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See detailL'agame-papillon géant, Leiolepis guttata (Cuvier, 1829), dans la province de Binh Thuan, Vietnam : biologie, écologie, alimentation, enjeux économiques et gestion d'élevage
Tran, Tinh ULg

Doctoral thesis (2015)

Nous avons d'abord considéré la viande et les oeufs de lézard pour la consommation humaine à travers le monde. Nous démontrons l'importance de cette ressource comme source de nourriture humaine de bonne ... [more ▼]

Nous avons d'abord considéré la viande et les oeufs de lézard pour la consommation humaine à travers le monde. Nous démontrons l'importance de cette ressource comme source de nourriture humaine de bonne qualité. Suite à l’apparition en 2004 des premiers élevages de Leiolepis gutatta, l’agame-papillon géant, dans la province côtière de Binh Thuan, aux succès qui s’ensuivirent et à leur importance pour les petits paysans de cette région semi-désertique où les productions agricoles sont extrêmement limitées à cause du climat et du sol, cette espèce a été choisie pour nos recherches. Notre étude vise à disposer de meilleures connaissances de Leiolepis guttata concernant sa biologie, son écologie, son alimentation et ses enjeux économiques, le tout débouchant sur une meilleure gestion de l’élevage. Nous envisageons en premier lieu sa distribution, son milieu de vie naturel, les types de formations végétales et les écosystèmes où il s’observe. Le climatope, l’édaphotope et les phytocénoses concernées ont été étudiés et définis. Un herbier de référence (MRT) a été constitué et un CD réalisé. L’alimentation constitue le thème suivant. Il s’appuie sur des observations préliminaires concernant le tractus digestif de l’agame-papillon ; les fractions végétales, animales et minérales observées dans les estomacs sont étudiées ; des enquêtes auprès des éleveurs ont été menées afin de recueillir des informations sur les aliments (essentiellement les végétaux) consommés par ce lézard. Au cours de ce travail, nous avons montré que Leiolepis guttata était un lézard essentiellement herbivore à même de consommer et de digérer un très grand nombre de végétaux en fonction des opportunités et disponibilités alimentaires. Nous avons approché la diversité alimentaire tant en milieu naturel qu’en élevage (116 produits différents, dont 91 relèvent du règne végétal et 22 du règne animal). La composition chimique de 71 plantes et 4 insectes a été déterminée. Nos observations ont également mis en évidence la présence importante de vers parasites (Oxyuridae notamment). Le nombre d’élevages de Leiolepis guttata dans la province de Binh Thuan a considérablement augmenté entre 2007 et 2013 afin de satisfaire une demande forte de ces reptiles soit pour la consommation de viande très prisée dans cette région touristique, soit comme reproducteurs ; par contre après avoir atteint des valeurs très élevées, les prix de vente sont en diminution depuis ces toutes dernières années : l’offre dépassant la demande. Si l’élevage s’est développé, c’est de façon anarchique, sans connaissances techniques de la part des éleveurs, mais surtout par échange d’expériences entre eux. Les enclos d’élevage, leur aménagement et l’achat des reproducteurs constituent un point important pour la réussite de ce type d’élevage. Notre travail apporte donc des informations sur les principaux avantages et inconvénients des types d'enclos actuels. Ensuite, nous formulons des recommandations pour la construction et l'aménagement d'enclos d'élevage adaptés aux conditions locales en ce compris une étude des coûts et revenus. Parallèlement au développement des élevages, on constate également une très forte régression de l’espèce dans le milieu naturel de plus en plus dégradé suite au développement des infrastructures routières et touristiques de la région. En conclusion, si l’élevage en captivité de Leiolepis guttata peut contribuer au maintien de l’espèce dans cette région, la durabilité de la production pour les éleveurs nécessite qu’ils acquièrent de meilleurs connaissances techniques quant à la biologie, l’écologie, l’alimentation et la gestion de l’élevage sans nécessairement rechercher des solutions techniquement optimales souvent coûteuses et non rentables pour ce genre de production. A l’avenir, une attention particulière devrait être apportée aux besoins nutritionnels en fonction des stades physiologiques, aux aspects génétiques (consanguinité) et aux risques de maladies liées à ces élevages en forte densité. Enfin, une régulation entre l’offre et la demande doit impérativement être recherchée. [less ▲]

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See detailAb-initio study of thermoelectricity of layered tellurium compounds
Ibarra Hernández, Wilfredo ULg

Doctoral thesis (2015)

In this thesis, we explore the electronic, dynamic and thermoelectric properties of different tellurium-based compounds. We perform ab-initio calculations within the Vienna Ab-initio Simulation Package ... [more ▼]

In this thesis, we explore the electronic, dynamic and thermoelectric properties of different tellurium-based compounds. We perform ab-initio calculations within the Vienna Ab-initio Simulation Package (VASP) that works in the framework of Density Functional Theory (DFT). For the thermoelectric properties, we use the Boltztrap code that solves the Boltzmann Transport Equations (BTE) for electrons within the Constant Relaxation Time Approximation (CRTA). This computational package allows us to obtain accurate values of the Seebeck coefficient as a function of temperature and carrier concentration (this last with the help of the rigid band approximation). While for the calculation of the lattice contribution to the thermal conductivity, we use the ShengBTE code that solves the BTE for phonons iteratively. The first tellurium-based compound that we study is the best room temperature thermoelectric material, Bi2Te3. We obtain results comparable with experimental data for the Seebeck coefficient at room temperature and pressure. Afterwards, we proceed to explore the evolution of the electronic properties and the thermoelectric performance under pressures up to 5 GPa. We reproduce the overall trend of the Seebeck coefficient as a function of pressure for two different values of doping, however, our results do not reproduce the small improvement found in experiments close to 1 GPa. Nevertheless, we support the experimental evidence of an Electronic Topological Transition (ETT) around 2 GPa and we explain this particular behavior. We also perform calculations on the tellurium-based phase-change materials (GeTe)x(Sb2Te3)1 (with x = 1, 2, 3). We show results for different stacking configurations since for some compositions, the stacking arrangement of the atoms in the primitive cell is still unsettled. We find that the change of the atomic arrangement leads to the systems to go from semiconductors to metals. We find that the semiconductor arrangements systematically overestimate the experimental values for the Seebeck coefficient, whereas the metallic stacking sequences are in very good agreement with the experimental data for the Seebeck coefficient and for the lattice contribution to the thermal conductivity. We show that (GeTe)x(Sb2Te3)1 materials could reach values of ZT=0.5 around 600 K with a proper optimization of S with respect to the carrier concentration. We also report that in the case of x=3, the most accepted stacking configuration is dynamically unstable, therefore we proposed another sequence. Finally, we discuss the discrepancies between our work and recent theoretical reports that claim the existence of a Dirac-cone like band structure for (GeTe)2(Sb2Te3)1. We explain the conditions necessary to obtain such electronic topology. [less ▲]

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See detailLes carrières en fin d'activités: un potentiel paysager?
Joris, Alicia ULg

Master's dissertation (2015)

The present study focuses on the landscape concept and evaluations and is based on some issues related to the impact, restoration and ecological potential of the abandoned quarries. It proposes a ... [more ▼]

The present study focuses on the landscape concept and evaluations and is based on some issues related to the impact, restoration and ecological potential of the abandoned quarries. It proposes a landscape character assessment for non active limestone quarries resulting from the spontaneous succession. Taking into account the guidelines of the European Landscape Convention (Conseil de l'Europe, 2000) , this work has for objectives (1) to describe these landscape areas and (2) to assess the landscape aesthetic quality. To achieve these goals, two methods inspired by the Landscape Character Assessment (LCA) were tested. The first one is a field sheet and the second one a landscape perception survey with stakeholders. The results have emphasized the natural, harmonious and unique character of these landscapes. The key characteristics are the visual importance of cliffs, water bodies, vegetation forms and the landform in bleachers. Furthermore, color contrast and textures from vegetation, rock and water were also relevant. An apparent aesthetic landscape quality was perceived and the study showed that respondents are feeling good in the site surveyed. The quarryscape can be characterized of challenging, attractive, wild with an important degree of naturality but not really safe. Cultural, historic, symbolic and ecological values were also highlighted as a potential. These later observations take part in a landscape dynamic and allow to open the debate concerning the need for landscape interventions within these sites and the profit we could benefit from if security issues were well-managed. [less ▲]

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See detailImportance des résidus lysine 70 et tryptophane 154 sur la structure, la stabilité, la carbonatation et l'activité de la béta-lactamase OXA-10 de Pseudomonas aeruginosa
Baurin, Stéphane ULg

Doctoral thesis (2015)

SUMMARY : This thesis was conducted to highlight the biochemical and structures impact of conserved residues of the beta-lactamase OXA-10 isolated from P. aeruginosa. The beta-lactamase OXA-10 production ... [more ▼]

SUMMARY : This thesis was conducted to highlight the biochemical and structures impact of conserved residues of the beta-lactamase OXA-10 isolated from P. aeruginosa. The beta-lactamase OXA-10 production is one of the main responsible to the beta-lactam antibiotics resistance of Pseudomonas strains. This work is subdivided in five chapters. The first is focused on the organization of class D beta-lactamase in sub classes. We have created by identity analysis, 21 sub classes that reflect an easy discrimination between proteins variability and mutants. This methodology is able to organize the enzymes as function of a parental enzyme but also based on the substrate profiles. The second chapter regroups the studies that target the importance of the residue tryptophan 154 carried by the Omega loop. The substitution of the residue tryptophan 154 by an alanine, a glycine or an phenylalanine leads to a large decrease of i) the catalytic activity, ii) of the affinity toward to CO2 and iii) on the enzyme stability. The structural data show an absence of lysine 70 modification and a large modification of the hydrogen network throughout the mutants structures. The various complexes resolved by R-x diffraction of the W154A mutant indicate that the deacylation rate is the most impacted. The third chapter makes an analogy between the available structural informations of others proteins characterized by a carboxylation modification. Others serine enzymes known to be not modified were also integrated in the analysis. The data reveal that the presence of a tryptophan residue seems to be necessary. We notice the presence of a large hydrophobic area with various shape near of the modified lysines. The calculation of the theoretical pKa values of the lysines seems to indicate a large decrease of the values that lead to an unprotonated form at physiological pH. The fourth chapter describes, the role of the lysine 70. The substitution of the lysine by a cysteine or a glutamate leads to a large decrease of the catalytic activity and an absence of carboxylation. At the opposite, the protein stability is not impacted, and an increase of stability is observed for the K70C mutant. The structural data show that the overall fold and structures localization are conserved. The complex obtained with the nitrocefin proves that the mutant is always able to react with the beta-lactams compounds and show that the deacylation step is rate limiting. Finally, the last chapter regroups the effect of pH on the structure, the dimerization, the stability and the catalytic activity. The data show that in the tested conditions the OXA-10 beta-lactamase is in a dimeric form at physiological pH. The addition of CO2, leads the formation of a more compact enzyme form. At high pH (10), the monomer is observed, while a fast equilibrium between the monomer and the dimer is observed between the pH 7.5 and 10. The enzyme is characterized with similar stability as function of pH. The addition of CO2 leads an increase of the stabilities. In tested conditions, the OXA-10 beta-lactamase is characterized by two optimum pH in presence or not of CO2. The CO2 addition leads to a large increase of the catalytic constant. The biophysics' studies reveal that in absence of CO2, subtle modifications are observed as function of pH, but that the addition of CO2 leads theirs disappearance. [less ▲]

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See detailFirst-Principles Study on the Lattice Dynamics and Thermoelectric Properties of Materials
Miao, Naihua ULg

Doctoral thesis (2015)

Thermoelectricity has been regarded as one of the most promising strategies for clean, low-cost and environmental friendly sustainable energy for several decades. Perovskite oxides, like SrRuO3, are ... [more ▼]

Thermoelectricity has been regarded as one of the most promising strategies for clean, low-cost and environmental friendly sustainable energy for several decades. Perovskite oxides, like SrRuO3, are considered as a potential thermoelectric material for low-cost and large-scale thermoelectric applications due to their good thermal and chemical stability in a wide temperature range, great flexibility for structural and compositional manipulating, and environmental friendliness. This thesis is devoted to a theoretical study of the lattice dynamics and thermoelectric properties of materials, like SrRuO3 perovskite and MgAgSb-based materials. Firstly, to obtain insight into the lattice dynamics of the SrRuO3, the phonon-related properties are presented and contributes to rationalize better why many ABO3 perovskites, including metallic compounds, exhibit an orthorhombic ground state. Then the thermoelectric properties of SrRuO3 are investigated by combining first-principles calculations and Boltzmann transport theory, revealing the relationship between the exchange-correlation functionals and the thermoelectric quantities. Furthermore, based on the first-principles calculations, effective model potentials for SrRuO3 are constructed providing access to the finite-temperature properties and phase-transitions. Additionally, the electronic structure and thermoelectric properties of a class of new emerging MgAgSb-based materials, which are promising for room-temperature thermoelectric applications, are also studied and the optimization strategies are proposed for the improvement of thermoelectric performance. [less ▲]

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See detailModeling of aerodynamic forces in flapping flight with the Unsteady Vortex Lattice Method
Lambert, Thomas ULg

Master's dissertation (2015)

This thesis concerns the extensive study and comparison of two approaches commonly used to compute the aerodynamic forces with the unsteady vortex lattice method. The first approach was introduced by Katz ... [more ▼]

This thesis concerns the extensive study and comparison of two approaches commonly used to compute the aerodynamic forces with the unsteady vortex lattice method. The first approach was introduced by Katz and Plotkin and is based on Bernoulli's equations, the second approach was based Joukowski's equations for the computation of forces. This report is divided in two main sections: the study of one wing undergoing simple movements (steady, pure harmonic pitching and pure harmonic plunging) and the study of two separate wings undergoing a combination of flapping and pitching such as seen in avian flight. For the simple test cases, the results obtained with both methods of computation were first compared to an analytical solution for a (quasi) 2D case. Then the comparison of both methods was made for finite wings. For the 3D problem a convergence study was done with respect to the chordwise discretisation of the airfoils. This section showed that for all the cases, the two methods give almost the same answer and therefore they could be considered as equivalent. The convergence study realised for finite wings showed however that Joukowski's method converges quicker than Katz's for symmetric airfoils, but it is the other way around when it comes to cambered airfoils. The study of the flapping and pitching motion is based on the work of N. Abdul Razak. The influence of pitch leading was extensively studied as this phenomenon presents a flow attached at all time, so these kinematics are well suited for the vortex lattice method. Both pure flapping and pitch lagging were also discussed but more briefly. For pitch leading, the study showed that in general both methods give the same results for the drag and the lift. Moreover, the UVLM solutions were very close to the experimental ones, especially for the drag. The convergence showed a small advantage for the Katz method for the coarser meshes, but in the end both methods appear to reach convergence for the same discretisation. [less ▲]

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See detailStudy of the recent disappearance of a tropical glacier in the Bolivian Andes with the help of the high resolution regional climate model MAR
Scholzen, Chloé ULg

Master's dissertation (2015)

This study provides a first evaluation of the MAR (Modèle Atmosphérique Régional) model over the Bolivian tropical Andes. MAR is currently developed at the ULg and allows dynamical downscaling up to 5 km ... [more ▼]

This study provides a first evaluation of the MAR (Modèle Atmosphérique Régional) model over the Bolivian tropical Andes. MAR is currently developed at the ULg and allows dynamical downscaling up to 5 km of horizontal resolution. The purpose of this work is to model the recent changes in the climatic parameters which are thought to control the mass and energy balance of mountain glaciers in the outer tropics. We focus on the recently vanished Chacaltaya Glacier (16°S), which by virtue of its location and its environmental context is representative of many small-sized glaciers of the Bolivian Andes. To evaluate our model, we first examine simulated precipitation and near-surface temperature against in situ observations from ground weather stations. Since observational data is very scarce in this part of the world, we also refer to qualitative information provided by the scientific literature. We compare the performance of the model forced with two different reanalyses, and with several corrections applied to the lateral boundary conditions (LBCs) impacting on temperature and humidity. MAR forced with the ERA-Interim reanalysis yields better results than with the NCEP/NCAR-v2 reanalysis. We then use the best ERA-driven simulation to assess the long-term climate change over 1960-2014 in the region of the Chacaltaya Mountain. The regional atmospheric circulation is adequately simulated by MAR, which reproduces the prevailing seasonal features of the lower, middle and upper troposphere. The climatic anomalies associated to the El Niño Southern Oscillation (ENSO) events are also properly recreated. Remaining model biases include an overall year-round dry bias over the Altiplano region, due to the strong corrections applied to the LBCs (-15% for humidity). Over the highest elevations of the Andes, both precipitation and cloud cover are probably overestimated by MAR. The sporadic spatial distribution of convective rainfall also suggests numerical instability in the convective parameterization scheme. Modeled temperatures match very well the observations, but the reliability of the observed time series is highly questionable. Between 1960 and 2014, the most significant trends concern precipitation and cloud cover which both decreased of about 35%. The surface radiation budget also changed as a result of the reduced cloudiness. Near-surface temperature increased by about 1.5°C. Those trends are believed to have been enhanced by the more frequent and more intense El Niño events during the warm Pacific Decadal Oscillation (PDO) phase between 1977 and 1999. The combination of the repeated droughts and the enhanced incoming short-wave radiation due to reduced low-level cloudiness are probably the main factors responsible for the acceleration of the Chacaltaya Glacier recession. Nevertheless, the ENSO signal is not always clear in the Bolivian Andes, because of the interference with strong local climatic processes. Moreover, additional forcings of non climatic nature may also be responsible for the rapid demise of the Chacaltaya Glacier. [less ▲]

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See detailApproche contingente du design du système d’information comptable dans les PMI tunisiennes : une étude fondée sur les équations structurelles
Ghorbel, Jihene ULg

Doctoral thesis (2015)

Malgré les recherches sur le système d’information comptable dans les PME, les résultats trouvés sont mitigés et contradictoires. Ainsi, nous essayons à travers ce travail de contribuer au débat relatif ... [more ▼]

Malgré les recherches sur le système d’information comptable dans les PME, les résultats trouvés sont mitigés et contradictoires. Ainsi, nous essayons à travers ce travail de contribuer au débat relatif au design du système d’information comptable dans les PMI des pays en voie de développement comme la Tunisie. En effet, le système d'information comptable, considéré comme un facteur de compétitivité des entreprises, fournit aux gestionnaires l'information comptable pertinente pour les aider dans leur prise de décision. Nous nous intéressons à une série de facteurs structurels et comportementaux susceptibles de mieux cerner le design du système d’information comptable. Une étude empirique menée par l'adoption de la technique du questionnaire auprès de 221 entreprises tunisiennes opérant exclusivement dans le secteur industriel montre que le design du système d'information comptable est influencé par plusieurs facteurs contextuels, en utilisant les méthodes des équations structurelles. [less ▲]

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See detailMiliter pour et sur Internet. L'adhésion au Parti Pirate belge
Macq, Hadrien ULg

Master's dissertation (2015)

Suède, le 7 juin 2009. Aux élections européennes, un parti politique vient de créer la surprise. Il s’agit du Piratpartiet, fondé à peine trois ans plus tôt et qui vient de récolter sept pourcents des ... [more ▼]

Suède, le 7 juin 2009. Aux élections européennes, un parti politique vient de créer la surprise. Il s’agit du Piratpartiet, fondé à peine trois ans plus tôt et qui vient de récolter sept pourcents des suffrages, obtenant de la sorte un élu au Parlement. Ce parti, créé avant tout pour défendre une autre idée de la propriété intellectuelle, fait rapidement plusieurs dizaines d’émules à travers le monde, y compris en Belgique. La base de leurs revendications est invariable : réforme du droit d’auteur, abolition du brevet sur le vivant et le logiciel, meilleure défense des données privées. Les partis pirates se distinguent également par une utilisation intensive des nouvelles technologies de l’information et de la communication, tant dans leur communication vers l’extérieur que dans leur gestion interne. L’apparition de tels partis sur la scène politique peut être mise en perspective avec deux tendances plus larges au sein des sociétés occidentales. D’une part, Internet s’est petit à petit constitué en tant qu’enjeu politique à part entière, questionnant le système politique sur son mode de gouvernance et son degré de régulation. D’autre part, les pratiques d’engagement se sont progressivement transformées jusqu’à inciter les organisations politiques traditionnelles à s’adapter aux volontés des supposés néo-militants. Dans ce cadre, les partis politiques ont notamment pu s’appuyer sur Internet pour offrir un mode de participation plus souple et plus à même d’attirer de nouveaux adhérents. Cette tendance serait d’ailleurs arrivée à son zénith avec l’émergence de « cyber-partis », basant une grande partie de leur structure sur l’usage des réseaux télématiques. C’est dans cette optique que s’inscrit cette étude, avec pour objectif plus particulier d’interroger les impacts d’Internet sur la dynamique d’adhésion partisane. La question posée est la suivante : quel rôle Internet joue-t-il dans l’adhésion au Parti Pirate belge ? A partir de ce cas, ce sont les perspectives plus larges de l’adhésion aux cyber-partis et des pratiques contemporaines d’engagement qui peuvent être envisagées. De cette manière, il est possible d’apporter certaines réponses au renouvellement des questionnements en science politique engendré par le Web, concernant notamment la participation politique et l’organisation des partis. [less ▲]

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See detailL'estétrol et le développement tumoral
Gallez, Anne ULg

Master's dissertation (2015)

A l’heure actuelle, le risque augmenté de troubles thromboemboliques et de cancer du sein chez les femmes sous hormonothérapie est un problème majeur de santé publique. La découverte de nouvelles ... [more ▼]

A l’heure actuelle, le risque augmenté de troubles thromboemboliques et de cancer du sein chez les femmes sous hormonothérapie est un problème majeur de santé publique. La découverte de nouvelles molécules procurant une sécurité sanitaire accrue aux utilisatrices est donc nécessaire. L’estétrol (E4) est proposé comme candidat potentiel. L’E4 est une hormone stéroïdienne, de type « œstrogène », retrouvée naturellement chez l’humain et synthétisée uniquement par le foie fœtal durant la grossesse. Sa grande biodisponibilité orale et son temps de demi-vie de 28 heures chez l’humain le rendent intéressant en tant qu’hormonothérapie de substitution (ERT/HRT). L’E4 est capable de traiter efficacement les symptômes principaux de la ménopause (les bouffées de chaleur, l’atrophie vaginale et l’ostéoporose) et ce, dès une concentration de 0,3 mg/kg/jour. L’étude de son impact sur le cancer du sein est au centre de ce mémoire, puisque c’est l’une des conséquences majeures de l’utilisation prolongée d’œstrogènes et que les données de la littérature restent controversées Des résultats préliminaires obtenus au laboratoire ont montré que l’E4 (3 mg/kg/jour) augmentait le poids des tumeurs dans le modèle murin de carcinogenèse mammaire MMTV-PyMT, contrairement à l’ovariectomie et au traitement au Tamoxifène. Au terme de ce mémoire, nos recherches démontrent que l’E4 utilisé aux doses 0,3 et 7 mg/kg/jour n’influence pas significativement la croissance tumorale. Par contre, l’E4 à 3 mg/kg/jour majore le poids tumoral et la dissémination métastatique chez des animaux ovariectomisés et intacts. De plus, l’E4 délivré à 3 mg/kg/jour est capable d’augmenter l’angiogenèse et de diminuer la nécrose et l’hypoxie intra-tumorale, de manière similaire à l’oestradiol (E2) alors que la dose de 0,3mg/kg/jour n’est pas suffisante pour observer cet effet. En conclusion, les travaux menés pendant mon mémoire de Master ont permis de caractériser les effets de l’E4 sur la carcinogenèse mammaire hormonodépendante, la dissémination métastatique et l'angiogenèse tumorale. Au vu de nos résultats, nous ne pensons pas qu'il soit judicieux d'utiliser l'E4 comme traitement anti-tumoral, comme cela a été suggéré par certains auteurs. Au contraire, nos données suggèrent que pour éviter un effet de l’E4 sur la croissance tumorale et l’angiogenèse, il est nécessaire de privilégier le développement d’un traitement clinique de la ménopause avec de faibles concentrations d’E4. [less ▲]

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See detailEtude de l'évolution des conditions climatiques dans la région du Kilimandjaro, à l'aide du modèle MAR, sur la période 1951-2014
Flachat, Alexia ULg

Master's dissertation (2015)

Kilimanjaro glaciers appear among the most famous tropical glaciers. Even if they represent only 5% of the moutain glaciers, tropical glaciers are very interesting witnesses of the global warming. Indeed ... [more ▼]

Kilimanjaro glaciers appear among the most famous tropical glaciers. Even if they represent only 5% of the moutain glaciers, tropical glaciers are very interesting witnesses of the global warming. Indeed, their time of answer and their sensibility to climatic variations are more important than those of higher latitudes glaciers. Moreover, tropical climate is a very stable climate, which doesn’t present strong annual amplitudes of temperature. Thereby, the temperature is constantly negative at the top of the Kilimanjaro, what induces that the melting is essentially made by sublimation : ice passes from the solid state to the gaseous one, without passing by the liquid state. If we refer to the studies led since the half of the 19th, the climate change had for consequences to intensify the melting of Kibo ice cap, making spend its surface from 12,06 km² in 1912, to 2,36 km² in 2011. Hence, we decided to study by using the Regional Atmospheric Model (MAR), the evolution of climatic conditions in the region of the Kilimanjaro, over the period 1951-2014. We were thus able to put forward, firstly, that the decrease in cloudiness and precipitation, as well as the increased solar radiation, have played an important role in the melting of these glaciers. On the other hand, we also demonstrated that the NCEP and ERA-Interim reanalyses on Africa are not reliable, and consequently, the model presents difficulties to represent in a correct way the climate in our zone. To finish, we analyzed if we found the El Niño and La Niña events, of which the impact on the East African climate has been shown, in the model outputs. [less ▲]

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See detailContribution au monitoring de populations d'hippopotame commun (Hippopotamus amphibius L.) par l'utilisation de la technologie drone (Parc National de la Garamba, République Démocratique du Congo)
Lhoest, Simon ULg

Master's dissertation (2015)

In an era of indisputable decline in populations of large wildlife species, setting up regular and efficient monitoring methods is essential. Because of the difficulties associated with conventional ... [more ▼]

In an era of indisputable decline in populations of large wildlife species, setting up regular and efficient monitoring methods is essential. Because of the difficulties associated with conventional pedestrian and aerial survey procedures, the development of UAV technology turns out to be a potentially interesting alternative. This work focuses on monitoring common hippopotamus (Hippopotamus amphibius L.) with the use of this innovative tool. The search for flight parameters optimization to maximize detection and visibility of animals showed a very small decrease in detection rate and certainty of counts with an increasing flying height and a high variability linked to operators realizing observations. It is recommended to fly at a height of 140 meters above ground level, between 6:30 and 8:45 am at the end of the dry season, with cloud cover and wind as low as possible. Three counts correction methods are proposed to estimate the total population from the only emerged observed animals. The average overall correction factor is 1.252. An attempt to describe the demography of a group by individuals length measurements was also implemented. It allowed to obtain a mean distribution of hippos in three age classes, even if results are not extremely accurate. Finally, an algorithm for the semi-automatic count of hippos on thermal infrared imagery was developed, and brought to a mean error of +3.9%. Taking into account the recommendations proposed in this study for the development of inventories protocols would help dealing with the practical constraints of conventional monitoring methods. [less ▲]

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See detailEcologie de reproduction du doussié, Afzelia bipindensis Harms, en forêt dense humide tropicale gabonaise.
Evrard, Quentin ULg

