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

Master's dissertation (2012)

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Master's dissertation (2012)

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Master's dissertation (2012)

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

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

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

Doctoral thesis (2012)

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

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

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See detailÉvolution du bilan de masse de surface Antarctique par régionalisation physique et conséquences sur les variations du niveau des mers
Agosta, Cécile ULg

Doctoral thesis (2012)

The Antarctic surface mass balance (SMB, i.e. the snow accumulation from which we sub- tract ablation by sublimation, run-off or erosion) is a major yet poorly known contribution to changes in the present ... [more ▼]

The Antarctic surface mass balance (SMB, i.e. the snow accumulation from which we sub- tract ablation by sublimation, run-off or erosion) is a major yet poorly known contribution to changes in the present-day sea level. Water storage by snow accumulation at the top of the ice- sheet is expected to increase during the 21st century, which would moderate the rise in sea level. Three-quarters of the Antarctic SMB are concentrated below 2000 m above sea level whereas this area represents only 40% of the grounded ice sheet area. Orographic precipitation is a major contributor to snow accumulation in this region, which is why a better estimation of this term is important. The representation of this process by models depends to a great extent on the resolu- tion of the model, since precipitation amounts depend on the ice sheet slopes. Sublimation and snowmelt also depend on elevation. Global and regional atmospheric climate models are unable to achieve a 40-km resolution over Antarctica at a century time scale, due to their computing cost. At this resolution, ice-sheet margins are still badly resolved. <br />That is why we developed the downscaling model SMHiL (surface mass balance high-resolution downscaling), which estimates the Antarctic SMB components at a high resolution (∼15 km) from large-scale atmospheric forcings. We compute the impact of the high-resolution topography on orographic precipitation amounts and on the boundary-layer processes that lead to sublima- tion, melting and refreezing. To validate SMHiL, we compare our results with more than 2700 field data recently updated and quality-controlled. However, we exhibit that field data below 2000 m above sea level are too scarce to settle SMHiL efficiency. In light of this, we show that the GLACIOCLIM-SAMBA stake lines located on the ice sheet coast-to-plateau area is an ap- propriate reference to evaluate model performance. Finally, we downscale the atmospheric global climate model LMDZ4 to estimate the SMB changes during the 21st and 22nd centuries. The high-resolution SMB is significantly different from the SMB given by LMDZ4. Our results sug- gest that running LMDZ4 at a finer resolution may give a future increase in SMB in Antarctica between 15% to 30% higher than at its standard resolution. Future changes in the Antarctic SMB at low elevations will result from the conflict between higher snow accumulation and ru- noff. The downscaling model is a powerful tool that can be applied to climate models for a better assessment of a future rise in sea level. [less ▲]

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See detailAnalyse palynologique de divers sondages du secteur haute altitude du Parc National de Kahuzi-Biega: Paleoenvironnements et paleoclimats au Pleistocène supérieur et à l'Holocène
Kabonyi Nzabandora, Chantal ULg

Doctoral thesis (2012)

Palynological studies of sedimentary sequences issued from swamps located in the highlands of the KBNP (Kahuzi-Biega National Park) on the western divide of Kivu in Eastern Congo D.R., revealed important ... [more ▼]

Palynological studies of sedimentary sequences issued from swamps located in the highlands of the KBNP (Kahuzi-Biega National Park) on the western divide of Kivu in Eastern Congo D.R., revealed important environmental events that occurred during the last 35000 years. In the Upper Pleistocene, during the “Kalambo Interstadial” period (32000-26000 years BP), a mixed forest spread out under a moderately warm-wet climate. In the course of the “Mount Kenya Hypothermal” regressive phase (25000-15000 years BP), in the “Last Glacial Maximum” (20000-18000 years BP) takes place an exceptional expansion of open grasslands that evidenced an important drought. After that, the revival of an afro-montane forest growing under cold-wet climatic conditions is recorded, but that one is temporarily interrupted by theYoung Dryas dry pulse. At the Humid Holocene Period (10000-7000 years BP), with the increase of rainfall, the Kivu Lake level is raising when the swamps in the highlands are transformed in lakes. Around 6500 yrs BP, the afro-montane rainforest invaded by afro-subalpine taxa turns into a secondary mixed forest as the result of a climatic deterioration. At 4000 yrs BP, an important spreading of grasslands in the highlands and of savannas in the lowlands testifies that an aridity peak occurs at the time. The changes that occurs from 3000 years BP to 2000 years BP in the afro-montane forest suggests a climatic instability that moreover speeds up erosion processes. In the course of the first millennium AD, rainforest grows again; that event being shortly interrupted by a drought around 500 years AD. At the beginning of the second millennium AD, the lower belt of the forest is yet deteriorated by anthropic action while middle and upper belts are stable but marked by a fresh climate resulting of the “Mount Kenya Neoglacial” influence. From 17th – 18th centuries, human impact increases progressively in the highlands. On the eastern divide of Kivu, where seasons are more contrasted, the environmental events of the first part of Holocene are registered in the peaty sedimentary sequences. A heterogeneous forest evolved from 10000 years BP till 6000 years BP into an afro-montane rainforest by warming of a humid climate. Then, from the arid climatic phase of 4000 years BP till today, the various environmental events follow each other in the eastern as in the western side of the rift. [less ▲]

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See detailBiohydrogen Production by the Citrobacter and Clostridium Genera : a Metabolic and Biomolecular Perspective
Hamilton, Christopher ULg

Doctoral thesis (2012)

The research activities described in this Thesis were carried out in the Walloon Centre of Industrial Biology at the University of Liege. Laboratory experiments were performed with Citrobacter freundii ... [more ▼]

The research activities described in this Thesis were carried out in the Walloon Centre of Industrial Biology at the University of Liege. Laboratory experiments were performed with Citrobacter freundii CWBI952, a facultative anaerobe of the Enterobacteriaceae family, and Clostridium butyricum CWBI1009, a strict anaerobe of the Clostridium genus, to produce hydrogen by dark fermentation of glucose in flasks and in bench-scale bioreactors maintained at 30°C. The aim of the research activities was not only to optimise the key determinants of H2 production, namely pH, nitrogen and iron concentrations, and the dilution rate, but also to gain a better understanding of the relatively unknown hydrogen production metabolism. This was done by monitoring the H2 production activity and tracking the net carbon and electron equivalent balances. The results for C. freundii CWBI952 (Chapter II) indicated that maximum hydrogen production activity, formate biosynthesis and glucose uptake rates were obtained at pH 5.9. Optimal overall performance (33.2 mLH2/L.h and 0.83 molH2/molglucose) was obtained in a semicontinuous culture with a dilution rate of 0.012 h-1. The best performance for C. butyricum CWBI1009 (Chapter V), i.e. 1.44 LH2/h and a yield of 2.02 molH2/molglucose, was associated with butyrate fermentation and obtained in a 20 L batch bioreactor at the optimal pH value of 5.2. For both of these strains we demonstrated that it should be possible to radically reduce nitrogen feedstock costs by replacing casein peptone with (NH4)2SO4, an ammoniacal substance closely related to the mineral nitrogen content of livestock manure. Additionally for C. butyricum CWBI1009 (Chapter III) we showed that a certain range of nitrogen content (0.56-0.062 gN/L) favours H2 production activity. This was confirmed by an analysis of the gene expression pattern, which suggested that the HydB2 gene was responsible for the H2 yield increase observed at 0.062 gN/L. Our investigations provided a better understanding of the highly diversified H2-production metabolism of C. butyricum CWBI1009 by mapping the distribution pattern for its carbon and electron fluxes (Chapters IV and V). This was done using three complementary approaches to study the metabolome (HPLC RID-UV), transcriptome (RT-qPCR and RNAseq) and the proteome (2D-DIGE). Tests under various different pH conditions showed that the role played by the different hydrogenases and the nitrogenase in H2 production varied substantially depending on the particular environmental conditions. At the end of the Thesis the discussion (Chapter VI) provides a general overview of the results obtained for the optimisation of the dark fermentation process parameters and an analysis of how these investigations have advanced our understanding of the metabolic processes involved. Potential industrial applications are reviewed and suggestions for further research are made. [less ▲]

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See detailUsage de l’agriculture dans le social : Dispositifs, pratiques et formes d’engagement
Muramatsu, Kenjiro ULg

Doctoral thesis (2012)

This thesis deals with the ethnographical and sociological analyses of the modes of use of agriculture “in the social sphere”. Two Japanese and Belgian municipal actions are treated in parallel: The ... [more ▼]

This thesis deals with the ethnographical and sociological analyses of the modes of use of agriculture “in the social sphere”. Two Japanese and Belgian municipal actions are treated in parallel: The Centre for the Creation of Agri-rural Life (Nô-Life Sôsei Center in Japanese) launched in 2004 in Toyota City, which aims at the reinvigoration of fallow land and the promotion of the ikigai (“Life worth living”) for an aging population of permanent residents. In Belgium, the Work Training Initiative at Ferme Delsamme (Entreprise de Formation par le Travail Ferme Delsamme in French) launched in 2002 in La Louvière City, which aims at the socio-professional integration of at-risk adults through organic agriculture. Based on the analysis of forms of engagement of operators and users in their relationships of interaction and their efforts at adjustment of the tension, this thesis proposes the idea of “ethical” regimes of action that consist of a minimum number of principles for reflection and practice available to be used by actors. This thesis identified in particular the importance of two characteristic forms of these regimes: compassion (taking an infinite responsibility to address individuals in distress) amongst operators; social autonomy (the balance between individual autonomy and relational dependency based on the recognition of vulnerability and fragility) amongst users. Agricultural activity is defined here as the intermediate space supporting the combination and the performance of these regimes that are not very visible and formalized, and difficult to objectify and justify. [less ▲]

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See detailPerspectives on parameters influencing entrepreneurial intentions
Heuer, Annamaria ULg

Doctoral thesis (2012)

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See detailEtude des facteurs écologiques influençant la croissance et le développement des Pectobacterium spp. infectant les tubercules de pomme de terre.
Moh, Ahoussi Augustin ULg

Doctoral thesis (2012)

Pectobacterium atrosepticum (Pba) and Pectobacterium carotovorum subsp. carotovorum (Pcc) are the main cause of potato tuber decay (soft rot) in storage and stem rot in the field (blackleg). It has been ... [more ▼]

Pectobacterium atrosepticum (Pba) and Pectobacterium carotovorum subsp. carotovorum (Pcc) are the main cause of potato tuber decay (soft rot) in storage and stem rot in the field (blackleg). It has been reported that ecological parameters such as humidity and temperature, greatly influence the disease development. The objective of the present study was to evaluate and model the growth of two phytopathogens bacteria (Pba and Pcc) under various ecological conditions at the level of wounded potatoes tubers. To this purpose, we adopted two experimental approaches named in vitro approach and in vivo approach. We determined in vitro the effect of water activity (0.960, 0.980 and 0.997) and temperature (10, 15 and 20°C) and their interactions on the growth parameters and pectate lyases (PEL) specific activity of Pba and Pcc using optical density (OD) measurement. Statistical analysis showed a significant effect of aw and temperature on µmax. Our result showed an increase of PEL specific activity with the temperature whatever the bacterial strains. But contrary to the bacterial growth, this research did not show an increase of PEL specific activity with aw except the treatment at 15 and 20°C for the two bacteria strains. According to our results on growth and PEL production, we concluded that Pba and Pcc had the same behaviour in the range of the values of the two factors (aw and temperature) investigated here. The studies made in vivo were consisted to evaluate and model the influence of temperature (10, 15 and 20°C), relative humidity (86, 96 and 100%) and initial concentration of bacterial inoculum (105, 107 and 109 CFU/ml) on the population density of Pba and Pcc, and on the development of soft rot symptoms caused by these bacteria at the surface of wounded potatoes tubers. With both bacterial species, statistical analysis showed a significant effect of temperature, relative humidity and initially applied bacterial concentration on population dynamics and soft rot development at the surface of wounded potato tubers. Multiple regression analyses and the contour plots showed that the temperature is the most important factor, followed by the initially applied bacteria concentration and relative humidity. More than 64% of the variability of the soft rot symptoms observed could be explained by the presence of Pba and Pcc at the level of wounded potato tubers under the combined effect of tested factors. The quadratic polynomial models developed (in vitro and in vivo) in our research, by means of the response surface methodology, should integrate in further research the large genetic variation (which was not evaluated in this investigation) within Pectobacterium genus (Pba and Pcc) and Dickeya spp. [less ▲]

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See detailProduction de biohydrogène par fermentation anaérobie chimiotrophe de substrats carbohydratés
Hiligsmann, Serge ULg

Doctoral thesis (2012)

Hydrogen (H2) is being considered as an ideal and clean energy carrier since the utilization of hydrogen, either via combustion or via fuel cells, results in pure water. The recent advances to produce ... [more ▼]

