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See detailMise au point d’un protocole de multiplication in vitro de Jatropha curcas L. en vue d’une application à grande échelle
Medza Mve, Samson Daudet ULg

Doctoral thesis (2013)

Jatropha curcas L. is a wild plant, that emerged as a source of energy for biodiesel production. It has acquired significant economic potential as it does not compete with the edible oil supplies ... [more ▼]

Jatropha curcas L. is a wild plant, that emerged as a source of energy for biodiesel production. It has acquired significant economic potential as it does not compete with the edible oil supplies. Realizing its importance, in vitro multiplication methods have been established to meet the demand of large scale supply of superior clones. In order to improve the in vitro multiplication rate (number of shoots/explant/subculture/three weeks) of J. curcas, axillary nodes taken from young plants of two accessions (originating from Cameroon and Senegal) have been cultivated for three weeks on a Murashige and Skoog (1962) medium (MS) supplemented with 8.87 µM BAP, 4.92 µM IBA, and 30 g/l sucrose at pH 5.7±0.1, and solidified with 0.7% agar. The shoots obtained from each original explant were then transferred to a multiplication media consisting of MS medium supplemented with 2.21 to 8.9 μM BA or 2.21 to 8.9 μM kinetin in combination with 2.46 μM IBA. Each combination was completed with 12.2 mg.l-1 adenine sulfate and 25 mg.l-1 of glutamine. The best multiplication rate was obtained for the PM medium containing 6.65 μM BA and 2.46 μM IBA. The mean multiplication rate is 8.1 shoots per explant during the 7 following subcultures. Leafy shoots obtained have been rooted in a medium containing half of the major mineral and minor mineral components of MS supplemented with 5.7 μM IBA, then acclimated with a survival rate of 97%. With the aim of finding a more efficient production protocol practicable on a large-scale, an alternative method has been developed to regenerate whole plants of J. curcas from nodes via the induction of buds aggregates. Histological observation shows that bud aggregates are simultaneously formed through axillary budding and adventitious regeneration of buds. These buds are elongated in MS medium supplemented with 2.21 µM BA, 5.70 µM IAA (indole-3-acetic acid) and 15 mg.l-1 L arginine. The leafy stems are then rooted on MS containing 2.46 µM IBA, 2% sucrose, and 0.7% agar. The entire process takes 14 weeks with 98% plants survival after acclimatization. We obtain a multiplication rate of 13 buds per explant per subculture. This protocol is more efficient than previously known protocols. [less ▲]

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See detailL'influence de la réforme du contrat d'occupation d'étudiants du 1er janvier 2012 sur les acteurs du monde du travail
Pironet, Antoine ULg

Master's dissertation (2013)

Background: The reform of the law on the student employment contract became effective January 1st 2012. This reform widely affects the way student employment takes place in Belgium. In this study, I ... [more ▼]

Background: The reform of the law on the student employment contract became effective January 1st 2012. This reform widely affects the way student employment takes place in Belgium. In this study, I evaluate the influence of this change on the behavior of the labor market actors at different points: (1) their knowledge of the law, (2) their interest for student employment, (3) the periods during which students work, (4) the competition between students and job seekers and (5) moonlighting. Methods: I carried out a qualitative study on 42 labor market actors belonging to the following categories: students, employers, representatives of temporary work agencies and union representatives. I interviewed these persons with a questionnaire based on the five points mentioned above. I analyzed the gathered data using techniques suited for qualitative data. Results: It first appears that the law is well known by the labor market actors. Second, the reform caused an increased interest for students employment through a cost decrease and an increase in flexibility, both on the employers’ and the students’ sides. Third, there seems to exist a link between school underperformance and a student’s amount of working days. Fourth, I observe that there exists an actual competition between students and job seekers, in particular because student employment bears a strategic aspect. Finally, I observe that 7 out of 10 students already moonlighted. The more the students like to work and the older they are, the more likely they moonlight. Conclusion: This work allowed me to answer some questions that remained open and to provide a first qualitative evaluation of the new system. The first problem of this system is that it could elicit school underperformance by allowing students to work during terms. Next, this system does not discourage some employers to resort to moonlighting because they still need more flexibility from the students. These two thoughts will have to be part of the debate when the authorities will assess the system. [less ▲]

