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See detailRole de l'ADN endogène et d'Interferon Response Factor-3 dans l'induction des réponses immunitaires médiées par les lymphocytes T auxiliaires de type 2.
Marichal, Thomas ULg

Doctoral thesis (2011)

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense ... [more ▼]

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense against helminths and artificially adjuvanted vaccination. Induction of adaptative T responses occurs with the help of innate immune cells, especially dendritic cells (DCs). These DCs make the link between innate and adaptative immunity by taking up antigens in peripheral tissues, migrating to lymphoïd organs and presenting antigens to T lymphocytes. Direct or indirect activation of these cells depends on the interaction between exogenous or endogenous danger signals and conserved innate immune receptors, mainly represented by Pattern Recognition Receptors (PRRs). Despite the importance of Th2 responses, the innate immune mechanisms leading to their activation remain partially unknown. For this reason, we have been interested in immune mechanisms underlying the induction of Th2 responses in two major Th2-dependent immunological processes : airway allergy and vaccination with aluminium hydroxides (alum). Airway allergy, of which the most severe manifestation is allergic ashma, is a constantly increasing disease in developped countries. It appears clearly that the stimulation of PRRs by allergens or immunostimulatory molecules plays a key role in the pathophysiology of airway allergy. In addition, PRRs transduce the signal though a limited number of signaling pathways and the role of Interferon Response Factor (IRF)-3 and IRF-7, two important transcription factors downstream of various PRRs, in the pathogenesis of allergic asthma, remains unknown. Therefore, we have investigated their potentiel implication in this disease. We have discovered that IRF-3, but not IRF-7, plays an essential role in allergic airway sensitization against house dust mite antigens, the main allergen source in humans. We have further demonstrated that IRF-3 was intrinsically required in lung DCs for their proallergic function. The IRF-3-dependent effects were independent of type I interferons, the main target genes of IRF-3. Alum is the most widely used artificial adjuvant in human and animal vaccination. Yet, little is known about its mechanism of action, in particular regarding the nature of signals and signaling pathways promoting Th2 responses. We have postulated that alum, like any other efficient adjuvant, must be expected to stimulate innate immunity. On one hand, alum does not contain any molecular pattern that is recognized by PRRs and, on the other hand, alum is known to be cytotoxic. Therefore, we hypothetised that alum-induced endogenous danger signals could play a role in its adjuvant activity. Here, we report that alum induces cell death and subsequent DNA release. This DNA acts as a endogenous immunostimulatory signal relaying alum adjuvant activity on adaptative responses. Furthermore, we propose that host DNA differentially regulates IgG1 and IgE production following alum immunization. Indeed, an IRF-3-dependent DNA signaling pathway plays a role in the activation of inflammatory DCs, the subsequent induction of Th2 response and IgE isotype switching, whereas DNA also induces IgG1 production through IRF-3- independent mechanisms. The finding that host cell endogenous DNA is a damageassociated molecular pattern relaying alum adjuvant activity may thus help in the comprehension of the mechanisms of action of current vaccines and in the design of novel adjuvants. In conclusion, this work has identified a previously unappreciated role for IRF-3, a transcription factor downstream of various PRRs primarily implicated in antiviral responses, in two Th2-dependent immunological processes: allergic asthma and alum-based vaccination. In these models, we have shown that IRF-3 was intrinsically required in professional antigen presenting cells, namely DCs, in order to activate them, a precondition for the priming of adaptative Th2 responses. In addition, we also discovered that host DNA released upon alum treatment acts as an endogenous danger signal mediating the adjuvant activity of alum. [less ▲]

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See detailSemi-solid constitutive modeling for the numerical simulation of thixoforming processes.
Koeune, Roxane ULg

Doctoral thesis (2011)

Semi-solid thixoforming processes rely on a material microstructure made of globular solid grains more or less connected to each other, thus developing a solid skeleton deforming into a liquid phase ... [more ▼]

Semi-solid thixoforming processes rely on a material microstructure made of globular solid grains more or less connected to each other, thus developing a solid skeleton deforming into a liquid phase. During processing, the material structure changes with the processing history due to the agglomeration of the particles and the breaking of the grains bonds. This particular evolutive microstructure makes semi-solid materials behave as solids at rest and as liquids during shearing, which causes a decrease of the viscosity and of the resistance to deformation while shearing. Thixoforming of aluminum and magnesium alloys is state of the art and a growing number of serial production lines are in operation all over the world. But there are only few applications of semi-solid processing of higher melting point alloys such as steel. This can partly be attributed to the high forming temperature combined with the intense high temperature corrosion that requires new technical solutions. However the semi-solid forming of steels reveals high potential to reduce material as well as energy consumption compared to conventional process technologies, such as casting and forging. Simulation techniques exhibit a great potential to acquire a good understanding of the semi-solid material process. Therefore, this work deals with the development of an appropriate constitutive model for semi-solid thixoforming of steel. The constitutive law should be able to simulate the complex rheology of semi-solid materials, under both steady-state and transient conditions. For example, the peak of viscosity at start of a fast loading should be reproduced. The use of a finite yield stress is appropriate because a vertical billet does not collapse under its own weight unless the liquid fraction is too high. Furthermore, this choice along with a non-rigid solid formalism allows predicting the residual stresses after cooling down to room temperature. Several one-phase material modeling have been proposed and are compared. Thermo-mechanical modeling using a thermo-elasto-viscoplastic constitutive law has been developed. The basic idea is to extend the classical isotropic hardening and viscosity laws to the non solid state by considering two non-dimensional internal parameters. The first internal parameter is the liquid fraction and depends on the temperature only. The second one is a structural parameter that characterizes the degree of structural build up in the microstructure. Those internal parameters can depend on each other. The internal parameters act on the the viscosity law and on the yield surface evolution law. Different formulations of viscosity and hardening laws have been proposed and are compared to each other. In all cases, the semi-solid state is treated as a particular case, and the constitutive modeling remains valid over the whole range of temperature, starting from room temperature to above the liquidus. These models are tested and illustrated by mean of several representative numerical applications. [less ▲]

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See detail"Intentionnalité et inconscient. Réflexions sur le fonctionnement de la vie psychique à partir du premier Husserl et de Freud"
Gyemant, Maria ULg

Doctoral thesis (2011)

This work tries the limits of Husserl’s concept of intentionality as it is conceived in the Logical Investigations. Once these limits exposed, we claim that Husserl’s theory of intentionality be completed ... [more ▼]

This work tries the limits of Husserl’s concept of intentionality as it is conceived in the Logical Investigations. Once these limits exposed, we claim that Husserl’s theory of intentionality be completed with a theory of the unconscious of Freudian inspiration. Thus, on the conceptual basis of Husserl and Freud’s work we elaborate an exhaustive map of the human mind, that shows not only the consciousness, but also the other mental phenomena. Our first section shows that Husserl’s concept of intentionality is established in opposition to Brentano’s intentionality. We also analyse the problem it is meant to solve, namely how exactly the mind connects with its objects. We show that this way of understanding intentionality cannot explain the dynamical aspect of intentional acts. Our second section is thus dedicated to this issue. A group of texts written by Husserl around 1913-1914 on the concept of tendency show clearly that Husserl never stopped in fact questioning the dynamical character of intentionality although he couldn’t explain it without thinking it as a form of intentionality. This solution leads nevertheless to an infinite regress. We have chosen thus in our third section to try a new approach of the dynamical aspect by using Freud’s approach to the Unconscious. The Freudian Unconscious has thus been articulated to Husserl’s theory of intentionality and at the same time the dynamical aspect of the latter has found an appropriate conceptual expression. [less ▲]

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See detailOn the sets of real vectors recognized by finite automata in multiple bases
Brusten, Julien ULg

Doctoral thesis (2011)

This thesis studies the properties of finite automata recognizing sets of real vectors encoded in positional notation using an integer base. We consider both general infinite-word automata, and the ... [more ▼]

This thesis studies the properties of finite automata recognizing sets of real vectors encoded in positional notation using an integer base. We consider both general infinite-word automata, and the restricted class of weak deterministic automata, used, in particular, as symbolic data structures for representing the sets of vectors definable in the first order additive theory of real and integer numbers. In previous work, it has been established that all sets definable in the additive theory of reals and integers can be handled by weak deterministic automata regardless of the chosen numeration base. In this thesis, we address the reciprocal property, proving that the sets of vectors that are simultaneously recognizable in all bases, by either weak deterministic or Muller automata, are those definable in the additive theory of reals and integers. Precisely, for weak deterministic automata, we establish that the sets of real vectors simultaneously recognizable in two multiplicatively independent bases are necessarily definable in the additive theory of reals and integers. For general automata, we show that the multiplicative independence is not sufficient, and we prove that, in this context, the sets of real vectors that are recognizable in two bases that do not share the same set of prime factors are exactly those definable in the additive theory of reals and integers. Those results lead to a precise characterization of the sets of real vectors that are recognizable in multiple bases, and provide a theoretical justification to the use of weak automata as symbolic representations of sets. As additional contribution, we also obtain valuable insight into the internal structure of automata recognizing sets of vectors definable in the additive theory of reals and integers. [less ▲]

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See detailNutrient fluxes and soil microbial processes
Bazgir, Masoud ULg

Doctoral thesis (2011)

Because of previous intense forest use and over exploitation in the past centuries, the plantation of coniferous stands, especially Norway spruce (Picea abies L. KARST.) with high production potentials ... [more ▼]

Because of previous intense forest use and over exploitation in the past centuries, the plantation of coniferous stands, especially Norway spruce (Picea abies L. KARST.) with high production potentials has been a common European afforestation strategy. However, the characteristics of Norway spruce such as susceptibility to windfall, forest dieback, drought, as well as soil acidification have caused negative ecological impacts in many sites. Conversion of conifers into deciduous or mixed stands has been suggested by some foresters, in order to improve the stability, ecology and biodiversity of forest ecosystems. Such changes in forest management require specific information on the impact of tree species on nutrient cycling, soil properties and microbial activities. In this study, six broadleaved species were growing at the same site with similar condition in terms of soil type, land use history and climate. Thus, the potential effects on biogeochemical cycling could be attributed to tree species. In this thesis, I focused on the effect of broadleaved species (conversion scenario) contrasting in terms of ecological characteristics (pioneer species versus main forestry species) and physiological characteristics (N2-fixing tree species (alder) versus non N2-fixing species) and Norway spruce (no conversion scenario) on (a) soil chemical properties (b) soil microbial activities and microbial biomass (c) nutrient input fluxes from throughfall and litterfall (d) foliar nutrient status. This investigation was carried out in south-eastern Belgium at a site converted in 1998 to a mixed deciduous stand, after two spruce generations. Plantations of common alder (Alnus glutinosa (L.) GAERTN.), european beech (Fagus sylvatica L.), pedunculate oak (Quercus robur L.), silver birch (Betula pendula ROTH.), goat willow (Salix caprea L.) and rowan (Sorbus aucuparia L.) were located in 4 fenced plots within a 81 ha catchment. Soil chemical properties (soil organic matter, pH, cation exchange capacity, base saturation, exchangeable cations), soil microbial activities (net N mineralization, potential nitrification, basal respiration) and microbial biomass (microbial biomass C and N) were measured under broadleaves and spruce. Soil chemistry of this highly acid soil was improved, 11 years after conversion, through an increase in base saturation and the exchangeable Mg2+ pool under rowan, as well as an increase in the exchangeable Ca2+ pool under alder, oak and rowan. Exchangeable acidity due to H+ in the forest floor also decreased under broadleaves. Nitrification was increased under the N2 fixing alder and decreased under young spruce. The C:N ratio of cold water-extractable soil organic matter fractions revealed to be a good indicator of potential nitrification rates within this site and across species, with a threshold of a C:N ratio of 10 above which soils did not nitrify. Throughfall and litterfall under the tree species were investigated by installing 63 throughfall collectors and 63 litter traps within 3 fenced plots (broadleaves) and across the catchment (young spruce). We measured the quantity of litterfall (foliar, twigs, reproductive parts and total), the quality of foliar litterfall (macro and micro-elements and C/N ratio) and calculated the potential nutrient return to the forest floor though foliar litterfall. For throughfall, we analyzed macro and micro-element concentrations and throughfall fluxes. Foliar nutrient status was determined by chemical analyses of fresh leaves and spruce needles of 3 age classes. The throughfall deposition of Ca2+, Mg2 and K+ was significantly higher under rowan and birch. NO3--N throughfall fluxes were significantly higher under young spruce compared to broadleaves. We observed the lowest total litterfall quantity produced by oak, while the highest litterfall quantity observed under rowan. Foliar litterfall of rowan showed significantly higher potential nutrient fluxes of Ca, Mg and K compared to other species, which corresponds to fresh foliage concentrations. The foliar litterfall was a main source of Ca, while for K throughfall was the main source of nutrient return to the forest floor in the study area. In spruce needles, Ca and Mg concentrations were at deficiency level and K concentrations at critical level, according to threshold values. Our results demonstrated that the plantation of pioneer species, especially rowan, may enhance the base cations in the forest floor on nutrient poor, acid soils through higher input in litterfall and throughfall. [less ▲]

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See detailTheoretical and Experimental Analysis of Liquid Flooded Compression in Scroll Compressors
Bell, Ian ULg

Doctoral thesis (2011)

Adding liquid to the working fluid in scroll compressors can allow for a working process that approaches isothermal compression. When liquid flooding and regeneration is applied to refrigeration and heat ... [more ▼]

Adding liquid to the working fluid in scroll compressors can allow for a working process that approaches isothermal compression. When liquid flooding and regeneration is applied to refrigeration and heat pump systems, simple cycle modeling predicts that for systems that operate at very large temperature lifts, the increase in system coefficient of performance can be greater than 50%. In order to better understand the liquid-flooded working process, a detailed scroll compressor model has been developed which comprises a geometric model and an overall compressor model. The geometric model includes numerically validated analytic solutions for all geometric parameters, including force terms, for constant wall thickness scroll wraps that can have multiple pairs of compression chambers. The overall model includes a frictionally-corrected isentropic nozzle leakage model, adaptive Runge-Kutta solver for the system of differential equations, and numerically efficient thermodynamic and transport property routines. The compressor model has been validated against testing conducted on the Liquid-Flooded Ericsson Cycle for oil mass fractions as high as 92% oil by mass with error in predictions of shaft power and mass flow less than 3%. Optimization of the compressor performance with flooding for several applications is carried out, and with optimization, overall isentropic efficiencies over 75% are predicted for configurations with large amounts of oil flooding. Further testing on a refrigerant R410A vapor injected compressor with oil injection has shown that the performance with oil injection improves monotonically with the oil injection rate as long as the oil is cooled prior to injection. [less ▲]

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See detailEpigenetic Therapy of Lung Cancers: Anti-tumoral effect of valproate on small cell lung cancer
Hubaux, Roland ULg

Doctoral thesis (2011)

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five ... [more ▼]

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five-year survival rate of less than 20 and 5 % for limited and extensive stage respectively. Based on increasing evidence that inhibitors of histones deacetylases (HDAC) have anticancer properties, the goal of this study was to evaluate the ability of valproate (VPA) to improve efficacy of chemotherapeutic regimen in SCLC. We show that VPA directly induces apoptosis of SCLC cell lines at concentrations relevant for clinical uses. Furthermore, VPA synergizes with two chemotherapeutic regimen used in first (cisplatin + etoposide) and second line (cyclophosphamid + vindesine + doxorubicin) treatments. Both mitochondrial and death receptor pathways are involved in VPA-induced apoptosis. Although VPA promotes production of reactive oxygen species, free radical scavenger N-acetylcystein is not sufficient to inhibit apoptosis. As expected, VPA triggers hyperacetylation of histone H3 and increases expression of p21. VPA reduces levels of BclxL, induces cleavage of Bid, translocation of Bax to mitochondria, release of cytochrome c into cytosol and phosphorylation of Erk and H2AX. Transcriptomic analyses by microarrays and quantitative RT-PCR have underscored a series of genes candidates potentially implicated into sensitivity of SCLC to VPA. Among these, the Fzd7 receptor of the WNT pathway is essential for VPA proapoptotic activity. Efficiency of VPA combined to first and second line chemotherapeutic agents is supported by preclinical models of SCLC cells engrafted into SCID mice. The second line combination is presently tested in a clinical trial with patients presenting with refractory or relapsing small cell lung cancer (protocol 01081 at http://www.elcwp.org). [less ▲]

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See detailOptimally Locating Facilities with Variable Characteristics
Kucukaydin, Hande ULg

Doctoral thesis (2011)

Facility location problems aim at optimally locating facilities like plants, warehouses, convenience stores, shopping malls etc. They can have different objectives such as maximizing the profit gained ... [more ▼]

Facility location problems aim at optimally locating facilities like plants, warehouses, convenience stores, shopping malls etc. They can have different objectives such as maximizing the profit gained from the customers or minimizing the costs of locating facilities and serving the customers. In this thesis, we mainly focus on competitive facility location problems which constitute a special family. In a competitive facility location problem, a firm or franchise is concerned with installing new facilities to serve customers in a market where existing facilities with known locations and attractiveness levels compete for increasing their market share and profit. We can classify these problems into two groups: those with non-reactive competition and those with reactive competition. Three different types of competitive facility location models are proposed in order to determine the locations and attractiveness levels of the new facilities to maximize the profit in this thesis. The first one belongs to the former class, where the last two models fall into the latter one. We formulate the first one as a mixed-integer nonlinear programming problem and propose three methods for its solution: a Lagrangean heuristic, a branch-and-bound method with Lagrangean relaxation, and a branch-and-bound method with nonlinear programming relaxation. The computational results obtained on a set of problem instances show that the branch-and-bound method using nonlinear programming relaxation is the most efficient and accurate solution method in order to solve the proposed problem. We consider next an extension of this model by relaxing the assumption that the competitor in the market does not react to the opening of new facilities. In other words, the competitor can react by adjusting the attractiveness levels of its existing facilities with the objective of maximizing its own profit. To this end, a bilevel mixed-integer nonlinear programming model is formulated. We transform this bilevel model into an equivalent one-level mixed-integer nonlinear program and solve it by a global optimization method. For this problem, we also consider a scenario in which the new entrant firm ignores the reaction of the competitor. The experimental results indicate that anticipating the competitor's reaction by including this into his optimization problem increases the profit of the new entrant firm, whereas the competitor's profit is decreased. The last competitive facility location model relaxes the limitation about the competitor's reaction: now the competitor can also open new facilities, close existing ones and/or adjust their attractiveness. This also formulates a bilevel mixed-integer nonlinear programming problem which we try to solve by combining tabu search with global optimization algorithms. We develop three different tabu search methods and the computational results on a set of problem instances for comparing the performance of the solution methods show that the third tabu search method is the most accurate one, while the second tabu search method is the most efficient solution procedure. Finally, we consider a different facility location problem which takes the customer preferences into account. The facilities are not necessarily identical and customers visit different types of facilities according to some given probability distribution and the maximum distance which they are willing to travel. We formulate a binary linear programming problem and solve it by three procedures that include a Lagrangean heuristic whose solution is improved further using a local search method. Based on the experimental results carried out on a set of problem instances the third solution method is the most efficient one. However, a statistical analysis on the quality of the solutions states that there is no significant difference between the three solution procedures. [less ▲]

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See detailDéfinition du régulon DasR chez Streptomyces coelicolor, un réservoir pour la découverte de nouveaux gènes essentiels à l'induction de la différenciation morphologique et la production de métabolites secondaires
Colson, Séverine ULg

Doctoral thesis (2011)

Ce travail vise à comprendre les mécanismes d’induction du développement chez les Streptomyces. Chez ce genre bactérien, le facteur de transcription DasR a été identifié comme le premier régulateur global ... [more ▼]

