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See detailMéthodes d'accélération du tir de rayons sonores pour la simulation en acoustique des salles
Lesoinne, Stephane ULg

Doctoral thesis (2014)

This thesis provides methods to speed up the acoustical ray tracing for room acoustics. These methods uses 3 complementary axes that have been implemented, tested and analyzed: CPU vectorization, a ... [more ▼]

This thesis provides methods to speed up the acoustical ray tracing for room acoustics. These methods uses 3 complementary axes that have been implemented, tested and analyzed: CPU vectorization, a geometry preprocessing based on visibility and a decrease in the number of traced rays by using variable size receivers. This results in a overall gain that ranges from 120 to 150 on a 8core CPU. [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 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 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 detailControl of attosecond electronic dynamics in molecules
Mignolet, Benoît ULg

Doctoral thesis (2014)

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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 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 detailModélisation 2D par éléments finis du contact : effet de l’utilisation de méthodes de représentation des surfaces présentant un ordre de continuité élevé et méthodes permettant de passer le patch test
Nguyen, Duc Tue ULg

Doctoral thesis (2014)

Ce travail de thèse concerne la mécanique numérique du contact entre les solides déformables. La simulation numérique des problèmes de contact comporte de nombreuses difficultés notamment dans un contexte ... [more ▼]

Ce travail de thèse concerne la mécanique numérique du contact entre les solides déformables. La simulation numérique des problèmes de contact comporte de nombreuses difficultés notamment dans un contexte de grands déplacements et de grandes déformations. Le but de ce travail est d’analyser l’influence de l’ordre de continuité élevé de la représentation de surface et de développer une méthode pour passer le patch test, à savoir qu’un élément passe le patch test si il transmet correctement des pressions de contact entre deux surfaces. Pour la discrétisation des éléments finis, l'interface de contact est représentée par une série de lignes et de courbes à continuité C0. Par conséquent, lors du passage du nœud esclave entre deux segments maîtres adjacents, il peut arriver avoir une discontinuité de la direction du vecteur normal. Cette situation peut mener à des problèmes de convergence de l'algorithme de résolution. Pour éviter ce problème, l’approche proposée consiste à développer les représentations de surface maître à ordre de continuité C1 ou C2 pour les éléments nœud-surface linéaires et quadratiques. Les éléments nœud-surface ne passent pas le patch test. Plus récemment, un élément linéaire utilisant la méthode des nœuds esclaves virtuels pour Passer le Patch Test (PPT) a été proposée dans la littérature. Cependant, cet élément est à ordre de continuité C0 et peut donner des grandes oscillations de la pression de contact à cause des pénétrations initiales des nœuds esclaves virtuels qui sont les pénétrations des nœuds esclaves virtuels dans la surface maître à l’état initial. Pour tenter de surmonter cette difficulté, une nouvelle approche repose sur un élément linéaire utilisant la méthode PPT et la représentation de surface à ordre de continuité C1 pour la surface maître et pour la surface esclave. L’élément quadratique nœud-surface donne des oscillations de pression de contact à cause de la distribution non-uniforme des forces nodales. Afin de résoudre ce problème, la méthode PPT est développée pour l’élément quadratique. [less ▲]

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See detailIntegration of near-surface geophysical, geological and hydrogeological data with multiple-point geostatistics in alluvial aquifers
Hermans, Thomas ULg

Doctoral thesis (2014)

Alluvial plains constitute essential geological bodies for environmental studies such as contaminated sites remediation, low-enthalpy geothermal energy or groundwater resources. The heterogeneity of these ... [more ▼]

Alluvial plains constitute essential geological bodies for environmental studies such as contaminated sites remediation, low-enthalpy geothermal energy or groundwater resources. The heterogeneity of these deposits governs flow processes and needs to be quantified. A proper description of such complex deposits requires an integrated approach combining geological, geophysical and hydrogeological data. Solving such spatial inverse problems in the Earth Sciences remains a considerable challenge given the large number of parameters to invert for, the non-linearity of forward models and, as a result, the ill-posedness of the problem. Geostatistics is therefore needed to specify prior models, more particularly, information to control the spatial features of the inverse solutions. Two-point geostatistical approaches have been developed to describe the heterogeneity of one geological formation but fail to reproduce the heterogeneity of fluvial deposits with multiple facies. Multiple-point statistics (MPS) introduced the training image (TI) concept to replace the variogram within an extended sequential simulation framework. The use of geophysics to constrain such simulations has been studied in the petroleum industry with wave-based methods (seismic reflection), but little research has been done to assess the use of near-surface potential methods to condition MPS in environmental studies. In this work, we propose to integrate geological (borehole logs), geophysical (electrical resistivity tomography (ERT) profiles) and hydrogeological (hydraulic heads) data within MPS models on the alluvial plain of the Meuse River, Belgium. Potential-based geophysical methods being integrative, they suffer from a relatively poor resolution. We first study how we can improve the informative content of geophysical inversion by including prior information in the ERT inverse problem. Three methods are tested and compared in several field cases, namely the reference model inversion, the structural inversion and the regularized geostatistical inversion. If every method has advantages and drawbacks, the best suited method for the considered problem is the regularized geostatistical method. Electromagnetic borehole logs enable to derive the vertical correlation length of electrical resistivity in the deposits and to subsequently use it to constrain the inversion. In addition to the knowledge of the bedrock position, it enables to retrieve an electrical resistivity distribution of the deposits close to direct observations. This ensures that geophysical models will be informative to constrain MPS simulations. Given the lack of geological and sedimentological data to build accurate TIs, a data base of TIs is built using several different parameters and scenarios. They are all based on a three facies description: clay/loam, sand and gravel corresponding to low, intermediate and high hydraulic conductivity. Then, we develop a methodology to verify the consistency of independently-built TIs with geophysical data. Our methodology starts by creating subsurface models with each TI. From these models we create synthetic geophysical data and from this synthetic data, synthetic inverted models. These models are now compared with a single inverted model obtained from the field survey, allowing for our definition of what is ``consistent''. To that extent, we calculate the Euclidean distance between any two inverted models as well as field data and visualize the results in a 2D or 3D space using multidimensional scaling (MDS). With this technique, it is possible to verify if field cases fall in the distribution represented by synthetic cases, and thus are consistent with them. In a second step, we present a cluster analysis on the MDS-map to highlight which parameters are the most sensitive for the construction of TI. Based on this analysis, a probability of each geological scenario is computed through kernel smoothing of the densities in reduced projected metric space. The integration of hydrogeological data is made through a stochastic inversion method: the probability perturbation method (PPM), using MPS constrained with geophysical data to generate models. The PPM algorithm automatically seeks solutions fitting both hydrogeological data and training-image based geostatistical constraints. Only geometrical features of the model are affected by the perturbation, i.e. we do not attempt to directly find the optimal value of hydrogeological parameters (chosen a priori), but the optimal spatial distribution of facies whose prior distribution is quantified in a training image. Tracing experiments may be used to further constrain hydrogeological models. ERT has proven its ability to monitor salt tracer tests, but few studies have investigated its performances in thermal tracing experiments. In this study, we demonstrate the ability of surface and crosshole ERT to image quantitatively temperature changes during heat injection experiments. Such resistivity data provides important information to improve hydrogeological models. Our study proves that ERT, especially crosshole ERT, is a reliable tool to follow thermal tracing experiments. It also confirms that ERT should be included to in situ techniques to characterize heat transfer in the subsurface and to monitor geothermal resources exploitation. [less ▲]

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See detailUtilisation de biocapteurs microbiens GFP pour la caractérisation des performances des bioréacteurs
Brognaux, Alison ULg

Doctoral thesis (2014)

The scale-up of bioprocesses is a critical step during bioproducts development. Actually, the mixing operation’s efficiency drops when the reactor volume increases: gradients of glucose and oxygen appear ... [more ▼]

The scale-up of bioprocesses is a critical step during bioproducts development. Actually, the mixing operation’s efficiency drops when the reactor volume increases: gradients of glucose and oxygen appear when operating in fed-batch mode, causing losses of production. The aim of this project is the scale-up and sizing of bioreactors based on the direct physiological parameters to consider this heterogeneity. Concretely, it consists in obtaining an on-line signal of the physiological status of micro-organisms. The coding sequence of the Green Fluorescent Protein (GFP) has been inserted after gene promoters of interest in Escherichia coli to built biosensors. A particular focus has been paid on promoters responding to general stress or specifically to lack of glucose and on those responding to cell growth rate. The GFP biosensors of interest have been tested in scale-down bioreactors, allowing to reproduce industrial hydrodynamic conditions at a laboratory scale. A mini-bioreactor platform has also been developed to enable a high throughput screening of biosensors. The intracellular accumulation of GFP has been measured by flow cytometry and GFP release has been monitored by western blot analyses. For biosensors sensitive to stress general response or glucose limitation, GFP has been induced during a glucose limitation and repressed by comparison when glucose heterogeneities appear. The use of a destabilized GFP has been considered in this project for ribosomal biosensors to approach more instantaneous physiological responses of microorganisms. For these ones, the response is proportional to growth rate during the batch phase, but more complex mechanisms take part during a prolonged glucose limitation. Membrane permeability has also been studied and has been noticed more important in homogeneous fed-batch bioreactors than in scale-down reactors. As GFP leakage has been noted in the extracellular medium, a study has also been carry out about proteins released in the extracellular medium (leakage), and correlated with the cell permeability. Finally, an on-line flow cytometer has been developed for the characterization of physiological status of micro-organisms during the bioprocess, and a 3D-ORM probe allowed to measure their viability on-line [less ▲]

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See detailDétermination de la broyabilité des plaquettes et des pellets de bois
Temmerman, Michaël ULg

Doctoral thesis (2014)

The literature about energy requirements for product milling in mining industry shows the subject has been, and still is, considered by numerous authors. Several milling theories have been proposed for ... [more ▼]

The literature about energy requirements for product milling in mining industry shows the subject has been, and still is, considered by numerous authors. Several milling theories have been proposed for these industries, especially concerning ores milling. Biomass milling, prior to its use as biofuel, has been, by far, less studied. Nevertheless, few measurements are available about energy needed for milling of particular biomass, in particular systems. But studies taking into account enough characteristic of the milled material (origin, moisture content, particle size distribution) are scarce. Moreover, the methods used to measure these properties are generally different. In consequence, nearly none biomass milling model has been proposed. Concerning wood densified product (pellets & briquettes) apparently no data are available yet. . This study draws upon the milling theories developed for the ore processing industry (Von Rittinger, Kick and Bond theories which have been merged by Charles and Hukki) in order to define a method for characterizing wood chip and pellet energy consumption during milling. Thus it proposes parameters and measurement methods that have to be taken into account when milling modelling comes to an end for biomass or densified biomass Energy consumption during wood milling depends on three main factors: the material moisture content, the particle size difference between the feed and the milled product, and the material itself. The latter may be characterized by a single grindability parameter based on an adaptation of Von Rittinger’s constant. A relation characterizing wood pellet energy consumption as a function of the particle size distribution of the pellet ingredients and the milled pellets is proposed as well. This is characteristic of each type of pellet for each moisture content value considered [less ▲]

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See detailL’antonymie. Définition de l’antonymie en langue et description des fonctions sémantico-référentielles de la co-présence antonymique en discours
Steffens, Marie ULg

Doctoral thesis (2014)

Grâce à un examen critique des travaux consacrés à l’antonymie, nous avons pu définir l’antonymie comme une relation multiforme qui touche des unités très différentes sur les plans sémantique et morpho ... [more ▼]

Grâce à un examen critique des travaux consacrés à l’antonymie, nous avons pu définir l’antonymie comme une relation multiforme qui touche des unités très différentes sur les plans sémantique et morpho-syntaxique mais dont l’unicité réside dans une opposition binaire fondamentale enracinée lexicalement. Nous avons ainsi dépassé la simple distinction entre contraires et contradictoires pour entrer dans la fascinante diversité de l’opposition et montrer comme les notions de graduation, de graduabilité, de scalarité, de borne et de seuil se combinent pour forger l’identité sémantique de chaque paire d’antonymes, la rapprocher ou la distinguer des autres. Grâce à l’analyse empirique d’énoncés extraits du journal Le Monde, nous avons montré que la co-présence antonymique en contexte s’appuie pour faire sens sur les relations antonymiques inscrites dans la mémoire linguistique des locuteurs, où sont fortement associées la forme et le sens des antonymes. Nous avons également montré comment la plongée de deux antonymes dans un contexte d’emploi peut moduler leur opposition et la définition du lexème neutre ou intermédiaire, lorsqu’il existe. Les antonymes co-présents, grâce aux rôles sémantico-syntaxiques qu’ils peuvent jouer, contribuent à la structuration des énoncés dans lesquels ils sont employés parce qu’ils organisent les unités qui les entourent sur le plan sémantico-référentiel. [less ▲]

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See detailCharacterization of thin layers into concrete with Ground Penetrating Radar
Van der Wielen, Audrey ULg

Doctoral thesis (2014)

The Ground Penetrating Radar (GPR) is a non-destructive method used for roads and buildings inspection: it is well adapted to detect the different layers constituting the structures. The objective of this ... [more ▼]

The Ground Penetrating Radar (GPR) is a non-destructive method used for roads and buildings inspection: it is well adapted to detect the different layers constituting the structures. The objective of this thesis is to develop a method for a fast determination of the properties of a buried layer on the basis of surface GPR measurements. The observation of the GPR waves propagation in numerical simulations led to develop an analytical model, which could be applied to the experimental determination of laboratory layered structures. [less ▲]

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See detailNonlinear Modal Analysis of Conservative and Nonconservative Aerospace Structures
Renson, Ludovic ULg

Doctoral thesis (2014)

The concept of nonlinear normal modes (NNMs) provides a solid and rigorous theoretical framework for the analysis of the nonlinear oscillations of mechanical systems. If NNMs have been studied since more ... [more ▼]

The concept of nonlinear normal modes (NNMs) provides a solid and rigorous theoretical framework for the analysis of the nonlinear oscillations of mechanical systems. If NNMs have been studied since more than fifty years, it is only very recently that contributions dealing with their numerical calculation have been reported in the literature. Although these methods pave the way for the application of NNMs to more complex systems, they have not yet reached the necessary maturity. In this context, the purpose of this research is (i) to further investigate the performance of an existing method for computing the NNMs of conservative systems and (ii) to propose two new methods for the computation of NNMs of nonconservative systems. The first contribution of this thesis is to calculate the NNMs of a real-life aerospace structure, the SmallSat spacecraft developed by EADS Astrium. An algorithm that combines an advanced shooting method with the pseudo-arclength continuation technique is utilized. We show that the NNMs provide a very useful interpretation of the strongly nonlinear dynamics of the spacecraft. One specific contribution is to numerically reproduce with great fidelity several interactions between modes with noncommensurate linear frequencies that were observed experimentally. The second original contribution of this thesis is to develop two new methods for computing the NNMs of damped systems. The first method solves the partial differential equations (PDEs) governing the geometry of the NNM. The PDEs are recognized as hyperbolic, and it is shown that they require appropriate numerical treatments including specific boundary conditions. The proposed method combines a streamline upwind Petrov-Galerkin finite-element formulation with a resolution strategy based on annular domains to grow sequentially the manifold. The algorithm is demonstrated using a wide variety of systems ranging from two-degree-of-freedom to multi-degree-of-freedom nonlinear systems with linear and nonlinear damping. The applicability of the algorithm to complex real-life structures is demonstrated using a full-scale aircraft. The second method presented in this work computes a NNM as a collection of trajectories defined with boundary value problems (BVPs). The method has the distinctive advantage that it does not rely on a parameterization of the NNM. It is demonstrated on two-degree-of-freedom examples featuring linear and nonlinear damping. [less ▲]

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See detailDroit électoral et principe d'égalité. L'élection des assemblées législatives nationales en droit allemand, belge et britannique
Bouhon, Frédéric ULg

Doctoral thesis (2014)

The study concerns the election law and the equality principle in three European legal systems, i.e. the Federal Republic of Germany, the Kingdom of Belgium and the United Kingdom. In this framework, the ... [more ▼]

The study concerns the election law and the equality principle in three European legal systems, i.e. the Federal Republic of Germany, the Kingdom of Belgium and the United Kingdom. In this framework, the research is structured into two principal questions. I firstly wonder whether the election law guarantees equality among the governed people. Should the answer to that question be negative, I secondly check if the inequality can be legally justified in democratic systems. My thesis is a nuanced answer to these questions. The work shows that election law, considered under the scope of the equality principle, includes two categories of legislations which effect is opposed: some legal rules tend to distribute equally the faculty to influence the composition of the elected assemblies, while others tend to distribute unequally that faculty. Among the rules of the second category, I argue that the tendency to inequality can be partly legally justified by the purposes of these rules, but is also a mean – hardly justifiable in a democratic system – that helps persons and parties in government to remain in power. [less ▲]

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See detailAcoustic communication in Ophidiiformes: a case study using Ophidion rochei
Kever, Loïc ULg

Doctoral thesis (2014)

A ce jour, la biologie des Ophidiiformes reste peu connue car la majorité des espèces de ce groupe est inféodée aux eaux profondes. Celles qui ne le sont pas ont adopté un mode de vie nocturne, passant la ... [more ▼]

A ce jour, la biologie des Ophidiiformes reste peu connue car la majorité des espèces de ce groupe est inféodée aux eaux profondes. Celles qui ne le sont pas ont adopté un mode de vie nocturne, passant la journée cachées dans le sable, les anfractuosités d’un récif, ou un hôte invertébré en fonction de l’espèce considérée. Des études antérieures ont montré que les appareils de production de sons des Ophidioidei (Ophidiidae et Carapidae) sont complexes et présentent des différences interspécifiques marquées. De plus, l’oreille interne est généralement bien développée. Ces poissons étant actifs dans le noir, la communication acoustique devrait tenir un rôle important dans leur biologie. Ce travail de recherches s’attèle, par différentes approches, à étudier cette thématique en utilisant Ophidion rochei comme cas d’étude. Cet Ophidiidae psammobionte, présente un dimorphisme sexuel marqué au niveau de l’appareil de production de sons avec notamment la présence chez les mâles d’une structure minéralisée à l’avant de la vessie natatoire : le « rocker bone ». Pour mieux cerner la fonction des différentes structures intervenant dans la production et la réception de sons, des comparaisons ont été réalisées avec deux Carapidae : Onuxodon fowleri pour la production de sons et Carapus acus pour la réception de sons. L’étude établit que les espèces O. rochei et C. acus peuvent entendre les sons de leurs conspécifiques. Cependant, l’apport principal de cette partie est la démonstration que la grande taille des otolithes (en valeur absolue ou relative) n’est pas liée à de meilleures capacités auditives. De gros otolithes seraient principalement associés à une plus grande acuité de l’appareil stato-acoustique pour des espèces vivant dans des milieux accidentés. Les mâles et les femelles O. rochei produisent des sons uniquement après le coucher du soleil, durant la période de reproduction qui se déroule de juin à octobre. Ces sons apparaissent courts et tonaux chez les femelles, longs et pulsés chez les mâles. Ces différences dans les signatures acoustiques sont clairement liées au dimorphisme sexuel marqué bien qu’un patron moteur commun soit conservé chez les deux sexes. Brièvement, le muscle sonique dorsal servirait à mettre la vessie natatoire sous tension et le muscle sonique ventral serait à l’origine de l’émission de chaque pulse. De plus, les mâles présentent dans les caractéristiques sonores des différences individuelles marquées qui doivent refléter leur statut reproducteur et/ou leur taille. Chez O. fowleri, les deux sexes possèdent des « rocker bones » de taille et de forme différentes. Les sons enregistrés sont uniquement pulsés, mais ces poissons se distinguent de nombreux téléostéens par leur capacité à moduler le taux de pulsation. La comparaison des morphologies et mécanismes permet de soutenir l’hypothèse selon laquelle les « rocker bones » des deux taxa sont le résultat de convergences évolutives. Chez beaucoup de téléostéens, les sons sont utilisés pour supporter des stimuli d’ordre visuel. Les Ophidioidei étant actifs dans le noir, les contraintes évolutives ont principalement dû se marquer au niveau de l’appareil producteur de sons. En conclusion, la morphologie des appareils de production de sons, le dimorphisme sexuel, les caractéristiques uniques des sons produits, leur moment d’émission dans l’année et dans la journée soulignent la place importante de la communication acoustique au sein des Ophidioidei. [less ▲]

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See detailProduction, transformation artisanale et commercialisation locale des produits alimentaires traditionnels au Vietnam: le cas du vermicelle de tolomane à Hung Yen
Le, Thi Long Vy ULg

Doctoral thesis (2014)

In Vietnam, the vermicelli of Canna edulis Ker Gawl. (C. indica L.) is an artisanal and traditional product, regularly consumed in the festive occasions. From Canna edulis Ker Gawl cultivation to trading ... [more ▼]

In Vietnam, the vermicelli of Canna edulis Ker Gawl. (C. indica L.) is an artisanal and traditional product, regularly consumed in the festive occasions. From Canna edulis Ker Gawl cultivation to trading of vermicelli of Canna edulis at the local level, the vermicelli commodity chain belongs to peasant economy with many actors involved. This research aims at a better understanding of how the actors of vermicelli commodity chain adapt to current socio-economic and environmental conditions of the villages which belong to two communes (Tu Dan and Yen Phu) located in Hung Yen Province. The surveys among 90 farmers and discussions with a group of producers who cultivate the canna and practice flour processing, and a group of vermicelli processors have been carried out from 2010 to 2012. According to our research results, vermicelli commodity chain has created a considerable additional quantity of jobs for local people within the villages of vermicelli processing and the neighboring ones. Thanks to these activities, the rural households income and production investment have been increased. Net income estimated per hectare of canna is about 22.2 million VND (about 822 €), and nearly 4.5 million VND (167 €) per ton of flour produced, and up to 1.7 million VND per ton of vermicelli product (about 63 €). In addition, these activities allow to diversify the sources of family incomes in the countryside. These activities also contribute to stabilize and increase the living standard of farmers (in 2010, the net family income (NFI) due to canna production accounted for 8% to 34 % of farming income; the NFI of vermicelli processing represented between 35% and 86 % of total processing family income). The value-added generated from this vermicelli commodity chain is important, up to 186 million VND (about 7,900 €) per hectare of canna, in which 38 % for flour processing; 20% for vermicelli processing and 20 % for canna cultivators. Thus, the vermicelli commodity chain contributes to meet a specific demand for traditional food in Vietnam. This chain contributes to the rural economy of traditional villages through improving the sources of familial income. However, it is necessary to increase the product quality and to improve the vertical and horizontal linkages between the actors in order to guarantee the sustainable development of this vermicelli chain. [less ▲]

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See detailMénages ruraux et lutte contre la pauvreté : cas des communes de Tu Ly et de Xuang Phong dans la province de Hao Binh Viet Nam
Mai, Lan Phuong ULg

Doctoral thesis (2014)

Since 1998, Viet Nam developed many poverty reduction strategies with the assistance of the WB and the IMF. However, although the national rate of poverty decreased in absolute terms, it does not reflect ... [more ▼]

Since 1998, Viet Nam developed many poverty reduction strategies with the assistance of the WB and the IMF. However, although the national rate of poverty decreased in absolute terms, it does not reflect a real reduction in poverty and does not take into account the nature of poverty. Income and opportunities inequality increased between urban and rural areas, between different social classes and between the Kinh (majority group in Viet Nam) and ethnic minorities. Poverty of ethnic minorities has become an ongoing challenge. In 2010, there were 66.3% of the poor among ethnic minorities against only 12.9% for the Kinh population. This thesis illustrates a reflection on the issue of poverty in Viet Nam and in particular mountainous northern regions where the poverty rate is the highest, reaching 39.4 % in 2012. The historical approach, the capacity approach, the descriptive statistical analysis and case analysis are used to conduct this research. The first difficulty is the identification of poor households and beneficiaries of poverty reduction strategies. Other difficulties are disclosed by the analysis of strategies against poverty: information confusion, budget limitation, insufficient participation of local people in program planning and monitoring, limited autonomy at the local level. Finally it appears that strategies against poverty are not efficient. In addition, land resource privatization, particularly forest resources, limits minority farmers’ ability to cope with unexpected risks Faced with this situation, a possible solution could be to strengthen the role of farmers' associations. Taking into account the ideas and initiatives of local actor, driven by farmers' associations, would have a positive impact on the poverty reduction strategy. Donations and subsidies to individuals should no longer be practiced. In the present threatening world, solidarity among small farmers is necessary to enable them to find their place in the production system and keep the justified profits. In the long run, it is better to give financial support to assist groups and support initiatives by associations of small farmers to facilitate their participation in the market economy while improving their well-being. [less ▲]

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See detailAudiovisual spatial congruence, and applications to 3D sound and stereoscopic video
André, Cédric ULg

