometry and Symmetries in Coordination Control
Sarlette, Alain ULg

Doctoral thesis (2009)

The present dissertation studies specific issues related to the coordination of a set of “agents” evolving on a nonlinear manifold, more particularly a homogeneous manifold or a Lie group. The viewpoint is ... [more ▼]

The present dissertation studies specific issues related to the coordination of a set of “agents” evolving on a nonlinear manifold, more particularly a homogeneous manifold or a Lie group. The viewpoint is somewhere between control algorithm design and system analysis, as algorithms are derived from simple principles — often retrieving existing models — to highlight specific behaviors. With a fair amount of approximation, the objective of the dissertation can be summarized by the following question: Given a swarm of identical agents evolving on a nonlinear, nonconvex configuration space with high symmetry, how can you define specific collective behavior, and how can you design individual agent control laws to get a collective behavior, without introducing hierarchy nor external reference points that would break the symmetry of the configuration space? Maintaining the basic symmetries of the coordination problem lies at the heart of the contributions. The main focus is on the global geometric invariance of the configuration space. This contrasts with most existing work on coordination, where either the agents evolve on vector spaces — which, to some extent, can cover local behavior on manifolds — or coordination is coupled to external reference tracking such that the reference can serve as a beacon around which the geometry is distorted towards vector space-like properties. A second, more standard symmetry is to treat all agents identically. Another basic ingredient of the coordination problem that has important implications in this dissertation is the reduced agent interconnectivity: each agent only gets information from a limited set of other agents, which can be varying. In order to focus on issues related to geometry / symmetry and reduced interconnectivity, individual agent dynamics are drastically simplified to simple integrators. This is justified at a “planning” level. Making the step towards realistic dynamics is illustrated for the specific case of rigid body attitude synchronization. The main contributions of this dissertation are I. an extensive study of synchronization on the circle, (a) highlighting difficulties encountered for coordination and (b) proposing simple strategies to overcome these difficulties; II. (a) a geometric definition and related control law for “consensus” configurations on compact homogeneous manifolds, of which synchronization — all agents at the same point — is a special case, and (b) control laws to (almost) globally reach synchronization and “balancing”, its opposite, under general interconnectivity conditions; III. several propositions for rigid body attitude synchronization under mechanical dynamics; IV. a geometric framework for “coordinated motion” on Lie groups, (a) giving a geometric definition of coordinated motion and investigating its implications, and (b) providing systematic methods to design control laws for coordinated motion. Examples treated for illustration of the theoretical concepts are the circle S^1 (sometimes the sphere S^n ), the rotation group SO(n), the rigid-body motion groups SE(2) and SE(3) and the Grassmann manifolds Grass(p,n). The developments in this dissertation remain at a rather theoretical level; potential applications are briefly discussed. [less ▲]

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See detailSOURCES DE VARIATION PHÉNOTYPIQUE DES TRAITS D’HISTOIRE DE VIE D’UNE ESPÈCE INVASIVE, SENECIO INAEQUIDENS DC. (ASTERACEAE).
Monty, Arnaud ULg

Doctoral thesis (2009)

L’importance des différentes sources de variation phénotypique que sont l’adaptation, la plasticité phénotypique, les effets maternels environnementaux, le niveau de ploïdie et la dérive génétique, a été ... [more ▼]

L’importance des différentes sources de variation phénotypique que sont l’adaptation, la plasticité phénotypique, les effets maternels environnementaux, le niveau de ploïdie et la dérive génétique, a été analysée pour différents traits d’histoire de vie, au sein de l’aire colonisée par une espèce végétale invasive. A cette fin, plusieurs expériences en jardins communs ont été installées, dont deux en transplantations réciproques. Les populations considérées étaient localisées en Belgique, en France, ainsi que dans l’aire d’indigénat de l’espèce. Senecio inaequidens DC. (Asteraceae), l’espèce étudiée dans ce travail, est une plante d’origine africaine accidentellement introduite en Europe par le commerce lainier, vers la fin du 19ème siècle. Dans son aire d’indigénat, elle présente deux niveaux de ploïdie, diploïde et tétraploïde. Seuls des plants tétraploïdes sont recensés en Europe. L’espèce présente un historique de colonisation particulier, bien documenté, qui en fait un modèle idéal pour les études évolutives. Les traits d’histoire de vie considérés ont été scindés en deux groupes. Les premiers concernaient la germination, la croissance et la reproduction sexuée. Les sources de variation phénotypique dans ces traits ont été principalement analysées en relation avec les variations climatiques dans l’aire d’invasion, le long de gradients d’altitude, ainsi qu’en relation avec le niveau de ploïdie et l’aire d’origine (aire d’indigénat vs aire d’invasion). Le deuxième groupe de traits considérés concernaient les capacités de dispersion de l’espèce. Celles-ci ont été modélisées. La variabilité phénotypique dans ces traits a ensuite été analysée, parmi les populations françaises, en relation avec l’éloignement depuis le site de première introduction. Les résultats ont montré des différences entre les cytotypes de l’espèce, principalement dans les capacités de survie hivernale. Le long des gradients d’altitude, les populations de S. inaequidens présentaient des différenciations phénotypiques de type clinal, dans les traits de croissance. Ces différenciations étaient d’origine génétique, même si les effets maternels environnementaux sont apparus comme des sources non-négligeables de variation phénotypique dans les zones à climat rigoureux. Parmi les traits liés à la dispersion, le plume loading était le mieux corrélé aux capacités de dispersion par le vent. Des différenciations clinales ont été détectées dans les traits de dispersion, en jardin commun, mais n’ont pas été vérifiées en populations naturelles. [less ▲]

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See detailCrucial role of reversible phosphorylation in the mechanisms governing the biological functions of class IIa Histone Deacetylases
Martin, Maud ULg

Doctoral thesis (2009)

Regulation of class IIa histone deacetylases (HDACs) phosphorylation is crucial because it provides the opportunity to control important developmental processes associated with these key enzymes. Indeed ... [more ▼]

Regulation of class IIa histone deacetylases (HDACs) phosphorylation is crucial because it provides the opportunity to control important developmental processes associated with these key enzymes. Indeed, the transcriptional repressor activity of class IIa HDAC is controlled via their phosphorylation-dependent nucleo-cytoplasmic shuttling. While a lot of efforts have been directed towards the identification of the inactivating kinases that phosphorylate class IIa HDACs, the identity of the antagonist phosphatase remained an open question. During this work, we found that protein phosphatase 2A (PP2A) is responsible for dephosphorylating the class IIa HDACs member HDAC7, thereby regulating its subcellular localization and repressor activity. In order to validate our model, functional consequences of these findings was illustrated during the two main biological processes involving HDAC7, i.e. T-cells apoptosis during negative selection and endothelial cells angiogenic activities during vascular network formation. Cellular PP2A represents a large population of trimeric holoenzymes containing a variable regulatory subunit, whose identity has a crucial role in determining the specificity of PP2A catalytic activity. In an effort to characterize the regulation of HDAC7 dephopshorylation, we identified the relevant PP2A holoenzyme regulating HDAC7 function during vasculogenesis and we found that, among diverse regulatory subunit isoforms, PP2A-Bα uniquely regulates endothelial cell angiogenic properties. PP2A-Bα silencing using small interfering RNAs results in a significant inhibition of endothelial cell tube formation and migration. These results establish PP2A, and more precisely the Bα containg PP2A holoenzyme, as an essential element in the regulation of the class IIa HDACs HDAC7 and unravel a first developmental function for the PP2A regulatory subunit Bα in the genesis of blood vessels. [less ▲]

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See detailAgronomical and molecular factors influencing bananas (Musa acuminata, AAA, cv ‘Grande-Naine’) susceptibility to crown rot disease
Lassois, Ludivine ULg

Doctoral thesis (2009)

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An ... [more ▼]

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An original approach of the disease is proposed and consists on presenting the fruit quality potential at harvest as a key factor in crown rot development. This potential develops during growth of bananas in the field and depends on a physiological and a parasitical component. The physiological component refers here to the level of fruit susceptibility to crown rot and reflects the physiological state of the fruit. The aim of this study was to clarify the role of the fruit physiological component at harvest in the post-harvest crown rot development. It appears that the fruit physiological component at harvest greatly influence the postharvest disease development and thus the fruit susceptibility. Seasonal variations in disease severity were shown in two production area and are related to a variation of the fruit physiological component. In Guadeloupian conditions, the internal necrotic surface of the crown was nearly multiplied by 4 during 11 successive weeks. Two pre-harvest factors that could influence the fruit physiological component by modifying their susceptibility to crown rot, were identified: (i) hand position on the bunch and (ii) source-sink ratio of the banana plant (hand considered as sink and leaves as source). It was shown that within a bunch, there is a gradient of susceptibility to crown rot (r= -0.95), the hands initiated first (the upper ones) being more susceptible than those initiated last (the lower ones). These results also confirmed that source-sink ratio changes have a significant effect on fruit morphology and demonstrated that there is also an effect on fruit susceptibility to crown rot disease. When the sink is decreased by artificial removal of many hands, the level of fruit susceptibility to crown rot decreases. However, the molecular mechanisms underlying these quantitative host-pathogen relationships were still unknown. A study was designed to compare gene expression, by cDNA-AFLP, between crowns of bananas showing a high susceptibility (S+) and crowns of bananas showing a low susceptibility (S-) to Colletotrichum musae responsible for crown rot disease. This comparison was performed at two situation time: (i) between crowns (S+ and S-) collected one hour before infection and (ii) between crowns (S+ and S-) collected 13 days after infection. Genes implied in signaling pathway and proteolytic machinery were identified. It also appears that a cellulose synthase, a CAF1 gene, 2 glycolipid transfer protein and a dopamine-β-monooxygenase were differently expressed between bananas showing different levels of susceptibility. This is the first study of the characterization of the banana physiological component at harvest which influences the crown rot post-harvest disease development. In addition, to our knowledge, this work is the first to address both pre- and post-infection gene expression with the same host-pathogen combination and different susceptibility levels. [less ▲]

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See detailAlgebraic approach to modal extensions of Łukasiewicz logics
Teheux, Bruno ULg

Doctoral thesis (2009)

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See detailEtude du rôle des macrophages interstitiels dans l'allergie des voies respiratoires
Bedoret, Denis ULg

Doctoral thesis (2009)

Respiratory mucosal surfaces are constantly exposed to a broad range of non-pathogenic environmental antigens. In the absence of proinflammatory signals, inhalation of harmless antigens results in ... [more ▼]

Respiratory mucosal surfaces are constantly exposed to a broad range of non-pathogenic environmental antigens. In the absence of proinflammatory signals, inhalation of harmless antigens results in immunological tolerance. Indeed, lung dendritic cells stimulate the development of antigen-specific regulatory T cells. Nevertheless, epidemiological studies have shown that ambient air contains not only inert antigens but also immunostimulatory molecules of microbial origin. Of particular interest are endotoxins, a cell wall component of gram-negative bacteria that is ubiquitous in the environment. In spite of the fact that high levels of endotoxin exposure in early life protect against allergic sensitization, most evidence indicates that exposure to house-dust endotoxin is a significant risk factor for increased asthma prevalence and severity. When the respiratory tract is stimulated with airborne endotoxins, lung dendritic cells lose their tolerogenic properties and rather promote the development of an allergic response directed against concomitant aeroantigens. Although endotoxins are omnipresent in the environment and favour airway allergy, only a minority of people develops asthma. A unifying model reconciling these conflicting observations is still lacking. We report here that LPS-triggered airway allergy is tightly controlled by lung interstitial macrophages, a cell population that remains largely uncharacterized. Interstitial macrophages could be distinguished from alveolar macrophages by their unique capacity to inhibit lung dendritic cell maturation and migration upon LPS stimulation, thereby preventing sensitization to concomitant inhaled antigens. We furthermore demonstrated that functional paralysis of LPS-stimulated dendritic cells involves interleukin-10 production by interstitial macrophages. Finally, we demonstrate that specific in vivo elimination of interstitial macrophages leads to overt asthmatic reactions to innocuous airborne antigens inhaled along with low LPS doses. Our study thus reveals a crucial role for interstitial macrophages in maintaining immune homeostasis in the respiratory tract and provides an explanation for the paradox that airborne LPS has the ability to promote the induction of Th2 responses by lung dendritic cells but does not provoke airway allergy under normal conditions. In the presence of LPS, interstitial macrophages, but not alveolar macrophages, break the link between innate and adaptive immunity, allowing harmless inhaled antigens to escape from T cell-dependent responses. [less ▲]

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See detailLes matières colorantes au début du Paléolithique supérieur : sources, transformations et fonctions
Salomon, Hélène ULg

Doctoral thesis (2009)

Abstract : Despite an increasing number of studies, colouring materials are still poorly understood among excavation remains. Their attraction lies in their capacity to bring to light diverse and complex ... [more ▼]

Abstract : Despite an increasing number of studies, colouring materials are still poorly understood among excavation remains. Their attraction lies in their capacity to bring to light diverse and complex skills, but also in their intense colouring power and their contrasting colours : red and black, which still possess a symbolic value. These highly symbolic materials may, therefore, highlight the “conceptual” practices of prehistoric men and give access to their symbolic world and thought. In such a particular context as the transition between the Middle and the Upper Palaeolithic, these remains, which are very abundant in most excavations, offer the possibility, through analysis, to get an exceptional insight into the way of life of the last Neanderthals. The Châtelperronian site of the “Grotte du Renne”, in Arcy-sur-Cure (Yonne), is a landmark. It was excavated beween 1949 and 1963 by André Leroi-Gourhan : Numerous colouring materials were discovered there, and Leroi-Gourhan developed theories about their transformation and uses which so far have not been tested, and have remained unchallenged.Since their discovery, the assumption is that those minerals were heated in a controlled way, in order to modify their colour. It is indeed well-known that heat transforms yellow materials (iron hydroxides) in orange, red or purple materials (iron oxides). From this hypothesis originates the theory according to which Neanderthals exploited colouring materials as pigments for symbolic or even aesthetic purposes. But the theory has so far never been proved true. Our study combines several sets of data, obtained from different methods. Physico-chemical and petrological analyses were carried out on the colouring materials. These data were related to their location on the site, in association with exceptionally well preserved “hut” structures. Furthermore, a series of experimentations, aimed to characterize powders obtained via different methods (grinding and crushing on the one hand, abrasion on the other hand). The comparison of all these data enabled us to identify the various technical choices which informed the supply in colouring minerals in all the Châtelperronian levels of the Grotte du Renne. It was thus possible to demonstrate that none of these materials, either red or black, was heated before being used, contrary to what had been assumed so far. The supply in colouring materials was as carefully organised as for other materials (flint, for example) ; they were collected in geological formations occasionally showing on the surface, at more than 10 km from the cave. The exploitation of these geological sites did not vary during the whole Châtelperronian period, and privileged materials which can easily be ground into powder. Part of their supply was ground coarsely in order to cover large surface areas (soils or hides) as preservative or to clean them up. The remaining materials were destined to more meticulous activities, which required a fine, regular, and highly-colouring powder. In this latter case, the Neanderthals of the Grotte du Renne used those products when working on bone materials (bone or mammoth ivory), and used them also for their sheer colour. The set of colouring minerals from the Grotte du Renne reveals Neanderthals’ in-depth knowledge of materials ; they understood perfectly well their properties and qualities, and used them extensively, so that the Châtelperronian site must have been a literally dazzling sight, all red and black. The “chaîne opératoire” which transpires from our analysis shows very sophisticated techniques, and an advanced “technological” knowledge. They are witness to surprising capacities and a highly-evolved pattern of thought. [less ▲]

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See detailMapping Athletic Performance Related Genes in the Equine Genome and a Genome Scan for Superior Athletic Performance in the Thoroughbred
Durkin, Keith ULg

Doctoral thesis (2009)

The primary goal of the Thoroughbred industry is to breed and train superior equine athletes capable of excelling on the racetrack. To date, research into the genetic underpinnings of athletic ability has ... [more ▼]