Hydrogen (H2) is being considered as an ideal and clean energy carrier since the utilization of hydrogen, either via combustion or via fuel cells, results in pure water. The recent advances to produce biohydrogen from renewable sources such as biomass and particularly by fermentation of carbohydrate-rich substrates from agriculture and agro-industries appear promising. Such a process called “dark fermentation” enables both organic waste treatment and renewable energy production to be coupled. In the thesis different hydrogen-producing microorganisms were studied and some environmental parameters and bioreactors have been investigated in order to improve the hydrogen production yields and rates. The experimental results compared the hydrogen production yield of 19 different pure strains and sludges : facultative and strict anaerobic H2-producing strains along with anaerobic digester sludges thermally pre-treated (to enrich the microflora in high H2-producers) or not. Significant yields variations were recorded even between different strains of the same species (up to 20% of variation). The pure Clostridium butyricum (C. but.) strains achieved the highest yields i.e. up to 172 L H2 produced per kilogram of glucose consumed (1.38 mol H2 / mol glucose). Two efficient H2-producing strains (C. but. CWBI1009 and Citrobacter freundii CWBI952) were further studied in order to determine the optimum culture conditions for the production of hydrogen. A 2.3 L bioreactor was operated at 30 °C in batch and sequenced-batch mode using glucose and starch as substrates. For glucose the maximum yield (211 L H2 / kg or 1.7 mol H2 / mol glucose) was measured with the C. but. strain when the pH was maintained at 5.2. In sequenced-batch reactor a 35% increase in H2 yield was obtained with removal–addition of 40% of the culture medium at the beginning of each sequence. For operation in continuous mode, original bioreactors such as an anaerobic biodisc reactor (AnBDR) were designed to both fix biomass and enable rapid liquid to gas transfer of hydrogen produced since H2 partial pressure and H2 supersaturation are known as hardly affecting hydrogen production performances. The highest and stable H2 production rate (703 L H2 per hour and per m³ of liquid volume inside the bioreactor) and yield (302 L / kg glucose consumed i.e. 2.4 mol/mol) with the pure culture of C. but. CWBI1009 were recorded in the AnBDR with 300 mL culture medium (total volume 2.3 L) at pH 5.2 and a glucose loading rate of 2.87 kg / m³.h. These results achieved with pure strains are relevant compared to the highest H2 yields and rates reported in the literature with mixed cultures and achieved in reactors, such as trickle bed bioreactors, with high gas transfer performances. Moreover, the soluble metabolites, mainly acetate and butyrate, contained in the spent medium of the dark fermentation bioreactor were efficiently converted to methane in a second anaerobic digester (20 L continuously stirred tank) with a methane yield of about 170 L/kg COD initially fed in the first stage. These results demonstrate that a two-step anaerobic digestion process may be carried out in two successive bioreactors, both with specific and optimized parameters, in order to generate separated biogas flows containing either H2 or CH4. In addition to the advantages related to both gaseous molecule properties, many technological improvements would be achieved by this way : better hydrolysis, higher process stability, etc. The general discussion highlights the central and relevant position of the 2-stage anaerobic digestion process in the panorama of technologies able to both treat raw or residual organic matter and to produce energy or energy vectors for stationary or mobile end-use. The technical, economical and environmental aspects have been considered. [less ▲]

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See detailRobustness analysis of clustering and classification techniques
Ruwet, Christel ULg

Doctoral thesis (2012)

As mentioned in the title, the framework of this doctoral dissertation encompasses two different subjects: robust statistics on the one hand and classification and clustering techniques on the other hand ... [more ▼]

As mentioned in the title, the framework of this doctoral dissertation encompasses two different subjects: robust statistics on the one hand and classification and clustering techniques on the other hand. Robust procedures try at the same time to emulate classical procedures and to produce results that are not unduly affected by contaminated observations or deviations from model assumptions. Classification and clustering techniques try to find groups among observations. Grouping is one of the most basic abilities of living creatures; the simple fact of naming objects is already grouping. The main interest lies in the fact that the characteristics of a group as well as its differences from other groups can be used as a summary of the dataset. [less ▲]

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See detailLectures, réécritures et peintures à partir de Pline l’Ancien. La réception de l’Histoire naturelle en Italie, de Pétrarque à Vasari
Bert, Mathilde ULg

Doctoral thesis (2012)

This study examines the way in which the information given by Pliny the Elder in his Natural History concerning classical painting were perceived and exploited in Renaissance Italy, from Petrarch (c. 1350 ... [more ▼]

This study examines the way in which the information given by Pliny the Elder in his Natural History concerning classical painting were perceived and exploited in Renaissance Italy, from Petrarch (c. 1350) until the second edition of Vasari’s Lives (1568). It shows that references to Pliny that are discernible in various texts and works of art are means for us to understand some of the artistic, theoretical, and social issues inherent in pictorial practice at the time. Many different types of sources have been exploited in carrying out this research. In the first instance, information concerning the editorial transmission of the Natural History has been examined. Reception of Book XXXV, dedicated to classical painting, has been given special attention, particularly through the analysis of Renaissance copies of Pliny’s so-called Encyclopaedia, and the annotations, translations, derivations and commentaries to which this work gave rise at the time. Recourse to Pliny in artistic literature and in pictorial practice is then examined. Finally, the emulation of Apelles in artistic practise is considered through a study of the signature in the imperfect. This is, in fact, a way of signing paintings that Pliny attributes to the Greek painter and which artists in the Renaissance would adopt from the end of the fifteenth century. In addition to the substantial consideration given to Petrarch, Alberti, Ghiberti, Castiglione, Pino, Dolce and Vasari, this study also analyses references to Pliny in many other artists and humanists, such as Boccaccio, Guglielmo da Pastrengo, Villani, Guarino, Leonardo Giustiniani, Decembrio, Fazio, Landino, Perotti, Santi, Leonardo, Jacopo de’ Barbari, Bellini, Costa, Macrino d’Alba, Palmezzano, Raphael, Titian, Sebastiano del Piombo, Andrea del Sarto, Giovio, Damiano Zambelli, Aretino, Varchi, Giovio, l’Anonimo Magliabechiano and Giovanni Battista Adriani. Thus, via a series of individual and comparative readings that draw out the many links between art and humanism, this study highlights the various different forms that borrowings from Pliny could take, and the functions they had, as well as emphasising the main themes for which those borrowings were exploited, such as commentary on the cultural and social development of painting, and reflection on genres and pictorial styles (portrait, landscape, female nude, the debate about disegno and colorito, and the paragone of the arts). [less ▲]

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See detailLe corps du détenu : Études psychopathologiques de l’homme en situation
Englebert, Jérôme ULg

Doctoral thesis (2012)

Cette thèse de doctorat a pour premier objet d’étude la psychopathologie. Et nous estimons qu’une telle entreprise ne peut se concevoir qu’en situation (voici son second objet). Une prise en considération ... [more ▼]

Cette thèse de doctorat a pour premier objet d’étude la psychopathologie. Et nous estimons qu’une telle entreprise ne peut se concevoir qu’en situation (voici son second objet). Une prise en considération rigoureuse des « phénomènes psychiques anormaux » (Jaspers, 1913) implique une conception de l’homme en tant qu’être incarné, inscrit dans un espace et un temps, au risque, sinon, de se limiter à une simple nosographie ou à une clinique sans dimension pratique. Notre propos ne se limite pas à penser que l’environnement du sujet influence son trouble – cet élément est déjà, nous semble-t-il, bien acquis – ; nous estimons plutôt, d’un certain point de vue, que « La » psychopathologie, hypothétique science transcendantale, n’existe tout simplement pas. Le phénomène psychopathologique, par nature multiple et polymorphe, nécessite une réflexion épistémique approfondie et réclame l’émergence d’autres alternatives au paradigme empiriste afin de rompre « avec l'idolâtrie du sujet épistémologique anonyme sans situation » (Ricœur, 1957, p. 10). Faire nôtre cette proposition d’études psychopathologiques de l’homme en situation nous permet de pouvoir écrire cette thèse et de l’inscrire dans une généalogie relative. Le « gage de sûreté » que représente le paradigme situationnel nous permet de ne pas nous « perdre » en tentant de répondre à ces questions de façon générale. Il s’agirait d’ailleurs d’une entreprise impossible que de définir la subjectivité, de lui donner une acception commune. Par contre, appréhender la subjectivité incarnée d’un sujet et la considérer comme objet d’étude à part entière, semblent constituer des objectifs dotés d’un intérêt majeur. La situation permet de « mettre au travail » la psychopathologie, véritable moment où elle prend forme et existe réellement. Le situationnel et l’événementiel sont également la possibilité qui s’offre à nous de ne pas répéter des choses que d’autres auraient mieux dites ; ce sont les garanties de l’intérêt à poursuivre la recherche en psychopathologie. Théoriser à la suite de ces nombreuses références n’aurait de sens s’il n’y avait ce prétexte de la situation, tant un sentiment de « déjà dit » pourrait anesthésier et rendre vaine toute tentative. Notre situation, c’est notre alibi. Pour réaliser ce projet, nous avons séparé notre étude en deux livres. Le premier est consacré à différentes situations cliniques en milieu carcéral. Il contient huit chapitres. Tous sont la mise en application autant que la création d’une méthode, que nous qualifions de phénoménologique, appropriée à l’analyse de situations rencontrées dans notre pratique de psychologue clinicien en milieu carcéral. Le second livre est fait de deux chapitres construits chacun en trois parties. Cette seconde partie consiste en une formalisation anthropologique de ce qu’est un homme en prison. Nous avons étudié, entre autres, les dimensions de l’espace, du temps, du corps, de l’imaginaire pour parvenir à un essai de définition de ce que nous appelons l’univers carcéral et discuter du statut de l’identité carcérale. Ces différents points de repère nous ont permis d’aborder la question de la subjectivité et de la sensation qui sont des contrées d’une complexité fondamentale que le psychologue se refuse souvent d’affronter dans le domaine de la recherche, mais auxquelles il est pourtant confronté quotidiennement dans sa pratique clinique. C’est avec l’esthétique, à travers les peintures de Bacon, les photographies de Nollet et Huis clos de Sartre que nous avons refermé cette thèse. Cet achèvement ouvre la réflexion vers la pratique clinique centrée sur le champ inépuisable, même en prison, de la liberté. Nous avons pu, à cet effet, constater le surgissement de la résistance, de l’agencement, et considérer le principe d’adaptation sous un jour nouveau. Enfin, nos dernières lignes ont permis l’émergence du concept oxymore de « liberté carcérale » qui caractérise l’homme en situation d’enfermement. [less ▲]

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See detailVariations on the Kalman filter for enhanced performance monitoring of gas turbine engines
Borguet, Sébastien ULg

Doctoral thesis (2012)

Since their advent in the 1940's, gas turbines have been used in a wide range of land, sea and air applications due to their high power density and reliability. In today's competitive market, gas turbine ... [more ▼]

Since their advent in the 1940's, gas turbines have been used in a wide range of land, sea and air applications due to their high power density and reliability. In today's competitive market, gas turbine operators need to optimise the dispatch availability (it i.e., minimise operational issues such as aborted take-offs or in-flight shutdowns) as well as the direct operating costs of their assets. Besides improvements in the design and manufacture processes, proactive maintenance practices, based on the actual condition of the turbine, enable the achievement of these objectives. Generating dependable information about the health condition of the gas turbine is a requisite for a successful implementation of condition-based maintenance. In this thesis, we focus on the assessment of the performance of the thermodynamic cycle, also known as Module Performance Analysis. The purpose of module performance analysis is to detect, isolate and quantify changes in engine module performance, described by so-called health parameters, on the basis of measurements collected along the gas-path of the engine. Generally, the health parameters are correcting factors on the efficiency and the flow capacity of the modules while the measurements are inter-component temperatures, pressures, shaft speeds and fuel flow. Module performance analysis can be cast as an estimation problem that is characterised by a number of difficulties such as non-linearity of the system and noise and bias in the measurements. Moreover the number of health parameters usually exceeds the number of gas-path measurements, making the estimation problem underdetermined. This thesis starts with a survey of the state-of-the-art in module performance analysis. We then propose enhancements to a monitoring tool for steady-state data developed by Dr. P. Dewallef during his thesis at the Turbomachinery Group. Specifically, the improvements concern the fault detection and isolation tasks, respectively handled by a hypothesis testing and a sparse estimator. As a complement, we define metrics for the selection and analysis of sensor--health parameter suites based on the Information Theory. In a second step, we investigate the feasibility and the benefit that could be expected from the processing of data collected during transient operation of a gas turbine. We also discuss the impact of modelling errors on the estimation procedure and propose a solution that makes the health assessment robust with respect to modelling errors. The theoretical developments are evaluated on the basis of simulated test-cases through a series of metrics that gauge the estimation accuracy and the performance of the fault detection and isolation modules. [less ▲]

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See detailApplication d’un modèle d’analyse de l’interaction ventriculo-artérielle à la défaillance hémodynamique
MORIMONT, Philippe ULg

Doctoral thesis (2012)

L’utilisation du modèle hémodynamique d’interaction ventriculo-artérielle au lit du malade, à la place des approches intuitives dépourvues de signification physiologique réelle, est un défi. La nécessité ... [more ▼]