Ce travail vise à comprendre les mécanismes d’induction du développement chez les Streptomyces. Chez ce genre bactérien, le facteur de transcription DasR a été identifié comme le premier régulateur global à la charnière entre le métabolisme primaire et le métabolisme secondaire, capable de percevoir l'état nutritionnel de l'environnement et d'adapter en conséquence la réponse des différents processus associés au développement (Rigali et al., 2006 et Rigali et al., 2008). La première ambition de cette thèse de doctorat a été d'évaluer l'ampleur du régulon DasR chez S. coelicolor afin d'obtenir une liste - exhaustive et appuyée par des critère de fiabilité - des gènes ciblés par ce régulateur global. L'hypothèse à la base de ce travail de prédiction était qu'au sein du régulon DasR se trouvaient peut-être des gènes de fonction encore inconnue mais essentiels au développement. Comprendre le rôle de ces protéines pouvait déboucher sur l'élucidation de nouvelles voies d'induction du développement et donc peut-être de nouvelles voies à exploiter pour induire le réveil des gènes cryptiques. La première démarche visant à répondre à ce premier objectif nous a amené à constater les lacunes des programmes web de prédiction des régulons existant, notamment le manque de flexibilité au niveau des critères de recherche et au niveau de l'exploitation des résultats obtenus, ainsi que l'absence de moyen permettant d'estimer la fiabilité de la prédiction. C'est pourquoi, dans un premier temps, nous nous sommes lancés le défi de créer un nouvel outil de prédiction des régulons procaryotiques qui répondrait davantage aux attentes des biologistes. Ce programme, nommé PREDetector (Prokaryotic Regulatory Elements Detector), a été réalisé en collaboration avec le Professeur Louis Wehenkel (Department of Electrical Engineering and Computer Science, Université de Liège) (Hiard et al., 2007). Les caractéristiques et les possibilités offertes par PREDetector sont expliquées et illustrées dans le premier chapitre des résultats. Le second chapitre des résultats - ainsi que l'annexe de cette thèse - sont quant à eux dédiés à l'exploitation de ce programme et la caractérisation de l'ensemble des cibles de DasR prédites chez S. coelicolor. Ensuite, et toujours motivé par un souci de présenter un travail fiable pour d'ultérieures investigations, une comparaison des régulons DasR prédits chez différents streptomycètes et autres actinomycètes (prédictions et démarches détaillées dans l'annexe de thèse), vient appuyer notre définition du noyau dur du régulon DasR - conservon DasR - déduit pour l'organisme modèle S. coelicolor. Enfin, nous passons à l'étape d'utilisation de ces données bioinformatiques avec l'étude de gènes/protéines dont l'expression est dépendante de DasR dans le but de peut-être établir de nouvelles connexions entre le métabolisme primaire et le développement chez la souche modèle S. coelicolor. De manière intéressante, le régulon DasR de S. coelicolor comprend plusieurs gènes codant pour des systèmes de transport ABC de sucre. A l'instar du PTSGlcNAc, ces transporteurs situés à l'interface cellule/environnement peuvent aussi être les senseurs de molécules cruciales pour l'induction du développement. Après le PTSGlcNAc, nous nous sommes donc concentrés sur l'étude du premier transporteur ABC de sucre régulé par DasR - en termes de fiabilité des prédictions et de conservation inter-espèces/-genres -, c'est-à-dire, le système DasABC. Dans le troisième chapitre des résultats nous démontrerons ainsi que DasA est une protéine impliquée dans le processus de différenciation morphologique de S. coelicolor (Colson et al., 2008). [less ▲]

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See detailVERS UNE EXPERTISE HYBRIDE AU SERVICE DU DROIT: LE CAS DES ALIMENTS FONCTIONNELS ET DU DOMMAGE ECOLOGIQUE
Kouembeu Tagne, Jean Jacques ULg

Doctoral thesis (2011)

L’apparition récurrente de phénomènes nouveaux et incertains dans le domaine de l’environnement bouscule de façon permanente les cadres de références législatives et interpelle quant à la place, le rôle ... [more ▼]

L’apparition récurrente de phénomènes nouveaux et incertains dans le domaine de l’environnement bouscule de façon permanente les cadres de références législatives et interpelle quant à la place, le rôle et à l’apport des prétendants à l’expertise. Au sens de la Cour de cassation belge, (Cass 15.02.2006, numéro RC 062F2_7, numéro de rôle P051583F) l’expert judiciaire est un auxiliaire de justice. Il n’est ni mandataire, ni préposé des parties. Il assiste le juge, sans empiéter sur la fonction de juger qui est confiée à ce dernier. L’expert est alors appelé à traduire des preuves scientifiques en preuves factuelles destinées à des profanes de sa discipline que sont les juges. Dans ce cas de figure, l’expertise participe de la bonne organisation judiciaire, assure une base de connaissance solide à l’élaboration des décisions judiciaires et se présente comme un partenaire qui pénètre dans le cœur du droit. L’expertise est considérée de la même manière quand dans les processus législatifs elle s’adresse à des parlementaires ou quand elle est convoquée par des politiques voire par le public. Considérée sous cet angle, l’expertise se présente comme un savoir limité aux faits, et non une connaissance discutable, en train de se construire. Cette thèse examine comment, dans des domaines complexes caractérisés par l’incertitude, le savoir objectif n’existe que comme construction. L’expertise n’est plus spécifique à une branche, elle est hétérogène, elle est hybride. Plus fondamentalement, cette expertise est appelée à articuler et à intégrer plusieurs objectivités à la fois, qu’elles soient scientifiques, socio-économiques, sanitaires ou politiques. Cette thèse montre à partir des cas de la réglementation sur les aliments fonctionnels d’une part et celui du dommage écologique d’autre part, comment les cadres juridiques sont investis par des scientifiques, des publics, des juristes, des associations, des politiques, des industriels, etc., et comment ceux-ci contribuent en retour à la modification de ces cadres. Si le droit se singularise par son devoir de qualification, c’est-à-dire, celui qui lui permet d’établir une distance avec les autres disciplines, avec le monde extérieur, la complexité des phénomènes environnementaux invite aujourd’hui à aller au-delà des cloisonnements du raisonnement juridique. En ce sens, cette thèse vise à éclairer la question essentielle suivante : comment le droit peut-il intégrer plusieurs objectivités dans un processus d’élaboration de la norme environnementale ? [less ▲]

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See detailContribution to the study of semiochemical slow-release formulations as biological control devices
Heuskin, Stéphanie ULg

Doctoral thesis (2011)

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present thesis ... [more ▼]

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present thesis, two sesquiterpenoids, E-β-farnesene and E-β-caryophyllene, were formulated for their related properties as aphid enemy attractants. E-β-farnesene, the alarm pheromone of many aphid species, was also identified as a kairomone by attracting and inducing oviposition of aphid predators (Episyrphus balteatus De Geer (Diptera: Syrphidae)) and by attracting aphid parasitoids (Aphidius ervi Haliday (Hymenoptera: Braconidae)). E-β-caryophyllene was identified as a potential component of the aggregation pheromone of the Asian ladybird, Harmonia axyridis Pallas, another aphid predator. The two products were purified from essential oils of Matricaria chamomilla L. (Asteraceae) and Nepeta cataria L. (Lamiaceae) for E-β-farnesene and E-β-caryophyllene, respectively. Natural and biodegradable slow-release formulations were then investigated in order to deliver these molecules on crop fields for a long period of time as biological control devices. Due to their sensitivity to oxidation, both sesquiterpenes needed to be protected from oxygen degradation. For this purpose, alginate – hydrophilic matrix with low oxygen permeability – was used as polymer for the formulations: the main objective was to deliver semiochemical substances in the air in a controlled way. Consequently, a careful selection of alginates was realised. Formulated beads showed different structural and encapsulation properties depending on various formulation factors. Alginate formulations were characterized by texturometry and by confocal microscopy in order to observe the distribution of semiochemicals in alginate network. The last step of alginate bead characterisation consisted in studying release rate of semiochemicals in laboratory-controlled conditions by optimised trapping and validated Fast-GC procedures. Finally, the efficiency of formulations as aphid predator (Syrphidae) and parasitoids (A. ervi) attractants was demonstrated by field trapping and olfactometry experiments. [less ▲]

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See detailLa qualité de vie dans la maladie d'Alzheimer et les syndromes apparentés
Missotten, Pierre ULg

Doctoral thesis (2011)

La question de la qualité de vie dans la démence, envisagée par rapport au patient, constitue l’objet d’étude de ce travail de thèse. Plus précisément, la première partie théorique du présent travail fait ... [more ▼]

La question de la qualité de vie dans la démence, envisagée par rapport au patient, constitue l’objet d’étude de ce travail de thèse. Plus précisément, la première partie théorique du présent travail fait le point sur les connaissances actuelles dans la littérature sur la qualité de vie. Cette dernière est appréhendée sous la double perspective conceptuelle et méthodologique. L’état des lieux dans la démence constitue, pour chacune des différentes caractéristiques conceptuelles et méthodologiques envisagées, le dernier élément qui est aussi le plus détaillé. Il est précédé d’un point centré sur la littérature gérontologique qui, lui-même, est devancé par une petite recherche focalisée sur la littérature « générale » (essentiellement issue de la littérature centrée sur des populations adultes). En ce sens, le développement de chaque caractéristique, tant conceptuelle que méthodologique, se fait donc en trois temps : général, gérontologie et démence. Ces trois phases témoignent d’une présentation allant dans le sens du général au spécifique et du moins développé au plus développé. Pour clôturer la première partie théorique, un recensement des outils de qualité de vie (instruments et méthodes d’observation directe) est présenté. En accord avec ce qui vient d’être énoncé pour les caractéristiques conceptuelles et méthodologiques, ce développement des outils est surtout détaillé pour la démence. Ensuite, les objectifs du travail de thèse sont développés pour commencer la partie expérimentale. Ils sont suivis par la présentation des quatre articles scientifiques. Ceux-ci sont centrés sur l’étude transversale et longitudinale (follow-up de 2 ans) de la qualité de vie et des principaux paramètres sociodémographiques (âge, sexe, lieu de résidence) et cliniques (fonctionnement cognitif, dépendance, troubles psychologiques et comportementaux, stade évolutif) de patients déments situés à tous les stades de l’évolution démentielle. De manière générale, les résultats démontrent que les patients déments sont capables de maintenir un niveau de qualité de vie acceptable. Cette constatation a notamment été établie sur base de la comparaison de la qualité de vie de ces patients avec celle de patients présentant des troubles cognitifs légers ainsi que des personnes âgées « contrôles ». Le niveau de qualité de vie des sujets déments est influencé par les variables cliniques dont l’impact a tendance à augmenter avec le temps. Toutefois, une part importante de la variance reste non expliquée, ce qui démontre l’influence d’autres variables. Enfin, le profil de qualité de vie en fonction du lieu de résidence et du fonctionnement cognitif montre des périodes de stabilisation et de détérioration. Cette observation permet 1) d’affiner la question du lien entre qualité de vie et paramètres cliniques ; 2) de démontrer l’absence de diminution strictement linéaire de la qualité de vie en fonction de l’état cognitif ; 3) de questionner le postulat d’une qualité de vie nécessairement meilleure au domicile par rapport à l’institution. Suite à la présentation de ces articles, le présent travail se centre sur une discussion générale. Celle-ci débute par une synthèse intégrée des résultats dégagés au sein des quatre articles. Elle se poursuit par le dégagement des principaux points conceptuels et méthodologiques avant de se terminer par une réflexion clinique et scientifique basée sur les résultats des articles et les principaux points théoriques abordés. Aussi, la présence d’un niveau de qualité de vie non catastrophique pour les patients déments est mis en parallèle avec les notions de buts et de priorités retrouvées dans la prise en charge actuelle des patients déments mais également avec les concepts de personnalité et de citoyenneté ainsi qu’avec les théories du vieillissement réussi et les stratégies d’adaptation. Enfin, ce travail se clôture par une conclusion générale. [less ▲]

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See detailFluorine in the atmosphere: Inorganic fluorine budget and long-term trends based on FTIR measurements at Jungfraujoch
Duchatelet, Pierre ULg

Doctoral thesis (2011)

High resolution solar spectra are routinely recorded since more than two decades by the University of Liège at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580 m ... [more ▼]

High resolution solar spectra are routinely recorded since more than two decades by the University of Liège at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580 m asl) with Fourier Transform Infrared (FTIR) spectrometers. Over the last years, major improvements have been implemented in the algorithms used to retrieve the abundances of atmospheric constituents accessible to the FTIR technique. Now, in addition to total column, information on the vertical distribution of the target gas is often available, allowing producing partial column data sets. We take advantage of these improvements to generate and characterize long-term total and partial columns time series of some important inorganic fluorinated trace gases deduced from FTIR measurements performed at Jungfraujoch. First, our investigations on hydrogen fluoride (HF) indicate that the adoption of a Galatry line shape model for this species significantly improves the fitting quality of the retrievals. The sensitivity of our FTIR measurements to HF inversions in three distinct regions that range from the low to the high stratosphere is confirmed thanks to products derived from two satellites and from two numerical models. We further demonstrate that the HF seasonal variations that occur in the low stratosphere are mainly responsible for the seasonal cycle observed in our HF total column time series. We have also developed an original multi-spectrum multi-window retrieval strategy allowing to derive, for the first time, some information on the vertical distribution of carbonyl fluoride (COF2) from ground-based FTIR measurements. After comparison with model data, our COF2 and HF FTIR datasets are combined to assess the atmospheric inorganic fluorine burden Fy. A trend analysis of our HF, COF2 and Fy time series is then performed for four different time periods spanning the 1985-2010 time interval. While we observe a recent stabilization for HF, corresponding COF2 data show a significant rise, after a period of significant reduction in its accumulation rate. This is probably ascribable to the combination of the decrease of its main source gas CFC-12 with the increase of the substitute product HCFC-22. However, this increase in the COF2 rate of change does not significantly impact the Fy trend, which is essentially driven by the change in HF. In addition, we show that the partitioning between the two major fluorine reservoirs HF and COF2 has not changed since the beginning of this century. Together, they account for around 95% of total inorganic fluorine in the atmosphere. Finally, we study the long-term evolution of carbon tetrafluoride (CF4), for the first time from ground-based FTIR measurements. The trend analysis of our time series indicates a slowing, initiated during the nineties, in the CF4 growth rate despite the fact that the absolute loading of this compound is still increasing. Our linear accumulation rates are consistent with those deduced from space or surface measurements. [less ▲]

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See detailEtude de l’évolution de l’état de surface de matériaux optiques sous bombardement ionique à faible énergie
Gailly, Patrick ULg

Doctoral thesis (2011)

In this work the roughness and topography evolution of optical materials sputtered with low energy ion beam (≤1 keV) has been investigated. These materials (bulk or thin layer) are used in the ... [more ▼]

In this work the roughness and topography evolution of optical materials sputtered with low energy ion beam (≤1 keV) has been investigated. These materials (bulk or thin layer) are used in the manufacturing of mirrors for scientific (ground or space) instruments or for other optical applications. In the first part of the work, the roughness evolution of optical surfaces under sputtering has been investigated in the frame of the industrial process known as Ion Beam Figuring. This technique consists in removing shape errors on optical surfaces with a low energy ion beam (≤1 keV). One disadvantage of this process is a potential increase of roughness for surfaces under treatment. The roughness evolution of some materials relevant to the optical industry has been accurately characterized as function of etching depth down to 5 µm. These sputtering experiments have been carried out at normal incidence, mainly with argon ions (but also in a lesser extent with krypton and xenon ions), ion current density of ~1 mA/cm2 and ion beam energy ranging from 200 eV to 1000 eV. The roughness evolution under sputtering is low for materials with amorphous (glass, electroless nickel), monocrystalline (silicon) or even polycrystalline structure (CVD silicon carbide, PVD gold or nickel film), whereas it is considerably more important for some other metallic materials such as electroplated nickel and aluminium. This work has shown small differences in the roughness evolution of CVD silicon carbide as function of the ion beam energy. The roughness increase is faster at low ion energy (<500 eV) than at higher ion energy (650-1000 eV). The grain structure of this material is less revealed at higher energy, which is supposed to be due to a larger amorphization of the sputtered layer in this case. The influence of the ion mass on CVD silicon carbide and gold films on nickel substrates has been also illustrated. Our measurements have been also compared to scaling laws. Various growth and roughness exponents have been found, sometimes rather different from those foreseen by the KPZ equation. In the second part, we focus on periodically modulated structures (ripples) which developed on many solids when sputtered by an off-normal ion bombardment. In this work, we first observed these ripples on gold films deposited on electroplated nickel (materials used as reflective surfaces for X-ray space telescope) sputtered at grazing incidence. We studied the influence of sputtering parameters (ion beam incidence angle, energy and flux) on the characteristics of ripples induced on gold and silver thin film (~0.2 µm). Ion-induced ripples have also been observed on CdS, an interesting semiconductor crystal for optical applications. The ripples orientation and dimensions (spatial wavelengths from 0.13 µm to 0.29 µm) have been confronted to the Bradley-Harper (B-H) linear model. We used the SRIM software to evaluate the deposited energy and the surface tension coefficient distributions. Our results can be in great part explained by the current theories (Bradley-Harper, Makeev) on morphology of ion-sputtered surfaces. These results can be summarized hereunder: • Clear development of ripples for angle of incidence equal or higher than 60° on gold film and 70° on silver film. • In this work the ripples wave vector is always perpendicular to the ion beam direction for all angles, whereas the change in ripple orientation beyond a critical angle is usually reported in literature. This is a due to the different shape of the energy distribution function for our sputtering conditions. • Different regimes for roughness and topography evolution (grains, ripples) have been observed in function of the angle of incidence. 3 different areas can be distinguished, as predicted by Makeev non-linear model. • The diminution of ripple wavelength with ion energy shows that thermal diffusion is the main relaxation mechanism. [less ▲]

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See detail'D’abord sa manière étoit gottique'. L'œuvre peint de Bernard van Orley jusqu'au début des années 1520
Galand, Alexandre ULg

Doctoral thesis (2011)

Les années 1510 et 1520 apparaissent comme un moment crucial pour l’introduction de la Renaissance dans les anciens Pays-Bas. Or, cette période coïncide avec la première période d’activité de Bernard van ... [more ▼]

Les années 1510 et 1520 apparaissent comme un moment crucial pour l’introduction de la Renaissance dans les anciens Pays-Bas. Or, cette période coïncide avec la première période d’activité de Bernard van Orley, un témoin majeur de cette époque de transition. Jusqu’à présent, la recherche a surtout envisagé l’artiste par le prisme de ses magnifiques tapisseries. De la fin de la première décennie du 16e siècle à 1521 où il signe le monumental Polyptyque de Job et de Lazare (Bruxelles, MRBAB/KMSKB, Inv. 1822), l’artiste a pourtant élaboré un œuvre peint de plus en plus perméable aux formes en provenance de la péninsule italienne. Ce changement de perspective a-t-il entraîné des différences importantes en termes de pratiques d’atelier ? Comment peuvent être caractérisées de manière précise les œuvres constituant le noyau dur d’un catalogue aux frontières mouvantes ? En quoi les documents d’archives peuvent-ils donner un nouvel éclairage sur l’activité de l’artiste ? Ces questions sont au centre d’un travail qui se donne pour ambition de renouveler la vision de la peinture de Bernard van Orley, domaine jusqu’à aujourd’hui négligé. [less ▲]

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See detailEtude expérimentale de la cristallochimie et de la stabilité des phosphates à structure fillowite
Rondeux, Mélanie ULg

Doctoral thesis (2011)

Les minéraux du groupe de la fillowite sont des phosphates sodiques de manganèse, de fer, de magnésium et de calcium. On rencontre ces phosphates essentiellement dans les pegmatites granitiques, en ... [more ▼]