Master's dissertation (2015)

The species Afzelia bipindensis is a precious woody tree known for its wood quality and considered vulnerable by the IUCN. In order to improve the current knowledge gaps about its reproductive ecology ... [more ▼]

The species Afzelia bipindensis is a precious woody tree known for its wood quality and considered vulnerable by the IUCN. In order to improve the current knowledge gaps about its reproductive ecology, the goals of this study are: (1) identify animal dispersers/predators of the seeds with direct and indirect observation methods, (2) quantify the dispersion/predation, (3) test the germination dynamics of those seeds under some circumstances that are likely to influence it, (4) model the growth of juveniles depending upon the access to light. This study was carried out in the forest concession attributed to the Precious Woods society and situated in evergreen forests in East Gabon. After more than 100 hours of direct observation and 3.000 hours of image capture by camera-trap, only four species (Cricetomys emini, Epixerus wilsoni, Protoxerus stangeri and some undetermined Muridae) would be the main animal species to get interested to Afzelia seeds. Those would take more than 90 % of the seeds and would be essentially predators. The results of the germination test revealed a significant influence of the aril on the germination rate. The conservation time and the volume of the seed had also a significant influence over its fitness. Finally, the modeling of growth showed a very low average growth value over time compared to equivalent data collected in Cameroon and a very high mortality rate, probably due to a high predation rate by duikers. [less ▲]

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See detailFrom mucosal resistance of larvae to behavioral fever of fingerlings: a journey in the innate immune defenses of common carp against cyprinid herpesvirus 3
Ronsmans, Maygane ULg

Doctoral thesis (2015)

Cyprinid herpesvirus 3 (CyHV-3) is a highly pathogenic virus responsible for a lethal disease in both common and koi carp (Cyprinus carpio). The common carp is one of the most important freshwater species ... [more ▼]

Cyprinid herpesvirus 3 (CyHV-3) is a highly pathogenic virus responsible for a lethal disease in both common and koi carp (Cyprinus carpio). The common carp is one of the most important freshwater species cultivated for human consumption. Its colourful subspecies koi is grown for personal pleasure and exhibitions. Both common and koi carp are economically important and since its description in the late 1990s, the CyHV-3 has caused severe financial losses in these two carp industries worldwide. Because of its economic importance and its numerous original biological properties, CyHV 3 became rapidly an attractive subject for both applied and fundamental research. The objectives of this thesis were to investigate the role of two unrelated innate immune mechanisms of carp in anti-CyHV-3 immunity. The first objective was to determine the role of epidermal mucus as an innate immune barrier against CyHV-3 entry during the early developmental stages of carp. To test this hypothesis, we investigated the sensitivity and the permissivity of carp to CyHV-3 during the early stages of its development. This hypothesis was tested using a recombinant CyHV-3 strain expressing luciferase as a constitutive reporter gene and in vivo bioluminescence imaging system. We demonstrated that carp are sensitive and permissive to CyHV 3 infection since hatching, but that their sensitivity remains relatively low in the two early developmental stages. Similarly to adults, we confirmed that the skin is the main portal of entry for the virus at early stages, and our results stress out the role of epidermal mucus as an innate immune defense of carp against pathogens even and especially at the early stages of development. The results of this study have been published in Veterinary research. The second objective of this thesis consisted to investigate whether carp express behavioral fever when infected by CyHV-3; and if so, what could be the effect of this innate immune reaction on the development of CyHV 3 disease. When infected by pathogens, both endotherms and ectotherms can express a salutary reaction by increasing their body temperature. While in endotherms this reaction is called fever and depends on intrinsic thermogenesis, ectotherms like teleosts can only upregulate their body temperature by moving to warmer places, hence the term behavioral fever. When studying the pathogenesis of CyHV-3, we observed that carp infected at 24°C (the thermal preference of healthy carp) tended to concentrate around the tank heater when it was running. This observation led us to postulate that infected subjects could express behavioral fever in natural environments where temperature gradients exist. Using multi-chamber tanks encompassing a gradient from 24°C to 32°C, we observed that carp infected by CyHV-3 express a salutary behavioral fever that completely suppresses virus induced mortalities. The relatively late onset of behavioral fever with respect to clinical signs, viral replication and cytokine upregulation led us to postulate that this phenomenon could be delayed by the virus to retain its host at a permissive temperature thereby favoring its replication and spreading. As some herpesviruses have been shown to express soluble decoy cytokine receptors, we hypothesized that CyHV-3 could express such receptor(s) able to neutralize putative pyrogenic cytokines produced by the fish. We found that CyHV-3 ORF12 encodes a soluble decoy receptor for carp Tnfα and that this viral protein makes the virus capable of delaying the migration of infected fish to warmer environments. Remarkably, the study of the molecular mechanism through which the virus alters its host’s behavior led to the discovery of the first pyrogenic cytokine in ectotherms (Tnfα). This study is the first to report the ability of a vertebrate virus to alter the behavior of its host through the expression of a single gene. This second study was submitted for publication when this thesis was printed. In conclusion, we investigated two innate immune mechanisms expressed by carp against CyHV 3 infection. The results generated in this thesis bring findings related to several scientific fields such as virology, immunology, animal behavior, evolution, ecology and even animal welfare. [less ▲]

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See detailGestion du risque associé au cycle de vie des méthodes analytiques : Applications aux molécules de faibles poids moléculaires analysées par Spectrométrie de Masse
Hubert, Cédric ULg

Doctoral thesis (2015)

Analytical method lifecycle is composed of several steps, but always starts with a question defining the problem. Analytical method performances are consequently specified by the analyst trough the ... [more ▼]

Analytical method lifecycle is composed of several steps, but always starts with a question defining the problem. Analytical method performances are consequently specified by the analyst trough the definition of the “Analytical Target Profile (ATP)”, as proposed by the regulatory bodies. Subsequent steps (namely the development and validation steps) then take place, followed by routine use of the analytical procedure. In the specific context of the pharmaceutical industry, regulatory authorities have recently imposed the assessment and management of risk throughout the entire product lifecycle. This includes the analytical procedure and consequently its own lifecycle. Working in this context, our concerns were initially focused on the validation step of the method lifecycle. Indeed, the objective of analytical method validation is to demonstrate that this method is suited for quantifying the target analytes with an established and suitable level of accuracy, as defined by the “ATP”. This is sometimes called the “fit-for-future-purpose” concept. In the course of this study we have experimentally confirmed that a decision regarding the validity of a method based on prediction can be achieved by using the “β-expectation tolerance interval” (accuracy profile) as a decision tool. Indeed, it seemed essential to demonstrate the capability of this approach to manage a part of the analytical risk before addressing the development step. Typically this step of the analytical procedure lifecycle is addressed using a “Changing One Separate Factor a Time (COST)” approach (also known as the “Quality-by-Testing (QbT)” approach). By means of a complex case study, and considering validation of the method through the accuracy profile, we have shown that this strategy can lead to a suitable method for assessing the risk of routine use, even where the experimental domain is not examined. In order to consider an experimental domain rather than a set of specific experimental conditions during the development phase, we have evaluated a multivariate approach: the “Quality-by-Design (QbD)” strategy. This strategy allows the definition of a “Design Space (DS)” by means of design of experiments (DoE). This DS, computed considering critical method parameters, allows the analyst to focus on the main objective of an analytical method: obtaining reliable results using a robust method. A comparative study of the QbT versus QbD approach was performed. In the course of this study, the benefits of the QbD strategy in terms of managing the qualitative part of the analytical risk were highlighted. Finally, we have focused our research on the development of a global strategy allowing the unification of the development and validation phases in a single step. With this innovative approach, we are the first to propose a strategy allowing the management of global analytical risk (i.e., both qualitative and quantitative risk). Indeed, we have demonstrated that it is possible to validate an experimental domain by means of the accuracy profile. With this innovative strategy, the DS is no longer simply the place where qualitative performances are obtained, but also the space where quantitative performances of the analytical procedure are assessed and managed. In conclusion, during this thesis, we have confirmed the predictive capabilities of the accuracy profile. Moreover, we have highlighted the benefits of a QbD strategy in terms of risk management. We have also demonstrated that this methodology can be used as a learning tool, facilitating the continuous improvement of the analytical procedure. Furthermore, with the innovative strategy presented during the latter part of this work, we have demonstrated that qualitative and quantitative risk can be assessed and managed throughout the entire analytical method lifecycle. [less ▲]

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See detailMise en place d’un système de mesure par covariance de turbulence des flux de N2O sur une parcelle agricole
Lognoul, Margaux ULg

Master's dissertation (2015)

Nitrous oxide (N2O) is a greenhouse gas responsible for 8% of anthropogenic radiative forcing. It is also a major contributor to stratospheric ozone depletion. Agricultural soils represent its main source ... [more ▼]

Nitrous oxide (N2O) is a greenhouse gas responsible for 8% of anthropogenic radiative forcing. It is also a major contributor to stratospheric ozone depletion. Agricultural soils represent its main source. N2O is produced by microorganisms through nitrification and denitrification processes. Both depend on oxygenation conditions and nitrogen and labile carbon availability, which are driven by soil and climate conditions and by farming practices. Yet there remain science gaps concerning the understanding of emission mechanisms and dynamics. The eddy covariance technique allows studying a whole ecosystem with a half-hourly temporal resolution, opening up for long-term monitoring and precise greenhouse gas budget calculation. However, this technique requires a specific expertise. In order to install such a system to measure N2O exchanges by a production crop at the Terrestrial Observatory of Lonzée (Belgium), we set the following goals : (1) establishing the state of knowledge concerning N2O fluxes exchanged by crops and identifying gaps, (2) setting up a N2O analyzer at the experimental site and providing operating procedures, and (3) building and adjusting the first data processing and calculation procedures. As a result of this work, scientific gaps were identified and avenues for further research are suggested. Monitoring and data acquisition routines as well as first data processing procedures were implemented. Numerous questions still remain regarding the adaptation of classical methods (created to study CO2) to N2O, and they constitute the investigation prospects of this work. [less ▲]

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See detailEtude de la biodégradation anaérobie des feuilles de Mangifera indica (manguier) et de Manihot utilissima (manioc)
Mambanzulua Ngoma, Philippe ULg

Doctoral thesis (2015)

The population growth of these last two decades leaded to an increase of waste in the City Province of Kinshasa (VPK), capital of the Democratic Republic of Congo. Deprived by an effective management ... [more ▼]

The population growth of these last two decades leaded to an increase of waste in the City Province of Kinshasa (VPK), capital of the Democratic Republic of Congo. Deprived by an effective management system, the VPK produces essentially vegetal wastes that are constituted for the greater part of dead leaves. These wastes bother and pollute the environment. On another point of view, the Kinshasa households meet enormous difficulties for soil fertilization and to collect wood for energy. Its overexploitation of the wood entails the deterioration of the ecosystems and the public health. Therefore in order to contribute to the reduction of all these difficulties simultaneously, the aim of this thesis was to investigate the methanization of these wastes since this technique is relatively simple, fast and non expensive. So, the methanation was performed at 30°C on the leaves of Mangifera indica (MU, mango) and of Manihot utilissima (MI, cassava) that are the most accessible of the VPK. The biochemical methane potentials of the MU and MI leaves demonstrated that the MU leaves were favorable to the methanation due to their low content in bioactive substance (secondary metabolites) and their low C/N ratio. In addition, their digestates would be an effective fertilizing. By contrast, the MI leaves were unfavorable to the methanation since the methanogenesis was inhibited, probably because of their composition rich in carbon and secondary metabolites (lignine, polyphenols, saponines and anthraquinones). However, these metabolites would be beneficial for the methanation in lower contents than 0.3 g/l in the culture medium. The anaerobic co-digestion improved the daily methane yields of these two leaves. The biogas produced with this process would represent about 28 % of the wooden annual domestic consumption and its digestate would cover annually the all agricultural and forest degraded areas. So, the domestic methanation or on site or near the site of waste generation would be favored to avoid the cost of their transport and their industrial treatment. A promising pilot essay has been achieved. [less ▲]

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See detailA Feasibility Study of Direct Injection Spraying Technology for Small Scale Farms: Modeling and Design of A Process Control System
El Aissaoui, Abdellah ULg

Doctoral thesis (2015)

El Aissaoui Abdellah (2015). A feasibility study of direct injection spraying technology for Small Scale Farming: Modeling and design of a process control system. University of Liege-Gembloux Agro-Bio ... [more ▼]

El Aissaoui Abdellah (2015). A feasibility study of direct injection spraying technology for Small Scale Farming: Modeling and design of a process control system. University of Liege-Gembloux Agro-Bio Tech. Belgium. 175p., 11 tabl., 75 fig. The study aims to develop a process controller of direct injection spraying system (DIS) that can fit to carry out precise chemical application using variable rate application based on speed sensing in the context of small scale farming. It has the specific objectives of studying the feasibility of DIS by optimizing the hydraulic system and the process control designs as the main requirements for the best system reactivity and performance. The final design of DIS assessed to implement hydraulic system (hardware) and process controller (software) of a sprayer framework mounted on a rolling chariot propelled by walker operator. A logical approach is used of reviewing the state of art and formulating a specification book to develop a cost effective prototype to eventually adapt DIS expertise to the context of small scale farming. The demarche consists on giving low cost solution of variable rate technology to solve the technical problems related to usage and inefficiency of pesticide application mainly done by portable sprayers. The state of art gives a light on the development process of direct injection spraying technology (DIS) within the scope of precision agriculture progress. It also deals with technical options, advantages and problems related to DIS and control engineering solutions developed for improving spraying application efficiency and safety measures for human and environment. After that we have specified requirements of the researched DIS prototype by referring to existing art of DIS technologies and by diagnosing problems of chemical application in the context of small scale farming. It concerns specifically the technical requirements, setting values and performance of DIS process controller according to the working conditions of intensive cropping in small farming. The materials and methods consist on presenting the approach used for modeling the DIS prototype (splitting the problematic to the two main design aspects of hydraulic system and process control system) and evaluating it in laboratory conditions using simulated velocity data input. The data acquisition system is implemented for assessing the performance of DIS hydraulic and process controller performances. After that, the process controller is implemented in a cost effective electronic kit (box) to be mounted on a small sprayer framework propelled by worker. The hydraulic modeling of DIS served for optimizing the lag transport task as main problem of system reactivity performance and concentration process change. An algorithm is implemented in VB program to assess effect of hydraulic serial boom design (diameter and number of mounted nozzles in serial scheme) on flow dynamic to find compromise between lag transport, mixing ability (turbulence) and friction loss tasks that yield lateral and longitudinal uniformities application of standard boom layout. The modeling results showed lag transport and uniformity of respectively 2 s and 96 % for optimal conventional boom of 6 mm inner diameter having ten tip nozzles (ISO11003, 1.2 L/min~3bars). To solve systematic problem of lateral miss uniformity of serial boom layout (standard scheme), improved parallel boom layout (equidistant tubing lines of 4 mm diameter) is adopted for obtaining an even lag transport between nozzles. The test of parallel boom layout showed even lag transport approximating 1.5 s for ten mounted nozzles. The total response time of DIS is optimally improved to be within 2.5 s by installing electrical pumps close to boom and injecting chemical in suction side to the carrier pump assumed to perform online mixing without use of static mixer. The PID feedback controller is modeled in MATLABTM software. The process is considered as a first order process having a time constant of 0.2 s and a delay transport less than 2 s. Two control strategies of constant carrier flow control (CCFC) and total flow control (TFC) are modeled and implemented for test in laboratory conditions. Both strategies were tested and evaluated on the basis of different solicitations of variable speed input within the range of 0 - 2 m/s as a field working condition of walker operating a rolling sprayer chariot. Finally, on the basis of the results of modeling and experimental assessment, an affordable kit of PLC process controller and PWM modules for actuating carrier pump and metering pump is performed in compact electronic box for potential usage on small sprayer framework to be propelled by walker operator in agricultural field. The controller is based on a PLC microcontroller implemented for carrying out a constant carrier flow rate and a variable chemical injection rate proportionally to the operating speed. The prototype is tested for applying variable rate application using simulated step solicitations within the range of the operator working conditions of 0 - 2 m/s. The study showed the feasibility of implementing a cost effective process controller design for applying variable rate chemical in small farming context. The controller is adaptable for sprayer mounted on wheeled chariot to be propelled by worker assumed to walk at variable velocity. [less ▲]

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See detailDÉTECTION ET QUANTIFICATION DES RACINES ET DES RÉSIDUS DE CULTURE DE FROMENT D’HIVER (TRITICUM AESTIVUM L.) PAR IMAGERIE HYPERSPECTRALE PROCHE INFRAROUGE
Fraipont, Guillaume ULg

Master's dissertation (2015)

On the basis of 384 soil samples collected at 4 different dates during the 2011-2012 crop season in the 0-30 cm soil horizon, this master thesis allowed the study of crop residues evolution and the ... [more ▼]

On the basis of 384 soil samples collected at 4 different dates during the 2011-2012 crop season in the 0-30 cm soil horizon, this master thesis allowed the study of crop residues evolution and the development of winter wheat root system throughout the crop season by the means of NIR-HSI technology and chemometric tools. [less ▲]

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See detailCases remémorées, redessinées. Mémoire de la bande dessinée, détournement et traces graphiques dans 'Au travail' d'Olivier Josso Hamel
Crucifix, Benoît ULg

Master of advanced studies dissertation (2015)

In his autobiographical comic Au travail, published at L’Association in 2012, Olivier Josso Hamel remembers his childhood readings of classic Franco-Belgian bandes dessinées by redrawing panels and ... [more ▼]

In his autobiographical comic Au travail, published at L’Association in 2012, Olivier Josso Hamel remembers his childhood readings of classic Franco-Belgian bandes dessinées by redrawing panels and sequences from these comics into the texture of his own graphic novel. This citational practice works as a détournement of the original material based on the author’s memories of specific images. Embedded in an autobiographical perspective, this appropriative technique sustains a retrospective reflection on what it means to be marked by an image. In this sense, Au travail offers a compelling ground to rethink the “case mémorable” (or ‘remembered panel’) a concept put forward by Pierre Sterckx to refer to comics panels remembered from childhood because of their visual impact. Through an analysis of Josso Hamel’s graphic novel, this paper argues that the remembered panel is not stictly mental but implies an active remembrance linked to the desire to share those personal images. As such, it is an intimate act of canonization based on the collective sharing of a personal history of comics. Expanding on Sterckx’s concept, this paper further seeks to show how the détournement of Franco-Belgian comics – as well as other graphic materials – in Au travail compels the author to reconsider his approach to drawing, reinventing his own style through the ‘graphic traces’ of his childhood. In turn, this carries further weight on the concept of the remembered panel: Josso Hamel’s practice of citation foregrounds the fragmentation of the narrative into fetishized images that become rooted in a personal history. In this way, Au travail highlights how non-narrative reading practices can break up the narrative into fragments that are reorganized into new combinations: not only in the author’s memory, but also and foremost in an ever-changing collective memory of the past of comics. [less ▲]

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See detailStudies of nebulae ejected from massive stars based on observations with the Herschel space observatory
Vamvatira-Nakou, Chloi ULg

Doctoral thesis (2015)

This PhD thesis is devoted to the study of the nebulae ejected by the luminous blue variable (LBV) stars WRAY 15-751 and AG Car as well as by the Wolf-Rayet star WR 124. It is based on new infrared data ... [more ▼]

This PhD thesis is devoted to the study of the nebulae ejected by the luminous blue variable (LBV) stars WRAY 15-751 and AG Car as well as by the Wolf-Rayet star WR 124. It is based on new infrared data taken by the Herschel Space Observatory. These data were complemented by optical data as well as by archived infrared observations. In the first chapter, a general introduction to the subject is given along with a description of the methods used for the data analysis. The three following chapters contain the study of each one of the three nebulae separately. This led to the determination of the physical parameters of the dust and gas components, with the aim to shed a new light on the mass-loss history of the central stars. In particular, the new Herschel infrared images provide a detailed mapping of the nebular dust distribution and of the circumstellar environment at different scales, revealing multiple shells and cavities linked to previous mass-loss events. Moreover, the combination of Herschel photometric results along with archival data was used to model dust with the help of a two-dimensional publicly available radiative transfer code. This model provided us with the dust mass, temperature and composition. The Herschel infrared spectra of all nebulae revealed forbidden nebular emission lines coming not only from an ionized gas region but also from a region where the gas is neutral. Based on the emission line flux measurements, the gas mass and the abundance ratios were estimated. These results, combined with the theoretical models of stellar evolution, were then used to constrain the evolutionary stage of the star at which each nebula was ejected. This study underlines the importance of the Herschel infrared observations for these nebulae. Thanks to them, a better understanding of these objects has been achieved. In particular, a second bigger and fainter dust shell was discovered around WRAY 15-751. In addition, all nebulae were found lying in empty cavities, probably formed during a previous evolutionary phase of their central star. The dust models indicated the necessity to include large grains in all nebulae to reproduce the data. This study showed that for the LBV WRAY 15- 751, with an initial mass of 40 M sun, the nebular ejection took place during a red supergiant phase, while for the LBV AG Car, with an initial stellar mass of 55 M sun, the ejection happened during a cool LBV phase. For the nebula M1-67 around the star WR 124, with an initial mass of 60 M sun, the ejection also took place during a LBV phase. These results are in agreement with the current evolutionary models with little stellar rotation. [less ▲]

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See detailCHARACTERIZATION OF STONY SOILS’ HYDRAULIC PROPERTIES AND REPRESENTATIVE ELEMENTARY VOLUME USING FIELD, LABORATORY AND NUMERICAL EXPERIMENTS
Pichault, Mathieu ULg

Master's dissertation (2015)

Determining soil hydraulic properties is of major concern in various fields of study such as soil physics, hydrology, ecology and agronomy. Though stony soils are widespread across the globe, most studies ... [more ▼]

Determining soil hydraulic properties is of major concern in various fields of study such as soil physics, hydrology, ecology and agronomy. Though stony soils are widespread across the globe, most studies deal with gravel-free soils so that the literature describing the impact of stones on a soil’s hydraulic characteristics is still rather scarce. The aim of this study is to assess, through a case study of a clayey soil in Thailand, the effect of rock fragments on the main hydraulic characteristics, i.e. hydraulic conductivity and retention curves, and on related physical properties of the soil. This was done by means of field, laboratory and numerical experiments involving different amounts and types of coarse fragments. Results were compared with those predicted by several models assuming that stones are non-porous and only reduce the cross-sectional area available for water flow. These models further consider that the shape parameters of the retention and hydraulic conductivity curves are not dependent on the stoniness. We tested the validity of such assumptions. We did not find evidence against the assumption stating that stones might be considered as non-porous. However, our results suggest that the shape parameters of the retention curve vary according to the stone content. Furthermore, considering that stones only reduce the cross-sectional area available for water flow might also be ill-founded. We pointed out several significant drivers of the saturated hydraulic conductivity which are not considered by these models. First of all, the effect due to the creation of voids at the fine earth-stone interface combined with an increased difficulty to repack the fine earth can counteract and even overcome the effect of a reduced cross-sectional area in some cases. Moreover, the shape and the size of inclusions may also affect substantially hydraulic conductivity. Finally, we developed a code destined to quantify the representative elementary volume of soils containing different amounts of stones of various diameters. [less ▲]

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See detailAdvanced numerical framework to simulate Incremental Forming Processes
Velosa De Sena, José ULg

Doctoral thesis (2015)

The framework of the present work supports the numerical analysis of the Single Point Incremental Forming (SPIF) process resorting to a numerical tool based on adaptive remeshing procedure based on the ... [more ▼]

The framework of the present work supports the numerical analysis of the Single Point Incremental Forming (SPIF) process resorting to a numerical tool based on adaptive remeshing procedure based on the FEM. Mainly, this analysis concerns the computation time reduction from the implicit scheme and the adaptation of a solid-shell finite element type chosen, in particular the Reduced Enhanced Solid Shell (RESS). The main focus of its choice was given to the element formulation due to its distinct feature based on arbitrary number of integration points through the thickness direction. As well as the use of only one Enhanced Assumed Strain (EAS) mode. Additionally, the advantages include the use of full constitutive laws and automatic consideration of double-sided contact, once it contains eighth physical nodes. Initially, a comprehensive literature review of the Incremental Sheet Forming (ISF) processes was performed. This review is focused on original contributions regarding recent developments, explanations for the increased formability and on the state of the art in finite elements simulations of SPIF. Following, a description of the numerical formulation behind the numerical tools used throughout this research is presented, summarizing non-linear mechanics topics related with finite element in-house code named LAGAMINE, the elements formulation and constitutive laws. The main purpose of the present work is given to the application of an adaptive remeshing method combined with a solid-shell finite element type in order to improve the computational efficiency using the implicit scheme. The adaptive remeshing strategy is based on the dynamic refinement of the mesh locally in the tool vicinity and following its motion. This request is needed due to the necessity of very refined meshes to simulate accurately the SPIF simulations. An initially mesh refinement solution requires huge computation time and coarse mesh leads to an inconsistent results due to contact issues. Doing so, the adaptive remeshing avoids the initially refinement and subsequently the CPU time can be reduced. The numerical tests carried out are based on benchmark proposals and experiments purposely performed in University of Aveiro, Department of Mechanical engineering, resorting to an innovative prototype SPIF machine. As well, all simulations performed were validated resorting to experimental measurements in order to assess the level of accuracy between the numerical prediction and the experimental measurements. In general, the accuracy and computational efficiency of the results are achieved. [less ▲]

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See detailMultiscale modelling of the hydromechanical behaviour of argillaceous rocks
van den Eijnden, Abraham Pieter ULg

Doctoral thesis (2015)

Feasibility studies for deep geological radioactive waste disposal facilities have led to an increased interest in the geomechanical modelling of its host rock. In France, a potential host rock is the ... [more ▼]

Feasibility studies for deep geological radioactive waste disposal facilities have led to an increased interest in the geomechanical modelling of its host rock. In France, a potential host rock is the Callovo-Oxfordian claystone. The low permeability of this material is of key importance, as the principle of deep geological disposal strongly relies on the sealing capacity of the host formation. The permeability being coupled to the mechanical material state, hydromechanical coupled behaviour of the claystone becomes important when mechanical alterations are induced by gallery excavation in the so-called excavation damaged zone (EDZ). In materials with microstructure such as the Callovo-Oxfordian claystone [Robinet et al., 2012], the macroscopic behaviour has its origin in the interaction of its micromechanical constituents. In addition to the coupling between hydraulic and mechanical behaviour, a coupling between the micro (material microstructure) and macro scale will be made. By means of the development of a framework of computational homogenization for hydromechanical coupling, a doublescale modelling approach is formulated, for which the macroscale constitutive relations are derived from the microscale by homogenization. An existing model for the modelling of hydromechanical coupling based on the distinct de nition of grains and intergranular pore space [Frey, 2010] is adopted and modi ed to enable the application of rst order computational homogenization for obtaining macroscale stress and uid transport responses. This model is used to constitute a periodic representative elementary volume (REV) that allows the representation of the local macroscopic behaviour of the claystone. As a response to deformation loading, the behaviour of the REV represents the numerical equivalent of a constitutive relation at the macroscale. For the required consistent tangent operators, the framework of computational homogenization by static condensation [Kouznetsova et al., 2001] is extended to hydromechanical coupling. The theoretical developments of this extension are implemented in the nite element code Lagamine (Li ege) as an independent constitutive relation. For the modelling of localization of deformation, which in classical FE methods su ers from the well-known mesh dependency, the doublescale approach of hydromechanical coupling is combined with a local second gradient model [Collin et al., 2006] to control the internal length scale of localized deformation. By accepting the periodic boundary conditions as a regularization of the microscale deformation, the use of the multiscale model in combination with the local second gradient model can be used for modelling localization phenomena in HM-coupled settings with material softening. The modelling capacities of the approach are demonstrated by means of simulations of oedometer tests and biaxial compression tests. The approach is demonstrated to be a powerful way to model anisotropy in the mechanical as well as the hydraulic behaviour of the material both in the initial material state and as an e ect of hydromechanical alterations. For the application to the modelling of Callovo-Oxfordian claystone, microstructural REVs are calibrated to geometrical characteristics of the inclusion that form the microstructure under consideration and to macroscale experimental results of the mechanical behaviour. The calibrated constitutive relation is used in the simulation of gallery excavation processes. These computations give a proof of concept of the doublescale assessment of the hydromechanical behaviour of the excavation damaged zones around galleries in the context of nuclear waste disposal. [less ▲]

