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See detailLes généralistes, la prévention et la promotion de la santé. Etat des lieux, attitudes actuelles et voies d’avenir
Vanmeerbeek, Marc ULg

Doctoral thesis (2014)

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health ... [more ▼]

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health was considered within its bio-psycho-social definition, and equity in health had to be maintained or improved in this process. Research questions: • What are general practitioners (GPs)’ representations of their role and actions in the Belgian preventive framework? (Chapter 2); • What factors can predict GPs’ involvement to a greater or lesser degree in this topic? (Chapter 3); • What are the published operating models about preventive health care and health promotion in primary care that can be used to formulate working hypotheses for the improvement of preventive clinical practice? (Chapter 4). • How to improve the connection between preventive health services, health promotion and the curative approach? (Chapter 5). Four studies are presented that illustrate the topic, as they were published (or under publication). Among the definitions of health, the weight of the structural determinants and the socio-economic context on health levels was stressed, while the weight of the health systems was gradually reduced to a lesser role. But patient education is still expected to help control the individual determinants of health. Primary care and general practice are adequately fit to a tailored approach of large populations. However, the physicians’ vocational training does not address integration of health promotion and curative practice. Meeting field GPs through individual semi-structured interviews allowed for a dialog that explored various aspects of the preventive health services delivery. Predisposing factors closely linked to the physicians’ personality appeared to be determinants. Organisational limitations and difficulties, and almost non-existent collective visions of the practice population were highlighted. To understand what shapes the behaviour of GPs in preventive healthcare delivery beyond statements, an attitude scale was devised. The analysis allowed the statements to be sorted into a four-factor model consisting of performance appraisal, guideline adherence, patient-centeredness & collaboration, and power sharing. The GPs’ attitudes towards preventative service delivery increased with multidisciplinary practice and decreased with seniority in the profession. A narrative literature review retrieved twelve models that address preventive health care and health promotion in primary care; these models helped formulate working hypotheses for the improvement the current situation. The models progressively integrated elements from the health promotion charters of the World Health Organisation and from the Commission on Social Determinants of Health. The following elements valued by health promotion could be integrated to preventive healthcare: empowerment of citizens, addressing community environment; increased involvement in local health professionals’ networks; and the integration of individual and collective approaches within the same health care facilities to simultaneously address individual customisation, efficiency and equity objectives. There was little room for patients in elaborating the models. Do GPs have the opportunity to develop the partnerships that are required to move to health promotion as proposed by these models? The trend toward quality assurance systems among health systems can contribute to the setting of structures and operating modes that are necessary. The quality cycle could be one of the tools used for that purpose. The quality criteria of primary care lead the way to a framework for integrating preventive health care and health promotion. • Comprehensive care addresses the bio-psycho-social environment of patients, considering patients as partners during the health care process. • Continuity of care challenges the managing of clinical data between members of a care team, thereby enhancing quality of care, patient safety and equity. • Integrated care involving caregivers and health promotion professionals will require adaptation of job description reference lists. The challenge created by these three quality criteria entails changes in GPs vocational training and necessitates a new definition of their specific tasks and skills. Such a challenge requires collaborative teamwork of the five members of Boelen’s “partnership pentagon”. The social accountability of medical schools should be fostered. [less ▲]

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See detailPRODUCTION DES CLADOCERES DANS LES BASSINS DE LAGUNAGE: MODELISATION ET ANALYSE DE RENTABILITE DE LEUR VALORISATION
Liady, Mouhamadou Nourou Dine ULg

Doctoral thesis (2014)

Face à l’urgence exprimée par la communauté internationale de trouver des solutions efficaces et durables à la crise sanitaire, due au manque d’accès à l’assainissement dans les pays du sud, la présente ... [more ▼]

Face à l’urgence exprimée par la communauté internationale de trouver des solutions efficaces et durables à la crise sanitaire, due au manque d’accès à l’assainissement dans les pays du sud, la présente thèse s’est intéressée à l’étude de la possibilité de promouvoir ce secteur à travers l’intégration, dans les projets d’assainissement, d’incitants financiers tels que la valorisation des cladocères qui se développent dans les bassins de lagunage. Pour ce faire, une approche méthodologique basée sur la modélisation (qui permet d’intégrer tous les processus et les variables qui concourent au fonctionnement des bassins de lagunage) a été adoptée pour non seulement améliorer les connaissances sur le fonctionnement de ces bassins, mais aussi estimer les productions des cladocères et leurs impacts sur l’épuration des eaux dans ces bassins. Ensuite, la rentabilité d’un avant-projet de valorisation des cladocères a été étudiée dans le contexte socio-économique du Bénin. Le travail a débuté par une revue de la littérature, s’est poursuivi par les calibrations des techniques utilisées pour estimer les biomasses de Daphnia pulex et des différents substrats utilisés. Les études de cinétiques et de stœchiométries des différents processus de conversion biochimique impliquant les cladocères, ainsi que l’étude de rentabilité de deux variantes de valorisation des cladocères, ont complété le travail. La stœchiométrie de chacun des différents processus de conversion biochimique a été décrite en commençant par démontrer que les biomoles appliquées dans le modèle "ModLag" et dans le RWQM1 sont bien applicables aux organismes étudiés dans la présente thèse puis, à défaut des équipements requis pour mesurer les paramètres stœchiométriques, en utilisant les valeurs proposées dans le RWQM1. Toutefois, des commentaires importants sur les mesures de ces paramètres, ont été effectués aux regards non seulement des pratiques en vigueurs en hydrobiologie d’une part et en biotechnologies (sur les cultures en continue sur chémostat notamment) d’autre part, vis-à-vis des besoins pour la modélisation. Des démarches méthodologiques ont été proposées. Les résultats obtenus des études cinétiques montrent que : - la cinétique de la croissance des cladocères sur les bactéries est décrite par un modèle de type Monod qui traduit une augmentation du taux de croissance en fonction des teneurs en bactéries, jusqu’à une certaine teneur en bactéries à partir de laquelle on observe une saturation de la croissance, - la cinétique de leur croissance sur les algues est décrite par un modèle qui traduit une inhibition de la croissance par de fortes teneurs en algues, - la cinétique globale de la croissance de D. pulex simultanément sur Scenedesmus sp. et E. coli est mieux décrite par le modèle de cinétique avec paramètre d’interaction, que par le modèle sans interaction. - les teneurs en cyanobactéries influencent la cinétique de la mortalité des cladocères. Ce travail est le premier, à notre connaissance à prendre en compte, en modélisation, la mortalité des cladocères du fait de la toxicité des cyanobactéries. Les résultats des analyses de stœchiométrie révèlent que : - Pour produire 1 g d’équivalent DCO de D. pulex, 5 g d’équivalent DCO de Scenedesmus sp., (ou d’E. coli) sont oxydés dont 0,77 sont convertis en matières organiques particulaires et, le reste (soit 3,23 équivalent DCO ou 65%) est oxydé (pour la production de l’énergie nécessaire au métabolisme) sous forme de CO2. - En conditions de respiration endogène (observée dans les bassins de lagunage, en période de surpopulation de cladocères par rapport aux ressources alimentaires disponibles), on assiste à un abattement de la DCO des daphnies exclusivement au profit de la production d’énergie pour le catabolisme. - Lorsque l’équivalent en DCO de 1 g de D. pulex meurt, 1,2 g de DCO de matières organiques particulaires sont produites dont 79% sont biodégradable. L’impact des cladocères sur l’épuration des eaux dans les bassins de lagunage peut ainsi être analysé de manière approfondie, à la fois au plan cinétique et stœchiométrique, à l’aide de la modélisation globale du système "bassin de lagunage" en complétant le "sous-modèle cladocère" proposé dans la présente thèse, au modèle de lagunage "ModLag" de l’unité "Assainissement et Environnement" et, en réalisant des simulations à l’aide du logiciel "WEST". L’essentiel du travail nécessaire pour la réalisation des simulations a été effectué et présenté dans le chapitre VIII; par contre, les simulations n’ont pas pu être finalisées avant le dépôt de la présente thèse dans les délais exigés, en raison d’un problème survenu sur "WEST". Elles le seront avant la défense publique de cette thèse et, les résultats pourront alors être présentés. En attendant, les analyses de cinétiques et de stœchiométries montrent que dans des conditions non limitantes en substrats et en absence de cyanobactéries, la vitesse de croissance des cladocères étant supérieure à la somme des vitesses de leur respiration et de leur mortalité, on assisterait plus à un abattement de la DCO essentiellement algale et bactérienne. Cela révèle que s’il est bien géré avec des récoltes périodiques, un étage trophique constitué de cladocères peut contribuer à accroître le rendement épuratoire en réduisant les biomasses d’algues et de bactéries en fin de traitement. Ces récoltes périodiques de biomasses de cladocères, permettront de maintenir un bon état de fonctionnement du système en évitant de trop réduire les biomasses d’algues et de bactéries qui assurent respectivement, l’oxygénation de l’eau et la minéralisation de la pollution organique dissoute avec un effet détoxifiant notamment à travers la nitrification de l’ammoniac. L’étude de rentabilité de l’avant-projet de valorisation des cladocères produits dans les bassins de lagunage révèle que, dans le contexte socio-économique du Bénin, avec une production journalière estimée à 1,19 g poids sec/m3.j : - la variante 1 consistant en une vente des récoltes de cladocères sous la forme de surgelés (ou de produits secs) est rentable et permet de réaliser un bénéfice annuel de l’ordre de 15.000 €/ha.an (si l’on considère la surface totale de l’exploitation), même en prenant en compte le remboursement sur une durée de dix ans des investissements dédiés à l’achat de terrains et à l’aménagement de la station d’épuration. - la variante 2 consistant en une valorisation sur place de la biomasse de cladocères, dans la production de poissons est également rentable mais seulement si les investissements pour l’achat de terres et les aménagements, n’étaient pas remboursés. Dans ces conditions, elle permettrait de réaliser un bénéfice annuel de 1629 €/ha.an (si l’on considère la surface totale de l’exploitation) ou 6803 €/ha.an (si l’on considère uniquement la surface du bassin de production). Cette étude a permis de : - mettre en exergue les insuffisances des modèles de la littérature, pour décrire la croissance des cladocères dans les bassins de lagunage, - bien cerner les substrats (algues et bactéries) qui contribuent à la croissance des cladocères ainsi que l’influence des teneurs de ces substrats sur la cinétique de leur croissance; - prendre en compte l’influence des cyanobactéries sur la cinétique de la mortalité des cladocères ; - apporter une importante contribution à la modélisation du fonctionnement des bassins de lagunage, en spécifiant clairement les modèles qui décrivent les cinétiques de croissance des cladocères sur les algues et les bactéries, et la cinétique de la mortalité des cladocères, en présence des cyanobactéries ; - proposer un sous-modèle qui traduit les processus de conversion biochimiques impliquant les cladocères ; - montrer que les récoltes raisonnables de cladocères contribuent à optimiser l’équilibre du système et ses performances épuratoires ; leur valorisation est financièrement rentable pour la gestion d’une station d’épuration, voire du secteur de l’assainissement. - montrer qu’il est possible de réaliser des marges bénéficiaires importantes à travers la valorisation des cladocères, et par conséquent, d’intégrer dans la conception des projets d’assainissements destinés aux pays du sud, des incitants financiers. Cela pourrait motiver les investisseurs à promouvoir ce secteur, et, accroître l’accès des populations à l’assainissement. [less ▲]

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See detailInnovative algorithms to combine phenotypic, genealogical and genomic information originating from diverse sources
Vandenplas, Jérémie ULg

Doctoral thesis (2014)

Along with technical developments, international exchanges of genetic material (e.g., frozen semen, embryos) have increased since the 1970s. However, genetic evaluations are traditionally based on ... [more ▼]

Along with technical developments, international exchanges of genetic material (e.g., frozen semen, embryos) have increased since the 1970s. However, genetic evaluations are traditionally based on phenotypic and genealogical data which are internally recorded, i.e., within well defined borders. Because imported (i.e., external) genetic material is usually strongly selected in their respective populations, internal genetic evaluations for external animals could be biased and less accurate if external data used for their selection is ignored. Moreover, comparison of internal and external animals based on their internal and external estimates of genetic merit is needed to select and potentially import the most suitable ones according to the internal breeding goal. However, such comparison is usually not possible among internal and external genetic evaluations due, e.g., to differences among units of measurement. Thereby, several approaches and algorithms have been developed to render internal and external genetic evaluations comparable, and to combine or blend phenotypic and genealogical data and external information, i.e., estimates of genetic merit and associated reliabilities. Furthermore, the recent development of genomic selection also increased needs for combining phenotypic, genealogical and genomic data and information. Therefore, the aim of this thesis was first to develop innovative algorithms to combine diverse sources of phenotypic, genealogical and genomic data and information, and second to test them on simulated and real data in order to check their correctness. Based on a Bayesian view of the linear mixed models and addressing several issues highlighted by previous studies, systems of equations combining simultaneously diverse sources of data and external information were developed for (multivariate) genetic and single-step genomic evaluations. Double counting of contributions due to relationships and due to records were considered as well as computational burden. The performances of the developed systems of equations were evaluated using simulated datasets and real datasets originating from genetic (genomic) evaluations for Holstein cattle and for show jumping horses. The different results showed that the developed equations integrated and blended several sources of information in a proper way into a genetic or a single-step genomic evaluation.It was also observed that double counting of contributions due to relationships and due to records was (almost) avoided. Furthermore, more reliable estimates of genetic merit were also obtained for external animals and for their relatives after integration of external information. Also, the developed equations can be easily adapted to complex models, such as multivariate mixed models. Indeed, it was shown that external information correlated to the internal phenotypic traits was properly integrated using the developed equations. Finally, research of this thesis led to the development of a genomic evaluation system for Holstein cattle in the Walloon Region of Belgium for production traits, as well as for other traits, like somatic cell score. Based on the research of this thesis, future research topics, e.g., concerning integration of correlated external information and of genomic information, were finally presented. [less ▲]

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See detailModélisation des processus physiques et biologiques dans des fosses septiques et voies de valorisation des boues de vidange:Application à Bujumbura-Burundi
Nsavyimana, Gaston ULg

Doctoral thesis (2014)

Dans les pays en développement (PED) en général et au Burundi en particulier, la problématique de gestion des eaux usées et des déchets solides constitue un enjeu majeur pour les spécialistes et les ... [more ▼]

Dans les pays en développement (PED) en général et au Burundi en particulier, la problématique de gestion des eaux usées et des déchets solides constitue un enjeu majeur pour les spécialistes et les autorités locales. En effet, suite à un manque des stations d'épuration collectives au Burundi, les fosses septiques sont les plus utilisées pour gérer les eaux usées produites. Cependant, les processus qui s'y déroulent ne sont pas encore maîtrisés et la gestion des boues de vidange lorsque ces installations sont remplies, constitue une problématique qui mérite d'être abordée afin de trouver des solutions adaptées, à court et à long terme. Et, suite à une absence des technologies appropriées en matière de gestion des déchets solides, ils sont jetés de manière inadmissible (dans les caniveaux, rivières, places publiques, etc.), et cela peut engendrer à court ou à long terme des nuisances graves, tant pour la santé et l'hygiène publique que pour l'environnement. C’est dans l’optique de contribuer: (i) à l'amélioration de la qualité environnementale; (ii) et à la réduction des risques sanitaires associés à la gestion des déchets liquides et solides à Bujumbura (Burundi), que s’inscrit ce travail de recherche qui porte sur la "Modélisation des processus physiques et biologiques dans des fosses septiques et voies de valorisation des boues de vidange: Application à Bujumbura-Burundi". Différents axes ont ainsi été abordés pour répondre a cet objectif général : (1) la quantification des processus physico-chimiques dans des fosses septiques; (2) la modélisation stœchiométrique, cinétique et mathématique des processus biochimiques; et (3) l'étude des voies de valorisation énergétique des boues de vidange, soit seules (en digestion anaérobie) ou combinées avec des déchets solides fermentescibles (en co-digestion anaérobie). L'étude de quantification des processus physico-chimiques, matérialisables par le phénomène de décantation des particules solides a permis de dégager deux résultats principaux: (i) les effluents d'entrée dans les fosses septiques présentent une bonne décantabilité; (ii) les effluents de sortie de ces ouvrages (107 mg MES/L) ne respectent pas les normes de rejets (30 mg MES/L: cas de la norme Belge). Des dispositifs appropriés pour le traitement des effluents de sortie des fosses septiques (lit filtrant drainé/ou non à flux vertical sur un massif de sable, lit filtrant drainé/ou non à flux vertical sur un massif de zéolithe, lit filtrant horizontal drainé, tertre d’infiltration, tranchée d'épandage ou lit bactérien percolateur) ont été proposés pour palier les insuffisances des puits perdants couramment utilisés au Burundi. L'étude de caractérisation des flux entrant dans des fosses septiques était indispensable pour les modélisations ultérieures (stœchiométrique, cinétique et mathématique) des processus biochimiques et a permis de quantifier, de manière revisitée, la notion d' un équivalent habitant. Ainsi, un équivalent habitant (EH) a été déterminé pour la Belgique et le Burundi en termes de la demande chimique en oxygène (DCO), soit 138,75 ± 20,09 gDCO/EH/j et 117,08 ± 10,09 gDCO/EH/j respectivement. De plus, cette étude a permis de caractériser, par rapport à un équivalent habitant, différents composés chimiques importants contenus dans les flux entrant dans les fosses septiques. Les résultats variaient entre 0,37 ± 0,18 g/EH/j (pour les acides aminés urinaires ) et 43,44 ± 4,35 g/EH/j ( pour glucides), avec des valeurs de 5,00 ± 0,3; 10,15 ± 1,96; 10,6 ± 3,27; 14,7 ± 0,4 et 14,99 ± 1,57 g/EH/j respectivement pour les savons de bain/douche, lipides, azote total, détergent pour lave-linge et protéines. Ces résultats ont contribué à l'élaboration d'une formule "de biomole de substrat complexe" (C23 H49O9N) représentant les eaux usées, utile pour simplifier la modélisation mathématique de fonctionnement des fosses septiques en réduisant le nombre de processus, de variables d’état, d’équations cinétiques associées et des paramètres qui en découlent. La modélisation stœchiométrique des processus biochimiques qui se déroulent dans les fosses septiques, après avoir vérifié que le métabolisme est bien anaérobie, même si des eaux usées éventuellement saturées en O2 entrent quotidiennement dans ce type de dispositifs, a permis de mettre en place un système d’équations qui décrit la stœchiométrie de fonctionnement des fosses septiques. Par ailleurs, dans les pays en développement comme le Burundi, les laboratoires sont moins équipés et ont un accès très limité aux équipements modernes d'analyse usuels (ex., GC ou HPLC ), pour le dosage des acides gras volatils (AGV). A cet effet, nous avons développé et vérifié une nouvelle méthode de dosage des AGV par titrage, efficace et proche de la méthode chromatographique en phase gazeuse. A 99% d'intervalle de confiance, les résultats obtenus à l'aide de cette nouvelle méthode, sont comparables à ceux de la chromatographie en phase gazeuse. La modélisation cinétique a permis de mettre en exergue un modèle de dégradation de la biomole du substrat complexe, qui s'est révélé comparable au modèle cinétique de Monod. Les constantes cinétiques découlant du traitement des données sont dans le cas présent: (i) le taux maximum de croissance spécifique (µmax) égal à 0,0065 j-1; (ii) la constante de demi-saturation de ce substrat combiné synthétique égale à 9,18 g DCO/l ou 4,26 g/l; et (iii) le taux de mortalité égal à 0,0001 j-1. Ces données sont très utiles pour les simulations de fonctionnement des fosses septiques à l'aide d'un logiciel de gestion des ouvrages de traitement des eaux usées (WEST®). Ce travail a également permis de développer un modèle global de fonctionnement des fosses septiques (MFS/DDA ), qui par ailleurs a été présenté suivant le formalisme matriciel de Petersen. Une étude préliminaire de caractérisation détaillée des boues de vidange a montré qu'elles sont presque stabilisées, du point de vue valorisation énergétique. Lorsqu'elles sont digérées seules, elles présentent un faible potentiel méthanogène, soit 2,09 m3 biogaz/m3 de boues fraîches (après deux mois de digestion). Ce biogaz est composé de 71% de CH4 contre 29% de CO2. Ce travail a montré un intérêt de co-digestion anaérobie des boues de vidange avec les déchets solides fermentescibles. A cet effet, un rapport MVSFS/MOVdéchets égal à 0,3 (MOVdéchets étant exprimées en poids sec de déchets et MVSFS en poids sec des boues de vidange) s’est révélé optimal , pour leur meilleure valorisation énergétique, avec une production cumulée maximale de biogaz égal à 12,14 m3biogaz/m3 de mélange gadoues-déchets. La composition moyenne de ce biogaz était de 65,6% en CH4 contre 34,4% en CO2. Mots Clés: Burundi; Assainissement; Fosses septiques; Eaux noires; Eaux grises; Equivalent habitant; Décantation; Digestion anaérobie; Substrat combiné; Acides gras volatils; Modèle stœchiométrique; Modèle cinétique; Matrice de Petersen; Simulations avec WEST®; Boues de vidange; Potentiel méthanogène; Co-digestion anaérobie; Déchets solides fermentescibles. [less ▲]

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See detailParticulate soils adherence and surface cleanability: influence of biomacromolecules at interfaces and of substrate hydrophobicity
Toure, Yetioman ULg

Doctoral thesis (2014)

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The ... [more ▼]

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The combination of particles and macromolecules substances appears in many processes. Adsorbed compounds from these mixtures may influence interactions at interfaces and thus fouling and cleaning. This thesis deals with a deeper understanding of the physico-chemical mechanisms affecting soiling and cleanability of open substrates in the presence of biomacromolecules (dextran, bovine serum albumin – BSA, beta-lactoglobulin – β-LGB). Model substrates were chosen according to their hydrophobicity. The influence of macromolecules was examined by introducing them in the quartz suspension taken as a model of hard hydrophilic soil used for soiling, or by conditioning the substrate prior to soiling. The substrates were pretreated with ethanol (-Eth.), piranha or UV-Ozone (-UVO); soiled by spraying the quartz suspensions, then dried, before cleaning assessment. The removal of the soiling particles was evaluated after exposure to water in a radial flow chamber (RFC). Auxiliary characterizations were surface tension and contact angle measurements, surface analysis of the substrate by X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM). The interpretation of XPS data allowed the complexity due to the ubiquitous presence of organic contaminants to be coped with, and the surface composition to be expressed in terms of both the amount of adlayer and the mass concentration of adlayer constituents. The contact of substrates with proteins led to their adsorption, which dominated the composition of the organic layer with respect to contaminants initially present, and was not markedly desorbed upon rinsing. Dextran was easily removed in presence of water, independently on the substrate nature. Surface hydrophobicity was shown to influence the morphology of the aggregates resulting from drying. The rounder aggregates formed on polystyrene when soiling was performed with suspension in pure water are more sensitive to wall shear stress than flatter ones formed on more hydrophilic substrate. This is the result of the competing processes of droplet rolling and coalescing, on the one hand, and droplet spreading, on the other hand. It affects the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning and finally, the adherence of soiling particles. The presence of proteins (either native or denatured) at the interface improved strongly the cleanability of more hydrophilic substrate (glass, StSteel-UVO). This is attributed to the lower surface tension. The dependence of cleanability on capillary forces, and in particular on the liquid surface tension, is predominant as compared with its dependence on the size and shape of the soiling aggregates, which influence the efficiency of shear forces exerted by the flowing water upon cleaning. The cleanability of less hydrophilic substrate (stainless steel only pre-cleaned with ethanol) did not change markedly in the presence of proteins; this may be due to a more complex interaction between surface tension and contact angle, on one hand, and a more complex interaction between proteins and contaminants, on the other hand. The presence of dextran did not affect the cleanability, as neither the liquid surface tension nor the contact angle was appreciably affected. [less ▲]

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See detailMise au point d'une forme stable de l'allergène Der p 3 de Dermatophagoides pteronyssinus pour le diagnostic rapide et le développement de nouvelles approches d'immunothérapie de l'allergie aux acariens
Bouaziz, Ahlem ULg

Doctoral thesis (2014)

L’allergie aux acariens touche 20 à 30 % de la population occidentale. L’allergène Der p 3 de l’acarien Dermatophagoides pteronyssinus est une protéase à serine active appartenant à la famille de la ... [more ▼]