The primary goal of the Thoroughbred industry is to breed and train superior equine athletes capable of excelling on the racetrack. To date, research into the genetic underpinnings of athletic ability has been limited in the horse. Advances in equine genomics and the genetics of athletic performance in humans have opened up the possibility of investigating this important trait in the Thoroughbred. Initially, 46 candidate genes associated with human athletic performance were mapped in the equine genome by radiation hybrid (RH) and fluorescent in situ hybridization (FISH) mapping. RH data and later the draft equine genomic sequence allowed us to identify microsatellites adjacent to these and other candidate genes (95 in total). Additional microsatellites were added to increase genome coverage, producing a final panel of 186 markers. All the potential markers were initially screened on a pool of DNA for 16 Thoroughbreds to ensure they were polymorphic. The panel was genotyped on 162 Thoroughbreds in total; Centimorgans (cM) between microsatellites were determined with CRI-MAP. The animal’s athletic ability was estimated using career winnings loge transformed to create a linear trait; unraced animals were treated as missing data. Linkage analysis was carried out using the MERLIN program, and association analysis was carried out using the QTDT program. Appropriate thresholds for statistical significance were determined by carrying out 1000 simulated genome scans based on the structure of the original data. LOD scores above 1.54 met the criteria of statistical significance (with a 5% chance of type I error). In the actual genome scan, the marker L12.2 had the highest observed LOD score of 1.16 and p-value of 0.01 and consequently was not significant; the association analysis also did not detect significant association with performance on the track. Given the complexity of the phenotype under investigation and the modest sample size, the lack of linkage/association was not unexpected. Nevertheless, this study has contributed to the RH and FISH maps of the equine genome. Additionally, the development of the genome scanning panel for this study has provided useful information on the most informative microsatellites for linkage or association studies in the Thoroughbred. [less ▲]

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See detailLES TRAITEMENTS ET LA PHARMACOGENETIQUE DES TRAITEMENTS ANTI-VIH-1
Cherrier, Thomas ULg

Doctoral thesis (2009)

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See detailÉtude de la modalité en néo-égyptien
Polis, Stéphane ULg

Doctoral thesis (2009)

Cette thèse constitue la première étude générale de la modalité en néo-égyptien. Le chapitre introductif (p. 5-43) est consacré [1] à la définition de ce premier état de langue de l’égyptien de la seconde ... [more ▼]

Cette thèse constitue la première étude générale de la modalité en néo-égyptien. Le chapitre introductif (p. 5-43) est consacré [1] à la définition de ce premier état de langue de l’égyptien de la seconde phase ; cette définition a permis la délimitation d’un corpus servant d’assise empirique à l’étude (la répartition du corpus en fonction de critères chronologiques et géographiques, de la nature du support et des "Textsorten" a donné la possibilité de pondérer et d’objectiver les analyses proposées pour chaque expression de la modalité). Ensuite, [2] un cadre théorique général pour l’étude de la langue est discuté. Le corps du travail se divise en trois parties consacrées respectivement : [1] à une définition générale de la notion de modalité (cela afin de déterminer les media expressifs qui relèvent de son étude en néo-égyptien) ainsi qu’à l’établissement d’un modèle sémantique à la fois économique, cohérent et correspondant aux données typologiques (p. 44-115) ; [2] à l’étude des modalités radicales (i.e. les modalités déontiques et bouliques en envisageant les relations qu’elles entretiennent avec le domaine axiologique ; p. 116-341) ; [3] à l’examen des modalités assertives (p. 342-446) : [a] analyse des formes de complémentation, en ce compris les liens entre intégration syntaxique, variation de l’assertivité et degré de manipulation, [b] étude de l’impact des auxiliaires d’énonciation sur le degré d’assertivité d’une proposition, [c] critique des théories existantes concernant les moyens expressifs du discours indirect en néo-égyptien. Les conclusions (p. 447-466) sont accompagnées de propositions prospectives devant permettre [1] de rendre le modèle défendu applicable à l’étude des complexes conditionnels, [2] d’intégrer la dimension énonciative dans l’analyse des relations interpersonnelles, [3] de proposer une approche globale des media expressifs de la causalité et de la finalité. [less ▲]

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See detailContribution to the Characterization of Scroll Machines in Compressor and Expander Modes
Lemort, Vincent ULg

Doctoral thesis (2008)

This thesis contributes to the knowledge and the characterization of scroll machines and their systems. It is based on experimental and modeling works carried out on: a) A hermetic scroll compressor used ... [more ▼]

This thesis contributes to the knowledge and the characterization of scroll machines and their systems. It is based on experimental and modeling works carried out on: a) A hermetic scroll compressor used inside an air-cooled water chiller. b) An oil-free open-drive scroll expander integrated into an Organic Rankine Cycle (ORC) power system. c) Open-drive scroll compressor and expander used in a Liquid Flooded Ericsson Cycle Cooler (LFEC). Such a system uses the liquid flooding of the compressor and of the expander to approach isothermal compression and expansion processes. New semi-empirical models of the scroll compressor and expander were proposed and existing models improved. A deterministic model of the scroll expander was established. The model associates a geometrical description of the machine with a thermodynamic description of the expansion process. This model was validated for the two expanders investigated experimentally. The model validation revealed that the performance of the expanders is mainly affected by the supply pressure drop and by the internal leakages. Using the validated model, parametric studies were carried out to investigate the variation of the performance of both expanders with modification of their design and with the operating parameters. The thesis also investigated the scroll machines from the point of view of their integration into thermal systems. A first experimental investigation was carried out on an air-cooled chiller. The scroll compressor semi-empirical model, with its parameters identified on the basis of published manufacturer data, was used as a refrigerant flow meter. The analysis of the experimental data allowed a better understanding of the chiller operation and a better identification of its model parameters (such as the fan and the hot gas bypass control models). A second experimental investigation was carried out on an ORC power system, working with R123. In order to select the most appropriate fluid, the performances achieved with four different fluids were compared by simulation. The experimental study confirmed that the scroll expander is a good candidate for an ORC system: the tested prototype presented a good performance (the maximum global isentropic effectiveness achieved was 68%). Using an ORC simulation model, parametric studies were carried out to investigate the effects of the expander characteristics and operating conditions on the cycle performance. The latter is mainly affected by the expander internal leakage and by the liquid subcooling at the condenser exhaust. A third experimental investigation was performed on a LFEC working with nitrogen as refrigerant and alkyl-benzene oil as flooding liquid. Experimental data was used to identify the parameters of the scroll compressor and expander semi-empirical models. Parametric studies were performed to identify the different factors affecting their performance. One of the undesirable features of the machines is the increase of the supply and exhaust pressure drops with the increase of oil quantity. [less ▲]

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See detailÉtude du vocabulaire de la vie familiale et sociale en Wallonie: approche géolinguistique et lexicologique
Baiwir, Esther ULg

Doctoral thesis (2008)

La thèse est concue comme un volume de l'Atlas Linguistique de la Wallonie (ALW), la plus grande et la plus ambitieuse œuvre de dialectologie en Wallonie. L'objet de la thèse est l'homme en tant qu'être ... [more ▼]

La thèse est concue comme un volume de l'Atlas Linguistique de la Wallonie (ALW), la plus grande et la plus ambitieuse œuvre de dialectologie en Wallonie. L'objet de la thèse est l'homme en tant qu'être social. C'est ainsi le vocabulaire de la famille et des interactions sociales qui est étudié. L'intérêt du sujet ne se limite donc pas uniquement au domaine linguistique, mais il a d'évidentes interactions avec l'ethnographie, l'histoire ou la sociologie. [less ▲]

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See detailBelgien im Nachkriegsdeutschland. Besatzung, Annäherung, Ausgleich (1944-1958)
Brüll, Christoph ULg

Doctoral thesis (2008)

Les relations belgo-allemandes ne constituent pas un champ de recherches souvent fréquenté par des chercheurs de part et d’autre de la frontière – à l’exception des deux occupations allemandes de la ... [more ▼]

Les relations belgo-allemandes ne constituent pas un champ de recherches souvent fréquenté par des chercheurs de part et d’autre de la frontière – à l’exception des deux occupations allemandes de la Belgique. Cette observation était encore plus nette pour la période après 1945. La thèse s’efforce de combiner une approche relativement classique de l’histoire diplomatique avec l’histoire sociale et celle des représentations et mentalités. En effet, l’analyse des plans belges pour l’après-guerre, des demandes de réparations territoriales et économiques et de l’occupation d’une partie de la zone d’occupation britannique par des troupes belges ne se fait pas seulement au niveau des ministères Affaires étrangères, mais également au niveau des principaux concernés : les soldats belges en Allemagne et la population frontalière. La présentation à différents niveaux de récit permet l’analyse des interactions entre la « grande politique » alliée et le quotidien des « concernés ». Les chapitres sur les années 1950 détaillent le rapprochement politique de la Belgique avec la jeune République Fédérale d’Allemagne devant un décor de guerre froide – rappelant la nécessité d’intégrer les Allemands dans le bloc de l’ « Ouest » – et des débuts de l’intégration européenne – discours dominant dans les justifications du rapprochement avec l’ancien ennemi. Dans ces pa-ges, c’est la représentation de l’ « autre » qui guide l’analyse. Le terminus ad quem était constitué par la ratification du traité bilatéral du 24 septembre 1956 par les deux parlements en 1958. Le travail évoque ici la question du prix de la rapide (comparée aux Pays-Bas ou à la France) réconciliation politique, notamment sur le plan de la société civile. Les relations belgo-allemandes après 1945 apparaissent ici surtout comme un processus d’apprentissage ayant pour objectif la volonté de ne plus commettre les mêmes erreurs que pen-dant l’entre-deux-guerres. [less ▲]

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See detailThérapie du mésothéliome pleural malin par l’utilisation du valproate, un inhibiteur de désacétylases
Vandermeers, Fabian ULg

Doctoral thesis (2008)

Le mésothéliome pleural est un cancer de la plèvre provoqué principalement par l’inhalation de fibres d’amiante. Nous avons émis l’hypothèse que la dérégulation de l’expression génique est un paramètre ... [more ▼]

Le mésothéliome pleural est un cancer de la plèvre provoqué principalement par l’inhalation de fibres d’amiante. Nous avons émis l’hypothèse que la dérégulation de l’expression génique est un paramètre important du développement de cette maladie. Or, les histones désacétylases (HDACs) peuvent jouer le rôle de répresseur transcriptionnel en modifiant la conformation de la chromatine. Dans ce contexte, nous avons étudié l’activité anticancéreuse du valproate, un inhibiteur d’HDAC, en combinaison avec différents types de traitements utilisés en chimiothérapie. Nous avons démontré l’effet synergique entre la chimiothérapie et le valproate dans des lignées cellulaires et dans des biopsies isolées à partir de patients. Nous avons étudié les processus impliqués dans l’apoptose et révélé l’implication des caspases, des espèces oxygéno-réactives et le rôle important de la protéine Bid. Nous avons ensuite réalisé une étude transcriptomique par microdamiers dans le but de mieux caractériser les mécanismes impliqués. Enfin, nous avons démontré l’efficacité du valproate dans un modèle préclinique murin. Ces recherches ont permis la mise en place d’un essai clinique de deuxième ligne sur des patients réfractaires à une première chimiothérapie. [less ▲]

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See detailStructure des communautés de plantes herbacées sur les Grands Causses : Stratégies fonctionnelles des espèces et interactions interspécifiques
Fayolle, Adeline ULg

Doctoral thesis (2008)

Plant community response to grazing management was studied on the INRA La Fage experimental station, Larzac Causse. Land use practices were considered as a disturbance and resource filter that remove ... [more ▼]

Plant community response to grazing management was studied on the INRA La Fage experimental station, Larzac Causse. Land use practices were considered as a disturbance and resource filter that remove species. The integrated approach of community structure used in this study was centred on plant functional traits. Continuous variations of plant traits associated with resource acquisition and early phenology indicated the replacement of stress tolerant species by ruderals along the gradient of land use intensity (grazing avoidance). Graminoids were particularly abundant in these communities. Changes in species identity and species functional identity were consistent with the grazing tolerance strategy. At the community scale, the strong functional convergence among dominant species confirmed the filtering effect of grazing management on these traits. Species richness reached its maximum at intermediate grazing. Maximal richness was associated with the coexistence of many growth forms and an important functional richness. These results are interpreted as an extension of the intermediate disturbance hypothesis to the traits of coexisting species. Finally, plant interaction dynamics experienced by five target species allowed us to identify the tendency of facilitated survival and intensely depressed biomass. The effect of communities was roughly similar although huge differences in specific and functional structure. The response to the least from competition and benefited the most from facilitation. [less ▲]

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See detailBehavior of Deep Reinforced Concrete Beams under Monotonic and Reversed Cyclic Load
Mihaylov, Boyan ULg

Doctoral thesis (2008)

Non-slender reinforced concrete beams find extensive application in cases where heavy loads need to be transferred over a given span. The safety of this kind of structural elements is often critical for ... [more ▼]

Non-slender reinforced concrete beams find extensive application in cases where heavy loads need to be transferred over a given span. The safety of this kind of structural elements is often critical for the safety of the structure as a whole. The research described in this thesis is devoted to studying the behaviour of lightly-reinforced non-slender beams under monotonic and reversed cyclic loads, as particular consideration is given to the load-bearing mechanisms which occur in moderately-deep beams. The choice of this topic was motivated in part by verification studies which show that the current code procedures for shear design of members without web reinforcement are least accurate in the range of transition from deep to slender beams. Furthermore, the issue of cyclic response of lightly-reinforced deep beams is of great importance for seismic assessment of existing structures, especially if the similarity between the load-bearing mechanisms in deep beams and those in other non-slender components such as coupling beams, squat shear walls, and frame joints is recognized. An experimental program consisting of ten tests of large non-slender reinforced concrete beams has been performed. All specimens failed in shear after transition from beam load-bearing mechanism to arch action (specimens without stirrups) or truss actions (specimens with stirrups). A suggested kinematic model was successfully used for interpretation of the various deformation measurements. The results showed that part of the ultimate shear was carried in the cracked concrete. It was concluded that load reversals had little effect on the overall response. A test of deep beam provided with single bar #18 demonstrated that anchorage by anchor heads is effective even when the biggest ASTM reinforcing bar is used. Comparison between experimentally-obtained and calculated shear strengths showed that the CSA code rendered reasonably conservative predictions compared to the mostly unconservative results of the ACI and EC2 codes. Theoretical work resulted in a derivation of an improved strut-and-tie model (ISTM) which is based on the CSA shear provisions but accounts for shear carried under the critical diagonal cracks of non-slender beams without web reinforcement. Verification against a large number of tests showed that the new model is consistent with physical observations and explains the transition from deep to slender beams. Furthermore, it was shown that the ISTM can be used in combination with the above-mentioned kinematic model for estimation of the ultimate displacement and deformed shape of non-slender beams. [less ▲]

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See detailProduction of alarm pheromone in aphids and perception by ants and natural enemies
Verheggen, François ULg

Doctoral thesis (2008)

Most Aphidinae species produce and use (E)-ß-farnesene (Eßf) as an alarm pheromone. This sesquiterpene is released by individuals under attack by a predator, and nearby aphids exhibit a variety of alarm ... [more ▼]