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See detailGénétique et biologie de la conservation du desman des Pyrénées (Galemys pyrenaicus) en France
Gillet, François ULg

Doctoral thesis (2015)

The Pyrenean desman (Galemys pyrenaicus) is a semi-aquatic mammal endemic to the Iberian Peninsula and the Pyrenees and classified as “vulnerable” by the IUCN. The aims of this PhD thesis, part of a ... [more ▼]

The Pyrenean desman (Galemys pyrenaicus) is a semi-aquatic mammal endemic to the Iberian Peninsula and the Pyrenees and classified as “vulnerable” by the IUCN. The aims of this PhD thesis, part of a National Action Plan, were to improve the knowledge on this species by the development of molecular tools (species identification by sequencing of a fragment of the cytochrome b gene and by RFLP, creation and amplification of polymorphic microsatellites). A genetic structure of three populations associated with low levels of genetic diversity has been evidenced in the French Pyrenees. In addition, the molecular analysis of its diet (COI gene) has allowed to identify its foraging areas and an individual survey on a stretch of river has revealed long distance movements unsuspected before. These results may direct conservation measures for this species. [less ▲]

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See detailEvaluation of the promethazine and acepromazine sedative and hemodynamic effects and norepinephrine reversal of acepromazine induced hemodynamic alterations in the standing horse
De Araujo Pequito, Manuel ULg

Doctoral thesis (2015)

Some phenothiazine derivates, such as acepromazine (ACP), have beneficial properties that could be interesting in equine patients with systemic inflammatory diseases where neutrophil activation and ROS ... [more ▼]

Some phenothiazine derivates, such as acepromazine (ACP), have beneficial properties that could be interesting in equine patients with systemic inflammatory diseases where neutrophil activation and ROS production are implicated. Besides, ACP’s vasodilatatory properties can also be of clinical importance in conditions such as acute laminitis or in anaesthetic protocols. However, the vasodilation induced by ACP is contraindicated in horses suffering from hypotension, a typical complication of systemic inflammatory diseases in horses. The sedative effect of ACP can also have an impact on the correct evaluation of the mental state of a horse in intensive care. Hence, it could be important either to select another phenothiazine derivate with the same beneficial effects as ACP, but with fewer undesirable effects, or to create a medication protocol, in which ACP is associated to another molecule, with the purpose of diminishing its undesired effects. Therefore, this work focused on the comparison of the sedative and peripheral hemodynamic effects of ACP and promethazine (PTZ) as well as on the evaluation of the hemodynamic effects of the administration of ACP followed by a norepinephrine (NOR) infusion in the standing healthy horse. To achieve this objective, 3 different studies were designed. The first one focused on the comparison between ACP and PTZ and the two other ones focused on the study of the association between ACP and NOR. In the first experimental protocol, 9 healthy Warmblood horses randomly received either intravenous ACP at 0.1 mg/kg or PTZ at 0.1, 0.2 or 0.3 mg/kg. A sedation score based on clinical examination was recorded, and systolic arterial blood pressure (SAP) was noninvasively evaluated using a Doppler flow detector at the tail, just before and every 15 minutes until 60 minutes after drug injection. Hemodynamics of the median artery of the left forelimb was studied using Doppler ultrasonography just before and 45 minutes after injection of the drug, which allowed calculation of surface (SURF), diameter (DIAM), and circumference (CIRC) of the vessel, as well as peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (MV), volumetric flow (VF), and resistivity index (RI) of the blood flow. In the second experimental protocol, an infusion of NOR at a constant rate of 1 μg/kg/minute for 15 minutes was administered to 5 standing healthy horses 45 minutes (TACP+45) after intravenous injection of ACP at 0.1 mg/kg. Non-invasive SAP and the same hemodynamic parameters than in study 1 were evaluated on the median artery. The SAP was evaluated before, 15, 30, 45 and every 5 minutes during the NOR infusion (TNORa, TNORb, TNORc) from TACP+45 to 60 minutes (TACP+60) after ACP administration and at 5 (TACP+65), 15 (TACP+75), 30 (TACP+90) and 45 (TACP+105) minutes after stopingt the NOR infusion. In the third experimental protocol, 45 minutes after ACP intravenous injection at 0.1 mg/kg, a continuous NOR infusion was performed during 10 minutes at 0.3 μg/kg/min, then 10 minutes at 0.5 μg/kg/min, and finally 10 minutes at 1 μg/kg/min in 5 standing healthy horses. Cardiac output (CO), stroke volume (SV) and systemic vascular resistance (SVR) were measured using lithium dilution (LiDCO). The mean (MAP), systolic and diastolic (DAP) systemic arterial pressures were measured invasively using an anesthesic monitoring system, that also automatically calculated the heart rate (HR). All parameters were measured immediately before ACP administration, 45 minutes after, at the end of each incremental 10 minutes NOR continuous infusion rate (TNOR0.3, TNOR0.5 and TNOR1) and ten minutes after terminating the NOR infusion. Regardless of the used dose, PTZ had lesser sedative and hypotensive effects than ACP at 0.1 mg/kg and did not induce significant variations in SURF, DIAM, CIRC, PSV, EDV, MV, VF, and RI of the studied standing horses. Conversely, the vasodilatory and hypotensive properties of ACP were illustrated by a significant increase in SURF, DIAM, CIRC, PSV, EDV, MV, and VF and a significant reduction of the RI and SAP. Unlike ACP, PTZ did not induce alterations on the morphology of the Doppler waveform. All the ACP-induced hemodynamic alterations, with the exception of PSV and MV were significantly counteracted by the NOR infusion at a constant 1 μg/kg/minute rate, from TNORa to TNORc for EDV, VF, MV and RI, and to TACP+65 for SAP, from TNORb to TACP+90 for CIRC and SURF and to TNORc for DIAM. Besides, although the ACP induced hypotension, no significant changes were observed in the CO, SV, SVR and HR. NOR infusion at incremental doses counteracted the decrease of SAP, from TNOR0.3 to TNOR1, of MAP at TNOR0.3 and TNOR1 and of DAP at TNOR1. After the ending of the infusion, the arterial pressure again dropped significantly, the CO and HR increased non significantly, and the SVR decreased non significantly. PTZ appears to have less sedative and peripheral vasodilator effects than ACP, thus it could be safer than ACP in patients suffering from hypotension. The results also demonstrate that a NOR infusion can reverse ACP’s vasodilatory effects, restoring hemodynamic parameters and blood pressure in horses. The studied NOR infusion proved hence to be useful in horses suffering from vasodilation and hypotension, as it reverted the hemodynamic alterations induced by ACP. [less ▲]

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See detailLa Musique silencieuse de José Muñoz et Carlos Sampayo : déconstruction des normes et lecture émotionnelle
Dejasse, Erwin ULg

Doctoral thesis (2015)

Cette thèse met en lumièredans l'oeuvre de José Muñoz et Carlos Sampayo les mécanismes de déconstruction des normes issues de la bande dessinée de genre fondée sur le principe de l’illusion référentielle ... [more ▼]

Cette thèse met en lumièredans l'oeuvre de José Muñoz et Carlos Sampayo les mécanismes de déconstruction des normes issues de la bande dessinée de genre fondée sur le principe de l’illusion référentielle. Cette entreprise de dislocation des standards graphiques et narratifs vise à substituer à la lecture traditionnelle fondée sur la consommation du récit, une lecture émotionnelle. [less ▲]

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See detailIntégration de la continuité spatiale dans la structure multidimensionnelle d’un entrepôt de données - SOLAP raster
Kasprzyk, Jean-Paul ULg

Doctoral thesis (2015)

Technological advances in recent decades have created a massive acquisition of digital data whose volume grows exponentially. To efficiently extract the information they contain, powerful tools have been ... [more ▼]

Technological advances in recent decades have created a massive acquisition of digital data whose volume grows exponentially. To efficiently extract the information they contain, powerful tools have been developed to collect, store and analyze these data. These tools are gathered in a discipline called “business intelligence”. Among them, data warehouses are responsible for archiving data by structuring them in a multidimensional way (time, space or others). They are called data hypercubes or data cubes when they are limited to three dimensions. Hypercubes can supply OLAP (On Line Analytical Processing) systems that aim at quickly synthesizing information in interactive tables and charts for decision-makers from various fields: marketing, environment, criminology, etc. Thus, users can navigate into hypercubes using OLAP operations such as slicing on dimension members (e.g. data aggregation for the month of January in the time dimension), or drilling into hierarchies (e.g. switching from the “year” level to the “month” level in the time dimension). When OLAP is coupled with spatial analysis techniques supplied by geographic information systems (GIS), a map interface then improves the exploration of data: OLAP operations can be applied to dimensions defined in the geographical space (spatial drilling or spatial slicing). This kind of tool is called SOLAP (Spatial OLAP). SOLAP tools currently available on the market all suffer from the same deficiency: they are unable to represent spatial dimensions (X, Y) in a continuous way. This representation is nevertheless essential for the management of spatially continuous phenomena (temperature, pollution, etc.) but also for visualizing spatially discrete events (product sales, crimes, etc.) while minimizing the Modifiable Areal Unit Problem (MAUP). This kind of visualization is used especially by the police to predict the location of future crimes through hotspot maps which are generated by the Kernel Density Estimation (KDE) method. In the field of GIS, raster data (as opposed to vector data) enable effective representation of spatial continuity through digital georeferenced grids. Whereas current SOLAP tools only consider vector data, our research uses the raster model to integrate spatial continuity into the multidimensional structure of a data warehouse feeding a SOLAP ("raster SOLAP"). Despite its underutilization in the SOLAP literature, the raster model has many similarities with a particular kind of data cube: the MOLAP cube (Multidimensional OLAP). Like a satellite image (raster) representing the two planimetric spatial dimensions and one "spectral band" dimension, a MOLAP cube is a three dimensional array whose cells’ coordinates (similar to raster pixels) enable an efficient indexation of dimensions’ members (describing the analyzed facts). In a first original model that we call "raster cube" we define the bases for a three-dimensional raster SOLAP, starting from the definition of a MOLAP cube. Unlike vector SOLAP - where spatiality is attached to a semantic dimension through pointers to geometries - our model directly integrates spatial dimensions (X, Y) in the multidimensional structure of the data warehouse. With this original feature, any geographical entity (country, building, road, etc.) can be imported on the fly as a member in the analysis of the user, which is hardly possible with conventional vector SOLAP tools. An extension of this SOLAP model, called "raster hypercube", is then developed by entrusting the management of extra non-spatial dimensions to a relational database management system (Relational OLAP or ROLAP). The raster hypercube is then populated by KDE raster fields representing crime densities, which are defined in a continuous space (raster dimensions) through time and crime types (ROLAP dimensions). Our model is able to combine the production of hotspot maps at different scales of analysis with SOLAP navigation operations: slicing on spatial or non-spatial members, and drilling into the hierarchy of spatial or non-spatial dimensions. Our raster hypercube model is validated by an operating prototype which is based on open source tools only. Several datasets are integrated through KDE fields, including crime data from London and Seattle. At the end of our work, the results of a comparative study between raster SOLAP and vector SOLAP demonstrate that hybrid vector/raster SOLAP architectures present the same interest for spatial data as hybrid ROLAP/MOLAP architectures do for purely semantic data (management of detailed hypercubes [less ▲]

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See detailExploiting Interspecific Genetic Variability for Improving Common bean for higher productivity on soils presenting biotic and abiotic stresses
Butare, Louis ULg

Doctoral thesis (2015)

Biotic and abiotic stresses often occur in the same field of rural poor farmer households in tropical countries resulting in heavy losses of common bean yields. To improve resistance of common beans ... [more ▼]

Biotic and abiotic stresses often occur in the same field of rural poor farmer households in tropical countries resulting in heavy losses of common bean yields. To improve resistance of common beans, sensitive Phaseolus vulgaris (SER16) was crossed to resistant P. coccineus (G35346-3Q) to create 94 F5:6 recombinant inbred lines (RILs) of the pedigree SER16♀ x (SER16♀ x G35346-3Q♂). The objectives of this study were to (i) identify potential parents for resistance to Al, drought and Fusarium root rot among 11 bean genotypes, (ii) to evaluate 94 F5:6 Recombinant Inbred Lines (RILs) of the cross SER 16♀ x (SER 16♀ x G35346-3Q♂) both for their resistance to Al and /or drought, (iii) to evaluate RILs for resistance to Fusarium root rot, and (iv) to identify QTL for resistance to these stresses. RILs were characterized in greenhouse for resistance to Al using a hydroponic screening employing a nutrient solution with or without 20 μM Al , to Al-toxic acid soil with high Al (HAl) and low Al (LAl) saturation, to terminal drought simulation with and without progressive soil drying, to combined stresses of Al and terminal drought in 80 cm long soil cylinder system, and to Fusarium root rot using inoculated perlite soil and sand (2:1). Two field studies were also carried on in Colombia under rainfed and irrigated conditions in Palmira, and high Al saturated acid soil in Santander of Quilichao. Our studies confirmed the superiority in Al response of Andean common beans in greenhouse trials compared to Middle American type for several root traits. Each screening method of our Al greenhouse experiments permitted an evaluation of different aspects of root traits. The two parents were virtually equal for tap root elongation rate at 24 h in the 20 μM Al treatment at about 1.4 mm h-1 while progenies ranged from less than 1-1.75 mm h-1. The correlation between leaf area and total root length was highly significant under high Al saturation (r = 0.70***) for HAl-acid soil. Two genotypes (ALB88 and ALB 91) emerged as strong multiple trait lines for the two abiotic stresses. Fusarium root rot induced root growth inhibition as high as 80.8% for the susceptible ALB 5, while resistant RILs (ALB45, ALB41, ALB126, ALB84, ALB49, ALB34, ALB88 and ALB85) didn`t show any inhibition . Seed yield under drought stress conditions was positively associated to 100-seed weight both under irrigated field (r = 0.28**) and rainfed field (r = 0.36***), and negatively associated to days to maturity (DTM) (r = - 0.36***) in field evaluation in Al-toxic acid soil in Quilichao (Colombia). QTLs for important traits including root characteristics under high Al , grain yield and yield components for drought and high Al saturation soil were identified. The use of both soil and hydroponic system, and field could contribute to evaluation of breeding materials to identify genotypes that combine Al resistance with acid soil tolerance, drought and root rot tolerance. [less ▲]

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See detailPerturbations de l'épissage des ARN pré-messagers par les agents chimiothérapeutiques: mécanismes d'action du cisplatine et impact sur la mortalité des cellules cancéreuses
Gabriel, Maude ULg

Doctoral thesis (2015)

L’épissage alternatif est un processus qui concerne plus de 90% des pré-ARN messagers et qui contribue largement à la diversité protéique. Il est régulé par une série de facteurs d’épissage qui se lient ... [more ▼]

L’épissage alternatif est un processus qui concerne plus de 90% des pré-ARN messagers et qui contribue largement à la diversité protéique. Il est régulé par une série de facteurs d’épissage qui se lient sur des séquences situées sur les transcrits primaires. L’activité de ces facteurs d’épissage est régulée, entre autres, par divers signaux externes et voies de signalisation.  Les agents chimiothérapeutiques peuvent altérer la régulation de l’épissage et, ainsi, modifier la séquence d’un grand nombre d’ARN messagers et, éventuellement, la fonction des protéines qui en résultent. Cependant, l’implication de ces mécanismes dans la thérapie anticancéreuse demeure mal connue en termes d’efficacité thérapeutique, de diagnostic, de pronostic, de développement de résistances aux traitements et d’induction d’effets secondaires. L’objectif principal de cette étude est d’évaluer si la régulation de l’épissage par le cisplatine est critique pour son activité anticancéreuse. L’analyse du transcriptome de cellules mammaires cancéreuses traitées avec du cisplatine a permis d’identifier de nombreuses altérations d’épissage induites par la chimiothérapie. Parmi les 700 évènements observés, un grand nombre touche des transcrits impliqués dans le cycle cellulaire et dans la régulation de l’épissage lui-même.   Bien que le cisplatine induise des dommages au niveau de l’ADN, nous avons exclu la participation des membres de la voie des dommages à l’ADN, tels que ATM, ATR, DNA-PK et p53, dans les altérations d’épissage induites par le cisplatine. Les PI3K de class I (p110) et la voie MEK/ERK sont , en revanche, requises.  L’utilisation d’une banque de plus de 50 siRNA ciblant des protéines se liant à l’ARN, en particulier des facteurs d’épissage, nous a permis d’évaluer l’implication de ces facteurs dans les modifications d’épissage observées après le traitement au cisplatine. Il est apparu que la réduction de l’expression de certains facteurs dont SF3A1, RBM39, U2AF1 et snRNP70 mime les effets du cisplatine. A l’inverse, l’inhibition de SRSF4 réprime ces effets.  Par co-immunoprécipitation, nous avons observé un lien physique entre le facteur de transcription c-Jun et les facteurs d’épissage SF3A1 et RBM39. Alors que cette liaison ne semble pas être affectée par le cisplatine, des modifications du statut de phosphorylation de c-Jun ont été observées après traitement au cisplatine. La déplétion de c-Jun et l’inhibition d’AP-1 corrigent en partie l’effet du cisplatine sur l’épissage, suggérant leur implication dans le processus.   Finalement, nous avons montré que la déplétion en SRSF4 réduit la mortalité cellulaire induite par le cisplatine, alors que la déplétion en SF3A1 et RBM39 l’augmente. Ces résultats montrent une corrélation entre épissage et mort cellulaire et suggèrent que la modulation de l’épissage pourrait être utilisée comme thérapie adjuvante afin d’augmenter l’efficacité de la chimiothérapie.   [less ▲]

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See detailBilan bactériologique des mammites dans les troupeaux Zébu Azawak à la station expérimentale sahélienne de Toukounous (Niger) et épidémiologie moléculaire des Staphylococcus aureus isolés entre 2009 et 2012
Issa Ibrahim, Abdoulkarim ULg

Doctoral thesis (2015)

L’élevage est la seconde activité principale après l’agriculture au Niger. Cependant, ce secteur est confronté à d’énormes problèmes, notamment la faible productivité des animaux, le faible investissement ... [more ▼]

L’élevage est la seconde activité principale après l’agriculture au Niger. Cependant, ce secteur est confronté à d’énormes problèmes, notamment la faible productivité des animaux, le faible investissement, des problèmes d’alimentation et d’accès aux points d’eau, et divers problèmes sanitaires récurrents. Depuis l’indépendance du pays en 1960, plusieurs politiques ont été mises en œuvre pour améliorer la productivité des espèces et races domestiques locales. C’est ainsi que, la station expérimentale sahélienne de Toukounous a vu le jour, avec comme objectifs la sélection et la diffusion de la race Zébu Azawak auprès des producteurs ruraux. Les efforts de sélection ont abouti à l’obtention d’un animal standard bien adapté au contexte sahélien avec un niveau de production en lait acceptable. Le bétail laitier à travers le monde souffre énormément des problèmes sanitaires liés aux infections de la glande mammaire. La situation est la même à Toukounous malgré la proximité de services vétérinaires et para-vétérinaires. Cependant, au Niger de manière générale, les données sur les mammites sont rares et très peu de publications scientifiques sont disponibles. Une des possibles explications est la prévalence élevée de mammites sub-cliniques, mais faible de mammites cliniques. La présente étude est dès lors centrée sur les problèmes de mammites au sein de la station sahélienne expérimentale de Toukounous afin d’identifier : (i) les vaches souffrant de mammites cliniques et/ou subcliniques ; (ii) les principales bactéries pathogènes responsables ; et (iii) les virulotypes et profils de résistance aux antibiotiques des souches de Staphylococcus (S.) aureus isolées ; et afin de démontrer l’impact positif de l’application de mesures simples d’hygiène lors de la traite manuelle sur la prévalence de vaches avec mammite. De 2009 à 2012, l’ensemble des vaches en lactation des trois troupeaux de la station, à savoir « élites », « non-élites » et « primipares » ont été testées avec le « California Mastitis Test » (CMT). Ensuite, le lait de tous les quartiers des vaches ayant réagi positivement au test CMT a été prélevé pour réaliser des analyses bactériologiques au Niger. Les espèces bactériennes pré-identifiées au Niger ont ensuite été importées en Belgique (ULg-FMV) afin de procéder à une identification complète par des galeries API®. Les souches confirmées de S. aureus ont par la suite été étudiées pour leurs virulotypes (i) phénotypiquement pour la production de biofilm par mesure de la densité optique après croissance en milieu liquide en plaque de microtitration et pour la synthèse d’une capsule par un test ELISA ; et (ii) génétiquement par PCR ciblant des gènes codant pour différentes propriétés de virulence (adhésines, leucotoxines, entérotoxines, biofilm, et capsule) ; ainsi que pour leurs profils de résistance aux antibiotiques par le test de diffusion en gélose, ou antibiogramme. Ces mêmes souches ont été comparées par leurs empreintes génétiques après « Pulsed Field Gel Electrophoresis » (PFGE), ou pulsotypes, pour en étudier la clonalité au cours des 4 années de l’enquête et dans les 3 troupeaux. Enfin, l’impact de mesures d’hygiène (lavage et désinfection du pis, des trayons et des mains des trayeurs avant et/ou après chaque traite) a été évalué en 2011 et en 2012, en comparant la prévalence de vaches positives au test CMT et l’identité des bactéries isolées en présence ou en absence de ces mesures. Au cours de la première étude en 2009 sur la prévalence des vaches positives au test CMT et l’identité des bactéries mammopathogènes, 104 des 265 vaches (39%) testées dans l’ensemble des 3 troupeaux étaient positives au test CMT, bien qu’aucune mammite clinique n’ait été diagnostiquée. Les analyses bactériologiques ont identifié 55 souches bactériennes: la moitié (51%) appartient au genre Staphylococcus, essentiellement à l’espèce S. aureus (42%). Les autres bactéries identifiées appartiennent à la famille des Enterobacteriaceae (26%) et aux genres Enterococcus (13%), Bacillus (9%) et Acinetobacter (2%). Des résultats similaires ont été obtenus en 2010, 2011 et 2012, bien que les pourcentages respectifs puissent varier selon l’année et le troupeau. Les résultats des tests phénotypiques et génétiques du virulotypage (études 1 et 3) des 122 souches de S. aureus isolées de 2009 à 2012 dans les trois troupeaux n’ont permis d’effectuer aucun regroupement. Par contre, les résultats des empreintes génétiques par PFGE sur ces mêmes souches ont montré qu’elles appartiennent à 16 pulsotypes différents, dont trois sont plus fréquents, A (33%), D (23%) et B (21%). Ces différents pulsotypes se distinguent, dans une certaine mesure, par la présence plus fréquentes des gènes icaA, spa et cap5H dans les souches des pulsotypes A et B ; des gènes cap8H, seg, sei et seb dans celles du pulsotype D ; et du gène luks-PV dans celles des pulsotypes B et D. Pour ce qui concerne les antibiogrammes des mêmes 122 souches (études 1 et 2 + résultats non publiés), des pourcentages élevés de souches résistantes de S. aureus, particulièrement aux -lactamines, ont été relevés. Ainsi, 41% des souches testées étaient résistantes à la pénicilline et 7%, à l’oxacilline. Mais, aucune souche résistante à la méticilline (SARM) ne possède le gène mecA. Les pourcentages de souches résistantes atteignaient 11% pour la tétracycline et la gentamicine, mais restaient inférieurs à 5% pour la clindamycine, l’association trimétoprime-sulfaméthoxazole et l’enrofloxacine. Pour la 4ème étude en 2011 et 2012, les mesures d’hygiène ont été appliquées pendant 6 mois : lavage du pis avant la traite, trempage des trayons avec de la chlorhexidine après la traite, et lavage et désinfection des mains des trayeurs avec une solution antiseptique à base d’hypochlorite de sodium. L’application de ces mesures a diminué de manière statistiquement significative les pourcentages de vaches positives au test CMT en comparaison avec les résultats dans les troupeaux et au cours des années sans application de ces mêmes mesures d’hygiène. En 2012, par exemple, les pourcentages de vaches positives au CMT dans les troupeaux « élite » et « non-élite » ont diminué de 65% et 62%, à 44% et 41% après trois mois d’application, puis à 20% et 24% après 6 mois d’application, respectivement. Par contre, ces mesures d’hygiène n’ont eu aucun effet statistiquement significatif sur les pourcentages relatifs des différents pathogènes identifiés. En conclusion, les mammites bovines sévissent essentiellement sous forme sub-clinique à la station sahélienne de Toukounous. Le genre Staphylococcus et l’espèce S. aureus sont les bactéries mammopathogènes les plus fréquemment identifiées. Les souches de S. aureus appartiennent à différents virulotypes et pulsotypes, bien que trois de ces derniers soient plus fréquents dans les trois troupeaux et au cours des quatre années de l’étude. Ces mêmes souches présentent différents profils de résistance aux antibiotiques, avec près de la moitié d’entre elles résistantes à des membres de la famille de -lactames. Enfin, l’application de mesures d’hygiène (lavage et désinfection du pis, des trayons et des mains des trayeurs) avant et/ou après la traite manuelle permet de réduire la prévalence des vaches positives au test CMT de manière statistiquement significative, mais n’a pas d’influence sur les fréquences relatives des bactéries pathogènes identifiées dans les laits. [less ▲]

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See detailWild boar movement ecology across scales: Insights from a population expanding into agroecosystems of Southern Belgium
Morelle, Kevin ULg

Doctoral thesis (2015)

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until ... [more ▼]