L’allergie aux acariens touche 20 à 30 % de la population occidentale. L’allergène Der p 3 de l’acarien Dermatophagoides pteronyssinus est une protéase à serine active appartenant à la famille de la trypsine. Son activité protéolytique pourrait être un facteur adjuvant impliqué dans le développement et la chronicité de l’allergie. A l’heure actuelle, l’implication de Der p 3 dans l’allergie est peu connue et son taux de fixation des IgE provenant de patients allergiques est controversé. Cependant, ces différentes études ont été réalisées au moyen d’un allergène naturel très sujet à l’autolyse et pouvant être contaminé par d’autres protéase. Durant la première partie de cette étude, nous avons pu montrer que rDer p 3 produit en P.Pastoris présente les mêmes propriétés allergéniques que nDer p 3. En effet, les résultats obtenus par test ELISA, inhibition compétitive montrent que rDer p 3 est correctement replié et présente les mêmes épitopes B conformationnels que l’allergène naturel. Dans la deuxième partie de cette thèse, nous avons pu mettre en évidence que l’autolyse de Der p 3 durant le test ELISA a un effet sur la reconnaissance des IgE. En effet, le taux mesuré avec la forme inactive est deux fois supérieur par rapport à la forme active. Der p 3S196A pourrait être donc un meilleur outil de diagnostic pour l’allergie à Der p 3. Dans la troisième partie de cette thèse, nous avons pu montrer que le propeptide de proDer p 3 affecte l’allergénicité de Der p 3. Par une étude in vitro, nous avons prouvé par ELISA, par les tests de dégranulation des basophiles de rat humanisés et d’activation des basophiles humains, que proDer p 3 est moins bien reconnu par les IgE de patients allergiques que la forme mature Der p 3. Ensuite, nous avons montré que les souris sensibilisées par les formes mature et zymogène de l’allergène Der p 3 ont développé une réponse immune de type TH2 et TH1 respectivement. ProDer p 3 pourrait donc être considéré comme une forme hypoallergénique de l’allergène Der p 3. Dans la dernière partie, nous avons construit un modèle tridimensionnel de l’allergène Der p 3 afin de prédire les épitopes B conformationnels par approche bioinformatique. En effet, 3 épitopes B ont été prédits ainsi que les acides aminés impliqués dans la reconnaissance et la fixation des IgE au sein de chaque épitope. Enfin, au moyen de la technique du peptide array, nous avons pu mettre en évidence un épitope B linéaire de l’allergène Der p 3. [less ▲]

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See detailLa promotion de l’activité physique chez les seniors : approche au sein d’une communauté locale
Mouton, Alexandre ULg

Doctoral thesis (2014)

In our contemporary society, get moving is rarely necessary to perform our daily routine. Consequently, physical inactivity is currently considered as the fourth cause of premature death worldwide. Faced ... [more ▼]

In our contemporary society, get moving is rarely necessary to perform our daily routine. Consequently, physical inactivity is currently considered as the fourth cause of premature death worldwide. Faced with an aging population, involving a doubling of the people aged 60 years and over in 2050, physical activity promotion could contribute to preserve individual health in supporting people to adopt an active lifestyle. Our personal contribution aimed at developing an appropriate physical activity promotion intervention at a local level. The Introduction chapter theoretically legitimate the need to implement new interventions, especially at a local level. In this thesis, we focused our attention on a particular Belgian French-speaking municipality, Esneux, in order to develop a structured and evidence-based physical activity promotion process. The Planned Health Promotion model guided this local approach. The Chapter 1 of our contribution aimed at analysing the local context in terms of physical activity behaviours in the population and opportunities to be physically active in the municipality environment. As observed on a larger scale, the results of this survey exposed that the majority of the participants did not respect the official recommendations for physical activity. Because participants aged 50 years and over were on average less active than younger participants, we developed a local intervention dedicated to seniors in Chapter 2. The purpose of this chapter was to assess the relevance of an original web-based physical activity promotion intervention addressed to older adults. The presented literature review and pilot study highlighted the suitability of such an approach for seniors, on condition that it includes a local perspective and a sufficient social support. The aim of the study presented in Chapter 3 was to compare the long-term effects of three different physical activity promotion interventions’ conditions implemented at the municipality level on physical activity behaviour and knowledge of older adults. Participants took part in a web-based intervention, a group-based intervention or a combined intervention during three months. Leading to significant improvements of the physical activity behaviour, but also of the knowledge about physical activity in general and regarding to the local opportunities, the combined approach could be considered as the most appropriate for a local level dissemination. The study presented in Chapter 4 specified the interest of a local environment-centered approach for physical activity promotion among older adults. This study underlined the mediating role of the perception of the local opportunities to be physically active and of the perception about the quality of the environment for physical activity on the intention-behaviour relationship. In the General discussion, we provide a critical look to each step of our local physical activity promotion approach and suggest potential avenues for future research in the field. [less ▲]

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See detailOrigines développementales des anomalies de l'homéostasie glucidique, de la croissance osseuse et prédisposition à l'ostéochondrose chez le poulain
Peugnet, Pauline ULg

Doctoral thesis (2014)

Fetal adaptations to intra-uterine stimuli have immediate and long term effects on the offspring’s health after birth. In equids, this concept known as the DOHaD (Developmental Origins of Health and ... [more ▼]

Fetal adaptations to intra-uterine stimuli have immediate and long term effects on the offspring’s health after birth. In equids, this concept known as the DOHaD (Developmental Origins of Health and Disease) was validated using crossbreeding: the mare’s size which affects the fetal environment throughout gestation and then lactation, has a critical impact on the foal’s post-natal growth, as well as on the neonate’s sensitivity to insulin. Osteochondrosis, a pathology of the growing horse, induces heavy financial losses in the equine industry. It has been associated to abnormalities in glucose homeostasis and its antenatal origin is highly suspected. The present research aimed to evaluate the impact of experimental disturbances during fetal development on growth, glucose homeostasis and predisposition to osteochondrosis in the foal until age 1½ year. Increased versus restricted fetal growth was obtained using between-breed embryo transfers (“ponies in draft horses” versus “saddlebreds in ponies”, respectively). The lush environment of the draft mare versus the restricted environment of the pony mare turned out to be critical in the regulation of bone growth, thyroid hormones secretion, β-cells function, insulin sensitivity and the osteoarticular status of the foal from birth to 1½ year of age. This validates the concept of the DOHaD in equids and shows that recipient mares should be carefully selected in embryo transfer practice. By demonstrating the scope of post-natal effects which were programmed in utero and throughout the lactating period, it also alerts the breeder about the importance of broodmare management and its long term impacts. Thus, the second model was developed to address breeders' practices. A disturbance of the nutritional environment of the fetus was induced by supplementing mares in late pregnancy with concentrated feed (barley). So far, only the neonatal foal's glucose homeostasis was affected, whereas all other studied parameters, including growth, were not affected. The foal’s predisposition to osteochondrosis, however, was increased at 6 months of age, which does not preclude that it will affect the animals afterwards since the osteoarticular status of the 6-month-old foal will evolve beyond weaning time. This research could help adjust nutritional recommendations to broodmares. [less ▲]

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See detailIntraocular lenses with functionalized surfaces by biomolecules in relation with lens epithelial cell adhesion
Huang, Yi-Shiang ULg

Doctoral thesis (2014)

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial ... [more ▼]

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial-Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including patient’s age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs show the former has more severe PCO after EMT transition. Additionally, the LEC adhesion is favored onto the hydrophobic materials compared to the hydrophilic ones. A biomimetic strategy to promote LEC adhesion without de-differentiation to reduce PCO development risk is proposed. RGD peptides, as well as their grafting and quantification methods on a hydrophilic acrylic polymer were investigated. The surface functionalized IOL promoting LEC adhesion via integrin receptors can be used to reconstitute the capsule-LEC-IOL sandwich structure, which is considered to prevent PCO formation in literature. The results show the innovative biomaterial improves LEC adhesion, and also exhibits similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties comparing to the starting material. In addition, comparing to the hydrophobic IOL material, this bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression. The in vitro assays suggest this biomaterial has the potential to reduce some risk factors of PCO development. [less ▲]

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See detailPhysical properties/texture relationship in industrial melt-cast processed Bi-2212 bulk superconductors using quantitative texture analysis
Dellicour, Aline ULg

Doctoral thesis (2014)

Superconducting Bi2Sr2CaCu2O8+δ tubes and rods manufactured at Nexans SuperConductors gmbh are known to achieve excellent performances despite apparently weak texture. A full texture characterization of ... [more ▼]

Superconducting Bi2Sr2CaCu2O8+δ tubes and rods manufactured at Nexans SuperConductors gmbh are known to achieve excellent performances despite apparently weak texture. A full texture characterization of the bulks has been performed at different scales, using X-ray diffraction and neutron diffraction. The texture experiments confirm that samples exhibit weak textures and reveal some differences between local and macroscopic texture. When investigating how the physical properties might be affected by texture, it was observed that the critical current density Jc is not much influenced by the direction of measurement, while the normal state electrical resistivity displays a ratio of 2.3 between the resistivity along the sample axis and the resistivity along the radial direction. These observations are qualitatively consistent with the texture results. A quantitative study based on the geometric mean of the resistivity tensor compares the experimental data with values calculated from the measured orientation distribution and literature single crystal data. It turns out that, despite the weak texture, a large fraction of the observed resistivity anisotropy is explained by texture effects, because of the very strong anisotropy between the resistivity along the c-axis and the resistivity in the ab-planes. Lastly, the influence of sample oxygenation on Tc and Jc has been studied. In these bulks, Tc as a function of oxygen content follows a bell-shaped curve, confirming literature results for other superconducting samples. Jc is also influenced by the oxygen content; interestingly, the maximum Jc is not obtained for the same oxygen content as the maximum Tc. [less ▲]

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See detailMujeres, circuitos y fronteras en el sur del Ecuador.
Ramos Ordonez, Maria ULg

Doctoral thesis (2014)

La recherche doctorale de Patricia Ramos porte sur la thématique des femmes et circuits migratoires dans le Sud de l’Equateur. Plus précisément, elle va s’intéresser à l’agence (agency) et aux dynamiques ... [more ▼]

La recherche doctorale de Patricia Ramos porte sur la thématique des femmes et circuits migratoires dans le Sud de l’Equateur. Plus précisément, elle va s’intéresser à l’agence (agency) et aux dynamiques de pouvoir auxquelles sont confrontées les femmes étrangères et équatoriennes au niveau local dans une partie de l’Equateur caractérisée par une très forte mobilité des populations. [less ▲]

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See detailMulti-Domain Approaches for the Solution of High-Frequency Time-Harmonic Propagation Problems
Vion, Alexandre ULg

Doctoral thesis (2014)

The numerical solution of high-frequency time-harmonic propagation problems by volumic discretization methods is a challenging task, most notably because of the very large size of the resulting linear ... [more ▼]

The numerical solution of high-frequency time-harmonic propagation problems by volumic discretization methods is a challenging task, most notably because of the very large size of the resulting linear systems. We present a framework for a class of iterative methods that distribute the work between several CPUs and exchange information between physical or artificial interfaces. The goal is to define subproblems of manageable sizes, and to exploit the power of parallel supercomputers. [less ▲]

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See detailLe coût en droit européen de la concurrence, essai sur la réception d'une notion économique
Provost, Elise

Doctoral thesis (2014)

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See detailVers une "dématérialisation" des droits fondamentaux? Convergence des droits fondamentaux dans une protection fragmentée, à la lumière du raisonnement du juge constitutionnel belge
Rosoux, Géraldine ULg

Doctoral thesis (2014)

Le thèse examine l'articulation tant "procédurale" que "substantielle" des droits fondamentaux, garantis par des dispositions tant constitutionnelles que conventionnelles, et protégés par de multiples ... [more ▼]

Le thèse examine l'articulation tant "procédurale" que "substantielle" des droits fondamentaux, garantis par des dispositions tant constitutionnelles que conventionnelles, et protégés par de multiples juges, tant nationaux qu'européens. Au travers d'une analyse empirique de la jurisprudence, est examinée la question de savoir si le juge des droits fondamentaux ne développe pas un raisonnement portant sur les droits fondamentaux comme tels, indépendamment de leur ancrage textuel dans une Constitution nationale ou une convention européenne. [less ▲]

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See detailLa stratégie de construction de puissance de la Chine sur la scène internationale : le cas de la pénétration chinoise en Amérique latine
Wintgens, Sophie ULg

Doctoral thesis (2014)

Dans le contexte de la globalisation post-Guerre froide, l’affirmation de « nouvelles puissances » et l’avènement concomitant de clubs interétatiques tels que les BRICS (Brésil, Russie, Inde, Chine et ... [more ▼]

Dans le contexte de la globalisation post-Guerre froide, l’affirmation de « nouvelles puissances » et l’avènement concomitant de clubs interétatiques tels que les BRICS (Brésil, Russie, Inde, Chine et Afrique du Sud), dans un système international au demeurant dominé par les États-Unis, alimentent les réflexions contemporaines sur la puissance et sa distribution mondiale. Eu égard au rôle international et aux potentialités conférés par sa dimension géopolitique d’État-continent, le seul développement économique de la Chine en fait aujourd’hui un acteur international incontournable (force), alors même que le syncrétisme de son modèle de développement présenté comme un « socialisme aux caractéristiques chinoises », alliant en ce sens des mécanismes de l’économie de marché à des éléments hérités du marxisme-léninisme, lui confère une certaine forme de vulnérabilité constitutive (faiblesse). Si bien que l’énigme de sa puissance (nature) et l’ambivalence de sa réponse à la domination américaine (exercice) enjoignent au double dépassement théorique. La présente thèse, dans son objectif d’analyser la stratégie de construction de puissance de la Chine sur la scène internationale à travers le cas de sa pénétration en Amérique latine, repose dès lors sur un double postulat théorique : la puissance chinoise se définit comme une entreprise de reconnaissance mondiale toujours en redéfinition et au résultat incertain, qui s’opère dans un monde multipolaire en gestation au sein duquel les puissances émergentes rivalisent avec les États-Unis et l’Union européenne (UE) pour la domination. Mesurer l’influence de la Chine sur la scène mondiale, à travers sa capacité à se faire reconnaître comme un acteur international de référence par les autres puissances émergentes et plus encore par les puissances occidentales, procède dès lors également d’une méthodologie ad hoc : seul l’examen corrélé des pratiques des acteurs, étatiques ou autres, (réalité) et du sens qu’ils confèrent à leurs actions (discours) permet de mesurer pleinement l’impact de la représentation que la Chine a du monde, d’elle-même et de sa place dans ce monde, sur les préférences et comportements des autres acteurs du système international. Dans ce cadre, le raisonnement au cœur de la présente thèse s’appuie sur deux parties ou questions centrales. La première interroge la stratégie de construction de puissance de la Chine sur la scène internationale post-Guerre froide. Elle met au jour le poids de trois enjeux fondamentaux en interne dans la construction de son statut d’acteur mondial incontournable, à savoir le poids de l’identité nationale façonnée par l’histoire et l’idéologie, le poids du régime mû par une quête de légitimité structurelle et le poids des intérêts nationaux guidant nécessairement sa diplomatie. La seconde partie questionne ensuite empiriquement la façon dont la Chine construit sa puissance vis-à-vis de l’Amérique latine, région porteuse d’un projet politico-économique sur lequel influent historiquement les stratégies respectives des États-Unis et de l’UE. Elle met au jour le déploiement par la Chine d’une stratégie nécessairement duale de coopération et d’hégémonie visant à consolider sa puissance sans atrophier son ascension (représentation), à même de séduire les États latino-américains (perception), et par conséquent de concurrencer les stratégies américaine et européenne influant sur le sous-continent (reconnaissance). [less ▲]

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See detailHigh-throughput synthesis of functional oxide films
Dhanapal, Pravarthana ULg

Doctoral thesis (2014)

Epitaxy of metal oxides is of great interest since it provides a way to obtain desired novel properties for the applications such as electronics and energy. However, earlier epitaxy research's have been ... [more ▼]

Epitaxy of metal oxides is of great interest since it provides a way to obtain desired novel properties for the applications such as electronics and energy. However, earlier epitaxy research's have been restricted because of the limited range of compositions and low-index of commercially available single crystal substrates. Consequently, novel epitaxy synthesis methods need to be developed in order to go beyond the present demands of of single crystal substrates in terms of phase, composition, size, orientation and symmetry. In this research work, we have developed a high-throughput synthesis process, called combinatorial substrate epitaxy (CSE), where an oxide film is grown epitaxially on a polycrystalline substrate. As a proof-of-concept, we firstly fabricated Ca3Co4O9 films on Al2O3 ceramics. Films have a good local epitaxial registry, and the Seebeck coefficient is about 170 µV/K at 300 K. High quality BiFeO3/La0.7Sr0.3MnO3 thin film heterostructures were secondly deposited on dense LaAlO3 ceramics prepared by spark plasma sintering. Piezoforce microscopy was used to confirm the local ferroelectric properties. Thirdly, we investigate the growth of of metastable monoclinic Dy2Ti2O7 epitaxial films on polycrystalline La2Ti2O7 substrates. We conclude that CSE approach opens the way towards unexpected electronic properties in oxide films. [less ▲]

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See detailStudy of supernovae and massive stars and prospects with the 4m International Liquid Mirror Telescope
Kumar, Brajesh ULg

Doctoral thesis (2014)

Massive stars are the progenitors of the most energetic explosions in the Universe such as core-collapse supernovae (CCSNe) and gamma ray bursts. During their life time they follow various evolutionary ... [more ▼]

Massive stars are the progenitors of the most energetic explosions in the Universe such as core-collapse supernovae (CCSNe) and gamma ray bursts. During their life time they follow various evolutionary phases (e.g. supergiant, luminous blue variable and Wolf-Rayet). They strongly influence their environments through their energetic ionization radiation and powerful stellar winds. Furthermore, the formation of low- and intermediate-mass stars are also being regulated by them. The Carina nebula region, which hosts a large population of massive stars and several young star clusters, provides an ideal target for studying the feedback of massive stars. In this thesis, we investigated a wide field (32′ × 31′ ) region located in the west of the Carina nebula and centered on the massive binary WR 22. For our study, we used new optical photometry (UBVRI Hα), along with some low resolution spectroscopy, archival near infra-red (2MASS), and X-ray (Chandra, XMM-Newton) data. We estimated several parameters such as reddening, reddening law, etc. and also identified young stellar objects located in the region under study (Kumar et al., 2014b). Among the various types of CCSNe, Type IIb are recognized with their typical observational properties. Some of them show clear indication of double peaks in their light curves. The spectral features of these SNe show a transition between Type II and Type Ib/c events at early and later epochs, respectively. It has been noticed that the occurrence of these events is not common in volume limited surveys. In this thesis we have studied the properties of the light curve and spectral evolution of the Type IIb supernova 2011fu. The observational properties of this object show resemblance to those of SN 1993J with a possible signature of the adiabatic cooling phase (Kumar et al., 2013). When light passes through the expanding ejecta of the SNe, it retains information about the orientation of the ejected layers. In general, CCSNe exhibit a significant level of polarization during various phases of their evolution at different wavelengths. We have investigated the broad band polarimetric properties of a Type II plateau SN 2012aw and compared it with other well-studied CCSNe of similar kinds (Kumar et al., 2014a). In the framework of the present thesis, we have also contributed to the development of the 4m International Liquid Mirror Telescope (ILMT) project which is a joint collaborative effort among different universities and research institutes in Belgium, India, Canada and Poland. We performed various experiments including the spin casting of the primary mirror, optical quality tests of the mercury surface, mylar film experiments, etc. The possible scientific capabilities and future contri- butions of this telescope are also discussed. We propose our plans to identify the transients (specially supernovae) with the ILMT and their further follow-up scheme. The installation of the ILMT will start very soon at the Devasthal observatory, ARIES Nainital, India. [less ▲]

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See detailEtude multiparamétrique de polymères acryliques, modèles de lentilles intraoculaires : recherche d'indicateurs de risque de développement de la cataracte secondaire.
Bertrand, Virginie ULg

Doctoral thesis (2014)

In this study we compared 3 biomaterials (supplied by the firm PhysIOL , Science park, Liège, Belgium). We have at first to estimate certain physico-chemical properties such as the surface hydrophilicity ... [more ▼]

In this study we compared 3 biomaterials (supplied by the firm PhysIOL , Science park, Liège, Belgium). We have at first to estimate certain physico-chemical properties such as the surface hydrophilicity, the adhesion force (Atomic Force Microscopy). We were then interested in the bioadhesive character of these biomaterials by estimating in vitro, the adsorption of BSA and the cellular adhesion (lens epithelial cells, LECs), the ex vivo capsular adhesion and the in vivo tissular reaction (subcutaneous implant of polymers for 1 month (rabbit)). We then realized a proteomic analysis using mass spectrometry : LECs used during our in vitro tests, proteins adsorbed on biomaterials after incubation in a complex medium, the fibrous capsule surrounding the biomaterial after its subcutaneous implantation and the lens (MALDI imaging). [less ▲]

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See detailMultimodal modelling of the human brain
Ziegler, Erik ULg

Doctoral thesis (2014)

There are many ways to model properties of the brain from magnetic resonance imaging (MRI) data. One acquisition technique, known as diffusion-weighted imaging (DWI), can map the speed and direction of ... [more ▼]

There are many ways to model properties of the brain from magnetic resonance imaging (MRI) data. One acquisition technique, known as diffusion-weighted imaging (DWI), can map the speed and direction of water diffusion within the brain. This work explores the quantitative potential of DWI, in combination with other neuroimaging modalities, for in vivo modelling of the human brain. Fiber tractography from DWI can be used to construct a wiring diagram of the brain (or connectome) and identify connectivity patterns between regions. To explore the utility of connectome modelling, we constructed brain networks from healthy subjects carrying known genetic variations. Using machine learning, we demonstrated high classification accuracy between subjects with different genotypes using only their connectomes. Next, we tested whether fiber track density images could be used to de- tect early pathological effects in patients with Parkinson’s disease. We found increases in track density in disease-relevant regions of the white matter, including the nigrostriatal pathway, used unbiased whole-brain statistical testing. This result is extremely encouraging, as axonal degen- eration within this area is challenging to identify with standard magnetic resonance imaging contrasts. Finally, a finite element modelling (FEM) approach was developed for solving the electroencephalography (EEG) forward problem. Electrical conductivity tensors were estimated from DWI in order to represent the heterogeneous conductivity profile of the white matter. When tested against the analytical solution, this FEM method proved more reliable than the current state-of-the-art alternative. Advanced brain modelling from DWI can clearly provide lucrative results. These methods have been open-sourced for use by the community. [less ▲]

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See detailEtude des produits de dissociation de H2O dans un échantillon de comètes d'origines variées
Decock, Alice ULg

Doctoral thesis (2014)

Les comètes sont connues pour contenir de grandes quantités d’eau et des molécules organiques en tout genre. Formées lors de la naissance de notre Système Solaire, il y a 4.6 milliards d’années, elles ... [more ▼]