L’utilisation du modèle hémodynamique d’interaction ventriculo-artérielle au lit du malade, à la place des approches intuitives dépourvues de signification physiologique réelle, est un défi. La nécessité de recourir à des mesures hautement invasives et à des variations de pré-charge reste une contrainte difficile chez des patients instables. Les recherches présentées dans cette thèse montrent que les indices nécessaires à l’application du modèle peuvent aussi être obtenus à partir de mesures ou de signaux utilisés usuellement en soins intensifs à condition de respecter des conditions précises. [less ▲]

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See detailContribution à la désinfection de l'eau par photosensibilisation avec des extraits de plantes
Sunda Makuba, Teddy ULg

Doctoral thesis (2012)

La problématique de l’accès à l’eau par les populations des pays en développement constitue toujours de nos jours un défi important à relever pour contribuer à un développement durable tout en ... [more ▼]

La problématique de l’accès à l’eau par les populations des pays en développement constitue toujours de nos jours un défi important à relever pour contribuer à un développement durable tout en garantissant des conditions sanitaires satisfaisantes. Malgré les Objectifs du Millénaire pour le Développement (OMD), de nombreux pays souffrent encore actuellement d’un manque d’accès à l’eau. En République Démocratique du Congo, seuls 26% de la population a accès à l’eau. Au-delà de la satisfaction des besoins humains assurés par la fourniture de la quantité d’eau nécessaire, il s’agit aussi de veiller à garantir sa bonne qualité, particulièrement la qualité microbiologique. Parmi les divers procédés de désinfection de l’eau au niveau familial, la présente contribution a pour objectif l’amélioration de la méthode de désinfection solaire par application du processus de photosensibilisation. En présence de lumière, un photosensibilisateur génère dans l’eau l’oxygène singulet très réactif conduisant à la destruction des microorganismes. Certaines plantes utilisées dans la pharmacopée traditionnelle pour soigner les infections microbiennes et parasitaires sont capables d’initier cette réaction de photosensibilisation. Dans un premier temps, parmi une dizaine de plantes analysées, nous avons mis en évidence l’activité photosensibilisante d’extraits non alcaloïdiques de Cassia alata, Cassia occidentalis, Carica papaya, Phyllanthus niruri et Coleus kilimandschari. L’inactivation des coliformes fécaux a été remarquée après trois heures d’ensoleillement, celle-ci se manifestant après une heure d’exposition lorsque le milieu est saturé en oxygène. Tout en étant libéré de la contrainte liée à la saturation du milieu en oxygène, l’étude des huiles essentielles extraites de plantes de la famille des Rutacées a montré une inhibition complète des coliformes fécaux présents dans l’eau après deux heures d’ensoleillement pour Citrus reticulata et Citrus limonum et une heure d’ensoleillement pour Citrus bergamia. L’examen de cette dernière huile en spectrométrie de masse a mis en évidence la présence de méthoxy-5 psoralène (MOP-5), responsable de l’activité photosensibilisatrice. Utilisé en solution dans l’eau, le MOP-5 a confirmé son rôle de photosensibilisateur et son efficacité désinfectante avec un abattement de 4 unités logarithmiques pour les Coliformes fécaux après une heure d’exposition et de 3 unités logarithmiques pour les Entérocoques fécaux après seulement 5 minutes d’exposition. La fixation du MOP-5 sur un support solide a permis de récupérer le photosensibilisateur après usage tout en conservant son pouvoir désinfectant supérieur à la forme libre. Le dispositif MOP-5/polystyrène a permis d’observer une inhibition complète des Coliformes fécaux après seulement 6 minutes d’exposition et deux minutes pour les Entérocoques fécaux. Cette recherche constitue un premier travail exploratoire qui ouvre la voie vers un nouveau processus de désinfection de l’eau par photosensibilisation à partir d’extraits de plantes. Mais il conviendra de préciser les modalités pratiques d’application afin de rendre ce processus opérationnel. [less ▲]

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See detailLearning for exploration/exploitation in reinforcement learning
Castronovo, Michaël ULg

Master's dissertation (2012)

We consider the problem of learning high-performance Exploration/Exploitation (E/E) strategies for finite Markov Decision Processes (MDPs) when the MDP to be controlled is supposed to be drawn from a ... [more ▼]

We consider the problem of learning high-performance Exploration/Exploitation (E/E) strategies for finite Markov Decision Processes (MDPs) when the MDP to be controlled is supposed to be drawn from a known probability distribution pM(·). The performance criterion is the sum of discounted rewards collected by the E/E strategy over an infinite length trajectory. We propose an approach for solving this problem that works by considering a rich set of candidate E/E strategies and by looking for the one that gives the best average performances on MDPs drawn according to pM(·). As candidate E/E strategies, we consider index-based strategies parametrized by small formulas combining variables that include the estimated reward function, the number of times each transition has occurred and the optimal value functions ˆ V and ˆQ of the estimated MDP (obtained through value iteration). The search for the best formula is formalized as a multi-armed bandit problem, each arm being associated with a formula. We experimentally compare the performances of the approach with R-max as well as with -Greedy strategies and the results are promising. [less ▲]

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See detailEnregistrements des changements environnementaux dans les sédiments lacustres de Patagonie au cours des derniers millénaires
Sacré, Vincent ULg

Master's dissertation (2012)

This study focuses on a multiproxy analysis of sedimentary records from Lago Bertrand (area 50 km2 ; 227 masl ; 46°55’S 72°50’W) and Lago Thompson (area 1 km2 ; 751 masl ; 45°38’S 72°47’W). Three cores ... [more ▼]

This study focuses on a multiproxy analysis of sedimentary records from Lago Bertrand (area 50 km2 ; 227 masl ; 46°55’S 72°50’W) and Lago Thompson (area 1 km2 ; 751 masl ; 45°38’S 72°47’W). Three cores were retrieved during fieldtrips between 2008 and 2011 with an Uwitec gravity corer. For Lago Bertrand, one core was collected in the main lake (LBt09, 102 cm) and another in a lateral extension (LBb11-A, 162 cm). For Lago Thompson, one core was retrieved (LT08-E, 130 cm). Data 210Pb and 137Cs give average sedimentation rates of 1–2 mm/yr for the upper core section from the main part of Lago Bertrand, allowing a decennial resolution. Respectively two and five 14C dates has been obtained for LBt09 and LT08-E. Our aim is to document the climatic variability during the last millennia in Northern Patagonia and its impact on the environment. Lago Bertrand is separated from a pro-glacial lake (Lago Plomo) by a morainic barrier. The sediments of this lake are mainly composed of clayey silts and very few sandy silts. In the cores from the Eastern branch of Lago Bertrand, X-ray radiographies, magnetic susceptibility, Loss On Ignition (LOI) 550℃ and C/N (carbon/nitrogen) ratio profiles evidence well-defined pluri-millimetric laminations with terrestrial organic-rich layers, especially in the central core section. Diatom content is dominated by benthic genera, it does not show major changes except a recent eutrophication of this part of the lake. In the main lake, X-ray radiographies show diffuse pluri-millimetric laminations. The sediments of the main lake appear more homogeneous with less organic-rich layers. They are characterized by low C/N ratio (10), supporting an important aquatic productivity. Inorganic content remains high on the whole core ( 90–95% of the bulk sediment) and biogenic silica profile exhibits two major peaks. We found a same diversity in diatoms than in the lake extension. According to the age model, the changes in aquatic productivity occurred between 1200 BC and 1000 AD. Lago Thompson is characterized by a smaller watershed and less steep sides. Its sediment content is dominated by clayey silts and amorphous particles (essentially diatoms). X-ray radiographies, magnetic susceptibility and LOI 550℃ profiles evidence two tephra deposits at 1410–1440 and 1780–1790 AD. C/N ratio and biogenic silica profiles suggest a bigger productivity during a period equivalent to the Little Ice Age. Diatom assemblage is dominated by planctonic genera (Aulacoseira and Cyclotella) and is less diversified in benthic genera than for Lago Bertrand. Diatoms show specific response to tephra deposits. Planctonic/benthic ratio allow us to identify periods of high and low lake-level matching with moist and dry phases of Little Ice Age (1200–1650 and 1650–1850 AD). Further sedimentological analyses would be undertaken to better characterize the sediment deposition models (sediment core impregnation). In addition, datation of the Lago Bertrand extension core (LBb11-A) would allow us to identify environmental changes found in this study. [less ▲]

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See detailFaisabilité économique et environnementale d'un bus au biogaz à Liège
Mostert, Martine ULg

Master's dissertation (2012)

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See detail« La Famille de Centaures » de Zeuxis. À propos d’un chef-d’oeuvre antique décrit par Lucien de Samosate
Vanesse, Sylvain ULg

Master's dissertation (2012)

Le but de ce travail était de s'interroger sur l'authenticité du tableau attribué à Zeuxis d'Héraclée, peintre du 5e-4e siècles av. J.-C., décrit par le rhéteur syrien Lucien de Samosate. Il s'agissait d ... [more ▼]

Le but de ce travail était de s'interroger sur l'authenticité du tableau attribué à Zeuxis d'Héraclée, peintre du 5e-4e siècles av. J.-C., décrit par le rhéteur syrien Lucien de Samosate. Il s'agissait d'étudier le texte du rhéteur de manière philologique et d'étudier de manière iconographique les différents thèmes présents dans le tableau. [less ▲]

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See detailImitative learning for designing intelligent agents for video games
Gemine, Quentin ULg

Master's dissertation (2012)

Over the past decades, video games have become increasingly popular and complex. Virtual worlds have gone a long way since the first arcades and so have the artificial intelligence (AI) techniques used to ... [more ▼]

Over the past decades, video games have become increasingly popular and complex. Virtual worlds have gone a long way since the first arcades and so have the artificial intelligence (AI) techniques used to control agents in these growing environments. Tasks such as world exploration, constrained pathfinding or team tactics and coordination just to name a few are now default requirements for contemporary video games. However, despite its recent advances, video game AI still lacks the ability to learn. In this work, we attempt to break the barrier between video game AI and machine learning and propose a generic method allowing real-time strategy (RTS) agents to learn production strategies from a set of recorded games using supervised learning. We test this imitative learning approach on the popular RTS title StarCraft II and successfully teach a Terran agent facing a Protoss opponent new production strategies. [less ▲]

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See detailContribution to experimental tests on the seismic behaviour of masonry structural elements
Mordant, Christophe ULg

Master's dissertation (2012)

The objective of this master’s thesis is to contribute to two main aspects of experimental tests on the behaviour of load-bearing masonry subjected to earthquake action carried out within the European ... [more ▼]

The objective of this master’s thesis is to contribute to two main aspects of experimental tests on the behaviour of load-bearing masonry subjected to earthquake action carried out within the European research project SERIES. The first part explains the general context and presents the exploitation of results of the first phase of SERIES project TA5. This first phase investigates the response of four simple unreinforced clay masonry walls, two of them including acoustic insulation devices (SonicStrip). This phase has a double objective. On one hand, the tests aim at a better understanding of the seismic behaviour of single wall in dynamic conditions. On the other hand, the comparison between walls having a same global geometry, but with and without acoustic insulation devices allows the assessment of the consequences of the presence of that type of device on the seismic behaviour. The second part describes the design of specimens and the preliminary assessment of the structural behaviour of the second phase of the SERIES project TA5. The design is focusing on the investigation of the behaviour of T- and L-shaped walls, and in particular on the role of the parts of the structural elements perpendicular to the earthquake direction, and on the characterization of the frame behaviour in such masonry structures. The structural assessment is carried out according to Eurocodes 6 and 8 and considers different loading situations that can be found in daily practice. Some preliminary information on the experimental results of the second phase of the SERIES project TA5 are finally given." [less ▲]

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See detailPerceptions culturelles dans un contexte de néoplasme pédiatrique: Considérations transculturelles entre l'Occident et le Japon
Vander Haegen, Marie ULg

Master's dissertation (2012)

This research has for objective the investigation of the process of enculturation at a sick child affected by a neoplastic disease. To this end, this report analyzes at first, the culture through an ... [more ▼]

This research has for objective the investigation of the process of enculturation at a sick child affected by a neoplastic disease. To this end, this report analyzes at first, the culture through an ethnographical reading of its definition, its paradoxes and its anthropological axioms. This first part urges us to widen our considerations, and to study the various vectors by which the culture passes in transit but also specific cultural items. In the second part, we review medical clinical notions of neoplasm at the child. A rigorous analysis of main oncologic typologies, their treatments and side effects are presented. The third part brings the reader through a general medical anthropology which offers an understanding of the disease as a cultural experience. For purpose of illustrations, a concise cross-cultural reflection between Japan and the West is carried out. For these both populations, the epidemiological situation of childhood cancer is proposed at first to underline then cultural elements of difference and convergence. A reflection on clinical implications with which health practitioners could be confronted comes to conclude. [less ▲]

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See detailÉtude de la structure et des propriétés de gels à base d’oxyde de titane en relation avec leurs mécanismes de formation
Bodson, Céline ULg

Doctoral thesis (2012)

Dans le contexte général du développement, au Laboratoire de Génie Chimique, de nouveaux photocatalyseurs à base de TiO2 présentant une activité sous lumière UV-Vis améliorée, l’objectif de ce travail ... [more ▼]