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See detailEtude des propriétés de repliement d’une protéine hélice bêta parallèle droite la pectine méthylesterase d’Erwinia chrysanthemi 3937
Guillerm, Jessica ULg

Doctoral thesis (2013)

The aim of protein folding studies is to elucidate the process by which a polypeptide chain spontaneously adopts its functional three-dimensional structure in vivo. This issue, known as the « protein ... [more ▼]

The aim of protein folding studies is to elucidate the process by which a polypeptide chain spontaneously adopts its functional three-dimensional structure in vivo. This issue, known as the « protein folding problem », is one of the major challenges in modern structural biology. Indeed, a better understanding of the fundamental principles underlying protein folding could have many applications, either in the understanding of various diseases related to protein misfolding, in the exploitation of advances in genomics, or in the design of proteins with new functions. Pectin methylesterase of Erwinia chrysanthemi 3937 (PemA) was chosen as a model protein for folding studies. It is a 37 kDa protein that is involved in the degradation of pectin, a major component of the plant cell wall. This enzyme has a right-handed parallel beta-helix structure, which has been proposed as a plausible model to describe the structure of amyloid fibrils. Characterization of PemA thermodynamic properties led to the determination of its conformationnal stability, whereas kinetic studies highlighted occurence of at least two obligatory intermediates on the folding patway of the the protein when it acquires its native structure. We first developed an effective procedure to obtain the protein of interest in sufficient quantities to perform various biophysical studies. PemA gene was cloned into an expression vector allowing improved production yields of the recombinant protein. The purification protocol was also improved and we developed an efficient activity test in order to probe the functionality of the enzyme.The conformational stability of PemA was assessed by destabilizing the native protein using different denaturing agents (guanidinium chloride, urea, temperature, pH, pressure) and probing the structural integrity of the protein with the help of one or more spectroscopic technique(s) (fluorescence, circular dichroism and FTIR spectroscopy). Data showed that PemA is particularly resistant to high pressure, while its chemical and thermal stability are in the range of what is commonly observed for mesophilic proteins. On the other hand, characterization of PemA folding kinetics highlighted that it folds along a sequential pathway, characterized by the formation of at least two obligatory kinetic intermediates. Simulation of the kinetics on the basis of the experimental data reinforced the view that PemA folding is adequatly described by a four states model. [less ▲]

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See detailIntérêt de l'épidémiologie et des modèles animaux expérimentaux dans l'étude des valvulopathies en cardiologie humaine et équine
Leroux, Aurélia ULg

Doctoral thesis (2013)

Valvular regurgitations are one of the most common causes of cardiac diseases in humans and in domestic animals. Clinical studies, epidemiological studies, and animal experimental models have been ... [more ▼]