Les comètes sont connues pour contenir de grandes quantités d’eau et des molécules organiques en tout genre. Formées lors de la naissance de notre Système Solaire, il y a 4.6 milliards d’années, elles n’ont ensuite pas beaucoup évolué, ce qui les rend témoins potentiels des processus physico-chimiques présents à cette période. L’étude des comètes permet donc d’en apprendre davantage sur leur propre nature encore potentiellement énigmatique, mais également sur notre Système Solaire lui-même, et tout particulièrement sa genèse. La mission européenne Rosetta, en orbite autour de la comète 67P/Churyumov-Gerasimenko témoigne de l’intérêt porté à ces petits corps gelés du Système Solaire. Cette mission est unique puisqu’elle va permettre pour la première fois de mesurer la composition chimique précise d’un noyau cométaire. Ce type de mission est par contre très coûteux et ne concerne qu’une comète en particulier. Avec des télescopes au sol, il est possible d’étudier un nombre plus important de comètes. Certes, le noyau n’est dans ce cas pas directement atteignable, mais la spectroscopie permet d’analyser l’atmosphère de la comète. Formée par la sublimation des glaces du noyau et la dissociation des molécules qui s’en échappent, la coma contient de nombreuses informations nous permettant d’accroître nos connaissances sur la composition chimique du noyau. L’objectif de cette thèse est l’étude des molécules liées à l’eau dans les comètes. Les glaces cométaires renferment en effet 80% d’eau. Etudier cette molécule est donc crucial pour définir la nature des comètes et comprendre les conditions physiques et chimiques régnant dans la coma. Toutefois, H2O n’est pas détectable dans le domaine de longueur d’onde visible. Sur base d’un ensemble de données spectroscopiques visibles acquises depuis le sol, nous proposons dans cette thèse l’analyse de deux produits de dissociation de la molécule d’eau observables dans l’atmosphère de la comète, l’oxygène atomique et le radical OH. Le premier volet de ce travail se concentre sur les trois raies interdites de l’oxygène localisées à 5577.339 Å pour la raie verte (O(1S)) et à 6300.304 Å et 6363.776 Å (O(1D)) pour les raies du doublet rouge en vue de déterminer la ou les molécules parentes à l’origine de ces atomes. Dans cette optique, nous avons créé un spectre synthétique de la molécule de C2 afin de décontaminer la raie verte des raies dues au C2. Ensuite, nous avons mesuré les rapports d’intensité et les largeurs intrinsèques des trois raies d’oxygène pour des comètes situées à différentes distances héliocentriques. La comparaison du rapport de l’intensité de la raie verte sur la somme des intensités des raies rouges (rapport G/R) avec les taux d’excitation fournis par la théorie montre que H2O est la molécule parente principale des atomes d’oxygène lorsque la comète est observée à r ∼ 1 ua. Par contre, lorsque la comète est loin du Soleil (>2.5 ua), les molécules de CO2 contribuent également à la production d’oxygène. La mesure des largeurs intrinsèques des raies montre que la raie verte est plus large que les raies rouges alors que la théorie prédit l’inverse. Découle de cette observation que la raie verte pourrait principalement provenir de la photodissociation du CO2 alors que les raies rouges seraient uniquement formées via H2O. En étudiant les raies d’oxygène à différentes distances du noyau cométaire, nous réalisons que la molécule parente de l’oxygène varie : le CO2 est le contributeur premier des atomes d’oxygène en deçà de ∼1000 km du noyau et laisse ensuite la place à H2O. Qui plus est, nous notons l’importance du quenching collisionnel produit par H2O dans la coma interne qui joue un rôle significatif dans la perte des atomes de O(1S) et O(1D). Un modèle d’émission est réalisé pour reproduire nos données observationnelles. En se penchant sur le comportement adopté par les raies d’oxygène près du noyau et sur l’ajustement fourni par le modèle, une estimation de l’abondance relative du CO2 est déterminée. Des lors, cette thèse présente une nouvelle méthode pour déterminer l’abon- dance CO2/H2O dans les comètes à partir de données obtenues depuis le sol alors qu’une mesure directe de la molécule de CO2 n’est jusqu’à ce jour possible que depuis l’Espace. La seconde partie de notre travail porte sur l’analyse des rapports isotopiques 16O/18O et D/H à partir des isotopes du radical OH. La connaissance des rapports isotopiques dans des comètes d’origines variées est importante car cela peut nous renseigner sur les conditions physiques et chimiques existantes lorsque la comète s’est formée. De plus, la mesure du D/H s’inscrit dans le débat actuel de l’origine des océans terrestres. Dans ce contexte, des spectres synthétiques de 16OH, 18OH et OD sont créés sur base d’un modèle de fluorescence. Le rapport 16O/18O est déduit pour la première fois par ce modèle pour la comète C/2012 F6 (Lemmon) et il établit le point de départ d’une longue série de mesures portées sur des comètes brillantes à venir. [less ▲]

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See detailLa naissance du livre de cuisine : Etude discursive des ouvrages culinaires d'Ancien Régime (1651-1799)
Colson, Maryse ULg

Doctoral thesis (2014)

Entre 1651 et 1799, l'édition culinaire de langue française connaît une efflorescence sans précédent ; conjointement, au coeur du 18e s., naît la Nouvelle Cuisine, mode culinaire qui se veut être l ... [more ▼]

Entre 1651 et 1799, l'édition culinaire de langue française connaît une efflorescence sans précédent ; conjointement, au coeur du 18e s., naît la Nouvelle Cuisine, mode culinaire qui se veut être l'adaptation bourgeoise des moeurs aristocratiques. Partant de ces deux prérequis, cette étude cherche à comprendre comment ces deux phénomènes ont participé à la structuration progressive de l'ouvrage culinaire, capitale dans son histoire et instigatrice du livre de cuisine contemporain. S'inspirant de concepts hérités de la narratologie, l'analyse se concentre sur deux aspects cruciaux des ouvrages culinaires - la situation d'énonciation et le péritexte - pour aboutir à une typologie. Nous distinguons ainsi le recueil de recettes, le manuel de cuisine, le livre de cuisine et l'avatar, ou dérivé culinaire. Cette étude met aussi en exergue le commentaire : portion discursive prise en charge par l'énonciateur et qui fait partie intégrante de l'appareil péritextuel des ouvrages culinaires. [less ▲]

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See detailL’émergence d’une politique foncière régionale en Bretagne : de l’identification des enjeux à la création d’un Etablissement public foncier d’Etat
Dupont, Josselin ULg

Doctoral thesis (2014)

During the last decades, we have experienced a general rise of real estate prices as well as the reinforcement of sustainable development issues. This resulted in a "renewal" of land policy in France ... [more ▼]

During the last decades, we have experienced a general rise of real estate prices as well as the reinforcement of sustainable development issues. This resulted in a "renewal" of land policy in France, with the development of “Etablissements publics fonciers” (EPF). At the same time, there is a withdrawal from the public sphere against a dominant financial logic. In this context, our thesis questions the need to develop land policy at the regional scale. To do so, we have examined the situation of Brittany on the basis of several partnerships (Regional Council, DREAL and EPF of Brittany, ADEF, COST and joint supervision with the University of Liege), with research materials gathered from three distinct research terrains (in Brittany, in France and in Europe). This leaded to a PhD structured in two main parts: on the one hand, a regional diagnostic on land issues for Brittany with a list of mobilized land data and, on the second hand, an original analysis of the EPF tool. Our results show that Brittany is facing fundamental land issues (fast land artificialization due to specific modes of living and demographic dynamics) that impact in different ways the regional territory (rural-urban and Armor-Argoat disparities). Our results also show that the choice of a regional land policy embodied in the creation of an EPF is at the same time very common from a French perspective and very original from a European perspective. In conclusion, we note that the effectiveness of EPF is not yet actually demonstrated and we propose recommendations to Brittany’s decision-makers. [less ▲]

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See detailSupercritical Carbon Dioxide Assisted Impregnation to Prepare Drug-eluting Polymer Implants
Champeau, Mathilde ULg

Doctoral thesis (2014)

The scCO2 impregnation process is a promising alternative to other manufacturing process to prepare drug-eluting polymer implants. This work enabled to rationalize the influence of the key parameters ... [more ▼]

The scCO2 impregnation process is a promising alternative to other manufacturing process to prepare drug-eluting polymer implants. This work enabled to rationalize the influence of the key parameters governing this process and to determine in which extent this process can be used to prepare drug-eluting implants. We have combined the information obtained with traditional polymer characterization techniques and a newly characterization set-up we have developed that is based on in situ FTIR micro-spectroscopy. We have worked on the impregnation of sutures made of PLLA, PP and PET with two anti-inflammatory drugs namely ketoprofen and aspirin. Firstly, the thermodynamic behaviors of the systems drug/CO2 (solubility and speciation of the drug) and polymer/CO2 (CO2 sorption, polymer swelling, evolution of the polymer microstructure and of the tensile properties) were studied as a function of pressure and temperature. Then, the scCO2 impregnation process was investigated. The impact of the operational conditions on the drug loading (contact time, pressure, temperature and depressurization conditions) was explored and accounted regarding to the CO2 sorption, the swelling, the drug solubility as well as the changes in the polymer microstructure with the experimental conditions and the presence of the drug. The drug/polymer affinity was also explored. The tensile properties of the impregnated fibers were also evaluated. PLLA was more impregnated (up to 32%) than PP and PET (up to 5%) in the investigated conditions. Finally, we have shown that the drug release can be tuned from 3 days to 3 months by varying the impregnation and depressurization conditions on the system PLLA/Ketoprofen. [less ▲]

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See detailcaractérisation physico-chimique et minéralogique de matériaux calcaro-dolomitiques en vue de la production de liants et produits dérivés
Matamba Jibikila, Raphaël ULg

Doctoral thesis (2014)

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial ... [more ▼]

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial sectors. Moreover, regardless of the scope of these materials, they must meet specific mineralogical and mechanical or physico-chemical properties, depending on the sector. Environmental requirements and sustainable management of mineral resources, have forced companies to reduce the value of naturally occurring materials, focusing oriented processing of waste materials or alternative approach. Moreover, technological developments have led to new applications requiring maximum purity of the material also led farmers to manage natural resources in a more rational manner. Mbuji-Mayi Region in the Democratic Republic of Congo, has huge limestone and dolomitic deposit; located in the " Mbuji-Mayi Supergroup". Nevertheless, the city suffers from a serious lack of sustainable infrastructure to consolidate its development and remains dependent on the supply of construction and building materials from other regions, located sometimes more than 1000 km from the Mbuji-Mayi site. The aim of this thesis is to investigate the potential use of Mbuji-Mayi supergroup materials to produce binder or derivated products in a sustainable management of mineral resources way. Thus, dolomitic samples were taken from Kanshi S13B and S70 Lubi drill cores, while limestone facies are from artisanal quarries in the region. They were then prepared and characterized. Techniques used are: X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), thermogravimetric analysis and the differential scanning calorimetry (TG-DSC), optical microscopy (OM) and scanning electron microscopy combined with chemical microanalysis (SEM / EDX). The results obtained after raw materials characterization showed that the Mbuji-Mayi Supergroup contains pure dolomite (respective mean CaO and MgO contents of 20.5 and 30%), impure dolomites and impure limestones. uniaxial compressive strength test, water absorption coefficient, and porosity were measured. Results were satisfactory in terms of the use of materials such as rubbles or building stones. Thermal and microscopic analyzes of pure dolomite, showed that these materials have high added value in the areas of refractory, glass manufacture or dolomitic lime production. Finally, a binder (CS1c) prepared from impure limestone, posted quite sufficient characteristics for applications with low mechanical stress. Metakaolin prepared from local raw material, was used to improve the characteristics of the binder CS1c. The analysis of the properties of the mixture CS1c-metakaolin, helped us to understand the role of some mineral phases, in contributing to the development of mechanical strength of such binders.   [less ▲]

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See detailEngineering of poly(2-oxazoline)s for a potential use in biomedical applications
Legros, Camille ULg

Doctoral thesis (2014)

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in ... [more ▼]

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in dilute media and in inverse emulsion based on a statistical copolymer made of 2-ethyl-2-oxazoline and ethylene imine units. These stimuli-responsive nanogels were swelling in acidic media and were cleaved in reductive environment. They proved to be non-cytotoxic and act as protein repellent. Second, a reactive platform based on a statistical POx polymer bearing aldehyde functionalities was engineered, enabling the synthesis of graft and cross-linked POx. Last, a block copolymer made of 2-methyl- and 2-isopropyl-2- oxazoline units, proved to self-assemble into micelles when heated above its LCST, for a short period of time (< 1h30). When annealed for a longer time (> 1h30), crystallization-driven self-assembly led to the formation of different morphologies (fiber rods and cross-linked micelles). [less ▲]

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See detailThe physical and biological controls on the distribution of gases and solutes in sea ice from ice growth to ice decay
Zhou, Jiayun ULg

Doctoral thesis (2014)

Les changements dans l’extension et les propriétés de la glace de la mer, liés au réchauffement climatique, affectent l’écosystème polaire, ainsi que les interactions entre l’atmosphère, la glace de mer ... [more ▼]

Les changements dans l’extension et les propriétés de la glace de la mer, liés au réchauffement climatique, affectent l’écosystème polaire, ainsi que les interactions entre l’atmosphère, la glace de mer et l’eau sous-jacente. Cependant, des incertitudes subsistent quant aux changements potentiels qui affecteront la biogéochimie de la glace de mer dans un futur proche. Afin de mieux comprendre les changements potentiels qui affecteront la biogéochimie de la glace de mer, nous avons étudié les facteurs qui influencent la distribution de certains composés dissouts (e.g., nutriments, matière organique dissoute (DOM)) et gazeux (e.g., Ar, O2, N2, CH4) au sein de la glace de mer, depuis la croissance de la glace, jusqu’à sa fonte. Les résultats ont été obtenus à partir d’une expérience de 19 jours dans un bassin expérimental à Hambourg (Allemagne) et une étude de terrain de 5 mois à Barrow (Alaska). Ils ont été ensuite comparés aux propriétés physiques de la glace (température, salinité et autres paramètres dérivés) et à des paramètres biologiques (activité bactérienne, abondance bactérienne, chlorophylle-a et phaeopigments). Nos travaux ont montré que les propriétés physiques de la glace exercent une forte influence sur la répartition des composes biogéochimiques dans la glace de mer, à travers leur impact sur la dynamique des saumures, la formation de bulles de gaz et la perméabilité de la glace. Nous avons décrit 4 stades dans la dynamique des saumures qui influencent la distribution des composés dissouts (e.g., silice et DOM) dans la glace. Cependant, le gaz inerte étudié (Ar) montre une dynamique différente de celle des composés dissouts, indiquant un mécanisme de transport différent. Nous suggérons que la formation de bulles de gaz dans la glace de mer est le mécanisme responsable de cette différence, parce que les bulles de gaz devraient migrer vers le haut, à cause de leur différence de densité par rapport aux saumures, alors que les saumures sont drainées vers le bas à cause de la gravité. Nos observations montrent également que le seuil critique de perméabilité pour l’ascension des bulles de gaz devrait se trouver entre 7.5 et 10 % de volume relatif en saumure ; seuil qui est plus élevé que les 5 % suggérés pour le transport de saumure vers le bas. L’augmentation de la perméabilité de la glace et les échanges de gaz prolongés tendent à amener les concentrations de gaz vers leur valeur de solubilité, sauf lorsque l’eau sous-jacente présente une sursaturation par rapport à l’atmosphère (e.g., CH4), ou lorsque une production in-situ se produit au sein de la glace (e.g., O2). Etant donné que l’ammonium et O2 s’accumulent clairement dans les couches de glace où la convection est limitée, nous suggérons que les variations de ces composés biogéochimiques dans la glace dépendent de la balance entre le transport physique et l’activité biologique ; l’impact de cette dernière sur les composés biogéochimiques est particulièrement visible lorsque le taux de production biologique du composé excède largement la vitesse d’élimination du composé par le transport physique. Nous avons ensuite discuté du potentiel d’utiliser Ar et N2 comme traceurs inertes pour corriger l’impact des processus physiques sur les variations de O2, afin de déterminer la production communautaire nette dans la glace de mer. Les propriétés chimiques de certains composés biogéochimiques (e.g., nitrate, ammonium, DOM) pourraient également influencer leur répartition au sein de la glace de mer, en plus des processus physiques et biologiques. Cependant, il est nécessaire d’avoir plus d’études à ce sujet pour confirmer cela. Enfin, sur base de nos résultats, nous présentons une mise à jour des processus qui régulent la répartition des gaz dans la glace de mer, avec des références à des observations récentes qui illustrent chacun des processus. Nous donnons également un aperçu des changements qui pourraient affecter la biogéochimie de la glace de mer à l’avenir, et des pistes de recherches pour une quantification précise de ces changements. [less ▲]

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See detailSynthesis of functionalized polyamide 6 by anionic ring-opening polymerization
Tunc, Deniz ULg

Doctoral thesis (2014)

The studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening ... [more ▼]

The studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening polymerization. By using this strategy, we describe: (i) the synthesis of thermally more stable fluorinated polyamide 6 having a hydrophobic surface; (ii) the synthesis of polyamides 6 bearing pendant cinnamoyl groups, which are thermo- and photoresponsivechromophore groups, and demonstrating their reversible crosslinking as well as improved thermo-mechanical properties; (iii) the copolymerization ofCL with a crosslinker (N-functionalized α-amino-ԑ-caprolactambis-monomers) into crosslinked polyamides 6.As part of our continuing interest in polyamide 6 chemistry, we developed the combination of anionic ring-opening polymerization of CL and chain-growth condensation polymerization of ethyl 4-butylaminobenzoate in order to obtain aliphatic/aromatic polyamides in one-step. [less ▲]

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See detailSilver Nanowire Networks: Effects of percolation and thermal annealing on physical properties
Langley, Daniel ULg

Doctoral thesis (2014)

The use of transparent conductive materials (TCMs) has rapidly increased in the last two decades as a result of the increasing demand for personal electronic devices and the development of thin film based ... [more ▼]

The use of transparent conductive materials (TCMs) has rapidly increased in the last two decades as a result of the increasing demand for personal electronic devices and the development of thin film based solar cells. To date, the most commonly used TCM is indium tin oxide (ITO). However indium is a rare earth metal with a complex geopolitical environment surrounding its supply and production. Furthermore, the oxide family suffers from poor mechanical properties such as brittleness and generally requires either high temperature synthesis (>400°C) or vacuum processes for their deposition. For these reasons, research in recent years has focused on the discovery or the design of a TCM to replace ITO. This thesis applies a dual approach combining simulations and experiments to explore the fabrication and optimisation of silver nanowire networks for use as a TCM and to improve the understanding of their physical properties. The simulation contribution focuses on the application of percolation modelling to 2D nanowire networks while the experimental part explores the electrical and optical properties of silver nanowire networks and their electrical behaviour under thermal annealing. We present in this work the modelling of 2D stick percolation systems initially composed of perfect idealised sticks, and then, investigate the influence of parameters such as length distributions, angular distributions or shape (curved nanowires). We address the divergence of the critical density for the onset of percolation observed for small system sizes and introduce some preliminary work on simulating the collection (or injection) efficiency of charges by a nanowire network. The experimental component provides a discussion of the impact of wire length, wire diameter, network density and fabrication technique on the optical and electrical properties of silver nanowire networks. An in-depth study of the effect of thermal annealing on the networks properties was undertaken, which revealed several mechanisms responsible for the initial reduction of resistance and the observed final loss of conductivity. An original observation enables the revelation of geometrical quantized percolation for rather sparse networks. Finally we conclude that silver nanowire networks are an excellent prospect as a TCM to replace ITO: these materials have superior mechanical properties and enable comparable and even superior electro-optical properties. [less ▲]

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See detailError
Bastin, Jean-François ULg

Doctoral thesis (2014)

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See detailModelling serial offenders’ spatial behaviours: new assumptions for geographic profiling
Trotta, Marie ULg

Doctoral thesis (2014)

The geographic profiling is amethodology of investigation which uses the crime sites of a criminal series in order to delineate prior areas for searching the offender. Its implementation is currently ... [more ▼]

The geographic profiling is amethodology of investigation which uses the crime sites of a criminal series in order to delineate prior areas for searching the offender. Its implementation is currently limited by too simplistic assumptions that are difficult to assess during an investigation or even not corroborated at an individual level of observation. This thesis studies the predictive capacities of geographic profiling in the context of Belgium, a dense country where the road network is not suitable for classical algorithmimplemented with Euclidean or Manhattan distances. More precisely, the thesis has for first objective to integrate space anisotropy with two improvements: (1) the integration of the road network in the journey-to-crime and (2) the integration of the structure of opportunities for series of sexual offences. Beyond this objective, the thesis questions a hypothesis underlying this type of research methodology: the kind of spatial relationship between the offender’s residence and the crime sites. An alternative to the distance decay effect is developed, minimising the variance in travelled distances between the offender anchor point and the initial contact sites of the offences (MOV hypothesis). The sensitivity of this methodology is measured and its effectiveness is compared to the one of the distance decay effect. A major result of the thesis is that the share of behaviours than can be modelled by this new hypothesis is similar to the one of the distance decay effect. However, a large number of series did not meet the required conditions to implement an efficientmethodology given the multiplicity of offender’s residences or the scarcity of sites composing the series; those applicability criteria are analysed in this work. Nevertheless, theMOV hypothesis is particularly valuable for long series of offences. Then, the thesis analyses the impact of the geometry of crime series locations on the effectiveness of the chosen spatial assumption (distance decay effect orMOV) with graph theory. It highlights the superiority of the MOV hypothesis for offenders travelling in some preferred direction. The analysis also shows that both hypotheses are not mutually exclusive but can be combined to build offender geographic profiles. Finally, this thesis focuses on the modelling of neutral areas in terms of criminal attractiveness on the Belgian territory. The work presents the originality of analysing data on a whole country, integrating both urban and non-urban areas. The objective of the modelling is the integration of the opportunity structure of sexual offences in the geographic profile and the estimation of the perturbing effect of a differentiated attractiveness. In order to assess this perturbation, we propose a two-steps process. Firstly, a regression model combining factors fromthe crime pattern and social disorganisation theories models the spatial distribution of crimes. The regression model identifies a centre-periphery relationship in the spatial distribution of crime locations. Still, the model underestimates the number of positive sectors, omitting some attractors. Then, the impact of attractive location (i.e. presenting the favourable factors for crime concentration)is evaluated for the series of sexual offences. In fine, the two spatial hypotheses do not seem affected by the attractors identified by the modelling except when the contact sites are clustered in attractive areas. In addition, the share of serial offenders committing their offences in the most attractive locations is smaller than that of single offenders. This observation strengthens the need for working on spatial distribution models instead of calibrated functions with solved cases. [less ▲]

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See detailTraining alters the innate immune response in the lower airway of horses
Frellstedt, Linda ULg

Doctoral thesis (2014)

Many human and animal studies have examined various markers of the innate and/or adaptive immunity in association with exercise and have come to the general conclusion that exercise, either acute or ... [more ▼]

Many human and animal studies have examined various markers of the innate and/or adaptive immunity in association with exercise and have come to the general conclusion that exercise, either acute or chronic, modifies the immune response. Regular moderate exercise has beneficial and protective effects on immunity because it results in a balance of pro- and anti-inflammatory effects. This balance may be disturbed during exhaustive exercise, such as that experienced during competition and overtraining, resulting in immunosuppression. Humans frequently suffer from upper respiratory tract infections after prolonged intense exercise, whereas horses suffer primarily from lower airway inflammation and/or infection. The underlying mechanism for this difference remains unknown at this time. The sampling of different cell types is limited in humans and therefore, these studies focus on the evaluation of cells in peripheral blood or markers in saliva. Two groups of researchers in human sports medicine have compared populations of sedentary and regularly exercising people. The expression of Toll-like receptors (TLRs) 1, 2, 3 and 4 was decreased in peripheral blood monocytes in exercising subjects. This altered expression of TLRs was also associated with a lower production of pro-inflammatory cytokines (IL-6, IL-1α, TNF-α). Regular exercise induced circulating anti-inflammatory cytokines (IL-10, IL-6) and, therefore, limited the effects of pro-inflammatory cytokines. The first line of defense in the airways is provided by pulmonary alveolar macrophages and bronchial epithelial cells. Strenuous exercise impairs the viability of bronchial epithelial cells, reduces the viral defense mechanisms, and decreases oxidative burst activity of pulmonary alveolar macrophages. The altered immune response in association with exercise/training does not only lead to an increased risk for infection but may also cause the development of allergies and chronic inflammation in the lower airway. This may explain why young equine athletes frequently suffer from Inflammatory Airway Disease (IAD). The etiology of IAD remains unknown but an association with subclinical viral infections as well as inflammatory stimuli from the environment has been suspected. The objective of this work was to increase our knowledge of immune mechanisms in young equine athletes by evaluating the effect of acute exercise and training on the innate immune responses of pulmonary alveolar macrophages (PAM), bronchial epithelial cells (BEC) and monocytes. The hypothesis was that exercise and training modify the TLR mRNA expression as well as the production of pro-inflammatory cytokines and interferons in these three cell types. Eight Standardbred horses were studied over a period of 9 months during which they were acclimatized, trained and deconditioned. Standardized exercise tests were performed regularly and biological samples (blood, bronchoalveolar lavages, and biopsies of the bronchial epithelium) were taken at defined intervals in order to allow a longitudinal evaluation of the different parameters. Monocytes, PAM and BEC were harvested and analyzed. The expression of TLR3 was decreased in equine PAM and monocytes after a period of training, but not after a single strenuous exercise session. In addition, the expression of TLR4 was increased in equine monocytes after training. The production of TNF-α and IFN-β was also examined in PAM and monocytes ex vivo after the stimulation with different TLR ligands. The production of these cytokines was reduced in PAM after a defined period of training and remained decreased for three months thereafter. In contrast, the synthesis of TNF-α was increased after a period of training in equine monocytes and remained increased thereafter. In a second study, a model for the culture of equine bronchial epithelial cells (EBEC) was developed which allowed us to evaluate the effect of exercise and training on the innate immune response of these cells. Acute exercise or training did not alter the TLR mRNA expression in EBEC. The production of IFN-β was increased in EBEC from trained horses after stimulation with a TLR3 ligand. Concurrently, the secretion of TNF-α and IL-6 was impaired in EBEC from trained horses after the stimulation with TLR2 and TLR3 ligands. This study focused on a single aspect of the innate immunity in horses, gaining knowledge of the TLR expression in three cell types and their response to specific TLR agonists. These results have to be considered in the global context of the innate immunity remembering that they represent only a small part of the complex immune system. Only one type of training (Standardbred race training) and one model of acute exercise (standardized exercise test on a treadmill) were evaluated in this study. This should be considered when drawing conclusions, because it is currently understood that the effects on immune responses vary with different types, intensity and duration of exercise and/or training. Nonetheless, this work has established that a local immunosuppression develops within the lungs in trained horses, and may explain the increased susceptibility of exercising horses to pulmonary viral infections. This local immunosuppression is associated with an increased potential of monocytes to produce pro-inflammatory cytokines when challenged with pathogens. The effects of exercise on innate immunity are complex and further studies are needed to continue the work in this field. In addition to the response to training in young sport horses, a number of environmental factors associated with their nutrition and housing may play important roles in the development of pulmonary infections and inflammation (e.g. IAD). To confirm the significance of the presented results, it would be interesting to investigate the innate immune response in trained horses when challenged with equine pathogens, such as equine influenza and equine herpesviruses. The ultimate goal of this work and other studies in the future is to develop immuno-modulating molecules that could be used for the prevention and treatment of equine respiratory diseases. [less ▲]