Les minéraux du groupe de la fillowite sont des phosphates sodiques de manganèse, de fer, de magnésium et de calcium. On rencontre ces phosphates essentiellement dans les pegmatites granitiques, en contextes métamorphiques, mais aussi dans certaines météorites. A l’heure actuelle, on compte cinq minéraux appartenant à ce groupe ; la fillowite sensu stricto [Na2CaMn7(PO4)6], la chladniite [Na2CaMg7(PO4)6], la galileiite [Na2Fe2+8(PO4)6], la johnsomervilleite [Na2CaFe2+7(PO4)6] et la stornesite-(Y) [(Y,Ca)□2Na6(Ca,Na)8(Mg,Fe)43(PO4)36]. Ces minéraux cristallisent dans le système rhomboédrique (groupe spatial R ) et présentent une maille cristalline de très grande taille (a = 15,28 Å, c = 43,51 Å, Z = 18) contenant 756 atomes dont 45 sont non équivalents. Le premier but de ce travail a été d’obtenir de nouvelles données sur la cristallochimie des minéraux du groupe de la fillowite, et de déterminer les limites d’incorporation de différents cations dans cette structure. La synthèse par voie sèche a été utilisée, à diverses températures (entre 650 et 970°C), lors des essais d’insertion des cations monovalents (Li+, Ag+ et K+), des cations bivalents (Mg2+, Fe2+, Zn2+, Ni2+, Ca2+ et Cd2+) et des cations trivalents (Fe3+, Al3+, Y3+, Cr3+ et Sc3+). Les cations monovalents sont toujours présents dans les minéraux du groupe de la fillowite. Nos résultats confirment cette observation et indiquent que, à l’exception de Ag+ qui peut totalement se substituer à Na+, les autres cations monovalents (Li+ et K+) ne rentrent que très difficilement dans la structure fillowite. Concernant les cations bivalents, les résultats de nos recherches montrent que c’est le manganèse qui s’incorpore le plus facilement dans la structure fillowite. En effet, la synthèse des phosphates de compositions Na2Mn8(PO4)6 ou encore Na2CaMn7(PO4)6, isotypes à la fillowite, est très commode. De plus, les analyses chimiques à la microsonde électronique des fillowites, obtenues par voie hydrothermale dans les systèmes Na-Mn-Fe2+-Mg-(PO4) et Na-Ca-Mn-Fe2+-Mg-(PO4), se localisent essentiellement dans la partie riche en Mn des diagrammes Mn-Fe-Mg. Nous avons également prouvé expérimentalement que d’autres cations bivalents comme le magnésium, le calcium et le cadmium peuvent également s’y introduire assez aisément, à l’opposé du zinc et du nickel qui forment préférentiellement des phases orthorhombiques ou de l’alluaudite. Finalement nos données montrent que le fer ferreux se substitue au manganèse, jusqu’à la composition Na2,244(Fe2+3,791Mn3,172Fe3+0,610)(PO4)6 obtenue à 600°C / 1 kbar. La structure fillowite ne semble pas affectionner les cations trivalents. Nos données corroborent cette observation car il est plus aisé d’insérer des cations bivalents que des cations trivalents, à l’exception de Sc. En effet, le scandium, dont le rayon ionique est le plus proche de celui de Mg2+, s’incorpore bien dans la structure fillowite. L’insertion de Al3+ dans cette structure se révèle également assez facile, comme en témoigne la détection de composés à structure fillowite obtenus sans impuretés dans les échantillons de compositions de départ : Na2(Mn7,4Al0,4)(PO4)6 et Na2Ca(Mn6,25Al0,5)(PO4)6. Enfin, ce sont Fe3+, Cr3+ et Y3+ qui entrent le plus difficilement dans cette structure. La substitution de Mn2+ par Fe3+ ou Cr3+ dans les systèmes étudiés en voie sèche induit immédiatement l’apparition de composés à structure alluaudite en association avec les phosphates à structure fillowite. Des analyses chimiques à la microsonde électronique indiquent toutefois que Fe3+ s’incorpore en faible teneur dans la structure fillowite. Le second objectif de ce travail a été d’appliquer les techniques de synthèse hydrothermale afin de mieux cerner la stabilité des minéraux du groupe de la fillowite. Dans ce but, les systèmes Na-Mn-Fe2+-Mg-(PO4) et Na-Ca-Mn-Fe2+-Mg-(PO4) ont été investigués, à des températures comprises entre 400 et 700°C (1 kbar). Des phosphates à structure fillowite sont formés, sans impureté, à toutes les températures étudiées, à partir des mélanges initiaux dépourvus de fer. L’incorporation du fer implique immédiatement l’apparition d’alluaudite et de sarcopside, alors que la marićite cristallise comme phase supplémentaire pour les compositions très riches en fer. Le contenu de ce dernier dans les composés à structure fillowite augmente entre 400 et 600°C, puis diminue légèrement entre 600 et 700°C (1 kbar). La composition de ces phosphates, obtenus à 600°C / 1 kbar, est très proche de celles des johnsomervilleites naturelles de Loch Quoich (Ecosse) et de Kiluli (Rwanda) indiquant que ceux-ci auraient pu se former dans des conditions similaires. Pour le mélange initial Na2Fe2+8(PO4)6, les phosphates à structure fillowite sont absents à 1 kbar, alors qu’ils apparaissent timidement lors des synthèses réalisées à 3 kbar. Ces résultats démontrent le rôle essentiel joué par la pression sur l’incorporation du fer dans la structure fillowite. [less ▲]

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See detailParameter identification for biological models
Fey, Dirk ULg

Doctoral thesis (2011)

This thesis concerns the identification of dynamic models in systems biology. and is structured into two parts. Both parts concern building dynamic models from observed data, but are quite different in ... [more ▼]

This thesis concerns the identification of dynamic models in systems biology. and is structured into two parts. Both parts concern building dynamic models from observed data, but are quite different in perspective, rationale and mathematics. The first part considers the development of novel identification techniques that are particularly tailored to (molecular) biology and considers two approaches. The first approach reformulates the parameter estimation problem as a feasibility problem. This reformulation allows the invalidation of models by analysing entire parameter regions. The second approach utilises nonlinear observers and a transformation of the model equations into parameter free coordinates. The parameter free coordinates allow the design of a globally convergent observer, which in turn estimates the parameter values, and further, allows to identify modelling errors or unknown inputs/influences. Both approaches are bottom up approaches that require a mechanistic understanding of the underlying processes (in terms of a biochemical reaction network) leading to complex nonlinear models. The second part is an example of what can be done with classical, well developed tools from systems identification when applied to hitherto unattended problems.In particular, part two of my thesis develops a modelling framework for rat movements in an experimental setup that it widely used to study learning and memory.The approach is a top down approach that is data driven resulting in simple linear models. [less ▲]

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See detailDes guerres en Italie avant les Guerres d'Italie. Les entreprises militaires françaises dans la Péninsule à l'époque du Grand Schisme d'Occident
Masson, Christophe ULg

Doctoral thesis (2011)

Si la guerre de Cent Ans stricto sensu, est depuis des années l'objet de recherches de tout premier plan, la question des expéditions françaises en Italie à l'époque du Grand Schisme d'Occident était ... [more ▼]

Si la guerre de Cent Ans stricto sensu, est depuis des années l'objet de recherches de tout premier plan, la question des expéditions françaises en Italie à l'époque du Grand Schisme d'Occident était restée vierge de toute étude de synthèse, à tout le moins sur le plan qui semble pourtant le plus évident, celui de la guerre, et ce alors même que les implications politiques de ces mêmes guerres italiennes sont étudiées depuis aujourd'hui plus d'un siècle. Au croisement des sources – sources narratives et documents d'archives se sont révélés être le socle sur lequel s'est progressivement construite notre synthèse puisqu'au caractère lacunaire des premières en terme de fiabilité ou de chronologie a fait pièce la précision des secondes qui trouvaient pour leur part dans la confrontation avec les chroniques les éléments de nature à enrayer l'aridité des relevés financiers – fait écho celui des approches, que nous avons souhaitées multiples, de notre sujet d'études. Pour appréhender le fait militaire, nous avons privilégié une vision globalisante, eu égard au fait que, à nos yeux, l'armée représentait un tout qui se doit d'être étudié de la sorte. Les divers éléments qui la composent étant interdépendants, on ne peut connaître l'un sans envisager l'autre. Il ressort de cette approche plurielle plusieurs observations. Alors que l'Europe se cliche au gré des intérêts politiques et spirituels en obédiences rivales, l'on aurait pu s'attendre à ce que des princes français, traditionnellement favorables à la papauté d'Avignon, deviennent les champions des prélats des bords du Rhône. Or, il n'en fut rien. Ce qui intéressa au premier chef les ducs d'Anjou fut non de déposer celui qu'il tenait pour un usurpateur et d'établir le successeur de saint Pierre pour lequel ils avaient opté sur le trône de Rome mais de profiter des ressources financières de la papauté, considérées alors, avec le trésor du roi de France, comme les plus massives de l'Occident. De la même façon, les ressources du duc d'Orléans et celles du roi de France furent, en toute logique, très largement sollicitées par les lieutenants de ceux-ci. Mais, à cette occasion encore, on constate une indépendance certaine des bénéficiaires vis-à-vis de leurs bailleurs de fonds. La mission qui leur est confiée offre un cadre relativement lâche à leurs actions, cadre qui, joint à l'éloignement géographique, facilite l'exercice d'un pouvoir des capitaines ouvertement personnel. Les actions menées en Italie se trouvent tout à fait différer des usages en cours lors de la guerre qui opposait la France à l'Angleterre. Depuis Charles V, en effet, les armées françaises s'étaient vues ordonner l'abandon de la charge de cavalerie au profit d'options tactiques mieux à même de contrer une infanterie adverse qui s'était signalée lors des sanglantes batailles de Crécy et de Poitiers. En Italie, au contraire, si les compagnies fleurdelysées ressemblaient par la taille à leurs homologues cisalpines, leur aspect les en faisait parfaitement différer. La prééminence est à nouveau le fait d'hommes d'armes montés. Le basculement est donc complet et rapide de la part de guerriers qui s'adaptent d'autant plus rapidement à leur nouvel ennemi que celui-ci se révèle être un fervent adepte du choc frontal, du moins lorsqu'il accepte le combat. C'est d'ailleurs un trait marquant des opérations françaises que de n'avoir que rarement produit de grandes batailles. Au vrai, les Italiens s'efforçaient le plus souvent d'éviter tout affrontement d'importance afin de tirer profit de leur établissement dans le royaume de Naples ou dans la République de Gênes. Partant, les Français organiseront leurs campagnes autour d'un objectif prioritaire, la soumission de la capitale adverse et auront donc recours à des moyens moins typiquement « chevaleresques » pour assurer le triomphe de leur cause. Si Louis Ier d'Anjou n'a visiblement pu compter que sur une faible artillerie, ceux qui, à sa suite, prirent le chemin de l'Italie ne semblent pas avoir négligé cette composante de plus en plus importante de l'art de la guerre. D'autres moyens pour emporter des places fortes furent mis en œuvre, qui tous s'éloignaient un peu plus de la morale traditionnellement défendue par cette classe sociale particulière qu'était la chevalerie. Or, ces pratiques étaient loin d'être étrangères aux capitaines royaux et ducaux. L'idée de l'honorable et pur chevalier parangon de vertu confronté à des réalités italiennes qu'il ne peut comprendre car trop ignobles ne résiste pas à l'examen attentif des faits. Les armées médiévales – de terre ou de mer – tiraient évidemment leur puissance de leur importance numérique. Par suite, ce sont les chefs de guerre à la tête des plus nombreuses compagnies qui reçurent le commandement de l'ensemble des troupes. Le recrutement en cascade – les fidèles d'un seigneur conduisant à leurs côtés certains de leurs fidèles et ainsi de suite – explique que, contrairement, une fois encore, à ce que l'on aurait pu croire, le service d'Italie ne s'est pas révélé un accélérateur de carrière chez les gens d'armes. Leur présence dépendait plus de liens personnels les unissant à un chef de guerre que de relations de service ou de vassalité les attachant au souverain commanditaire de l'entreprise. Nulle surprise donc à ce que ce dernier ne juge pas nécessaire de les récompenser à la fin de leur mission. Au contraire, ce sont les techniciens, gens de finances et de lettres, qui bénéficièrent de promotions à leur retour d'Italie. La guerre dans la Péninsule n'était qu'une étape de plus dans la carrière d'un homme d'armes alors qu'elle prouvait les capacités des « petites mains » de l'armée à affronter des situations auxquelles l'on ne pouvait se préparer. Si la délégation de pouvoir est importante, il n'en reste pas moins que l'on assiste tout au long de ces campagnes à la négation de la personnalité du capitaine dans le domaine pourtant si important des symboles politiques. L'armée demeure ainsi un instrument de pouvoir aux mains du souverain. Au-delà de l'aspect spécifiquement politico-militaire, elle exprime l'excellence de ce dernier, qu'il s'agisse des ducs d'Anjou et d'Orléans ou du roi de France, lequel prouve par le succès des armes et la qualité – sociale aussi bien qu'esthétique – de son armée la valeur et la justesse de ses prétentions. Au vrai, si c'est la noblesse qui, logiquement, compose les armées françaises et occupe les principales charges de gouvernement, elle est subjuguée par l'État qu'elle sert. Elle en retire un prestige certain mais renonce aussi, simultanément, à son indépendance. Ici encore, l'état moderne en construction se bâtit sur et grâce à une aristocratie relais des intérêts ducaux ou royaux. De la même façon, la présence de Français au sein de ces administrations locales trahit l'importance prise par les liens sociaux dans l'exercice du pouvoir et sa délégation. Ce sont leur proximité et leur amitié qui font des lieutenants du capitaine les officiers du roi. La fidélité personnelle intervient donc comme ciment d'un pouvoir étatique. La noblesse, bien qu'elle soit en Italie moins soumise au pouvoir royal en Italie qu'en France, constitue le véritable cœur de l'armée, tout comme cette dernière est le noyau de l'état princier que l'on développe outremonts grâce au cadre fourni par le modèle royal. 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See detailInnovative strategies for the control of apple scab (Venturia inaequalis [Cke.] Wint.) in organic apple production
Jamar, Laurent ULg

Doctoral thesis (2011)

The aim of this thesis, conducted over six growing seasons (2003-2008), is to define new measures for reducing the use of fungicides and in particular, copper fungicides, for the control of apple scab (V ... [more ▼]

The aim of this thesis, conducted over six growing seasons (2003-2008), is to define new measures for reducing the use of fungicides and in particular, copper fungicides, for the control of apple scab (V. inaequalis) in organic apple production. Special emphasis is put on primary scab infection control during spring season. An original approach is proposed for defining a specific spray timing involving spraying during the infection processes, especially before fungal penetration, determined by the RIMpro software warning system. This ‘during-infection’ spray strategy allows reducing from 30 to 50% the amount of fungicide usually used for effective apple scab control, on high scab-susceptible cultivars. The field study shows that six alternative products (e.g., potassium bicarbonate and lime sulphur), among 60 products tested, have the potential to reduce copper use. However, copper use, even with low doses, seems to be still necessary in presence of scab-susceptible cultivars. The results obtained in these experiments could not be attributed to the specific technical performances of the tunnel sprayer used, which however, offer valuable environmental benefits. On the basis of the present study, the organic management system seems a good farming approach for maintaining soil quality with regard to biological indicators. This work shows and draws attention to the fact that (i) planting cultivars with polygenic scab-resistance traits, (ii) increasing emphasis on sanitation practices aimed at reducing initial inoculum in autumn, and (iii) applying an accurate spray strategy in spring, as defined in the present study, are the three most promising approaches for substantial further reductions in protection products fully compliant with international organic crop production standards. [less ▲]

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See detailOptimisation contrainte et non-contrainte par régions de confiance avec approximations locales quadratiques
Walmag, Jérôme ULg

Doctoral thesis (2011)

This work deals with optimisation problems in which the numerical cost associated with the evaluation of the target function and/or of the constraints is large; the number of calls to these functions by ... [more ▼]

This work deals with optimisation problems in which the numerical cost associated with the evaluation of the target function and/or of the constraints is large; the number of calls to these functions by the optimisation algorithm should therefore be kept as small as possible. The first part of the work is about globalisation by trust regions where the objective function and the constraints are replaced by a local approximation, easier to use, in a certain region of confidence. Different types of local approximations are introduced but the main part of the work deals with quadratic approximations. The theoretical aspects of the global convergence of trust regions methods are also presented. One of the applications considered in this work is the parametrical identification of a dynamical model with respect to experimental measurements. This identification can be expressed in the form of an unconstrained optimisation problem. For the practical implementation of the identification algorithm, the derivative of the objective function is required, which asks for the derivation of the underlying model. An algorithm, named Trust, has been implemented: it is a trust region method of quasi-Newton type which uses quadratic local approximations. The choice of the differentiation method is analysed in details in relation with its influence on the rate of convergence. A brand new update strategy of the trust region radius is also introduced. The trust region radius is a parameter that measures the size of the trust region around the current iterate. The new approach relies on the identification and appropriate handling of so-called “too successful iterations” that lead to a much more important reduction of the function objective than predicted by the local approximation. This approach goes with a significant improvement of the performances of the algorithm. Constrained optimisation is then considered using sequential quadratic methods. A fully effective algorithm for the resolution of quadratic convex sub-problems with quadratic constraints is introduced. This original method, named UVQCQP, makes use of an exact non-differentiable penalty function to addresses the constrained optimisation problem. The algorithm relies on a decomposition of the variable space into three orthogonal subspaces: a first subspace taking into account bound constraints, a second one in which the objective function is continuously derivable and a third one with slope discontinuities. The performances of this algorithm are further improved by the implementation of a fast mode taking into account the second order corrections. Eventually, the UVQCQP algorithm is applied within the framework of sequential algorithms of quadratic programming with quadratic constraints: its advantages are demonstrated through some examples. The numerical tests carried out reveal very encouraging prospects. [less ▲]

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See detailLa représentation documentaire des années de plomb allemandes (1970-1979): de la contrinformation au mélancolique
Hamers, Jérémy ULg

Doctoral thesis (2011)

Comment représenter un ensemble d’évènements affectés par leur inaccessibilité, la polarisation extrême du contexte qu’ils contribuent à mettre en place, et une censure à la fois morale et financière ... [more ▼]

Comment représenter un ensemble d’évènements affectés par leur inaccessibilité, la polarisation extrême du contexte qu’ils contribuent à mettre en place, et une censure à la fois morale et financière ? Telle était la question de départ de notre recherche doctorale, à laquelle nous avons soumis un corpus de films documentaires allemands traitant des événements de la crise terroriste des années septante, et réalisés entre 1970 et 1979. Un rappel chronologique de quelques évènements saillants des années de plomb allemandes nous a permis d’examiner d’abord les multiples liens et interactions entre terrorisme allemand et représentation. L’analyse de l’usage des médias par les terroristes et l’examen de quelques représentations produites par les médias, ont révélé un double lien symbiotique entre acte terroriste et discours médiatique : intrication de l’événement et de sa représentation en vertu de laquelle certaines images s’érigent d’abord en emblèmes des évènements avant de s’y substituer totalement ; chassé-croisé de représentations terroristes, étatiques et médiatiques, qui révèle que les productions audiovisuelles des terroristes et les représentations produites par l’Etat appartiennent en réalité à un seul et même grand réseau de représentations, sémantiquement violentes, dont les principaux moteurs sont la citation et le détournement ainsi que le remplissage de décors vides dans lesquels se sont déroulés des événements révolus. Cet état de fait compromet a priori toute approche documentaire indépendante des événements. La suite de notre étude a dès lors été consacrée à la recherche d’une forme documentaire qui serait en mesure d’échapper à ce grand réseau de représentations. Cette recherche a d’abord abouti à l’analyse de six documentaires – totalement ignorés par la littérature scientifique pour la plupart – issus d’écoles de cinéma et de groupes de vidéastes militants. Ces films ont été réunis au nom de leur capacité structurelle à échapper à la censure financière et morale de l’époque. L’analyse de ces œuvres nous a permis d’identifier quelques modes de représentation qui tous peuvent contribuer à l’élaboration d’un regard sur le réel, affranchi partiellement de l’irreprésentabilité de la crise terroriste et du réseau de représentations qu’elle contribue à mettre à place. Mais il est également apparu que ces œuvres reproduisent des logiques narratives et informationnelles héritées des médias, qui compromettent in fine l’existence d’un regard non polarisé sur les événements. La suite de notre étude s’est alors focalisée sur le film collectif L’Allemagne en automne. L’analyse de différentes formes de signatures auctoriales a révélé d’abord que si le film est à considérer comme une œuvre signée en groupe, sa signature « désindividualisante » entre aussi en concurrence directe avec un ensemble de marqueurs d’énonciation individuelle. En résulte l’oscillation d’un auteur, reconnaissable et anonyme, proposant de la sorte un nouveau lieu du discours. Enfin, nous nous sommes penchés sur les mises en scène des séquences du film. Notre analyse a mis en évidence que les évènements précis de l’automne '77 agissent seulement comme des rappels visuels d’un contexte particulier. Ce contexte anxiogène nous a amené à conclure provisoirement à l’échec de l’auteur : incapable de se libérer du camp qui lui est attribué a priori, il reproduit les comportements et regards de ses « adversaires » (point de vue du « policier embusqué, etc.). Conscient de cette paralysie, l’auteur est pourtant aussi le premier créateur de ces manifestations d’échec. En ce sens, il ne subit pas la crise dans laquelle le précipite l’Automne Allemand, mais il la (re)met en scène. Le produit de cette lucidité, de cette conscience est le mélancolique : une représentation ou un discours produits par un sujet conscient mettant en abyme le retournement contre soi, la perte de soi qui lui paraît inéluctable dans le contexte des années de plomb. [less ▲]

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See detailProphétisme, hétérodoxie et dissidence. L’imaginaire kimbanguiste en mouvement
Melice, Anne ULg

Doctoral thesis (2011)

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See detailMolecular characterization of the host-pathogen relationships involved during an infection of GF-305 peach trees by the Peach latent mosaic viroid (PLMVd)
Parisi, Olivier ULg

Doctoral thesis (2011)

The Peach latent mosaic viroid (PLMVd) infects peach trees in all production areas. This pathogen is responsible of direct and indirect crop losses. However only a few data are available as regards on one ... [more ▼]

