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See detailLe geste philosophique de Whitehead : éléments pour une lecture de Modes of Thought autour du concept de vie
Deroo, Emeline ULg

Doctoral thesis (2013)

L'objectif de ce travail se déploie en deux temps. Tout d'abord, il s'agit de mettre en évidence l'originalité de la conception de la vie telle que Whitehead la développe dans son dernier ouvrage, 'Modes ... [more ▼]

L'objectif de ce travail se déploie en deux temps. Tout d'abord, il s'agit de mettre en évidence l'originalité de la conception de la vie telle que Whitehead la développe dans son dernier ouvrage, 'Modes de pensée' (1938), et de révéler les enjeux que cette conception charrie par rapport aux ouvrages précédents de Whitehead. A cette fin, nous nous penchons sur des thématiques comme la dimension expressive de la vie, la relation entre ordre et nouveauté, le rôle du corps dans une théorie de l'expérience et de la perception. Dans un second temps, nous tentons de montrer que ces transformations conceptuelles relatives au thème de la vie dans l'oeuvre tardive de Whitehead sont indissociables d'une évolution dans la forme employée, c'est-à-dire d'un changement dans le type de discursivité utilisé. Plus précisément, nous tâchons de dégager la cohésion forte qui se noue entre les concepts et leur mise en oeuvre au fil du texte, de telle sorte que nous y découvrons l'auteur mettre ses thèses à l'épreuve de sa propre pensée. Cet objectif procède de l'idée qu'une pensée de l'individuation ne peut, pour garantir sa cohérence, être séparée d'un autre mouvement, qui est l'individuation de la pensée. En d'autres termes, la pensée whiteheadienne, qui place au centre de sa démarche les notions de processus et d'avancée créatrice, ne s'en tient pas à un discours programmatique mais se rend aussi capable d'intégrer les conséquences de cette démarche dans sa propre évolution, quel que soit le prix que ces remises en question impliquent vis-à-vis de sa pensée. Ainsi, nous espérons dégager une méthode permettant d'évaluer le cheminement philosophique de Whitehead dans ses dernières années d'écriture. [less ▲]

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See detailSurface tension and buoyancy in vertical soap films
Adami, Nicolas ULg

Doctoral thesis (2013)

This manuscrit presents our experimental works about maintained vertical soap films.

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See detailThe role of galectins in the vasculature
Heusschen, Roy ULg

Doctoral thesis (2013)

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See detailDesign and fabrication of a variable wall thickness two-stage scroll expander to be integrated in a micro-solar power plant
Dickes, Rémi ULg

Master's dissertation (2013)

Improving access to energy in developing countries without exacerbating climate change requires novel technical strategies. MicroCSP power plants using organic Rankine cycles (ORCs) are one example of a ... [more ▼]

Improving access to energy in developing countries without exacerbating climate change requires novel technical strategies. MicroCSP power plants using organic Rankine cycles (ORCs) are one example of a promising approach for meeting this challenge. Specifically, expander development has been identified as a critical component for enhancing the performances of small ORC units. The goal of this project is to develop an optimized two-stage scroll expander to be integrated in a MicroCSP power plant designed to supply remote, off-grid areas. The expansion requirements are firstly defined so as to meet production specifications. Then, employing a deterministic model and a selection process, optimal scroll geometries are chosen for both expansion stages. The deterministic model is executed with Matlab and accounts for the relevant physical phenomena i.e. radial and flank leakages, throttling losses at the intake and exhaust processes, friction between the two scrolls and mechanical losses in the different bearings. A performance enhancement of about 6\% of the isentropic efficiency is predicted in comparison with baseline practice. A CAD model of a single-stage prototype is developed in Solidworks following the main architectural features of a compliant HVAC scroll compressor. This CAD is updated and improved with the optimal scroll geometries and some parts are 3D printed to verify their mechanical assembly. Toolpaths to control CNC machines are generated using the CAM program HSMXpress and the parts constituting the expander prototype are manufactured in a machine shop. In conclusion, the properties of the enhanced scroll expander are evaluated in the context of a typical Micro-CSP plant. A simple steady state model in EES is developed to quantify how three parameters (T_ev, T_cond and eta_exp) influence the power plant overall sunlight to electricity conversion efficiency (a gain of 0.73% is predicted). This project underscores the importance of optimizing the expansion process and identifies further research pathways to progress towards this goal. [less ▲]

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See detailLes représentations linguistiques des étudiants Erasmus et la vision plurilingue européenne: normes, discours, apprentissages
Meunier, Deborah ULg

Doctoral thesis (2013)

Le plurilinguisme est devenu la pierre angulaire des politiques éducatives linguistiques promues par le Conseil de l’Europe, et les programmes de mobilité étudiante Erasmus constituent un terrain ... [more ▼]

Le plurilinguisme est devenu la pierre angulaire des politiques éducatives linguistiques promues par le Conseil de l’Europe, et les programmes de mobilité étudiante Erasmus constituent un terrain privilégié pour la mise en place d’une éducation plurilingue et pluriculturelle. La nouvelle « génération Erasmus » s’incarnerait dans une figure d’étudiant humaniste, responsable et conscient de son rôle dans la construction d’une Europe plus citoyenne, et le rapport aux langues de cet étudiant cosmopolite serait à la fois la fin et le moyen de son évolution. En effet, l’immersion linguistique et culturelle liée à la mobilité serait l’occasion de développer des attitudes plus tolérantes vis-à-vis des langues et des locuteurs dans leur diversité. Au-delà d’une « culture éducative européenne partagée » se pose ainsi la question de l’incidence réelle des programmes de mobilité sur les apprentissages linguistiques et les attitudes des étudiants face à la diversité. L’objectif de ce travail est d’interroger l’interaction entre les logiques institutionnelles européennes et les logiques individuelles des étudiants mobiles afin de nourrir la réflexion didactique. Pour ce faire, nous avons étudié d’une part les principes véhiculés par une sélection de textes européens et, d’autre part, les représentations que des étudiants Erasmus non francophones activent ou se forgent des langues et des pratiques langagières, à partir de praxis sociales et scolaires dans le cadre de leur séjour à Liège en Belgique francophone. Quelle(s) norme(s) ces discours (institutionnels et ordinaires) construisent-ils ? Quelles postures les acteurs de la mobilité étudiante adoptent-ils vis-à-vis des langues ? S’est également posée la question de l’évolution vs la fossilisation des contenus représentationnels à la suite de l’expérience Erasmus. Nos analyses montrent que les déplacements paradigmatiques importants occasionnés par le passage à une vision plurilingue nécessitent des déplacements représentationnels non négligeables et qui ne vont pas de soi, tant au niveau institutionnel qu’individuel. Les postures adoptées par les étudiants se situent entre d’une part, l’acceptation d’une pratique plurilingue et sa normalisation/légitimation (nécessaire pour en faire une compétence) et, d’autre part, la pression normative intrinsèque aux langues, particulièrement au français et à sa tradition puriste. Les ethnotypes et les sociotypes observés témoignent de postures variées et fluctuantes : tantôt puriste, tantôt instrumentaliste, ou encore plus relativiste à certains égards, en accord avec le développement d’une identification et d’une compétence plurilingues. Suite à ces analyses, nous proposons plusieurs déplacements conceptuels pour une didactique du plurilinguisme mieux adaptée au contexte Erasmus : déterminer et prendre en considération des représentations normatives des acteurs de la mobilité au lieu de prétendre les neutraliser ; rendre une place de choix aux savoirs afin que les étudiants valorisent leurs compétences et se sentent en mesure de répondre aux exigences normatives, notamment celles des discours universitaires ; valoriser, voire certifier une compétence spécifique que nous avons observée et nommée compétence (métalinguistique) corrective qui participerait d’une posture à la fois normative et pragmatique, conjuguant ainsi le souci de la langue pour elle-même et pour ce qu’elle permet. [less ▲]

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See detailLa qualité de vie au travail des professionnels prenant en charge des personnes déficientes intellectuelles vieillissantes
Clesse, Audrey ULg

Master's dissertation (2013)

Introduction : Dans la littérature, de nombreuses recherches se sont concentrées sur l’impact de la prise en charge d’un proche dément sur les aidants informels, en termes de conséquences néfastes sur ... [more ▼]

Introduction : Dans la littérature, de nombreuses recherches se sont concentrées sur l’impact de la prise en charge d’un proche dément sur les aidants informels, en termes de conséquences néfastes sur différentes composantes de leur qualité de vie (dépression, problèmes de santé, épuisement émotionnel, etc.). Ces résultats alarmants combinés à une récente prise de conscience du vieillissement de la population déficiente intellectuelle, en particulier porteuses d’une trisomie 21, nous mènent à un questionnement majeur concernant leur prise en charge par les professionnels. En considérant que ces derniers présentent un investissement émotionnel similaire aux aidants informels de patients Alzheimer, nous envisageons un vécu et un fonctionnement semblable en regard de la prise en charge. Hypothèses : Nous posons l’hypothèse qu’en fournissant aux aidants les moyens d’agir sur une nouvelle situation-problème par la transmission d’éléments pratiques et de connaissances théoriques, propices à une meilleure appréhension du processus de vieillissement, leur bien-être subjectif au travail en sera amélioré. Cette amélioration serait induite, entre autre, par (1) la mise en place de stratégies de résolution de problèmes plus efficientes, vers une prise en charge optimale, ainsi que (2) par la prise de conscience des effets néfastes des stéréotypes, pour faciliter leur déconstruction. Méthodologie : La personne trisomique étant particulièrement sujette au développement d’une démence de type Alzheimer et à des pathologies surajoutées en lien avec son processus de vieillissement, notre intérêt s’est porté sur une population de 13 professionnels prenant en charge des personnes trisomiques vieillissantes, issues d’un Service Résidentiel pour Adultes. Les participants ont été évalués avant et après le suivi d’une intervention théorico-pratique au sujet des vieillissements réussi et pathologique, et plus particulièrement des stéréotypes les concernant. Résultats : L’évaluation en deux temps a permis, d’une part, de rendre compte de la situation initiale des professionnels, à savoir un bien-être affectif élevé et un sentiment de compétence plus important envers les personnes trisomiques jeunes. L’utilisation de stratégies cognitives, la présence d’une « triple stigmatisation » de la personne déficiente intellectuelle vieillissante et des connaissances modérées sur la maladie d’Alzheimer sont également à mettre en lien avec les besoins et les attentes des professionnels, en termes de formation continuée sur le vieillissement. D’autre part, l’observation des changements entre le T0 et le T1 a permis d’apprécier l’impact de notre intervention sur le bien-être subjectif des professionnels, en lien avec les nouvelles connaissances assimilées. Conclusion : En regard de nos résultats, à mettre en lien avec la littérature de comparaison, nous envisageons un besoin urgent de développer la recherche sur cette thématique, afin de déployer des interventions efficaces ayant pour objectif de soutenir et d’informer les professionnels sur l’ajustement dont ils auront à faire preuve dans un futur proche. [less ▲]

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See detailVirtualisation-Based Security Countermeasures in Software Runtime Systems
Gadaleta, Francesco ULg

Doctoral thesis (2013)

As systems become larger and more complex, the need to optimise the infrastructure in favour of reliability and redundancy becomes an imperative. Virtualisation technology seems to have partially ... [more ▼]

As systems become larger and more complex, the need to optimise the infrastructure in favour of reliability and redundancy becomes an imperative. Virtualisation technology seems to have partially fulfilled the needs dictated by growth by redefining the concept of infrastructure and paving the way for new business models such as cloud computing. As a matter of fact, successful low level attacks can circumvent or disable many of the traditional countermeasures in place within the same target system. Another trend that, according to the security research community, might be a cause for concern in the near future, is the tendency to shift current computer use to remote Internet services. This is making the web browser one of the most considerable actors of today’s computer usage. As a consequence, the web browser is gaining more and more attention from attackers, due to its prominent position within user’s experience. Despite the active contribution of researchers to mitigate the aforementioned security issues, one major challenge to focus in the immediate future consists in minimising the performance overhead, while guaranteeing the highest degree of security. Such a task seems achievable only by the puzzling tradeoff between performance and security that usually sacrifices the former in favour of the latter or vice versa. This dissertation contributes security mitigation techniques that address the aforementioned challenges. First, we focus on virtualisation technology to tackle the problem of operating system security. A countermeasure that relies on the cooperation between the target system and the virtualisation architecture, protects those critical memory locations within the target system that can be potentially compromised. Within the same field, a general framework that protects operating systems by enforcing the execution of trusted code is presented. Secondly, a security measure that improves web browser security against memory corruption attacks is provided. [less ▲]

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See detailEtude chémo-écologique et comportementale du parasitoïde, Nasonia vitripennis Walker (Hym., Pteromalidae), en vue de son utilisation comme biodétecteur en entomologie forensique
Frederickx, Christine ULg

Doctoral thesis (2012)

Most reports published in the field of forensic entomology are focused on Diptera, mostly on Calliphoridae. However, Hymenoptera are part of the entomofaunal colonisation of a dead body. Despite their ... [more ▼]

Most reports published in the field of forensic entomology are focused on Diptera, mostly on Calliphoridae. However, Hymenoptera are part of the entomofaunal colonisation of a dead body. Despite their significant presence in crime scenes, parasitoids are largely ignored due to their small size and the paucity of biological and behavioral information available in the ecosystem of corpse. The use of Hymenoptera parasitoids in forensic entomology can be relevant to many applications such as development of a biodectector. The objectives of this thesis were (1) to identify the Hymenoptera community parasitizing necrophagous Diptera, (2) to identify volatile organic compounds emitted by decaying process and by hosts which facilitate host-habitat and host location by female Nasonia vitripennis Walker (3) to evaluate the species N. vitripennis as biodectector of corpses. The faunistic study has identified five species of Hymenoptera in cadaver ecosystem. Alysia manducator was the most abundant Braconidae species. However, N. vitripennis was chosen as insect model; because over the last 50 years, this wasp has been intensely investigated in the subject of genetic, ecological and evolutionary research. A chemo-ecological approach, combining EAG and behavioral studies, was used on N. vitripennis with selected compounds from the decay process and their hosts. Firstly, we have demonstrated that host- habitat location and host location were dependent on the concentration of volatile organic compounds tested. In addition, dimethyldisulfide, a key component of decomposition and also released by Calliphora vicina Robineau-Desvoidy (Diptera, Calliphoridae) pupae, has a biological activity. Secondly, we have showed that rate of parasitism was based on the age of pupa, depth and substrate in which larvae burrow. This rate is the most important when pupae were six day-old, on the surface of soil and in a soil with a granulometry greater than 1mm. Moreover, N. vitripennis expanded our potential resource in biosensor used in forensic science. Females demonstrated a capacity for learning and memory. [less ▲]

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See detailGenomic Association Screening Methodology for High-Dimensional and Complex Data Structures: Detecting n-Order Interactions
Mahachie John, Jestinah ULg

Doctoral thesis (2012)

We developed a data-mining method, Model-Based Multifactor Dimensionality Reduction (MB-MDR) to detect epistatic interactions for different types of traits. MB-MDR enables the fast identification of gene ... [more ▼]

We developed a data-mining method, Model-Based Multifactor Dimensionality Reduction (MB-MDR) to detect epistatic interactions for different types of traits. MB-MDR enables the fast identification of gene-gene interactions among 1000nds of SNPs, without the need to make restrictive assumptions about the genetic modes of inheritance. This thesis primarily focused on applying Model-Based Multifactor Dimensionality Reduction for quantitative traits, its performance and application to a variety of data problems. We carried out several simulation studies to evaluate quantitative MB-MDR in terms of power and type I error, when data are noisy, non-normal or skewed and when important main effects are present. Firstly, we assessed the performance of MB-MDR in the presence of noisy data. The error sources considered were missing genotypes, genotyping error, phenotypic mixtures and genetic heterogeneity. Results from this study showed that MB-MDR is least affected by presence of small percentages of missing data and genotyping errors but much affected in the presence of phenotypic mixtures and genetic heterogeneity. This is in line with a similar study performed for binary traits. Although both Multifactor Dimensionality Reduction (MDR) and MB-MDR are data reduction techniques with a common basis, their ways of deriving significant interactions are substantially different. Nevertheless, effects on power of introducing error sources were quite similar. Irrespective of the trait under consideration, epistasis screening methodologies such as MB-MDR and MDR mainly suffer from the presence of phenotypic mixtures and genetic heterogeneity. Secondly, we extensively addressed the issue of adjusting for lower-order genetic effects during epistasis screening, using different adjustment strategies for SNPs in the functional SNP-SNP interaction pair, and/or for additional important SNPs. Since, in this thesis, we restrict attention to 2-locus interactions only, adjustment for lower-order effects always (and only) implies adjustment for main genetic effects. Unfortunately most data dimensionality reduction techniques based on MDR do not explicitly require that lower-order effects are included in the ‘model’ when investigating higher-order effects (a prerequisite for most traditional, especially regression-based, methods). However, epistasis results may be hampered by the presence of significant lower-order effects. Results from this study showed hugely increased type I errors when main effects were not taken into account or were not properly accounted for. We observed that additive coding (the most commonly used coding in practice) in main effects adjustment does not remove all of the potential main effects that deviate from additive genetic variance. In addition, also adjusting for main effects prior to MB-MDR (via a regression framework), whatever coding is adopted, does not control type I error in all scenarios. From this study, we concluded that correction for lower-order effects should preferentially be done via codominant coding, to reduce the chance of false positive epistasis findings. The recommended way of performing an MB-MDR epistasis screening is to always adjust the analysis for lower-order effects of the SNPs under investigation, “on-the-fly”. This correction avoids overcorrection for other SNPs, which are not part of the interacting SNP pair under study. Thirdly, we assessed the cumulative effect of trait deviations from normality and homoscedasticity on the overall performance of quantitative MB-MDR to detect 2-locus epistasis signals in the absence of main effects. Although MB-MDR itself is a non-parametric method, in the sense that no assumptions are made regarding genetic modes of inheritance, the data reduction part in MB-MDR relies on association tests. In particular, for quantitative traits, the default MB-MDR way is to use the Student’s t-test (steps 1 and 2 of MB-MDR). Also when correcting for lower-order effects during quantitative MB-MDR analysis, we intrinsically maneuver within a regression framework. Since the Student’s t-statistic is the square root of the ANOVA F-statistic. Hence, along these lines, for MB-MDR to give valid results, ANOVA assumptions have to be met. Therefore, we simulated data from normal and non-normal distributions, with constant and non-constant variances, and performed association tests via the student’s t-test as well as the unequal variance t-test, commonly known as the Welch’s t-test. At first somewhat surprising, the results of this study showed that MB-MDR maintains adequate type I errors, irrespective of data distribution or association test used. On the other hand, MB-MDR give rise to lower power results for non-normal data compared to normal data. With respect to the association tests used within MB-MDR, in most cases, Welch’s t-test led to lower power compared to student’s t-test. To maintain the balance between power and type I error, we concluded that when performing MB-MDR analysis with quantitative traits, one ideally first rank-transforms traits to normality and then applies MB-MDR modeling with Student’s t-test as choice of association test. Clearly, before embarking on using a method in practice, there is a need to extensively check the applicability of the method to the data at hand. This is a common practice in biostatistics, but often a forgotten standard operating procedure in genetic epidemiology, in particular in GWAI studies. In addition to the presentation of extensive simulation studies, we also presented some MB-MDR applications to real-life data problems. These analyses involved MB-MDR analyses on quantitative as well as binary complex disease traits, primarily in the context of asthma/allergy and Crohn’s disease. In two of the presented analyses, MB-MDR confirmed logistic regression and transmission disequilibrium test (TDT) results. Part of the aforementioned methodological developments was initiated on the basis of observations of MB-MDR behavior on real-life data. Both the practical and theoretical components of this thesis confirm our belief in the potential of MB-MDR as a promising and versatile tool for the identification of epistatic effects, irrespective of the design (family-based or unrelated individuals) and irrespective of the targeted disease trait (binary, continuous, censored, categorical, multivariate). A thorough characterization of the different faces of MB-MDR this versatility gives rise to is work in progress. [less ▲]

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See detailStudy of the physiological component involved in the development of crown rot in bananas and the role of phenolics in susceptibility variation mechanisms
Ewane, Cécile ULg

Doctoral thesis (2012)

Crown rot is a post-harvest disease caused by a broad unspecific and opportunistic parasitic complex, which affects the quality of export bananas in Cameroon, as well as in most of the production areas ... [more ▼]