Most Aphidinae species produce and use (E)-ß-farnesene (Eßf) as an alarm pheromone. This sesquiterpene is released by individuals under attack by a predator, and nearby aphids exhibit a variety of alarm behaviours. This PhD thesis aims to better understand how aphids manage their production and emission of alarm pheromone (Chapter IV). We also wanted, in a second step, to improve our knowledge on the roles that Eßf could play in the relationships that aphids have with their predators (Chapter V) and tending ants (Chapter VI), in order to better pinpoint the problem in this very tough context. The aphid predators have indeed a real advantage to be able to use the odorant cues emitted by their prey, to locate them and to select an adequate oviposition site. Ants establish with certain aphid species mutualistic relationships, which occurrence could be facilitated by the use of aphids’ odours. In Chapter IV, we have highlighted that aphid colonies non subjected to attack by predators release constantly small quantities of Eßf in their headspace, which means that this molecule could have additional roles than just acting as an alarm pheromone. In a second study, we demonstrated that the release of Eßf was not contagious, and therefore that a non stressed aphid receiving the alarm signal does not release additional Eßf. Since the production of alarm pheromone is likely to entail physiological cost, we tested and validated the hypothesis that aphids regulate their Eßf production according to their social environment. In Chapter V, we studied the ability of the hoverfly predator Episyrphus balteatus (Diptera, Syrphidae) to be used as biological control agent against aphids infesting tomato plants (Lycopersicon esculentum). After identifying the odours emitted by aphid infested plants, we have demonstrated that although this Diptera is able to perceive all the odours released by the system, it mainly uses Eßf to select its oviposition site. However, the E. balteatus larvae are not adapted to the architecture of tomato plants. We also showed that the Asian ladybeetle Harmonia axyridis (Coleoptera, Coccinellidae) olfaction was adapted to the perception of Eßf and that this beetle is also attracted by this sesquiterpene. Finally, in Chapter VI, we characterized the benefits accruing to aphid populations that have established mutualistic relationships with Lasius niger (Hymenoptera, Formicidae), and have demonstrated the role of Eßf and honeydew, respectively in locating aphid colonies and in the persistence of the mutualism. [less ▲]

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See detailNovel Strategies towards aminophosphonic derivatives by [4+2] cycloadditions
Monbaliu, Jean-Christophe ULg

Doctoral thesis (2008)

Aminophosphonic and related compounds were almost unknown 50 years ago, but today the literature data have considerably increased. Their negligible mammalian toxicity and their similarity with aminoacids ... [more ▼]

Aminophosphonic and related compounds were almost unknown 50 years ago, but today the literature data have considerably increased. Their negligible mammalian toxicity and their similarity with aminoacids confer on these compounds a top place as potential candidates for drugs. The discovery of numerous natural aminophosphonic derivatives endowed with biological properties useful to both medicinal and agricultural fields enhanced the infatuation for synthetic analogs and homologs. Intensive work has been performed towards alpha-aminophosphonic compounds, the direct analogs of natural alpha-aminoacids, disclosing versatile strategies, compatible both with molecular diversity and asymmetric synthesis. Less synthetic effort was devoted to the synthesis of higher homologs. Recent developments of the Diels-Alder reaction offer an asymmetric and convergent entry to various six-membered highly functionalizable key intermediates, compatible with molecular variety. As it is, the Diels-Alder (D-A) reaction should provide an original and versatile entry to beta-, gamma- and delta-aminophosphonic compounds, a challenging research area. As a direct consequence of the strategy, one of the two D-A partners (diene or dienophile) will act as vehicle for the phosphonate moiety. By contrast to its common use for the stabilization of alpha-negative charges, its implication in D-A reactions remains scarce. Indeed, the phosphonate moiety is not an efficient substituent susceptible to activate the D-A reaction; its use requires compensation by the activation of the other partner or by specific activation. Both synthetic organic and computational chemistry will furnish information to propose a fine understanding of the key D-A steps, in view to optimize the achievement of the corresponding cycloadducts. These cycloadducts will be considered as synth-/chirons for the synthesis of aminophosphonic compounds. [less ▲]

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See detailHagiographie et statistique linguistique : étude d’un corpus de traductions médiolatines d’origine grecque
Philippart de Foy, Caroline ULg

Doctoral thesis (2008)

The dissertation considers a corpus of 35 hagiographic texts translated from Greek into Latin in the Middle Ages. This corpus is representative of the different stages in the history of hagiographic ... [more ▼]

The dissertation considers a corpus of 35 hagiographic texts translated from Greek into Latin in the Middle Ages. This corpus is representative of the different stages in the history of hagiographic translations and of the various centres of translation in Italy. Those translations are to be presented in a new and original way by studying from a linguistic point of view the Latin language used by the translators to render their Greek models and the techniques that were implemented to achieve those translations, considering them not individually but in a global and comparative way. Quantitative linguistics was chosen as a method in order to go through a large corpus and to compare numerous texts, to enlighten their characteristics and their common or opposite features on a lexical as well as a syntactical basis. [less ▲]

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See detailMechanical properties, residual stresses and structural behavior of thin-walled stainless steel profiles
Rossi, Barbara ULg

Doctoral thesis (2008)

Although it offers a wide variety of interesting properties such as fire resistance or durability, stainless steel has been used in limited amount in structures. It is a known fact that the design rules ... [more ▼]

Although it offers a wide variety of interesting properties such as fire resistance or durability, stainless steel has been used in limited amount in structures. It is a known fact that the design rules don't properly account for the additional benefits of stainless steel properties and are largely based on the specifications for carbon steel. Indeed, a number of similarities exist between stainless steel and ordinary carbon steel but there is sufficient differences to afford a specific treatment in design standards. And since stainless steel is an expensive material, it is important to accurately predict the resistance of structural members. The present research work is dedicated to the study of cold-formed stainless steel profiles. It actually follows the life of a stainless steel construction element and falls on three fundamental topics: the material behavior, the through-thickness residual stress distribution and mechanical enhancement due to the cold-forming process and, last, the strength of concentrically compressed thin-walled columns. Firstly, several constitutive models are characterized such as Teodosiu-Hu's micro-structural based hardening model, capable of predicting the behavior of the studied stainless steel grade submitted to biaxial loading causing plastic strain. This model accounts for the nonlinear hardening behavior, the anisotropy, the Bauschinger effect and more complex behavior such as the observed work-hardening stagnation under reversed deformation at large strains. For this purpose, a collection of tests is carried out including multiaxial tests such as tensile-shear tests and successive simple shear tests and plane-strain tests. Secondly, the effects of the forming process on the mechanical properties are studied. To begin with, on the basis of the constitutive models developed previously, an analytical method that calculates the biaxial residual stress distribution in the walls and in the corners of cold-formed profiles is established. Based on the conclusions drawn from this theoretical analysis, a new formula for the evaluation of the actual mechanical properties is established. This formula is not restricted to a single alloy or type of cross-section. Current design standards are then used to calculate the strength of lipped-channel section columns failing by combined distortional and overall flexural-torsional buckling and the results are compared to tests. Indeed, full-scale tests on cold-formed stainless steel lipped channel section columns were achieved in the Structures Laboratory of the University of Liège. And, once verified against the test results, finite element models were used to generate additional results when necessary. The author then presents a new Direct Strength Method taking into account this phenomenon. Finally, a wide amount of reference results are gathered from the literature, without limiting oneself to any kind of cross-section or stainless steel grade. This database is used to propose an improved formulation for the design of stainless steel thin-walled section columns failing by distortion, local or combination of local and overall buckling in the low slenderness range. [less ▲]

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See detailImplantation d'acide hyaluronique estérifié lors de la microchirurgie des lésions cordales bénignes
FINCK, Camille ULg

Doctoral thesis (2008)

La microchirurgie des pathologies cordales bénignes est pratiquée afin d’améliorer les caractéristiques mécaniques du vibrateur laryngé. C’est en augmentant la souplesse tissulaire et la fermeture ... [more ▼]

La microchirurgie des pathologies cordales bénignes est pratiquée afin d’améliorer les caractéristiques mécaniques du vibrateur laryngé. C’est en augmentant la souplesse tissulaire et la fermeture glottique en phonation que le micro-chirurgien espère améliorer les caractéristiques du son laryngé émis. Les techniques microchirurgicales ont évolué de manière spectaculaire au cours des 20 dernières années grâce à la connaissance de plus en plus approfondie de la structure cordale normale et surtout de son tissu conjonctif : la lamina propria. C’est la partie la plus superficielle de la lamina propria, l’espace de Reinke, qui joue le rôle le plus important dans la production du son. C’est aussi l’espace de Reinke qui est occupé, détruit ou remanié en cas de pathologie cordale bénigne. La microchirurgie vise à le libérer du processus pathologique. L’originalité des techniques microchirurgicales exposées dans ce travail est de tenter, non seulement de libérer l’espace vibrant de la lésion cordale, mais aussi de modifier les processus cicatriciels post-opératoires par l’utilisation d’un implant résorbable d’acide hyaluronique estérifié. Les objectifs de ce travail sont : - de contribuer à la connaissance des résultats fonctionnels laryngés et vocaux observés après une microchirurgie cordale - d’évaluer l’impact fonctionnel, sur ces résultats, de l’utilisation d’un implant résorbable d’acide hyaluronique estérifié, en fin d’intervention chirurgicale. [less ▲]

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See detailSystematic Cooperation in P2P Grids
Briquet, Cyril ULg

Doctoral thesis (2008)

P2P Grid computing seeks the convergence of Grid and P2P technologies. Deploying a P2P Grid middleware on a set of computers enables an organization to automatically barter computing time with other ... [more ▼]

P2P Grid computing seeks the convergence of Grid and P2P technologies. Deploying a P2P Grid middleware on a set of computers enables an organization to automatically barter computing time with other Internet-connected organizations. Such P2P exchanges of computing time enable individual Peers, i.e. organizations, to transparently aggregate large amounts of computational power with minimal infrastructure requirements or administrative cost. Challenges arise from the requirement for scalability and robustness. Individual worker nodes are unreliable, as P2P Grids operate on unmanaged desktop computers. A specificity of P2P Grids is that each Peer can reclaim at any time the computational power of worker nodes supplied to other Peers, leading to bursts of execution preemption. These are the major contributions of our dissertation: * Firstly, we propose a new P2P Grid architecture, the Lightweight Bartering Grid (LBG). Through systematic cooperation between Grid nodes, the reliability of execution of computational requests is greater than the sum of the reliabilities of worker nodes. * Secondly, we propose a highly scalable data transfer architecture. It is based both on the BitTorrent P2P file sharing protocol and on the removal of the temporal cost of downloading redundant copies of input data files. * Thirdly, besides a middleware implementation of LBG, we also provide an implementation of a discrete-event simulator. Its originality resides in the weaving of the simulator code into the bartering code of the middleware, which is made possible through the virtualization of Grid nodes. This enables reproducible testing and accurate performance evaluation of the bartering policies because the Peers of a simulated Grid make the same bartering decisions as Peers deployed on real computers. The LBG architecture exhibits the following remarkable features: * The scheduling model supports the queueing of external requests and the architecture enables a flexible study of bartering policies. * The architecture is open, flexible, lightweight and facilitates software engineering. It enables the easy development, testing, evaluation and deployment of combinations of scheduling policies. * The architecture is fully P2P. [less ▲]

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See detailEtudes génétiques et immunomodulatoires de la ghréline sur les traits de production et de conformation en races bovines ainsi que sur la croissance chez le rat
Colinet, Frédéric ULg

Doctoral thesis (2008)

En production animale, notamment dans les filières bovines, il est d’un intérêt économique d’augmenter la quantité d’hormone de croissance dans la circulation sanguine. La ghréline est un peptide ... [more ▼]

En production animale, notamment dans les filières bovines, il est d’un intérêt économique d’augmenter la quantité d’hormone de croissance dans la circulation sanguine. La ghréline est un peptide principalement produit au niveau de la paroi stomacale. Ce ligand endogène au GHSR stimule la sécrétion hypophysaire de l’hormone de croissance. Peptide orexigène, la ghréline est impliquée dans les mécanismes relatifs au maintien de l’homéostasie énergétique. Dans l’optique d’améliorer les performances animales, deux approches de la ghréline ont été effectuées. La première approche consiste en l’étude des gènes bovins codant pour la ghréline (bGHRL) et son récepteur (bGHSR). Ces deux gènes ont été respectivement localisés sur BTA 22 et BTA 1. Quatorze polymorphismes ont été détectés sur ces deux gènes et trois d’entre eux affectent la structure primaire du GHSR bovin. Des associations, à différents niveaux de signification, entre certains de ces 14 sites polymorphiques et des traits de production et de conformation ont été mis en évidence au sein d’un groupe de 127 taureaux Holstein sur base de leurs descendances directes présentes en Région Wallonne. La seconde approche aborde les effets d’une immunisation passive contre la ghréline sur des rats mâles en croissance en comparaison à celles contre la leptine et la cholécystokinine. Lors d’une alimentation équilibrée, le traitement envers la ghréline sur ces rats n’a pas influencé la croissance et l’ingestion par rapport aux animaux témoins. Des effets ont été observés entre les différentes immunomodulations au niveau des paramètres de croissance, d’ingestion et endocrinologiques. Les présents résultats invitent à de nouvelles investigations des gènes bGHRL et bGHSR sur des données relatives à d’autres populations/races bovines et de l’immunomodulation de la ghréline lors de conditions d’expérimentation différentes (alimentation déséquilibrée, stade physiologique, espèce, etc.). Ces investigations pourraient être valorisées en sélection et production animale mais également en médecine tant humaine que vétérinaire. [less ▲]

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See detailDesign, synthesis and biological evaluation of cognitive enhancers acting through the potentiation of the AMPA receptors
Francotte, Pierre ULg

Doctoral thesis (2008)

Alzheimer’s disease (AD) represents one of the greatest health problems in industrialized countries considering the ageing population. Only four drugs are currently approved for the treatment of this ... [more ▼]

Alzheimer’s disease (AD) represents one of the greatest health problems in industrialized countries considering the ageing population. Only four drugs are currently approved for the treatment of this disease. As these drugs are characterized with a limited time efficacy, it has become urgent to develop additional innovative AD treatments. Amongst the approaches that are actively investigated, the one consisting in potentiating a subclass of glutamate receptors appears attractive. This well advanced pharmacological approach includes three major classes of compounds amongst which appear the benzothiadiazine 1,1-dioxides. The present thesis is a pursuit of the preliminary efforts that were published in 1998 and 2001 by our team. Based on promising in vitro results obtained with the lead compound 59, pharmacomodulations around 59’s structure have been achieved in order to enhance its in vivo activity and to optimize its pharmacokinetic parameters. First efforts were devoted to exploratory synthesis where attention was paid to the impact of the substituent introduced at the 7-position. Moreover, some pyridothiadiazine dioxides as well as thienothiadiazine dioxides were prepared. The most important part of our pharmacomodulations was focused on the thiadiazine ring system. Considering that the poor in vivo results obtained with 59 could be due to a metabolic weakness of the latter, the introduction of fluorine atoms was tempted as a lead optimization strategy. This approach was successful, since it led to the synthesis of 95b which was selected for further pharmacological evaluations. This new lead compound was shown to exert significant cognitive-enhancing effects in vivo after oral administration to Wistar rats. Moreover, the study of the metabolic degradation of 95b allowed the assessment of the starting hypothesis that had dictated the pharmacomodulation’s philosophy. Finally, additional exploratory pharmacomodulations were achieved notably leading to the preparation of a quinazolinone series and 1,4-benzothiazine compounds. This research allowed to significantly improve the pharmacokinetic profile of our series and led to the identification of 95b as a new lead compound. However, many pharmacomodulations remain to be explored. The data collected during this thesis are appealing further studies. Efforts in the near future should lead to the design of novel drug candidates among which a future innovative AD treatment could emerge. [less ▲]

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See detailDesign of new stealthy and pH-sensitive polymer micelles for potential solid tumor targeting
Van Butsele, Kathy

Doctoral thesis (2008)

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See detailEtude des facteurs écologiques et écotoxicologiques impliqués dans la réussite d’incubation chez la tortue luth, Dermochelys coriacea, de Guyane Française
Guirlet, Elodie ULg

Doctoral thesis (2008)

Leatherback turtles, Dermochelys coriacea, have relatively low hatching success in comparison to other marine turtle species. This low hatching rate is largely a result of high embryonic mortality rather ... [more ▼]

