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

Doctoral thesis (2014)

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

Le thèse examine l'articulation tant "procédurale" que "substantielle" des droits fondamentaux, garantis par des dispositions tant constitutionnelles que conventionnelles, et protégés par de multiples juges, tant nationaux qu'européens. [less ▲]

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

Certaines tendinopathies (l’épicondylite, les tendinopathies d’Achille et rotulienne proximale ou Jumper’s knee) présentent une évolution désespérément rebelle et ce, malgré l’instauration de traitements ... [more ▼]

Certaines tendinopathies (l’épicondylite, les tendinopathies d’Achille et rotulienne proximale ou Jumper’s knee) présentent une évolution désespérément rebelle et ce, malgré l’instauration de traitements « classiques » ; différentes thérapeutiques, régulièrement utilisées (repos, orthèse, AINS locaux ou per os, électrothérapie, kinésithérapie, mésothérapie, infiltration de corticoïdes, ondes de choc, intervention chirurgicale…), ne brillent guère par leur efficacité… Dans le cadre d’épicondylites chroniques, certains travaux (avec ou sans contrôle échographique) rapportent, dans les suites d’une infiltration de sang autologue, une évolution favorable. Ce traitement permettait d’éviter une intervention chirurgicale. Diverses études soulignent les propriétés réparatrices des plaquettes qui, effectivement, pourraient accélérer la cicatrisation de différents tissus: os, muscles et tendons. Le plasma riche en plaquettes (platelet-rich plasma ou PRP) a initialement été utilisé en chirurgie maxillofaciale, en stomatologie et en chirurgie orthopédique. Cette technique pourrait représenter une thérapeutique d’avenir en médecine physique - traumatologie du sport. Mishra et Pavelko, les premiers, ont démontré que le PRP améliore la douleur de patients souffrant d’épicondylite chronique, rebelle aux traitements classiques. Les plaquettes contiennent divers métabolites et facteurs de croissance, libérés lors de leur dégranulation dans les suites de leur activation. Ces facteurs de croissance favoriseraient le remodelage tissulaire, la cicatrisation et l’angiogenèse. Actuellement, les effets du PRP restent toujours discutés voire controversés : les résultats cliniques sont parfois contradictoires même si son efficacité in vitro et sur animal apparait plus franche. Cette variabilité pourrait s’expliquer par l’absence de consensus relatif au mode de préparation du PRP, à la concentration plaquettaire (mais éventuellement aussi érythrocytaire et leucocytaire…), à la technique d’infiltration (activation ou non, avec ou sans contrôle échographique) et au protocole post-infiltration (repos, rééducation classique - excentrique…). Notre travail appréciera l’efficacité du PRP sur la cicatrisation tendineuse de l’animal et de l’homme souffrant, notamment de jumper’s knee chronique. Nous souhaiterions standardiser le protocole de recueil et de concentration plaquettaire et celui de la rééducation post-infiltration afin d’optimaliser son usage clinique. [less ▲]

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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See detailrecherche de nouvelles potentialités des bacteries du genre Bacillus pour l'agriculture et l'agroalimentaire
Ait Kaki, Asma ULg

Doctoral thesis (2014)

L’exploration des échantillons en provenance de divers environnements de l’Est Algérien (du lac salé de Ain M’lila et de la rhizosphère d’une plante adjacente ; de l’eau de la source thermale d’Oued El ... [more ▼]

L’exploration des échantillons en provenance de divers environnements de l’Est Algérien (du lac salé de Ain M’lila et de la rhizosphère d’une plante adjacente ; de l’eau de la source thermale d’Oued El-Athmanya et du sol environnant ; de la rhizosphère de la plante Calendula officinalis, cultivée en serre à Setif) a abouti à l’obtention de 39 isolats de Bacillus et de Paenibacillus, dont 28 % sont sélectionnés pour leur capacité à inhiber la croissance de certaines moisissures phytopathogènes comme : Alternaria alternata, Aspergillus niger, Botrytis cinerea, Cladosporium cucumerinium, Fusarium oxysporium et Fusarium sp. Le calcul du taux d’inhibition de la croissance fongique par les isolats sélectionnés, réalisé, à titre d’exemple, sur F. oxysporium et B. cinerea, a permis d’obtenir des valeurs variant entre 39% et 84% suivant l’isolat. L’identification moléculaire des isolats sélectionnés par l’analyse d’ADN-16S et du gène « gyrase-A » a montré que les isolats de Ain M’lila appartiennent à Bacillus amyloliquefaciens, ceux isolés d’Oued El Athmanya sont : B. amyloliquefaciens, B. atrophaeus et B. mojavensis, enfin, les bactéries isolées de la rhizosphère de C. officinalis, sont : Paenibacillus polymyxa, B. velezensis, B. amyloliquefaciens et B. subtilis subsp. spizezenii. Les souches de Bacillus sélectionnées développent, dans les conditions de culture en fioles, des taux de sporulation importants variant entre 8 .108 et 27.108 spores/ml., alors que, le taux de sporulation chez P. polymyxa est insignifiant. Seuls les isolats de B. amyloliquefaciens sont capables de produire de la protéase. Cependant, l’activité cellulasique est observée chez toutes les espèces de Bacillus étudiées exceptant le B. atrophaeus qui a été le seul à produire de la chitinase. Toutes les espèces étudiées ont les mêmes capacités à produire les trois familles de lipopeptides (iturines, fengycines et surfactine), les siderophores et l’indole 3 acide acétique (IAA). Toutefois, le P. polymyxa (18SRTS) produit, dans les conditions expérimentales, une meilleure concentration d’IAA (54µg/ml). Par ailleurs, il est à mettre en exergue que, les B. amyloliquefaciens isolés du lac salé et de la source thermale produisent de nouvelles variantes de fengycines. En effet, il a été mis en évidence que le B. amyloliquefaciens (ET), produit de nouveaux homologues de fengycines A et B, ayant des chaines d’acides gras à 20 et à 18 atomes de carbone, respectivement, et deux nouvelles variantes de fengycines (fengycine X et Y) à cycles peptidiques dont la structure diffère de celle des fengycines conventionnelles. L’activité antifongique de certains isolats (B. amyloliquefaciens (ET), B. atrophaeus (6SEL), B. mojavensis (9SEL), B. amyloliquefaciens (9SRTS) et B. subtilis subsp. spizezenii (23SRTS)) sur milieux gélosés à base d’exsudats racinaires de tomate, de courgette et d’haricot, obtenus à différentes températures a été observée, vis-à-vis d’Alternaria alternata et de F. oxysporium. En complément, les souches B. atrophaeus (6SEL), B. amyloliquefaciens (9SRTS) et B. subtilis sub sp spizezenii (23SRTS), ont fait l’objet d’une production industrielle avec un taux de survie, après lyophilisation, très appréciable et leurs test in situ en serre et en champs sur le pois chiche a révélé une capacité intéressante de biofertilisation, de phytostimulation et de biocontrôle, ce qui justifie largement l’objectif assigné à cette recherche. [less ▲]

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See detailAssessing tropical forage species used as pig feed ingredients in the western provinces of the Democratic Republic of the Congo
Kambashi Mutiaka, Bienvenu ULg

Doctoral thesis (2014)

The use of forage species to feed pig goes back to immemorial times. If forage is no longer used in industrial farms with genetically-improved breeds, its accounts for an important part of pig diets in ... [more ▼]

The use of forage species to feed pig goes back to immemorial times. If forage is no longer used in industrial farms with genetically-improved breeds, its accounts for an important part of pig diets in smallholder pig production systems in tropical areas including the Western provinces of the Democratic Republic of the Congo (DRC). The aim of this research thesis was to assess the relevancy of the use of local forage resources as a strategy to reduce reliance of pig production systems on concentrate feed ingredients in tropical environment, by identifying plant species available to smallholders with interesting nutritional value that could partly replace concentrates in the diets. First, smallholder pig production systems in two western provinces of the DRC were characterized and the most used forage species in pigs identified. Their nutritional value was determined using an in vitro model of the pig’s gastro-intestinal tract. It was concluded that Manihot esculenta, Ipomoea batatas, Moringa oleifera, and legume species exhibit an interesting profile for feeding pigs while grasses, Eichhornia crassipes, Acacia mangium and Cajanus cajan should be discouraged. Feeding values of Psophocarpus scandens, Vigna unguiculata, Stylosanthes guianensis, and Pueraria. phaseoloides were measured by assessing the voluntary feed intake of forage hays-based diets and their digestibility. Finally, the economic impact of feeding Psophocarpus scandens, Vigna unguiculata, and Stylosanthes guianensis, was measured through growth performance, carcass quality, and production costs determination. It is concluded that although forage species reduce the nutritive value and the growth of animals, the investigated legumes do not impact negatively the economical balance of concentrate-fed pigs when forage accounts for approx. 10 % of the diet. The ability of some forage species to improve performances of animals fed ill-balanced diets as usually practiced by smallholder farmers in the DRC should be investigated as it is suspected that under less favourable conditions, conclusions on the usefulness of forage legumes in pigs might be more positive [less ▲]

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See detailLa conditionnalité environnementale dans la politique agricole commune. Analyse de l'intégration de la politique de protection de l'environnement au sein de la politique agricole commune
Habran, Maxime ULg

Doctoral thesis (2014)

Pierre angulaire de la construction européenne, la politique agricole commune (PAC) est à l’origine mise en place dans le but d’assurer l’autosuffisance alimentaire de la Communauté européenne. L’objectif ... [more ▼]

Pierre angulaire de la construction européenne, la politique agricole commune (PAC) est à l’origine mise en place dans le but d’assurer l’autosuffisance alimentaire de la Communauté européenne. L’objectif, rapidement atteint, laisse dans son sillage des stocks et excédents considérables ainsi que des dépenses communautaires importantes. Le mode de production agricole basé sur un modèle productiviste montre rapidement ses limites, obligeant les Etats membres à une réorientation de la PAC. Cette politique sera modifiée et réformée à de nombreuses reprises. La reconnaissance de la protection de l’environnement comme politique transversale contraint les Etats membres à l’adapter. D’une politique productiviste, elle devient attentive aux considérations environnementales, intégrant ces dernières dans chacune des réformes, allant même jusqu’à lier l’octroi de paiement au respect de règles essentiellement environnementales. Cette recherche présente la manière dont s’articule la relation entre les deux politiques autour de la notion de conditionnalité environnementale. A travers une étude minutieuse de chaque réforme de la PAC, une analyse de transversalité permet de saisir les enjeux et les motivations de l’intégration environnementale. [less ▲]

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See detailComputation and approximation of the inverse of relationship matrices between genotyped animals: Algorithms and Applications
Faux, Pierre ULg

Doctoral thesis (2014)

The recent developments in molecular biology have made available thousands of genetic markers, allowing livestock genotyping at a reasonable cost and the subsequent development of genomic prediction. The ... [more ▼]

The recent developments in molecular biology have made available thousands of genetic markers, allowing livestock genotyping at a reasonable cost and the subsequent development of genomic prediction. The single-step procedure, a unified approach of genomic prediction, requires inversion of two matrices gathering additive relationships between genotyped animals: the genomic relationship matrix (G) and a part of the additive relationship matrix (A22). The inverse of A22 may also be interesting for other applications. Matrix inverse can be constructed successively by, first, computing, for each animal, the vector containing contributions of other animals to its relationship and, secondly, adding the product of each vector of contributions by itself to a zeroed matrix. The objectives of this thesis were (1) to propose algorithms to compute or to approximate the vector of contributions and (2) to test the numerical efficiency of these algorithms (computing speed, memory use and, if needed, approximation accuracy). Computing contributions covered two points: (1) finding or approximating which contributions are different from zero, and (2) computing the value of contributions considered as non-zero. In the first approach, we considered that animals closely related have non-zero contributions and approximated their values by linear regression. This approach was extended in a recursive way. In the second approach, we empirically determined the set of non-zero contributions by a heuristic algorithm of pedigree exploration (only for the case of A22). Values were then computed either by linear regression, or using the already computed inverse. We also tested an approximation strategy: limiting the number of extracted generations of non-genotyped ancestors to reduce pedigree complexity. In a third approach, we followed the same heuristic algorithm as before but restricted the pedigree exploration to find out which animals have a non-zero contribution. Their values were approximated by linear regression. The presentation of the different approaches is followed by a general discussion in which the approaches are compared. It was found that the best compromise between speed, memory and approximation accuracy was achieved by the last approach for the case of A22. Use of this last approach simplified computations and therefore made predictions more feasible. However, for the case of G, no sufficient approximations could be reach in a reasonable time. Perspectives of other uses of algorithms developed and of future researches were drawn, as well as practical perspectives for animal breeding. [less ▲]