Crown rot is a post-harvest disease caused by a broad unspecific and opportunistic parasitic complex, which affects the quality of export bananas in Cameroon, as well as in most of the production areas around the world. The originality of this research is that it is sets out, not only to investigate on the conditions surrounding the development of the disease and the variable factors of fruit’s susceptibility, but equally to characterize the phenolic content of the banana crown with differential susceptibility levels. The study therefore aims at showing the influence of abiotic and biotic factors on the fruit’s physiological component at harvest and the involvement of phenolic compounds in the mechanism staked in fruit’s susceptibility variations to this pathology. At the end of this study, it appears that abiotic and biotic factors influence the fruit’s physiological component at harvest, affecting thus its susceptibility level and therefore favours the development of crown rot disease. The reliability of internal necrosis surface (INS) assessments method was improved. The influence of abiotic factors (production area and harvest date) on fruit susceptibility was demonstrated without season influence. Fruits grown in high altitudes (Ekona, 500 m) were less susceptible to crown rot than the ones grown in low altitudes (Dia-Dia, Koumba, 80 m). It was noticed that at certain harvest dates within the rainy season, fruit susceptibility was higher in plantations with low altitudes. Concerning biotic factors, Mycosphaerella leaf spot disease’s influence was shown in two geographical areas. In Cameroon, black leaf streak disease significantly influenced banana’s sensitivity to crown rot (P< 0.001). In Guadeloupe, Sigatoka disease had no effect (P> 0.05) on banana’s susceptibility to the development of crown rot disease. The influence of the source-sink ratio variations, an abiotic factor, on fruit physiology could explain these differences. The influence of severe source-sink ratio modification on fruit susceptibility to crown rot was shown. Fruits with low source-sink ratio were the most susceptible. Bananas of extreme modalities (12leaves/1hand, 1leaf/8hands) and with differential susceptibility (S-, S+) to crown rot were used for the biochemical characterization of their phenolic content at two stages: the day of harvest before inoculation (dhbi) and 13 days post-inoculation (13dpi) by chromatographic methods (GC-MS, HPLC, LC-MS). Dopamine was identified as the major secondary metabolite (phenolic alkaloid) in banana crown. Norepinephrine and normetanephrine levels were high in the dhbi, especially in the S+ crowns. Hydroxycinnamic acids (ferulic acid, coumaric acid and their derivatives) and other unidentified compounds were accumulated in highly significant quantities (P <0.001) in the dhbi in the less susceptible crown (S-) as compared to the susceptible ones (S+), with decreased 13dpi mostly in the susceptible fruits (S+). These results suggest a possible role of these phenolics in banana crown biochemical defense. However, the main role of each phenolic detected in the susceptibility variations mechanism remains unclear. This study is the starting point to understanding the function(s) of phenolics in banana crown defense. This is a pioneer study on the influence of abiotic and biotic factors on the banana fruit’s physiological component at harvest through the assessment of their incidence on crown rot development. This work appears to be the first to link the level of fruit’s susceptibility at two stages (dhbi and13dpi) with their crown phenolic content. [less ▲]

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See detailFrom medical imaging to finite element simulations: a contribution to mesh generation and locking-free formulations for tetrahedra
D'Otreppe, Vinciane ULg

Doctoral thesis (2012)

Patient-specific finite element (FE) modelling is gaining more and more attention over the years because of its potential to improve clinical treatment and surgical outcomes. Thanks to patient-specific ... [more ▼]

Patient-specific finite element (FE) modelling is gaining more and more attention over the years because of its potential to improve clinical treatment and surgical outcomes. Thanks to patient-specific modelling, the design of individualised implants and prostheses, surgical pre-operative planning and simulation, and the computation of stresses and strains in a patient's organ for diagnostic purposes will become a reality in the future. This work investigates two of the most challenging tasks of patient-specific modelling: the creation of image-based finite element meshes and the development of a low-order locking-free tetrahedral element. First, a general meshing strategy for tetrahedral mesh generation from segmented 3D images is proposed. The originality of the approach is the addition of surface reconstruction algorithm to the traditional image-to-mesh pipeline. The main advantages for this are: the generation of smooth boundaries, robustness to segmentation noise, a user-defined mesh resolution and a good fidelity of the mesh boundaries with respect to the underlying image. Also, the proposed meshing strategy is capable of generating meshes of heterogeneous structures, containing several interconnected types of tissues. Applications demonstrate that the interfaces between distinct material regions are topologically correct, i.e. the connections are edge-on-edge and node-on-node. Specific mesh decimation and mesh smoothing algorithms were designed for this multi-material tetrahedral mesh generator. In a last chapter, patient-specific hexahedral meshes are created by combining the proposed surface reconstruction algorithm with a classical voxel-conversion algorithm. Second, a low-order tetrahedral element for the solution of solid mechanics problems involving nearly incompressible materials is developed. The formulation is based on F-bar methodologies and nodal-based formulations. As in nodal based formulations, nodal Jacobians are defined. These nodal quantities are then averaged over the element to define a modified elemental Jacobian, which is used to define a modified deformation gradient, F-bar, for the element. Both 2D triangular and 3D tetrahedral are proposed and they can be used for both implicit and explicit analysis. The exact stiffness terms for the tangent stiffness matrix are derived so that a quadratic convergence rate in ensured for the Newton-Raphson equilibrium iterations. Most importantly, the new element can be used regardless the material model. Benchmarking 2D and 3D numerical tests using several constitutive models indicate a substantial removing of both the volumetric and the shear locking tendency of the standard linear triangle and tetrahedron, as well as an accurate distribution of strain, stress and pressure fields. The potential of the resulting image - to - FE model procedure is demonstrated in the last part of this work, through patient-specific finite element analyses of actual biomechanical research topics. [less ▲]

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See detailAchromatization of nonimaging Fresnel lenses for photovoltaic solar concentration using refractive and diffractive patterns
Languy, Fabian ULg

Doctoral thesis (2012)

In the field of concentrated photovoltaics, the main disadvantage of lenses compared to mirrors lies in their chromaticity: Snell's law is related to the refractive index which is wavelength dependent ... [more ▼]

In the field of concentrated photovoltaics, the main disadvantage of lenses compared to mirrors lies in their chromaticity: Snell's law is related to the refractive index which is wavelength dependent. Consequently, even for purely collimated beams under normal incidence, the maximum concentration achievable with typical lenses made of PMMA is limited to ~1000×. This maximum value becomes even lower when considering Sun's angular aperture. Since the law of reflection is not wavelength dependent, mirrors can theoretically achieve the thermodynamic limit of concentration which is about 46'000×. This thesis aims at the design and the manufacturing of an achromatic Fresnel lens suitable for photovoltaic solar concentration, i.e. combining high concentration, low production cost and tolerance to manufacturing errors. Firstly, we investigated a hybrid lens made of a refractive lens and a diffractive lens. The investigations showed that the concentration ratio could be multiplied by 4. A full chapter is dedicated to the optimisation of blazed diffraction gratings to finally achieve the design of the diffractive lens. Nevertheless, a bilayer diffractive lens is needed to obtain a high diffraction efficiency which makes the diffractive lens highly sensitive to manufacturing errors and consequently not suitable for photovoltaic solar concentration. Purely refractive achromatic Fresnel doublets were then investigated and several designs were compared. They allow for very high concentration ratios in the case of collimated beams under normal incidence, higher than 100'000×. Therefore, contrary to singlets, Fresnel doublets are much more affected by the angular size of the source than by the chromatic aberration. Moreover, it was shown that they are tolerant to manufacturing error, change of temperature and uncertainty on the refractive index. It emerges from this thesis that the concept of achromatic doublets is a tolerant and low-cost production solution to achieve a highly concentrated white flux. Although bilayer diffractive lenses are not suitable for concentrated photovoltaics, the combination of refractive with diffractive structures seems to be promised to a bright future for spectrum splitting applications, including spectrum splitting for concentrated photovoltaics. [less ▲]

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See detailMulti-row approaches to cutting plane generation
Poirrier, Laurent ULg

Doctoral thesis (2012)

This thesis focuses on the use of cutting-plane techniques to improve general-purpose mixed-integer linear programming solvers. The first topic covered here is a fast separation method for two-row cuts ... [more ▼]

This thesis focuses on the use of cutting-plane techniques to improve general-purpose mixed-integer linear programming solvers. The first topic covered here is a fast separation method for two-row cuts. Two-row cuts are intersection cuts from two rows of a simplex tableau describing the LP relaxation of the problem. This type of cuts recently gathered a lot of attention from the scientific community following a paper by Andersen, Louveaux, Weismantel and Wolsey describing the facets of the underlying two-row model and providing an intuitive geometric classification the the derived cuts. The specificity of the approach adopted here is that it does not rely on an "infinite relaxation" point of view and generate intersection cuts from fixed lattice-free sets. Instead, given a fractional point, it aims at always finding a most violated facet-defining inequality for the two-row model. This can be achieved by optimizing over the polar set of the integer hull of the model. A fast way of performing this is provided, by means of a polyhedron that is equivalent to the polar for that purpose, but has a more compact representation. Moreover, a row-generation algorithm is developed in order to avoid the costly computations of integer hulls of two-dimensional cones. An implementation of the resulting algorithm performs separation of two-row cuts in a few milliseconds on average, on the standard MIPLIB 3 and 2003 testsets. While this two-row separator is quick, the measurements of the computational usefulness of the cuts do not yield satisfactory results. Since all the cuts generated are facet-defining, this might suggest that the underlying two-row models are too weak. This observation prompted the second part of this thesis, an attempt to evaluate the strength of various multi-row relaxations, on small instances, using a generic separator. To that end, a separator is developed, which is able to compute facet-defining inequalities from arbitrary (yet reasonably small) mixed-integer sets. A row-generation approach is again adopted, but this time the slave part consists in the resolution of a mixed-integer problem instead of a closed-form oracle. Some interesting computational tricks are developed, in order to speedup the inherently hard computations. [less ▲]

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See detailThe functional neuroanatomy of tinnitus: insights from resting-state fMRI
Maudoux, Audrey ULg

Doctoral thesis (2012)

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See detailRéflexion pure, Vérité, Violence. Pour une pensée de la conditionnalité. Lecture croisée de Sartre et d'un texte tibétain
Filipucci, Alexis ULg

Doctoral thesis (2012)

In this work, a systematic reading of Sartre's philosophy is intended. Methodogically, we use a highly systematic thought of a Tibetan philosopher, Ju Mipham. Having translated one work of this Buddhist ... [more ▼]

In this work, a systematic reading of Sartre's philosophy is intended. Methodogically, we use a highly systematic thought of a Tibetan philosopher, Ju Mipham. Having translated one work of this Buddhist writer, we observe how the process of the hermeneutical spiral between two philosophies born in different cultural areas helps us to understand in a deeper manner these two thoughts. [less ▲]

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See detailLa fonction mitochondriale des cellules musculaires squelettiques équines en culture : effet de l'anoxie et des neutrophiles activés.
Ceusters, Justine ULg

Doctoral thesis (2012)

Introduction Horses are known to be remarkable athletes. However, to realize such repeated intense exercises, as competition horses do, and could also became a stressing condition leading to muscular ... [more ▼]

Introduction Horses are known to be remarkable athletes. However, to realize such repeated intense exercises, as competition horses do, and could also became a stressing condition leading to muscular dysfunctions but could also decrease their performances. In horses, lesions from ischemia/reperfusion are found in numerous clinical situations but also during intense exercise, the muscular oxygenation decreasing as a function of the exercise intensity. But it is during the reoxygenation, with the subsequent increase of the electron flux within the mitochondrial respiratory electron transport chain at the cessation of exercise, that an important increase of the reactive oxygen and nitrogen species (RNOS) production will be observed. The realization of such intense exercise provokes also an important systemic inflammatory reaction. Recently, some studies realized by our group on competing horses showed that intense exercise can activate the polymorphonuclear neutrophils (PMNs) which degranulate their myeloperoxidase (MPO) and elastase (ELT). The increase of MPO was not only plasmatic but also muscular, where it was associated with a decrease of the mitochondrial complex I activity, showing there a possible link between the MPO activity and the mitochondrial dysfunction in horses performing exercise. The relationship between ischemia/reperfusion, ROS production from mitochondria, muscular damages and inflammatory reaction is largely unexplored in horses. The principal objectives of this work were to study, on a primary culture of equine skeletal muscle cells obtained from muscular microbiopsies, the effect of anoxia/reoxygenation (A/R) and/or of MPO on their ROS production and mitochondrial respiratory function. Results Primary culture of equine skeletal muscle cells from muscular microbiopsies With muscular microbiopsies, we developed an efficient and convenient sampling method, usable in current practice and even on high level competing horses. By using the microbiopsies as explants, we obtained a primary culture of skeletal muscle cells, a suitable experimental model for the in vitro study of equine muscular function. Model of anoxia/reoxygenation applied on cultured equine skeletal muscle cells Thanks to the primary culture, we showed by fluorescence spectroscopy and gas chromatography, an increased ROS production by adherent cells submitted to 2 h of A/R. For the following investigations, 2 other models were designed on detached cells : a first one of cyclic A/R (2 x 30 min) and a second one of a single long period of 1 h, 2 h or 3 h of A/R. The first one showed a decrease of the routine respiration, but also of ROS production and of the mitochondrial complex I specific activity of the cells submitted to cyclic A/R. After a single long period of A/R, on the contrary, the routine respiration, the ROS production and the mitochondrial complex I specific activity of the cells were increased while the ATP production by these cells was decreased. This observation, arguing for an uncoupling of the oxidative phosphorylation, prompted us to investigate the uncoupling protein 3 (UCP3) expression by cultured cells. The indirect immunofluorescence, as well as the electrophoresis coupled with the western blot, showed that they expressed UCP3, in normoxia and after 2 h of A/R, but also that this expression varied as a function of the duration of the A/R, with a maximum observed for 2 h. The oxygraphic phosphorylation control protocol (PCP) applied on detached cells showed an increase of their routine but also of their non phosphorylating (after ATP synthase inhibition) respirations after a single long period of 2 h A/R. Their maximal respiratory capacity, per contra, decreased significantly. When regarding the flux control ratios (FCR, related to maximal respiratory capacity), we confirmed that cells submitted to 2 h of A/R need to function more to keep stable their energetic state (increase of the part of their maximal respiratory capacity used for oxidative phosphorylation because of a lesser efficiency). Inflammatory model Equine neutrophils activation in whole blood All the activation systems used, 12-phorbol 13-myristate acetate (PMA), cytochalasin B with N-formyl-methionyl-leucyl-phenylalanine (CB/fMLP), tumor necrosis factor-alpha (TNF- α), lipopolysaccharides (LPS) and LPS with TNF-α, induced a significant degranulation of total MPO by the PMNs activated in whole blood. Only the combinations CB/fMLP and LPS/TNF-α caused a significant release of active MPO. For the release of ELT by activated PMNs, only the action of the PMA was significant. Use of purified active equine MPO Initially, we showed that MPO incubated with equine skeletal muscle cells was able to bind to the cell membranes, but furthermore, thanks to the differential centrifugation protocol, that we demonstrated that it was able to enter within the cells, because we found it in the cytosolic fraction. Our following experiences showed that it was able, even alone, to increase the ROS produced by the cells, as demonstrated by fluorescence and gas chromatography. Furthermore, MPO worked harder than Horseradish peroxidase (HRP), our "peroxidasic control". The MPO seemed also to alter the mitochondrial respiratory function of cultured cells. Anyway, thanks to the oxygraphic PCP protocol, we showed that MPO alone decreased mostly their routine respiration and their maximal respiratory capacity. Paradoxically, we seen that it increased the part of the maximal respiratory capacity used for routine and non phosphorylating respirations. The second oxygraphic protocol, designed on permeabilized cells, seems to confirm these observations. Compared to control cells, the MPO-treated cells had a increased non phosphorylating respiration and a decreased maximal respiratory capacity, particularly via the mitochondrial complex I. Combined model: anoxia/reoxygenation in inflammatory conditions With fluorescence spectroscopy as well as with gas chromatography, the MPO amplifies the ROS production already increased with the A/R alone. Furthermore, with a 3,3-diaminobenzidine (DAB) coloration, we showed the persistence of the MPO (and of the HRP), within the cells, even after 2 h of A/R. The oxygraphic PCP protocol confirms that MPO seems to exacerbate the damage initiated by A/R. Thus, compared to what we observed with A/R alone, the addition of MPO causes a further decrease of the routine respiration and the maximal respiratory capacity of the cells and increases their non phosphorylating respiration. These observations, along the lines of an important mitochondrial dysfunction, were confirmed when regarding the FCR. Thus, MPO-treated cells, submitted to A/R need to use a greater part of their maximal respiratory capacity for routine respiration, but a greater part of it was also used for non efficient respiration. So, these cells need to work more intensely to keep stable their energetic state, what is reflected in our protocol by an increased part of the maximal respiratory capacity used for oxidative phosphorylation compared to what we observed after A/R alone. Conclusion and perspectives During intense exercise, some physiopathological conditions, inducing important mitochondrial and energetic alterations, seem to gather within the muscle of sport horses. As showed by our work, because of its implication in the mitochondrial regulation at the respiratory level as well as for RNOS production, and of its particular sensibility to nitration, the mitochondrial complex I could play a pivotal role. Although our results clearly indicate that MPO, by exacerbating the deleterious effects of A/R, is detrimental to cellular and mitochondrial functions, further precisions are needed to confirm the specific implication of mitochondrial complex I in the observed phenomena. The results obtained by our group in vivo on competing horses lead the way in this direction but, the adaptation of the oxygraphic protocol on permeabilized cells, combining A/R with the action of MPO, will help to confirm, in vitro, the hypothesis. On another way, the effect of nitration or nitrosation on the mitochondrial complex I will need to be further investigated. Finally, to consider in a largest way the action of the PMNs on the mitochondrial function, it will be interesting to use the whole blood model of PMNs activation in co-culture with equine skeletal myoblasts. By this way, the action of other inflammatory factors or mediators could be studied in conditions nearly to the ones observed in vivo. [less ▲]

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See detailEtude des mécanismes responsables du comportement agrégatif d’Harmonia axyridis (Pallas) (Coleoptera : Coccinellidae)
Durieux, Delphine ULg

Doctoral thesis (2012)

The negative impacts linked to the introductions of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), progressively increasing in Europe and in North America, it is urgent to find a way to ... [more ▼]

The negative impacts linked to the introductions of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), progressively increasing in Europe and in North America, it is urgent to find a way to manage its populations. The social interactions involved in its aggregative behavior remain misunderstood although a better understanding of the semiochemicals the ladybeetles use during this phenomenon could lead to the development of new control methods. Therefore, the main objective of this thesis was to improve the understanding of the mechanisms set up by H. axyridis during its aggregative stage. Firstly, we have demonstrated the use of two different area markings by this species during its overwintering. The first one, laid by the ladybeetles while walking, lead conspecifics towards aggregation sites whereas the second one, deposited inside these sites, ensures the cohesion of the cluster. These markings are made up of saturated, mono- and diunsaturated hydrocarbons. Among these chemicals, it seems that the unsaturated hydrocarbons, and in particular the ones containing two double bonds, present a greater biological activity. However, the response of H. axyridis towards these chemicals depends on the insect physiological state. In the second instance, we have showed for the first time that H. axyridis presents a permanent aggregative behavior. The hydrocarbons laid by the ladybeetles during their displacements do not play any role in this behavior during summer conditions. On the other hand, conspecific elytral compounds and, in a lesser extent, physical contact, are well involved. Moreover, all our experiments have pointed out that visual elements play a major role in this social behavior and so, have also to be taken into account in the design of traps to control the populations of this invasive species. [less ▲]

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See detailCoastal pollution of the Mediterranean and extension of its biomonitoring to trace elements of emerging concern
Richir, Jonathan ULg

Doctoral thesis (2012)

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming ... [more ▼]

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming from our continental activities, are transported through rivers or by air and accumulate in seas and oceans where they mainly affect coastal areas. During the 70ies, scientists suggested to use organisms, in particular mussels of the genus Mytilus, in order to evaluate the status of chemical contamination of coastal ecosystems. Biomonitoring was born. Since, many monitoring studies were published using various animal and vegetal species. Two of the most studied bioindicators species in the Mediterranean are the marine magnoliophyte Posidonia oceanica and the Mediterranean mussel Mytilus galloprovincialis. Monitoring studies with these two species have mainly focussed on contaminations by Cr, Ni, Cu, Zn, Cd, Pb (Mytilus galloprovincialis and Posidonia oceanica), Fe (Posidonia oceanica), As, V and Ag (Mytilus galloprovincialis). However, other trace elements like Be, Al, Mn, Co, Se, Mo, Sn, Sb and Bi have been subject to nearly no ecotoxicological survey. Furthermore the worldwide evolution of our technologies and of our lifestyle increases the extraction and production of trace elements (notably to answer needs of developing countries). The biomonitoring of the pollution by trace elements is henceforth a topical subject. The overall objective of this work was therefore to evaluate the potential use of Mytilus galloprovincialis and Posidonia oceanica as bioindicators to monitor the Mediterranean coastal pollution by Be, Al, Mn, Co, Se, Mo, Sn, Sb, Bi, Fe, As, V, and Ag. These trace elements, mostly little studied, can be categorized as elements of “environmental emerging concern”. A time-integrated efficient monitoring of trace elements requires the continuous survey of their environmental levels; we therefore also measured levels of trace elements classically monitored with these two species. Mytilus galloprovincialis and Posidonia oceanica complement each other in monitoring surveys. Both species accumulate pollutants dissolved in the water column. Posidonia oceanica, rooted in the seafloor, accumulates moreover pollutants stored in sediments in the long term. Mytilus galloprovincialis, as a filter feeder, further accumulate particulate pollutants suspended in the water column. The combined use of both bioindicators therefore provides a global view of the health status of the coastal environment (water, sediments, suspended matter). Our first goal was to measure, at the scale of the French Mediterranean littoral, the spatial variability of trace element contents in Posidonia oceanica, and to determine if trace elements of environmental emerging concern threaten the chemical integrity of coastal ecosystems. We observed that the large majority of trace elements little or no monitored with Posidonia oceanica showed an equivalent to higher spatial variability than elements classically monitored with that species. We also showed that the spatial variability could be associated to specific anthropic activities like agriculture (Mo), mining (Sb), storage and refinement of oil products (V), or the presence of harbours and major urban centres (Sn, Bi). Their monitoring, along with the one of trace elements classically studied in the Mediterranean, turns out to be essential. In addition, the in-depth study of the contamination state of the Calvi Bay (Northwestern coast of Corsica, France), enabled us to define (or re-define) this site as a reference site for the monitoring of the chemical pollution by trace elements in the Northwestern Mediterranean. We further studied the physiological mechanisms of accumulation, storage and excretion of trace elements by Posidonia oceanica. In situ contamination of seagrass bed portions allowed us to model the rapid kinetics of accumulation of contaminants by Posidonia oceanica shoots. Compartments of the plant answered differently to pollutant exposures. So, adult and senescent leaves assimilated pollutants less rapidly than young actively growing leaves. Trace elements, once accumulated, could be redistributed between the plant compartments, notably towards the rhizomes-roots systems buried in sediments. Our results experimentally showed that these below-ground organs could therefore play the role of biological archives for many elements. At the end of periods of exposure to pollutants, kinetics of decontaminations of Posidonia oceanica shoots were relatively fast and depended notably on the duration of the exposure to trace elements, on their toxic or essential character and on the studied compartment. We concluded that Posidonia oceanica was a sensitive bioindicator for the monitoring of the past and present coastal pollution by trace elements. We showed that Mytilus galloprovincialis efficiently accumulated trace elements of environmental emerging concern as well as elements classically studied with this bioindicator species. The physiology of mussels further conditioned their answers to pollutant exposures. Their reproductive cycle dissolved trace element concentrations during the massive production of gametes and conducted to differences more or less important between individuals of both sexes. The conservative character of the distribution of trace elements between the different body compartments of Mytilus galloprovincialis suggested an important physiological regulation of their internal levels. Finally, the size of mussels used in this study, harvested from an aquaculture farm, did not noticeably influence inter-individual concentrations, all mussels of a same rope having approximately the same age. In conclusion, this study enabled to improve and enlarge our state of knowledge about the monitoring of the pollution of the Mediterranean coastal environment by trace elements. In particular, both Mytilus galloprovincialis and Posidonia oceanica showed to be good candidates for the monitoring of trace elements of environmental emerging concern. [less ▲]