Leatherback turtles, Dermochelys coriacea, have relatively low hatching success in comparison to other marine turtle species. This low hatching rate is largely a result of high embryonic mortality rather than infertility, but the specific causes remain unknown. Leatherbacks are vulnerable to excessive adult mortality (resulting in population decline) because they are long-lived species. However, low hatching success and corresponding low juvenile recruitment could also result in long term declines of leatherbacks. On the Yalimapo beach, in French Guiana, hatching success is lower for this species than on other nesting sites, emphasising the problem of recruitment for the population. Understanding the causes of low hatching success is therefore an important conservation step towards preventing extinction in this population. During my thesis, I investigated the role of ecological (predation and nest site location) and ecotoxicological factors (blood and egg contamination by trace elements and organochlorine compounds) on the hatching success of leatherback nests. Firstly, nest location was shown to have an important effect on predation and inundation rate that decreased hatching success. Secondly, a maternal transfer of contaminants from females to their eggs was confirmed, raising the issue of the deleterious effects of environmental contaminants on embryos development, a developmental stage very sensitive to contaminants. Dose-effect relationships between contaminants and hatching success need to be assessed to establish the risk of environmental pollution for leatherback reproduction. Moreover, the use of stable isotope analysis for females differing in the number of years between two reproductive seasons revealed that they used different feeding areas. These feeding grounds differed in their geographical location, but also in the quality of the available prey in terms of their level of contamination by environmental pollutants, highlighting the issue of adult contamination. This thesis confirmed the importance of ecological factors for hatching rate and highlighted the existence of ecotoxicological factors, which have not yet been studied for the leatherback turtle. [less ▲]

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See detailPolitical Transnationalism and the State
Lafleur, Jean-Michel ULg

Doctoral thesis (2008)

The first part of the thesis consists in a review of the literature and a conceptual discussion about the concept of immigrant transnationalism and immigrant political transnationalism. This discussion ... [more ▼]

The first part of the thesis consists in a review of the literature and a conceptual discussion about the concept of immigrant transnationalism and immigrant political transnationalism. This discussion shows that a series of gaps currently exists in the research on the links between the emigrants and the home country. Two of such gaps are underlined in the thesis. On the one hand, it remains difficult to determine why states decide to extend political citizenship to their citizens abroad. On the other hand, the influence of the state on its emigrant community seems neglected for the benefit of a post-national vision of citizenship. These are the gaps that this thesis is trying to address. The second part of the thesis presents in three case studies the results of the empirical research conducted in Italy, Belgium and Mexico. Some elements of migration history introduce each case and is then followed by an extensive analysis of the debate on the extension of political citizenship (especially the right to vote from abroad). A special focus is put on the role of internal actors (political parties, administrations...) and external actors (migrants, associations...). In the third part of the thesis, the author conducts a comparative analysis of the three cases. By doing so, the reasons why states extend political citizenship to citizens residing abroad appears clearly. It also leads to reject the post-national vision of citizenship supported by some scholars. After the presentation of the four variables pushing to act as they do in the field of external political citizenship, the thesis concludes by opening up new research tracks in the field of political transnationalism. [less ▲]

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See detailHileôs tôi phorounti. Sérapis sur les gemmes et les bijoux antiques
Veymiers, Richard ULg

Doctoral thesis (2008)

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See detailDétection et caractérisation de peptides obliques au sein de protéines amyloïdogéniques
Crowet, Jean-Marc ULg

Doctoral thesis (2008)

The study of amyloidogenic proteins is of interest in biochemistry because these proteins undergo conformational changes and aggregation. Both processes are largely implicated in several diseases ... [more ▼]

The study of amyloidogenic proteins is of interest in biochemistry because these proteins undergo conformational changes and aggregation. Both processes are largely implicated in several diseases including Alzheimer’s, Parkinson’s or Creutzfeldt-Jakob’s disease. These phenomena are not completely understood, either at a structural or energetical point of view. Tilted peptides are short protein fragment (11 to 19 residues) that adopt a tilted orientation when inserted into biological membranes and destabilise them. Recently, tilted peptides have been detected in two amyloidogenic proteins involved in neurodegenerative diseases; the amyloid β peptide responsible for Alzheimer’s disease, and the PrP protein that causes Creutzfeldt-Jakob’s disease. Tilted peptides could be responsible for the neurotoxic effects of these proteins. Due to their destabilising properties, they could interact directly with the membrane leading to cell death. Tilted peptides could also be involved in the transconformational process of the proteins. The aim of this work is to detect tilted fragments in other amyloidogenic proteins by molecular modelling and to study some of these peptides experimentally to evidence their lipid destabilizing properties, their structure and their toxicity. In addition, this work enable the design of an automatic method of detection for tilted peptides. Twenty-two tilted peptides from 18 different proteins have been detected among 53 amyloidogenic proteins and 7 peptides were tested experimentally. The results support the hypothesis that some tilted peptides could be involved in transconformational processes and/or cytotoxicity related to amyloidogenic proteins. [less ▲]

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See detailUne rhétorique par objet: les mimétismes chez Francis Ponge
Demoulin, Laurent ULg

Doctoral thesis (2008)

Les recueils de Francis Ponge Le Parti pris des choses et Pièces sont analysés poème par poème à la recherche de mimétismes, c'est-à-dire des "procédés stylistiques de formes variables visant à minimiser ... [more ▼]

Les recueils de Francis Ponge Le Parti pris des choses et Pièces sont analysés poème par poème à la recherche de mimétismes, c'est-à-dire des "procédés stylistiques de formes variables visant à minimiser l'arbitraire du signe, c'est-à-dire à motiver quelque peu le langage en établissant un mien entre la forme du plan du contenu et celle du plan de l'expression". [less ▲]

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See detailStudy of Genetic Variability of Fatty Acid Profile in Bovine Milk and Fat Using Mid-Infrared Spectrometry
Soyeurt, Hélène ULg

Doctoral thesis (2008)

Changes in milk fat composition influence its nutritional quality as well as the technological properties of butter. The impact of feed on fat composition is well known; however, limited information is ... [more ▼]

Changes in milk fat composition influence its nutritional quality as well as the technological properties of butter. The impact of feed on fat composition is well known; however, limited information is available on the genetic variability of fatty acids in bovine milk. The overall aim of this PhD thesis was to study the genetic variability of fatty acid profile in bovine milk and fat. This type of research needs a large amount of data. Expensive reference analysis is used to measure the fatty acid contents in fat. The first objective of this thesis was to develop an alternative method that could be faster and cheaper than traditional methods. Calibration equations predicting the contents of fatty acid from mid-infrared spectrum were established. The contents of saturated and monounsaturated fatty acids, omega-9, fatty acids with short, medium and long chain were the best predicted. Thanks to the implementation of this method in the Walloon routine milk recording, more than 20,000 milk samples were analyzed. This database permitted to model the variation of fatty acid contents in milk and fat. From these models, the genetic variability of fatty acid profile was shown. The complexity of models increased throughout this project due to the increase of new available data. Differences across 7 dairy breeds were estimated using single and multi-trait mixed models. Milk fat and delta-9 desaturase activity of Jersey and dual purpose Belgian Blue differed significantly from Holsteins. Therefore, the choice of a given breed could modify the fat composition. Heritability values obtained for studied fatty acids with multi-trait mixed model ranged from 0.05 to 0.42. Higher values were observed for saturated compared to unsaturated fatty acids. Moderate heritability estimates were observed for the activity of delta-9 desaturase (0.20) and the hardness of butter (0.27). These two traits were estimated by specific fatty acid ratios. The heritability observed using a multi-trait random regressions test day model for the content of saturated fatty acids (0.42) was similar to the one observed for the percentage of fat (0.37). Considering the impact of selection on fat content, the selection could have a great impact on fat composition. High genetic correlations were observed between some fatty acids having similarities in their synthesis. Heritability and correlations varied through the duration of the lactation. Due to the large number of fatty acids, the estimation of an index, which includes the proper fatty acid profile, could be interesting for a future selection program. This PhD thesis provides the background required by future studies to estimate the impact of animal selection on milkfat composition. [less ▲]

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See detailLa transmission du patrimoine culturel immatériel : réflexion sur l'importance d'une médiation culturelle
Lempereur, Françoise ULg

Doctoral thesis (2008)

By signing the UNESCO Convention for the Safeguarding of Intangible Cultural Heritage , each State Party committed itself to take the necessary measures to ensure the viability of oral traditions ... [more ▼]

By signing the UNESCO Convention for the Safeguarding of Intangible Cultural Heritage , each State Party committed itself to take the necessary measures to ensure the viability of oral traditions, performing arts, social practices, traditional knowledge & craftsmanship, and everything which should be transmitted as such or as an addition to natural, movable or real-estate heritages present within its territory. In the Convention, “Safeguarding” means “measures aimed at ensuring the viability of the intangible cultural heritage, including the identification, documentation, research, preservation, protection, promotion, enhancement, transmission, particularly through formal and non-formal education, as well as the revitalization of the various aspects of such heritage”. To ensure identification with a view to safeguarding, each State Party should draw up, in a manner geared to its own situation, one or more inventories of the intangible cultural heritage present in its territory. As no general theoretical studies exist on the validity of inventory and safeguarding, this dissertation progressed into a discussion about the issues, conditions and practices of transmission. Various interdisciplinary approaches – anthropological, historical, sociological, ethical, political and even sometimes linguistical, musicological, medical or juridical – resulted in blended viewpoints. The research is as theoretical as it is pragmatical. It comes after thirty years of pratical experience and observations, of filming and recording the oral and non-verbal traditions in the small communities of Wallonia, as well as experiences elsewhere. The author's basic assumption is that the existence of an intangible cultural heritage specific to each sociocultural community (of any size or composition) which, inspite of the threat of cultural globalization, allows this community to socialize, instead of cutting it off from the others. To highlight this heritage does not mean to withdraw into oneself or one’s past but to make way for cultural diversity, without ranking. This dissertation does not claim to solve, in 415 pages, all the theoretical problems raised by transmission and safeguarding of intangible cultural heritage. It suggests a first reflection about the contents, the aims, the means of transmission and the useful mediators for sustaining cultural diversity. It shows that the permanent evolution of the patrimonial values results from the social and economic situations where they are found and that it is pointless to supervise the transmission if holders of the heritage do not themselves support, consciously or not, the transmission process. [less ▲]

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See detailContribution à l'étude pharmacologique et clinique du tiludronate chez le cheval
Delguste, Catherine ULg

Doctoral thesis (2008)

Le tiludronate (Tildren™, CEVA Santé Animale, Libourne, France) est un bisphosphonate récemment introduit sur le marché dans plusieurs pays européens pour le traitement du syndrome podotrochléaire ... [more ▼]

Le tiludronate (Tildren™, CEVA Santé Animale, Libourne, France) est un bisphosphonate récemment introduit sur le marché dans plusieurs pays européens pour le traitement du syndrome podotrochléaire (syndrome naviculaire) et de l’ostéoarthrose des articulations intertarsienne distale et tarso-métatarsienne (éparvin) chez le cheval. Il est le premier bisphosphonate disponible en médecine vétérinaire en général, et en médecine équine en particulier. La posologie de tiludronate qui a fait l’objet d’un enregistrement dans différents pays d’Europe est de 10 administrations quotidiennes consécutives de 0.1 mg/kg sous forme de bolus intraveineux. Or, il ressort de la pratique courante que l’administration de la dose totale de 1 mg/kg en une perfusion lente unique est préférée par les utilisateurs pour des raisons pratiques et financières. Il ressort aussi de différentes études que cette forme d’administration est bien tolérée (Varela et al., 2002) et efficace dans certaines pathologies (Coudry et al., 2007). La première étude de ce travail a consisté en la comparaison pharmacologique de ces deux schémas posologiques. Il en est ressorti qu’ils produisaient une même exposition plasmatique totale et des effets similaires sur le marqueur plasmatique de résorption osseuse carboxy-télopeptide de collagène de type I (CTX-1). Il en a été conclu que les dix administrations quotidiennes consécutives de 0.1 mg/kg pouvaient être remplacées par la perfusion intraveineuse lente unique de 1 mg/kg. Les bisphosphonates sont caractérisés par des propriétés pharmacologiques très spécifiques et inhabituelles, de par leur forte affinité pour l’os et leur stockage à long terme dans ce compartiment profond. De ce fait, les modèles PK-PD classiques qui mettent en relation mathématique les concentrations plasmatiques avec les effets du médicament sont inadaptés pour décrire le comportement pharmacologique des bisphosphonates, et il est suggéré que les concentrations osseuses doivent être davantage prises en compte pour le développement de tels modèles (Cremers et al., 2005). Dans le but final de développer un modèle PK-PD du tiludronate chez le cheval, une méthode de biopsie osseuse permettant la répétition de dosages de tiludronate osseux a été validée dans la seconde étude de cette thèse. Dans celle-ci, huit chevaux ont subi des biopsies osseuses bilatéralement en quatre sites (le tuber coxae, le métacarpien principal, la 13ème côte et l’os cuboïde) à différentes échéances s’étalant de 1 jour à 1 an après 1 (n=4) ou 2 (n=4, à 4 semaines d’intervalle) traitements au tiludronate de 1 mg/kg par voie intraveineuse. En chaque site, les biopsies osseuses ont été effectuées à la fois à l’aide d’une fraise électrique de 5 mm de diamètre interne (Implanteo™, Anthogyr) pour l’échantillon test et d’un ostéotome ou d’une scie oscillante pour les échantillons de référence. Le tuber coxae s’est avéré être le meilleur site de biopsie, à la fois accessible, facile à biopsier, et sur lequel les dosages de tiludronate ne présentaient pas de difficultés techniques et étaient fiables. Malheureusement, ces biopsies n’offraient pas un matériel qualitativement et quantitativement suffisant que pour permettre des analyses histologiques et histomorphométriques. Dans une troisième étude, a donc été testée sur quatre chevaux la validité pour ce type d’analyses d’une autre technique de biopsies, utilisant un plus grand trocart que dans l’étude 2 (15 versus 5 mm de diamètre interne), et de type manuel. Les biopsies ont été réalisées sur cheval debout au niveau du tuber coxae avant (côté gauche) et 48 h après (côté droit) l’administration d’une perfusion intraveineuse lente de 1 mg/kg de tiludronate. Les biopsies ainsi réalisées ont permis d’effectuer les analyses escomptées. Cependant, aucun effet précoce du traitement au tiludronate n’a pu être mis en évidence sur les paramètres histologiques et histomorphométriques étudiés. Aucun modèle expérimental équin relatif aux pathologies pour lesquelles le tiludronate a été enregistré n’existe. Or il est indispensable, pour mieux en cerner les propriétés pharmacologiques et les applications cliniques potentielles, de tester son efficacité en conditions standardisées. L’immobilisation d’un membre sous plâtre est connue pour induire de l’ostéopénie de non usage chez le cheval (Buckingham et Jeffcott, 1991; van Harreveld et al., 2002). Dans la quatrième étude de ce travail, l’efficacité clinique du tiludronate versus placebo a été testée dans les conditions standardisées d’un modèle équin d’ostéopénie induite par immobilisation sous plâtre d’un membre antérieur pendant 8 semaines. Seize chevaux ont ainsi été immobilisés, dont huit ont été traités au tiludronate 1 mg/kg en perfusion lente deux fois à quatre semaines d’intervalle, soit en début et à mi-immobilisation, et huit ont reçu un placebo. Après la période d’immobilisation, les chevaux ont été progressivement remobilisés pendant 4 semaines puis ont subi un entraînement standardisé pendant 8 semaines. Le traitement au tiludronate a permis de prévenir la chute significative de densité minérale osseuse (DMO) mesurée par absorptiométrie biphotonique (DEXA) observée à long terme au niveau du membre immobilisé des chevaux du groupe placebo. Cet effet préventif ne s’est pas marqué sur le membre controlatéral. Le tiludronate a également induit chez les chevaux traités des chutes rapides et significatives des taux de CTX-1 sérique, contrairement aux chevaux du groupe placebo chez qui ces taux sont restés élevés pendant la quasi-totalité de l’immobilisation. Aucun effet du tiludronate n’a été constaté sur l’activité des iso-enzymes osseuses des phosphatases alcalines (bone ALP), marqueur de formation osseuse, ni sur les caractéristiques du cortex superficiel du canon du membre immobilisé évaluées par ultrasonographie quantitative (QUS). De l’ensemble de ces travaux, il a été conclu que (1) le CTX-1 sanguin est un marqueur de résorption osseuse sensible et adéquat pour le suivi d’un traitement au tiludronate chez le cheval ; (2) le tuber coxae est un site de biopsie osseuse adéquat pour effectuer les analyses nécessaires à l’élaboration d’un modèle PK-PD du tiludronate chez le cheval ; (3) le tiludronate est capable d’inhiber la résorption osseuse dans un modèle d’immobilisation chez le cheval, et la DEXA est une méthode suffisamment sensible pour l’objectiver en quelques mois ; (4) de nouvelles études pharmacologiques devraient être menées afin de documenter l’accumulation osseuse et les effets du tiludronate sur différents paramètres pharmacodynamiques en cas d’administrations répétées de perfusions de 1 mg/kg chez le cheval. Pour ce faire, des techniques plus sensibles de dosage du tiludronate devraient idéalement être utilisées dans un souci d’exactitude des données. D’autre part, de nouvelles études cliniques d’efficacité sur des chevaux souffrant de pathologies osseuses devraient être menées en incluant des mesures de CTX-1, et si possible des mesures de DMO à différents sites d’intérêt. [less ▲]