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See detailManaging understory light to maintain the coexistence of forest tree species with different shade tolerances
Ligot, Gauthier ULg

Doctoral thesis (2014)

Similar to the management of the other environmental resources, forest management has been questioned and more sustainable practices of forest management are being sought. New close-to-nature practices ... [more ▼]

Similar to the management of the other environmental resources, forest management has been questioned and more sustainable practices of forest management are being sought. New close-to-nature practices aim to favor natural processes over human interventions. Particularly, continuous-cover forestry has the goal of relying on natural regeneration, and maintaining irregular stand structure and tree species mixture. However, maintaining mixture of species with different shade tolerances appears arduous with such a silvicultural system. Successfully managing irregular and mixed forests, relying on natural processes, requires a strong knowledge of the ecology of natural regeneration. In particular, strong knowledge is required to predict the result of the interspecific competition in the understory depending upon light availability. The amount of radiation transmitted to the understory is indeed a critical factor determining regeneration dynamics. It determines, at least in part, regeneration composition because of interspecific differences of growth and survival under shade. Moreover, our quantitative understanding of understory light in uneven-aged and mixed stands remains incomplete. A better quantitative understanding of understory light is needed to provide quantitative guidelines for the management of understory light in uneven-aged and mixed stands and, hence, for the management of natural regeneration. The purpose of this thesis is to determine how close-to-nature forest management can maintain mixtures of species with contrasting shade tolerances. I consider ecological conditions with good water and nutrient supplies. In these conditions, partially closed canopy limits the amount of light that reaches the understory, and light is the major factor driving regeneration composition. Consequently, I study the dynamics of natural regeneration with regards to light availability as well as the interception of light by the canopy of heterogeneous stands. Studying the regeneration ecology of two species with contrasting shade tolerances (Fagus sylvatica L. and Quercus petraea (Matt.) Liebl.), I find that the shade-tolerant species outgrow the less shade-tolerant species in all light conditions. Even though the control of understory light with continuous-cover silviculture is required to sustain the growth of less shade-tolerant regenerations, it might not be sufficient to maintain the coexistence of species with contrasting shade tolerances. In order to examine the effects of canopy structure and composition on understory light availability, I use a model of light interception by heterogeneous canopies after synthesizing and discussing the approaches reported in the literature. The model predicts satisfactorily measures of transmitted light even though it is a relatively simple radiative transfer model. I next explore how various silvicultural treatments can be manipulated to provide favorable understory light conditions for natural regeneration. These silvicultural strategies correspond to selective thinnings of five different types, e.g., harvesting preferentially small trees, large trees, or trees of shade-tolerant species or creating circular gaps. The results underline that creating favorable understory light conditions for natural regeneration can be achieved with various regeneration treatments. However, the adequate reduction of stand density depends upon the chosen silvicultural strategies. In particular, creating gaps of about 500 m2 provides adequate light for small regeneration clumps. Harvesting preferentially small and trees of shade-tolerant species are also appropriate but required higher harvest intensity. Harvesting preferentially large trees slightly increases understory light and promotes more shade-tolerant species than less shade-tolerant species. In order to maintain the coexistence of species with contrasting shade tolerances, forest manager must control understory light and manually suppress the regeneration of the shade-tolerant species. The outcome of this study provides foresters with the necessary tools to evaluate how silvicultural treatments can be manipulated to create or maintain favorable light conditions for the regeneration of species of different shade tolerances. Guidelines are additionally proposed for forest managers wanting to maintain the coexistence of species with contrasting shade tolerances. [less ▲]

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See detailRegularity of functions: Genericity and multifractal analysis
Esser, Céline ULg

Doctoral thesis (2014)

As surprising as it may seem, there exist functions of C∞(R) which are nowhere analytic. When such an unexpected object is found, a natural question is to ask whether many similar ones may exist. A ... [more ▼]

As surprising as it may seem, there exist functions of C∞(R) which are nowhere analytic. When such an unexpected object is found, a natural question is to ask whether many similar ones may exist. A classical technique is to use the Baire category theorem and the notion of residuality. This notion is purely topological and does not give any information about the measure of the set of objects satisfying such a property. In this purpose, the notion of prevalence has been introduced. Moreover, one could also wonder whether large algebraic structures of such objects can be constructed. This question is formalized by the notion of lineability. The first objective of the thesis is to go further into the study of nowhere analytic functions. It is known that the set of nowhere analytic functions is residual and lineable in C∞([0, 1]). We prove that the set of nowhere analytic functions is also prevalent in C∞([0, 1]). Those results of genericity are then generalized using Gevrey classes, which can be seen as intermediate between the space of analytic functions and the space of infinitely differentiable functions. We also study how far such results of genericity could be extended to spaces of ultradifferentiable functions, defined using weight sequences or using weight functions. The second main objective is to study the pointwise regularity of functions via their multifractal spectrum. Computing the multifractal spectrum of a function using directly its definition is an unattainable goal in most of the practical cases, but there exist heuristic methods, called multifractal formalisms, which allow to estimate this spectrum and which give satisfactory results in many situations. The Frisch-Parisi conjecture, classically used and based on Besov spaces, presents two disadvantages: it can only hold for spectra that are concave and it can only yield the increasing part of spectra. Concerning the first problem, the use of Snu spaces allows to deal with non-concave increasing spectra. Concerning the second problem, a generalization of the Frisch-Parisi conjecture obtained by replacing the role played by wavelet coefficients by wavelet leaders allows to recover the decreasing part of concave spectra. Our purpose in this thesis is to combine both approaches and define a new formalism derived from large deviations based on statistics of wavelet leaders. As expected, we show that this method yields non-concave spectra and is not limited to their increasing part. From the theoretical point of view, we prove that this formalism is more efficient than the previous wavelet-based multifractal formalisms. We present the underlying function space and endow it with a topology. [less ▲]

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See detailA Riemannian approach to large-scale constrained least-squares with symmetries
Mishra, Bamdev ULg

Doctoral thesis (2014)

This thesis deals with least-squares optimization on a manifold of equivalence relations, e.g., in the presence of symmetries which arise frequently in many applications. While least-squares cost ... [more ▼]

This thesis deals with least-squares optimization on a manifold of equivalence relations, e.g., in the presence of symmetries which arise frequently in many applications. While least-squares cost functions remain a popular way to model large-scale problems, the additional symmetry constraint should be interpreted as a way to make the modeling robust. Two fundamental examples are the matrix completion problem, a least-squares problem with rank constraints and the generalized eigenvalue problem, a least-squares problem with orthogonality constraints. The possible large-scale nature of these problems demands to exploit the problem structure as much as possible in order to design numerically efficient algorithms. The constrained least-squares problems are tackled in the framework of Riemannian optimization that has gained much popularity in recent years because of the special nature of orthogonality and rank constraints that have particular symmetries. Previous work on Riemannian optimization has mostly focused on the search space, exploiting the differential geometry of the constraint but disregarding the role of the cost function. We, on the other hand, propose to take both cost and constraints into account to propose a tailored Riemannian geometry. This is achieved by proposing novel Riemannian metrics. To this end, we show a basic connection between sequential quadratic programming and Riemannian gradient optimization and address the general question of selecting a metric in Riemannian optimization. We revisit quadratic optimization problems with orthogonality and rank constraints by generalizing various existing methods, like power, inverse and Rayleigh quotient iterations, and proposing novel ones that empirically compete with state-of-the-art algorithms. Overall, this thesis deals with exploiting two fundamental structures, least-squares and symmetry, in nonlinear optimization. [less ▲]

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See detailEtude et justification des courants de contact induits par les lignes à haute tension dans le parc résidentiel belge et leurs incidences sur la population.
Barbier, Pierre-Paul ULg

Doctoral thesis (2014)

Depuis les années septante, des recherches ont mis en avant une possible corrélation entre la leucémie infantile et les champs électriques et magnétiques générés par les lignes haute tension. Cette thèse ... [more ▼]

Depuis les années septante, des recherches ont mis en avant une possible corrélation entre la leucémie infantile et les champs électriques et magnétiques générés par les lignes haute tension. Cette thèse a pour vocation de mettre en avant un autre mécanisme indirect pouvant être un lien possible de cause à effet, les courants de contact. Le document explore différentes pistes (simulations, modèles) pouvant justifier l’apparition de ces courants. [less ▲]

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See detailContribution à l’étude du Plasma Riche en Plaquettes (PRP) dans le traitement des lésions tendineuses
Kaux, Jean-François ULg

Doctoral thesis (2014)

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and ... [more ▼]

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and wound healing. We made an extended literature review of the use of PRP in chronic tendinopathies. Despite the proven efficacy of PRP on tissue regeneration in experimental studies, there is currently scanty tangible clinical evidence with respect to its efficacy in chronic tendon disorders. The few studies that have been performed appear unlikely to be comparable. Randomized controlled studies with appropriate placebo groups are needed to determine the real effectiveness of PRP for treating chronic musculoskeletal injuries. After, we made a study to compare the platelet concentrations using 5 techniques of preparation of PRP and observed that each provides a very different PRP, with variations in the platelet concentrations and of the amount (if any) of erythrocytes and leucocytes. White blood cells could adversely affect wound healing through the release of proinflammatory factors responsible for extracellular matrix degradation. In addition, erythrocyte lysis releases free radicals that harm tissue structures. We thus think that ideal PRP should not contain any erythrocytes or leucocytes, and that the quality of the PRP could perhaps partially explain the variable results observed in the literature. The aim of our next study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. We concluded that an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance. Vascular endothelial growth factor (VEGF) is a platelet growth factor known to regulate angiogenesis. VEGF-111, a biologically active and proteolysis-resistant splice variant of this family, was recently identified. We made a study with the aim of evaluating whether VEGF-111 could have a therapeutic interest in tendon pathologies with the same rat protocol as our previous study. The force necessary to induce tendon rupture was greater for tendons of the VEGF-111 group (but less than the results obtained with the PRP in our previous study), while the section areas of the tendons were similar. The mechanical stress was similar at 5 and 15 days in both groups but was improved for the VEGF-111 group at day 30. No differences were observed in the mRNA expression of collagen III, tenomodulin and MMP-9. Finally, we made a study, the aim of which was to evaluate the clinical status and the return to sports activities in patients with chronic upper patellar tendinopathies, up to one year after a single infiltration of PRP. Twenty patients with chronic upper patellar tendinopathy were enrolled. Assessments were made before infiltration of PRP, and 6 weeks, 3 months and 1 year after the infiltration, using a 10-point Visual Analogic Scale, clinical examinations with a pressure algometer, algofunctional scores (IKDC and VISA-P), functional assessments (isokinetic and optojump evaluations) and imagery (ultrasounds and MRI). The PRP was obtained with an apheresis system (COM.TEC, Fresenius). Six millilitres of PRP were injected without local anaesthetic. One week after infiltration, patients started a standardised sub-maximal eccentric reeducation. We observed that with time, during the 1-year follow-up, VAS dropped significantly and both IKDC and VISA-P scores improved also significantly. During functional evaluation, it decreased as well, but without significant functional improvement. No improvements in the imagery measurements were observed. Younger patients seemed to be more susceptible to have a relief of pain by the PRP infiltration. Seventy percent of the patients reported a favourable evolution with decrease of pain, 15% reported no improvement and 15% were treated surgically. Seventy percent returned to sports activities, 64,3% without any pain and 50% recovered the same sports level. Even if 1 infiltration seems to be efficient in the indication of patellar tendinopathies, most studies evaluated the effects of 3 successive infiltrations. However, the multiplication of infiltrations risks increasing complications, and this treatment can be expensive. It seemed relevant to evaluate if 2 infiltrations of PRP would be more effective than only 1.Twenty patients suffering from jumper’s knee for more than 3 months were enrolled and randomized in 2 groups (1 or 2 infiltrations of PRP). The follow-up was made as follows: VAS, IKDC and VISA-P scores, algometer, isokinetic and ultrasounds evaluations. The concentration of the PRP used for each infiltration was similar in both groups, without any red or white blood cells. Results for all the evaluations did not show any difference between the groups. The comparison of 1 or 2 infiltrations of PRP did not show any difference between the 2 groups after a follow-up of 3 months. A second close infiltration of PRP to treat upper patellar tendinopathies is not necessary to improve the efficacy of this treatment in the short term. However, these results must be evaluated at a longer term. [less ▲]

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See detailMultibody Modelling of Mechanical Transmission Systems in Vehicle Dynamics
Virlez, Geoffrey ULg

Doctoral thesis (2014)

This thesis addresses the dynamic modelling of automotive driveline components by means of the nonlinear finite element method for flexible multibody systems. Starting from a detailed study of an ... [more ▼]

This thesis addresses the dynamic modelling of automotive driveline components by means of the nonlinear finite element method for flexible multibody systems. Starting from a detailed study of an industrial application, the TORSEN differential, several contributions are proposed in the field of contact modelling. The contact between rigid bodies in several geometric configurations is investigated and the influence of the squeeze film of lubricating oil is studied. A contact formulation between flexible bodies modelled as superelements is also developed and applied to the modelling of 3D flexible gear pairs. [less ▲]

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See detailFunction of the chloroplastic hydrogenase in the microalga Chlamydomonas reinhardtii: A trvel from dark to light
Godaux, Damien ULg

Doctoral thesis (2014)

The decreasing availability of fossil energy stocks and the eventuality of tragic climate changes caused by greenhouse gases lead to search for alternative renewable energy sources. Biological hydrogen ... [more ▼]

The decreasing availability of fossil energy stocks and the eventuality of tragic climate changes caused by greenhouse gases lead to search for alternative renewable energy sources. Biological hydrogen might be one promising renewable energy carrier. A specific and restricted group of microalgae developed the ability to produce hydrogen based on an oxygen-sensitive hydrogenase enzyme coupled to the photosynthetic pathway, acting as a putative valve for excess electrons in conditions where other electron acceptors are scarce. The unicellular green alga Chlamydomonas reinhardtii is widely regarded as a model organism for various biological processes, especially for photosynthesis. Moreover, the capacity of Chlamydomonas hydrogenase is claimed as the highest recorded in literature. Less than twenty years ago, a group of American scientists designed a new approach for sustained photobiological production of hydrogen, based on a two-stage protocol that temporally separates photosynthetic O2 evolution from the H2 production phase (Melis et al., 2000). The transition occurs upon sulfur deprivation of the culture and leads to an operating continuous production for several days, opening new possibilities in the aim of an economically rentable bioproduction. For these reasons, hydrogen photoproduction in Chlamydomonas reinhardtii has been extensively examined in the last decade as extension of photosynthesis research entailing the understanding of hydrogen metabolism in microalgae (for reviews, see Hankamer et al., 2007; Ghirardi et al., 2009; Ghysels and Franck, 2010). Despite the attractive trait of generating a renewable fuel from nature’s most plentiful resources, i.e. light and water, the physiological significance of such oxygen-sensitive enzyme coupled to oxygenic photosynthesis has been poorly investigated with the exception of some old studies (Kessler, 1973; Schreiber and Vidaver, 1974). In this work, hydrogenase implication in photosynthetic reactivation from dark and anoxic environment is investigated. In the first part of the work, by analyzing several strains affected in hydrogen metabolism (e.g. nda2-RNAi (Jans et al., 2008), pfl1 (Philipps et al., 2011), dum11 (Dorthu et al., 1992)), we show that the PSII–dependent photosynthetic electron flow upon dark to light shift is linearly related to the activity of hydrogenase, both for short and long-terms adaptation (Publication I). In agreement with this conclusion, a hydrogenase-deficient strain for the HydEF maturation factor (hydef, Posewitz et al., 2004) shows peculiar chlorophyll fluorescence induction kinetics after adaptation to dark and anoxia. Based on these findings, a novel imaging screening method is developed, allowing rapid identification of strains impaired in hydrogen metabolism. Compared to existing screens (for review, see Hemschemeier et al., 2009), our protocol is remarkably fast, sensitive and non-invasive. At this stage, application of this new screening method allowed us to isolate several hydrogenase-deficient strains, among which one was impaired for the hydrogenase maturation protein HydG (hydg-2 mutant). Chlamydomonas reinhardtii might frequently encounter period of dark and anoxia in its natural habitat, especially during the night when the microbial community respires the available oxygen. In the second part of my work, the physiological importance of hydrogenase is investigated in the context of photosynthesis induction at the onset of light upon anoxia. In such conditions, the plastoquinone pool is known as being overreduced. This triggers the process of state transitions which is described as allowing the redistribution of light capture between both photosystems to manage the redox poise of the photosynthetic pathway (for review, see Lemeille and Rochaix, 2010). We therefore revisit the impact of both state transitions and hydrogenase activity on the reactivation of photosynthetic electron flow (Publication II). Here we show that, in presence of hydrogenase, photosynthesis reactivation is slightly faster in stt7 mutant locked in state 1 (Depege et al., 2003) compared to wild type which is in state 2. However, photosynthesis reactivation is delayed in hydef stt7-9 double mutant compared to hydef mutant. This indicates that, in a hydrogenase-deficient context, state 2 promotes photosynthesis reactivation. Considered for a long time as being tightly interconnected (Finazzi et al., 1999; Finazzi et al., 2002; Finazzi and Forti, 2004), state transitions and PSI-CEF have recently been revealed as unrelated to each other (Takahashi et al., 2013). Nonetheless, the increasing of PSI antenna size in state 2 could even though enhance the PSI-CEF rate, in an indirect way, by enhancing PSI energy capture (Cardol et al., 2009; Alric, 2014). This reasonably raises the question of a possible involvement of PSI-CEF in photosynthesis induction. This possibility is further studied in the third and last part of the work. Thanks to mutants devoid of PSI-CEF (i.e. pgrl1 mutant (Tolleter et al., 2011)) and hydrogenase activity (i.e. hydg-2 mutant (Publication I)), we investigate the role played by PSI-CEF along with hydrogenase during photosynthesis reactivation during a shift from dark anoxia to light (Publication III). Herein, we demonstrate that Calvin cycle reactivation is proton gradient-dependent, most likely due to ATP requirement for carbon dioxide fixation. By measuring the PSI/PSII efficiency ratio during the re- illumination period, we point out the physiological occurrence of PSI-CEF within the first minutes of ilumination. We therefore propose a schematic model that assesses the electron flow through hydrogenase, PSI-CEF and Calvin cycle in function of the illumination period in all studied strains. Although lack of PSI-CEF does not appear to be essential for cell survival, photosynthesis reactivation is delayed in pgrl1 mutants. We also isolate a pgrl1 hydg-2 double mutant and demonstrate that the combination of both defects prevents any photosynthetic activity and strongly impairs growth. This highlights the importance for algae to keep both pathways in the course of evolution, being critical for the survival of Chlamydomonas reinhardtii in its natural environment. [less ▲]

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See detailÉTUDE DU COMPLEXE ENZYMATIQUE DES SYMBIONTES DU TERMITE RETICULITERMES FLAVIPES (EX. SANTONENSIS)
Tarayre, Cédric ULg

Doctoral thesis (2014)

In the light of the economic, environmental and social context in which we live today, it has become obvious that the use of fossil fuels is not conceivable over the long term. Some alternatives have ... [more ▼]

In the light of the economic, environmental and social context in which we live today, it has become obvious that the use of fossil fuels is not conceivable over the long term. Some alternatives have therefore emerged in recent years. Second-generation biofuels are one of those alternatives and are based on the exploitation of vegetal biomass, also called lignocellulosic biomass. These materials require a hydrolysis step which can notably be achieved by enzymes. Some insects, such as termites, harbor complex microbial communities inside their digestive tracts. Those communities are able to produce enzymes which can be used in the field of the hydrolysis of vegetal biomass. This is what this thesis deals with. The main part of the work done focused on the research of enzyme-producing microorganisms (bacteria, mycetes and protists) responsible for the degradation of hemicelluloses and cellulose, the hydrolysis of which releases fermentable sugars. The insect which was used in this work was Reticulitermes flavipes (ex. santonensis), a lower termite, harboring a highly diversified internal microflora. This thesis describes the characterization of the microbial strains which were isolated and the enzymes they secrete. A complementary part of this research focussed on termites grown on artificial diets. The objective of this part was multiple : isolating enzyme-producing strains, not extractable according to the standard technique, and characterizing the microflora resulting from the applied artificial diets. This multidisciplinary approach was based on microscopy, proteomics, metagenomics and the assessment of metabolism applied to the different microbial consortia. [less ▲]

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See detailUnderstanding Random Forests: From Theory to Practice
Louppe, Gilles ULg

Doctoral thesis (2014)

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations ... [more ▼]

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations, unraveling underlying patterns in data and providing insights about the problem. Yet, caution should avoid using machine learning as a black-box tool, but rather consider it as a methodology, with a rational thought process that is entirely dependent on the problem under study. In particular, the use of algorithms should ideally require a reasonable understanding of their mechanisms, properties and limitations, in order to better apprehend and interpret their results. Accordingly, the goal of this thesis is to provide an in-depth analysis of random forests, consistently calling into question each and every part of the algorithm, in order to shed new light on its learning capabilities, inner workings and interpretability. The first part of this work studies the induction of decision trees and the construction of ensembles of randomized trees, motivating their design and purpose whenever possible. Our contributions follow with an original complexity analysis of random forests, showing their good computational performance and scalability, along with an in-depth discussion of their implementation details, as contributed within Scikit-Learn. In the second part of this work, we analyze and discuss the interpretability of random forests in the eyes of variable importance measures. The core of our contributions rests in the theoretical characterization of the Mean Decrease of Impurity variable importance measure, from which we prove and derive some of its properties in the case of multiway totally randomized trees and in asymptotic conditions. In consequence of this work, our analysis demonstrates that variable importances as computed from non-totally randomized trees (e.g., standard Random Forest) suffer from a combination of defects, due to masking effects, misestimations of node impurity or due to the binary structure of decision trees. Finally, the last part of this dissertation addresses limitations of random forests in the context of large datasets. Through extensive experiments, we show that subsampling both samples and features simultaneously provides on par performance while lowering at the same time the memory requirements. Overall this paradigm highlights an intriguing practical fact: there is often no need to build single models over immensely large datasets. Good performance can often be achieved by building models on (very) small random parts of the data and then combining them all in an ensemble, thereby avoiding all practical burdens of making large data fit into memory. [less ▲]

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See detailModelling the hygrothermal behaviour of crop-based construction materials
Dubois, Samuel ULg

Doctoral thesis (2014)

In the context of developing sustainable buildings, crop-based construction materials appear as valuable products given their intrinsic environmental and technical qualities. Their ability to exchange ... [more ▼]