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See detailTime delays in gravitationally lensed quasars
Eulaers, Eva ULg

Doctoral thesis (2012)

Starting with a concise introduction on gravitational lensing, time delays between lensed quasars and its importance as a cosmological probe to estimate the Hubble constant, we present our contribution to ... [more ▼]

Starting with a concise introduction on gravitational lensing, time delays between lensed quasars and its importance as a cosmological probe to estimate the Hubble constant, we present our contribution to this domain. In a first part, we explain the details of the Numerical Model Fit, a method to estimate time delays between two or more lensed quasar images. We apply this technique to the light curves of 11 lensed quasars with known time delays in order to analyse these published delays in a more homogeneous way. Some results can be confirmed, but others prove to be unreliable. The second part is devoted to the most recent results of our contribution to the COSMOGRAIL collaboration. We briefly summarize the data reduction and analysis tools before the presentation of the photometry and time delay analysis of 6 lensed quasars. On top of the confirmation of time delays in two objects, SDSS J1206+4332 and SDSS J1650+4251, we are the first to measure the time delay in three doubly lensed quasar systems: HS 2209+1914, SDSS J0903+5028, and SDSS J1155+6346. The time delay analysis of the well-known quadruply lensed quasar PG 1115+080 reveals interesting elements, and asks for further investigation of longer light curves. [less ▲]

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See detailGRH et Organisation du travail dans les centres d'appels délocalisés au Maroc
Makkaoui, Mohamed ULg

Doctoral thesis (2012)

Considered, rightly or wrongly, as "new factories of the future", call centers generate more interest for both researchers and professionals. Their human aspects in general and their HR practices in ... [more ▼]

Considered, rightly or wrongly, as "new factories of the future", call centers generate more interest for both researchers and professionals. Their human aspects in general and their HR practices in particular is a rich field for investigations, due to the importance of their technical and social systems in their performance or their sustainability. The question of the choice of HR practices is the focus of this work devoted to the issue of HRM and work organization in offshoring call centers. It is based on nine case studies representing a varied typology of Moroccan call centers sector and three typical -ideal models adopted by them (Hard, Soft or hybrid). The choice of a model or another comes, initially, from a business strategy, a targeted market segment and a given level of outsourced value-added activities. The alignment between strategy and organization of the call center operates for each model to incorporate the same operational requirements (customer-agent interactions, colleagues) and its internal labor market. This variable is the link between work organization and HR strategy adopted. Referring to an HR model or another is conditioned by the intervention of the principal who greatly influence the decisions of managers as well as decision makers. [less ▲]

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See detailIMPACT DE LA STEAM EXPLOSION ET DE L’HOMOGENEISATION SUR LES PROPRIETES PHYSICOCHIMIQUES ET L’HYDROLYSE ENZYMATIQUE DE LA CELLULOSE
Jacquet, Nicolas ULg

Doctoral thesis (2012)

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is ... [more ▼]

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is to develop second generation biofuel and biobased product that utilizes non-food plant materials. The major component of these materials is lignocellulose, which is a complex composed by widely available biological polymers such as cellulose, hemicelluloses and lignin. This thesis is a part of this approach and is focused on a well-define part of these materials: the cellulose. The first part of this work was focused on the impact of two pretraitements (steam explosion and homogenization) on physico-chemical properties and hydrolysis yield of pure cellulose fiber. In contrast with literature, results obtained showed that moderate steam explosion treatments did not appear to improve the enzymatic hydrolysis yield of the cellulose fibers. In Parralel, a model that predicts the effect of the intensity of the steam explosion treatment in correlation with temperature and time was assessed. Links between this model and the evolution physico-chemical properties of the cellulose during pretreatment and cellulose hydrolysis yield were established In a second way, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. Regarding the homogenization, it was shown that homogenization increase significatively the cellulose hydrolysis (from 25 to 100%). Results highlights potential of this technology to be used as a pretreatment Finally, enzymatic hydrolysis step has been studied in order to improve cellulose hydrolysis and to obtain high concentrated hydrolysate. In this way, two methods based on successive addition of enzyme and substrate were assessed [less ▲]

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See detailExtending Donor Pool with Donation after Cardiac Death in Kidney and Liver Transplantation:What is the Price to Pay?
Le Dinh, Hieu ULg

Doctoral thesis (2012)

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation ... [more ▼]

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation coming from this donor source in Liège and Belgium. Additionally, an adapted DCD Maastricht classification is also discussed. Chapters 2.1 and 2.2 summarize the DCD procurement and transplant activity in Liège and Belgium from 2000 to 2009 with an update on data up to 2011. In Liège, DCD really contributes to the DD pool and boosts the transplant activity of the center in both kidneys and livers by on average 30%. By contrast, the steady rise in DCD activity in Belgium does not lead to major increase in the DD donation and transplantation. In other words, some kind of donor-type redistribution within the DD pool might occur. Chapters 2.2, 3.1, and 3.2 discuss the results of kidney transplantation (KT) from DCD. We demonstrate that Liège‟s experience is comparable to the national level in Belgium and does not differ from the general results in the world with regard to early graft dysfunction, medium-term graft function, graft and patient survival. The excellent results of DCD-KT are attributed to the relatively short warm and cold ischemia, favorable donor factors, and the role of hypothermic machine perfusion (in Belgian series). Chapters 4.1, and 4.2 discuss the results of liver transplantation (LT) from DCD. Liège‟s results are encouraging and apparently as good as those from donation-after-brain-death LT because of short warm and cold ischemia times. Belgian results show an increased incidence of primary non-function and ischemic cholangiopathy which is in agreement with previously published data. Chapter 5 proposes an adapted DCD Maastricht classification which maintains the original categories 1 to 4 that are now well-known and widely accepted, and adds a fifth category, so-called „DCD after euthanasia‟. Each category is divided into two or three sub-categories: sub-category A is linked to longer warm ischemia (and worse results) than sub-category B; and B versus C, respectively. In addition, sub-categories A (2A, 3A, 4A, and 5A) are mostly linked to DCD processes occurring in the ICU, which helps to understand and memorize this classification. By keeping the original skeleton of the 1995 Maastricht classification, room is left to add new sub-categories in the future, if deemed clinically relevant. [less ▲]

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See detailS’engager dans un atelier-théâtre : vers une recomposition du sens de l’expérience
Brahy, Rachel ULg

Doctoral thesis (2012)

Dans cette thèse, nous traitons des animations théâtrales mises en place par les compagnies de théâtre-action situées en Communauté française de Belgique. La question centrale qui nous guide est celle des ... [more ▼]

Dans cette thèse, nous traitons des animations théâtrales mises en place par les compagnies de théâtre-action situées en Communauté française de Belgique. La question centrale qui nous guide est celle des formes concrètes que revêtent les pratiques contemporaines d’animation. Par ailleurs, nous nous intéressons également aux changements survenus dans l’exercice de l’activité. En effet, les premières compagnies à se revendiquer du « théâtre-action » naissent autour des mouvements de 1968. D’abord perçues comme expérimentales, ces pratiques pourraient bien, aujourd’hui, être considérées comme désuètes, à tout le moins, déconnectées des problématiques contemporaines. Notre enquête s’ouvre à partir de cette idée et nous montrons ensuite comment s’est acheminée une progressive reconversion des pratiques. En privilégiant le cadre théorique de la sociologie pragmatique française (et plus exactement, celui des « régimes d’engagement » établi par Laurent Thévenot) nous détaillons les modalités d’engagement dans un « atelier-théâtre ». Alors qu’originellement, le dispositif théâtral privilégiait les formats de la revendication « critique » et mobilisait prioritairement des personnes issues du monde ouvrier, on constate aujourd’hui une relation forte entre les compagnies de théâtre-action et le monde de l’accompagnement social. Cette proximité produit inévitablement un déplacement signifiant qui, pourtant, ne s’apparente pas à une totale superposition des secteurs. L’analyse de notre matériel empirique (composé d’entretiens et d’observation ethnographiques) témoigne d’une irréductible spécificité inhérente à l’engagement dans le monde du théâtre et de la fiction. Ainsi, les manières de prendre part à un monde commun et de s’engager en public sont repensées. En définitive, nous dégageons l’existence d’un « espace public esthétique » et précisons les voies par lesquelles un « engagement en présence » permettrait d’y accéder. [less ▲]

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See detailLa littérature scientifique dans la formation des bioingénieurs à Gembloux. Vingt années d'évolution du concept d'Information Literacy
Pochet, Bernard ULg

Doctoral thesis (2012)

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to ... [more ▼]

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to recognize an information need and enable them to locate, evaluate and use information needed. The concept of information literacy has evolved over the last two decades. This essay traces, through five articles and a review of the literature on the subject, the evolution of the concept. It also presents ways to implement information literacy education with a methodological approach, starting by the identification of the need of information to solve a problem to the production of a scientific communication (a homework, a conference, a scholarly paper...). This work addresses also the question of the relative invisibility of the concept of information literacy outside information specialists such as librarians. The major objective is to demonstrate that information literacy education is going well beyond the library. The skills involved are also intellectual, social and cultural skills. They include media and new information technologies and are not limited to technical or technological skills. Information literacy has become an autonomous discipline, with specific content, evolving, to talk about a didactic. Information literacy courses held in Gembloux should be considered as tools to improve the training of bioengineers and particularly the quality of their scientific publications. [less ▲]

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See detailStructure et fonction des communautés phytoplanctoniques en milieux côtiers marin et lagunaire (Méditerranée – Corse) dans une optique de gestion
Garrido, Marie ULg

Doctoral thesis (2012)

Les écosystèmes côtiers contribuent de manière importante à la production primaire des océans. De par leur position géographique, ils sont particulièrement sensibles à l’eutrophisation. Le compartiment ... [more ▼]

Les écosystèmes côtiers contribuent de manière importante à la production primaire des océans. De par leur position géographique, ils sont particulièrement sensibles à l’eutrophisation. Le compartiment phytoplanctonique y joue un rôle prépondérant au regard de sa position dans la chaîne tropique, mais également en termes de diversité. Il est également capable d’intégrer et/ou de refléter les changements environnementaux qui s’opèrent à court, moyen et long terme. Cette thèse vise à renforcer les connaissances sur la dynamique et la fonction des communautés phytoplanctoniques par rapport aux conditions environnementales dans deux écosystèmes côtiers, en utilisant des techniques traditionnelles comme la microscopie, l’HPLC et d’autres plus récentes comme le Phyto-PAM et la FluoroProbe. Le littoral corse a été choisi comme site d’étude. En effet, ses 1 047 km de côtes regorgent d’écosystèmes particulièrement dynamiques, d’une richesse biologique importante et de zones d’interfaces productives (e.g. structure frontale, milieu lagunaire). Malgré cela, il existe peu de données concernant la dynamique et la fonction de ces micro-algues, aussi bien en milieu marin côtier que lagunaire. Une fréquence d’échantillonnage appropriée à l’échelle d’observation a été utilisée selon les écosystèmes étudiés et le type d’étude menée (in situ ou expérimentale), allant de prélèvements mensuels à des prélèvements journaliers. Dans un premier temps, nous avons poursuivi les efforts engagés depuis plusieurs années concernant l’amélioration des méthodes d’analyses spectrofluorimétriques nécessaires pour l’étude de la dynamique et l’analyse fonctionnelle des communautés phytoplanctoniques. Des recommandations concernant les conditions de conservation des échantillons (i.e. durée, température) ont été dégagées pour l’analyse au Phyto-PAM, afin d’affiner les limites d’utilisation de cet outil. Nous avons également testé l’utilisation de la FluoroProbe dans les écosystèmes côtiers en Méditerranée. Dans un second temps, nous avons étudié la variabilité spatio-temporelle des communautés phytoplanctoniques en milieu marin côtier (Calvi et Bastia) et en milieu lagunaire eutrophisé (Réserve Naturelle de Biguglia). Les résultats ont mis en avant une succession écologique et une structure des peuplements phytoplanctoniques différentes dans les deux écosystèmes marins côtiers étudiés, présentant des spécificités locales propres et comparés à l’échelle des zones côtières en Méditerranée. Nous avons démontré que des événements météorologiques pouvaient influencer les variations observées, agissant directement sur l’abondance des espèces ou indirectement sur les conditions du milieu (e.g. nutriments). Au niveau lagunaire, les actions de gestion mises en œuvre ont impacté la structure et l'efficacité photosynthétique des communautés phytoplanctoniques. Les modifications des flux hydrologiques ont exacerbé le caractère confiné de la lagune et des efflorescences successives d’espèces opportunistes et non profitables au réseau trophique supérieur ont été observées. Ces études ont permis de fournir une aide scientifique en ce qui concerne la prise de décision qui incombe aux acteurs de l’environnement et plus particulièrement les gestionnaires, dans une optique de gestion. [less ▲]

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See detailBiolixiviation de la carrolite-Application aux minerais polymétalliques de l'Arc Cuprifère du Katanga (cas de minerais de la mine de Kamoya, Kambove) en RDC
Nkulu Wa Ngoie, Guy ULg

Doctoral thesis (2012)

The present work focuses on the bioleaching of carrolite as pure mineral and application of bioleaching as an alternative technique for processing the polymetallic sulphide ores in Katanga copperbelt ... [more ▼]

The present work focuses on the bioleaching of carrolite as pure mineral and application of bioleaching as an alternative technique for processing the polymetallic sulphide ores in Katanga copperbelt (case of Kamoya deposit ores) in Democratic Republic of Congo (DRC). A preliminary study on the bioleaching of carrolite in the presence of mesophilic bacteria has highlighted the effect of the initial pH (pH = 1.5, 2.0 and 2.5), particle size (-53μm, -75+53 µm, -106+75µm), the pulp density (dp= 2.5 and 10) on the pH, the solution redox and on the dissolution performance of copper, nickel and cobalt. The results obtained at this stage showed that the initial pH, particle size and pulp density greatly influences the process of bioleaching of carrolite. The evolution of pH, solution redox and the efficiency of metals dissolution with time considering these factors indicate the importance of bacterial growth. Good bacterial activity thereby yields high metal dissolution which is being obtained at initial pH 2.0, particle size of -53μm and 2% pulp density. A second study upon the bioleaching of carrolite has allowed highlighting the metal dissolution mechanism during the bioleaching process. The evolution of the bacterial population, observations of Optical Microscope (MO), Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) of carrolite grains during bioleaching and spectroscopical analysis in X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) of bioleaching residues allowed us to demonstrate the role and importance of bacteria attached on the surface of carrolite grains from one hand, and ferric ions on the other hand, during the carrolite bioleaching. Strong adhesion of bacteria to the surface of the carrolite grains was observed during early bioleach stages and playing an important role in the process. This phenomenon would cause the release of ferrous ions in solution by a direct contact mechanism on the one hand and causing oxidation of ferrous ions, elemental sulfur or sulfur compounds on the other hand, compounds which would accumulate at the surface of carrolite grains. The number of free bacteria in solution increases thus promoting the oxidation of ferrous to ferric ions, which oxidize the mineral through indirect mechanism. The number of free bacteria in solution and that of attached bacteria became constant over time, suggesting a cooperative mechanism of carrolite bioleaching. Finally, a statistical study of bioleaching of polymetallic concentrate from Kamoya deposit by Taguchi methodology and analysis of variance (ANOVA) was used to investigate the effect of different physicochemical parameters (initial pH, temperature, agitation, pulp density and duration of bioleaching) on the process efficiency. The results obtained from this statistical approach showed the possibility of bioleaching application as an alternative technique for treatment of the polymetallic sulphide ores of the Katanga copperbelt in Democratic Republic of Congo (DRC) but further investigation using thermophilic bacteria should be considered to improve metal dissolution. [less ▲]

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See detailDiffractive straylight rejection system for wide field imagers. Design, performance and application to the STEREO solar space mission.
Halain, Jean-Philippe ULg

Doctoral thesis (2012)

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection ... [more ▼]

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection (CME), generated by violent eruptions on the sun’s surface, that propagates in the heliosphere. The CME brightness however rapidly decreases with the distance from the Sun. To reach a sufficient signal to noise ratio and follow CME away from the Sun, a high sensitivity is therefore required and the unwanted parasitic light (so called straylight) must be minimized. In particular, the Sun disk brightness must be occulted by a highly rejecting baffle system. A multi-edge diffractive baffle can provide a very high level of straylight attenuation for nearly collimated light source. A model of the multi-edge diffractive rejection has been implemented on the basis of the Fresnel diffraction theory. It allows the design and optimisation of such diffractive baffle as function of the instrument and observing geometries. The model was validated on a diffractive baffle mock-up, providing rejection down to an un-precedent level of 10-10 of the input flux. The model of multi-edge diffractive baffle has been applied to the specific configuration of the Heliospheric Imager (HI), on-board the NASA scientific Solar Terrestrial Relations Observatory (STEREO) mission, as part of its overall straylight reduction. The STEREO-HI baffle performance has been validated on a prototype and during the final end-to-end calibration of the flight instrument. After launch, the in-flight straylight level has been quantified, showing a very good correspondence with the on-ground measurements. The straylight evolution has also been shown to be stable during the mission, showing the baffle efficiency does not degrade with the space environment. The STEREO-HI instrument achieves a 10-13 rejection level, or greater, of the solar brightness at the detector pixel level. This instrument is the first wide field space imager viewing from outside the Sun-Earth line, and therefore able to directly follow the propagation of CME from the Sun to the Earth with a high accuracy and sensitivity. Since its launch, it provides unprecedented images and information on solar wind and CME propagation and evolution in the heliosphere. The next generation of wide-field solar imagers are under development for the ESA Solar Orbiter and NASA Solar Probe Plus missions. Their concept benefits from of the STEREO-HI front diffractive baffle system and is based on a multi-edge diffractive baffle to protect their cameras from solar disk brightness. The straylight calibration of these two instruments is in preparation and will be performed at the Centre Spatial de Liège with the tools and methods developed in the frame of the present work. [less ▲]

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See detailRegulation of water flow in the soil-root domain. New tools and methods
Lobet, Guillaume ULg

Doctoral thesis (2012)

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See detailEtude du rôle de l’Hypoxia Inductible Facteur 1 dans les cellules myéloïdes lors d'allergie des voies respiratoires
Toussaint, Marie ULg

Doctoral thesis (2012)

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation ... [more ▼]