Doctoral thesis (2014)

While 3D cinema is becoming increasingly established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D ... [more ▼]

While 3D cinema is becoming increasingly established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D) movie. The perceptual relevance of such spatial audiovisual coherence is of significant interest. In this thesis, we investigate the possibility of adding spatially accurate sound rendering to regular s-3D cinema. Our goal is to provide a perceptually matched sound source at the position of every object producing sound in the visual scene. We examine and contribute to the understanding of the usefulness and the feasibility of this combination. By usefulness, we mean that the technology should positively contribute to the experience, and in particular to the storytelling. In order to carry out experiments proving the usefulness, it is necessary to have an appropriate s-3D movie and its corresponding 3D audio soundtrack. We first present the procedure followed to obtain this joint 3D video and audio content from an existing animated s-3D movie, problems encountered, and some of the solutions employed. Second, as s-3D cinema aims at providing the spectator with a strong impression of being part of the movie (sense of presence), we investigate the impact of the spatial rendering quality of the soundtrack on the reported sense of presence. The short 3D audiovisual content is presented with three different soundtracks. These soundtracks differ by their spatial rendering quality, from stereo (low spatial coherence) to Wave Field Synthesis (WFS, high spatial coherence). The original stereo version serves as a reference. Results show that the sound condition does not impact on the sense of presence of all participants. However, participants can be classified according to three different levels of presence sensitivity with the sound condition impacting only on the highest level (12 out of 33 participants). Within this group, the spatially coherent soundtrack provides a lower reported sense of presence than the other custom soundtrack. The analysis of the participants' heart rate variability (HRV) shows that the frequency-domain parameters correlate to the reported presence scores. By feasibility, we mean that a large portion of the spectators in the audience should benefit from this new technology. In this thesis, we explain why the combination of accurate sound positioning and stereoscopic-3D images can lead to an incongruence between the sound and the image for multiple spectators. Then, we adapt to s-3D viewing a method originally proposed for 2D images in the literature to reduce this error. Finally, a subjective experiment is carried out to prove the efficiency of the method. In this experiment, an angular error between an s-3D video and a spatially accurate sound reproduced through WFS is simulated. The psychometric curve is measured with the method of constant stimuli, and the threshold for bimodal integration is estimated. The impact of the presence of background noise is also investigated. A comparison is made between the case without any background noise and the case with an SNR of 4 dBA. Estimates of the thresholds and the slopes, as well as their confidence intervals, are obtained for each level of background noise. When background noise is present, the point of subjective equality (PSE) is higher (19.4° instead of 18.3°) and the slope is steeper (-0.077 instead of -0.062 per degree). Because of the overlap between the confidence intervals, however, it is not possible to statistically differentiate between the two levels of noise. The implications for the sound reproduction in a cinema theater are discussed. [less ▲]

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See detailLa résilience chez les plus vulnérables au Rwanda
Militery Ngamata, Olivier ULg

Doctoral thesis (2014)

After the tragedy of the genocide against Tutsi in 1994, the Rwandan Government has developed and implemented different programmes and interventions in the sector of social protection in order to reduce ... [more ▼]

After the tragedy of the genocide against Tutsi in 1994, the Rwandan Government has developed and implemented different programmes and interventions in the sector of social protection in order to reduce the poverty of the vulnerable populations and so reach the Millennium Development Goals (MDGs). The different interventions done in the context of social security of the poor people are considered as means of increasing the economy, integrating people in employment market, improving human development thanks to a better access to health and education, and reducing poverty. After the context and justification of the research as well as the methods for data collection, this study focuses primarily on the conceptualization of resilience and connected concepts. Secondly, it scrutinizes the impact of the three programmes of social protection that were developed to reduce poverty of the beneficiaries. The first programme is FARG that supports the survivors of the 1994 genocide against the Tutsi in the domain of education, access to accommodation, medical health and income generating activities. The second programme is Ubudehe-VUP-2020. This one helps very poor households via direct financial transfers, creation of jobs and access to financial services. Girinka is the third programme; it contributes to food improvement, subsistence means and land fertility by supplying a dairy cow to poor families. In third position, this research assesses the achievements of the association of the widows survivors of genocide called - Agahozo (AVEGA) as well as the successes so far reached by the widows beneficiaries. The widows consider AVEGA as an important ‘tutor for resilience’ because it not only deals with their psychological aspects related to the tragedies they experienced but also the promotion and development of economic activities that can supply them with an income for their social reintegration at both economic and social levels. Thus, AVEGA involves a diversity of actors in order to help the widows and implement various income generating activities. Research conducted on the field has targeted, in last position, the most resilient widows. These widows have got support from social protection programmes and AVEGA, in order to involve in income generating activities among which the most developed are agriculture, animal rearing and commerce. All in all, the widows of genocide who were surveyed positively commented the support they get from SPP and AVEGA regarding the reinforcement of their economic resilience. [less ▲]

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See detailEtude des possibilités de culture de Jatropha curcas L. dans la région de Kinshasa en République Démocratique du Congo (RDC)
Minengu Mayulu, Jean de Dieu ULg

Doctoral thesis (2014)

Au cours de ces dernières années, des plantations de Jatropha curcas L. ont été mises en place dans de nombreuses régions d’Afrique subsaharienne pour la production d’agrocarburants sans connaissances ... [more ▼]

Au cours de ces dernières années, des plantations de Jatropha curcas L. ont été mises en place dans de nombreuses régions d’Afrique subsaharienne pour la production d’agrocarburants sans connaissances préalables des conditions de rentabilité et des techniques de production les mieux adaptées aux contextes locaux. L’objectif du présent travail est de lever cette lacune pour la région de Kinshasa en apportant des réponses aux principales questions qui conditionnent la mise au point d’un agrosystème durable basé sur la culture de J. curcas. Pour atteindre cet objectif, les performances d’une plantation pilote installée à proximité de la cité de Mbankana en décembre 2007 ont été évaluées et quatre essais ont été réalisés à partir de juillet 2009 à janvier 2013 dans deux sites représentatifs des conditions du Plateau des Batéké (Mbankana et Mongata) et à proximité de la rivière N’sele dans la banlieue de Kinshasa. Les résultats obtenus montrent que les facteurs de l’environnement et les pratiques culturales ont une influence sur le rendement en graines et en huile de J. curcas. Les faibles rendements obtenus, le coût très élevé des intrants (engrais et insecticides) et les faibles quantités de graines récoltées par journée de travail sont les principales causes de l’absence de rentabilité de la culture pure de J. curcas dans les premières plantations mises en place avec du matériel végétal local subspontané. Les principaux insectes ravageurs de J. curcas dans la zone d’étude sont les grillons Brachytrupes membranaceus Drury (Orthoptera, Grillidae) qui s’attaquent aux jeunes plantes lors de leur mise en place en saison pluvieuse (octobre à décembre), les chenilles mineuses de feuilles Stomphastis thraustica Meyrick (Lepidoptera, Gracillariidae), les chrysomèles Aphthona sp. (Coleoptera, Chrysomelidae) qui consomment le limbe des feuilles et les bourgeons, ainsi que les punaises à bouclier Calidea sp. (Heteroptera, Scutelleridae) qui causent des dégâts aux fleurs et aux capsules. Parmi ceux-ci, la chrysomèle est pour l’instant le ravageur le plus dommageable. En l’absence de traitements insecticides, le niveau des pertes de rendement occasionnées par ces insectes ravageurs atteignent 90% en culture pure sur le Plateau des Batéké. La gravité des dégâts des insectes ravageurs sur J. curcas est plus élevée en culture pure (>60%) que quand il est associé à d’autres cultures annuelles (<45%). La mise au point de méthodes durables de contrôle des ravageurs est une des conditions indispensables à l’installation de plantations de J. curcas dans la région de Kinshasa. L’application de la taille, de la fertilisation minérale et de la couverture du sol avec Stylosanthes guianensis (Aublet) Swartz, permet d’améliorer significativement le rendement en graines de J. curcas Onze écotypes de J. curcas, collectés dans les différentes régions de la RDC et mis en culture au Plateau des Batéké, ont montré des différences significatives en termes du développement végétatif et des rendements en graines et en huile. Le rendement moyen obtenu en 3eme année de production par l’écotype le plus productif (Panu : 473,1±3,6 kg de graines sèches ha-1) était près de 7 fois plus élevé que le rendement de l’écotype qui a produit le moins (Ilebo : 68,6±3,6 kg ha-1). Contrairement à ce qui était annoncé dans la littérature, le temps nécessaire pour l’entrée en pleine production de J. curcas en conditions tropicales humides est supérieur à 5 ans. Il n'est pas possible de déterminer sur base de nos résultats, le niveau exact de rendement qui sera obtenu quand les plantes entreront en pleine production. Quel que soit celui-ci, le coût très élevé de la main d’œuvre nécessaire à la collecte des graines de J. curcas et au désherbage limite fortement les perspectives de rentabilité de la culture pure dans la région de Kinshasa. Dans les zones enclavées du pays, où le coût de la main d’œuvre est moindre et où le prix du diesel est plus élevé, la production de J. curcas peut constituer l’une des solutions pour résoudre les problèmes d’accès à l’énergie. [less ▲]

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See detailDistributed control of electromechanical oscillations in very large-scale electric power systems
Wang, Da ULg

Doctoral thesis (2014)

Electromechanical oscillations threaten the secure operation of power systems and if not controlled efficiently can lead to generator outages, line tripping and even large-scale blackouts. Different ... [more ▼]

Electromechanical oscillations threaten the secure operation of power systems and if not controlled efficiently can lead to generator outages, line tripping and even large-scale blackouts. Different damping devices, like Power System Stabilizers (PSSs), Thyristor Controlled Series Compensators (TCSCs), and so on, are installed to damp these oscillations. This thesis proposes a trajectory-based supplementary control to improve damping effects of existing controllers, which treats damping control as a multi-step optimization control problem with discrete dynamics and costs. At each control time, it collects current system states, solves the optimal control problem and superimposes the calculated supplementary inputs on the outputs of existing damping controllers, in order to enhance the damping. These supplementary signals are continuously updated, which allows to adaptively adjust and coordinate a subset of existing damping controllers, and eventually all of them. Two kinds of methods, Model Predictive Control (MPC) and Reinforcement Learning (RL), are used to embody the proposed supplementary damping control. Firstly, a fully centralized MPC scheme is designed based on a linearized, discrete, complete state space model. Its performances are evaluated both in ideal conditions and considering realistic state estimation errors, and computation and communication delays. The effects of the number and type of available damping controllers are also studied. This scheme is further extended into a distributed scheme with the aim of making it more viable for very large-scale or multi-area systems. Different ways of decoupling and coordinating between subsystems are analyzed. Finally, a robust hierarchical multi-area MPC scheme is proposed, introducing a second layer of MPC based controllers at the level of individual power plants and transmission lines. Secondly, a tree-based batch mode RL algorithm is applied to carry on the proposed supplementary damping control. Using a set of dynamic and reward four-tuples, it constructs an approximation of the optimal $Q$-function over a given temporal horizon. The actions greediest with respect to the $Q$-function are applied as supplementary signals to existing damping controllers. The scheme is firstly tested on a single generator, and then on multiple generators. Different reward signals and damping levels are also considered. Finally, the combined control effects of MPC and RL are investigated. [less ▲]

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See detailAbondance et variabilité des méduses en Baie de Calvi (Corse)
Collignon, Amandine ULg

Doctoral thesis (2014)

L’importance et la variabilité temporelle des méduses calycophores et de la méduse schyphozoaire, Pelagia noctiluca en Baie de Calvi (Corse) ont été étudiées en utilisant une série temporelle planctonique ... [more ▼]

L’importance et la variabilité temporelle des méduses calycophores et de la méduse schyphozoaire, Pelagia noctiluca en Baie de Calvi (Corse) ont été étudiées en utilisant une série temporelle planctonique hebdomadaire de 2003 à 2013. Cette variabilité a été comparée à celles des variables biotiques et abiotiques grâce à la technique du calcul des anomalies saisonnières et interannuelles. La diversité des méduses siphonophores calycophores a été décrite et les critères taxonomiques permettant d’identifier les espèces dominantes (Chelophyes appendiculata, Lensia subtilis, Abylopsis tetragona et Muggiaea atlantica) et de leurs stades de développement ont été précisés. Le cycle de développement de Chelophyes appendiculata a été établi sur base de la variation saisonnière climatique des différents stades moyennée sur les 10 années. Cette espèce est rencontrée toute l’année et présente deux générations, par an. Ce cycle est en phase avec les périodes d’abondance du zooplancton et en particulier des copépodes. Il s’inscrit dans la séquence des événements planctoniques liés à stratification de la colone d’eau. La variation interannuelle se marque par la succession des différentes espèces dont l’abondance augmente sur une période de quatre ans environ. Ainsi au cours des 10 ans, Chelophyes est progressivement remplacé par Lensia. La corrélation entre la moyenne annuelle de l’abondance des eudoxies et celle de la température de surface est très significative et suggère le contrôle de la reproduction par la température. Une relation inverse de l’abondance des stades polygastriques et l’abondance du zooplancton suggère un contrôle de ces méduses sur ce dernier. La distribution spatiale des calycophores a été étudiée au large de la Corse en relation avec les différentes masses d’eau et structures hydrologiques associées au front Liguro-provençal. Les plus fortes abondances sont situées au niveau du plateau continental. Dans 90% des échantillons de surface de fortes abondances de microplastiques étaient associées au zooplancton et aux méduses en particulier. L’étude de la variabilité de la méduse Pelagia noctiluca en Baie de Calvi a confirmé que les invasions obéissent à un cycle pluriannuel indépendamment de la pollution. La distribution en essaims a été étudiée en relation avec les contraintes du milieu. [less ▲]

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See detailComputational homogenization of cellular materials capturing micro-buckling, macro-localization and size effects
Nguyen, Van Dung ULg

Doctoral thesis (2014)

The objective of this thesis is to develop an efficient multi-scale finite element framework to capture the macroscopic localization due to the micro-buckling of cell walls and the size effect phenomena ... [more ▼]

The objective of this thesis is to develop an efficient multi-scale finite element framework to capture the macroscopic localization due to the micro-buckling of cell walls and the size effect phenomena arising in structures made of cellular materials. Under the compression loading, the buckling phenomenon (so--called micro--buckling) of the slender components (cell walls, cell faces) of cellular solids can occur. Even if the tangent operator of the material of which the micro--structure is made, is still elliptic, the presence of the micro--buckling can lead to the loss of ellipticity of the resulting homogenized tangent operator. In that case, localization bands are formed and propagate in the macroscopic structure. Moreover, when considering a cellular structure whose dimensions are close to the cell size, the size effect phenomenon cannot be neglected since deformations are characterized by a strain gradient. On the one hand, a classical multi-scale computational homogenization scheme (so-called first-order scheme) looses accuracy with the apparition of the macroscopic localization or the high strain gradient arising in cellular materials because the underlying assumption of the local action principle, in which the stress state on a macroscopic material point depends only on the strain state at that point, is no--longer suitable. On the other hand, the second-order multi-scale computational homogenization scheme proposed by Kouznetsova exhibits a good ability to capture such phenomena. Thus this second--order scheme is improved in this thesis with the following novelties so that it can be used for cellular materials. First, at the microscopic scale, the periodic boundary condition is used because of its efficiency. As the meshes generated from cellular materials exhibit a large void part on the boundaries and are not conforming in general, the classical enforcement based on the matching nodes cannot be applied. A new method based on the polynomial interpolation without the requirement of the matching mesh condition on opposite boundaries of the representative volume element (RVE) is developed. Next, in order to solve the underlying macroscopic Mindlin strain gradient continuum of this second-order scheme by the displacement-based finite element framework, the presence of high order terms (related to the higher stress and strain) leads to many complications in the numerical treatment. Indeed, the resolution requires the continuities not only of the displacement field but also of its first derivatives. This work uses the discontinuous Galerkin (DG) method to weakly impose these continuities. This proposed second--order DG--based FE2 scheme appears to be easily integrated into conventional parallel finite element codes. Finally, the proposed second-order DG-based FE2 scheme is used to model cellular materials. As the instability phenomena are considered at both scales, the path following technique is adopted to solve both the macroscopic and microscopic problems. The micro--buckling leading to the macroscopic localization and the size effect phenomena can be captured within the proposed framework. [less ▲]

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See detailA framework for using decision-support tools at various spatial scales for the management of irrigated agriculture in semi-arid West-Africa
Wellens, Joost ULg

Doctoral thesis (2014)

The Kou watershed, situated in the Southwestern part of Burkina Faso, has succumbed since a couple of decades to a typical theater play of anarchistic water management. With its 1.800 km², this small ... [more ▼]

The Kou watershed, situated in the Southwestern part of Burkina Faso, has succumbed since a couple of decades to a typical theater play of anarchistic water management. With its 1.800 km², this small watershed includes the second largest city of Burkina Faso (Bobo-Dioulasso), a former state run irrigated rice scheme and several informal agricultural zones. Despite the abundance of water resources, most water users find themselves regularly faced with shortages due to an increase in population and low irrigation efficiencies. Local stakeholders are hence in need of easy to use and low-cost decision support tools for the monitoring and exploitation of the water resources at different spatial and user levels. A top-to-bottom string of adapted water management tools has successfully been installed to tackle the problems: from watershed (top) to field level (bottom), not to mention the 1200 ha irrigation scheme. Land use maps have been derived from satellite and aerial images. Combined with data from a network of hydrologic gauging stations, regional water use maps were established. Hot spots in inefficient water use could be geographically identified and more detailed actions undertaken. Scheme Information Management Information System (SIMIS) was put in place for the management of the regions irrigated rice scheme. A more equitable distribution for the ever diminishing available water resources could be elaborated. A public-private partnership was installed to guarantee its sustainability. Day to day water use on irrigated plots was monitored by soil humidity and crop canopy measurements. A simple field-crop-water balance model AquaCrop was calibrated and validated, and is used by extension workers to draft optimal irrigation charts. Each tool is applied independently, requiring only limited data; but their combined results contribute to an improved integrated water management. [less ▲]

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See detailL'utilisation de la spectrométrie (NIR) et l’imagerie hyperspectrale (NIR-HIS) proche infrarouge pour étudier la composition chimique et botanique de des fourrages
Dale, Laura-Monica ULg

Doctoral thesis (2014)

Forage quality or nutritive value is related to chemical composition, which can be determinated by laboratory methods. The NIR technique in comparison with classical methods is non-destructive, non ... [more ▼]

Forage quality or nutritive value is related to chemical composition, which can be determinated by laboratory methods. The NIR technique in comparison with classical methods is non-destructive, non-polluting, fast and relatively inexpensive per analysis. Investigations on nutritional quality of Carpathians Apuseni Mountains (Romania) grasslands are rarely performed with NIR technique. Therefore, the objective of the thesis was to develop non-destructive methods for evaluating the quality of feed originating from the Gârda area of the Carpathians Apuseni Mountains (Romania) potentially and to similar grassland arround the world. The first task was to study the potential of NIR spectroscopy for building a spectral database for forage quality based on a large collection of semi-natural grassland samples, using a ‘local’ calibration model built by the Walloon Agricultural Research Centre (CRA-W), in Belgium, to determine various parameters (e.g., protein, dry matter, ash, fibre, fat, aNDFom, ADF, lignin, digestibility, crude energy) from samples collected worldwide, outside Romania. The second task was to develop calibration models for an NIR-HSI system, which involved larger spectral data registration as an image. Until now, analyses to determine plant species were based on botanical composition evaluation, including visual observation, which is a subjective method involving identifying plants directly in the field. Distinguishing samples of pure grassland species can be time consuming, and it was therefore decided to build a spectral database of pure samples and then discriminate these samples into binary and ternary artificial sample mixtures. The main objective of these tasks was to identify the botanical families to which the samples belonged (Poaceae, Fabaceae and Other Botanical Families [OBF]). The focus was not on quantity monitoring, but rather on determining forage quality from stationary experiments in the grasslands. To conclude, this research has shown that it is possible to develop calibration models not only for quality assessment, but also for sample discrimination in dry powder samples. It was intended, that the mathematical models constructed and the database obtained, would be used for future research. [less ▲]

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See detailLa nozione di "partecipazione" nella Glossematica di Louis Hjelmslev
Cigana, Lorenzo ULg

Doctoral thesis (2014)

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See detailStudy of the multi-decadal evolution of the Black Sea hydrodynamics and biogeochemistry using mathematical modelling
Capet, Arthur ULg

Doctoral thesis (2014)

This thesis addresses the biogeochemical cycles in the Black Sea (BS) during the shifting environmental context that affected the BS during the last decades of the 20th century. The study is based on ... [more ▼]

This thesis addresses the biogeochemical cycles in the Black Sea (BS) during the shifting environmental context that affected the BS during the last decades of the 20th century. The study is based on sophisticated data analysis tools and on the development and implementation of a coupled 3D biogeochemical model on the BS domain. The long term variability of the BS hydrodynamical structure was first examined on the basis of in-situ profiles (1950-2012), satellite imagery (1985-2000) and 3D modelling (1960-2000). Profiles of temperature and salinity were used to derive vertical characteristics of the BS structure: the mixed layer depth and the cold content of the Cold Intermediate Layer. To untangle the spatial and temporal trends from this heterogeneous dataset, a general methodology was proposed and embedded in the data analysis software DIVA. The detrended climatologies and long-term time series provided by this approach were used to assess statistical relationships with local atmospheric conditions. Satellite data (sea surface temperature and altimetry) and model results were then analyzed to relate observable surface dynamics to internal hydrodynamic properties. The main multivariate modes of variability of the BS hydrodynamic structure were highlighted on the basis of Empirical Orthogonal Function analysis. Their temporal evolution was explained by the occurrences of specific atmospheric patterns, identified on the basis of neural algorithm analysis and related to the phases of well known teleconnection systems (i.e. the North Atlantic and East Asia/West Russia oscillations). To study the dynamics of eutrophication in the shallow Black Sea NorthWestern Shelf (BS-NWS), a benthic model component was developed that considers the environmental control on diagenetic processes and the bottom shear stress restriction on organic matter deposition. The model accurately reproduced the seasonal and spatial variability depicted by in-situ estimates of benthic nutrients and oxygen fluxes in the BS-NWS. Outputs were used to review the role of the benthic component in BS biogeochemical cycles. The multi-decadal simulations, enabled by the low computational requirements of the benthic-pelagic coupling approach, revealed an inertial component in the dynamics of eutrophication resulting from the accumulation of organic matter during the years of important nutrient loads. This refined resolution of the BS-NWS biogeochemistry allowed us to study the phenomenon of seasonal hypoxia, which is believed to have played a part in the sudden collapse of the fisheries stocks in the late 80s. An index H, combining the spatial and temporal extension of the seasonal hypoxic event, was proposed to quantify the annual intensity of hypoxia as a pressure on benthic communities. We have shown that hypoxia was first triggered in the late 70s by high nitrogen loads, and sustained by sedimentary organic matter accumulation after a rapid reduction of these loads in the 90s. After 2000, warmer summers again led to a increase of the H-index, by entraining hypoxic events of smaller spatial extension but increased duration. A practical relationship distinguishing the impacts of eutrophication and climatic drivers was proposed to assess the effect of their projected values on the future intensity of hypoxia. [less ▲]

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See detailÉtude de l’entomofaune au sein d’associations culturales comprenant le Safoutier (Dacryodes edulis) dans le Haut-Ogooué (Gabon).
Poligui, René Noël ULg

Doctoral thesis (2014)

Le safoutier Dacryodes edulis (Burseraceae) est un important arbre fruitier originaire du Golfe de Guinée. Ses fruits (safou) sont nutritionnels, beaucoup consommés et commercialisés sur les marchés ... [more ▼]