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See detailOrigine et survivances. L'historique et le transcendantal en tension. Warburg, Cassirer, Panofsky.
Hagelstein, Maud ULg

Doctoral thesis (2008)

Cette étude se divise en trois chapitres principaux, respectivement consacrés aux travaux de Warburg, de Cassirer et de Panofsky. Bien qu’étant organisées de manière chronologique, les trois parties ... [more ▼]

Cette étude se divise en trois chapitres principaux, respectivement consacrés aux travaux de Warburg, de Cassirer et de Panofsky. Bien qu’étant organisées de manière chronologique, les trois parties obéissent à une articulation thématique : la première est consacrée à l’analyse des phénomènes temporels décrits par l’historien de l’art Aby Warburg ; la seconde, à la définition du transcendantal livrée par Ernst Cassirer ; la troisième, à la possibilité d’un « transcendantal historique » favorisée par les travaux d’Erwin Panofsky. Pour poser le cadre de la recherche entreprise ici, on est reparti d’un problème métaphysique important : la définition de l’entreprise critique kantienne à travers la notion de « transcendantal ». En relisant les grands textes de Kant sur la question (Critique de la raison pure / Prolégomènes), on s’aperçoit en premier que le caractère nécessaire et objectif de toute connaissance a priori l’oppose par principe aux analyses historiques. La distinction entre connaissance pure et connaissance empirique est fermement établie. Or, Kant laisse tout de même entrevoir la possibilité d’un « a priori empirique » : dans le domaine même des connaissances a priori, il faut séparer les connaissances pures et empiriques. Certaines propositions peuvent être a priori sans être nécessairement transcendantales. Partant de là, rien n’interdit de reconsidérer le caractère « apriorique » de certaines notions centrales de l’histoire de l’art. Mais peut-on concevoir une approche véritablement transcendantale de l’objet d’art, qui suspende son caractère historique et empirique ? La question de l’« origine » s’avère révélatrice à cet égard. En effet, cette notion complexe peut s’entendre en un double sens (empirique ou non-empirique). Même les études historiennes oscillent entre ces deux acceptions – ce qui amène à interroger la nature même de l’enquête historique. [less ▲]

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See detailStyle beyond Borders: Language in Recent Nigerian Fiction
Tunca, Daria ULg

Doctoral thesis (2008)

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See detailNeuroplasticité saisonnière chez le canari adulte (Serinus canaria): expression des protéines Doublecortin et Reelin et modulation par les hormones stéroïdes, la photopériode et l'environnement social.
Boseret, Géraldine ULg

Doctoral thesis (2008)

Dans de nombreuses espèces d’oiseaux chanteurs (ou Passériformes), dont fait partie le canari domestique (Serinus canaria), le comportement de chant est produit à la fois pour défendre un territoire ou ... [more ▼]

Dans de nombreuses espèces d’oiseaux chanteurs (ou Passériformes), dont fait partie le canari domestique (Serinus canaria), le comportement de chant est produit à la fois pour défendre un territoire ou attirer un partenaire. Le Système de Conntrôle du Chant est un réseau nerveux central spécialisé, principalement localisé au niveau du télencéphale et associé au contrôle de l’apprentissage, la perception et la production du chant. Ce comportement a été décrit subir la modulation de facteurs externes, tels que la testostérone, la photopériode et les interactions sociales. En parallèle avec le comportement de chant, certains des noyaux appartenant au Système de Contrôle du Chant (HVC, RA et Area X) présentent un phénomène de plasticité saisonnière nerveuse fascinante. Le volume de ces noyaux augmente notamment par espacement des cellules, agrandissement de la taille du neuropile et de l’arborisation dendritique et, dans le cas particulier d’HVC, par incorporation de neurones nouveaux-nés. Nous proposons ici une synthèse de la littérature concernant ce phénomène tout à fait particulier ; en effet, la régénération des neurones du système nerveux central est considérée comme inexistante -ou uniquement limitée à la production de quelques interneurones- chez les mammifères. L’étude de la neuroplasticité chez l’oiseau chanteur constitue dès lors un modèle tout à fait remarquable et offrant des perspectives nouvelles dans l’étude du cerveau des vertébrés. [less ▲]

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See detailSynthesis and stabilization of colloids for optical and magnetic detections
Aqil, Abdelhafid ULg

Doctoral thesis (2008)

The development of nano-sized particles is motivated by their optical, electronic and magnetic behavior related to quantum confinement resulting from the nanometric size. To prevent aggregation in ... [more ▼]

The development of nano-sized particles is motivated by their optical, electronic and magnetic behavior related to quantum confinement resulting from the nanometric size. To prevent aggregation in solution, the nanoparticles are covered with stabilizing molecules. The aim of this thesis is to develop a new generation of functional copolymers with different architectures to improve the stability of various synthesized NPs. Two types of nanoparticles are considered, gold NPs for the optical properties and iron oxide NPs for the magnetic properties. The copolymers considered in this study are synthesized following a controlled radical polymerization process, i.e. Reversible Addition - Fragmentation Chain Transfer (RAFT) and confer novel properties to the coated nanoparticles. Stealth NPs are obtained when they are covered by the poly(ethylene oxide), and thermosensitive NPs when they are stabilized by the poly (N-isopropyl acrylamide). These properties have been exploited in applications in the biomedical field. Another challenge in this work is the synthesis and functionalization of the surface of carbon NPs, and thus carbon nano-capsules were synthesized by graphitization of poly (acrylic acid)-poly (acrylonitrile) micelles and carbon nanotubes have been decorated by magnetite NPs allowing their orientation in a magnetic field. [less ▲]

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See detailPolitiques d’approvisionnement dans les systèmes à plusieurs fournisseurs et Optimisation des décisions dans les chaînes logistiques décentralisées
Arda, Yasemin ULg

Doctoral thesis (2008)

Coordinating product flows between the partners of a supply chain is a difficult task because of random variations in demand and supply processes and the antagonistic nature of the individual economic ... [more ▼]

Coordinating product flows between the partners of a supply chain is a difficult task because of random variations in demand and supply processes and the antagonistic nature of the individual economic objectives of the partners. This study concentrates on the management of interorganizational product flows in supply chains. Two approaches are analyzed with the aim of improving performances of production/inventory systems controlled by base stock type product flow control policies. In the first approach, the effects of multi-supplier strategies on the performances of supply chains are studied. It is shown that a multi-supplier strategy decreases the expected replenishment delay and the expected inventory holding and shortage costs. The second approach deals with the deviations from the set of supply chain optimal actions due to the decentralisation of decision rights in a two-stage supply chain. In the game theory framework, the partners play a two-stage game of the Stackelberg type. A coordination contract is proposed and it is shown that the optimal supply chain performance is achievable using the proposed contract. [less ▲]

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See detailEpidemiology and Genetics of Pituitary Tumours
Daly, Adrian ULg

Doctoral thesis (2008)

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See detailHerstelrecht en procedurele waarborgen
Lauwaert, Katrien ULg

Doctoral thesis (2008)

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See detailDroit de la construction et de la promotion immobilière en Europe. Vers une harmonisation de la protection du consommateur en droit de la construction?
Kohl, Benoît ULg

Doctoral thesis (2008)

Dans plusieurs Etats membres de l’Union européenne, des dispositions particulières ont été adoptées, en marge du droit de la construction et de la promotion immobilière, pour assurer une protection ... [more ▼]

Dans plusieurs Etats membres de l’Union européenne, des dispositions particulières ont été adoptées, en marge du droit de la construction et de la promotion immobilière, pour assurer une protection particulière au consommateur dans le secteur du logement. Pour un juriste européen, cette observation conduit à s’interroger sur les perspectives d’harmonisation du droit de la construction et de la promotion immobilière, puisque la politique de protection des consommateurs constitue désormais une compétence législative autonome de l’Union européenne. Dans cet ouvrage, l’auteur, après avoir rappelé le contexte de l’harmonisation du droit privé dans le secteur de la construction, exprime sa préférence pour une harmonisation spécifique, limitée – du moins dans un premier temps – au seul secteur résidentiel. Aussi procède-t-il à la comparaison des mesures de protections dont bénéficie le consommateur, en droit de la construction et de la promotion immobilière, dans différents Etats membres de l’Union européenne ; une attention particulière est portée aux mécanismes d’autorégulation, qui, dans certains pays, résident au cœur de l’organisation de la protection du consommateur de la construction. L’auteur analyse l’impact de ces mesures ainsi que leur intégration dans l’acquis communautaire, de manière à pouvoir dégager des principes communs en matière de protection du consommateur européen et à formuler, de lege ferenda, des propositions d’harmonisation. La faisabilité d’une telle harmonisation par le recours à la méthode de corégulation est également analysée et certaines pistes nouvelles sont tracées dans cette perspective. L’ouvrage, prochainement publié aux éditions Bruylant (Bruxelles) et L.G.D.J. (Paris) est issu de la thèse de doctorat en sciences juridiques que l’auteur a soutenue à la Faculté de Droit de l’Université de Liège en 2008. [less ▲]

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See detailIn vitro characterisation of dietary fibre fermentation in the pig intestines and its influence on nitrogen excretion
Bindelle, Jérôme ULg

Doctoral thesis (2008)

Increasing attention has been paid to dietary fibre (DF) fermentation in the large intestine of pigs during the past years in pig nutrition. The bacterial growth supported by DF intestinal fermentation ... [more ▼]

Increasing attention has been paid to dietary fibre (DF) fermentation in the large intestine of pigs during the past years in pig nutrition. The bacterial growth supported by DF intestinal fermentation induces a shift of N excretion from urea in urine to bacterial protein in faeces that reduces NH3 emission from the manure. The objective of this thesis was to investigate the relationship between DF fermentability, intestinal bacteria growth and the N excretion. In the first part, an in vitro gas-test method using a living bacterial inoculum developed for ruminants was adapted to the pig. The use of pig colonic content was compared to faeces for the preparation of the inoculum and it was concluded that faeces could replace intestinal content, avoiding the use of cannulated animals. Secondly, the influence of a pespin-pancreatin hydrolysis prior to the fermentation in order to simulate digestion in the stomach and the small intestine was demonstrated. Finally, the influence of the faeces donnor bodyweight and the dietary fibre content of its diet on the gas production kinetics was shown. When studying a topic related to a specific category of pig, it is recommended to use animals from the same category as faeces donors to prepare the inoculum. In the second part of the thesis, the amount of protein synthesis (PS) by faecal microbes fermenting different sources of purified carbohydrates, or ingredients differing in DF content, was measured using 15N-labelled NH4Cl in the inoculum. PS ranged between 9.8 and 22.9 mg N g-1 fermented carbohydrate according to the rate of fermentation of the carbohydrate and its soluble fibre content. These in vitro observations were confirmed through in vivo experiments with diets containing increasing levels of soluble DF: in vitro PS passed from 1.51 to 2.35 mg N g-1 diet while in vivo urinary- N:fecal–N excretion ratio decreased from 2.171 to 1.177. [less ▲]

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See detailCorrosion atmosphérique des bronzes et Spectroscopie Mössbauer.
Sougrati, Moulay Tahar ULg

Doctoral thesis (2008)

The aim of this work is to improve our understanding of the atmospheric corrosion of bronzes. This work focuses on three axes: - The characterization of tin compounds expected in atmospheric corrosion ... [more ▼]

The aim of this work is to improve our understanding of the atmospheric corrosion of bronzes. This work focuses on three axes: - The characterization of tin compounds expected in atmospheric corrosion. The Mössbauer spectroscopy which has been the main tool in our multianalytical approach, allows selective and quantitative analysis. The Mössbauer parameters and f-factors have been determined for many tin oxides, chlorides and sulfates. The f-factors are different from a compound to another and highly T-dependent which justify low temperature Mössbauer measurements. - The development of a low temperature CEMS detector to permit low temperature and non-destructive surface analysis. The detector operation has been optimized for various gases between 41 and 300 K. - The 2-years outdoor exposure in an urban site including CuSn9, CuSn3Zn9 bronzes, CuZn33 brass and pure metals. The corrosion and runoff rates have been investigated as well as the role of alloying elements in corrosion process. [less ▲]

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See detailThermo-plasticity of fine-grained soils at various saturation states: Application to nuclear waste disposal
François, Bertrand ULg

Doctoral thesis (2008)

Soil is a particulate material that may undergo irreversible strain as the relative positions of the constituent particles change. That irreversible behaviour may be induced not only by an external stress ... [more ▼]

Soil is a particulate material that may undergo irreversible strain as the relative positions of the constituent particles change. That irreversible behaviour may be induced not only by an external stress variation but also by temperature or suction changes. The geomaterials that will be involved in the confinement of radioactive waste in deep geological formations will be submitted to strong thermal, hydraulic, and mechanical modifications. Those modifications may produce a significant change of the characteristics of the confinement barrier. A safety assessment of such facilities must be performed that considers the potential thermo-plasticity effects in the confining soil. Following the need for understanding and quantifying such effects, a constitutive model that deals with the thermo-mechanical modelling of unsaturated soils is proposed. In light of elastoplasticity, this model is based on the relevant temperature and suction effects on the mechanical behaviour of fine-grained soils, as observed in experiments. In addition, an experimental program has been undertaken in order to corroborate and to extend the existing results. Finally, the developed constitutive model has been properly implemented in a finite element code in order to study the behaviour of the soils that confine the nuclear waste. Therefore, this work addresses the issue from three different directions: a constitutive, experimental, and numerical point of view. (i) Constitutive study. The elaboration of a thermo-plastic constitutive model for unsaturated soils is done in a systematic manner. Starting from a hardening plasticity model for isothermal and saturated conditions, the constitutive relations are progressively extended to non-isothermal conditions and then to unsaturated states. For the more advanced model, a generalized effective stress framework is adopted, which includes a number of intrinsic thermo-hydro-mechanical connections, to represent the stress state in the soil. Two coupled constitutive aspects are used to fully describe the soil behaviour. The mechanical constitutive part is built on concepts of bounding surface theory and multi-mechanism plasticity, while water retention characteristics are described using elasto-plasticity to reproduce the hysteretic response and the effect of temperature and dry density on the soil's water retention properties. The theoretical formulation is supported by comparisons with experimental results. (ii) Experimental study. Aiming at a better understanding of the non-isothermal mechanical behaviour of unsaturated soils, a series of oedometric compression tests under controlled temperatures and suction conditions has been carried out on a silty material. The characteristics and the calibrations of the experimental apparatus are presented. The main results are interpreted in light of the proposed constitutive framework. The compressibility of the soil tested appears not to be affected by the temperature, but it decreases with a suction increase. As far as the preconsolidation stress is concerned, the results show a decrease of the yield limit with increasing temperature, while a suction increase tends to enhance this limit. Finally, an analytical expression is proposed to describe the evolution of the preconsolidation stress with respect to temperature and suction. (iii) Numerical study. In the issue of nuclear waste disposal, the quantification of the temporal and spatial distributions of the thermo-hydro-mechanical phenomena that occur in the confining soils requires that numerical simulations be carried out under imposed boundary conditions. To this end, the last part of this work presents finite element modelling results of several in-situ or laboratory simulation tests through using the developed constitutive model that was implemented in an advanced finite element code. The parameters of the different materials involved in the simulated experiments are determined by means of an extensive literature analysis on their thermal, hydraulic, and mechanical characteristics. The simulation results are interpreted in light of the elasto-thermoplasticity of saturated and unsaturated soils, which emphasizes the significant role of thermo-plastic processes in the global thermo-hydromechanical response of the confining materials. In that sense, this work supplies, in a systematic and progressive manner, constitutive explanations that may help to provide a better understanding of what the effects of thermo-plasticity in soils involved in the confinement of nuclear waste are. [less ▲]