In the context of developing sustainable buildings, crop-based construction materials appear as valuable products given their intrinsic environmental and technical qualities. Their ability to exchange moisture with the surrounding environment and damping humidity peaks in rooms, referred to as moisture buffering, is often presented as a way to improve occupants comfort and otentially reduce the operational energy of the building. It is understandable why modelling their hygrothermal behaviour and evaluating the impact on indoor air volumes is essential during the design phases. This thesis explores themodelling of the hygrothermal behaviour of crop-basedmaterials with a numerical tool. The latter is developed in a widespread general computational environment that brings both modularity and interoperability. Three challenges are addressed: the improvement of mathematical description of crop-based materials in non-standard operating conditions, the improvement of materials properties determination, and the assessment of their impact at room-scale. Several experimental facilities are developed in parallel to validate the proposed approaches, focusing on two materials expected to improve indoor conditions: straw bales and lime-hemp concrete. Results show that the developedmodel allows improving the understanding and the characterization of these green materials at various scales of study. [less ▲]

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See detailAltérations fonctionnelles des cellules dendritiques dans la cancérisation du col utérin
Demoulin, Stéphanie ULg

Doctoral thesis (2014)

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à ... [more ▼]

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à travers le monde. Actuellement, deux vaccins empêchant l'infection par des HR-HPV spécifiques sont disponibles, cependant, ils n'ont pas d'efficacité thérapeutique et il a été estimé qu'il n'y aura pas de baisse mesurable des cancers associés à HPV avant 2040. Même si l'infection par les HR-HPV est nécessaire à la carcinogenèse du col utérin, elle n'est pas suffisante pour le développement du cancer puisque seule une minorité des cas progresseront vers une tumeur. En effet, d’autres facteurs, liés à l’hôte ou environnementaux, qui agissent après l’infection peuvent augmenter le risque de développement cancéreux. Récemment, il a été proposé que les cellules épithéliales et/ou inflammatoires pourraient créer un environnement immunosuppresseur facilitant la transformation maligne en altérant l'immunité antitumorale. Etant donné que plusieurs études ont montré que le microenvironnement tumoral pouvait altérer la fonction des cellules dendritiques plasmacytoïdes (pDC) et conventionnelles (cDC) et les rendre tolérogènes, nous avons concentré notre attention sur ces cellules et sur leur rôle potentiel dans la cancérisation du col utérin. Dans la première partie de ce travail, nous nous sommes concentrés sur l'implication des pDC dans la cancérisation du col utérin. Nous avons d'abord montré que ces cellules sont recrutées au cours de la séquence "métaplasie-dysplasie-cancer" du col de l’utérus suite à l’augmentation de l'expression de la chémérine dans ces lésions. Etant donné que les pDC représentent un population cellulaire rare dans le sang périphérique, nous avons développé une nouvelle méthode afin de générer un grand nombre de pDC à partir d'un nombre limité de cellules progénitrices CD34+ isolées de sang de cordon ombilical. Notre but était de fournir un outil permettant de définir si la fonction de ces cellules peut être influencée par le microenvironnement tumoral. Les pDC générées in vitro présentent la morphologie, les caractéristiques phénotypiques et fonctionnelles des pDC se trouvant dans le sang périphérique. Les pDC générées in vitro ont été exposées aux molécules sécrétées dans le microenvironnement du cancer du col utérin grâce à un système de coculture. Ces pDC présentent un profil de maturation altéré, une diminution de sécrétion en IFN-α, une cytokine ayant un rôle antiviral et antitumoral. De plus, ces pDC sont capables d’induire la différenciation des lymphocytes T CD4+ naïfs en cellules T régulatrices (Treg) grâce à l’expression d’ICOSL. Les cellules Treg et les pDC forment des clusters autour des cellules cancéreuses, ce qui facilite leurs interactions. Nous avons identifié HMGB1 comme étant la molécule impliquée dans la modification du phénotype et de la fonction des pDC exposées au microenvironnement du col utérin. En parallèle, nous avons démontré que les cDC différenciées en présence de lignées de SCC du col utérin acquièrent un phénotype semi-mature et une activité fonctionnelle défectueuse, associée à une augmentation de leur sécrétion d'IL-10, une cytokine immunosuppressive. En outre, les cDC présentent également une fonction tolérogène associée à leur expression d’ILT3. L’inhibition de la voie de signalisation RANK/RANKL a permis de limiter l’effet des lignées de SCC sur les cDC. Ainsi, le cancer du col de l’utérus exploite activement la plasticité des pDC et des cDC afin de promouvoir sa progression. Des traitements ciblant HMGB1 et RANKL pourraient être utilisés afin de restaurer les activités anti-tumorales des cellules dendritiques et, par conséquent, de surmonter la tolérance immunitaire associée au microenvironnement du cancer du col utérin. [less ▲]

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See detailEtude du rôle des sites de N-glycosylation dans la pathogenèse induite par le virus de la leucémie bovine
De Brogniez, Alix ULg

Doctoral thesis (2014)

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes ... [more ▼]

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes économiques importantes dans l’industrie laitière et viandeuse de nombreux pays dont notamment les Etats-Unis, l’Argentine et le Brésil. Ce rétrovirus infecte les lymphocytes B à l’aide de ses glycoprotéines virales SU et TM qui fusionnent avec la membrane cellulaire. Bien que de nombreuses études se soient penchées sur la caractérisation de la propagation virale, les composants cellulaires et viraux impliqués dans le contrôle de ce mécanisme ne sont toujours pas élucidés. Mon projet de thèse s’est donc attaché à la compréhension du rôle joué par les 8 sites potentiels de glycosylation présents sur la protéine SU du BLV. Chaque site du gène a été muté individuellement par mutagenèse dirigée. L’expression, la localisation, la capacité de fusion cellulaire et la stabilité protéique ont d’abord été étudiées en culture. Des provirus mutés ont ensuite été inoculés à des moutons afin d’évaluer leur potentiel infectieux et de suivre l’évolution de la pathogenèse induite. Nos études ont permis de mettre en évidence un mécanisme de glycosylation qui limite la réplication virale et ralentit la pathogenèse en faveur de la persistance virale. [less ▲]

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See detailTheoretical studies of PbTiO3 and SrTiO3 under uniaxial mechanical constraints combining first-principles calculations and phenomenological Landau theory
Sharma, Henu ULg

Doctoral thesis (2014)

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory ... [more ▼]

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory. ABO$_3$ perovskites form a very important class of functional materials that can exhibit a broad range of properties (e.g., superconductivity, magnetism, ferroelectricity, multiferroism, metal-insulator transitions\ldots) within small distortions of the same simple prototype cubic structure. Though these compounds have been extensively studied both experimentally and computationally, there are still unresolved issues regarding the effect of pressure. In recent years, strain engineering has reported to be an original approach to tune the ferroelectric properties of perovskite ABO$_3$ compounds. While the effect of epitaxial biaxial strain and hydrostatic strain is rather well understood in this class of materials, very little is yet known regarding the effect of uniaxial mechanical constraints. Our study is motivated by the little existing understanding of the effect of uniaxial strain and stress, that has been up to now almost totally neglected. Two prototype compounds are studied in detail: PbTiO$_3$ and SrTiO$_3$. After a general introduction on ABO$_3$ compounds and calculations techniques (ab initio and phenomenological Landau model), we studied the effect of mechanical constraints in these compounds in our thesis. PbTiO$_3$ is a prototypical ferroelectric compound and also one of the parent components of the Pb(Zr,Ti)O$_3$ solid solution (PZT), which is the most widely used piezoelectrics. For PbTiO$_3$, we have shown that irrespectively of the uniaxial mechanical constraint applied, the system keeps a purely ferroelectric ground-state, with the polarization aligned either along the constraint direction ($FE_z$ phase) or along one of the pseudo-cubic axis perpendicular to it ($FE_x$ phase). This contrasts with the case of isotropic or biaxial mechanical constraints for which novel phases combining ferroelectric and antiferrodistortive motions have been previously reported. Under uniaxial strain, PbTiO$_3$ switches from a $FE_x$ ground state under compressive strain to $FE_z$ ground-state under tensile strain, beyond a critical strain $\eta_{zz}^c \approx +1$\%. Under uniaxial stress, PbTiO$_3$ exhibits either a $FE_x$ ground state under compression ($\sigma_{zz} < 0$) or a $FE_z$ ground state under tension ($\sigma_{zz} > 0$). Here, however, an abrupt jump of the structural parameters is also predicted under both compressive and tensile stresses at critical values $\sigma_{zz} \approx$ $+2$ GPa and $- 8$ GPa. This behavior appears similar to that predicted under negative isotropic pressure and might reveal practically useful to enhance the piezoelectric response in nanodevices. The second compound of interest is SrTiO$_3$. It has been widely studied in the past decades due to its unusual properties at low temperature. In this work, we have extended our previous investigations on PbTiO$_3$ by exploring theoretically the pressure effects on perovskite SrTiO$_3$ combining the first-principles calculations and a phenomenological Landau model. We have discussed the evolution of phonon frequencies of SrTiO$_3$ with the three isotropic, uniaxial and biaxial strains using first-principles calculations. We also reproduce the previous work done in SrTiO$_3$ with epitaxial strain and hydrostatic strain. Finally, we have calculated the phase diagram of SrTiO$_3$ under uniaxial strain, as obtained from Landau theory and discussed how it compares with the first-principles calculations. [less ▲]

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See detailBehavioral ecology and commensal long-tailed macaque (Macaca fascicularis) populations in Bali, Indonesia: impact of anthropic factors
Brotcorne, Fany ULg

Doctoral thesis (2014)

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges ... [more ▼]

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges for wildlife populations, another option relies on the sharing of space, i.e., tolerating wildlife living alongside human populations in non-protected interface zones. During the last century, massive human encroachment into wildlife natural habitat has led to an increasing number of worldwide interface zones and a consecutive intensification of the human-wildlife conflict which is likely to escalate further as human populations rapidly expand. However, conflict does not account for all the scenarios since diverse forms of interaction between humans and wildlife exist. The human-nonhuman primate commensalism is one of these possible interspecies associations. Commensal (or synanthropic) primates are free-ranging populations ecologically associated with humans in anthropogenic habitats and taking advantage of human food, waste or crops to supplement their diet. In Bali, Indonesia, humans and long-tailed macaques (Macaca fascicularis) already have a long history of coexistence. The forest-agricultural matrix landscape of the island and the numerous religious Hindu temples provide habitat patches for macaques sometimes living in very close proximity to humans. The opportunistic style of this species enables it to exploit numerous habitat types. However little is known about the ways anthropic factors impact its behavioral ecology. Our intention was to conduct a comparative study which would investigate whether anthropic factors were potential drivers of the behavioral ecology and population dynamics of Balinese macaques. During a two-year period in the field (between 2009 and 2013), using a protocol including three populations of Balinese macaques made of ten social groups, we documented variations in the activity, dietary, ranging and demographic patterns between populations. We systematically investigated the anthropogenic influences (i.e. human food provisioning degree and habitat anthropization level) on those variations, and we questioned the biological significance of the responses in terms of costs and benefits. While daily following each social group of macaques, we collected spatial, behavioral and botanical data, and we further conducted bi-annual demographic census in order to estimate the status and demographic trends of the study groups. Finally, our interest was to link our results with applied concerns regarding the management of these populations interacting with humans, while taking into account the implications of these interactions from the human point of view. We found a remarkable eco-behavioral diversity between our studied populations. Human food was a central component of their ecology, macaques preferentially exploiting this resource when available while retaining their abilities to forage on natural resources. The inclination for human food was optimal for macaques as it maximized their energy intake while minimizing the time expended for food acquisition. Therefore, they adjusted their activity budget according to the proportions of human food consumed. The free time available from relaxed foraging constraints was invested into resting and social activities. Macaques were flexible in their movements, making them successful in exploiting natural forest areas as well as highly anthropogenic habitats. However, increased social tension was a cost that stemmed from high-density situations induced by excessive anthropization of their habitat. We showed that, although predation risk partially influenced the selection of sleeping trees, proximity to human settlements appeared to be the most influential factor in the essential process of sleeping site choice by long-tailed macaques living at the edge of the forest and anthropogenic zones. Demographic data provide essential information to assess the status of a population and the long-term impacts of human pressures. Overall, our three studied populations displayed good reproductive performances and positive growth rates, probably due to the human food consumed. Indeed, we showed that the human food abundance in tourist sites may have diminished the density-dependence mechanism on macaques’ birth rates, to eventually inflate the size of populations. When combined with a high level of habitat anthropization, these effects have led to high local densities and even overcrowded situations with associated costs regarding within and between-group social tension and epidemic risks. In this framework, we documented the demographic and social impacts of a Streptococcus outbreak which occurred in the Ubud population in 2012. The pre- and post-epidemic study showed that macaques modified their social dynamics following a significant mortality in certain groups. This study emphasized the role of pathogens in regulating primate populations living in zones of interface with humans. Our research also contributed to identify solutions regarding management of these populations increasingly interacting with humans in Bali. We notably provided preliminary evidence that vasectomy, as sterilization technique to control for overpopulation, had no negative side-effects on social and sexual behaviors of male macaques. Finally, we assessed the effect of a ten-year management regime at the Ubud Monkey Forest, using an ethnoprimatological approach. We showed that the aggressiveness of macaques towards visitors had been effectively reduced and the high tolerance of local people towards macaques was determined by economic and cultural benefits deriving from the macaque presence. However, we also identified men and adult or subadult male macaques as the most exposed groups to a potential risk of cross-species pathogen transmission given the frequency of close physical contact interactions at this site. [less ▲]

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See detailModélisation et étude expérimentale du comportement de Saccharomyces cerevisiae (boulardii) lors de l'extrapolation du procédé à des bioréacteurs de volume industriel
Lejeune, Annick ULg

Doctoral thesis (2014)

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales ... [more ▼]

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales qui peuvent être dommageables pour les cellules se développant dans le réacteur. Il est donc important de prendre en compte le côté génie chimique pour comprendre quelles sont les conditions hydrodynamiques présentes dans le réacteur et ensuite s’attacher à étudier la réponse des cellules vis-à-vis de ces conditions. Ce travail se place dans le cas particulier de la production de biomasse de Saccharomyces cerevisiae (boulardii). Dans ce cas, le point critique est l’ajout de la solution concentrée de substrat dans le réacteur. L’utilisation de réacteurs scale-down a permis d’étudier différents cas de conditions hydrodynamiques défavorables, ainsi que leurs impacts sur différents paramètres. Dans un premier temps, l’étude des paramètres ségrégés (concentration en biomasse, en co-produits…) a montré, notamment, une diminution du rendement et une augmentation de la concentration en éthanol. Ensuite, l’étude s’est placée au niveau cellulaire avec l’utilisation de souches exprimant une protéine recombinante fluorescente et de marqueurs cellulaires fluorescents, couplée à la cytométrie en flux. Ces techniques ont permis de mettre en évidence la présence de différentes sous-populations cellulaires, ainsi que l’apparition du phénomène de résistance cellulaire aux stress lors de la production en réacteurs scale-down. L’importance du choix de la méthode de traitement des données cytométriques a également été débattue. Ce travail a abordé différents domaines pour tenter de mieux comprendre la réponse cellulaire aux fluctuations des conditions environnementales ressenties par Saccharomyces cerevisiae (boulardii) lors de productions en réacteurs mimant les conditions hydrodynamiques des réacteurs de grands volumes. [less ▲]

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See detailBilan de carbone d'une prairie pâturée en Région wallonne: effets du climat et de la gestion du pâturage
Jerome, Elisabeth ULg

Doctoral thesis (2014)

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – ... [more ▼]

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – CH4), this PhD investigates the C balance of an intensively managed grazed grassland in the temperate climate of southern Belgium. It analyses more particularly impact of climatic conditions and management practices on the C balance. The research site is a permanent grassland, covering 4.22 ha, intensively used for more than 50 years for Belgian Blue cattle grazing with the application of organic and inorganic fertilizers. Management practices but also climatic conditions are representative of livestock production systems developed in southern Belgium. Over a three years study period, soil C stock variations are determined indirectly by measuring the balance of C fluxes at the system boundaries. This approach not only takes into account CO2 and CH4 exchanged with the atmosphere but also organic C imports (manures, complementary feedings), exports (harvests, animal products) and C lost through leaching. CO2 fluxes are measured by eddy covariance while other C fluxes are estimated from data provided directly by the farmer, from punctual measurements and from aboveground herbage mass measurements. Considering only assimilation and respiration, the ecosystem behaves, on average, as a weak CO2 source, although the interannual variability is large. Interannual variability seems not to be significantly correlated with the main environmental drivers but rather influenced by fertilization management. Taking other C fluxes into account, the site appears as being at equilibrium. Management (organic fertilization), as well as climatic conditions that dictated them (complementary feeds), are the principal factors influencing the C balance. Finally, results show that management practices were the key control of the C flux variability at this grassland. Grazing impact on CO2 fluxes appears not explicitly at the seasonal and annual scale. It is therefore quantified by developing innovative eddy covariance data analyses and experiments. For that, indirect and direct grazing impacts are separated. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle modifying CO2 exchanges. To quantify it, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalised dark respiration (Rd,10) is analysed. On average, GPPmax decreases during grazing periods and increases during non-grazing periods. This could respectively be explained by aboveground biomass reduction and re-growth. In addition, GPPmax variations are negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 is found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. Direct impact results from livestock CO2 emissions through respiration that adds to the total ecosystem respiration. It is emphasized through specific designed livestock confinement experiments. Net CO2 exchange is compared on successive days with similar climatic conditions, livestock being confined (≈ 26 livestock units ha-1), or not, in the main wind direction area of the eddy covariance set-up. Results obtained are corroborated by independent estimates based on the C ingested by cattle during confinement. Finally, the C balance analysis of this particular grazed grassland in southern Belgium reveals that, taking into account the climatic conditions observed and the management practices developed over the three study years, the site is C neutral. This means that GHG emissions linked to fertilization (N2O) and grazing (CH4) are not partly mitigated by soil C sequestration. However, we conclude that, management practices being the main factor controlling the C balance, strategies to enhance soil C sequestration exist. If those kinds of management practices are studied, a global approach, taking into consideration both the C fluxes and other GHG fluxes, would be required to see if they do not induce supplementary N2O and CH4 emissions. [less ▲]

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See detailLes dynamiques socio-économiques autour de l'Aire Marine Protégée Communautaire de Bamboung (Delta du Saloum, Sénégal): entre conservation et développement territorial
Gaye, Ndickou ULg

Doctoral thesis (2014)

The problem of the marine protected areas (MPA) in Senegal raises the question of how to balance socioeconomic dynamics and preservation. Since 2004, the network of MPA has been implemented along the ... [more ▼]

The problem of the marine protected areas (MPA) in Senegal raises the question of how to balance socioeconomic dynamics and preservation. Since 2004, the network of MPA has been implemented along the Senegalese coast where communities are strongly dependent on fishery resources. The thesis debates the difficult compatibility between preservation and development, it analyzes the emergent social and economic dynamics related to the creation of the community marine protected area of Bamboung, located in the Reserve of Biosphere of the delta of Saloum (Senegal). In the context of the implementation of this MPAC, the analysis studies the relative possibility of balancing preservation and development, as taken in a territorial approach. The resultas are based on surveys, led between 2010 and 2014, with fishermen, women collecting mollusks and transforming the fish, managers of the tourist sector, administrators of the MPAC, but also the local authorities. The results show how the development processes is related to endogenous and exogenous factors. The MPAC creates some growth due to the eco-touristic lodge “Keur Bamboung”, but also to the protection of the local resources. Some pre-existing dynamics are reinforced. All of this can contribute to the revelation and to the emergence of territorial resources of the MPAC. [less ▲]

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See detailPotentialités et limites de la gestion participative des Aires Marines Protégées : Le cas de Joal-Fadiouth, Sénégal
Sene, Claude ULg

Doctoral thesis (2014)

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus ... [more ▼]

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus, this thesis aims to contribute to this emerging debate on MPA governance through reflections about the experience of a conservation project implemented by an international NGO (WWF WMPAO) in collaboration with the State and the local populations in Joal-Fadiouth, with a view to identify the catalysts social factors. The results show that the objectives of the MPA project are not purely local; they are strongly influenced by a global standard as well as regional and national dynamics. Thus, the MPA is much more seen as a conservation tool, whith sanctuarization as philosophical and conceptual basis. This logic of action has led to a real discrepancy between the original objectives and the outcomes in daily practice in the field. The victory of "sanctuarization" on local development, despite discourses based on a constructive approach of the integration paradigm, gave rise to tensions and multiple repulsive reactions and claims in relation to local territorial rights. And in this respect, MPA is a “reserve with reservation”: it refers, on the one hand to a "sanctuarized" space and, on the other, to an increasingly challenged social acceptance in relationship to local territorial dynamics. This thesis has shown, through three case studies, the real potential of co-management regimes, which main catalyst factors are, but not limited to, the setting in the core of the process of actors with real decision-making powers and responsibilities, of information and awareness raising, of financial incentives to overcome the limitations, of integration of scientific expertise to endogenous knowledge, of support of the State and its decentralized services, and of the strengthening of local capacities ... Those co-management experiences offer real additional strategic options to the MPA tool in a global approach to fisheries governance and territorialized development. However, the results of the thesis show also the limits of participatory management induced by the projects (obligation of results short time-frame) through the "formatting of local institutions of governance" especially a Management Committee, which is struggling to meet its "excessive" responsibilities in light of its very limited resources. This committee has become a "local brokerage arena" which captures and capitalizes on co-management resources and means; which tends to move the real power towards "intermediary actors" who serve as populations/State interface or even "exploit" the administration officials. This thesis has also highlighted the paradox of the State that justifies and provides legitimacy to local co-management processes through legal institutionalization, but does not mobilize the legal, financial, human and logistical resources required to guarantee and secure the implementation of the agreements reached between the different actors. It has more of a posture of an organizing State than that of a State guarantor of management agreements. [less ▲]

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See detailLes pêcheurs migrants de Guet-Ndar (Saint-Louis du Sénégal) : analyse d’une territorialité diverse entre espaces de conflits et espaces de gestion
Seck, Aichetou ULg

Doctoral thesis (2014)

In Western Africa and more particularly in Senegal, the fishing represents an important sector. This situation involves diverse communities which, for several decades, work in the small- scale fisheries ... [more ▼]

In Western Africa and more particularly in Senegal, the fishing represents an important sector. This situation involves diverse communities which, for several decades, work in the small- scale fisheries and which print in the sea their own socio- spatial dynamics. Among these, fishermen’s community of Guet-Ndar, a district of the “langue de Barbarie” located on the big Senegalese coast constitute one of the most notable halieutic societies. Very early, this littoral population made the activity of fishing its exclusive speciality. So, those fishermen developed around the sea, under the regime of free access, quite new practices of which various forms of migration along African west coast. However, with the overexploitation of the fish stock, the Guet-Ndar migrant fishing is not without facing confrontations with autochthonous fishermen. This research aims on one hand, at understanding the evolving territoriality of the migrant fishermen of Guet-Ndar through the prism of conflicts which appear on their halieutic space, notably in Cayar and in Mauritania. On the other hand, it tries to see how these sea craftmen adapt and are collectively organizing and redefining their territories through local mobilizations and within the framework of regional policies. [less ▲]

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See detailEtude de la fibrose pulmonaire idiopathique canine: analyse du transcriptome, investigation des voies du TGF beta 1 et recherche de biomarqueurs
Krafft, Emilie ULg

Doctoral thesis (2014)

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a ... [more ▼]