The Peach latent mosaic viroid (PLMVd) infects peach trees in all production areas. This pathogen is responsible of direct and indirect crop losses. However only a few data are available as regards on one hand the determinant of pathogenicity of this viroid and on the other hand the resistance mechanisms of plants against this pathogen. The original approach of this work was to give the foundation of this double characterization. Firstly, the role of the P8 pseudoknot, present in every sequenced PLMVd, was studied by directed mutagenesis. Secondly, the molecular response of different peach trees infected by different variants was evaluated by the use of the cDNA-AFLP. The main objective of this thesis was to identify a metabolic pathway implicated in the plant defence against the PLMVd. In the term of this work, it seemed that the P8 pseudoknot was implicated either in the stability or in the replication of the viroid into the infected cells. Indeed, the inoculated variant (with a destabilized pseudoknot) has shown a reduced replication during the cultural season. In spite of the presence of the mutated variant in the plants, no symptom was observed on the peach tree leaves. However, we cannot conclude if this absence of symptom is due to the low viroid quantity either to an implication of the pseudo-knot in the pathogenicity of the PLMVd. The characterization of the gene expression in the infected peach trees has allowed to highlight that the PLMVd represses genes implicated in the photosynthesis and more specifically genes involved in the protection of the two photosystems. This particular gene expression in the infected leaves was linked to the chlorosis and mosaic induced by the PLMVd. However, we cannot conclude with certitude if these symptoms are a cause or a consequence of this particular genes expression. The cDNA-AFLP has also allowed to identify the repression of genes coding for heat shock proteins (HSPs) in symptomatic leaves. These proteins generally have a role in the protein folding, assembly, translocation, stabilization and degradation. The regulation of their expression may have a great influence in the infected plants and, maybe, play a role in the symptoms expression. The gene coding for the novel cap-binding protein (nCBP) was also identified has repressed in the symptomatic leaves. The biological role of these proteins is unclear but it seems that these proteins act in the regulation of the mRNA translation. The repression of nCBP may thus have an important impact and to destabilize various biological pathways. Finally, two genes implicated in the plant defence were identified. One coding for a polygalacturonase inhibitor (over-expressed in symptomatic leaves) and the other one coding for a thiamine intermediate (involved in the SAR and over-expressed in the non-symptomatic leaves). The role of these proteins in the plant defence against the PLMVd is however unclear. To our knowledge, this is the first work where the host-pathogen relationship established during a PLMVd infection are studied. This is also the first time were the gene expression is linked to the viroid-induced symptoms. [less ▲]

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See detailApproaches for assessing the presence and impact of thyroid hormone disrupting chemicals in sea bass (Dicentrarchus labrax) from European coasts
Schnitzler, Joseph ULg

Doctoral thesis (2011)

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro ... [more ▼]

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg) were analysed in the muscle of sea bass (Dicentrarchus labrax) sampled in coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). We applied a multi-level approach of thyroid function assessment. Thyroxine (T4) and triiodothyronine (T3) concentrations in muscle were analyzed by radioimmunoassay. The activity of hepatic enzymes involved in extrathyroidal pathways of thyroid hormone metabolism, viz. deiodination, glucuronidation and sulfation were analyzed. Last, follicle diameter and epithelial cell heights were measured. We observed changes that lead to an increased conversion of T4 to T3 and lowered thyroid hormone excretion. The changes in the metabolic pathways of thyroid hormones can be interpreted as a pathway to maintain thyroid hormone homeostasis. The higher chlorinated PCBs seemed to be the most implicated in this perturbation. To gain a more integrated insight, we examined the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. After 120 days of exposure, histomorphometry of thyroid tissue, muscular thyroid hormone concentration and activity of enzymes involved in metabolism of thyroid hormones were assessed. The results show that the effects of PCB exposures on the thyroid system are dose-dependent. Exposure to environmentally relevant doses of PCB (0.3 to 1.0 μg Σ7PCBs per g food pellets) increases thyroid hormone synthesis and stimulates hepatic T4 outer ring deiodinase and T4 sulfation. Thyroid hormone tissue levels were preserved thanks to the PCB induced changes in T4 dynamics. At 10 times higher concentrations (10 μg Σ7PCBs per g food pellets) an important depression of T3 and T4 levels could be observed which are apparently caused by degenerative histological changes in the thyroid tissue. We propose accurate interpretations, by reviewing the different stages of teleost thyroid function and regulation. [less ▲]

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See detailUn médiateur invisible. Analyse et mise en perspective du régime de régulation des ondes électromagnétiques
Joris, Geoffrey ULg

Doctoral thesis (2011)

La présente thèse de doctorat propose une analyse du régime de régulation des risques liés à la téléphonie mobile et ce à différents niveaux de pouvoir (International, européen, belge - échelons fédéral ... [more ▼]

La présente thèse de doctorat propose une analyse du régime de régulation des risques liés à la téléphonie mobile et ce à différents niveaux de pouvoir (International, européen, belge - échelons fédéral, régional et local). L'idée est de démontrer la dynamique d'ouverture et de fermeture tout au long de la "séquence" de la politique publique construisant progressivement un régime de régulation du risque "électromagnétique" [less ▲]

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See detailOptimisation et caractérisation d’un extrait de cassis riche en antioxydants utilisable comme complément alimentaire
Tabart, Jessica ULg

Doctoral thesis (2011)

Blackcurrant (Ribes nigrum, family Saxifragaceae) produces fruits with a high antioxidant content. This shrub is much known for its strongly aromatic fruits. It is largely used in the industrial ... [more ▼]

Blackcurrant (Ribes nigrum, family Saxifragaceae) produces fruits with a high antioxidant content. This shrub is much known for its strongly aromatic fruits. It is largely used in the industrial production of syrups and of concentrates, it contains very high quantities of phenolic compounds, particularly anthocyanins. Blackcurrant buds and leaves are also used as a food complement for their tonic and diuretic properties, as well as for the treatment of rheumatic affections. With this plant, we tried to develop, on a laboratory scale, a flavonoid-rich extract, stable in time and to show several biological activities. Initially, different plant materials were compared (fruits, leaves, buds, from different cultivars harvested at different times) and the method of extraction were optimized. Lyophilised-leaf extracts obtained with the acetone-water-acetic acid mixture (70: 28: 2) show an excellent yield in antioxidant compounds. These freeze-dried extracts have also the advantage of being stable for several months. We characterized these extracts for their content in various classes of antioxidant molecules. The leaves and the buds yielded extracts containing mainly flavonols, flavanols and total phenolic compounds, as compared to berries. On the other hand, these fruits showed higher contents of ascorbic acid and anthocyanins. In a third part, we analyzed certain health-properties (antioxidant capacity, anti-inflammatory capacity and the properties in vasorelaxation process) of the blackcurrant extracts by using in vitro methods as well as cellular and isolated organ models. Our study highlighted the intracellular and the extracellular properties of the blackcurrant extract as radical scavenger. We also showed an inhibition of the myeloperoxydase activity in the activated neutrophils, and an activation of the vasorelaxation process of the blood-vessels (production of NO, modulation of the expression of ARNm eNOS in the endothelial cells and relaxing effect in isolated organ), and this, without presenting any toxic effects. In conclusion, the black currant leaf extract obtained through extraction in acetone-water- acetic acid mixture has many interesting properties for health-protection. This extract, rich in phenolic compounds and having a high antioxidant activity, can also modulate the activity of several enzymes involved in inflammation or in vascular motricity. [less ▲]

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See detailContributions to Batch Mode Reinforcement Learning
Fonteneau, Raphaël ULg

Doctoral thesis (2011)

This dissertation presents various research contributions published during these four years of PhD in the field of batch mode reinforcement learning, which studies optimal control problems for which the ... [more ▼]

This dissertation presents various research contributions published during these four years of PhD in the field of batch mode reinforcement learning, which studies optimal control problems for which the only information available on the system dynamics and the reward function is gathered in a set of trajectories. We first focus on deterministic problems in continuous spaces. In such a context, and under some assumptions related to the smoothness of the environment, we propose a new approach for inferring bounds on the performance of control policies. We also derive from these bounds a new inference algorithm for generalizing the information contained in the batch collection of trajectories in a cautious manner. This inference algorithm as itself lead us to propose a min max generalization framework. When working on batch mode reinforcement learning problems, one has also often to consider the problem of generating informative trajectories. This dissertation proposes two different approaches for addressing this problem. The first approach uses the bounds mentioned above to generate data tightening these bounds. The second approach proposes to generate data that are predicted to generate a change in the inferred optimal control policy. While the above mentioned contributions consider a deterministic framework, we also report on two research contributions which consider a stochastic setting. The first one addresses the problem of evaluating the expected return of control policies in the presence of disturbances. The second one proposes a technique for selecting relevant variables in a batch mode reinforcement learning context, in order to compute simplified control policies that are based on smaller sets of state variables. [less ▲]

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See detailRhizosphere-driven lipopeptide production by different strains of Bacillus spp. as mechanism involved in biological control of plant pathogens
Nihorimbere, Venant ULg

Doctoral thesis (2011)

Some plant-beneficial bacteria with biopesticide potential produce antimicrobial compounds that are tightly involved in multitrophic interactions occurring in the phytosphere among which antagonism toward ... [more ▼]

Some plant-beneficial bacteria with biopesticide potential produce antimicrobial compounds that are tightly involved in multitrophic interactions occurring in the phytosphere among which antagonism toward a diverse range of phytopathogens. However, there is a crucial need for an accurate assessment of antibiotic production rate in this environment colonized by these bacteria. In this context, we conducted the present thesis work with the scope to better understand how two different Bacillus genus strains produce lipopeptides in the rhizosphere of plants. In the first part, one of the strains (B. amyloliquefaciens S499) was selected out of other isolates for its technological traits and in vitro inhibition growth activity of plant pathogenic fungi. We further demonstrated its biocontrol potential in tomato open-field experiments where plantings have been devastated by a local fungus preliminary identified as Fusarium semitectum. In a second part, we combined two mass spectrometry-based approaches (electrospray ionization and imaging) to analyze the pattern of surfactin, iturin and fengycin lipopeptide families produced in planta by strain S499. Our results show that rhizosphere conditions are conducive for surfactin synthesis but not for other types of lipopeptides and that the lipopeptide pattern can be markedly influenced by nutritional factors, biofilm formation and oxygen availability. In a last part, surfactin gene expression (srfA) level was evaluated in situ on tomato root using the reporter gene (LacZ) inserted in B. subtilis strain BGS3. Results showed effective expression of srfA and production of surfactin in biologically important level quantities upon establishment of bacterial population on roots. Our results also demonstrate that BGS3 developing in colonies, efficiently utilizes the main substrates from plant exudates to produce surfactins. The production may also be favored in bacteria growing slowly in the rhizosphere. Globally, this work contributes to better appreciate the impact of some environmental factors on the in situ biosynthesis of lipopeptides by strains of Bacillus which is probably an essential step for improving the level and reliability of their efficacy as biological agents for the control of plant diseases. [less ▲]

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See detailConscience de soi dans le vieillissement normal et pathologique
Feyers, Dorothée ULg

Doctoral thesis (2011)

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See detailContribution to pomegranate seeds conservation (Punica granatum L.) by osmotic dehydration
Bchir, Brahim ULg

Doctoral thesis (2011)

The aim of this work was to create a complete conservation process of pomegranate seeds (Punica granatum L.). This process is essentially based on osmotic dehydration (OD), which was associated to ... [more ▼]

The aim of this work was to create a complete conservation process of pomegranate seeds (Punica granatum L.). This process is essentially based on osmotic dehydration (OD), which was associated to freezing and air-drying process. Several parameters were studied to optimize the process such as osmotic solution (sucrose, glucose, and sucrose/glucose and date juice with sucrose added), temperature (30, 40, and 50°C) and state of the fruit (fresh and frozen). All these conditions were linked to seed proprieties (texture, structure, and colour). The study of osmotic dehydration parameters (water loss (WL), solids gain (SG) and weight reduction (WR)) showed that most significant changes of mass transfer took place during the first 20 min of dewatering using frozen seeds, independently of temperature and sugar type. During this period, seeds water loss was estimated at 46% in sucrose, 41% in sucrose/glucose mix, 39% in date juice, and 37% in glucose. Mass transfer was slower starting from fresh fruit but led to a higher rate of WL at the end of the process. This fact can be explained by scanning electron microscopy, which showed damage of seed cell structure after freezing. This has practical consequences in terms of the modification of seeds texture. The same process also revealed a modification of seed texture and cell structure after osmotic dehydration. Using a sucrose solution and a temperature of 50°C favoured the best mass transfer. The determination of different water fractions of seed by differential scanning calorimetry (DSC) showed that the % of frozen water decreased 3.5 times contrary the % of unfreezable water that increased 2.5 times. This favours a better seeds conservation. During osmotic dehydration, there was a non negligible leaching of natural solutes from seeds into the solution, which might have an important impact on the sensorial and nutritional value of seeds. Using only osmotic dehydration could not maintain the stability of seeds during conservation. In fact, after the osmotic process, water activity of seeds was found to be higher than 0.9, allowing to the development of microorganisms and some undesirable reactions. As a consequence, a drying of the pomegranate seeds (during four hours) was investigated at three different temperatures (40, 50, and 60 °C) with air flow rate of 2 ms-1. Prior to the drying process, seeds were osmodehydrated in a sucrose solution (55°Brix) during 20 min at 50°C. The drying kinetics and the effects of OD and air-drying temperature on antioxidant capacity, total phenolic, colour, and texture were determined. This work is a contribution to the study of physico-chemical properties of pomegranate seeds (Punica granatum L.) during freezing, osmotic dehydration and drying. After the global process, the pomegranate seed characteristics lead to new industrial developments. [less ▲]

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See detailInfluence of Biomaterials in Alveolar Bone Regeneration and Preservation
LAMBERT, France ULg

Doctoral thesis (2011)

Dental implants are nowadays a reliable solution to replace missing teeth and have been widely documented. However, they require a minimal bone quantity (in height and thickness). But alveolar bone ... [more ▼]

Dental implants are nowadays a reliable solution to replace missing teeth and have been widely documented. However, they require a minimal bone quantity (in height and thickness). But alveolar bone defects are very frequent, for instance due to periodontitis, traumatism or acute dental infection. Moreover, a simple tooth extraction leads to significant bone resorption. Therefore, alveolar bone regeneration is often necessary in order to place implants and to restore the patient's dentition with implant-supported prosthesis. Even though alveolar bone reconstructions have been considered as traumatic, especially due to the need of a second surgical site for bone harvesting, techniques have evolved with the introduction of biomaterials. However, it is difficult to compare the influences of such biomaterials on osteogenesis and to elaborate on the advantages of one product over another. The overall objective of this thesis is to contribute to the understanding of the biological concept of alveolar bone regeneration, in particular sinus lift and socket preservation procedures. The influence of biomaterials on bone regeneration has been emphasized through preclinical and clinical studies. The number of commercially available biomaterials for bone regeneration is growing every day and some materials are not supported by strong scientific data in the literature. The first part of this thesis (Chapter 1) is dedicated to the characterization of several biomaterials often used in dentistry. The impact of their various characteristics on osteogenesis has been reviewed, from chemical aspect to micro- and macromorphology. Furthermore, a data sheet integrating the physico-chemical and morphological properties of each studied biomaterial has been developed as a tool for clinicians. Sinus floor elevation has often been considered as a bone graft. In 1996, a consensus conference on “sinus lift” took place and the procedure was qualified as “sinus bone-graft”. But new scientific evidence has shown that this qualification is not justified. Chapter 2 aims at understanding the physiology and the biological model of sub-sinusal bone augmentation by using either a simple blood clot, autogenous bone chips or biomaterials (BHA) as space fillers under the lifted sinusal membrane. If bone formation did occur with the 3 types of space fillers, the augmented volumes significantly dropped with the blood clot or the autogenous bone chips but remained stable with BHA. Therefore, a slowly resorbable biomaterial such as BHA might be suitable in sub-sinusal bone augmentation to prevent the re-expansion process. Understanding the biological concept of sinus lift procedures, several authors demonstrated the clinical efficacy of biomaterials when used alone in this specific model. Nevertheless, biomaterials known to be resorbable led to a lamellar bone architecture that might not be able to maintain the volume of the regenerated tissue over time. Moreover, many types of biomaterials are available and scientific evidence of short and long-term performance of newly introduced biomaterials is still poor. Chapter 3 aims at comparing the performances, in terms of bone formation, resorption rate and 3-D stability, of four calcium phosphate-based biomaterials often used for sub-sinusal bone augmentation, in a rabbit model. Particulated space-filling biomaterials seemed to be more efficient to promote osteogenesis compared to paste-like biomaterials. Highly resorbable biomaterials appeared to withstand intrasinusal pressure after a period of six months in rabbits. Non- or slowly resorbable biomaterials are of great interest in the dental field because the long-term stability of 3-D bone augmentation is a key factor for dental implant and aesthetic outcomes. Therefore, the mechanical and non-resorbable properties of titanium, known to be highly compatible in vivo and highly resistant to body fluid corrosion, are potential advantages for bone augmentation prior to dental implantation. Nevertheless, the use of titanium particles as space fillers in bone regeneration was weakly reported in the literature from a histological point of view. Thus, Chapter 4 compares the behavior and the effect of porous titanium particles versus the well-documented BHA. Even though both biomaterials allowed osteogenesis and adequate 3-D stability, the bone architecture, and more specifically the amount of bone-to-material contact (BMC), was significantly different. Inclusion of the particles in a carrier or in binding agents such as a collagen gel or fibers might be of interest in order to ease surgical handling. However, the possible influence of those collagen carriers on bone tissue responses remains poorly investigated. The objective of Chapter 5 was to investigate the effect of collagen at different stages of the osteogenesis process, still in the same rabbit model. The findings clearly showed the presence of inflammatory cells at an early stage of bone regeneration when collagenated xenogenic biomaterials were used compared to collagen-free xenogenic granules. Nevertheless, despite the transient inflammation, the final quantity of newly formed bone was similar in the various groups. The last two chapters of this thesis take some of the preclinical findings of the previous chapters to the clinical field. The objective of Chapter 6 was to assess the clinical outcome of a minimalized sub-sinusal bone augmentation procedure using only biomaterials, simultaneously with the placement of 102 non-submerged implants in 40 patients. Implant and prosthodontic survival rates as well as complications were evaluated after a follow-up period of 2 to 6 years. This clinical trial emphasized that, if the amount of remaining bone height is sufficient to ensure implant primary stability, their placement can be performed simultaneously with sinus lifting, even in a non-submerged fashion. This procedure reduces the number of surgeries and the time before prosthetic rehabilitation. The objective of Chapter 7 was to to develop a new method to objectively evaluate in humans the 3-D volume variation of alveolar socket preservation over time by means of computed tomography and 3-D image analysis. Short summary: Before placing dental implants, alveolar bone regeneration is often required due to bone defects caused by periodontitis, traumatism or even a simple tooth extraction. Bone augmentation surgical procedures have very much evolved thanks to a better understanding of biological processes and to the introduction of biomaterials. The overall objective of this thesis is to bring a contribution to the understanding of the biological concept of alveolar bone regeneration, and in particular sinus lift and socket preservation procedures. The influence of biomaterials on bone regeneration has been emphasized through preclinical and clinical studies. [less ▲]

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See detailDesign and Implementation of a Distributed Lattice Boltzmann-based Fluid Flow Simulation Tool
Dethier, Gérard ULg

Doctoral thesis (2011)

Lattice Boltzmann-based (LB) simulations are well suited to the simulation of fluid flows in complex structures encountered in chemical engineering like porous media or structured packing used in ... [more ▼]

Lattice Boltzmann-based (LB) simulations are well suited to the simulation of fluid flows in complex structures encountered in chemical engineering like porous media or structured packing used in distillation and reactive distillation columns. These simulations require large amounts of memory (around 10 gigabytes) and would require very long execution times (around 2 years) if executed on a single powerful desktop computer. The execution of LB simulations in a distributed way (for example, using cluster computing) can decrease the execution time and reduces the memory requirements for each computer. Dynamic Heterogeneous Clusters (DHC) is a class of clusters involving computers inter-connected by a local area network; these computers are potentially unreliable and do not share the same architecture, operating system, computational power, etc. However, DHCs are easy to setup and extend, and are made of affordable computers. The design and development of a software system which organizes large scale DHCs in an efficient, scalable and robust way for implementing very large scale LB simulations is challenging. In order to avoid that some computers are overloaded and slow down the overall execution, the heterogeneity of computational power should be taken into account. In addition, the failure of one or several computers during the execution of a simulation should not prevent its completion. In the context of this thesis, a simulation tool called LaBoGrid was designed. It uses existing static load balancing tools and implements an original dynamic load balancing method in order to distribute the simulation in a way that minimizes its execution time. In addition, a distributed and scalable fault-tolerance mechanism based on the regular saving of simulation’s state is proposed. Finally, LaBoGrid is based on a distributed master-slave model that is robust and potentially scalable. [less ▲]

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See detailMolecular characterization of embryogenesis in Phaseolus
Abid, Ghassen ULg

Doctoral thesis (2011)

Chez les végétaux supérieurs, l’embryogenèse est une phase clé du développement au cours de laquelle l’embryon établit les principales structures de la future plante. La compréhension des processus ... [more ▼]