Le safoutier Dacryodes edulis (Burseraceae) est un important arbre fruitier originaire du Golfe de Guinée. Ses fruits (safou) sont nutritionnels, beaucoup consommés et commercialisés sur les marchés urbains d’Afrique centrale et sur les marchés africains d’Europe, générant des revenus substantiels aux producteurs et aux commerçants. Le safoutier est susceptible d’apporter des revenus considérables aux économies des pays d’Afrique centrale. Cependant, malgré cette importance alimentaire et économique, il existe très peu d’études sur le safoutier au Gabon, et ses ravageurs sont peu connus dans toute son aire de culture. La présente étude a donc été entreprise pendant les saisons de floraison et de fructification de cet arbre, d’Août à Décembre 2009 à 2011. Le principal objectif était d’évaluer l’entomofaune fréquentant le safoutier au sein des agroécosystèmes du Gabon. Des techniques complémentaires de surveillances entomologiques ont été utilisées, à savoir les pièges jaunes et les observations visuelles, en zones rurales et urbaines. L’étude révèle l’existence une typologie culturale constituée de jardins de case à dominance fruitière, et des jardins de cultures mixtes. Dans les deux systèmes culturaux, D. edulis est l’arbre fruitier majeur. Les abondances et la diversité entomologique ont été déterminées, et les ravageurs et insectes utiles les plus importants ont été identifiés suivant les associations culturales. L’exploitation des diagrammes de relations trophiques (food webs) a permis de caractériser les liens entre les espèces entomologiques et le type de cultures. Les abondances d’insectes sont plus élevées en milieu rural où D. edulis a une densité plus forte qu’en milieu urbain. La diversité d’insectes est similaire entre les deux milieux. L’intérêt et les caractéristiques phénologiques des ravageurs majeurs ont été décrits, et des mesures de lutte biologique ont été préconisées pour leur contrôle. Les ravageurs prédominants de l’agroécosystème rural sont Oligotrophus sp (Diptera: Cecidomyiidae), Pseudophacopteron serrifer Malenovsky (Phacopteronidae) et Selenothrips rubrocinctus Giard (Thysanopera: Thripidae), tandis que Pseudonoorda edulis Maes & Poligui (Lepidoptera: Crambidae), Bactrocera invadens Drew Tsuruta & White (Diptera: Tephritidae) et Physophoropterella bendroiti Poppius (Hemiptera: Miridae) sévissent prépondéremment dans l’agroécosystème urbain. Apis mellifera andansoni Latreille (Apidae) est la principale espèce pollinisatrice, en milieu urbain. Pseudonoorda edulis a été le ravageur le plus dommageable des fruits du safoutier, et des informations de base sur sa prévalence, sa biologie et ses caractéristiques morphométriques ont été fournies dans ce travail. Ces résultats apportent une meilleure connaissance des ravageurs et pollinisateurs de D. edulis au Gabon. Des études ultérieures devraient être conduites sur un environnement plus large de la culture, mais surtout cibler la recherche des mesures de contrôle biologique de P. edulis. [less ▲]

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See detailEtude du recyclage de l'eau résiduaire dans la flottation des minerais oxydés cuprocobaltifères du gisement de Luiswishi
Shengo Lutandula, Michel ULg

Doctoral thesis (2014)

The present work aims at improving practices in the management of wastewater from flotation of ores in the Katanga province and suggests the recycling considering its advantages on the environment ... [more ▼]

The present work aims at improving practices in the management of wastewater from flotation of ores in the Katanga province and suggests the recycling considering its advantages on the environment safeguarding, the sustainable management of hydric resources and the economy of flotation reagents standpoint. It focuses on the determination of the best process water-recycling rate in flotation of copper - cobalt oxidised ores from the Luiswishi deposit and on the explanation of phenomena implicated in the depression of malachite and heterogenite in the recycled water presence. The studied ores have been sulphidised (NaSH) prior to flotation with KAX using the process water recovered from the industrial effluents and a Lab scale replication of the New Concentrator in Kipushi (NCK) flow sheet to simulate the full-size plant operations. The following methodological approach has been adopted: • The lab flotation tests of the pulps originating from the NCK grinding circuit while varying the proportion of the recycled process water added to the feed water in view to determine the proportion which gives a concentrate grading at least 2% Co at the recovery of 80% and at least 7% Co at the recovery of 60% respectively at the rougher and cleaner stages; • The study of the effects from the recycled water chemical components on flotation of malachite and heterogenite through flotation of the studied ores in the presence of S2O32-, SO42-, HCO3-, Ca2+ and Mg2+ introduced in the feed water (demineralised water) through dissolution of their analytical graded-salts and based on the follow-up of the Cu-Co recovery and the roughing flotation concentrates mineralogical analysis by the polarised light microscopy, the X- rays diffraction and the scanning electron microscopy; • The study of the behaviour of malachite and heterogenite based firstly on electrochemical investigations of the pulp (pH, Eh, Es and DO), the leaching tests and sulphidisation of malachite and heterogenite with NaSH in presence of S2O32-, SO42- and HCO3. Secondly, based on thermodynamical calculations for the establishment of the Pourbaix diagrams of the systems Cu(Co-Cu) – Chemical species – Water at 25 °C and the Drift spectroscopic analysis (4000 à 400 cm-1) of malachite after sulphidisation with NaSH and agitation with KAX in the presence of S2O32-, SO42- and HCO3-. The obtained results have shown that the process water recycling is successful when 20% of the recycled water is added to the feed water since one obtains a concentrate grading 2% Co at the recovery of 80% at the rougher stage. However, considering the significant drops in the grade and the recovery of cobalt in the concentrate observed at the cleaner stage, a proportion of 10% has been suggested as optimal for the overall flotation circuit because 82% cobalt were recovered at rougher stage bringing at the cleaner stage a concentrate grading 9.5% Co at the recovery of 63%. Beyond 10%, the process water recycling has proved detrimental to flotation efficiency owing to the build-up of chemical species (S2O32-, SO42-, HCO3-, Ca2+, Mg2+ and Cl-) in the feed water, which becomes corrosive and scaling leading to depression of malachite and heterogenite. This depression results from an increase in the valuable minerals hydrophilicity boosted-up by their strong dissolution in water in the presence of S2O32-, SO42 and HCO3- leading to alterations in their surface properties and the exaggerated liberation of copper and cobalt ions in solution responsible for the overconsumption of NaSH and KAX. [less ▲]

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See detailVariabilité morphologique, génétique et chimique de Cananga odorata [Lam.] Hook.f. & Thoms. en vue de l'amélioration qualitative de la production de l'huile essentielle d'ylang-ylang dans les îles de l'Océan Indien
Benini, Céline ULg

Doctoral thesis (2014)

Summary: Cananga odorata (Lam.) Hook f. & Thomson forma genuina (Annonaceae) commonly called ylang-ylang is an essential oil tree used in the preparation of cosmetics. Despite this plant is an ... [more ▼]

Summary: Cananga odorata (Lam.) Hook f. & Thomson forma genuina (Annonaceae) commonly called ylang-ylang is an essential oil tree used in the preparation of cosmetics. Despite this plant is an indispensable source of incomes for the producing islands, and despite its essential oil is valued by the cosmetic industry, only few studies have been conducted. Ylang-ylang essential oil sector is dying and conservation and valorization strategies are urgently needed to preserve it. During this thesis, we tried to gather the necessary data to achieve this goal. We thus characterized the variability of ylang-ylang at morphological, genetic and chemical levels. This study revealed an important variability in the chemical composition of ylang-ylang essential oil in the study area. In order to suggest valorization and conservation strategies tailored to the current context, we needed to know the causes responsible for the chemical polymorphism. These causes are to be found probably in the environmental variability. Indeed, the genetic structure only revealed few consistencies with the chemical polymorphism. It would be though wiser to further investigate these two potential causes of the chemical variability of ylang-ylang as our study is pioneer in this field. On the basis of the data collected, we then proposed a market-oriented valorization of the genetic and chemical diversity (uniformity of the quality and the composition of ylang-ylang essential oils, raw material sources and quality labels). In terms of genetic and chemical conservation, we propose a conservation strategy mainly based on an on-farm conservation in plantation. We also propose integrated valorization strategies of the on-farm conservation (direct sales and tourism). [less ▲]

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See detailDetermination of the relationship between foam morphology and electrical conductivity of polymer/carbon nanotube nanocomposite foams
Tran, Minh Phuong ULg

Doctoral thesis (2014)

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is ... [more ▼]

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is very interesting in bone tissue engineering. Moreover, the incorporation of appropriate carbonaceous nanoparticles into polymeric foams contributes to the reinforcement of their mechanical performances but also renders them electrically conductive, consequently extending their potential interest in electromagnetic shielding (EMI) and electrostatic discharge (ESD) applications for instance. In this PhD thesis, we aim at designing various polymeric foams containing a conductive nanofiller (carbon nanotubes) and to identify the main morphological parameters (pore size, cell density, cell wall thickness,…) that affect and govern the final properties of the foams. In this work, the electrical conductivity of the foams is the main property investigated because it is governing their performances as materials for EMI absorbers, the main application targeted in this work. These important morphology/electrical conductivity relationships would indeed be very useful to guide the foam development towards the material with the best performances for the targeted applications. Two different foaming methods are used in this work: (i) the supercritical CO2 (scCO2) foaming technology and (ii) the freeze-drying process. The first technique enables to produce isotropic foams with spherical closed cells structures and the second one, oriented anisotropic foams with cylindrical open cells. The variation of the foaming parameters allows preparing foams with a large panel of morphologies required for the establishment of the structure/properties relationships. In parallel to this main objective, an improvement of the overall conductive performances of the nanocomposites foams is also investigated through the optimization of the foam morphology and the content in conductive nanofillers. [less ▲]

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See detailDe l'écologie d'un discours heuristique d'acculturation à l'algèbre linéaire
DUNIA MWATI, Adrien

Doctoral thesis (2014)

ABSTRACT : Our research examines the sustainability of an acculturation heuristic discourse to Linear Algebra, prototypical gradual development of this discipline in a dialectical process with elementary ... [more ▼]

ABSTRACT : Our research examines the sustainability of an acculturation heuristic discourse to Linear Algebra, prototypical gradual development of this discipline in a dialectical process with elementary geometry. Our theoretical frameworks are borrowed from mathematics Didactic : mainly, Theory of Didactic Situations by Brousseau and Anthropological Theory of Didactics by Chevallard. These theories have enabled us to problematize the studied issue and make it a teaching "phenomenon" by giving intelligibility to the observations in a way that they are interpreted in a falsifiable hypothesis ( in Popper's sense ) which may integrate them all . In this context, the strict meaning given by Lakatos to heuristic speech has been broadly extended in terms of fundamental situation and praxeologies “modeling” according to Job and Schneider. A rational reading of historical and epistemological development of linear algebra then allowed us to build a "reference epistemological model" not only allowing us to answer to the question: "what is it to do linear algebra ?", but also to legitimize the referent heuristic discourse that served us as “phénoménotechnique”. Considering that our study is well marked, we have experimented in "secondary" and "university" institutions a heuristic device based on some selected aspects of the referent heuristic discourse. The analysis of observable that empirical work has identified has led us to identify several factors that combine to determine the ecological fragility of this speech and are at different levels of scale didactic codetermination (by Chevallard) : - The institutional variation of the curriculum of secondary education part in relation to linear systems. Including an emphasis on a resolution systems contract at the expense of their discussion, with a focus placed on the substitution method ; little technological discourse on the principles of equivalence systems and no intelligibility in terms of beams ; little work on equations as constraints with an impact on the lack of connection between the solution space of a system and the number of "independent" constraints, and finally, no ecological niche for the study of systems due to fragmentation of knowledge involved in multiple chapters. - The constraints inherent in the process of didactic transposition in terms of depersonalization and “désyncrétisation” of the knowledge but also in terms of progress in teaching time or chronogenesis. - Constraints related to teaching : a teacher accommodation to a socio-constructivist paradigm which appears as disguised exposition (ostension) and some ineffective activities ; a university pedagogy marked by “applicationnisme”, protectionism and a timing organization that puts theory on a pedestal where it is no longer in question. - An allegiance to the "mathematical" institution that is manifested, for instance, by some emblematic gestures linked to the mathematic rigor and which do not have great functionality. - Finally, an influence of the work of mathematicians on the didactic transposition, in the era of modern mathematics, which still inspires today didactic way, impeding (or being an obstacle for) linear algebra construction in dialectic with the geometry. The selected scenario for the role of interpretive hypothesis articulating these factors questions, in turn, all our education system which is too inspired by deductive theories in their completed text application. [less ▲]

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See detailLa discipline scolaire "français" : du questionnement identitaire à la conscience disciplinaire. Panorama sur les zones avancées de la francophonie et gros plan sur le cas particulier de l'enseignement du français au secondaire supérieur en Fédération Wallonie-Bruxelles
Van Beveren, Julien ULg

Doctoral thesis (2014)

Après avoir envisagé l'introduction de l'approche par compétences et l'élargissement du corpus des supports d'apprentissage du cours de français comme deux des causes possibles de la crise identitaire que ... [more ▼]

Après avoir envisagé l'introduction de l'approche par compétences et l'élargissement du corpus des supports d'apprentissage du cours de français comme deux des causes possibles de la crise identitaire que nous semble traverser cette discipline scolaire, nous nous sommes livré à l'analyse d'un grand nombre de livraisons de la revue de l'Association internationale des chercheurs en didactique du français, afin de nous interroger sur la rareté des publications ayant trait à la discipline scolaire "français" dans son ensemble. Dans la troisième partie de notre thèse, nous nous sommes penché sur la notion de discipline scolaire et sur quelques syntagmes qui y sont liés, avant de nous focaliser sur l'enseignement-apprentissage du français, au secondaire supérieur, en Fédération Wallonie-Bruxelles. Ajoutons que c'est surtout selon la perspective du didacticien-formateur que nous avons analysé cet enseignement-apprentissage. [less ▲]

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See detailSpace-variant optical phase retarders in liquid crystal polymers and their applications
Piron, Pierre ULg

Doctoral thesis (2014)

During the last decade, extensive investigations were performed to achieve optical phase retarders with a space-variant orientation of their fast axis. These retarders present unique behaviors and they ... [more ▼]

During the last decade, extensive investigations were performed to achieve optical phase retarders with a space-variant orientation of their fast axis. These retarders present unique behaviors and they can be used for several applications such as polarization analysis, beam splitting, phase mask coronagraphy, optical tweezers … The present thesis is dedicated to the development of space-variant retarders made out of liquid crystal polymers recorded by polarization holography. The liquid crystals define the fast axis orientation of the retarder. Polarization holography is based on the superimposition of differently polarized beams to achieve the electric field required to properly align the liquid crystals without mechanical action. In the present work, we start with an introduction about the space-variant retarders, their characteristics and current recording methods, which usually require mechanical action. In the second chapter, polarization holography and several simple examples are presented as well as the liquid crystal polymers, their generic recording process and the first prototypes. In chapter three, the first application that we developed is exposed. It consists in a polarization analysis method based on a retarder characterized by a variation in one dimension of its fast axis orientation. The principle of the method, numerical simulations and the first results are exposed. Chapter four cares about the second application based on a separator of polarization state. The mathematical model and its application to shearography are exposed. In chapter five, another kind of retarders is introduced. These retarders are characterized by a rotation of their fast axis along the center of the retarder. Their properties, the recording systems and the first prototypes are detailed and analyzed. In the last chapter, the application of our retarder to coronagraphy is presented and their performances are computed for different configurations based on experimental constrains. Finally, we conclude with the improvements of our applications and future uses of these retarders. [less ▲]

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See detailContribution à l’amélioration de l’épidémiosurveillance des maladies animales en Afrique francophone de l’Ouest et du Centre
Ouagal, Mahamat ULg

Doctoral thesis (2014)

Livestock is an important source of income in most developing countries. In Africa, it often makes up 10% to 20% of the gross national product at level. One of the major constraints to the development of ... [more ▼]

Livestock is an important source of income in most developing countries. In Africa, it often makes up 10% to 20% of the gross national product at level. One of the major constraints to the development of this sector is animal diseases, which sometimes generate significant economic losses with social consequences that are often very burdensome for farmers. They restrict trade between countries. Reducing the impact of these constraints necessarily involves the prevention and the control of diseases. For this purpose, an adequate knowledge of the epidemiology of the diseases is a prerequisite to define a strategy for their prevention and/or the design of appropriate monitoring measures. One of the essential tools of production remains the epidemiological information network for the surveillance of animal diseases. It is also a tool for decision in international trade involving livestock products. For this purpose, its effectiveness is a guarantee for its credibility. An effective network system must be well organized, meet scientific standards and satisfy the efficiency characteristics which are sensitivity, specificity, acceptability, responsiveness and cost. In west and central Africa, epidemiological surveillance networks of animal diseases are mostly created in the 1990s through the Pan African Program for the Control of Epizootics. A 2004 assessment carried out by this program revealed that these networks are at different stages and found weaknesses in their efficiency. To contribute to the improvement of these systems, an analysis of some performance parameters of these networks has been conducted and suggestions for improvement were made. To achieve this overall objective, the following specific objectives were listed: (i) analyze the technical and functional organization of epidemiological surveillance networks in West and Central Africa; (ii) compare the effectiveness of active surveillance and passive surveillance, the two main monitoring methods used by the networks in West and Central Africa using the case study of the epidemiological surveillance network, in Chad, namely REPIMAT; (iii) assess the sensitivity of an epidemiological surveillance network from an approach based on prevalence of a disease such as Foot and Mouth Disease; (iv) develop performance indicators for regular monitoring of the epidemiological surveillance network for animal diseases in West and Central Africa, again by taking the case of REPIMAT; and finally, (v) estimate the cost incurred by an epidemiological surveillance network in West and Central Africa, for example the REPIMAT. Each of these specific objectives leads to a specific study of which results are presented below: Organization of epidemiological surveillance networks in West and Central Africa The survey on technical and institutional organizations networks in west and central Africa was organised on the basis of a written questionnaire. It involved nine networks of which five were in West Africa (Senegal, Burkina Faso, Ivory Coast, Togo, Guinea) and four in Central Africa (Cameroon, Central African Republic, Democratic Republic of Congo and Chad). The results of this survey showed that the oldest epidemiological surveillance network is that of Chad, REPIMAT. There are more similarities than differences between these networks. In general, network monitoring of animal diseases in west and central Africa are technically and institutionally well formalized. The establishment and operation of the networks surveyed are mainly financed by foreign aid. In general, these are epidemiological surveillance networks that monitor several diseases. All countries surveyed have a central national laboratory for the analysis of samples collected. However, only four countries (Cameroon, Côte d'Ivoire, Guinea and Senegal) can make a diagnosis of all diseases selected for monitoring. The laboratories are considered as partners with surveillance networks in most of the countries surveyed. All networks use the PID/ARIS for data management. In addition to the latter, countries such as Guinea, DRC, Senegal and Chad use a national database developed with Access®. On average, 26% of veterinary stations on the total networks surveyed are involved in the monitoring. This proportion varies from 7% to 91%. However, insufficient diagnostic capacity of laboratories and inadequate operational steering committees are the two main weaknesses of the networks concerned with this survey. Comparison between active and passive surveillance within the network of epidemiological surveillance of animal diseases in Chad The comparison between active and passive surveillance involved 106 REPIMAT surveillance stations randomly divided into 52 active surveillance stations and 54 passive surveillance stations. Vaccination status of nine diseases and their respective prevalence levels are monitored by the network. A work plan was developed for each station. The stations of active surveillance make monthly visits to four herds (villages) to look for monitored diseases and also organise four information meetings with farmers how to react in case of suspicion of the monitored diseases. Passive surveillance stations only organise, monthly, four information meetings with farmers. Suspicions in each station are recorded on a specific form developed for each disease. The agent mentions if the suspicion is performed following a breeder call, a visit from herds or a sensitization meeting. Monitoring lasted 24 months. The results of this study showed that regardless of the type of surveillance, diseases monitored with the exception of rare diseases (Rinderpest, and Rift Valley fever) are reported by the monitoring agents. However, we note that the number of calls recorded following suspicions of farmers (41%) was significantly higher (p <0.05) than suspicions made during visits to herds (30%) or in meetings (29%). For moderately prevalent diseases, the suspicions are mainly calls farmers (77%) and regardless of the type of monitoring (73% for active surveillance and 84% for passive surveillance). On the other hand, for FMD, a disease with high prevalence, 37% of suspicions are recorded by visiting farms. Overall, no significant difference was observed between the types of surveillance because of a low rate of disease onset during sensitization meetings by the active surveillance stations. Passive surveillance stimulated by awareness meetings appears to be a mode for surveillance in the conditions of Chad and cheaper. However, for rare diseases, the specific methods of active surveillance (such as, for example, sentinel flocks) seems preferable. Evaluation of the sensitivity of the animal disease epidemiological surveillance network for Foot and Mouth Disease in Chad Evaluation of the sensitivity of the animal disease epidemiological surveillance network for Foot and Mouth Disease in Chad The study on the network sensitivity was carried out in REPIMAT by taking the surveillance of FMD as an example. FMD is the disease most frequently suspected by REPIMAT. However, the reporting of cases is limited to clinical suspicion. The samples for the purpose of laboratory diagnostic for confirmation of these suspicions are not made. In order to assess the sensitivity of REPIMAT for this disease, a serological survey was conducted in eight of the nine regional delegations with the highest cattle population of the country. The samples were analyzed by the National Reference Laboratory for FMD in Brescia (Italy) with the support of the European Commission action against FMD. The 3ABC and SP-ELISA tests were used for the detection of antibodies and the serotype of the virus. The number of FMD suspicions reported within the network was compared with the seroprevalence. Epidemiological information on the disease, including the circulating serotypes in Chad, was also provided. A total of 796 cattle sera were collected. The seroprevalence rate at individual level was 35.6% (95% CI: 32.2 to 39.0) and that at the herd level was 61.9% (95% CI: 51.9 to 71.2). A strong correlation was observed between the estimated prevalence and number of clinical suspicions reported within REPIMAT. The disease is present in all livestock regional delegations surveyed with a high prevalence in the delegations located in the south, the wettest area, and where cross-border movements are the most important. Serotypes A, O, SAT1and SAT2 were identified. Development of operating performance indicators of Chad epidemiological surveillance network for animal diseases: REPIMAT The maintenance and effectiveness of a disease monitoring system requires regular evaluation to identify timely deficiencies that may occur. For this purpose, the performance indicators are essential tools. One approach for developing performance indicators as well as their application in the operation of 43 monitoring stations REPIMAT was carried out. An analysis of the objectives and operation mechanism of REPIMAT allowed retaining three main components, namely the field workers, the animation cell and the laboratory. The activities of each of these components were listed. The analysis of the outcomes of these activities resulted in the development of the performance indicators that can be used in the operation of REPIMAT. The application of these indicators has highlighted the weaknesses of each component. Estimated cost of a network for animal diseases epidemiological surveillance in Central Africa: the case of Chad network In sub-Saharan Africa, most of the networks for epidemiological surveillance of animal diseases were temporarily financed by external aid. The sustainability of such decision support tools should have been insured by national public funds. The objective of this study was to estimate the costs involved in running an animal disease epidemiological surveillance network by taking the example of such network in Chad (REPIMAT) and its weight in the state budget. These costs were then compared to those of other epidemiological surveillance in West Africa networks. The results of this study showed that the total annual operating and implementing cost of REPIMAT is estimated at € 666 349 (437 096 291 FCFA) for the entire system comprising 106 monitoring stations constituting the local level, 26 livestock sectors, nine regional livestock delegations representing the intermediate level and an animation cell constituting the central level. This cost represents only 3% (2% of fixed costs and 1% of variable costs) of the budget allocated by the Chadian Ministry of Livestock. Fixed costs (72%) weighed more than variable costs (28%) regardless of the levels of intervention. This estimate is similar to the estimated costs of epidemiological surveillance networks in Benin, Ghana, Mauritania and Senegal. Considering only the variable costs (operation), the annual cost of operating a surveillance station, the most important entity in the system was only 932 € or 611 352 FCFA. The surveillance cost is mainly related at the local level (surveillance stations) and intermediate level (livestock sectors and regional livestock delegations) to the cost involved in health surveillance as well as the equipment it requires. This thesis allowed to analyze some parameters of effectiveness of a surveillance network for animal diseases including general organization, type of surveillance, sensitivity, cost and to develop a tool for continuous monitoring of operating a network. It is difficult to meet all the efficiency criteria of an animal disease surveillance network, however, the few parameters studied which are interrelated will help if they are used properly to improve the efficiency of an epidemiological surveillance system of animal diseases in sub-Saharan Africa. [less ▲]

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See detailMathematical modeling od the mitral valve. From local to global hemodynamics
Paeme, Sabine ULg

Doctoral thesis (2014)

Mitral valve dysfunction is a relatively common heart disease which typically requires mechanical valve replacement, with consequent high social and economic costs. More specifically, ischemic mitral ... [more ▼]