Valvular regurgitations are one of the most common causes of cardiac diseases in humans and in domestic animals. Clinical studies, epidemiological studies, and animal experimental models have been developed to test new diagnostic and therapeutic techniques. Electrocardiography, Doppler echocardiography, angiography, magnetic resonance imaging (MRI) and computed tomography are currently used in clinical practice for diagnosis and prognosis. Medical management and, in humans, surgical treatments can increase life expectancy and improve quality of life of cardiac patients. In horses, cardiac clinical abnormalities including murmurs and arrhythmias are relatively common while the prevalence of clinically significant cardiac diseases is low. However, investigation of these with ECG and Doppler echocardiography is recommended as even mild cardiac abnormalities may lead to significant cardiac disease and cause poor performance in sport horses. To our knowledge, risk factors for several cardiac diseases have been suspected in equids. Few have been statistically demonstrated in a large equine population, since most studies about cardiac murmurs or arrhythmias concerned only racehorses. The first aim of this research work was to perform an epidemiological study in a large equine population to describe risk factors for various cardiac diseases. The prevalence of main cardiac diseases in the studied population was in accordance with previously described prevalence as mitral regurgitation (MR), atrial fibrillation (AF), aortic regurgitation (AR) and tricuspid regurgitation (TR) were the most frequently observed cardiac diseases. Various risk factors of these cardiac diseases were statistically demonstrated: Ageing and male gender appear to predispose to AR, TR appears to affect middle-aged patients, and AF was significantly more common in larger and heavier horses. Moreover MR was an important cardiac disease since it led to congestive heart failure (CHF) whereas AR was not a direct risk factor for CHF. Functional ischemic MR is one of the main human valvular diseases and is caused by ischemic cardiomyopathy with one or more prior myocardial infarctions involving most commonly the basal posterolateral myocardium of the left ventricle (LV). The therapeutic approach to functional MR is difficult and still controversy as regards the timing and the nature of the treatment. To our knowledge, no percutaneous large animal model of functional MR has been conceptualized. This model would be the first one to allow studying the dynamic component of functional MR. Therefore the second aim of this work was the development of an experimental animal model of functional ischemic MR. Goats appeared as good candidates for the model as they fulfill all requested conditions. They have a body and heart size comparable to that of humans and can be handled easily even during exercise tests. As few publications are available in this species, three first studies were designed to test the repeatability and to establish the reference values of measurements obtained using Two-Dimensional (2D), M-Mode, Pulsed-wave (PW) Doppler and 2D speckle tracking (2DST) echocardiography in unsedated standing adult goats. Standardized echocardiographic protocols were performed three times by the same observer at one day interval on 10 to 12 goats and the intra-observer inter-day repeatability and variability was calculated. 2D and M-Mode echocardiography showed a good inter-day repeatability and a low variability of the cardiac measurements, whereas PW Doppler measurements had a poor inter-day repeatability and a moderate variability. Caprine 2DST parameters demonstrated a poor but acceptable repeatability and a high variability and allowed determination of significant physiologic differences between measurements at rest and after exercise. Then the experimental model of functional ischemic mitral regurgitation induced by a percutaneous approach in goats was developed. This experimental study was conducted in two steps: first, the study of the goat coronary arteries anatomy to determine the best myocardial infarction location to induce ischemic MR in adult Saanen goats and, secondly, the development and the imaging characterization of the goat model of functional ischemic MR. The anatomic pattern of the coronary artery system of the goat was determined using casts made of auto polymerizing resin. Two coronary arteries branches were highlighted from the results of this anatomical study: the left marginal branch (LMB) and the posterior descending branch (PDB) of the left circumflex artery, which could supply the posterolateral wall of the LV. Then myocardial infarction was induced by microcoil embolization of LMB, PDB, or both, under fluoroscopic guidance. The results confirmed that LMB and PDB occlusion produced a large myocardial infarction and an immediate severe functional MR (n=3) unlike only LMB (n=2) or only PDB occlusion (n=2). Mortality rate of this model was high (56%), particularly when LMB and PDB were simultaneously occluded (87,5%). After the myocardial infarction, a complete follow-up was performed in each surviving goat using echocardiographic techniques previously described and MRI. 2DST techniques allowed quantifying LV dysfunction during acute ischemic MR. Quantification of functional MR was performed by Doppler techniques including measurements of the vena contracta width, the effective regurgitant orifice area and the regurgitant volume using the proximal isovelocity surface area method (PISA), and by 2D-echocardiographic technique analyzing the geometrical distortion of the mitral apparatus in mid-systole (tenting area and coaptation distance). Finally, MRI confirmed the location of myocardial ischemia and the presence of functional MR. These findings make this model an interesting alternative to study the pathophysiology of the functional ischemic MR, especially for its dynamic component yielding useful prognostic information. In conclusion, the two major aims of this research were met: the prevalence of various cardiac diseases and their risk factors in a large population of equids were described and an experimental model of functional ischemic mitral regurgitation induced by a percutaneous approach in goats was developed. This model of experimental ischemic MR could be useful to further study the pathophysiology of the functional ischemic MR, especially for its dynamic component and to maximize further treatment in problem patients. Our epidemiologic study confirmed that horses with cardiac murmurs or arrhythmias and presenting demonstrated risk factors, should routinely undergo ECG and Doppler echocardiography to diagnose and to evaluate the severity of any pathological cardiac abnormalities and to identify potential signs of evolution into CHF, including the presence of multiple cardiac diseases and enlargement of the cardiac chambers. [less ▲]