Chez les végétaux supérieurs, l’embryogenèse est une phase clé du développement au cours de laquelle l’embryon établit les principales structures de la future plante. La compréhension des processus moléculaires et physiologiques menant à la formation de la graine est donc d’un intérêt agronomique majeur. Chez Phaseolus la caractérisation moléculaire de l’embryogenèse permet de mieux comprendre les mécanismes du développement embryonnaire et de son dysfonctionnement observé chez les hybrides interspécifiques. Cette thèse s’inscrit dans ce cadre et vise à identifier et caractériser des gènes clés impliqués dans le développement de l'embryon chez Phaseolus. Des hybridations interspécifiques ont été réalisées entre l’espèce P.vulgaris L. (cultivar NI637) utilisée comme parent mâle et l’espèce P. coccineus L. (cultivar NI16) utilisée comme parent femelle. Des analyses ont aussi été effectuées sur un mutant obtenu par mutagenèse chimique à l'EMS (Ethyl Méthyl Sulfonate) de graines de la variété BAT93 de P.vulgaris. Une étude histologique comparative a permis de suivre la dynamique de l’embryogenèse du haricot commun à partir d’embryons prélevés 3 à 12 jours après la pollinisation et provenant de plantes normales et déficients dans la production de graines. Les embryons de P. vulgaris se développent plus rapidement par rapport à ceux issus du mutant EMS. Ces derniers présentent des anomalies au niveau de l’embryon et du suspenseur. La caractérisation fonctionnelle de deux gènes candidats MIPS (myo-inositol phosphate synthase) et Sus (sucrose synthase) a été réalisée par RT-PCR quantitative et hybridation in situ suite à une étude spatio-temporelle d’expression de ces deux gènes candidats au cours de développement embryonnaire chez Phaseolus. L’analyse du profil d’expression de ces deux gènes montre qu’ils sont exprimés différemment au niveau des tissus de l’embryon et du suspenseur. L’analyse in silico nous a permis de sélectionner 22 gènes candidats dont nous avons vérifié l'expression au cours de développement de la graine chez Phaseolus. Des variations au niveau de la méthylation de l’ADN ont été déterminées chez les hybrides interspécifiques comparativement à leurs parents. La technique de l’HSS a permis d’isoler des fragments d’ADNs complémentaires différemment exprimés au cours de développement de la graine chez Phaseolus. L’analyse des séquences de ces ADNs complémentaires montre qu’ils codent pour plusieurs protéines intervenant dans le développement cellulaire et embryonnaire, en particulier le "storage protein activator" (SPA), le "pentatricopeptide repeat-containing protein" (PPR) et l’acetyl-CoA carboxylase (ACCase). La caractérisation de ces différents gènes exprimés au cours du développement de la graine, fournit de nouveaux outils susceptibles de mettre en évidence des mécanismes de dysfonctionnement embryonnaire chez le genre Phaseolus. [less ▲]

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See detailOptimal experimental designs for funtional magnetic resonance imaging
Maus, Bärbel ULg

Doctoral thesis (2011)

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See detailLattice dynamics in thermoelectric Zintl phases
Möchel, Anne ULg

Doctoral thesis (2011)

A brief introduction to the thermoelectric effects, the studied materials, and the experimen- tal methods is given in the first chapter. The introduction is not intended to be exhaustive, but only to ... [more ▼]

A brief introduction to the thermoelectric effects, the studied materials, and the experimen- tal methods is given in the first chapter. The introduction is not intended to be exhaustive, but only to summarize important basic information for the reader. The introduction is followed by four chapters dedicated to detailed experimental studies of the lattice dynamics in selected thermoelectric Zintl phases. First, the lattice dynamics in the unfilled and filled skutterudites FeSb3 , CoSb3 , and YbFe4 Sb12 were studied by nuclear inelastic scattering, inelastic neutron scattering, and several macroscopic methods. These studies reveal that FeSb3 exhibits softer Sb bonds than CoSb3 , that the density of phonon states is shifted towards lower energies and the velocity of sound is lower in FeSb3 as compared to CoSb3 . It appears thus that the soft [Fe4 Sb12 ] framework dynamics might play an important role in the thermoelectric properties of filled skutterudites. The observed anomalous temperature dependence of the elastic constants and the rearrangement of the spectral weight of the Yb phonon states in YbFe4 Sb12 can be explained by a change of the Yb valence state with the temperature. Second, the lattice dynamics in the Sr8 Ga16 Ge30 clathrate was investigated by inelastic neutron scattering measurements on a single crystal. We found that several mechanisms contribute to the low thermal conductivity in this system and that the reduction of the heat capacity contribution to the thermal conductivity plays a significant role to the low thermal conductivity, besides the reduction in the phonon lifetime and the phonon group velocity that is related to the guest atom. Third, the lattice dynamics of the Zintl phase Yb14 MnSb11 was studied by inelastic neu- tron scattering and nuclear inelastic scattering measurements. All phonon modes of these complex crystal systems are in a narrow energy range below ∼25 meV and the Debye tem- perature, the velocity of sound and the mean force constants are small compared to those of other thermoelectric materials such as Zn4 Sb3 . By comparing the lattice dynamics in Yb14 MnSb11 and Zn4 Sb3 different mechanisms which lead to the low thermal conductivity in Zintl phases have been identified. Between 300 and 1200 K no softening of the velocity of sound in Yb14 MnSb11 was observed by temperature dependent inelastic neutron scattering measurements, which is in line with its large melting temperature. [less ▲]

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See detailDéveloppement d’un modèle hydrologique sol et zone vadose afin d’évaluer l’impact des pollutions diffuses et des mesures d’atténuation sur la qualité des eaux en Région wallonne
Sohier, Catherine ULg

Doctoral thesis (2011)

Implementation of new European directives in the environmental field and, specially, in the water field, generate a request from policy-makers for news tools able to evaluate impact of measures token in ... [more ▼]

Implementation of new European directives in the environmental field and, specially, in the water field, generate a request from policy-makers for news tools able to evaluate impact of measures token in order to reduce pressures on ecosystems. In this context, the objective of this PhD thesis is to develop a “soil and vadose” hydrological model in order to evaluate impact of diffuses pollutions and mitigation measures on water quality in the Walloon region. The “soil and vadose zone” model of the Walloon region (EPICgrid model) has been developed at catchment scale with an original modular concept on the basis of the field scale “water-soil-plant” EPIC model (Williams et al., 1984). After that the model was validated at field scale and at catchment scale, the EPICgrid model was used to simulate the hydrological behaviour of the Walloon region catchments and to produce environmental indicators for surface water and groundwater bodies of the Walloon region. The simulated fluxes are related to unsaturated or temporarily saturated soils. The simulations are focused, on the one hand, on hydrological balance terms (direct runoff, subsurface fluxes, groundwater recharge, soil moisture variability, actual evapotranspiration) and, on the other hand, on associated fluxes of nitrogen, phosphorus, organic matters and sediments, from agricultural origin. The EPICgrid model was then used to evaluate water quality impact of mitigation measures token in order to reduce agricultural diffuse pollution effect on the quality on surface water and groundwater bodies in the Walloon region. [less ▲]

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See detailEtude de l'activité antifongique des bactéries lactiques isolées de produits alimentaires fermentés et caractérisation de leurs métabolites inhibiteurs
Ndagano, Dora ULg

Doctoral thesis (2011)

Summary: The aim of this present research was to study the antifungal properties of lactic acid bacteria (LAB) isolated from fermented Mill flour and fermented cassava in order to use them for ... [more ▼]

Summary: The aim of this present research was to study the antifungal properties of lactic acid bacteria (LAB) isolated from fermented Mill flour and fermented cassava in order to use them for biopreservation. Antifungal activity of these LAB were assessed in MRS solid medium against food spoilage moulds as Aspergillus niger MUCL 28699, Aspergillus niger CWBIF194, Aspergillus tubingensis MP1 and Penicillium crustosum MY1. Three strains, Lactobacillus plantarum VE56, Weissella cibaria FMF4B16 and Weissella paramesenteroides LC11 were selected among 116 for their strongest inhibitory activity and their broad inhibitory spectrum against food moulds. The 4-fold concentrated supernatant of L. plantarum VE56 and W. paramesenteroides LC11 had the strongest inhibitory activity to compare to W. cibaria FMF4B16. The antifungal activity of the cell-free supernatant was pH dependent and insensitive to proteolytic enzymes action suggesting that the inhibitory activity was due to other compounds than proteins. The identification of antifungal compounds by chromatographic studies highlighted the production of phenyllactic acid by the three strains. In addition, 2-hydroxy-3-methylpentanoic acid and 2-hydroxy-4-methylpentanoic acid were produced by L. plantarum VE56 and W. paramesenteroides LC11. However, the concentration assessed in the supernatant was lower than the minimal inhibitory concentration showing a synergic action of all these produced compounds. The effect of the antifungal supernatant of L. plantarum VE56 and W. paramesenteroides LC11 on Aspergillus flavus NRRL 3357 resulted to an inhibition of conidial development and aflatoxin B1 production which was reflected in decreased gene expression of brlA (conidiophore specific transcription factor) and laeA (global regulator of secondary metabolism). These two bacteria also delayed Penicillium expansum MUCL 14498 conidial development in bread. [less ▲]

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See detailSonia Hajjar Domaine : Human resource management Titre : Status of Female Auditors in Lebanon: Careers and Family Concerns
Hajjar, Sonia ULg

Doctoral thesis (2011)

This research discusses the status of female auditors in Lebanon with a special emphasis on individual career and family concerns. It attempts at investigating the status of female auditors, and at ... [more ▼]

This research discusses the status of female auditors in Lebanon with a special emphasis on individual career and family concerns. It attempts at investigating the status of female auditors, and at pointing out the major hindrances that they face when trying to achieve a balance between career and family life; thus, issues such as organizational, individual, and social factors are discussed. The focus is to discuss the status of female Lebanese auditors through analysis and conclusions drawn from practical experience and to present a model of the issues in relation to certain variables and factors. Questionnaires and interviews were used to collect the data. Results show that the above-mentioned factors, cross-referenced with the glass ceiling, work life balance, and turnover, are combined. Research revealed that many factors mold the status of female auditors in Lebanon. The limitations of the study stem from the fact that no such studies have been conducted in Lebanon and, thus, the literature review was mainly constructed on published research done in the West. Results reveal that the individual Lebanese female auditor is faced with a glass ceiling only because she chose her family over her career, and when she chose to leave the profession (turnover) it was because of her family duties, the long working hours, stress, and work life balance that forced her to make a choice between herself as a career women, or as a mother and wife. The study is aimed at establishing possible relationship between academia, audit profession, and the business market. [less ▲]

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See detailLes cultes de l'île de Cos après le synécisme de 366 avant notre ère. Contribution à l'étude du fonctionnement du polythéisme grec
Paul, Stéphanie ULg

Doctoral thesis (2011)

L’étude des cultes de l’île de Cos vise à discerner les modalités selon lesquelles une cité grecque organise ses relations avec le monde supra-humain. L’exposé est articulé en deux volets complémentaires ... [more ▼]

L’étude des cultes de l’île de Cos vise à discerner les modalités selon lesquelles une cité grecque organise ses relations avec le monde supra-humain. L’exposé est articulé en deux volets complémentaires. La première partie propose une analyse systématique des différents cultes attestés dans l’île, fondée sur l’exploitation de toutes les sources à disposition, épigraphiques principalement, mais également littéraires et archéologiques. Les cultes sont ordonnés selon une répartition géographique, ceux de la cité, puis des dèmes. Le sanctuaire de l’Asclépieion, situé à quelques kilomètres à l’extérieur de la ville de Cos et jouissant d’une cohérence propre, fait l’objet d’un chapitre à part. Cette analyse exhaustive, incluant les nouvelles inscriptions publiées en nombre ces dernières années et encore peu étudiées, permet de pallier une lacune dans la bibliographie actuelle. La seconde partie du travail se conçoit comme une synthèse de cette analyse des cultes et propose une réflexion sur le fonctionnement du polythéisme tel que la cité de Cos permet de le saisir. Le premier chapitre, consacré aux « configurations du panthéon », s’attache à définir, dans la mesure du possible, le profil des divinités qui constituent ce dernier, ainsi que les relations qui se nouent entre elles. L’intérêt d’une telle approche régionale est de pouvoir ancrer ces cultes dans le contexte historique auquel ils appartiennent, et cela se justifie d’autant plus que les panthéons locaux « cristallisaient » les préoccupations des communautés qui les construisaient. Ainsi, on observe qu’un événement particulier de l’histoire de l’île a eu une influence remarquable sur l’organisation des cultes. Il s’agit du synécisme de 366 avant notre ère, qui a vu l’unification des différentes communautés en une seule cité, dont le centre urbain a été fondé sur la pointe nord de l’île. Cette influence résulte notamment en une orientation spécifique conférée à une série de cultes, qui mettent une emphase particulière sur la communauté et sur l’unité de la cité, tels que ceux de Zeus Polieus ou d’Aphrodite Pandamos. En outre, et en dépit de l’ancrage local de cette étude, le recours fréquent à la comparaison avec les panthéons d’autres cités grecques permet d’inscrire largement l’interprétation de celui de Cos sur un plan panhellénique. À côté de cette réflexion sur le panthéon de Cos, un second chapitre se propose d’affiner l’interprétation de certaines procédures sacrificielles, décrites dans les inscriptions et évoquées dans la première partie, et de les mettre en perspective par rapport au reste de la documentation de Cos. Une telle étude contextuelle du sacrifice a l’avantage d’apporter un éclairage complémentaire aux études thématiques plus générales, qui ne permettent guère de remettre les pratiques en contexte. L’acte sacrificiel étant au cœur du système religieux des Grecs et de leur communication avec le monde supra-humain, son étude ne peut être dissociée de celle de la représentation du divin. Ainsi, la manière dont ces actes sacrificiels sont posés est porteuse de sens quant au profil du destinataire ou encore au message précis qui lui était adressé. En conclusion, par les diverses configurations qu’elle met en évidence, qu’elles relèvent de spécificités locales ou de représentations plus largement partagées, l’étude des cultes de Cos permet d’apporter une contribution à notre compréhension du système religieux des Grecs et de son imbrication dans la vie des communautés. [less ▲]

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See detailPhysical modelling of overbank flows with a groyne set on the floodplain
Peltier, Yann ULg

Doctoral thesis (2011)

Detailed reference viewed: 15 (5 ULg)
See detailA 3D model of ocean biogeochemical cycles and climate sensitivity studies
Mouchet, Anne ULg

Doctoral thesis (2011)

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See detailPhenomenology of supersymmetric neutrino mass models
Vicente, Avelino ULg

Doctoral thesis (2011)

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See detailSupervised Learning for Sequential and Uncertain Decision Making Problems - Application to Short-Term Electric Power Generation Scheduling
Cornélusse, Bertrand ULg

Doctoral thesis (2010)

Our work is driven by a class of practical problems of sequential decision making in the context of electric power generation under uncertainties. These problems are usually treated as receding horizon ... [more ▼]

Our work is driven by a class of practical problems of sequential decision making in the context of electric power generation under uncertainties. These problems are usually treated as receding horizon deterministic optimization problems, and/or as scenario-based stochastic programs. Stochastic programming allows to compute a first stage decision that is hedged against the possible futures and -- if a possibility of recourse exists -- this decision can then be particularized to possible future scenarios thanks to the information gathered until the recourse opportunity. Although many decomposition techniques exist, stochastic programming is currently not tractable in the context of day-ahead electric power generation and furthermore does not provide an explicit recourse strategy. The latter observation also makes this approach cumbersome when one wants to evaluate its value on independent scenarios. We propose a supervised learning methodology to learn an explicit recourse strategy for a given generation schedule, from optimal adjustments of the system under simulated perturbed conditions. This methodology may thus be complementary to a stochastic programming based approach. With respect to a receding horizon optimization, it has the advantages of transferring the heavy computation offline, while providing the ability to quickly infer decisions during online exploitation of the generation system. Furthermore the learned strategy can be validated offline on an independent set of scenarios. On a realistic instance of the intra-day electricity generation rescheduling problem, we explain how to generate disturbance scenarios, how to compute adjusted schedules, how to formulate the supervised learning problem to obtain a recourse strategy, how to restore feasibility of the predicted adjustments and how to evaluate the recourse strategy on independent scenarios. We analyze different settings, namely either to predict the detailed adjustment of all the generation units, or to predict more qualitative variables that allow to speed up the adjustment computation procedure by facilitating the ``classical'' optimization problem. Our approach is intrinsically scalable to large-scale generation management problems, and may in principle handle all kinds of uncertainties and practical constraints. Our results show the feasibility of the approach and are also promising in terms of economic efficiency of the resulting strategies. The solutions of the optimization problem of generation (re)scheduling must satisfy many constraints. However, a classical learning algorithm that is (by nature) unaware of the constraints the data is subject to may indeed successfully capture the sensitivity of the solution to the model parameters. This has nevertheless raised our attention on one particular aspect of the relation between machine learning algorithms and optimization algorithms. When we apply a supervised learning algorithm to search in a hypothesis space based on data that satisfies a known set of constraints, can we guarantee that the hypothesis that we select will make predictions that satisfy the constraints? Can we at least benefit from our knowledge of the constraints to eliminate some hypotheses while learning and thus hope that the selected hypothesis has a better generalization error? In the second part of this thesis, where we try to answer these questions, we propose a generic extension of tree-based ensemble methods that allows incorporating incomplete data but also prior knowledge about the problem. The framework is based on a convex optimization problem allowing to regularize a tree-based ensemble model by adjusting either (or both) the labels attached to the leaves of an ensemble of regression trees or the outputs of the observations of the training sample. It allows to incorporate weak additional information in the form of partial information about output labels (like in censored data or semi-supervised learning) or -- more generally -- to cope with observations of varying degree of precision, or strong priors in the form of structural knowledge about the sought model. In addition to enhancing the precision by exploiting information that cannot be used by classical supervised learning algorithms, the proposed approach may be used to produce models which naturally comply with feasibility constraints that must be satisfied in many practical decision making problems, especially in contexts where the output space is of high-dimension and/or structured by invariances, symmetries and other kinds of constraints. [less ▲]

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See detailMachine Learning Solution Methods for Multistage Stochastic Programming
Defourny, Boris ULg

Doctoral thesis (2010)

This thesis investigates the following question: Can supervised learning techniques be successfully used for finding better solutions to multistage stochastic programs? A similar question had already been ... [more ▼]

This thesis investigates the following question: Can supervised learning techniques be successfully used for finding better solutions to multistage stochastic programs? A similar question had already been posed in the context of reinforcement learning, and had led to algorithmic and conceptual advances in the field of approximate value function methods over the years. This thesis identifies several ways to exploit the combination "multistage stochastic programming/supervised learning" for sequential decision making under uncertainty. Multistage stochastic programming is essentially the extension of stochastic programming to several recourse stages. After an introduction to multistage stochastic programming and a summary of existing approximation approaches based on scenario trees, this thesis mainly focusses on the use of supervised learning for building decision policies from scenario-tree approximations. Two ways of exploiting learned policies in the context of the practical issues posed by the multistage stochastic programming framework are explored: the fast evaluation of performance guarantees for a given approximation, and the selection of good scenario trees. The computational efficiency of the approach allows novel investigations relative to the construction of scenario trees, from which novel insights, solution approaches and algorithms are derived. For instance, we generate and select scenario trees with random branching structures for problems over large planning horizons. Our experiments on the empirical performances of learned policies, compared to golden-standard policies, suggest that the combination of stochastic programming and machine learning techniques could also constitute a method per se for sequential decision making under uncertainty, inasmuch as learned policies are simple to use, and come with performance guarantees that can actually be quite good. Finally, limitations of approaches that build an explicit model to represent an optimal solution mapping are studied in a simple parametric programming setting, and various insights regarding this issue are obtained. [less ▲]

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See detailModelling Transient Air-water Flows in Civil and Environmental Engineering
Kerger, François ULg

Doctoral thesis (2010)

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See detailSynthèse et caractérisation de nanomatériaux fonctionnels siliciques structurés à l’aide de micelles complexes de copolymères séquencés doublement hydrophiles
Warnant, Jérôme ULg

Doctoral thesis (2010)

This study focused on the design and development of new structuring agents of silica constituted of induced and reversible assemblies of original copolymers, the double hydrophilic block copolymers (DHBC ... [more ▼]