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a progressive deterioration until death from respiratory insufficiency. Clinical, tomodensitometric and histological characteristics of cIPF have been described recently. However, this disease remains largely unknown and the clinicians are dealing with two major challenges: confirmation of the diagnosis, which requires many complementary exams, and absence of effective treatment. Identification of a targeted therapy is difficult without having a good understanding of the mechanisms leading to pulmonary parenchyma fibrosis. A similar disease, the idiopathic pulmonary fibrosis (IPF) is recognized in humans and cIPF might be interesting as a spontaneous model. This project in dogs was undertaken to answer, at least partly, to these challenges. The aims were to elucidate some mechanisms involved in cIPF pathogenesis and to identify biomarkers that could be used in the diagnosis process. The hypotheses were first that analysis of the transcriptome through microarray experiment would identify altered biological functions in cIPF, highlight specific molecules with an altered expression and identify potential biomarkers. Another hypothesis was the transforming growth factor beta 1 (TGFB1) pathways, considered central in the pathogenesis of IPF, would also be modified in cIPF. Finally, ET1, a known biomarker in human IPF, might also be an interesting biomarker in dogs. Gene expression analysis through microarray analysis, combined with the use of IPA, a data analysis program, identified altered biological functions in cIPF: cellular growth and proliferation, developmental processes, cellular movement, cell to cell signaling and interaction and antigen presentation. Some genes highlighted in the microarray experiment were then analyzed individually. Quantitative RT-PCR analysis confirmed an upregulation of the expression of CCL2, CCL7, CXCL14, IL8 and FAP (fibroblast activation protein) as well as a downregulation of the expression of PLUNC (palate, lung and nasal epithelium associated). We then complete the gene expression analysis with a search for potential biomarkers. Thirty-four potential biomarkers were identified with 32 biomarkers potentially measurable in blood (including CCL2, serum amyloid 1, IL8) and 2 biomarkers measurable only in the bronchoalveolar lavage fluid (BALF) (PLUNC and mesothelin). This approach was validated by measurement in serum of one of this biomarker: CCL2. CCL2 serum concentration was higher in affected WHWT compared to healthy WHWT and also higher in dogs with cIPF compared to dogs with chronic bronchitis (CB) or eosinophilic bronchopneumopathy (EBP). Based on serum CCL2 determination, cIPF was diagnosed with a sensibility of 92% and a specificity of 80%. We then studied TGFB1 and part of its storage, activation and signaling pathways. TGFB1 gene expression was not significantly different in the pulmonary parenchyma between affected and control dogs. However, in affected dogs, increased TGFB1 protein levels were seen by immunohistochemistry in fibrotic areas. High expression of bothTGFB1 type I receptor and phosphorylated Smad2/3, markers of an active intracellular TGFB1 signal, were seen in epithelial cells. No difference in expression for the storage proteins LTBP1 and LTBP2 was seen while expression of LTBP4 was significantly decreased in dogs with cIPF. Concerning the proteins involved in TGFB1 activation, gene expression was decreased for integrin subunit β8, increased for thrombospondin-1 and not modified for integrin subunit β6. Expression of Smad 7, involved in intracellular TGFB1 signal inhibition, was not modified. No difference for TGFB1 serum concentration was seen between WHWT with cIPF and healthy WHWT. A multivariate analysis performed on healthy dogs showed no age effect but a significant breed effect with higher levels in predisposed breeds. We evaluated part of the serotonin pathway, as one of its receptor (5HTR2B) was highlighted during the gene expression analysis. Serotonin has also been involved in the pathogenesis of human IPF and described to be of potential use as a biomarker in degenerative mitral valve disease in dogs. Expression of 2 serotonin receptors (5HTR2A and 5HTR2B), evaluated by quantitative RT-PCR in pulmonary tissue, was not different between dogs with cIPF and control dogs while expression of the serotonin transporter (5HTT) was significantly lower in affected dogs. No difference in serotonin serum level was seen between affected and healthy WHWT or between dogs with cIPF, CB or EBP. ET1 was evaluated as a biomarker in serum and BALF. ET1 serum concentration was not different between healthy WHWT and Beagles. Covariance analysis did not reveal any significant age effect. Serum levels were significantly higher in dogs with cIPF compared to dogs with CB or EBP. ROC curve analysis was then used to evaluate its diagnostic performances. The area under the curve was 0,818 with a sensitivity of 91.7% and a specificity of 87.5%. ET1 was also measured in the BALF in a small number of dogs. Its concentration was measurable in all dogs with cIPF while it was below the detection limit in all other dogs tested (healthy and with CB). Even though cIPF and human IPF are not completely identical from clinical, tomodensitometric or histological points of view, these results show that both canine and human diseases share molecular pathways, supporting the idea that cIPF might have an interest as spontaneous model. This work allowed a better understanding of cIPF pathogenesis. Gene expression analysis in the pulmonary parenchyma of affected dogs first identified several altered biological functions that should be analyzed in details in further studies. A more targeted analysis of some genes confirmed an upregulated expression of CCL2, CCL7, CXCL14, IL8 and FAP. Such a positive regulation of the expression of various inflammatory cytokines tends to suggest that inflammation might have a role in cIPF pathogenesis. Some of these cytokines also have profibrotic properties. PLUNC was one of the top down-regulated genes. Roles of the protein are still largely unknown; it might have a role in the inflammatory response and in the innate immunity. Developmental pathways were also altered in cIPF and quantitative RT-PCR confirmed an upregulation of FAP, a protein normally expressed in areas of tissue remodeling during fetal development and also positively regulated in human IPF. This study has shown that there is an active TGFB1 signal in the lungs of dogs with cIPF, especially at the level of the pathological epithelium. TGFB1 storage and activation pathways also seemed to be altered. Elevated TGFB1 circulating levels were found in predisposed breeds, which might explain at least partly their susceptibility for cIPF. Because of these results and its well-known profibrotic properties, we can suggest that TGFB1 is probably involved in cIPF pathogenesis and that modulation of its storage, activation or intracellular signaling might offer potential therapeutic targets. Our preliminary results are not in favor of a significant modification of the serotonin pathways in cIPF, although a decreased expression of 5HTT was seen in affected dogs and might have an impact on the amount of serotonin present locally. However, other studies are needed to conclude. Finally, several potential biomarkers have been identified and some of them were evaluated in details. While serum measurements performed for TGFB1 and serotonin indicated that these molecules have no interest as diagnostic biomarkers, ET1 and CCL2 were identified as interesting candidates with good diagnostic performances. However these results need to be confirmed in an independent validation cohort and the interest of combining both biomarkers should be evaluated. [less ▲]

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See detailValorisation de l’information pédologique numérisée pour la modélisation de la percolation des pesticides vers les eaux souterraines
Bah, Boubacar Billo ULg

Doctoral thesis (2014)

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required ... [more ▼]

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required standard (0.1 µg L-1 by pesticide and 0.5 µg L-1 for all pesticides) for human drinking water is most often exceeded at some catchments. Tools such as mechanistic models are appropriate since they allow an a priori estimation of pesticide concentrations leached at the bottom of soil profile, which could reach the groundwater tables. However, simulations often lead to a degree of uncertainty due to the approximations noted in the models, or due to the reliability of available data. The main objective of this thesis was to improve the usefulness of the Digital Soil Map of Wallonia (DSMW) and the associated soil analysis database named “Aardewerk” in the framework of the evaluation of the groundwater table contamination by pesticides, in order to reduce approximations associated with the GeoPEARL model and its meta-model MetaPEARL in the area of Condroz. In order to cover the broad spectrum of pesticides used in agriculture in Wallonia, nine theoretical pesticides have been defined. The first research question is to measure the sensitivity of GeoPEARL to two soil data parameterization schemes at the regional scale, depending on whether we first aggregate soil data at a regional scale before application of the model (AC approach); or we first apply the model to soil profiles and aggregate simulated leached concentrations afterwards (CA approach). The results show a significant difference between the two approaches, compared on the basis of a spatial threshold (80th percentile) calculated by soil type. Moreover, this difference varies depending on pesticide type, and is more important when the simulated concentrations are very low. It is also clear from this analysis that only pesticides located in certain ranges of DT50 (30 and 67 days) and Kom (58 and 252 dm3 kg-1) give concentrations more often above water potability standard of 0.1 µg L-1. The second research question is to calibrate MetaPEARL metamodel (simplified model) based on GeoPEARL simulated concentrations, from which it was derived by considering only the most sensitive parameters of GeoPEARL. The objective by developing a metamodel is to provide a simple tool, usable for a first evaluation of pesticides leaching in order to identify the most risk-prone areas, but also readily transposable for a global decision support system. In contrast to the approach of MetaPEARL calibration used until now, taking into account soil morphology through soil horizons (layers) types explains about 80% of the spatial variability of pesticide concentrations obtained from the complete original GeoPEARL model. The third research question is to take into account the spatial variability of input variables within the same soil typological unit using stochastic simulations to assess the uncertainty associated with deterministic simulations (taking into account average values by soil type for the input variables at the regional scale) obtained from MetaPEARL. The random spread of soil characteristics variability leads to a very significant spreading of simulated pesticide concentrations. Moreover, we obtain values of 80th spatial probabilistic percentile higher than those obtained from the deterministic approach. Consequently, for a risk mapping designed to aid decision-making tools, the probabilistic approach should be used since it allows, by taking into account the spatial variability of the model input parameters, to obtain more realistic concentrations of leached pesticides. [less ▲]

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See detailMOLECULAR TOOLS APPLIED TO THE STUDY OF MICROCYSTIN-PRODUCING CYANOBACTERIA IN BELGIAN WATERBODIES
Lara, Yannick ULg

Doctoral thesis (2014)

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries ... [more ▼]

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries. These amenities are affected by recurrent mass proliferations of cyanobacteria. The latter are responsible for the production of a wide range of bioactive compounds, including potent toxins (cyanotoxins). These comprise neurotoxins, cytotoxins, inflammatory agents, and hepatotoxins. Microcystins (MCs), hepatotoxins and tumour promoters are the most documented of the cyanotoxins. The microcystin synthetase gene cluster (mcy) involved in MC biosynthesis consists of a succession of non-ribosomal peptide synthase (NRPS) and polyketide synthetase (PKS) genes. The main producers of MCs are Anabaena, Microcystis, and Planktothrix. However, it is not possible to distinguish a toxic from a non-toxic strain on the basis of their morphology. In the present study, molecular tools were used, optimized and developed to (i) characterize the 16S rRNA gene diversity of planktonic cyanobacteria, (ii) to detect the cyanobacteria responsible for the production of MCs, (iii) to identify the MCs producing taxa, and (iv) to determine the environmental factors that influence the dynamic of toxic and non-toxic genotypes in Belgian freshwaters. Eighty-nine strains were isolated and their 16S rRNA genes sequenced. The 16S rRNA gene diversity was studied in 32 samples by denaturing gradient gel electrophoresis (DGGE). In order to evaluate the contribution of this work to the study of the molecular diversity of cyanobacteria in Belgian waterbodies, 114 (strains and DGGE) sequences obtained during this PhD thesis were compared to Belgian sequences obtained by others. As a result, 14 previously undiscribed operational taxonomic units (OTUs) were found in the present study. For polymerase chain reaction (PCR) detection of the mcyA/B/E genes, the DNA from a total of 162 environmental samples was extracted. The three genes were found together in 64.2% of the samples, whereas the mcyB alone was detected in 95.1% of the samples. In order to identify the mcyE-carriers present in the freshwaters, a restriction fragment length polymorphism (RFLP) was performed on the mcyE gene. The presence of potentially toxic Microcystis was observed in most of the cases.To bypass the constraint of bacterial cultivation, a combination of whole genome amplification (WGA) and enzyme-linked immunoassay (ELISA) was tested on individual colonies of members of two cyanobacteria, Microcystis and Woronichinia, directly from the natural environment. Sequences of 3 different housekeeping genes (ftsZ, gltX, and recA), of 3 mcy genes, and the Internal Transcribed Spacer (ITS) were analyzed for 11 colonies of Microcystis. MCs were detected and quantified by ELISA in 7 of the 11 Microcystis colonies tested, in agreement with the detection of mcy genes. Sequence types (ST) based on the concatenated sequences of housekeeping genes from cyanobacterial colonies from Belgian water bodies appeared to be endemic when compared to those of strains described in the literature. One colony belonged to a yet undiscovered lineage. A similar protocol was used for 6 colonies of the genus Woronichinia, a taxon that is very difficult to cultivate in the laboratory. The 16S rRNA analysis confirmed the colony identification based on morphology. In addition, we obtained for the first time new genetic data for this genus, such as the rpoC1 gene sequences and the sequences and secondary structures of the ITS. The first discovery of NRPS and PKS DNA sequences in Woronichinia colonies highlights the need for further study of this widely occurring genus, to better assess its ability to produce MCs and/or related metabolites. For the first time, in this study, we were able to simultaneously monitor one toxic and one non-toxic genotype of M. aeruginosa using real time qPCR technology during a monitoring of 2 years. Both toxic and non-toxic genotypes dynamics appeared influenced by the photoperiod. In addition, the dynamic of the toxic genotype was influenced of light intensity. The results obtained during this PhD research show the need to characterize toxic cyanobacteria in freshwaters, as well as the conditions that influence MCs concentration dynamics. We showed that factors controlling the dynamics of toxic and non-toxic genotypes are complex. Nevertheless, detection tools can be developed to better understand these widely occurring phenomena. Therefore, efforts should go on in this field with collaborations between the scientists and the authorities. [less ▲]

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See detailBiologie de la reproduction et analyse du déterminisme et de la différenciation du sexe à des stades précoces chez le tilapia du Nil, Oreochromis niloticus
Gennotte, Vincent ULg

Doctoral thesis (2014)

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental ... [more ▼]

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental), ainsi que par une plasticité du contrôle génétique et endocrinien de la différenciation sexuelle incomparables parmi les autres vertébrés. Le tilapia du Nil (Oreochromis niloticus) est un cichlidé gonochorique possédant un système chromosomique de déterminisme sexuel à homogamétie femelle XX/XY, complété par un déterminisme environnemental, les hautes températures pouvant modifier le développement phénotypique du sexe. L’intérêt porté à cette espèce en aquaculture à conduit au développement de différentes techniques de contrôle du sexe (par traitement hormonal) permettant la production de poissons présentant différentes combinaisons de phénotype/génotype sexuels (mâles XX, XY, YY, femelles XX, XY et YY). Ces derniers constituent des outils majeurs de l’étude du déterminisme et de la différenciation du sexe et soulèvent de nombreuses questions concernant les interactions génotype/phénotype sexuels chez cette espèce. Au regard de ces considérations, nous nous sommes fixés 2 objectifs principaux : 1. Déterminer l’influence du génotype sexuel sur certains aspects liés à la biologie reproductive chez le tilapia du Nil tels que la qualité du sperme, les taux de stéroïdes sexuels (testostérone, T ; 17β-œstradiol, E2 ; 11-cétotestostérone, 11KT) et les comportements agressifs. Le génotype sexuel ne semble pas avoir d’influence sur la qualité gamétique des mâles, puisqu’aucune différence n’est observée entre les individus XX, XY et YY, alors que paradoxalement, les taux de 11KT sont plus élevés chez les mâles XX. De la même manière, les femelles présentent des taux croissants d’E2 chez les individus XX, XY et YY. Ces différences de taux de stéroïdes sexuels pourraient être liées aux taux d’agressivité (évalué par la quantification de huit comportements agonistiques dans des confrontations mâle-femelle) plus élevés des mâles XX et des femelles XY et YY et engendrer des perturbations des comportements reproducteurs. Des recherches complémentaires sont nécessaires d’une part, pour évaluer l’effet du génotype sur la qualité des gamètes des femelles et d’autre part, pour déterminer si les modifications phénotypiques observées sont liées à l’expression du génotype sexuel ou à des perturbations engendrées par les traitements hormonaux d’inversion sexuelle administrés durant la période de différenciation des gonades. 2. Explorer les mécanismes du déterminisme et de la différenciation à des stades précoces du développement. Grâce à la mise au point d’une technique d’inversion sexuelle ciblant les périodes embryonnaire et larvaire (avant 10 jpf) par des expositions courtes (4h) d’embryons âgés d’un jpf à des androgènes (11KT, 17α-méthyltestostérone), un inhibiteur de l’aromatase (Fadrozole) ou un œstrogène (17α-éthynylœstradiol), nous avons confirmé l’existence d’une période sensible de la différenciation sexuelle avant le développement des gonades. Les voies de différenciation phénotypique semblent être différentes en fonction du génotype, puisque la masculinisation des embryons XX est moins efficace (max 10%) que la féminisation d’embryons XY (max 91%). De la même manière, un probable effet chromosomique rend inefficace la féminisation d’embryons YY. La féminisation des individus XY est concomitante avec une augmentation des taux de T et d’E2 et d’expression de l’aromatase cérébrale à 4 jpf qui pourrait indiquer un rôle précoce du cerveau dans la différenciation sexuelle. Dans l’ensemble, nos résultats nous permettent de suggérer, d’une part, que les premiers événements moléculaires de la différenciation sexuelle du tilapia sont initiés avant la formation des gonades, et d’autre part, que chez les individus sexuellement inversés, des différences sexuelles peuvent apparaître dans le cerveau avant ou en même temps que le développement des gonades et induire des modifications comportementales à l’âge adulte. La question du rôle possible du cerveau dans la différenciation des gonades reste ouverte. [less ▲]

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See detailOrigin and properties of the two-dimensional electron gas at the LaAlO3/SrTiO3 interface: a first-principles hybrid functional study.
Fontaine, Denis ULg

Doctoral thesis (2014)

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations ... [more ▼]

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations are required, especially in oxide interfaces, where new and amazing phenomena can arise. A prototypical example is the LaAlO3-SrTiO3 interface that appear to be conducting, magnetic or even supra-conducting while these properties are not present in the LaAlO3 and SrTiO3 bulk insulator compounds. The conductivity arises from the formation of a highly localized electron gas at the interface which exhibits a different behavior than the one at semiconductor interfaces. Even nowadays, its exact origin, intrinsic versus extrinsic, is still intensively debated. The existence of an electric field in LaAlO3 used as a key feature of models based on an intrinsic origin is highly controversial. In these models, the closing of the band gap with increasing LaAlO3 film thicknesses finally results to a Zener breakdown and to the metal/insulator transition. In this Ph.D. thesis we aim to investigate the various consequences of the presence of an electric field in LaAlO3 through first-principles calculations in pristine LaAlO3-SrTiO3 interfaces. First, using both experimental and theoretical structural distortions in LaAlO3, we predicted a lattice expansion via an electrostrictive effect, supporting the existence of an electric field in LaAlO3. Second, the metal/insulator transition was tuned with regards to the intensity of the electric field in the film, which was controlled by the composition of a solid solution between LaAlO3 and SrTiO3. The theoretical results match the experimental one where, nevertheless, extrinsic origin mechanisms are allowed and defects are present. These two works are in favors of an intrinsic origin of the electronic gas observed in LaAlO3-SrTiO3 heterostructures. In addition, a relationship between the sheet carrier density and spatial extension of the gas was established and thus setting an intrinsic threshold to the sheet carrier concentration. At lower density the electrons are strictly localized close to the interface while above this value the carriers start to spill into the SrTiO3 substrate. [less ▲]

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See detailAnalyse de la variabilité naturelle du climat : application à l’aide des ondelettes
Mabille, Georges ULg

Doctoral thesis (2014)

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes ... [more ▼]

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes développé à l’Institut de Mathématique de l’Université de Liège, sont de l’ordre de quelques dizaines de mois. [less ▲]

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See detailMultiscale Finite Element Modeling of Nonlinear Quasistatic Electromagnetic Problems
Niyonzima, Innocent ULg

Doctoral thesis (2014)

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft ... [more ▼]

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft magnetic composites, used in the so-called magnetoquasistatic (low frequency) regime. Current homogenization models (e.g. the classical homogenization method, mean field homogenization, ...) fail to handle all the difficulties raised by the modeling of these materials, particularly taking into account the complexity of their microstructure and their nonlinear/hysteretic behaviour. In this thesis we develop a multiscale computational method which allows to effectively solve multiscale magnetoquasistatic problems. The technique is inspired by the HMM (heterogeneous multiscale method), which involves the resolution of two types of problems: a macroscale problem that captures slow variations of the overall solution, and many mesoscale problems that allow to determine the constitutive laws at the macroscale and to construct accurate local fields. Macroscale and mesoscale weak, b-conform and h-conform formulations, are derived starting from the two-scale convergence and the periodic unfolding methods. We also use the asymptotic homogenization method for deriving the homogenized linear material laws and, in the end, we derive scale transitions for bridging the scales. Numerical tests carried out in the two-dimensional case allow to validate the models. In the case of b-conform formulations, it is shown that the macroscale solution approximates well the average of the reference solution and that the resolution of the mesoscale problems allows to reconstruct accurate local fields and to compute accurate Joule losses and this, for materials with (non)linear and hysteretic behavior. Similar findings were obtained for the h-conform formulations. In both cases, the deterioration of the accuracy for mesoscale problems located near the boundary of the computational domain could be treated by defining suit- able mesoscale problems near such boundaries. The extension of the model to three-dimensional problems, to multiphysical problems and the inclusion of the mesoscale domains with a stochastic distribution of phases are also some of the possible prospects for improving this work. [less ▲]

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See detailDéveloppement de nouvelles méthodes de marquage au fluor-18 pour peptides et oligonucléotides en vue de leur études par tomographie par émission de positons
Flagothier, Jessica ULg

Doctoral thesis (2014)

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears ... [more ▼]

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears often as the radionuclide of choice for the preparation of short-lived positron-emitter radiotracers for PET studies. The fluorine-18 labelling reaction for biomolecules requires very mild conditions. The current method for highly efficient fluorine-18 labelling of biomolecules is the conjugation of a [18F]prosthetic group with a reactive function on the organic compound. During this thesis, two techniques were developed to label biomolecules via a [18F]prosthetic group: the first one to label tyrosine-containing peptides and the second one to label a siRNA. The first part of this work present the synthesis of the [18F]F-PTAD which is a agent for specific radiolabelling of tyrosine. [18F]F-PTAD was coupled with a tyrosine with a global radiochemical yield (synthesis, coupling, purification) of 20% (DC) and the synthesis lasts 2h30. During the second part of this work, two alkyne-bearing linkers were synthesized. These linkers were ligated with siRNA and then reacted with azide-bearing [18F]prosthetic group via a Huisgen cycloaddition reaction. The [18F]siRNA is then obtained with an global radiochemical yield of 12% (DC) and the synthesis lasts 2h00. In conclusion, two methods for labeling biomolecules have been developed. [less ▲]

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See detailFamily from afar: Moroccan migration, family practices and the transnational social space
Zickgraf, Caroline ULg

Doctoral thesis (2014)

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives ... [more ▼]

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives and analyzes their subsequent construction and reconstruction of familyhood across national borders. Through a multi-sited qualitative study into Moroccan family networks with residential nodes in Liège, Belgium and Oujda, Morocco, but also several other destinations, Caroline Zickgraf considers both the material and non-material functions of transnational family practices that together produce and inflate transnational social spaces. She treats both the social and physical geographies of these networks in order to understand how the circulation of people affects the circulation of care but also treats the tensions and asymmetries that characterize their multi-directional cross-border exchanges. [less ▲]

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See detailCARACTÉRISATION DE LA DIVERSITÉ GÉNÉTIQUE DE CULTIVARS D’OIGNON (ALLIUM CEPA L.) DU NIGER EN VUE DE LEUR CONSERVATION IN SITU ET DE LEUR AMÉLIORATION
Abdou, Rabiou ULg

Doctoral thesis (2014)

Plante monocotylédone, allogame, entomophile, avec un cycle cultural annuel pour la production des bulbes, bisannuel pour celle des graines, l’oignon est l’un des légumes le plus important au Niger en ... [more ▼]

Plante monocotylédone, allogame, entomophile, avec un cycle cultural annuel pour la production des bulbes, bisannuel pour celle des graines, l’oignon est l’un des légumes le plus important au Niger en raison de son utilisation en alimentation et en médecine. Le semis en pépinière suivi d’un repiquage des planches est le mode de culture le plus fréquent chez les producteurs nigériens. Cette étude explore la diversité génétique des cultivars d’oignon du Niger. La diversité est à comprendre ici au sens de la diversité nommée, la diversité morphologique et la diversité moléculaire. Cette thèse se propose d’utiliser ces trois approches complémentaires pour identifier et caractériser les variétés et écotypes selon la perception des producteurs, de caractériser la diversité morphologique et agronomique à partir des descripteurs du genre Allium établis par Bioversity International, et d’analyser la diversité moléculaire des variétés et écotypes d’oignon du Niger à partir des marqueurs moléculaires microsatellites. Cinquante-deux écotypes nommés ont été inventoriés, mais après analyse et regroupement des synonymes, il ressort que dix-sept écotypes sont cultivés au Niger. Les principaux critères des paysans pour caractériser un écotype local sont la couleur des bulbes et la zone de provenance. Les variables quantitatives et qualitatives les plus distinctives entre les écotypes d’oignon sont la longueur et le diamètre des feuilles, le poids des bulbes, la couleur des feuilles, la forme et la couleur des bulbes, l’uniformité de la forme et de la couleur des bulbes. La distance génétique est plus grande, d’une part, entre les écotypes les plus éloignées géographiquement, et d’autre part, entre les écotypes les plus différents au niveau des caractères morphologiques. Le nombre de morphotypes varie de un à neuf par écotype testé. Les analyses moléculaires confirment la forte variabilité à l’intérieur des écotypes et les conclusions relatives à la distance génétique observée à partir des données morphologiques. A l’issue de ces travaux de caractérisation génétique de l’oignon, il est donc utile de combiner des stratégies de conservation in situ et ex situ, et l’exploitation de ces ressources génétiques pour améliorer la production et la rusticité des cultivars d’oignon du Niger. [less ▲]