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See detailAnalyse et stratégies de développement de l’agriculture familiale dans un pays post-conflit: cas de la Province de Kirundo au nord du Burundi
Minani, Bonaventure ULg

Doctoral thesis (2014)

The Burundian family farming is indeed at the center of solutions to food and nutrition insecurity prevailing in Burundi. The agricultural sector contributes more than 40 % of GDP and employs 90 % of ... [more ▼]

The Burundian family farming is indeed at the center of solutions to food and nutrition insecurity prevailing in Burundi. The agricultural sector contributes more than 40 % of GDP and employs 90 % of active people. Kirundo famers practiced family agriculture market-oriented. This region was formerly considered as the breadbasket of the country because it fed many regions in cereals and legumes. Before 1993, Kirundo was the second rural province who had fewer households (28 %) living under poverty line. Today, this agriculture is consuming-oriented. Over 60 % of households in Kirundo Province live in food and nutrition insecurity, and 83 % of people live under poverty line. The objective of this study is to analyse underpinning constraints which hinder the system production performance of the region, in order to formulate strategies which can boost the family farming in Kirundo Province. In that case, a survey was carried out among 355 farm households in seven municipalities of the province. The results of this study showed that 282 farmers (79% of respondents) have small farmland and / or land conflicts as barriers to the family agriculture development. Contrariwise, the study identified also the existence of 73 farmers (21% of respondents) who didn’t have the small farmland and/ or land conflicts as constraints to the performance of their production systems. These farmers were divided into two groups: the first group (group A) included 41 farmers who were unable to fully exploit their land while the second group (group B) included 32 farmers who had a higher agricultural productivity. Thus, a case study was conducted with the farmers to know the core constraints which are impeding the land profitability in the first group (group A), and in other side, strategies implemented by other farmers in the group B to increase agricultural productivity. The results from this case study show that farmers partially exploiting their lands have an average area equivalent to 1.6 hectares per household, but only the third of this area is exploited. The crop yields (coffee, bananas, beans, maize, cassava, rice, sorghum, sweet potatoes, etc.) were lower than those observed at the national level. The main constraints of their lower production system performance are: the lack of agricultural workforce, this is lower because ( i) the rural exodus and early marriage of their children and departure of the household headers for seeking employment in Rwanda or in other family farms neighboring the regions, (ii) the lack of agricultural inputs, (iii) the lack of agricultural equipments, (iv) the use of moneylenders, (v) the insufficient erosion control techniques, (vi) the high rate of illiteracy,(vii) the poor distribution of organic manure between banana trees and other food crops, (viii) the persistence of traditional agro-pastoral techniques, (ix) the high animal mortality, (x) the low rate of households with fields in the lowlands and marshes, and (xi) the lack other opportunities outside the agricultural sector. Moreover, the strategies used by farmers with higher agricultural productivity for increasing the technical and economic performance of their production systems are: (i) the high rate of technology adoption (for erosion control, crop fertilization and pest management), (ii) the social development through the membership in local development associations well-structured and organized , (iii) the rational distribution of organic manure between banana trees and food crops , (iv) the application of modern agro- pastoral techniques, (v) the renewal of agricultural tools, (vi) the high rate of households with fields in the lowlands or marshes where they practice rice and other foods crops, (vii) the high literacy rate, (viii) the using of banks for credit, and (ix) the development of non-farm activities such as trade and crafts. The author concludes his study by recommending the development of non-farm activities, training farmers in modern agricultural techniques, the renewal of agricultural tools, the practices of food crops in the lowlands and marshes, and the development of small ruminants through the introduction of improved animal races and the practice of zero grazing as strategies to develop family farming in Kirundo Province. [less ▲]

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See detailImprovement of data quality for Diffusion Kurtosis Imaging and application to clinical neurological research
André, Elodie ULg

Doctoral thesis (2014)

Understanding human brain function and dysfunction is one of the major challenges of our century. One of the most popular methods to achieve this goal is in vivo magnetic resonance imaging. In particular ... [more ▼]

Understanding human brain function and dysfunction is one of the major challenges of our century. One of the most popular methods to achieve this goal is in vivo magnetic resonance imaging. In particular, diffusion-weighted (DW) imaging has become a standard tool to non-invasively study white matter structure in vivo. The main contributions of this work can be divided in two parts. The first part deals with the development of pre-processing methods to improve image quality and the accuracy of diffusion tensor and diffusion kurtosis-derived parameters. First, we describe and evaluate a novel method to correct data misalignment due to subject motion. Using an iterative model-based ap- proach, individual diffusion images are realigned to their own theoretical pair, rather than to the unweighted image. A recently developed advanced measure of tensor distance was used as a stopping criterion. The accuracy of the method is tested via a simulated diffusion tensor imaging data set. We have shown here that our procedure is a reliable and efficient way to correct subject motion during DW acquisitions, and that with a proper acquisition setup, it performs better than standard coregistration procedures. Next, we studied the influence of noise in diffusion kurtosis imaging. Two noise correction approaches are proposed and applied to a pool of 25 sub- jects to evaluate inter-subject variability and the impact of noise correc- tion. Additionally, data were acquired on a single subject with different head positions within the coil and different acquisition scheme to evaluate the impact of noise correction on within-subject variability. Results show a strong impact of noise correction on the estimated mean kurtosis, while the estimation of fractional anisotropy and mean diffusivity were less affected. Both within- and between-subject signal-to-noise (SNR) related variability of the mean kurtosis estimate is considerably reduced after correction for the noise bias, leading to more accurate and reproducible measures. In this work, we have proposed a straightforward method that improves the accu- racy of diffusion kurtosis metrics. Diffusion kurtosis imaging acquisitions at higher spatial resolution are made possible, which increases the chances to make valuable inferences in group analysis.The second part of this thesis deals with a clinical application of these meth- ods. A large group of patients with early-stage Parkinson’s disease was in- vestigated with diffusion kurtosis imaging and compared with a group of age- and sex-matched healthy volunteers using voxel-based analysis. Kur- tosis metrics show more sensitivity to white matter changes than standard diffusion metrics. Significant differences were found in posterior cerebral areas as well as subcortical regions like the putamen, and are therefore promising results. [less ▲]

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See detail"Je ne suis pas philosophe." Rousseau au miroir de l'épistolaire. Images de soi dans la correspondance de Jean-Jacques Rousseau (1730-1765)
Biquet, Stéphanie ULg

Doctoral thesis (2014)

L’objet de cette recherche consiste donc en une analyse de l’image de soi dans le discours épistolaire de Jean-Jacques Rousseau, depuis les premières années genevoises (vers 1730) jusqu’au départ pour ... [more ▼]

L’objet de cette recherche consiste donc en une analyse de l’image de soi dans le discours épistolaire de Jean-Jacques Rousseau, depuis les premières années genevoises (vers 1730) jusqu’au départ pour l’Angleterre (1765). Plus précisément, nous avons examiné le rapport que cette image entretient avec la figure du philosophe, qui fait l’objet d’une profonde reconfiguration au cours du XVIIIe siècle et qui nous semble une clé de lecture incontournable pour comprendre Rousseau. [less ▲]

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See detailDensité et écologie des chimpanzés (Pan troglodytes schweinfurthii) dans le Parc National de la Kibira, Burundi
Hakizimana, Dismas ULg

Doctoral thesis (2014)

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les ... [more ▼]

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les activités de braconnage. L'impact de ces menaces est si grand que certaines communautés de primates ont complètement disparu avant d’avoir été reconnues, encore moins étudiées. Des données référentielles sont toujours nécessaires pour comprendre les variations spatio-temporelles des primates. Les estimations de la densité ou d'abondance des populations sont des outils de première importance lors de la détermination des priorités de conservation et de la mise en place d’un plan de gestion des populations de primate. Comme dans les écosystèmes forestiers, la répartition et l’abondance des différentes espèces d’arbres influencent profondément les communautés animales qui y vivent, nous avons d’abord cherché à déterminer la densité et la structure des espèces d’arbres de la forêt de Kibira. Dans 256 plots couvrant une superficie de 32,15 ha, un total de 6.504 arbres répartis en 70 espèces, 67 genres et 37 familles ont été enregistrés. La densité était de 202 tiges par hectare, avec une surface basale de 21,05 m² par hectare. Au total, six espèces de primates diurnes ont été enregistrées dont une espèce anthropoïde (Pan troglodytes schweinfurthii), quatre cercopithecinae (Cercopithecus mitis, Cercopithecus mona denti, Cercopithecus lhoesti et Lophocebus albigena) et une colobinae (Colobus angolensis). Seule la densité et l’effectif total de la population des chimpanzés sont connus, tandis que pour le reste des espèces, seul l’indice d’abondance kilométrique a été calculé. Cette recherche a accordé une attention particulière à l’espèce emblématique du Parc National de la Kibira, le chimpanzé d’Afrique de l’est, Pan troglodytes schweinfurthii. Afin de mieux protéger cette sous-espèce en danger d’extinction, nous avons mené des investigations sur les sites de nidification pour identifier les espèces et les caractéristiques des arbres sur lesquelles les chimpanzés comptent pour la construction des nids. Les résultats ont montré que les chimpanzés sélectionnent certaines espèces d’arbres lors de la construction des nids. Le secteur Mabayi, situé au nord du parc, est le plus riche en espèces de primates; il abrite cinq espèces sur les six enregistrées, et deux espèces: Cercopithecus lhoesti (menacée) et Colobus angolensis ne se retrouvent qu’à Mabayi uniquement. Cette partie du parc constitue une clé pour la diversité et devrait par conséquent bénéficier d’une attention particulière en matière de protection et conservation. [less ▲]

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See detailEffets génomiques et non-génomiques de l'oestradiol lors de l'activation du comportement sexuel mâle
Seredynski, Aurore ULg

Doctoral thesis (2014)

Testosterone, via its estrogenic metabolites, is involved in the control of different behaviors such as social communication or reproduction. Estrogens act mainly at the genomic level via the activation ... [more ▼]

Testosterone, via its estrogenic metabolites, is involved in the control of different behaviors such as social communication or reproduction. Estrogens act mainly at the genomic level via the activation of nuclear receptors to regulate the transcription of target genes but also act at the non- genomic level via the activation of membrane receptors. The main question of my work was how these two types of actions of estrogens interact to control male sexual behavior. [less ▲]

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See detailRole of transcription factor sox4b in the differentiation of pituitary cells in zebrafish.
Quiroz O' Donova, Yobhana ULg

Doctoral thesis (2014)

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and ... [more ▼]

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24hpf and later in the entire head region including the pituitary. At 48hpf, sox4b mRNA colocalizes with that for thyroid stimulating hormone (tsh), glycoprotein subunit  (gsu) and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knock-down or expression of a dominant negative Sox4 mutant, leads to a drastic decrease in tsh and gsu expression and reduced levels of gh, while other anterior pituitary gland markers including prl, slβ, pomc and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tsh and gsu expression at 48hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tsh and gsu expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhβ and fshβ) at 4dpf. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary. [less ▲]

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See detailCourse à l'innovation et mécanique des brevets. L'évolution technologique dans l'industrie belge du zinc (1806-1873)
Peters, Arnaud ULg

Doctoral thesis (2014)

Dans le jeune État belge fragilisé par son statut international, l'innovation technique constitue une priorité étatique, mais aussi un des moteurs du développement entrepreneurial. L'essor industriel du ... [more ▼]

