References of "Dissertations and theses"
     in
Bookmark and Share    
See detailLa résilience chez les enfants atteints de leucémie: Mythe ou réalité?
Vander Haegen, Marie ULg

Master's dissertation (2009)

This research aims to investigate the process of the resilience in children treated for leukemia. To this end, this report analyzes at first the phenomenon of resilience and its related notions. Then, we ... [more ▼]

This research aims to investigate the process of the resilience in children treated for leukemia. To this end, this report analyzes at first the phenomenon of resilience and its related notions. Then, we shall approach the oncologic disease through a clinical analysis and we shall consider the presence of specific psychological factors in pediatric oncology. An exploratory study is led in a second part in the form of a questionnaire submitted to six participants of the hospital. These various healthcare professionals will learn us to improve better the real-life experience of childhood cancer. Moreover we highlight certain risk factors and protective factors in the development of resilience. [less ▲]

Detailed reference viewed: 115 (18 ULg)
Full Text
See detailNon-Destructive Methods for the Detection of Delaminations in Concrete Bridge Decks
Van der Wielen, Audrey ULg

Master's dissertation (2009)

To detect delaminations in concrete bridge decks, the non-destructive techniques (NDT) permit a frequent inspection of the slabs without damaging the structures. Within this study, twelve samples were ... [more ▼]

To detect delaminations in concrete bridge decks, the non-destructive techniques (NDT) permit a frequent inspection of the slabs without damaging the structures. Within this study, twelve samples were realized, presenting diverse horizontal defects simulating delaminations. They were scanned with high frequency GPR with the common offset (CO) and common mid point (CMP) methods. The electromagnetic waves speed and defects depth were determined from the CMPs. A 3D visualization program was also created to display the CO measurements. The visibility of the inserted defects revealed to be dependent on their lateral extension, their thickness and especially their constitutive material. [less ▲]

Detailed reference viewed: 556 (18 ULg)
Full Text
See detailBanc polarimétrique de mesure de masques de phase pour la coronographie
Piron, Pierre ULg

Master's dissertation (2009)

Ce travail comprend deux parties. La première partie replace la coronographie dans son contexte historique (détection des exoplanètes) et scientifique (différentes théories physiques et leur développement ... [more ▼]

Ce travail comprend deux parties. La première partie replace la coronographie dans son contexte historique (détection des exoplanètes) et scientifique (différentes théories physiques et leur développement mathématique). Elle présente les qualités et les défauts des différents masques utilisés dans les coronographes. A l’origine, la coronographie est une technique utilisée en astronomie pour reproduire une éclipse totale de soleil. Depuis la découverte de la première exoplanète en 1995, la coronographie est en pleine (r)évolution : elle s’efforce de donner une image d’un compagnon faible qui orbite autour d’une étoile brillante. Grâce à la spectroscopie, une image peut fournir des informations inaccessibles aux autres méthodes de détection (présence d’eau, de vie, ...). La chromaticité (dépendance à la longueur d’onde de travail) est le défaut le plus gênant pour un masque coronographique ; les chercheurs rivalisent donc d’ingéniosité pour améliorer sans cesse les performances et repousser toujours plus loin les limites instrumentales. Dans les années 2000, les masque de phase apparaissent : ils produisent un déphasage soit par différence de chemin optique (masques chromatiques : DPM, 4QPM) soit par opposition de phase entre les composantes électrique et magnétique de la lumière (masques achromatiques : 4QAPS, 4ZOG, AGPM). L’interférence destructive due au déphasage provoque l’atténuation totale ou partielle d’une source lumineuse centrée (une étoile). Par contre, la lumière d’une source décentrée (une étoile faible voisine, une planète qui orbite autour de l’étoile) n’est pas ou peu atténuée. Ce principe explique le rôle joué par la coronographie dans la détection des exoplanètes. Grâce à leur biréfringence de forme, les réseaux sublambda de type ZOG créent une différence de phase entre les composantes électrique et magnétique de la lumière. Le masque de phase à quatre quadrants 4ZOG est formé de quatre ZOGs orientés pour créer une opposition de phase entre deux quadrants adjacents. L’Annular Groove Phase Mask (AGPM) est un réseau ZOG "space-variant" qui génère un vortex optique avec une interférence destructive au centre. L’optimisation de la configuration spatiale d’un ZOG (pas du réseau, profondeur de gravure, facteur de remplissage, ...) améliore ses performances optiques mais une erreur sur le déphasage est toujours possible. Elle est due au manque de précision lors de la fabrication par lithographie. Le défi actuel à relever est de trouver une technologie de fabrication plus fiable : les Liquid Crystal Polymers semblent prometteurs. La deuxième partie est plus pratique : elle présente le banc de mesure mis au point à l’Hololab de la Faculté des Sciences de l’Université de Liège. Il est prévu pour travailler dans les bandes infrarouges H et K qui sont couramment utilisées en astronomie, notamment pour la détection des exoplanètes. Il est destiné à mesurer le déphasage produit par les retardateurs de phase (phase shifters), entre autres, les masques de phase utilisés en coronographie : des plus simples (lames quart d’onde, lames demi-ondes) aux plus sophistiqués (masques de phase de type ZOG) en passant par les rhomboèdres de Fresnel (réflection totale interne). Cette partie décrit les différents composants et leur mise au point initiale, le principe polarimétrique de son fonctionnement, le programme LabVIEW qui commande les polariseurs mobiles et la prise de mesure par le détecteur, les modules MATLAB qui traitent les données, les limites actuelles à son fonctionnement (vitesse de fonctonnement, précision des mesures, stabilité des mesures, ...) Un chapitre présente les résultats expérimentaux obtenus pour quelques échantillons testés : une lame quart d’onde avec le laser à 1.55 m, la même lame avec le laser à 2.3 m, un rhomboèdre de Fresnel avec le laser à 1.55 m. [less ▲]

Detailed reference viewed: 127 (38 ULg)
Full Text
See detailEtude et modélisation d'un aquifère alluvial en vue de la mise en place d'installations géothermiques de refroidissement et de conditionnement d'air
Fossoul, Frédérique ULg

Master's dissertation (2009)

Policies against global warming are generating mechanisms favorable to renewable energies. In particular, the development of geothermal expertise has considerably increased these last years and numbers of ... [more ▼]

Policies against global warming are generating mechanisms favorable to renewable energies. In particular, the development of geothermal expertise has considerably increased these last years and numbers of various environments are henceforth studied and worked to feed heating and/or cooling systems. However numerical models, allowing to simulate these processes by integrating the maximum of the available information, are still seldom used in this domain. In this work, the basic principles of geothermal processes are first described. Then, the governing equations for heat transfer in saturated porous media are detailed and the analogies between heat transfer and solute transport are established. Due to the general lack of specific data, the currently available techniques for measuring and evaluating the two main parameters of the subsoil, the thermal conductivity λ and the specific heat capacity c, are reviewed. The main purpose of this work consists in modeling the flow and the heat transfer within the alluvial aquifer of the Meuse in Liège with the aim to set up a system of air conditioning by pumping the groundwater. Two numerical codes are used and compared: MT3D/MODFLOW (finite differences) and HGS (finite elements). The variations of the aquifer temperature are assumed to be weak enough to neglect their influence on hydrodynamics and thermal parameters. A simplified situation is however simulated by means of both previous codes and of software Processing Shemat to validate this hypothesis and to estimate the approximation it could generate in this kind of problem. [less ▲]

Detailed reference viewed: 203 (33 ULg)
Full Text
See detailSécurisation, externalisation et virtualisation dans l'espace européen: mutations de la sécurité et des frontières, le programme Eurosur
Lejeune, Zoé ULg

Master's dissertation (2009)

L’espace de liberté, de sécurité et de justice constitue aujourd’hui un domaine de compétence hautement politisé et controversé en plein essor dans le cadre européen, d’où l’intérêt que nous avons ... [more ▼]

L’espace de liberté, de sécurité et de justice constitue aujourd’hui un domaine de compétence hautement politisé et controversé en plein essor dans le cadre européen, d’où l’intérêt que nous avons manifesté pour ce sujet de réflexion. La politique de gestion des frontières extérieures y occupe actuellement une place centrale. Elle constituerait en effet l’une des solutions fondamentales face à la pression migratoire, considérée comme un élément clef de la nouvelle sécurité en Europe. La gestion frontalière – qu’il s’agisse de surveillance ou de contrôle – a fait l’objet de nombreuses réflexions et législations ces dernières années, témoignant ainsi de sa centralité dans la politique sécuritaire et migratoire européenne. La politique frontalière a contribué à la redéfinition du territoire européen et à la reconfiguration de la coopération sécuritaire entre les Etats membres. Dans cette optique, nous nous sommes intéressés à un projet européen lancé en 2006 par la Commission, qui porte sur la surveillance transfrontalière. L’objectif du présent travail consiste ainsi à interroger les fondements d’un nouveau programme de gestion frontalière au travers de différents prismes que nous avons jugés cruciaux pour comprendre la dynamique de la politique de gestion des frontières extérieures européennes à l’heure actuelle : la sécurisation, l’externalisation des pratiques frontalières et, de manière plus large, des politiques dites « JAI » – Justice et Affaires intérieures –, la virtualisation, la complexification et la suréglementation de certains domaines d’action à l’échelon communautaire. Le nouveau programme Eurosur illustre ainsi les enjeux fondamentaux des politiques frontalière, migratoire et sécuritaire européennes à l’heure actuelle. Notre propos consiste donc à interroger les questions de légitimité qui sous-tendent la mise en place d’un nouvel outil frontalier de grande envergure à l’échelle européenne. Nous avons choisi d’aborder le projet Eurosur – European Border Surveillance System – pour plusieurs raisons. Tout d’abord, le stage que nous avons effectué au sein de la Représentation permanente de la Belgique près l’Union européenne durant le mois de septembre 2008 nous a permis de développer des contacts essentiels pour notre démarche, d’accéder aux documents pertinents de la Commission européenne et ainsi d’allier réflexion théorique et outils empiriques. Ensuite, la nouveauté d’Eurosur nous permettait d’appliquer des éléments fondamentaux de la réflexion actuelle sur les frontières et la sécurité en Europe à un nouvel instrument ayant fait l’objet de peu de questionnements en termes « scientifiques ». [less ▲]

Detailed reference viewed: 177 (15 ULg)
Full Text
See detailThermal Design of the OUFTI-1 nanosatellite
Jacques, Lionel ULg

Master's dissertation (2009)

OUFTI-1 is the first nanosatellite developed at the University of Liège and even the first one ever made in Belgium. This student project takes place within the framework of a long-term goal program ... [more ▼]

OUFTI-1 is the first nanosatellite developed at the University of Liège and even the first one ever made in Belgium. This student project takes place within the framework of a long-term goal program called LEODIUM (Liège in Latin). The goal of this program is to provide hands-on experience to engineering students through the development of a series of nanosatellite for scientific experiments in cooperation with space industries of the region of Liège. OUFTI-1 will be the first satellite ever equipped with one of the latest digital amateur radio communication protocol : the D-STAR protocol. This technology represents one of the three payload of OUFTI-1, since one target of the mission is to test this new protocol in space. The two other payloads are high efficiency solar cells provided by Azur Space and an innovative electrical power system developed with Thales Alenia Space ETCA. OUFTI-1 will hopefully be launched on the new European launcher Vega with eight other student nanosatellites. This present thesis focuses on the thermal design of OUFTI-1 whose goal is to guarantee all components are functioning within their allowable temperature range. With this in mind, different thermal model of increasing complexity are developed within both Matlab/Simulink and ESATAN/ESARAD environments. based on their results, proper measures will be taken to ensure all the components works indeed in their allowable range of temperatures. [less ▲]

Detailed reference viewed: 361 (23 ULg)
Full Text
See detailModeling of a pilot plant for the CO2-reactive absorption in amine solvent for power plant flue gases
Léonard, Grégoire ULg

Master's dissertation (2009)

During the combustion of fossil fuels in power plants, large carbon dioxide quantities are produced and released into the atmosphere. Carbon dioxide is a greenhouse gas and its role in the current global ... [more ▼]

During the combustion of fossil fuels in power plants, large carbon dioxide quantities are produced and released into the atmosphere. Carbon dioxide is a greenhouse gas and its role in the current global warming is widely accepted by the scientific community. Many projects have been launched in the last few years that aimed at developing processes for the mitigation of carbon-dioxide emissions. Among the different carbon capture and storage technologies (CCS), the post-combustion capture of CO2 in power plants seems promised to a large development. The objective of the present work is to model a pilot installation that should be built in the next few months. This pilot installation will be retrofitted in an existing coal-fired power plant in order to treat 5000 Nm³/h flue gas in two process trains. It is planed that 90% of the CO2 present in the flue gas can be removed, which corresponds to a capture rate of about 1 ton CO2/h. The role of this simulation is to facilitate the comprehension of the capture phenomena and to highlight the key process parameter and their influence on the obtained results. Furthermore, some technical improvements are studied that aim at a reduction of the energy consumption of the CO2-capture process. The simulation tool Aspen Plus has been employed to model the pilot installation. It has been assumed for the simulation requirement that the equilibrium state was achieved for each stage of the mass transfer columns. Mass transfer limitations and reaction kinetics have then been neglected. The model described in this work has been successfully developed for one process train treating a flue gas flow of 2500 Nm³/h. The solvent is monoethanolamine (MEA), which is the most employed solvent in CO2-capture technologies. The CO2-recovery rate has been fixed to 90%. The most relevant process parameter that have been studied with the developed model are the solvent flow rate, the solvent concentration, and the stripper pressure. An optimum for the solvent flow rate has been identified at 11,75 m³/h, corresponding to a thermal energy consumption of 3,76 GJ/ton CO2. When increasing the stripper pressure, the thermal energy consumption decreased up to 16%. The fact that a pressure increase in the stripper leads to a temperature increase and the strong temperature dependence of the CO2-partial pressure explained this reduction of the thermal energy consumption. However, an increase of the stripper pressure induces solvent degradation problems, corrosion and a more complex equipment design. The MEA-concentration has been varied between 27 and 37 wt-%. When using a more concentrated solvent solution, the solvent is easier to regenerate. Consequently, the thermal energy consumption of the process decreased up to 12,5%. However, corrosion problems limit the use of concentrated solvents so that the MEA-concentration in capture-processes is generally adjusted to 30 wt-%. Furthermore, two process modifications have been tested successfully. First, a partial evaporation of the regenerated solvent after the stripper outlet has been studied. The gaseous product of this partial evaporation was compressed and recycled to the stripper. A decrease by 25% of the thermal energy consumption could be achieved. However, compression work has to be furnished. When calculating the improvement on the basis of exergy, then the exergy of the capture process decreased by 18%. The second modification that has been studied is a solvent intercooling between two absorber stages. It has been observed that intercalating the intercooler between absorber bottom stages gives better results than between absorber top stages. Simulation results have shown that the thermal energy consumption decreased by up to 6%. In the case of a flue gas pre-cooling before the absorber inlet, about the same reduction of the thermal energy requirement could be achieved. Finally, a thermal energy consumption of 2,82 GJ/ton CO2 has been achieved in the best case, corresponding to a process exergy reduction by approximately 18%. The developed model allows further improvements so that the optimization of the CO2-capture process could be pursued. Since a detailed study of the process model could help the planning of an experimental test phase, the test-campaigns with the new pilot plant could be optimized. [less ▲]

Detailed reference viewed: 258 (20 ULg)
Full Text
See detailAménagement de la voie navigable "Seine-Escaut Est" : Conception et calcul des portes aval des écluses de Marchienne-au-Pont, Gosselies, Viesville et Obourg
Gernay, Thomas ULg