Mitral valve dysfunction is a relatively common heart disease which typically requires mechanical valve replacement, with consequent high social and economic costs. More specifically, ischemic mitral insufficiency following myocardial infarction has a dynamic behavior that can lead to failure in its detection in certain patients, creating a situation with increased risk of morbidity and mortality. Improving the tracking and the control of valvular pathologies is therefore crucial, as it offers significant opportunities to improve care, costs and prognosis for patients with this disease. To study heart and cardiac valve dysfunction, cardiologists need information about detailed pressure and flow dynamics around and through the valves, atria and ventricles. However, non-invasive information about pressure is currently limited to indices at specific times and invasive catheterization data, which is more traumatic for the patient, is not usually routinely available. One alternative to this involves mathematical modeling of the cardiovascular system which offers a non-invasive and inexpensive way of studying cardiac and circulatory dynamics. This is particularly beneficial where detailed, continuous measurements may not be practicable. This study consisted of the development of a multi-scale closed-loop model of the cardiovascular system that accounted for progressive mitral valve aperture area over the entire cardiac cycle. This multi-scale model, which included detailed mitral valve and left atrium models, was tested over a range of physiological situations and clinical data. The goal was to validate the model’s ability to reproduce clinically measured physiological and pathophysiological behavior in a manner that would enable a model to be made patient-specific using available data. The resulting model was designed to be made patient-specific, and thus capture and reproduce the patient’s unique hemodynamic state on both global and local scales. In particular, it was shown to provide significant information about the patient’s mitral valve dynamics and the detailed flow dynamics and pressure around it. These data are not currently available without extensive, invasive measurements, and this therefore represents a significant step forward in model-based sensing and diagnosis. It is hoped that the model and methods developed in this study will be a powerful tool in assisting medical teams in investigating, tracking, diagnosing and controlling the cardiovascular system. More specifically, the mitral valve, as well as other similar valves, could be directly monitored to improve the diagnosis, costs and prognosis of valvular dysfunction. Furthermore, the overall results justify detailed in vivo animal experiments to thoroughly validate these models and methods in advance of clinical trials. [less ▲]

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See detailProtein Structural Annotation: Multi-Task Learning and Feature Selection
Becker, Julien ULg

Doctoral thesis (2014)

Experimentally determining the three-dimensional structure of a protein is a slow and expensive process. Nowadays, supervised machine learning techniques are widely used to predict protein structures, and ... [more ▼]

Experimentally determining the three-dimensional structure of a protein is a slow and expensive process. Nowadays, supervised machine learning techniques are widely used to predict protein structures, and in particular to predict surrogate annotations, which are much less complex than 3D structures. This dissertation presents, on the one hand, methodological contributions for learning multiple tasks simultaneously and for selecting relevant feature representations, and on the other hand, biological contributions issued from the application of these techniques on several protein annotation problems. Our first methodological contribution introduces a multi-task formulation for learning various protein structural annotation tasks. Unlike the traditional methods proposed in the bioinformatics literature, which mostly treated these tasks independently, our framework exploits the natural idea that multiple related prediction tasks should be designed simultaneously. Our empirical experiments on a set of five sequence labeling tasks clearly highlight the benefit of our multi-task approach against single-task approaches in terms of correctly predicted labels. Our second methodological contribution focuses on the best way to identify a minimal subset of feature functions, {\em i.e.}, functions that encode properties of complex objects, such as sequences or graphs, into appropriate forms (typically, vectors of features) for learning algorithms. Our empirical experiments on disulfide connectivity pattern prediction and disordered regions prediction show that using carefully selected feature functions combined with ensembles of extremely randomized trees lead to very accurate models. Our biological contributions are mainly issued from the results obtained by the application of our feature function selection algorithm on the problems of predicting disulfide connectivity patterns and of predicting disordered regions. In both cases, our approach identified a relevant representation of the data that should play a role in the prediction of disulfide bonds (respectively, disordered regions) and, consequently, in protein structure-function relationships. For example, the major biological contribution made by our method is the discovery of a novel feature function, which has - to our best knowledge - never been highlighted in the context of predicting disordered regions. These representations were carefully assessed against several baselines such as the 10th Critical Assessment of Techniques for Protein Structure Prediction (CASP) competition. [less ▲]

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See detailNanobodies as tools to investigate the mechanism of aggregation of chimeric proteins made by the insertion of polyglutamine stretches into the beta-lactamase BlaP
Pain, Coralie ULg

Doctoral thesis (2014)

Among the neurodegenerative amyloidoses, ten disorders, referred to as polyglutamine (polyQ) diseases and including Huntington's disease and several spinocerebellar ataxias, are associated with ten ... [more ▼]

Among the neurodegenerative amyloidoses, ten disorders, referred to as polyglutamine (polyQ) diseases and including Huntington's disease and several spinocerebellar ataxias, are associated with ten proteins within which a polyQ tract is expanded above a threshold of typically 35-45 glutamine residues. Such expanded polyQ tracts lead to the aggregation of the host protein into amyloid fibrils that accumulate in the nucleus of some populations of neurons; these aggregates or some of their precursors are thought to contribute to neuronal death. So far, no preventive or curative treatment exists for these devastating pathologies. While the expansion of the polyQ tract above the threshold is the determinant factor for aggregation, recent studies suggest that non-polyQ regions of these proteins can play a significant role, either preventative or facilitative, in the aggregation process. The general principles governing the complex interplay between the role of the expanded polyQ tract and the role of the non-polyQ regions in the aggregation process are not well understood yet. In order to develop therapeutic strategies, it is important to better understand this complex interplay. To contribute to this aim, we have engineered chimeric proteins via the insertion of polyQ repeats of various lengths (23, 30, 55 and 79Q) into two sites (197 and 216) of the BlaP beta-lactamase from Bacillus licheniformis 749/C. The properties of these chimeric proteins recapitulate the characteristic features of the disease-associated polyQ proteins, i.e. (i) there is a minimum number of inserted glutamines (threshold) required to trigger the aggregation of the chimeras into amyloid fibrils, and (ii) above the threshold, the longer the polyQ tract, the faster the aggregation. Interestingly, for the same polyQ length, the chimeras with insertions in position 216 have an increased propensity to form amyloid fibrils compared to their counterparts with insertions in position 197. These findings highlight the strong influence of the overall protein context on aggregation triggered by expanded polyQ tracts. This thesis addresses the use of the variable domains of camelid heavy-chain antibodies, referred to as nanobodies or VHHs, as structural and mechanistic probes to better understand the different aggregating properties of the two sets of BlaP-polyQ chimeras (197 and 216). We have also performed limited proteolysis experiments and transglutaminase-mediated reactions on the monomeric form of the BlaP-polyQ chimeras to further investigate the effects of the polyQ insertions on the structure and dynamics of the BlaP moiety, as well as the structure of the polyQ tract itself. From the blood of a llama immunised with BlaP197(Gln)55, we isolated more than 60 VHHs specific to the BlaP-polyQ chimeras. Twenty eight of them were produced, purified and characterised. These VHHs were found to be all specific to the BlaP moiety and could be classified into four different groups recognising distinct epitopes on the surface of BlaP. One representative VHH of each group (i.e. cAb-A3S, cAb-H7S, cAb-F11N and cAb-G10S) was selected as probe to investigate the mechanism of aggregation of the BlaP-polyQ chimeras. The epitope of three of them was determined by X-ray diffraction and/or by NMR spectroscopy. Although they recognise distinct epitopes and exhibit different affinities for BlaP, the binding of the four VHHs significantly slows down the aggregation of all the BlaP-polyQ chimeras investigated (i.e. BlaP197(Gln)55, BlaP197(Gln)79 and BlaP216(Gln)79). The extent of inhibition depends however on the chimera and on the experimental conditions. We show that the inhibition of the aggregation of BlaP197(Gln)55 and BlaP197(Gln)79 upon binding of the four VHHs is correlated with the stabilisation of their native state. In the case of BlaP216(Gln)79, the extent of inhibition could not be only correlated to the stabilisation of its native state; the location of the epitope of the VHH is instead also determinant. This observation demonstrates that the lower thermodynamic stability of BlaP216(Gln)79 is not the unique factor responsible for its increased aggregation propensity. It also further highlights the complexity of the aggregation mechanism of polyQ proteins and the strong influence of the non-polyQ regions on the amyloid fibril formation triggered by the expanded polyQ tract. All together our results suggest that antibodies or antibody fragments raised against the non-polyQ regions of polyQ proteins associated with diseases could constitute a relevant therapeutic strategy. They also further demonstrate the power of nanobodies as probes to get a deeper knowledge of the underlying mechanisms of amyloid fibril formation. The preliminary limited proteolysis and transglutamination experiments obtained suggest that the polyQ tracts are all flexible, except that of 23 glutamines inserted in position 197 of BlaP, which seems to be more rigid than the others. The results obtained confirm that, globally, the structure of BlaP is not significantly modified by the insertions while the 216 chimeras seem more dynamic than the 197 chimeras. [less ▲]

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See detailContribution à l'étude de la réponse immune au cours d'une infection à Microsporum canis et établissement d'un modèle murin de dermatophytose
Cambier, Ludivine ULg

Doctoral thesis (2014)

Les dermatophytoses (ou « teignes ») sont des mycoses cutanées superficielles provoquées par des champignons filamenteux, appelés dermatophytes, affectant les animaux et l’homme. Microsporum canis est un ... [more ▼]

Les dermatophytoses (ou « teignes ») sont des mycoses cutanées superficielles provoquées par des champignons filamenteux, appelés dermatophytes, affectant les animaux et l’homme. Microsporum canis est un dermatophyte zoophile dont l’hôte naturel est le chat. Il touche principalement les carnivores domestiques et est un agent fréquent de zoonose. Les dermatophytes envahissant les structures kératinisées de l’épiderme, de nombreuses études ont porté sur la caractérisation des protéases sécrétées comme facteurs de virulence potentiels. Cependant, peu de recherches ont été consacrées aux mécanismes impliqués dans la mise en place de la réponse immune anti-dermatophytes. Il est couramment admis que la réponse immune protectrice lors d’une dermatophytose est une réponse à médiation cellulaire impliquant les lymphocytes de type Th1 et caractérisée par une réaction cutanée d’hypersensibilité de type retardé (Delayed Type Hypersentivity, DTH). Un constituant sécrété de M. canis correspondant au surnageant de culture du champignon cultivé sur milieu de Sabouraud liquide, appelé surnageant non induit (SNI), provoque des DTH chez le cobaye immunisé après une primo-infection, ce qui suggère que le SNI contient des antigènes potentiellement intéressants pour le développement d’un vaccin. Le cobaye est le modèle animal le plus utilisé pour étudier l’immunologie des dermatophytoses. Cependant, la quasi absence d’outils génétiques et immunologiques dans cette espèce ne permet pas d’étudier la réponse immune induite lors de dermatophytoses de manière satisfaisante. La mise au point d’un modèle murin de dermatophytose permettrait de pallier tous ces inconvénients. Au cours d’une dermatophytose à M. canis, les premières cellules rencontrées par le champignon lors de l’infection sont les kératinocytes qui, suite à l’activation par des composants fongiques, peuvent attirer les polymorphonucléaires neutrophiles (PMN) sur le site d’infection. Ces leucocytes sont, avec les macrophages, responsables in fine de l’élimination du dermatophyte. Cependant, le rôle des PMN dans les mécanismes liés à l’établissement de l’immunité anti-dermatophytes demeure inconnu. L’objectif général de ce travail était de contribuer à l’étude de la réponse immune au cours d’une dermatophytose à M. canis et de mettre au point un nouveau modèle animal de dermatophytose. Pour l’atteindre, trois études ont été réalisées : (1) l’évaluation du rôle des PMN félins dans la mise en place d’une réponse immune protectrice au cours d’une dermatophytose à M. canis, (2) l’évaluation des propriétés protectrices du SNI de M. canis dans un essai vaccinal en utilisant le cobaye comme modèle expérimental et (3) la mise au point d’un modèle murin de dermatophytose pour l’étude de l’immunité anti-dermatophytes. Résumé 2 Les résultats obtenus dans la première étude montrent que les PMN félins produisent des cytokines pro-inflammatoires telles le tumor necrosis factor (TNF)-α, l’interleukin (IL)-1β et l’IL-8 lorsqu’ils sont stimulés par les arthrospores vivantes du champignon ainsi que par des constituants structuraux, représentés par des arthrospores tuées par la chaleur, et sécrétés comme le SNI. De plus, après stimulation pendant 2 ou 4 heures par les arthrospores vivantes et tuées ainsi que par les protéases sécrétées Sub3 et Sub6, disponibles sous forme recombinante dans notre laboratoire, les taux d’ARNm du toll like receptor (TLR)-2 et du TLR-4 étaient augmentés dans les PMN. Ces résultats suggèrent que les PMN félins jouent un rôle dans l’établissement de la réponse immune anti-M. canis en produisant des cytokines pro-inflammatoires et que les mécanismes responsables de cette activation feraient intervenir les récepteurs TLR-2 et TLR-4. Dans la deuxième étude, les résultats indiquent que l’adjuvant monophosphoryl lipid-A (MPLA), dérivé non toxique du lipopolysaccharide et agoniste du TLR-4 a, à lui seul, un effet protecteur partiel chez les cobayes soumis à une épreuve d’infection par M. canis. En effet, les symptômes cutanés observés chez les cobayes ayant préalablement reçu l’adjuvant, étaient moins importants que ceux développés par les cobayes infectés n’ayant pas reçu l’adjuvant. En revanche, le SNI ne semble pas protéger les cobayes d’une infection expérimentale dans cet essai vaccinal. Les résultats obtenus dans la troisième étude démontrent que notre modèle murin de dermatophytose est valide et reproductible, en utilisant Arthroderma benhamiae et Arthroderma vanbreuseghemii. Ce n’est pas le cas avec M. canis. En effet, 100 % et 80 % des souris infectées respectivement par A. vanbreuseghemii et A. benhamiae ont développé des symptômes cutanés typiques de dermatophytose, à savoir de l’érythème, des squames, des croûtes et de l’alopécie alors que seulement 40 % des souris infectées par M. canis ont développé des signes cliniques, par ailleurs très discrets. Le recrutement important de PMN dans la peau des souris infectées par A. benhamiae et A. vanbreuseghemii et le profil cytokinique (transforming growth factor (TGF)-β, l’IL-1β, l’IL-6 et l’IL-22) généré par l’infection suggèrent l’implication de la voie Th17 dans la mise en place de la réponse immune anti-dermatophytes. En conclusion, l’ensemble de ce travail a contribué à élargir nos connaissances sur la réponse immune au cours d’une dermatophytose à M. canis. De plus, un nouveau modèle murin de dermatophytose à A. benhamiae et A. vanbreuseghemii a été mis au point et est approprié pour l’étude de la réponse immune anti-dermatophytes. [less ▲]

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See detailContribution à la compréhension de l'immunopathogénie de l'aspergillose nasosinusale chez le chien
Vanherberghen, Morgane ULg

Doctoral thesis (2014)

Sinonasal aspergillosis is a sever fungal rhinosinusitis mainly affecting large breed dogs in their mid ages. Its most common causal agent is A. fumigatus, a fungus that is largely spread in the ... [more ▼]

Sinonasal aspergillosis is a sever fungal rhinosinusitis mainly affecting large breed dogs in their mid ages. Its most common causal agent is A. fumigatus, a fungus that is largely spread in the atmosphere. As of today, the diagnostic and treatment for this disease remain a challenge for the practicing veterinary doctor. Very little data is available to explain why such a ubiquitous fungus induces a sever rhinosinusitis in otherwise healthy dogs, while other dogs do not present any sign of fungal infection. The authors of a study analysing the expression of mRNA encoding for certain cytokines and chimiokines in the nasal mucosa of SNA affected dogs, propose the assumption that dogs develop a protective immunity (Th1) against A. fumigatus, but that it could be blocked by an excessively intense regulating immunity (massive production of IL-10). Indeed, it is commonly described that in humans affected by invasive aspergillosis, as well as in mice-based models, the production of immunoregulating cytokines (IL-10) should be considered as a sign of the escalation of the sickness and an absence of its remission. The objective of this thesis was to investigate the adaptive immunity reaction of SNA affected dogs based on the assumption that sick subjects develop a protective immunity that is antagonised by a disproportional regulating immunity. Three axes of analysis have been considered to answer this objective. The first looked into the difference of expression and/or production of cytokines and transcriptor factors prototypics of the different adaptative and regulatory immunological paths: Th1 (IFN-γ and Tbet) – Th2 (IL-4 and GATA3) – Th17 (IL-17A and RORc) and Treg (IL-10 and FoxP3) in PBMC of affected and healthy dogs after A. fumigatus stimulation. Secondly, an analysis of genes by microarray has been carried on nasal mucosa biopsies of affected and healthy dogs. Thirdly, the promotor zone of the gene encoding IL-10 in dogs has been analysed by sequencing. This study has been done within three cohortes of dogs: Rottweiler-Labrador and Golden containing affected and healthy dogs. The objective was to investigate, as it is the case in human medicine, the possibility of a genetic modification as a factor susceptible of leading to SNA development. The results of the first study revealed that: (1) the PBMC of half the controls dogs and every affected dogs expressed a relevant overexpression of IFN-γ. This increase was significantly more important within PBMC of affected dogs. The analysis of IFN-γ production in culture supernatants was in accordance with these last observations. A significant increase in the expression of mRNA coding for Tbet was also observed in half of the PBMC of affected dogs. (2) a significant increase in expression of mRNA encoding IL-4 was observed in the PBMC of most of the affected and healthy dogs. This increase was significantly higher in the PBMC of affected dogs than in the healthy dogs. (3) the PBMC of most control and affected dogs also revealed an increase in expression of mRNA encoding IL-17A. This increase was statistically more important in the PBMC of affected dogs than in the healthy dogs. (4) a relevant decrease in mRNA expression encoding IL-10 was observed in the PBMC of more than half of the affected dogs. The expression of the mRNA encoding IL-10 was significantly smaller in the PBMC of affected dogs than in the healthy dogs. The microarray analysis showed that: (1) amongst the 49 overexpressed biological groups, 13 were associated to the immunological or inflammatory process; (2) the nasal mucosa of affected dogs presented an increase in the expression of genes encoding for molecules involved directly (IFN-γ and STAT4) and indirectly (IL-16, CCL3, CCL4, and CXCL10) in the development of protective Th1 immunity, as well as molecules involved in the regulatory branch of the immune response (IL-16 and Ikaros). The sequencing analysis of the promotor region of the gene encoding IL-10 revealed the presence of polymorphisms. Three polymorphisms were observed more frequently in clones belonging to the three studied cohorts, excepted for the clones belonging to SNA affected Rottweiler. The polymorphisms observed in dogs were not similar to those described in humans. The first study showed an increase in the expression of mRNa encoding IFN-γ - Tbet – IL-4 and IL-17A in most of the PBMC of the affected dogs, and a decrease in the expression of IL-10 in comparison with the PBMC of healthy dogs. Similar results were observed in mice repeatedly affected by A. fumigatus. The suggested hypothesis was that an intense Th17 immunity resulted in a massive inflammatory reaction leading to a favourable environment were A. fumigatus was able to proliferate as hyphae. In return, hyphae would lead to the development of a non-protective Th2 immunity. It is tempting to suggest that the same hypothesis could be made for dogs affected by SNA. In order to reinforce this hypothesis, we should compare the expression of the different molecules involved in the Th17 immunity inside the nasal mucosa of affected and healthy dogs. Additionally, we should be running a kinetic study based on the expression of prototypical cytokines in parallel with the analysis of the production of these cytokines in culture supernatants. Ideally these studies should use DC and lymphocytes isolated from the nasal mucosa of affected and healthy dogs. In conclusion, an new hypothesis could be formulated: the possibility that not the overstimulation of the regulatory branch of the immunity response but an overstimulation of the Th17 branch of the immune response could be the cornerstone of the incapacity of dogs to clear from their SNA. The results of the microarray study were partially in accordance to the starting hypothesis. Indeed, the results showed an overexpression of genes involved in in the development of the protective Th1 (IFN-γ, STAT4, IL-16, CCL3, CCL4, and CXCL10) as well as genes involved in the regulatory path of the adaptive immunity (IL-16 and Ikaros). But the results of this study did not show an increase in IL-10. No conclusion could be drawn from these results; indeed, they were only the reflection of a fixed image at a given moment and we cannot consider qPCR results as the exact replica of the production of cytokines in the microenvironment. Nevertheless this study pointed out new possible areas of research. The results obtained after the sequencing of the promotor zone of the gene encoding IL-10 did not show any clear difference between affected and healthy dogs. However, this study was undertaken with a very limited number of dogs. In order to further assess the possibility of a genetic modification as the cornerstone of the development of SNA, more dogs should be analysed and the sequencing analysis should be run in parallel with an ELISA analysis. [less ▲]

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See detailComplémentation précoce en colostrum de vache Azawak chez la chèvre rousse de Maradi au Niger: effets sur les performances de croissance et de reproduction, et sur la survie au cours de la première année de vie.
Abdou, Harouna ULg

Doctoral thesis (2014)

L’élevage  des  petits  ruminants  représente  au  Niger,  la  ressource  principale  pour  plus  de  6  millions  de   paysans pauvres, vivant avec moins de 1 dollar US par jour. C'est un trésor ... [more ▼]