Dans le contexte général du développement, au Laboratoire de Génie Chimique, de nouveaux photocatalyseurs à base de TiO2 présentant une activité sous lumière UV-Vis améliorée, l’objectif de ce travail consiste à étudier les mécanismes de formation mis en jeu lors de leur synthèse et de leur dopage par la méthode sol-gel de cogélification. Plusieurs dopants, contenant du silicium, du phosphore ou de l’argent, ont été utilisés. L’influence des variables opératoires de synthèse sur les propriétés physicochimiques, et de là sur les propriétés photocatalytiques des xérogels obtenus, a été examinée en détail. La compréhension de cette relation a permis d’ouvrir la voie à la synthèse de photocatalyseurs à base de TiO2 combinant différents dopages et présentant des activités élevées. Le développement de nouveaux dopants à base de porphyrines fonctionnalisées par des groupements phosphonatés a également été réalisé en vue de leur incorporation ultérieure dans les gels de TiO2. L’obtention d’un gel ou d’un précipité dépend des cinétiques des réactions d’hydrolyse et de condensation du tétraisopropoxyde de titane (TIPT). Le recours à un solvant chélatant a permis de ralentir la cinétique des ces réactions et donc d’obtenir un gel. Ces xérogels sont cependant non poreux après séchage. L’insertion, lors d’une synthèse par cogélification, d’un additif silylé ou phosphonaté contenant une éthylènediamine ralenti également la cinétique des réactions via un mécanisme de complexation du TIPT. Dans ce cas, il est possible d’obtenir un gel poreux dans un solvant non chélatant, et non un précipité. Ce résultat est très intéressant car il a été prouvé que lors du dopage du TiO2 avec du phosphore par cogélification, la formation du gel est importante car elle s’accompagne d’un degré élevé d’hétérocondensation (liaisons P-O-Ti), contrairement à la formation des précipités. Afin d’éliminer les résidus organiques encore présents à l’issue du séchage et de cristalliser le TiO2 en anatase, les échantillons doivent être calcinés. L’influence de la température de calcination sur les propriétés des photocatalyseurs a été examinée en détail. Dans les échantillons calcinés, des propriétés telles que la taille des cristallites d’anatase, la surface spécifique et le spectre d’absorption UV-Vis sont principalement influencés par la teneur en phosphore. Pour maîtriser cette dernière, il est important de maximiser le degré d’hétérocondensation entre le TIPT et l’additif phosphonaté (EDAP). En effet, lors de la calcination, l’EDAP non intégré au réseau de TiO2 via des liaisons Ti-O-P, se décompose en dessous de 350 °C et du phosphore est perdu par sublimation de P2O5. Parmi les dopages étudiés, seul celui au P permet de déplacer le spectre d’absorption du TiO2 vers les plus grandes longueurs d’onde. Lors du test de dégradation du p-nitrophénol sous lampe halogène, les xérogels de TiO2 dopé au P calcinés donnent de meilleurs résultats que le xérogel de TiO2 pur ou encore que ceux dopés à l’Ag uniquement. L’influence intrinsèque du phosphore sur l’activité photocatalytique a été confirmée par une étude statistique. Cette étude montre également que l’activité dépend de la teneur en phosphore via son influence sur la taille des cristallites d’anatase et sur la surface spécifique des xérogels. Cette activité est d’autant plus élevée que la taille des cristallites est petite et que la surface spécifique est élevée. Afin de maximiser les performances photocatalytiques du TiO2 sous lampe halogène, un co-dopage à l’Ag et au P a été réalisé pour essayer de combiner l’effet bénéfique du P sur l’activité sous lumière visible et celui de l’Ag sur la vitesse de recombinaison des paires électron-trou. L’utilisation d’une molécule comme l’EDAP, capable de complexer l’ion Ag+, permet d’obtenir dans le matériau final des nanoparticules d’Ag finement dispersées dans les particules de TiO2. Le co-dopage à l’Ag et au P permet d’augmenter de manière très significative l’activité des xérogels de TiO2 pour la dégradation du p-nitrophénol sous lampe halogène. Cette augmentation résulte d’un effet synergique entre les deux additifs. Le dernier chapitre de ce travail est une étude préliminaire pour ouvrir la voie au dopage du TiO2 avec des porphyrines fonctionnalisées par des groupements phosphonatés ou silylés via la méthode de cogélification. Cette étude a permis de mettre au point des protocoles de synthèse de porphyrines phosphonatées et de porphyrines aminées. Ces porphyrines aminées serviront de précurseurs pour l’obtention de porphyrines silylées. [less ▲]

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See detailSois belle et tais-toi: la bienveillance sexiste comme outil de discrimination
Sarlet, Marie ULg

Doctoral thesis (2012)

Doit-on encore, en 2012, s'inquiéter des préjugés et de la discrimination basés sur le genre? Si oui, ceux-ci doivent-ils nécessairement revêtir une forme hostile pour engendrer des conséquences négatives ... [more ▼]

Doit-on encore, en 2012, s'inquiéter des préjugés et de la discrimination basés sur le genre? Si oui, ceux-ci doivent-ils nécessairement revêtir une forme hostile pour engendrer des conséquences négatives pour les femmes qui en sont les cibles? Dans cette thèse, nous allons nous intéresser à ces préjugés et, plus particulièrement, à une forme particulière de sexisme, le sexisme bienveillant, qui renvoie à des attitudes sexistes subjectivement positives, teintées de galanterie et de condescendance (Glick & Fiske, 1996). Au travers des différents chapitres, nous allons nous demander si cette forme de sexisme, bien qu’elle puisse sembler anodine, peut être considérée comme un outil susceptible de contribuer au maintien des inégalités entre les genres. Le Chapitre 1 nous permettra de justifier l’importance qu’il y a encore de nos jours d’accéder à une meilleure compréhension du sexisme. Un aperçu de la situation respective des femmes et des hommes en Belgique soulignera la persistance, au sein des différentes sphères de vie, des inégalités entre les genres, se marquant très souvent en défaveur des femmes. La contribution du sexisme dans l’explication de ces inégalités sera illustrée par différentes études empiriques. De façon plus générale, nous nous intéresserons au processus de stigmatisation et à ses conséquences pour les personnes qui en sont les cibles. Dans le Chapitre 2, nous nous focaliserons sur la théorie du Sexisme Ambivalent (Glick & Fiske, 1996) qui suggère que le sexisme est bidimensionnel, comprenant une composante de bienveillance, le sexisme bienveillant, et une composante d’hostilité, le sexisme hostile. Ce chapitre dressera les définitions conceptuelle et opérationnelle de ces deux formes de sexisme ainsi que leurs origines. Ensuite, une revue de la littérature soutiendra la définition du sexisme bienveillant en tant que préjugé malgré une apparence qui peut sembler anodine, voire avantageuse pour les femmes. Nous définirons le sexisme bienveillant en tant qu’idéologie traditionnelle décrivant les femmes comme sociables et incompétentes (Fiske, Cuddy, Glick, & Xu, 2002), idée reflétée dans le titre de cette thèse : sois belle et tais-toi. Le sexisme bienveillant sera donc présenté comme un véritable processus de maintien des inégalités sociales entre les genres se basant sur un paradoxe : il semble valoriser les femmes, mais les défavorise pourtant dans leur position sociale. Dans les chapitres suivants, nous investiguerons deux grandes questions. Premièrement, nous étudierons les mécanismes par lesquels le sexisme bienveillant est susceptible de contribuer au maintien de la subordination des femmes dans le milieu professionnel (Chapitres 3 à 6). Dans un second temps, nous nous demanderons par quels processus le sexisme bienveillant est maintenu au sein des relations entre les genres (Chapitre 7). Pour répondre à notre première question, nous testerons l’hypothèse selon laquelle le sexisme bienveillant, en milieu professionnel, induirait chez les femmes une internalisation mais aussi une confirmation comportementale des croyances stéréotypiques les décrivant comme sociables et incompétentes. Le Chapitre 3 s’intéressera à l’impact du sexisme bienveillant sur la dimension stéréotypique de sociabilité. Dans un premier temps, nous observerons, au travers d’une tâche de mémoire autobiographique, l’impact de l’activation du sexisme bienveillant sur le concept de soi des femmes en termes de traits positifs liés à la sociabilité (Etude 1). Ensuite, nous testerons l'idée que l’adhésion personnelle des femmes au sexisme bienveillant les conduirait à privilégier des stratégies de promotion de soi mettant en évidence des traits positifs liés à la dimension de sociabilité et nous en observerons les conséquences sur leur orientation professionnelle (Etude 2). Dans le Chapitre 4, nous considérerons l’impact du sexisme bienveillant sur la dimension stéréotypique de compétence. Nous verrons si l’exposition au sexisme bienveillant en milieu professionnel déplace le concept de soi des femmes vers l’incompétence, ce que nous opérationnaliserons par une mesure de pensées intrusives et par une tâche de mémoire autobiographique. Nous nous intéresserons, par ailleurs, à l’impact du sexisme bienveillant sur la suppression de pensées intrusives et sur les performances cognitives des femmes grâce au Reading Span Test (Daneman et Carpenter, 1980). Dans les Chapitres 5-6, nous utiliserons des mesures plus implicites pour évaluer les conséquences engendrées par l’exposition au sexisme bienveillant en milieu professionnel. Dans le Chapitre 5, nous utiliserons une tâche de Stroop (MacLeod, 1991) nous permettant d’étudier les fonctions exécutives des femmes soumises au sexisme bienveillant. Par ailleurs, l’utilisation d’une tâche de Stroop modifiée approfondira l’étude du contenu des pensées intrusives induites par l’exposition au sexisme bienveillant. Nous observerons notamment si le sexisme bienveillant active simultanément, dans l’esprit des femmes, des pensées intrusives liées à la sociabilité et à l’incompétence, regroupant ainsi les hypothèses de nos chapitres 3 et 4. Dans le Chapitre 6, nous utiliserons le dispositif de l’Imagerie par Résonance Magnétique fonctionnelle (IRMf) afin d’étudier les substrats neuronaux impliqués par l’exposition au sexisme bienveillant en milieu professionnel. Plus exactement, nous nous focaliserons sur les aires cérébrales associées au contrôle mental (i.e., cortex préfrontal dorsolateral et cortex cingulaire antérieur). Le Chapitre 7 nous permettra d’investiguer notre seconde question : comment le sexisme bienveillant est-il maintenu au sein des relations entre les genres ? Au travers de cinq études, nous envisagerons un mécanisme susceptible de participer à ce maintien: la prescription de comportements paternalistes faite aux hommes (ex. les hommes doivent se montrer protecteurs envers les femmes). Nous considérerons également la prescription de comportements égalitaristes faite aux hommes (Etudes 1 à 3). Au travers de ce chapitre, nous prendrons en compte une variable contextuelle qui est la sphère (romantique ou professionnelle) dans laquelle s’expriment les comportements des hommes (Etudes 1 à 5). Par ailleurs, nous nous intéresserons à la façon dont ces comportements sont interprétés en fonction du contexte considéré (Etude 4) et le rôle que joue le niveau personnel d’adhésion des femmes aux idéologies sexistes bienveillantes sur leur prescription (Etude 5). Le Chapitre 8 consistera en un chapitre de discussion générale et de conclusions. Nous y présenterons des données supplémentaires récoltées au cours de cette thèse, mettrons en évidence les forces et faiblesses de notre travail ainsi que certaines explications alternatives. Nous envisagerons également différentes pistes de recherche pour les explorations futures. [less ▲]

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See detailNumerical simulations of brittle and elasto-plastic fracture for thin structures subjected to dynamic loadings
Becker, Gauthier ULg

Doctoral thesis (2012)

The main purpose of this thesis is the development of a framework to model fracture initiation and propagation in thin bodies. This is achieved by the combination of two original models. On one hand ... [more ▼]

The main purpose of this thesis is the development of a framework to model fracture initiation and propagation in thin bodies. This is achieved by the combination of two original models. On one hand, (full) discontinuous Galerkin formulations of Euler-Bernoulli beams as well as Kirchhoff-Love shells are established. These formulations allow modeling a thin structure with discontinuous elements, the continuity being ensured weakly by addition of interface terms. The first advantage of the recourse to a discontinuous method is an easy insertion of cohesive elements during the simulation without a modification of the mesh topology. In fact with a continuous method, the insertion of the cohesive elements at the beginning of the simulation leads to numerical issues and their insertion at onset of fracture requires a complex implementation to duplicate the nodes. By contrast, as interface elements are naturally present in a discontinuous formulation their substitution at fracture initiation is straightforward. The second advantage of the discontinuous Galerkin formulation is a simple parallel implementation obtained in this work by exploiting, the discontinuity of the mesh in an original manner. Finally, last advantage of the recourse to a discontinuous Galerkin method for thin bodies is to obtain a one field formulation. In fact, the C1 continuity is ensured weakly by interface terms without considering rotational degrees of freedom. On the other hand, the through-the-thickness crack propagation is complicated by the implicit thickness model inherent to thin bodies formulations. Therefore we suggest an original cohesive model based on reduced tresses. Our model combines the different reduced stresses in such a way that the expected amount of energy is released during the crack process leading to a model which respects the energetic balance whatever the applied loadings. The efficiency of the obtained framework is demonstrated through the simulation of several benchmarks whose results are in agreement with numerical and experimental data coming from the literature. Furthermore, the versatility of our framework is shown by simulating 2 very different fracture phenomena: the crack propagation for elastic as well as for elasto-plastic behavior and the fragmentation of brittle materials. This demonstrates that our framework is a powerful tool to study dynamics crack phenomena in thin structure problems involving a large number of degrees of freedom. [less ▲]