Master's dissertation (2009)

This paper presents a research study performed lock gates. It concerns the downstream lock gates of the one of the four new locks planned within the framework of the “Seine-Escaut Est (SEE)” project in ... [more ▼]

This paper presents a research study performed lock gates. It concerns the downstream lock gates of the one of the four new locks planned within the framework of the “Seine-Escaut Est (SEE)” project in the Walloon Region of Belgium. At the stage of the basic preliminary design, it was decided to use four identical gates, all suspended and manoeuvred by lateral movement. On this basis, the present work tackles with different aspects of the lock gate study. The aim is double: on one hand, to advance in the study of the solution of the four downstream lock gates of the SEE project, and the other hand, to concentrate more particularly on the lock gate analysis, among which their design, optimization and structural behavior in the case of ship impact. We began with the design and optimization of the gate. This work was realized with the LBR5 lock gate optimization software, according to a method comparing a representative number of optimized solutions considering at the same time the cost and weight aspects of the structure. This method leaded to an optimized solution of the downstream gate on which further studies are concentrated. Indeed this optimized gate was modeled with the non linear finite elements software FINELG. This program was used to conduct a non linear numerical analysis of the effect of a boat impact on the downstream gate. Several analyses were performed that allowed us to discuss on the influence of the stiffener dimensions and the influence of the impact zone on the gate structural behavior submitted to the impact. Two different behaviors have been brought to light, a ductile one and a fragile one. The results of the numerical analysis with finite elements have underlined the importance of the development of a global plastic mechanism with the purpose of dissipating a large amount of energy. Finally, we have used an analytical model to calculate the gate theoretical strength in a case of a ship impact, and to compare this value with the FEM numerical analysis results. [less ▲]

Detailed reference viewed: 254 (35 ULg)
See detailÉléments de toponymie générale. Du Grand-Bornand à Passamainty, terrain de longue durée et enquêtes contrastives en terrain varié dans les domaines roman, polynésien, basque et bantu
Delorme, Jérémie ULg

Doctoral thesis (2009)

Rechercher les bases d’une connaissance des toponymes renouvelée et renforcée se situe au fondement de cette thèse. Ce projet repose sur l’hypothèse selon laquelle les approches récentes et actuelles des ... [more ▼]

Rechercher les bases d’une connaissance des toponymes renouvelée et renforcée se situe au fondement de cette thèse. Ce projet repose sur l’hypothèse selon laquelle les approches récentes et actuelles des faits toponymiques peuvent être améliorées. Sa mise en œuvre invite à engager une réflexion sur les méthodes et les théories de la toponymie. Il s’agit, en s’efforçant de satisfaire aux conditions de cohérence et de rigueur d’une approche scientifique, de poursuivre un but de conceptualisation et de généralisation. Cette démarche répond à l’observation de principes essentiels : 1° aligner la toponymie sur les méthodes et les théories de la linguistique générale ; 2° privilégier l’oralité, les synchronies observables et le point de vue des locuteurs natifs, d’après un idéal d’adéquation de la toponymie, science sociale et science de terrain, à son objet, l’étude des phénomènes toponymiques ; à cette fin, 3°, tirer profit d’une longue expérience des informateurs et du terrain ; et, 4°, soumettre l’étude des toponymes à une analyse progressive, en abordant les faits toponymiques dans leur ordre logique, des plus simples au plus complexes, à travers trois thèmes de recherche majeurs – l’établissement de corpus toponymiques oraux, l’exploration approfondie des lieux désignés par des toponymes, et l’étude des formations toponymiques, menée à rebours de travaux de toponymie dont l’étymologisation constitue le thème directeur. Fondés sur la pratique d’un terrain privilégié – celui d’une toponymie francoprovençale –, les acquis de cette recherche font l’objet d’une évaluation : soumis au contrôle de toponymies-tests – futunienne, basque et comorienne –, ils ne sont tenus pour généralisables qu’après s’être vu corroborés ou amendés. [less ▲]

Detailed reference viewed: 57 (0 ULg)
Full Text
See detailContribution à l’étude de l’activité antivirale et du mécanisme moléculaire de la MX1 bovine
Baise, Etienne ULg

Doctoral thesis (2009)

Summary Type I interferons (IFNs a/b) induce the synthesis of many factors belonging to the innate immune system which is known to play an essential role as the first defence line against the viral ... [more ▼]

Summary Type I interferons (IFNs a/b) induce the synthesis of many factors belonging to the innate immune system which is known to play an essential role as the first defence line against the viral infection. Among these contributors, the MX protein (a member of the large GTPase family) along with the double stranded (ds) RNA dependent protein kinase R (PKR) and the 2’5’ oligoadenylate synthetase/Rnase L system, has been shown to be one of the most efficient among the murine and the human species. The bovine counterpart of the MX system was, at the beginning of this work, described at the sole gene level (the CDS sequence) but its functional capacity was still totally unexplored. Accordingly, our first aim was to assess the ability of the bovine GTPase we called boMX1 to inhibit viruses infecting cattle. A Vero cell line (V103) conditionally expressing the boMX1 was established. To proof the concept, we firstly tested the inhibition of a canonical virus on this field, the vesicular stomatitis virus (VSV) which was confirmed to be as sensitive to boMX1 as previously shown to MXA (Homo sapiens). In a second step, we focused our investigation on the activity of boMX1 against two Paramyxoviridae viruses, the boRSV and the boPI3, both of these being sensitive to IFNs as reported in the literature and furthermore confirmed by our previous in vitro experiments. Although boMX1 was expected to be the most important factor of the type I interferon resistance recorded against boPI3 and boRSV, our study has shown that the bovine protein was not able to block these viruses belonging to the Respirovirus genus. Conversely, the famous Orthomyxoviridae virus member, Influenza A was shown to be almost completely inhibited in cells expressing boMX1. The inhibitory potential of boMX1 was so strong it could only be measured upon the replacement of the low pathogenic H1N1 strain used in the first assays by the hypervirulent H7N7 one. In this case, the protection rate was as high as 108. Typically, the value found for the human counterpart MXA is in the range of 103 – 104 and according to our knowledge, none of the MX proteins investigated so far have never been shown to be so effective against Influenza A. In the wave of these results, the well-known avian H5N1 Influenza A strain has been tested in vitro and in vivo. All the data reinforced the concept of a very high anti-Influenza A activity for BoMX1. A such important antiviral effect appeared as an opportunity to initiate an experimental approach of the largely unknown underlying mechanism(s) of the MX antiviral activity. Our first objective was to identify the “primum movens” of the inhibition mechanism. Therefore, we followed the kinetic of the infection in V103 expressing or not the boMX1 during one single cycle. The evidence of an important activity of the bovine GTPase in the first hours post-infection led us to identify at the RNA level which replication step was the first to be blocked. Following the collected results, we adapted a primer extension method to quantify the genomic viral RNA (vRNA) early entry in the induced and non induced cell cultures. Finally, we tested a first interaction hypothesis between the boMX1 and a potential interacting protein sister. [less ▲]

Detailed reference viewed: 99 (40 ULg)
Full Text
See detailRegulatory T cells in Wiskott-Aldrich syndrome and after allogeneic transplantation with nonmyeloablative conditioning
Humblet-Baron, Stéphanie ULg

Doctoral thesis (2009)

Etude des Treg dans la physiopathologie du syndrome de Wiskott-Aldrich et étude de la reconstitution des Treg dans les greffes de cellules souches hématopoïétiques après un conditionnement ... [more ▼]

Etude des Treg dans la physiopathologie du syndrome de Wiskott-Aldrich et étude de la reconstitution des Treg dans les greffes de cellules souches hématopoïétiques après un conditionnement nonmyéloablateur. [less ▲]

Detailed reference viewed: 21 (3 ULg)
Full Text
See detailLa justice réparatrice en milieu carcéral : plasticité d’une fonction et malléabilité d’un concept criminologique
Dubois, Christophe ULg

Doctoral thesis (2009)

Although it is recognized as being inhuman by some people and inefficient by others, prison only seldomly serves as a gathering political objective. The ministerial circular of 4 October 2000, which is ... [more ▼]

Although it is recognized as being inhuman by some people and inefficient by others, prison only seldomly serves as a gathering political objective. The ministerial circular of 4 October 2000, which is implementing « restorative justice » in Belgian prisons, seems however to be an outstanding case in this matter as it includes prison in the political program. The new “restorative” discourse carried out by this circular creates a new role of “restorative justice consultant” and plans to assign one in each prison. The purpose of this book is to describe, analyze and account for the concrete practices through which this political discourse tends to take some social forms. Through an ethnographic work, the new “restorative” practices will be depicted and replaced in a policy and organizational analysis based on four case studies. [less ▲]

Detailed reference viewed: 121 (25 ULg)
Full Text
See detailLa fonction récréative des massifs forestiers wallons : analyse et évaluation dans le cadre d'une politique forestière intégrée
Colson, Vincent ULg

Doctoral thesis (2009)

An analysis of forest recreation in Wallonia has been carried out. The originality of the approach resides mainly in the fact that a regional scale was used. The precise meaning of “forest recreation” was ... [more ▼]

An analysis of forest recreation in Wallonia has been carried out. The originality of the approach resides mainly in the fact that a regional scale was used. The precise meaning of “forest recreation” was clarified by limiting it to the non benefit services. The analysis of the public demand was performed by means of three main surveys: a phone survey based on a sample of the Walloon and Brussels population, a survey within 40 woodlands (during 6 periods) and, finally, a survey conducted among managers of Forest Service districts in order to map the visitation level of all Walloon woodlands. Data concerning the recreational supply of the Walloon forest have been gathered as well. These data concerning supply and demand were used to create a model capable of forecasting the number of visits for the whole Walloon forest according to local population, one day tourists and holidaymakers. An economic assessment of these visits and the whole recreational function of the Walloon forest was made by adapting two methods (travel costs and the contingent valuation method) to the Walloon regional context and to the available data. All these investigations provided the quantification of the importance of the recreational function at a regional level as well as highlighting local variations. Recommendations related to the taking into account of forest recreation in forest policy, both at the regional level and at the local level were therefore proposed. [less ▲]

Detailed reference viewed: 66 (18 ULg)
Full Text
See detailGenotype by Environment Interaction for Production Traits of Holsteins Using Two Countries as Model: Luxembourg and Tunisia
Hammami, Hedi ULg

Doctoral thesis (2009)

Under globalization, breeding organizations are selecting animals and exchanging germplasm across various environments. Ignoring genotype by environment interaction (G x E) may affect the efficiency of ... [more ▼]

Under globalization, breeding organizations are selecting animals and exchanging germplasm across various environments. Ignoring genotype by environment interaction (G x E) may affect the efficiency of breeding strategies and limit outcomes from cooperation between breeding programs. Quantifying the effectiveness of indirect selection and effects of G x E for different breeds is therefore necessary. The objective of this thesis was to evaluate the magnitude of G x E for milk yield using Luxembourg and Tunisian Holstein populations. In fact, these two countries rely considerably on importation of superior genes from diverse origins for their breeding programs. This study needed records on both the genotype and the environment. In the first part of this thesis, genetic ties between the two populations were studied. Additive relationships and genetic similarity were important and genetic links have been strengthened with time which allowed the analysis of the phenotypic expression of daughters of common sires under each of these tow production environments. In the second part, genetic parameters for production traits of Tunisian Holsteins were estimated by a test-day random regression model (RRTD). Heritability estimates for 305-d milk, fat and protein yields were low to moderate (0.12 to 0.18) suspecting difficulties of high-producing cows to express their potential under limiting production conditions. In the third part, G x E for milk yield and persistency were investigated using character state models, where milk yield in each country was considered as a separate trait, and where the country border delimitation was designed as an environmental character state. A RRTD sire model was applied and was extended to a RRTD animal model. Significant G x E was detected for milk yield and persistency by both models. Large differences in genetic and permanent environmental variances between the two countries were observed. Genetic correlations for 305-d milk yield and persistency between Luxembourg and Tunisian Holsteins were 0.50 and 0.43 (sire model) and 0.60 and 0.36 (animal model). Moreover, low rank correlations obtained between estimated breeding values of common sires translate a significant re-ranking between the two environments. At the end of this thesis, a herd management (HM) parameter reflecting feeding and management intensity was defined. Three HM levels were identified in each country and G x E was investigated within- and across-environments. Significant G x E was detected between the Tunisian HM levels, whereas, only heterogeneous genetic variance for milk yield with limited re-ranking of sires across the three Luxembourg environments was observed. Overall, this thesis shows that under constraining environmental effects, selection for adaptive traits among economically valuable traits under their specific conditions is needed for low-input systems. When satisfactory feeding resources, management and husbandry practices are available, high degree environmental sensitivity is desired and the use of a high yielding breed may be encouraged. [less ▲]

Detailed reference viewed: 242 (39 ULg)
Full Text
See detailLes stratégies e-commerce des entreprises face au cadre juridique: une analyse exploratoire de la prise de risque dans le contexte belge
Lisein, Olivier ULg

Doctoral thesis (2009)

Après le scepticisme engendré par l’éclatement de la bulle Internet et la brutale chute de certaines "dot com", on assiste ces dernières années à une réelle "e-volution" des relations d’affaires et à un ... [more ▼]

Après le scepticisme engendré par l’éclatement de la bulle Internet et la brutale chute de certaines "dot com", on assiste ces dernières années à une réelle "e-volution" des relations d’affaires et à un essor particulièrement marqué du commerce électronique, lesquels confèrent désormais à Internet un statut d’espace marchand incontournable. Cet enthousiasme se heurte cependant au manque de confiance exprimé par certains acteurs économiques envers les échanges de type e-business/e-commerce, soulevant de façon sous-jacente la problématique de la régulation des transactions électroniques ainsi que de ses effets sur le comportement des consommateurs et le succès des stratégies e-commerce des entreprises. Alors que de nombreuses études abordent ces enjeux relatifs au commerce électronique sous un angle monodisciplinaire, notre propos s’inscrit dans une optique davantage transversale, basée sur l’interconnexion de différents courants théoriques issus des sciences de gestion et du droit. Prenant appui sur une vingtaine d’études de cas, issues de quatre secteurs d’activités contrastés en matière d’utilisation des technologies numériques, notre démarche réflexive interroge le positionnement stratégique des dirigeants d’entreprises envers l’e-commerce ainsi que l’influence que revêt à cet égard un nombre déterminé de facteurs : la nature des transactions opérées, la stratégie d’affaires poursuivie et le cadre juridique qui régit les relations commerciales établies par voie électronique. Articulées autour de la question de la prise de risque, que nous appréhendons essentiellement au travers du prisme de l’opportunisme possible des partenaires d’affaires, ces différentes variables permettent de mettre en évidence et de justifier des approches contrastées du commerce électronique de la part des responsables d’entreprises, en ce qui concerne aussi bien l’étendue des services proposés en ligne, le degré de numérisation du processus transactionnel ou encore la posture privilégiée par rapport aux dispositions réglementaires et aux éventuels mécanismes de protection à mobiliser. [less ▲]

Detailed reference viewed: 159 (29 ULg)
Full Text
See detailL’entrepreneuriat rural comme stratégie de la sécurité alimentaire au Sud-Kivu. Cas des localités Mwanda et Ciranga en territoire de Kabare.
Furaha Mirindi, Germaine ULg

Master's dissertation (2009)

Le présent travail qui porte sur l’entrepreneuriat rural comme stratégie de la sécurité alimentaire au Sud-kivu, cas des localités Mwanda et Ciranga en territoire de Kabare. En effet, l’intervention de ... [more ▼]