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See detailMaison, architecture domestique et société dans le Moyen-Euphrate et la Djézireh syrienne à l'âge du Bronze
Mas, Juliette ULg

Doctoral thesis (2013)

Cette thèse s’est attachée à l’étude de l’architecture domestique et de la société dans les régions du Moyen-Euphrate et de la Djézireh syrienne à l’âge du Bronze. L’étude a été fondée sur la constitution ... [more ▼]

Cette thèse s’est attachée à l’étude de l’architecture domestique et de la société dans les régions du Moyen-Euphrate et de la Djézireh syrienne à l’âge du Bronze. L’étude a été fondée sur la constitution d’un vaste catalogue regroupant les vestiges de 375 maisons mises au jour sur 35 sites. L’attention a été portée sur différents aspects techniques de ces édifices ainsi que sur les aménagements, le matériel in situ et les tombes qui y ont été découvertes. Différentes séries statistiques ont été tirées du corpus et confrontées à nos connaissances sur le contexte historique, politique, social et économique de la région, selon des axes synchronique et diachronique. Or, l’âge du Bronze, qui couvre plus d’un millénaire offre l’opportunité de mieux comprendre les phénomènes de discontinuité et d’évolution des structures socio-économiques. Les débuts de la période ont vu l’émergence des sociétés complexes et stratifiées, organisées par des structures étatiques, dans le cadre des établissements urbains. Le système économique y était déjà très articulé et, au delà des grandes organisations palatiales, était au moins en partie basé sur les activités de groupes privés, qui, dans certains cas, étaient structurés par des liens de parenté. L’analyse de la masse documentaire réunie a permis de tester certaines hypothèses proposées par de précédentes études sur l’architecture domestique, d’en formuler de nouvelles et enfin de proposer un modèle interprétatif permettant d’expliquer la diversité typologique des habitations de ces régions à l’âge du Bronze par le degré de stratification économique de leurs occupants, le plus élevé correspondant à des groupes ayant développé leurs propres moyens de subsistance et s’apparentant à des entreprises privées. [less ▲]

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See detailDevelopment of a didactic SPH model
Goffin, Louis ULg

Master's dissertation (2013)

The SPH method (smoothed particle hydrodynamics) is a numerical meshless, particle and Lagrangian method. It is used in a lot of fields of engineering, such as solids mechanics, hydraulics and ... [more ▼]

The SPH method (smoothed particle hydrodynamics) is a numerical meshless, particle and Lagrangian method. It is used in a lot of fields of engineering, such as solids mechanics, hydraulics and astrophysics. The medium is represented thanks to a set of particles that have an influence on each other. First of all, the positioning of the method is discussed. The SPH method is compared to some existing numerical methods. Its advantages and drawbacks are introduced. Its particle, meshless and Lagrangian characteristics are compared to other existing methods. The basics of the method are explained through the integral representation of a function and the particle approximation. Moreover, some smoothing functions are analysed. The SPH method being Lagrangian, the Navier-Stokes equations must be written in the Lagrangian formalism. After this, the SPH method can be applied to the equations of continuity and of conservation of momentum. Some practical issues linked to the SPH method such as the neighbours search, the equations of state or the boundary conditions are discussed. Then, the practical implementation of the method and of the chosen options is explained in details. An object-oriented programming was chosen for its advantages in comparison to a classical sequential implementation. Finally, the implemented program is tested and commented. Its advantages are highlighted and its drawbacks are discussed and explained. There are a lot of test cases presented. They include some validation tests (dam breaks, particles fall, etc.), some test cases used to compare the options of the program and other tests present the possibilities of the code. [less ▲]