Dans le jeune État belge fragilisé par son statut international, l'innovation technique constitue une priorité étatique, mais aussi un des moteurs du développement entrepreneurial. L'essor industriel du 19e s. s'accompagne ainsi d'une course à l'innovation qui sous-tend de nombreux enjeux. Cette thèse les questionne en parcourant, dans un premier temps, le territoire codifié de la propriété industrielle. L'étude porte d'abord sur la construction d'un système belge des brevets. Comment est-il conçu par les premiers gouvernements belges ? Quelles sont ses caractéristiques ? Comment favorise-t-il la course à l'innovation ? Il convient d'appréhender d'abord les cadres juridiques, les références et les singularités qui définissent l'expérience belge. Ensuite, la nature de l'adhésion des acteurs au système est analysée. Dans un second temps, l'interrogation privilégie une approche sectorielle. La relation liant les brevets à l'innovation est examinée à travers le cas de l'industrie belge du zinc et de l'entreprise qui la domine : la s.a. des Mines et Fonderies de zinc de la Vieille-Montagne, première multinationale d'Europe. Que révèlent les brevets à propos des technologies en place et de leur évolution ? Par quels mécanismes contribuent-ils à l'innovation ? L'analyse porte sur un corpus de plus de 200 brevets étudiés à la lumière des archives d'entreprises. Elle éclaire sur les processus innovants et les conditions de leur déploiement. Cette histoire technique de la filière du zinc illustre les dynamiques qui s'attachent à l'innovation au temps de l'essor industriel. Elle met en lumière un ensemble de stratégies mises en œuvre par les industriels pour contourner les problèmes que pose la technologie en place : imperfection des méthodes de réduction, nuisances, mécanisation, diversification, etc. comme les tâtonnements, hésitations, échecs, ruptures inhérents aux processus innovants. [less ▲]

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See detailModes d'Organisation et Distribution de l'eau: Une Evaluation empirique de la Performance par les Méthodes des frontières de production
Mande Buafua, Patrick ULg

Doctoral thesis (2014)

Cette thèse est une contribution à l’analyse empirique de la performance (efficacité technique et effectivité) dans le secteur de la distribution de l’eau en Afrique Subsaharienne. Nous cherchons à ... [more ▼]

Cette thèse est une contribution à l’analyse empirique de la performance (efficacité technique et effectivité) dans le secteur de la distribution de l’eau en Afrique Subsaharienne. Nous cherchons à répondre à la question de l’impact des modes d’organisation (participation du secteur privé, régulation et une combinaison de deux) sur l’amélioration de la performance dans ce secteur. Notre analyse s’appuie sur les données issues de la base des données de l’AICD pour la période 2000 à 2005. Premièrement, grâce au modèle de Battese & Coelli (1995), nous calculons les scores d’efficacité technique et nous identifions les sources de l’inefficacité technique. L’approche PLP nous sert de technique complémentaire pour approfondir l’examen des élasticités d’échelle et du coût implicite des pertes d’eau sur le réseau pour chaque opérateur. En moyenne, les entreprises de l’échantillon sont techniquement inefficaces sur la période. Réguler par contrat de performance conduit à des scores d’efficacité technique plus élevés que réguler par agence. La participation du secteur privé dans la gestion ou l’exploitation du service présente un effet positif sur l’efficacité technique. Il n’y a pas de preuve d’une différence significative entre l’efficacité technique des entreprises sous gestion publique régulées par contrat de performance ou par agence de régulation et celles avec participation du secteur privé dans la gestion ou l’exploitation régulées par contrat de performance ou par agence de régulation. Les élasticités d’échelle sont, en moyenne, décroissantes. Le coût des pertes d’eau sur le réseau est évalué, en moyenne, à 4 travailleurs pour 100.000 m³ d’eau perdue. De plus, ce coût marginal a tendance à augmenter avec les niveaux de la qualité du réseau. Deuxièmement, nous analysons notre question de recherche en prenant en compte la performance en termes d’effectivité. Nous nous appuyons sur la méthode DEA basée sur la procédure en double bootstrap (Simar & Wilson, 2007) en appliquant l’approche analytique, en 4 étapes, inspirée de Mbuvi et al., (2012). Les résultats laissent entrevoir l’existence d’un problème d’ineffectivité plus élevé que celui d’inefficacité technique. Ainsi, les opérateurs ont besoin des ressources additionnelles pour atteindre 100% de leur effectivité. Réguler par contrat de performance conduit à une plus grande effectivité que réguler par agence de régulation. La variable relative à la participation du secteur privé dans la gestion ou l’exploitation du service a un effet négatif et significatif sur l’effectivité. Enfin, il n’y a pas de différence significative, en termes d’effectivité, entre les entreprises avec participation du secteur privé dans la gestion ou l’exploitation régulées par agence ou par contrat de performance et celles publiques régulées par agence ou par contrat de performance. Enfin, nous évaluons l’impact des variables institutionnelles sur les taux de couverture du service en utilisant les modèles à effets fixes. Nous nous attaquons à la question de l’endogénéité en utilisant le cadre proposé par Heckman (1978). Réguler par contrat de performance a un effet positif et significatif sur les taux de couverture. La participation du secteur privé dans la gestion ou l’exploitation du service possède un effet négatif et significatif sur les taux de couverture du service. Combiner la gestion publique avec la régulation par agence ou par contrat de performance conduit à des taux de couverture du service plus élevés que combiner la participation du secteur privé dans la gestion ou l’exploitation du service avec la régulation par agence ou par contrat de performance. [less ▲]

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See detailThe cyclic behaviour of sand, from the Prevost model to offshore geotechnics
Cerfontaine, Benjamin ULg

Doctoral thesis (2014)

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE ... [more ▼]

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE. The first step consists in summarising the salient features of the cyclic behaviour of sand observed in laboratory tests. Undrained monotonic and cyclic experiments are addressed. The phase transformation line is a key parameter in the description of its behaviour. The plasticity effects in both loading and unloading, the progressive pore pressure accumulation coupled with the degradation of the stiffness of the soil are of uttermost importance in the cyclic behaviour. The Prevost model is adopted for its conceptual simplicity and its physically related parameters. The basic equations of the model are described and its variants are illustrated. Calibration of the required parameters is carried out by means of simplified routines implemented in Matlab. A unique set of parameters is determined for each soil at a given relative density. Monotonic experiments are well reproduced. The model also replicates satisfactorily the trend of cyclic experiments. An implicit scheme is embraced in order to implement the model in the finite element code LAGAMINE. The implicit Prager translation rule is adopted for that purpose. It is ensured the discrete formulation reproduces exactly the analytical model. Accuracy, efficiency and robustness of the model are addressed throughout triaxial and multi-axial numerical examples. A hydro-mechanical interface finite element is developed. It consists in a three-node 1D isoparametric element. It is able to reproduce fluid flows across and along the interface. The unsticking of both walls of the interface is coupled with a suction effect due to the filling of the vacuum created. The behaviour of the element is illustrated by simple 1D examples of transient consolidation of a soil column. A final application consists in the modelling of a suction caisson, part of a tripod structure for wind turbines. An axisymmetric representation of this foundation is carried out. It is assumed embedded into dense Lund sand described by the Prevost model. Monotonic and cyclic simulations are performed in both drained and partially drained conditions. The salient features of the resistance of such foundations are highlighted. Their partially drained behaviour strongly increases their transient resistance. A storm including an extreme event is employed to simulate a cyclic loading. A pseudo-random short signal and its sinusoidal equivalent representation finally lead to an identical vertical settlement. This is confirmed by a long duration storm. Finally, a cyclic diagram summarising the final settlement attained for combinations of average and cyclic vertical loads is elaborated. Keywords [less ▲]

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See detailReprésentations de l’environnement et adoption des pratiques durables de production par les cotonculteurs du Bénin
Assogba, Sonagnon Claude-Gervais ULg

Doctoral thesis (2014)

The research aims at contributing to a better understanding of the adoption of eco-friendly innovations. It analyses representations of environment and practices associated with sustainable management of ... [more ▼]

The research aims at contributing to a better understanding of the adoption of eco-friendly innovations. It analyses representations of environment and practices associated with sustainable management of cotton farming systems in order to deepen understanding of logics and strategies underlining farmers’ practices, and motivations that determine their sustainable farming system adoption behaviors. Organic cotton (SCBIO) and cotton made in Africa (SCMIA) systems were used as case study. Field research was carried out in Kandi and Pehunco in the largest area of cotton production in the North of Benin. The theoretical framework is based on the theories of technical change analysis, the actor-oriented approach and the theories of social representations. Data were collected from a sample of 90 organic cotton farmers and 100 CmiA farmers selected from a typology based on endogenous criteria of prosperity. 39 field agents from organizations promoting sustainable cotton farming system were surveyed. Individuals and groups interviews were used to collect data. The data were analyzed with a combination of qualitative and quantitative methods including normative and relative comparison analysis, perception analysis, descriptive statistics, analysis of variance, chi square test, etc. Results show a marginal contribution of organic cotton and cotton made in Africa to national economy in comparison to the conventional system. At farmer’s level farming system analysis reveals that both organic cotton and cotton made in Africa systems are not intensively sustainable. Their implementation is characterized by a large gap between recommendations and farmers’ practices, especially in soils’ fertility and pests’ management. The use of organic matters in combination with crops rotation including leguminous plants is the main approach of soils fertility management in organic cotton system. However, quantities of organic matters used, especially cow dung, are not sufficient due to its low availability and the lack of transportation means. The management of pests and diseases faces enormous constraints ranging from biopesticides production difficulties, weak efficiency of biopesticides, to observation of the evolution of parasitic complex, etc. Although the use of organo-chemical fertilizer is recommended in SCMIA system, more than 50% of SCMIA farmers apply only chemical fertilizer. Globally, the quantities of chemical fertilizer applied are under the requirements while the quantities of organic fertilizers are too small. Application of staged and targeted pest control (lutte étagée ciblée) is limited by constraints coming from the late implementation and the ineffectiveness of pesticides, the high number of observations needed, etc. Therefore, pesticides are used in overdose and prohibited pesticides such as endosulfan are also used. Consequently yields are very low and decrease. In addition, some farmers, especially from organic system, considering necessity of chemical fertilizers use for maize production develop diverse strategic logics such as misappropriation, craftiness, etc. to obtain these fertilizers. It appears from analysis that strategic logics carried out by farmers in farming systems’ adoption are the result of a combination of explanatory factors. These factors contribute to deepen the understanding of the weaknesses of organic and CmiA values chains in Benin and the bottlenecks in their development. Far from being static, farmers’ logics area temporary equilibrium resulting from different explanatory categories relative to social representations of environment, perceptions of projects and production and social reproduction objectives of farmers, the demand of sustainable cotton on international market, etc. Consequently, all actions aimed at promoting the sustainability of cotton farming system may facilitate access of farmers to inputs through the improvement of their existence means for a better soil fertility and pests management. Sensitization and training programs on the importance of leguminous plants integration to crops rotation, staged and targeted pest control, etc., may be carried out. At policy level it would be desirable that policies decisions don't negatively affect the development of alternative cotton value chains. In addition, measures may be taken to facilitate farmers’ access to chemical fertilizers for food crops, especially maize, to avoid their selling off. [less ▲]

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See detailImpact of micro-physics and macro-physics on the seismic properties of main-sequence B-type stars
Salmon, Sébastien ULg

Doctoral thesis (2014)

L’étude des pulsations stellaires, tout comme les ondes sismiques sur Terre, nous donne une méthode puissante afin de découvrir l’intérieur des étoiles. Cette discipline scientifique est aussi connue sous ... [more ▼]