Le présent travail qui porte sur l’entrepreneuriat rural comme stratégie de la sécurité alimentaire au Sud-kivu, cas des localités Mwanda et Ciranga en territoire de Kabare. En effet, l’intervention de l’ONG Louvain Coopération au Développement dans le domaine entrepreneuriale à travers son partenaire GEL a motivée notre choix d’analyser l’impact de l’entrepreneuriat rural sur la sécurité alimentaire dans l’une des zones d’intervention de cette organisation. Nous nous sommes inspirée de Sen qui accorde plus d’importance à l’accès économique des populations aux denrées alimentaires. Il a alors été question de vérifier cette question dans le cadre de ce travail. A Ciranga et Mwanda il s’observe un régime foncier (non appropriation définitive des terres) limitant l’accès à la terre et sa mise en valeur, une faible production agricole liée à une moindre productivité des cultures, de l’élevage et de la pêche, ce qui rend la plupart des ménages pauvres avec une insuffisance alimentaire remarquée. Le manque de revenus pour les ménages apparaît comme un grand obstacle à l’achat des nourritures pour compenser l’insuffisance de l’autoconsommation. Face à cette situation, nous avons donc voulu, à travers cette étude, comprendre si l’entrepreneuriat pouvait être une stratégie pour les ménages d’être en possession des revenus afin de contribuer à l’atteinte de la sécurité alimentaire. Nous nous sommes fixés alors comme hypothèse de départ que l’entrepreneuriat rural pouvait en être une stratégie et que l’affectation des revenus issus de ces activités pourrait en prouver l’impact. Nous sommes alors parti de la compréhension des concepts clés de notre étude où nous avons abouti à dégager la définition suivante de la sécurité alimentaire : l’accès de tout individu à tout moment à la nourriture qu’il désire. Quant à ce qui est de l’entrepreneuriat nous avons retenu la définition selon laquelle l’entrepreneuriat consiste à prendre des risques. L’entrepreneur est alors une personne qui est prête à mettre en jeu sa carrière et sa sécurité financière pour mettre en œuvre une idée, à mettre son temps et son capital dans une entreprise risquée. Une autre définition de l’entrepreneuriat décrit le processus de découverte, d’évaluation et d’exploitation d’occasions. Ainsi un entrepreneur peut être défini comme « quelqu’un qui agit non en fonction des ressources qu’il contrôle actuellement, mais qui poursuit inlassablement une occasion. Ainsi nous avons retenu trois types d’entrepreneurs (créateur de valeur, combleur de vide et courtier stratège). Parmi cette typologie, l’entrepreneur comme créateur de valeur a plus intéressé notre étude. Une enquête a été menée dans le milieu d’étude auprès de 121 ménages afin de collecter des données sur la structure de ces ménages (taille, niveau d’étude des membres, leur âge,…), sur les activités entrepreneuriales et sur la sécurité alimentaire (accessibilité, disponibilité). Le test de khi-carré et la technique économétrique appliqués sur les principales variables (entrepreneuriat, genre, taille de ménages, niveau d’étude du chef de ménage et son âge), ont été utilisés pour l’analyse statistique. Grâce au modèle PROBIT nous avons descellé les variables qui expliquent au mieux la différence calorique que nous avons retenu comme indice de sécurité alimentaire selon les normes de la FAO. Les résultats révèlent que 60 chefs de ménages (49,5%) sur les 121 enquêtés pratiquent une activité entrepreneuriale quelconque. Les principales activités entrepreneuriales et leur importance sont : Le commerce (21,67%), la pêche (15%), l’agriculture (10%), la production de la boisson traditionnelle (8,3%), le transport (8%), Meunier (6,7%), Carrière des pierres (3,3%), Réparation (3%), Menuiserie (3%), Artisanat (3,3%), Cordonnerie (3%), Education (3,3%), Couture (1,6%), Savonnerie (1,7%), Boulangerie (1,7%), Restaurant (1,6%), santé (1,6%),production de la tourbe (1,7%). Ces résultats ont été satisfaisants car ils nous ont permis de faire une bonne comparaison et prouvent que la population du milieu étudié est entrepreneur, bien que leurs activités soient de petite taille et aboutit souvent à la survie des ménages. La non-couverture des besoins caloriques dans 98 ménages sur 121 enquêtés montre la situation de détresse alimentaire dans laquelle se trouve un nombre important de ménages. Si le mode de sondage ne nous permet pas d’utiliser ces données pour présenter des conclusions globales au niveau de la Province du Sud-kivu, elles sont néanmoins pertinentes pour illustrer la situation d’insécurité alimentaire d’une bonne partie du monde rural de cette province. Le résultat du test de khi-carré (X²) révèle que le degré de sécurité alimentaire est dépendant de manière significative de la capacité à épargner et de l’âge du chef de ménage, alors qu’elle est indépendante du genre et du niveau d’étude. La capacité à épargner des ménages est très bas car sur les 121 ménages, 4 seulement épargnent soit 3, 31%. L’entrepreneuriat rural et l’implication totale de la femme dans l’économie du ménage prédisposent à 78,5% le ménage à la sécurité alimentaire. Ce résultat affirme notre hypothèse de départ. L’importance de ces variables (entrepreneuriat rural et genre) dans le modèle PROBIT montre la nécessité d’entreprendre des actions pour améliorer la situation des ménages. Bien que les variables éducation et taille du ménage n’influencent pas significativement la sécurité alimentaire, les programmes de planning familial et d’éducation ont également un rôle pour prévenir l’insécurité alimentaire. En matière d'éducation, il s'agit non seulement d'accroître et d'améliorer l'offre (construction d'écoles, mise à disposition d'instituteurs) mais aussi de considérer toutes les contraintes liées à la demande (faiblesse des revenus, calendrier scolaire non adapté au calendrier agricole, etc.). Au terme de ce travail il est important de préciser que toutes les variables pouvant influencer de manière significative la sécurité alimentaire n’ont pas été identifiées. Ce travail étant une œuvre humaine, nous ne prétendons pas l’avoir achevé dans toute perfection. Cependant nous ouvrons une brèche à une étude ultérieure à d’autres chercheurs si pas nous même de pouvoir le compléter en étudiant par exemple l’efficacité des activités entrepreneuriales, l’importance de la croissance dans le domaine entrepreneuriale en milieu rural, la possibilité de créations d’agro-industries alimentaires, la nécessité de saisir les opportunités agricoles pour des productions commerçables, etc. [less ▲]

Detailed reference viewed: 49 (4 ULg)
See detailLa donation de titres de société
Krzesinski, Marjorie ULg

Master's dissertation (2009)

Detailed reference viewed: 91 (23 ULg)
Full Text
See detailContribution à l’élaboration d’un espace commun de représentation pour l’analyse morpho-fonctionnelle du membre supérieur : application à l’articulation glénohumérale
Schwartz, Cédric ULg

Doctoral thesis (2009)

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion ... [more ▼]

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion analysis systems provide dynamic measures. However, these measures may be distorted by the presence of soft tissues between the bones and the skin surface. First, we study a new method for correcting soft tissues artifacts when using external markers for motion estimation. This method is based on a surfacic approach and aims to follow the deformation created by the scapula on the skin surface. A robust registration algorithm, called IMCP, is used. This algorithm, developed in previous works, has been modified and adapted to be more specific to the study context: motion analysis using external markers. The improvements concern post-processing so as to make the most of the information mutualization properties of the IMCP, a way to take into account the influence of the edges of the markers clusters, and finally the optimization of the processing time thanks to multi-threading developments. In a second time, a specific MRI protocol is developed in order to allow morpho-functional analysis. Moreover, articular coherence indicators are proposed for the glenohumeral joint. These indicators are adapted to the case of errors in motion estimation. The results show that the use of a markers cluster covering all the scapula do not allow to follow the scapula print at skin surface. Thanks to simulation studies, two hypotheses are proposed to explain these results: the noise created by the soft tissues is too significant, and / or the available skin resolution is not sufficient. The relevance of proposing markerless analysis is so emphasized. Our morpho-functional study on the glenohumeral joint shows the significant influence of the motion analysis protocol on joint coherence during bones animation. The placement of the markers on the scapula and on the humerus as well as the choice of the motion estimation algorithm have a large influence on the bony structures motion estimation. [less ▲]

Detailed reference viewed: 94 (27 ULg)
Full Text
See detailEnvironmental Changes and Migration Flows. Normative Frameworks and Policy Responses.
Gemenne, François ULg

Doctoral thesis (2009)

Depuis quelques années, d’importants déplacements de populations sont régulièrement annoncés comme l’une des conséquences les plus dramatiques du changement climatique. Plusieurs dizaines de ... [more ▼]

Depuis quelques années, d’importants déplacements de populations sont régulièrement annoncés comme l’une des conséquences les plus dramatiques du changement climatique. Plusieurs dizaines de millions de personnes pourraient ainsi être contraintes à l’exil en raison des impacts du réchauffement global, selon les estimations les plus alarmistes. Ces prédictions, pourtant, relèvent d’une logique largement déterministe, qui simplifie souvent la relation entre dégradation environnementale et migrations à une causalité directe, et néglige l’importance des cadres normatifs. Cette thèse prend le contre-pied de l’approche déterministe dominante, et soutient que l’ampleur et la nature de ces flux migratoires ne dépendent pas uniquement des impacts du changement climatique, mais également – et surtout – des politiques qui seront mises en place pour limiter ces impacts et encadrer ces migrations. Elle adopte une posture constructiviste, et s’interroge sur la manière dont les réponses politiques apportées jusqu’ici aux mouvements de population provoqués par des dégradations environnementales influencent la conceptualisation du phénomène de ‘migrations environnementales’. Afin d’analyser le processus politique de mise en place de cadres normatifs et de réponses politiques en place au niveau international, la thèse utilise le modèle théorique de l’Advocacy Coalition Framework (ACF), mis au point par Sabatier et Jenkins-Smith. Dans un premier temps, la thèse analyse l’émergence du concept de ‘migrations environnementales’ dans la littérature et à l’agenda politique. La littérature sur le sujet est traversée par une opposition entre deux courants de pensée, que j’ai qualifiés respectivement de ‘sceptique’ et d’ ‘alarmiste’. Le courant sceptique, composé essentiellement de spécialistes des migrations, soutient que toute migration est multi-causale, et que l’environnement n’est pas un facteur migratoire plus déterminant qu’un autre. Ainsi, les sceptiques estiment que le concept de ‘migration environnementale’, considéré comme un type spécifique de migration, n’a guère de sens. A l’inverse, les alarmistes, qui sont essentiellement des spécialistes de l’environnement, affirment que les dégradations de l’environnement constituent un facteur croissant de migrations forcées, qui ont déjà commencé. Ces deux courants de pensée, qui trouvent leur origine dans un fossé disciplinaire, peuvent être analysés comme de véritables coalitions, qui pénètrent le processus politique. Le rôle des chercheurs dans la définition des politiques publiques est dès lors mis en avant, et la thèse émet l’hypothèse que cette opposition entre ‘alarmistes’ et ‘sceptiques’ a dépassé le champ académique pour traverser également le champ politique. La thèse entreprend alors de décrire et d’analyser le développement de normes et de politiques s’appliquant aux déplacements de populations liés à des dégradations de l’environnement dans deux sphères politiques distinctes : les politiques environnementales d’une part, et migratoires d’autre part. Dans les politiques environnementales, la thèse examine en particulier la gestion des catastrophes naturelles au niveau international, et les questions d’adaptation dans les négociations sur un nouveau traité international sur le changement climatique. Le domaine de la gestion des catastrophes naturelles s’est considérablement transformé au cours des dernières, et les personnes déplacées par les catastrophes sont au centre de plusieurs débats, ateliers et recommandations. Pour autant, ce sont négociations sur le changement climatique qui sont devenues, au fil des ans, le réceptacle premier des discussions et revendications sur les ‘migrations climatiques’. Les politiques migratoires, par contre, ont évolué dans un sens très différent. Le régime international de l’asile n’a guère évolué depuis la Convention de Genève de 1951 et son Protocole additionnel de 1967, et n’a guère pris en charge les nouvelles configurations des migrations forcées dans le monde, comme l’importance croissante aux dégradations de l’environnement. Les politiques d’asile et de mobilité n’ont pas non plus véritablement intégré la question, se cantonnant à des formes de protection complémentaires et/ou non contraignantes, dont pourraient se prévaloir ceux qui sont déplacés par une catastrophe naturelle. La thèse cherche à expliquer cette évolution différente par les différentes coalitions qui dominent ces sphères politique : les politiques migratoires sont dominées par les sceptiques, tandis que les politiques environnementales sont dominées par les alarmistes. Depuis le milieu des années 2000, les alarmistes dominent les débats sur les migrations environnementales, et ces débats se sont dès lors déplacés dans la sphère des politiques environnementales, et plus particulièrement dans celles des négociations sur le futur régime climatique. L’apparente réconciliation récente entre les deux coalitions marquent en réalité un glissement vers le terrain des politiques environnementales. Ce glissement révèle que le phénomène de ‘migrations environnementales’ reste largement conceptualisé de manière déterministe, et comme une migration forcée, inéluctable conséquence de l’échec de l’adaptation. Or, des illustrations empiriques, provenant de terrains effectués à La Nouvelle-Orléans après l’ouragan Katrina et à l’archipel de Tuvalu menacé par la montée des eaux, démontrent que cette conceptualisation ne correspond pas à la réalité des flux migratoires liés à des changements de l’environnement. La thèse souligne donc le caractère socialement construit des migrations environnementales, et l’importance du rôle joué par les politiques publiques. [less ▲]

Detailed reference viewed: 467 (15 ULg)
Full Text
See detailBiogeochemical study of coccolithophorid blooms in the context of climate change
Harlay, Jérôme ULg

Doctoral thesis (2009)

Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania ... [more ▼]

Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania huxleyi, are mainly found in the sub-polar and temperate oceans, where they produce huge blooms visible from space. Coccolithophores are sensitive to ocean acidification that results from the ongoing accumulation of anthropogenic carbon dioxide (CO2) in the atmosphere. The response of these organisms to global change appears to be related to the reduction of their ability to produce calcium carbonate at the cellular level. At the community levels, one anticipates changes in the carbon fluxes associated to their blooms as calcification is reduced. However, the consequences of such environmental changes on this species are speculative and require improvements in the description of the mechanisms controlling the organic and inorganic carbon production and export. The first aspect of this work was to study the response of these organisms to artificially modified CO2 concentrations representative of the conditions occurring in the past (glacial) and those expected by the end of the century (2100). Two different levels were examined: the continuous monospecific cultures (chemostats) allowed us to work at the cellular level while the mesocosms gave light to the mechanisms taking place in an isolated fraction of the natural community. The second aspect of this work consisted of field studies carried out during four cruises (2002, 2003, 2004 and 2006) in the northern Bay of Biscay, where the occurrence of E. huxleyi blooms were observed in late spring. I describe the vertical profiles of biogeochemical variables (nutrients, chlorophyll-a, dissolved inorganic carbon chemistry, particulate carbon, transparent exopolymer particles (TEP)) and study processes such as primary production, calcification and bacterial production. The properties of these blooms are compared with those reported in the literature and enriched with original measurements such as the abundance and concentration of TEP that could play an important role in carbon export to the deep ocean, modifying the properties of the settling ballasted aggregates. [less ▲]

Detailed reference viewed: 24 (3 ULg)
Full Text
See detailDépistage Néonatal de la Drépanocytose: Nouvelles Méthodologies
BOEMER, François ULg

Doctoral thesis (2009)

Detailed reference viewed: 32 (8 ULg)
See detailMéthode de Perturbation pour la Modélisation par Éléments Finis des Systèmes Électrostatiques en Mouvement - Application aux MEMS Électrostatiques
Boutaayamou, Mohamed ULg