L’élevage  des  petits  ruminants  représente  au  Niger,  la  ressource  principale  pour  plus  de  6  millions  de   paysans pauvres, vivant avec moins de 1 dollar US par jour. C'est un trésor important qui contribue à la renommée des familles. Selon le recensement général  de  l’agriculture  et  de  l’élevage  (2007),  le   cheptel Nigérien se chiffre à 31 millions toutes espèces confondues dont 11 millions de caprins (36,21 %)  et  9  millions  d’ovins  (30  %). Bien  qu'il  occupe  une  place  de  choix,  l’élevage  des  petits  ruminants  reste confronté à des contraintes dont les principales sont: les sécheresses chroniques et répétitives ayant pour conséquence un déficit alimentaire constant, la pression démographique entrainant une concurrence entre les cultures et les animaux   pour   l’occupation de la terre et enfin les pathologies récurrentes (parasitoses gastro- intestinales, affections digestives) accompagnées le plus souvent par des diarrhées. Par ailleurs, la naissance et le sevrage sont deux périodes critiques pour les jeunes animaux. Si à la naissance, le système immunitaire reste en chantier et par conséquent déficient, au sevrage c'est le changement alimentaire qui peut handicaper la croissance des jeunes. Malheureusement, ils ne reçoivent pas toujours   toute   l’attention   et   la   vigilance nécessaire pour optimaliser leur développement. Dans ce contexte,   il   serait   intéressant   d’étudier   les   solutions   possibles   à   ces   problèmes.   L’utilisation   du   colostrum bovin semble être exploitable dans la mesure où il renferme des éléments nutritifs et antimicrobiens  nécessaires  pour  le  bovin,  mais  également  pour  d’autres  espèces  (caprins,  ovins,  porcs,   homme). Pour cette étude, le choix du colostrum bovin a été guidé aussi par sa disponibilité à la station sahélienne expérimentale de Toukounous au Niger. À priori, l’objectif de cette thèse est de vérifier l'hypothèse d'un effet bénéfique de l'administration du colostrum bovin sur la santé et les performances zootechniques des cabris. Le   premier   chapitre   présente   d’abord   le   milieu   physique   du   Niger,   puis   s’intéresse à quelques caractéristiques  des  animaux  de  l’étude  à  savoir  la  race  bovine  Azawak  et  la  race  caprine  dénommée   chèvre rousse de Maradi. En effet, le zébu Azawak est un animal de taille moyenne (1,3 m au garrot), Dans des très bonnes conditions et en élevage intensif, la vache zébu Azawak peut produire en moyenne  12  litres  par  jour.  Le  rendement  à  l’abattage  va  de  50  à  60%.  Quant  à  la  chèvre  rousse,  elle   est de taille moyenne ou petite (0,55-0,65 m). La durée de lactation est de 3 à 4 mois après la mise bas selon   les   conditions   d’élevage   et   la   production   laitière   annuelle   est   de   150   kg   en   200   jours.   Le   rendement  à  l’abattage  (poids  carcasse)  varie  de  50  à  55%  pour  le  sujet  castré. Le deuxième chapitre est une synthèse bibliographique sur la physiologie de la production et composition chimique du colostrum. Cette revue fait la compilation des informations les plus récentes sur le mécanisme de synthèse du colostrum, son aspect physico-chimique, son importance et enfin les facteurs de variation des composants chimiques de cette première sécrétion mammaire après la mise bas. Le colostrum renferme tous les éléments nécessaires permettant non seulement une protection contre les agressions d ́agents pathogènes, mais également une croissance rapide des jeunes animaux. Le chapitre trois est relatif à la comparaison par méta-analyse de la composition chimique du colostrum de la race bovine Azawak à des données synthétisées de la littérature. Cette étude a guidé le choix  de  l’espèce  dont  le  colostrum  doit  être administré au cours des expériences sur le terrain. Les concentrations  moyennes  d’IgG, IgM, MS, protéines et matières grasses pour la vache Azawak ont présenté des  valeurs  plus  faibles  (P  ˂  0,001) que celles obtenus chez d'autres races, mais il convient de noter des niveaux élevés d'IgA (P > 0,05), de  lactose  et  de  cendre  brute  (P  ˂  0,001). En ce qui concerne les minéraux solubles, les concentrations moyennes de Ca, P, Na et Mg dans le colostrum de bovin Azawak étaient  significativement  plus  élevées  (P  ˂  0,001) que celles de moyennes obtenues à partir des données de synthèse. En conclusion, comparé aux données de littérature, le colostrum de vache Azawak semble être plus pauvre en immunoglobuline, en lipides et en protéines, mais plus riche en lactose et en minéraux.  Il  se  pourrait  qu’il  s’agisse  d’une  adaptation  de  la  race  au  milieu  sahélien. Le  chapitre  quatre  est  intitulé  "l'Effet  de  l’administration  du  colostrum  de  bovin  Azawak  sur  le  profil   plasmatique, la croissance et la survie chez les chevreaux roux". Cette  étude  visait  à  évaluer  l’impact   de  l’administration  de  colostrum  hétérologue  Azawak  sur  le  profil  protéique  plasmatique,  la  croissance   et le taux de survie des chevreaux roux au Niger. Après la naissance et ce, jusqu'à la fin de l'essai, les poids vifs ont augmenté avec le temps dans les deux groupes, mais les valeurs ont été plus élevées dans le groupe colostrum que dans le groupe témoin (+ 1,4 kg à j29, P < 0,001). Dans l'ensemble, le groupe colostrum a présenté un gain moyen quotidien largement supérieur à celui du groupe témoin (P < 0,001). Les concentrations moyennes de fractions plasmatiques obtenues à l'âge de 10 et 30 jours ont atteint des valeurs plus élevées dans le lot colostrum que dans le lot contrôle. A 10 jours, le groupe colostrum a tendu à montrer des teneurs supérieures pour l'ɑ-globuline  et  la  β1-globuline (P < 0,06). A 30   jours,   les   protéines   totales   et   les   β2-globulines ont été supérieures dans le groupe colostrum. L’administration  du  colostrum  hétérologue  chez  le  chevreau  semble donc avoir des effets positifs sur certains paramètres plasmatiques et même les performances pondérales. Le  cinquième  chapitre  traite  de  "Effet  de  l’apport  en  colostrum  de  bovin  Azawak  sur  les  performances,   les paramètres de reproduction et la survie chez les chevreaux roux". Cette étude a permis de comparer les performances de croissance pondérale ainsi que le gain moyen quotidien de deux lots de cabris élevés selon les deux modes c'est-à-dire la supplémentation (n = 20) et son absence non (n = 20). Le poids vif moyen du groupe colostrum a atteint une valeur significativement plus élevée que celle obtenu chez les animaux non supplémenté (P < 0,001) et les effets du traitement sur ADG ont été observés jusqu'à 150 jours après la fin de la supplémentation. Une tendance similaire de longue durée a également été observée en relation avec le taux de mortalité (25% pour ColG vs 55% pour ConG, (P = 0,05). L'âge à la première mise bas tendait à être plus faible dans le groupe traité (13,8 ± 0,7 vs 14,1 ± 0,8 mois, p ˂ 0,1). Dans l'ensemble, l'analyse statistique a révélé des différences très significatives en faveur du groupe de colostrum. Globalement,   l’analyse   statistique   des   données   a   révélé   des   différences hautement significatives en faveur du lot colostrum. Le  sixième  chapitre  porte  sur  l’Effet  de  l’administration  post-partum de colostrum bovin Azawak sur les paramètres zootechniques de cabris roux. Un dispositif quasi-similaire à celui du premier essai (chapitre IV) a été appliqué. La différence se situait au niveau de la dose du colostrum administré. En effet, la quantité de colostrum administrée (15 ml) lors du premier essai a été majorée de 66,7 % au cours de cette expérimentation soit une quantité de 25ml/jour/chevreau. Comme le premier essai a été probant,   l’objectif   de   ce   travail   était   de   voir   si   l’augmentation   de   la   dose   du   colostrum   à   administrer   peut améliorer davantage les paramètres zootechniques et réduire considérablement le taux de mortalité. Les résultats indiquent que la supplémentation avec du colostrum bovin augmente la croissance  des  chevreaux  principalement  jusqu’au  sevrage  (P < 0,001),  améliore  l’état  sanitaire  et   diminue le taux de mortalité (P < 0,05), modifie quelques paramètres zootechniques. Cette étude suggère de prodiguer un allaitement  artificiel  chez  d’autres  espèces  animales  dont  les  mères  peinent  à   couvrir les besoins en colostrum et en lait de leur progéniture. A   notre   connaissance,   dans   l’environnement   étudié,   ce   travail   est   original et semble apporter de nouvelles connaissances qui auront probablement des applications pratiques dans les régions présentant  des  conditions  d’élevage  assez  difficiles. [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 detailÉléments optiques biréfringents pour interféromètre à chemins optiques quasi-communs
Blain, Pascal ULg

Doctoral thesis (2014)

Notre étude porte sur l’utilisation de composants optiques biréfringents en tant qu’élément séparateur dans un interféromètre à chemins optiques communs ou quasi-communs. Pour ce type d’interféromètre, la ... [more ▼]

Notre étude porte sur l’utilisation de composants optiques biréfringents en tant qu’élément séparateur dans un interféromètre à chemins optiques communs ou quasi-communs. Pour ce type d’interféromètre, la seule différence introduite dans les chemins optiques des faisceaux objet et de référence est celle résultant du relief de la surface testée. Utiliser un élément biréfringent permet de n’avoir qu’un seul élément pour créer les faisceaux référence et objet. On parle d’auto-référencement. Cette propriété désensibilise l’interféromètre vis-à-vis de certaines perturbations extérieures car les faisceaux sont identiquement affectés par celles-ci. La biréfringence des cristaux étant bien souvent faible mais l’interféromètre à construire devant être le plus compact possible, le cisaillement entre les deux faisceaux s’en retrouve faible comparé à la taille de l’objet observé. Une séparation totale des faisceaux émergents n’est possible qu’avec un faisceau « ponctuel » collimaté. La configuration des interféromètres que nous étudierons sera donc différentielle. Deux types d’éléments biréfringents sont étudiés. Le premier est un assemblage de deux cristaux uniaxes taillés à 45° et dont l’orientation de l’axe de l’un des cristaux est tournée à 90° par rapport à celle de l’autre. Il s’agit de la lame de Savart. Les propriétés de cette lame sont détaillées pour justifier l’intérêt de son utilisation dans l’interféromètre. Ce dernier a été utilisé en shearographie et en profilométrie par projection de franges interférométriques. Une installation originale permet l’association des deux méthodes dans un unique montage compact. Dans la configuration proposée, seule l’orientation du cisaillement par l’interféromètre est possible. Pour faire varier la taille du cisaillement, nous avons décidé d’évoluer vers un autre type d’élément biréfringent. L’essor des éléments optiques à biréfringence spatialement variable nous a incités à investiguer cette voie. Ces éléments ont la particularité de permettre une variation spatiale de l’orientation de l’axe optique. Les réseaux de polarisation font partie de cette famille. Après avoir décrit et simulé leur comportement, nous proposons notre propre méthode d’enregistrement de tels réseaux par holographie de polarisation à l’aide d’une lame de Savart. Nous prouvons par la suite que deux réseaux de polarisation circulaire de même orientation et disposés l’un à la suite de l’autre créent un élément séparateur à taille et orientation de cisaillement variables pour un interféromètre à chemins optiques quasi-communs. Nous proposons une application en shearographie. [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 detailFrontière(s), jeu d'acteurs et espace du contrôle: le cas de Ceuta
Bernes, Laure-Anne ULg

Doctoral thesis (2013)

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See detailMarchés boursiers africains : problématique de l’efficience, dynamique de la volatilité, rendement et volume des transactions
Woroucoubou, Habibou ULg

Doctoral thesis (2013)

With the exception of the Johannesburg Stock Exchange, African stock markets are characterized, in their vast majority, by a marginal number of listed companies, low capitalization, low trading volume and ... [more ▼]

With the exception of the Johannesburg Stock Exchange, African stock markets are characterized, in their vast majority, by a marginal number of listed companies, low capitalization, low trading volume and low liquidity. These characteristics raise questions about the volatility, efficiency, optimal compensation risks to investors and, more generally, to the price adjustment speed to the information conveyed by the volume of transactions. The objective of this doctoral work is to study the behavior of African stock markets through volatility, price, return and volume of transactions in connection with the performance and volatility. Compared to the volatility modeling, the study shows that the EGARCH model is the most suitable process may be applied to the data of African stock markets for estimating and forecasting volatility. For efficiency, the study shows that only the market of South Africa seems to be informationally efficient in the weak form. The analysis of the risk-return relationship reveals that only less developed markets (except Botswana) show a positive and significant premium risk. Such a result means that the least developed African stock markets in the sample reach rewarded accordingly risks for investors. For asymmetry, the study shows that there is presence of leverage for all emerging markets, indicating that in these markets, the bad news has a greater impact on volatility than good news of the same magnitude. In contrast, for less developed markets, there is no leverage. With respect to the relationship between the volume of transactions, performance and volatility, the study shows that emerging African stock markets showed a more or less close to the behavior of other emerging and developed markets of the world in terms of leverage, contemporary positive relationship and causality between trading volume and performance on the one hand, and between trading volume and volatility, on the other hand. In contrast, for other less developed stock markets, the impact of volume on return and volatility is less noticeable. [less ▲]

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See detailInsight into the mechanisms underlying the oncogenic potential of BCL-3 through transcriptomic studies
Zhang, Xin ULg

Doctoral thesis (2013)

Constitutive NF-κB activation, a hallmark of many hematological and solid tumors, disrupts the balance between apoptosis and proliferation by upregulating the expression of anti-apoptotic genes, thus ... [more ▼]

Constitutive NF-κB activation, a hallmark of many hematological and solid tumors, disrupts the balance between apoptosis and proliferation by upregulating the expression of anti-apoptotic genes, thus promoting cell growth and controlling angiogenesis, invasion and metastasis. Studies that addressed the roles of NF-κB in normal epidermis and in skin cancers led to conflicting results. Indeed, while enhanced NF-κB activities were reported in squamous cell carcinomas, inhibition of this pathway in normal epidermis paradoxically promoted cell carcinoma. Similarly, despite a constitutive NF-κB activity seen in cervical cancer, the precise role of NF-κB in the development of these tumours, which are associated with human papillomavirus (HPV) infection, also remains unclear. We define here PINB (for Protein induced by NF-kappaB and BCL-3) as a BCL-3- and p65-dependent gene in transformed keratinocytes. PINB expression is enhanced upon human papillomavirus (HPV) infection and is aberrantly expressed in clinical cases of cervical (pre)neoplastic lesions. Mechanistically, PINB binds Plexin A2, stabilizes EGFR and links Semaphorin 3A signalling cascades to EGFR phosphorylation. Moreover, PINB protects from Semaphorin 3A-mediated cell death and promotes EGF-mediated epithelial-mesenchymal transition (EMT) through the Ras/MEK1/ERK1/2 pathway. Taken together, our data define PINB as an oncogenic protein induced by constitutive NF-kappaB activity that transmits prosurvival and invasive signals through EGFR. In conclusion, we revealed new mechanisms by which constitutive NF-κB activation is linked to keratinocyte transformation in the skin and cervix. [less ▲]

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See detailContribution à l'étude des relations entre des poissons de la famille des Carapidae et leurs hôtes invertébrés
Parmentier, Eric ULg

Doctoral thesis (2013)

Among possible associations in sea, different Carapidae fish are able to live within various invertebrates such as holothuroids, starfishes and bivalves. In this study, a multidisciplinary approach is ... [more ▼]

Among possible associations in sea, different Carapidae fish are able to live within various invertebrates such as holothuroids, starfishes and bivalves. In this study, a multidisciplinary approach is realised to understand the biology of the Carapidae fish and to highlight the various factors which make these associations possible. Two research axis were carried out. The first axis attempts to establish Carapidae evolution. These approach was realised by comparisons 1) of the anatomy (muscles, skeleton, ligaments, dentition and otoliths), 2) of the functional morphology (feeding and sonic apparatus), 3) of the larvae development and 4) of the way of life of fish from the genera Pyramodon, Snyderidia, Echiodon, Onuxodon, Carapus and Encheliophis. The Carapidae may be divided in five ecomorphological groups which are placed on an ecological gradient leading to parasitism. The pelagic ancestor group gave rise to a benthic taxon. The latter could be at the origin of two distinct taxa of commensal fish. Within the Carapus clade, a group would have evolved to the parasitic life. The second axis of the study provided elements elucidating various aspects of the Carapini (Carapus and Encheliophis) behaviour. The morphofunctional study of the bucco-pharyngeal apparatus, the stable isotopes of carbon (13C) and nitrogen (15N), the stomach content determinations and the study of otolith increments allow to define clearly the commensal behaviour of Carapus and the parasitic behaviour of Encheliophis. The study of the larval development (axial skeleton and otoliths) reveals that the association between the fish and the host is obligatory, as the fish needs its host to initiate its metamorphosis. The hosts could be used as a bridal room. The capacities to emit sounds were also highlighted and the structures (skeletal, muscular and of the swim bladder) responsible were identified and described. The fish use the sound production at least to communicate inside the host but experimental manipulations also show that the fish are unable to determine if a host is already occupied or not. [less ▲]

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See detailStructural and biochemical study of the proteins AmiC, NlpD and FtsW involved in the bacterial cell division
Rocaboy, Mathieu ULg

Doctoral thesis (2013)

Cell division in the Gram negative bacterium Escherichia coli is a highly coordinated mechanism involving various physiological functions such as chromosome segregation, cell envelope invagination ... [more ▼]

Cell division in the Gram negative bacterium Escherichia coli is a highly coordinated mechanism involving various physiological functions such as chromosome segregation, cell envelope invagination, peptidoglycan synthesis at the division site and separation of the daughter cells. All these functions require a high level of spatio-temporal regulation in order to preserve the physical integrity of the cell. At least 20 proteins required for a proper cell division are recruited to the division site to form a supramolecular complex called the divisome. This thesis work focused on three major components of the E. coli division machinery: the N-acetylmuramyl L-alanine amidase AmiC, the LytM factor NlpD and the lipid II flippase FtsW. These proteins are recruited at midcell at a late stage of cell division. FtsW is an integral membrane protein crucial for the translocation of the peptidoglycan precursor from the cytoplasm to the periplasm where it will be processed to produce septal peptidoglycan. AmiC acts as a septal peptidoglycan hydrolase that allow the separation of the daughter cells. This enzyme has been shown to be activated by the LytM factor NlpD. The crystal structure of AmiC from E. coli presented in this work confirms the presence of an inhibitory helix in the active site. The AmiC variant lacking this helix exhibits by itself an activity comparable to that of the wild type AmiC activated by NlpD. Furthermore, the direct interaction between AmiC and NlpD has been detected by microscale thermophoresis with an apparent Kd of about 13 µM. The crystal structure of AmiC also reveals the β-sandwich fold of the AMIN domain, responsible for the septal targeting of AmiC to the division site. The two symmetrical four-stranded β-sheets exhibit highly conserved motifs on the two outer faces. Along with the peptidoglycan binding capacity of the AMIN domain, results obtained so far suggest that the AMIN domain could be involved in the recognition of a specific peptidoglycan architecture or a composition different than the lateral peptidoglycan. Production screenings of FtsW from different strains were realized and FstW from E. coli was purified. This challenging project will require additional efforts to obtain sufficient amount of protein for structural investigation. Information gathered in this work confirms the high level of regulation of the hydrolytic activity at the septum and gives a structural basis for a more precise molecular characterization of the division site targeting. Disruption or over-activation of these regulation mechanisms could represent a new strategy in the development of antibacterial compounds. [less ▲]

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See detailDéfinition de propriétés acido-basiques dans les liquides ioniques de seconde génération
Robert, Thierry ULg

Doctoral thesis (2013)

The ionic liquids are salts having the particularity of being molten at temperatures lower than 100 °C. Consequently, these new solvents mainly made up of ions have original physicochemical properties ... [more ▼]

The ionic liquids are salts having the particularity of being molten at temperatures lower than 100 °C. Consequently, these new solvents mainly made up of ions have original physicochemical properties. Within a few years, the ionic liquids passed from a laboratory curiosity to a true field of research impossible to circumvent, currently in full rise. Indeed, the replacement of usual organic solvents in catalytic and/or separation processes by these neoteric solvents offers many advantages but also new opportunities for the “Green Chemistry”. However, the systematic exploitation of the ionic liquids as reactional media rests in particular on the understanding of their chemical properties, which for some of them are still scarcely known, such as the acidity for example. This thesis thus aims to undertake a study of the acido-basic properties of (and in) these solvents, and more particularly to determine the accessible levels of acidity for acid solutions (with added HOTf or HNTf2) in second generation ionic liquids such as [HNEt3][NTf2], [BMIm][NTf2], [BHIm][NTf2], [BMIm][BF4], [BMIm][OTf], [BMIm][PF6] and [BMIm][SbF6]. In order to evaluate these acidity levels, we propose two different methods, each one resting on an extra-thermodynamic assumption. The first, the Hammett acidity function H0, is based on the protonation equilibrium of indicators whose pKa's are proposed as solvent independent. The second, the Strehlow potentiometric function R0(H+), consists in measuring, in a given solvent, the electrochemical potential of the proton compared to the ferricinium/ferrocene redox couple whose potential is supposed to be independent of the solvent, and then to refer it versus the Normal Hydrogen Electrode (NHE) in water. The two methods lead to the same conclusions. Firstly, the ionic liquids are generally contaminated by residual basic impurities (from solvents needed for the synthesis…) which need to be neutralized before reaching the acidity characteristic of the medium. The levels of acidity then obtained are very high and can reach values as high as R00(H+) = -10 in the case of [BMIm][BF4]. Then, the accessible level of acidity in an ionic liquid depends mainly on the nature of its anion, and not of that of its cation. We thus obtain the following classification, by decreasing acidity: [PF6-] > [BF4-] > [NTf2-] > [OTf-], indicating that the triflate is the more solvating anion It was found however that the Hammett acidity function led, for the same concentration in acid, to different levels of acidity, depending on the indicator used. The ionic liquids would consequently be media less dissociating than estimated in the literature and the Hammett function would then be related to an apparent acidity (H0)app, underestimating the real acidity. Finally, a difference in acidity between HNTf2 and HOTf is observed in [BMIm][NTf2] and [BMIm][OTf], HNTf2 showing an acidic character stronger than HOTf. On the other hand, in [BMIm][OTf] these two acids show the same acidity since that of HNTf2 has been leveled by solvent. [less ▲]

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See detailEntomofaune associée à Jatropha curcas (Euphorbiaceae) au Niger et évaluation de l'activité insecticide de son huile
Abdoul Habou, Zakari ULg

Doctoral thesis (2013)

Résumé Jatropha curcas L. est un arbuste de la famille des Euphorbiacées originaire d’Amérique centrale. Cette plante est cultivée pour son huile, valorisée dans la production de biocarburant. Cette huile ... [more ▼]

Résumé Jatropha curcas L. est un arbuste de la famille des Euphorbiacées originaire d’Amérique centrale. Cette plante est cultivée pour son huile, valorisée dans la production de biocarburant. Cette huile possède également une activité insecticide qui constitue un second volet de valorisation de la plante. Malgré la toxicité de la plante, de nombreux insectes causent des dégâts non négligeables au niveau des inflorescences, fruits et/ou des feuilles, réduisant considérablement le rendement en graine et la qualité de l’huile. La première partie de ce travail a consisté en la réalisation d’inventaires de ces insectes au Niger durant la période de juin à octobre, en 2010 et en 2011. Les principaux insectes ravageurs de J. curcas au Niger incluent les familles des Acrididae (Oedaleus senegalensis, O. nigeriensis, Heteracris leani, Parga cyanoptera, Catantops stramineus et Acanthacris ruficornis citrina), Cetoniidae (Pachnoda interrupta, P. marginata, P. sinuata et Rhabdotis sobrina), Coreidae (Leptoglossus membranaceus et Cletus trigonus), Pentatomidae (Agonoscelis versicoloratus, Nezara viridula et Antestia sp.) et Scutelleridae (Calidea panaethiopica). La seconde partie de ce travail a porté sur les possibilités d’utilisation de l’huile de J. curcas dans la lutte contre les ravageurs du niébé et le puceron noir de la fève. Des essais d’efficacité de terrain et de laboratoire ont été menés avec différentes formulations d’huile de Jatropha. Nous avons pu mettre en évidence un effet biocide croissant avec la concentration en huile. Les concentrations de 5% et 7,5% d’huile de J. curcas permettent de réduire le niveau d’attaque des pucerons (Aphis craccivora) de 10 et 50% respectivement par rapport au témoin. Une diminution du nombre des thrips (Megalurothrips sjöstedti) et de punaises (Anoplocnemis curvipes) respectivement de 50 et 75% est observée dans les mêmes conditions. Ces traitements ont conduit à une augmentation significative du rendement [less ▲]

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See detailContribution de la télémétrie à l'investigation urodynamique de la fonction vésico-urétrale chez la chienne.
Noël, Stéphanie ULg

Doctoral thesis (2013)

Micturition disorders are common in veterinary medicine and can occur already in puppies. The congenital urethral sphincter mechanism incompetence represents the second cause of urinary incontinence in ... [more ▼]

Micturition disorders are common in veterinary medicine and can occur already in puppies. The congenital urethral sphincter mechanism incompetence represents the second cause of urinary incontinence in puppies but data on the development and the evolution of the continence mechanism are lacking in veterinary medicine. This study could be the first step in the understanding of the pathophysiology of congenital urethral sphincter mechanism incompetence which resolves spontaneously in half of the affected dogs after the first of the second oestral cycle. The lower urinary tract has been widely investigated in adult female dogs, particularly by urodynamics. Urodynamics is a useful technique providing informations on the vesico-urethral function but some limitations are described. The major limitation is the need for sedation or anaesthesia as it is not feasable to obtain interpretable data from an awake animal. A second limitation is associated with the technique of retrograde cystometry because the technique of bladder filling and the filling rate are not physiological. Therefore, techniques have been developed such as diuresis cystometry or ambulatory urodynamics to decrease the impact of these limitations. In urological research, telemetry allows the investigation of different urodynamic parameters without the need for physical or chemical restraint and during several micturition cycles. The objectives of this work were to study the development and the evolution of the continence mechanism during the prepubertal period and during the two first oestral cycles and to study the vesico-urethral function with telemetry. This technique will be standardized and afterwards will be used to study different current urological drugs commonly used in veterinary medicine. In the first study, we showed that the values of the urodynamic and morphometric parameters of the lower urogenital tract varied in function of the growth of the bitches and also in function of the different phases of the œstrus cycle. The end of the prepubertal period was characterized by an increase of the urethral pressures (maximal urethral pressure, MUP ; maximal urethral closure pressure, MUCP ; integrated pressure, IP) and functional urethral length (FPL) but also by an increase of the urethral (UL) and vaginal lengths (VL) measured by vagino-urethrography compared with values at earlier times. The bladder function was characterized by a non-linear increase of the bladder capacity, which was reached at 6 months of age and by an increase of the bladder threshold pressure observed from 7 months of age. During the oestrus cycle, the urethral pressures significantly decreased during the oestrus and the early dioestrus which are characterized by a decrease in oestrogen plasmatic concentration and by an increase in progesterone plasmatic concentration. The highest values of FPL were observed during the follicular phase (œstrus, prooestrus). Values of UL could not be determined during œstrus of the first cycle because urethras were not identifiable on vaginourethrograms obtained at that time. During the second œstrus cycle, UL was significantly higher during œstrus and early dioestrus compared to anoestrus. No significant variation in Pth was observed during the first cycle ; however during the second cycle, the lowest Pth values were observed during late anoestrus. Pth values were also lower during œstrus compared to proestrus. The luteal phase was associated with an increase in bladder capacity that reached the highest value during the dioestrus. The VL decreased progressively during the second cycle to reach the lowest value during anoestrus. The MUCP and UL were significantly higher during the anoestrus of both cycles compared to the values obtained when the dogs were 9 months old. The same observation was made for IP at the first anoestrus. The increase in values of these parameters during periods with low hormonal influence could suggest an impact of the growth but also a constant improvement of bladder function all along the study. It was interesting to observe that the position of the bladder was variable during the prepubertal period as she was either in an intrapelvic or in an intra-abdominal position. After the prepubertal period, the bladder was always in an intra-abdominal position. In the second study, we showed that a single administration of ephedrine or phenylpropanolamine (PPA) was able to significantly modify the urodynamic and the morphometric parameters. Using conventional urodynamics, both ephedrine or PPA increased the urethral pressures during 4 hours and the FPL during 2 hours. The integrated pressure was elevated during 6 hours with PPA and its value was higher than the value obtained with ephedrine. On the other hand, the FPL remained elevated during 18 hours with ephedrine. Using telemetry, ephedrine, and to a lesser extent PPA, modified bladder function. The administration of ephedrine was associated with an increase in bladder threshold volume and a decrease of the detrusor threshold pressure. An increase in bladder volume was observed after PPA administration. Both drugs modified significantly the hemodynamic parameters. Arterial pressures were significantly increased during 4 to 6 hours after the administration of both drugs and were associated with a decrease in heart rate during 12 hours. These results were in agreement with previous studies and confirmed the fact that sympathetic drugs must be used with caution in incontinent dogs suspected of cardio-vascular diseases. In the third study, we showed that interpretable values of urodynamic parameters were obtained with telemetry. Physiological data were obtained from telemetric recordings because no sedative or analgesic drugs were used during the recording and bladder filling was natural. The location of the implant inside a subcutaneous cavity in the left flank did not disturb the dogs and the quality of the signals were good when the receiver was placed on the lateral wall of the metabolic cage. Telemetry allows continuous recording of values of urodynamic parameters (abdominal pressure, bladder pressure, detrusor pressure and bladder threshold volume) and values of smooth muscle electrical activity parameters. In the first step of the study, conventional urodynamics was compared to telemetry. The values of bladder threshold volume obtained by telemetry was significantly lower than the values obtained by conventional urodynamics. No difference in values of threshold bladder pressure was observed between the two techniques. In the second step of the study, the repeatability of telemetric recordings was assessed between day and night. A good repeatability was obtained with the night recordings. Comparing day and night recordings, higher bladder threshold volumes and lower detrusor threshold pressures were obtained during the night. No variation of the urodynamic parameters was observed during the bladder filling phase. The smooth muscle urethral electrical activity did not vary during the bladder filling phase. The frequency of micturition was not different between day and night but the frequency of involuntary detrusor contractions was higher during the day. In the third step of the study, the effect of drugs currently used to treat different micturition disorders were studied. Oestriol and duloxetine increased the electrical activity at day 8 compared to days 0, 1 and 15. No significant effect of PPA, oestriol, oxybutynin, bethanechol and duloxetine was observed on the values of urodynamic parameters or on the frequency of involuntary detrusor contractions. The results obtained in this study suggest that circadian variations may influence urodynamic measurements and that long-term telemetric studies of the lower urinary tract should be conducted during the night to obtain repeatable recordings. Further pharmacokinetic and pharmacodynamics studies are needed to confirm the effects of the different drugs on vesico-urethral function. [less ▲]