L’étude des pulsations stellaires, tout comme les ondes sismiques sur Terre, nous donne une méthode puissante afin de découvrir l’intérieur des étoiles. Cette discipline scientifique est aussi connue sous le nom d’astérosismologie. Grâce aux missions spatiales CoRoT et Kepler, l’astérosismologie est entrée depuis dans une période faste. Par ailleurs, une frac- tion significative des étoiles présente des pulsations, ce qui nous permet de sonder leur intérieur pour la plupart de leurs stades d’évolution. Cette thèse se concentre sur les étoiles de type B de la séquence principale. Via l’inter- action de leurs vents stellaires avec leur milieu environnant et la production de nouveaux éléments chimiques en leurs intérieurs, elles contribuent aux processus dynamiques et d’enrichissement chimique du milieu interstellaire. Heureusement, deux types de pulsa- tion stellaire affectent ces étoiles: d’une part les pulsations dites de type β Cephei et d’autre part celles de type SPB. La nature de ces pulsations est sensible aux processus physiques internes de ces étoiles. Ainsi, l’observation de ces pulsations nous offre de sonder ces différents processus. Dans cette thèse, nous étudions tout particulièrement la sensibilité de ces étoiles aux opacités ra- diatives, et nous appuyant sur ces résultats, contraignons l’opacité radiative des éléments du groupe du fer à l’aide des étoiles pulsantes repérées dans les Nuages de Magellan. Dans une seconde étape, nous évaluons la possibilité de contraindre la nature du mélan- ge (diffusif ou overshooting instantané) à l’aide de la modélisation des β Cephei par l’ap- proche directe. Nous testons également les facteurs influençant la détermination de l’exten- sion de la zone mélangée. Enfin, nous proposons un scénario explicatif de la récente découverte d’une nouvelle classe d’étoiles variables dans un amas stellaire connu pour comporter de nombreuses étoiles en rotation rapide. [less ▲]

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See detailSimulation d’une Cellule Solaire Cristalline par la Méthode des Différences Finies & Fabrication, Caractérisation et Modélisation de Cellules Solaires à base d’hétérojonctions organiques distribuées en volume
Aazou, Safae ULg

Doctoral thesis (2014)

This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and ... [more ▼]

This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and their economic, ecologic and environmental advan- tages in comparison with fossil energy resources are emphasized, then, a revue of structure, types of bonds and energy bands of a solid material is presented and the case of a semiconductor is considered. Starting from Maxwell equations, the basic semiconductor equations namely Poisson’s equation and the continuity equations of electrons and holes are established. Next, discretizations of Poisson’s equation using a finite difference scheme and of the continuity equations by the Gummel-Scharfetter scheme are performed. The obtained system of equations is solved iteratively according Newton-Raphson algorithm. The experimental part of the work, entirely achieved in LIOS affiliated to JKU at Linz (Austria), aims the fabrication and the characterization of organic bulk heterojunction solar cells based on two different polymers used as donors P3HT and AnE-PVstat and the molecule PCBM as acceptor. A comparative study of the fabricated solar cells indicates that the device efficiency depends on the donor:acceptor ratio. In or- der to understand electronic and optical mechanisms occurring within a solar cell and which may affect its characteristics and performance, and to identify the role of the equivalent circuit parameters describing these mechanisms, many electronic circuits modelling the solar cell are presented and only the five physical parameters circuit is chosen. Several physical parameters extraction methods are exposed in details and only three of them are retained to extract the five physical parameters of the fabricated solar cells. The effects of each physical parameter on the solar cell efficiency are investigated. Thus, the variation intervals of the photovoltaic metrics, fill factor and efficiency under the influence of parameters variations can be identified. [less ▲]

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See detailModélisation des conditions d’apparition du micro-hydrodynamisme via la méthode des éléments finis dans la perspective d’intégrer ce phénomène dans un modèle numérique de laminage à froid.
Carretta, Yves ULg

Doctoral thesis (2014)

This dissertation presents a finite element numerical model able to predict the occurrence of Micro-Plasto-Hydrodynamic (MPH) lubrication. This phenomenon, which was first introduced by Mizuno and Okamoto ... [more ▼]

This dissertation presents a finite element numerical model able to predict the occurrence of Micro-Plasto-Hydrodynamic (MPH) lubrication. This phenomenon, which was first introduced by Mizuno and Okamoto, appears in the mixed lubrication regime. It consists in lubricant flows at the microscopic scale leading to a lubrication of the tool-piece solid contacts and therefore to a local friction drop. For instance, Laugier et al. have observed a friction decrease while rolling High Strength Steels for different strip thickness reductions. The only physical explanation to this trend is the MPH lubrication. Despite the huge influence of MPH lubrication on friction in metal forming processes, only a few numerical models can be found in the literature. Moreover, these models rely on several restrictive assumptions which prevent them from delivering predictive results. This work consists in the development of the first finite element model capable of predicting the appearance of the MPH lubrication. This model is used to numerically reproduce the experiments of Bech who studied this phenomenon, in plane strip drawing, by observing the behaviour of macroscopic pyramidal lubricant cavities through a transparent die. In the proposed approach, plane strip drawing is modelled in 2D with Metafor, an in-house nonlinear FE code. This model allows us to compare the lubricant pressure to the solid-solid contact pressure profile between the upper die and the strip material. Once the lubricant pressure exceeds the solid-to-solid contact pressure, the condition allowing a lubricant flow from the pocket to the neighbouring plateaus is fulfilled. The presented FE model is able to predict backward and forward escapes of the lubricant from the pocket. As in the experiments of Bech, several parametric studies have been carried out. The numerical results show that the model reproduces the trends observed experimentally. [less ▲]

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See detailLas políticas de representación del género en la escritura de la migración latinoamericana. Un análisis comparativo de El camino a Ítaca, de C. Liscano; Árbol de luna, de J. C. Méndez Guédez; y The Brief Wondrous Life of Oscar Wao, de J. Díaz.
Berlage, Pauline ULg

Doctoral thesis (2014)

The present thesis addresses the question of Latin-American migration literature by dealing with the subject from a gender perspective. This work brings into focus the politics of representation of bodies ... [more ▼]

The present thesis addresses the question of Latin-American migration literature by dealing with the subject from a gender perspective. This work brings into focus the politics of representation of bodies and migrant subjectivities in three works of narrative fiction from the end of the twentieth century and beginning of the twenty-first: El camino a Ítaca (1994), by Carlos Liscano; Árbol de Luna (2000), by Juan Carlos Méndez Guédez; and The Brief Wondrous Life of Oscar Wao (2008), by Domincan-American writer J. Díaz. Basing myself on that body of novels by male writers, I examine the way the subjectivity of gender-oriented register is combined with other “identity data” as class, race, ethnic differences and nationality. Moreover, this study focuses on the individual and collective re-subjectification process that the literary discourse transcribes through representation conventions in which the sexual and gender dimension is determining. The gender question is, therefore, discussed in terms of discursive aesthetic possibilities and is analysed in the particular cases of various literary migratory itineraries. Each novel is analyzed in the framework of the discursive production of Latin-American migration waves and in relation to the current debate over migrant literature. The literary analysis which focuses on concepts such as discursive ethos, the polysemy of “topic”, “corpo-graphy” and finally the concept of heterotopy. These will facilitate our understanding of migration in relation to the reshaping or reification of masculinity and feminity that are built followig some specific national norms. [less ▲]

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See detailÉvolution géomorphologique du littoral occidental de la péninsule tingitane (Maroc)
El Abdellaoui, Jamal ULg

Doctoral thesis (2014)

This work traces the geomorphological evolution of the western coast of the tingitane Peninsula (Morocco) in two time scales: the current scale and the Quaternary scale. Geomorphological characteristics ... [more ▼]

This work traces the geomorphological evolution of the western coast of the tingitane Peninsula (Morocco) in two time scales: the current scale and the Quaternary scale. Geomorphological characteristics have been identified and placed into their morphotectonic and/or morphodynamic contexts. To make our work more interesting, fruitful and realistic, we adopted an empirical approach. Firstly, we based our research on collection of data and analysis of available documents. Secondly, we made measurements, using appropriate techniques to answer specific questions, or to argue the hypotheses. It appears from this study, that the organization of geological units in a NNW-SSE direction has created a rugged shore, mainly in rocky cliff and pocket beaches on the Strait of Gibraltar coast, and a low sandy coast on the Atlantic coast. The geological and geomorphological quaternary history of Gibraltar Strait coast is characterized by a series of marine abrasion stepped and raised surfaces. The history of the Atlantic coast is rather marked by tectonic subsidence. This tectonic subsidence is manifested on the surface by a system of closed depressions (daya) arranged in a NNW-SSE axis, almost parallel to the orientation of geological units. The evolution of the geomorphological depressions is also controlled by the fluvio-marine action and wind activity. The last interglacial period is marked by two transgressive pulsations of eustatic origin. They were recorded at the marine terraces on both coasts. The second pulsation is aged at least 119.6 ± 2.3 ky. After the last interglacial, the central area of the Strait of Gibraltar was raised by an average of 8.1mm/100year from 117ky. The Ouljien was raised to a height of 13 to 16m. The Atlantic coast was stable at 117ky. Marine terraces are 5-6m high. The analysis shows that the current morphodynamics of the Atlantic coast are characterized by a barred beach geomorphology with a high spatio-temporal variability. It appears that a land wind plays a key role in the morphosedimentary evolution of backshore and foreshore. Indeed, the backshore develops, by negative retroaction, a geomorphology with a dune system to slow transport operated by land winds from the east. The foreshore, meanwhile, develops, by a positive retroaction, a system of bar and rip channels to counter a change in slope generated by the wind. On the one hand, risk analysis shows that the succession of anthropic changes at Tangier Bay has brooked the internal sediment balance. Erosion has affected both the sandy and rugged beaches of the eastern sector. The Atlantic coast doesn’t show signs of erosion, but it has a high vulnerability, because it evolves in a closed sedimentary system. On the other hand, the characteristic of a low open ocean coast facilitates the penetration of marine waters within the continent, especially the lower areas. Finally, a barred beach geomorphology creates problems of harbor silting and access disruption. [less ▲]

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See detailDétection automatique des changements du bâti à partir des images satellitaires à haute résolution spatiale et des données cartographiques existantes.
El Mansouri, Loubna ULg

Doctoral thesis (2014)

La révision des données cartographiques (DC) est un processus réalisé actuellement d'une manière entièrement manuelle en cherchant les changements entre la donnée existante et une image plus récente ou ... [more ▼]

La révision des données cartographiques (DC) est un processus réalisé actuellement d'une manière entièrement manuelle en cherchant les changements entre la donnée existante et une image plus récente ou carrément par une nouvelle cartographique du territoire comme le cas au Maroc. La tâche étant lourde, lente et coûteuse, de nombreux travaux sont menés pour l'automatiser. L'idée développée dans plusieurs agences de cartographie collaborativement avec des institutions de recherche est d'adopter un mode de mise à jour semi automatique, où des procédures de détection automatique de changements sont mises en place pour extraire les zones de changement potentielles et les présenter à un technicien cartographe pour les valider avant de les intégrer à la DC à mettre à jour. Dans cette thèse, nous nous focalisons sur la détection des changements du bâti par comparaison automatique d'une carte numérique (CN) existante à une image satellitaire à haute résolution spatiale (HRS) plus récente, en vue d'une mise à jour semi automatique. L'approche proposée décompose le processus de détection de changements en deux étapes. Dans la première, les bâtiments sont extraits de l'image en se basant sur la classification de l'image pré-segmentée. Nous avons utilisé conjointement les avancées en algorithmes de classification d'images et les connaissances dérivées de la carte et des relations entre les objets urbains afin de s'affranchir des difficultés liées à l'extraction d'objets à partir d'images à HRS. Les objets de la carte sont intervenus à plus d'un niveau pour soutenir et automatiser l'extraction. Dans la seconde étape, la couche de bâtiments extraits est comparée à l'ancienne couche de bâtiments pour déduire les changements à l'échelle du "bâtiment". Ces changements représentent les mises à jour à valider par le technicien avant de les intégrer dans la carte. Nous illustrons l'efficacité de notre approche par des expériences menées avec une carte et une image QuickBird de la ville de Rabat au Maroc, qui connait depuis la dernière décennie une forte extension urbaine au détriment des zones de végétation. [less ▲]