Doctoral thesis (2009)

La modélisation par éléments finis des conducteurs en mouvement nécessite généralement des calculs successifs et le remalliage de certaines régions. Une modélisation 3D de géométries complexes par les ... [more ▼]

La modélisation par éléments finis des conducteurs en mouvement nécessite généralement des calculs successifs et le remalliage de certaines régions. Une modélisation 3D de géométries complexes par les techniques classiques nécessite dès lors de gros efforts en terme de temps de calcul. Dans cette thèse, une méthode originale basée sur une approche par sous-problèmes, appelée méthode de perturbation, a été développée. Utilisant la méthode des éléments finis, cette technique consiste à subdiviser un problème entier en sous-problèmes. La complexité du problème initial est par conséquent diminuée en ne se concentrant que sur les zones les plus pertinentes. Appliquée aux systèmes en mouvement, la méthode de perturbation permet d'exploiter les résolutions antérieures au lieu d'effectuer un nouveau calcul pour chaque position. L'analyse par la méthode de perturbation des microsystèmes électromécaniques (MEMS) électrostatiques comprenant des parties en déplacement ou en déformation est en outre considérée dans ce travail. Il est notamment question de démontrer l'implication naturelle de cette approche pour des simulations plus efficaces et plus précises des MEMS électrostatiques. [less ▲]

Detailed reference viewed: 78 (32 ULg)
See detailContribution à l'étude de la pathologie pleurale maligne.
DUYSINX, Bernard ULg

Doctoral thesis (2009)

Detailed reference viewed: 20 (1 ULg)
Full Text
See detailEtude moléculaire des short-chain isoprényle diphosphate synthases chez les pucerons : Evaluation de leur potentiel d’utilisation comme cible de nouveaux bio-insecticides
Vandermoten, Sophie ULg

Doctoral thesis (2009)

Les pucerons sont considérés comme des ravageurs majeurs, d’une part en raison de leur action directe sur le végétal, mais également en tant que vecteurs de nombreux virus phytopathogènes. A l’heure ... [more ▼]

Les pucerons sont considérés comme des ravageurs majeurs, d’une part en raison de leur action directe sur le végétal, mais également en tant que vecteurs de nombreux virus phytopathogènes. A l’heure actuelle, la lutte contre certaines espèces de pucerons, au moyen d’insecticides de synthèse, devient extrêmement difficile en raison de l’apparition de populations résistantes. Le développement de nouveaux produits antiparasitaires, visant spécifiquement les pucerons, devient, par conséquent, hautement souhaitable. Dans ce contexte, nous avons choisi de nous intéresser aux enzymes de la famille des « short-chain » isoprényle diphosphate synthases (scIPPS). Ces enzymes constituent une classe de prényltransférases impliquées dans le métabolisme des isoprénoïdes. Cette classe comprend la géranyle diphosphate synthase, la farnésyle diphosphate synthase et la géranylgéranyle diphosphate synthase qui respectivement synthétise le géranyle diphosphate (GPP, C10), le farnésyle diphosphate (FPP, C15), et le géranylgéranyle diphosphate (GGPP, C20). Nous avons cloné chez le puceron un nouveau type de scIPPS. Contrairement à d'autres scIPPS connues, l’enzyme recombinante du puceron affiche une activité bifonctionnelle ; cette dernière étant capable de synthétiser à la fois le GPP, le précurseur commun des monoterpènes, mais également le FPP, le précurseur des sesquiterpènes. Chez les pucerons, ces deux précurseurs sont supposés jouer un rôle clé dans la biosynthèse de l'hormone juvénile et des phéromones d'alarme et sexuelle. Dans le but de fournir une explication structurelle à la bifonctionnalité observée chez la GPP/FPP synthase de puceron, nous avons entrepris de résoudre sa structure tridimensionnelle en se basant sur les structures cristallographiques du poulet. Plusieurs mutants ont été ensuite conçus et caractérisés. [less ▲]

Detailed reference viewed: 66 (29 ULg)
Full Text
See detailModélisation et résolution du problème de contact mécanique et son application dans un contexte multiphysique
Bussetta, Philippe ULg

Doctoral thesis (2009)

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non ... [more ▼]

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non differentiability of the contact's equations (stick/unstick and the initiation of sliding). Until now, no method could be used to resolve all contact problems. This work is focused on the methods of calculation of the mechanical contact in a more general way. It could be separated in two parts. The first one concerns the creation of the systems of equations and the algorithm of resolution. The methods more used are the Penalty Method and Lagrangian Augmented Method. Although these methods are simple, they are very difficult to use because the choice of the value of penalty coefficients (normal and tangential). For this reason, a new method, the "Lagrangian Augmented Adapted Method" is proposed. This new method is based on the Lagrangian Augmented Method and on the adaptation of the penalty coefficients. With it, the user does not need to choose the value of penalty coefficients. In addition, this method has the speed of the Penalty Method and the reliability of the Lagrangian Augmented Method. The second part of this work deals with the calculation of the mechanical contact under a spatial disctretization. The method more used is the "Point-Surface" Method. The contact is calculated between every point of one surface and the other surface. This method has many limits, as the representativeness and the regularity of the solution when the boundaries are deformable and irregular. Many researches are done on another method, the "Surface-Surface" Method based on the Mortar Element Method. The mechanical contact is calculated on each node of one surface in function of the two surfaces. With this method the solution is more regular and reliable. But the calculation of the mechanical contact is more difficult, so it can not be used to the three dimensional problems. An adaptation of this method has been proposed to the two and three dimensional problems. All these methods are tested on some academics and industrials multi-physical problems. [less ▲]

Detailed reference viewed: 280 (18 ULg)
Full Text
See detailSolute transport modelling at the groundwater body scale: Nitrate trends assessment in the Geer basin (Belgium)
Orban, Philippe ULg

Doctoral thesis (2009)

Water resources management is now recognized as a multidisciplinary task that has to be performed in an integrated way, within the natural boundaries of the hydrological basin or of the aquifers. Policy ... [more ▼]

Water resources management is now recognized as a multidisciplinary task that has to be performed in an integrated way, within the natural boundaries of the hydrological basin or of the aquifers. Policy makers and water managers express a need to have tools able at this regional scale to help in the management of the water resources. Until now, few methodologies and tools were available to assess and model the fate of diffuse contaminants in groundwater at the regional scale. In this context, the objective of this research was to develop a pragmatic tool to assess and to model groundwater flow and solute transport at the regional scale. A general methodology including the acquisition and the management of data and a new flexible numerical approach was developed. This numerical approach called Hybrid Finite Element Mixing Cell (HFEMC) was implemented in the SUFT3D simulator developed by the Hydrogeology Group of the University of Liège. A first application of this methodology was performed on the Geer basin. The chalk aquifer of the Geer basin is an important resource of groundwater for the city of Liège and its suburbs. The quality of this groundwater resource is threatened by diffuse nitrate contamination mostly resulting from agricultural practices. New field investigations were performed in the basin to better understand the spatial distribution of the nitrate contamination. Samples were taken for environmental tracers (tritium, CFC’s and SF6) analysis. The spatial distribution of environmental tracers concentrations is in concordance with the spatial distribution of nitrates. This allows proposing a coherent interpretative schema of the groundwater flow and solute transport at the regional scale. These new data and the results of a statistical nitrate trend analysis were used to calibrate the groundwater model developed with the HFEMC approach. This groundwater flow and solute transport model was used to forecast the evolution of nitrate concentrations in groundwater under a realistic scenario of nitrate input for the period 2008-2058. According to the modelling results, upward nitrate trends observed in the basin will not be reversed for 2015 as prescribed by the EU Water Framework Directive. The regional scale groundwater solute transport model was subsequently used to compute nitrate concentrations in groundwater under different scenarios of nitrate input to feed a socio-economic analysis performed by BRGM. These computed concentrations were used to assess the benefit, for the users, linked to the reduction of contamination resulting from the changes in nitrate input. These benefits were compared to the costs associated to the implementation of the considered agri-environmental schemes that allow reducing the nitrate input to groundwater. [less ▲]

Detailed reference viewed: 130 (41 ULg)
Full Text
See detailGeometry and Symmetries in Coordination Control
Sarlette, Alain ULg

Doctoral thesis (2009)

The present dissertation studies specific issues related to the coordination of a set of “agents” evolving on a nonlinear manifold, more particularly a homogeneous manifold or a Lie group. The viewpoint is ... [more ▼]

The present dissertation studies specific issues related to the coordination of a set of “agents” evolving on a nonlinear manifold, more particularly a homogeneous manifold or a Lie group. The viewpoint is somewhere between control algorithm design and system analysis, as algorithms are derived from simple principles — often retrieving existing models — to highlight specific behaviors. With a fair amount of approximation, the objective of the dissertation can be summarized by the following question: Given a swarm of identical agents evolving on a nonlinear, nonconvex configuration space with high symmetry, how can you define specific collective behavior, and how can you design individual agent control laws to get a collective behavior, without introducing hierarchy nor external reference points that would break the symmetry of the configuration space? Maintaining the basic symmetries of the coordination problem lies at the heart of the contributions. The main focus is on the global geometric invariance of the configuration space. This contrasts with most existing work on coordination, where either the agents evolve on vector spaces — which, to some extent, can cover local behavior on manifolds — or coordination is coupled to external reference tracking such that the reference can serve as a beacon around which the geometry is distorted towards vector space-like properties. A second, more standard symmetry is to treat all agents identically. Another basic ingredient of the coordination problem that has important implications in this dissertation is the reduced agent interconnectivity: each agent only gets information from a limited set of other agents, which can be varying. In order to focus on issues related to geometry / symmetry and reduced interconnectivity, individual agent dynamics are drastically simplified to simple integrators. This is justified at a “planning” level. Making the step towards realistic dynamics is illustrated for the specific case of rigid body attitude synchronization. The main contributions of this dissertation are I. an extensive study of synchronization on the circle, (a) highlighting difficulties encountered for coordination and (b) proposing simple strategies to overcome these difficulties; II. (a) a geometric definition and related control law for “consensus” configurations on compact homogeneous manifolds, of which synchronization — all agents at the same point — is a special case, and (b) control laws to (almost) globally reach synchronization and “balancing”, its opposite, under general interconnectivity conditions; III. several propositions for rigid body attitude synchronization under mechanical dynamics; IV. a geometric framework for “coordinated motion” on Lie groups, (a) giving a geometric definition of coordinated motion and investigating its implications, and (b) providing systematic methods to design control laws for coordinated motion. Examples treated for illustration of the theoretical concepts are the circle S^1 (sometimes the sphere S^n ), the rotation group SO(n), the rigid-body motion groups SE(2) and SE(3) and the Grassmann manifolds Grass(p,n). The developments in this dissertation remain at a rather theoretical level; potential applications are briefly discussed. [less ▲]

Detailed reference viewed: 315 (24 ULg)
Full Text
See detailSOURCES DE VARIATION PHÉNOTYPIQUE DES TRAITS D’HISTOIRE DE VIE D’UNE ESPÈCE INVASIVE, SENECIO INAEQUIDENS DC. (ASTERACEAE).
Monty, Arnaud ULg

Doctoral thesis (2009)

L’importance des différentes sources de variation phénotypique que sont l’adaptation, la plasticité phénotypique, les effets maternels environnementaux, le niveau de ploïdie et la dérive génétique, a été ... [more ▼]

L’importance des différentes sources de variation phénotypique que sont l’adaptation, la plasticité phénotypique, les effets maternels environnementaux, le niveau de ploïdie et la dérive génétique, a été analysée pour différents traits d’histoire de vie, au sein de l’aire colonisée par une espèce végétale invasive. A cette fin, plusieurs expériences en jardins communs ont été installées, dont deux en transplantations réciproques. Les populations considérées étaient localisées en Belgique, en France, ainsi que dans l’aire d’indigénat de l’espèce. Senecio inaequidens DC. (Asteraceae), l’espèce étudiée dans ce travail, est une plante d’origine africaine accidentellement introduite en Europe par le commerce lainier, vers la fin du 19ème siècle. Dans son aire d’indigénat, elle présente deux niveaux de ploïdie, diploïde et tétraploïde. Seuls des plants tétraploïdes sont recensés en Europe. L’espèce présente un historique de colonisation particulier, bien documenté, qui en fait un modèle idéal pour les études évolutives. Les traits d’histoire de vie considérés ont été scindés en deux groupes. Les premiers concernaient la germination, la croissance et la reproduction sexuée. Les sources de variation phénotypique dans ces traits ont été principalement analysées en relation avec les variations climatiques dans l’aire d’invasion, le long de gradients d’altitude, ainsi qu’en relation avec le niveau de ploïdie et l’aire d’origine (aire d’indigénat vs aire d’invasion). Le deuxième groupe de traits considérés concernaient les capacités de dispersion de l’espèce. Celles-ci ont été modélisées. La variabilité phénotypique dans ces traits a ensuite été analysée, parmi les populations françaises, en relation avec l’éloignement depuis le site de première introduction. Les résultats ont montré des différences entre les cytotypes de l’espèce, principalement dans les capacités de survie hivernale. Le long des gradients d’altitude, les populations de S. inaequidens présentaient des différenciations phénotypiques de type clinal, dans les traits de croissance. Ces différenciations étaient d’origine génétique, même si les effets maternels environnementaux sont apparus comme des sources non-négligeables de variation phénotypique dans les zones à climat rigoureux. Parmi les traits liés à la dispersion, le plume loading était le mieux corrélé aux capacités de dispersion par le vent. Des différenciations clinales ont été détectées dans les traits de dispersion, en jardin commun, mais n’ont pas été vérifiées en populations naturelles. [less ▲]

Detailed reference viewed: 274 (52 ULg)
See detailCaractérisation de l’induction de mécanismes de défense et de l’émission de sémiochimiques chez Solanum lycopersicum L. en réponse à la présence de miellat
De Clerck, Caroline ULg

Master's dissertation (2009)

Le miellat est une substance épaisse et collante rejetée sur les feuilles et au pied de la plante-hôte par les pucerons pour éliminer l’excédent de sucres qu’ils consomment. Des travaux récents ont montré ... [more ▼]

Le miellat est une substance épaisse et collante rejetée sur les feuilles et au pied de la plante-hôte par les pucerons pour éliminer l’excédent de sucres qu’ils consomment. Des travaux récents ont montré qu’en plus des sucres et des acides aminés, le miellat contenait plusieurs souches bactériennes. L’objectif de ce travail est de déterminer si cette excrétion des pucerons possède un pouvoir éliciteur, à savoir si elle est capable de provoquer une réaction de défense de la part de la plante, ce qui la rendrait plus résistante à des attaques ultérieures. Pour ce faire, différentes étapes dans la mise en place des défenses chez la plante ont été ciblées. Une alcalinisation du milieu extracellulaire chez des cellules de tabac a été observée, essentiellement provoquée par la bactérie S. sciuri contenue dans le miellat. Les résultats permettent également de suspecter une action combinée de la bactérie avec un ou plusieurs de ses métabolites. La mise en présence de plantes entières traitées avec du miellat et du champignon pathogène B. cinerea a permis d’observer une meilleure résistance des plantes traitées. De plus, des cellules de tabac mises en présence de la bactérie S. sciuri montrent une forte mortalité, sans doute due à une réponse hypersensible. Des essais de chémiluminescence et de prélèvement de molécules volatiles ont été réalisés afin de confirmer ces observations mais n’ont donné aucun résultat significatif. Il est donc difficile de conclure, sur base de ces résultats, à l’existence d’un réel pouvoir éliciteur du miellat. Au vu des premiers résultats obtenus ici et afin de les affiner, d’autres techniques plus sensibles devraient être utilisées. [less ▲]