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See detailEtude prospective des caractéristiques hématologiques, biochimiques et urinaires du Dogue de Bordeaux: Une race prédisposée à une glomérulopathie familiale
Lavoué, Rachel ULg

Doctoral thesis (2013)

Dogue de Bordeaux (DDB) dogs are predisposed to a juvenile glomerulonephropathy (JGN), usually leading to an end-stage chronic kidney disease (CKD), mostly before 2 years of age. Since its first ... [more ▼]

Dogue de Bordeaux (DDB) dogs are predisposed to a juvenile glomerulonephropathy (JGN), usually leading to an end-stage chronic kidney disease (CKD), mostly before 2 years of age. Since its first description a few years ago, the number of DDB dogs diagnosed with JGN has drastically increased in Europe. Furthermore, some DDB dogs might develop clinical signs far later than initially thought. As the mode of inheritance of this condition has not yet been elucidated, an early diagnosis of JGN is of central importance for breeders and owners. To ease screening of affected dogs, we first wanted to improve our knowledge of this ancient French breed by describing characteristics of healthy DDB dogs. Given available information, we indeed suspected that some biological specificity existed in this breed, which could affect diagnostic processes and lead to erroneous clinical decisions. We thus determined, in a first study, breed-specific biochemical and hematological reference intervals (RI). For most of the 29 measured biochemical analytes, using the manufacturer’s generic canine RI would not have had a major clinical impact, however breed-specific RI established for 6 of them were relevantly different. Limits of the RI for total proteins, total cholesterol, aspartate aminotransferase, alanine aminotransferase and lipase were higher, while they were markedly lower for total thyroxin. Among the 25 hematological RI that were determined and compared with generic canine RI established in the same laboratory, only those of some red blood cells and platelet indices were sufficiently different to have a significant impact on clinical decision. Most red blood cells indices had higher, whereas most platelet indices had lower RI. As we also hypothesized that some apparently healthy adult DDB could suffer from JGN, we decided to look, in a second study, for the biological abnormalities that were previously described in association with the disease. We thus recruited a large cohort of adult DDB and found that proteinuria (urine protein-to-creatinine ratio (UPC) > 0.5) was present in 33%, and proteinuric CKD in 2% of the dogs. When assessed by UPC, proteinuria increased with age and was associated with changes in several biological variables. Urine specific gravity, plasma albumin and total calcium decreased, whereas cholesterol, fibrinogen and thyroid-stimulating hormone increased with UPC. Furthermore, changes in total renal volume, evaluated by ultrasound, were also described to be affected by magnitude of proteinuria. Having a UPC>0.5 increased the probability of observing urinary granular casts by an odds-ratio of 4. Amplitude of biological variations observed in this study was however generally moderate. Finally, to investigate if proteinuric DDB could be suffering from a glomerular disease related to the JGN, we attempted in a third study to characterize the nature of their proteinuria. For that purpose, we used urinary proteins electrophoresis and specific tubular (retinol binding protein (uRPB) and N-acetyl-β-D-glucosaminidase (uNAG) enzyme) and glomerular (albumin (uAlb) and immunoglobulins G (uIgG)) urinary markers. One hundred and two DDB, including 2 dogs with proteinuric CKD, were retrospectively recruited for this study, irrespective of UPC values, to facilitate comparison. Final interpretations of urine proteins electrophoresis attributed a “normal” pattern to 39 dogs, a tubular pattern to 9 of them, a glomerular pattern to 38, and a mixed pattern to 16. Most of these results were highly correlated to UPC values. However, tubular and mixed patterns were only attributed to entire male dogs because of the presence of an isolated 25kDa band, which might be due to urinary contamination by seminal proteins. When results for urinary markers were compared to values obtained in non proteinuric (UPC≤0.2) DDB dogs, 37% of the borderline proteinuric dogs (0.2≤UPC<0.5) had all four markers within reference limits. On the other hand, all proteinuric DDB dogs had elevated ratios of uAlb and uIgG when their concentrations were related to urinary creatinine (/c). Only 53% of them had an elevated uRBP/c and 35% an elevated uNAG/c, which corresponded to the dogs with highest UPC values. Results of this last study support the hypothesis that proteinuric DDB dogs have a glomerular disease which is likely related to JGN. Additionally, sensitivity, specificity, positive and negative likelihood ratio of electrophoresis to identify dogs with elevated uAlb/c were 94%, 92%, 11.85 and 0.07, in that order. These indices were respectively 90%, 74%, 3.43 and 0.13, to identify DDB dogs with abnormally elevated uIgG/c. [less ▲]