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation of innate immunity. Through its action on innate immune cells, Hypoxia inducible factor 1 (Hif1) has been described as a major regulator of inflammatory responses. Airway allergy is a disease whose incidence is in constant increase in developed countries, and the potential implication of Hif1 in innate immune cells during the development of such disease remains currently unknown. Therefore, we were interested in the involvement of Hif1 within innate immune cells in two experimental models of allergic airway inflammation: allergic asthma and recurrent airway obstruction (RAO). Recurrent airway obstruction is one of the most frequent respiratory syndrome that veterinary equine practice has to deal with in our countries. In the case of RAO, the role of the innate immune system, representing the first line of host defense, has not been investigated so far. We have therefore looked at the potential implication of Hif1 in pulmonary innate immune cells during this disease. We have found that, upon allergenic challenge, Hif1 expression within pulmonary innate immune cells was significantly increased in RAO-affected horses in comparison to the control animals. In addition, Hif1 expression was positively correlated to the severity of clinical dysfunctions in RAO-affected horses. We have also shown that the presence of hay-derived LPS could specifically increase Hif1 expression in macrophages. As previously described in other models of inflammation, these results allowed us to show, in a model of RAO, that Hif1 plays a pro-inflammatory role in innate immune cells. Since 90% of innate immune cells of a healthy horse are macrophages, we decided to further investigate the implication of Hif1 in lung myeloid cells. In the second study, for technical reasons, we decided to focus on another model of airway allergy, namely allergic asthma. Although molecular and cellular mechanisms governing asthma development are well characterized, very few information is available regarding the mechanisms that can prevent the development of this disease in healthy subjects. The identification of such mechanisms could be key to understand the origin of development of that epidemic disease as well as to improve the strategies of prevention. We have found that mice that were specifically deficient in Hif1 within myeloid cells (Hif1αm-/-) developed significantly more allergic inflammation in comparison to control mice. We have further shown that these mice had a higher inclination to develop a Th2 response upon allergenic challenge. We then proved that the increase of antigen-specific Th2 responses in Hif1αm-/- mice was the result of increased lymph node dendritic cells migration and antigen presentation. These results suggested that a brake to DC activation by allergens was lost following deletion of myeloid Hif1. Finally, we have found that the specific deletion of Hif1 in interstitial macrophages was indeed responsible of the observed effects. Indeed, we have shown that the TLR-dependent activation of Myd88 in interstitial macrophages induced increased expression of Hif1, thereby increasing IL-10 production from interstitial macrophages. In addition, following HDM stimulation, we observed that Hif1αm-/- interstitial macrophages produced significantly less IL-10 than control interstitial macrophages. Since we have previously shown that interstitial macrophages were capable of blocking dendritic cell activation through the production of IL-10, we proposed that Hif1 was able to control the immunoregulatory functions of interstitial macrophages by regulating their IL-10 production. Our work revealed a crucial role for Hif1 in interstitial macrophages for maintaining the immune homeostasis in the lung. It also suggests for the first time that Hif1 within innate immune cells can display an anti-inflammatory role. As a conclusion, we have been able to assess the importance of Hif1 activation within innate immune cells in the regulation of airway allergy development. We have further proposed that a compartmentalization of pro- and anti-inflammatory functions of Hif1 exists in immune cells. In opposition to what we obtained in the first study and what is currently known in the literature; we have found an anti-inflammatory role for Hif1 in innate immune cells. Indeed, thanks to its role in interstitial macrophages, Hif1 can play a crucial role in the prevention of aberrant immune responses against harmless antigens by preventing allergic sensitization. Hif1 therefore plays a key role in maintaining lung mucosal immune homeostasis. [less ▲]

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See detailDynamique et perspectives de la filière cotonnière du Burundi
Gahungu, Antoine ULg

Doctoral thesis (2012)

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the ... [more ▼]

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the cotton crop continued to flourish as a vertically integrated chain from upstream to downstream in pursuing the objectives of job creation, import substitution and maximizing the added value generated by various cotton products. Since 1993, the cotton is in perpetual decline due to various factors both endogenous and exogenous to reach in 2009 the lowest level in its history. Its competitiveness is challenged by instability of the global market of cotton fiber, policies (subsidies) of large producers (China, India, USA, Pakistan, ...), competition from synthetic textile industry, the prices of agricultural inputs (fertilizers and phytosanitary products) and raw materials for industries, competition for food crops production factors which are already scarce and especially less remunerative producer prices. Survey work on a sample of 120 farms during three seasons (2007/2008, 2008/2009, 2009/2010) as well as interviews with various agents involved in the cotton sector have been conducted to understand the reasons of the decline of the cotton sector and see the adaptation mechanisms implemented in the segment "producers - COGERCO." It appears from these investigations that the cotton is not competitive with food crops. The price paid to growers is not motivating, production costs are expensive and factors of production become increasingly restrictive. COGERCO however, continues to subsidize cotton without benefit. In this context the majority of cotton producers combine beans or cowpeas with cotton to take advantage of subsidies (inputs, management, ...) and other benefits (loans, fields ...) that the company offers to producers without benefit to the company. The latter is in chronic deficit due to poor sector governance which is under pressure of privatization already imposed on other agro-industrial crops of the country (coffee, tea). [less ▲]

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See detailMechanical Processes of a Single Synthetic Molecular Machine Studied by AFM-based Force Spectroscopy
Lussis, Perrine ULg

Doctoral thesis (2012)

Some biomolecules are able to generate directional forces by rectifying random thermal motions. This allows these molecular machines to perform mechanical tasks such as intracellular cargo transport or ... [more ▼]

Some biomolecules are able to generate directional forces by rectifying random thermal motions. This allows these molecular machines to perform mechanical tasks such as intracellular cargo transport or muscle contraction in plants and animals. Although some artificial molecular machines have been synthesized and used collectively to perform mechanical tasks, so far there have been no direct measurements of mechanical processes at the single-molecule level. Here we report measurements of the mechanical work performed by a synthetic molecule less than 5 nm long. We show that biased Brownian motion of the submolecular components in a hydrogen-bonded [2]rotaxane -a molecular ring threaded onto a molecular axle- can be harnessed to generate significant directional forces. We used the cantilever of an atomic force microscope to apply a mechanical load to the ring during single-molecule pulling-relaxing cycles. The ring was pulled along the axle, away from the thermodynamically favoured binding site, and was then found to travel back to this site against an external load of 30 pN. Using fluctuation theorems, we were able to relate the measurements of the work done at the level of individual molecules to the free energy change measured previously by ensemble measurements. Finally, we used dynamic single-molecule force spectroscopy to probe kinetic information of the interaction between the molecular ring and the preferred binding site. The results also demonstrate that AFM-based single-molecule force spectroscopy, which has been widely used to investigate the mechanochemical behaviour of (bio)macromolecules, can be applied to a molecule that is less than 5 nm in its extended form. [less ▲]

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See detailThe effects of a cadmium exposure on poplar plants: A combined proteomic, physiological and biochemical approach to unravel stress-responses in poplar.
Kieffer, Pol ULg

Doctoral thesis (2012)

The industrial revolution in the 1800s and the subsequent industrialization had the consequence of an anthropogenic release of many organic and inorganic pollutants. Among these pollutants, cadmium is ... [more ▼]

The industrial revolution in the 1800s and the subsequent industrialization had the consequence of an anthropogenic release of many organic and inorganic pollutants. Among these pollutants, cadmium is very problematic due to its high toxicity. It can induce significant damage to the vegetation and an accumulation in farmland introduces the pollutant into the food chain. This creates a possible major health risk for humans. Poplar plants, as a member of the Salicaceae family, seem to possess a certain tolerance to this toxic metal and accumulate significant amount in their aerial parts, making poplar a possible candidate for phytoremedation. The metabolic and physiological impact of cadmium have been studied as well in field trials as in controlled laboratory conditions, but mostly in clearly targeted studies focusing on a few key aspects. The recent advent of more global techniques such as transcriptomics and proteomics, make it possible to obtain new results. In the thesis presented here, a proteomic study of the short-term and long-term effects of cadmium on poplar leaf and roots metabolic processes in controlled laboratory conditions was carried out. With the help of this technique, complemented with biochemical and physiological approaches and with morphological observations, it was possible to obtain results on the stress-coping mechanisms underlying an acute first response, but also on the more general adaptation mechanism which make it possible for the poplar plants to tolerate significant amounts of cadmium. Results showed a negative impact on important cell processes like photosynthesis and ATP synthesis and the antioxidant system, explaining the impaired growth. Similar results could be obtained in roots, although the stress seemed much more acute, as evidenced by the stronger accumulation of typical stress proteins (i.e. heat shock proteins). In a final set of experiments a controlled combination of two stresses (cadmium and nonlethal chilling stress; 4°C) allowed separating specific cadmium responses from a more general stress response. Cadmium had a much more severe impact on plant survival when combined with an additional constraints. In this present work, the procedures, results and conclusions obtained are presented in detail. [less ▲]

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See detailModélisation de la transition solide-fluide dans les géomatériaux. Application aux glissements de terrain.
Prime, Noémie ULg

Doctoral thesis (2012)

Geomaterials are present in nature in many forms : solid soil or rock, soft clay, almost liquid mud, etc. Geomechanics deals with the understanding the solid behavior of geomaterials. However, solid ... [more ▼]

Geomaterials are present in nature in many forms : solid soil or rock, soft clay, almost liquid mud, etc. Geomechanics deals with the understanding the solid behavior of geomaterials. However, solid ground can happen, under specific external conditions, to turn into fluid : as for example during mudflows or debris flows. In such a context, our work concerns, in a general way, solid-fluid transition in geomaterials behavior and the development of a constitutive model describing both the solid phase, fluid phase, and the transition between the two. In this framework, we chose to carry out calculations with the FEMLIP numerical method (Finite Element Method with Lagrangians Integration Points) which has shown a strong potential to describe a wide variety of behaviors (including history dependent behavior), in a unique model. Having implemented and validated the first elasto-plastic law in Ellipsis (FEMLIP based code), we have introduced in this code the solid-fluid transition model. This last is based on the evolution, at the failure state detected by the second order work criterion, of the solid elasto-plastic behavior towards a viscous fluid behavior, exhibiting a yield stress. After validation of the solid-fluid transition model in homogeneous cases (considering Plasol elasto-plastic law and Bingham viscous one), we applied this model to the modeling of Sarno and Quindici mudflows (Italy, 1998). [less ▲]

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See detailReflection amplifiers in self-regulated learning
Verpoorten, Dominique ULg

Doctoral thesis (2012)

The project studies how presenting task-related, performance and social context indicators as prompts for reflection to learners can best support meta-learning in self-regulated-learning settings. Meta ... [more ▼]

The project studies how presenting task-related, performance and social context indicators as prompts for reflection to learners can best support meta-learning in self-regulated-learning settings. Meta-learning, for the purpose of this research, denotes the competency to make the experience of learning an object of attention, an object of reflection and an object of conversation. Reflection amplifiers are artefacts that trigger, ease and enhance this activity. Though it strongly relies on and refers to the research dedicated to the germane concept of metacognition, the thesis prefers to use the term "meta-learning" because this involves more than cognition, embracing aspects of the learning experience like semantic intensity, affective dimensions, social relations or context appraisal. Also, the term meta-learning it is more easily understood by practitioners (students and teachers). The PhD-work entails analysing existing solutions and prototyping new tools, investigating their relevance and use conditions, and assessing their effects on meta-learning. The research also includes the development of a pedagogically-grounded rationale and a set of guidelines for the design of such artefacts. [less ▲]

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See detailValorisation du savoir local pour une cogestion conservatoire de l'arganeraie marocaine
Aziz, Larbi ULg

Doctoral thesis (2012)

L’arganeraie est un écosystème particulier disposant d’une biodiversité animale et végétale spécifique dont l’élément central est l’arganier. C’est un arbre multifonctionnel du fait des usages multiples ... [more ▼]

L’arganeraie est un écosystème particulier disposant d’une biodiversité animale et végétale spécifique dont l’élément central est l’arganier. C’est un arbre multifonctionnel du fait des usages multiples qu’en font les populations locales. Il constitue l’élément central du système agraire local car il a configuré et rythmé la vie et les activités des populations. Celles-ci, disposant de nombreux droits de jouissance au niveau de la forêt d’arganier, ont mis au point une gestion communautaire régulant l’accès et le contrôle aux ressources. Cette gestion et le fonctionnement du système agraire témoignent de la possession par ces populations de savoirs et savoirs faire locaux qui perdurent de génération en génération. Toutefois, ces savoirs n’ont pas été assez étudiés pour pouvoir les valoriser. Or, depuis des décennies, les savoirs locaux font l’objet d’intérêt croissant à l’échelle internationale, tant au sein de la communauté scientifique que des ONG internationales. C’est ainsi que cette recherche vise à identifier et à valoriser ces savoirs dans le cadre d’une stratégie de cogestion conservatoire, intégrée et participative de l’arganeraie. Comme outils d’investigation, nous avons eu recours à l’observation et à l’entretien semi directif. Ainsi, nous avons interrogé une centaine de personnes (hommes et femmes) relevant des communes rurales d’Aguerd et de Tidzi (région d’Essaouira). Nous avons aussi interrogé des acteurs institutionnels (agriculture, eaux et forêts, agences, recherche et ONG) en vue de dégager leurs points de vue. Pour l’analyse des données, nous avons utilisé trois méthodes complémentaires: l’analyse descriptive, l’analyse du contenu et l’analyse comparative. Les savoirs locaux identifiés ont été analysés notamment au regard du savoir scientifique. Les résultats ont été comparés entre les deux communes, et au sein de chaque commune ces savoirs sont différenciés selon le genre. Par ailleurs, nous nous sommes basés sur le cadre analytique de Berkes (1999) et sur le modèle IAD Framework d’Orstom (1994) pour pouvoir comprendre la problématique traitée dans toutes ses facettes. Ainsi, nous avons identifié des savoirs relatifs aux trois éléments du système agraire local et à leurs interactions ainsi que ceux relatifs au mode de gestion de la forêt d’arganier et la vie culturelle de la population enquêtée (rites, recettes cosmétiques et de la pharmacopée traditionnelle,..). Il en ressort que l’ensemble de ces savoirs renvoie à une meilleure adaptation de la population à son milieu, à une fine connaissance de l’écosystème et de son fonctionnement. D’autre part, ces savoirs, différenciés selon le genre, montrent que les paysans ne raisonnent pas l’écosystème de manière sectorielle mais dans sa globalité. Par ailleurs, les modes de transmission de ces savoirs sont l’observation, la participation et l’imitation. Cependant, certains de ces savoirs sont en train de disparaître suite aux changements que connaît la zone. Ils doivent donc être requalifiés comme patrimoine culturel à respecter, à conserver, à en contrôler l’accès et à valoriser. D’un autre côté, nos résultats ont montré que l’engouement pour les produits de l’arganier et la flambée de leurs prix à partir de la fin des années 1990, ont entrainé des conséquence socio-économiques au niveau de la zone : changements au niveau des représentations et des comportements des locaux vis-à-vis de l’arbre, apparition de nouveaux acteurs s’enroulant dans des collectifs qui ont beaucoup évolué, mis en place d’un marché peu structuré et pas assez profitable aux locaux, érosion du savoir local, apparition de nouveaux modes d’alimentation, disparition de coutumes et de traditions, etc. ce qui nous a poussé à plaider pour la conception d’une stratégie de conservation de l’arganeraie. Or, de nombreuses actions ont été menées par certains acteurs dans ce sens. Malheureusement, ces efforts sont restés sectoriels, éparpillés, non intégrés et ne prenant pas en compte les nouvelles dynamiques en place. C’est ainsi que nous avons élaboré une proposition de stratégie de cogestion conservatoire de l’arganeraie faisant participer l’ensemble des acteurs, particulièrement les populations locales en valorisant leurs savoirs. Elle se veut cohérente, intégrée et reposant sur les axes suivants : la participation et la concertation entre les différents acteurs, l’assurance d’une bonne gouvernance locale (au sein des structures et entre les partenaires), l’appropriation de l’aménagement de l’arganeraie en valorisant les savoirs locaux identifiés et en appuyant la structure de l’agdal, la structuration du marché et la relocalisation de la plus-value (IGP argane), la promotion du tourisme rural, la réalisation d’actions d’accompagnement. Par ailleurs, cette stratégie doit s’inscrire dans le cadre d’un développement local plus global pour pouvoir prendre en compte l’aspect temporel dans les évolutions des dynamiques en cours. [less ▲]

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See detailOptimisation de l'utilisation des ressources en eau du bassin du Kou pour des usages agricoles
Traore, Farid ULg

Doctoral thesis (2012)

Water is a priceless natural resource very sensitive to external factors and environmental degradation. It becomes more valuable as competing uses multiply. Therefore, integrated and cooperative water ... [more ▼]

Water is a priceless natural resource very sensitive to external factors and environmental degradation. It becomes more valuable as competing uses multiply. Therefore, integrated and cooperative water resources management is essential within a watershed. The Kou watershed (Burkina Faso) has significant water resources which are divided between domestic (water supply, etc.), agricultural (irrigation) and industrial uses. The hydro-agricultural context of the Kou watershed is marked by a perennial river, along which are located several agricultural areas. Over time, once satisfying water needs degraded to irrigation water deficits, mainly due to a reduction in water supply and an increase in irrigated farmland. Irrigation water deficits are mostly encountered in the more downstream agricultural areas. The socio-economic context is characterized by a growing trend for highly profitable and water consuming crops (e.g. banana). This further increases the irrigation water deficits, as well as the upstream-downstream water-sharing inequalities. In the context of the study area, the main factor that may influence the agricultural water withdrawals is the farmers' production system. The main hypothesis of the study was to verify whether these agricultural production systems could be the lever to optimize irrigation water use. The methodology of the study was to provide a sufficiently accurate knowledge of the water management system, so that improvements could be proposed. A decision support tool based on the ‘multi-agent systems’ approach (MAS) was developed in order to provide an answer to the problems of the study area’s water management by simulating management scenarios. The findings of the study showed (using the MAS tool) that through actions on agricultural production systems it is possible to optimize irrigation water withdrawals. Within the production systems, it is mainly changes in irrigation practices that have led to an optimization of the water management. Finally, the study showed that the use of MAS in resolving agricultural water management issues in the Kou watershed could be the starting point for a new approach in water management. This approach allows the effective integration of the consequences of farmers' decisions regarding water management. More generally MAS-based natural resources management tools provide a common representation of the environment within a model that can help raise awareness concerning a better management of these natural resources. [less ▲]

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See detailLong-term study of biogenic volatile organic compound exchanges in a forest ecosystem
Laffineur, Quentin ULg

Doctoral thesis (2012)

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical ... [more ▼]

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical characteristics. In particular, VOCs are precursors in the formation of ozone and sec-ondary organic aerosols. Isoprene and monoterpenes dominate the total VOC emissions, and methanol is one of the most abundant atmospheric VOCs due to its longer half-life than the other two. The main objective of this thesis was to investigate (using the eddy covariance technique and a proton-transfer-reaction mass spectrometer) the mechanisms of VOC (isoprene, monoterpene and methanol) emission and/or deposition at the scale of a temperate climate forest ecosystem (Vielsalm, Belgium) comprising several species (Fagus sylvatica, Abies alba, Picea Abies and Pseudotsuga menziessi). The eddy covariance technique is very suitable for studying VOC emission/deposition mechanisms at ecosystem level as it does not interfere with the functioning of the ecosystem and it has very good temporal resolution (half an hour). It was used for several months at the Vielsalm site without any major interruption to the measurements. The first measurement period ran from early July to late November 2009 and the second from late March to late November 2010. As well as measuring the VOC exchanges by eddy covari-ance, the climate parameters controlling the exchange mechanisms were also measured. During both these periods the methanol, acetaldehyde, acetone, isoprene, methyl vinyl ke-tone/methacrolein, monoterpene, acetic acid (2010) and formic acid (2010) fluxes were meas-ured. The highest emission levels observed were isoprene and monoterpenes along with methanol, which unlike the first two also showed depositions. The thesis therefore naturally focused on studying these three fluxes, in view of the important role played by these three compounds in atmospheric chemistry and hence the scientific community’s interest in refining the parametrisation of these compounds’ ecosystem/atmosphere exchange models. The study of the isoprene, monoterpene and methanol fluxes has been written up in three original articles which form the main body of this thesis. Because of the heterogeneity of the ecosystem studied, the first essential study concerned the identification of VOC-emitting species. This was done with the aid of a flux footprint model combined with a map of the species occurring on the site. This analysis showed that the main monoterpene emitter was Fagus sylvatica followed, to a lesser extent, by Abies alba, Picea Abies and Pseudotsuga menziessi. In contrast to the literature, the analysis showed Abies alba to be a probable isoprene emitter but the presence of Picea Abies, a known isoprene emitter, ruled out absolute certainty on that point. The isoprene fluxes were observed by day only, unlike the monoterpene fluxes which were observed both day and night. Diurnal flux analysis clearly showed temperature and light to be the two main variables controlling emissions. Combining this analysis with a study of the close relationship between isoprene/monoterpene emissions and photosynthesis revealed the plants’ de novo biosynthetic production mechanisms, an original aspect at ecosystem scale. From the occurrence of nocturnal monoterpene emissions it was possible to determine that de novo monoterpene production emitted directly into the atmosphere (as in the case of isoprene) was not the only source of the emissions observed. Withdrawals from monoterpene sinks located in plant organs or in the soil can also be monoterpene sources. Studying the relationship between isoprene/monoterpene fluxes and light, distinguishing between cloudy and sunny conditions, showed that for the same light intensity the emissions were higher in cloudy con-ditions than in sunshine. Similarly, a study of the relationship between isoprene fluxes and photosynthesis in cloudy/sunny conditions suggested that de novo isoprene production is greater in leaves above the canopy than in leaves within the canopy. Long-term measurement of isoprene and monoterpene emissions enabled seasonal changes in the mechanisms observed to be studied and more fully understood. As well as providing an understanding of the mechanisms, this research also resulted in quantification of the seasonal changes in the key parameters for modelling isoprene/monoterpene emissions. Methanol exchanges were generally positive (emissions) by day and negative (depositions) at night. Overall, methanol depositions were predominant in summer and autumn but in the mi-nority in spring. On average, the Vielsalm site behaved like a methanol sink, which contradicts all the other research published to date. An original model was developed for identifying the mechanisms responsible for short-term and long-term methanol emissions/depositions. The consistency between the measurements and the model simulations suggested that the main processes controlling methanol exchanges in summer could be attributed, in the short term, to (water-soluble) methanol adsorption/desorption occurring in the films of water on leaf surfaces and/or on the soil surface and, in the long term, to methanol destruction by a biological and/or chemical degradation process also occurring on the surface of leaves and/or the soil. A study of the difference between the measurements and the model, in spring, indicated the possibility of biosynthetic methanol production by the plants. This production was apparently controlled mainly by temperature, but it could not be shown in summer when methanol adsorption/desorption processes dominated. The literature on ecosystem-atmosphere exchanges of isoprene, monoterpenes and, to a lesser extent, methanol is extensive. Nevertheless, what makes this research original is the spatio-temporal scale used. We are in fact working at ecosystem scale, and not at leaf or branch scale as in most other cases. Moreover, our measurements cover a timescale from half an hour to a full growing season, which is rarely found in the literature. This has resulted in a better under-standing of these compounds’ production and exchange mechanisms. To be precise, the methanol flux study is currently unique in its description and understanding of the deposition mechanisms. [less ▲]