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See detailDevelopment and numerical validation of a 2-scale computational model to study the mechanical behavior of nanocrystalline metals
Péron, Vincent ULg

Doctoral thesis (2014)

This work aims at predicting the mechanical behavior of nanocrystalline structure using a 2-scale approach. Molecular simulations using the quasicontinuum method (QC) are performed to obtain the ... [more ▼]

This work aims at predicting the mechanical behavior of nanocrystalline structure using a 2-scale approach. Molecular simulations using the quasicontinuum method (QC) are performed to obtain the mechanical responses of the grain-boundaries and grains at the nanoscale. A finite element model is then calibrated using these atomistic results. This 2-scale model accounts for intergranular and intragranular plasticity, can predict the intergranular failure, and is able to study large structures. [less ▲]

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See detailImportant roles of SoHo proteins in vascular development: Sorbs1 and Sorbs2 have related but distinct functions in endothelial cells angiogenic properties
Bleuart, Anouck ULg

Doctoral thesis (2014)

Vascular system in all vertebrate organisms has in charge essential functions such as to bring nutrients, oxygen and signalling molecules to distant organs. Vascular network is established through ... [more ▼]

Vascular system in all vertebrate organisms has in charge essential functions such as to bring nutrients, oxygen and signalling molecules to distant organs. Vascular network is established through sequential and distinct processes. During embryogenesis, angioblasts give rise to differentiated endothelial cells, which form primary vessels through vasculogenesis. Expansion of this primary network is then achieved through a multistep process known as angiogenesis. During angiogenesis, remodelling of endothelial cell shape relies on cytoskeleton dynamics. In this study, our goal was to investigate the potential role of the SoHo family of adaptor proteins in angiogenesis. The SoHo family comprises three members, Sorbs1, Sorbs2 and Sorbs3. Although accumulative evidence links this protein family to the regulation of cell adhesion and actin cytoskeletal organisation, their expression and potential functions in endothelial cells remain unknown. Using zebrafish loss of function experiments combined with confocal imaging, we show that loss of Sorbs1 affects caudal vein-derived vessel formation, whereas Sorbs2 depletion impairs ISV development essentially derived from the dorsal aorta. We then demonstrated that both members impact on EC behaviour via regulation of RhoGTPases activity, leading to the vascular defects observed in vivo. Using a series of in vitro functional assays, we found that Sorbs1 and Sorbs2 have opposite effects on adhesives properties of HUVECs related to their ability to regulate different RhoGTPases. Sorbs1 depleted ECs adhere excessively to the ECM due to decrease in Rac1 activity. In contrast, loss of Sorbs2 impaired RhoA activation during adhesion and decreases cell adhesiveness to the matrix. Interestingly, these opposite effects on cell adhesion lead to similar outcome on EC migratory abilities, a decrease in cell migration. Here, for the first time, we establish a role for Sorbs1 and Sorbs2 in angiogenesis and demonstrate that these SoHo members are essential for EC adhesiveness and subsequent migratory abilities. [less ▲]

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See detailExtension of the Direct Strength Method to hot-rolled and welded H profile cross-sections
Li, Yongzhen ULg

Doctoral thesis (2014)

The cross-sectional capacity is limited by material yielding on one hand and local buckling on the other hand. Most current metallic structural design codes use the concept of section classification for ... [more ▼]

The cross-sectional capacity is limited by material yielding on one hand and local buckling on the other hand. Most current metallic structural design codes use the concept of section classification for determining the section capacity of hot-rolled profiles. In this system, there exists a discontinuity between the classes 2 and 3 under pure bending load condition, while for the class 4, the effective width method (EWM) must be used to account for local buckling phenomenon. With the appearance of the more complex cross-sections, especially for thin-walled steel structures, the calculation using EWM becomes more and more intolerable and complicated. In order to overcome these difficulties when evaluating the cross-section strength, the alternative Direct Strength Method (DSM) approach, developed only for cold-formed thin-walled members, has gained importance over the last few years, and has been adopted by the North American and Australian standards for the design of cold-formed steel structural members recently. This thesis investigates the possibility to extend the DSM method to hot-rolled and welded structural steel members, and the objective is to derive a new formulation that would cover the whole field of section slenderness without section classification system used in Eurocode 3, using the same procedure for the DSM developed for cold-formed thin-walled steel structural members. Hot-rolled and welded H sections are mainly considered in this thesis. The DSM is premised on the assumption that the strength can be predicted from the yield strength to the elastic critical load ratio used in conjunction with a strength curve; i.e. the same concept than the one used in Eurocode 3, in terms of member buckling phenomenon. In the DSM approach applied for cold-formed thin-walled sections, local buckling and distortional buckling modes should be considered. For common hot-rolled or welded sections, only local buckling needs to be considered since distortional buckling does not occur for these sections. All available test results in literature are collected and evaluated with the current methods for calculating the cross-section resistance such as EWM, DSM, and the recent Continuous Strength Method (CSM). A short comparison is made and their domains of applicability are commented. A consistent approach has been adopted to develop numerical models for hot-rolled and welded sections subjected to compression and bending respectively. The FE model was built in FineLg and verified against test results of the “Semi-comp: Plastic member capacity of semi-compact steel sections - a more economic design” project, which was carried out earlier with the objective of improving the utilization of plasticity in rolled and welded sections with medium cross-section slenderness. Measured material and geometric properties, initial geometrical imperfections and residual stresses distributions have been highlighted. Once verified against the test results, the FE models have been used to carry out a parametrical study aimed at providing more FE results and highlighting the local buckling interaction between the webs and the flanges. All the experimental and FE numerical results constitute data base for the derivation of the new DSM curves. On the basis of Winter Formula for plate buckling and the generic DSM strength curve, different formulas are proposed for hot-rolled and welded H cross-sections under axial and bending load respectively. Also the statistical evaluation and safety study is conducted to obtain the safety factor γ_M, which is required for practical design. [less ▲]

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See detailIdentification et rôle des médiateurs sonores dans les phases de colonisation et d’installation de poissons dans un environnement corallien
Berten, Laetitia ULg

Doctoral thesis (2014)

La majorité des poissons de récifs coralliens présentent un cycle de vie complexe, caractérisé par une phase larvaire pélagique dispersive en milieu océanique, suivie d’une phase benthique au sein du ... [more ▼]

La majorité des poissons de récifs coralliens présentent un cycle de vie complexe, caractérisé par une phase larvaire pélagique dispersive en milieu océanique, suivie d’une phase benthique au sein du lagon ou sur la pente externe du récif. Ce travail porte sur l'influence du stimulus sonore lors de la colonisation et de l'installation, au sein du récif, des larves de poissons. De récentes études ont montré un effet attracteur du son de récifs sur les larves de poissons et de crustacés. Mais on ignore encore la distance à laquelle les larves sont capables de repérer le son du récif, ni si elles sont attirées par une signature spectrale complexe ou plus simplement par la présence d'un "bruit". Enfin, on ignore si les différents habitats d’un récif peuvent présenter des signatures acoustiques propres, ni si les sons des habitats peuvent guider les larves lors de leur installation au sein du récif. L'étude de mesures de pression sonore le long de trois transects de 2 km effectuées sur la côte nord de l'île de Moorea (Polynésie Française) met en évidence une diminution régulière de l'intensité sonore jusqu'à une distance à la crête de 750-1000 m. Au-delà de cette distance, et jusqu'à 2 km, une augmentation graduelle de la pression sonore est observée. Dès lors, une larve située à 750-1000 m du récif se retrouve confrontée à deux gradients de pression, l'un dirigés vers l'océan et l'autre vers le récif, et devra faire appel à d'autres stimuli pour s'orienter vers ce dernier. Au sein du récif, les sons provenant de 5 habitats de Moorea (crête interne, récif barrière, récif frangeant, chenal et mangrove) ont été étudiés. Les signatures sonores de chaque habitat (hormis crête interne et récif barrière) diffèrent des autres sur une certaine gamme de fréquences, et ces différences sont conservées avec la distance (plusieurs km). De plus, l'étude de l'influence des sons d'habitats et d'un son artificiel sur le comportement des larves met en évidence une modification du comportement chez 16 des 20 espèces testées. Les différentes réponses illustrent deux stratégies d'installation sur base du son: soit une sélection directe de l'habitat, soit un évitement de certains habitats, et donc une sélection "par défaut" des habitats restants. Pourtant, les niveaux de pression sonore des habitats du lagon sont sous les seuils de capacités sonores des juvéniles d'Abudefduf vaigiensis, Acanthurus triostegus, Chaetodon citrinellus, Rhinecanthus aculeatus et Myripristis kuntee. Ce paradoxe nous pousse à remettre en question l'utilisation de l'outil "ABR" (Auditory Brainstem Response) dans les études de perception et d'influence des sons sur le comportement des poissons. [less ▲]

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See detailNew perspectives on probabilistic methods for nonlinear transient dynamics in civil engineering
Canor, Thomas ULg

Doctoral thesis (2014)

The objective of this thesis is to develop probabilistic methods to perform nonlinear transient analysis in civil engineering applications. The manuscript is divided into two parts. For large-dimensional ... [more ▼]

The objective of this thesis is to develop probabilistic methods to perform nonlinear transient analysis in civil engineering applications. The manuscript is divided into two parts. For large-dimensional structures subject to coherent random loads, an asymptotic expansion-based method is used to improve linear evolutionary spectral analysis. Then, this method is extended to equivalent statistical linearization by a multiple timescales approach. The second part of the thesis is focused on small-dimensional systems. It explores the solution of the Fokker-Planck equation with the smoothed particle hydrodynamics method. This meshless Lagrangian method particularly ensures the conservation and the positivity of the probability field. The accuracy and efficiency of both approaches are compared with Monte-Carlo simulations. [less ▲]

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See detailCaractérisation des modes de consommation alimentaire des ménages à Kinshasa : analyse des interrelations entre modes de vie et habitudes alimentaires
Muteba Kalala, Damien ULg

Doctoral thesis (2014)

This study was initiated at the start of a hypothesis that households are in a situation of food insecurity when their lifestyles and livelihoods have changed or have not adapted and they have not the ... [more ▼]

This study was initiated at the start of a hypothesis that households are in a situation of food insecurity when their lifestyles and livelihoods have changed or have not adapted and they have not the ability to find a balance between a set of needs. Households’ food demand cannot be analyzed independently from all livelihoods and living conditions. For this study, a methodology based on household surveys was adopted. Based on their supposed wealth level, three districts were selected, the Residential Area in Limete, the Mabulu neighbourhood in Makala and Quarters I and VII in Ndjili. A sample of 346 households was selected. The results of the first survey on the characterization of households have achieved the first three objectives of the study. The second survey consisted of a household monitoring defined according to specific criteria. Thirty households were selected at the rate of 10 in each of three quarters. They were followed first during the dry season for three months, from June to August 2011, and subsequently in the rainy season for three months also between February and April 2012. The results of this study show among other things that food expenditures are much higher in the rainy season than in the dry season. However, the quantities consumed are relatively higher in the dry season than in the rainy season. The amount of food consumed per person per day was estimated in the dry season respectively at 1.202g (in the richest households), 833g (in average households) and 506g (in poor households). During the rainy season, quantities consumed are respectively of 1.120g (in the richest neighborhood), 801g (in the average households) and 493g (in less well-off households). Energy intake per person per day in the dry season is respectively 2571 calories (in the richest households), 1.864 calories (in average households) and 1,094 calories (in poor households). Energy intake was also lower in the rainy season. It reaches respectively 2.452 calories (in wealthy households), 1,838 calories (in average households) and 1,130 calories (in poor households). Protein intake per person per day was estimated in the dry season respectively at 102g (wealthier households), 81g (in average households) and 51g (in poor households). During the rainy season, these contributions are also low. They are around of 100g in the wealthier households, 80g in the average households and 50g in poor households. The analysis of different consumption patterns showed that the dietary habits of Kinshasa do not seem to meet the nutritional requirements. Considerations between the two parameters show that households are scarcely managing to find a balance. The evidence supporting this difficult balancing includes: food monotony in households, the tendency to promote the consumption of cheap food, food choices unrelated to dietary considerations, the appearance of more and more public health problems related to food consumption patterns. However, the dietary imbalance in Kinshasa households is not always linked to income. [less ▲]