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See detailLa limite Paléocène-Eocène dans le Bassin de Douala Biostratigraphie et essai de reconstitution des paléoenvironnements
Mbesse, Cecile Olive ULg

Doctoral thesis (2013)

ABSTRACT This work consists of the analysis of the palynoflora (dinoflagellates and sporomorphs) identified from four petroleum exploration wells drilled through the Nkapa Formation (Douala Basin ... [more ▼]

ABSTRACT This work consists of the analysis of the palynoflora (dinoflagellates and sporomorphs) identified from four petroleum exploration wells drilled through the Nkapa Formation (Douala Basin, Cameroon). The vertical distribution of index taxa in the Moulongo, Ngata, Mamiwater and North Matanda wells allowed establishing a biostratigraphic frame of the first half of the Paleogene of the Douala Basin and identifying the Paleocene/Eocene boundary in each well through a comparison with surrounding sedimentary basins. Seventy dinoflagellate species have been identified, among which 30 are stratigraphically informative. Four biozones have been established, three for the Paleocene and one for the Early Eocene. The biozone 1 is characterized by Cretaceous species such as Cerodinium diebelii, Lejeunecysta hyalina, Andalusiella gabonensis, Palaeocystodinium australinum and Palaeocystodinium golzowense. The biozone 2 is defined by the acme of Areoligera coronata, Adnatosphaeridium multispinosum and Glaphyrocysta ordinata. The biozone 3 is defined by the acme of several Apectodinium species (A. hyperacanthum, A. homomorphum, A. paniculatum, A. parvum, A. quinquelatum). The biozone 4 is defined by the occurrence of Eocene taxa such as Deflandrea cf. oebisfeldensis, Hystrichosphaeridium tubiferum and Wetzeliella sp. Based on the position of the Paleocene/Eocene boundary in the Moulongo well, correlations have been established with the others sedimentary sequences analysed. Our study shows that, as previously demonstrated for Nigeria in an other study, the acme of Apectodinium in the Douala Basin can be attributed a Late Paleocene age and hence occurred before the carbon isotope excursion (CIE) of the Paleocene-Eocene boundary and the coeval Paleocene-Eocene thermal maximum (PETM). The acme of Apectodinium in the Douala Basin is thus markedly diachronous with the Apectodinium acme identified in various Nordic Basins, where it is contemporaneous with the PETM (earliest Eocene). Ninety-four sporomorph species have been recognized, among which fifty are stratigraphically informative. Three biozones have been established. The biozone 1 is predominantly characterized by Palmae- and Proteaceae-type pollens, the latter with Cretaceous characteristics. The biozone 2, Late Paleocene in age, is characterized by a transition from original floras towards more « modern » floras. The biozone 3 is earliest Eocene in age and shows the early steps of the extant « Leguminosae flora » of West Africa. Together with the biostratigraphic analysis, a palaeoenvironmental reconstruction is proposed, based on dinoflagellate ecology, on the evolution of the dinoflagellate /sporomorph ratio, as well as on the reconstruction of the plant environments in the studied sedimentary sequences. The evolution of the Douala Basin during the timespan studied occurred according to two geographical axes: a WE (Moulongo-Ngata) axis and a SSW-NNE (Moulongo-Mamiwater-North Matanda) axis. During the Early and Middle Paleocene, the Douala Basin was open towards the sea and showed a coastal-estuarine environment, with marginal mangroves and lowland swamp forests. During the Late Paleocene, the marine character of the sedimentation was less prominent as brackish fluvio-lagoonal intertidal environments developped. They were accompanied by gallery forests and surrounded by dense, periodically flooded, forests northwards and by forests on wet soils eastwards. During the earliest Eocene, a marine regression occurred. The palaeoenvironments included confined coastal lagoon systems with a peripheral impoverished local flora northwards, and moist, dense, evergreen forests eastwards. [less ▲]

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See detailLa limite Paléocène-Eocène dans le Bassin de Douala Biostratigraphie et essai de reconstitution des paléoenvironnements
Mbesse, Cécile ULg

Doctoral thesis (2013)

RESUME Ce travail présente une analyse du phytoplancton et des sporomorphes recensés dans divers puits de prospection pétrolière ayant traversé la Formation de Nkapa dans le Bassin de Douala au Cameroun ... [more ▼]

RESUME Ce travail présente une analyse du phytoplancton et des sporomorphes recensés dans divers puits de prospection pétrolière ayant traversé la Formation de Nkapa dans le Bassin de Douala au Cameroun. La distribution verticale de taxons marqueurs dans les sondages de Moulongo, Ngata, Mamiwater et Nord Matanda a permis d’établir une biostratigraphie du Tertiaire inférieur du Bassin et d’y préciser la position de la limite Paléocène-Eocène sur base d’une comparaison avec les bassins sédimentaires avoisinants. En considérant trente espèces de dinoflagellés à caractère stratigraphique sur les quelque septante inventoriées, quatre biozones ont pu être établies, trois pour le Paléocène, une pour l’Eocène basal. La biozone 1 se caractérise par des espèces héritées du Crétacé, Cerodinium diebelii, Lejeunecysta hyalina, Andalusiella gabonensis, Palaeocystodinium australinum et Palaeocystodinium golzowense; les biozones 2 et 3 par les acmés de certaines espèces, pour la 2, de Areoligera coronata, Adnatosphaeridium multispinosum et Glaphyrocysta ordinata, pour la 3, de diverses espèces du genre Apectodinium (A. hyperacanthum, A. homomorphum, A. paniculatum, A. parvum, A. quinquelatum). La biozone 4 voit apparaître des espèces caractéristiques de l’Eocène: Deflandrea cf. oebisfeldensis, Hystrichosphaeridium tubiferum et Wetzeliella sp. En tenant compte de la limite Paléocène/Eocène établie par les stratigraphes pétroliers à Moulongo, les corrélations ont été précisées avec les autres séquences analysées. L’étude a mis en évidence l’existence d’un diachronisme entre deux acmés d’Apectodinium, celui pré-CIE (Carbon Isotope Excursion) observé au Paléocène supérieur dans le Bassin de Douala comme dans celui du Nigeria voisin et celui contemporain du PETM (Paleocene-Eocene Thermal Maximum) dans l’Eocène basal de divers bassins nordiques passés en revue dans le travail. Sur les nonante-quatre espèces de sporomorphes identifiées, une cinquantaine de taxons a été retenue dans un objectif biostratigraphique. Trois biozones à caractère évolutif se sont dégagées: une biozone inférieure à caractère paléocène soulignée par une dominance de formes de types « Palmae » et « Proteaceae », ces dernières d’aspect archaïque crétacé; une biozone intermédiaire du Paléocène supérieur avec évolution de la flore originelle vers un ensemble qui peut être qualifié de plus « moderne » et enfin, à l’Eocène basal, de l’installation d’associations annonçant les prémices de la mise en place de la flore actuelle à « Légumineuses » d’Afrique de l’Ouest. En parallèle de l’analyse biostratigraphique est proposée une reconstitution paléoenvironnementale basée sur l’écologie des dinoflagellés, sur l’évolution du ratio dinoflagellés/pollen et spores et sur la reconstitution des milieux végétaux dans les différentes séquences étudiées. L’évolution du Bassin selon deux axes géographiques a été mise en évidence: un axe WE (Moulongo-Ngata) et un axe SSW-NNE (Moulongo-Mamiwater-Nord Matanda). Au Paléocène inférieur et moyen, le Bassin, largement ouvert sur la mer, présente un milieu côtier-estuarien frangé de mangroves et de forêts de basse plaine marécageuse. Au Paléocène supérieur, l’influence marine se faisant moins importante, des milieux saumâtres fluvio-lagunaires soumis aux marées se développent, ils sont bordés de galeries forestières et entourés de forêts denses périodiquement inondées vers le Nord et de forêts sur sols humides vers l’Est. Avec la régression marine amorcée à la base de l’Eocène, les paléoenvironnements s’individualisent: vers le Nord s’installent des milieux lagunaires confinés entourés d’une flore locale appauvrie et vers l’Est, autour de milieux d’eau douce d’arrière-delta, une forêt dense sempervirente humide de terre ferme occupe le terrain. [less ▲]

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See detailAmélioration de l’efficience d’utilisation de l’eau chez les principales cultures fourragères au Tadla- Maroc
Bouazzama, Bassou ULg

Doctoral thesis (2013)

Aiming to define irrigation strategies improving the water productivity by folder crops under water scarcity in the irrigated perimeter of Tadla (Morocco), this work combines field experimentation and ... [more ▼]

Aiming to define irrigation strategies improving the water productivity by folder crops under water scarcity in the irrigated perimeter of Tadla (Morocco), this work combines field experimentation and modeling. The field study of crop response to water stress is important to maximize yield and improve agricultural water use efficiency (WUE) in areas where water resources are limited. On the silage maize, the results showed that water deficit affected plant height growth, accelerated the senescence of the leaves and reduced the leaf area index. Dry matter yields varied from 3.9 t.ha-1 under T5 (20% ETc) to 16.4 t.ha-1 under T1 (100% ETc). The establishment of the water budget by growth phase showed that the water use efficiency was higher during the linear phase of growth. WUE calculated at harvest varied between 2.99 kg.m-3 under T1 and 1.84 kg.m-3 under T5. The actual evapotranspiration under T1 (100% ETc) was 478 mm and 463 mm in 2009 and 2010, respectively. The yield response factor (Ky) for the silage maize for both growth seasons was 1.12. The ETc of silage maize was determined using lysimeter drainage at 415 mm. the mean values of crop coefficients Kc were 0.56, 1.22 and 1.05 for beginning phase, mid-season and at harvest (grain milky pasty stage) respectively. Drip irrigation allows obtaining dry matter yields similar to flood irrigation but with less water and saves about 30% of irrigation water applied. Over five cycles, berseem dry biomass yields achieved under T1 are 14.3 and 13.9 t/ha in 2009/10 and 2010/11 respectively. The yield reductions by applying 60% of water requirements are 40 and 42% in 2009/10 and 2010/11 respectively. Berseem daily productivity increases with more water applied with the highest value of 102 kg DM/ ha/ day. The dry matter content increases with water stress. The mean values range between 12.3 and 23.7% under T1 (100% ETc) and T4 (40% ETc) respectively. The contribution of without irrigation cycles (rainy period) on the total annual yield may vary from 35% to 52% under treatments T1 and T4 respectively. Water balance achieved by water regime shows that drainage losses increase with more water applied especially in the first cycle. WUE is low during the first cycle, optimal in 2nd, 3rd and 4th cycle and decreases in the last one with water stress. Global WUE of berseem determined over the entire crop period (slope of the regression line) is 3.37 kg.m-3. The yield response factor (Ky) for the berseem for both growth season was 1.11. Berseem ETc determined by drainage lysimeter was 520 mm. The Kc values were estimated for each cycle for all three phases: initial, development (median) and mid-season. Maximum yield average under drip irrigation was 15.7 t/ha and obtained with 411 mm of water supply allowing to save 57% of water compared to traditional irrigation technique. Comparing the behavior of six alfalfa varieties most commonly practiced in the irrigated perimeter of Tadla shows that the "Super Siriver" cultivars followed by «Trifecta» have higher yield potential and higher tolerance to water deficit. Alfalfa maximum annual yield obtained was 24.2 t.ha-1. The contribution of the spring cycles to the annual yields range from 55% under T1 (100% ETc) to 65% under T4 (40 % ETc). In addition to water quantities, alfalfa yields depend on time application during a growth cycle. WUE varies from cycle to another and from one season to another. The maximum value was 2.57 kg.m-3 and obtained in spring 2011, while the low value was 0.64 kg.m-3 and obtained in winter 2010. WUE decreases with water stress, with mean values of 1.83, 1.67, 1.54 and 1.23 kg.m-3 under T1 (100% ETc), T2 (80% ETc), T3 (60% ETc) and T4 (40% ETc) respectively. The yield response factor (Ky) of alfalfa was 0.92. The determination of the alfalfa water requirements was performed on the basis of cycle’s calendar during two years in 2010 and 2011. The values founded for flood irrigation are 1388 and 1364 mm respectively for the two years. Drip irrigation allows achieving similar dry mater yield to flood irrigation with less water and agronomic efficiency. Water applied under T1 in drip irrigation with 50 cm of spacing between ramps was less than water requirements (of alfalfa) by about 7% and 18% in 2010 and 2011 respectively. Under the same treatment in flood irrigation, the water requirements are exceeded by 16% and 21% in 2010 and 2011 respectively. Two crop models, PILOTE and CropSyst, had been selected to be tested on their ability to simulate the growth and yield of the studied crops under the edaphic-climatic conditions of Tadla. Tested on silage maize, both models correctly simulated the growth and development of the crop under different water regimes. The parameters of both models are validated and shown effective for simulation of biomass, leaf area index and soil water storage. Although PILOTE requires less parameters and data than CropSyst, it often proves to be more successful in simulating the biomass of silage maize and water balance. As to berseem, predictions of biomass by CropSyst seem to be more accurate than PILOTE model. The latter was best at predicting the soil water reserve on the soil depth exploited by the roots (0-80 cm). Given its ease of integrating daily climatic data for several years, CropSyst model was chosen to test its ability to simulate the crop rotation of berseem and maize silage. The results show that this model correctly simulates the evolution of biomass and yields of the two crops considered in rotation during three years. Modeling the growth and production of alfalfa is made by both models outside the crop installation period (seeding year). After calibration and validation achieved, the model CropSyst simulates adequately biomass and soil water reserve under all water regimes considered while PILOTE best simulations were limited to non-stressed treatment T1 (100% ETc). Although CropSyst model takes into account several parameters in the simulation of alfalfa growth, their simplifications (unique values) reduce its performance in more water stress situation. Less parameters considered in the PILOTE model makes it validation difficult for perennial crops such as alfalfa. CropSyst model was used to evaluate irrigation practices of farmers and develop irrigation virtual scenarios for the three crops studied. The assessment shows that virtual scenario developed for alfalfa that applying 1600 mm of irrigation water amount through 14 applications divided into six irrigations during the spring, six in summer, one in the fall and another in early winter maximizes irrigation water efficiency (1.21 kg/m3) and achieve a yield of 23.1 t/ha (95% of the yield potential). In the case of maize, if water is available, application of 648 mm according to the combination [2 irrigations in initial phase (after sowing), 2 irrigations in linear and two in final phases] allows to achieve high biomass yield and better water use. On berseem, the simulation results confirm that the adoption of the scenario that provides 625 mm through 7 irrigations (3 in autumn, 2 in winter and 2 in spring) allows obtaining 14.1 t/ha of dry matter which represents 94% of the yield potential of the 6454 cultivar. This scenario allows greater water efficiency (1.24 kg/m3) and results in low water drainage losses estimated at about 17% of applied water. The comparison of the two cropping systems represented by alfalfa and silage maize-berseem rotation shows that the rotation allows the better water use and mobilizes less water than alfalfa, which is distinguished by its profitability. Finally, the coupling of the results of three years (2008 to 2011) "in situ" experimentations with the simulations of scenarios by CropSyst and PILOTE models has shown to be highly effective in order to improve the folder crops irrigation in the Tadla irrigated area in Morocco. [less ▲]

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See detailFundamental and Applied Studies on Freeze-dried Vinegar Starter
Shafiei, Rasoul ULg

Doctoral thesis (2013)

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant : le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud est du Cameroun
Bourland, Nils ULg

Doctoral thesis (2013)

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged ... [more ▼]

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged trees. These species may have established in the past because of large disturbances. Indeed, major climate changes have occurred in the past few millennia, in some areas coupled with strong human occupations. Among these light-demanding species we find the assamela / afrormosia (Pericopsis elata (Harms) Meeuwen, Fabaceae), a large high trading value tree of African semi-deciduous moist forests. Nowadays this logged species suffers from significant regeneration problems on its natural range from Ghana to the Democratic Republic of Congo. Therefore, it is included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. No convincing solution can be found in the available scientific literature to overcome the deficiency of its regeneration. In addition, little or no information is available describing ca. its population dynamics, genetics, silviculture or the probable origin of its stands. It is in this context that the present PhD was undertaken. In this study, we have adopted a multidisciplinary approach to understanding the dynamics of this population rich in long-lived light-demanding species logged in the Congo basin. Moreover, we have suggested ways for their management and conservation in a changing world. To do so, we have adopted as a study-model the case of P. elata in southeastern Cameroon. The main results of the study show that, on a local scale, physico-chemical soil parameters have no influence on the presence or absence of this clustered species. However, on the same scale, large quantities of charcoal were found in the soil, mainly inside those clusters. The anthracological analysis has also shown that the vegetation at the time of the burn was similar to that of today. Numerous fragments of pottery were also found in the top soil layers only inside clusters formed by the species. Finally, some 14C datings go back to ca. 200 years BP, which is approximately the average age of concerned clusters. This body of evidence leads us to conclude on an ancient form of shifting cultivation as the most likely origin of the assamela populations currently present in southeastern Cameroon. In addition to its current population structure within the study area, several parameters controlling its population dynamics were estimated. While the annualized natural mortality of the species reaches about 1%, its average diameter growth rate is 0.31 cm.year-1, which is a relatively low value compared to other long-lived light-demanding species. Selective logging seems to have only a light influence on the behavior of the species. On the other hand, the impact of logging on its seed tree populations is only ca. 12%. Each seed tree bears fruit on average only once every five years. The minimum diameter of reproduction and the effective flowering diameter were respectively 32 and 37 cm. The recovery rate, varying greatly from one country to another, is more than 100% in Cameroon, where the conservation status assigned to the species seems excessive. A sufficient regeneration by planting should allow the perpetuation of the assamela populations in the long run, as with other major logged light-demanding trees. [less ▲]

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See detailOn the Verification of Programs on Relaxed Memory Models
Linden, Alexander ULg

Doctoral thesis (2013)

Classical model-checking tools verify concurrent programs under the traditional "Sequential Consistency" (SC) memory model, in which all accesses to the shared memory are immediately visible globally, and ... [more ▼]

Classical model-checking tools verify concurrent programs under the traditional "Sequential Consistency" (SC) memory model, in which all accesses to the shared memory are immediately visible globally, and where model-checking consists in verifying a given property when exploring the state space of a program. However, modern multi-core processor architectures implement relaxed memory models, such as "Total Store Order" (TSO), "Partial Store Order" (PSO), or an extension with locks such as "x86-TSO", which allow stores to be delayed in various ways and thus introduce many more possible executions, and hence errors, than those present in SC. Of course, one can force a program executed in the context of a relaxed memory system to behave exactly as in SC by adding synchronization operations after every memory access. But this totally defeats the performance advantage that is precisely the motivation for implementing relaxed memory models instead of SC. Thus, when moving a program to an architecture implementing a relaxed memory model (which includes most current multi-core processors), it is essential to have tools to help the programmer check if correctness (e.g. a safety property) is preserved and, if not, to minimally introduce the necessary synchronization operations. The proposed verification approach uses an operational store-buffer-based semantics of the chosen relaxed memory models and proceeds by using finite automata for symbolically representing the possible contents of the buffers. Store, load, commit and other synchronization operations then correspond to operations on these finite automata. The advantage of this approach is that it operates on (potentially infinite) sets of buffer contents, rather than on individual buffer configurations, and that it is compatible with partial-order reduction techniques. This provides a way to tame the explosion of the number of possible buffer configurations, while preserving the full generality of the analysis. It is thus possible to even check designs that may contain cycles. This verification approach then serves as a basis to a memory fence insertion algorithm that finds how to preserve the correctness of a program when it is moved from SC to TSO or PSO. Its starting point is a program that is correct for the sequential consistency memory model (with respect to a given safety property), but that might be incorrect under TSO or PSO. This program is then analyzed for the chosen relaxed memory model and when errors are found (a violated safety property), memory fences are inserted in order to avoid these errors. The approach proceeds iteratively and heuristically, inserting memory fences until correctness is obtained, which is guaranteed to happen. [less ▲]

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See detailEnzymatic synthesis of glycosylated compounds in non-conventional media
Galonde, Nadine ULg

Doctoral thesis (2013)

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See detailStudy of the roles of Cyprinid herpesvirus 3 ORF134 in the biology of the infection
Ouyang, Ping ULg

Doctoral thesis (2013)

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

The common carp is one of the most important freshwater fish species in aquaculture, and its colourful subspecies koi is grown for personal pleasure and competitive exhibitions. Both two subspecies are economically important. In the late 1990s, a highly contagious and lethal pathogen called koi herpesvirus (KHV) or cyprinid herpesvirus 3 (CyHV-3) began to cause severe financial losses in these two carp industries worldwide. In 2005, CyHV-3 has been classified in the Alloherpesviridae family of the order Herpesvirales. Because of its economic importance and its numerous original biological properties, CyHV 3 became rapidly an attractive subject for applied and fundamental research. However, to date, there is a little information on the roles of individual CyHV-3 genes in the biology of CyHV-3 infection or its pathogenesis. Moreover, there is a lack of safe and efficacious vaccine for the control of CyHV-3 disease. The goal of this thesis was to study the roles of CyHV-3 ORF134 encoding an IL-10 homologue in the biology of the infection. CyHV-3 ORF134 has been predicted to contain an 84 bp intron flanked by 2 exons encoding together a 179 amino acid product. Transcriptomic analyses reveal that ORF134 is expressed as a spliced early-late gene. The identification of the CyHV-3 secretome was achieved using 2D-LC MS/MS proteomic approach. This method led to the identification of 5 viral and 46 cellular proteins in concentrated infected cell culture supernatant. CyHV-3 ORF12 and ORF134 were amongst the most abundant proteins detected. To investigate the roles of ORF134 in the biological of the infection, a strain deleted for ORF134 and a derived revertant strain were produced by using BAC cloning and prokaryotic recombination technologies. Comparison of these strains demonstrated that CyHV-3 ORF134 does not contribute significantly to viral growth in vitro or to virulence in vivo in the present laboratory setting. The present study addressed for the first time the in vivo role of a vIL-10 encoded by a member of the family Alloherpesviridae. This study has been published in Veterinary Research. During the course of the first study, we obtained an unexpected recombination event while we were reconstituting infectious virus from mutated BAC plasmids. To generate a revertant ORF134 Del galK strain, CCB cells were co-transfected with the FL BAC ORF134 Del galK plasmid and the pGEMT-TK vector to remove the BAC cassette inserted in the ORF55 locus (encoding thymidine kinase). One of the clones obtained had an unexpected recombination leading to the deletion of ORF56 and ORF57 in addition to the expected deletion of ORF134. Unexpectedly, this triple deleted strain replicated efficiently in vitro, exhibited an attenuated phenotype in vivo and was proved to confer in a dose dependent manner an immune protection against a lethal challenge. The goal of the second experimental chapter was to investigate the role of the ORF56-57 and ORF134 deletions in the observed safety/efficacy profile of the triple deleted recombinant. To reach this goal, a collection of recombinant strains were produced using BAC cloning technologies, characterized and tested in vivo for their safety/efficacy profile. The results obtained demonstrated that the ORF56-57 deletion is responsible for the phenotype observed and that ORF134 deletion does not contribute to this phenotype significantly. Finally, the immune protection conferred by ORF56-57 deleted recombinant was investigated by challenging immunized fish with a wild type strain expressing luciferase as a reporter gene. In vivo imaging system (IVIS) analyses of immunized and challenged fish demonstrated that the immune response induced by the ORF56-57 deleted strain was able to prevent subclinical infection of the challenge strain. In conclusion, the present thesis addressed both fundamental and applied aspects of CyHV-3. For the first time, it investigated in vivo the roles of a viral IL-10 homologue encoded by a member of the family Alloherpesviridae. Importantly, it identified the ORF56-57 loci as target for production of safe and efficacious attenuated recombinant vaccines. [less ▲]