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See detailAlternative possible à la production traditionnelle du coton en Afrique dans une perspective de développement durable? Le cas du système de production biologique et équitable au Mali
Dembele, Kouloumegue ULg

Doctoral thesis (2012)

SUMMARY The general objective of this work is to analyze the viability of the culture of organic fair trade cotton in comparison with that of conventional cotton. The study was conducted with a sample of ... [more ▼]

SUMMARY The general objective of this work is to analyze the viability of the culture of organic fair trade cotton in comparison with that of conventional cotton. The study was conducted with a sample of 45 farms with 15 farms per system, and following a systemic approach at three levels: the land of cotton cropping systems based on cotton and across the operation. At the cotton, whatever the socio-economic producer, cotton compared to conventional cotton has lower average yields, work time higher and smaller plots (0.85 ha production organic fair against 2.35 and 1.76 ha respectively in conventional production calendar and thresholds. organic fair trade cotton generates less revenue because of smaller plots. Nevertheless, the cotton is organic fair identified two broad categories of farms: farms with high levels of resources have an important livestock farms and poor with little means of production, for which the organic fair trade cotton is one of the few alternatives for income money. It should be noted that the level of these poor farms, it is often women and dependent operations manager who practice organic cultivation of cotton. Only farms with high level of resources that have a herd can derive significant profits from the cultivation of organic fair trade cotton. The alternative organic fair this effect allows access to land and access to the culture of cotton formerly marginalized groups, including women, unlike conventional cotton where only the manager manages the cultivation of cotton. There is thus improving the status of women. However, the lack of sustained management of soil fertility and nutrient compromises obtaining better yields - which is a key success factor to be and remain competitive. Level of cropping systems, comparative analysis of the performance of cropping systems confirms that productivity and valuation levels of the working day cultures and cultivation systems based on organic fair trade cotton are lower than obtained by conventional production. At the farm level, conventional production systems produce between 29% (SPCca) and 43% (SPCs) more grain from the organic production system. Reflecting the fragility of food security in the region in case of massive conversion to organic production. Regarding environmental sustainability, it appears that the most important contribution of organic cotton is safe for human health and the environment of the inputs used. [less ▲]

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See detailFirst-principles and experimental studies of hexagonal YMnO3 single crystals and epitaxial films
Prikockyte, Alina ULg

Doctoral thesis (2012)

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk ... [more ▼]

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk and in thin film forms. Yttrium manganite belongs to the class of ABO3 compounds. Most theoretical studies of ferroelectricity to date were concentrated on cubic perovskite ABO3. Yttrium manganite is hexagonal and is an improper ferroelectric. We were interested to study theoretically and experimentally how these two features behave in thin film form. Our study is organized as follows. [less ▲]

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See detailDevelopment of a transmission model of Murid herpesvirus 4
François, Sylvie ULg

Doctoral thesis (2012)

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural ... [more ▼]

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural condition has been limited by the fact that no experimental transmission model exists. Establishment and characterization of a model of transmission are therefore critical points to evaluate strategies of interference with the epidemiological cycle of gammaherpesviruses. We are studying Murid herpesvirus 4 (MuHV-4) which has originally been isolated from naturally infected bank voles (Myodes glareolus). Although serological data indicate that closely related strains are present in wood mice (Apodemus sylvaticus) and domestic mice (Mus musculus), no experimental transmission of MuHV-4 has been demonstrated in laboratory mice, the classically used in vivo model. The objective of this work was therefore to fill this gap. In a first study, we performed a comparative characterization of the infection by MuHV-4 in mice and bank voles. Our results showed that the infectious process, the pathology and the latency establishment are similar in the two species, even if replication is quantitatively lower in bank voles than in mice. It therefore appeared that, Mus musculus represents a suitable host for studying gammaherpesvirus pathogenesis with MuHV-4. These results have been published in Journal of General Virology (J Gen Virol. 2010 Oct;91(Pt 10):2553-63). In a second study, thanks to in vivo imaging, we have been able to observe, for the first time, transmission of MuHV-4 in mice. We firstly showed that MuHV-4 reexcretion occurs in the genital tract of female mice at a period by which latency is considered as established. Ex vivo imaging, histology and PCR allowed us to demonstrate the presence of viral genomes in vaginal tissues and to localize viral replication at the external border of the vagina. We also demonstrated the transient and repetitive presence of infectious viruses in the vaginal cavity. Secondly, we demonstrated the implication of sexual steroid hormones in this re-excretion process. Indeed, we analyzed the infection of untreated mice, ovariectomized mice and ovariectomized mice complemented with estrogens and/or progesterone. These analyses revealed a positive role of estrogens in the observed re-excretion. Finally, based on these results, we tested MuHV-4 transmission in mice by creating different epidemiological conditions. In the conditions tested, vertical transmission did not occur, nor did horizontal transmission between individuals of the same gender. In contrast, we were able to observe sexual transmission to naïve males by serology, in vivo imaging and quantitative PCR. In conclusion, this work has on one hand demonstrated the quality of mice as an in vivo model for MuHV-4 studies and, on the other, it has shown for the first time the existence of re-excretion and sexual transmission of MuHV-4 amongst laboratory mice. The results of this work should therefore have implications for the study of gammaherpesviruses, but also more generally for the study of sexually transmissible infections. [less ▲]

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See detailLe nationalisme algérien et ses diverses expressions dans l'immigration en France métropolitaine entre 1945 et 1965
Abssi, Marion ULg

Doctoral thesis (2012)

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des ... [more ▼]

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des différentes organisations nationalistes algériennes représentées en métropole, et des conflits ayant opposés les Algériens aux Européens mais aussi et surtout les Algériens entre eux durant toute la période considérée. [less ▲]

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See detailIonosphere Modelling for Galileo Single Frequency Users
Bidaine, Benoit ULg

Doctoral thesis (2012)

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ... [more ▼]

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ionospheric effect affecting the signal propagation from the satellites. This propagation is delayed by the free electrons in the atmosphere so that the navigation signals appear to travel distances larger than actual ones by 7 m on average. Hence this delayed propagation deteriorates the positioning accuracy deemed on a 10−m level for mass-market applications mainly involving single frequency users. Tomorrow the European navigation system Galileo will offer a new mitigation strategy to single frequency users. This strategy will rely on the NeQuick ionospheric model and associated broadcast information. To be properly implemented, it must be extensively described to future Galileo users. These users will also wonder about its effectiveness in accounting for the ionospheric delay. The PhD research covered by the present thesis has built on Belgian expertise in ionosphere monitoring to investigate the NeQuick model and its use for Galileo. It began with the collection and handling of ionosphere measurements including GPS data. It analysed various situations at different places in the world encompassing a whole year (2002). This PhD thesis provides the ins and outs of the Galileo Single Frequency Ionospheric Correction Algorithm. It gathers an algorithm description, a performance evaluation and a variant investigation. In the shape of a paper collection, it discloses many figures as visual entry-points into the juxtaposed text and includes many references allowing to dig into the details. The algorithm performances are usefully characterised both in terms of delay mitigation and positioning accuracy. On the one hand, the residual ionospheric delay reaches 31% for the chosen sites and year. On the other hand, the positioning accuracy amounts to 6 m horizontally and 9.3 m vertically. The performance evaluation allowed to emphasise several aspects of the Galileo ionospheric correction. This correction depends largely on the modelling of the topside, the upper part of the ionosphere, which hosts more complex physical processes. It owes its good performances to data ingestion, the model adaptation technique to actual measurements underlying the Galileo algorithm. It does not necessarily provide highly correlated correction levels in terms of delay on the one hand and positioning on the other. It enables the definition of alternative regional procedures following a compatible design but coping with its weaknesses. The present thesis paves the way for future work related to ionosphere modelling for Galileo single frequency users. It supplies comparative information for the algorithm assessment in the framework of successive phases of Galileo deployment. It establishes a conceptual basis for an Assisted Ionospheric Correction Algorithm (A-ICA) disseminating more flexible ionospheric information thanks to the integration of Global Navigation Satellite Systems and telecommunications. [less ▲]

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See detailEtude hydrogéologique du système aquifère du horst de Diass en condition d’exploitation intensive (bassin sédimentaire sénégalais) : apport des techniques de télédétection, modélisation, géochimie et isotopie
Madioune, Diakher Hélène ULg

Doctoral thesis (2012)

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante ... [more ▼]

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante destinée à l’Approvisionnement en Eau Potable (AEP) de la ville de Dakar et des localités de Sébikotane, Pout, Mbour ainsi que leurs besoins industriels et agricoles. La configuration géométrique du système est caractérisée par quatre failles majeures délimitant un horst où affleure la nappe du Maastrichtien gréso-calcaire et sablo-gréseux du compartiment de Diass encadrée par les compartiments calcaires affaissés de Sébikotane et de Pout qui hébergent la nappe captive à libre du Paléocène. L’exploitation de ce système a progressivement évoluée pour atteindre actuellement plus de 109000 m3/j environ avec cinq principaux centres de captage. Cette exploitation intensive a provoquée une baisse continue du niveau des nappes, un changement dans le régime des flux et une salinisation dans les zones de Sébikotane et de Mbour. Ainsi donc, il est nécessaire d’étudier les caractéristiques des aquifères notamment, leurs relations hydrauliques verticales et latérales. Cependant, cette étude reste difficile en raison de la complexité de la configuration géométrique du système et des pompages intensifs. La présente étude vise à contribuer à une meilleure compréhension du fonctionnement hydrodynamique du système pour une bonne gestion durable des ressources en eau. Plus précisément, il vise à déterminer : (1) le comportement spatio-temporel de l’hydrodynamisme et de l’hydrochimisme du système en rapport avec les pompages, (2) la recharge actuelle des eaux souterraines, (3) les zones potentielles de recharge nécessaires au calcul du bilan. Pour atteindre ces objectifs, une approche multidisciplinaire comportant une étude piézométrique, hydrogéochimique, d’estimation de la recharge spatialement distribuée et de modélisation a été utilisée. Les variations spatio-temporelles de la piézométrie depuis les années 1960 en rapport avec la configuration hydrogéologique combinées aux données chimiques et isotopiques ont été considérées pour fournir une meilleure compréhension du fonctionnement hydrodynamique du système et établir le modèle conceptuel de circulation des eaux. Les méthodes de Thornthwaite et Penman sont utilisées pour estimer la recharge qui a été spatialement distribuée sur les zones potentielles de recharge. Les enseignements clés tirés de ces différentes approches sont utilisés comme paramètre d’entrée du modèle hydrogéologique 3D développé et calibré en régime permanent et transitoire pour les périodes 1960-1971 et 1971-2009 respectivement. Les résultats montrent l’influence prépondérante des pompages sur le niveau piézométrique favorisant ainsi la drainance verticale et latérale vers les captages. Les données chimiques et isotopiques reflètent la dynamique du système. Les faibles teneurs en tritium et en 14C montrent une absence de recharge actuelle et une prédominance d’eaux anciennes dans le système. Cependant, la présence d’eau tritiée au droit de quelques forages indique un mélange avec des eaux récentes par drainance verticale descendante et/ou par écoulement latéral. Le fonctionnement hydrodynamique dérivé de ces résultats montre que le réservoir fonctionne comme un système aquifère multicouche avec des compartiments interconnectés par des failles qui favorisent des échanges de flux. L’aquifère du Quaternaire est alimentée par l’infiltration des eaux de pluie particulièrement dans la zone de Mbour (1) ; cette aquifère est drainé par les nappes profondes du Paléocène et du Maastrichtien (2) ; ce dernier draine le Paléocène (3), les écoulements latéraux se font du Maastrichtien de Diass vers le compartiment de Pout Sud et à partir du compartiment de Thiès vers le compartiment de Pout à travers les failles de Pout et de Thiès respectivement (4). [less ▲]

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See detailAdaptations structurales et fonctionnelles aux températures extrêmes au sein de la famille des alpha-amylases chlorure-dépendantes
Cipolla, Alexandre ULg

Doctoral thesis (2012)

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été ... [more ▼]

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été initiées et publiées. La première est basée sur la "mésophilisation" de l’α-amylase psychrophile AHA, issue de la bactérie Antarctique Pseudoalteromonas haloplanktis. L’ajout d’interactions faibles et d’un pont disulfure présents chez son homologue mésophile PPA de Sus scrofa et absents chez AHA ont permis de construire deux mutants multiples stabilisés, Mut5 et Mut5CC. Ces quatre enzymes ont été étudiées sur base de leur stabilité, de leur activité et de la perméabilité de leur structure protéique. L’étude des cinétiques de renaturation/dénaturation d’AHA, Mut5 et Mut5CC a permis de déterminer l’origine cinétique du gain de stabilité liée à l’ajout d’interactions faibles et du pont disulfure chez AHA. Il en résulte que Mut5 et Mut5CC ont effectivement été stabilisés mais en contrepartie ils ont perdu l’optimalisation de l’activité à basse température observée chez AHA. De plus, la perméabilité de leur structure protéique s’est réduite, se rapprochant de celle de PPA. L’origine du gain de stabilité est liée à une diminution des cinétiques de dépliement sans modification des cinétiques de repliement. Non seulement ces résultats démontrent l’importance du rôle des interactions faibles dans l’adaptation thermique des protéines mais de plus, ils démontrent la synergie entre celles-ci. La seconde étude a pu être développée par la découverte d’une α-amylase chlorure-dépendante thermophile TFA issue de l’actinomycète Thermobifida fusca et par la production de l’α-amylase chlorure-dépendante mésophile ectotherme DMA de Drosophila melanogaster. Ainsi avec AHA et PPA respectivement comme représentants psychrophile et mésophile homéotherme, nous pouvions couvrir l’ensemble des températures physiologiques/environnementales connues. Nous avons pu mettre en évidence le continuum des propriétés physico-chimiques observées (activité, stabilité, affinité pour le substrat…) mais aussi que l’énergie thermique de l’environnement influence grandement l’activité enzymatique qui ne serait pas contrebalancée par les mécanismes adaptatifs. L’influence de la température sur l’activité a mis en évidence la plus faible dépendance d’AHA par rapport à TFA. Ces travaux ont permis d’améliorer notre compréhension des mécanismes moléculaires liés à l’adaptation thermique des protéines et du rôle joué par les interactions faibles dans cette adaptation. Ils ouvrent aussi la voie à de futures recherches visant à analyser par d’autres méthodes la flexibilité de la structure protéique et à cristalliser TFA pour étudier d’un point de vue structural le continuum des propriétés physico-chimiques mis en évidence au cours de ce travail. [less ▲]

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See detailPresent and future Greenland ice sheet surface energy balances with the help of the regional climate MAR model
Franco, Bruno ULg

Doctoral thesis (2012)

See enclosed abstract-and-contents.pdf

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See detailStructure and Lattice Dynamics of Thermoelectric Complex Chalcogenides
Bauer Pereira, Paula Beatriz Lee ULg

Doctoral thesis (2012)

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe ... [more ▼]

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe, SnTe and GeTe. Synchrotron radiation studies including high energy X-ray di raction and nuclear inelastic scattering, and macroscopic measurements of heat capacity and elastic constants were performed. A new resonant ultrasound spectroscopy setup with capable of performing measurements from room temperature to 1073K was built for mechanical characterization of the thermoelectric alloys at their working temperatures. The rst chapter presents a brief review of relevant information on thermoelectricity and on the materials under study. The characterization methods including heat capacity, resonant ultrasound spectroscopy, X-ray di raction and nuclear inelastic scattering are introduced. Not as an exhaustive review, but rather in order to give the reader a basic level of understanding and a sense of the acessible information. The introduction is followed by three chapters which address the experimental studies of lattice dynamics in chalcogenide alloys. Chapter 2 describes the lattice dynamics in the compounds GeTe, SnTe and PbTe studied by 119Sn and 125Te nuclear inelastic scattering. The obtained partial density of phonon states were compared with published theoretical calculations, and the resulting vibrational properties were found to be in good agreement with these reports. Additionally, the phase purity and structure were characterized by high energy X-ray di raction. The atomic arrangement, rhombohedral for GeTe and cubic for SnTe and PbTe, is seem to a ect the density of phonon states, with the NaCl-type structure having a softer character in comparison with the rhombohedral structure. In Chapter 3, the lattice dynamics of a polycrystalline AgSbTe2 sample was investigated by 121Sb and 125Te nuclear inelastic scattering, at low temperatures. For this compound, the phonon modes have energies below 25meV and a sound velocity of vs =1490(30) m/s was determined. A simple temperature independent estimation of the lattice thermal conductivity of AgSbTe2 yielded L =0.50 0.05Wm􀀀1K􀀀1. The low Debye temperature, D =150(15)K combined with the short phonon lifetime and the low sound velocity are found to be key factors for the low thermal conductivity in AgSbTe2 and are related to the good thermoelectric performance in AgSbTe2 and AgSbTe2containing systems. Chapter 4 is dedicated to the study of the average and local structure in bulk AgPb18SbTe20 alloy, by a combined Rietveld and Pair Distribution Function analysis. The strong in uence of the synthesis conditions on the lattice parameters and on the composition and the concentration of nanoclusters in LAST-18 is con- rmed. Moreover, the 121Sb and 125Te partial density of phonons states were obtained by nuclear inelastic scattering in order to separately characterize the lattice dynamics from the matrix and the nanoinclusions. Additional characterization of the elastic properties and lattice governed properties were performed by resonance ultrasound spectroscopy, heat capacity and thermal expansion measurements. The nal chapter is dedicated to the resonant ultrasound spectroscopy technique, and the process of building up this bu er-rods high-temperature measurement system are presented. Advantages and disadvantages, as well as limitations and di culties are discussed. Using the \mode-tracking" method, the mechanical behavior of a PbTe and a Niobium sample, from room temperature to 523K and from room temperature to 973 K, respectively, were investigated. [less ▲]

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See detailA multiaxial constitutive model for concrete in the fire situation including transient creep and cooling down phases
Gernay, Thomas ULg

Doctoral thesis (2012)

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need ... [more ▼]

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need for proper concrete model remains a very challenging task in structural (fire) engineering because of the complexity of the concrete mechanical behavior characterization and the severe requirements for the material models raised by the development of performance-based design. Methodology - The thesis opted for a phenomenological approach for modeling the thermo-mechanical behavior of concrete. The specifications of the model are based on the study of published experimental data of concrete samples tests and on the specific needs related to the applications in structural fire engineering. With these specifications in mind, a state of the art review of concrete models is conducted in order to choose the general theoretical framework that best fits the criteria for the development of the new model. The thesis presents the theoretical development of the model and its numerical implementation in a finite elements software. Numerical simulations of experimental tests are then performed to verify that the model satisfy the specifications. Findings - The combination of elastoplasticity theory and damage theory allows to develop a phenomenological model suitable for concrete behavior modeling within the pragmatic and robust theoretical framework of continuum constitutive models based on smeared crack approach. The state of damage in concrete, assumed isotropic, is modeled by means of a fourth order damage tensor to capture the unilateral effect. When complex performance-based situations are considered, the effect of transient creep strain at high temperature must be taken into account by an explicit term in the strain decomposition. A generic transient creep model is therefore developed based on experimental data and the model is calibrated to yield the same results as the Eurocode implicit model in simple prescriptive situations. The concrete model comprises a limited number of parameters that can be identified by three simple tests; besides, a standard set of values to be used in predictive calculations is clearly defined for these parameters. Numerical simulations can deal with all stress states as the model is developed as fully three-dimensional. A large number of examples highlight the capabilities of the model that range from the modeling of sample tests to the modeling of large scale composite structures developing membrane action. Limitations – Due to the assumption that damage and plasticity are driven by the same internal variables in the model, a limitation appears for capturing the concrete post-peak behavior in highly confined stress states. This assumption allows for reducing the number of parameter but it restrains the domain of applicability of the model; it is suggested to adopt a different approach if the behavior in multiaxial compression at high confinement level has to be accurately captured. Another limitation of the model is related to the localization issue, which is only partly addressed in this work by means of the regularization of the crack energy. Further works should bring a more elaborated response while considering the case of reinforced concrete structures, in which numerous cracks develop. Finally, several simplifying assumptions have been adopted to restrain the scope of the research; for instance, the phenomenon of spalling has not been considered. Practical implications - The thesis includes implications for the development of advanced numerical tools for the simulation of concrete structures at ambient temperature and at high temperature. The use of such advanced tools in the design may lead to significant reduction in the building costs and to improved robustness of the structures. Value – The thesis contributes to fulfil an identified need to make available proper constitutive concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. Special care is given to the numerical robustness of the model and to the clear definition of the material parameters as the model is intended to be used by structural (fire) engineers in real applications. [less ▲]

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See detailThe Unharnessed World: Janet Frame and Buddhist Thought
Gabrielle, Cindy ULg

Doctoral thesis (2012)

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage ... [more ▼]