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See detailMulti-period Stochastic Optimization Problems in Transportation Management
Pironet, Thierry ULg

Doctoral thesis (2014)

The topic of this thesis in management science is to propose a methodology to tackle multi-period decision problems including stochastic forecasts and to apply it to the field of transportation management ... [more ▼]

The topic of this thesis in management science is to propose a methodology to tackle multi-period decision problems including stochastic forecasts and to apply it to the field of transportation management. This methodology relies mostly on a sequence of numerical experimentations based on a set of algorithms to assess the value of the multi-period setting and the interest to use the stochastic information contained in the forecasts. Moreover, a statistical validation method to compare the performances of algorithms enables us to rank them meaningfully. From theory to practice, the thesis is structured into four parts. Firstly, we define the thesis subject and content. Then, based on a literature review, we present the past and present issues within the research field: "Optimization in Transportation". Mainly, we define the differences between multi-period stochastic models and classical deterministic mono-period ones. We explain how dynamism and stochasticity are taken into account within transportation problems. Secondly, our methodology, which is our main contribution, is exposed from a generic point of view in the theoretical research field: "Multi-period Stochastic Optimization Problems". On the one hand, temporal parameters and computational issues in multi-period optimization are detailed; on the other hand a summary of optimization techniques and algorithms for stochastic optimization problems is provided. Afterwards, the statistical validation of algorithmic performance is discussed. Then, part three contains two applications that lead us to set up the methodology, following an inductive method. The first problem, based on an industrial application at the start of the research, investigates a "multi-period vehicle loading problem with stochastic release dates". The second application, based on a more generic approach for the deployment of the methodology, deals with a "multi-period vehicle assignment problem with stochastic load availability". Finally, in the fourth part, we conclude on the thesis contributions and propose some perspectives. [less ▲]

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See detailEtude de l'implication de cellulases dans la voie de biosynthèse de cellulose chez les bactéries
Delsaute, Maud ULg

Doctoral thesis (2014)

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact ... [more ▼]

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact contribution remains unclear. In the present study, we have investigated the involvement of cellulases from glycoside hydrolase family 5 (GH5) in cellulose synthesis. In particular, we have functionally and structurally characterized the Ps_Cel5A cellulase from Pseudomonas stutzeri and its metagenome-derived homolog RBcel1, which both belong to the GH5 family and are suspected to be involved in cellulose biosynthesis. In addition, we have also compared these enzymes with the well-characterized Ta_Cel5A cellulase from the cellulolytic fungus Thermoascus aurantiacus. The first part of the work was devoted to the description of the tridimensional structure of RBcel1, in comparison with other glycoside hydrolases from GH5. In the second part of the study, we focused on the functional and structural comparison between RBcel1, Ps_CelA and Ta_Cel5A. Biochemical analysis has highlighted that, besides their hydrolytic activity, RBcel1 and Ps_Cel5A were able to catalyze transglycosylation in vitro. This synthesis reaction was not detected for Ta_Cel5A, which seemed to remain hydrolytic only. Determination of the structure of RBcel1 in complex with cellobiose has revealed distinct features in the aglycone substrate binding sites compared to Ta_Cel5A which could potentially explain the observed differences in their activities in vitro. Finally, the involvement of Ps_Cel5A in cellulose production by P. stutzeri was confirmed, by analysis the ability of P. stutzeri-ΔPs_Cel5A to produce the polymer. Complementation of this mutant strain by the three cellulases was also performed and discussed. [less ▲]

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See detailLes effets délétères métaboliques et oxydants induits lors d'un sepsis sur la fonction rénale
Quoilin, Caroline ULg

Doctoral thesis (2014)

Acute kidney injury (AKI) is a frequent complication of sepsis that can increase mortality as high as 70%. The pathophysiology of this kidney failure was previously believed to be secondary to decreased ... [more ▼]

Acute kidney injury (AKI) is a frequent complication of sepsis that can increase mortality as high as 70%. The pathophysiology of this kidney failure was previously believed to be secondary to decreased global renal perfusion causing hypoxia-induced injury. However, new research suggests this paradigm is overly simplistic, and injury is now considered multifactorial in origin. Mechanisms that contribute to kidney injury mainly include inflammation, alterations in microvascular renal blood flow and changes in bioenergetics. To study the mechanism of oxygen regulation in acute kidney injury during sepsis, we developed a sepsis-induced in vitro model using proximal tubular epithelial cells (HK-2) exposed to a bacterial endotoxin (lipopolysaccharide, LPS). Our first investigation, by using both high-resolution respirometry and electron spin resonance spectroscopy, showed that HK-2 cells exhibit a decreased oxygen consumption rate when treated with LPS. Surprisingly, this cellular respiration alteration persists even after the stress factor is removed. We suggested that this irreversible decrease in renal oxygen consumption after LPS challenge is related to a pathologic metabolic down-regulation such as a lack of oxygen utilization by cells for ATP production. In the long term, this metabolic disturbance leads cells to a predominantly apoptotic death. To confirm this hypothesis of cytopathic hypoxia, we demonstrated that this alteration in the renal respiratory function is mainly due to an impairment in the metabolic activity of HK-2 cell mitochondria. Following LPS treatment, the oxidative phosphorylation is interrupted because of the inhibition of cytochrome c oxidase activity. As a consequence, disruptions in the electron transport and the proton pumping across the system occur, leading to a decrease of the mitochondrial membrane potential, the release of apoptotic-inducing factors and a decrease in ATP production. To clarify the mechanism by which the LPS induces mitochondrial alterations, we studied the oxidative stress generation in HK-2 cells. Interestingly, we revealed that the induction of a cytosolic oxidative stress is an event that appears before mitochondrial dysfunction in the LPS-treated HK-2 cells. This primary redox state is notably due to the activation of the two enzymes NADPH oxidase 4 and inducible NO synthase. The simultaneous production of anion superoxide and nitric oxide strongly suggests the formation of peroxynitrite, a relative stable powerful oxidant that can diffuse through mitochondrial compartments and undergo cytotoxic reactions. To our knowledge, our model reveals for the first time the role of NADPH oxidase-derived cytosolic ROS in triggering tubular cell damage. Moreover, after being first target of the oxidative stress, mitochondria become in turn producer of reactive oxygen species that carry on mitochondrial dysfunction. It seems thus that a mechanism of oxidative stress-induced redox cycling is a main cause of the mitochondrial dysfunction of LPS-treated HK-2 cells. The role of oxidants in mitochondrial dysfunction was further confirmed by the use of iNOS inhibitors or antioxidants that preserve cytochrome c oxidase activity and block mitochondrial membrane potential dissipation. Overall, these results suggest that sepsis-induced AKI should not only be regarded as failure of energy status but also as an integrated response, including transcriptional events, ROS signaling, mitochondrial activity and metabolic orientation such as apoptosis. [less ▲]

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See detailApport de la pédologie au conseil de fumure personnalisé par l’intégration d’arguments morphospatiaux et physico-chimiques impliquant de nouveaux outils d’analyse : la carte numérique des sols de Wallonie et la spectroscopie proche infrarouge
Genot, Valérie ULg

Doctoral thesis (2014)

The current environmental and agronomical context requires that farmers manage their inputs with the utmost precision, which can only be achieved by developing state of the art tools leading to clear ... [more ▼]

The current environmental and agronomical context requires that farmers manage their inputs with the utmost precision, which can only be achieved by developing state of the art tools leading to clear, exhaustive and efficient decisions. In this context, soil analysis being a vital tool, we have endeavoured to refine the advice given to farmers by the Walloon soil analysis laboratories, members of the non-profit-making organization REQUASUD, by studying the opportunity of developing two complementary tools, one cartographic, the other analytical, which can be integrated in the daily running of a laboratory. First of all, to ensure that soil analysis provides reliable results, it is essential for the sample to be as representative as possible of the plot. Lacking this representativity, an analytical result, however accurate, would be devoid of meaning and give the farmer misleading advice. In the field, the main obstacle for the soil sampler is the recognition of soil criteria which are however essential in establishing fertility advice, especially in Wallonia (southern Belgium) due to a high soil variability. The Digital Soil Map of Wallonia, surveyed at a scale of 1/5000, should prove to be an invaluable tool that can be used easily and directly for routine work not only by soil samplers but also by farmers and agronomists. That’s why a mapping web portal REQUACARTO has been designed to help define homogenous morpho-pedological areas and to validate them in different situations. Furthermore, in Wallonia, certain soil properties seldom undergo routine analysis, despite their importance in fertility advice, and when they do, they result in the use of extracts which are harmful to the environment and to health. Therefore we investigated the feasibility of a routine application of near infrared reflectance spectroscopy (NIRS) to determine these soil properties. This technique offers a number of advantages compared to analyses carried out according to reference methods: speed, respect of the environment and health, recovery of the sample, ease of use and thus economy. On a selection of representative samples of the pedological context of Wallonia, for which we also had analytical results of exchange cation capacity, as well as rates of carbon, nitrogen and clay, trials were performed using NIRS instead of or in addition to laboratory reference analyses. The findings highlight the relevance of using NIRS and were substantiated by a study of repeatability and intermediate precision of the technique. The spectral library was then transferred to the different soil analysis laboratories of the network. The goal is multiple: to offer further analyses to farmers at no extra cost, reduce the number of analyses performed according to reference methods and implement the spectral library with samples not predicted by NIRS to improve predictions. [less ▲]

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See detailModeling risk and expected returns in finance and macroeconomics
Lejeune, Thomas ULg

Doctoral thesis (2014)

This doctoral dissertation contributes to the modeling of risk and expected returns in the fields of finance and macroeconomics. On the finance side, the thesis proposes a portfolio choice model and a ... [more ▼]

This doctoral dissertation contributes to the modeling of risk and expected returns in the fields of finance and macroeconomics. On the finance side, the thesis proposes a portfolio choice model and a risk-return setup that simultaneously deal with agents’ unknown utility function, incomplete knowledge of financial return distributions, departures from the Gaussian distribution (i.e. asymmetry and fat-tail risks), investment horizons and investors’ objectives in terms of expected returns. On the macroeconomic side, the objective is to deliver a comprehensive picture of the financial sector in a general equilibrium framework, which accommodates the heterogeneity of behaviors within financial intermediaries. The first part of the thesis introduces an innovative risk measure, risk horizon, with reference to the speed of convergence of an asset’s mean return to its expectation. This measure is a keystone to a general framework for characterizing investors’ behavior in portfolio selection, which takes into account consideration for volatility, asymmetric and fat-tail risk, a trade-off between downside and upside potential of financial assets, and the timing and probability of deviations from expected returns. The risk horizon framework opens up the way to the identification of forward-looking determinants of market sentiment that includes, among others, the expected market and credit returns. The last part of the thesis is devoted to a macroeconomic model with heterogeneous and financially constrained intermediaries. An analysis of endogenous risk mechanisms when traditional and shadow banking interact is carried out. The model sheds light on the importance of relative leverage behaviors in the amplification of adverse shocks in the economy. [less ▲]

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See detailInteractions in massive binaries: spectral modelling – CoMBiSpeC – and observational analyses
Palate, Matthieu ULg

Doctoral thesis (2014)

Massive stars are very important to the life of the galaxiesbut they are rare and many open questions on their formation, evolution and characteristics remain. One of the best ways to improve our ... [more ▼]

Massive stars are very important to the life of the galaxiesbut they are rare and many open questions on their formation, evolution and characteristics remain. One of the best ways to improve our knowledge on massive stars is to study massive binaries (that represent at least 50% of massive stars see Mahy et al. 2009, and Sana & Evans 2011) and their spectra. Spectral and atmosphere modelling of stars are very interesting tools that are now often used in spectral analyses. However, these models are designed for single spherical stars. In this context, we have developed a numerical code of spectral modelling of massive binary systems: CoMBiSpeC (code of massive binary spectral computation) that computes the spectra of massive binary systems and accounts for various effects that affect these systems. Our models, and the observational analyses of the four binary systems presented in the second part of this work, have allowed to explain several effects linked to binarity: luminosity class discrepancy, temperature distribution, Struve-Sahade effect, and some kind of line profile variations. In summary, CoMBiSpeC is a first step in the spectral modelling of massive binary systems and several improvements are still needed to be able to study all massive binaries. Nevertheless, this model can explain and reproduce various observed phenomena which was the main goal of this thesis. [less ▲]

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See detailDiagnostic de sites et méthode d’implantation de tours pour une insertion urbaine de qualité
Saint-Pierre, Claire ULg

Doctoral thesis (2014)

The matter of towers construction in urban areas has been coming back among topical subjects, taking part in the questioning of sustainable urban development. While the debate still remains as regards ... [more ▼]

The matter of towers construction in urban areas has been coming back among topical subjects, taking part in the questioning of sustainable urban development. While the debate still remains as regards towers legitimacy, location choices are primarily driven by economic considerations (funding, real estate availability) and the issue of urban insertion is not always tackled at the right time. The decision-making process of tower construction is linear and takes into account some criteria relatively late even though if it was done earlier they could anticipate the impact of the tower on its urban environment. Using several comparative analysis (benchmarking), we identified the inherent criteria in this decision-making process. Their analysis and classification allowed us to highlight the preponderance of six criteria and the presence of significant interaction between them: the functionality, the shape, the movement, the public space, the environment and the townscape. The relations which exist between criteria reflect the complexity of the tower location process for which the most appropriate study approach seems to be the systemic. Between the multi-criteria analysis and the systemic approach, our implantation method of towers offers to consider these criteria at the very beginning of the project. Thus, it allows to draw up a list of indicators of urban integration which evaluation will indicate the quality of tower insertion in the urban environment. By considering upstream the identified criteria and also in a regular and diffuse way, the decision-making process of tower construction will be more efficient and effective to help finding the right location for a future tall building project. This implantation method is also designed to give rise discussions and reflections on the topics tackled, so that the dialogue between the actors turns towards a better location of towers in urban areas. [less ▲]

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See detailContribution à l'exploration de la structure des sols par microtomographie aux rayons X : vers une amélioration de la modélisation hydropédologique
Beckers, Eléonore ULg

Doctoral thesis (2014)

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil ... [more ▼]

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil hydrodynamic behaviour. This study takes place in this context, aiming to understand these modifications using X-ray microtomography (µCT), which allows a more fundamental analysis of soil. Indeed, this tool becomes a key in the field of soil science, giving a direct insight of the internal structure of soil. Besides, anisotropy studies are still rare as tiresome, and this work shows that the current hydrological models are anyway unable to represent it correctly: when it is taken into account, it rests on the hypothesis of a simple ratio between vertical and horizontal conductivity functions. First, microtomography is used supplementary to usual methods for the establishment of hydrodynamic functions near saturation. We showed that the retention curve designed with µCT information is more realistic since it leads to a better estimation of unsaturated hydraulic conductivity. However, these results could be doubtful depending on the different µCT acquisition or processing choices and hypothesis. Particularly, the thresholding step is crucial. Consequently, we propose a new global thresholding method based on the visible part of soil sample porosity. This method has been tested and validated in the context of the present study. This step allows us to use microtomography results to increase our knowledge of soil structure. A principal component analysis on soil pores structural parameters confirms that connectivity, specific surface, volume and radius are key factors for the differentiation of soil horizons texturally similar but structurally different. Our results show that structural parameters have to be taken into account to improve hydropedological modelling, especially if pores orientation is considered. We described thus the relevant parameters that can be obtained with µCT and which could help to better model water fluxes in soil while discussing the remaining limits and uncertainties, about upscaling issues notably. [less ▲]

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See detailExactitude du positionnement numérique des axes de ruissellement dans les bassins versants agricoles
Ouedraogo, Mohamar ULg

Doctoral thesis (2014)

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 ... [more ▼]

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 et 16,5 millions d’euros par an pour les habitations. La carte des zones à risque potentiel de ruissellement concentré est l’un des outils mis en place par la Wallonie pour lutter contre ces phénomènes de plus en plus fréquents. Cependant, la résolution (10 × 10 m) du MNT utilisé pour extraire les axes de ruissellement est trop faible pour prendre en compte les détails de la microtopographie (travail du sol, résidus de cultures, cultures…) des parcelles agricoles. De plus, elle ne tient pas compte des incertitudes inévitables, présentes dans les données altimétriques utilisées. L’objectif de cette thèse est d’envisager l’utilisation des nouvelles technologies d’acquisition des données altimétriques de haute densité (plusieurs points/m²), i.e., le scanner laser terrestre (TLS) et la photogrammétrie à partir d’un véhicule non piloté (VNP) pour créer un modèle numérique de terrain (MNT) de meilleure exactitude et de haute résolution spatiale (maille de dimensions ± 1 x 1 m). Cela permet de tenir compte de la variabilité altimétrique des parcelles agricoles, et d’analyser son impact sur le positionnement numérique des axes de ruissellement. Dans un premier temps, un TLS et un VNP à voilure fixe ont été utilisés pour acquérir des données altimétriques sur un bassin versant agricole de 12 ha. Deux logiciels photogrammétriques ont permis de générer le MNTPSC (Agisoft PhotoScan) et le MNTMCM (MicMac) ; tandis que des traitements statistiques ont été nécessaires pour supprimer les erreurs systématiques présentes dans les nuages de points obtenus au TLS avant de les fusionner pour générer le MNTTLS. La comparaison des MNT avec des points de contrôle (GCP) positionnés au récepteur GNSS (Global Navigation Satellite System) en mode RTK (Real Time Kinematic) a montré que le MNTTLS est le plus exact avec un RMSE (Root Mean Square Error) de 4,5 cm, suivi par le MNTMCM et le MNTPSC avec des RMSE valant respectivement 9,0 et 13,9 cm. Dans un second temps, la méthode de Monte Carlo a été utilisée pour générer à partir du MNTTLS, des MNT équiprobables. L’extraction des axes de ruissellement à partir des MNT équiprobables a permis de définir pour chaque maille du MNT, la probabilité d’appartenir à l’axe de ruissellement, et de définir une zone contenant l’axe de ruissellement extrait du MNTTLS avec une probabilité définie. Une telle zone peut être utilisée pour la mise en place de solutions telles que les bandes et les chenaux enherbés. La comparaison des algorithmes de suppressions des dépressions fermées d’une part, et des algorithmes d’extraction de la direction de l’eau d’autre part, a montré peu de différence au niveau de la probabilité d’appartenance des mailles à l’axe de ruissellement lorsque le MNT est de haute résolution spatiale (± 1 m). Enfin, les analyses statistiques ont montré que les altitudes des GCP utilisés dans la méthode de Monte Carlo sont influencées par l’état d’ameublissement et par la rugosité des sols des parcelles agricoles. Les études futures, e.g., à l’échelle de la Wallonie, devront prendre en compte l’impact de ces erreurs. [less ▲]

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See detailSur les quantifications équivariantes en supergéométrie de contact
Nibirantiza, Aboubacar ULg

Doctoral thesis (2014)

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See detailLe Comité permanent R dans sa relation avec le Parlement et certains acteurs du pouvoir exécutif : cohérence ou incohérence?
Stans, David ULg

Doctoral thesis (2014)

Il est possible d’envisager dans un Etat démocratique, bien que de manière un peu restrictive, que les deux grandes formes de contrôle traditionnelles opérées sur les services de renseignement (efficience ... [more ▼]

Il est possible d’envisager dans un Etat démocratique, bien que de manière un peu restrictive, que les deux grandes formes de contrôle traditionnelles opérées sur les services de renseignement (efficience et légalité) peuvent s’exercer, de manière très générale, suivant cinq axes différents : interne (hiérarchique), exécutif (tutelle ministérielle), externe (avec une composante parlementaire), judiciaire et médiatique/société civile. Chaque axe peut être composé ou se subdiviser en divers mécanismes qui agissent parfois dans une temporalité différente. Le recours à un Comité indépendant et externe tend à répondre aux dysfonctionnements des services (interne, coordination, rétention d’information, dépassement de compétences, etc.) et au manque de capacité tant pour le Parlement que pour l’Exécutif, de mettre en œuvre leurs prérogatives dans cette matière. Il est théorique admis que pour être véritablement démocratique, le contrôle de la gouvernance du renseignement doit comporter une composante parlementaire. C’est donc à ces acteurs que nous nous sommes intéressés. Le choix a été fait en Belgique de recourir à un organe externe chargé, dans sa mission générale, de surveiller le respect des Droits et Libertés des citoyens par les services et l’Ocam mais aussi leur efficience et coordination au profit et dans le respect des compétences de certains acteurs. L’objectif du Comité n’est donc pas de remplacer les autres acteurs. Ce contrôle doit, dans sa mission générale, permettre aux acteurs de jouer leur rôle (sans les remplacer) et conduire ainsi à la réalisation d’un véritable contrôle démocratique favorisant la responsabilité de la gouvernance du renseignement tout en respectant un équilibre indispensable secret et ouverture. Nous avons donc chercher à savoir si permettre l’intervention de certains acteurs de l’Exécutif dans un mécanisme indépendant et externe, d’une certaine manière rattaché au parlement est cohérent ou non ? [less ▲]

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See detailTowards a better understanding of time-lapse electrical resistivity properties associated to organic contaminants and bioremediation processes in the subsurface
Caterina, David ULg

Doctoral thesis (2014)

Management of contaminated sites represents a major problem for our society. Geophysical methods arise progressively as non-conventional techniques that should allow decreasing the uncertainty linked to ... [more ▼]

Management of contaminated sites represents a major problem for our society. Geophysical methods arise progressively as non-conventional techniques that should allow decreasing the uncertainty linked to the local nature of punctual drilling/sampling measurements classically used to identify, characterize and monitor such sites. However, the use of geophysics for this purpose is relatively recent and still requires an improvement of geophysical imaging and a better understanding of the impact of contaminants and remediation processes on measured properties to be fully effective. The main objective of this thesis was thus to improve our knowledge on these two aspects. In order to assess the reliability of geophysical imaging, and electrical resistivity tomography (ERT) in particular, we first compare quantitatively different image appraisal indicators. The latter are developed to detect artefacts, estimate depth of investigation, address parameters resolution and appraise ERT-derived geometry. Numerical benchmarks are created representing different geological situations in terms of heterogeneity and scale. On the basis of this comparison, we propose a methodology and guidelines to appraise both qualitatively and quantitatively field ERT images. We show the successful applications on real data coming from the contaminated sites we investigated. It notably allows us to exclude from our interpretation zones of the electrical images that are not considered as sufficiently reliable. To enhance electrical imaging, we investigate three different approaches to incorporate prior information into the ERT inverse problem, namely reference model, structural constraint and regularized geostatistical inversion that we notably apply on real data coming from two contaminated sites. The results are benchmarked against the standard smoothness constraint inversion. Results with real data show that adding prior information in the inversion process always lead to a modification of the solution at least in zones of low sensitivity (allowing notably to better image contaminant plumes at depth). However, the choice of the constraint to apply is highly dependent on the type and amount of information available. Therefore, we provide guidelines that should help the practitioner to include their prior information directly into the inversion process through an appropriate way. To understand the temporal geoelectrical signature of organic contaminants and bioremediation processes, we monitor a site contaminated with hydrocarbons and subjected to stimulated bioremediation. We first show that the most contaminated areas above the groundwater table level are associated to very low resistivities. We then show that during biostimulation (promoting aerobic degradation) and natural attenuation, observed resistivity variations (up to 140%) are mostly located in the saturated zone of the contaminated area. They follow a seasonal trend suggesting a temperature dependence not observed in an uncontaminated zone of the site. However, in the contaminated area, changes largely exceed the expected variations due only to the temperature. We therefore investigate systematically different hypotheses that may explain such changes. Among those hypotheses, we show that microbial activity is a factor that may potentially influence the electrical signature of a contaminated soil and may contribute to the observed resistivity changes. In order to further study the electrical response associated to bacterial activity during bioremediation processes, we monitor a tank experiment that contains soils contaminated with hydrocarbons subjected first to biostimulation and then to bioaugmentation (with an inoculum of Rhodococcus erythropolis T902.1). Whereas no particular electrical signature is observed during the biostimulation phase, we observe a correlation between the evolution of bulk resistivity changes and the specific oil-degrading flora after bioaugmentation that cannot be attributed to fluid resistivity changes. This suggests a direct impact of microbial growth/activity on electrical properties through the modification of surface and/or local electrolytic conduction mechanisms. These latter results open up new perspectives for future experiments that should involve spectral induced polarization measurements allowing a better discrimination between the two conduction mechanisms. [less ▲]