Detailed reference viewed: 144 (14 ULg)
Full Text
See detailLes quartiers durables : processus de production et reproductibilité
Marique, Anne-Françoise ULg

Master's dissertation (2009)

Detailed reference viewed: 150 (34 ULg)
Full Text
See detailÉtude de la modalité en néo-égyptien
Polis, Stéphane ULg

Doctoral thesis (2009)

Cette thèse constitue la première étude générale de la modalité en néo-égyptien. Le chapitre introductif (p. 5-43) est consacré [1] à la définition de ce premier état de langue de l’égyptien de la seconde ... [more ▼]

Cette thèse constitue la première étude générale de la modalité en néo-égyptien. Le chapitre introductif (p. 5-43) est consacré [1] à la définition de ce premier état de langue de l’égyptien de la seconde phase ; cette définition a permis la délimitation d’un corpus servant d’assise empirique à l’étude (la répartition du corpus en fonction de critères chronologiques et géographiques, de la nature du support et des "Textsorten" a donné la possibilité de pondérer et d’objectiver les analyses proposées pour chaque expression de la modalité). Ensuite, [2] un cadre théorique général pour l’étude de la langue est discuté. Le corps du travail se divise en trois parties consacrées respectivement : [1] à une définition générale de la notion de modalité (cela afin de déterminer les media expressifs qui relèvent de son étude en néo-égyptien) ainsi qu’à l’établissement d’un modèle sémantique à la fois économique, cohérent et correspondant aux données typologiques (p. 44-115) ; [2] à l’étude des modalités radicales (i.e. les modalités déontiques et bouliques en envisageant les relations qu’elles entretiennent avec le domaine axiologique ; p. 116-341) ; [3] à l’examen des modalités assertives (p. 342-446) : [a] analyse des formes de complémentation, en ce compris les liens entre intégration syntaxique, variation de l’assertivité et degré de manipulation, [b] étude de l’impact des auxiliaires d’énonciation sur le degré d’assertivité d’une proposition, [c] critique des théories existantes concernant les moyens expressifs du discours indirect en néo-égyptien. Les conclusions (p. 447-466) sont accompagnées de propositions prospectives devant permettre [1] de rendre le modèle défendu applicable à l’étude des complexes conditionnels, [2] d’intégrer la dimension énonciative dans l’analyse des relations interpersonnelles, [3] de proposer une approche globale des media expressifs de la causalité et de la finalité. [less ▲]

Detailed reference viewed: 357 (18 ULg)
See detailContribution à l'étude de métabolites secondaires d'Harmonia axyridis (Pallas) en relation avec la coloration de l'insecte
Fischer, Christophe ULg

Master's dissertation (2009)

This work aims to study secondary metabolites of Harmonia axyridis (Pallas) (Coccinellidae) in relation with the insect color. To achieve this goal, two original quantification methods of insect secondary ... [more ▼]

This work aims to study secondary metabolites of Harmonia axyridis (Pallas) (Coccinellidae) in relation with the insect color. To achieve this goal, two original quantification methods of insect secondary metabolites have been devised. The first one allows quantifying harmonine which is its main defense alkaloid; the other one permit to determine its emission rate of 2-isopropyl-3-methoxypyrazine which is highly odorous compound probably involved in the communication between individuals and in the aposematism of this insect. As well, a method for characterizing the elytra color has been developed. First of all, a method of extraction, acetylation and purification of harmonine from Harmonia axyridis has been devised to obtain a calibration standard because this molecule is not available commercially. The identity of the compound extracted has been confirmed by mass spectrometry and NMR. The GC purity of this N,N-diacetylharmonine is of 100%. Its stability in acetonic solution at 4°C has been verified. Using this purified molecule, an original method of harmonine quantification has been developed by ultra fast gas chromatography and validated using accuracy profile. This method allows quantifying harmonine in one single insect. Afterward, an original method for determining the emission rate of 2-isopropylmethoxypyrazine of a Harmonia axyridis by TD-GC-MS has been validated. These two methods and the picture analysis script have been used to analyze 80 Harmonia axyridis divided in four groups of at least 15 individuals on basis of the morph type and the elytra hue. The mean 2-isopropyl-3-methoxypyrazine emission rate of a Harmonia under stress is of 707 pg/4h with a standard deviation of 1766pg/4h. The mean harmonine content is of 106,6µg/individual with a standard deviation of 80,2µg/individual. So a strong variability between individuals is observed. Results have been statistically analyzed in order to show potential correlations between these factors. What emerges is that elytra color seems to be linked with the insect harmonine content and its pyrazine emission rate. Individuals with a non-melanic orange color present a harmonine content significantly higher than other studied colors while individuals with a melanic red color show a lower pyrazine emission rate. Leads explaining the high variability observed have been researched. It seems that elytra black pattern is mainly influenced by genetic factors and that the hue is influenced by environmental and seasonal factors. The harmonine content and the pyrazine emission rate do not seem influenced by the population of origin in a limited geographic area. These conclusions are to take with caution because of samples size. It only opens ways to future researches. The harmonine quantification method has been transposed to Coccinella septempunctata in order to study intraguilde predation by searching exogenous sequestrated alkaloids. It seems possible to use the image analysis script as classification and elytra color characterization tool. [less ▲]

Detailed reference viewed: 209 (24 ULg)
Full Text
See detailTypologie d’exploitations agricoles familiales dans la province de Hai Duong au Vietnam
Andres, Ludovic ULg

Master of advanced studies dissertation (2009)

Detailed reference viewed: 24 (9 ULg)
Full Text
See detailBiochemical markers and radiographic scores as an evaluation for the osteochondral status of Warmblood stallions
Verwilghen, Denis ULg

Master of advanced studies dissertation (2009)

Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could reveal to be an interesting alternative to this ... [more ▼]

Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could reveal to be an interesting alternative to this procedure which is time consuming and sometimes technically difficult. The aim of this study was to investigate the relationship between the radiological status of the horses and the levels of biochemical markers of cartilage degradation and synovial inflammation. A specific radiological scoring and classification system was therefore developed and applied on 63 stallions presented for studbook admission. Additionally, groups of horses were established according to the occurrence of osteochondrosis, degenerative joint disease and distal interphalangeal joint effusion. Insulin growth factor-I, myeloperoxidases, Coll2-1 and Coll2-1NO2 were used as blood markers. The combination of the blood parameters did not seem to correlate with the used scoring system. Coll2-1NO2 levels however tended to increase with poorer radiological class and this could therefore potentially be a useful predictor of the osteoarticular status in the horse. Coll2-1 levels were significantly higher in the degenerative joint disease group. A high percentage of horses with distal interphalangeal joint effusion was present in this study and was associated with decreased IGF-I and increased Coll2 [less ▲]

Detailed reference viewed: 35 (9 ULg)
Full Text
See detailLe commerce sensible des biens à double usage : analyses des législations européennes et des États-Unis
Rasson, Frédéric ULg

Master's dissertation (2009)

L’Union européenne a réglementé le commerce sensible des biens et technologies à double usage. Quelles différences existent entre le système harmonisé européen de contrôle sur les exportations d’articles ... [more ▼]

L’Union européenne a réglementé le commerce sensible des biens et technologies à double usage. Quelles différences existent entre le système harmonisé européen de contrôle sur les exportations d’articles à double usage et le contrôle organisé par les États-Unis ? [less ▲]

Detailed reference viewed: 191 (14 ULg)
Full Text
See detailLes imaginaires des migrants lesbiennes et gays latino-américains à propos de l'Europe. Analyse de récits de vie de chilien(ne)s péruvien(ne)s et colombiens.
Berlage, Pauline ULg

Master of advanced studies dissertation (2009)

Dans ce travail, nous nous sommes donc interessée aux migrants lesbiennes et gays latino-américains et nous nous sommes posée la question suivante : « Quels sont les imaginaires des migrants lesbiennes et ... [more ▼]

Dans ce travail, nous nous sommes donc interessée aux migrants lesbiennes et gays latino-américains et nous nous sommes posée la question suivante : « Quels sont les imaginaires des migrants lesbiennes et gays latino-américains à propos de l’Europe ? » Nous avons comparé les imaginaires des lesbiennes et des gays au sujet de l’Europe avant de quitter l’Amérique latine avec ceux des lesbiennes et gays latino-américains qui vivent maintenant en Europe (en Belgique et en Espagne) ou qui sont revenus dans leur pays d’origine. À travers cette double question, nous avons voulu comprendre comment se forment ces images ainsi que les rapports de forces qui entrent en ligne de compte pour ces acteurs. En effet, peut-être y a-t-il un rapport de domination (hétéro-normativité) dans la société d’origine qui pousse les LGBT à migrer. Ce rapport de domination peut également exister dans le pays d’accueil, et, dans ce cas, il pourrait être intéressant d’observer les négociations mises en place. De plus, une fois ces migrants arrivés en Europe, ceux-ci peuvent se trouver au coeur d’un autre rapport de force entre le poids de la tradition et de la culture de la communauté d’origine et celle de la société d’accueil. Nous avons tenté d’expliquer comment les imaginaires de cette population spécifique de migrants se constituent, quels sont les facteurs, les conditions ou idéologies qui participent à la formation de ces imaginaires à propos de l’Europe. Cette étude comporte également des dimensions temporelle et spatiale. Nous avons, en effet, comparé les imaginaires des lesbiennes et gays vivants en Amérique latine avec celles des lesbiennes et gays immigrés en Belgique et en Espagne et ceux qui sont revenus au pays – et donc à une étape plus avancée de leur parcours migratoire –. De plus, la perspective transnationale de cette étude permettra de comprendre comment ces imaginaires se redéfinissent dans un mouvement d’aller-retour incessant entre les pays d’origine et le pays d’accueil. [less ▲]

Detailed reference viewed: 103 (4 ULg)
See detailBiopsies rectales chez le cheval : technique, innocuité, et valeur diagnostique de l'examen histopathologique.
Leroux, Aurélia ULg

Master of advanced studies dissertation (2009)

La biopsie rectale est couramment utilisée sur les chevaux présentant un amaigrissement, de la diarrhée chronique ou des coliques récidivantes. Le but de cette étude est la mise au point de cette ... [more ▼]

La biopsie rectale est couramment utilisée sur les chevaux présentant un amaigrissement, de la diarrhée chronique ou des coliques récidivantes. Le but de cette étude est la mise au point de cette technique, l’étude de son innocuité et de sa valeur diagnostique. Huit biopsies rectales sont prélevées en différents endroits, avec la pince à biopsie utérine de la clinique, sur chacun des 12 chevaux de l’étude, 7 malades et 5 témoins, sous anesthésie générale ou simple sédation. Des prélèvements de duodénum, iléon, caecum, colon et rectum sont effectués post mortem sur chaque cheval. Un examen histopathologique sur lames colorées à l’hématoxyline-éosine, est réalisé. Pour un droitier, il est plus facile de prélever dans le cadran supérieur droit. Les autopsies montrent que 91% des biopsies à 30 cm de l’anus et 48% de celles à 15 cm sont localisées en avant du cul-de-sac rétropéritonéal. Des hématomes sont fréquents (44%) surtout ventralement. Une seule perforation est observée. Au microscope, l’inflammation sur les biopsies rectales est plus marquée à 30 cm et chez les chevaux malades. Des études similaires avec la méthode proctoscopique et avec une pince à biopsie utérine de plus petit calibre, seraient intéressantes en vue de comparer les résultats. [less ▲]

Detailed reference viewed: 268 (3 ULg)
Full Text
See detailContamination du marsouin commun (Phocoena phocoena) de la Mer du Nord par des perturbateurs endocriniens persistants
Didimo Imazaki, Pedro Henrique ULg

Master's dissertation (2009)

Endocrine disrupters are molecules able to interfere with the endocrine system and are largely spread in the environment. The evaluation of the estrogenic activity of some of these substances by reporter ... [more ▼]

Endocrine disrupters are molecules able to interfere with the endocrine system and are largely spread in the environment. The evaluation of the estrogenic activity of some of these substances by reporter gene assays was the first aim of this paper. The substances chosen are also persistent organic pollutants (POP), which are capable to bioaccumulate in several organisms. Then, the occurrence of these substances was evaluated in the blubber tissue of North Sea harbour porpoises (Phocoena phocoena). Harbour porpoises are good indicators of the environmental contamination and therefore of seafood by POP. These POP were quantified by GC-MS and also by reporter gene assays. For the achievement of these aims, different analytical methods were developed. The following raking is proposed for the studied substances, according to their estrogenic activity: o,p’-DDT > o,p’-DDD > β-HCH > p,p’-DDT > p,p’-DDD > p,p’-DDE > δ-HCH > PCB 138 > γ-HCH > α-HCH > PCB 153 > HCB > PCB 180. None of them presented anti-estrogenic activity. The analysed samples presented high levels of POP, sometimes associated with estrogenic activity, confirming the occurrence of endocrine disruptors in these animals. [less ▲]

Detailed reference viewed: 81 (17 ULg)
See detailLes dieux et leurs statues dans la céramique attique et italiote
Collard, Hélène ULg

Master's dissertation (2009)

Detailed reference viewed: 44 (8 ULg)
Full Text
See detailLes arabismes du français selon le Trésor de la Langue française
Baiwir, Esther ULg

Master's dissertation (2009)

Detailed reference viewed: 642 (7 ULg)
Full Text
See detailLes matières colorantes au début du Paléolithique supérieur : sources, transformations et fonctions
Salomon, Hélène ULg

Doctoral thesis (2009)

Abstract : Despite an increasing number of studies, colouring materials are still poorly understood among excavation remains. Their attraction lies in their capacity to bring to light diverse and complex ... [more ▼]

Abstract : Despite an increasing number of studies, colouring materials are still poorly understood among excavation remains. Their attraction lies in their capacity to bring to light diverse and complex skills, but also in their intense colouring power and their contrasting colours : red and black, which still possess a symbolic value. These highly symbolic materials may, therefore, highlight the “conceptual” practices of prehistoric men and give access to their symbolic world and thought. In such a particular context as the transition between the Middle and the Upper Palaeolithic, these remains, which are very abundant in most excavations, offer the possibility, through analysis, to get an exceptional insight into the way of life of the last Neanderthals. The Châtelperronian site of the “Grotte du Renne”, in Arcy-sur-Cure (Yonne), is a landmark. It was excavated beween 1949 and 1963 by André Leroi-Gourhan : Numerous colouring materials were discovered there, and Leroi-Gourhan developed theories about their transformation and uses which so far have not been tested, and have remained unchallenged.Since their discovery, the assumption is that those minerals were heated in a controlled way, in order to modify their colour. It is indeed well-known that heat transforms yellow materials (iron hydroxides) in orange, red or purple materials (iron oxides). From this hypothesis originates the theory according to which Neanderthals exploited colouring materials as pigments for symbolic or even aesthetic purposes. But the theory has so far never been proved true. Our study combines several sets of data, obtained from different methods. Physico-chemical and petrological analyses were carried out on the colouring materials. These data were related to their location on the site, in association with exceptionally well preserved “hut” structures. Furthermore, a series of experimentations, aimed to characterize powders obtained via different methods (grinding and crushing on the one hand, abrasion on the other hand). The comparison of all these data enabled us to identify the various technical choices which informed the supply in colouring minerals in all the Châtelperronian levels of the Grotte du Renne. It was thus possible to demonstrate that none of these materials, either red or black, was heated before being used, contrary to what had been assumed so far. The supply in colouring materials was as carefully organised as for other materials (flint, for example) ; they were collected in geological formations occasionally showing on the surface, at more than 10 km from the cave. The exploitation of these geological sites did not vary during the whole Châtelperronian period, and privileged materials which can easily be ground into powder. Part of their supply was ground coarsely in order to cover large surface areas (soils or hides) as preservative or to clean them up. The remaining materials were destined to more meticulous activities, which required a fine, regular, and highly-colouring powder. In this latter case, the Neanderthals of the Grotte du Renne used those products when working on bone materials (bone or mammoth ivory), and used them also for their sheer colour. The set of colouring minerals from the Grotte du Renne reveals Neanderthals’ in-depth knowledge of materials ; they understood perfectly well their properties and qualities, and used them extensively, so that the Châtelperronian site must have been a literally dazzling sight, all red and black. The “chaîne opératoire” which transpires from our analysis shows very sophisticated techniques, and an advanced “technological” knowledge. They are witness to surprising capacities and a highly-evolved pattern of thought. [less ▲]