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See detailLe Rhin aux époques romaines. Zone grise, frontière, branchements
Dignef, Anthony ULg

Doctoral thesis (2013)

Dans cette thèse de doctorat, j’ai repris l’étude des processus et des conditions d’émergence et d’existence, de stabilisation et d’évolution de la frontière du Rhin aux époques romaines, c’est-à-dire ... [more ▼]

Dans cette thèse de doctorat, j’ai repris l’étude des processus et des conditions d’émergence et d’existence, de stabilisation et d’évolution de la frontière du Rhin aux époques romaines, c’est-à-dire essentiellement les périodes post-républicaine et impériale, de César à Valentinien Ier. L’idée était de procéder à une nouvelle analyse des dynamiques liées au phénomène frontalier. Ainsi, dans un souci d’élargissement du domaine de l’histoire militaire généralement attendue, j’ai tenté le difficile exercice de l’appréhension du système de limite du Nord-Ouest de l’Empire, par une relecture croisée des problématiques de l’affirmation du pouvoir romain, des transformations socio-politiques des sociétés en marge de l’Empire, et des façons dont celles-ci ont conditionné la frontière du Rhin. Ce travail dépasse donc largement le cadre d’une étude des installations frontalières, lesquelles ont déjà considérablement retenu l’attention des chercheurs. Il tient, en outre, et probablement davantage, de l’histoire politique, de l’histoire des relations internationales et de l’histoire connectée, telle que je l’ai découverte à travers les travaux de Sanjay Subrahmanyam et de Romain Bertrand. [less ▲]

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See detailAdaptation de la procédure de Maquet pour le traitement chirurgical de la rupture du ligament croisé crânial chez le chien
Etchepareborde, Sébastien ULg

Doctoral thesis (2013)

La rupture du ligament croisé crânial est la première cause d’ostéoarthrose chez le chien. Récemment, une étude a évalué à plus d’un milliard de dollars le chiffre d’affaire que générait cette pathologie ... [more ▼]

La rupture du ligament croisé crânial est la première cause d’ostéoarthrose chez le chien. Récemment, une étude a évalué à plus d’un milliard de dollars le chiffre d’affaire que générait cette pathologie annuellement aux Etats-Unis. Bien que la rupture du ligament croisé crânial (RLCC) soit la cause la plus fréquente de boiterie du membre postérieur rencontrée dans les centres de référés, aucune technique chirurgicale ne semble prévaloir sur les autres. La pléthore de publications sur la RLCC, pas moins de 160 articles consacrés à ce sujet au cours des 6 dernières années dans les 5 plus importantes revues de chirurgie vétérinaire, témoigne du manque de consensus dans ce domaine. Si les chirurgies intracapsulaires ou la physiothérapie uniquement sont les méthodes les plus employées en médecine humaine pour traiter la rupture du ligament croisé antérieur (RLCA), elles se sont montrées insatisfaisantes en médecine vétérinaire. Les techniques extracapsulaires utilisées depuis des décennies se sont vues, elles aussi, remplacées par des techniques de stabilisation dite dynamique : principalement l’ostéotomie de nivellement du plateau tibial (Tibial Plateau Levelling Osteotomy : TPLO) et l’avancement de la tubérosité tibiale (Tibial Tuberosity Advancement : TTA). Cette dernière chirurgie est une adaptation d’une technique utilisée chez l’homme et décrite par P. Maquet en 1976. Bien que la technique se réalise sans aucun implant synthétique chez l’homme, la technique décrite chez le chien présente de nombreux implants pour stabiliser la crête tibiale une fois son avancement réalisé. La mise en place de ces implants entraine une approche invasive de la face médiale du tibia. Les objectifs de ce travail sont d’adapter progressivement la TTA originalement décrite, pour la simplifier telle qu’elle est réalisée chez l’homme, c’est à dire avec pour seul implant un bloc placé dans le trait d’ostéotomie. Cette simplification s’inscrit dans le mouvement actuel de chirurgie minimalement invasive avec une préservation optimale des tissus. En référence à son inventeur chez l’homme, nous avons baptisé cette chirurgie la Technique de Maquet Modifiée (Modified Maquet Technique : MMT). Dans la première étude, le trait d’ostéotomie décrit dans la technique de TTA a été modifié pour laisser intact la partie la plus distale de la corticale de la crête tibiale créant ainsi une « charnière » osseuse. Après cette nouvelle ostéotomie, la résistance à la traction de la crête tibiale a été testée dans trois cas de figures : 1) lorsque la charnière est intacte et la crête maintenue par un fil de cerclage, 2) lorsque la charnière est intacte mais non maintenue et 3) lorsque la charnière est accidentellement cassée, la crête étant maintenue uniquement par un fil de cerclage. Cette étude biomécanique a montré que lorsque la charnière est intacte, le fil de cerclage n’augmente pas la résistance du montage et que la crête tibiale résiste à des tensions supérieures à celles rencontrées dans le grasset d’un chien au pas. En revanche, si la charnière est cassée, la tension tolérée par la crête est significativement inférieure à celle des deux autres groupes. Dans une deuxième étude, la technique nouvellement testée a été utilisée sur un panel de 20 chiens présentés pour une RLCC. Malgré l’absence de plateforme de marche pour évaluer objectivement la récupération fonctionnelle, la MMT a montré des résultats prometteurs et subjectivement comparables à ceux des autres techniques de stabilisation dynamique. Le temps moyen de cicatrisation de la crête était inférieur à 7 semaines, ce qui est dans la moyenne publiée pour la TTA. Aucune complication majeure n’a nécessité de réintervention dans cette étude préliminaire. Une étude prospective avec une plateforme de marche permettrait de comparer directement ces résultats à ceux déjà publiés sur la TTA. Grâce à notre expérience tant ex-vivo que clinique, il nous est apparu que le trait d’ostéotomie tel que nous l’avions décrit pour réaliser cette charnière osseuse n’était pas optimal. En effet, le trou foré à l’extrémité distale de l’ostéotomie, censé prévenir la propagation de fissures lors de l’avancée de la tubérosité tibiale, non seulement n’empêchait pas toujours l’apparition de telles fissures mais était, de plus, toujours le site de fracture de la crête tibiale dans les rares cas où nous l’avons observée. Au lieu de concentrer toutes les contraintes de la déformation osseuse au niveau de cette charnière, nous avons donc eu l’idée de prolonger distalement l’ostéotomie parallèlement à la corticale afin de diminuer les contraintes de déformation. Cette troisième étude nous a permis de tester de manière approfondie ce nouveau trait d’ostéotomie. Nous en avons conclu que l’avancement maximal autorisé était proportionnel au poids du chien et à l’avancée angulaire de la crête ; la résistance maximale était proportionnelle à l’épaisseur de la charnière. Grâce à cette nouvelle ostéotomie, pour toutes les catégories de chiens, l’avancement permis était supérieur aux valeurs utilisées cliniquement. Par ailleurs, la résistance de la crête à la traction était encore supérieure à celle décrite dans notre première étude. Notre quatrième étude visait poursuivre le processus de simplification pour atteindre notre objectif d’appliquer directement au chien l’avancement de la tubérosité tibiale tel que réalisé chez l’homme. Après une étude monotonique de plusieurs matériaux (cage en titane Kyon, bloc de mousse de titane et bloc d’os synthétique biphasique de différentes porosités), ceux présentant une résistance compatible avec les forces rencontrées in vivo ont été soumis à une étude cyclique afin d’évaluer leur capacité à rester dans le trait d’ostéotomie sans aucun autre moyen de fixation que la friction avec l’os. Le bloc de mousse de titane et le bloc d’os synthétique de porosité 60% ont ainsi été testés cycliquement. Durant le test, aucun des implants n’a migré, prouvant ainsi que la friction était suffisante pour maintenir l’implant dans l’ostéotomie. De plus, l’os synthétique s’est révélé capable de résister aux 200 000 cycles permettant ainsi d’envisager, enfin, la réalisation d’une MMT aussi simplement que l’avancement de la tubérosité tibiale décrite chez l’homme. Nos travaux intensifs sur la technique d’avancement de la tubérosité tibiale nous ont conduit à observer une sous-estimation de l’avancement nécessaire préconisé jusque-là. Bien que cela n’ait jamais été mentionné dans la littérature, la prise en compte de cette sous-estimation est indispensable à la réalisation correcte de la chirurgie. Après avoir étudié, dans un premier papier, la variabilité intra- et inter-opérateur de la mesure de l’angle entre le tendon patellaire et le plateau tibial (PTA), et donc indirectement de celle de l’avancement, une deuxième étude a porté sur la quantification de cette sous-estimation et la proposition d’abaques destinés à la corriger. [less ▲]

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See detailProbabilistic Models of Visual Appearance For Object Identity, Class, and Pose Inference
Teney, Damien ULg

Doctoral thesis (2013)

The topic of object recognition is a central challenge of computer vision. In addition to being studied as a scientific problem in its own right, it also counts many direct practical applications. We ... [more ▼]

The topic of object recognition is a central challenge of computer vision. In addition to being studied as a scientific problem in its own right, it also counts many direct practical applications. We specifically consider robotic applications involving the manipulation, and grasping of everyday objects, in the typical situations that would be encountered by personal service robots. Visual object recognition, in the large sense, is then paramount to provide a robot the sensing capabilities for scene understanding, the localization of objects of interests and the planning of actions such as the grasping of such objects. This thesis presents a number of methods that tackle the related tasks of object detection, localization, recognition, and pose estimation in 2D images, of both specific objects and of object categories. We aim at providing techniques that are the most generally applicable, by considering those different tasks as different sides of a same problem, and by not focusing on a specific type of image information or image features. We first address the use of 3D models of objects for continuous pose estimation. We represent an object by a constellation of points, corresponding to potentially observable features, which serve to define a continuous probability distribution of such features in 3D. This distribution can be projected onto the image plane, and the task of pose estimation is then to maximize its “match” with the test image. Applied to the use of edge segments as observable features, the method is capable of localizing and estimating the pose of non-textured objects, while the probabilistic formulation offers an elegant way of dealing with uncertainty in the definition of the models, which can be learned from observations — as opposed to being available as hand-made CAD models. We also propose a method, framed in a similar probabilistic formulation, in order to obtain, or reconstruct such 3D models, using multiple calibrated views of the object of interest. A larger part of this thesis is then interested in exemplar-based recognition methods, using directly 2D example images for training, without any explicit 3D information. The appearance of objects is also defined as probability distributions of observable features, defined in a nonparametric manner through kernel density estimation, using image features from multiple training examples as supporting particles. The task of object localization is cast as the cross-correlation of distributions of features of the model and of the test image, which we efficiently solve through a voting-based algorithm. We then propose several techniques to perform continuous pose estimation, yielding a precision well beyond a mere classification among the discrete, trained viewpoints. One of the proposed method in this regard consists in a generative model of appearance, capable of interpolating the appearance of learned objects (or object categories), which then allows optimizing explicitly for the pose of the object in the test image. Our model of appearance, initially defined in general terms, is applied to the use of edge segments and of intensity gradients as image features. We are particularly interested in the use of gradients extracted at a coarse scale, and defined densely across images, as they can effectively represent shape as they capture the shading onto smooth non-textured surfaces. This allows handling some cases, common in robotic applications, of objects of primitive shapes with little texture and few discriminative details, which are challenging to recognize with most existing methods. The proposed contributions, which all integrate seamlessly in a same coherent framework, proved successful on a number of tasks and datasets. Most interestingly, we obtain performance on well-studied tasks of localization in clutter and pose estimation, well above baseline methods, often on par with or superior to state-of-the-art method individually designed for each of those specific tasks, whereas the proposed framework is similarly applied to a wide range of problems. [less ▲]

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See detailEtude ab-initio d’oxydes antiferroélectriques de structure pérovskite
Amisi, Safari ULg

Doctoral thesis (2013)

In this thesis we present an original ab-initio study of the evolution of antiferrodistortive (AFD), anti-polar electric (APE), and ferroelectric (FE) instabilities in various ABO3 oxides of perovskite ... [more ▼]

In this thesis we present an original ab-initio study of the evolution of antiferrodistortive (AFD), anti-polar electric (APE), and ferroelectric (FE) instabilities in various ABO3 oxides of perovskite structure, as well as their structural and dynamic properties. The main goal is to understand better the microscopic origin of the antiferroelectricity exhibited in these compounds. Three prototypical compounds are studied in detail : PbZrO3 , NaNbO3 , and SrZrO3. After a general introduction on ABO3 compounds, and the ab-initio techniques, we review the concept of antiferroelectricity in perovskites, highlighting some ambiguities in the usual definition and the necessity of turning to what we call a modern definition of antiferroelectricity. First, we highlight that it is the rigidity of the oxygen cage that tends to favor the FE distortion compared to the APE instability. Although illustrated on BaTiO3 , this argument is general, and confirmed by the inspection of the phonons dispersion curves of the ABO3 compounds in whom the strongest instability of the FE/APE branch is systematically at Γ. We show that the emergence of a stable or meta-stable APE distortion appear naturally through a coupling with other instabilities. The presence of AFD modes turns out to be a concrete way to create mixed FE/AFD and APE/AFD phases, crucial for the emergence of antiferroelectricity (AFE). This clarifies why the known AFE compounds systematically include AFD distortions. In this context, since the FE, APE and AFD instabilities are usually in competition, the coexistence of FE, APE and AFD instabilities of strong amplitudes seems required to create mixed phases combining them. This establishes the context convenient to the development of FE and AFE metastable phases close in energy. Another important element concerns the need of a first order AFE-FE transition under electric field producing a double hysteresis loop, typical of AFE compounds. Here also the AFD modes could play a key-role by allowing the emergence of FE/AFD and APE/AFD phases close in energy and developing distinct tilt patterns. These various elements give a new perspective on AFE and allow us to have a more precise idea of the origin of the AFE behavior in perovskites. We identify some key intrinsic characteristics allowing the prediction of materials with the propensity of developing an AFE behavior. [less ▲]

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See detailVALORISATION INDUSTRIELLE ET ARTISANALE DES ARGILES DU MAROC
El Ouahabi, Meriam ULg

Doctoral thesis (2013)

Dans une perspective de développement local durable, la présente étude est focalisée sur la caractérisation des matériaux argileux du Nord du Maroc en vue de leur valorisation dans le secteur de la ... [more ▼]

Dans une perspective de développement local durable, la présente étude est focalisée sur la caractérisation des matériaux argileux du Nord du Maroc en vue de leur valorisation dans le secteur de la céramique. Elle a l’avantage de contribuer à la promotion des matériaux locaux de construction tout en améliorant la qualité des céramiques artisanales produites. Les sédiments utilisés dans cette étude proviennent de la région du nord du Maroc (Tétouan, Tanger et Meknès), ainsi que de sites argileux utilisés à l’échelle nationale dans la fabrication de la céramique traditionnelle, à savoir les sites de Fès, Salé et Safi. Dans le cadre de ce travail, nous avons procédé à une caractérisation minéralogique, granulométrique, texturale, physique, chimique, thermique et technologiques de ces argiles afin d’évaluer leurs potentialités en industrie céramique. Les argiles de Tétouan et Tanger sont caractérisées par des assemblages minéralogiques diversifiés (en particulier une proportion variable d'argile, de quartz et de calcite). En particulier, les argiles de Meknès, Fès, Salé et Safi présentent une forte teneur en argile, en quartz et en calcite. La fraction argileuse des échantillons de Tétouan et Tanger est dominée par l'illite et la kaolinite avec des proportions variables de chlorite. Ces trois types de minéraux argileux sont responsables en grande partie des propriétés céramiques favorables des échantillons d’argiles étudiées. Les matériaux argileux étudiés sont généralement constitués de fines particules d'argiles avec une plasticité moyenne à forte et une faible teneur en matière organique. Ces échantillons sont composés essentiellement de SiO2 (35 - 60 %), Al2O3 (7 - 30 %) et Fe2O3 (10 - 22 %). La quantité de CaO dans les argiles de Tanger et Meknès est très variable (0 - 30 %). Le CaO n’est présent que dans certaines argiles de Tétouan. Le taux de Fe2O3 est variable allant de 0 à 22 %. Les autres oxydes représentent de faibles proportions (< 6 %). La capacité d’échange cationique et la surface spécifique de tous les échantillons sont faibles. La masse volumique apparente, le volume poreux et le nombre de micropores sont peu variables pour toutes les argiles. Les argiles de Tétouan et de Meknès montrent globalement un bon comportement au séchage, à l’exception de quelques échantillons qui montrent des fissures superficielles au séchage due à la présence des argiles gonflantes (smectite et vermiculite). Les argiles de Tétouan et de Meknès constituent des ressources minérales industrielles de bonne qualité pour la fabrication des produits variés dont des carreaux de sol, des briques et les tuiles. Afin d’avoir de bon produit fini, ces argiles doivent êtres cuites à des températures supérieur à 1050 °C. Les argiles de Tanger montrent des propriétés conformes avec les critères de production des briques. Néanmoins, la présence de sulfates en faible quantité dans quelques échantillons carbonatés conduit après cuisson à 1000 °C à la formation de nodules blancs de sulfate de calcium (CaSO4) à la surface de la brique, résultant de la réaction de sulfates avec le CaO. Néanmoins, quelques produits cuits ont présenté un retrait à la cuisson supérieur à 10% pour de températures allant de 1100 à 1150°C et une perte en poids à la cuisson supérieur à 10%. Pour une bonne rentabilité industrielle, ces retraits peuvent être minimisés par l’ajout d’une quantité optimale de dégraissant ou en faisant des mélanges et/ ou des formulations avec d’autres argiles proche géographiquement afin d’obtenir un mélange adéquat. [less ▲]

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See detailSmart drug delivery systems based on specifically-designed macromolecules and inorganic colloids
Liu, Ji ULg

Doctoral thesis (2013)

In the past few decades, various hybrid nano-vehicles have been developed as new drug delivery systems (DDS), in which inorganic and organic components are integrated within a nano-object. An ideal DDS ... [more ▼]

In the past few decades, various hybrid nano-vehicles have been developed as new drug delivery systems (DDS), in which inorganic and organic components are integrated within a nano-object. An ideal DDS should satisfy the conflicting requirements for high stability in extracellular fluid, so that it maintains its integrity during the in vivo circulation; however, it becomes labile upon the activation of internal or external stimuli after targeting to the disease sites, allowing the triggered release of therapeutic agents. The aim of this thesis was to build different hybrid nano-vehicles, explore the possibility to manipulate the release behaviors and evaluate their potential biomedical application. The first part presents an original work on reversibly-crosslinked nanogels based on poly(vinyl alcohol)-b-poly (Nvinylcaprolactam) copolymers. The second part is devoted to stimuli-responsive hybrid nanovehicles, composed of inorganic cores, e.g. maghemite nanoparticles or gold nanorods, and a stimuli-responsive polymer corona, e.g. poly(vinyl alcohol)-b-poly(acrylic acid) or poly(ethyl glycol)-b-poly(N-vinylcaprolactam). The third part focuses on core-shell nanoparticles made of a maghemite core and a mesoporous silica shell, while phase-changed molecules, e.g. 1-tetradecanol with melting temperature of 39 °C, were introduced as gatekeepers to regulate the release behaviors. These different nanostructures were developed as DDS to accommodate cargo molecules, and the triggered cargo release upon variation in pH or temperature, activation of reductive agent or presence of glucose was explored. Moreover, remote stimuli, e.g. alternating magnetic field or near infrared light, were also applied to trigger the release. Studies on cytotoxicity, cellular uptake and in vitro triggered release with cell culture are also described. [less ▲]

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See detailEcologie, dynamique des populations et intérêts économiques du noisetier d'Afrique (Coula edulis Baill.) au Gabon
Moupela, Christian ULg

Doctoral thesis (2013)

Le noisetier d’Afrique (Coula edulis Baill. Olacaceae) est une espèce à usages multiples des forêts denses humides africaines. Elle produit des graines d’une grande valeur nutritive qui sont régulièrement ... [more ▼]

Le noisetier d’Afrique (Coula edulis Baill. Olacaceae) est une espèce à usages multiples des forêts denses humides africaines. Elle produit des graines d’une grande valeur nutritive qui sont régulièrement collectées et commercialisées par les populations locales. Cependant, la valorisation et la domestication de ce produit forestier non ligneux (PFNL) est entravée faute de connaissances précises sur ses caractères reproductifs, son potentiel de production, ses mécanismes de régénération, et les perspectives de développement d'un marché commercial local pour ce produit. Une étude dédiée à cette espèce a donc été entreprise. L’objectif visé était d’améliorer les connaissances sur cette espèce afin de promouvoir sa place dans les systèmes agroforestiers et fournir des informations permettant d'assurer la conservation in situ de la ressource. Les résultats de l'étude montrent que C. edulis est utilisé selon une stratégie de subsistance par les populations, avant tout pour leur autoconsommation et éventuellement pour un revenu qui reste marginal. La reproduction de l'espèce est annuelle, garantissant une disponibilité régulière des fruits. Le diamètre minimum de floraison est de 10,6 cm tandis que le diamètre de fructification régulière est de 23 cm. L’accroissement annuel moyen de l’espèce est de 0,22 cm/an, une valeur similaire à celles observées chez d'autres arbres du sous-bois. La production fruitière est fortement liée au diamètre des tiges et varie d’une année à l’autre. En forêt naturelle, la dissémination de l'espèce est potentiellement assurée par sept espèces frugivores, le principal étant le potamochère, Potamochoerus porcus. Des rongeurs fouisseurs pourraient également jouer un rôle non négligeable dans la dispersion de C. edulis. Par contre, l'éléphant qui était soupçonné de contribuer significativement à la dispersion de l'espèce s'avère n'être qu'un disperseur anecdotique, voire nul. En matière de domestication, les stratégies ne devront pas être basées sur le semis, la germination de C. edulis étant très lente et échelonnée sur plusieurs années, avec des taux de levée très faibles. En revanche, le marcottage aérien a été un succès relatif sur cette espèce et présente l'avantage de maintenir le potentiel génétique de l'arbre multiplié. Les implications de ces résultats aussi bien en termes de gestion durable des peuplements naturels que de domestication de l'espèce dans un contexte agroforestier sont détaillés dans le document. Si l’on désire que les PFNL d’intérêt local comme C. edulis participent substantiellement au développement en milieu rural gabonais, il est essentiel d’orienter ces ressources à la fois dans une stratégie de gestion durable par leur domestication et leur intégration dans le cycle agricole et dans une stratégie de revenu supplémentaire où l’exploitation répond à une demande marchande. [less ▲]

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See detailCONTRIBUTION A LA CARTOGRAPHIE, PAR ETUDES DE LIAISON ET D’ASSOCIATION, DE LOCI D’INTERET CHEZ LES ANIMAUX DOMESTIQUES.
Zhang, Zhiyan ULg

Doctoral thesis (2013)

Until recently, breeding values were estimated based on phenotypes measured on the individual and its relatives, and the notion that the covariance between breeding values is proportionate to the kinship ... [more ▼]