This study focused on the design and development of new structuring agents of silica constituted of induced and reversible assemblies of original copolymers, the double hydrophilic block copolymers (DHBC). The first system studied consists of a neutral-anionic DHBC PAPEO-b-PAA ou poly(acrylate methoxy poly (ethylene oxide))-b-poly (acrylic acid). The PAA block is a weak polyacid with a degree of ionization depending on the pH. In aqueous solution and in a right pH range, the association of this copolymer with a weak polybase, an oppositely charged polyamine, such as an oligochitosan, leads to the formation of polyion complex micelles (PIC) with a core/corona structure. These micelles can direct the structure of highly organized inorganic materials with different types of mesostructures. In a second step, by adjusting the conditions of pH, ionic strength, it is possible to "control" the extraction of organic species to get functional porous materials able to trap species of charge opposite to the functionality. Organized materials are obtained because of a favourable balance of the interactions between organic and inorganic species. If a polyamine/silica interaction occurs at the expense of the interaction polyamine/DHBC, the mesostructuring process by the micelles is limited. A neutral-cationic DHBC PEO-b-PDMAEMA poly(ethylene oxide)-b-poly(2-(dimethylamine)ethyl) associated with an anionic PVS poly(vinyl sulfonic acid) polymer can play a dual role in the synthesis of silica materials: firstly managing the growth of silica particles by interacting with the silicates and secondly acting as a structuring agent in association with PVS, confering a mesostructuration to the material. Finally, a very promising approach allowed to encapsulate water-soluble and charged drugs in a material by using as silica complexing agent a complex between the drug and a DHBC. [less ▲]

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See detailLES PRODUCTIONS LITHIQUES DU PALÉOLITHIQUE MOYEN DE BELGIQUE : VARIABILITÉ DES SYSTÈMES D’ACQUISITION ET DES TECHNOLOGIES EN RÉPONSE À UNE MOSAÏQUE D’ENVIRONNEMENTS CONTRASTÉS
Di Modica, Kévin ULg

Doctoral thesis (2010)

LITHIC PRODUCTION FROM THE MIDDLE PALAEOLITHIC OF BELGIUM VARIABILITY OF RAW MATERIAL PROCUREMENT SYSTEMS AND TECHNOLOGIES AS A RESPONSE TO A MOSAIC OF CONTRASTING ENVIRONMENTS Belgium is noted for its ... [more ▼]

LITHIC PRODUCTION FROM THE MIDDLE PALAEOLITHIC OF BELGIUM VARIABILITY OF RAW MATERIAL PROCUREMENT SYSTEMS AND TECHNOLOGIES AS A RESPONSE TO A MOSAIC OF CONTRASTING ENVIRONMENTS Belgium is noted for its many ancient prehistoric sites which are spread over a limited geographic area. Despite its limited size, this area shows important regional contrasts in terms of topographic relief and availability of mineral resources. These factors in conjunction with important regional differences related to the types of sites represented (cave/open air) as well as the proximity and morphology of the available flint make this area favorable for the study of man's relationship with his environment. The connection between the Neanderthal populations and the types of environments encountered constitutes the focus of this study which is divided into four closely associated parts. The first part is devoted to environmental variation starting with the interface between the flint-rich plains of Middle Belgium and the deep valleys of Upper Belgium. Only a few kilometers separate these two contrasting environments. Chronological variations follow because quaternary sedimentation had as much impact on the accessibility of lithic resources as on site preservation. The history of the research from 1829 to the present is also addressed. The motives and constraints of the researchers are responsible for both the abundance of documentary evidence and for the extremely variable quality of these documents. The second part concerns the previously mentioned documentation. Artifacts attributable to the Middle Paleolithic have been recovered from 437 sites : 46 sites (16 major ones) are found in karstic contexts and 391 sites (31 major ones) are open air sites. The distribution of these sites is a direct result of taphonomic processes, circumstances of discovery, and choices made by the Neanderthals themselves. In particular, two environments were favored : the plains which have abundant flint resources and the caves of the Mosan Basin. Prehistoric Man's choice of sites appears to be linked to topographical position : plateaus or cliff tops overhanging small valleys were preferred. Chronological distribution is also examined. It notably shows an abundant documentation from the Beginning of the Weichselian Pleniglacial and an absence of occupation during the Lower Weichselien Pleniglacial It also shows a concentration of archaeological evidences related to the Middle Weichselian Pleniglacial which is very exceptional for Northwest Europe. Based on research to date, Scladina Cave (38.000 B.P.) gives the most recent date for Middle Palaeolithic industries and Betche-aux-Rochtes at Spy (36.000 B.P.) provides the date for the last Neanderthals. The third part consists of a detailed study of ten lithic industries and their environmental context. Several general tendencies were detected in the way Palaeolithic populations adapted their systems of acquisition and exploitation of rocks. Clear variations in the systems of acquisition and exploitation along a northwest/southeast gradient were noted. In Lower Belgium, the use of local flint pebbles was coupled with the importation of nuclei and flakes from Middle Belgium. In Middle Belgium, the available local flint was used almost exclusively. Recourse to other local rocks or to imports was very exceptional. In Upper Belgium, the importation of flint from Middle Belgium in combination with other locally available materials constituted the rule. These variations in the systems of raw material procurement generated diversity in terms of nature, morphology, conditioning, and availability of the nodules chosen by the knappers. These diverse parameters impacted the technical choices of the Neanderthals during the reduction or debitage stage. Other important regional differences were also observed. The sites of Upper Belgium exhibited economic options which manifested in the reduction of blocks (Trou du Diable at Hastière) and in extreme adaptations or manipulation of concepts of reduction such as those recognized in several refittings from Scladina Cave. The sites of Middle Belgium exhibited an extravagant use of the primary material and a strict expression of different concepts : mainly Levallois, also Discoid, and volumetric blade production (gisement paléolithique d'otrange, Obourg Canal). The fourth part is devoted to a discussion of the results and a preliminary comparison to the rest of Europe. The connection of the diversity in lithic productions and the geographic position of the sites is particularly important. Lithic industries from the two occupation layers of Scladina (layers 5 and 1A) present more analogies between themselves than other plenicomtemporaneous sites in different environments (lays 1A of Scladina and WFL of Veldwezelt-Hezerwater). Other factors of variability superimpose themselves in this diverse region : function of the sites, cultural traditions and techniques, palaeoenvironmental variations, chronology. Comparisons with the results obtained from regions bordering Belgium as well as those obtained from greater distances showed some behavioural similarities in southern Europe in environments which evoke aspects of the karst valleys of the Mosan Basin. Translation : Cheryl Roy, Department of Anthropology, Faculty of Social Sciences, Vancouver Island University [less ▲]

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See detailOn the influence of indenter tip geometry on the identification of material parameters in indentation testing
Guo, Weichao ULg

Doctoral thesis (2010)

The rapid development of structural materials and their successful applications in various sectors of industry have led to increasing demands for assessing their mechanical properties in small volumes. If ... [more ▼]

The rapid development of structural materials and their successful applications in various sectors of industry have led to increasing demands for assessing their mechanical properties in small volumes. If the size dimensions are below micron, it is difficult to perform traditional tensile and compression tests at such small scales. Indentation testing as one of the advanced technologies to characterize the mechanical properties of material has already been widely employed since indentation technology has emerged as a cost-effective, convenient and non-destructive method to solve this problem at micro- and nanoscales. In spite of the advances in indentation testing, the theory and development on indentation testing are still not completely mature. Many factors affect the accuracy and reliability of identified material parameters. For instance, when the material properties are determined utilizing the inverse analysis relying on numerical modelling, the procedures often suffer from a strong material parameter correlation, which leads to a non-uniqueness of the solution or high errors in parameter identification. In order to overcome that problem, an approach is proposed to reduce the material parameter correlation by designing appropriate indenter tip shapes able to sense indentation piling-up or sinking-in occurring in non-linear materials. In the present thesis, the effect of indenter tip geometry on parameter correlation in material parameter identification is investigated. It may be helpful to design indenter tip shapes producing a minimal material parameter correlation, which may help to improve the reliability of material parameter identification procedures based on indentation testing combined with inverse methods. First, a method to assess the effect of indenter tip geometry on the identification of material parameters is proposed, which contains a gradient-based numerical optimization method with sensitivity analysis. The sensitivities of objective function computed by finite difference method and by direct differentiation method are compared. Subsequently, the direct differentiation method is selected to use because it is more reliable, accurate and versatile for computing the sensitivities of the objective function. Second, the residual imprint mappings produced by different indenters are investigated. In common indentation experiments, the imprint data are not available because the indenter tip itself shields that region from access by measurement devices during loading and unloading. However, they include information about sinking-in and piling-up, which may be valuable to reduce the correlation of material parameter. Therefore, the effect of the imprint data on identification of material parameters is investigated. Finally, some strategies for improvement of the identifiability of material parameter are proposed. Indenters with special tip shapes and different loading histories are investigated. The sensitivities of material parameters toward indenter tip geometries are evaluated on the materials with elasto-plastic and elasto-visoplastic constitutive laws. The results of this thesis have shown that first, the correlations of material parameters are related to the geometries of indenter tip shapes. The abilities of different indenters for determining material parameters are significantly different. Second, residual imprint mapping data are proved to be important for identification of material parameters, because they contain the additional information about plastic material behaviour. Third, different loading histories are helpful to evaluate the material parameters of time-dependent materials. Particularly, a holding cycle is necessary to determine the material properties of time-dependent materials. These results may be useful to enable a more reliable material parameter identification. [less ▲]

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See detailEtude biomecanique articulaire chez le cheval par tribometrie et analyse dynamique inverse
Noble, Prisca ULg

Doctoral thesis (2010)

In locomotor biomechanics, three groups of constraints are usually encountered : pressure, traction and torsion (Kamina, 2005). In supra-maximal conditions, all of these contraints would be responsible ... [more ▼]

In locomotor biomechanics, three groups of constraints are usually encountered : pressure, traction and torsion (Kamina, 2005). In supra-maximal conditions, all of these contraints would be responsible for some disease of equine locomotor systems (Radin et al., 1972 ; Radin, 1983 ; Smith et al., 2002). In order to understand better the constraints in the equine locomotor dynamics, some investigations have been carried out. Moreover, some measurement methods, based on the mechanics of Newton, have been performed. This work consists of three different experimental approaches: The first approach was an ex vivo micro-systemic model of the diarthrodial cartilage-cartilage contact : from osteochondral specimens in contact, dynamic frictional constraints were measured by tribometry using a pin-on-disc tribometer in Coulomb’s regime. The effects of age and load on the frictional response were studied. The second approach was an ex vivo macro-systemic model of the diarthrodial cartilage-cartilage contact : from whole fetlock joints fixed into an original pendulum tribometer and mobilized, dynamic visco-frictional constraints have been followed in viscous regime. The effect of a lipid solvent on the synovial fluid was studied. The third approach was an in vivo macro-systemic model of the diarthrodial cartilage-cartilage contact : from distal forelimbs, cinematic, cinetic and radiographic data have been collected, then tendon tensions and joint contact forces components were calculated using an inverse dynamic analysis. From a sensitivity analysis, the effect of raised hell (0°, 6°, 12°) were elucidated. In the first approach : (i) an original equine joint friction test model using a cartilage-on-cartilage arrangement (pin-on-disc) has been performed, (ii) cartilage ageing was found, under experimental operating conditions, to be responsible for an increase in friction coefficient, (iii) lubrication remained stable when young cartilage was loaded whereas lubrication of older cartilage was affected by increased load. In the second approach : (i) an original equine joint pendulum tribometer has been designed, (ii) visco-frictionnal data have confirmed the joint pendulum damping can be modelled like a harmonic oscillator fluid damping, (iii) the lipid solvent injection into the fetlock joint increased the visco-frictional parameters of the joint and the damping time decreased, suggesting that the lubrication capacity was compromised. In the third approach : (i) an original equine distal limb model with tendinous variable pulleys was described, (ii) polynomial relationships of second order between the variation of the dorsal angle of the fetlock joint and the moment arm variation of the deep digital and superficial digital flexors tendons have been established, (iii) the joint contact force components of the coffin joint and of the fetlock joint have been calculated during the phase of the trot, (iv) the effect of raised heel on the tendinous tensions and on the joint contact force components was established, suggesting that the use of heel wedges to reduce the loading of the coffin joint may in fact increase the loading of the fetlock joint. The two ex vivo equine articular models (tribometry) are some original and complementary mechanical analysis tools: the pin-on-disc tribometer may highlight the mechanical properties of the triplex cartilage-synovial fluid-cartilage that are related with the structural properties (contact surface), and the pendulum tribometer may clarify the mechanical properties of the articular lubricant in a very realistic intra-articular environment (quasi anaerobic). These two tools could be used to characterize the mechanical properties of some new articular prosthesis and lubricants in the future. Finally, the numerical in vivo model (dynamic inverse analysis), calculating dynamic tendinous tensions and dynamic joint contact force components in the equine distal forelimb, is equally a very interressing and original tool. Indeed, it measures some articular intrinsic informations, in non-invasive manner (no using of intra-articular and intra-tendinous constraint gaugues) and can be perfectly integrated in a classical equine locomotor analysis. [less ▲]

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See detailNon-invasive monitoring of water and solute fluxes in a cropped soil
Garré, Sarah ULg

Doctoral thesis (2010)

Although the influence of root water uptake on solute transport is commonly recognized as important, it has barely been studied throughout the literature. However, plants take up a big amount of the ... [more ▼]

Although the influence of root water uptake on solute transport is commonly recognized as important, it has barely been studied throughout the literature. However, plants take up a big amount of the infiltrating water and therefore they influence water flow patterns in the soil and concurrently solute transport processes. For this reason, experiments are required to investigate the relationship between plant root water uptake and flow field variability. Within this PhD project, we tried to elucidate the role of root water uptake on soil moisture distribution and solute transport in two undisturbed soil columns. During three consecutive experimental phases, the soil hydraulic and solute transport characteristics were investigated and the influence of growing barley on water content and tracer movement were studied. Soil water concentration and moisture content in the lysimeters were monitored non-invasively using 3-D electrical resistivity tomography (ERT). ERT is a valuable technique to monitor processes in the unsaturated zone. It is suitable to quantify solute concentration or soil moisture content at the decimeter scale in different soils and under varying conditions. In combination with TDR and effluent measurements, different aspects of the solute transport process and manifestations of preferential flow can be investigated. Steady-state step tracer experiments are very suitable for this purpose. Soil moisture measurements with ERT were conducted as well, but an horizon-specific in-situ calibration of the ERT-measurements for water content was a prerequisite for success. We observed that the solute transport in our silty lysimeters was considerably more heterogeneous than in the loamy-sand soil studied by Koestel (2008; 2009a; 2009b). We observed a clear preferential flow path in one of the lysimeters and found that soil layering had a big influence on the leaching process. The measured water depletion rate, being the result of combined effects of root water uptake and soil water redistribution during the barley experiment without irrigation, was compared with the evaporative demand and root length densities. We could observe a gradual downward movement of the maximum water depletion rate together with periods of redistribution when there was less transpiration. However, we were unable to make the distinction between soil water fluxes and root water uptake, since modeling of the soil water flow field using the time series of water content was not satisfying. We observed root growth at rhizotube surfaces and noted an increasing number of roots with depth. Since the minirhizotron measurements were only conducted at four depths and thus represent a small volume of the entire root zone, we estimated a root architecture model for the barley plants using RootTyp. We were able to set up a simple model, but to obtain better results, the effect of soil constraints and the process of re-iteration should be included. Many aspects of water flow and solute transport in the root zone need to be further investigated. The need for high-quality soil moisture data and simultaneous root architecture data remains. ERT is a promising technique to fill part of this gap, however some issues need to be solved before it can be used without difficulties. Next to measurements, the effort to improve our soil water flow models must be continued in order to improve the estimation of soil water fluxes. Only in this way, we will be able to measure root water uptake at the lysimeter and field scale. This is a necessary step towards a better understanding of the interactions in the soil-plant continuum. [less ▲]

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See detailImages radar des précipitations et durée d’humectation simulée pour l’évaluation des risques potentiels d’infection du blé d’hiver par la septoriose
Mahtour, Abdeslam ULg

Doctoral thesis (2010)

Summary - Weather-Radar Rainfall Measurement and Simulated Surface Wetness Duration for Septoria Leaf Blotch Risk Assessment. The persistence of free moisture on leaves, mainly as a result of ... [more ▼]

Summary - Weather-Radar Rainfall Measurement and Simulated Surface Wetness Duration for Septoria Leaf Blotch Risk Assessment. The persistence of free moisture on leaves, mainly as a result of precipitation in the form of rainfall or dew, plays a major role during the process of plant infection by most fungal pathogens. Acquiring rainfall and leaf moisture information is needed for accurate and reliable disease prediction and management. The objective of this research is to contribute to improve forecasting Septoria leaf blotch and other fungal pathogens on winter wheat in Belgium and Luxembourg. In the first part of this work, the potential of weather-radar rainfall estimates for plant disease forecasting is discussed. At first step, we focused on assessing the accuracy and limitations of radar-derived precipitation estimates, compared with rain-gauge data. In a second step, the Septoria leaf blotch prediction model PROCULTURE was used to assess the impact on the simulated infection rate of using, as input data, rainfall estimated by radar instead of rain gauge measurements. When comparing infection events simulated by PROCULTURE using radar-derived estimates and reference rain gauge measurements, the probability of detection (POD) of infection events was high (0.83 on average), and the false alarm ratio (FAR) of infection events was not negligible (0.24 on average). FAR decreased to 0 and POD increased (0.85 on average) for most stations, when the model outputs for both datasets were compared against visual observations of Septoria leaf blotch symptoms. Analysis of 148 infection events observed over three years at four locations showed no significant difference in the number of simulated infection events using either radar assessments or gauge measurements. This suggests that, for a given location, radar estimates are just as reliable for predicting infection events as rain gauges. As radar is able to estimate rainfall occurrence over a continuous space, unlike weather station networks that do observations at only a limited number of points, it has the great advantage of being able to predict the risk of infection at each point within an area of interest with an accuracy equivalent to rain gauge observations. This gives radar an important advantage that could significantly improve existing warning systems. In the second part, a physical model based on the energy balance, known as the Surface Wetness Energy Balance (SWEB), was applied for the simulation of Surface Wetness Duration (SWD) on winter wheat canopy. The model, developed in the United States on grapes canopies, was adapted for the winter wheat cultivars and was applied for use with agrometeorological data easily available from standard weather stations and weather-radar rainfall estimates. The SWEB model simulates surface wetness duration for both dew and rain events. The model was validated with data measured by sensors and with visual observations of SWD conducted in experimental plots during two cropping seasons in 2006 and 2007. The wetness was observed visually by assessing the presence or absence of surface water on leaves. Based on the results, the SWEB model appeared to underestimate surface wetness duration and especially for the dry-off events when compared statistically to visual observations. The error, on average, is generally less than 90 minutes. In order to establish a relationship between the surface wetness periods and Septoria leaf blotch development risk on the top three leaves, the SWEB model SWD outputs were compared with the number of hours of high probability of infection simulated by PROCULTURE as well as with visual plant diseases observations. A minimal surface wetness duration of favourable infection conditions for Septoria tritici was established. It is now required to develop an operational system that would integrate weather radar, surface wetness duration and foliar epidemic model. In this work, we have analyzed the advantages and limitations of the radar system as input to models and its ability for spatial interpolation of rainfall. We also tested the model for the determination of surface wetness periods required for Septoria Leaf Blotch Risk development. The proposed approach could be integrated in the existing system. Finally this approach shows once more the "happy marriage" between agrometeorology and plant disease management. [less ▲]

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See detailEffets des antibiotiques sur le procédé d'épuration par boues activées. Etude du cas de l'érythromycine, du floc bactérien au réacteur biologique
Louvet, Jean-Noël ULg

Doctoral thesis (2010)

This study examines the effect of erythromycin on activated sludge bacteria and the inhibition of the pollution removal in batch reactors treating urban wastewater. Results showed the importance of ... [more ▼]

This study examines the effect of erythromycin on activated sludge bacteria and the inhibition of the pollution removal in batch reactors treating urban wastewater. Results showed the importance of exposure time to erythromycin. Inhibition of nitrification and COD removal was measured during a 4 h period for erythromytcin concentrations higher than 1 mg/L. A 4 µg/L erythromycin concentration inhibited COD removal during a 20 h exposure time. The effect of erythromycin on nitrification was variable depending on the sludge origin. Erythromycin inhibited the specific nitrification rate with sludge from Nancy WWTP, but increased the nitrification rate at the other facility (Epinal WWTP). The cell lysis resulted in destruction of activated sludge flocs. Microscopic techniques (epifluorescence and confocal laser scanning microscopy (CLSM)), combined with a fluorescent viability indicator, allowed us to study erythromycin time-kill activity.Viability staining results showed a latency time before the lower antibiotic concentrations began to kill bacteria. This latency time could be related to antibiotic adsorption and diffusion into activated sludge flocs as well as the rate of bateria death. The effect of erythromycin according to the bacterial Gram type was investigated with 3-dimensional Confocal Laser Scanning Microscopy (CLSM) time-lapse imaging combined with a Gram and Viability staining. Gram+ bacteria had a higher mortality rate than the Gram- bacteria. This result suggests that antibiotic in wastewater could change the activated sludge bacteria composition according to their Gram type by selecting bacteria the less sensitive to the antibiotics. [less ▲]