Detailed reference viewed: 362 (13 ULg)
Full Text
See detailCrucial role of reversible phosphorylation in the mechanisms governing the biological functions of class IIa Histone Deacetylases
Martin, Maud ULg

Doctoral thesis (2009)

Regulation of class IIa histone deacetylases (HDACs) phosphorylation is crucial because it provides the opportunity to control important developmental processes associated with these key enzymes. Indeed ... [more ▼]

Regulation of class IIa histone deacetylases (HDACs) phosphorylation is crucial because it provides the opportunity to control important developmental processes associated with these key enzymes. Indeed, the transcriptional repressor activity of class IIa HDAC is controlled via their phosphorylation-dependent nucleo-cytoplasmic shuttling. While a lot of efforts have been directed towards the identification of the inactivating kinases that phosphorylate class IIa HDACs, the identity of the antagonist phosphatase remained an open question. During this work, we found that protein phosphatase 2A (PP2A) is responsible for dephosphorylating the class IIa HDACs member HDAC7, thereby regulating its subcellular localization and repressor activity. In order to validate our model, functional consequences of these findings was illustrated during the two main biological processes involving HDAC7, i.e. T-cells apoptosis during negative selection and endothelial cells angiogenic activities during vascular network formation. Cellular PP2A represents a large population of trimeric holoenzymes containing a variable regulatory subunit, whose identity has a crucial role in determining the specificity of PP2A catalytic activity. In an effort to characterize the regulation of HDAC7 dephopshorylation, we identified the relevant PP2A holoenzyme regulating HDAC7 function during vasculogenesis and we found that, among diverse regulatory subunit isoforms, PP2A-Bα uniquely regulates endothelial cell angiogenic properties. PP2A-Bα silencing using small interfering RNAs results in a significant inhibition of endothelial cell tube formation and migration. These results establish PP2A, and more precisely the Bα containg PP2A holoenzyme, as an essential element in the regulation of the class IIa HDACs HDAC7 and unravel a first developmental function for the PP2A regulatory subunit Bα in the genesis of blood vessels. [less ▲]

Detailed reference viewed: 76 (7 ULg)
See detailEtude des processus inconscients d'auto-activation et d'auto-inhibition de l'action motrice par imagerie par résonance magnétique fonctionnelle
D'Ostilio, Kevin ULg

Master's dissertation (2009)

Bien que plusieurs recherches aient soulignées l’importance des mécanismes automatiques et inconscients dans le contrôle de l’action motrice, les substrats neuronaux impliqués dans ce genre de processus ... [more ▼]

Bien que plusieurs recherches aient soulignées l’importance des mécanismes automatiques et inconscients dans le contrôle de l’action motrice, les substrats neuronaux impliqués dans ce genre de processus sont encore peu connus. En effet, les expérimentations précédentes ont démontré une implication de certaines régions cérébrales en utilisant uniquement pour la plupart une approche lésionnelle. Ce travail avait donc pour but d’identifier les corrélats cérébraux de ces processus au moyen de l’imagerie par résonance magnétique fonctionnelle, pendant l’administration d’une tâche d’amorçage subliminal masquée à des volontaires sains. Dans cette tâche visuomotrice, les sujets doivent répondre le plus rapidement possible à une flèche cible congruente ou non avec l’amorce subliminale cachée qui la précède. Ce paradigme permet, en manipulant l’intervalle entre le masque et la cible, de mettre en évidence un effet de compatibilité positive ou négative sur les temps de réaction. L’effet de compatibilité négative (ECN) a été interprété comme une conséquence d’une inhibition automatique qui supprime l’activation motrice produite par l’amorce. L’ECN engendre un conflit de réponse, les sujets mettant donc un temps plus important pour répondre à une flèche qui a été préalablement inhibée. Nous avons, dans un premier temps, répliqué les résultats comportementaux de la tâche d’amorçage subliminal masquée. Dans un second temps, en accord avec les autres études dans le domaine, nous avons démontré que la simple perception inconsciente d’un stimulus pouvait activer les régions cérébrales sous-tendant la représentation, la sélection et l’initiation de l’action motrice, alors que l’inhibition se traduit principalement par une diminution de l’activité de ces régions. Cette découverte apporte une nouvelle contribution à l’explication de la pathophysiologie des troubles hyperkinétiques. [less ▲]

Detailed reference viewed: 205 (34 ULg)
Full Text
See detailAlgebraic approach to modal extensions of Łukasiewicz logics
Teheux, Bruno ULg

Doctoral thesis (2009)

Detailed reference viewed: 125 (8 ULg)
Full Text
See detailLa coopération roumaine au développement : exercice d'approche goffmannienne
Teclu, Codrat Alin ULg

Master's dissertation (2009)

L’objectif du présent mémoire est de comprendre comment un pays, en l’occurrence la Roumanie, passe du statut d’aidé à celui d’aidant. Le 1er janvier 2007, celle-ci intègre en effet l’Union Européenne ... [more ▼]

L’objectif du présent mémoire est de comprendre comment un pays, en l’occurrence la Roumanie, passe du statut d’aidé à celui d’aidant. Le 1er janvier 2007, celle-ci intègre en effet l’Union Européenne. Faisant partie de l’acquis communautaire, la coopération au développement commence dès lors officiellement pour la Roumanie en tant que nouveau membre. Le pays se voit ainsi confronté à un nouvel horizon : soutenir la réalisation des Objectifs du Millénaire pour le Développement (OMD) dans le « Sud ». Mais lorsque l’on sait qu’elle a eu, elle aussi, son propre rapport des OMD pour 2008, on prend conscience que ce chantier constitue un vrai défi. Devant cette situation nouvelle, nous avons mobilisé l’un des concepts clés du sociologue Erving Goffman – le faceworking – afin de rendre compte le plus finement possible du processus d’acquisition des rôles dorénavant dévolus aux différents acteurs nationaux impliqués dans l’aide roumaine. Nous démontrons que si les protagonistes tentent de réaliser leurs intérêts, ils ne peuvent le faire qu’en maintenant chacun une "face" vis-à-vis des autres. Les rencontres entre deux institutions sont dès lors encadrées par une dynamique propre à l’interaction. Une dynamique qui a peut-être été sous-estimée par la littérature sociologique et anthropologique en développement : si les rôles et le statut des institutions ont été abondamment analysés, la manière dont naît un nouveau rôle/statut est fréquemment traitée comme une « boîte noire ». Or, cette situation est exactement celle que vit aujourd’hui la Roumanie sur la scène internationale. Prenant à rebours ce changement macro social, l’hypothèse du mémoire est que les interactions à première vue les plus anodines peuvent être au fondement de changements de plus grande échelle. [less ▲]

Detailed reference viewed: 73 (34 ULg)
Full Text
See detailAgronomical and molecular factors influencing bananas (Musa acuminata, AAA, cv ‘Grande-Naine’) susceptibility to crown rot disease
Lassois, Ludivine ULg

Doctoral thesis (2009)

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An ... [more ▼]

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An original approach of the disease is proposed and consists on presenting the fruit quality potential at harvest as a key factor in crown rot development. This potential develops during growth of bananas in the field and depends on a physiological and a parasitical component. The physiological component refers here to the level of fruit susceptibility to crown rot and reflects the physiological state of the fruit. The aim of this study was to clarify the role of the fruit physiological component at harvest in the post-harvest crown rot development. It appears that the fruit physiological component at harvest greatly influence the postharvest disease development and thus the fruit susceptibility. Seasonal variations in disease severity were shown in two production area and are related to a variation of the fruit physiological component. In Guadeloupian conditions, the internal necrotic surface of the crown was nearly multiplied by 4 during 11 successive weeks. Two pre-harvest factors that could influence the fruit physiological component by modifying their susceptibility to crown rot, were identified: (i) hand position on the bunch and (ii) source-sink ratio of the banana plant (hand considered as sink and leaves as source). It was shown that within a bunch, there is a gradient of susceptibility to crown rot (r= -0.95), the hands initiated first (the upper ones) being more susceptible than those initiated last (the lower ones). These results also confirmed that source-sink ratio changes have a significant effect on fruit morphology and demonstrated that there is also an effect on fruit susceptibility to crown rot disease. When the sink is decreased by artificial removal of many hands, the level of fruit susceptibility to crown rot decreases. However, the molecular mechanisms underlying these quantitative host-pathogen relationships were still unknown. A study was designed to compare gene expression, by cDNA-AFLP, between crowns of bananas showing a high susceptibility (S+) and crowns of bananas showing a low susceptibility (S-) to Colletotrichum musae responsible for crown rot disease. This comparison was performed at two situation time: (i) between crowns (S+ and S-) collected one hour before infection and (ii) between crowns (S+ and S-) collected 13 days after infection. Genes implied in signaling pathway and proteolytic machinery were identified. It also appears that a cellulose synthase, a CAF1 gene, 2 glycolipid transfer protein and a dopamine-β-monooxygenase were differently expressed between bananas showing different levels of susceptibility. This is the first study of the characterization of the banana physiological component at harvest which influences the crown rot post-harvest disease development. In addition, to our knowledge, this work is the first to address both pre- and post-infection gene expression with the same host-pathogen combination and different susceptibility levels. [less ▲]

Detailed reference viewed: 121 (17 ULg)
Full Text
See detailWhat Is the Impact of Benevolent Sexism on Reactions Facing Unfairness?
Silvestre, Aude ULg

Master's dissertation (2009)

Social interactions between men and women are subject to lots of influences, be it during an encounter, on the work place, in an intimate relationship, etc. Moreover, whereas they are in a similar ... [more ▼]

Social interactions between men and women are subject to lots of influences, be it during an encounter, on the work place, in an intimate relationship, etc. Moreover, whereas they are in a similar situation, men and women react quite differently. Benevolent sexism is one of the factors that affect men-women relationships. In this dissertation, an experiment was built in order to study the impacts of benevolent sexism on relationships between men and women in a particular frame: the Ultimatum Game. The authors try to know the impacts of benevolent sexism on women’s behaviour during an Ultimatum Game, and that according to the context female participants are in. Female participants played the role of receivers who had to accept or reject offers proposed by photographs of men on the computer screen. The results of the experiment revealed that the kind of offer (fair, unfair, very unfair), the context (romantic or occupational) and the level of benevolent sexism as well as attractiveness of the photographed male’s faces will influence female participants’ behaviour and their decision-making process in an Ultimatum Game. The results will then be discussed and suggestions for future research will be put forward. [less ▲]

Detailed reference viewed: 80 (9 ULg)
See detailEtude du rôle des macrophages interstitiels dans l'allergie des voies respiratoires
Bedoret, Denis ULg

Doctoral thesis (2009)

Respiratory mucosal surfaces are constantly exposed to a broad range of non-pathogenic environmental antigens. In the absence of proinflammatory signals, inhalation of harmless antigens results in ... [more ▼]

Respiratory mucosal surfaces are constantly exposed to a broad range of non-pathogenic environmental antigens. In the absence of proinflammatory signals, inhalation of harmless antigens results in immunological tolerance. Indeed, lung dendritic cells stimulate the development of antigen-specific regulatory T cells. Nevertheless, epidemiological studies have shown that ambient air contains not only inert antigens but also immunostimulatory molecules of microbial origin. Of particular interest are endotoxins, a cell wall component of gram-negative bacteria that is ubiquitous in the environment. In spite of the fact that high levels of endotoxin exposure in early life protect against allergic sensitization, most evidence indicates that exposure to house-dust endotoxin is a significant risk factor for increased asthma prevalence and severity. When the respiratory tract is stimulated with airborne endotoxins, lung dendritic cells lose their tolerogenic properties and rather promote the development of an allergic response directed against concomitant aeroantigens. Although endotoxins are omnipresent in the environment and favour airway allergy, only a minority of people develops asthma. A unifying model reconciling these conflicting observations is still lacking. We report here that LPS-triggered airway allergy is tightly controlled by lung interstitial macrophages, a cell population that remains largely uncharacterized. Interstitial macrophages could be distinguished from alveolar macrophages by their unique capacity to inhibit lung dendritic cell maturation and migration upon LPS stimulation, thereby preventing sensitization to concomitant inhaled antigens. We furthermore demonstrated that functional paralysis of LPS-stimulated dendritic cells involves interleukin-10 production by interstitial macrophages. Finally, we demonstrate that specific in vivo elimination of interstitial macrophages leads to overt asthmatic reactions to innocuous airborne antigens inhaled along with low LPS doses. Our study thus reveals a crucial role for interstitial macrophages in maintaining immune homeostasis in the respiratory tract and provides an explanation for the paradox that airborne LPS has the ability to promote the induction of Th2 responses by lung dendritic cells but does not provoke airway allergy under normal conditions. In the presence of LPS, interstitial macrophages, but not alveolar macrophages, break the link between innate and adaptive immunity, allowing harmless inhaled antigens to escape from T cell-dependent responses. [less ▲]

Detailed reference viewed: 81 (20 ULg)
See detailLes importations parallèles après les affaires Glaxo
Aliaj, Arjeta ULg

Master of advanced studies dissertation (2009)

Detailed reference viewed: 50 (16 ULg)
Full Text
See detailMapping Athletic Performance Related Genes in the Equine Genome and a Genome Scan for Superior Athletic Performance in the Thoroughbred
Durkin, Keith ULg

Doctoral thesis (2009)

The primary goal of the Thoroughbred industry is to breed and train superior equine athletes capable of excelling on the racetrack. To date, research into the genetic underpinnings of athletic ability has ... [more ▼]

The primary goal of the Thoroughbred industry is to breed and train superior equine athletes capable of excelling on the racetrack. To date, research into the genetic underpinnings of athletic ability has been limited in the horse. Advances in equine genomics and the genetics of athletic performance in humans have opened up the possibility of investigating this important trait in the Thoroughbred. Initially, 46 candidate genes associated with human athletic performance were mapped in the equine genome by radiation hybrid (RH) and fluorescent in situ hybridization (FISH) mapping. RH data and later the draft equine genomic sequence allowed us to identify microsatellites adjacent to these and other candidate genes (95 in total). Additional microsatellites were added to increase genome coverage, producing a final panel of 186 markers. All the potential markers were initially screened on a pool of DNA for 16 Thoroughbreds to ensure they were polymorphic. The panel was genotyped on 162 Thoroughbreds in total; Centimorgans (cM) between microsatellites were determined with CRI-MAP. The animal’s athletic ability was estimated using career winnings loge transformed to create a linear trait; unraced animals were treated as missing data. Linkage analysis was carried out using the MERLIN program, and association analysis was carried out using the QTDT program. Appropriate thresholds for statistical significance were determined by carrying out 1000 simulated genome scans based on the structure of the original data. LOD scores above 1.54 met the criteria of statistical significance (with a 5% chance of type I error). In the actual genome scan, the marker L12.2 had the highest observed LOD score of 1.16 and p-value of 0.01 and consequently was not significant; the association analysis also did not detect significant association with performance on the track. Given the complexity of the phenotype under investigation and the modest sample size, the lack of linkage/association was not unexpected. Nevertheless, this study has contributed to the RH and FISH maps of the equine genome. Additionally, the development of the genome scanning panel for this study has provided useful information on the most informative microsatellites for linkage or association studies in the Thoroughbred. [less ▲]