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See detailModélisation des tensions circonférentielles en simulation méridienne d'écoulements en turbomachines
Thomas, Jean-Philippe ULg

Doctoral thesis (2012)

The systematic use of three-dimensional Navier-Stokes simulations being too demanding in turbomachinery design phase, throughflow simulation, two-dimensional, simpler and faster, is used extensively on an ... [more ▼]

The systematic use of three-dimensional Navier-Stokes simulations being too demanding in turbomachinery design phase, throughflow simulation, two-dimensional, simpler and faster, is used extensively on an industrial scale. However, its limitation is its need for empirical information to reproduce the action of the blades and the effect of three-dimensional components of the flow, higher-order elements compared to the classical throughflow. We propose to lead to a decrease of empiricism needed by the classical throughflow by obtaining this information autonomously. Obtaining information of a circumferential order may be considered in resolving all the components of the flow with a purely three-dimensional code or by accommodating an approximate solution with a reduced numerical cost, the way chosen in this contribution. To do this, we propose to extend to the circumferential case the He's "nonlinear harmonic method", of proved efficiency in the case of approximate reproduction of unsteadiness. Adapting this technique to the throughflow model passes through a reformulation of the presence of blades. Indeed, the use of Fourier series requires a continuous circumferential evolution of flow, prohibiting the existence of local impermeability condition. To work around this feature of the circumferential case, the effect of the blades is modeled by a force field sufficiently continuous and formalized by the Peskin's "immersed boundary method". The validation of the new technique, resulting from an innovative combination of the harmonic and immersed boundary methods inside a throughflow code, is performed on the case of inviscid flow around a cylinder. It illustrates the capabilities of the harmonic throughflow to access higher order information, that enrich the mean flow but also make available the circumferential view of the flow from the Fourier modes resolved. Finally, the harmonic throughflow is applied to a stator airfoil and a single-stage compressor. It is shown that after adjusting the model to the specific geometry of thin profiles, it is possible to access information of higher order. In particular, the model captures the potential characteristics of circumferential non-uniformities on the entire vein and the viscous characteristics near meridional walls. [less ▲]

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See detailEtude de la glycoprotéine L de l'herpèsvirus bovin 4 et de sa protection vis-à-vis des anticorps neutralisants
Lété, Céline ULg

Doctoral thesis (2012)

L’herpèsvirus bovin 4 (BoHV-4) appartient à la famille des Herpesviridae qui comprend un nombre important de pathogènes classés en trois sous-familles (alpha-, beta, et gamma-herpesvirinae) (Ackermann ... [more ▼]

L’herpèsvirus bovin 4 (BoHV-4) appartient à la famille des Herpesviridae qui comprend un nombre important de pathogènes classés en trois sous-familles (alpha-, beta, et gamma-herpesvirinae) (Ackermann, 2004). Parmi les gammaherpèsvirus, l’Epstein Barr virus (EBV) et l’herpèsvirus associé au sarcome de Kaposi (KSHV) sont responsables de pathologies humaines importantes. Etant donné que ces deux virus se multiplient mal in vitro et n’ont pas de modèle in vivo, le BoHV-4 représente un modèle plus accessible pour l’étude de ces pathogènes humains. Etant donné que les herpèsvirus sont réexcrétés après qu’une réponse immune spécifique se soit mise en place, ces virus ont dû développer un cycle d’infection élaboré leur permettant d’échapper à la neutralisation par les anticorps spécifiques de l’hôte. Comme les anticorps neutralisants agissent principalement en bloquant l’entrée des virions au sein des cellules cibles, il est nécessaire, afin d’améliorer le contrôle de ces infections, de connaître avec précision les mécanismes d’entrée de ces virus au sein des cellules cibles. Contrairement à la plupart des virus enveloppés qui n’utilisent qu’une seule protéine de fusion pour l’entrée, les herpèsvirus utilisent un complexe de fusion conservé composé des glycoprotéines gB, gH et gL (Connolly et al., 2011). La glycoprotéine gB, essentielle à l’infection chez les herpèsvirus, est une protéine de fusion de classe III(Roche et al., 2007). Cependant, gB seule ne peut opérer la fusion et requiert la présence des glycoprotéines gH et gL associées en hétérodimère. Ce complexe est une cible majeure de neutralisation chez plusieurs herpèsvirus (Gill et al., 2006) indiquant son implication dans l’entrée du virus. Plusieurs études rapportent que gH pourrait avoir un rôle effecteur dans la fusion et agir comme une glycoprotéine de fusion de classe I(Gianni et al., 2005). Cependant, la récente cristallisation du complexe gH/gL chez l’HSV-2 et l’EBV (Chowdary et al., 2010; Matsuura et al., 2010) suggère que celui-ci n’agit vraisemblablement pas comme co-fusogène mais intervient plutôt pour réguler la fusion de gB. Quant à la glycoprotéine gL, son rôle propre est controversé. Certains auteurs soutiennent que gL n’agit qu’en tant que protéine chaperon pour gH (Hutchinson et al., 1992), d’autres affirment qu’elle est également impliquée dans l’attachement (Gillet et al., 2008b). Considérée comme essentielle jusqu’à présent, une étude a récemment montré que la gL de l’herpèsvirus murin 4 (MuHV-4) est non essentielle pour l’infection (Gillet et al., 2007b). Afin de mieux comprendre les mécanismes d’entrée des gammaherpèsvirus au sein de leurs cellules cibles et dès lors pouvoir mieux combattre ces infections, ce travail a été consacré à l’étude de la glycoprotéine L du BoHV-4. Il s’articule en 3 volets. Le premier volet étudie l’implication de gL dans l’entrée virale. La seconde partie étudie gL en tant que cible potentielle de neutralisation. Enfin, dans le dernier volet de ce travail, nous nous sommes intéressés plus spécifiquement à la protection de la glycoprotéine L vis-à-vis des anticorps neutralisants.   1. La glycoprotéine L de l’herpèsvirus bovin 4 est non essentielle pour l’infectivité mais déclenche l’endocytose des virions pendant l’entrée. Afin d’étudier les conséquences fonctionnelles de l’absence de gL sur l’infection par le BoHV-4, nous avons généré un virus recombinant déficient pour la glycoprotéine gL. Les virions dépourvus de gL présentent une altération de la glycosylation de gH et une incorporation moindre de gH au sein des virions, bien que ceux-ci restent infectieux. L’absence de gL s’accompagne d’un important retard de croissance virale associé à un déficit d’entrée. Ce déficit d’entrée survient à une étape postérieure à l’attachement mais antérieure à la fusion. Enfin, grâce à la réalisation de marquages immunofluorescents de virions lors de l’entrée dans la cellule cible, nous avons pu montrer que ce déficit d’entrée associé à l’absence de gL est lié à un retard d’endocytose et à un défaut de migration vers les endosomes tardifs de la cellule. En conclusion, la glycoprotéine L du BoHV-4 est non essentielle mais intervient dans l’endocytose des virions attachés en surface cellulaire. 2. Etude de la glycoprotéine gL en tant que cible de la neutralisation. Au cours de la deuxième étude, nous avons voulu déterminer l’implication de gL dans le cycle naturel du virus et dans la neutralisation de celui-ci. Une expérience in vivo réalisée chez le lapin a mis en évidence que l’absence de gL n’avait pas d’impact significatif sur l’établissement et le maintien de la latence du BoHV-4. Nous avons également montré que l’absence de gL n’affectait pas quantitativement la réponse humorale à l’encontre du BoHV-4. Par contre, des expériences de neutralisation menées avec des séra provenant de lapins infectés avec la souche sauvage ou avec la souche n’exprimant plus la glycoprotéine L ont montré l’importance de la glycoprotéine L dans la ,neutralisation virale. En effet, l’absence d’anticorps dirigés contre la gL ou contre des épitopes dépendant de sa présence réduisait de manière importante le pouvoir neutralisant des séra. Nous avons donc pu conclure que la glycoprotéine L, ou des épitopes dépendants de sa présence, sont des cibles majeures de neutralisation. 3. Etude de la protection de la glycoprotéine L vis-à-vis des anticorps neutralisants. Parmi les mécanismes de résistance des virus à la neutralisation, plusieurs études ont mis en évidence l’utilisation de boucliers de glycans (« Glycan shield ») par différents virus(Lee et al., 2008a; Wei et al., 2003b). Nous nous sommes donc intéressés au rôle des glycans dans l’évasion par le BoHV-4 des anticorps neutralisants. Nous avons dans un premier temps montré que les glycans protègent de la neutralisation. Nous avons ensuite identifié, grâce à la réalisation du protéome structural du BoHV-4 en collaboration avec l’équipe du Professeur Wattiez, 4 protéines massivement glycosylées au sein du virion à savoir gB, gL, gH et gp 180. Nous nous sommes d’abord intéressés à gp 180, celle-ci étant la protéine potentiellement la plus glycosylée. Nous avons montré que gp 180 est massivement O-glycosylée et que les virus n’exprimant plus gp 180 sont plus neutralisés par le sérum que les virus sauvage et révertant. De plus, l’absence de gp180 augmente l’accessibilité des glycoprotéines gB, gH et gL à leur anticorps spécifiques. Gp180 et ses glycans semble donc jouer le rôle de « glycan shield » à la surface du BoHV-4. En parallèle, nous avons investigué le rôle de la glycosyltransférase encodée par le gène Bo17 du BoHV-4. Nous avons montré que la glycoprotéine gp 180 est une des cibles de cette glycosyltransférase. Etant donné que le gène Bo17 subit un phénomène d’épissage alternatif qui génère soit une protéine entière enzymatiquement active soit une protéine plus courte dont l’activité enzymatique est supprimée, nous avons généré et caractérisé des virus recombinants n’exprimant que la forme longue ou que la forme courte de Bo17. Grâce à ces virus, nous avons pu montrer que le BoHV-4, via le splicing alternatif du gène Bo17, est capable de moduler la glycosylation de gp180. Dans le futur, nous voulons étudier les conséquences de ces observations sur la neutralisation du BoHV-4. Ce travail devrait nous permettre de comprendre le rôle potentiel de Bo17 et de son épissage dans la biologie de l’infection par le BoHV-4. En conclusion, ce travail a permis de mettre en évidence la complexité du mécanisme d’entrée des gammaherpèsvirus nécessaire à la protection des épitopes vulnérables de la neutralisation par les anticorps. Ce travail a aussi démontré l’importance de la O-glycosylation dans ce processus. Les données générées ont illustré la complexité des interactions glycans-virus-cellules hôtes et ont constitué une première base pour des perspectives tant fondamentales qu’appliquées. [less ▲]

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See detail« Abandonner le contrôle sans perdre le contrôle ». Une investigation du rôle de la confiance des subordonnés envers leur manager comme levier potentiel du contrôle organisationnel
De Zanet, Fabrice ULg

Doctoral thesis (2012)

Toute organisation souhaite que ses salariés remplissent au mieux leurs missions. Les moyens mis en œuvre pour s’en assurer sont étudiés dans un champ disciplinaire appelé le contrôle organisationnel dont ... [more ▼]

Toute organisation souhaite que ses salariés remplissent au mieux leurs missions. Les moyens mis en œuvre pour s’en assurer sont étudiés dans un champ disciplinaire appelé le contrôle organisationnel dont la finalité est d’inciter les salariés à agir dans l’intérêt de leur organisation. Par ailleurs, parce que les organisations évoluent dans un contexte se caractérisant par davantage d’incertitude et d’interdépendance, elles ne peuvent plus se contenter d’attendre que leurs salariés se conforment à des procédures ou comportements précisément définis. Dès lors, elles confient à leurs managers la délicate mission de contrôler leurs subordonnés tout en les incitant à aller au-delà de ce qui est attendu d’eux et à contribuer activement aux objectifs de l’organisation. Ces managers sont alors confrontés à un dilemme : comment « abandonner le contrôle sans perdre le contrôle » ? Dans le cadre de cette thèse, nous abordons la question du contrôle organisationnel à travers le rôle clé des managers. Nous postulons que les managers capables de gagner la confiance de leurs subordonnés peuvent accomplir plus facilement leur mission de contrôle organisationnel. A travers trois études empiriques, nous examinons comment les managers contribuent au développement de la confiance et comment la confiance des subordonnés envers leur manager les incite à agir dans l’intérêt de leur organisation. L’originalité de notre travail est de se situer à la croisée de différentes disciplines, à savoir la théorie des organisations, le contrôle de gestion et le comportement organisationnel. [less ▲]

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See detailA Tool for Design Decision Making Zero Energy Residential Buildings in Hot Humid Climates
Attia, Shady ULg

Doctoral thesis (2012)