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See detailModélisation numérique de la localisation des déformations dans le béton avec un modèle de second gradient
Jouan, Gwendal ULg

Doctoral thesis (2014)

Cette thèse porte sur l’utilisation d’un modèle de second gradient pour les problèmes de localisation dans le béton. La localisation des déformations est un phénomène courant dans les solides qui ont subi ... [more ▼]

Cette thèse porte sur l’utilisation d’un modèle de second gradient pour les problèmes de localisation dans le béton. La localisation des déformations est un phénomène courant dans les solides qui ont subi des chargements importants et qui mène progressivement à la fissuration du milieu. D’un point de vue pratique, il importe de prévoir la possible occurrence de tels phénomènes et de simuler le comportement de la structure après son apparition (on parlera alors de comportement post-localisation). Pour modéliser de façon objective ce phénomène, le modèle dit de second gradient «local», cas particulier des milieux à microstructure, est ici appliqué à des structures en béton. Le comportement du modèle est étudié pour des essais représentatifs de telles structures (poutre en flexion, propagation de fissures en mode I). Certaines limitations du modèle dans le cas de localisations importantes des déformations sont mises en évidence et on propose la transition vers un modèle cohésif afin de décrire l’ensemble du processus de fissuration. Ce modèle cohésif et la transition depuis la description continue sont formulés et implémentés dans un code de calcul éléments finis. [less ▲]

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See detailContribution à l'étude épidémiologique d'Anaplasma phagocytophilum chez des cervidés et suidés sauvages en Région wallonne.
Nahayo, Adrien ULg

Doctoral thesis (2014)

Au cours des vingt dernières années, de nombreuses études ont souligné l’importance croissante des maladies vectorielles. Au sein des arthropodes, les tiques occupent la deuxième place, après les ... [more ▼]

Au cours des vingt dernières années, de nombreuses études ont souligné l’importance croissante des maladies vectorielles. Au sein des arthropodes, les tiques occupent la deuxième place, après les moustiques, en tant que vecteurs d’agents pathogènes. L’anaplasmose granulocytaire humaine est une zoonose transmise par des tiques et dont l’agent responsable est Anaplasma phagocytophilum, une bactérie intracellulaire obligée qui infecte essentiellement les granulocytes neutrophiles. L’anaplasmose granulocytaire est considérée comme une maladie émergente qui suscite l’intérêt du monde scientifique. Jusqu’à présent, de nombreuses études ont été réalisées aussi bien sur les tiques vectrices d’A. phagocytophilum que sur les différentes espèces animales considérées comme réservoirs. Mais il reste actuellement beaucoup d’inconnues quant aux multiples mammifères sauvages qui hébergent cette bactérie et qui pourraient être considérés comme réservoirs potentiels. Dans ce contexte, les objectifs généraux de cette thèse étaient de déterminer si A. phagocytophilum circule au sein des populations de cervidés sauvages (cerfs et chevreuils) présents dans la zone d’étude (Région wallonne), si ces espèces sont des réservoirs compétents pour A. phagocytophilum et enfin si ces espèces peuvent être utilisées comme sentinelles sanitaires pour la surveillance spécifique de l’anaplasmose granulocytaire humaine. En outre, vu les populations importantes de suidés sur l’ensemble de la région, l’espèce sanglier a été la troisième espèce cible incluse dans l’étude. Pour remplir ces objectifs, des prélèvements ciblés (sang et rate) ont été réalisés sur les espèces cibles dans le cadre du programme de surveillance active mis en œuvre par le réseau de surveillance décrit dans la première étude. En 2006 puis 2011 et 2012, 854 cervidés et 513 sangliers ont été prélevés au sein des 33 unités géographiques couvrant la zone d’étude. Les échantillons ont été identifiés en fonction de l’espèce, de l’âge, du sexe de l’animal ainsi que de la date et du lieu de prélèvement. Un test d’immunofluorescence indirecte a été réalisé sur sérum pour détecter les anticorps anti A. phagocytophilum et une PCR 16S (qui permet d’amplifier un fragment du gène qui code pour le RNA ribosomal 16S) a été mise en œuvre sur les échantillons spléniques. Une partie des amplicons obtenus a été séquencée. Les enquêtes menées en cervidés ont montré que la séroprévalence apparente globale, en 2006 et 2012, était respectivement de 95% et 88% pour l’espèce chevreuil et de 37% et 32% pour l’espèce cerf. Les résultats PCR ont révélé que 94% des cerfs (79 sur 84) et 81% de chevreuils (245 sur 300) étaient infectés par A. phagocytophilum et que les résultats positifs étaient uniformément répartis sur l’ensemble de la zone d’étude. Par contre, le taux d’infection des sangliers était très faible puisque moins de 1 % des rates étaient PCR positives. En conclusion, nous avons montré pour la première fois en Belgique qu’A. phagocytophilum circulait de manière endémique au sein des populations de cervidés sauvages vivant en Région wallonne. Deux enquêtes sérologiques ont fourni les premiers indices de présence de cette bactérie chez des cerfs et chevreuils. Les analyses PCR ont ensuite révélé que ces deux espèces étaient fortement infectées par A. phagocytophilum par opposition aux sangliers qui présentaient des taux d’infection très faibles. Sur l’ensemble des résultats PCR positifs, les 25 amplicons séquencés étaient identiques quelle que soit l’origine de l’espèce (cerf, chevreuil ou sanglier) et ils présentaient 100% de similitude avec 2 souches d’origine humaine et plusieurs souches d’origine animale. Des études supplémentaires, qui ciblent les gènes ankA et groESL, sont nécessaires pour déterminer si les variants d’A. phagocytophilum qui circulent en faune sauvage sont pathogènes pour l’homme. Le cas échéant, chevreuil et sanglier devraient être considérés comme espèces sentinelles sanitaires pour la surveillance spécifique de l’anaplasmose granulocytaire humaine. [less ▲]

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See detailQuels agritourismes pour les campagnes périurbaines ? Les cas de la Wallonie et du Grand-Duché de Luxembourg
Dubois, Charline ULg

Doctoral thesis (2014)

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and ... [more ▼]

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and are looking to diversify their activities. Taking advantage of certain assets related to their operation and of opportunities for tourism development in the region (such as availability of buildings, subsidies related to ecology and environment images), some of them have chosen agritourism, a tourist activity proposed by the farmer on his/her farm. The literature includes many studies on this topic, but there is no consensus on terminology, definitions, and concepts: they vary from one author to another and evolve over time. Having distinguished different agritourist typologies in which accommodation is a basic element, we have personally chosen to study agritourism defined as "all tourist and leisure activities and services present in a working farm". Wallonia and the Grand Duchy of Luxembourg, our geographical research areas, are neighbouring entities, with similar agriculture, and their tourist markets offer some similarities. Included in rural tourism, agritourism is nevertheless marginal compared to the overall tourist product offered. Some successes might suggest that agritourism could be the panacea against the crisis in agriculture. But is this always the case? Agritourism should be defined, localized, and differentiated. Working on these two periurban entities of Western Europe which are not yet discussed in the literature, we wanted to understand and to identify agritourist dynamics. We wanted to understand the geographic relationship between agritourism, periurban countryside, local resources, and agricultural and tourist specializations. We wanted to understand the logic of the emergence of tourism on a farm and the links between tourist and agricultural functions in a specific spatial context. Finally, we wanted to understand the integration of the motivations of different types of tourists and their reasons for visiting particular regional and local contexts. To do this, we analyse both the location and the agritourist geographical position in relation to the different markets. To meet the objectives, we conducted a comparative heuristic analysis of agritourism in both territories. We interviewed key organisational representatives (31 persons), we made field observations, documents comparisons... We conducted interviews with various Walloon and Luxembourg farmers (34 life histories) affording different agritourist practices that we synthesized by circumstantial geographical sketches. We conducted surveys with potential tourists (1148surveys) in seven Walloon and Luxembourg tourist spots. These steps and the statistical and cartographic processing based on the results allowed us to build a heuristic geographical model of the Walloon and Luxembourg agritourism. The experiences of farmers interviewed allowed us to understand the position of the agritourist system in its spatial context. Each of them develops opportunities and experience threats (economic, social, from heritage) in connection with the launch of the project, a true survival kit in some cases. It appears that agritourism is not always a panacea for farmers. On the farm, the tourist function comes after the agricultural one and is based on the latter, but the agricultural function also benefits from the tourist function because both activities are related. The emergence of tourism is an autonomous decision of the farmers who can be influenced by other actors, including authorities, but also by other factors such as the existence of a local demand or the regional real estate pressure. There is no particular profile of tourists visiting agritourism, but some features, including those of family, are more favourable to the experience of this type of tourism. Definitions and representations as well as the reasons and expectations differ depending on the characteristics of the interviewed tourists: urban or rural origin, level of experience. Three agritourist profiles were also highlighted: those seeking accommodation in a rural environment, those who think about accommodation linked to gastronomy, those who prefer accommodation that would be a comfortable basis from which to tour in a tourist area. The comparison between the experiences of farmers and the expectations of tourists shows that there is a risk of developing different organizational temporalities in the farm "open" to tourists as well as of favouring unbalanced images of agritourism, which could lead to a vision and a promotion of agriculture which does not correspond to its regional reality. By combining the different results and by linking the typology of the Walloon and Luxembourg agritourist products, the types of rural areas and the geographical components, it appears that agritourism should not only be analysed according to the environmental dimensions, but that the analysis must also take into account other factors such as accessibility, local communities, hospitality, rural development policies, the real estate market, the agricultural orientation of farm operations, as well as the degree of complementarity with tourist spots. We have demonstrated that agritourism, combining agriculture with tourism, is not developing, either everywhere, or in the same manner, and differs between different types of periurban countryside, depending on local resources. Moreover, agritourism is not always a solution for all countrysides, nor always a path for each farmer, nor always a perfect tourist destination for all tourists. However, even if strict regionalization of agritourism does not seem possible when we consider all the factors involved in the different regions, trends may emerge depending on agritourist types. There is thus a link between agritourism type and countryside type, which the heuristic model we propose should allow to improve in order to increase the convergence between the expectations of the different stakeholders. [less ▲]

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See detailPopulations of aphid natural enemies in agroecosystems, with special emphasis on the Multicoloured Asian Ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae)
Vandereycken, Axel ULg

Doctoral thesis (2014)

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some ... [more ▼]

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some cases the new imported species can spread out of control. These species can cause economical and ecological damages. The Multicoloured Asian ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is one of these species which was intentionally introduced for biological control and has spread from its native range in Central and Eastern Asia to large parts of North and South America, Europe and Africa. The decline of native species is linked to the spread and the aggressive behaviour of H. axyridis. The objective of this thesis is the evaluation of aphid's predator population densities and predator diversities, with a special focus on H. axyridis in agroecosystems in Wallonia, in the South of Belgium. First, field crops preferences of H. axyridis were determined. Later aphid's predator population changes during time were evaluated. Finally H. axyridis population changes between two crop farming were evaluated. Our main findings were as follows. Results, based on insects collected since 2001, highlighted that the first collected H. axyridis was in 2002 and the population of H. axyridis is increasing until 2008. In the same time population of Adalia bipunctata, Propylea quatuordecimpunctata and Psyllobora vigintiduopunctata, three native species, are decreasing. Samplings in agroecosystems highlighted that aphid's predator community is composed of few dominant species: three coccinellids Coccinella septempunctata, P. quatuordecimpunctata and H. axyridis, one syrphid Episyrphus balteatus and one chrysopid Chrysoperla carnea. We have shown that H. axyridis do not invade all Wallonia crops at the same rate because corn and broad bean are more invaded that wheat and potato at both larval and adult stages. Moreover in corn, H. axyridis populations has strongly increased from 2009 to 2011. Finally, organic farming do not enhance abundance of H. axyridis but lead to increase the total abundance of aphid natural enemies. [less ▲]

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See detailL'univers romanesque d'Hubert Juin : L'aventure d'une écriture
Kangomba, Lulamba ULg

Doctoral thesis (2014)

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices ... [more ▼]

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices near New Roman, without the texts claim to this literary movement. This analysis is closely related to the biographical and poetic texts of the author. The approach is characterized, first, by the work of literary pragmatics developed by Dominique Maingueneau; secondly, by the work on the space novel done by Jean Weisgerber. [less ▲]

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See detailRésonance locale et caractérisation de défauts de délaminage par vibrothermographie
Demy, Philippe ULg

Doctoral thesis (2014)

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant ... [more ▼]

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant, la méthode souffre d’un manque de fiabilité des résultats lié au chaos acoustique inhérent à la nature du contact pour la stimulation. La principale innovation de cette thèse consiste à étudier et proposer une méthode alternative à la vibrothermographie classique à partir d’un couplage linéaire obtenu par collage. La mise en évidence et l’étude d’un phénomène de résonance locale de délaminage a permis la mise au point d’une technique performante et fiable pour la détection et la caractérisation de défauts dans les matériaux composites. [less ▲]

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See detailEtude des propriétés de surface et techno-fonctionnelles des fractions protéose-peptones
Karamoko, Gaoussou ULg

Doctoral thesis (2014)

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of ... [more ▼]

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of surface properties and techno-functional properties (foaming and emulsifying properties) and well as setting a relationship between the different properties. In this work, PPT fractions were extracted according to a classical approach and other industrially transposable by considering respectively the skimmed UHT milk and whey protein concentrate (WPC) as raw materials. The using of such both sources allowed to highlight the fundamental differences in the composition of the extracts of PPT. This has begotten a direct impact on the surfactant properties of the PPT. It has been therefore established that these differences at interfaces can have major consequences on their techno-functional behavior. This study also made it possible to determine the contribution of components especially non-hydrophobic and hydrophobic fractions in the interfacial behavior of PPT and the influence of pH, protein concentration, source and method of extraction. The setting in relationship of properties showed the existence of some statistically significant correlations between the interfacial parameters and, foaming and emulsifying properties. It will be therefore possible to predict the behavior of techno-functional PPT from some physico-chemical parameters. Finally, this study also showed that PPT fractions can be used as techno-functional agents in various food formulations based foams or emulsions. [less ▲]

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See detailPopulation ecology of coastal bottlenose dolphins (Tursiops truncatus) in Northern Patagonia Argentina
Vermeulen, Els ULg

Doctoral thesis (2014)

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were ... [more ▼]

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were conducted in Bahía San Antonio, of which 227 were land-based and 129 were conducted from a small outboard-powered rigid-hull inflatable boat. In total, 1472 h was spend searching for dolphins, and resulted in 215 h of observation of 415 dolphin groups. Photo-identification data resulted in the identification of 67 individual dolphins. Based on mark-recapture analysis, total abundance had a maximum corrected estimate of 83 (95%CI = 46 - 152) individuals. Adult survival rates varied between 0.97 (SE = 0.04) and 0.99 (SE = 0.01). Average calving interval of the 14 reproducing females equalled 3.5 ± 1.0 years. This results in 3.5 births/year in the entire population and a minimum annual birth rate of 4.2%. However, data suggest that calves may have been born and lost before being documented, underestimating birth rate, calf mortality and possibly the number of reproductive females. Either way, the recruitment rate of calves appears to be insufficient to compensate the overall mortality in the population. Additional data further indicated the genetic isolation and extremely low genetic diversity within this community, thus indicating this community of bottlenose dolphins is highly vulnerable and at risk. Association patterns within the studied community were relatively strong (HWI 0.30 ± 0.08), re-indicating the small size of the population. Nonetheless, the fluctuation in prey density and availability appeared to be the most important factor determining their fission-fusion dynamics. It appears that a combination of aspects inherent to the species and this habitat, such as low cost of locomotion, low predation pressure and food predictability, has helped reduce the costs of fission in response to intraspecific competition. Behavioural data indicated that Bahía San Antonio is mainly used to rest and forage, with a marked diurnal and seasonal pattern in their activity. Furthermore, dolphins appeared to show a preference for the shallower waters inside their core area; they moved in and out with the tide to remain in the intertidal zone as much as possible. The observed variation in foraging activity and spatial distribution is suggested to be driven by a seasonal and locally predictable variation in prey density and availability. Most of the identified dolphins showed a yearlong residency and long term site-fidelity to Bahía San Antonio, suggesting it is the core area within the larger home range of this community. Furthermore, based on the frequent presence of calves and high residency of reproductive females, this protected coastal environment appears to provide shelter for nursing calves. Many individuals of this community ranged along the entire northern coastline of the San Matías Gulf, up to the Río Negro Estuary (approx. 200 km). Further to the north, in the southern part of the Province of Buenos Aires, a neighbouring community of bottlenose dolphins was shown to exist. Both communities are largely isolated from each other, and the environmental discontinuities between two adjacent oceanic regimes in which these communities live are hypothesised to promote their co-existence. Additionally, four individuals from another community, originating from the more southern Province of Chubut, are known to reside in Bahía San Antonio. These individuals are genetically differentiated from all other individuals in the area, clearly shown in their distinct morphology. The apparent fine-scale population structure of bottlenose dolphins over the relative small geographical distances in Argentina has conservation implications and indicates the need for further detailed research. Currently, the populations of bottlenose dolphins in the Provinces of Buenos Aires and Chubut are reported to have nearly vanished. However, this disappearance has been largely ignored in the past 40 years resulting in the studied communities to be one of the last ones remaining in the country. It seems that the coastal lifestyle and site-fidelity of coastal bottlenose dolphins, and the belief of the species to be common, may have obfuscated the need for more extensive research and conservation efforts in Argentina in former years. Local declines of common species are easily overlooked when establishing priorities for conservation, and Argentina is not a unique case. An ever-increasing number of coastal bottlenose dolphin populations are reported to be vulnerable or declining worldwide. This study provides insight into how the failure to recognise local population declines can threaten the regional status of a common species like the bottlenose dolphin. Continued research and urgent conservation measures are therefore strongly recommended to prevent the disappearance of the bottlenose dolphin from the coasts of this South American country. [less ▲]

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See detailPoéticas del fracaso en la narrativa de David Toscana
Scheffer, Aurélie ULg

Doctoral thesis (2014)

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer ... [more ▼]

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer la fréquence d’occurrence d'un mot en particulier: “échec” (fracaso). Cette thèse se propose d'examiner les différentes manifestations intratextuelles de l'échec (Bärtschi et Leuzinger) dans l’œuvre toscanienne, c'est-à-dire, les formes fictionnelles de l'échec. Nous avons choisi de diviser notre étude en deux chapitres principaux: personnages et espace. Dans le premier, nous mettons en relation la notion d'échec et les divers protagonistes qui peuplent l'univers toscanien et tentons de comprendre dans quelle mesure ces derniers peuvent recevoir le qualificatif de “ratés” (fracasados). Plus concrètement, cette observation des personnages principaux favorise la réflexion sur ce que David Freundenthal appelle échec interne, en d'autres termes, l'échec très personnel et subjectif que ressent et vit l'individu, frustré dans ses désirs, ses projets et ses tentatives. À notre étude de l'échec interne correspond une perspective d'analyse interne: dans un premier temps, nous privilégions une approche de l’œuvre essentiellement orientée vers le texte même, et par conséquent, volontairement détachée de son contexte. Si nous optons pour ce type d'approche, nous nous refusons cependant à nous limiter à une analyse strictement thématique. Ainsi, nous pensons l'échec tant d'un point de vue thématique qu'en fonction de ses manifestations dans le processus d'écriture, c'est-à-dire, à travers les techniques et structures narratives appliquées au texte littéraire. L’œuvre du narratologue français Gérard Genette intitulée Figures III nous sert d'appui théorique dans l'appréhension des formes narratives de l'échec. Le second chapitre met l'accent sur la relation entre échec et espace narratif. En réalité, tous les personnages de Toscana partagent un même espace, le Mexique. Selon nous, la représentation que l'auteur fait de cet espace est à son tour inséparable de la notion d'échec. Aux antipodes des “foundational fictions” (Sommer), l’œuvre met en scène une nation désunie, incapable de se définir, d'assumer le passer et d'aller vers l'avant, incapable de synthétiser ses divergences, de respecter ses traditions, de s'identifier à un profil de valeurs propre. Ainsi, par exemple, la famille et la religion apparaissent, sous la plume de Toscana, comme des valeurs stériles et insubstantielles. Cette approche ne renvoie donc plus à l'échec interne mais bien à l'échec diagnostiqué de l'extérieur ou échec externe, selon l'expression de Freundenthal: indirectement et avec subtilité, Toscana postule le non-aboutissement d'un projet, celui qui aspirait à la constitution d'une nation mexicaine forte et cohésive, orientée vers l'avenir. Ce second chapitre repose sur les principes majeurs de l'analyse du discours. Pratiquer l'analyse du discours suppose l'acceptation que chaque phrase porte en elle un message qui la dépasse et dont le sens est à chercher tant dans son contexte d'énonciation que d’interprétation. Rejetant l'opposition traditionnelle entre texte et contexte, entre un “intérieur” et un “extérieur”, l'analyse du discours littéraire privilégie une conception du texte comme maillon d'une longue chaîne appelée “interdiscours” et qui correspond à “l'ensemble des unités discursives avec lesquelles un discours particulier entre en relation implicite ou explicite” (Charaudeau et Maingueneau 2005: 334). Le texte littéraire est donc à considérer “relationnellement et historiquement” (Meizoz 2010: 66) puisqu'il s'inscrit toujours dans un processus de communication, dans un échange réel ou virtuel avec la parole d'autrui. Adoptant cette perspective, nous décidons de chercher et de créer du sens à travers la mise en relation du texte toscanien avec un certain discours sur la mexicanité. En fait, l'échec se manifeste selon nous à travers la présence d'une série d'images nationales stéréotypées que l'écrivain régiomontain récupère et manipule à sa guise dans l'ensemble de son œuvre. De ce jeu avec les stéréotypes découle la construction d'un imaginaire national déterminé traduisant, de manière implicite et symbolique, l'échec de la nation mexicaine. Ainsi, nous insistons notamment sur l’affinité entre la fiction toscanienne et le célèbre discours sur la mexicanité d'Octavio Paz, énoncé dans son essai Le labyrinthe de la solitude. Plus que de simples traces de banalité, ces stéréotypes qui envahissent l’œuvre de Toscana constituent à nos yeux de véritables éléments narratifs dotés d'une fonction constructive et productive propre. La théorie des stéréotypes, une des nombreuses théories littéraires qui se revendiquent de l'analyse du discours, constitue le cadre théorique principal de ce second chapitre. [less ▲]

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See detailBodies of Evidence: An Anthropology of the Health Claim
Hendrickx, Kim ULg

Doctoral thesis (2014)

How can a food or food ingredient be proven healthy, without calling it a drug? In this thesis, I make an attempt at understanding the stakes of a heated debate involving scientists from the food industry ... [more ▼]

How can a food or food ingredient be proven healthy, without calling it a drug? In this thesis, I make an attempt at understanding the stakes of a heated debate involving scientists from the food industry, academia, and the European regulatory authorities. The centrality and importance of 'science' in the debate is remarkable, and merits our full attention. The 'science' that is disputed between 'industry' and 'the regulatory authorities', and that serves as a vehicle for their credibility and authority respectively, consists of a very particular practice of putting molecules to the test in clinical trials. The clinical trial in drug testing allows for making a qualitative leap from a molecule's biological action to its therapeutic effect. In the case of food, it is not permitted to define the molecule's therapeutics in relation to pathology, otherwise the substance tips over and becomes a drug. The shared concern of all scientists involved in the debate is to avoid this 'tipping point'. What the debate shows, is not so much an opposition between 'corporate science' and 'regulatory science', but an uneasy relationship between the ecology of pharmaceutical drugs, and an ecology-yet-to-be-made for food therapeutics. Such an ecology rests upon a pattern of collaboration -or agencement- between materials and humans pertaining to different realms of production, regulation and science. As such, the terms of the debate on healthy food ingredients can be reformulated in more precise terms than 'industry' versus 'the authorities', or 'good science' versus 'bad science', which only come to exacerbate a deeper-lying tension that is technical and political at once. At stake are our conceptions of health and disease, cure and prevention, and the professionals that have the authority to talk about health in present-day Europe. [less ▲]

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