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See detailÀ propos d'une tête de momie égyptienne conservée au Musée de l'Homme à Paris
Ricciardetto, Antonio ULg

Master of advanced studies dissertation (2013)

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See detailMorphologie de l'émission aurorale UV principale de Jupiter en fonction du temps local
Palmaerts, Benjamin ULg

Master's dissertation (2013)

L'émission aurorale principale sur Jupiter est associée à des courants alignés liés à la diminution radiale de la vitesse de rotation du plasma magnétosphérique. Elle présente une structure complexe qui n ... [more ▼]

L'émission aurorale principale sur Jupiter est associée à des courants alignés liés à la diminution radiale de la vitesse de rotation du plasma magnétosphérique. Elle présente une structure complexe qui n'est uniforme en temps local ni en épaisseur, ni en intensité, ni en position dans le plan équatorial. L'objectif de ce mémoire est l'étude des variations de morphologie le long de cette émission. Cette étude est basée sur l'analyse d'images UV des aurores de Jupiter récoltées par le Télescope Spatial Hubble lors de différentes campagnes d'observations entre 1997 et 2007. L'analyse réalisée porte sur les variations d'épaisseur, d'intensité et de position de l'émission principale en fonction du temps local. L'étude montre certains changements systématiques de la structure aurorale en fonction du temps local, dont une intensité faible en matinée et une épaisseur plus élevée dans l'après-midi. De plus, la source de l'émission principale s'avère être plus éloignée l'après-midi, indiquant une rupture de corotation se produisant à des distances plus grandes dans cette région. Afin de comprendre l'origine de ces changements morphologiques, les résultats sont finalement comparés avec des simulations de la magnétosphère de Jupiter et avec les observations in situ de la sonde Galileo en orbite autour de la planète géante. Cette étude démontre que les variations en temps local de l'émission principale sont liées aux inhomogénéités en temps local du champ magnétique, du système de courants et de la distribution du flux de plasma dans la magnétosphère jovienne. [less ▲]

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See detailOptimisation de la gestion de grands barrages, avec prise en compte du changement climatique
Bruwier, Martin ULg

Master's dissertation (2013)

Les effets du changement climatique sont aussi multiples et divers que la variation du niveau des océans, la migration de certaines espèces,… Ce travail a pour objectif d’étudier les effets de ce ... [more ▼]

Les effets du changement climatique sont aussi multiples et divers que la variation du niveau des océans, la migration de certaines espèces,… Ce travail a pour objectif d’étudier les effets de ce changement du climat sur la gestion de barrages. Cette étude est appliquée à deux ouvrages de rétention d’eau situés dans le bassin de la Vesdre, en Belgique. A partir d’un modèle intégré comprenant un modèle climatique, un modèle hydrologique du bassin versant de la Vesdre, un modèle hydraulique de ce cours d’eau et un modèle de simulation de la gestion des barrages, les variables hydrauliques de la Vesdre et les niveaux d’eau des lacs peuvent être déterminés. A partir de données climatiques alimentant le modèle, une étude de l’influence des divers paramètres constituant la loi de gestion des réservoirs est réalisée, après avoir proposé des indicateurs de performance de la gestion originaux. Ces indicateurs représentent les dommages occasionnés par des crues à l’aval des réservoirs, la production hydroélectrique, le soutien aux débits d’étiage et la possibilité d’assurer une production d‘eau potable à tout moment de l’année. Ensuite, sur base de deux scénarios de changement climatique, un sec et un humide, les modifications des indicateurs de performances sont déterminées aux horizons temporels 2020-2050 et 2070-2100. L’analyse de sensibilité, réalisée sur la période 1974-2004, est alors utilisée pour rechercher des adaptations à la loi de gestion afin d’atténuer les effets néfastes calculés. [less ▲]