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See detailcontribution à l'étude des paramètres pouvant influencer l'étanchéité des obturations adhésives en dentisterie conservatrice : évaluation des stress thermiques
Gueders, Audrey ULg

Doctoral thesis (2010)

La dentisterie a fortement évolué ces dernières années, notamment dans le domaine de la dentisterie adhésive. Les restaurations directes en composite, collées aux tissus dentaires, sont plus esthétiques ... [more ▼]

La dentisterie a fortement évolué ces dernières années, notamment dans le domaine de la dentisterie adhésive. Les restaurations directes en composite, collées aux tissus dentaires, sont plus esthétiques que les restaurations amalgames et sont devenues tout aussi fiables. La technique de thermocyclage est utilisée de manière courante dans les études dentaires in vitro. Cette technique a été utilisée dans le cadre de cette thèse de doctorat afin d'évaluer l'étanchéité de restaurations adhésives en résine composite. Plusieurs systèmes adhésifs ont été testés ainsi que différentes techniques de restaurations. [less ▲]

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See detailPaysage dans l’action, paysage en action(s). Développement territorial et processus de construction de projets locaux de paysage en Wallonie (Belgique).
Droeven, Emilie ULg

Doctoral thesis (2010)

The European Landscape Convention acknowledges landscape as a key element of territorial development, management and planning. At the same time there has been a rising public concern about landscape ... [more ▼]

The European Landscape Convention acknowledges landscape as a key element of territorial development, management and planning. At the same time there has been a rising public concern about landscape evolution and a strong social demand for high quality landscape. In scientific and institutional spheres, as well as within civil society, this has resulted in a growing interest for the everyday landscape and an enlargement of landscape concerns to larger spaces. Consequently a diversification of actors, with an interest in the definition and implementation of the landscape policies, has taken place. These evolutions in landscape concerns require land management and planning, thus permitting new action and research perspectives. Considering that landscape projects can favourably respond to these evolutions, this research, conducted with the support of the Standing Conference on Territorial Development of the Walloon Region, investigates the processes of landscape project design on a local scale in Wallonia (Belgium). The aim of the research is to analyze how action is being carried out in the context of landscape use. In order to do so, it develops a framework for characterizing and interpreting these observed processes. The specificity of the research is to examine the practical implementation of on-going landscape action. Based on the empirical analysis of nine case studies, taking place in Wallonia (Nature Parks, Local Action Groups, River Contracts), the research takes the form of an inductive, holistic, transdisciplinary and qualitative approach. The methods of investigation are a literature review, a stakeholder interview (project coordinator) and participant observation. The research emphasizes four dimensions of the landscape projects: rising and conception conditions (through actors and instruments of public action analysis), implemented actions and underlying social representations. Each enables the researcher to define characterization criteria and specific categories. In doing so, the research relates project contributions and limits assuming new landscape management challenges. In conclusion, it reframes the contribution of the landscape issue to regional development and outlines prospects for further action and research. [less ▲]

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See detailMeasuring Individual Brand Image Perceptions and Brand Reputation using Associative Networks: Theory and Implications for Consumer Goods
Brandt, Céline ULg

Doctoral thesis (2010)

This study specifically addresses the question of how associative networks contribute to brand image perception measurement to segment the market more effectively, as well as to demonstrate brand image ... [more ▼]

This study specifically addresses the question of how associative networks contribute to brand image perception measurement to segment the market more effectively, as well as to demonstrate brand image impairment. Carried out using surveys and experimental designs, this dissertation is positioned as part of the research stream on the use of associative networks in marketing, and particularly consumer mapping. Firstly, this study provides clear arguments for using brand concept maps (BCM) as highly suitable method to capture the complete brand image and segment the market based on brand perception. Secondly, thanks to BCM, the present research provide empirical evidences on the likelihood of brand image confusion, namely the dilution of attributes and the creation of unattractive associations, as a result of the introduction of a new brand. Thirdly, BCM captures the effect of exposure to negative user-generated content on the likelihood of doppelganger brand image, namely the appearance, or reinforcement, of negative associations at the brand reputation level. This work reveals that BCM is a superior approach to measure brand image and brand reputation, compared to dyadic methods. In addition, it broadens the applications of associative networks in marketing. Moreover this research shows how consumers and competitors may influence the brand image. Besides this scientific output, this research aims in providing brand mangers with an effective method to monitor and capture brand image and brand reputation. [less ▲]

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See detailÉtude et développement de techniques de métrologie de déplacements en lumière cohérente en infrarouge thermique
Vandenrijt, Jean-François ULg

Doctoral thesis (2010)

This thesis presents the works realised to apply ESPI and digital holography techniques at 10 µm for the monitoring of surface displacements of aerospace structures and space re- flectors. We consider ... [more ▼]

This thesis presents the works realised to apply ESPI and digital holography techniques at 10 µm for the monitoring of surface displacements of aerospace structures and space re- flectors. We consider objects with dimensions from a few tens of centimetres to more than one metre and with measurement ranges extending from a few micrometers to hundreds of micrometers. For specular surfaces where no diffusive coatings are allowed, we present the speckle pro- jection technique. We implement it in the special case of space reflectors. The use of a dif- fuser as the light source makes optical design much more simple and flexible than tradi- tional interferometric techniques. It allows use to consider its application on a wide range of form. We have also taken profit of the LWIR range to realise for the first time simultaneous dis- placement and temperature measurements with the same infrared detector. For this, we propose different computation techniques of the thermal image out of the phase shifted ESPI specklegram acquisitions. [less ▲]

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See detailModélisation spatiale des flux organiques et minéraux assurant la productivité durable des agroécosystèmes culture-élevage dans le sahel nigérien
Djaby, Bakary ULg

Doctoral thesis (2010)

Agriculture (including crop and livestock) employs more than 80% of the work force in semi-arid regions of West Africa and provide most of the food requirements and incomes. In most developing countries ... [more ▼]

Agriculture (including crop and livestock) employs more than 80% of the work force in semi-arid regions of West Africa and provide most of the food requirements and incomes. In most developing countries, soil nutrient depletion is a major issue for soil degradation. Crop-livestock integration is an effective means by which nutrients can be rapidly recycled within and between farms. In West Niger, where mixed farming systems dominate, livestock's role in recycling organic matter and mineral nutrients (nitrogen, phosphorus and potassium) must be better assessed to increase production and ensure sustainable food security. Nutrient flows through forage uptake and excretion deposit by grazing livestock must be assessed at a wider scale than the farm. Organic matter and nutrients balance and fluxes were used as measurable criteria for sustainable agriculture production. This research focuses on these indicators assessments at farm, land use unit and village level. This study was conducted in three agropastoral territories in the Fakara region of western Niger (Dantiandou District) that lies between the Niger River to the west and the Dallol Boboye (Bosso), a fossil valley tributary of the Niger, to the east. The area has homogeneous geological characteristics and rainfall conditions, but land use history, human and animal population density and cropping intensity vary within the region. 461 farms were concerned. In the mixed crop-livestock systems, the duality of the spatial organization, crop management at field level and livestock management with communal rangeland is a major issue for nutrients balance and fertility management modeling. Two models were then used to assess flows and nutrients balances. The NUTMON Toolbox developed by Dutch researchers is used to assess agricultural fluxes at farm parcels level. Spatial modeling was done with NUTPAST, a GIS tool developed in this thesis framework to assess livestock intake and excretion fluxes at land use scale. This tool takes into account the spatiotemporal patterns of vegetation as well as livestock seasonal variation. Quantile regression analysis and multinomial polytomous logistic regression modeling was used to assess soil fertility depletion risk indicator based on farm agriculture viability variables and nutrients partial balance. The results obtained show a less negative partial nutrients balance than in previous studies when the livestock spatio-temporal effect is taken into account. The results bring functional improvement and analytical evaluation of flows and partial nutrients balance calculation, while taking into account the functions of livestock in the organic matter recycling. The overall partial balance of N, P, K are 0.3 ± 0.6, 1.2 ± 0.2, 0.9 ± 0.5 kg/ha. The review highlighted a wide disparity between farms which show a strongly positive balance among livestock owners and negative balance among Fakara small farmers with few land and livestock endowments. Owning animals allows some households to maintain soil fertility by capturing and mobilizing soil nutrients. Risk indicators, based on land pressure indicator at 3x3 km geographic grid level, livestock endowments and land per capita reveal that despite a slow intensification, the trend for a risk of relative depletion of soil fertility is very high. This trend may compromise the sahelian agriculture sustainability. The problems of unequal benefit from communal resources remain a big issue of the sahelian agriculture. With increasing pressure on land, it is necessary to look beyond the traditional free range communal grazing systems to more intensive alternatives and stronger land tenure policies. [less ▲]

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See detailQuasi-Elastic Production at Hadronic Colliders
Dechambre, Alice ULg

Doctoral thesis (2010)

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of ... [more ▼]

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of hadronic remnants after the interaction. In view of the recent data from CDF Run II, we critically re-evaluated the standard approach to the calculation of quasi-elastic cross sections in the high-energy limit and evaluated the uncertainties that affect this kind of process. The main idea of this work was to understand the various ingredients that enter the calculation and the uncertainties coming from each of them. We studied and narrowed down these uncertainties using available data on dijets quasi-elastic event at the TeVatron. All the arguments developed apply to high-mass central systems and lead to a prediction of the Higgs quasi-elastic cross section at the LHC energies. [less ▲]

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See detailAnalysis of simple connections in steel structures subjected to natural fires
Hanus, François ULg

Doctoral thesis (2010)

Until recently, investigations on the fire resistance of steel joints have been neglected by structural engineers under the arguments that the design resistance of connections at room temperature is ... [more ▼]

Until recently, investigations on the fire resistance of steel joints have been neglected by structural engineers under the arguments that the design resistance of connections at room temperature is usually higher than the resistance of the connected members and that the temperature increases more slowly in the joint zone (high concentration of mass, low exposure to radiative fluxes) than in the adjacent beams and columns. However, brittle failures of connection components have been observed especially during the cooling phase of real fires for two main reasons: the high sensitive and non-reversible character of the resistance of bolts and welds at elevated temperatures and the development of high tensile thrusts. The present thesis is a contribution to the understanding of the thermo-mechanical behaviour of simple connections in steel beam-to-column joints subjected to natural fire conditions, with a special attention to the behaviour of these connections during the cooling phase. The distribution of temperature in joints has been analysed by use of numerical models built in SAFIR software. The simplified methods presently mentioned in the Eurocodes are discussed and new methods, calibrated on the results of numerical simulations, are proposed in the present work to predict the temperature profile in steel beams and joints covered by a flat concrete slab under fire. An existing method aimed at evaluating the distribution of internal forces in restrained steel beams (and by extension, in joints) under natural fire has been analysed in detail. Several modifications have been added in order to improve this method and to extend its field of application. The final version of this analytical method has been implemented and validated against numerical results. An experimental programme aimed at characterising the mechanical behaviour of bolts and welds under heating and subsequent cooling is described in the present thesis. The properties of the tested specimens, the thermal loading applied to these specimens, the test set-ups and the results of the tests are reported in detail. Mechanical models for bolts loaded in tension or in shear have been calibrated on the experimental results. The loss of resistance of bolts and welds due to their non-reversible behaviour under heating and subsequent cooling has been quantified. Finally, a large part of the thesis is dedicated to the development of component-based models representing the action of common simple connections under natural fire conditions and to the analysis of the behaviour of these connections as a part of a sub-structure or large-scale structure. These simple models can be used for parametric analyses because it conciliate a reasonable time of definition of the data, an acceptable time of simulation and a good degree of accuracy of the results. Recommendations for the design of connections have been defined. The ductility of connections has a major influence on the occurrence of connection failures and classes of ductility for connections, dependant of the fire loading, have been defined in this work. [less ▲]

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See detailHigher-Moment Equity Risk Premiums in Hedge Funds
Lambert, Marie ULg

Doctoral thesis (2010)

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See detailNul n'est censé être ignoré par le(s) droit(s). Politiques d'accès au droit et à la justice en Belgique et en France
Lejeune, Aude ULg

Doctoral thesis (2010)

My PhD dissertation seeks to describe and explain legal aid policies and practices in Belgium and France. The main focus lies on the relation between the mobilization of law and the institutional contexts ... [more ▼]

My PhD dissertation seeks to describe and explain legal aid policies and practices in Belgium and France. The main focus lies on the relation between the mobilization of law and the institutional contexts in which lawyers provide legal aid. This approach allows me to highlight the formation of innovative social and political mobilizations of law. This process is linked with recent social policies’ and, more broadly, public policies’ transformations. In my dissertation I suggest to break the deadlock between two types of opposite explanations of lawyering for the poor. On the one hand, macro-sociological explanations of legal aid transformations in occidental societies identified several waves of legal programs with little differences between the studied countries. On the other hand, micro-sociological approaches focused on the commitment conditions and choices of lawyering for the poor and disadvantaged. I rather lay emphasize on legal aid actors’ constraints, opportunities and resources in order to highlight both structures and agencies in legal practice. The first part of my dissertation is dedicated to a comparative and socio-historical outline of the transformation process the legal aid programs underwent in the past. During the second half of the 20th century the change of legal mobilizations and legal practices which target disadvantaged people correlated closely with the evolution of social policies. Particular attention is given to the progressive formation of non-professional groups, specialized in legal information and legal advice. I also analyze how these non-lawyers mobilize and refer to law. However, while innovative legal mobilization makes its appearance, old types of legal mobilization do not just vanish; this phenomenon makes legal mobilizations more diversified and complex. It also offers new opportunities for lawyers and non-lawyers to mobilize law in order to serve the disadvantaged. The examination of the lawyers and non lawyers’ strategies to be recognized as participants in legal aid policies constitutes the second part. I thereby analyze innovative social and political mobilizations of law how lawyers and local Bars attempt to preserve their professional jurisdiction as well as how non-legally-trained actors try to be recognized. The objective is to demonstrate empirically that the cooperation and the actors’ strategies can be fully understood by studying how lawyers and non-lawyers define legal mobilizations. Indeed, the actors’ main incertitude lies in defining which legal mobilizations are legitimate and which are not. The comparative approach of the thesis highlights peculiar national characteristics, particularly concerning the relationship among the State and “intermediate actors”, i.e. lawyers, Non-Governmental Organizations (NGOs) and, in France, local authorities (collectivités territoriales). In the legal aid sector, there are two models of governance. The French one relies on the delegation of social exclusion handling from the national state to NGOs and local authority. This process comes with a permanent control from the national state which seeks to preserve its authority to determinate policies in the legal sector. The Belgian one is based on the recognition of the lawyers’ activities by the State through a process I qualify as “mutual instrumentalization” between public authorities and intermediate actors. In the third part I analyze legal mobilizations in legal aid policies. Considering the translation of social problems into legal vocabulary as a political process, I contributed to the understanding of the relationship between lawyering and social change by underlying different ways of translations. Legal practices, professional belonging, and lawyers’ commitments are very heterogeneous. Nevertheless, I constructed a typology of legal mobilizations and legal practices. In a context where the transformation of social policies seeks to empower laypeople, lawyers are encouraged to intervene before litigations in order to pass “legal consciousness” on laypeople. Through this process, citizens could be able to defend and promote their rights in everyday life. In summary, my thesis underlines the tensions between the different kinds of legal mobilizations which refer to a specific definition of relationship between law and politics. [less ▲]

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See detailEffet de l’hypoxie sur la résistance des cellules cancéreuses à l’étoposide : Etude de l’apoptose et de l’autophagie
Cosse, Jean-Philippe ULg

Doctoral thesis (2010)

L’hypoxie tumorale est une caractéristique du microenvironnement de la plupart des tumeurs solides. Elle correspond à la faible tension en oxygène observée au niveau de certaines zones de la tumeur et est ... [more ▼]

L’hypoxie tumorale est une caractéristique du microenvironnement de la plupart des tumeurs solides. Elle correspond à la faible tension en oxygène observée au niveau de certaines zones de la tumeur et est la conséquence de la prolifération rapide des cellules tumorales et de la structure désordonnée de la tumeur et de sa vascularisation. L’hypoxie tumorale est souvent corrélée à un mauvais pronostic de guérison des patients car c’est un phénomène qui renforce l’agressivité des cellules cancéreuses et leur résistance à des thérapies anticancéreuses telles que la radiothérapie et la chimiothérapie. La résistance à la chimiothérapie est due à un effet direct de l’hypoxie, car les agents utilisés en chimiothérapie nécessitent souvent l’oxygène pour exercer leur cytotoxicité, et à un effet indirect de l’hypoxie qui induit une série d’adaptations au niveau de la cellule. L’hypoxie modifie le métabolisme de la cellule, stimule l’angiogenèse, l’érythropoïèse et régule la survie cellulaire en participant à la régulation de l’apoptose. La régulation de l’apoptose par l’hypoxie est complexe car en fonction de sa sévérité, l’hypoxie peut stimuler ou au contraire, inhiber l’apoptose. La compréhension de la régulation de l’apoptose par l’hypoxie est importante car l’apoptose participe à la sélection des cellules tumorales les plus agressives et conditionne l’efficacité des agents cytotoxiques utilisés au cours de la chimiothérapie. Ce travail a pour objectif d’étudier les mécanismes de régulation de l’apoptose par l’hypoxie. Dans un premier temps, nous avons comparé l’effet de l’hypoxie sur l’apoptose induite par l’étoposide, qui est un agent cytotoxique utilisé pour traiter certains types de cancers, au niveau de trois lignées cancéreuses humaines provenant de trois organes différents. Nous avons montré que l’effet de l’hypoxie sur l’apoptose induite par l’étoposide était dépendant de la lignée cellulaire car l’hypoxie stimule l’apoptose induite par l’étoposide dans les cellules MCF7 alors qu’elle inhibe l’apoptose induite par l’étoposide dans les cellules HepG2. Ceci montre que la régulation de l’apoptose par l’hypoxie est un mécanisme complexe, qui ne dépend pas uniquement de la sévérité de l’hypoxie, mais également d’autres paramètres tels que la lignée cellulaire. Dans la suite du travail, nous avons étudié comment l’hypoxie était capable de protéger les cellules HepG2 de l’apoptose induite par l’étoposide. Pour cela, nous avons évalué l’implication de plusieurs facteurs de transcription. Les résultats ont mis en évidence que l’hypoxie protège les cellules HepG2 de l’apoptose induite par l’étoposide en inhibant le facteur de transcription p53 et en activant le facteur de transcription c-jun. Nous avons également évalué l’implication de l’autophagie qui est un processus cellulaire impliqué dans le recyclage des protéines de longue durée de vie et des organites ainsi que dans la survie et la mort cellulaire. En condition d’hypoxie, l’autophagie peut être induite par un mécanisme impliquant la protéine BNIP3. Nous avons montré que, dans les cellules HepG2, l’autophagie était induite par l’étoposide mais pas par l’hypoxie. Cependant, l’autophagie induite par l’étoposide a des conséquences différentes en fonction de la tension en oxygène puisque les résultats ont montré que l’autophagie favorise l’apoptose induite par l’étoposide en normoxie mais pas en hypoxie. Enfin, nous avons montré que BNIP3 n’influençait pas l’autophagie mais participait à la protection contre l’apoptose induite par l’étoposide en hypoxie. En conclusion, les résultats obtenus montrent que la régulation de l’apoptose par l’hypoxie est un phénomène complexe qui est dépendant de plusieurs paramètres dont la lignée cellulaire. De plus, ces résultats indiquent que, lorsque l’hypoxie protège de l’apoptose, cette protection résulte de plusieurs adaptations mises en place par l’hypoxie. Ces résultats sont importants car ils améliorent notre compréhension des phénomènes de résistance observés chez les patients. [less ▲]

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See detailDéveloppement d’un formalisme Arbitraire Lagrangien Eulérien tridimensionnel en dynamique implicite. Application aux opérations de mise à forme.
Boman, Romain ULg

Doctoral thesis (2010)

Dans le cadre de la simulation de procédés de mise à forme par la méthode des éléments finis, le formalisme Arbitraire Lagrangien Eulérien (ALE) permet de découpler le mouvement du maillage et de la ... [more ▼]