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage point of its indebtedness to Eastern epistemologies, and to Buddhism in particular. Even though it is possible to establish links between an author and a given system of thought (Heidegger’s for instance) without necessarily buttressing the comparison from a factual perspective, in this case, the author’s (auto-)biography, her fiction and letters, as well as the circles of Buddhists or Buddhist-sympathizers in which she evolved at a given time, all testify to the fact that a direct encounter between Janet Frame and Buddhism did occur. It can thus be affirmed that, just like W.B. Yeats, C.G. Jung, Heidegger and many others before her, one of the most striking personalities of the 20th century was drawn eastward. The relevance of this study to Janet Frame scholarship resides not only in its politicized angle of approach but also, more importantly, in the fresh light it sheds on entire segments of the Framean corpus which have tended to remain obdurately mysterious; this includes passages centering on e.g. the existence of a non-dual world, a reality un-harnessed by the partial categories of empirical thinking, on a character’s sudden embrace of a non-ego-like self, or on the jolting back of distracted individuals into an awareness of their physical reality in ‘this’ profane world. On the whole, and despite this apparent profusion of themes, my concern is to show that these obscure passages, as well as many other key moments in the narratives, all coalesce into a systematic deconstruction of empirical thinking and its point of anchorage in a discriminating kind of consciousness, both notions forming excellent points of entry into virtually all the texts produced by Frame. Through a careful mapping of the impact of discriminating habits of thought on the self’s place of being in the world and perception thereof, this work clarifies, or rather reconstructs, the narratological architecture of the studied texts – especially the novels – quite apart from the somewhat restrictive view, held in some circles of literary criticism, that they are mazes of random turnabouts and dead-ends where narrotological playfulness is valorized for its own sake. To provide just one example of how a study of Janet Frame via Buddhist thought facilitates the navigation of the author’s intricate novels, the idea in Buddhism that the artist is the bow that shoots the arrows, but then s/he is the target also, is a useful starting point for analyzing the seminal “Jan Godrey” (one of Frame’s best known short stories) in which a terrified author-figure finally allows her creature of words, described as an alien inside, to take full control of the speaking position. A contrario, Thora Pattern’s willingness in The Edge of the Alphabet to trap her creation within neat academic cages of words (as she calls them) spawns images of a hellish self-scape of containment which translate in an endless regression of framed frames since her attitude is paralleled by some of her own creatures of words and by the Christian God Himself – each at his or her level of being and of influence. But that is not all for, in a last turn of the screw, and pace the critics who diminish their roles in the narrative, Thora’s characters rebel against their creator, and they succeed in jamming her creative incarcerating mechanisms so that, by the end of the novel, the author-figure is no longer able to exist without the not-self. This dialectics of un/framing, in which a discriminating consciousness battles against the invading otherness of the non-dual, unharnessed world in all its manifestations, is one which typically informs the Framean corpus although, of course, the architecture of enactments it gives birth to is as varied as it is unpredictable. The idea, which Frame shares with Buddhism or with Nietzsche (who, incidentally, owes an intellectual debt to Buddhism), that most of the human existence is characterized by the “will to power,” i.e. by the drive to take full possession of one’s chosen place of being, is rather unflattering for her fellow human beings. In another sense, the author’s conception of our (in-)humanity as being made up of an accretion of egotistic habits that can be unlearned certainly explains why, in her oeuvre, a liberation from totalizing structures demands an encounter with the negative of place, of identity, of vision, of sound, of fullness, of shape, of well-worn mind-routes and, as we saw in the last chapter, with the negation of negation. Often, it takes no less than a rebellion of the supposedly harnessed reality to disorient a protagonist’s dualistic bearings or to jam an artist’s incarcerating mechanisms; and this, in part, accounts for the extreme physicality encoded in a fiction replete with moments of thumping or bashing – indeed with the promise of a cut finger. Still pondering the centrality of ‘unframed’ or ‘ego-less’ modes of being, each of the nine chapters that constitute this work aims at countering the oft-recurring claim that Frame’s oeuvre is studded with traces of a ‘beyond’ which no character can ever approach because ‘one cannot explore beyond’. By this definition, each of the questing selves that clutters the author’s haunting universe is condemned to failure beforehand, as it were, while concomitantly the Framean text itself is deemed to be bleak, defeatist, even nihilistic. Therefore, it is of the utmost significance that a Buddhist navigation of Frame’s texts should lead one to the conclusion that this unharnessed world which human beings are often unable to apprehend and embrace has always been right under their nose so that, between ‘this’ world of limited perceptions and ‘that’ world of the beyond, the boundary is as thick or as thin as the walls of a self-made conceptual prison. Indeed, whenever the aspect of the intellect that filters perceptions into mutually excluding categories fails to function, or is willingly jettisoned by a protagonist, s/he finds a place of subjective arrival in, and sees, this supposedly unknowable ‘beyond’. Thus, possibly against the grain of mainstream criticism, this study argues that Janet Frame constantly seeks ways through which the infinite and the Other can be approached, though not corrupted, by the perceiving self, and that she found in the Buddhist epistemology a pathway towards grasping such alterity. [less ▲]

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See detailSubstrats cérébraux des processus moteurs automatiques et inconscients
D'Ostilio, Kevin ULg

Doctoral thesis (2012)

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See detailLe terrorisme à motif religieux en Turquie : Recrutement, profils et motivations des membres du Hizbullah turc
Gülver, Murat ULg

Doctoral thesis (2012)

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance ... [more ▼]

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance. Plus de dix organisations terroristes, se basant sur une idéologie religieuse, ce sont organisées sur le territoire turc dans le but de changer le système politique et pour fonder un État islamique. Dans cette recherche, nous avons examiné le cas du Hizbullah turc, en tant que la plus grande et la plus violente organisation terroriste à motif religieux en Turquie. Cette étude a exploré d’abord les méthodes de recrutement du Hizbullah, ensuite les profils de ses militants et enfin les motivations individuelles et les facteurs, qui se trouvent à la base de la radicalisation religieuse en Turquie. Pour ce faire, l’examen quantitatif et qualitatif de données originales comble les principales lacunes dans la recherche sur le terrorisme à motif religieux et donne des indications pour de futures recherches criminologiques et de politiques de sécurité préventives. Dans cette étude, pour examiner et comprendre le recrutement, les profils et les motivations des membres du Hizbullah, nous avons utilisé essentiellement deux sources : les autobiographies des militants eux-mêmes et les entretiens semi-structurés avec des policiers spécialistes du terrorisme à motif religieuse, ainsi que des desservants du culte islamique, qui ont une expérience dans les régions où le Hizbullah était actif. Cette recherche entend apporter une contribution significative à la compréhension des motivations individuelles des militants du Hizbullah, à l’identification des caractéristiques des membres, et à la définition des méthodes de recrutement de l’organisation. Elle propose en outre de nombreuses informations aux organisations de sécurité pour la lutte antiterroriste. [less ▲]

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See detailLa protéine JNKBP1 agit comme un régulateur négatif de la signalisation de NOD2 en inhibant son processus d’oligomérisation
Lecat, Aurore ULg

Doctoral thesis (2012)

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui ... [more ▼]

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui induit les différentes cascades de signalisation conduisant à l'activation de NF-κB, des MAPKs et de l'autophagie. Ces voies contribuent à une réponse immunitaire innée et adaptative efficace. La perte de fonction des mutants NOD2 a été associée à une plus grande susceptibilité à la maladie de Crohn, ce qui souligne l'importance physiologique de la régulation de l'activité de NOD2. Nous avons effectué une étude par une approche protéomique pour rechercher de nouveaux régulateurs de NOD2. Nous avons généré un modèle cellulaire pour cette étude, les cellules HEK293GNV. Nous avons identifié plusieurs nouveaux partenaires de NOD2, dont la protéine JNKBP1 (c-Jun N-terminal kinase binding protein 1), une protéine scaffold caractérisée par un domaine WD40 en amino-terminal. Nous avons aussi débuté la caractérisation d’autres protéines appartenant aux complexes NOD2 purifiés comme ROCK2 (Rho activated kinase 2) et HDAC5 (Histone deacetylase 5). Au vu de nos premiers résultats, les protéines ROCKs sembleraient être des activateurs de la voie NOD2. Nous nous sommes principalement consacrés à l’étude de JNKBP1 qui a été identifiée, en 1999, comme un partenaire et un régulateur positif de JNK. Nous avons montré que JNKBP1 via son domaine WD40, se lie à NOD2 suite à l’activation par le MDP. Cette interaction atténuait l'activation de NF-κB dépendante de NOD2, la synthèse de l'IL-8 et l’activité antibactérienne de NOD2. JNKBP1 exerçait son effet répresseur en perturbant l’oligomérisation NOD2 et la phosphorylation de la tyrosine de RIP2 : deux étapes nécessaires à la signalisation en aval. En outre, nous avons montré que JNKBP1 et NOD2 étaient exprimées dans l'épithélium intestinal humain et dans les cellules immunitaires recrutées dans la lamina propria, ce qui suggère que JNKBP1 contribuerait au maintien de l'homéostasie intestinale dépendante de NOD2. [less ▲]

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See detailStructure and Lattice Dynamics of Bismuth Telluride Nanostructures
Bessas, Dimitrios ULg

Doctoral thesis (2012)

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics ... [more ▼]

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics of bulk and nanostructured bismuth telluride, a chapter on lattice instabilities observed in bulk EuTiO3 around room temperature, and a chapter on the development of a resonant ultrasound spectrometer for small samples. First, the lattice dynamics in bulk Bi2Te3 and Sb2Te3 were investigated by nuclear inelastic scattering, diffraction of high energy synchrotron radiation and calorimetry. In combination with earlier inelastic neutron scattering data, the element specific density of phonon states was extracted not only for Te and Sb but also for Bi. The Bi-Te bonding in Bi2Te3 is fundamentally different than the Sb-Te bonding in Sb2Te3. It appears that the Te specific density of phonon states is mostly unaffected upon substitution of Sb with Bi. Phonon polarization analysis was conducted in a Bi2Te3 single crystal. The observed low lattice thermal conductivity in bulk Bi2Te3 and Sb2Te3 results essentially from the small acoustic cut off energy. Second, the lattice dynamics in elemental modulated Sb2Te3 films were studied by nuclear inelastic scattering and diffraction of high energy synchrotron radiation. These studies reveal that the main features in the Sb specific density of phonon states arise from the layered structure. The extracted average speed of sound is practically the same as in bulk Sb2Te3. The impact of the acoustic cut off energy is further highlighted. Third, the phonon confinement in a Bi2Te3 nanowire array was studied by nuclear inelastic scattering, diffraction of high energy synchrotron radiation, scanning as well as transmission electron microscopy. For the first time the element specific density of phonon states was measured on nanowires in two perpendicular orientations. The much lower than in bulk average speed of sound measured in 56 nm diameter nanowires is directly related to the confined dimensions. The related 50 % decrease in macroscopic thermal conductivity is in line with macroscopic measurements on similar nanowires. Fourth, a detailed structural and lattice dynamical investigations of the bulk cubic perovskite EuTiO3 revealed a lattice instability close to room temperature. The low temperature phase is associated with anharmonic europium displacement and has a significant impact in the lattice dynamics. Last, a resonant ultrasound spectrometer for measurements on small samples and thin films was developed. Successful measurements versus temperature of the elastic constants were carried out with sub-percentage accuracy on oriented single crystals smaller than 1 mm3. [less ▲]

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See detailThe role of sleep in the consolidation of rewarded and relational memory
Gaggioni, Giulia ULg

Master's dissertation (2012)

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See detailBiologie et Ecologie du Martin- pêcheur huppé (Alcedinidae : Alcedo cristata, PALLAS 1764) de la région de Kinshasa: habitat, tactique alimentaire et reproduction.
Kisasa Kafutshi, Robert ULg

Doctoral thesis (2012)

Pour expliquer la rareté de sites de nidification du Martin-pêcheur huppé dans la région de Kinshasa, trois hypothèses ont été successivement testées au cours de ce travail. Une première hypothèse ... [more ▼]

Pour expliquer la rareté de sites de nidification du Martin-pêcheur huppé dans la région de Kinshasa, trois hypothèses ont été successivement testées au cours de ce travail. Une première hypothèse suggérait que le choix de son habitat de reproduction résulterait d’un compromis entre le taux de survie de ses nids, de son succès reproducteur et de la qualité des sols utilisés pour la construction des nids. Le résultat obtenu a révélé qu’un sol propice à l’excavation est constitué de 10,8 ± 6,1% de limon, 7,5 ± 6,6% d’argile et de 81,4 ± 11,4% de sable. Par contre les falaises dont les sols sont constitués en moyenne de 8,5±5,6% de limon ; 11,6±6,5% d’argile et de 78,9±13% de sable, étaient soit abandonnées, soit non occupées. Il semble que la teneur en argile pour un sol favorable chez la plupart des oiseaux nichant dans le terrier est généralement inférieure à 10%. Une différence d’environ 1% de teneur en argile, en comparaison avec les falaises abandonnées ou sans nids dans la région, nous a paru inconcevable pour relier l’absence des nids dans certains habitats naturels avec la dureté des sols. La seconde hypothèse confirme le rôle de la relation structure fonction à partir des suivis réguliers de 138 poussins de l’éclosion à la sortie des nids. Le résultat obtenu montre que la croissance et le développement des organes expliquent le patron de consommation de l’espèce et les paramètres plus ou moins importants à la survie de l’espèce en milieux urbanisés (Kisasa Kafutshi sous presse). Et enfin, la troisième hypothèse suggère que le choix de proies à capturer par les adultes dépendrait des exigences des poussins et leur disponibilité dans le site. Pour toute la durée d’élevage, la consommation d’une nichée a été estimée à environ 17 proies. Il s’agissait des insectes, des grenouilles et de poissons de tailles variant de 2-6,5cm. Nous avons montré que le Martin-pêcheur huppé module le choix de son habitat de reproduction non seulement en fonction de la texture du sol des falaises (Kisasa Kafutshi & Aloni Kumanda 2011), de la disponibilité des proies (Kisasa Kafutshi 2012a), mais surtout de la chance de survie de ses nids d’une année à l’autre (Kisasa Kafutshi 2012b). [less ▲]

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See detailLes iguanodons de Bernissart: leur évolution diagénétique et les processus de dégradation
Leduc, Thierry ULg

Doctoral thesis (2012)

About thirty complete articulated skeletons of iguanodons have been excavated from Bernissart. This unique collection is conserved at the RBINS. The bones excavated were the object of diverse physical and ... [more ▼]

About thirty complete articulated skeletons of iguanodons have been excavated from Bernissart. This unique collection is conserved at the RBINS. The bones excavated were the object of diverse physical and chemical treatments to protect them from their degradation. These bones were not the object of detailed mineralogical analyses allowing to understand either diagenetic mechanisms involved or to understand the specific mechanisms of their change. This work thus aims at filling this lack. It integrates petrographic (POM, SEM), mineralogical (DRX, Raman Spectroscopy) and chemical (EDS, X-ray fluorescence, microprobe) techniques. By these methods, 30 different minerals were identified. The diagenesis of Iguanodon bones is the result of cumulative physical, chemical and biological processes that will modify the original chemical and/or structural properties of this organic object. Bone diagenesis is a complex process that includes the degradation of organic matter, the dissolution and recrystallization of bone apatite, the enrichment in trace elements, the precipitation of new minerals in the bone cavities (permineralisation), the fracturation process. A plan is proposed positioning in a relative timescale minerals formed during 3 diagenetic stages and the degradation processes engaged following the bones exhumation. During burial variable recrystallisation took place: the slightly crystallized carbonated hydroxylapatite (the mineral phase of fresh bone tissue) was replaced by well crystallized carbonated fluorapatite currently present in the Iguanodon bones. Whereas some minerals infiltrated in the bone during cavity filling by the sediment (“mainly” quartz, “argillaceous” phyllosilicates), others are authigenic and precipitated in the cavities during burial (pyrite, barite, sphalerite, celestine, iron oxi-hydroxides, authigenic apatite, calcium sulfate and to a lesser extent vivianite). Pyrite is the most abundant authigenic mineral in the Iguanodon fossil bones. It occurs in different morphologies (crystals, framboids, sticks, fibroradial structure, thin coating…). Four kind of pyrite were determined according to the diagenesis phase during which they were formed and the source of iron and sulfur. Besides pyrite barite is the second most abundant phase. When both minerals are present pyrite has been formed first. The distribution of these minerals within bones is more controlled by micro-environments than by particular structure of the bone. Since their discovery the Iguanodon fossil bones were treated for conservation in several ways. This however did not prevent the alteration of pyrite into an assemblage of 16 different secondary minerals. The ferrous sulfates (szomolnokite and rozenite) are the most abundant of these minerals and can be found in nearly all samples sulfatized. Other sulfates were formed as the result of alteration of the wealdian shale by acid produced by pyrite oxidation: e.g. tschermigite, natrojarosite and halotrichite. Gypsum, anhydrite, iron phosphate and diadochite are the result of dissolution of bone apatite. The variations of relative humidity in collections and in showrooms are responsible for the pursuit of the bones degradation (sulfatation of the residual sulfides ; fracturing by dilation / contraction). The relative humidity, conjugated to the temperature variations are the parameters to be controlled for a better preservation of these invaluable fossils. Techniques implementing some chemicals products proposed in the literature are applicable only to certain objects of limited size. [less ▲]

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See detailAux origines de la métaphysique : l'interprétation par Alexandre d'Aphrodise de la "Métaphysique" d'Aristote
Guyomarc'h, Gweltaz ULg

Doctoral thesis (2012)

Le terme de « métaphysique » ne se lit pas chez Aristote. Les livres rassemblés sous ce titre ne cessent d'interroger leurs lecteurs quant à leur unité. La science ainsi désignée, enfin, semble ... [more ▼]

Le terme de « métaphysique » ne se lit pas chez Aristote. Les livres rassemblés sous ce titre ne cessent d'interroger leurs lecteurs quant à leur unité. La science ainsi désignée, enfin, semble contrevenir aux règles communes de la scientificité aristotélicienne. Désigner Aristote comme le « fondateur de la métaphysique » fait dès lors problème. L'hypothèse du présent travail est que cette fondation engage l'œuvre des commentateurs d'Aristote, au premier chef desquels se situe Alexandre d'Aphrodise. L'Exégète par excellence ouvre la possibilité de « faire de la métaphysique » sans que cela signifie seulement commenter Aristote. Alexandre travaille en effet à faire de la Métaphysique un livre et à instituer la métaphysique une science une. Selon l'Aphrodisien, la métaphysique est cette science à la fois universelle et première, à la fois science modèle et fondatrice des autres sciences. Elle s'articule en trois programmes principaux : l'étude générale de l'étant en tant qu'étant, celle de la substance et celle enfin de la cause première. Ces trois programmes sont distincts, mais coordonnés et suffisamment proches pour ne pas pouvoir être étudiés par une autre science, ni éclatés entre diverses sciences. Ils progressent à chaque fois par un passage d'une généralité à son maximum et sa cause. Ainsi la substance est-elle cause de l'être des autres étants et étant au maximum. Ainsi la cause première est-elle intelligible au plus haut point et cause de l'intelligibilité du monde. L'Exégète offre une interprétation forte de l'unité de la Métaphysique et de celle de la science correspondante. C'est dans et par cette reprise que les écrits du Stagirite sont devenus proprement fondateurs. [less ▲]

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See detailDownmodulator role of SHIP-1 in NOD2 signaling
Condé, Claude ULg

Doctoral thesis (2012)

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See detailCatchment modelling and sensitivity analysis to spatial interpolation methods of daily rainfall
Ly, Sarann ULg

Doctoral thesis (2012)

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to ... [more ▼]

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to continuous surfaces. The objective of this dissertation is to confront the performances of the several spatial interpolation methods, in particular the geostatistics for daily rainfall data in the nested catchments to realize a sensitivity analysis on discharges modelled at the outlets to the daily rainfall input in the modelling. The previous studies in the literature emphasized a requirement of novel investigation on the essential means to recover the rainfall data and eventually, the quality of the hydrological modelling. This study leaned on 30-year daily rainfall data of 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km²). Two common deterministic methods are employed here. The Thiessen Polygon (THI) assigns the value from the nearest observation to a certain grid cell. The Inverse Distance Weighting (IDW) is an advanced nearest neighbour approach that allows including more observations than only the nearest points. The value at a certain grid cell is obtained from a linear combination of the surrounding locations. In the geostatistical algorithms, the spatial variation may be better described by a stochastic function. Four versions of kriging are used. The Ordinary Kriging (ORK) is the basic form of Kriging that the prediction is also a linear combination of the measured values. But the spatial correlation between the data, as described by the variogram, determines the weights, assuming that the mean is constant but unknown. The Universal Kriging (UNK) is based on the hypothesis that this mean is a polynomial function of spatial coordinates. So, this type of kriging is not stationary with regard to the mean. The Kriging with External Drift (KED) supposes that the mean of the interest variable depends on auxiliary variables; the theory of this kriging is in fact the same as the theory of UNK, which also contains a non-constant mean. The drift is defined externally through some auxiliary variables. The Ordinary Cokriging (OCK) suggests estimating the variable of interest by weighted linear combination of its observations and the observations of the auxiliary variables. This technique requires the study of the spatial dependence between variables besides the study of the simple spatial dependences. All types of kriging use a variogram model to characterise spatial correlation. A variogram describes in terms of variances how spatial variability changes as a function of distance. Seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) were fitted to daily sample semi-variogram on a daily basis. These seven variogram models were also adopted to avoid negative interpolated rainfall. The elevation, extracted from a digital elevation model, was incorporated into multivariate geostatistics. Seven validation raingages and cross validation were used to compare the interpolation performance of these algorithms applied to different densities of raingages. The areal rainfalls are calculated for the catchment area and used for analysis of extreme rainfall. The effects of the interpolation methods on the extreme rainfall are analysed. The interpolated rainfalls are also used as rainfall input of the physically-based and distributed EPIC-GRID model. The long series of model results are analysed by comparison with the observed discharges at the different outlets of the catchments. Then, the extreme discharges at the outlets are computed. All of these investigations always take into account of the raingage density and the raingage position for very sparse raingage cases. The main results show that among the methods based on the only rainfall data, the geostatistics and IDW are the best ones. The performances change according to the density of the raingages. For the extreme rainfall and long term modelling results, no big difference is found for a high density of raingage but large difference are found for the case of the scattered raingage. For the latter case, UNK and KED are very sensitive to the position of the raingages. IDW, ORK and OCK are found to be the best performance. However for the extreme flow, KED and OCK is the best whereas IDW is not better for the high density of the raingages. For the case of the scattered raingages, the difference in extreme discharge between the interpolation methods is very large and larger than shown in the extreme rainfall and the long term modelling results. IDW, ORK and OCK always perform better. UNK and KED still are sensitive to the positions of raingages. The index of position is used to describe the form of polygon defined by the four raingages. This index is defined as the relation between the polygon perimeter and a circle perimeter having an area equivalent to that of the polygon. The best raingage position for all interpolation methods used in this research should be arround the catchment area, its index should be close to one. [less ▲]