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until recently, ungulates have progressively adapted to these modi cations and are now able to cope with human-shaped environments, consequently their number and range have greatly and worryingly increased. More particularly, among ungulates species, the wild boar Sus scrofa raises important concerns due to its environmental, economic and social impacts on modern societies. Understanding the ecology of ungulates species and their ability to survive within highly dynamic and seasonal ecosystems, such as agricultural environment, is thus necessary to better mitigate their negative impacts and to sustainably manage growing and expanding populations. Although only recently studied, movement ecology of animal is an important species trait that allows animal to adapt to rapid environmental changes. Considering movement as the resulting interaction of the animal’s internal state, navigation and motion capacity as well as of the e ect of the surrounding environment (“external factors”), provides a clear conceptual framework enabling to study patterns, mechanisms and processes, such as coping with land-use changes. In this thesis, we study the case of an expanding wild boar population in Southern Belgium and consider the movement ecology of the species to understand how wild boar colonize and ourish in agroecosystems. More speci cally, the thesis aims at i) reviewing quantitatively and qualitatively the scienti c literature about wild boar movement ecology, and ii) analyzing the spatial response of wild boar to agroecosystems in terms of movement and habitat selection across three spatial and temporal scales. The literature review highlights that wild boar is the least studied ungulates species in terms of movement ecology.We suggest that this is likely due i) to the relative complexity of tting tracking devices to this species, and ii) to its generalist diet making the species not suitable to test foraging hypotheses. Among existing studies, a large part focuses on the role of external factors (e.g. hunting, landscape features) on movement while others components of the movement ecology framework (internal state, navigation and motion capacity) remain poorly studied. However, when assuming behavioral similarity between wild and domestic boars, experimental studies on captive animals show how wild boar can develop complex movement strategies by using their highly developed cognitive and sensory abilities, and spatial memory. The spatio-temporal analysis suggests a scale-speci c response of wild boar to agricultural habitat. At the intermediate scale (landscape, seasonal), wild boar uses seasonal habitat shift strategies towards agricultural areas, while at broader scale (regional, decades), wild boar avoids this habitat, preferring the forest habitat to spread and extend its occupancy range. This results in a contradiction with our preliminary hypothesis that increased area of cultivations providing cover (maize, rapeseed, cereals) facilitates wild boar population expansion. Furthermore, we show that besides the use of forest habitat, high population density is a major driving factor of the colonization of agroecosystems by wild boar. The ne-scale analysis (home range, daily), highlights the large variety of spatial behaviors (area restricted search, central place foraging, nomadism, dispersing) wild boar is able to use to cope with heterogeneous environments. In terms of management of the species, the results of this thesis suggest that it is required to lower the population density in order to limit the population spread into agroecosystems, not only at the margin of expansion but all over the species’ range. Furthermore, we recommend developing more exible control strategies taking into account both the spatial abilities of the species and the complexity and dynamics of the environment. For example, the creation of a seasonal landscape of fear could be promoted, i.e. reducing attractivity of agricultural lands by increasing risk sensation (e.g. hunting with dogs all along the growing season). However, in our opinion, the success of any management strategy requires rst to tackle the issue of the decreasing number of hunters observed in large part of Europe and to improve communication among the di erent stakeholders (hunting associations, farmers, public administration). Indeed, while ungulates have progressively adapted to human-induced changes, the capacity of humans to adapt to this new human-ungulate relation is questionable. [less ▲]

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See detailEtude du potentiel des sous produits de la filière vinicole pour des applications à haute valeur ajoutée
Berchem, Thomas ULg

Master's dissertation (2015)

Nowadays, there is no longer any doubt about the future fossil fuels rarefaction. It is necessary to find more sustainable ways to produce everyday consumer products faced to an increasing population. Bio ... [more ▼]

Nowadays, there is no longer any doubt about the future fossil fuels rarefaction. It is necessary to find more sustainable ways to produce everyday consumer products faced to an increasing population. Bio-based chemistry and bio-refining are alternative solutions deserving a particular attention. The large amount of green waste produced all around the world represents energy and chemical resources with an under-exploited potential. Wine-making byproducts come from grape growing which is one of the largest crop around world. It seems to be an interesting source of bio-based molecules but, despite this potential, these byproducts are untapped. Their uses are limited to poor value added applications like composting, agricultural spreading or bioethanol. This work focuses on the high value added valorization possibilities of the wine-making byproducts. It takes part in the current trend of using natural bioactive molecules in pharmaceutical, parapharmaceutical or food industry. This study is built around three main objectives: a characterization of the raw material and the development of a method to extract polyphenols. The results shown in this work tend to indicate a high valorization potential of grape pomace thank to the identification of interesting compounds like bioactive molecules and especially polyphenols as well as high concentrations of other molecules of which the valorization potential from wine-making byproducts needs to be explored. [less ▲]

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See detailCaractérisation et étude du potentiel de valorisation des polyphénols de miels monofloraux
Istasse, Thibaut ULg

Master's dissertation (2015)

Honey is a natural sweet substance mainly produced by Apis mellifera L. from flowers nectar or honeydew. It is consumed by humans and used as sweetening agent since ancient times. Nowadays, its main ... [more ▼]

Honey is a natural sweet substance mainly produced by Apis mellifera L. from flowers nectar or honeydew. It is consumed by humans and used as sweetening agent since ancient times. Nowadays, its main valorization is in the food sector. Besides its sweetness, honey also has other interesting properties like an antibacterial action. The origins of this antibacterial action are manifold because although honey contains mainly sugars, it is nonetheless a very complex mixture comprising more than one hundred different components. Factors usually involved in honey antibacterial effect are hydrogen peroxide, the high concentration in sugars, the acidic pH, antimicrobial peptides secreted by bees and polyphenols which are secondary metabolites from plants visited by the bees. Among these factors, polyphenols are of particular interest because they represent a market of hundreds of millions of dollars in the world and exhibit different biological activities: antioxidants, antibacterial, anticancer, antifungal, anti-inflammatory, etc… These observations lead to a question: could honey polyphenols be extracted for high value-added applications? The purpose of this work is to give a beginning of answer. That’s why an extraction method for honey polyphenols was developed. These compounds were sought in six different honey samples: acacia, chestnut, eucalyptus, thyme, sunflower and wild carrot honeys. After the extraction, samples were analyzed by high performance liquid chromatography coupled with UV detection and mass spectrometry. Several polyphenols were identified and quantified in honeys. If the extraction method isn’t recommended at industrial level at this stage of the project, it can, however, be used for analytical purposes. Further development of the method could allow to link honeys to their floral sources. [less ▲]

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See detailDétection des sauts de cycles en mode multi-fréquence pour le système Galileo
Van de Vyvere, Laura ULg

Master's dissertation (2015)

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See detailTime-domain simulation of large electric power systems using domain-decomposition and parallel processing methods
Aristidou, Petros ULg

Doctoral thesis (2015)

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. Over the last decades, they have become indispensable to anyone involved in power system ... [more ▼]

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. Over the last decades, they have become indispensable to anyone involved in power system planning, control, operation, and security. Transmission system operators depend on fast and accurate dynamic simulations to train their personnel, analyze large sets of scenarios, assess the security of the network in real-time, and schedule the day ahead operation. In addition, those designing future power systems depend on dynamic simulations to evaluate proposed reinforcements, whether these involve adding new transmission lines, increasing renewable energy sources, or implementing new control schemes. Even though almost all computers are now parallel, power system dynamic simulators are still based on monolithic, circuit-based, single-process algorithms. This is mainly due to legacy code, written in the 80's, that is still today in the core of the most important commercial tools and does not allow them to fully exploit the parallel computational resources of modern computers. In this thesis, two parallel algorithms belonging to the family of Domain Decomposition Methods are developed to tackle the computational complexity of power system dynamic simulations. The first proposed algorithm is focused on accelerating the dynamic simulation of large interconnected systems; while, the second algorithm aims at accelerating dynamic simulations of large combined transmission and distribution systems. Both proposed algorithms employ non-overlapping decomposition schemes to partition the power system model and expose parallelism. Then, “divide-and-conquer” techniques are utilized and adapted to exploit this parallelism. These algorithms allow the full usage of parallel processing resources available in modern, inexpensive, multi-core machines to accelerate the dynamic simulations. In addition, some numerical acceleration techniques are proposed to further speed-up the parallel simulations with little or no impact on accuracy. All the techniques proposed and developed in this thesis have been thoroughly tested on academic systems, a large real-life system, and a realistic system representative of the continental European synchronous grid. The investigations were performed on a large multi-core machine, set up for the needs of this work, as well as on two multi-core laptops computers. [less ▲]

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See detailHölder Continuity and Wavelets
Simons, Laurent ULg

Doctoral thesis (2015)

There exist a lot of continuous nowhere differentiable functions, but these functions do not have the same irregularity. Hölder continuity, and more precisely Hölder exponent, allow to quantify this ... [more ▼]

There exist a lot of continuous nowhere differentiable functions, but these functions do not have the same irregularity. Hölder continuity, and more precisely Hölder exponent, allow to quantify this irregularity. If the Hölder exponent of a function takes several values, the function is said multifractal. In the first part of this thesis, we study in details the regularity and the multifractality of some functions: the Darboux function, the Cantor bijection and a generalization of the Riemann function. The theory of wavelets notably provides a tool to investigate the Hölder continuity of a function. Wavelets also take part in other contexts. In the second part of this thesis, we consider a nonstationary version of the classical theory of wavelets. More precisely, we study the nonstationary orthonormal bases of wavelets and their construction from a nonstationary multiresolution analysis. We also present the nonstationary continuous wavelet transform. For some irregular functions, it is difficult to determine its Hölder exponent at each point. In order to get some information about this one, new function spaces based on wavelet leaders have been introduced. In the third and last part of this thesis, we present these new spaces and their first properties. We also define a natural topology on them and we study some properties. [less ▲]

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See detailLearning Artificial Intelligence in Large-Scale Video Games: A First Case Study with Hearthstone: Heroes of Warcraft
Taralla, David ULg

Master's dissertation (2015)

Over the past twenty years, video games have become more and more complex thanks to the emergence of new computing technologies. The challenges players face now involve the simultaneous consideration of ... [more ▼]

Over the past twenty years, video games have become more and more complex thanks to the emergence of new computing technologies. The challenges players face now involve the simultaneous consideration of many game environment variables — they usually wander in rich 3D environments and have the choice to take numerous actions at any time, and taking an action has combinatorial consequences. However, the artificial intelligence (AI) featured in those games is often not complex enough to feel natural (human). Today's AI is still most of the time hard-coded, but as the game environments become increasingly complex, this task becomes exponentially difficult. To circumvent this issue and come with rich autonomous agents in large-scale video games, many research works already tried and succeeded in making video game AI learn instead of being taught. This thesis does its bit towards this goal. In this work, supervised learning classification based on extremely randomized trees is attempted as a solution to the problem of selecting an action amongst the set of available ones in a given state. In particular, we place ourselves in the context where no assumptions are made on the kind of actions available and where action simulations are not possible to find out what consequences these have on the game. This approach is tested on the collectible card game Hearthstone: HoW, for which an easily-extensible simulator was built. Encouraging results were obtained when facing Nora, the resulting Mage agent, against random and scripted (medium-level) Mage players. Furthermore, besides quantitative results, a qualitative experiment showed that the agent successfully learned to exhibit a board control behavior without having been explicitly taught to do so. [less ▲]

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See detailEnquêter auprès des sourds. Implications éthiques, méthodologiques et statistiques de l’adaptation d’enquêtes d’opinion au public sourd.
Fontaine, Sébastien ULg

Doctoral thesis (2015)

For technical and logistical reasons, disabled people (and especially deaf people) are excluded from opinion surveys. This leads to the situation that deaf people remain unrepresented in the statistical ... [more ▼]

For technical and logistical reasons, disabled people (and especially deaf people) are excluded from opinion surveys. This leads to the situation that deaf people remain unrepresented in the statistical tendencies emerging from such quantitative opinion surveys. This observation is at the heart of the research presented in this work. This thesis consists of four chapters, each one tackling specific aspects of the implications of this lack of representation of deaf people in opinion surveys. The first chapter gives a short description of the situation of deaf people, from a sociological point of view. The second chapter discusses the moral and ethical issues raised by the lack of representation of deaf people in opinion surveys, in a more philosophical perspective. In the third chapter, we present new adapted methods making it possible to conduct opinion surveys among deaf people. Thanks to a new type of electronic questionnaire including sign language videos, we more specifically show how deaf people can be surveyed for different purposes. On the basis of these new techniques, the final chapter offers a commented statistical analysis of the deaf people situation in French-speaking Belgium. [less ▲]

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See detailDiscrete Element Method Modeling of Ball Mills - Liner Wear Evolution
Boemer, Dominik ULg

Master's dissertation (2015)

Ball mills, i.e. rotating cylindrical drums filled with a feed material and metal balls, also known as the charge, are a major category of grinding devices in mineral processing and cement production ... [more ▼]

Ball mills, i.e. rotating cylindrical drums filled with a feed material and metal balls, also known as the charge, are a major category of grinding devices in mineral processing and cement production. Since the grinding process is excessively energy-intensive and aggressive in terms of wear, a profiled and wear-resistant liner is installed in the mill to transfer energy to the grinding charge more efficiently and to protect the mill shell. Because of the harsh environment inside of the mill and the relatively long lifespan of its liner, the optimization of the liner by the classical way, i.e. experimental testing, is a difficult and slow process. In this thesis, a procedure for predicting the charge motion and the power draw of a ball mill based on the discrete element method (DEM) is calibrated and validated by means of photographs of the charge, and power draw measurements of a 1:5-scale laboratory mill, which were kindly provided by the company Magotteaux International S.A. . This computational method essentially renders future experimental testing unnecessary with respect to these characteristics. Based on this first method, a generic process for predicting the wear distribution and the progressive shape evolution of liner surfaces is developed and validated by the wear profiles of the shell liner in the first chamber of a 5.8 m diameter cement mill monitored during a decade by Magotteaux International S.A. . The energy dissipated by tangential damping defined by the linear spring-slider-damper DEM contact law was found to be the best fitting wear model with respect to the real wear data. The progressive update of the liner geometry by a multi-step procedure delivers relatively accurate results for liners without axial height variation while further investigations are still required for almost fully variable geometries. Nevertheless, detailed phenomena, like the creation of grooves in the liner, were for the first time numerically modeled in this thesis. [less ▲]

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See detailModel polyQ proteins based on the beta-lactamase BlaP: How non-polyQ regions influence the polyQ length-dependent aggregation process
Huynen, Céline ULg

Doctoral thesis (2015)

Neurodegenerative amyloid diseases are fatal disorders representing an important human health and economic burden. Amongst them, nine disorders are classified as polyglutamine (polyQ) diseases, for which ... [more ▼]

Neurodegenerative amyloid diseases are fatal disorders representing an important human health and economic burden. Amongst them, nine disorders are classified as polyglutamine (polyQ) diseases, for which no treatment is yet available. They are all characterized by the pathological expansion of a poly(CAG) sequence, above a specific threshold, within the coding sequence of nine unrelated genes, translated in nine polyQ proteins. The polyQ expansion, the only common point, is the critical determinant for polyQ disease development by triggering protein aggregation into amyloid fibrils. More recent studies however indicate that the protein context modulates the polyQ-induced aggregation process and the disease phenotype. The objectives of my thesis are to deeper investigate the molecular determinants of the complex interplay between the propensity of the polyQ tract to trigger protein aggregation and the modulating role of non-polyQ regions in order to allow the identification of strategies to interfere with the pathological aggregation process. For that purpose, model polyQ proteins, referred to as BlaP-polyQ chimeras, based on the β-lactamase BlaP and polyQ sequences (23 – 79Q) inserted at two positions (197, in between or not unstructured peptides, or 216), are used and their aggregation properties are characterized under several conditions. We first observe that the polyQ length is determinant for BlaP-polyQ chimera aggregation. Indeed, there is a Q-threshold for the aggregation into amyloid fibrils and for fibril elongation. Above this threshold, the aggregation in solution and the elongation rate increase with the length of the polyQ tract, with an exponential rise-to-maximum and a linear regression, respectively, independently of the conformation of the BlaP moiety, and of the position of the polyQ tract within BlaP. Longer polyQ tracts are likely to have a larger conformational flexibility allowing them to more easily adopt an amyloid-aggregation prone conformation. However, the Q-threshold for fibril elongation is much lower than for fibril formation in solution: the polyQ tract requires a larger conformational flexibility to nucleate the formation of fibrils than to elongate them. Secondly, the Q-threshold for fibril formation is lower once the BlaP moiety is unfolded, and BlaP-polyQ chimeras aggregate faster into amyloid fibrils under conditions favoring the unfolding of the BlaP moiety. The native structure of BlaP is likely to impose conformational constraints to moderate and long polyQ tracts that block and decrease, respectively, their propensity to form fibrils. The effects of constraints decrease with the polyQ length. Thirdly, BlaP chimeras with the polyQ tract in position 216 have an increased propensity to trigger the nucleation and the elongation of amyloid fibrils compared to chimeras with the polyQ in position 197. Advanced studies confirm that the propensity of the polyQ tract to aggregate into amyloid fibrils is linked to the conformational flexibility of the polyQ tract, which depends on (i) the polyQ length, (ii) the location of the polyQ tract within BlaP, i.e., a terminal location or embedded within a protein domain, and (iii) the structural properties of the polyQ flanking regions. Finally, we observe that the whole region flanking the polyQ tract in position 197 at its N-terminus has an anti-aggregating property that fully counterbalances the pro-aggregating property of that flanking at the C-terminus. The former imposes strong conformational constraints to the polyQ tract that reduce its conformational flexibility and hence its aggregation propensity. Moreover, these regions are likely to differently affect the solubility of the polyQ protein and hence the driving force for insoluble aggregation. Altogether, our data also suggest that BlaP chimeras aggregate via the commonly described nucleation-dependent polymerization mechanism during which the aggregation is first triggered by polyQ-polyQ interactions, and then a subsequent slight reorganization of the BlaP moiety is required for conversion of aggregates into amyloid fibrils. Based on these results, we should allow the development of therapeutic strategies, targeting specifically the molecular features of the complex interplay between the polyQ and non-polyQ regions during the nucleation and/or elongation of the pathological aggregation of polyQ proteins. [less ▲]

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See detailDevelopment of a new design method for the cross-section capacity of steel hollow sections
Nseir, Joanna ULg

Doctoral thesis (2015)

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through ... [more ▼]

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through a classification system consisting on rules depending on the cross-section dimensions. For example, in EN 1993-1-1, classes are defined spanning from stocky sections (class 1) able to develop their full plastic capacity, to slender sections (class 4) for which the effective properties are used with the use of the effective width method (EWM). However, for cold-formed steel sections, characterized by a non-linear material law, the cross-section resistance can go beyond its plastic capacity due to strain hardening effects. Moreover, with the emergence of high strength steel (i.e. cross-sections falling into class 4) and more complex cross-section shapes, the effective width method is becoming too complicated. Many other reasons and discrepancies are making the cross-section classification too complex and inconsistent. The Overall Interaction Concept (OIC) stands as a new design approach that aims at a straightforward design check of the stability and resistance of steel cross-sections. Based on the use of a generalized relative slenderness and so-called interaction curves, it can be applied to any type of cross-section, further includes potential non-linear material behaviour and covers combined loading cases. The main aim of this thesis is to develop and propose OIC interaction curves dedicated to steel hollow sections subjected to various load cases. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to investigate the cross-sectional behavior of cold-formed hot-finished and hot-rolled square, rectangular and circular sections. 57 cross-sections tests including simple and combined load cases were performed. Besides, a finite element model was developed and calibrated on the basis of the tests, and its accuracy was seen to be sufficient to subsequently undergo an extensive numerical parametric study for hot-rolled and cold-formed cross-sections, leading to over than 40 000 numerical results. Based on these computations, design proposals were made within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a validation of the proposed formulae was made through a comparison with existing approach and worked examples were presented, in order to illustrate (i) the application of the method and (ii) its benefits in comparison to application of current EC3 rules. [less ▲]

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See detailModelling of the response of a slender structure to vortex shedding in the atmospheric boundary layer
Wertz, Freddy ULg

Master's dissertation (2015)

This work is about modelling vortex induced vibrations on a 100 m height generic reinforced concrete pylon with a square cross-section and a 20 height/width ratio, vibrating in its first across-wind ... [more ▼]

This work is about modelling vortex induced vibrations on a 100 m height generic reinforced concrete pylon with a square cross-section and a 20 height/width ratio, vibrating in its first across-wind bending mode at a frequency of 0.35 Hz for a critical wind speed of 14.6 m/s. An equivalent aeroelastic model made of a copper spline modelling the dynamic behaviour and a foam blocks skin modelling the external geometry and adjusting the mass is realized. Similitude laws are discussed based on their relevance in the simulation. The model is validated through experimental modal analysis and is tested in wind tunnel uniform and boundary layer winds. 3 turbulence levels and 4 incidence angles are tested. Measured amplitudes are small (around 5 cm in full scale). The influence of turbulence is qualitatively visible in experimental results. Analytical and numerical estimation procedures are also implemented and discussed: The Eurocode norm, a harmonic load model and the spectral model of Vickery and Clark. The Eurocode approach gives the most conservative estimations and is followed by estimations from the harmonic load model having the correlation length as parameter. The spectral model gives estimations of the order of magnitude of experimental measurements in the wind tunnel for a spectral bandwidth of 0.2 and a correlation length comprised between 1 and 3 times the width of the cross-section. [less ▲]

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See detailOrigine et dynamique des populations d’arbres des forêts denses humides d’Afrique Centrale, le cas de Lophira alata Banks ex Gaertn C.F. (Ochnaceae)
Biwole, Achille ULg

Doctoral thesis (2015)

The canopy of Central African rainforests is characterized by the abundance of light-demanding trees belonging to several species, suggesting that favorable conditions for their regeneration once ... [more ▼]

The canopy of Central African rainforests is characterized by the abundance of light-demanding trees belonging to several species, suggesting that favorable conditions for their regeneration once prevailed. Today this isn’t the case in light of the demographic structure of their populations, which shows a lack of regeneration. The appearance of such species in rainforests is the result of significant and sustainable openings in the forest canopy. Such events may have occurred with climatic changes and / or large-scale anthropogenic disturbances. The risk of their populations decline is increased by the fact that most of them are timber species. This is typically the case of Lophira alata Banks ex Gaertn C.F., which is one of the most important Central African trees harvested, and is considered vulnerable by the IUCN. In the current context where the preservation of the biodiversity and the integrity of the forest cover is a major concern, the present PhD aims to understand the history and ecological requirements of L. alata in order to propose the sustainable management strategies. The history of L. alata has been studied using an approach integrating both anthracology and archeology. We found a large body of evidences (pottery fragments, palm nuts and charcoal) in the forests soil of southern Cameroon indicating human occupation and widespread fires over two periods : 2200 - 1500 years BP, and around 300 years BP. The age of the most recent events coincides with the probable age of the tallest specimens of L. alata. To determine the light requirements of the species and to better define its regeneration strategy, a quantitative study on the guild of juveniles was conducted for two years. The results show that L. alata has both the characteristics of a pioneer species and those of a non-pioneer species. Indeed, at low irradiances (1% of full sunlight), the plants mortality rate was very low and their biomass showed no signs of decline, a behavior observed in all non-pioneer species. By contrast, the response of leaf traits, patterns of biomass allocation, and the maximum growth of plants in the intermediate (23-43% of the relative irradiance) and high (100%) irradiance levels, according to the population origins, are typical of all pioneer species. These results emphasize the importance of the population origins when studying the response to light and the need to define a more encompassing classification system. In terms of the dynamics of mature populations, environmental conditions affect the diameter growth of trees, with better growth being realized in the evergreen forest. Nevertheless, even under these favorable conditions, simulations of the exploitable stocks and their recovery rates indicated a significant decline during the first three cutting cycles, which could lead to a decline in economic activity associated with this species. Our results allowed us to suggest a set of recommendations for the sustainable management of L. alata. [less ▲]

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See detailL'activité de la NADPH oxydase : une nouvelle cible pour la curcumine ?
Derochette, Sandrine ULg

Doctoral thesis (2015)

La NADPH oxydase (Nox2) des neutrophiles (PMNs) est une enzyme multi-protéique responsable de la production d'espèce activées de l'oxygène (ROS) pour la destruction des pathogènes. L'activation excessive ... [more ▼]

La NADPH oxydase (Nox2) des neutrophiles (PMNs) est une enzyme multi-protéique responsable de la production d'espèce activées de l'oxygène (ROS) pour la destruction des pathogènes. L'activation excessive des PMNs est souvent associée à des pathologies mortelles chez le cheval, faisant de l'activité de la Nox2 une cible thérapeutique privilégiée. Le premier but de ce travail, a été de développer une méthode appelée "cell-free system" (CSF) pour mesurer l'activité in vitro de la Nox2 équine. Un inconvénient de cette technique sont les interférences possibles entre les inhibiteurs et la sonde utilisée pour la mesure de l'activité. Sur base de notre CFS, nous avons créé l'EquiNox2, un nouvel outil pharmacologique, pour étudier les interactions entre des inhibiteurs et la Nox2 et leurs effets sur l'assemblage et l'activité de l'enzyme. Cette méthode consiste en la mesure in vitro de l'activité de la Nox2 fixée sur un support solide, ce qui permet d'éliminer les inhibiteurs avant la mesure de l'activité et réduit les interférences citées pour le CFS. Le CFS et l'EquiNox2 ont été validés avec le diphénylène iodonium et le Gp91ds-tat, deux inhibiteurs connus de la Nox2 humaine. Le deuxième but de ce travail, était l'étude du NDS27, un complexe de lysinate de curcumine avec l'hydroxypropyl-β-cyclodextrine (HPβCD) sur la réponse oxydante des PMNs. Le NDS27, n'est pas toxique et est capable d'entrer et d'interagir avec les membranes des PMNs et d'inhiber l'activité de la myéloperoxydase, la Nox2 et la PKCδ (un activateur de Nox2) impliquées dans la production de ROS. Nous avons montré en CFS et EquiNox2 que le NDS27 se fixe fortement à la Nox2 pour empêcher son assemblage et que l'HPβCD, l'excipient du NDS27, en plus de solubiliser et transporter la curcumine, augmente l'action de celle-ci sur les activités de la PKC et la Nox2. L'effet modulateur du NDS27 sur l'activation de la Nox2 ouvre des perspectives thérapeutiques pour traitement des pathologies accompagnées de réactions inflammatoires excessives. [less ▲]

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See detailEtude de la sémaphorine virale codée par le gène A3 de l’herpèsvirus alcélaphin 1
Myster, Françoise

Doctoral thesis (2015)

Among gammaherpesvirus, the Macavirus genus is composed of viruses associated to malignant catarrhal fever (MCF) and other phylogenetically related viruses. MCF is a frequently fatal lymphoproliferative ... [more ▼]