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See detailEntre recettes du Soi et recettes de l'Autre. Ethnographie de pratiques culinaires marocaines à Sesto San Giovanni (Milan, Italie)
Mescoli, Elsa ULg

Doctoral thesis (2014)

La thèse porte sur les processus de subjectivation d’un groupe de femmes marocaines résidant dans la ville de Sesto San Giovanni, dans le nord de l’Italie. Elsa Mescoli considère les habitudes ... [more ▼]

La thèse porte sur les processus de subjectivation d’un groupe de femmes marocaines résidant dans la ville de Sesto San Giovanni, dans le nord de l’Italie. Elsa Mescoli considère les habitudes alimentaires et les pratiques culinaires de ces femmes et de leurs familles, facteurs qui agissent dans la construction de soi à plusieurs niveau : celui intime, en contexte domestique ; celui partagé/contesté, en contexte publique. L’étude se situe au croisement entre l’anthropologie de l’alimentation, l’anthropologie de la culture matérielle et l’anthropologie des migrations. En fait, ces processus sont analysés en adoptant une perspective praxéologique, c’est-à-dire en portant l’attention sur la matérialité. La thèse met en évidence les « ingrédients » concrets de la définition de soi des femmes considérées, ainsi que de leurs rapports interpersonnels et « interculturels ». [less ▲]

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See detailEtude des propriétés des variants amyloïdogéniques du lysozyme humain à l’aide de fragments d’anticorps à chaînes lourdes comme sondes structurales
Dumont, Janice ULg

Doctoral thesis (2014)

Les fibres amyloïdes sont des agrégats de protéines hautement organisés qui sont associés à une trentaine de maladies appelées amyloses, dont les maladies d'Alzheimer et de Parkinson et la maladie de la ... [more ▼]

Les fibres amyloïdes sont des agrégats de protéines hautement organisés qui sont associés à une trentaine de maladies appelées amyloses, dont les maladies d'Alzheimer et de Parkinson et la maladie de la vache folle. L'amylose systémique à lysozyme est une amylose non-neuropathique héréditaire associée à sept variants de la protéine (Y54N, I56T, F57I, W64R, D67H, F57I/T70N et W112R/T70N). Ces protéines forment des fibres amyloïdes extracellulaires qui se déposent dans de nombreux tissus et organes tels que le foie, la rate et les reins. Il a été montré que les mutations I56T et D67H diminuent la stabilité et la coopérativité globale de la protéine. Ainsi, dans des conditions proches des conditions physiologiques, ces variants forment, in vitro, transitoirement un état intermédiaire dans lequel le domaine β et l'hélice C se déplient de manière coopérative, alors que le reste du domaine α conserve sa structure native. La formation d'interactions intermoléculaires entre les régions dépliées serait à l'origine du processus d'agrégation qui conduit à la formation et au dépôt de fibres amyloïdes dans les tissus des patients porteurs de ces mutations. Il a également été montré que la liaison de trois fragments d'anticorps à chaînes lourdes de camélidés (VHH), dirigés contre le lysozyme humain de sauvage, inhibe in vitro la formation de fibres amyloïdes par les variants D67H et I56T. Ces trois VHH se lient à des régions différentes du lysozyme et inhibent la formation de fibres amyloïdes selon différents mécanismes. Au cours de ce doctorat, seize nouveaux VHH spécifiques du lysozyme humain ont été générés. Des expériences de liaisons compétitives suivies par résonnance plasmonique de surface ont montré que les 16 VHH se lient à cinq épitopes distincts à la surface du lysozyme. Quatre d’entre eux sont capables de se lier au lysozyme dans les conditions utilisées in vitro pour induire la formation de fibres amyloïdes par les variants du lysozyme. Leur site de liaison a été déterminé par RMN. Deux d'entre eux reconnaissent des épitopes différents de ceux des trois VHH caractérisés précédemment. Des expériences d’échange H/D analysés par spectrométrie de masse ont montré que les 4 VHH ont des capacités différentes à restaurer la coopérativité globale du variant D67H du lysozyme. L’analyse de l’ensemble des résultats nous a permis d’identifier qu'elles sont les régions du lysozyme qui doivent être affectées par la liaison d'un VHH afin de restaurer la coopérativité globale de la protéine. La liaison simultanée aux deux domaines (i.e. α et β) semble être le dénominateur commun de tous les VHH restaurant la coopérativité globale du variant D67H. La liaison aux hélices B et C, ainsi que de l'interface des deux domaines semble aussi contribuer à la restauration de la coopérativité globale. A l'inverse, une liaison qui perturbe la partie N-terminale ne permet pas de restaurer la coopérativité globale de la protéine. La liaison d’un VHH, cAb-HuL9a, au variant D67H du lysozyme inhibe de manière similaire la formation de l’intermédiaire partiellement déplié, l'élongation de fibres amyloïdes préformées et la formation de fibres amyloïdes in vitro. Cette observation est en accord avec l’hypothèse selon laquelle, la formation de cet intermédiaire est à l’origine de l’amyloïdogénicité des variants du lysozyme. Afin d'étudier les effets des mutations amyloïdogéniques récemment identifiées sur les propriétés du lysozyme et ainsi obtenir une meilleure connaissance du mécanisme de formation des fibres amyloïdes, il est nécessaire de produire ces variants en grande quantité. Les variants D67H, I56T et F57I sont produits dans Aspergillus niger. L'expression des variants dans ce micro-organisme est toutefois particulièrement chronophage alors que les rendements de production sont relativement faibles. Les tentatives d'utiliser d'autres systèmes de production tels que Pichia pastoris ou le système bacculovirus n'ont pas été concluantes. Aussi, dans le cadre de mon doctorat, j’ai étudié la possibilité de produire le variant D67H sous forme de corps d'inclusion dans Escherichia. coli. Un protocole permettant de produire 20 mg de protéine sous forme de corps d’inclusion par litre de culture a été développé. Différents stratégies ont été testées pour replier la protéine à partir des corps d’inclusion. Cette approche a permis d’obtenir une protéine ayant 90% d’activité spécifique du lysozyme. Le rendement massique obtenu après repliement est néanmoins très faible. [less ▲]

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See detailMultiscale modelling of angiogenesis during normal and impaired bone regeneration
Carlier, Aurélie ULg

Doctoral thesis (2014)

Bone regeneration is, like many other healing events, a complex, well-orchestrated process involving a myriad of different cell types and regulated by countless biochemical, physical and mechanical ... [more ▼]

Bone regeneration is, like many other healing events, a complex, well-orchestrated process involving a myriad of different cell types and regulated by countless biochemical, physical and mechanical factors. But unlike other adult biological tissues, the majority of bone fractures can heal without the production of scar tissue, eventually recovering the original bone shape, size and strength. Despite bone’s remarkable healing capacity and the continuing research efforts, the impaired healing of complex orthopaedic cases is still not fully understood. This PhD work hypothesises that computational modelling can make a substantial contribution to the bone regeneration field by proposing and testing the underlying mechanisms of action as well as by designing and optimising experimental strategies in silico. In the first part of this work, an existing bioregulatory model of fracture healing is extended with an intracellular module of Dll4-Notch1 signalling in order to capture the ingrowth of new blood vessels through sprouting angiogenesis. The predictions of the new MOSAIC model are compared to experimental results and an extensive sensitivity analysis is performed on the newly introduced parameters. The potential of the MOSAIC model to investigate the influence of the molecular mechanisms on angiogenesis and consequently the bone formation process is illustrated. In the second part of this work, the MOSAIC model is further improved with a rigorous implementation of the influence of oxygen on the behaviour of skeletal cells. A comprehensive literature study is performed in order to ensure the correspondence of the oxygen ranges of the cell-specific oxygen-dependent processes with the state-of-the-art experimental knowledge. The oxygen model is corroborated with previously published experimental results. The robustness of the oxygen model with respect to the newly introduced oxygen thresholds is demonstrated by a sensitivity analysis. Some limitations and shortcomings of the oxygen model are identified together with suggestions for future work. In the last part of this work, the added value of the oxygen model is shown by applying it to three cases of impaired bone healing: the occurrence of nonunions in critical size defects, bone graft healing in a compromised environment and the impaired healing of bone fractures in NF1 patients. Not only is the oxygen model used to determine the underlying mechanisms of action, potential treatment strategies for the respective challenging orthopaedic conditions are also designed and optimised in silico. In conclusion, this PhD thesis demonstrates the potential of an integrative in vivo-in silico approach to advance our current understanding of bone regeneration as well as to design effective treatments of complex bone fractures. [less ▲]

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See detailÉtude des Culicoides Latreille (Diptera: Ceratopogonidae) vecteurs d'agents pathogènes: état des lieux des espèces belges, de leurs micro-habitats larvaires et de leurs préférences trophiques
Zimmer, Jean-Yves ULg

Doctoral thesis (2014)

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are the biological vectors of many recently described pathogens in Northern Europe, including the Bluetongue and Schmallenberg viruses ... [more ▼]

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are the biological vectors of many recently described pathogens in Northern Europe, including the Bluetongue and Schmallenberg viruses. These arboviral diseases have led to considerable economic loss in sheep and cattle livestock. However, many uncertainties remain regarding the distribution, biology, and ecology of these vectors. This research project had three main objectives. The first objective was to conduct an inventory of the different Culicoides species on different Belgian farms and on wetlands, using light traps. Many more Culicoides were caught in the vicinity of buildings than in meadows; this finding seemed to be influenced by the density of hosts near the trap and the opening of buildings. The Obsoletus complex was predominant inside buildings and in the meadows of farms; however, the meadows exhibited greater species diversity. The oligotrophic species C. impunctatus, a potential vector of several pathogens, was particularly abundant in peat bogs. The traps that were used herein enabled the identification of three species that have not previously been reported in Belgium, bringing the total number of Belgian species to 52. The second objective was to identify and characterize larval microhabitats of the main Belgian species of Culicoides, and to study the distribution of coprophilous species (C. chiopterus and C. dewulfi) in meadows. Ten Belgian cattle farms were monitored for two consecutive years, and sixteen substrates conducive to the larval development of these biting midges were identified. The most significant finding was that different types of silage residues (e.g., corn, grass, beet pulp, and their combinations) were favourable to the larvae of the two species that compose the Obsoletus complex. A larval microhabitat that is appropriate to these two species was also identified, for the first time, directly inside a barn: specifically, within the dried dung stuck to the barn walls and resulting from the partial removal of used litter. Therefore, Culicoides could complete their life cycle in the vicinity of the stables, which might explain the persistence of the virus from one year to the next despite harsh winters. Influences of the carbon-to-nitrogen ratio, lignin, insoluble fibre, magnesium, and calcium on the presence of larvae were also examined. The third objective was to study the feeding preferences of the species C. obsoletus. This species is prevalent on Belgian farms and has considerable medical and veterinary relevance. Behavioural analyses were performed under field and laboratory conditions, respectively through a flight tunnel containing potential hosts (human, calf, sheep and chicken) and a two-choice olfactometer containing volatile extracts of host skin. The field experiment revealed the preference of C. obsoletus females for large hosts, probably caused by greater emission of carbon dioxide. In contrast, these midges were more attracted to volatile organic compounds released from the skin surface of chicken and sheep during the laboratory experiment. This study contributed to improve the fundamental knowledge of Palaearctic species of the genus Culicoides, and highlighted promising avenues to control these biting midges. Knowledge of the breeding sites of Culicoides could thus allow substrates to be monitored and control or hygiene measures to be implemented, while preventing new sites from being created. A better understanding of the vector-host interactions may aid in developing new strategies to control adult midges, while improving understanding of the pathogen transmission cycle and the epidemiology of associated diseases. [less ▲]