Informed decision-making is the basis for the design of Net Zero Energy Buildings (NZEBs). This thesis investigates the use of building performance simulation tools as a method of informing the design ... [more ▼]

Informed decision-making is the basis for the design of Net Zero Energy Buildings (NZEBs). This thesis investigates the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study was to develop a design decision making tool, ZEBO, for zero energy residential buildings in hot climates and to evaluate the effect of a simulation-based decision aid, on informed decision-making using sensitivity analysis. An assessment of the role of the BPS tools used in informing the decision-making was ascertained through cases studies, usability testing and several self-reported metrics. The thesis provides results that shed light on the effectiveness of sensitivity analysis as an approach for informing the design decisions of NZEBs. [less ▲]

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See detailExperimental Investigation of the Aerodynamics and Aeroelasticity of Flapping, Plunging and Pitching Wings
Norizham, Abdul Razak ULg

Doctoral thesis (2012)

This thesis concerns the experimental analysis of the aerodynamics and aeroelasticity of oscillating wings. It is divided into two sections, an inves- tigation of wings undergoing imposed root flapping ... [more ▼]

This thesis concerns the experimental analysis of the aerodynamics and aeroelasticity of oscillating wings. It is divided into two sections, an inves- tigation of wings undergoing imposed root flapping and pitching motion, such as seen in avian flight and an experimental investigation of the self- excited stall flutter oscillations of a wing undergoing plunging and pitching motion. The objective of the flapping wing investigation is to improve the under- standing of the unsteady aerodynamics of flapping flight. The work con- sists of designing and building a flapping and pitching bird-like mechanical model and testing it in a low speed wind tunnel. The model’s size is sim- ilar to that of a goose. The wind tunnel tests involved the measurement of forces, power, kinematics and local flow velocities using Particle Im- age Velocimetry (PIV). The mechanical model was tested at four different frequencies and three airspeeds. In addition, three different wing profiles were tested. The kinematic modes included pure flapping and combined flapping and pitching. It was shown that pure flapping and pitch-lagging combined motion can lead to interesting aerodynamic phenomena, such as flow separation and dynamic stall. Dynamic stall can cause significant increases in instantaneous lift production, although it also generates a lot of drag. On the contrary, pitch leading combined motion can generate a net propulsive force over the entire cycle. In the stall flutter study, a 6 degree of freedom NACA 0018 wing was sus- pended by springs in the wind tunnel. The wing was then exposed to an airflow at a number of airspeeds and wind-off angles of attack. The wing was instrumented with pressure sensors and accelerometers. In addition, PIV flow measurements were carried out on the wing’s upper surface. The work demonstrates that stall flutter is the result of a combination of dy- namic stall with the elastic properties of the system. The dynamic stall mechanism was studied using the PIV measurements and was found to be different to the classical stall mechanisms that are reported in the litera- ture. The sensitivity of the stall flutter phenomenon to parameters such as airspeed and wind-off angle of attack is demonstrated by means of a two-parameter bifurcation diagram. [less ▲]

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See detailCorpus et catégorisation. Perspective linguistique sur les genres en néo-égyptien
Gohy, Stéphanie ULg

Doctoral thesis (2012)

Le corpus néo-égyptien a suscité - et suscite encore – un large intérêt, sans toutefois attacher suffisamment d’attention à la définition du corpus. Dans bon nombre d’études, l’appellation « néo-égyptien ... [more ▼]

Le corpus néo-égyptien a suscité - et suscite encore – un large intérêt, sans toutefois attacher suffisamment d’attention à la définition du corpus. Dans bon nombre d’études, l’appellation « néo-égyptien » a longtemps été réservée aux textes de la pratique censés refléter au mieux la langue parlée. À vrai dire, si l’étude du néo-égyptien a suscité un certain engouement dans le milieu égyptologique, deux perspectives ont généralement été envisagées :  une vision englobante : l’étude du néo-égyptien se fait à partir d’un corpus étendu, sans aucune restriction particulière et sans prêter attention aux genres des textes, à la diachronie ou à l’état de langue employé ;  une vision restrictive : l’étude du néo-égyptien s’appuie sur un corpus réduit, en tenant compte de critères préalablement définis comme la diachronie, le lieu géographique ou le genre (littéraire >< non littéraire). Quelques études ont également été consacrées à un genre de texte particulier. Une étude manquait donc encore ; aucun travail de recherche n’avait envisagé l’étude du corpus néo-égyptien selon une perspective diachronique large, sans restriction entre textes littéraires et non littéraires, et en tenant compte des genres. Dans ma thèse, j’ai donc proposé de définir le corpus néo-égyptien comme suit : il s’agit d’un ensemble de textes s’inscrivant dans différents genres dans lesquels s’actualisent différents registres d’expression. Dès lors, la définition du corpus néo-égyptien passait nécessairement par la définition des genres et des registres d’expression employés au sein de ce corpus. On le sait, chaque texte s’inscrit dans un genre qui va imposer des règles/normes codifiant ce genre. Ce sont ces normes, ces règles qu’il s’agissait de mettre en avant. Je me suis donc attelée à définir ces genres, c’est-à-dire mettre en évidence les critères qui les définissent, spécifier les fonctionnements propres aux différents genres afin d’établir leur « carte d’identité ». C’est la base de données Ramsès qui a servi de corpus de référence à mon étude. À chacun des textes a été attribué un genre a priori. Il est vite apparu que dans l’examen des normes imposées par le genre, de nombreux critères pouvaient être mobilisés, toutefois, j’ai décidé de concentrer mes recherches sur quatre critères de définition : la phraséologie, la diplomatique (particulièrement, les formules d’incipit et d’explicit), le répertoire, l’emploi de l’encre rouge. L’examen de ces 4 critères a donc permis de mettre en évidence quelques-unes des normes codifiant les différents genres et, par la même occasion, d’assurer la pertinence de la classification proposée. [less ▲]

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See detailPrévisions des rendements du blé d’hiver à échelle régionale par modélisation de la courbe de chute de l’indice foliaire
Kouadio, Amani Louis ULg

Doctoral thesis (2012)

Estimation of cereal-crop production is considered as a priority in most crop research programs due to the relevance of food grain to world agricultural production. A large number of agrometeorological ... [more ▼]

Estimation of cereal-crop production is considered as a priority in most crop research programs due to the relevance of food grain to world agricultural production. A large number of agrometeorological models for crop yield assessment are available with various levels of complexity and empiricism. The current development of models for wheat yield forecasts, however, does not always reflect the inclusion of the loss of valuable green area and its relation to biotic and abiotic processes in production situation. At the field level, the close correlation between green leaf area during maturation and grain yield in wheat revealed that the onset and rate of senescence appeared to be important factors for determining wheat grain yield. Earth observation data, owing to their synoptic, timely and repetitive coverage, have been recognized as a valuable tool for crop monitoring at different levels. Our study sought to explore an approach for winter wheat (Triticum aestivum L.) yield forecasts at a regional scale, based on metrics derived from the senescence phase of the green area index (GAI). The senescence phase of winter wheat was analyzed and its modelling was achieved through two curve-fitting functions (modified Gompertz and logistic function). Metrics derived from these functions and characterizing this phase (i.e. the maximum value of GAI, the senescence rate and the time taken to reach either 37% or 50% of the remaining green surface in the senescent phase) were related to grain yields. The Senescence-based Approach For Yield estimates (SenAFY) was established and first tested at plot scale based on GAI values derived from digital hemispherical photograph. Then, it was applied at a regional scale using GAI temporal profiles retrieved from MODIS data. This second part of our study took advantage of recent methodological improvements in which imagery with high revisit frequency but coarse spatial resolution can be exploited to derive crop-specific GAI time series by selecting pixels whose ground-projected instantaneous field of view is dominated by the winter wheat. The regression-based models derived from the SenAFY provide interesting yield estimates at these two spatial scales. At regional scale, especially, the use of the SenAFY in order to forecast wheat yield gave satisfactory results. Such an approach may be considered as a first yield estimate that could be performed in order to provide better integrated yield assessments in operational systems. [less ▲]

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See detailConception et réalisation d'un photobioréacteur adapté à l'étude de la production d'hydrogène chez les micro-algues. Application à l'étude de l'influence d'une NAD(P)H déshydrogénase-plastoquinone-réductase chloroplastique de type II sur le potentiel de photoproduction d'hydrogène chez Chlamydomonas reinhardtii.
Mignolet, Emmanuel ULg

Doctoral thesis (2012)

Conception and building of a photobioreactor adapted to the study of the production of hydrogen in microalgae. Application to the study of the influence of a Type II NAD(P)H dehydrogenase plastoquinone ... [more ▼]