Among gammaherpesvirus, the Macavirus genus is composed of viruses associated to malignant catarrhal fever (MCF) and other phylogenetically related viruses. MCF is a frequently fatal lymphoproliferative disease. Three macaviruses inducing MCF have been entirely sequenced: alcelaphine herpesvirus 2 (AlHV-2), ovine herpesvirus 2 (OvHV-2) and alcelaphine herpesvirus 1 (AlHV-1). Sheep carries OvHV-2 asymptomatically while wildebeest is infected with AlHV-1 without developing any clinical signs or lesions. Both viruses represent the most studied macaviruses. In susceptible ruminants, OvHV-2 and AlHV-1 induce the sheep-associated form and the wildebeest-derived form of MCF (WD-MCF), respectively. Economic consequences of WD-MCF are significant in sub-Saharan Africa. WD-MCF is characterized by the proliferation and infiltration of lymphoblastoid T cells surrounding blood vessels and can be considered as a model for peripheral T cell lymphoma caused by a virus. Rabbits are used as experimental model to study MCF. This species develops clinical signs and lesions that they are indistinguishable from those observed in other susceptible species. Until recently, available data on WD-MCF pathogenesis were limited to the simple description clinical signs and lesions. Recently, it was demonstrated that CD8+ T cells proliferate and that this cellular expansion is associated with a severe increase of the viral load in PBMC and lymphoid organs (Dewals et al., 2008). The cloning of the AlHV-1 genome as an infectious and pathogenic bacterial artificial chromosome (BAC) has greatly facilitated the study of individual gene of AlHV-1 (Dewals et al., 2006). Among herpesviruses, viral semaphorins can only be found in members of the Macavirus genus. OvHV 2 encodes Ov3, and AlHV-2 and AlHV-1 encode A3, both genes encoding a semaphorin homolog. Semaphorins are proteins characterized by a conserved amino-terminal domain, the SEMA domain. The roles of the semaphorins on cytoskeleton dynamics have been widely studied. Viral semaphorins could mediate immune evasion mechanisms or viral dissemination and could be involved in specific properties of macaviruses. The first study of the present thesis was dedicated to the investigation of the pathogenesis of WD-MCF and the role of latency. We investigated the distribution of the AlHV-1 infection in the lesions and demonstrated that the infiltration of CD8+ T cells in different lymphoid and non-lymphoid organs and tissues is directly associated with a non-productive viral infection. The second study focused on the A3 gene of AlHV-1 and its potential functions during WD-MCF. We showed that the A3 gene is expressed during the early phase of the viral infection and encodes a functional semaphorin that was termed AlHV-sema. AlHV-sema was able to induce cell retraction. Despite the observed independent acquisition of pox- and herpesvirus semaphorins, AlHV-sema inhibited phagocytosis by dendritic cells and migration to the draining lymph node through mechanisms similar to poxvirus semaphorin. AlHV-sema could also facilitate viral dissemination or confer immune evasion functions. Next, we investigated whether AlHV-sema could affect WD-MCF induction. We did not observe any effect of the absence of AlHV-sema expression during the development of WD-MCF after rabbit nasal infection. Macaviruses are swine and ruminant gammaherpesviruses responsible for a latent asymptomatic infection in their natural species. The development of MCF in other ruminant susceptible species is due to cross-species transmission. During evolution, the gene selection in susceptible species is certainly reduced due to the fact that these species are dead-end hosts. Thus, it is difficult to address the role of AlHV-1 specific genes in MCF as these genes have evolved in other species. Nevertheless, we brought in this work important insight for our understanding of the pathogenesis of WD-MCF and we identified AlHV-sema as a potential immunoevasion factor. DEWALS B., MYSTER F., PALMEIRA L., GILLET L., ACKERMANN M., VANDERPLASSCHEN A. Ex vivo bioluminescence detection of alcelaphine herpesvirus 1 infection during malignant catarrhal fever. J. Virol., 2011, 85, 6941-6954. MYSTER F., PALMEIRA L., SOREL O., BOUILLENNE F., DEPAUW E., SCHWARTZ-CORNIL I., VANDERPLASSCHEN A., DEWALS B.G. Viral semaphorin inhibits dendritic cell phagocytosis and migration but is not essential for gamma-herpesvirus-induced lymphoproliferation in malignant catarrhal fever. J. Virol., 2015. [less ▲]

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See detailSeagrass macrophytodetritus: a copepod hub - Species diversity, dynamics and trophic ecology of the meiofauna community in Posidonia oceanica leaf litter accumulations
Mascart, Thibaud ULg

Doctoral thesis (2015)

Macrophytodetritus is a heterogeneous mixture of detrital material that accumulates on submerged unvegetated sand patches amid vast Mediterranean Posidonia oceanica seagrass meadows. Several vagile ... [more ▼]

Macrophytodetritus is a heterogeneous mixture of detrital material that accumulates on submerged unvegetated sand patches amid vast Mediterranean Posidonia oceanica seagrass meadows. Several vagile invertebrates are present in substantial biomass and biodiversity. Among these invertebrates, meiofauna (fauna between 38µm and 1mm) is ubiquitous and seems to play a key-feature in this dynamic and patchy system. Coastal ecosystems are under the direct effect of anthropogenic disturbance and degradation. Extra research is crucially needed to understand better the dynamics of coastal vegetation, in order to have a more successful restauration of these regressing ecosystems. In this context, the main goal of this PhD research was triple: (1) characterising in situ the physico-chemistry and the composition of the macrophytodetritus accumulations in the Calvi Bay, Corsica, (2) identifying the diversity of the associated meiofauna communities, especially harpacticoid copepods together with unravelling the origin of the present copepods and (3) characterizing the trophic ecology of the copepod communities in the macrophytodetritus at the specific and eco-morphological level. This research showed that macrophytodetritus biomass is composed on average for 75% of dead P. oceanica seagrass leaves shed after senescence. Attached to the surface of the seagrass leaves numerous micro- and macroepiphytes are present, representing on average 10% of the total biomass. The remaining part is mainly constituted of drift material, like detached P. oceanica shoots and epilithic macroalgae. A seasonal pattern is observed regarding the amount of accumulated material and the physico-chemical composition inside the accumulation. Wind-induced hydrodynamics is the responsible driver behind the variability of the macrophytodetritus and consequently it has a major impact on the faunal communities already present in a macrophytodetritus accumulation. Previous studies showed that the presence of macrofaunal invertebrates (> 1 mm) in high amounts contributes to the degradation of the detritus. Similarly, this study proves the ubiquitous presence of meiofauna in macrophytodetritus. Depending on the season, densities from 20.10³ to 160.10³ meiofaunal organisms per square metre of accumulation were recorded. Copepods were the most abundant taxon (> 50%) of which 87% belonged to the order Harpacticoida. Nematodes were the second most abundant taxon, representing on average 18% of the total meiofauna densities. A total of 61 copepod species were found in Calvi Bay macrophytodetritus accumulations and adjacent habitats (bare sand, seagrass and water column), wherefrom 85% were shared amongst these habitats, underlining the high colonization capabilities of copepods. Active colonization occurred within 24h through species-specific dispersal pathways. Certain species were more avid to colonize, resulting in a colonizer-competitor trade-off among the copepod community. Eco-morphological characteristics seemed to be responsible for the dispersal potential. However, the variety of the composition of the copepod community suggested that other factors also contributed to the attractiveness of the structurally complex macrophytodetritus habitat. The isotopic niches of four abundant copepod species, representing four different eco-morphological groups were identified: Ectinosoma dentatum (mesopsammic-type), Diosaccus tenuiremis (phytal-type), Tisbe furcata (epibenthic-type) and Clausocalanus arcuicornis (water-column-type). Based on stable isotope analysis, fatty acid profiling and Bayesian mixing model, results suggested an interspecific diversity which would indicate a species-specific resource partitioning. C. arcuicornis mainly fed on suspended organic matter, while D. tenuiremis thrived mainly on epiphytes (mostly diatoms). E. dentatum was dependent on the seasonal availability of food sources, while T. furcata fed on a heterogeneous mixture of sources. Presumably none of the species directly assimilated dead seagrass leaf litter. Overall, by combining in situ sampling, novel mesocosm experiment, biomarkers and mixing models, this study displayed the carrying capacity of macrophytodetritus to support a large amount of meiofauna and a wide diversity of copepod species. The morphological differences among copepod species seem to allow specialization towards habitat preferences, (physical habitat preferences and colonization potential) and towards resource preferences (food partitioning). Macrophytodetritus seems thus to be a suitable home, or a temporary hub for a diverse copepod community. Finally, this dynamic and patchy habitat, prone to swift changes and situated at the crossing of different ecosystems, plays a major role in coastal ecology. [less ▲]

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See detailNouveaux modèles pour le calcul des roulements à billes cryotechniques
Servais, Christophe ULg

Doctoral thesis (2015)

The behavior of cryogenic ball bearings, that is to say those included in several space rocket engines, is quite difficult to estimate. The high speed effects, heavy loads and lack of conventional ... [more ▼]

The behavior of cryogenic ball bearings, that is to say those included in several space rocket engines, is quite difficult to estimate. The high speed effects, heavy loads and lack of conventional lubrication are among the main concerns during the conception phase. This doctoral thesis proposes a new numerical method to evaluate the way solid lubricated ball bearings are working. The main originality of the survey is the determination of the link between the ball/ring contacts and the rolling elements kinematics, for any kind of bearing loading or rotational speed. Moreover, the dissertation includes a mathematical model of the cage dynamics. The result of the whole exposed method is a computer program, which allows to deal with critical aspects of cryogenic ball bearings. Indeed, a set of examples demonstrates the capabilities of the new method as a design tool and provides a deep understanding of the specific features of such ball bearings. [less ▲]

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See detailLES ANOMALIES CONGENITALES DANS L’ESPECE BOVINE EN WALLONIE
Djebala, Salem ULg

Master's dissertation (2015)

Les anomalies congénitales sont devenues un sujet d’actualité en médecine vétérinaire notamment chez les ruminants. Et ce depuis l’émergence des infections virales tératogènes. Les étiologies de ces ... [more ▼]

Les anomalies congénitales sont devenues un sujet d’actualité en médecine vétérinaire notamment chez les ruminants. Et ce depuis l’émergence des infections virales tératogènes. Les étiologies de ces anomalies sont nombreuses. Elles sont d’origines infectieuses, toxiques, alimentaires, traumatiques, génétiques et plusieurs autres étiologies inconnues. Les anomalies musculo-squelettiques et de l’appareil reproducteur sont les plus fréquentes, elles représentent respectivement 51 % et 30 % des cas. Dans les tares congénitales du Blanc-bleu Belge, le nanisme est l’anomalie la plus fréquente (21 %) suivie par le syndrome de la queue tordue, la gestation prolongée et l’hamartome avec 11 %, 10 % et 8 % respectivement. Le syndrome d’arthrogrypose et palathoschisis et la dystonie musculaire congénitale sont de plus en plus rare, leurs fréquences respectives sont 5 % et 3 %. Plusieurs cas de maladie de la génisse blanche et de parésie spastique des membres postérieurs ont été observés. L’autopsie et l’échographie sont les meilleurs moyens pour le diagnostic des anomalies cardiaques congénitales. Dans la race BBB la persistance du trou de Botal est l’anomalie le plus fréquente (22 %). Le segment du coeur le plus touché par les anomalies congénitales est le ventricule droit (34 %). [less ▲]

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See detailAnalyse de la répartition spatiale des restes fauniques du site éémien de Caours (Somme). Apport des systèmes d'information géographique.
Moreau, Gwénaëlle ULg

Master's dissertation (2015)

The Palaeolithic deposit of Caours, located in the Somme, is the only Eemian site in Northern Europe in interglacial context. This site show an incredible conservation of faunal remains spread out over a ... [more ▼]

The Palaeolithic deposit of Caours, located in the Somme, is the only Eemian site in Northern Europe in interglacial context. This site show an incredible conservation of faunal remains spread out over a large area and a recurrence Human occupation. That gave us a large amount of data about this period of Neanderthal history. We now questioning about the choice of this locality and the spatial organisation of Neanderthal. Then, spatial analysis using the Geographic Information System (GIS) appear to being a useful tool to answer it. We show the consequent availability of water, prey and tool raw material. Neanderthalians was opportunistic hunters of cervidae. There has also eat a heavier prey as aurochs and rhino by trapping or scavenging. Then Neanderthal of Caours butchering with tool made in-situ eating the meat and the marrow. [less ▲]

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See detailCARACTÉRISATION D'UNE SOUCHE LOCALE DE MICROALGUE VERTE PRODUCTRICE DE CAROTÉNOÏDES SECONDAIRES
Corato, Amélie ULg

Master's dissertation (2015)

Les pigments secondaires produits par certaines algues (Haematococcus pluvialis, Chlorella zofingiensis, Coelastrella striolata var. multistriata,…) ont de nombreux intérêts dans la médecine(par leur ... [more ▼]

Les pigments secondaires produits par certaines algues (Haematococcus pluvialis, Chlorella zofingiensis, Coelastrella striolata var. multistriata,…) ont de nombreux intérêts dans la médecine(par leur pouvoir antioxydant), l’aquaculture, l’industrie,…. La microalgue H. pluvialis est la plus grande source productrice naturelle d’astaxanthine. Ce pigment est le caroténoïde secondaire le plus recherché de par son pouvoir antioxydant très élevé. H. pluvialis est difficile à cultiver et croît lentement par rapport à d’autres microalgues vertes (par exemple, l’organisme de référence C. reinhardtii), c’est pourquoi de nombreux scientifiques cherchent des alternatives efficaces à celle-ci. Parmi elles, C. zofingiensis semble être une bonne concurrente, même si elle est loin de produire une quantité d’astaxanthine équivalente à celle que produit H. pluvialis. Dans ce contexte, nous avons isolé une microalgue dans la région de Liège (Belgique) et, en première observation, il s’est avéré qu’elle possède la particularité de produire naturellement des pigments secondaires. Nous avons donc cherché des conditions de culture propices à l’augmentation de la vitesse de production de ces pigments par cette microalgue. Nous avons réalisé une identification, en utilisant des outils moléculaires. Ensuite, nous avons analysé les différents modes de cultures possibles pour augmenter sa vitesse de croissance et son accumulation de biomasse « verte », en vue de l’utiliser pour les analyses de production de caroténoïdes secondaires. Des mesures de l’activité photosynthétique ont également été réalisées en vue de mieux comprendre l’effet du CO2 sur la croissance photoautotrophe. Enfin, des analyses de production de caroténoïdes secondaires par des cultures, suite à l’application de stress reconnus pour augmenter la vitesse de production de ces pigments chez les microalgues, ont été effectuées et le contenu en pigments de différentes cultures a été analysé par HPLC. [less ▲]

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See detailLa gestion participative en contexte de fusion/acquisition dans les PME à finalité sociale
Souply-Pierard, Fernand ULg

Master's dissertation (2015)

The goal of this study is to answer the following research question: “Is participative management a determining factor in the success of the process of "mergers and acquisitions", particularly in the ... [more ▼]

The goal of this study is to answer the following research question: “Is participative management a determining factor in the success of the process of "mergers and acquisitions", particularly in the specific context of study which is that of a socially oriented SMEs? ". It will indeed matter to verify whether the participatory management can be described as such, and that through a study of the literature and a case study in a particular context - that of an Adapted Work Enterprise (ETA): the Ateliers Jean Del'Cour. It recently experienced a merger and acquisition process with another ETA, the ETA Jacqueline Orts. To do so, the case study was conducted in two parts. One of these, the qualitative part, was made with the "top" and "middle" management of the company, while the second, more quantitative, was conducted among workers from one of the absorbed sites which was most affected by this merger and acquisition process. It has been probing the question of indicators (welfare, engagement, recognition, values, participation and communication, essentially) to establish a positive link between participation and merger and acquisition. It was then discovered that such a link exists clearly and that participative management is indeed one of the determining factors in the success of a merger and acquisition process. But the discoveries of this study go further. It was highlighted that communication is the essential element of participatory management, as well as a tool than as a backdrop behind the implementation of other tools and participatory means. The communication must be implemented as soon as possible during the merger and acquisition process, it must be adapted and must be as formal as informal (informal side being very important). This is also valid for the other tools and participatory means. These findings are a real contribution for the managerial level in the specific context studied but also for all merger and acquisition processes, and an invitation to pursue more specific researches on this issue in order to provide accurate and specific answers to problems encountered by companies who experience this major change. [less ▲]

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See detailCardio-pulmonary mechanics and minimal modelling in critical care
de Bournonville, Sébastien ULg

Master's dissertation (2015)

Positive pressure ventilation is a widely used support for patients in intensive care units.Their weak respiratory condition is often accompanied by a weak cardiac status and haemodya-mical instability ... [more ▼]

Positive pressure ventilation is a widely used support for patients in intensive care units.Their weak respiratory condition is often accompanied by a weak cardiac status and haemodya-mical instability. This ventilation support has significant impacts on the cardiovascular systemthat are known but not predicted nor taken into account when varying the respiratory para-meters such as the positive end-expiratory pressure. The fact is that positive end-expiratorypressure increases the intrathoracic pressure. Ultimately, this will lead to decreases in cardiacoutput and stroke volume of the left ventricle. The good parametrization of such ventilator istherefore of primary importance for the critically ill patient cares.This master’s thesis seeks to develop a new minimal model of the cardiovascular and therespiratory system that is new in terms of its cardiovascular lumped model representationand the fact that it takes into account the cardiopulmonary interactions. This new model isaimed to be implemented at bedside for real time monitoring of the patients’ cardiac status asfunction of the respiratory inputs. Its ultimate use will be prediction and active control of thisstatus to improve the work of clinicians.The physiological knowledge in terms of cardiopulmonary interactions was investigated toselect the specific behaviour that will be modelled. The mathematical representation of themodel was precisely described and was designed as a function of physiological relevancy, com-putational weight and data availability. These factors lead to the design of a three chambermodel of the cardiovascular system, focused on the left ventricle, the aorta and the vena cavawhich represent the common available data in ICUs. This three chamber model was coupledto a single compartment model of the lung to compute the intrathoracic pressure that actson intrathoracic structures. Porcine measurements performed with the chest closed were usedto build patient specific models by fitting the model outputs to these measurements. Theconstruction of patient specific models was performed by identifying the patient-specific pa-rameter values of the model. For this purpose, the data were first processed to compute andidentify many parameters. Then an iterative optimization process was implemented to fit themodel to the specific datasets.This model was validated against the aforementioned porcine datasets. It showed physiolo-gical behaviours and reactions in a cardiovascular point of view as well as in a cardiopulmonaryinteractions point of view. By analysing the several identified parameters on the PEEP levelof each pigs, correlations between haemodynamical parameters and the PEEP level applied tothe patients were identified. It also allowed the confirmation that linear ESPVR models arenot appropriated for relatively high levels of PEEPs. The model showed the expected beha-viour of decreasing cardiac output for an increasing PEEP although not in the expected ranges.Eventually, this work opens many research hypotheses and questions in this field. Thequestion of implementing the model at bedside for real-time monitoring should be investigated.A modelling of the correlation between haemodynamic parameters and PEEP based on theresult of this work should also be investigated. [less ▲]

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See detailDynamic model reduction of a thermocline storage integrated in a micro-scale solar power plant
Wéber, Noé ULg

Master's dissertation (2015)

Concentrated solar power plants (CSPs) are one of the growing technologies that will help increase the share of renewable energy in the world’s electricity production. Coupling them with a storage tank ... [more ▼]

Concentrated solar power plants (CSPs) are one of the growing technologies that will help increase the share of renewable energy in the world’s electricity production. Coupling them with a storage tank allows for the storage of excess energy during sunny periods to be reused during the day, hence improving the plant’s capacity factor and reducing the cost of electricity. Thermocline storage tanks are a very good compromise between cost and efficiency constraints, compared with other storage technologies. Nevertheless, powerful dynamic simulation tools are needed to model efficiently the transients linked to the intermittency of the solar source. The aim of the proposed thesis is to contribute to the development of such tools. This paper first compares existing physical deterministic models of a thermocline storage tank and a parabolic trough solar field to reduced models over four reference days. The deterministic models give accurate results with high simulation times, whereas the reduces models are fast, but loose some precision in the results. Some flaws of the simplified tank model are detected, and a third model of storage system is designed. Based on the study of numerous charging and discharging processes, the law that characterizes the evolution of the thermocline is computed and integrated in the new model. This model is then validated over the same four reference days; the dynamic update of the height of the thermocline allows this new model to fit very well any weather condition. The model developed has fixed dimensions and parameters, which limits its generality. As such, a fourth model of tank is developed, based on dimensionless numbers. This last model is validated in various conditions, and is therefore suitable to any situation, with no constraint regarding weather conditions, geometry of the tank or working fluid. The simulation time required by this model is between 75 and 180 times less than that of the first complex model, and the robustness of the model is flawless, which makes it a very powerful tool. Finally, a new control strategy for the solar power plant is assessed : it allows validation of the new model of tank in yet another set of working conditions, as well as investigation of advantages and drawbacks of one strategy over an other. An unexpected observation is that the thermocline height at the end of the day does not depend on the strategy used, even though the evolution is different in both cases. Some numerical issues that have been tackled to bring the model to a perfect robustness are also discussed. [less ▲]

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See detailImplementing and Comparing Stochastic and Robust Programming
Cuvelier, Thibaut ULg

Master's dissertation (2015)

Traditional optimisation tools focus on deterministic problems: scheduling airline flight crews (with as few employees as possible while still meeting legal constraints, such as maximum working time ... [more ▼]

Traditional optimisation tools focus on deterministic problems: scheduling airline flight crews (with as few employees as possible while still meeting legal constraints, such as maximum working time), finding the shortest path in a graph (used by navigation systems to give directions, usually based on GPS signals), etc. However, this deterministic hypothesis sometimes yields useless solutions: actual parameters cannot always be known to full precision, one reason being their randomness. For example, when scheduling trucks for freight transportation, if there is unexpected congestion on the roads, the deadlines might not be met, the company might be required to financially compensate for this delay, but also for the following deliveries that could not be made on schedule. Two main approaches are developed in the literature to take into account this uncertainty: take decision based on probability distributions of the uncertain parameters (stochastic programming) or considering they lie in some set (robust programming). In general, the first one leads to a large increase in the size of the problems to solve (and thus requires algorithms to work around this dimensionality curse), while the second is more conservative but tends to change the nature of the programs (which can impose a new solver technology). Some authors [2] claim that those two mindsets are equivalent, meaning that the solutions they provide are equivalent when faced with the same uncertainty. The goal of this thesis is to explore this question: for various problems, implement those two approaches, and compare them. Is one solution more secluded from variations due to the uncertain parameters? Does it bring benefits over a deterministic approach? Is one cheaper than the other to compute? [less ▲]

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See detailLa critique cinématographique : Analyse des contrats de lecture proposés dans la presse traditionnelle d’aujourd’hui
Krywicki, Boris ULg

Master's dissertation (2015)

De nos jours, l’on constate l’existence de nombreuses alternatives à la critique cinématographique que l’on peut trouver dans la presse traditionnelle. La critique a beaucoup été chahutée au fil du temps ... [more ▼]

De nos jours, l’on constate l’existence de nombreuses alternatives à la critique cinématographique que l’on peut trouver dans la presse traditionnelle. La critique a beaucoup été chahutée au fil du temps : remise en question de la légitimité des journalistes spécialisés, soupçons d’un dénigrement du cinéma populaire, accusation d’être réservée à une élite culturelle… Le genre a changé significativement, tentant de s’adapter à une industrie en constante évolution. Aujourd’hui, l’on peut voir de nouvelles formes émerger sur Internet, de la critique en vidéo sur Youtube à l’avis succinct laissé sur un réseau social. Malgré tout, la critique traditionnelle semble s’en tenir à certains réflexes et aux fondamentaux de la fonction critique. Face à l’opposition entre ces évolutions et ce conservatisme, l’on pourrait s’interroger sur le changement des attentes des lecteurs de critiques. Sont-elles restées les mêmes que dans les années 50, aux débuts des Cahiers du cinéma ? Les réflexes des journalistes spécialisés restent-ils adaptés ? Si nouvelle forme de critique il y a, ne correspond-elle pas à de nouveaux contrats de lecture ? Il nous a semblé intéressant de scruter la critique sous le point de vue de la relation qu’elle propose à son lecteur. [less ▲]

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See detailFragmentation urbaine à travers les réseaux techniques
Cabrera Quispe, Juan Edson ULg

Doctoral thesis (2015)

Since about three decades ago, the networking services (water, energy, transport and telecommunications) are the subject of studies and mainly reforms (liberalization, privatization and concessions to ... [more ▼]

Since about three decades ago, the networking services (water, energy, transport and telecommunications) are the subject of studies and mainly reforms (liberalization, privatization and concessions to private companies, etc.) and also an important economic policy issue. However the possible effects of these reforms on the fragmentation or integration of urban societies are still poorly studied, although some studies (mainly on developing cities) support the thesis that there would be a growing urban fragmentation, reinforced by the dominant modes of implementing reforms network services. One of the most important theses about the subject is in a relatively recent development of the English authors Stephen Graham and Simon Marvin (2001). Their work generalizes the motion of fragmentation (splintering Urbanism) to all network services and a set of economic regions in the world. While this thesis presents consistency and validity - since it is known that the application of models of decentralization and liberalization of services has an effect on the fragmentation - the position of fragmentation due to centralized networks is inside a new analysis framework and still incomplete considering the absence of more empirical evidence. The thesis of fragmentation from centralized networks suggests that powerful factors are contributing to the disintegration of infrastructure, favoring the fragmentation of the social structure and material of cities. In fact, this breakdown of infrastructures makes possible many strategies of evasion; they are addressed to connect powerful users and valorized spaces, preventing the connection with less powerful users and poor spaces. These processes lead to the creation of spaces from different social networks, resulting in social elites living every day in places disconnected from the urban structure of the set (in gated communities, new complex people and other planned communities), as well as the lower classes, but the latter with the worst conditions. The main hypothesis of the "splintering Urbanism" argues that network services have an integrated character and are precisely the privatization and liberalization of services that contribute to the breakdown of network infrastructure and urban fragmentation feed. The control of networks from powerful coalitions of actors, separation and segmentation boost infrastructure in different network elements and service pack (2001: 141). This separation would occur across strategies "bypass" or "wrap" seeking to connect users, valuable or powerful places, and through discarding or dodge weaker users and worthless places. Our thesis "Urban Fragmentation through technical networks," confirms and reinforces the thesis made by Graham & Marvin, across expounding on the Cochabamba Bolivian context, a set of technical networks of small-scale or micro decentralized networks which are managed by autonomous social organizations that also fragment the territory without the need for "by pass" and the socio-spatial differentiation, but through the realization of strategies linked to autonomous administration and management of common and basic goods like water. This thesis demonstrates the existence of processes of spatial dislocation and loss of solidarity (main evils of urban fragmentation) across the dynamics of technical devices and decentralized networks infrastructure services from private-community water and small scale. However, our work describes in its urban development, territorial and environmental problems inside the phenomenon. The paper first presents a set of theories that attempt to explain the fragmentation and its particularities, then describes the socio-spatial formation of the study area whose characteristics allow this type of phenomenon, to arrive to a section that exposes all the particularities of the management water from public and local actors, analyzed from the environmental logic of urban water cycle, including the specifics of the main stage of study of this thesis, the municipality of Quillacollo in Cochabamba. From a spatial perspective, the thesis exhibits the characteristics of urban fragmentation across technical networks, exposing the details related to the organization of urban space as a result of processes of spatial dislocation, loss of solidarity and exercise of territoriality in small networks. It is concluded in a discussion about the validity of the strategies in terms of access to the resource, the possibilities of intervention and reflections about the power relationships among fragments and for water control. Finally, as a supplement, urban fragmentation through small technical networks, also allows to display the tensions between two ways of managing the territory (centralized view from the public sector and decentralized vision from local communities) highlighting the uncomfortable and marginalized urban planning position, but challenging the urbanism to recover to action on the highly fragmented contemporary cities with complex scenarios of governance and sometimes rare or endangered resources. [less ▲]

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See detailAnalytical strategies for ultra-trace measurement of dioxins and related compounds in biological matrices
L'Homme, Benjamin ULg

Doctoral thesis (2015)

The human exposure to persistent organic pollutants (POPs) is a concern since these compounds are ubiquitous in the environment. This class of compounds group different families such as the ... [more ▼]

The human exposure to persistent organic pollutants (POPs) is a concern since these compounds are ubiquitous in the environment. This class of compounds group different families such as the polychlorodibenzo-p-dioxins (PCDDs), the polychlorodibenzofurans (PCDFs), the polychlorinated biphenyls (PCBs), the organochlorine pesticides (OCPs), and the halogenated flame-retardants (HFRs). Their use, their release in the environment, their presence in foodstuffs, as well as in various goods on the market are mostly regulated through international conventions, like the Stockholm convention on POPs, and at the European and national levels. Despite the proactive approach in order to reduce the overall exposure to POPs, levels of contaminants (even banned) are still found in the environment and in the human body. In this thesis, we developed several methods of analysis of POPs in different samples. The first was a confirmatory method for PCDD/Fs and PCBs analysis in food and feed following a new European Regulation No 709/2014 that recently allowed the use of gas chromatography (GC) coupled to triple quadrupole mass spectrometry (GC-QQQMS/MS) for this purpose. We fully validated the method on vegetable oil matrix around the maximum level of 1.50 ng WHO2005TEQ/kg. We showed that all analytical criteria, specific to this instrumentation, laid down by the Regulation were met, which indicates that the QQQMS/MS can successfully be used in the legal context for confirmatory purposes and could be an alternative to high-resolution sector field mass spectrometry (HRMS) in this context. The proper establishment of limits of quantitation was a key point in the discussion along with other analytical criteria proposed in the European Regulation, as new interpretations were necessary for the use of triple quadrupole mass spectrometry due to its different features from the HRMS. In addition, we developed in parallel a method for the analysis of Dechloranes in food. The measurement of ultra-trace levels of compounds from this emerging class of flame-retardants was possible after optimization of the injections parameters by means of experimental design, and of fragmentation pathways. Eventually, we reported relatively low levels in various food matrices and preliminary data about the significance of this route of exposure for humans. Besides food analysis, we developed a screening method to quickly assess levels of contaminants in human blood, involving a minimally invasive sampling technique and a couple of drops of blood. The instrumentation was first based on cryogenic zone compression (CZC) hyphenated to high-resolution time of flight mass spectrometry (HRTOFMS) applied to the analysis of two markers of exposure in regular dried-blood spots (DBS) typically used for newborn sampling. The second approach was based on GC-QQQMS/MS applied to the analysis of a broader range of OCPs and NDL-PCBs (30 analytes) in 40 µL blood. The blood was however collected using a novel Volumetric Absorptive MicroSampling (VAMS) method, directly inspired by the DBS but offering a control on the volume of blood sampled, hence opening the door to quantitation. The sample preparation of the VAMS dried sample was miniaturized and only 2 mL of solvents were necessary to prepare a sample, which makes it environmentally friendly. The focus was especially drawn to maximize the sensitivity via the optimization of the ionization energy and the electron multiplier voltage in order to reach appropriate low limits of quantitation. In this context of ultra-low volume of blood, background levels arose as the limitation of the method owing to the small signals coming from samples and closing the gap with blanks. Nevertheless, this patient-friendly approach is perfectly suitable for fast screening of population and could be useful in the context of UNEP campaigns where samples are hardly collected. [less ▲]

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See detailLe confesseur du Prince dans les Pays-Bas espagnols (1598-1659): une fonction, des individus.
Pirlet, Pierre-François ULg

Doctoral thesis (2015)

Cette thèse envisage, à la cour de Bruxelles (1598-1659), les rapports entre les pouvoirs séculiers et religieux au travers de la figure nodale du confesseur du Prince.