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See detailStructure et ontogenèse des comportements de banc chez deux poissons Cichlidés: approche quantitative par l'utilisation du vidéotracking automatisé chez Oreochromis niloticus et Pelvicachromis pulcher.
Delcourt, Johann ULg

Doctoral thesis (2008)

Structures and ontogeny of schools in two cichlid fishes: quantitative approach with computerized videotracking systems in Oreochromis niloticus and Pelvicachromis pulcher. by Johann DELCOURT (Behavioural ... [more ▼]

Structures and ontogeny of schools in two cichlid fishes: quantitative approach with computerized videotracking systems in Oreochromis niloticus and Pelvicachromis pulcher. by Johann DELCOURT (Behavioural Biology Unit, Ethology and Animal Psychology, University of Liège, Belgium) The research works presented in this thesis, using new ethometric techniques based on digital imaging analysis, concerns several questions relating to the study of shoaling and schooling behaviours in early stages of life in two Cichlid species. Our two model species, the Nile tilapia (Oreochromis niloticus L.) and Pelvicachromis pulcher, are respectively a mouthbreeder and a substrate breeder. These reproductive and parental strategies have a direct impact on the ontogeny of fry. In this study, we have worked at understanding the impact of these strategies on the ontogeny of shoaling and schooling behaviours. The characterization of these behaviours needed the elaboration of new videotracking systems able to track individually a large number of fish, and the analysis of the spatial and dynamical structure of the group. After an extensive general introduction devoted to the shoaling and schooling behaviours in regards of the ethological study plan, we present our works in three major goals. These three topics concern: 1. Lab works using some classical methods of direct observation and a technique of computerised vision systems (Ethovision®). Moreover, Laboratory studies of fish groups were conducted to develop a new multitracking system, in collaboration with the G.R.A.S.P. (ULg), able to track a large number of unmarked individuals (up to 100 fishes) during several minutes. Thanks these two tracking systems, we studied the fry behaviours at the individual and the groups levels. 2. The emergence conditions of these behaviours. Are the fry able to adopt these behaviours in absence of parents, in absence of external stimuli? In this context, we described the spatial and dynamical (local and global) structures of groups to understand the mechanisms allowing the existence of schools. 3. The ontogeny of shoaling and schooling behaviours in the two model parental species. The first part exposes research devoted to the application, development and validation of the use of two videotracking systems (presented in the material and methods section). The advantages, capacities and limits of these systems are presented. The work concerning the emergence (the mechanisms) and the ontogeny are presented in scientific paper format in the “Results” section. A large general discussion centred on the three major goals (development of new ethometric tools, the structures and mechanisms of schools and the ontogeny of shoaling and schooling behaviours) concludes this PhD dissertation. [less ▲]

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See detailConception et réalisation d'un dispositif interférométrique de shearographie. Application en milieu diffusant.
Rosso, Vanessa ULg

Doctoral thesis (2007)

L’objectif de cette thèse était de concevoir et développer un dispositif expérimental réalisant des mesures dans la gamme micrométrique, qui soit compact, transportable et le plus stable possible pour la ... [more ▼]

L’objectif de cette thèse était de concevoir et développer un dispositif expérimental réalisant des mesures dans la gamme micrométrique, qui soit compact, transportable et le plus stable possible pour la réalisation de mesures in-situ. Ce projet a donc contribué à la conception et à la réalisation d’un dispositif interférométrique de shearographie qui constituera une base pour de futurs développements. Un interféromètre original de shearographie à chemins optiques quasi-communs et utilisant la technique du décalage de phase temporel a été présenté dans ce travail. L’élément clef du montage expérimental de shearographie est le dispositif de cisaillement (« shearing device », en anglais) : il s’agit d’un prisme qui sépare les états de polarisation TE et TM grâce à une couche mince polarisante et une fine lame de verre qui lui est accolée. Cet élément de cisaillement ainsi que l’utilisation d’une caméra CMOS et d’une cellule à cristaux liquide pour modulateur de phase, ont permis la réalisation d’un interféromètre compact, en ligne, relativement bon marché et à chemins optiques quasi-communs, lui conférant ainsi une grande stabilité par rapport aux perturbations extérieures. De plus, la sensibilité de cet interféromètre peut être ajustée pour différentes applications en modifiant la distance de cisaillement, par exemple en utilisant une lame de verre d’épaisseur différente accolée au prisme séparateur de polarisation. Des logiciels pour l’acquisition et le traitement des images ont également été développés afin de rendre le système simple d’utilisation et convivial. L’efficacité de cet interféromètre de shearographie a été prouvée dans le domaine mécanique et une application originale a été développée dans le domaine de la biophotonique. [less ▲]

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See detailL’Imaginaire des Pays-Bas dans la littérature française du XIXe siècle
Andringa, Kim ULg

Doctoral thesis (2007)

The imagination of the Netherlands comes close to a mythoid aggregate. The corpus transmits a superficial and picturesque imagery, based on tourist, pictorial and historical sources. The tourist ... [more ▼]

The imagination of the Netherlands comes close to a mythoid aggregate. The corpus transmits a superficial and picturesque imagery, based on tourist, pictorial and historical sources. The tourist conventions reinforce its stereotypical and anachronistic nature. The anachronism is also typical of the images borrowed from paintings of the Dutch school and a few art historians. Realism is most appreciated when poetically tinged, as with Rembrandt who reveals the boundary between dream and reality. History provides the authors with heroic or dramatic episodes, as well as with legends expressing national character or the struggle against the waters. At the dawn of the 20th century, the imagination of the Netherlands becomes more introspective. Societal changes and especially the industrialisation put the place of man in question. We have subjected three groups of images to a symbolical analysis. First, the group of miniaturised dwelling places, that express a unfulfilled desire for intimacy and a refuge out of time. Then, a group related to the painting as a mirror. These boundary images of an inaccessible space express the same disappointed desire. The sea images express progressive ideas as well as fear of mechanization at the same time. The illusion of the fantastic and the phantasmagoria make it possible to vanquish the setbacks suffered through the figures of intimacy. Against the industrialisation, against the changes of modern society, as well as against mass tourism, the author will oppose his imaginary experience of the world, and through his description will give a autoreferential image, revealing of his dreams and desires. L’imaginaire des Pays-Bas se rapproche d’un agrégat mythoïde. Le corpus véhicule une imagerie superficielle et pittoresque, construite autour de sources touristiques, picturales et historiques. Les conventions du tourisme en renforcent le caractère stéréotypée et anachronique. L’anachronisme caractérise aussi les images empruntées aux tableaux de l’école hollandaise et à quelques historiens de l’art. Le réalisme est surtout apprécié lorsqu’il est mêlé de poésie, comme chez Rembrandt qui révèle la frontière entre réel et rêve. L’Histoire fournit aux auteurs des épisodes héroïques ou dramatiques, et des légendes traduisant le caractère national ou la lutte contre les eaux. À l’aube du 20e siècle, l’imaginaire des Pays-Bas devient plus introspectif. Les changements sociétaux et surtout l’industrialisation remettent en cause la place de l’homme. Nous avons soumis trois groupes d’images à une analyse symbolique. D’abord celui des habitations miniaturisées, exprimant un désir d’intimité et de refuge hors du temps non satisfait. Le second se rattache à la peinture qui devient miroir. Ces images frontalières d’un espace inaccessible expriment le même désir déçu. Les images marines véhiculent à la fois des idées progressistes et la peur du machinisme. L’illusion du fantastique et de la fantasmagorie permet de surmonter les échecs rencontrés par les figures de l’intimité. À l’industrialisation, aux changements de la société moderne, au tourisme de masse aussi, l’auteur va opposer son expérience imaginaire du monde et à travers sa description, il va donner une image suiréférentielle révélatrice de ses rêves et désirs. [less ▲]

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See detailLe réveil de l’immatériel. La production onirique du patrimoine des Indiens Zápara (Haute Amazonie)
Bilhaut, Anne-Gaël ULg

Doctoral thesis (2007)

The Zapara Indians in the Upper Amazon are on the verge of disappearing from the linguistic map. This is a fact. And yet, their emergence within the political landscape in Ecuador (but not yet in Peru ... [more ▼]

The Zapara Indians in the Upper Amazon are on the verge of disappearing from the linguistic map. This is a fact. And yet, their emergence within the political landscape in Ecuador (but not yet in Peru), has provided them with a greater international visibility as an indigenous group. Most unusually, the accounts of dreams become one of the key elements of new forms of identity practices and identification processes – as those narrated here by two Zapara political leaders will attest. In search of their material and immaterial heritage, these leaders make use of the realm of dreams, using occurred dreams to orient their choices in the reconstruction of a collective memory. The dream, as a tool for engaging in a regredient process or in the return into the past, provides the historical elements that the Indians will then re-inject into their present in order to construct new “traditions”. In this dissertation, I will be describing the mechanisms, the learning of, and the local theories concerning the experience of dreams. In order to be understood, the dream must first circulate, and must have an issuer as a point of departure. Dreaming is also the means for a privileged relationship between human and non- human beings. Throughout this thesis, various systems of memory will be examined based upon empirical data revealing of the dreamt experience, but also of daily life, such as new teaching methods, or the creation of artefacts, produced both by ancestors or contemporaries. These accounts will help us to understand this new process of “Zaparaisation”, which depends as much on a process of ethno-archiving than on ethno-museography, and which awakens the immaterial. [less ▲]

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See detailCaractérisation physiologique et biochimique du processus de vieillissement du tubercule de pomme de terre (Solanum tuberosum L.)
Delaplace, Pierre ULg

Doctoral thesis (2007)

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the ... [more ▼]

Potato seed tuber is considered as a model organ to study plant ageing. Besides, its physiological age greatly influences germination pattern and thus agronomical performance. In order to unravel the biochemical processes underlying ageing, potato seed tubers (cv. Bintje and Désirée) were stored at 4°C for 7 months and regularly sampled to assess both physiological and biochemical parameters. Physiological age markers (PAI, incubation period) evolution was measured and allowed us to define a reference frame more accurate than the chronological age. A correlation has also been established with the growth parameters (number of stems, duration before emergence). In parallel, two biochemical approaches allowed us to assay proteome and antioxidant system modifications occurring during ageing. Protein pattern evolution was assessed by DIGE after hot SDS extraction. During ageing, 93 spots were strictly up- or down- regulated while 4 others exhibited an abundance curve with a transient maximum. After manual picking of 43 selected spots based on their expression profile, 32 proteins were identified by MS/MS. Differentially expressed proteins are mainly involved in patatin catabolism, stress response, glycolysis, protein turn-over and lipid oxidation. A complementary targeted approach has then been set up based on the free radical ageing theory. SOD, CAT, APX and POX activities as well as ascorbate, glutathione, carotenoid and phenolic compound contents were measured during ageing. These data seem to indicate that the antioxidant system undergoes marked changes in response to an increased production of reactive oxygen species. However, no accumulation of oxidative damages has been observed on lipids and proteins. All these kinetic data allowed us to build an integrated ageing model. These results are discussed in the above-mentioned theoretical context. [less ▲]

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See detailThe synchronic layering of English size and Type noun constructions
Brems, Lieselotte ULg

Doctoral thesis (2007)

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See detailContribution au diagnostic et à la correction des carences en iode et sélénium chez les bovins
Guyot, Hugues ULg

Doctoral thesis (2007)

Deficiencies of selenium (Se) and iodine (I) are widespread in livestock all over Europe. They have an impact on the animals’ health. Since the clinical signs of the deficiencies are rarely pathognomic ... [more ▼]

Deficiencies of selenium (Se) and iodine (I) are widespread in livestock all over Europe. They have an impact on the animals’ health. Since the clinical signs of the deficiencies are rarely pathognomic, auxiliary exams, based on blood and milk samples are needed for the confirmation of the diagnosis. To evaluate the Se and I status, the plasmatic Se content, the erythrocytic glutathione peroxydase activity (GPX), and the inorganic plasmatic I (IIP) content are measured routinely. Other analyses, like e.g. the dosage of tri-iodothyronine (T3) or thyrotropine (bTSH) can be used. Once the deficiency is diagnosed, it can be corrected by several methods. The first aim of the study was to evaluate the zinc, copper, Se, and I status of Wallonian dairy and beef herds and to correlate their trace element status to their health. The trace element status of the herds with pathologies was less good than that of healthy herds. Further, more herds with pathologies had deficiencies when compared to healthy ones. Dairy herds had a better trace element status than beef herds. Se and I deficiencies are among the most important ones and have the most severe sequels. Therefore, the subsequent parts of the study focussed on these two trace elements. The second aim was the establishment of a technique for the dosage of bTSH and of reference values in healthy cattle. Reference ranges for bTSH and for thyroxine (T4) have been determined in healthy adult cows and in healthy calves. Thereafter, the next aim was to compare the concentration of bTSH in newborn calves with goitre to those obtained in healthy calves, in order to validate a diagnostic test for this pathology. The bTSH allowed the discrimination of the two groups and to approve the diagnosis of hypothyroidism in some of the calves. The threshold value of bTSH for the diagnosis of hypothyroidism in the newborn calf has been fixed at 35 µU/ml. The fourth aim was to compare the I (IIP) and Se (plasmatic Se, GPX) status as well as the thyroid status (bTSH, T4, T3, rT3) in dried pregnant cows and their calves and in non-pregnant cows, that received normal diet and a diet enriched in Se and I. In those receiving a Se and I enriched diet, the T4 and the bTSH decreased while the IIP, the T3, and the GPX activity increased. In the group that received a diet with normal Se and I contents, only the GPX activity increased. At birth, calves from mothers receiving the Se and I enriched diet, had a higher IPP content and GPX activity, and a lower bTSH concentration than calves from the other group. The last aim was to compare the effects of two different forms of Se (sodium selenite versus seleno-methionine) and two different doses of Se (0.1 versus 0.5 ppm) on the health and the Se status of Se deficient Belgian Blue cows and their calves. The first two groups of cows received a ration with 0.1 and 0.5 ppm, respectively, of Se in the form of sodium selenite (Na-Se 0.1 and Na-Se 0.5), while the third group received 0.5 ppm of Se in the form of seleno-methionine (Y-Se 0.5). The Se content of plasma, colostrum, and milk was higher in the cows of group Y-Se 0.5 when compared to the two other groups. The Se content of the plasma was higher in calves from group Y-Se 0.5 when compared to the two other groups. The daily weight gain of the Y-Se 0.5 group was higher than those of the group Na-Se 0.1. The incidence of diarrhoea among calves in group Na-Se 0.1 was higher than in group Y-Se 0.5. In conclusion, trace elements deficiencies are common in Wallonia and often they are multiple. They play a major role in the aetiology of multifactorial diseases diagnosed in the cattle herds. Deficiencies in Se and in I are most commonly implicated in clinical problems. The diagnosis of these deficiencies is determined by blood analyses. Therefore, the tests need to be differentiated according to their capacity to test the nutritional or the thyroid status. A simultaneous supplementation with I and Se, as well as the form of the supplemented Se, may modify the interpretation of the nutritional and the thyroid status. Better reproduction performances and a better health have been observed in herds with a normal trace element status. Furthermore, the advantage of the supplementation with Se in the form of seleno-methionine has been demonstrated in comparison to sodium selenite in deficient Belgian Blue cattle. This study opened numerous perspectives. The measurement of bTSH should be implemented in laboratories in order to offer it as a routine analysis to the practitioning veterinarian, who could use this tool in the framework of many diseases other than goitre. From a fundamental point of view, the dosage of deiodinases would allow the understanding of the regulation and of the synthesis of the thyroid hormones in bovines, and identifying the role of Se and I in this process. Finally, following the discoveries concerning the seleno-methionine, the effect of organic forms of other trace elements in bovine supplementation should be investigated. [less ▲]