Conception and building of a photobioreactor adapted to the study of the production of hydrogen in microalgae. Application to the study of the influence of a Type II NAD(P)H dehydrogenase plastoquinone reduction chloroplast on the potential of hydrogen photo-production in Chlamydomonas reinhardtii. Context and abstract of the thesis This project is part of a research framework to better understand the process of hydrogen photobioproduction in microalgae. Overall, we can say that hydrogen photobioproduction depends on the set of biochemical reactions that define cellular energy metabolism. In Chlamydomonas, H2 photobioproduction is ensured by two enzymes (Hyda1 and Hyda2). These two enzymes are located in the chloroplast stroma, they catalyze the reaction of hydrogen production (Fig. 1). The electrons required for the synthesis of H2 come from two different metabolic pathways, situated upstream of the PSI and CytB6f. The transport of electrons between these two paths and the CyB6f is via the plastoquinones (PQ) pool. The first pathway for the reduction of PQ involves the photolysis of water via photosystem II, known as the PSII-dependent pathway. The second reduction pathway is thought to involve an enzyme catalyzing the oxidation of NAD(P)H, and the reduction of PQ. Thought to be located on the stroma side of the membrane, it is known as the PSII-independent pathway. Succinctly, the PSII-dependent pathway could be considered as a contribution to the reductant supply from light energy and the PSII-independent pathway as a contribution to the reductant supply from starch, or more generally, from cellular carbon substrates. The existing situation: the NAD(P H-type II (Ndh-II) are enzymes capable of oxidizing NAD (P) H and transferring electrons to a quinone molecule (plastoquinone or ubiquinone). They are known as type II by analogy with mitochondrial complex I. As regards the chain of mitochondrial electron transport, NDH-II proteins constitute an alternative pathway to complex I and II to bring electrons to the ubiquinone pool. This alternative pathway would enable an adaptation to the yield of the electron transport chain based on the metabolic state of the algae. As regards the chloroplast electron transport chain, Ndh-II proteins are thought to participate in several mechanisms of adaptation to light intensity variations. Their function would be for the non-photochemical reduction of the PQ pool. In 2005, seven ''open reading frames'' corresponding to hypothetical type II NAD(P)H dehydrogenase (NDA1 to NDA2) were identified in the nuclear genome of Chlamydomonas. A study of Chlamydomonas NDA gene expression highlighted the most important expression of the NDA2 gene. In order to specifically study the role of the NDA2 enzyme, it was inactivated by RNA-interference. (Fred Jans thesis 2011). From the wt84 strain (Chlamydomonas reinhardtii), two lines of mutant deficient Nda2 were obtained: G4: Nda2-RNAi (1) P11: Nda2-RNAi (2) If we consider these lines from a phenotypic point of view, two main theoretical hypotheses can be made: is there a significantly decreased reduction of the PQ pool by the PSII-independent pathway? is there an affected, reduced or even completely inhibited hydrogen photobioproduction? In order to study the effect of the deficiency of the enzyme (Nda2) on the potential for hydrogen production, a set of tools and specific experimental protocols had to be developed to meet the second hypothesis (above). The aim of this project was mainly be to develop the study of modifications in hydrogen production. Purpose and specificity of the thesis: The purpose and specificity of this project was to break away from complex technical difficulties: knowing that the two mutant lines of Chlamydomonas reinhardtii were wall-less cells and therefore, highly sensitive to hydrodynamic stress; knowing that the study of hydrogen photobioproduction by microalgae was based on the capacity of degassing the culture medium, i.e. the need to obtain optimal hydrodynamic agitation favoring gas exchange. The main challenge was therefore to develop a system to find a consensus technique in order to resolve the contradiction between preserving the fragile algae while causing sufficient hydrodynamic agitation to degas the culture medium. In 2005, experimental tools for the study of hydrogen production by microalgae were poorly developed. The majority of H2 photoproduction experiments were conducted in glass bottles according to the Melis protocol. The Melis protocol is based on a temporal separation of two phases: the first is a phase of growth of microalgae in a culture medium that is optimal for photosynthesis and the accumulation of reserves (starch); the second phase begins after the transfer of the microalgae into a sulfur depleted medium. This procedure consists of causing biochemical stress, inducing reorganization and metabolic adaptation which will eventually lead to hydrogen photobioproduction. Although it is sufficient for a basic approach, the experimental procedure of bottle culture has several major drawbacks when it comes to studying the processes of hydrogen production over long periods (100 to 200 hours). In the bottles, the homogenization of the culture medium is conducted using magnetic stirrers moved by rotary shakers. To obtain good homogenization, a minimum speed of agitation is necessary. This process induces a relatively large hydrodynamic stress, resulting in significant cell death. On the other hand, microscope observation of Chlamydomonas cells grown in sulfur depleted medium deficient shows that the majority of algae lose their flagella and thus their natural mobility. This phenomenon reinforces the idea that magnetic stirrers severely limit the quality of experimental results: the agitation necessary for good homogenization must be more vigorous in sulfur depleted medium than in an optimal medium. Another major problem encountered in experiments using bottles is the quality of degassing. Generally, the analysis of gas products is done by gas chromatography; samples are taken in the gas phase, and then analysed. This method is unsuitable for this type of experiment. Is the gas phase in equilibrium with the liquid phase? Is there a risk of over or under-saturation of hydrogen? Is there an influence from pressure? Is there a risk of inhibiting the production of hydrogen by its own concentration in the medium? Does periodic and repeated sampling induce disturbances in how the reaction takes place? In order to solve these uncertainties and technical difficulties, a new and original concept of algal culture has been developed. The basic principle of this system involves placing a suspension of algae (culture medium) in a photobioreactor made of two transparent tubes connected at their ends. The photobioreactor is fixed on an oscillating table. A glass ball placed in one of the tubes slides because of the force of gravity, and this enables the homogenization of the medium. In addition to obtaining optimal homogenization without hydrodynamic stress (by three different types of mixing), a geometric feature of the whole has enabled active degassing of the hydrogen produced in the culture medium. Parallel and in annex to this photobioreactor (PBR), a system enabling the measurement and analysis in real time of the concentration of hydrogen in the gas phase has been developed. This system is based on the principle of polarographic analysis of oxygen concentration developed by Leland C. Clark. The O2 and H2 concentrations can be measured by a periodic reversal of the voltage across the electrodes. Finally, a theoretical model of evolution and equilibrium of hydrogen concentration in the PBR has been developed to monitor and compare the experimental results. The findings: The new concept of microalgae culture developed in this project has solved several problems. The homogenization of the culture medium by mixing the phases and stirring with a glass ball is a particularly effective alternative compared to mixing with the magnetic stirrers commonly used in bottles. Cell death by hydrodynamic stress can be reduced to virtually zero, whereas experience has shown that in this field, mixing using magnetic stirrers is a relatively harmful process. The original system of mixed phases with active degassing (at atmospheric pressure) has resulted in superior yields of hydrogen being produced than in other systems. The real-time analysis of changes in concentrations of oxygen and hydrogen via the probes has increased the accuracy of the results. It was observed that the variation of several experimental factors could lead to significant distortions between the theoretical model of evolution of the concentration of hydrogen (depending on the gas collected in the gasometer) and the measurements made using gaseous chromatography (GC). Those factors are the following: the quantity of culture medium in the reactor; he geometry of the interface between gas phase and liquid phase; he speeds of the mixing cycles; the pressure of the PBR; dynamic permeability and porosity; changes in production rates of hydrogen in different strains of microalgae. Because of these factors, changes in the experimental protocol were required: fixing an interval of time (within each experiment) to obtain the speed ​​of stable production; a study on the influence of pH, which helped validate the experimental range usually used; a study on the influence of hydrogen concentration on the rate of production. These changes have not only increased measurement accuracy, but have also confirmed certain hypotheses concerning a probable inhibition of hydrogen production by its own concentration in the culture medium. Confirmation of the inhibition of hydrogen production by its own concentration in the culture medium is undoubtedly the most important piece of information provided by the latter optimization of the protocol. Parallel to this, the observation of significant discrepancies between the theoretical model of the evolution of hydrogen concentration (depending on the gas collected in the gasometer) and the measurements made by gas chromatography (GC), result in the latter (GC) seeming to be unreliable in this type of experiment. The contribution of hydrogen / oxygen probes in the field of hydrogen photobioproduction by microalgae Developing of the system of measuring O2/H2 probes by time multiplexing (periodic alternation of the polarity probe) has provided new insights into the possibilities of monitoring the evolution of hydrogen concentration in real time. Although these probes were made by hand and used without the real purpose of gaining precise quantification, their potential in this area of ​​research is clearly visible. It is obvious that developing a similar system, but more accurate in terms of electrode geometry, would allow the calibration and enhancement of measurements (from a quantitative point of view). Besides this, an optimization of surface characteristics of the electrodes would also improve performance and increase capacity of use. A perfectly sealed probe head could work in the liquid medium and directly provide the values ​​of hydrogen concentration in the liquid phase. It is likely that this method of measuring hydrogen concentration by polarography, may in future replace the current method of gas chromatography. Taking all these elements into account: In the semi-closed PBR, the main problem for obtaining the values ​​of metabolic fluxes to study is keeping the characteristics of the gas exchange in well-defined operating range (pressure, H2 concentration and mixing dynamics). It is demonstrated in this paper that this procedure is relatively easy to carry out: the only constraint is to precisely define the characteristics of the PBR and the theoretical models. In the second part of the project, the photobioreactor is used to develop and complete a protocol analysis to characterize the relative contributions of the two metabolic pathways involved in hydrogen photobioproduction (the chloroplast electron transport chain) in the microalgae Chlamydomonas reinhardtii. Two publications have been written regarding the biochemical approach of the second part; interested readers can find there all the results and comments that this project has brought to the field. Follow-up to, and the future of, this project: Thanks to the PBR and its multi-adaptability, an original approach to the theoretical modeling of the metabolism of hydrogen production is possible if the following are known: the various flux values ​​of the metabolic pathways; the volumes of hydrogen produced; production rates based on metabolic configurations; the speed and quantity of starch consumed; the speeds of mitochondrial respiration and their involvement in hydrogen production (via PEDO2). By standardizing and unifying the various units of measurement used to characterize the flow and the amounts of material as well as the electrochemical potentials and the gradients, through which the matter passes, it should be possible to construct a matrix model according to Kirchhoff's laws. From this model, it should be possible to deduce other values and other metabolic constants without having to necessarily pass through experimentation. This model would also, by successive iterative approaches and extrapolation, determine new optimal operating ranges for the PBR. [less ▲]

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See detailLithostratigraphie, sédimentologie et analyse séquentielle du Quartzite de Berlé (Emsien supérieur, Grand-Duché de Luxembourg)
Michel, Jonathan ULg

Doctoral thesis (2012)

The Lower Devonian is a period of interest because it is characterized by the first transgression of the Rheic Ocean, after the Caledonian orogeny, over the coasts of the Old Red Sandstones Continent. In ... [more ▼]

The Lower Devonian is a period of interest because it is characterized by the first transgression of the Rheic Ocean, after the Caledonian orogeny, over the coasts of the Old Red Sandstones Continent. In the Ardenne Basin, during this transgression, widespread siliciclastic deposits were deposited. From the Lochkovian to the Upper Emsian, the basin underwent various stages of development. The main object of this PhD thesis was to focus on one of these episodes recorded in the Neufchâteau-Wiltz-Eifel Basin. This work is the result of the integration of different techniques, such as field work, microscopic analyses, biostratigraphy, sequence stratigraphy, magnetic susceptibility and diagenesis. The analysis of the microfossil content of four sections in Luxembourg led to the identification of 23 species of spores and 11 species of acritarchs. Biostratigraphically, these spores confirmed the Emsian age of the different lithological units (“Couches de Clervaux”, “Quartzite de Berlé” and “Schistes de Wiltz”). The sedimentological analysis of the Neufchâteau-Wiltz-Eifel Basin is based on the study of more than 600 thin sections from 11 sections covering the entire basin. This study allowed to identify an estuary setting divided into three types of environments: an alluvial, a tidal and finally a marine distal environment. Detailed sedimentology associated with sequence stratigraphy of the whole Neufchâteau-Wiltz-Eifel Basin allowed to propose a vertical and lateral succession model of this estuarine setting. In this model, the “Quartzite de Berlé” corresponds to tidal sand ridges and changes laterally to the flaser bedded sandstones of the top of the “Couches de Clervaux”. This lateral facies transition tends to proof that the “Quartzite de Berlé” is a lenticular deposit. The “Quartzite de Berlé” is a prominent feature in the landscapes and a very resistant rock appreciated as a building material. Diagenesis study allows a better understanding of the mechanisms responsible for these characteristics, trough the identification of different cements and authigenic minerals. Temporal relationships between these different components are integrated in a paragenetic modelisation that includes four distinct phases: an eogenetic, a mesogenetic, a metamorphic and a telogenetic phase. The clay mineralogy (illite cristallinity) shows that the “Quartzite de Berlé” underwent variable conditions of burial, depending of the area considered. Our results point out that this variability is related to the pre-orogenetic rifting stage of the Rhenohercynian Basin. Finally, the use of magnetic susceptibility, suggested that in proximal setting, the magnetic susceptibility signal is mainly controlled by environmental parameters (water agitation, sedimentation rates) and diagenesis. [less ▲]

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See detailIntegration of farmers in the shrimp subsector in the Mekong River Delta, Vietnam
Ho, Thi Minh Hop ULg

Doctoral thesis (2012)

Hatcheries, input dealers, farmers, collectors and processors are the primary actors of shrimp value chain in the Mekong River Delta (MRD) Vietnam, a sector that has many problems of disease, shrimp seed ... [more ▼]

Hatcheries, input dealers, farmers, collectors and processors are the primary actors of shrimp value chain in the Mekong River Delta (MRD) Vietnam, a sector that has many problems of disease, shrimp seed, environmental pollution, and management skills. Holding the strongest power in the shrimp value chain, the processors determine shrimp prices and set up requirements of shrimp quality and size in the market though quality control has not been completely implemented due to the limitations of financial capital, knowledge, awareness, as well as the quality of raw material supplied by collectors and farmers. Farmers stayed in the weakest position in the chain due to their small individual scale, and low skills. The results of the study show that most of the shrimp farmers stay out of vertical integration under farming contracts while the rest joined in the game without success. Contract farming seems not for small scale farmers who account for a large part in the MRD, and not interesting for producers who get success with their cultivation. Farmers prefer a non-contract option due to non-transparency of interest share as well as cost account. Food safety standards, decision No. 80/2002/QĐ-TTg, culture, trust, government structure, credit support and corruption are the main factors affecting farmers’ integration chances. Floor price mechanism, risk sharing, small scale of the model of vertical integration and excess suppliers in the market, administrative misconception and inefficient public management are the main reasons of failures of contract farming of two case studies in the MRD. Planning and projection of shrimp production zones are therefore the priority matters to address. Furthermore, re-organizing shrimp farmers into legal teams or groups or cooperatives is also necessary to increase the size of the existing shrimp cultivation units in Vietnam in order to improve the sector. [less ▲]

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See detailGeophysical identification, characterization, and monitoring of preferential groundwater flow paths in fractured media
Robert, Tanguy ULg

Doctoral thesis (2012)

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to ... [more ▼]

This thesis investigates fractured zones leading to preferential groundwater flow paths. In this context, we used the electrical resistivity tomography (ERT) and the self-potential (SP) methods to identify, characterize, monitor, and finally model preferential flow in hydraulically-active fractured zones at a scale representative of real world applications. From an experimental point of view, we first identified the magnitude of self-potential signature, a -15 mV anomaly that could be associated with preferential groundwater flow in a shallow quartzite aquitard whereas the streaming potential theory was originally developed for porous media. This signature was confirmed experimentally in limestone aquifers at greater depths. The joint use of surface ERT and SP allowed the identification of water-bearing fractured areas which were electrically more conductive, presenting contrasts from 1 to 10 and which were hydraulically-active presenting negative SP anomalies ranging from -10 to -30 mV. We were also able to correlate hydraulic heads and SP gradients during a low and a high groundwater level period leading to interesting perspectives in understanding the dynamics of complex groundwater flow systems. Finally, a preferential flow and rapid transport path, over 10 m/h, was highlighted in a 20 m deep fractured and karstified limestone valley by monitoring a salt tracer test with only surface ERT. This methodology was being mostly used for relatively shallow and homogeneous aquifers up to now. Such information is crucial to set up new monitoring wells or to define the sampling rates of classic tracer test. From a methodological point of view, we quantitatively assessed the efficiency of blocky and minimum-gradient-support regularizations in electrical imaging to recover sharp interfaces on numerical benchmarks and with field data. The usefulness of resolution indicators such as the cumulative sensitivity matrix and the resolution matrix were also assessed in this context. We demonstrated that noise characterization is crucial in time-lapse inversion and may supplant the choice of the time-lapse inversion scheme, calling for a systematic analysis of reciprocal measurements (or a subset of them). We also showed that, when using data differences in an inversion scheme, the data error, as estimated by time-lapse reciprocal measurements, depends on the mean measured resistance. These error characterization studies should always be performed if one wants to avoid wrong interpretations about the hydrodynamics. We further showed that focused inversion techniques (blocky inversion, minimum-gradient-support) may offer great perspectives when recovering model changes in time-lapse inversion. Finally, ERT and SP were jointly used to conceptualize a physically-based and spatially distributed hydrogeological model, in particular to characterize the preferential flow paths. Predicted hydraulic heads and SP-derived hydraulic heads using the water table model showed a clear correlation, leading to perspectives in terms of hydrogeological model calibration. Further experiments are however needed to fully estimate the streaming potential apparent coupling coefficient, but the use of the full SP signals for hydrogeological model calibration is a clear perspective to this work. [less ▲]