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See detailArtificial Intelligence in Video Games: Towards a Unified Framework
Safadi, Firas ULg

Doctoral thesis (2015)

The work presented in this dissertation revolves around the problem of designing artificial intelligence (AI) for video games. This problem becomes increasingly challenging as video games grow in ... [more ▼]

The work presented in this dissertation revolves around the problem of designing artificial intelligence (AI) for video games. This problem becomes increasingly challenging as video games grow in complexity. With modern video games frequently featuring sophisticated and realistic environments, the need for smart and comprehensive agents that understand the various aspects of these environments is pressing. Although machine learning techniques are being successfully applied in a multitude of domains to solve AI problems, they are not yet ready to enable the creation of fully autonomous agent that can reliably learn to understand the environments found in complex video games. Since video game AI is often specifically designed for each game, video game AI tools currently focus on allowing video game developers to quickly and efficiently create specific AI. One issue with this approach is that it does not efficiently exploit the numerous similarities that exist between video games not only of the same genre, but of different genres too, resulting in a difficulty to handle the many aspects of a complex and realistic environment independently for each video game. These similarities, however, exist on a conceptual level. While video games do indeed share a variety of concepts, their interpretations vary from one game to another. Hence, these similarities can only be directly exploited at a conceptual level. Inspired by the human ability to detect analogies between games and apply similar behavior on a conceptual level, this thesis suggests an approach based on the use of a unified conceptual framework to enable the development of conceptual AI which relies on conceptual views and actions to define basic yet reasonable and robust behavior. Because conceptual AI is not tied to any game in particular, it benefits from a continuous development process as opposed to a development that is confined to the scope of a single game project. [less ▲]

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See detailSynthèse et applications catalytiques d'adduits zwitterioniques de carbènes N-hétérocycliques
Hans, Morgan ULg

Doctoral thesis (2015)

In 1991, Arduengo isolated and fully characterized the first N-Heterocyclic Carbene (NHC), thereby confirming the existence of these stable divalent carbon species postulated almost thirty years earlier ... [more ▼]

In 1991, Arduengo isolated and fully characterized the first N-Heterocyclic Carbene (NHC), thereby confirming the existence of these stable divalent carbon species postulated almost thirty years earlier by Wanzlick. Since then, the enthusiasm for these highly nucleophilic and strongly basic compounds has steadily increased in the scientific community. Their reactivity with respect to organic compounds is very rich and is relatively well documented since the middle of the 1960’s. Their strong electron-donicity and their moderate pi-acidity make them almost universal ligands. NHC complexes have indeed been prepared with practically all the metals from the periodic table. Their high nucleophilicity also allowed to successfully employ them as organocatalysts. The state of the art in these three fields as well as the properties of NHCs and their electronic and steric characterizations are discussed in the introduction of this manuscript. The second chapter is devoted to the synthesis and characterization of imidazol(in)ium dithiocarboxylates (NHC•CS2 adducts), carboxylates (NHC•CO2 adducts) and thiocarboxylates (NHC•COS adducts) and to their applications in organic synthesis and in coordination chemistry. First, because NHC•CO2 adducts do not require any reagents to generate free carbenes in solution, we proposed them as precursors of NHC to promote various Michael additions. Preliminary catalytic assays of a set of five representatives of this zwitterion family in a carba-Michael addition previously reported in the literature highlighted the net superiority of 1,3 dicyclohexylimidazolium carboxylate (ICy•CO2). Subsequently, we showed the efficiency of our catalytic system to promote sulfa-, and phospha-Michael additions. Eventually, the same precatalyst showed efficiency to initiate various sulfa-Michael/aldol organocascades. Second, we looked at the synthesis of a representative set of five imidazol(in)ium thiocarboxylates. Their characterization indicated a probable loss of the thiocarboxylate group. Hence, we tested their efficiency as carbene’s precursors in two benchmark reactions usually catalyzed by NHCs. 1,3-Dicyclohexylimidazolium thiocarboxylate (ICy•COS) turned out to be most effective to promote transesterification/acetylation, while 1,3 bis(2,4,6-trimethylphenyl)imidazolinium thiocarboxylate (SIMes•COS) afforded a quantitative yield in the benzoin condensation. Moreover, reaction of NHC•COS betaines with a half-equivalent of ruthenium dimer [RuCl2(p-cymene)]2 led to [RuCl2(p-cymene)(NHC•COS)] complexes in which the zwitterions were bonded to ruthenium by the sulfur atom only. This is a remarkable result because NHC•CO2 zwitterions behaved like efficient NHC precursors leading to metal-NHC complexes, while imidazol(in)ium dithiocarboxylates showed no signs of dissociation. They behaved as kappa2-S,S’ chelating ligands and led to metal-(S2C•NHC) complexes. Finally, catalytic tests of these new complexes bearing NHC•COS adducts in the Ring-Opening Metathesis Polymerization (ROMP) of cyclooctene, in the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate and in the synthesis of enol esters resulted in low yields. However, they provided evidence for the rearrangement of the starting complexes in Ru-NHC species under the experimental conditions adopted. The third chapter is devoted to the synthesis of azolium enolates and their characterization, as well as their involvement in the Staudinger reaction and to their coordination chemistry to ruthenium. Our interest initially focused on the general mechanism of the NHC-catalyzed Staudinger reaction. Literature reports two plausible mechanisms for the [2 + 2] cycloaddition between ketenes and electron-poor imines. The first one, called "Imine-first" involves an azolium amide, while the second one, called "Ketene-first" goes through an azolium enolate. Synthesis and full characterization of these two types of zwitterionic adducts combined with their catalytic assay in the reaction between diphenylketene and N-tosylbenzaldimine allowed us to acquire a strong experimental evidence in favor of the "Ketene-first" observed path. We were then interested by probing the diastereoselectivity observed during NHC catalyzed [2 + 2] cycloadditions between unsymmetrical ketenes and various N sulfonylbenzaldimines. In order to investigate the parameters that influenced the stereoselectivity during these reactions, we prepared and fully characterized two new betaines (S)IMes•EtPhC=C=O and we performed catalytic assays in the reaction between ethylphenylketene and different N-sulfonylbenzaldimines, during which we varied various experimental parameters. We showed that steric hindrance of the catalyst is critical, poorly hindered NHCs favoring cis diastereoisomers, while trans-beta-lactams were essentially produced when more congested catalysts were used. The reaction solvent is also a critical parameter, N,N-dimethylformamide allowing to obtain the best diastereoisomeric ratio, 16:84, in favor of the trans isomer. Finally, the reaction temperature and the nature of the substituent on the N-sulfonylated imine are less important. The last part of this chapter concerned the coordination of NHC•ketene adducts to ruthenium. Our starting hypothesis was that these betaines could provide simultaneously an NHC ligand and an alkylidene precursor (a ketene) to the metal. By this way and from adequate metallic precursors, we envisioned to synthetize second-generation Grubbs type complexes, benchmark catalysts for olefin metathesis, in one step and without the need to handle diazo compounds. Although the first exploratory experiments did not lead to the expected results, they provided crucial information to help achieve these syntheses in future investigations. [less ▲]

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See detailContribution à la caractérisation des cellules du ganglion spiralé et des cellules de Boettcher de l’épithélium cochléaire durant le développement chez les rongeurs
Cloes, Marie ULg

Doctoral thesis (2015)

As per a recent WHO report (2015), 360 million people worldwide suffer from invalidating deafness. In hearing physiology a central role is played by the sensory cells of the organ of Corti. The sensory ... [more ▼]

As per a recent WHO report (2015), 360 million people worldwide suffer from invalidating deafness. In hearing physiology a central role is played by the sensory cells of the organ of Corti. The sensory cells are responsible for the transduction of the acoustic stimuli into nerve impulses. Located nearby the sensory cells, Boettcher’s cells (BC) are barely known. The first part of our study aims at examining their morphology and ultrastructure during the postnatal development of the rat cochlear epithelium. Our morphological studies indicate that BC begin their differentiation around the 8th postnatal day (P8) and become mature around P20, once they are fully covered by Hensen’s and Claudius’ cells. Moreover, with the help of the transmission electron microscope, we noted the presence of apical tight junctions as long as BC are in contact with endolymph between P8 and P16. Our ultrastructural and immunohistological studies also show gap junctions between BC and the adjacent cells before the end of the covering process of BC. We also noted intermediate junctions between BC during the whole length of their maturation process. Finally we noticed cytoplasmic secretory granules and an accumulated material in the intercellular spaces between P8 and P25. Our data suggest that BC fulfill several functions in the cochlear epithelium: endolymphatic K+ recycling via the stria vascularis and the biosynthesis of the basilar membrane’s extracellular matrix. As the first and exclusive relay for the transmission of the auditory information to the central nervous system, the spiral ganglion (SG) is another key element of hearing physiology. The SG is mainly made up of neurons and glial cells. In an attempt to clarify the embryonic origin of the cells of the SG, we studied a strain of double transgenic mice Wnt1-Cre;Rosa26YFP, which are characterized by the permanent labelling of the neural crest cells by the YFP. We observed a constant labelling in the SG and in the stria vascularis, further supporting that the SG glial cells and the intermediate cells of the stria vascularis originate from the neural crests. However we also detected an additional and changeable positivity amongst the cells of the cochlear epithelium and osseous labyrinth, disqualifying the strain as a suitable tool of investigation. [less ▲]

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See detailCompétitivité, valorisation des ressources et objectifs de sécurité alimentaire pour la filière sucrière au Maroc
Redani, Latifa ULg

Doctoral thesis (2015)

The general objective of this work is to examine the coherence between food security policies and economic efficiency and valuation of resources policies for the sugar sub-sector in Morocco. A food ... [more ▼]

The general objective of this work is to examine the coherence between food security policies and economic efficiency and valuation of resources policies for the sugar sub-sector in Morocco. A food security policy implies state intervention and thus leads implicitly to market distortions, while a resource valuation policy would imply a free market. To address this issue, I will firstly adopt an approach that involves a sugar market analysis (measuring determinants of demand and changes in international prices against their impact on food security). Then, an economic analysis which attempts at assessing the competitiveness of the various segments of the sugar sub-sector will be undertaken. Finally, an analysis of the relative valuation of resources (capital, labor and irrigation water) by sugar crops compared to different irrigated crops will be led, in order to determine their private and social returns on. The analysis of demand during the period between 2000 and 2010 shows that the trend of domestic consumption witnessed major increases, which lead to the enhancement of food insecurity for sugar in the future. The analysis of volatility of world sugar prices from 1960 to 2010, through the decomposition method of time series, allows the isolation of an accidental effect, which reflects variability due neither to seasonal effects nor to trend. This accidental effect is mainly marked during three periods: 1973-1975, 1980-1981 and 2009-2010. In terms of food security, these fluctuations in world sugar prices have no impact on household access to sugar, yet they have a significant impact on state budget. Any variation in prices in the international market is absorbed by the compensation system since prices are regulated by this system. The food safety policy conducted during the sixties and seventies have mitigated the country's dependence on imports and thus reduce the impact of world sugar price fluctuations. However, this policy has often been criticized in terms of market efficiency and valuation of resources. The economic analysis of the sugar sub-sector in Morocco shows that the different segments of the value chain don’t enjoy the same level of protection. If the production segment of sugar beet doesn’t receive any protection, the processing segment of raw sugar will remain protected. However, the level of this protection has generally declined during the post structural adjustment period. In terms of competitiveness, while the sugar beet crop becomes competitive, the effective competitiveness of the industrial segment, and given the significant distortions in the world market, is difficult to assess. The analysis of the valuation of resources (capital, labor and water) shows that sugar crops, especially sugar beets, value relatively better capital resources and labor than most horticultural crops. They occupy an important position in terms of employment and value added created per hectare. However, the valuation of irrigation water remains low for sugar beet (excluding the region of Doukkala). But the technology trend shows substantial opportunities for improvement. Food security policy for sugar has been efficient since it helped establish a competitive national production which is generally able to value resources better. The distortions introduced by state intervention gave the time to farmers to improve their technical skills and to become competitive in the framework of international market, marked as it was by significant distortions. Finally, a food security policy is in no way inconsistent with a policy of valuation of resources on the condition that when the sub-sector becomes competitive, a way to market mechanisms must be given. [less ▲]

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See detailRepresenting a Minority Group in Multinational Federal Systems: Career Patterns in Catalonia, Scotland and Wallonia
Dodeigne, Jérémy ULg

Doctoral thesis (2015)

Dans nos démocraties représentatives, comprendre « qui » gouverne et plus précisément « comment » et « pourquoi » certains accèdent aux positions de pouvoir a toujours été un enjeu démocratique majeur ... [more ▼]

Dans nos démocraties représentatives, comprendre « qui » gouverne et plus précisément « comment » et « pourquoi » certains accèdent aux positions de pouvoir a toujours été un enjeu démocratique majeur. Avec les processus de régionalisation et de fédéralisation observés à travers le monde, cette question s’est complexifiée en raison de la multiplication des lieux de décision politique. Dans de nombreux pays, les représentants politiques évoluent désormais dans des systèmes multi-niveaux. L’une des conséquences directes de ces réformes institutionnelles est la transformation des carrières parlementaires, particulièrement dans les régions minoritaires des états plurinationaux comme la Belgique, l’Espagne et le Royaume-Uni. L’objectif de cette recherche doctorale est double. D’une part, elle cherche à définir l’orientation régionale et/ou nationale qui caractérise la carrière des élus depuis l’instauration des assemblées régionales. D’autre part, elle vise à identifier les facteurs qui expliquent l’émergence de ces différents types de carrières. À cette fin, la thèse développe une étude comparée de la Catalogne, de l’Écosse et de la Wallonie qui combine analyses quantitatives et qualitatives. Une des conclusions majeures de cette recherche est que le niveau de pouvoir régional est devenu une arène politique de plus en plus attractive – voire prédominante pour certains acteurs. Toutefois, contrairement à ce qui fut suggéré par des études antérieures, les parlements nationaux espagnol, britannique et belge continuent d’être des arènes politiques attractives pour les élus catalans, écossais et wallons. [less ▲]

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See detailEtude épidémiologique et moléculaire de la dyskinésie ciliaire chez le chien
Merveille, Anne-Christine ULg

Doctoral thesis (2015)

Les dyskinésies ciliaires primaires (DCP) sont des maladies génétiques rares regroupant des pathologies respiratoires liées à une anomalie constitutionnelle des cils dits “mobiles” (Leigh, 2006). Ces cils ... [more ▼]

Les dyskinésies ciliaires primaires (DCP) sont des maladies génétiques rares regroupant des pathologies respiratoires liées à une anomalie constitutionnelle des cils dits “mobiles” (Leigh, 2006). Ces cils jouent un rôle important dans l’organisme, notamment au niveau du tractus respiratoire, où ils entrent dans la composition de l’escalator mucociliaire. Ils jouent également un rôle au niveau du système reproducteur et durant l’embryogénèse. Chez l’homme, la prévalence des DCP est estimée à 1 :10.000 (Afzelius et Stenram, 2006). Chez le chien, il existe une trentaine de cas décrits dans la littérature dans 20 races différentes. Les deux espèces partagent des manifestations cliniques similaires, directement liées à la dysfonction de la mobilité ciliaire. La plupart des individus touchés présentent des signes dès leur plus jeune âge. Parmi ces signes, on retrouve une atteinte des voies respiratoires comprenant des infections récidivantes des voies hautes (rhino-sinusites) et basses (bronchites et bronchopneumonies qui mènent à de la bronchiectasie), mais aussi de l’infertilité et, dans la moitié des cas environ, des défauts de latéralité que l’on appelle situs inversus (Leigh, 2006). La structure des cils mobiles est hautement conservée entre les différentes espèces et se caractérise par un agencement de neuf paires de microtubules périphériques organisées autour d’une paire centrale de microtubules. A cette structure, se rajoutent des complexes protéiques qui permettent de stabiliser les différents composants comme les crêtes radiales ou le complexe régulateur des dynéines, mais aussi des protéines motrices qui permettent au cil de se mouvoir comme les bras de dynéine. Cet agencement est perturbé dans la grande majorité des DCP qui présentent différents types de défauts ultrastructuraux en fonction des différents gènes impliqués (Papon et al., 2010) (Jorissen et al., 2000b). Chez l’homme, comme chez le chien, le défaut ultrastructurel le plus fréquent est une atteinte des bras de dynéine externes. La plupart des DCP se transmettent selon un mode autosomique récessif et plusieurs gènes causals ont été identifiés (Zariwala et al., 2011). Toutefois, les bases moléculaires d’un certain nombre de cas chez l’homme restent à ce jour indéterminées et chez le chien aucun gène responsable n’avait été identifié avant cette présente étude. Le chien représente un modèle spontané de DCP qui pourrait être utile dans la découverte de nouveaux gènes impliqués dans cette pathologie. Les différents objectifs de ce travail étaient d’une part, d’étudier le phénotype clinique d’une DCP ségrégant au sein d’une race de chien, le bobtail, et d’autre part, d’identifier le mode de transmission génétique ainsi que les bases moléculaires de cette DCP. Nous avons également voulu étudier la fréquence de la mutation identifiée dans cette race. Une fois le gène identifié chez le bobtail, nous avons voulu déterminer si celui-ci pouvait être responsable de cas de DCP humaines présentant un phénotype ultrastructurel similaire à celui des bobtails atteints. Ensuite, nous avons voulu évaluer les conséquences qu’une dysfonction de ce gène pouvait entraîner, afin de gagner en compréhension sur le rôle de la protéine impliquée et pour confirmer que les mutations identifiées étaient bien à l’origine du phénotype clinique observé. Enfin, nous avons voulu déterminer si ce gène pouvait être impliqué dans d’autres ciliopathies. Nous avons tout d’abord obtenu des données cliniques sur une dizaine de chiens atteints. Tous appartenaient au même pedigree et présentaient un phénotype clinique caractéristique apparu très tôt dans la vie de l’animal. Ce phénotype se caractérisait par un jetage nasal bilatéral, une toux productive, une leucocytose neutrophilique et des infections respiratoires récurrentes dont les séquelles étaient visibles sur les radiographies thoraciques avec des lésions de bronchopneumonie touchant les lobes crâniaux et moyen droit ainsi que des lésions de bronchiectasie. L’analyse du sperme d’un de ses chiens mettait en évidence une réduction de la mobilité des spermatozoïdes et un pourcentage important de formes anormales en microscopie optique. Un situs inversus était également présent dans environ un tiers des cas. Les anomalies ciliaires observées en microscopie électronique chez ces chiens révélaient un phénotype ultrastructurel peu commun, associant une atteinte des bras de dynéine internes et des anomalies de la paire centrale de microtubules. L’analyse du pédigree de ces chiens était en faveur d’un mode de transmission autosomique récessif. L’étude d’association génome entier réalisée chez 5 atteints et 15 contrôles a permis d’identifier une région contenant 151 gènes candidats. Une sélection des gènes décrits comme impliqués dans la structure et/ou la fonction des cils (Gherman et al., 2006; Inglis et al., 2006) a permis une réduction drastique des gènes candidats. Le séquençage de ceux-ci a permis d’identifier un codon stop prématuré au sein de CCDC39, un gène codant pour une protéine enrichie en domaine « coiled-coils ». Tous les chiens atteints possédaient cette mutation à l’état homozygote tandis que leurs parents étaient tous hétérozygotes, confirmant ainsi le mode de transmission autosomique récessif. Après avoir mis au point un test génétique rapide basé sur la technologie Taqman, plus de 500 bobtails ont été génotypés afin d’estimer la fréquence de la mutation au sein de cette race. L’allèle muté se retrouvait plus fréquemment dans la population européenne avec une fréquence d’hétérozygotes autour de 19%. Les hétérozygotes étaient plus rares chez les chiens provenant d’Amérique du nord avec une fréquence d’hétérozygotes de 7%. Plusieurs éléments étaient en faveur du fait que cette mutation était bien la mutation causale. Premièrement, le séquençage d’une population de 80 chiens issus de 9 races différentes, n’a pas permis d’identifier une seule fois cette mutation. De plus, en étudiant l’expression de CCDC39 au sein de l’épithélium respiratoire de chiens porteurs, nous avons mis en évidence un phénomène de dégradation de l’ARNm non-sens. Une nette diminution de l’expression de CCDC39 était visible chez les atteints par rapport aux sains et la protéine était absente des cellules ciliées respiratoires des atteints, contrairement aux chiens contrôles. Nous avons également pu démontrer que CCDC39 était principalement exprimé dans les tissus ciliés chez la souris et chez l’homme. Enfin, pour confirmer définitivement que CCDC39 joue un rôle important dans la mobilité ciliaire, nous avons supprimé son expression à l’aide de morpholinos dans des embryons de zebrafish. L’injection provoquait l’apparition de défauts de latéralité, dose-dépendants. Ce phénotype était spécifique car il disparaissait lorsque les embryons étaient co-injectés avec de l’ARNm sauvage. Vu son implication dans une DCP canine, il était légitime de suspecter que CCDC39 pouvait être à l’origine de cas humains. Nous avons sélectionné une cinquantaine de patients présentant un phénotype ultrastruturel identique à ceux des bobtails atteints. Le séquençage de ces patients a permis d’identifier quinze mutations différentes. Chez la plupart des atteints, ces mutations étaient, soit à l’état homozygote, soit à l’état d’hétérozygote composite. Par contre, nous n’avons pas mis en évidence de mutation au sein de CCDC39 pour une vingtaine de patients atteints de DCP avec un phénotype ultrastructurel différent ou chez plus de 200 patients ne présentant que des défauts de latéralité. Afin de mieux comprendre la fonction de CCDC39 et l’impact de sa dysfonction sur la structure cilaire, nous avons analysé son expression au niveau protéique, en examinant des cellules épithéliales nasales prélevées par frottis brosse. Comme chez le chien, la protéine était absente des cellules épithéliales respiratoires des patients atteints, alors qu’elle était présente chez les contrôles. En utilisant des techniques d’immunofluorescence à haute résolution, nous avons pu démontrer que CCDC39 se localisait principalement au niveau de l’axonème ciliaire chez l’individu sain mais pas chez l’individu atteint. Afin de caractériser l’impact d’une déficience de CCDC39, nous avons étudié les autres composants de l’axonème ciliaire en utilisant des anticorps dirigés spécifiquement sur des sous-unités de l’axonème ciliaire. Nous avons ainsi pu démontrer que l’absence de CCDC39 est responsable d’une absence de certains constituants axonémaux comme les bras de dynéine internes ou le complexe régulateur des dynéines. Enfin, l’analyse du battement ciliaire de certains sujets atteints a permis de mettre en évidence un pattern dyskinétique, caractérisé par une amplitude réduite et des axonèmes rigides. Cette étude a permis d’identifier un nouveau gène impliqué dans les DCP tant dans la race bobtail que chez l’homme. Nous avons pu mettre en évidence que ce gène code pour une protéine axonémale dont l’absence est responsable d’une atteinte des bras de dynéine internes et d’une désorganisation axonémale, ce qui a pour conséquence un battement ciliaire dyskinétique. Le phénotype clinique présenté par les chiens atteints est remarquablement similaire à celui de l’homme, avec une atteinte sévère des voies respiratoires, mais également des anomalies spermatiques chez le mâle et l’existence de défaut de latéralité chez certains atteints. Comme dans la grande majorité des DCP, les individus ne présentent la maladie que s’ils recoivent deux copies défectueuses de CCDC39, puisque nous avons pu montré que tous les chiens atteints étaient homozygotes pour la mutation et que la plupart des patients humains atteints possédaient soit une mutation à l’état homozygote, soit deux mutations différentes. Toutes les mutations identifiées au sein de ce gène sont associées à une perte de fonction et sont vraisemblablement responsables d’une absence de production de la protéine, secondaire à un phénomène de dégradation de l’ARNm, comme nous avons pu le mettre en évidence chez le bobtail. Par la suite, d’autres études ont confirmé cette hypothèse en identifiant de nouvelles mutations au sein de CCDC39, pratiquement toutes liées à une perte de fonction (Blanchon et al., 2012) (Zariwala et al., 2013) (Antony et al., 2013). Les mutations identifiées étaient systématiquement associées à un phénotype ultrastructurel bien particulier représentant environ 12% des cas de DCP (Jorissen et al., 2000b) (Chilvers et al., 2003a) (Papon et al., 2010) (Shoemark et al., 2012). Simultaménent à la découverte de CCDC39, un autre gène, CCDC40, a été identifié comme étant responsable d’un phénotype ultrastrucurel identique. Ces deux gènes sont étroitement liés, puisque l’absence de CCDC40 affecte la localisation axonémale de CCDC39 au sein de la cellule ciliée (Becker-Heck et al., 2010). Ces deux gènes expliquent à eux seuls une grande proportion des patients présentant ce phénotype particulier (Blanchon et al., 2012) (Antony et al., 2013). Nous avons pu démontrer, par différentes méthodes, que ce gène jouait un rôle important dans la structure et la fonction des cils mobiles en observant que son expression était principalement localisée dans les organes présentant des cils mobiles et que la protéine était absente chez des individus porteurs de mutation. De plus, en inactivant l’expression de ce gène dans des embryons de zebrafish, nous avons observé l’apparition de défaut de latéralité ce qui suggère une atteinte des cils mobiles de la vésicule de Kupffer, responsable de l’asymétrie droite gauche. L’identification de ce gène est particulièrement intéressante car CCDC39 a été la première protéine enrichie en domaine « coiled-coils » a être impliquée dans une DCP et a permis de souligner l’importance de ces motifs pour la fonction du cil mobile. Depuis lors, plusieurs autres gènes possédant ces structures particulières ont été associés avec d’autres cas de DCP humaines (Becker-Heck et al., 2010) (Hjeij et al., 2014) (Horani et al., 2013a) (Knowles et al., 2013a) (Panizzi et al., 2012) (Wirschell et al., 2013). Le rôle exact de ces protéines riches en des domaines « coiled-coils » reste à préciser, mais elles semblent jouer un rôle dans la structure du complexe régulateur des dynéines et dans l’ancrage des bras de dynéine aux microtubules adjacents. Cette étude a permis d’identifier le premier gène responsable de DCP dans l’espèce canine. Le génotypage de plus 500 bobtails a permis d’établir que la mutation semble plus fréquente en Europe, ce qui pourrait être lié à l’usage intensif de certains grands champions dans les années 80. La disponibilité de ce test permettra aux éleveurs de dépister les porteurs asymptomatiques et évitera l’apparition de nouveaux atteints. Enfin, cette étude permet de mettre en lumière l’intérêt du chien en tant qu’organisme modèle pour identifier les origines génétiques de certaines pathologies humaines. En effet, le chien représente un modèle unique à bien des égards (Lequarré et al., 2011). Le chien bénéficie de soins médicaux de plus en plus poussés et chaque race de chien représente un isolat génétique, ce qui a pour conséquence une concentration de certains allèles morbides responsables de pathologies similaires à celles de l’homme. On peut ajouter que le chien possède un répertoire génétique très proche de celui de l’homme et que la strucure de son génome est particulièrement intéressante pour disséquer génétiquement des caractères mendéliens, mais aussi des caractères complexes (Lindblad-Toh et al., 2005). Enfin, ou peut imaginer que les bobtails atteints de DCP pourraient représenter une opportunité unique pour tester de nouvelles thérapies et éventuellement pour mettre au point une thérapie ciblée contre le défaut génétique responsable. [less ▲]