Detailed reference viewed: 71 (5 ULg)
See detailLES TRAITEMENTS ET LA PHARMACOGENETIQUE DES TRAITEMENTS ANTI-VIH-1
Cherrier, Thomas ULg

Doctoral thesis (2009)

Detailed reference viewed: 27 (8 ULg)
Full Text
See detailContribution to the Characterization of Scroll Machines in Compressor and Expander Modes
Lemort, Vincent ULg

Doctoral thesis (2008)

This thesis contributes to the knowledge and the characterization of scroll machines and their systems. It is based on experimental and modeling works carried out on: a) A hermetic scroll compressor used ... [more ▼]

This thesis contributes to the knowledge and the characterization of scroll machines and their systems. It is based on experimental and modeling works carried out on: a) A hermetic scroll compressor used inside an air-cooled water chiller. b) An oil-free open-drive scroll expander integrated into an Organic Rankine Cycle (ORC) power system. c) Open-drive scroll compressor and expander used in a Liquid Flooded Ericsson Cycle Cooler (LFEC). Such a system uses the liquid flooding of the compressor and of the expander to approach isothermal compression and expansion processes. New semi-empirical models of the scroll compressor and expander were proposed and existing models improved. A deterministic model of the scroll expander was established. The model associates a geometrical description of the machine with a thermodynamic description of the expansion process. This model was validated for the two expanders investigated experimentally. The model validation revealed that the performance of the expanders is mainly affected by the supply pressure drop and by the internal leakages. Using the validated model, parametric studies were carried out to investigate the variation of the performance of both expanders with modification of their design and with the operating parameters. The thesis also investigated the scroll machines from the point of view of their integration into thermal systems. A first experimental investigation was carried out on an air-cooled chiller. The scroll compressor semi-empirical model, with its parameters identified on the basis of published manufacturer data, was used as a refrigerant flow meter. The analysis of the experimental data allowed a better understanding of the chiller operation and a better identification of its model parameters (such as the fan and the hot gas bypass control models). A second experimental investigation was carried out on an ORC power system, working with R123. In order to select the most appropriate fluid, the performances achieved with four different fluids were compared by simulation. The experimental study confirmed that the scroll expander is a good candidate for an ORC system: the tested prototype presented a good performance (the maximum global isentropic effectiveness achieved was 68%). Using an ORC simulation model, parametric studies were carried out to investigate the effects of the expander characteristics and operating conditions on the cycle performance. The latter is mainly affected by the expander internal leakage and by the liquid subcooling at the condenser exhaust. A third experimental investigation was performed on a LFEC working with nitrogen as refrigerant and alkyl-benzene oil as flooding liquid. Experimental data was used to identify the parameters of the scroll compressor and expander semi-empirical models. Parametric studies were performed to identify the different factors affecting their performance. One of the undesirable features of the machines is the increase of the supply and exhaust pressure drops with the increase of oil quantity. [less ▲]

Detailed reference viewed: 236 (14 ULg)
See detailÉtude du vocabulaire de la vie familiale et sociale en Wallonie: approche géolinguistique et lexicologique
Baiwir, Esther ULg

Doctoral thesis (2008)

La thèse est concue comme un volume de l'Atlas Linguistique de la Wallonie (ALW), la plus grande et la plus ambitieuse œuvre de dialectologie en Wallonie. L'objet de la thèse est l'homme en tant qu'être ... [more ▼]

La thèse est concue comme un volume de l'Atlas Linguistique de la Wallonie (ALW), la plus grande et la plus ambitieuse œuvre de dialectologie en Wallonie. L'objet de la thèse est l'homme en tant qu'être social. C'est ainsi le vocabulaire de la famille et des interactions sociales qui est étudié. L'intérêt du sujet ne se limite donc pas uniquement au domaine linguistique, mais il a d'évidentes interactions avec l'ethnographie, l'histoire ou la sociologie. [less ▲]

Detailed reference viewed: 76 (3 ULg)
See detailBelgien im Nachkriegsdeutschland. Besatzung, Annäherung, Ausgleich (1944-1958)
Brüll, Christoph ULg

Doctoral thesis (2008)

Les relations belgo-allemandes ne constituent pas un champ de recherches souvent fréquenté par des chercheurs de part et d’autre de la frontière – à l’exception des deux occupations allemandes de la ... [more ▼]

Les relations belgo-allemandes ne constituent pas un champ de recherches souvent fréquenté par des chercheurs de part et d’autre de la frontière – à l’exception des deux occupations allemandes de la Belgique. Cette observation était encore plus nette pour la période après 1945. La thèse s’efforce de combiner une approche relativement classique de l’histoire diplomatique avec l’histoire sociale et celle des représentations et mentalités. En effet, l’analyse des plans belges pour l’après-guerre, des demandes de réparations territoriales et économiques et de l’occupation d’une partie de la zone d’occupation britannique par des troupes belges ne se fait pas seulement au niveau des ministères Affaires étrangères, mais également au niveau des principaux concernés : les soldats belges en Allemagne et la population frontalière. La présentation à différents niveaux de récit permet l’analyse des interactions entre la « grande politique » alliée et le quotidien des « concernés ». Les chapitres sur les années 1950 détaillent le rapprochement politique de la Belgique avec la jeune République Fédérale d’Allemagne devant un décor de guerre froide – rappelant la nécessité d’intégrer les Allemands dans le bloc de l’ « Ouest » – et des débuts de l’intégration européenne – discours dominant dans les justifications du rapprochement avec l’ancien ennemi. Dans ces pa-ges, c’est la représentation de l’ « autre » qui guide l’analyse. Le terminus ad quem était constitué par la ratification du traité bilatéral du 24 septembre 1956 par les deux parlements en 1958. Le travail évoque ici la question du prix de la rapide (comparée aux Pays-Bas ou à la France) réconciliation politique, notamment sur le plan de la société civile. Les relations belgo-allemandes après 1945 apparaissent ici surtout comme un processus d’apprentissage ayant pour objectif la volonté de ne plus commettre les mêmes erreurs que pen-dant l’entre-deux-guerres. [less ▲]

Detailed reference viewed: 76 (7 ULg)
Full Text
See detailThérapie du mésothéliome pleural malin par l’utilisation du valproate, un inhibiteur de désacétylases
Vandermeers, Fabian ULg

Doctoral thesis (2008)

Le mésothéliome pleural est un cancer de la plèvre provoqué principalement par l’inhalation de fibres d’amiante. Nous avons émis l’hypothèse que la dérégulation de l’expression génique est un paramètre ... [more ▼]

Le mésothéliome pleural est un cancer de la plèvre provoqué principalement par l’inhalation de fibres d’amiante. Nous avons émis l’hypothèse que la dérégulation de l’expression génique est un paramètre important du développement de cette maladie. Or, les histones désacétylases (HDACs) peuvent jouer le rôle de répresseur transcriptionnel en modifiant la conformation de la chromatine. Dans ce contexte, nous avons étudié l’activité anticancéreuse du valproate, un inhibiteur d’HDAC, en combinaison avec différents types de traitements utilisés en chimiothérapie. Nous avons démontré l’effet synergique entre la chimiothérapie et le valproate dans des lignées cellulaires et dans des biopsies isolées à partir de patients. Nous avons étudié les processus impliqués dans l’apoptose et révélé l’implication des caspases, des espèces oxygéno-réactives et le rôle important de la protéine Bid. Nous avons ensuite réalisé une étude transcriptomique par microdamiers dans le but de mieux caractériser les mécanismes impliqués. Enfin, nous avons démontré l’efficacité du valproate dans un modèle préclinique murin. Ces recherches ont permis la mise en place d’un essai clinique de deuxième ligne sur des patients réfractaires à une première chimiothérapie. [less ▲]

Detailed reference viewed: 22 (3 ULg)
Full Text
See detailStructure des communautés de plantes herbacées sur les Grands Causses : Stratégies fonctionnelles des espèces et interactions interspécifiques
Fayolle, Adeline ULg

Doctoral thesis (2008)

Plant community response to grazing management was studied on the INRA La Fage experimental station, Larzac Causse. Land use practices were considered as a disturbance and resource filter that remove ... [more ▼]

Plant community response to grazing management was studied on the INRA La Fage experimental station, Larzac Causse. Land use practices were considered as a disturbance and resource filter that remove species. The integrated approach of community structure used in this study was centred on plant functional traits. Continuous variations of plant traits associated with resource acquisition and early phenology indicated the replacement of stress tolerant species by ruderals along the gradient of land use intensity (grazing avoidance). Graminoids were particularly abundant in these communities. Changes in species identity and species functional identity were consistent with the grazing tolerance strategy. At the community scale, the strong functional convergence among dominant species confirmed the filtering effect of grazing management on these traits. Species richness reached its maximum at intermediate grazing. Maximal richness was associated with the coexistence of many growth forms and an important functional richness. These results are interpreted as an extension of the intermediate disturbance hypothesis to the traits of coexisting species. Finally, plant interaction dynamics experienced by five target species allowed us to identify the tendency of facilitated survival and intensely depressed biomass. The effect of communities was roughly similar although huge differences in specific and functional structure. The response to the least from competition and benefited the most from facilitation. [less ▲]

Detailed reference viewed: 349 (30 ULg)
Full Text
See detailBehavior of Deep Reinforced Concrete Beams under Monotonic and Reversed Cyclic Load
Mihaylov, Boyan ULg

Doctoral thesis (2008)

Non-slender reinforced concrete beams find extensive application in cases where heavy loads need to be transferred over a given span. The safety of this kind of structural elements is often critical for ... [more ▼]

Non-slender reinforced concrete beams find extensive application in cases where heavy loads need to be transferred over a given span. The safety of this kind of structural elements is often critical for the safety of the structure as a whole. The research described in this thesis is devoted to studying the behaviour of lightly-reinforced non-slender beams under monotonic and reversed cyclic loads, as particular consideration is given to the load-bearing mechanisms which occur in moderately-deep beams. The choice of this topic was motivated in part by verification studies which show that the current code procedures for shear design of members without web reinforcement are least accurate in the range of transition from deep to slender beams. Furthermore, the issue of cyclic response of lightly-reinforced deep beams is of great importance for seismic assessment of existing structures, especially if the similarity between the load-bearing mechanisms in deep beams and those in other non-slender components such as coupling beams, squat shear walls, and frame joints is recognized. An experimental program consisting of ten tests of large non-slender reinforced concrete beams has been performed. All specimens failed in shear after transition from beam load-bearing mechanism to arch action (specimens without stirrups) or truss actions (specimens with stirrups). A suggested kinematic model was successfully used for interpretation of the various deformation measurements. The results showed that part of the ultimate shear was carried in the cracked concrete. It was concluded that load reversals had little effect on the overall response. A test of deep beam provided with single bar #18 demonstrated that anchorage by anchor heads is effective even when the biggest ASTM reinforcing bar is used. Comparison between experimentally-obtained and calculated shear strengths showed that the CSA code rendered reasonably conservative predictions compared to the mostly unconservative results of the ACI and EC2 codes. Theoretical work resulted in a derivation of an improved strut-and-tie model (ISTM) which is based on the CSA shear provisions but accounts for shear carried under the critical diagonal cracks of non-slender beams without web reinforcement. Verification against a large number of tests showed that the new model is consistent with physical observations and explains the transition from deep to slender beams. Furthermore, it was shown that the ISTM can be used in combination with the above-mentioned kinematic model for estimation of the ultimate displacement and deformed shape of non-slender beams. [less ▲]

Detailed reference viewed: 512 (29 ULg)
Full Text
See detailProduction of alarm pheromone in aphids and perception by ants and natural enemies
Verheggen, François ULg

Doctoral thesis (2008)

Most Aphidinae species produce and use (E)-ß-farnesene (Eßf) as an alarm pheromone. This sesquiterpene is released by individuals under attack by a predator, and nearby aphids exhibit a variety of alarm ... [more ▼]

Most Aphidinae species produce and use (E)-ß-farnesene (Eßf) as an alarm pheromone. This sesquiterpene is released by individuals under attack by a predator, and nearby aphids exhibit a variety of alarm behaviours. This PhD thesis aims to better understand how aphids manage their production and emission of alarm pheromone (Chapter IV). We also wanted, in a second step, to improve our knowledge on the roles that Eßf could play in the relationships that aphids have with their predators (Chapter V) and tending ants (Chapter VI), in order to better pinpoint the problem in this very tough context. The aphid predators have indeed a real advantage to be able to use the odorant cues emitted by their prey, to locate them and to select an adequate oviposition site. Ants establish with certain aphid species mutualistic relationships, which occurrence could be facilitated by the use of aphids’ odours. In Chapter IV, we have highlighted that aphid colonies non subjected to attack by predators release constantly small quantities of Eßf in their headspace, which means that this molecule could have additional roles than just acting as an alarm pheromone. In a second study, we demonstrated that the release of Eßf was not contagious, and therefore that a non stressed aphid receiving the alarm signal does not release additional Eßf. Since the production of alarm pheromone is likely to entail physiological cost, we tested and validated the hypothesis that aphids regulate their Eßf production according to their social environment. In Chapter V, we studied the ability of the hoverfly predator Episyrphus balteatus (Diptera, Syrphidae) to be used as biological control agent against aphids infesting tomato plants (Lycopersicon esculentum). After identifying the odours emitted by aphid infested plants, we have demonstrated that although this Diptera is able to perceive all the odours released by the system, it mainly uses Eßf to select its oviposition site. However, the E. balteatus larvae are not adapted to the architecture of tomato plants. We also showed that the Asian ladybeetle Harmonia axyridis (Coleoptera, Coccinellidae) olfaction was adapted to the perception of Eßf and that this beetle is also attracted by this sesquiterpene. Finally, in Chapter VI, we characterized the benefits accruing to aphid populations that have established mutualistic relationships with Lasius niger (Hymenoptera, Formicidae), and have demonstrated the role of Eßf and honeydew, respectively in locating aphid colonies and in the persistence of the mutualism. [less ▲]

Detailed reference viewed: 252 (17 ULg)
Full Text
See detailNovel Strategies towards aminophosphonic derivatives by [4+2] cycloadditions
Monbaliu, Jean-Christophe ULg

Doctoral thesis (2008)

Aminophosphonic and related compounds were almost unknown 50 years ago, but today the literature data have considerably increased. Their negligible mammalian toxicity and their similarity with aminoacids ... [more ▼]

Aminophosphonic and related compounds were almost unknown 50 years ago, but today the literature data have considerably increased. Their negligible mammalian toxicity and their similarity with aminoacids confer on these compounds a top place as potential candidates for drugs. The discovery of numerous natural aminophosphonic derivatives endowed with biological properties useful to both medicinal and agricultural fields enhanced the infatuation for synthetic analogs and homologs. Intensive work has been performed towards alpha-aminophosphonic compounds, the direct analogs of natural alpha-aminoacids, disclosing versatile strategies, compatible both with molecular diversity and asymmetric synthesis. Less synthetic effort was devoted to the synthesis of higher homologs. Recent developments of the Diels-Alder reaction offer an asymmetric and convergent entry to various six-membered highly functionalizable key intermediates, compatible with molecular variety. As it is, the Diels-Alder (D-A) reaction should provide an original and versatile entry to beta-, gamma- and delta-aminophosphonic compounds, a challenging research area. As a direct consequence of the strategy, one of the two D-A partners (diene or dienophile) will act as vehicle for the phosphonate moiety. By contrast to its common use for the stabilization of alpha-negative charges, its implication in D-A reactions remains scarce. Indeed, the phosphonate moiety is not an efficient substituent susceptible to activate the D-A reaction; its use requires compensation by the activation of the other partner or by specific activation. Both synthetic organic and computational chemistry will furnish information to propose a fine understanding of the key D-A steps, in view to optimize the achievement of the corresponding cycloadducts. These cycloadducts will be considered as synth-/chirons for the synthesis of aminophosphonic compounds. [less ▲]