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See detailApport de données d’ADN nucléaire à la Phylogénie et à la Biologie de la Conservation des Ursidae
Pagès, Marie ULg

Doctoral thesis (2007)

Currently, the Ursidae family includes eight bear species. They represent an unusual family within the order of the Carnivores because of their peculiar physiological adaptations related to hibernation ... [more ▼]

Currently, the Ursidae family includes eight bear species. They represent an unusual family within the order of the Carnivores because of their peculiar physiological adaptations related to hibernation. These physiological features, unique in the animal kingdom, make bear a unique model for medical research in full expansion because of its putative clinical applications. This point will be developed in introduction of this manuscript. Surprisingly, the phylogenetic relationships within the extant Ursid representatives remain unclear. In order to clarify their phylogeny, we sequenced 12 nuclear genes for all the Ursid species (nearly 8 kilobases corresponding to 6 genes implied in the pathway of the thyroid hormones, 3 genes specific to the sexual chromosomes, and 3 other autosomal genes). By concatenating these new data with those available in the sequence databanks, phylogenetic reconstructions (maximum likelihood and bayesian analyses) were carried out on a nuclear DNA dataset of 10 kilobases. It was then possible to refine the phylogeny of the Ursidae family. In addition, based on the study of the genes SRY (Sex determining region of the Y chromosome), ZFX/ZFY (Zinc Finger protein) and AMLX/AMLY (Amelogenine), we developed a reliable method to determine the sex of Ursidae based on the analysis of DNA extracted from non invasive samples such as hairs or faeces. If this tool has obvious implication for the conservation biology of Ursidae (most of the extant species are threatened with extinction), it also opens new prospects in palaeontology. This kind of analysis was indeed applied to samples of fossils of North African brown bears (Ursus arctos). The last chapter of this manuscript illustrates how the palaeogenetics can help palaeontology interpreting the variability of fossil forms. [less ▲]

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See detailSynthesis, characterization and applications of pH-responsive core-shell-corona micelles in water
Willet, Nicolas ULg

Doctoral thesis (2007)

ABC triblock copolymers self-organize into a wide variety of supramolecular structures in the bulk. However, their associative behavior in selective solvents has scarcely been studied. Within the search ... [more ▼]

ABC triblock copolymers self-organize into a wide variety of supramolecular structures in the bulk. However, their associative behavior in selective solvents has scarcely been studied. Within the search for new stimuli-responsive supramolecular architectures, our attention focused on a pH-responsive polystyrene-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymer. In addition to the synthesis of monodisperse spherical core-shell-corona (CSC) micelles, the reversibility and the cooperativity of the response to pH variations were studied, morphological transitions were induced and multi-responsive micellar gels were prepared. The micellization mechanism, the structure, the responsiveness and the internal organization of these new nanomaterials were investigated using a combination of transmission electronic microscopy, atomic force microscopy, light scattering, small-angle neutron and X-ray scattering, nuclear magnetic resonance and rheology. Finally, efforts were geared towards potential applications. The ability of PS-b-P2VP-b-PEO CSC micelles to encapsulate and release hydrophobic species was probed and gold nanoparticles were successfully synthesized within the P2VP layer of spherical and cylindrical micelles, which acted as nanoreactors. [less ▲]

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See detailSimulation et aide au dimensionnement des chaudières de récupération
Dumont, Marie-Noëlle ULg

Doctoral thesis (2007)

Heat recovery steam generators (HRSG) play a very important role in combined cycle (CC) power plants, where steam is generated from a gas turbine exhaust and supplied at the appropriate pressure and ... [more ▼]

Heat recovery steam generators (HRSG) play a very important role in combined cycle (CC) power plants, where steam is generated from a gas turbine exhaust and supplied at the appropriate pressure and temperature to steam turbines for further power generation. The power plants achieve an overall efficiency above 55% and are ideally suited for combined heat and power generation in utility systems. The performance of energy conversion is improved by reducing exergy losses which implies reducing the temperature difference between the combustion gas and the steam cycle. Thus recent HRSG designs include up to three pressure levels with reheat in the steam cycle for maximum energy recovery and the use of high pressure, high temperature superheater and reheater in CC plants. Super critical boilers are also conceivable. Since HRSG performance has a large impact on the overall efficiency of the CC power plant, an accurate simulation of the performance of the HRSG is necessary. We present a steady state HRSG model to support design and rating simulations of vertical units. The simulation model, called FELVAL, divides the boiler in its rows. The row model can also be divided several times following the tube length, to better estimate the fumes temperature distribution across the hot gas path. Another model, called SUFVAL, carries out the design as well as the automatic generation of the FELVAL units and all the needed connections. The log mean temperature difference (LMTD) method and the effectiveness-NTU (ε -NTU) method are alternatively used to compute the overall heat transferred in each part of the HRSG. The problem of convergence of boiler models with more than one row in parallel is discussed. Good initialisation of the different variables is crucial to obtain convergence. The models are tested on 2 references HRSG. The first one is an assisted circulation boiler that operates at 3 subcritical pressure levels. The second is a once through boiler able to operate above the critical pressure of water. These new models were introduced into a commercial software of data reconciliation (VALI of Belsim sa) already used by the engineering and design departments of a HRSG manufacturer. They thus have a general-purpose package enabling them to make design, data reconciliation and simulation with the same software. Moreover, the use of FELVAL model will enable them to simulate any type of boiler and to obtain informations on the change of the temperatures inside the heat exchangers. This information is crucial for well monitoring closely the operation of a boiler, and better understanding its behaviour. This knowledge improvement allows to limit the overdesign and the safety margins and to reduce the investment costs. [less ▲]

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See detailNonvisual brain responses to light exposure in human as assessed by functional magnetic resonance imaging
Vandewalle, Gilles ULg

Doctoral thesis (2007)

La lumière influence profondément la physiologie humaine, en plus de permettre la vision. Elle constitue le synchronisateur principal des rythmes circadiens et induit des effets physiologiques immédiats ... [more ▼]

La lumière influence profondément la physiologie humaine, en plus de permettre la vision. Elle constitue le synchronisateur principal des rythmes circadiens et induit des effets physiologiques immédiats. Ces effets concernent des fonctions non-visuelles telles que la régulation du rythme veille/sommeil, de la température corporelle, de fonctions endocrinologiques, de l’éveil et des performances. Plusieurs études de ces effets réalisées chez l’animal et chez l’homme ont montré l’implication d’un système de photoréception non-visuel sensible surtout aux courtes longueurs d’onde (~470nm ; bleu). Ce système utilise les photorécepteurs classiques (cônes et bâtonnets), en plus de cellules ganglionnaires rétiniennes (CGR) intrinsèquement photosensibles, et exprimant la mélanopsine. Ces CGR se connectent à de nombreux noyaux sous-corticaux et corticaux, ce qui suggère un rôle du système non-visuel dans de nombreuses fonctions cérébrales. Cependant, au delà de ces projections rétiniennes directes, les autres régions du cerveau impliquées sont très peu connues. Une étude en tomographie par émission de positons (TEP), réalisée à l’Université de Liège, a démontré que l’effet éveillant d’une lumière nocturne intense (>8000lux) pouvait moduler l’activité cérébrale liée à une tâche attentionnelle. Cette étude, ainsi que quelques données d’EEG, résume notre connaissance des mécanismes cérébraux impliqués dans le système non-visuel chez l’homme. De plus, la majorité des études sur ces effets ont été entreprises la nuit. Nous avons réalisé trois études en imagerie fonctionnelle par résonance magnétique (IRMf) utilisant des expositions lumineuses diurnes pour mieux caractériser le système cérébral non-visuel chez l’homme. L’IRMf bénéficie d’une meilleure résolution spatiale et temporelle que la TEP et permet la caractérisation d’activités cérébrales liées à un processus cognitif précis. La première étude met en évidence des réponses cérébrales liées à une tâche attentionnelle avant et après une exposition lumineuse intense (>7000lux) de 21min. L’amélioration de l’éveil subjectif induite par la lumière est liée à une augmentation de l’activité thalamique. De plus, la lumière augmente l’activité d’un réseau de régions corticales impliquées dans la tâche, prévenant les diminutions d’activités observées en obscurité continue. Ces augmentations déclinent en quelques minutes après l’arrêt de la lumière, en suivant des dynamiques diverses spécifiques à chaque région. Ces premiers résultats suggèrent que, via une modulation de l’activité de structures sous-corticales régulant l’éveil, la lumière peut promouvoir dynamiquement l’activité corticale de réseaux impliqués dans un processus cognitif non-visuel. La deuxième étude montre que de courtes expositions (18min) à des lumières monochromatiques (3x1013ph/cm2/s) bleues (470nm) ou vertes (550nm) affectent différemment les réponses cérébrales liées à une tâche de mémoire de travail. La lumière bleue augmente les réponses cérébrales ou, du moins, prévient les diminutions observées sous lumière verte dans des cortex pariétaux et frontaux impliqués dans la mémoire de travail, ainsi que dans le thalamus. Ces résultats montrent qu’une lumière monochromatique peut rapidement influencer les fonctions cognitives et suggèrent que ces effets sont induits via un système de photoréception qui utilise la mélanopsine. Ces résultats démontrent qu’une exposition lumineuse diurne peut moduler l’activité cérébrale non-visuelle liée à deux fonctions cognitives complexes. La lumière agit rapidement en fonction de la région cérébrale et de la longueur d’onde considérées. Les sensibilités aux différentes longueurs d’ondes suggèrent l’implication d’un système de photoréception utilisant la mélanopsine. XXX. Les résultats suggèrent également une implication étendue de la lumière dans la régulation des fonctions cérébrales chez l’homme et soutiennent son utilisation pour contrecarrer la somnolence diurne et traiter des désordres circadiens et psychiatriques. [less ▲]

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See detailL’interface neuro-immune et l’expression de la protéine prion cellulaire dans le cadre des maldies à prions. Une étude comparative des espèces bovine et humaine.
Defaweux, Valérie ULg

Doctoral thesis (2007)

Le tropisme cellulaire des prions infectieux diffère selon l’espèce animale, celui-ci est corrélé à la souche infectieuse et à des facteurs spécifiques de l’hôte. Par exemple, certains prions infectieux ... [more ▼]

Le tropisme cellulaire des prions infectieux diffère selon l’espèce animale, celui-ci est corrélé à la souche infectieuse et à des facteurs spécifiques de l’hôte. Par exemple, certains prions infectieux sont lymphotropiques, notamment en cas de scrapie chez les moutons et de variant de la maladie de Creutzfeldt-Jakob (vMCJ) chez l’homme. Par opposition, certains prions se caractérisent par un neurotropisme comme observé chez des patients Creutzfeldt-Jakob atteints de la forme sporadique ou chez des bovins atteints d’encéphalopathies spongiformes bovines (ESB). L’hypothèse de notre travail repose sur les observations suivantes : dans le cas du variant de la maladie de Creutzfeldt-Jakob et des encéphalopathies spongiformes bovines, l’agent responsable est identique, la voie d’inoculation et les lésions neurologiques le sont également, seul le tropisme de cette souche pour les organes lymphoïdes diffère. En effet, les amygdales, la rate et l’appendice sont infectieux chez l’homme. Par contre, l’infectiosité est surtout confinée au niveau du système nerveux chez le bovin. Lors d’une inoculation expérimentale par voie orale de l’agent responsable de l’ESB chez les bovins, les plaques de Peyer iléales sont les seuls tissus lymphoïdes infectieux. Notre hypothèse de travail est que des propriétés de l’hôte interviennent dans le tropisme de l’agent infectieux. Deux axes de recherche ont été envisagés afin de vérifier cette hypothèse :  L’analyse de la distribution des fibres nerveuses au sein des tissus lymphoïdes associés aux muqueuses (MALT) des espèces bovine et humaine  L’étude de l’expression de PrPc et de ses isoformes au sein des tissus lymphoïdes et nerveux des espèces bovine et humaine. Pour atteindre au mieux nos objectifs, il nous manquait un outil essentiel permettant la caractérisation spécifique des FDC bovines. En effet, aucun marqueur spécifique de ces cellules n’était commercialisé. Nous avons donc produit, en collaboration avec le Centre d’Economie Rural de Marloie, un anticorps monoclonal spécifiquement dirigé contre les cellules folliculaires dendritiques (FDC) bovines. Cet anticorps nous a permis d’étudier la distribution des FDC au sein des organes lymphoïdes bovins. Une attention particulière a été portée aux FDC isolées à partir des plaques de Peyer jéjunales (PPJ) et iléales (PPI). L’apparente différence d’infectivité de ces tissus lymphoïdes chez des bovins atteints expérimentalement d’ESB nous a conduit à comparer les capacités fonctionnelles des FDC isolées à partir de PPJ et de PPI. Ces observations sont décrites et discutées dans le chapitre 1. Dans le chapitre 2, nous avons établi une cartographie des fibres nerveuses au sein des amygdales, des plaques de Peyer iléales et jéjunales bovines de plusieurs catégories d’âge et ensuite comparé ce pattern d’innervation à celui des amygdales humaines; ceci permettra de pister les voies potentielles de neuro-invasion. Une attention particulière a été portée à l’interface cellules folliculaires dendritiques – fibres nerveuses. En effet, les FDC matures jouent un rôle prépondérant dans la pathogenèse des maladies à prion puisqu’en leur absence, une infection périphérique n’a pas lieu. De plus, la proximité entre fibres nerveuses et FDC est un paramètre intervenant dans la neuro-invasion; nous avons dès lors aussi analysé les contacts entre les FDC et les éléments nerveux. L’expression de la PrPc est une condition sine qua non pour la formation de PrPres. Cette protéine cellulaire sert probablement de récepteur pour son homologue infectieux mais sert surtout de substrat pour l’amplification de PrPres ; toute modification au niveau de sa synthèse pourrait entraîner un changement de la cinétique d’infection et pourrait expliquer l’apparente absence d’infectivité constatée au niveau du système immunitaire chez les bovins. L’expression tissulaire et cellulaire spécifique d’isoformes de la PrPc représente un facteur de l’hôte potentiellement capable d’influencer le tropisme cellulaire de l’agent infectieux chez l’humain et le bovin. Cette expression a été étudiée dans les systèmes MALT bovins et humains. Pour affiner notre étude, nous avons analysé, par des techniques de western-blotting, le glycopattern de la PrPc ainsi que l’expression de ses formes tronquées dans les tissus lymphoïdes humains et bovins mais également dans des populations cellulaires spécifiques, les lymphocytes et les FDC. Afin de vérifier si les isoformes de PrPc sont spécifiques aux tissus lymphoïdes, nous avons effectué une étude comparative du pattern de glycosylation et du ratio des formes clivées de PrPc, exprimés au sein de différentes régions du système nerveux central bovin et humain. Les résultats de ces travaux sont repris dans le chapitre 3. [less ▲]

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See detailPathogénie cellulaire et moléculaire du stress oxydatif dans l'ostéo-arthropathie dégénérative équine
Schneider, Nicole ULg

Doctoral thesis (2007)

L’ostéo-arthropathie dégénérative affecte fréquemment les chevaux, et particulièrement le cheval de trait ardennais (Lejeune et al., 2002). Les nombreuses recherches consacrées à cette pathologie montrent ... [more ▼]