Until recently, breeding values were estimated based on phenotypes measured on the individual and its relatives, and the notion that the covariance between breeding values is proportionate to the kinship coefficient. Advances in genomics now allow for direct analysis of the genome and identification of the loci that determine the breeding values of individuals. As a consequence, marker assisted selection and genomic selection have become more effective and are replacing conventional selection. The identification of loci influencing the traits of interest requires the use of advanced statistical methods that are constantly evolving. In the context of this thesis, we have (i) contributed to the development of gene mapping methods, (ii) applied these methods to map loci influencing both metric and meristic traits, and (iii) contributed to the development of methods for the integration of genomic information in livestock breeding and management. The mapping methods that we have helped developing distinguish themselves mainly by the fact that (i) they exploit haplotype information (by means of a hidden markov model) which should increase the linkage disequilibrium with causative variants and hence detection power, (ii) they can simultaneously extract linkage information within families, and linkage disequilibrium information across the population, and (iii) they correct for population stratification by means of a random polygenic effect, and (iv) they can be applied to binary as well as quantitative traits. We have applied these and other methods to map loci influencing (i) quantitative hematological parameters in a porcine line-cross, and (ii) binary traits including diseases in bovine and non-syntenic Copy Number Variants in cattle, horse and human. In fine, we have contributed to the development of methods for the utilization of marker information in animal selection and production. We have extended the haplotype-based mapping method to allow imputation and have evaluated the utility of this approach in scenarios mimicking reality. We have also contributed to the development of a method to quantify somatic cell counts in the milk of individual cows by genotyping a sample of milk from the farm’s tank (hence a mixture of milk from all cows on the farm) Our work has resulted in the development of a software package (“GLASCOW”) that is increasingly used by the community to map genes influencing complex traits, primarily binary. By using this tool, we have contributed to the localization of several trait loci in pig, cattle, horse and human. We have contributed to the development of approaches that reduce the costs of genomic analyses in livestock by, on the one hand, complementing real SNP genotypes with genotypes obtained in silico by means imputation, and, on the other hand, by developing a method to deconvolute genotypes obtained on DNA pools. [less ▲]

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See detailA walk into random forests: adaptation and application to Genome-Wide Association Studies
Botta, Vincent ULg

Doctoral thesis (2013)

Understanding underlying mechanisms of common diseases is one of the major goals of current research in medicine. As most of these disorders are linked to genetic factors, identification of the associated ... [more ▼]

Understanding underlying mechanisms of common diseases is one of the major goals of current research in medicine. As most of these disorders are linked to genetic factors, identification of the associated variants forms an excellent strategy towards the elucidation of molecular and cellular dysfunctions, and in fine could lead to better personalised diagnostics and treatments. Genome-Wide Association Studies (GWAS) aim to discover variants spread over the genome that could lead, in isolation or in combination, to a particular trait or an unfortunate phenotype such as a disease. The basic idea behind these studies is to statistically analyse the genetic differences between groups of healthy (controls) and diseased (cases) individuals. Advances in genetic marker technology indeed allow for dense genotyping of hundreds of thousands of Single Nucleotide Polymorphisms (SNPs) per individual. This allows to characterise representative samples composed of several hundreds to several thousands of cases and controls, each one characterised by up to a million of genetic markers sampling the genomic variations among these individuals. The standard approach to genome wide association studies is based on univariate hypothesis tests. In this approach each genetic marker is analysed in isolation from the others, in order to assess its potential association with the studied phenotype, in practice by the computation of so-called p-values based on some statistical assumptions about the data-generation mechanism. Because of the very high ratio between the large number of SNPs genotyped and the limited number of individuals, multiple-testing corrections need to be applied when carrying out these analyses, leading to reduced statistical power. While this standard approach has been at the basis of many novel loci unravelled in the last years for several complex diseases, it has several intrinsic limitations. A first limitation is that this approach does not directly account for correlations among the explanatory variables. A second intrinsic limitation of GWAS is that they can't account for genetic interactions, i.e. causal effects that are only observed when specific combinations of mutations and/or non-mutations are present at the same time. The third limitation of univariate approaches is that they do not directly allow to assess the genetic risk, since many of the identified markers (with similarly small p-values) actually account for the same underlying causal factor: exploiting their information to predict the genetic risk is hence far from straightforward. Within bioinformatics, machine learning has actually become one of the major potential sources of progress. As a matter of fact, biology has become nowadays one of the main drivers of research in machine learning, and is by itself already a very competitive research field. Among the subfields of machine learning, supervised learning and its extensions such as semi-supervised learning, stand out as the most mature and at the same time most rapidly evolving area of research. Within this context, the purpose of this thesis was to study the application of random forest types of methods to genome wide association studies, with the twofold goal of (i) inferring predictive models able to asses disease risk and (ii) to identify causal mutations explaining the phenotype. The choice of this family of methods was originally motivated by the fact that these methods are a priori well suited for that kind of analysis due to some of their interesting properties. They are indeed able to deal efficiently with very large amounts of data without relying on strong assumptions about the underlying mechanisms linking genetic and environmental factors to phenotypes, and they can also provide interpretable information, in the form of scorings and/or rankings of SNPs so as to help in the identification of causal genetic loci. In the first part of this manuscript, we analyse the state-of-the art in the application field of genome wide association studies and in supervised machine learning, and subsequently describe in details the three tree-based ensemble methods that we have implemented and applied in our research; in Part II, we report our empirical investigations, in three successive steps, namely i.) a preliminary study on simulated datasets yielding controlled conditions with known ground-truth and allowing for a first sanity check of the T-Trees methods, in ideal conditions; ii.) a detailed study on a given real-life dataset concerning Crohn's disease, where we try to understand the main features of the three different algorithms in terms of predictive accuracy and capability of identification of relevant genetic information, and their sensitivity with respect to various kinds of quality control procedures and algorithmic parameters; iii.) a systematic replication study, where we confirm, on 7 different datasets from the Wellcome Trust Case Control Consortium, the main outcomes of our study on the Crohn's disease, while using default parameter settings. 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See detailLarge scale phylogenetic patterns of diversification in Bryophytes
Laenen, Benjamin ULg

Doctoral thesis (2013)

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See detailVers une gestion rationnelle de l'eau dans une situation complexe d'urbanisation anarchique dans un pays en développement : cas du bassin versant de l'Abiergué (Yaoundé-Cameroun)
Kouam Kenmogne, Guy Romain ULg

Doctoral thesis (2013)

This study focuses on an analysis of water resource management in cities of developing countries with very rapid rates of urbanization. The objectives are twofold: firstly, to highlight the factors which ... [more ▼]

This study focuses on an analysis of water resource management in cities of developing countries with very rapid rates of urbanization. The objectives are twofold: firstly, to highlight the factors which caused and which govern poor water resources management these cities and secondly to develop a coherent sustainable urban water resources management strategy. The study was conducted in the Abiergue watershed in Yaoundé-Cameroon. The methodology used is based on holistic and participative approaches resulting from the combination of principles of "Integrated Water Resources Management-IWRM" and "Ecosystem and Human Health-ECOHEALTH". Political, economic, social, environmental, historical and mesological factors have resulted in a water resources management system marked by many inadequacies and constraints. Poor access to drinking water and sanitation, recurrent flooding, endemic waterborne diseases, water pollution etc are all permanent pressures that contribute to the impoverishment of households and hamper the development of the area in particular and that of the town of Yaoundé in general. The poor water resources management in the Abiergué watershed is an indicator of an urban governance crisis. Three scenarios to improve this situation were developed: maintaining the status quo; destruction of buildings and a scenario based on IWRM and ECOHEALTH. The optimal strategy integrates principles from IWRM and ECOHEALTH with the base scenario 3.4 focused on actors. Using a sequential process, it takes into account actions on water resources, health and reforms on the legislative, regulatory and institutional framework. Many constraints like land tenure, corruption, limited financial resources and poor urban governance may undermine the implementation of this strategy despite the potential of the watershed. All indicators suggest that water resources management in the Abiergue watershed is poor. There is therefore an urgency to implement this strategy within the framework of the ongoing IWRM process in Cameroon. "Time for Solutions", the theme of the 6th World Water Forum held in Marseille in 2012 is fully translated into action through this study. [less ▲]

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See detailL’Arganeraie des Haha : droits réels, inégalités d’accès aux ressources naturelles et principales dynamiques (Sud Ouest du Maroc)
Bejbouji, Jihane ULg

Doctoral thesis (2013)

Véritable spécificité du Sud-Ouest marocain, l’arganeraie est l’ensemble des écosystèmes dont l’espèce caractéristique est l’arganier, relique de la végétation subtropicale de l’ère tertiaire. Outre son ... [more ▼]

Véritable spécificité du Sud-Ouest marocain, l’arganeraie est l’ensemble des écosystèmes dont l’espèce caractéristique est l’arganier, relique de la végétation subtropicale de l’ère tertiaire. Outre son originalité historique et géographique, l’arganeraie assure de multiples fonctions écologiques et procure de nombreux biens à une population pauvre et vivant dans des conditions précaires. Toutefois, cet espace intrigue. Alors que dans les autres forêts marocaines, les riverains ne disposent que de deux droits (la récolte de bois mort gisant et le parcours), la population de l’arganeraie bénéficie depuis 1925 d’une législation spéciale lui assurant une large gamme d’utilisations et d’exploitations des ressources forestières. Cette thèse, menée dans l’arganeraie des Haha (province d’Essaouira) se propose de contribuer à la gestion durable d’un territoire partagé dans un contexte caractérisé par de nombreuses mutations. Pour appréhender les évolutions de cet éco-socio-système, nous avons privilégié une entrée par l’étude des droits réels, d’accès et d’usage, en accordant une attention particulière aux inégalités qui les caractérisent. Nous nous sommes fixé trois objectifs : identifier les modes de gestion, analyser les dynamiques actuelles des usages et pratiques dans ces écosystèmes à arganier et proposer des scénarios de gestion. Pour ce faire, nous avons mené une enquête qualitative et quantitative auprès de 100 ménages au niveau de trois communes rurales, Smimou, Ida ou Azza et Imgrade, situées autour du massif du Jbel Amsitten, l’une des zones centrales de la Réserve de Biosphère de l’arganier. Notre travail de recherche a d’abord dressé le portrait actuel de l’espace et de l’ensemble des droits qui le régissent. Il montre que leur appropriation s’est faite progressivement par une population en majorité issue d’un brassage récent d’émigrants provenant du sud. Il en résulte une trame de droits récemment forgée et très diversifiée. Ensuite, en partant des représentations que se font les populations de leur patrimoine, nous avons identifié trois grands types de propriétaires se comportant selon des logiques différentes : d’abord des ménages, qui sont les plus nombreux, dont les ressources sont rares ou limitées et qui cherchent avant tout à survivre. Ensuite des ménages dont les ressources sont modérées et qui développent une logique de gestionnaire et finalement, quelques ménages dont les ressources sont importantes et qui poursuivent une logique d’entrepreneur. Par ailleurs, l’étude du compartiment agdal, son concept, ses configurations sociales et spatiales et ses types de gestion a montré l’évolution d’une pratique de mise en défens à celle d’un terroir se révélant comme un agrégat de droits. Et contrairement à ce qu’on croit, la détention de l’agdal ne concerne pas toute la population, mais elle semble plutôt liée à la disponibilité des ressources aux différentes périodes d’arrivée des ménages immigrants. Quant à sa gestion, deux types ont été identifiés : individuel et commun. En ayant recours à une étude monographique, nous avons alors montré que la gestion de cet espace-ressources est complexe. Elle résulte à la fois de l’histoire de l’appropriation des droits, de la délimitation forestière et des stratégies de gestion intergénérationnelle individuelles et collectives adoptées par la population pour mettre en valeur ces ressources. Enfin, moyennant la systémique, nous avons identifié quatre principales dynamiques qui traversent ce système : une dynamique de déprise, de maintien/résistance, de marché et de projet. Ce travail de recherche a mis en lumière le fait que l’arganeraie n’est pas un tout, approprié par un groupe homogène, mais qu’elle renvoie plutôt à un ensemble d’éléments en osmose : une population diversifiée, des patrimoines inégaux et des rapports au territoire variés. Par ailleurs, les formes de gestion en commun dans cet espace déclinent tandis que la tendance à la gestion privée se renforce. La prise en compte de cette complexité, des inégalités d’accès aux ressources naturelles, des stratégies anticipatives adoptées par la population et de la diversité des compartiments et des pratiques, s’avère nécessaire pour la réussite de tout projet d’aménagement, mais aussi pour la durabilité de l’approvisionnement en fruits. C’est ainsi que nous avons construit trois scénarios de gestion qui sont, à notre avis, les plus plausibles : un scénario tendanciel ou de statu quo, un scénario optimiste ou de gestion partagée entre l’Etat et les communautés et un scénario modéré ou de gestion privée. La gestion patrimoniale et intégrée de l’arganeraie serait en mesure de contribuer à sa gestion durable. Renouer avec le corpus de règles qu’entretenait la population avec cet espace-ressources peut être, à notre avis, une des principales portes d’entrée de sa conservation. [less ▲]

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See detailUse of Bacillus subtilis starter cultures during red sorghum malting
Bwanganga Tawaba, Jean-Claude ULg

Doctoral thesis (2013)

Bacillus subtilis was used to inhibit mould growth during red sorghum malting. Improved conditions for achieving good malt properties were studied and mathematical models are proposed for the induction ... [more ▼]

Bacillus subtilis was used to inhibit mould growth during red sorghum malting. Improved conditions for achieving good malt properties were studied and mathematical models are proposed for the induction and the repression phases of α- and β-amylase synthesis. The problems associated with the hydrolysis of β-glucans and the biocontrol steeping effect on β-glucanase activities are discussed. The effect of the biocontrol treatment and that of phytohormones produced by the bacterial strain used on the synthesis of specific red sorghum enzymes are elucidated. Gibberellic acid and abscisic acid diffusion and cross-talk as factors affecting the synthesis of red sorghum malt α- and β-amylase activities are also discussed. The production of 3-indole acetic acid (IAA) by B. subtilis S499 was also a focus in this study and the determination of the conditions for improving the production of indole-3-acetic acid are determined. [less ▲]

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See detailEffet de l'effort, l'entrainement et l'inflammation sur l'immunité innée des voies respiratoires profondes du Trotteur Français
Waldschmidt, Ingrid ULg

Doctoral thesis (2013)

Ce manuscrit rapporte dans un premier temps, l'élaboration du protocole expérimental de stimulation des TLR des macrophages alvéolaires équins ex vivo. Dans un second temps, l'effet de l'exercice et l ... [more ▼]

Ce manuscrit rapporte dans un premier temps, l'élaboration du protocole expérimental de stimulation des TLR des macrophages alvéolaires équins ex vivo. Dans un second temps, l'effet de l'exercice et l'entrainement sur la réponse des macrophages alvéolaires équins en conditions standardisées d'entrainement. Enfin, dans un troisième temps, l'impact de l'inflammation pulmonaire sur la réponse des macrophages alvéolaires ex vivo de chevaux de course atteints d'IAD, en conditions de terrain. [less ▲]

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See detailAnalyse critique de l'économie politique de l'utilisation des ''enfants-soldats''. Etude de cas des pays du fleuve Mano (Liebria, Sierra Léone, Côte d'Ivoire)
Zina, Seydina Ousmane ULg

Doctoral thesis (2013)

Notre thèse a consisté à construire analytiquement le cadre de pensée de la rationalité économique et à le discuter au regard de la littérature et des cas des pays du fleuve Mano (Libéria, Sierra Léone ... [more ▼]

Notre thèse a consisté à construire analytiquement le cadre de pensée de la rationalité économique et à le discuter au regard de la littérature et des cas des pays du fleuve Mano (Libéria, Sierra Léone, Côte d’Ivoire). Et elle a retenu que les variables de l’approche économique (nombre élevé de jeunes, faible niveau d’éducation, faible revenu et pillage des ressources naturelles) sont contrairement à leur fonction utilitariste, des répertoires d’action mobilisés par les jeunes et les groupes armés dans le cadre du ‘’marché de la violence’’. Cette approche de la violence remet le comportement économique du jeune au cœur des contextes socio-économiques, politiques et culturels du conflit armé, et limite l’hypothèse du choix rationnel. [less ▲]

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See detailDynamics of Agrarian Systems in Hai Duong Province, North Vietnam
Han Quang, Hanh ULg

Doctoral thesis (2013)

In Vietnam, the agrarian systems have evolved considerably during the socio-economic transformation period initiated in the late 1980s with the political reform (Doi Moi). In a region around the capital ... [more ▼]

In Vietnam, the agrarian systems have evolved considerably during the socio-economic transformation period initiated in the late 1980s with the political reform (Doi Moi). In a region around the capital, where the process of industrialization, urbanization, and international integration has been accelerating, a number of questions about the sustainability of agrarian systems are raising. By diagnosing and analysing the dynamics of agrarian systems from 1980 to 2010, this study aims to provide decision-makers with some sectorial and territorial policy options authorizing the sustainable development of agriculture and rural society in the new socio-economic context. Combining the historical, adaptive, and systematic approaches, this study shows that farmers in Hai Duong province adapted effectively to the socio-economic and institutional changes, notably by transforming part of the rice land areas into other agricultural land use purposes such as fish ponds, animal buildings, vegetable fields and fruit orchards. These rapid changes, however, do not go in the direction of improving the sustainability of agrarian systems. Farm holders are now facing with many technical and economic contradictions whereas land issues are not only related to the agricultural purposes. Competition functions in land use, fragmentation of plots, the imperfection of the land market and rising property values are all emerging. The prospects for sustainability of agrarian systems are analysed under different scenarios which highlight the complexity of policy options. The recommendations are made not only for the agricultural sector in general, but also for different agrarian systems in specific regions. [less ▲]

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See detailL'impact des politiques internationales de financement du développement sur les marges de manoeuvre politiques (policy space) des pays en développement. Une étude selon la grille d'analyse centre/périphérie
Zacharie, Arnaud ULg

Doctoral thesis (2013)

La thèse de ce travail est que dans le contexte du processus contemporain de globalisation, le système international du financement du développement a renforcé les contraintes de jure et de facto qui ... [more ▼]

La thèse de ce travail est que dans le contexte du processus contemporain de globalisation, le système international du financement du développement a renforcé les contraintes de jure et de facto qui pèsent sur l’autonomie des politiques économiques des pays en développement, mais qu’il offre également de nouvelles opportunités en transformant la géographie de la production mondiale et des flux économiques et financiers qui en découlent. Notre hypothèse est dès lors que l’impact des politiques internationales de financement du développement sur les marges de manœuvre politiques des pays en développement n’a pas été uniforme et que ce sont précisément les pays qui ont réussi à assurer un équilibre entre les contraintes du système international et leur autonomie politico-économique qui ont réussi à tirer profit de ce système et à entamer un processus de convergence économique avec les pays du centre. [less ▲]

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See detailSimulations numériques de la dynamique d’épidémies sur réseaux aléatoires selon une approche de physique statistique
Ababou, Malika ULg

Doctoral thesis (2013)

Dans le présent manuscrit, notre travail est focalisé dans un premier temps, sur l’étude de la dynamique de propagation des épidémies sur un modèle de réseaux complexes qui est une variante du modèle de ... [more ▼]

Dans le présent manuscrit, notre travail est focalisé dans un premier temps, sur l’étude de la dynamique de propagation des épidémies sur un modèle de réseaux complexes qui est une variante du modèle de Barabási-Albert (BA). Les simulations numériques révèlent une transition d’une loi exponentielle à une loi de puissance de la distribution du nombre de liens par nœud en fonction du paramètre de précision ω. Nous avons prouvé aussi que la synchronisation collective σ induite par le processus épidémiologique Susceptible-Infected-Recovered-Susceptible (SIRS ) dépend de la structure topologique du réseau. Dans un second temps, nous nous intéressons à l’étude numérique de ce modèle épidémique en introduisant une source permanente d’infection I_0, afin d’éviter la disparition de la maladie, sur un réseau exponentiel généré par le modèle (BA) d’attachement préférentiel à précision finie. Les simulations montrent que la valeur moyenne de la fraction des personnes infectées dépend de la période naturelle du cycle d’infection τ_0 et du temps d’infection τ_I . Un maximum de synchronisation des personnes infectées est atteint lorsque le rapport τ_I /τ_0 est légèrement plus petit que 1/2. Un autre résultat important est la dépendance linéaire de la valeur moyenne de la fraction d’éléments infectés ⟨n_inf ⟩ en fonction de τ_I /τ_0 bien que, la synchronisation est une fonction non triviale de τ_I /τ_0. [less ▲]

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See detailConstruction of an interactomic map of Ets factors and identification of new functions in mRNA processing
Rambout, Xavier ULg

Doctoral thesis (2013)

The family of Ets factors is one of the largest families of human transcription factors. This thesis aimed at molecularly and biologically defining these well known though not well-understood ... [more ▼]

The family of Ets factors is one of the largest families of human transcription factors. This thesis aimed at molecularly and biologically defining these well known though not well-understood transcription factors using a system biology approach. Combination of interactomic and bioinformatics tools gave rise to the first interactome of the human Ets factors built on more than 400 interactions with nearly 300 interaction partners. We fragmented our interactome in 24 functional highly intraconnected sub-networks (clusters, or CL) and highlighted a new role for Ets transcription factors in mRNA processing (CL1). Steady-state levels of mRNAs result from the balance between transcription and mRNA decay, two events sitting at both ends of the mRNA life. In the traditional and still prominent view, these events are spatially, functionally and temporally independent. Here, we showed that the Erg subfamily of Ets factors (composed of the three members ERG, FLI1, and FEV) regulate mRNA decay of specific targets via promoter-mediated mRNA imprinting with sequence-specific RNA-binding proteins (CL1) and the CCR4-NOT deadenylation complex. This constitutes the first evidence, regardless of the organism, that DNA-binding transcription factors recruit RNA-binding proteins and mRNA decay components to control the degradation of specific mRNAs. This is also the most detailed demonstration of a functional coupling between transcription and mRNA decay machineries in humans. We showed that ERG promoted mRNA decay of key mitotic regulators, among which the Aurora kinases Aurora A and B. Depletion of ERG prevented degradation of Aurora A and B mRNAs during mitosis, leading to aberrant levels of Aurora proteins, accumulation of centrosome and mitotic spindle defects, and ultimately mitosis blockage. This consists in a significant advance in understanding of mitosis progression that was until now thought to be exclusively regulated by post-translational modifications and proteasomal degradation of proteins. Our results show that, in the contrary of bulk mRNAs whose decay is inhibited during mitosis, degradation of specific transcripts is a prerequisite for normal mitosis progression. [less ▲]

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See detailFirst-principles study of ferroelectricity in oxide superlattices
Zhao, Jinzhu ULg

Doctoral thesis (2013)

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See detailDesign, performance analysis, and implementation of a positioning system for autonomous mobile robots
Pierlot, Vincent ULg

Doctoral thesis (2013)

Positioning is a fundamental issue in mobile robot applications, and it can be achieved in multiple ways. Among these methods, triangulation based on angle measurements is widely used, robust, and ... [more ▼]

Positioning is a fundamental issue in mobile robot applications, and it can be achieved in multiple ways. Among these methods, triangulation based on angle measurements is widely used, robust, and flexible. In this thesis, we present an original beacon-based angle measurement system, an original triangulation algorithm, and a calibration method, which are parts of an absolute robot positioning system in the 2D plane. Also, we develop a theoretical model, useful for evaluating the performance of our system. In the first part, we present the hardware system, named BeAMS, which introduces several innovations. A simple infrared receiver is the main sensor for the angle measurements, and the beacons are common infrared LEDs emitting an On-Off Keying signal containing the beacon ID. Furthermore, the system does not require an additional synchronization channel between the beacons and the robot. BeAMS introduces a new mechanism to measure angles: it detects a beacon when it enters and leaves an angular window. This allows the sensor to analyze the temporal evolution of the received signal inside the angular window. In our case, this feature is used to code the beacon ID. Then, a theoretical framework for a thorough performance analysis of BeAMS is provided. We establish the upper bound of the variance and its exact evolution as a function of the angular window. Finally, we validate our theory by means of simulated and experimental results. The second part of the thesis is concerned with triangulation algorithms. Most triangulation algorithms proposed so far have major limitations. For example, some of them need a particular beacon ordering, have blind spots, or only work within the triangle defined by the three beacons. More reliable methods exist, but they have an increasing complexity or they require to handle certain spatial arrangements separately. Therefore, we have designed our own triangulation algorithm, named ToTal, that natively works in the whole plane, and for any beacon ordering. We also provide a comprehensive comparison between other algorithms, and benchmarks show that our algorithm is faster and simpler than similar algorithms. In addition to its inherent efficiency, our algorithm provides a useful and unique reliability measure, assessable anywhere in the plane, which can be used to identify pathological cases, or as a validation gate in data fusion algorithms. Finally, in the last part, we concentrate on the biases that affect the angle measurements. We show that there are four sources of errors (or biases) resulting in inaccuracies in the computed positions. Then, we establish a model of these errors, and we propose a complete calibration procedure in order to reduce the final bias. Based on the results obtained with our calibration setup, the angular RMS error of BeAMS has been evaluated to 0.4 deg without calibration, and to 0.27 deg, after the calibration procedure. Even for the uncalibrated hardware, BeAMS has a better performance than other prototypes found in the literature and, when the system is calibrated, BeAMS is close to state of the art commercial systems. [less ▲]

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