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See detailControl of attosecond electronic dynamics in molecules
Mignolet, Benoît ULg

Doctoral thesis (2014)

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See detailLe rôle du commerce frontalier des produits alimentaires avec le Rwanda dans l'approvisionnement des ménages de la ville de Bukavu (Province du Sud-Kivu)
Vwima Ngezirabona, Stany ULg

Doctoral thesis (2014)

This thesis aims at highlighting the importance of food supply from the Rusizi District (Rwanda) in the food security of the city Bukavu (Democratic Republic of Congo). Due to the informal nature of this ... [more ▼]

This thesis aims at highlighting the importance of food supply from the Rusizi District (Rwanda) in the food security of the city Bukavu (Democratic Republic of Congo). Due to the informal nature of this supply, it was necessary to characterize its magnitude, drivers, and consequences as well as to develop policies that are likely to improve this supply and facilitate regional integration. The fieldwork consisted of two series of investigations. The first series of data collection included scoring the flow of food supply from Rusizi District during three months and for each of the food supply axes of Bukavu city. Secondly, a questionnaire was administered to a sample of 233 households, wherein 76 consuming households and 157 reselling households. Results from the scoring exercise show that 2,021 households on average cross both borders (Rusizi 1 and Ruzizi 2) for their food supply daily. A total of 661 of these households (about 32.7%) are direct food consumers and 1,360 households (about 67.3%) are food resellers. Excepted for cassava (which is a traditional staple of South Kivu), plantains (because of conservation problem, much more coming from within the province), and beans (much more from North Kivu), other major food products are imported from Ruzizi district in Rwanda. In this regard, the dependency ratios towards Rwanda remain much higher for products such as maize (66%), potatoes (82%), sorghum (73%), groundnut (69%), sweet potato (98%), rice (70%), and beef and pork meat (85%). With such dependency ratios, Bukavu is a major food market of the Rusizi District (Rwanda) food products. This is however far from being confirmed by official import statistics of the Congolese Control Office (CC0) which, except for rice, underestimates the border trade for a large portion of food commodities flows. The commodities analyzed provide the population of the city of Bukavu 1027 kcal per person per day from which 593.5 kcal, 338.9 kcal and 92.4 kcal are provided by products respectively from Rwanda, North-Kivu and South-Kivu. The calories consumed in the city of Bukavu are mainly of vegetable origin dominated by maize (563.1 kcal), cassava (120 kcal) and beans (167.1 kcal), which play a strategic role given their importance in the food habits of Bukavu. The significant flows of food supplies from Rusizi district are a major contribution to the livelihood of thousands of families in the city of Bukavu. It emerges that all products supplied from Rusizi district by reselling households generate positive return per month demonstrating a positive remuneration not only for the invested capital, but also for the time and effort invested in the activity (average 5.67 hours). More than 68 % of reselling households claim are satisfied with the result of this activity and allocate the generated income mainly to cover subsistence needs. In this sense, the economic impact of border trade on incomes of reselling households is a reality. The analysis of budgets of consuming households shows that 69.1% of food expenditure and 48.8% of total expenditure of consuming households cross the border. The significant impact of food supplies from the Rusizi district on reducing households’ income poverty, reflects the interests of border trade which only reinforces the structural and relative decline of the agricultural sector in South Kivu already confronted to various problems. The free trade policy advocated by a large number of sub-regional and regional communities such as CEPGL and COMESA will make the Rusizi originating food supply of Bukavu more efficient, but it remains a short-term solution of food security of the city and the province in general. In the long term, it would be better to stimulate the production and promote local food trade. To achieve this, investments need to be channeled to the agricultural sector. It is at this price that the agricultural sector in South-Kivu can be revived and reach the threshold of self-sufficiency, and even create a surplus for export. Admittedly, this solution then poses the problem of reconversion of consuming households and sellers-households that we should rethink from the outset. [less ▲]

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See detailA Frequency-domain Approach to Subspace Identification of Nonlinear Systems, Application to Aerospace Structures
Noël, Jean-Philippe ULg

Doctoral thesis (2014)

The construction of mathematical models from experimental data is an essential step in the design process of engineering systems. The different tasks involved in this activity, from the measurement and ... [more ▼]

The construction of mathematical models from experimental data is an essential step in the design process of engineering systems. The different tasks involved in this activity, from the measurement and processing of data to the validation of the model, fall into the general field of system identification. In structural dynamics, the theoretical and experimental aspects of linear system identification have been successfully addressed since the early seventies, and mature analytical, computational and testing tools have emerged. Nonlinear system identification of vibrating structures has also enjoyed significant advances during the past few years. However, the common practice in industry is to ignore nonlinearities, arguably because their analysis is still regarded as impractical. The objective of this doctoral thesis is precisely to progress towards the development of a practical system identification methodology dedicated to real-life nonlinear structures. The first facet of the thesis is to introduce a nonlinear generalisation in the frequency domain of the so-called subspace identification methods. The proposed frequency-domain nonlinear subspace identification (FNSI) approach yields accurate models of large-scale systems comprising strong nonlinearities, closely-spaced modes and high damping. Because it can also estimate a large number of parameters while maintaining an acceptable computational burden, the second facet of this research is to investigate the utilisation of cubic splines as a very flexible means to model complex nonlinearities. Finally, the third facet of the present work is to derive nonlinear models with optimal statistical properties in the presence of measurement noise. This is achieved by embedding the FNSI method into the maximum likelihood identification framework. The scope of the identification and modelling tools developed in this thesis encompasses nonlinear structural systems originating from the various areas of vibration engineering, including the aerospace, mechanical or civil fields, amongst others. Throughout the dissertation, these tools are illustrated using numerical and experimental structures of increasing complexity, mainly related to aerospace applications. [less ▲]

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See detailIncertitudes liées à la modélisation agro-environnementale en vue de développer des outils d'aide à la décision
Dumont, Benjamin ULg

Doctoral thesis (2014)

The European Nitrates Directive 91/6/76/EEC aims to ensure water quality by preventing pollution of surface and groundwater induced by nitrates originating from agricultural sources and by promoting ... [more ▼]

The European Nitrates Directive 91/6/76/EEC aims to ensure water quality by preventing pollution of surface and groundwater induced by nitrates originating from agricultural sources and by promoting agronomical good practices. While the implementation of this Directive seems effective, it appears however that the use of nitrogen has still increased by 6% over the last four years in 27 European countries. Furthermore, agricultural sources would be still at the origin of 50% of the total amount of nitrogen discharged into surface waters (http://ec.europa.eu/environment/water/water-nitrates/index_en.html). In Wallonia (Belgium), the Nitrates Directive has been transposed under the Sustainable Nitrogen Management in Agriculture Program (PGDA). Launched in 2002, it involves different sets of actions, like rules definitions concerning fertilizers application, specific and appropriate crop management in vulnerable areas, the control of potentially leachable nitrogen (APL) levels in soils, etc. This is the global context in which lies the present thesis. The main aim is to optimise the nitrogen fertiliser practices to ensure that the needs of a winter wheat culture (Triticum aestivum L.) could be met while reducing the environmental pressure. It relies on the use of crop models, which describe the growth and the development of a culture interacting with its environment, namely the soil and the atmosphere. The major difficulty while working with crop models and model-based decision support tools lies in the fact that different sources of uncertainties have an impact on the modelled phenomena. Indeed, crop models are constituted by a consequent number of differential non-linear equations, involving a lot of parameters which need to be determined as accurately as possible in order to match as close as possible observed sequences of measurements. The first source of uncertainty is thus constituted by the parameters definition. Once the model has been correctly and robustly calibrated it can be used to perform predictions. However, in an agronomical context, the time-delay between sowing and harvest is consequent. As the end-season yield is often the expected output, the uncertainty linked to the non-knowledge of the future implies for the modeller to refer to different hypothesis concerning upcoming climatic scenarios. Finally, moving from models to decision systems dealing with N management involves a last source of uncertainty. Indeed the main problem is that the impact of a given practice is delayed in time from its realisation. In addition to the uncertainty linked to climatic projections themselves, it is highly important to consider the interactions between the practices and the climate. Furthermore, in a decision-making process, it could be highly relevant to know the uncertainty's estimation that could be tolerated on the decision.. Therefore, the present thesis aims to study these different sources of uncertainty in order to design an efficient decision support system. It is divided into five parts. In the first part, a Bayesian sampling algorithm, known as DREAM (DiffeRential Evolution Adaptative Metropolis) will be presented. It was successfully coupled with the STICS soil-crop model used in this study. The a posteriori probability density function of many parameters was sampled in order to improve the simulations of the growth of a winter wheat culture (Triticum aestivum L.). The DREAM algorithm offers different advantages in comparison to usual methods. Among these, it is possible to study i) the most probable a posteriori parameters distributions, ii) the parameters correlations, and iii) the uncertainties impacted on model outputs. Furthermore, a new version of the likelihood function was proposed, making an explicit use of the coefficient of variation. Results showed that it allowed the noise existing on measurements to be considered, but also the heteroscedasticity phenomenon usually encountered in biological growth processes. In parallel, assimilation data is another way to improve models simulations. These techniques allow considering measurements performed in real-time (e.g. remote measures of LAI or soil water content) in order to correct and adjust the possible drift of model simulations. In particular, a recently developed algorithm, known as variational filter, was evaluated. Its superiority, both in term of state variables simulations improvement and parameter resampling, was demonstrated. The third part of the research focuses on the real-time end season yield prediction. It involves building climate matrix ensembles, combining different time ranges of projected mean data and real measured weather originating from the historical records. As the crop growing season progresses, the effects of real monitored data plays a greater role and the prediction reliability increases. Our results demonstrated that a reliable predictive delay of 3-4 weeks before harvest could be obtained. Finally, using real-time data acquired with a micrometeorological station enabled to (i) predict, daily, potential yield at the local level, (ii) detect stress occurrence, and (iii) quantify yield losses (or gains). Being based on projected seasonal norms, this methodology is in opposition to another technique that consists to offer a panel of solution for what concerns the future. Such probabilistic technique relies on the use of stochastic weather generator (LARS-WG in this case). However, in the fourth part of this thesis, on the basis of the convergence in law theorem, it was demonstrated that in 90% of the climatic situations, both approaches were equivalent, exhibiting RRMSE and normalised deviation criteria inferior to 10%. Furthermore the two approaches offered similar predictive delay-time. The main difference between techniques lies in the finality. The first allows to quickly simulate the remaining yield potential, while the second aims to quantify the uncertainty level associated to the predictions. In the fifth and last part of this thesis, in order to quantify the uncertainty level associated to different modalities of N applications, the STICS model answers were studied under stochastic climatic realisations. It was demonstrated that, if no N was applied, under our temperate climatic conditions, the yield distribution could be considered as normal. However, with increasing N practices, the asymmetry level was found itself increasing. As soon as N was applied, not only were the yields higher, but also was the probability to achieve yields that were at least superior to the mean of the distribution. This undoubtedly reduced the risk for the farmer to achieve low yields levels. To summary all the researches conducted in this thesis, a N strategic decision support system was developed. In a general way, for what concerns the Hesbaye Region, the superiority of three fractions N protocols was demonstrated. In addition, the three rates fertilisation management based on the systematic applications of 60 kgN.ha-1 at tillering and stem extension stages and offering the possibility to adapt the flag-leaf fraction in real-time appeared as an optimal strategy. Within this tool, the uncertainty associated to climatic variability could be finely characterised, and the risk encountered by the farmer was quantified for different investigated practices. But far more important, it was demonstrated that N management could be optimised in real-time. In a general way, the research should be pursued by studying more fundamentally and systematically a wide range of different agro-environmental situations. In particular, it would be interesting to study of the Genotype × Environment × Cultural practices interactions to ensure food security in a climatic changing world. [less ▲]

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See detailEtude du mécanisme d’activation du zymogène proDer p 6 de l’acarien Dermatophagoides pteronyssinus et du rôle de son propeptide dans l’inhibition, le repliement et l’immunogénicité de l’allergène
Herman, Julie ULg