Detailed reference viewed: 16 (4 ULg)
See detailHagiographie et statistique linguistique : étude d’un corpus de traductions médiolatines d’origine grecque
Philippart de Foy, Caroline ULg

Doctoral thesis (2008)

The dissertation considers a corpus of 35 hagiographic texts translated from Greek into Latin in the Middle Ages. This corpus is representative of the different stages in the history of hagiographic ... [more ▼]

The dissertation considers a corpus of 35 hagiographic texts translated from Greek into Latin in the Middle Ages. This corpus is representative of the different stages in the history of hagiographic translations and of the various centres of translation in Italy. Those translations are to be presented in a new and original way by studying from a linguistic point of view the Latin language used by the translators to render their Greek models and the techniques that were implemented to achieve those translations, considering them not individually but in a global and comparative way. Quantitative linguistics was chosen as a method in order to go through a large corpus and to compare numerous texts, to enlighten their characteristics and their common or opposite features on a lexical as well as a syntactical basis. [less ▲]

Detailed reference viewed: 28 (3 ULg)
Full Text
See detailImplantation d'acide hyaluronique estérifié lors de la microchirurgie des lésions cordales bénignes
FINCK, Camille ULg

Doctoral thesis (2008)

La microchirurgie des pathologies cordales bénignes est pratiquée afin d’améliorer les caractéristiques mécaniques du vibrateur laryngé. C’est en augmentant la souplesse tissulaire et la fermeture ... [more ▼]

La microchirurgie des pathologies cordales bénignes est pratiquée afin d’améliorer les caractéristiques mécaniques du vibrateur laryngé. C’est en augmentant la souplesse tissulaire et la fermeture glottique en phonation que le micro-chirurgien espère améliorer les caractéristiques du son laryngé émis. Les techniques microchirurgicales ont évolué de manière spectaculaire au cours des 20 dernières années grâce à la connaissance de plus en plus approfondie de la structure cordale normale et surtout de son tissu conjonctif : la lamina propria. C’est la partie la plus superficielle de la lamina propria, l’espace de Reinke, qui joue le rôle le plus important dans la production du son. C’est aussi l’espace de Reinke qui est occupé, détruit ou remanié en cas de pathologie cordale bénigne. La microchirurgie vise à le libérer du processus pathologique. L’originalité des techniques microchirurgicales exposées dans ce travail est de tenter, non seulement de libérer l’espace vibrant de la lésion cordale, mais aussi de modifier les processus cicatriciels post-opératoires par l’utilisation d’un implant résorbable d’acide hyaluronique estérifié. Les objectifs de ce travail sont : - de contribuer à la connaissance des résultats fonctionnels laryngés et vocaux observés après une microchirurgie cordale - d’évaluer l’impact fonctionnel, sur ces résultats, de l’utilisation d’un implant résorbable d’acide hyaluronique estérifié, en fin d’intervention chirurgicale. [less ▲]

Detailed reference viewed: 119 (12 ULg)
See detailMechanical properties, residual stresses and structural behavior of thin-walled stainless steel profiles
Rossi, Barbara ULg

Doctoral thesis (2008)

Although it offers a wide variety of interesting properties such as fire resistance or durability, stainless steel has been used in limited amount in structures. It is a known fact that the design rules ... [more ▼]

Although it offers a wide variety of interesting properties such as fire resistance or durability, stainless steel has been used in limited amount in structures. It is a known fact that the design rules don't properly account for the additional benefits of stainless steel properties and are largely based on the specifications for carbon steel. Indeed, a number of similarities exist between stainless steel and ordinary carbon steel but there is sufficient differences to afford a specific treatment in design standards. And since stainless steel is an expensive material, it is important to accurately predict the resistance of structural members. The present research work is dedicated to the study of cold-formed stainless steel profiles. It actually follows the life of a stainless steel construction element and falls on three fundamental topics: the material behavior, the through-thickness residual stress distribution and mechanical enhancement due to the cold-forming process and, last, the strength of concentrically compressed thin-walled columns. Firstly, several constitutive models are characterized such as Teodosiu-Hu's micro-structural based hardening model, capable of predicting the behavior of the studied stainless steel grade submitted to biaxial loading causing plastic strain. This model accounts for the nonlinear hardening behavior, the anisotropy, the Bauschinger effect and more complex behavior such as the observed work-hardening stagnation under reversed deformation at large strains. For this purpose, a collection of tests is carried out including multiaxial tests such as tensile-shear tests and successive simple shear tests and plane-strain tests. Secondly, the effects of the forming process on the mechanical properties are studied. To begin with, on the basis of the constitutive models developed previously, an analytical method that calculates the biaxial residual stress distribution in the walls and in the corners of cold-formed profiles is established. Based on the conclusions drawn from this theoretical analysis, a new formula for the evaluation of the actual mechanical properties is established. This formula is not restricted to a single alloy or type of cross-section. Current design standards are then used to calculate the strength of lipped-channel section columns failing by combined distortional and overall flexural-torsional buckling and the results are compared to tests. Indeed, full-scale tests on cold-formed stainless steel lipped channel section columns were achieved in the Structures Laboratory of the University of Liège. And, once verified against the test results, finite element models were used to generate additional results when necessary. The author then presents a new Direct Strength Method taking into account this phenomenon. Finally, a wide amount of reference results are gathered from the literature, without limiting oneself to any kind of cross-section or stainless steel grade. This database is used to propose an improved formulation for the design of stainless steel thin-walled section columns failing by distortion, local or combination of local and overall buckling in the low slenderness range. [less ▲]

Detailed reference viewed: 376 (27 ULg)
Full Text
See detailSystematic Cooperation in P2P Grids
Briquet, Cyril ULg

Doctoral thesis (2008)

P2P Grid computing seeks the convergence of Grid and P2P technologies. Deploying a P2P Grid middleware on a set of computers enables an organization to automatically barter computing time with other ... [more ▼]

P2P Grid computing seeks the convergence of Grid and P2P technologies. Deploying a P2P Grid middleware on a set of computers enables an organization to automatically barter computing time with other Internet-connected organizations. Such P2P exchanges of computing time enable individual Peers, i.e. organizations, to transparently aggregate large amounts of computational power with minimal infrastructure requirements or administrative cost. Challenges arise from the requirement for scalability and robustness. Individual worker nodes are unreliable, as P2P Grids operate on unmanaged desktop computers. A specificity of P2P Grids is that each Peer can reclaim at any time the computational power of worker nodes supplied to other Peers, leading to bursts of execution preemption. These are the major contributions of our dissertation: * Firstly, we propose a new P2P Grid architecture, the Lightweight Bartering Grid (LBG). Through systematic cooperation between Grid nodes, the reliability of execution of computational requests is greater than the sum of the reliabilities of worker nodes. * Secondly, we propose a highly scalable data transfer architecture. It is based both on the BitTorrent P2P file sharing protocol and on the removal of the temporal cost of downloading redundant copies of input data files. * Thirdly, besides a middleware implementation of LBG, we also provide an implementation of a discrete-event simulator. Its originality resides in the weaving of the simulator code into the bartering code of the middleware, which is made possible through the virtualization of Grid nodes. This enables reproducible testing and accurate performance evaluation of the bartering policies because the Peers of a simulated Grid make the same bartering decisions as Peers deployed on real computers. The LBG architecture exhibits the following remarkable features: * The scheduling model supports the queueing of external requests and the architecture enables a flexible study of bartering policies. * The architecture is open, flexible, lightweight and facilitates software engineering. It enables the easy development, testing, evaluation and deployment of combinations of scheduling policies. * The architecture is fully P2P. [less ▲]

Detailed reference viewed: 111 (10 ULg)
Full Text
See detailEtudes génétiques et immunomodulatoires de la ghréline sur les traits de production et de conformation en races bovines ainsi que sur la croissance chez le rat
Colinet, Frédéric ULg

Doctoral thesis (2008)

En production animale, notamment dans les filières bovines, il est d’un intérêt économique d’augmenter la quantité d’hormone de croissance dans la circulation sanguine. La ghréline est un peptide ... [more ▼]

En production animale, notamment dans les filières bovines, il est d’un intérêt économique d’augmenter la quantité d’hormone de croissance dans la circulation sanguine. La ghréline est un peptide principalement produit au niveau de la paroi stomacale. Ce ligand endogène au GHSR stimule la sécrétion hypophysaire de l’hormone de croissance. Peptide orexigène, la ghréline est impliquée dans les mécanismes relatifs au maintien de l’homéostasie énergétique. Dans l’optique d’améliorer les performances animales, deux approches de la ghréline ont été effectuées. La première approche consiste en l’étude des gènes bovins codant pour la ghréline (bGHRL) et son récepteur (bGHSR). Ces deux gènes ont été respectivement localisés sur BTA 22 et BTA 1. Quatorze polymorphismes ont été détectés sur ces deux gènes et trois d’entre eux affectent la structure primaire du GHSR bovin. Des associations, à différents niveaux de signification, entre certains de ces 14 sites polymorphiques et des traits de production et de conformation ont été mis en évidence au sein d’un groupe de 127 taureaux Holstein sur base de leurs descendances directes présentes en Région Wallonne. La seconde approche aborde les effets d’une immunisation passive contre la ghréline sur des rats mâles en croissance en comparaison à celles contre la leptine et la cholécystokinine. Lors d’une alimentation équilibrée, le traitement envers la ghréline sur ces rats n’a pas influencé la croissance et l’ingestion par rapport aux animaux témoins. Des effets ont été observés entre les différentes immunomodulations au niveau des paramètres de croissance, d’ingestion et endocrinologiques. Les présents résultats invitent à de nouvelles investigations des gènes bGHRL et bGHSR sur des données relatives à d’autres populations/races bovines et de l’immunomodulation de la ghréline lors de conditions d’expérimentation différentes (alimentation déséquilibrée, stade physiologique, espèce, etc.). Ces investigations pourraient être valorisées en sélection et production animale mais également en médecine tant humaine que vétérinaire. [less ▲]

Detailed reference viewed: 58 (13 ULg)
Full Text
See detailDesign, synthesis and biological evaluation of cognitive enhancers acting through the potentiation of the AMPA receptors
Francotte, Pierre ULg

Doctoral thesis (2008)

Alzheimer’s disease (AD) represents one of the greatest health problems in industrialized countries considering the ageing population. Only four drugs are currently approved for the treatment of this ... [more ▼]

Alzheimer’s disease (AD) represents one of the greatest health problems in industrialized countries considering the ageing population. Only four drugs are currently approved for the treatment of this disease. As these drugs are characterized with a limited time efficacy, it has become urgent to develop additional innovative AD treatments. Amongst the approaches that are actively investigated, the one consisting in potentiating a subclass of glutamate receptors appears attractive. This well advanced pharmacological approach includes three major classes of compounds amongst which appear the benzothiadiazine 1,1-dioxides. The present thesis is a pursuit of the preliminary efforts that were published in 1998 and 2001 by our team. Based on promising in vitro results obtained with the lead compound 59, pharmacomodulations around 59’s structure have been achieved in order to enhance its in vivo activity and to optimize its pharmacokinetic parameters. First efforts were devoted to exploratory synthesis where attention was paid to the impact of the substituent introduced at the 7-position. Moreover, some pyridothiadiazine dioxides as well as thienothiadiazine dioxides were prepared. The most important part of our pharmacomodulations was focused on the thiadiazine ring system. Considering that the poor in vivo results obtained with 59 could be due to a metabolic weakness of the latter, the introduction of fluorine atoms was tempted as a lead optimization strategy. This approach was successful, since it led to the synthesis of 95b which was selected for further pharmacological evaluations. This new lead compound was shown to exert significant cognitive-enhancing effects in vivo after oral administration to Wistar rats. Moreover, the study of the metabolic degradation of 95b allowed the assessment of the starting hypothesis that had dictated the pharmacomodulation’s philosophy. Finally, additional exploratory pharmacomodulations were achieved notably leading to the preparation of a quinazolinone series and 1,4-benzothiazine compounds. This research allowed to significantly improve the pharmacokinetic profile of our series and led to the identification of 95b as a new lead compound. However, many pharmacomodulations remain to be explored. The data collected during this thesis are appealing further studies. Efforts in the near future should lead to the design of novel drug candidates among which a future innovative AD treatment could emerge. [less ▲]

Detailed reference viewed: 13 (2 ULg)
See detailDesign of new stealthy and pH-sensitive polymer micelles for potential solid tumor targeting
Van Butsele, Kathy

Doctoral thesis (2008)

Detailed reference viewed: 82 (30 ULg)
See detailModulation de la voie de la lipoxygénase dans le cadre de la résistance systémique induite chez la tomate
Mariutto, Martin ULg

Master of advanced studies dissertation (2008)

Detailed reference viewed: 14 (2 ULg)
See detailLa naissance et la vie de la Révolution.
Bayramzadeh, Kamal ULg

Master's dissertation (2008)

Detailed reference viewed: 24 (5 ULg)
See detailMeasuring Time Delays in Gravitational Lenses
Eulaers, Eva ULg

Master of advanced studies dissertation (2008)

Detailed reference viewed: 11 (0 ULg)
Full Text
See detailEtude des facteurs écologiques et écotoxicologiques impliqués dans la réussite d’incubation chez la tortue luth, Dermochelys coriacea, de Guyane Française
Guirlet, Elodie ULg

Doctoral thesis (2008)

Leatherback turtles, Dermochelys coriacea, have relatively low hatching success in comparison to other marine turtle species. This low hatching rate is largely a result of high embryonic mortality rather ... [more ▼]

Leatherback turtles, Dermochelys coriacea, have relatively low hatching success in comparison to other marine turtle species. This low hatching rate is largely a result of high embryonic mortality rather than infertility, but the specific causes remain unknown. Leatherbacks are vulnerable to excessive adult mortality (resulting in population decline) because they are long-lived species. However, low hatching success and corresponding low juvenile recruitment could also result in long term declines of leatherbacks. On the Yalimapo beach, in French Guiana, hatching success is lower for this species than on other nesting sites, emphasising the problem of recruitment for the population. Understanding the causes of low hatching success is therefore an important conservation step towards preventing extinction in this population. During my thesis, I investigated the role of ecological (predation and nest site location) and ecotoxicological factors (blood and egg contamination by trace elements and organochlorine compounds) on the hatching success of leatherback nests. Firstly, nest location was shown to have an important effect on predation and inundation rate that decreased hatching success. Secondly, a maternal transfer of contaminants from females to their eggs was confirmed, raising the issue of the deleterious effects of environmental contaminants on embryos development, a developmental stage very sensitive to contaminants. Dose-effect relationships between contaminants and hatching success need to be assessed to establish the risk of environmental pollution for leatherback reproduction. Moreover, the use of stable isotope analysis for females differing in the number of years between two reproductive seasons revealed that they used different feeding areas. These feeding grounds differed in their geographical location, but also in the quality of the available prey in terms of their level of contamination by environmental pollutants, highlighting the issue of adult contamination. This thesis confirmed the importance of ecological factors for hatching rate and highlighted the existence of ecotoxicological factors, which have not yet been studied for the leatherback turtle. [less ▲]

Detailed reference viewed: 32 (5 ULg)