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See detailEtudes des systèmes de défenses antitoxiques chez l’amphipode Gammarus roeseli : Effets du parasitisme et d’une exposition au cadmium.
Gismondi, Eric ULg

Doctoral thesis (2012)

Pour faire face à des perturbations environnementales, les organismes ont développé des défenses antitoxiques couramment utilisés comme biomarqueurs dans l’évaluation de la qualité des milieux. Cependant ... [more ▼]

Pour faire face à des perturbations environnementales, les organismes ont développé des défenses antitoxiques couramment utilisés comme biomarqueurs dans l’évaluation de la qualité des milieux. Cependant, de nombreux facteurs confondants comme la température ou le genre, influencent la réponse de ces biomarqueurs. Il est ainsi nécessaire de connaitre les effets de ces facteurs afin d’imputer correctement la réponse biologique mesurée à la présence de polluants. Dans ce contexte, nous avons choisi d’étudier l’influence d’un parasite acanthocéphale, Polymorphus minutus, transmis horizontalement et de microsporidies à transmission verticale, sur les réponses physiologiques de leur hôte, Gammarus roeseli, un crustacé amphipode d’eau douce d’intérêt écotoxicologique. Pour cela, nous avons choisi d’étudier le glutathion, tripeptide jouant un rôle central dans les systèmes antitoxiques, sa synthèse (i.e. activité γ-glutamylcystéine ligase), les réserves énergétiques (i.e. lipides, glycogène, protéines) et un biomarqueur d’effets toxiques, le malondialdéhyde. L’influence du parasitisme a été appréhendé dans différents cas d’études: (i) chez G. roeseli infecté par P. minutus, (ii) chez G. roeseli infecté par des microsporidies (Dictyocoela roeselum essentiellement) et (iii) chez G. roeseli co-infecté par ces deux types de parasite. Chaque cas d’étude a été réalisé en absence de stress et lors d’une exposition au cadmium. Nous avons mis en évidence qu’en absence de contamination, la présence de P. minutus et une co-infection par P. minutus et D. roeselum affectent les biomarqueurs de G. roeseli. Après exposition au cadmium, la présence de parasites (i.e. infection simple ou co-infection) modifie la mobilisation des défenses antitoxiques et accentue les effets toxiques subits par l’hôte. Les résultats obtenus au cours de ce travail mettent en avant le caractère confondant du parasitisme en écotoxicologie et souligne l’importance de prendre en compte ce paramètre lors de l’évaluation de la qualité des milieux. [less ▲]

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See detailStudy of the portals of entry of Cyprinid herpesvirus 3 in Cyprinus carpio
Fournier, Guillaume ULg

Doctoral thesis (2012)

The common carp is one of the most important freshwater species in aquaculture and its colourful subspecies koi is grown for personal pleasure and exhibitions. Both subspecies are economically important ... [more ▼]

The common carp is one of the most important freshwater species in aquaculture and its colourful subspecies koi is grown for personal pleasure and exhibitions. Both subspecies are economically important. In the 1990s, a highly contagious and lethal pathogen called koi herpesvirus (KHV) or cyprinid herpesvirus 3 (CyHV-3) began to cause severe financial losses in these two carp industries worldwide. Because of its economic importance and its numerous original biological properties, CyHV 3 became rapidly an attractive subject for applied and fundamental research. The goal of this thesis was to identify the portals of entry of CyHV-3 in carp. This information is essential to understand the pathogenesis and the epidemiology of the infection, but also to develop efficacious vaccines. Prolonged CyHV-3 cultivation in vitro leads to the spontaneous attenuation of the virus. To circumvent this problem, the entire viral genome was cloned as a bacterial artificial chromosome (BAC). Then to test the usefulness of the BAC clone, several recombinants strains were generated as described in the first chapter. In the second chapter, we took profit of the CyHV-3 BAC clone to produce a recombinant strain encoding a firefly luciferase (LUC) expression cassette. Infection of carp by immersion in water containing the CyHV-3 LUC strain demonstrated, using bioluminescent in vivo imaging system (IVIS), that the skin, and not the gills, is the major portal of entry for CyHV-3. Fish skin provides mechanical, chemical and immune protection against injury and pathogenic microorganisms. Its mucus layer confers an innate immune protection against pathogen entry. However, there is little in vivo evidence on the role of skin mucus as a first line of innate immune protection against bacterial and viral infections. In the third chapter, we used the CyHV-3 LUC strain and IVIS to investigate the roles of epidermal mucus as an innate immune barrier against CyHV-3 entry. Our results demonstrate that the mucus of the skin inhibits CyHV-3 binding to epidermal cells and contains soluble molecules able to neutralize CyHV-3 infectivity. The skin is the major portal of entry after inoculation by immersion in water containing CyHV-3. While this model of infection mimics some natural conditions in which infection takes place, other epidemiological conditions could favor entry of virus through the digestive tract. Consequently, in the fourth and last chapter, we investigated the role of the carp digestive tract as a viral portal of entry using bioluminescence imaging. We found that feeding carp with infectious materials induces CyHV-3 entry through infection of the pharyngeal periodontal mucosa. In conclusion, this study demonstrated that according to epidemiological conditions, CyHV-3 can enter carp either through infection of the skin (immersion in infectious water) or through infection of the pharyngeal periodontal mucosa (feeding on infectious materials). The existence of these two portal of entry adapted to different epidemiological conditions most probably contributes to the high contagious nature of the virus. [less ▲]

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See detailL’action publique de lutte contre le travail des enfants au Burkina Faso : politiques, acteurs, dynamique d’actions et controverses
Wouango, Joséphine ULg

Doctoral thesis (2012)

La thèse analyse les politiques et les interventions en matière de protection de l'enfance au Burkina Faso. Les enseignements de cette recherche concernent sa dimension empirique d'une part et son objet ... [more ▼]

La thèse analyse les politiques et les interventions en matière de protection de l'enfance au Burkina Faso. Les enseignements de cette recherche concernent sa dimension empirique d'une part et son objet spécifique d'autre part. Cet objet n'est pas le travail des enfants comme tel, mais la construction d'une politique publique dans un pays qui reste massivement rural et largement dépendant de l'aide internationale. [less ▲]

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See detailPoroelastic Center of Dilation Revisited
Huynen, Alexandre ULg

Master of advanced studies dissertation (2012)

In both elasticity and poroelasticity, the nucleus of strain is usually used to refer to a singular solution such as the point force, the force dipole, the centers of rotation and dilation, etc. These ... [more ▼]

In both elasticity and poroelasticity, the nucleus of strain is usually used to refer to a singular solution such as the point force, the force dipole, the centers of rotation and dilation, etc. These fundamentals solutions constitute the building blocks for various problems of practical importance and are, therefore, relatively well understood. However, a comparison of the original elastic solution for the center of dilation with the classic Lamé solution reveals an unexpected dependence of the center of dilation solution on the Poisson’s ratio. This inconsistency is investigated by means of two alternative representations of the singularity and leads to the identification of a compressed zone inside the singularity. The poroelastic equivalent to this nucleus of strain is shown to be the superposition of the elastic one with drained material parameters and an instantaneous point fluid source associated with a finite volume of fluid that is expelled from the compressed region inside the singularity and is injected in the porous medium. [less ▲]

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See detailOrigine et effet de la myéloperoxydase lors de la congélation du sperme d'étalon
Ponthier, Jérôme ULg

Doctoral thesis (2012)

Semen freezing allows worldwide commercialization of equine genetic. Despite improvement of techniques, semen of 20% of stallions remains unfreezable. Currently, post-thaw semen quality is only determined ... [more ▼]

Semen freezing allows worldwide commercialization of equine genetic. Despite improvement of techniques, semen of 20% of stallions remains unfreezable. Currently, post-thaw semen quality is only determined by progressive motility, but its definition is not standardised. Spermatozoa are highly differentiated cells and freezing lesions can occur on DNA, membrane, mitochondria or acrosome. Current research focuses on prediction of freezability, improvement of freezing extenders and prevention of Reactive Oxygen Species (ROS) effects. Under its O2 form, oxygen is inactive and oxidase or oxygenase enzymes are required to produce ROS. Two pathways of ROS production in semen are described: the intrinsic pathway reflecting ROS escaping from the spermatozoon mitochondria and the extrinsic pathway corresponding to ROS produced by inflammatory cells. ROS induce DNA fragmentation, lipid peroxidation, apoptosis and decreased motility of spermatozoa. Myeloperoxidase (MPO) is a pro-oxidant enzyme contained in and released by neutrophils during degranulation or after lysis. It is responsible for formation of hypochlorous acid, a strong oxidant, which could damage spermatozoa. However, MPO presence and effects have never been investigated in equine semen. The first aim was to assay presence of MPO in equine thawed semen and to determine a relation between MPO concentration and post-thaw semen parameters. 35 straws from different stallions were analyzed. Post-thaw spermatozoa and MPO concentrations, viability, morphology, progressive and total motility were determined. Our study showed that thawed semen contains large amounts of free MPO. High MPO concentration samples showed lower total and progressive motility. Higher proportion of acrosome reaction was observed in late examinations of the high MPO concentration group. As MPO was present in frozen semen and did interfere with its quality, timing and origin of its release was determined during the freezing process. Forty ejaculates were frozen with a classical procedure. MPO ELISA and MPO immunocytochemistries (ICC) were assayed in raw semen, centrifugation supernatant, and after cooling down to 4°C. Post-thaw MPO concentration and spermogram parameters were determined. MPO concentration increased after cooling and thawing when compared to fresh semen. As temperature decreased, MPO was higher in post-thaw poor quality samples. Non-sperm cells (NSC) showed various degrees of MPO-ICC, and were mostly epithelial cells with nuclear picnosis. Elastase, another neutrophil pro-inflammatory enzyme, was also assayed in post-thaw semen. In twenty ejaculates, NSC concentration was determined in fresh semen. Post-thaw motilities were determined by CASA; MPO and elastase concentrations were assayed by ELISA. Post-thaw elastase concentrations were low and there was no difference according to semen quality. NSC or MPO concentrations were not correlated to elastase concentration. NSC concentration was higher in unfreezable semen and correlated to post-thaw MPO concentration. To confirm MPO release by NSC during freezing, the effect of washing semen with density gradient centrifugation (DGC) was then assayed on NSC and MPO concentrations. NSC and MPO concentrations were assessed at each step and MPO localization was performed by ICC. DGC washing decreased NSC and MPO concentrations in post-thaw semen and NSC were mainly remaining in DGC supernatant. MPO concentration was correlated with NSC concentration in the upper layer of the DGC supernatant and in post-thaw semen. NSC were epithelial cells showing MPO-ICC staining. Fresh semen MPO concentration had no effect on fresh or post-thaw semen quality, while post-thaw semen concentrations were correlated with decreased motility. To understand these findings, concentration, activity and structure of MPO present in seminal plasma, sperm-rich pellet and post-thaw semen were assayed. Factor inducing MPO release was determined by adding or not glycerol in samples stored at 4°C or 20°C. Total MPO was high in seminal plasma and thawed semen and low in sperm-rich pellet. Active MPO was high in sperm-rich pellet and low in seminal plasma and post-thaw semen. MPO concentrations were correlated in post-thaw and in semen cooled at 4°C with or without glycerol. Active MPO in sperm-rich pellet and post-thaw progressive motility were highly negatively correlated. MPO present in fresh semen is mainly the native inactive enzyme subunit. To confirm our previous findings, effect of active MPO and fresh or frozen-thawed NSC was assayed on purified spermatozoa motility, mitochondrial potential, membrane and acrosome integrity. Highest MPO concentration tested (50ng/ml) decreased motility. However, highest MPO concentration did not affect mitochondrial potential, membrane or acrosome integrity. Thawed NSC did decrease motility and mitochondrial potential when compared to fresh NSC, suggesting a synergic effect between MPO and other products released by NSC after thawing. Temperature decrease during freezing process increases MPO concentration and post-thaw concentration is negatively associated to post-thaw motilities. ICC slides have shown MPO presence on epithelial keratinized and pycnotic cells while neutrophils were rarely observed. Semen washing with DGC decreases MPO and NSC concentrations in post-thaw semen as NSC and MPO concentrations were positively correlated. MPO present in seminal plasma is native and inactive form while MPO present in sperm-rich pellet is active and negatively correlated to the post-thaw progressive motility. Addition of active MPO in semen decreased motility but had no effect on acrosome integrity, despite what had previously been suggested. Thawed NSC addition to spermatozoa decreased mitochondrial potential, suggesting a synergic effect between MPO and other factors released by NSC. Further studies should investigate the origin of high inactive MPO concentrations in fresh semen. Other studies should be conduced about the origin of epithelial keratinized pyknotic NSC in fresh semen and the pathophysiological mechanism leading to their MPO release during freezing. Large scale studies should be conducted to confirm the use of NSC concentration in fresh semen or active MPO concentration in sperm rich pellet as freezability prognosis. Further studies should also investigate effect of MPO specific inhibitors. [less ▲]

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