Doctoral thesis (2014)

L’allergie aux acariens touche 20 à 30% de la population occidentale. L’allergène Der p 6 de l’acarien Dermatophagoides pteronyssinus est une protéase à sérine active de la famille de la chymotrypsine ... [more ▼]

L’allergie aux acariens touche 20 à 30% de la population occidentale. L’allergène Der p 6 de l’acarien Dermatophagoides pteronyssinus est une protéase à sérine active de la famille de la chymotrypsine. Son activité protéase pourrait être impliquée dans l’augmentation de la réponse allergique chez les patients atopiques. Der p 6 est synthétisée chez l’acarien sous la forme d’une pré-pro-protéine constituée d’un peptide signal (17 résidus) et d’un zymogène présentant un propeptide de 34 résidus en amont du domaine protéase de 231 résidus. Après avoir produit en Pichia pastoris et purifié le zymogène proDer p 6, son mécanisme d’activation a été élucidé dans la première partie de ce travail. Il s’agit d’un mécanisme tout à fait particulier, propre à l’acarien lors duquel la protéase à cystéine active Der p 1 mature proDer p 6. Un mécanisme similaire avait pu être montré pour le trypsinogène proDer p 3. Pour la première fois, la forme recombinante de Der p 6 a pu être produite. Celle-ci présente la même activité que la protéase naturelle présente dans les extraits d’acariens. Dans la seconde partie de ce travail, Der p 6 ainsi que Der p 1 ont pu être mis en évidence au niveau du tube digestif de l’acarien D. pteronyssinus, ce qui confirme que ces protéases sont impliquées dans la digestion de l’acarien. La protéase Der p 1 est présente au niveau de l’intestin moyen, tandis que Der p 6 est présente dans le gros intestin. Dans cette dernière partie de l’intestin, les protéases sont co-localisées, ce qui indique que le procédé de maturation observé in vitro pourrait se dérouler in vivo. Dans la troisième partie de ce travail, nous avons montré que le propeptide de proDer p 6 est un inhibiteur spécifique de la protéase Der p 6. Le propeptide est donc impliqué dans le contrôle spatio-temporel de l’activation de la protéase. Lors de ce processus, les quatre résidus en amont du site de clivage (résidus P4 à P1) sont nécessaires et suffisants pour la reconnaissance et le clivage du propeptide par Der p 1. Comme cela a été montré pour Der p 3, aucun rôle du propeptide dans le repliement de la protéase Der p 6 n’a pu être mis en évidence. Dans la dernière partie, une étude préliminaire de l’allergénicité de Der p 6 a été réalisée. Der p 6 serait un allergène mineur avec une prévalence d’environ 30 %. Les études par ELISA et activation des basophiles, réalisées avec les formes naturelles, recombinantes ou inactives de Der p 6 indiquent que ces différentes formes pourraient être utilisées en diagnostic. Des prédictions bioinformatiques ont également été réalisées afin de déterminer les épitopes B de Der p 6. [less ▲]

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See detailChimie Intégrative dédiée aux morphosynthèses de matériaux composites multi-échelles et étude de leurs applications en photoluminescence, photocatalyse et photovoltaïque
Kinadjian, Natacha ULg

Doctoral thesis (2014)

The shaping of functional materials and the control of their texture at all length scales are sine qua non conditions for the improvement of current systems. This PhD project consists in creating complex ... [more ▼]

The shaping of functional materials and the control of their texture at all length scales are sine qua non conditions for the improvement of current systems. This PhD project consists in creating complex solid architectures using interdisciplinary methods such as sol-gel chemistry or complex fluids physics. Therefore, it is possible to synthesize Titanium Dioxide macroscopic fibers or films which possess a hierarchical porosity. This organization allows the optimization of the matter transport (liquid/gaz) for air depollution application (photocatalysis) or dye-sensitized solar cells. In another project, we were able to control the alignment of zinc oxide nanorods within a macroscopic fiber. This alignment provides to the fiber an anisotropic photoluminescence behavior which can be useful for switching devices application. Finally, we synthesized anisotropic particles and nano-sheets of polypyrrole (conducting polymer) in order to obtain smooth thin films presenting interesting electrical properties. The objective was to use them as electrolyte and/or electrode in dye-sensitized solar cells. [less ▲]

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See detailL'ordinaire du contentieux administratif : Analyse du processus décisionnel au Conseil d'Etat belge francophone
Colemans, Julie ULg

Doctoral thesis (2014)

La thèse porte sur le processus décisionnel au Conseil d’Etat belge. Le raisonnement juridique pratique a été étudié à travers les activités concrètes que les auditeurs et conseillers accomplissent tout ... [more ▼]

La thèse porte sur le processus décisionnel au Conseil d’Etat belge. Le raisonnement juridique pratique a été étudié à travers les activités concrètes que les auditeurs et conseillers accomplissent tout au long du parcours du dossier. De cette manière, le raisonnement juridique n’est pas appréhendé comme une opération logique de la pensée mais comme un accomplissement pratique qui se déploient dans un horizon de sens partagé incarné par le concept de « raisonnable ». [less ▲]

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See detailMigration, mémoire, patrimonialisation. Étude empirique de la mémoire collective de l'exil et de l'immigration espagnols en Belgique
Molina Marmol, Maïté ULg

Doctoral thesis (2014)

Dans le prolongement de premiers travaux de recherche, la thèse de doctorat a été consacrée à l’exploration du croisement, présenté comme heuristiquement enrichissant, entre mémoire et migration, en ... [more ▼]

Dans le prolongement de premiers travaux de recherche, la thèse de doctorat a été consacrée à l’exploration du croisement, présenté comme heuristiquement enrichissant, entre mémoire et migration, en partant de l’étude empirique de la présence espagnole en Belgique. Se proposant de comparer la mémoire collective de la vague migratoire de l’exil (centré autour de l’expérience des Niños de la Guerra qui en ont composé les effectifs principaux en Belgique) et de l’immigration dite « économique » (soit d’après-guerre), la recherche s’est basée sur des terrains réalisés à Bruxelles et Liège, en tant que deux plus importants points de concentration de la population espagnole en Belgique ayant vu se sédimenter sur leur territoire les trois premières vagues migratoires. En dehors de l’évidence de logiques migratoires différentes, l’intuition d’une reconnaissance sociale inégale – au profit de l’exil –, malgré certains référents symboliques communs – dont la guerre d’Espagne –, a motivé le choix d’une approche comparative. Au niveau théorique, après avoir mêlé les apports de la sociologie de la mémoire à la perspective historienne sur ce phénomène, il s’agissait de s’émanciper du cadre des groupes politiques, se prêtant particulièrement bien à une analyse en terme de mémoire collective dans une perspective halbwachsienne et de compléter cette dernière d’une vision anthropologique davantage attentive et sensible au caractère volatile des phénomènes mémoriels et à leur imprégnation au sein de certaines pratiques quotidiennes – ce que Joël Candau a conceptualisé sous la notion de « protomémoire » . Construite autour de trois grandes parties dont l’intersection constituerait le lieu de déploiement d’une mémoire collective, la thèse envisage tour à tour la « mémoire sur les migrants » (soit le contexte des états d’origine et d’accueil et les initiatives publiques de différents ordres), « par les migrants » (à savoir les actions des associations et des entrepreneurs de mémoire) et « des migrants » (la mémoire vive). D’emblée il s’est agi d’inscrire pleinement dans l’analyse l’invention du terrain et d’une perspective théorique, la recherche se basant sur un mouvement de déconstruction/reconstruction dès la définition de ses « objets ». Par ailleurs, la réflexion méthodologique a constitué l’occasion de revenir sur les spécificités de la place et du rôle du chercheur dans la situation d’une « ethnographie indigène ». Si l’analyse a permis de conclure à l’existence d’une mémoire collective de l’exil des Niños en Belgique, elle a ouvert la question non seulement du contenu mais de l’existence, et plus particulièrement des conditions de possibilité d’une mémoire collective de l’immigration. L’analyse des discours publics, des initiatives communautaires et des entretiens individuels a conduit à poser l’hypothèse de sa localisation au croisement des mémoires militantes, ouvrières et ethniques. Le cas espagnol a bien constitué dans ce cadre un terrain d’élection, de par l’ambiguïté structurelle entre « exil politique » et « immigration économique » qui a d’emblée été posée et qui ne s’est pas avéré sans répercussions en termes mémoriels – notamment en termes d’établissement d’un « espace du dicible ». Mais si tant les dimensions ethnique et militante de l’expérience migratoire et de sa mémoire peuvent être qualifiées de « collectives », il reste que situer à leur intersection une mémoire collective de l’immigration constituerait une opération de réduction, évacuant toute une part de cette mémoire, celle la plus difficilement appréhendable, notamment portée par les femmes et se jouant dans la labilité des gestes quotidiens et des espaces de vie. [less ▲]

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See detailDynamique et composition des atmosphères supérieures de Mars et Vénus observées par les spectrographes ultraviolets à bord de Mars Express et Vénus Express
Stiepen, Arnaud ULg

Doctoral thesis (2014)

Venus has a dense CO2-dominated atmosphere. Above 50 km, the atmospheric circulation is composed of two dominants patterns: the Retrograde Superrotating Zonal (RSZ) circulation up to 65 km and the ... [more ▼]

Venus has a dense CO2-dominated atmosphere. Above 50 km, the atmospheric circulation is composed of two dominants patterns: the Retrograde Superrotating Zonal (RSZ) circulation up to 65 km and the subsolar to antisolar (SSAS) circulation beyond 120 km. The SSAS is caused by the temperature gradient between the day and the night hemispheres and it generates a global flow from the dayside to the nightside. Between 65 and 120 km, the circulation is complex as it is the superposition of the two main components. I have used the nightglow emitted by the NO* molecule (180-300 nm) produced by recombination of N(4S) and O(3P) atoms. These atoms are created by photodissociation of N2 and CO2 molecules on the dayside and carried to the nightside by the SSAS circulation. I analyze the full set of measurements of the NO δ and γ bands measured by the SPICAV instrument on board the ESA Venus Express spacecraft. I discuss the altitude and brightness of the emission peak (60 kR at 115 km) and show that the emission profile exhibits a secondary peak in ~10% of the cases. This additional peak is probably caused by upward-moving gravity waves propagating from below. I have developed an inversion method of the observed limb profiles to compare the results with a chemical-diffusive model of the atmosphere of Venus and constrain the vertical fluxes of N and O. On the basis of an extended statistical analysis, I characterize the presence of a bright spot of the nightglow of NO shifted from the antisolar point and located around 0230LT, 10°S. I use the vast SPICAV airglow database to statistically demonstrate that the NO nightglow is highly variable, both temporally and spatially. Mars experiences seasons as its rotation axis is inclined from its spin axis. Its upper atmospheric dynamics is dominated by summer-to-winter global transport. I study the upper atmosphere of Mars using nightglow observations performed by the SPICAM instrument on board ESA’s Mars Express spacecraft. I analyze the δ and γ bands of molecule NO in the nightside mesosphere to confirm, on statistical basis, the peak brightness and altitude of the NO UV emission (5 kR at 72 km). I show that the NO nightglow is located following the relation Latitude = -80xsin(Solar Longitude), in agreement with results based on stellar occultations and from the LMD model, which simulates the photochemistry and dynamics of the Mars atmosphere. I have performed a detailed study of the CO Cameron band (170 to 270 nm) and CO2+ doublet (290 nm) dayglow. I have developed a method to deduce the temperature profile around 150 km, an important study as the distribution of the temperature in the Mars atmosphere is poorly known. I showed that the temperature at high altitude is only weakly correlated with the solar EUV flux. This result suggests that the variability of the upper atmosphere may include internal processes. Comparisons with the Mars Global Ionosphere Thermosphere Model show that the model can reproduce the observation for high solar conditions but predicts lower temperature for low to moderate solar conditions. Further study will therefore be necessary to identify and understand the mechanisms that govern the temperature variability. [less ▲]

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