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See detailA geometric local frame approach for flexible multibody systems
Sonneville, Valentin ULg

Doctoral thesis (2015)

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and ... [more ▼]

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and systematic way. A frame transformation is thus seen as an element of the special Euclidean group $SE(3)$, which is represented by a four by four transformation matrix, and frame operations, such as spatial interpolation or time integration, rely on non-linear but analytical expressions in which translation and rotation contributions are inherently coupled. Based on this formalism, this thesis develops geometrically exact formulations of many classical components used in flexible multibody system modelling, which includes the formulation of a rigid body, several kinematic joints, a flexible beam, a flexible shell and a superelement. As opposed to most popular techniques in the literature, a local frame representation of the equations of motion is adopted in this work. This means that the unknown kinematic variables such as the motion increments, the velocities and the accelerations, as well as the generalized forces are all expressed in a local frame attached to the body. After spatial semi-discretization, the equations of motion of a multibody system take the form of differential-algebraic equations on a Lie group which can be conveniently solved in a global parametrization-free approach using a Lie group integration scheme. This thesis presents numerous arguments to recommend this framework for the development of efficient codes for the numerical simulation of flexible multibody systems. On the one hand, the proposed framework leads to novel and interesting theoretical aspects. For instance, it features a naturally singularity-free description of large rotations and it leads to inherently shear-locking free beam and shell finite elements. On the other hand, the formulation leads to unprecedented computational properties. The geometric non-linearities are naturally filtered out of the equilibrium equations such that non-linearities are significantly reduced, as compared to classical formulations. In particular, the iteration matrix, which is used in implicit integration schemes, is insensitive to overall large amplitude motions and is only affected by local relative transformations, such as deformations in flexible elements and relative motions in kinematic joints. This property can be exploited to strongly reduce computational costs, as compared to classical formulations. [less ▲]

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See detailExperimental study and modeling of the quasi-static mechanical behavior of Ti6Al4V at room temperature
Gilles, Gaëtan ULg

Doctoral thesis (2015)

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts ... [more ▼]

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts. The first one presents a literature review of the basic properties of titanium and its alloys (crystal structure, classification, deformation mechanisms), then it focuses on the specific mechanical features of Ti6Al4V. It also proposes a state of art in the field of the phenomenological constitutive laws used to model the mechanical behaviors of metals. The second part deals with the experimental campaign conducted on a 0.6 mm thick Ti6Al4V sheet. The devices and the tests are first described before giving the test results. The campaign includes experiments with monotonic and complex strain paths (tension, compression, simple shear, plane strain, Bauschinger tests, deep-drawing processes, layer compression tests). The experimental results show that the material displays anisotropy in yield stress, r-ratios and hardening, as well as a strength differential effect between tension and compression. The third part describes the implementation of the yield criteria CPB06exn in the non-linear finite element code LAGAMINE developed in MSM team. These criteria are selected to model the yield locus of Ti6Al4V since they are able to take into account both the anisotropy and the tension-compression asymmetry exhibited by the alloy. Several parameter identifications are performed using the classical simulated annealing algorithm. They determine that CPB06ex2 is required to represent the yield surface. The criterion is next associated to different hardening formulations: (1) Voce isotropic law; (2) mixed Voce isotropic – Armstrong-Frederick kinematic law; (3) model taking into account the evolution of the yield locus shape with the deformation. The identification of the hardening parameters is achieved from the monotonic and Bauschinger tests either by inverse method, or by the simulated annealing method. The last part of the thesis proposed a validation of the different modelings in the case of the layer compression tests and the deep-drawing processes. [less ▲]

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See detailEvaluation des systèmes de management de la sécurité et de la qualité de l’aquaculture du tilapia du Nil "Oreochromis niloticus" dans l’Ouest algérien.
Dergal, Nadir Boudjlal ULg

Doctoral thesis (2015)

Cette thèse a été entreprise afin d’élaborer et de développer le premier modèle HACCP spécifique pour la gestion de la qualité ante et post mortem du tilapia (Oreochromis niloticus) produit au niveau de ... [more ▼]

Cette thèse a été entreprise afin d’élaborer et de développer le premier modèle HACCP spécifique pour la gestion de la qualité ante et post mortem du tilapia (Oreochromis niloticus) produit au niveau de la ferme continentale "Fat-Steppes" (Ouest algérien). Pour ce faire, différents points critiques (PCC) ont été déterminés et maitrisés tout au long de la phase d’élevage et de commercialisation. Durant la phase d’élevage, les résidus d’antibiotiques, les résidus de la 17α-méthyle testostérone et la qualité microbiologique et physicochimique de l’eau et de l’aliment d’élevage ont été évalués. Une stratégie analytique pertinente a été développée basée sur une première technique microbiologique de screening qui a été améliorée et partiellement validée pour l’identification des tétracyclines et des fluoroquinolones. Suivie d’une seconde technique LC-UV-MS qui a été spécialement optimisée pour l’identification et la quantification de l’acide oxolinique. Une nouvelle méthode d’extraction, compatible avec un test immuno-enzymatique ELISA (enzyme-linked immunosorbent assay), a été optimisée pour la détection des résidus de 17α-méthyle testostérone (MT) dans la chair du poisson, dans l’eau et l’aliment d’élevage. Le profil nutritionnel du tilapia produit à Fat Steppes a été caractérisé en déterminant sa composition en macronutriments, son profil en acides gras et en acide aminés. Par la suite, l’évolution temporelle de la qualité hygiénique, du tilapia conservé à 4°C et 30°C, a été évaluée par une approche sensorielle, microbiologique (Flore Mésophile Aérobie Totale et Entérobactéries) et biochimique. L’analyse des diènes conjuguées, des hydroperoxydes et des TBARS "Thiobarbituric acid reactive substances" a servi pour évaluer l’oxydation lipidique. L’analyse d’azote basique volatil totat "ABVT", la triméthylamine "TMA" et les amines biogènes a servi pour évaluer la protéolyse bactérienne et enzymatique. Les résultats obtenus ont démontrés des performances satisfaisantes des deux techniques d’analyse des résidus d’antibiotiques. La capacité de détection (CCß) du test de screening est de 0,75 fois la limite maximale de résidus (LMR) de l’acide oxolinique (OXO) et la limite de la quantification chromatographique LC/UV est de LMR/20. Le délai d’attente de l’OXO est estimé à 8 jours après un traitement de six jours successifs avec une dose de 12 mg/ kg de poids vif. La nouvelle méthode d’extraction des résidus d’MT est acceptable en termes de rendement d’extraction (55 % pour la chair et 85 % pour l'eau) et de linéarité (R2 = 0,998). Le délai d’attente des résidus de la MT est estimé à deux mois après un traitement avec une dose ≤ 65 mg MT/kg d’aliment, pendant 28 jours, à partir du 10ème jour post-éclosion. Des seuils microbiologiques de 103 ufc/100 ml de coliformes fécaux et de 3 x 106 ufc/g de flore mésophile aérobie totale (FMAT) sont retenus comme critères de bonne qualité microbiologique de l’eau et de l’aliment d’élevage respectivement. Le tilapia algérien est considéré comme un poisson maigre (± 0,33 % de lipide) et riche en protéines (± 17,3 %). Son profil en acides aminés essentiels et en acides gras polyinsaturés est relativement intéressant. Les paramètres de performance de la nouvelle méthode HPTLC "High Performance Thin Layer Chromatography", développée pour le screening et la quantification de six amines biogènes d’intérêt, sont satisfaisants en termes de linéarité (R2 > 0,98), de justesse (> 84 %), de fidélité. La limite de détection (LOD) de la méthode HPTLC est de l’ordre de 5 µg.g-1 de chair de poisson. Les résultats de l’analyse organoleptique, microbiologique et biochimique sont fortement et positivement corrélés et révèlent que la date d’utilisation optimale du tilapia est limitée à 12 heures et à 5 jours de conservation à 30°C et à 4°C respectivement. Après ces délais, le poisson est rejeté par l’appréciation organoleptique et tous les seuils critiques établis dans ce travail sont dépassés. Des valeurs de l’ordre de : 6 log cfu g-1 pour les FMAT et les entérobactéries, 0,85 mg MDA kg-1 de poids humide, 35 mg ABVT-N 100 g-1 de chair, 8 mg TMA-N 100 g-1 de chair, 100 µg.g-1 de putrescine et de cadavérine sont retenus comme critères microbiologiques et biochimiques respectivement. [less ▲]

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See detailSatellite Orbits in the Atmosphere: Uncertainty Quantification, Propagation and Optimal Control
Dell'Elce, Lamberto ULg

Doctoral thesis (2015)

From the massive international space station to nanosatellites, all space missions share a common principle: orbiting an object requires energy. The greater the satellite's mass, the higher the launch ... [more ▼]

From the massive international space station to nanosatellites, all space missions share a common principle: orbiting an object requires energy. The greater the satellite's mass, the higher the launch cost. In astrodynamics, this translates into the motto ``use whatever you can''. This concept encompasses a broad spectrum of missions, e.g., the Earth's oblateness is exploited for sun-synchronous orbits and the kinetic energy of a planet is used to accomplish fly-by maneuvers. Nowadays, the same paradigm is coming on stream in the context of distributed space systems, where complex missions are envisaged by splitting the workload of a single satellite into multiple agents. Orbital perturbations -- often regarded as disturbances -- can be turned into an opportunity to control the relative motion of the agents in order to reduce or even remove the need for on-board propellant. This thesis is an attempt to combine uncertainty quantification, analytical propagation, and optimal control of satellite trajectories in the atmosphere for effectively and robustly exploiting the aerodynamic force. Specifically, by means of a probabilistic estimation and prediction of the aerodynamic force and an efficient and consistent propagation of low-Earth orbits, a robust reference trajectory for the realization of relative maneuvers between two satellites in a realistic environment can be generated. [less ▲]

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See detailLa jurisprudence de la Cour constitutionnelle en procédure pénale : le Code d'instruction criminelle remodelé par le procès équitable ?
Michiels, Olivier ULg

Doctoral thesis (2015)

INTRODUCTION GÉNÉRALE Ma dissertation doctorale porte sur une question simple qui peut succinctement se résumer de la manière suivante : la Cour constitutionnelle développe-t-elle un modèle de procédure ... [more ▼]

INTRODUCTION GÉNÉRALE Ma dissertation doctorale porte sur une question simple qui peut succinctement se résumer de la manière suivante : la Cour constitutionnelle développe-t-elle un modèle de procédure pénale ? Cette question me paraissait intéressante dès lors que l’extension du socle de compétence de la Cour constitutionnelle au titre II de la Constitution a considérablement renforcé la « constitutionnalisation » du droit pénal sensu lato et que le catalogue constitutionnel belge des droits fondamentaux a subi un véritable bouleversement à la suite de l’évolution des droits et libertés garantis par les instruments internationaux, dont la Convention européenne des droits de l’homme. Afin de disposer des bases nécessaires pour appréhender ce sujet d’étude, il convenait, d’une part, de déterminer les possibilités d’action de la Cour constitutionnelle dès l’instant où sa saisine se réalise par voie de questions préjudicielles ou de recours en annulation et de cerner l’éventuelle ingéniosité juridique que la doctrine prête à la Cour pour étendre son analyse au delà de la vision manichéenne de la constitutionnalité. D’autre part, il était nécessaire de procéder à une recension des arrêts prononcés par la Cour constitutionnelle, dans le but toujours de vérifier si, et, le cas échéant, comment la Cour s’inscrit ou non dans une logique définie de la procédure pénale. J’ai, dès lors, après avoir rappelé le socle de compétence de la Cour constitutionnelle, la manière dont cette dernière est saisie et les techniques récurrentes auxquelles la Cour recourt dans la construction de ses arrêts, procédé à un inventaire des principaux arrêts prononcés par la Cour constitutionnelle en procédure pénale. Sciemment, j’ai pris comme point de départ de cette recension l’année 1998 qui a vu entrer en vigueur la loi du 12 mars 1998, dite Franchimont, dont le but était de donner un cadre légal et résolument actuel à l’information et à l’instruction. Une fois ce travail réalisé, j’ai entrepris de déterminer s’il était possible de dégager des prises de position répétées de la Cour qui s’imposeraient comme autant de « fondamentaux » qui jalonnent la procédure pénale. QUELS SONT LES FONDAMENTAUX DE LA COUR CONSTITUTIONNELLE EN PROCEDURE PENALE ? De la jurisprudence de la Cour constitutionnelle, il me paraît qu’il est possible de dégager 7 fondamentaux qui balisent la procédure pénale. 1. LA DISTINCTION ENTRE LES PARTIES AU PROCES PENAL ET LES PHASES PROCEDURALES 1. L’on sait que la Cour constitutionnelle estime qu’il existe une différence fondamentale entre le ministère public, d’une part, et l’inculpé et la partie civile, d’autre part. Pour la Cour, cette distinction repose sur un critère objectif : le premier accomplit, dans l’intérêt de la société, les missions de service public relatives à la recherche et à la poursuite des infractions ; les seconds défendent leur intérêt personnel . Cette différence justifie raisonnablement que, tout particulièrement au long de l'instruction, le ministère public jouisse de prérogatives dont la constitutionnalité ne peut être appréciée en procédant à une comparaison de sa situation avec celle de l'inculpé. 2. Lors de la phase du jugement, la différence tend à s’amenuiser. Il serait toutefois hasardeux de soutenir que le ministère public devient une partie comme les autres. En effet, par la Cour de cassation – dans un arrêt du 19 décembre 2012 discuté dont l’analyse m’éloignerait de mon sujet – retient que « la mission impartie au ministère public ne se réduit pas à celle d’un accusateur. Il intervient aussi au procès pour proposer au juge une solution de justice ». La Cour constitutionnelle insiste pareillement sur le rôle imparti au ministère public qui ne se cantonne pas à celui d’une simple partie au procès pénal au regard des missions qui sont les siennes. Cependant, si la distinction entre les différentes parties au procès répressif repose sur un critère objectif, la Cour constitutionnelle m’admettrait pas que cette seule différence puisse porter atteinte au principe de l’égalité des armes ce qui l’amènerait inévitablement à rétablir l’égalité. 2. LE DROIT D’ACCES AU JUGE 3. L’approche de la Cour constitutionnelle quant au droit d’accès à un tribunal est tout en nuance. Pour la Cour, ce droit peut ne pas être absolu et peut souffrir de limitations. Ainsi, la Cour insiste sur le fait que si le droit d’accès au juge peut être soumis à des conditions de recevabilité, celles-ci ne peuvent aboutir à restreindre le droit de manière telle qu’il s’en trouve atteint dans sa substance même. Une telle motivation n’est pas sans rappeler la jurisprudence de la Cour européenne des droits de l’homme sur le sujet. En effet, pour la Cour européenne des droits de l’homme, « ce droit d’accès au tribunal se trouve atteint lorsque sa réglementation cesse de servir les buts de la sécurité juridique et de la bonne administration de la justice et constitue une sorte de barrière qui empêche le justiciable de voir son litige tranché au fond par la juridiction compétente ». On aperçoit immédiatement que, la question du droit d’accès au juge est, sous certains aspects, intimement liée à celle du formalisme procédural. 3. LE FORMALISME PROCEDURAL 4. Par l’examen des règles de forme, la Cour renforce le contrôle qu’elle porte sur le droit d’accès au juge. En effet, la Cour en réalisant une distinction entre les règles de fond – entendues comme le droit garanti ou protégé – et de forme –qui déterminent les manières de procéder –elle confère un volet substantiel à certaines règles procédurales. Ce faisant, la Cour garantit l’effectivité du droit revendiqué qui est souvent dépendante de la protection procédurale qui l’encadre. 4. LA NON-INTERFERENCE DANS LES CHOIX D’OPPORTUNITE DU LEGISLATEUR 5. La Cour constitutionnelle ne se prononce pas sur le caractère approprié ou non du choix opéré par le législateur. Elle n’est pas le juge de « l’opportunité législative ».Son contrôle porte, en fait, sur l’adéquation d’une mesure au but recherché et l’existence d’un rapport raisonnable entre les moyens employés et l’objectif visé. Cependant, à nouveau, la Cour s’autorisera à sanctionner le choix du législateur s’il était porté atteinte, sans justification raisonnable, aux droits d’une catégorie de citoyens. 5. LE RESPECT DES DROITS DE LA DEFENSE 6. Au fil de sa jurisprudence, la Cour constitutionnelle se montre intensément attentive au respect des droits de la défense et au droit à un procès équitable qui, à vrai dire, sont l’essence même de la procédure pénale. La Cour veille, au stade du jugement, à assurer l’égalité des armes entre l’accusation et la défense à laquelle le droit à la contradiction est étroitement lié. Pour la Cour constitutionnelle, l’effectivité des droits de la défense passe encore par la protection de la relation de confiance qui doit se créer entre le justiciable et l’avocat qui le conseille et le défend. Le secret professionnel de l’avocat constitue « l’un des principes fondamentaux sur lesquels repose l’organisation de la justice dans une société démocratique ». 7. De manière globale, on notera que la notion de droits de la défense garantie par la Cour constitutionnelle est viscéralement marquée du sceau de la jurisprudence de la Cour européenne des droits de l’homme mais il lui revient d’intégrer ces données dans le système procédural belge en ayant égard aux choix réalisés par le législateur. 6. LA DIFFERENCIATION ENTRE LES PROCEDURES JUDICIAIRES 8. La Cour semble, a priori, rejeter une comparaison d’office entre les règles de la procédure civile et celles de la procédure pénale quand bien même la première constitue le droit commun. La Cour rappelle que vouloir établir un parallélisme entre les règles de la procédure civile et celles de la procédure pénale n’est pas nécessairement pertinent. En effet, l’application de règles procédurales différentes dans des circonstances différentes n’implique pas en soi l’émergence d’une discrimination. 7. LA PREVISIBILITE 9. Certains arrêts prononcés par la Cour constitutionnelle permettent de mettre en lumière l’importance que cette dernière accorde à la condition de prévisibilité. En droit pénal, sensu stricto, la Cour a pu rappeler qu’il découle de l’article 12, alinéa 2, de la Constitution que la loi pénale doit être formulée en des termes qui permettent à chacun de connaître, au moment où il adopte un comportement, si ce comportement est punissable ou non et la peine éventuellement encourue. Les principes de légalité et de prévisibilité ne se cantonnent toutefois pas au droit pénal, sensu stricto, mais sont applicables à l’ensemble de la procédure pénale en ce compris aux stades de l’information et de l’instruction. Ces principes entendent exclure tout risque d’intervention arbitraire de la part du pouvoir exécutif ou du pouvoir judiciaire dans l’établissement et l’application des peines. En somme, l’exigence de prévisibilité de la procédure pénale garantit à tout citoyen qu’il ne pourra faire l’objet d’une information, d’une instruction et de poursuites que selon une procédure établie par la loi et dont il peut prendre connaissance avant sa mise en oeuvre. CHAPITRE 3. VERS LA RECOMPOSITION DE LA PROCEDURE PENALE ? 10. Si, pour ma part, la Cour constitutionnelle dégage des « principes constants » qu’elle s’astreint à respecter, peut-on nécessairement en déduire que la Cour entend s’inscrire dans un modèle précis de procédure pénale ? Pour appréhender cette question, il convient naturellement d’apprécier si la Cour constitutionnelle, par les orientations qu’elle confère à ses arrêts, ouvre au juge judiciaire des perspectives qui lui permettront de se libérer d’une interprétation traditionnelle de la norme pour satisfaire aux exigences d’aujourd’hui envisagées sous l’angle du respect de la personne et de ses droits fondamentaux ? Il me paraît que la Cour y parvient par le recours au dialogue des jurisprudences. 1. LE DIALOGUE DES JURISPRUDENCES 11. Le dialogue des jurisprudences se caractérise par l’emprunt de motivations émanant de juridictions nationales ou de juridictions étrangères ou internationales qui deviennent décisoires dans les arrêts de la Cour constitutionnelle. 12. La Cour constitutionnelle s’est résolument et immédiatement positionnée en faveur du dialogue des jurisprudences. Nombre des arrêts que nous avons répertoriés se réfèrent expressément à la jurisprudence de la Cour européenne des droits de l’homme dont elle fait sien les enseignements. Au fil des années, les emprunts à la jurisprudence strasbourgeoise se sont accentués et non plus seulement en termes de référence mais encore en termes de contenu. La suprématie, selon la Cour constitutionnelle, de notre Charte fondamentale sur la Convention européenne des droits de l’homme n’enraie nullement ce dialogue. Par ces emprunts, la Cour constitutionnelle renforce, selon moi, ces « principes fondamentaux », et par là même leur autorité persuasive, en s’appuyant sur la notoriété et le rayonnement international de la Cour européenne des droits de l’homme. Un tel dialogue contribue à promouvoir le caractère universel des garanties fondamentales inhérentes au procès pénal et oblige à la confrontation des idées entre les juridictions ce qui doit permettre, me semble-t-il, de surmonter les tensions entre elle et la Cour de cassation. Il est vrai que ces deux hautes juridictions s’affrontent sur certains points, mais ces divergences ne doivent pas être exagérées car je persiste à penser que ces deux Cours doivent avoir l’intelligence stratégique de coordonner leur interprétation, dès lors que de telles divergences de jurisprudence en procédure pénale le sont toujours au détriment du justiciable alors que le but premier des règles de procédure est d’assurer la protection des droits fondamentaux de ce dernier. Ceci étant ce dialogue des jurisprudences ne va-t-il pas faire craindre l’émergence d’une « oligarchie » des juges et à plus forte raison que des juges pourraient s’émanciper par rapport à la loi en saisissant d’autres juges qui pourraient mettre le législateur « hors jeu »? 2. L’ « OLIGARCHIE » DES JUGES 13. Je crois qu’il ne faut pas amplifier le phénomène car la Cour constitutionnelle privilégie l’interprétation téléologique et rappelons-le elle n’entend pas, en règle, substituer son appréciation à celle du législateur si le choix est raisonnable. Par ailleurs, pour faire très bref, la Cour constitutionnelle devient le lieu de débats et d’échanges d’arguments où le travail légistique est réexaminé au regard des droits et libertés garantis par la Constitution couplés bien souvent à la Convention européenne des droits de l’homme. Si bien que les juges constitutionnels belges et, par ricochet le législateur, lorsqu’il obtempère aux injonctions qui lui sont faites par ces derniers, s’alignent sur l’appréciation de l’équité du procès telle qu’elle se dégage des positions adoptées par la Cour européenne des droits de l’homme. Mais le pouvoir du dernier mot appartient au législateur. 14. A l’inverse ne pourrait-on penser que de facto en raison de la composition de la Cour qui contient en son sein d’anciens mandataires politiques, le pouvoir législatif ne garde-t-il pas une certaine mainmise sur le contrôle de la constitutionnalité des lois ? 3. LA COMPOSITION DE LA COUR CONSTITUTIONNELLE Répondre à cette question relève du divinatoire et poserait en postulat que le juge, ancien parlementaire, serait un défenseur de la norme critiquée ce qui ne peut scientifiquement être démontré. Il ne paraît, dès lors, qu’il s’agit là d’une crainte infondée. Un dernier point doit, en revanche, être souligné : le pragmatisme et le conséquentialisme de la Cour. CHAPITRE 4. PRAGMATISME ET CONSEQUENTIALISME DE LA COUR CONSTITUTIONNELLE 15. Une autre grande tendance se dégage des arrêts analysés, le pragmatisme dont fait preuve la Cour dans le but d’assurer une véritable praticabilité à la procédure. 16. En parallèle au pragmatisme, le moyen conséquentialiste ne peut être négligé. Bien évidemment, tous les arrêts prononcés par la Cour ont nécessairement une conséquence dans leur sphère d’application. En l’espèce, par conséquentialisme il faut entendre plus précisément les positions adoptées par la Cour qui sont teintées de réalisme « politique » qui répond à des impératifs budgétaires ou de sécurité nationale ou encore à une volonté populaire. Ces données réelles et par toujours facile à identifier peuvent évidemment constituer autant des contraintes susceptibles de limiter la liberté d’appréciation par la Cour d’un modèle de procédure pénale. CONCLUSIONS 17. Alors, en définitive, est-il possible de répondre à ma question initiale : la Cour constitutionnelle développe-t-elle un modèle de procédure pénale ? A l’examen, il paraît illusoire, voire naïf, de vouloir répondre à cette interrogation de manière catégorique. Une telle réponse manquerait de nuances et prêterait nécessairement le flanc à la critique. Il faut donc procéder par touches successives et observer que le critère phare du raisonnement de la Cour constitutionnelle devient celui de l’équité du procès. La Cour n’en garde pas moins à l’esprit qu’elle doit maintenir la cohérence du système juridique dans lequel elle se meut et que ses interventions sont, somme toute, conditionnées par les recours et les questions qui lui sont adressés et qui dépendront, pour ces dernières, de l’attitude adoptée par le juge a quo. Par ailleurs, la Cour ne manque pas de souligner que la procédure pénale reste encadrée par le principe de légalité sans que la marge de manœuvre du pouvoir judiciaire – et de la Cour constitutionnelle elle-même – ne puisse jamais aller au-delà d’une interprétation raisonnablement prévisible des règles de procédure fixées par le seul législateur. Enfin, l’argument conséquentialiste, qu’il n’est pas toujours aisé de distinguer dans le raisonnement de la Cour, peut complètement chambouler la grille de lecture que l’analyste tenterait de dresser. En conclusion, s’il ne fallait retenir qu’une chose de ma thèse c’est que la si la Cour constitutionnelle ne développe pas un modèle de procédure pénale, il n’en est pas moins vrai, qu’à l’aulne du procès équitable, dont il ne paraît guère possible de cerner le périmètre d’action, elle refaçonne résolument cette procédure. [less ▲]