L’ostéo-arthropathie dégénérative affecte fréquemment les chevaux, et particulièrement le cheval de trait ardennais (Lejeune et al., 2002). Les nombreuses recherches consacrées à cette pathologie montrent un phénomène inflammatoire et un déséquilibre entre la production des enzymes dégradant le cartilage et l’intensité du processus de régénération (Landoni et al., 1996). On observe donc des dégâts à la surface du cartilage : f ibrillation, érosion, ulcération, formation d’ostéophytes, sclérose de l’os sous-chondral et remodelage ostéochondral (Reboul et al., 1996). Tous les éléments anatomiques sont concernés, avec une libération de médiateurs par les chondrocytes et les synoviocytes : cytokines, métalloprotéases, prostanoïdes (Cadore et Donabedian, 1997), leucotriènes, et espèces activées de l’oxygène et de l’azote (RNOS : reactive nitrogen and oxygen species). La formation des RNOS est souvent invoquée en relation avec des phénomènes d’anoxie-réoxygénation cycliques, liés au trauma ou à la surcharge articulaire, à un épanchement ou à un oedème de la capsule articulaire. Les travaux consacrés à la production des RNOS dans l’articulation l’attribuent habituellement aux chondrocytes et des observations biochimiques récentes ont révélé une augmentation des concentrations sanguines d’un produit oxydé caractéristique de la dégradation du cartilage, signe d’un métabolisme oxydant intra-articulaire (Lejeune et al., 2007). Peu de travaux sont consacrés à l’étude directe d’une production d’espèces radicalaires par les chondrocytes et les synoviocytes. L’objectif du travail était donc d’étudier la capacité des chondrocytes et des synoviocytes articulaires équins à produire des RNOS sous l’effet de l’anoxieréoxygénation. Il nécessitait la mise au point d’un modèle de culture des chondrocytes équins (Sanchez et al., 2002), d’un modèle de culture des synoviocytes équins (Georgescu et al., 1988) et d’un modèle de co-culture chondrocytes-synoviocytes pour imiter les interactions entre ces deux types cellulaires dans l’articulation où les chondrocytes matures sont nourris par diffusion à partir du liquide synovial à basse tension en oxygène (Grimshaw et Mason, 2000). Pour induire l’activité oxydante, nous avons soumis les cellules en culture à plusieurs cycles d’anoxie-réoxygénation, sur base de l’hypothèse qu’un traumatisme aigu ou chronique peut modifier le débit sanguin dans la membrane synoviale et initier des cycles d’anoxie-réoxygénation (par oedème et hypoxie tissulaire transitoire), avec une production intra-articulaire de RNOS, capables de déclencher des dommages tissulaires participant au développement de la pathologie articulaire. Pour tenir compte des conditions en oxygène existant dans l’articulation et du rôle du glucose ajouté au milieu de culture dans la résistance à l’anoxie, les chondrocytes ont été cultivés avec des concentrations variables en glucose (0, 1 et 4,5 g/l de milieu), combinées aux tensions d’oxygène de 1 % (hypoxie), 5 % (équivalent à la normoxie in vivo) et 21 % (condition hyperoxique prise comme référence par rapport à la littérature internationale). L’étude du métabolisme oxydant est effectuée en mesurant la consommation d’oxygène [oxymétrie mesurant la réponse mitochondriale (Mouithys- Mickalad et al., 2002)], la production globale de RNOS [estimée par la mesure de l’éthylène, produit par l’attaque d’un substrat par les RNOS (Deby-Dupont et al., 2005)] et la production d’espèces radicalaires [par résonance paramagnétique électronique (RPE) couplée au « spin trapping »] [less ▲]

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See detailGlobalisation, communication et champ du pouvoir : une socio-économie comparée des structures actionnariales et dirigeantes des groupes de médias et des entreprises dans le domaine des Nouvelles Technologies de l’Information et de la Communication en Europe et aux États-Unis
Geuens, Geoffrey ULg

Doctoral thesis (2007)

Les « Nouvelles Technologies de l’Information et de la Communication » (NTIC) font aujourd’hui l’objet d’une abondante littérature, tant francophone qu’anglo-saxonne. L’objectif de la thèse était ... [more ▼]

Les « Nouvelles Technologies de l’Information et de la Communication » (NTIC) font aujourd’hui l’objet d’une abondante littérature, tant francophone qu’anglo-saxonne. L’objectif de la thèse était précisément de soumettre à l’analyse critique cette prolifération de discours le plus souvent clichés – associés, pour les uns, à la « société de l’information », pour les autres, à la « mondialisation » de l’économie – qui forment presque un discours social à part entière, et dont l’un des traits communs est notamment de révoquer en doute, à l’exemple des phénomènes examinés sous le point de vue qu’ils adoptent, les principaux référents théoriques d’antan. Les « idéologèmes » véhiculés par ce discours social, on l’a montré, relèvent pour l’essentiel de trois grandes catégories particulièrement saillantes, organisées en l’occurrence sous la forme de trois binômes largement reçus, qui tendent à fonctionner comme des structures de pensée communes : a)Privatisation/désétatisation. La croyance en l’omnipotence des communications de masse va, le plus souvent, de paire avec la thèse du déclin présumé de l'Etat-nation ; les « nouveaux médias » et les NTIC libéralisés ayant, dit-on, acquis leur autonomie et plaçant nos sociétés à l’enseigne du réticulaire marchand. La « nouvelle économie » en réseaux se serait définitivement libérée de la tutelle politique, pour le meilleur (dynamisme, efficacité, compétitivité) comme pour le pire (marchandisation, affaiblissement de l’État, soumission du politique), selon le point de vue adopté à l’égard de ces évolutions données pour inévitables ; b)Mondialisation/déterritorialisation. L’internationalisation des structures de pouvoir des groupes de communication entretient une relation organique avec la dépolitisation du secteur. C’est que l’explication majeure de la disjonction État/médias réside, justement, dans la logique de dissociation croissante entre l’espace démocratique national et les réseaux technologiques mondiaux. Les nouveaux conglomérats de l’information s’identifieraient alors à des géants transnationaux apatrides et déterritorialisés. Quant à la « financiarisation » des industries culturelles, elle annoncerait la fin des actionnaires de références nationaux et l’avènement parallèle d’une nouvelle économie s’appuyant sur une multitude de petits porteurs disséminés aux quatre coins de la planète dont les investisseurs institutionnels constituent, en quelque sorte, le modèle le plus abouti ; c)Libéralisation/dérégulation. La « dépolitisation » et la « globalisation » des industries technologiques auraient instauré un marché débarrassé des entraves et des privilèges associés aux anciens opérateurs publics. Décidées au nom du libéralisme économique, les réformes de dérégulation adoptées dès le début des années 80 auraient ainsi abouti à la décomposition des antiques monopoles et à la mise en concurrence d’entités industrielles isolées les unes des autres. Quant aux conquérants de la Silicon Valley, Media Moguls et autres Tycoons, ils seraient en quelque sorte les effigies suprêmement individuelles de cette métamorphose du « capitalisme numérique » : autant de managers déracinés, dépeints comme d’infatigables compétiteurs apolitiques, engagés dans une course féroce au gigantisme, n’ayant pas la moindre solidarité de classe et n’ayant pour seul moteur que la quête du profit à court terme. Les discours convenus touchant à la « société de l’information » et aux phénomènes de « globalisation », il nous faut en réalité les relativiser, sinon même les infirmer, à la lumière de nos observations et analyses. C’est que la « mondialisation » de l’économie doit en effet compter non seulement avec la permanence de particularismes nationaux dont témoignent les structures de détention et de contrôle des groupes de médias et des NTIC, mais également avec le fait que la très grande majorité des entreprises étudiées sont caractérisées par un rapport entre investisseurs résidents et non-résidents tournant très nettement à l’avantage des premiers. On peut ainsi affirmer que les « multinationales » de la communication n’existent pas. Souhaitée par les uns ou redoutée par les autres, mais proclamée par tous, la « financiarisation » des industries culturelles n’a pas, en effet, débouché sur la trans-nationalisation du capital dont elle se voulait, pourtant, annonciatrice. Le « marché global » de l’information demeure, à ce jour, une vue de l’esprit séduisante, mais scientifiquement non fondée, les réseaux technologiques n’ayant pu transformer les capitalismes en un marché mondial faisant fi des principaux référentiels d’antan tels que ceux de « propriété », de « classes sociales » et de « souveraineté nationale ». Quant au pouvoir des grands actionnaires traditionnels (familles, pouvoirs publics, etc.), il n’a pas non plus cédé face à la pression des fonds d’investissements anglo-saxons, mais s’est au contraire consolidé à cette haute finance ayant permis le lancement d’opérations de fusion et acquisition, sans précédent jusque-là, dans le secteur de la communication. La « globalisation » des réseaux informationnels ne s’identifie pas, enfin, à la régénérescence d’un libéralisme pur et parfaitement concurrentiel, mais à la réaffirmation de quelques-unes des caractéristiques les plus fondamentales des industries culturelles en régime capitaliste : concentration de la propriété des firmes, centralisation de l’économie nationale, fusion des intérêts bancaires et industriels, consolidation des principaux holdings et, enfin, imbrication des groupes financiers et de l’appareil d’Etat. On aurait tort cependant de se limiter à une approche strictement financière de ces phénomènes. La situation quasi monopolistique que connaissent certaines compagnies leaders dans le domaine de la presse ou des NTIC ne s’éclaire, en effet, véritablement qu’à la lumière de leur très forte centralité au sein des réseaux de pouvoir. La densité des relations que les firmes en question entretiennent avec l’appareil d’Etat, les principales entreprises industrielles et financières, et les plus influents groupes de pression et autres think tanks constitue à nos yeux la première des conditions garantissant la reproduction des positions dominantes occupées par ces sociétés privées sur leur marché respectif. Cette approche relationnelle du pouvoir économique est illustrée par la multiplicité des positions institutionnelles détenues par les dirigeants des entreprises médiatiques. Représentant autant de formes incarnées de relations sociales génériques entre Economie, Politique et Communication, les grands administrateurs, issus pour la plupart d’entre eux du secteur financier ou de la très haute fonction publique, peuvent être légitimement considérés, pour parler le langage un peu oublié d’un Gramsci, comme les intellectuels organiques de la fraction hégémonique du bloc au pouvoir. Ce qu’il faut, au total, rejeter dans la définition des médias en tant que « quatrième pouvoir » ou dans celle des réseaux numériques en tant que « nouveaux pouvoirs », c’est l’impensé théorique qui sous-tend cette représentation d’une industrie de la communication qui « globalisée », « libéralisée » et « dérégulée », se serait simultanément affranchie des territoires nationaux, des gouvernements et de la grande bourgeoisie d’affaires. Il n’est pas non plus conforme à la vérité des faits et de leur recoupement de penser que la classe dirigeante ne se servirait de la presse que comme vulgaire relais ou instrument de propagande. Tout semble plutôt se passer comme si le champ du pouvoir était invaginé dans le champ médiatique du fait de la circulation ininterrompue de certains agents sociaux privilégiés entre les divers sous-espaces constitutifs du champ du pouvoir (pouvoir économique, pouvoir d’Etat, pouvoir idéologique, etc.). [less ▲]

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See detailInfluence, information and item response theory in discrete data analysis
Magis, David ULg

Doctoral thesis (2007)

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See detailThe Problems and Challenges of Cambodian Rural Economy. Between New Governances and Peasant’s Realities. The Case of Kampong Thom Province
Diepart, Jean-Christophe ULg

Doctoral thesis (2007)

In Cambodia, agriculture and natural resources constitute a corner stone in the production systems of peasant families, who constitute the large majority of the rural population. Hence, in the perspective ... [more ▼]

In Cambodia, agriculture and natural resources constitute a corner stone in the production systems of peasant families, who constitute the large majority of the rural population. Hence, in the perspective of an important demographic growth and an increasing marketing of agricultural inputs and outputs, man-made management of ecosystems represent considerable economic, social and environmental challenges to Cambodian peasants. The study precisely focuses on the peasant’s ways to manage rural territories. It rests on a fundamental hypothesis, according to which peasant practices are environmentally sustainable, economically efficient (in terms of creation of added-values) and socially equitable in the distribution of these added-values. A multi-scale analytical framework that integrates different dimensions of natural resources management is established to check out and fine tune this fundamental hypothesis. A first analytical framework, given a priori, covers the entire province of Kampong Thom. The second analytical framework is determined by choice. It covers two communes, selected on the basis of agro-ecological and institutional criteria, which are representative of rural dynamics observed and detailed at the provincial level. The first part shows the intricate links between agro-ecological diversity and peasant’s production systems. It details the social relationships that liven up rural territories and shows how power relationships structure or affect peasant communities. The next part analyses the new choices for collective and individual action for the management of natural resources. It points out the very conflictive nature of previous forms of management and the internal contradictions of the new choices. The potential contribution of commune council in natural resources management is also examined from a legal and organisational point of view. Field works carried out at the level of two communes detail and complete this analysis. First of all, spatial analysis of land use change between 1992 and 2006 shows the growing importance of non-peasant stakeholders in rural development dynamics. The analysis shows that when the development of rural territories can be entirely controlled by peasant’s communities, the dynamics of change are rational and efficient. Peasant’s strategies are characterized by a large diversity of activities, that all have in common the cultivation of rain-fed rice. The access to forest or fisheries resources on public state land is triggered by household’s activities diversification tactics in the dry season. These modes of access and use of natural resources are critically detailed and put in the perspective of the establishment of community fisheries and community forestry schemes. Management of private agricultural land is characterized by the overwhelming importance of rice in the cropping systems. Technical itineraries for rice cultivation implemented by rural households are analyzed and their economic results are evaluated. Different economic rationalities are highlighted in relation to inputs productivity. Elements of productivity, efficiency and profitability are also apprehended in relation with the access to credit and land markets. This analysis allows revisiting the assumed self-regulating role of land markets to ensure the growth of the agricultural sector on the one hand, and the improvement in the access of land for more equity on the other hand. Eventually, the analysis done at the commune level are put into the perspective of new institutional choices for collective and individual action for natural resources management and propose, in fine, operational recommendations to support peasant’s ways to manage natural resources. [less ▲]

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See detailMathematical modeling of bone regeneration during fracture healing and implant osseointegration
Geris, Liesbet ULg

Doctoral thesis (2007)

Despite the extensive body of literature on bone regeneration, many questions remain on e.g. the regulatory mechanisms and potential treatment strategies of pathological regeneration cases. The hypothesis ... [more ▼]

Despite the extensive body of literature on bone regeneration, many questions remain on e.g. the regulatory mechanisms and potential treatment strategies of pathological regeneration cases. The hypothesis underlying this work states that mathematical models of bone regeneration can make a substantial contribution to this domain by proposing pathological regeneration mechanisms and designing therapies, which can subsequently be tested experimentally. In the first part of this work, existing mechanoregulatory and bioregulatory models of bone regeneration are implemented and applied to both implant osseointegration and fracture healing set-ups. A quantitative comparison with experimental results is performed. Thorough sensitivity analyses are carried out to assess the influence of various modelling aspects on the simulation outcome. Shortcomings of these models are identified and suggestions for improvements are made. In the second part of this work, a novel bioregulatory model of bone regeneration is developed in which several of the previously defined shortcomings are addressed. This model includes key aspects of the regeneration process such as intramembranous and endochondral ossification, angiogenesis and directed cell motion. The results obtained with this novel model are corroborated both qualitatively and quantitatively by comparison with experimental data for normal fracture healing. Cases of pathological fracture healing are simulated and experimentally testable therapeutic strategies are implemented. The last part of this work describes the establishment of a mathematical framework, based on the previously developed bioregulatory model, in which the regulatory influence of both biological and mechanical factors is combined. This is the first model of bone regeneration in which the coupling between mechanical loading and angiogenesis is made in an explicit and mechanistic manner. Several examples are given to illustrate the added value of this approach in simulating normal and pathological bone regeneration. In summary, this work demonstrates the potential of mathematical models in advancing the knowledge on bone regeneration and designing treatment strategies for pathological healing cases. [less ▲]

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