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See detailLorsque les limites des sciences et les sentiers de chasse s’entrecroisent: Une ethnographie des laboratoires scientifiques amazoniens en partenariat avec les communautés autochtones locales
Escobar Jimenez, Kelly ULg

Doctoral thesis (2012)

Currently, protected areas and protected natural species are in a state of proliferation all over the world. Landscapes, flagship species, peoples in voluntary isolation, ecosystems, and “biological ... [more ▼]

Currently, protected areas and protected natural species are in a state of proliferation all over the world. Landscapes, flagship species, peoples in voluntary isolation, ecosystems, and “biological corridors” are all protected. In order to achieve this, categories of protection at different geographical levels have been mobilized. The processes that allow any one of these categories to become operational within a precise territory are more or less well standardized and have in common, amongst others things, two components that have caught my attention: Firstly, the central role of previous scientific and technical studies, and secondly, the desire to ensure the participation of the populations concerned. How are relations between scientists and the non-scientific public in participatory environmental management? This thesis seeks to answer this question, from the starting point of an analysis of the cognitive dimension of participatory environmental management, i.e. how the production of knowledge affects the modes of existence within protected areas (and consequently their human and nonhuman inhabitants). Building upon the study of daily activities that bring scientists and indigenous peoples into contact in and around the scientific field stations “Yasuní” and “Juri Juri Kawsay” (in the Ecuadorian Amazon), this research describes the relationship between ways of knowing a conflicting object (for example a natural species, a territorial boundary, an isolated people) and the consequences in terms of configuration of that object (in terms of identity, value, and fragility) and its management (administration, use, protection, recovery or abandonment). By mobilizing the approach of Actor-Network theory, this dissertation attempts to outline how mediation between humans and nonhumans, non-scientific and scientific, occurs. It also offers a reflection on how the Agency of an entity (the competence to make make distributed in the humans and nonhumans actors) comes to influence the joint actions. This research can capture the ambiguity, instability, resistance and complexity that still exist in the Amazon, with some unexpected findings along the way, by showing the changes among things and people throughout development projects, land management initiatives, and conservation and science programs. After describing the trajectory of four entities (laboratories, species conservation, territories and subjects), which meet at the Amazonian interfaces where science, conservation and development are in competition, the findings of this dissertation have met two ambitions: to consider the importance of taking into account the complexity and historicity of scientific data and to answer a broader question: What are the relevant factors to take into account when considering the possibilities for joint action between scientists and indigenous populations? [less ▲]

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See detailApprentissages automatiques supervisés pour le monitoring environnemental et énergétique d'une chaudière de régénération
Sainlez, Matthieu ULg

Doctoral thesis (2012)

The broad objective of this thesis is to apply and compare supervised learning techniques for prediction of nitrogen oxide pollutant emission from the recovery boiler of a Kraft pulp mill. In this task ... [more ▼]

The broad objective of this thesis is to apply and compare supervised learning techniques for prediction of nitrogen oxide pollutant emission from the recovery boiler of a Kraft pulp mill. In this task, we want to highlight a technique that is most suited and self-adapted to boiler transient operating conditions. The Kraft process is an alkaline process to produce chemical pulp; cellulose fibers are dissociated from lignin by cooking the chips in a solution of sodium hydroxide (NaOH) and sodium sulfide (Na2S), called white liquor. The residual black liquor is concentrated and burned in a recovery furnace to yield an inorganic smelt of sodium carbonate (Na2CO3) and Na2S. The recovery boiler both regenerates the cooking chemicals and produces high pressure steam to the pulp mill, but the boiler is a major source of atmospheric pollutants in the mill. In particular nitrogen oxide formation is very complex because of several chemicals and dynamic mechanisms: thermal NOx, prompt NOx and fuel NOx. Nowadays, there is an increasing demand in such industries for efficient data analysis tools, especially for pollutant monitoring and/or energy management. Literature reviews refer mainly on numerical solutions where a complete description of the process is needed and where stationary condition is often a working hypothesis. This is the case with the advanced data validation and reconciliation techniques that we evaluate. This technique is based on thermodynamic models, chemical and physical relationships within process parameters and equipment. This is helpful to highlight some lack of information about the process, but this approach failed to model accurately steam and fumes utilities operating points. Indeed, in a Kraft recovery boiler, the total nitrogen oxide emission is dependent on several operating factors and heterogeneous conditions, e.g. operating fuels (black liquor or heavy fuel), furnace load, droplet size, air system operation, retention time, biomass characteristics,... For such a complex problem, machine learning techniques may be used as alternative methods in engineering analysis and predictions. They involve algorithms that improve automatically through experience collected in historical databases. Among supervised learning techniques, we focus mainly on neural networks methods (static and dynamic architectures) and additionally on tree-based (regression tree and random forests) and linear ones. For each method, we evaluate its ability to predict NOx pollutant emission in varying conditions. A random forest is a collection of uncorrelated regression trees, induced from bootstrap samples of the training data. Its internal estimates are also used to measure variable importance and allow us to classify relevant variables for a model inputs selection task. Note that we need some additional a priori knowledge to select the final inputs set. Among static neural network structures, the multilayer perceptron is the most widely used, particularly the two-layer structure in which the input units and the output layer are interconnected with an intermediate hidden layer. The model of each neuron in the network includes a nonlinear activation function that is differentiable; this network can perform static mapping between an input space and an output space. Within dynamic architectures, we distinguish those that have only feed-forward connections and those that have feedback (recurrent) connections. In this work, we focus mainly on NARX network (Nonlinear AutoRegressive model with eXogenous inputs) and additionally on Elman recurrent neural network. This last one incorporates an additional layer, called context layer, the nodes of which are the one-step delay elements embedded into the local feedback paths. Nevertheless, Elman's approach has some drawbacks associated with learning parameters scheme and temporal gradient approximation. Particularly, the NARX network is used for input-output modeling of nonlinear dynamical systems. It is a recurrent model: model inputs are applied to a tapped-delay-line memory of n units and outputs are fed back to the input layer through another line of m units. The total model order s=n+m is therefore a key parameter and the method of Lipschitz numbers is a tool for estimating it. An advantage of NARX is that we can use standard backpropagation algorithm for neural network learning scheme. Furthermore, to increase model robustness, we average neural predictions over a set of individual neural predictors, this is helpful for reducing variance prediction across trials. Despite the fact that generalization is done on the worst case configuration possible, we see that ensemble of NARX networks perform well on predicting NOx emissions during transient operations and Lipschitz numbers are very helpful for system orders estimations. We illustrate the potential of a dynamic neural approach compared to the others in the nitrogen oxide prediction task. It is more suited to practical modeling needs and offers a modeling of time and memory. It allows us to monitor NOx pollution and possibly adjusting control variables and performing diagnostics. The thesis is divided into seven chapters covering several publications. Chapter 1 is about the Kraft process and its recovery boiler. We start with a short description of the Kraft pulp mill. Then we describe the Kraft recovery boiler, some chemical reactions in the furnace, the steam production equipments and the atmospheric pollutants. Finally we discuss about nitrogen oxide formation in the furnace, the effects of several operating conditions on its production. Chapter 2 is about data mining, on what it is, on what it is used for and which are the main modeling cultures. This chapter deals with system identification, modeling approaches (white box, grey box, black box), some definitions about learning and modeling, and finally some links between modeling and optimization techniques. Chapter 3 starts with a state-of-the-art about numerical simulation of a Kraft recovery boiler, then we apply and evaluate a data validation scheme for steam and fumes utilities modeling. Finally we discuss the application of artificial intelligence techniques within the framework of a recovery boiler. Chapter 4 aims at selecting model inputs, starting with a supervised selection approach based on random forests. We introduce some methodological insights about tree-based methods, from a simple regression tree to random forests. Random forests internal estimates are used to measure the relative importance of each input variable in predicting a response, i.e. nitrogen oxide emission or high pressure steam production. Finally we discuss about some useful extra knowledge to take in account for the selection of final inputs. Chapter 5 is about neural networks modeling, we introduce the perceptron, the multilayer perceptron, and the associated backpropagation algorithm. We discuss about static and dynamic architectures, especially the Elman recurrent neural network. Finally, we apply a multilayer perceptron and an Elman recurrent neural network for predicting the high pressure steam flow rate from the Kraft recovery boiler. Chapter 6 presents some insights about input-output modeling of nonlinear dynamical systems, especially with NARX network. At the end, we explain the Lipschitz method that is applied for system orders estimation. Chapter 7 summarizes some comparison results about supervised learning techniques applied to predict nitrogen oxide pollutant emission from the recovery boiler. This comparison involves neural network techniques, tree-based methods and multiple linear regression. Finally, some research perspectives are presented and some conclusions are drawn. [less ▲]

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See detailElectrografting on nanoparticles: A new way toward polymer stabilized nanoparticle suspensions
Serwas, Harry ULg

Doctoral thesis (2012)

Abstract: Nowadays, nanomaterials keep sparking interest tremendously because of the unique properties materials exhibit at the nanoscale. However, the stabilization of nanoparticles against aggregation ... [more ▼]

Abstract: Nowadays, nanomaterials keep sparking interest tremendously because of the unique properties materials exhibit at the nanoscale. However, the stabilization of nanoparticles against aggregation is a prerequisite to exploit their remarkable properties, since they are very prone to aggregation. Moreover, even if many synthetic methods have been reported to prepare nanoparticles, achieving an efficient and convenient stabilization, without an alteration of the properties nanoparticles remains a challenge up to now. Therefore, a novel approach toward polymer stabilized metal based nanoparticles was developed using sonoelectrochemistry combined to electrografting to form a protective polymer layer in-situ directly on the generated particles. Nanopaticles prepared using this new approach were characterized. The influence of major experimental parameters on the characteristics of the produced polymer coated particles was also studied. [less ▲]

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See detailEtude de trois souches entomopathogènes de champignons Hyphomycètes dans la lutte contre les moustiques (Diptères : Culicidae)
Bawin, Thomas ULg

Master's dissertation (2012)

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. The prospects for the use of three Hyphomycetes fungi (Aspergillus clavatus Desm., Metarhizium anisopliae (Metsch ... [more ▼]

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. The prospects for the use of three Hyphomycetes fungi (Aspergillus clavatus Desm., Metarhizium anisopliae (Metsch.) Sorokin, and Metarhizium sp.) towards an important vector species (Culex quinquefasciatus Say) are discussed. 1. Culture tests were performed in flasks to assess the spore productivity of the fungal strains on wheat bran (an agricultural by-product) and husked rice (a food product that is classically used) in solid, semi-solid and liquid-state media. Regardless of the substrate, solid-state media showed the highest productivity. The observations suggested that culture tests could be carried out in solid-state or sequential fermentation with wheat bran. 2. Classical toxicity tests using aqueous suspensions of spores were performed to assess their larvicidal potential against C. quinquefasciatus. The LD50 and LD90 were estimated after 72 hours of treatment with 1.35 x 10^8 and 5 x 10^8 spores/ml for Aspergillus clavatus, 1.3 x 10^8 and 4 x 10^8 spores/ml for Metarhizium anisopliae, 1.75 x 10^8 and 9.9 x 10^8 spores/ml for Metarhizium sp. Mycelial filaments appeared from dead larvae and produced spores in the case of each strain. Spores were also found in the gut of emerged adults from surviving larvae. In comparison, the LC50 and LC90 of a commercial formulation based on the bacterium Bacillus thuringiensis var. israelensis (Vectobac ®, serotype H14) were estimated after 48 hours to 0.043 mg/l and 0.115 mg/l. The results showed that the fungi tested cannot be effective control agents at the tested doses and the applied protocol. Different axes of research are suggested. 3. The potentialities of the injection of spore suspensions into mosquito larvae in order to assess their pathogenicity have been considered. The percentages of corrected mortality were obtained after 72 hours for Aspergillus clavatus (62%), Metarhizium anisopliae (53%) and Metarhizium sp. (57%). Additional experiments would be needed to make sure whether it is well a direct response linked to the toxic effect of these fungi. 4. Optical and electron microscopy observations were conducted to study the mode of action of A. clavatus on C. quinquefasciatus larvae. Histological sections revealed that the lethal effect observed in toxicity tests is due to the ingestion of spores. An analysis of toxins produced at the beginning of germination, their contribution to larval mortality and their impact on non-target organisms should be carried out. 5. Finally, the specificity of the pathogenicity of A. clavatus and M. anisopliae against mosquitoes has been evaluated by considering another biological model: the aphid Acyrthosiphon pisum Harris. No link between the range of tested doses and (1) mortality of adults, (2) the decline of their offspring was found. Additional experiments should be carried out. The application of these fungi to other insects of agricultural, veterinary or medical interest should also be tested. [less ▲]

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See detailEvénements de santé et transition à la retraite des seniors en Belgique. Une approche biographique
Banturiki, Yannick Védaste ULg

Doctoral thesis (2012)

La thèse de Mr. Banturiki porte sur une analyse socio-démographique réalisée dans une perspective biographique mettant en relation des événements vécus dans le parcours de vie et la transition à la ... [more ▼]

La thèse de Mr. Banturiki porte sur une analyse socio-démographique réalisée dans une perspective biographique mettant en relation des événements vécus dans le parcours de vie et la transition à la retraite des seniors en Belgique. L’une des approches novatrices de ce travail est la conceptualisation d’un événement de santé en vue de sa collecte dans les biographies individuelles. S’appuyant sur le paradigme des parcours de vie, ce travail se veut une contribution dans la compréhension de l’incidence que peuvent avoir des événements vécus tout au long de la vie sur le risque de connaître une sortie d’une activité salariée chez les seniors. [less ▲]

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See detailDétection de signes de conscience chez des patients sévèrement cérébro- lésés avec le contrôle volontaire de la respiration.
Charland-Verville, Vanessa ULg

Master's dissertation (2012)

Suite à un accident cérébral grave, les patients peuvent évoluer d’un coma (patient non-éveillable et inconscient), vers un état végétatif/syndrome d’éveil non-répondant (patient éveillé mais inconscient ... [more ▼]

Suite à un accident cérébral grave, les patients peuvent évoluer d’un coma (patient non-éveillable et inconscient), vers un état végétatif/syndrome d’éveil non-répondant (patient éveillé mais inconscient), vers un état de conscience minimale (patient éveillé et conscient, mais non-communiquant), ou un locked-in syndrome (patient éveillé, conscient, mais ne pouvant exprimer sa conscience que par le biais de mouvements oculaires). L’attribution d’un diagnostic différentiel suite aux évaluations cliniques à l’aide d’échelles comportementales peut se révéler extrêmement complexe avec un taux d’erreurs diagnostiques pouvant toucher plus de 4 patients sur 10 (Childs, Mercer, & Childs, 1993; Schnakers, Vanhaudenhuyse, Giacino, Ventura, Boly et al., 2009c). Ce diagnostic aura un impact tant au niveau éthique que clinique, influant sur les décisions de fins de vie comme sur les soins et traitements prodigués au patient (Demertzi, Schnakers, Ledoux, Chatelle, Bruno et al., 2009; Johnson, 2011). Afin d’affiner le diagnostic des états de conscience altérée, un vaste champ de recherche s’est créé ayant pour but le développement d’outils objectifs complémentaires à l’examen comportemental clinique. Le but de ce travail s’inscrit donc dans le cadre de la mise au point de techniques permettant de détecter des signes de conscience chez ces patients incapables de communiquer et d’exprimer leur conscience par les voies classiques. En effet, nous avons proposé l’utilisation du sniff controller, une toute nouvelle technique permettant de répondre à la commande par la respiration. Notre paradigme, utilisé pour la première fois auprès de patients atteints de trouble de la conscience, avait pour but de demander aux patients de moduler volontairement leur respiration afin de dépasser un seuil prédéfini. Selon les résultats obtenus, il semble que le sniff controller, moyennant plus d’essais et certaines modifications à apporter au système et au paradigme, pourrait se révéler être un outil complémentaire dans l’évaluation para-clinique de ces patients. En effet, l’utilisation de ce système pourrait se révéler comme plus sensible à la détection de réponse à la commande que les évaluations comportementales. De plus, il s’agit d’une interface peu dispendieuse, relativement simple d’utilisation, transportable au chevet du patient et tout à fait non-invasive. Par ailleurs, en ne reposant pas directement sur l’activité cérébrale, cette technique n’est pas sensible aux artéfacts cérébraux inhérents aux lésions cérébrales rencontrées chez les patients. [less ▲]

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See detailLe sommeil chez les patients en état de conscience altéré
Cologan, Victor ULg

Doctoral thesis (2012)

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de ... [more ▼]

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de conscience minimale. Les conclusions supportent l'intérêt neurophysiologique mais aussi diagnostique et pronostique de l'examen du sommeil chez ces patients. [less ▲]

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See detailCaractérisation des exoplanètes en transit WASP-34b, WASP-35b et WASP-44b à l'aide du télescope TRAPPIST
Delrez, Laetitia ULg

Master's dissertation (2012)

Les Jupiters chauds sont des exoplanètes très intéressantes à étudier du fait des conditions extrêmes auxquelles elles sont soumises (forte irradiation, champs gravitationnel et magnétique intenses ... [more ▼]

Les Jupiters chauds sont des exoplanètes très intéressantes à étudier du fait des conditions extrêmes auxquelles elles sont soumises (forte irradiation, champs gravitationnel et magnétique intenses). Lorsque ces planètes transitent devant leur étoile, elles nous offrent une opportunité unique de pouvoir étudier leur structure, leur composition chimique ainsi que les mécanismes physiques à l’œuvre dans de telles conditions extrêmes. Dans ce mémoire, nous avons procédé à la caractérisation des trois Jupiters chauds en transit WASP-44b, WASP-35b et WASP-34b sur base de courbes de lumière de haute précision de leurs transits obtenues à l’aide du télescope TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope). Pour chacun des systèmes, ces courbes de lumière ont été combinées à des mesures de vitesse radiale de l’étoile hôte dans une analyse MCMC (Monte Carlo Markov Chain) globale afin de contraindre efficacement les paramètres de la planète et de l’étoile. Les résultats que nous obtenons confirment globalement ceux des articles de découvertes des trois exoplanètes. Par ailleurs, nos résultats améliorent considérablement les contraintes sur les paramètres du système WASP-44. Nous mettons également en évidence le fait que les rayons des trois exoplanètes ne peuvent pas (ou assez difficilement dans le cas de WASP-44b) être expliqués par les modèles classiques d’évolution de planètes irradiées. Suite à cette constatation, nous explorons la possibilité d’un éventuel chauffage récent de l’intérieur des planètes par effets de marée comme explication possible de ces rayons trop importants. Nous montrons que les trois exoplanètes pourraient effectivement avoir subi dans le passé un important chauffage par effets de marée. Ce chauffage pourrait avoir contribué aux rayons observés actuellement pour WASP-44b et WASP-35b, parallèlement à d’autres mécanismes. Nous montrons qu’il semble en revanche fort peu probable que le rayon anormalement élevé de WASP-34b soit lié à un tel chauffage. Enfin, nous obtenons une probabilité de 89.3% que les transits de l’exoplanète WASP-34b soient rasants. Cette probabilité est plus élevée que celle donnée dans l’article de découverte mais reste cependant inférieure au seuil 3-σ à partir duquel on pourrait raisonnablement conclure à des transits rasants pour cette exoplanète. [less ▲]

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See detailApproche écologique du neuston en baie de Calvi
Collard, France ULg

Master's dissertation (2012)

Le neuston, à l’inverse du plancton sous-jacent, est un milieu peu connu. Son importance écologique est pourtant réelle : il constitue d’une part une zone d’accumulation de bactéries, de molécules ... [more ▼]