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See detailGraded-commutative nonassociative algebras: higher octonions and Krichever-Novikov superalgebras; their structures, combinatorics and non-trivial cocycles.
Kreusch, Marie ULg

Doctoral thesis (2015)

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra ... [more ▼]

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra of octonion numbers $\bbO$. This generalization is similar to the one of the algebra of quaternion numbers in Clifford algebras. Introduced by Morier-Genoud and Ovsienko, these algebras have a natural $\bbZ_2^n$-grading ($p+q =n$), and they are characterized by a cubic form over the field $\bbZ_2.$ We establish all the possible isomorphisms between the algebras $\bbO_{p,q}$ preserving the structure of $\bbZ_2^n$-graded algebra. The classification table of $\bbO_{p,q}$ is quite similar to that of the real Clifford algebras $\cC l_{p,q}$, the main difference is that the algebras $\bbO_{n,0}$ and $\bbO_{0,n}$ are exceptional. We also provide a periodicity for the algebras $\bbO_n$ and $\bbO_{p,q}$ analogous to the periodicity for the Clifford algebras $\cC l_{n}$ and $\cC l_{p,q}$. In the second part we consider superalgebras of Krichever-Novikov (K-N) type. Krichever and Novikov introduced a family of Lie algebras with two marked points generalizing the Witt algebra and its central extension called the Virasoro algebra. The K-N Lie (super)algebras for more than two marked points were studied by Schlichenmaier. In particular, he extended the explicit formula of $2$-cocycles due to Krichever and Novikov to multiple-point situation. We give an explicit construction of central extensions of Lie superalgebras of K-N type and we establish a $1$-cocycle with values in its dual space. In the case of Jordan superalgebras related to superalgebras of K-N type, we calculate a 1-cocycle with coefficients in the dual space. [less ▲]

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See detailPhotochemical generation of reactive oxygen species using plasmonic nanoparticles
Lismont, Marjorie ULg

Doctoral thesis (2015)

During his lecture entitled “ There is plenty of room at the bottom ”, Richard Feyn- man foresaw the possibility of manipulating material at the scale of individual atoms and molecules. Although Feynman’s ... [more ▼]

During his lecture entitled “ There is plenty of room at the bottom ”, Richard Feyn- man foresaw the possibility of manipulating material at the scale of individual atoms and molecules. Although Feynman’s conceptual idea of a nanoworld was evoked in 1959, the nanoscience and nanotechnology revolution began 30 years later with the ability to see at the atomic scale with the invention of electronic microscopy and related tools. The size range that has attracted so much attention over these last 30 years is typically from 100 nanometers down to the atomic level. Subsequently, nanomaterials were defined as materials, which have structured components with at least one dimension in this size range. For instance, material with three nanometric dimensions defines a nanoparticle. Among the variety of core materials available to synthesize nanoparticles, noble metal nanoparticles, i.e. gold and silver, have fascinated people for centuries owing to their bright and intense colors, used in particular as decorative pigments in cathedral stained glasses and artworks. The red and yellow colors displayed by gold and silver nanoparti- cles arise from their interaction with light, which one induces collective oscillations of free electrons at the nanoparticle surface in resonance with the light field. This phenomenon is commonly known as the localized surface plasmon resonance. Their remarkable optical properties and the intense electric field generated by plasmonics nanoparticles have brought these nanomaterials in the forefront of nanotechnology research, ranging from photonics to medicine. Shining light on plasmonic nanoparticles to push back limitations of light-activated therapy and so taking part to the societal challenge of cancer treatment improvement defines the global framework of the thesis. Falling within the nanomedicine topic, this one more precisely deals with the development of efficient plasmonic nano-drugs using light to cure diseases. Clearly, nanoplasmonics, which explores how electromagnetic field can be confined over dimension on the order or smaller than the wavelength of light, has come a long way since the stained glass of Roman times. [less ▲]

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See detailPolyphosphate-based amphiphilic copolymers: synthesis and application to drug nanocarriers
Vanslambrouck, Stéphanie ULg

Doctoral thesis (2015)

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications, especially for drug delivery systems. In contrast to aliphatic polyesters ... [more ▼]

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications, especially for drug delivery systems. In contrast to aliphatic polyesters, such as poly(?-caprolactone) and poly(lactide), the pentavalency of phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendants groups. The goal of this thesis focused on the design of drug nanocarriers based on amphiphilic block copolymer micelles well-suited for the encapsulation of poorly soluble drugs. For that purpose, novel diblock copolymers composed of a water-soluble poly(ethylene oxide) block and a polyphosphate block bearing a variety of alkyl side-groups were synthesized. Firstly, n- butyl, i-butyl and n-heptyl cyclic phosphate monomers were synthesized and used for the organo-catalyzed ring-opening polymerization providing a range of PEO-b-polyphosphate amphiphilic copolymers varying by the architecture and length of the polyphosphate pendant group. Then, post-polymerization thiol-ene click reactions on preformed PEO-b- polybutenylphosphate copolymer was used to graft dodecyl or tocopherol side-chains on the polyphosphate block.The micellization of these amphiphilic block copolymers in aqueous medium was then investigated and a comparative study of the encapsulation and release of a poorly soluble model drug, i.e. ketoconazole, was carried out. Ultimately, the synthesis of a triblock copolymer was investigated to prepare shell- crosslinked core-shell-corona micelles to improve the nanoparticles stability. [less ▲]

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See detailThe System for Adressing Personal Problems-From medicalisation to Socialisation: Shifts in Belgian Psychiatric and Mental Health Institutions
Thunus, Sophie ULg

Doctoral thesis (2015)

My PhD thesis related the growth of a large social system devoted to the treatment of personal problems; i.e. problems successively labelled as madness, mental illness and mental health problems, from the ... [more ▼]

My PhD thesis related the growth of a large social system devoted to the treatment of personal problems; i.e. problems successively labelled as madness, mental illness and mental health problems, from the early fifties to the present days. That system involved heterogeneous networks of actors, including scientific experts, established professions, social movements, policy makers, services users and international organisations; instruments and knowledge ranging from psychoanalytical theories to biological knowledge and models of governance. It meant to explain how institutional change happened in that complex social system, by studying past and ongoing reforms, considered as interrelated steps towards complete paradigm shift, including shifting policy means, policy objectives and social organisation. By relying on in-depth analyses of five past reforms, it conceptualised the system as composed of interrelated ecologies, corresponding to different kinds of knowledge of personal problems, whose development was directed by protective and expansion strategies used by two coalitions of actors, holding different kinds of resources to influence the change process. The traditional coalition was embedded in the Belgian institutional system; it referred to medical knowledge of personal problems; and held many institutions delivering residential treatments. By contrast, the reformist coalition was connected to international professional and policy networks stimulating change in OECD-mental health systems; it referred to practical knowledge of social psychiatry and evidence produced by international organisations as the World Health Organisation; and it held non-profit associations delivering community treatments. Cross-regulations exerted through joint-participation of those coalitions in successive reforms caused rapid changes in the system’s structural configuration while hindering change in its social organisation. Thus, we suggested thinking of the issue of change in the system as consisting in setting conditions in which the reformist coalition might extensively use its resources in conducting a new reform starting in 2010. By relying on that assumption, I presented three case studies analysing the devising of that reform at the policy level and its implementing through local networks. Those case studies drew attention to the kinds of knowledge used by key actors and to the way in which they used it in joint-attempts to take the leadership of the reform. Three main findings resulted from those case studies. First, the designing of the policy guide framing the reform consisted in assembling different kinds of knowledge together, including policy learning achieved through past changes in the system and knowledge of alternative care models implemented in OECD-countries, in a way that encouraged sustained enactments of knowledge specific to the reformist coalition, while decreasing the relevance of resources specific to the traditional coalition. Second, local meetings caused by the implementing of the reform enabled adaptations of knowledge embodied by the participants, i.e. multiple actors representing different ecologies and members of one of the two coalitions, to enacted knowledge, i.e. knowledge collectively produced by thinking about concrete means to implement the reform locally. Third, enacted knowledge caused, in turn, adaptations of the care model inscribed in the policy guide to local particularities. Those adaptations did not prevent, however, the global philosophy of the new reform, inspired by social psychiatry, from pervading in local networks, among other by being inscribed in operational documents resulting from meetings. Thus, by following the policy guide through local networks where it was translated into concrete practices, I have been able to indicate new directions in the global process of change in the system, towards a complete paradigm shift, from medical to social psychiatry, and to highlight social and learning processes making it possible. [less ▲]

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See detailNonparametric and bootstrap techniques applied to financial risk modeling
Hambuckers, julien ULg

Doctoral thesis (2015)

For the purpose of quantifying financial risks, risk managers need to model the behavior of financial variables. However, the construction of such mathematical models is a difficult task that requires ... [more ▼]

For the purpose of quantifying financial risks, risk managers need to model the behavior of financial variables. However, the construction of such mathematical models is a difficult task that requires careful statistical approaches. Among the important choices that must be addressed,we can list the error distribution, the structure of the variance process, the relationship between parameters of interest and explanatory variables. In particular, one may avoid procedures that rely either on too rigid parametric assumptions or on inefficient estimation procedures. In this thesis, we develop statistical procedures that tackle some of these issues, in the context of three financial risk modelling applications. In the first application, we are interested in selecting the error distribution in a multiplicative heteroscedastic model without relying on a parametric volatility assumption. To avoid this uncertainty, we develop a set of model estimation and selection tests relying on nonparametric volatility estimators and focusing on the tails of the distribution. We illustrate this technique on UBS, BOVESPA and EUR/USD daily stock returns. In the second application, we are concerned by modeling the tail of the operational losses severity distribution, conditionally to several covariates. We develop a flexible conditional GPD model, where the shape parameter is an unspecified link function (nonparametric part) of a linear combination of covariates (single index part), avoiding the curse of dimensionality. We apply successfully this technique on two original databases, using macroeconomic and firm-specific variables as covariates. In the last application, we provide an efficient way to estimate the predictive ability of trading algorithms. Instead of relying on subjective and noisy sample splitting techniques, we propose an adaptation of the .632 bootstrap technique to the time series context. We apply these techniques on stock prices to compare 12,000 trading rules parametrizations and show that none can beat a simple buy-and-hold strategy. [less ▲]

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See detailOn-line Dynamic Security Assessment in Power Systems.
Weckesser, Johannes ULg

Doctoral thesis (2015)

The thesis concerns the development of tools and methods for on-line dynamic security assessment (DSA). In a future power system with low-dependence or even independence of fossil fuels, generation will ... [more ▼]

The thesis concerns the development of tools and methods for on-line dynamic security assessment (DSA). In a future power system with low-dependence or even independence of fossil fuels, generation will be based to a large extent on non-controllable renewable energy sources (RES), such as wind and solar radiation. Moreover, ongoing research suggests that demand response will be introduced to maintain power balance between generation and consumption at all times. % as well as to account for forecasting inaccuracies related to power generation from RES. Due to these changes, the operating point of the power system will be less predictable. Consequently, today's stability and security assessment tools, which are generally dependent on extensive off-line studies, may no longer be feasible in their current development state. A core component of an efficient on-line dynamic security assessment is a fast and reliable contingency screening. As part of this thesis a contingency screening method is developed and its performance is assessed utilizing a set of test cases. The developed method reliably assesses first-swing transient angular stability of a power system in its current state with respect to a given set of contingencies. In order to ensure fast performance of the screening method, first a review of existing transient stability assessment (TSA) methods was carried out and their computational complexity was investigated. This allowed to identify the single machine equivalent (SIME) method as the potentially fastest assessment method and, hence, well suited for on-line DSA. Means for further performance improvement of the SIME method are investigated such as the reduction of the degree of system model detail used in time-domain simulation. This results in a recommendation for the required model detail for synchronous generator. A challenging task when using the SIME method is to early and reliably determine the critical machine cluster, which is the group of generators likely to lose synchronism. Therefore, a novel approach to identify the critical machine cluster is proposed in the thesis. This approach uses a new coupling coefficient, which is a measure of the coupling strength of pairs of generators, and a simple clustering algorithm to identify the critical group of generators. In order to determine a system to be transient secure, it is not sufficient to solely assess if all synchronous generators remain in synchronism, it is also required that the bus voltages remain within acceptable limits. A transient disturbance and the following angular divergence of a group of generators can cause critical voltage sags at certain buses in the system. In this thesis assessment of such voltage sags is proposed using two types of sensitivities, which are derived from the algebraic network equations. These sensitivities are derived after an in-depth study of the mechanism causing the voltage sags. The first sensitivity type is called load voltage sensitivity and allows identifying which bus voltages are affected by a change in rotor angle of a particular generator. % It is shown that the derived load voltage sensitivities for example allow to determine the contribution of each generator to an observed voltage sag, which is valuable information for identifying preventive controls. The second proposed type is called generator power sensitivity, which provides information on the effect of load variation on the generator's power injection. It is shown that the derived sensitivities can give valuable information to identify critical generator-load pairs as well as locations for applying preventive or remedial control measures. Furthermore, the development of a method for early prediction of critical voltage sags is described. The method's performance is compared to other prediction approaches. The results show that the proposed method succeeds in early, accurately and consistently predicting critically low voltage sags. An efficient on-line DSA not only identifies unstable or insecure operation, but also proposes preventive or remedial control actions to restore stability and security in the system. In this thesis a further development of a method for determining real-time remedial action against aperiodic small signal rotor angle instability is described. A real-time aperiodic small signal rotor angle stability assessment method is employed to monitor the respective stability boundary and to compute the respective stability margin of each generator in the system. In case that the stability margin of a particular generator falls below a pre-defined security threshold, the proposed method analytically determines power generation re-dispatch solutions, which restore stable and secure operation in the system. The effectiveness of the method is presented on two test cases in two different test systems. [less ▲]

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See detailDe quels marchés boursiers l’Afrique a-t-elle besoin pour son développement ? Au-delà des illusions, une étude précise de l’attractivité et de l’efficience des marchés boursiers africains
Teuwa Nkeuwo, Mathieu Hugues ULg

Doctoral thesis (2015)

Les marchés boursiers africains ont connu durant ces deux dernières décennies de profondes mutations et une évolution en terme numérique. Face à ces changements et aux impératifs de rentabilité, ces ... [more ▼]

Les marchés boursiers africains ont connu durant ces deux dernières décennies de profondes mutations et une évolution en terme numérique. Face à ces changements et aux impératifs de rentabilité, ces marchés sont entrés dans une logique de concurrence. Ce faisant, ils se doivent aujourd’hui d’offrir à leurs clients des services de qualité supérieure à des coûts compétitifs. Pendant ce temps, le continent africain connaît, depuis ces dernières années, une progression de sa croissance économique et fait l’objet d’attractivité et de convoitise de la part des investisseurs étrangers. L’objectif de cette thèse est de déterminer le type de marché boursier dont l’Afrique a besoin pour stimuler sa croissance économique, dans un environnement concurrentiel marqué par une double évo- lution sous les angles de la croissance économique et de la dynamique des marchés boursiers. Pour atteindre cet objectif, ce travail analyse, d’une part, la relation entre le développement des marchés boursiers et la croissance, l’attractivité et l’ef cience des marchés boursiers africains et examine, d’autre part, le potentiel d’économies d’échelle et/ou de gamme des dépositaires centraux des titres. Des résultats de l’étude, il ressort que les marchés boursiers africains sont, dans l’ensemble, peu attractifs des points de vue de la négociation des investisseurs et de la cotation des entrepri- ses, exceptions faites des bourses de Johannesburg et d’Ile Maurice. La majorité des marchés présentent un potentiel d’économies d’échelle et connaissent néanmoins, des problèmes de gestion stratégique. La thèse révèle que, bien que le développement du marché boursier joue un rôle dans la croissance économique, les marchés boursiers, captés par les indicateurs (scores d’attractivité des entreprises et des investisseurs) stimulent davantage la croissance que lorsqu’ils sont captés par des indicateurs traditionnels (la capitalisation boursière au PIB et le turnover). On peut con- clure qu’il ne suf t pas pour un pays africain de posséder un marché boursier pour béné cier d’un quelconque effet de levier de ce marché sur sa croissance économique, mais qu’il faudrait que ce marché soit performant, compétitif et attractif pour les entreprises et les investisseurs. Dans ce con- texte, la création des marchés boursiers en Afrique ne devrait plus reposer sur des considérations de mode, mais devrait répondre à des besoins et à des perspectives de concurrence prometteuse de développement et de croissance économique. [less ▲]

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See detailAnalyse des propriétés anti-tumorales des exosomes endothéliaux dans le cancer du sein suite au transfert du microARN miR-503
Bovy, Nicolas ULg

Doctoral thesis (2015)

L’angiogenèse est un processus essentiel au développement tumoral ainsi qu’à la dissémination des métastases. De plus, il a été démontré ces dernières années que les miARN, des ARN non codant d'une ... [more ▼]

L’angiogenèse est un processus essentiel au développement tumoral ainsi qu’à la dissémination des métastases. De plus, il a été démontré ces dernières années que les miARN, des ARN non codant d'une vingtaine de nucléotides régulant l’expression des gènes au niveau post-transcriptionnel, jouent un rôle important dans divers processus tumoraux. Ils ont en outre été détectés dans plusieurs fluides biologiques, protégés de la dégradation dans des microvésicules, les exosomes. Cependant, à l’heure actuelle, aucune information n’est connue sur le rôle des exosomes endothéliaux et des miARN qu’ils contiennent sur la croissance tumorale. Au cours de ce travail, nous avons pour la première fois mis en évidence l’existence d’un transfert de miARN des cellules endothéliales vers les cellules tumorales par l’intermédiaire d’exosomes. Nous avons ensuite identifié un miARN, miR-503, dont l’export dans ces microvésicules est modifié en conditions tumorales. L’analyse de la fonction du miARN dans les cellules tumorales de cancer du sein montre qu’il possède des propriétés anti-tumorales en réduisant la prolifération et l’invasion. Nous avons également observé que le miR-503 d’origine endothéliale génère les mêmes effets. Pour expliquer ces résultats, deux cibles du miARN ont été identifiées, CCND2 et CCND3. De plus, l’inhibition de ces dernières conduit au même phénotype qu’une surexpression de miR-503. Nous avons ensuite voulu déterminer si le niveau plasmatique de ce miARN était modulé chez des patientes atteintes de cancer du sein. Nos analyses révèlent une augmentation du niveau sanguin de miR-503 à la suite d’un traitement par chimiothérapie néoadjuvante. Nous avons de plus observé que des cellules endothéliales soumises aux mêmes agents chimiothérapeutiques sécrètent activement du miR-503 dans leurs exosomes. Il semble également que le changement phénotypique induit par miR-503 sur les cellules tumorales modifie leur production en facteurs angiogènes ce qui mène, en retour, à une inhibition de l’angiogenèse. Ces résultats montrent que miR-503 est un miARN anti-tumoral sécrété dans les exosomes de cellules endothéliales. Celui-ci provoque l’inhibition de la prolifération et de l’invasion de cellules tumorales du cancer du sein en ciblant CCND2 et CCND3. Ce processus pourrait être complémentaire des effets directs générés par la chimiothérapie sur la tumeur et favoriser la réponse de l’hôte dans le traitement de la maladie. [less ▲]

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See detailDispositifs de conservation écorégionale et droits indigènes dans l’Amazonie Bolivienne: Les cas des Peuples du Madidi et Pilón Lajas
Marquez Guerra, José Francisco ULg

Doctoral thesis (2015)

The apparatus of conservation at the ecoregional scale integrating natural landscape and cultural landscapes in the Amazon basin has been introduced by international conservation NGOs since the beginning ... [more ▼]

The apparatus of conservation at the ecoregional scale integrating natural landscape and cultural landscapes in the Amazon basin has been introduced by international conservation NGOs since the beginning of the 90s when the term hotspot was invented to designate the importance of "mega-diversity "of tropical forests for the survival of humanity. The representation of environmental problems in the Amazon region as serious threats to life on the planet entered the political agenda of the international community becoming a matter of priority attention. To find solutions to this expanding threat, scientists, activists and interested parties have reflected on some formulas, innovative programs and strategies in order that cooperation and international aid could favor the action of effective conservation and sustainable development. The problem of resource degradation of biodiversity, and the loss of the values of cultural diversity of Amazonian peoples is since then conceived as a challenge that goes beyond national political interests, becoming a global issue. Bolivia was a breeding ground for these pioneering efforts, they have made a pragmatic view of international aid with new tools and effective techniques to combat emerging threats, one of them are financial mechanisms for conservation planning. These have entered the Bolivian legal system from the 80 which coincides with the modernization of the state, an ambitious development plan supported by the implementation of neoliberal measures to promote economic growth, administrative decentralization as a new form to exercise power by delegating powers to the departmental and municipal levels, popular participation, as legitimacy methodology, defining local actors and regional planning policy as a useful management of natural resources for sustainable development. International actors of conservation, a group of scientific elite and environmental activists in the country and leaders of local indigenous movements have played an important role before and after this neoliberal modernization in the implementation of an ecorregional conservation apparatus in the Bolivian Amazon. The objective of this transdisciplinaria research, is an ethnographic description, based on the theoretical and methodological repertoire of legal anthropology and sociology of ANT Translation, of how the practices and strategies of conservation at the ecoregional scale through its technical, financial and legal instruments configure the territories, affect social relations and transform representations and practices of the nature of Amazonian peoples Mosetene, Tsimane' Tacana, Quechua-Tacana and Leco. The traditional spaces of these peoples are in total or partially overlapping with the current Natural Park and Integrated Management Area Madidi and Biosphere Reserve and Indigenous Territory Pilón Lajas implemented as protected areas during the 90 In this context, challenges and current controversies looming over the planning and use of space at different scales between actors of the policies of sustainable development and conservation, local political elites and indigenous peoples. [less ▲]

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See detailUncoupled and coupled hydrogeophysical inversions of seawater intrusion and geothermal hydrologic models
Beaujean, Jean ULg

Doctoral thesis (2015)

Most of humans live in coastal and alluvial plains. Sustainable water supply systems are essential for drinking water production while long-term groundwater access ensures its geothermal use. Owing to ... [more ▼]

Most of humans live in coastal and alluvial plains. Sustainable water supply systems are essential for drinking water production while long-term groundwater access ensures its geothermal use. Owing to climate change and anthropogenic activities, groundwater resources will be increasingly threatened throughout the twenty-first century. In the context of over-development, any effort to overcome groundwater mining at the expense of better understanding groundwater management problems may be misguided. A combination of robust measuring technologies and reliable predictions based on numerical models are necessary to estimate better hydrogeological parameters. Sparse and continuous data are increasingly being used conjunctively in hydrogeological modeling and inverse calibration to alleviate extrapolation and subjective interpretation. In hydrogeology, electrical resistivity tomography (ERT) gives quantitative and qualitative information on salinity and temperature distribution. ERT offers a means for mapping the subsurface hydrogeological structures and the hydrologic process dynamics in both space and time. The integration of ERT data to hydrogeological calibration is particularly suited to define the hydrogeological models quantitatively and qualitatively. In a deterministic framework, hydrogeophysical inversion methods may be particularly useful for predictive analysis and assessment of groundwater pre-emptive management strategies. This work focuses on calibrating physically-based and spatially distributed groundwater flow and transport models with non-to minimally invasive electrical tomography. The general objective is to provide better estimates of hydrogeological parameters on two relevant problems: seawater intrusion in coastal areas and geothermal energy in shallow environments. We compare methods to integrate quantitatively ERT data, possibly other hydrologic or geological data, with existing information to hydrogeological models. Two hydrogeophysical inversion schemes are developped and a thorough comparison of an uncoupled and a coupled quantitative approach based on the use of surface ERT only is performed. The uncoupled hydrogeophysical inversion involves constraining hydraulic parameters using geophysically-derived data and first requires a geophysical inversion, after which the geophysical parameters are converted to hydrologic data through a petrophysical relationship. The inverse hydrological calibration is then performed on these inferred hydrological data. The coupled hydrogeophysical inversion involves constraining hydraulic parameters using geophysical data through a forward hydrogeophysical model in which the hydrologic data are converted to resistivities through a petrophysical relationship. A geophysical forward problem is then solved for the geophysical data. The inverse hydrological calibration is performed on the inferred geophysical observations. In both schemes, we show that an independent geophysical inversion is required to delineate heterogeneous bodies. In this context, we study how to derive informative content of ERT images and therefore ERTderived hydrologic data and ERT-derived geometry. We show that a quantitative appraisal (the cumulative sensitivity) must be used as a proxy for filtering areas correctly resolved. Our developments are demonstrated on several benchmark SWI models (numerical and analytical), a thermohydrologic model and a field test. We show that the reliability of estimated SWI model parameters with the uncoupled approach depends on ERT image appraisal, on geophysical data collection strategy and hydrogeological model conceptualization. The ERT image appraisal plays a key role in retrieving high quality ERT-derived data and helps discriminate different measurement arrays. It is particularly useful in preventing the integration of noise-related artefacts in the conceptualization. We endeavor to quantify the modeling error by a thorough comparison of different strategies to assess the effect of decreasing model conceptual errors to hydrogeological calibration. In the SWI analytical models, we highlight the subjectivity of the uncoupled approach due to the nature of the required hydrologic data (sharp interface). We demonstrate that the conjunctive use of an image appraisal tool with the well-known Ghyben-Herzberg solution is needed to infer reliable ERT-derived observation data. We further demonstrate that a SWI analytical solution may be used to calibrate an equivalent hydraulic parameter based on an ERT dataset generated from a density-dependent groundwater flow model. In the thermohydrologic model, we show that the effectiveness of the uncoupled scheme in calibrating heat transport parameters may be hampered due to the regularization constraint in the geophysical inversion. We demonstrate the importance of a noise level-related filter on the time-lapse ERT images aimed at properly quantifying the spatio-temporal ERTderived temperature changes. We also advocate the use of a physically-based constraint on the ERT-derived temperatures to account for spatial mixing of waters and to cope indirectly with the smoothing effect in the ERT images. In each application, the coupled approach significantly prevails over the uncoupled scheme in terms of reliability of the parameter estimates when no model conceptual error exists. [less ▲]

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See detailLa dynastie belge et la science, 1909-1959
Pirot, Pascal ULg

Doctoral thesis (2015)

The project consists in investigating the role of the Belgian dynasty in scientific development since the beginning of the reign of king Albert I (1909), until the establishment of the National Council ... [more ▼]

The project consists in investigating the role of the Belgian dynasty in scientific development since the beginning of the reign of king Albert I (1909), until the establishment of the National Council for Science Policy (CNPS) in 1959, during king Baudouin's reign, following the publication of the work of the "National Commission on Science" which released its conclusions in the same year. The study deals with the action of the sovereign and the networks he formed with his entourage (the queen, the crown prince, the advisers of the court, some close relations of the king, the ministers in charge of scientific affairs) in the field of science, along various research themes; how these people saw the role of science in society; what influence they had in the development of science (institutions, initiatives, projects); what relationships existed between the dynasty and the scientific institutions; what the relationships between the dynasty and the Congo were in the realm of science. This perspective, which focuses on three Belgian sovereigns of the twentieth century, should make it possible to assess the development and progressive implementation of the "science policy". To date, no study has been specifically devoted to this topic. [less ▲]

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