Dans le cadre de la simulation de procédés de mise à forme par la méthode des éléments finis, le formalisme Arbitraire Lagrangien Eulérien (ALE) permet de découpler le mouvement du maillage et de la matière. Pour de très grandes déformations, la qualité du maillage peut être ainsi améliorée sans avoir recours à une procédure de remaillage complexe et coûteuse. Un second domaine d'application du formalisme ALE est la simulation de procédés stationnaires pour lesquels le maillage peut rester fixe dans la direction de l'écoulement de matière. Ce type de maillage quasi eulérien permet de diminuer le nombre d'éléments finis du modèle numérique par rapport à une simulation lagrangienne classique. En conséquence, le temps de calcul est également réduit. Bien que le formalisme ALE ne soit pas nouveau, il est rarement utilisé en pratique. D'une part, les techniques de repositionnement de noeuds tridimensionnelles ne sont pas évidentes à mettre en oeuvre et, d'autre part, il n'existe pas de schéma de transfert de données précis adapté aux éléments finis à plus d'un point de Gauss tels que ceux utilisés en dynamique implicite. Cette thèse tente de combler ces deux lacunes: une méthode de repositionnement de noeud sur les surfaces libres du solide est présentée. Elle est très robuste et permet de conserver la forme des surfaces malgré le mouvement arbitraire du maillage. Concernant le transfert des données, un schéma de convection 3D précis au second ordre et utilisable pour des éléments finis à plusieurs points de Gauss est déduit d'un opérateur de projection. L'efficacité et la généralité de l'algorithme ALE qui en résulte sont ensuite démontrées sur une série d'applications de plus en plus complexes: impact d'une barre de Taylor, traction d'une barre d'Hopkinson, double extrusion, laminage, planage et profilage à froid. Dans chaque cas, les résultats ALE sont comparés avec des résultats lagrangiens traditionnels ainsi que des mesures expérimentales lorsque celles-ci sont disponibles. [less ▲]

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See detailEnjeux et dynamiques du Technology Assessment parlementaire. Science, technologie et innovation sur le chemin de la réflexivité
Delvenne, Pierre ULg

Doctoral thesis (2010)

L’auteur entreprend une analyse comparative, des années 1970 à nos jours, de plusieurs offices de « Technology Assessment (TA) parlementaire ». Ces institutions se chargent d’anticiper et d’évaluer quels ... [more ▼]

L’auteur entreprend une analyse comparative, des années 1970 à nos jours, de plusieurs offices de « Technology Assessment (TA) parlementaire ». Ces institutions se chargent d’anticiper et d’évaluer quels pourraient être les effets de la science, la technologie et l’innovation sur la société et leur traduction dans les processus décisionnels. L’ouvrage adopte une approche originale qui consiste à étudier les institutions de science, technologie et innovation comme des indicateurs pertinents d’un processus de transformation réflexive des structures centrales de la modernité. En suivant les chemins de développement des offices de Technology Assessment, Pierre Delvenne montre la complexité et la nature parfois contestée de l’évolution de la trajectoire de la modernité. A l’aide de neuf études de cas abondamment documentées, ce livre démontre que le chemin de la réflexivité reste toutefois difficile à emprunter pour les offices de TA. Même si ceux-ci ont dû, dès le début, franchir des frontières entre science, technologie et société, ils continuent à évoluer dans un paysage d’institutions modernistes et à affronter par ailleurs les obstacles inhérents à la nature du régime de science et d’innovation. Soucieux également des raisons qui empêchent l’émergence d’un TA dans un régime d’innovation, l’auteur prend l’exemple de la Wallonie — qui aujourd’hui ne comporte pas de TA institutionnalisé — et met en évidence l’importance pour les élites politiques de se doter d’outils pour penser la science et la technologie en société. [less ▲]

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See detailLes citoyens et le fédéralisme. Perceptions et préférences fédérales en Belgique et au Canada
Reuchamps, Min ULg

Doctoral thesis (2010)

This doctoral dissertation aims at studying the relationships between the perceptions of federalism and the preferences for its future, through deliberative citizens panels which offer beter informed ... [more ▼]

This doctoral dissertation aims at studying the relationships between the perceptions of federalism and the preferences for its future, through deliberative citizens panels which offer beter informed opinions and through a comparison of four fields of investigation whose dynamics converge and diverge. The rationale of this endeavour is twofold. On the one hand, studies – which are usually quantitative – on the opinions about federalism focus mainly on a few dimensions, leaving aside a deeper investigation of all the factors at stake. A qualitative approach may therefore offer a more comprehensive understanding of the relations between perceptions and preferences. On the other hand, such an analysis of the citizens’ opinions and especially of the diversity of their positions on this issue bears the potential to shed light on the federal dynamics in their country. This endeavour seems even more fruitful that it compares four political contexts where the future of federalism is persistently a hot topic. To fulfil this objective, a specific method – the deliberative citizens panels – was developed in order to collect beter informed opinions through a dual process of information and interaction, across the four different fields: Liège in French-speaking Belgium, Antwerp in Dutch-speaking Belgium, Kingston in English-Canada and Montréal in Québec. To do so, the thesis is divided in three parts. The first part puts forward the general and the methodological framework of the research. Thus, chapter 1 presents the origins, the formation and the evolution of federalism in Belgium and in Canada. On this background, chapter 2 builds the method and the methodology behind the deliberative citizens panels. The second part explores each specific field in order to draw from the empirical data several ideal types which summarize the different visions of federalism. Chapters 3 and 4 present the results respectively of the French-speaking Belgium panel and the Dutch-speaking Belgium panel while chapters 5 and 6 analyze the data gathered in the English-speaking Canada panel and the Québec panel. The third and last part concludes the dissertation. Chapter 7 compares the ideal types and offers a rich four-faced comparison. The conclusions assess the methodology of the research as well as its results. Finally, on this basis, new avenues of research are highlighted. [less ▲]

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See detailENZYMATIC PRODUCTION OF PURIFIED ISOMALTOOLIGOSACCHARIDES PREBIOTIC PREPARATIONS AND THEIR FULL QUALITATIVE AND QUANTITATIVE CHARACTERIZATION
Goffin, Dorothée ULg

Doctoral thesis (2010)

Prebiotics are non-digestible food ingredients that beneficially affect the host health by stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and moreover can have ... [more ▼]

Prebiotics are non-digestible food ingredients that beneficially affect the host health by stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and moreover can have systemic effects on metabolism regulation. Recent studies have pointed out the certain links between their structure (DP, types of linkage, sequence) and the specificity and intensity of their effects on host health. Therefore, the knowledge of the exact composition of prebiotic preparations has become a crucial step in the development of new products. Amongst these prebiotics, isomaltooligosaccharides (IMO), produced enzymatically from hydrolyzed starch, are the most developed in Asia thanks to their many favourable properties for application in food industry. However, their full characterization hasn’t been achieved yet. In the present thesis, an HPAEC-PAD method has been set up in order to quantify the IMO present in syrups. Moreover, this step-forward analytical method permitted us to point out the presence of unknown IMO. Two structural determination methods were then set up and applied. PGC-LC-ESI-IT-MS2 including a chromatographic separation on a porous graphitized carbon column and producing MS2 fragment ion profiles specific to the linkage position proved to be promising but delicate for certain combination of linkage, while 1D and 2D NMR experiments give unambiguous structural determinations but need a preliminary chromatographic preparation step. Moreover, two enzymes from different families (a glucosyl-transferase and an α-glucosidase) were tested on maltose individually or in combination. The IMO kinetics of formation and mixtures obtained were compared with a view to produce IMO preparations with singular profiles. Finally, a new original method was set up to convert deleterious digestible saccharides, present in IMO preparations, into gluconic acid which presents various advantageous techno-functional properties as well as nutritional properties, in particular, prebiotic. [less ▲]

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See detailCost Effectiveness and Complexity Assessment in Ship Design within a Concurrent Engineering and "Design for X" Framework
Caprace, Jean-David ULg

Doctoral thesis (2010)

Decisions taken during the initial design stage determine 60% to 95% of the total cost of a product. So there is a significant need to concurrently consider performance, cost, production and design ... [more ▼]

Decisions taken during the initial design stage determine 60% to 95% of the total cost of a product. So there is a significant need to concurrently consider performance, cost, production and design complexity issues at the early stages of the design process. The main obstacle to this approach is the lack of convenient and reliable cost and performance models that can be integrated into a complex design process as is used in the shipbuilding industry. Traditional models and analysis methods frequently do not provide the required sensitivity to consider all the important variables impacting performance, cost, production and ship’s life cycle. Our challenge is that achieving this sensitivity at the early design stage almost requires data available during the detail design analysis. The traditional design methods do not adequately include, early enough, production and life cycle engineering to have a positive impact on the design. Taking an integrated approach throughout the life cycle of the ship and using concurrent engineering analysis tools can improve these traditional design process weaknesses. Innovation is required in structural design and cost assessment. The use of design for X, and particular design for production and cost schemes, during the design is the solution: to reduce failure during a ship’s life caused by design misconception, to reduce the overall design time and to shorten the build cycle of ships, to enlarge the number of design alternatives during the design process. The author has developed some assessment methods for cost effectiveness and complexity measurements intended to be used by ship designers for the real time control of cost process. The outcome is that corrective actions can be taken by management in a rather short time to actually improve or overcome predicted unfavourable performance. Fundamentally, these methods will provide design engineers with objective and quantifiable cost and complexity measures making it possible to take rational design decisions throughout the design stages. The measures proposed in this PhD are based on several techniques like decision analysis, data mining, neural network, fuzzy logic. They are objective facts, which are not dependent on the engineer’s interpretation of information, but rather on a model generated to represent the ship design. The objectivity aspect is essential when using the complexity and cost measures in a design automation system. Finally, with these tools, the designers should obtain well-defined and unambiguous metrics for measurement of the different types of cost effectiveness and complexities in engineered artefacts. Such metrics help the designers and design automation tools to be objective and perform quantitative comparisons of alternative design solutions, cost estimation, as well as design optimization. In this PhD, these metrics have been applied and validated with success in real industrial conditions on the design of passenger ships. [less ▲]

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See detailImpact of climate change on groundwater reserves
Goderniaux, Pascal ULg

Doctoral thesis (2010)

Estimating the impacts of climate change on groundwater represents one of the most difficult challenges faced by water resources specialists. One difficulty is that simplifying the representation of the ... [more ▼]

Estimating the impacts of climate change on groundwater represents one of the most difficult challenges faced by water resources specialists. One difficulty is that simplifying the representation of the hydrological system, or using too simple climate change scenarios often leads to discrepancies in projections. Additionally, these projections are affected by uncertainties from various sources, and these uncertainties are not evaluated in previous studies. In this context, the objective of this study is to provide an improved methodology for the estimation of climate change impact on groundwater reserves, including the evaluation of uncertainties. This methodology is applied to the case of the Geer basin catchment (480 km²) in Belgium. A physically-based surface-subsurface flow model has been developed for the Geer basin with the finite element model HydroGeoSphere. The simultaneous solution of surface and subsurface flow equations in HydroGeoSphere, as well as the internal calculation of the actual evapotranspiration as a function of the soil moisture at each node of the defined evaporative zone, improve the representation and calibration of interdependent processes like recharge, which is crucial in the context of climate change. Fully-integrated surface-subsurface flow models have recently gained attention, but have not been used in the context of climate change impact studies. This surface-subsurface flow model is combined with advanced climate change scenarios for the Geer basin. Climate change simulations were obtained from six regional climate model (RCM) scenarios assuming the SRES A2 greenhouse gases emission (medium-high) scenario. These RCM scenarios were statistically downscaled using two different methods: the 'Quantile Mapping Biased Correction' technique and a 'Weather Generator' technique. Both of them are part of the most advanced downscaling techniques. They are able to apply corrections not only to the mean of climatic variables, but also across the statistical distributions of these variables. This is important as these distributions are expected to change in the future, with more violent rainfall events, separated by longer dry periods. The 'quantile mapping bias-correction' technique generate climate change time series representative of a stationary climate for the periods 2011-2040, 2041-2070 and 2071-2100. The 'CRU' weather generator is used to generate a large number of equiprobable scenarios simulating full transient climate change between 2010 and 2085. All these scenarios are applied as input of the Geer basin model. The uncertainty is evaluated from different possible sources. Using a multi-model ensemble of RCMs and GCMs enables to evaluate the uncertainty linked to climatic models. The application of a large number of equiprobable climate change scenarios, generated with the 'weather generator', as input of the hydrological model allows assessing the uncertainty linked to the natural variability of the weather. Finally, the uncertainty linked to the calibration of the hydrological model is evaluated using the computer code 'UCODE_2005'. The climate change scenarios for the Geer basin model predict hotter and drier summers and warmer and wetter winters. Considering the results of this study, it is very likely that groundwater levels and surface flow rates in the Geer basin will decrease. This is of concern because it also means that groundwater quantities available for abstraction will also decrease. However, this study also shows that the uncertainty surrounding these projections is relatively large and that it remains difficult to state on the intensity of the decrease. [less ▲]

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See detailLilia florent : l’imaginaire politique et social à la cour de France durant les premières Guerres d’Italie (1494-1525)
Dumont, Jonathan ULg

Doctoral thesis (2010)

Ces dernières années, l’historiographie des premières Guerres d’Italie (1494-1525) s’est considérablement enrichie notamment grâce aux études de D. Le Fur, N. Hochner, A.-M. Lecoq et R. W. Scheller ... [more ▼]

Ces dernières années, l’historiographie des premières Guerres d’Italie (1494-1525) s’est considérablement enrichie notamment grâce aux études de D. Le Fur, N. Hochner, A.-M. Lecoq et R. W. Scheller. Croisant délibérément des sources variées (littéraires, politiques et iconographiques) ainsi que les méthodes (celle de l’historien des textes et celle de l’historien d’art), leurs travaux se sont attachés à définir les différents aspects du pouvoir royal et la manière dont celui-ci se met en scène tout spécialement sous les règnes de Charles VIII, de Louis XII et de François Ier. Force est donc de constater que la figure du roi de France domine l’historiographie récente des premières Guerres d’Italie. Pourtant, à chaque fois que les souverains des fleurs de lys sont mis en scène, ils n’occupent pas seuls le discours politique. D’autres personnages, la France et les Français, apparaissent à côté d’eux. Le premier est dépeint, selon une tradition établie, comme un espace bénéficiant de qualités exceptionnelles. Lesdites qualités conditionnent la nature du deuxième personnage – les Français –, lequel s’intègre dès lors à un portrait de la nation. Durant les Guerres d’Italie, ce discours sur la France et les Français ne sert pas uniquement à décrire le royaume lui-même. Il permet avant tout aux artisans de la propagande royale d’élaborer une pensée légitimant la conquête de l’Italie et permettant d’y imposer une nouvelle culture politique et sociale d’inspiration française. Cet amalgame d’images à propos de l’Italie française ou Franco-Italia traverse l’ensemble de la période, croisant parfois la figure royale, mais s’en éloignant aussi très souvent. L’étude d’une telle idéologie révèle enfin un intérêt supplémentaire. Au cours des premières décennies du XVIe siècle, la France connaît un véritable bouleversement de son modèle d’organisation sociale traditionnel. Nous voulons parler des trois ordres du féodalisme (oratores, bellatores et laboratores). Certes, dans la réalité quotidienne, le système ternaire ne reflète plus, depuis des siècles, la complexité des relations politiques et sociales. Par contre, la remise en cause de ce modèle au sein de la pensée politique curiale, en somme dans la culture de l’élite, est une donnée relativement nouvelle en ce début de XVIe siècle. Ainsi, le discours sur l’Italie française sert de champ d’expérimentation aux théoriciens du politique, aux polémistes ainsi qu’aux chroniqueurs et même aux poètes, leur permettant de redéfinir les contours d’un schéma ternaire qui, dans sa forme traditionnelle, leur apparaît désuet. On l’aura compris : notre thèse s’oriente donc vers l’étude, non d’un seul mode de pensée, mais plutôt d’une pluralité de concepts et d’opinions ayant comme dénominateur commun la redéfinition des contours de l’Italie et également de la France. Il s’agira de comprendre la manière dont les auteurs de la cour de France regardent la Péninsule et ses habitants et comment, de cette expérience de l’altérité, ils en arrivent à pratiquer un retour sur eux-mêmes et à relire leur propre mode d’organisation sociale, autrement dit, les cadres théoriques de leur existence. Cette histoire des lys qui s’évertuent à fleurir dans les champs d’une Italie pourtant bien décidée à les faucher sera l’occasion d’entrevoir sous un angle neuf cette période de bouleversements et d’inquiétudes que sont les premières Guerres d’Italie. [less ▲]

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See detailEssays in Empirical Finance: Portfolio Risk and Performance Management
Bodson, Laurent ULg

Doctoral thesis (2010)

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See detailEvaluation économique de la prise en charge de l'ostéoporose
Hiligsmann, Mickaël ULg

Doctoral thesis (2010)

Health economic evaluation is a method for evaluating the value for money of medical technologies by comparing alternative options in terms of their costs and consequences. This method is frequently used ... [more ▼]

Health economic evaluation is a method for evaluating the value for money of medical technologies by comparing alternative options in terms of their costs and consequences. This method is frequently used to inform decision makers about how to allocate scarce resources. Economic evaluation has become increasingly important nowadays, with the increasing health care expenditures, the rapid introduction of new medical technologies, and the extending role of economic evaluations in health care decision making. Osteoporosis becomes an increasingly major health problem around the world. It is a disease characterized by low bone mass with microarchitectural disruption and increased skeletal fragility, leading to increased fracture risk. Osteoporotic fractures result in significant morbidity and mortality, and impose a huge financial burden on health care systems. Financial resources are used to prevent, diagnose and treat osteoporosis. These resources must be allocated in an efficient manner. The general purpose of this thesis is therefore to contribute to the economic evaluation of osteoporosis management. More specifically, this thesis is divided into four parts. The first part is devoted to the development and the validation of a new Markov microsimulation model. This modelling approach accurately encompasses the complexity of osteoporosis, increasing the reliability of the results. The second part estimates the cost-effectiveness of osteoporosis screening strategies and provides recommendations for their implementation. The third part estimates the cost-effectiveness of new anti-osteoporotic therapies (strontium ranelate and denosumab). It is important to assess whether new drugs represent a good value for money compared to the relevant alternatives. Finally, the last part of the thesis investigates the clinical and economic implications of non-adherence to osteoporosis medications. This thesis provides new information on the cost-effectiveness of osteoporosis management, which may be useful to inform decisions makers about resources allocation for patients with osteoporosis. The results may also be used to raise awareness among public health authorities, the medical profession and the general population regarding the burden of osteoporosis, the importance of screening and adequate follow-up, as well as to the role of economic evaluation in health care decision making. [less ▲]

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See detailEtude de l'hydrodynamique dans une colonne de distillation réactive: Mesure de la distribution des phases par tomographie à rayons X.
Aferka, Saïd ULg

Doctoral thesis (2010)

Le mémoire concerne l’étude de l’hydrodynamique des écoulements dans des lits fixes parcourus par un écoulement à contre courant de gaz et de liquide. Il est plus particulièrement consacré à l’analyse par ... [more ▼]

Le mémoire concerne l’étude de l’hydrodynamique des écoulements dans des lits fixes parcourus par un écoulement à contre courant de gaz et de liquide. Il est plus particulièrement consacré à l’analyse par tomographie à rayons X de la distribution spatiale des phases liquide et solide dans des empilages de distillation et de distillation réactive. Le principe de la distillation réactive est de réaliser, dans une même colonne, une réaction chimique exothermique et la séparation des produits par distillation. L’industrie chimique marque beaucoup d’intérêt pour ce type d’appareil en raison des nombreux avantages qu’il offre : une réduction des investissements, puisqu’un seul appareil est utilisé au lieu de deux ; une très grande intégration énergétique des étapes de réaction et de séparation, puisque la chaleur générée par la réaction est directement utilisée pour la distillation ; la possibilité d'augmenter la conversion dans le cas des réactions limitées à l'équilibre ; … Les empilages utilisés en distillation réactive présentent généralement une structure modulaire. Chaque élément comporte une ou plusieurs zones catalytiques, dans lesquelles la réaction se déroule et une ou plusieurs zones de séparation, où la distillation peut être réalisée. Vu la structure extrêmement complexe de ces empilages, la compréhension et la description des écoulements en leur sein sont des tâches particulièrement ardues que très peu d’équipes de recherches ont entamées jusqu’à présent. Le but du présent travail de thèse est de collecter une information expérimentale aussi précise et aussi complète que possible, permettant de déterminer les mécanismes hydrodynamiques qui interviennent dans les empilages de distillation réactive. La tomographie à rayons X est utilisée pour mesurer la distribution des phases à différentes échelles, depuis l’échelle locale des détails de l’empilage, jusqu’à l’échelle de la colonne dans son ensemble. Les résultats obtenus permettent non seulement de quantifier les grandeurs hydrodynamiques macroscopiques comme la rétention ou l’aire interfaciale mais, ils permettent également et surtout d’expliquer leur évolution en fonction de la structure de l’empilage et des conditions opératoires. [less ▲]

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