Le neuston, à l’inverse du plancton sous-jacent, est un milieu peu connu. Son importance écologique est pourtant réelle : il constitue d’une part une zone d’accumulation de bactéries, de molécules organiques (lipides, protéines mais aussi plastiques et polluants organiques), de débris terrestres et d’autre part, il est le lieu d’échange des gaz air-océan. Il subit les conditions météorologiques de plein fouet (précipitations, vent, lumière) tout comme les organismes qui y vivent. La diversité neustonique est importante : une trentaine d’espèces de copépodes ont été déterminées et tous les groupes marins planctoniques en baie de Calvi se retrouvent dans le neuston. Parmi les organismes retrouvés en surface, certains sont spécifiques du neuston. C’est le cas des copépodes de la famille des Pontellidae qui sont dominés par des juvéniles. L’abondance neustonique de la plupart des groupes rencontrés varie de manière saisonnière et journalière. L’hiver est très différent de l’été en termes de diversité tandis que le biovolume ne présente pas de variabilité saisonnière marquante. Les Pontellidae, les copépodes du genre Temora, les cladocères, l’ichtyoplancton sont des groupes estivaux tandis que les copépodes du genre Candacia et les isopodes sont hivernaux. La variation à court terme s’explique généralement par la variation de la direction du vent. Lorsqu’il amène des eaux du large, les copépodes (dont les Pontellidae) sont plus abondants, ainsi que les œufs de poisson entre autres. La turbulence, les précipitations et la concentration en chlorophylle a semblent avoir moins d’importance. Une comparaison entre le neuston et le plancton révèle que les Pontellidae sont 200 fois plus abondants dans le neuston. Les copépodes en général, les siphonophores, l’ichtyoplancton semblent y être plus nombreux. A contrario, certains groupes sont plus abondants dans le plancton sous-jacent que dans le neuston (cladocères, mollusques, …). Parmi les débris associés au neuston, on trouve des (micro)plastiques. On comptabilise en moyenne 7,2 fragments sur 100 m² avec un maximum de 78,8 fragments par 100 m². Généralement ils ont la taille du microplancton ou du mésoplancton et sont de couleurs différentes. Leur concentration est influencée par la direction du vent et non par la turbulence. Un vent de nord-nord-est ou d’est-nord-est apporte des plastiques dans la baie. Le neuston est un milieu complexe car beaucoup de paramètres influencent sa dynamique et son écologie. Il est différent du plancton à certains égards, c’est un écosystème à part entière. En baie de Calvi, le vent a une grande importance sur l’abondance des espèces neustoniques ainsi que sur la concentration en débris. [less ▲]

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See detailUse of intercropping and infochemical releasers to control aphids in wheat
Zhou, Haibo ULg

Doctoral thesis (2012)

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See detailAltération hydrothermale du béryl et formation de ses minéraux secondaires dans la pegmatite de Prà della Munega (Sondrio, Italie)
de Marchin, Stéphanie ULg

Master's dissertation (2012)

Beryl crystals have been found in the pegmatite of Prà della Munega rich in feldspars, quartz, muscovite and garnet. This pegmatite outcrops near Chiavenna, in Sondrio Province, Lombardy, Italy. These ... [more ▼]

Beryl crystals have been found in the pegmatite of Prà della Munega rich in feldspars, quartz, muscovite and garnet. This pegmatite outcrops near Chiavenna, in Sondrio Province, Lombardy, Italy. These beryls show different degrees of alteration according to their localization in the pegmatite. Electron microprobe analyzes and X-ray diffraction mesurments (powder and four circles diffractometer) allowed to identify several silicates produced by the alteration of beryl: bavenite, bertrandite, chiavennite, milarite. Chemical analyzes of these minerals show substitution mechanisms which affect beryl and bavenite. Crystal structures of bavenite, chiavennite and milarite were also resolved. These structures are in accordance to structures described in literature, except milarite which Na’s site occupies a slightly shifted position compared with mirror plan. Petrographic observations and the Rietveld methodology allowed to define asequence of alteration. During the alteration, the shape of original beryl is conserved. Bavenite crystallizes in the shape of original beryl, bertrandite and chiavennite crystallize in the shape of original beryl and out of this, and milarite crystallizes out of the shape of original beryl due to a mobilization of Be by pegmatitic fluids. Bavenite and bertrandite are the first minerals to crystallize with an input of Ca, Mn, K, Si, Li, Be and Rb which results of the metasomatism of Na (albitization). These fluids, with a temperature of 350°C, destabilize the beryl and allow the crystallization of these alteration-induced minerals. Chiavennite and milarite are the last minerals who crystallize in the system with an input of K and Mn. These fluids, reaching low temperature and rich in K and Mn, could originate from late metamorphic fluids or residual fluids in pegmatites. [less ▲]

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See detailCalcul de l’aléa sismique pour une région dans le Tien-Shan Central, étude in situ et modélisation numérique dynamique de la réponse sismique de sites de bassin de retenue.
Lamair, Laura ULg

Master's dissertation (2012)

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is ... [more ▼]

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is essential, not only at regional scale but also at local scale. First, this work presents a detailed analysis of seismic hazard in the Central Tien Shan. Several seismic hazard map have been made but none of them include paleoseismic data. Our maps are based on previous studies of probabilistic seismic hazard of the Kyrgyz Tien Shan (Abdrakhmatov et al., 2003). We integrate in our calculation the palaeoseismicity of the Talas Fergana Fault. It allows us to take into consideration strong earthquakes with high return periods. The final results are presented as maps with different return periods (100, 200, 475, 1000, 2000, 5000 and 10000 years). The outcomes are discussed in comparison with previous results, with GSHAP predictions (Ulomov et al., 1999) and with probabilistic seismic hazard map (Abdrakhmatov et al., 2003). The purpose of the second part of this study is the assessment of local seismic hazard of Tuyuk-Suu and Taldy-Bulak "D" tailings, both located in the Minkush valley. First, seismic wave amplifications are determined by means of spectral ratios of the horizontalto- vertical (H/V) components acquired through ambient noise measurements. Secondly, a dynamic modeling of the two tailings is performed. It is based on peak ground acceleration calculated previously for a return period of 1000 years. The dynamic modeling gives Fourier spectra for several histories. Spectral ratios obtained from dynamic modeling are compared with H/V measurement in order to estimate site effects. [less ▲]

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See detailL'expérience de travail dans une organisation autogérée : Le cas de l'asbl Barricade
Croquet, Alice ULg

Master's dissertation (2012)

La recherche part du constat désormais largement démontré qu’un travail, bien plus qu’un moyen de se procurer un revenu, fait sens pour les individus (Ferreras, 2007). À cet égard, le mode de ... [more ▼]

La recherche part du constat désormais largement démontré qu’un travail, bien plus qu’un moyen de se procurer un revenu, fait sens pour les individus (Ferreras, 2007). À cet égard, le mode de fonctionnement autogestionnaire que les salariés de l’asbl Barricade expérimentent chaque jour au regard d’un ambitieux idéal démocratique semble particulièrement privilégié : leur implication dans la gestion de l’organisation entend combattre l’aliénation et cultiver l’émancipation de tout un chacun. Dans l’optique de réfléchir sur ce qui fait réellement sens pour les travailleurs, cette recherche interroge le mode de fonctionnement autogestionnaire adopté par l’association pour en saisir les impacts sur l’expérience des travailleurs. [less ▲]

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See detailEtude longitudinale des besoins psychosociaux des conjoints de personnes atteintes d'un cancer - Evaluation de l'efficacité de méthodes d'action : hiérarchisation des besoins psychosociaux et résolution de problème
Wagener, Aurélie ULg

Master's dissertation (2012)

Introduction. Le cancer, une maladie chronique, a indéniablement un impact sur les patients qui en sont atteints mais aussi sur les membres de leur famille. Les conjoints, plus particulièrement ... [more ▼]

Introduction. Le cancer, une maladie chronique, a indéniablement un impact sur les patients qui en sont atteints mais aussi sur les membres de leur famille. Les conjoints, plus particulièrement, adopteront généralement le rôle de proche aidant principal et ressentiront de nombreux besoins psychosociaux et de la détresse émotionnelle. Méthodologie. Notre recherche-action compare l’efficacité de la combinaison de méthodes d’action « Hiérarchisation + Résolution de problème » à l’utilisation de la « Hiérarchisation » seule. Pour ce faire, 37 conjoints, répartis aléatoirement dans deux groupes (expérimental vs contrôle), ont répondu à divers questionnaires évaluant à trois reprises (T0, T1 et T2) les variables dépendantes suivantes : les besoins psychosociaux, la détresse émotionnelle, les réactions quant à la position de proche aidant principal et le sentiment d’auto-efficacité. D’autres variables dépendantes n’étaient évaluées qu’au T0 : les données sociodémographiques, l’ajustement conjugal, les services d’aide et la perception d’iniquité. Lors du T0, tous les participants réalisent la hiérarchisation. Entre le T0 et le T1, le groupe expérimental pratique la résolution de problème alors que le groupe contrôle n’y aura accès qu’entre le T1 et le T2. Hypothèses. Nous pensons que la combinaison des méthodes d’action aura un impact plus important et plus bénéfique que l’utilisation de la « Hiérarchisation » seule. Résultats. Entre le T0 et le T1, l’amélioration des scores sur les variables dépendantes est plus marquée au sein du groupe expérimental. Entre le T1 et le T2, les scores du groupe contrôle s’améliorent aussi : l’amplitude de changement est d’ailleurs plus élevée. Par contre, les scores que le groupe expérimental avait obtenus lors du T1 ne se maintiennent pas en T2. Par ailleurs, l’ensemble des données qualitatives récoltées mettent en évidence de hauts niveaux de satisfaction des participants quant aux méthodes utilisées. Conclusion. Les résultats obtenus mettent en évidence une plus grande efficacité de la combinaison des méthodes d’action proposées. Ainsi, il s’agit, premièrement, de réfléchir à la façon d’améliorer le protocole utilisé et, deuxièmement, à la façon de l’implanter au sein des services d’oncologie. [less ▲]

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See detailPortfolio professionnel Formasup
Jérôme, Françoise ULg

Master of advanced studies dissertation (2012)

Analyse de pratiques : Régulation des stratégies d’évaluation mises en œuvre dans le cadre d’un cours de traduction littéraire par le biais de la récolte et de l’analyse de données objectives et ... [more ▼]

Analyse de pratiques : Régulation des stratégies d’évaluation mises en œuvre dans le cadre d’un cours de traduction littéraire par le biais de la récolte et de l’analyse de données objectives et subjectives. [less ▲]

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See detailPortfolio professionnel
Hanzen, Christian ULg

Master of advanced studies dissertation (2012)

Ce portfolio a été rédigé dans le cadre du master complémentaire en pédagogie de l'enseignement supérieur (FORMASUP). Ce master visait l'acquisition de trois compétences : concevoir, enseigner et réguler ... [more ▼]

Ce portfolio a été rédigé dans le cadre du master complémentaire en pédagogie de l'enseignement supérieur (FORMASUP). Ce master visait l'acquisition de trois compétences : concevoir, enseigner et réguler. Le portfolio présente les divers aspects et preuves de l'acquisition de ces compétences. [less ▲]

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See detailSymmetries of the scalar sector of multi-Higgs-doublet models
Keus, Venus ULg

Doctoral thesis (2012)

In pursuit of the origin of the masses of particles in the Standard Model, the Brout- Englert-Higgs Mechanism predicts the existence of a scalar boson, whose discovery has been the main goal of the Large ... [more ▼]

In pursuit of the origin of the masses of particles in the Standard Model, the Brout- Englert-Higgs Mechanism predicts the existence of a scalar boson, whose discovery has been the main goal of the Large Hadron Collider. However, introducing this scalar boson does not provide the answer to all inadequacies of the Standard Model. Many different Beyond Standard Model theories have been proposed in order to explain these anomalies. Multi-Higgs-doublet models are among these models. We restrict ourselves to the scalar sector of multi-Higgs-doublet-models. The huge number of free parameters in the scalar potential in these models, makes it impossible to study the most general case for any N. In order to reduce the number of free parameters, one could impose symmetries on the scalar potential. Therefore, it is important to explore which symmetries can be implemented in the scalar sector, how these symmetries are broken, how they could be encoded in the Yukawa sector and what the resulting properties of the fermions are. Classifying these symmetries in the scalar sector is the main focus of this thesis. We have found certain symmetries that are always broken in models with more than two doublets, which we name ”frustrated symmetries”. Examples of such symmetries are presented in 3HDM, and one particular symmetry, the octahedral symmetry, is studied further. This symmetry seems to be the largest realizable discrete symmetry that can be imposed on the scalar sector in 3HDM, and interestingly results in a 2HDM-like mass spectrum. In the attempt towards the classification of possible symmetries in the scalar sector of the NHDM, we find that these symmetry groups are either subgroups of the maximal torus, or certain finite Abelian groups which are not subgroups of maximal tori. For the subgroups of the maximal torus, we present an algorithmic strategy that gives the full list of possible realizable Abelian symmetries for any given N . We extend this strategy to include Abelian antiunitary symmetries (with generalized CP transformations) in NHDM. We also show that multi-Higgs-doublet models can naturally accommodate scalar dark matter candidates protected by the group Zp , since these groups are realizable in NHDM. These models do not require any significant fine-tuning and can lead to a variety of forms of microscopic dynamics among the dark matter candidates. [less ▲]

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See detailApprocher la médiation par ses usages professionnels. Le cas de l'art-thérapie
Vandeninden, Elise ULg

Doctoral thesis (2012)

La médiation est une notion aujourd’hui centrale dans de nombreuses recherches en SIC : elle est mobilisée en tant que concept permettant de décrire la spécificité de dispositifs communicationnels ... [more ▼]

La médiation est une notion aujourd’hui centrale dans de nombreuses recherches en SIC : elle est mobilisée en tant que concept permettant de décrire la spécificité de dispositifs communicationnels tripartites mais aussi comme problématique susceptible d’interroger autrement certains objets. Les domaines d’étude privilégiés par les chercheurs relèvent traditionnellement des champs de la culture ou des médias et techniques. Dans le premier, la notion de médiation désigne le réseau d’intermédiaires reliant l’œuvre au public ; le travail des analystes consiste alors à faire apparaître « les médiations » auparavant invisibles. Dans le second, le terme renvoie à un « objet intermédiaire » qui s’insère dans les relations humaines et substitue le rapport objectal au rapport intersubjectif. Dans ces deux domaines, il est question d’un contact différé, espacé. Les usages professionnels de la médiation - ceux qui renvoient, par exemple, aux divers métiers de « médiateurs » - sont, en revanche, très peu interrogés par les chercheurs en SIC. Ils se caractérisent par un recours au terme de médiation comme stratégie de communication. Son processus renvoie à l’insertion d’un « tiers humain » dans des relations intersubjectives souvent décrites comme conflictuelles. Ce qui distingue ces derniers usages de ceux traditionnellement investigués en SIC, c’est donc ce tiers « incarné » et la confrontation directe des sujets. Cette recherche s’attache à comprendre d’une part les raisons de ce désintérêt des chercheurs en SIC pour des pratiques professionnelles pourtant reconnues socialement, d’autre part la spécificité de l’activité du « tiers humain ». Afin d’explorer le fonctionnement de cette dernière, nous avons opté non pour l’étude d’un médiateur « nommé » tels que ceux qui exercent dans les domaines juridique, familial, entrepreneurial ou encore scolaire mais pour le « cas » des psychothérapies médiatisées dont « l’art-thérapie » fait partie. Si cet objet d’étude nous a semblé intéressant, c’est que son articulation avec la notion de médiation « fait problème ». C’est à un texte de Jean-Claude Passeron et de Jacques Revel (2005) qu’il faut se référer pour décrire la particularité de notre travail : « Penser par cas. Raisonner à partir de singularités ». Ils y décrivent cette démarche qui consiste à s’appuyer sur la richesse d’un objet pour mettre des outils théoriques à l’épreuve, non pas pour illustrer la théorie (cela reviendrait alors à mobiliser le « cas » comme « exemple ») mais pour l’interroger : « c’est, à dire vrai, l’ensemble des questions dont on l’investit – et dont il est susceptible d’être investi – qui fait le cas » (p. 11). Ainsi, nous envisageons la façon dont le « cas » de l’art- thérapie interroge la définition de la médiation : comment les visions des professionnels mettent en cause les conceptions des chercheurs en SIC mais aussi de quelle façon les différents modes d’appréhension possibles (approche à partir des discours ou des situations) appellent l’instauration d’un cadre de perception nouveau, apte à mettre en relation les éléments disjoints révélés par l'étude du cas. [less ▲]

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See detailComment définissons-nous nos souvenirs lors d'un témoignage oculaire ?
Schroyen, Sarah ULg

Master's dissertation (2012)

Lorsque nous sommes amenés à définir notre souvenir, on distingue classiquement deux processus : - Un processus de recollection, faisant référence au rappel conscient de détails épisodiques - Un processus ... [more ▼]

Lorsque nous sommes amenés à définir notre souvenir, on distingue classiquement deux processus : - Un processus de recollection, faisant référence au rappel conscient de détails épisodiques - Un processus de familiarité, désignant un sentiment de déjà-vu Lors de ce mémoire, nous nous basons sur une vision graduelle tant pour le processus de recollection que de familiarité, un processus n’excluant par l’autre. Nous utilisons un paradigme de témoignage oculaire : les sujets visionnent l’extrait d’un film et doivent ensuite répondre à une série de détails. Pour chaque proposition, un jugement « souvenir » (correspondant au processus de recollection) et un jugement « familiarité » leur sera demandé sur une échelle de 1 à 4. Une série de questions sur chaque item (à propos de détails visuels, sonores…) leur est ensuite posée. Dans un premier temps, nous essayons de reproduire les résultats obtenus par Bodner et Richardson-Champion (2007) sur l’influence du contexte sur le jugement : notre hypothèse étant un plus haut taux de réponses souvenirs pour les items de difficulté moyenne lorsqu’ils sont mélangés à des items difficiles plutôt que des items faciles. Ensuite, nous comparons deux groupes d’âge : des sujets entre 20 et 26 ans et des sujets entre 60 et 69 ans. Nous nous attendons à observer une diminution du taux de jugement souvenir accordé aux items correctement reconnu et une augmentation des fausses alarmes avec un jugement souvenir avec l’avancée en âge. L’effet du contexte sur le jugement phénoménologique accordé aux items n’a pas été vérifié chez les sujets âgés. Par contre, le nombre de détails associés à chaque item montre un effet du contexte dans les deux groupes d’âge. À propos de l’effet de l’âge, comme attendu nous montrons une augmentation des fausses alarmes jugées comme souvenir chez les sujets âgés comparativement aux sujets jeunes. Par contre, le jugement souvenir accordé aux items correctement reconnus est plus élevé avec l’âge. Des pistes pour expliquer ces différents résultats sont ensuite proposées. [less ▲]

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See detailPortfolio FORMASUP
Colaux, Catherine ULg

Thèse d’agrégation de l’enseignement supérieur (2012)

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See detailL'étude de l'impact de l'activité professionnelle et de l'âge de départ à la retraite sur le développement de la maladie d'Alzheimer.
Grotz, Catherine ULg

Master's dissertation (2012)

Contexte : Le vieillissement s'accompagnerait de modifications cérébrales entrainant des répercussions sur certaines fonctions cognitives. Cependant, il existerait une grande hétérogénéité ... [more ▼]

Contexte : Le vieillissement s'accompagnerait de modifications cérébrales entrainant des répercussions sur certaines fonctions cognitives. Cependant, il existerait une grande hétérogénéité interindividuelle pouvant s’expliquer par des différences de réserve cognitive, concept très récent et complexe, qui suggère que toutes les activités entreprises durant la vie feraient que l’individu se construise une réserve, lui permettant de différer les effets du vieillissement sur le cerveau. Objectif : Le but de cette étude est, en partant de l’âge de la retraite comme facteur de réserve, de déterminer si la retraite exerce une influence sur le développement de la maladie d’Alzheimer ainsi que sur son décours temporel. Méthode : Les données ont été recueillies sur 32 patients (Alzheimer probable/Mild Cognitive Impairment) de plus de 50 ans. La cognition des sujets a été évaluée via une courte batterie de tests cognitifs (mémoire épisodique et fonctions exécutives). D’autres données relatives à la maladie ont été récoltées via le dossier médical. Un entretien semi structuré (e.g., questions relatives au parcours professionnel, à la retraite) et des questionnaires ont été administrés aux sujets. Résultats : Aucune relation n’a été mise en évidence entre l’âge de début de la maladie, certaines mesures cognitives et l’âge de la retraite. Par contre, l’âge de cessation de l’activité professionnelle serait négativement lié au MMSE, lors du 1er bilan, et à la tâche du Stroop. La relation Retraite/Cognition serait, cependant, influencée par le type de profession, et dans une moindre mesure, par le nombre d’activités de loisirs. Enfin, la vitesse d’évolution de la maladie ne serait pas liée à l’âge de la retraite. Conclusion : Ces résultats ne confirment que partiellement nos hypothèses et ne permettent pas d’apporter beaucoup d’arguments en faveur du concept de réserve cognitive. Néanmoins, cette étude souligne qu’à un stade d’évolution léger, l’effet protecteur de la réserve peut continuer à se manifester. [less ▲]

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See detailEvolution des herbiers à Posidonia oceanica (L.) Delile dans la baie de Calvi (Corse, France) et influence de l’ancrage dans la baie de l’Alga
Abadie, Arnaud ULg

Master's dissertation (2012)

In the framework of the STARE-CAPMED program we studied the impact of human activities on Posidonia oceanica meadows in Calvi Bay (Corsica, France). We mostly focused on the consequences of boats ... [more ▼]

In the framework of the STARE-CAPMED program we studied the impact of human activities on Posidonia oceanica meadows in Calvi Bay (Corsica, France). We mostly focused on the consequences of boats anchoring in Alga Bay. The map of the marine habitats realized during this study shows that P. oceanica meadows cover a surface of 4.94 km2 in 2010 and have declined of 26 % since 1997. Advances in the data acquisition techniques allow a better identification of the habitats and a map reliability improvement. In several places in the bay, especially near the waste waters rejection site, the lower limit of the meadow is shallower than in the past. The diminution of the meadow surface in the 21-30 m bathymetric section is more important in the Alga site than in the rest of Calvi Bay. The ecological state of the water surrounding the meadow in Alga was assessed as "good" with a PREI index of 0.685. However, big units anchoring in this area lead to the creation of dead “mattes” whose compactness are medium. In this area, the generation of dead mattes seems to favor the settlement of the invasive Chlorobionta Caulerpa racemosa var. cylindracea, of which anchoring is known to be one of the introduction vectors. [less ▲]

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