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See detailThe Hedonic Analysis : an Application to the Belgian Housing Market
Broos, Sébastien ULg

Master's dissertation (2013)

The goal of this master’s thesis is to build a hedonic model to analyse the Belgian housing market and in particular, the market for apartments. We will start by describing what the hedonic theory is and ... [more ▼]

The goal of this master’s thesis is to build a hedonic model to analyse the Belgian housing market and in particular, the market for apartments. We will start by describing what the hedonic theory is and why it is useful. We will also present traditional price indices and the specificities of the housing market. A hedonic price index will be built through ordinary least squares regressions. With its help, we will see that prices of apartments, between 2011 and 2012 and at constant quality, have increased in some regions in Belgium. We will compare our results with another hedonic study about Belgium and with the re- sults from traditional price indices. This comparison will show some conclusions that can be drawn thanks to hedonic price indices. It will also show that they are absolutely needed if economists want to understand the real estate market rigorously. [less ▲]

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See detailEtude d’un photobioréacteur à biomasse fixée pour la production de métabolites à haute valeur ajoutée
de Lamotte, Anne ULg

Master's dissertation (2013)

This master thesis is part of the FOTOBIOMAT research project financed by the Walloon Region, the aim of which is the development of a photobioreactor (PBR) using hybrid materials in the shape of beads ... [more ▼]

This master thesis is part of the FOTOBIOMAT research project financed by the Walloon Region, the aim of which is the development of a photobioreactor (PBR) using hybrid materials in the shape of beads within which photosynthetic microalgae producing high added-value metabolites are encapsulated. The most important limiting factor for the design of a PBR is the illumination of the culture medium. Externally illuminated rectangular reactors with a small thickness and with a high surface to volume ration allows optimising the supply of light. Nevertheless, due to the strong absorption by the cells, the recirculation of encapsulated microalgae is necessary to insure their access to the light provided at the PBR walls. To avoid any risk of deleterious shock or attrition, the beads recirculation is performed by fluidisation (hydraulic mixing) in a reclining reactor. The present work aims at describing the influence of the illumination distribution and of the fluid and particle flows on the levels and on the fluctuation of light intensity encountered by microalgae encapsulated in solid beads. Several experimental techniques were used to quantitatively characterise the illumination distribution and the liquid phase hydrodynamics. The motion of the solid particles was analysed more qualitatively. All these information on light distribution, liquid phase hydrodynamics and displacement of encapsulated microalgae in beads will have to be integrated and coupled to kinetic data on photosynthesis reactions to build a complete model of the PBR performance. [less ▲]

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See detailLes discours des travailleurs dans les tombes privées de la Première Période Intermédiaire et du Moyen Empire
Motte, Aurore ULg

Master's dissertation (2013)

The subject of the master thesis is the workers’ speeches in the private tombs of the First Intermediate Period and the Middle Kingdom. These speeches are dialogues between peasants, work- or craftsmen ... [more ▼]

The subject of the master thesis is the workers’ speeches in the private tombs of the First Intermediate Period and the Middle Kingdom. These speeches are dialogues between peasants, work- or craftsmen, which can range from a simple onomatopoeia to a small text. The corpus consists of 348 speeches coming from 21 tombs out of 8 provincial necropolises. The first part of the study comprises a catalogue of all the First Intermediate Period and Middle Kingdom speeches; the first time such a survey has been made, and including a great deal (more than two-thirds) of unpublished material. The speeches are studied in their iconographic contexts, allowing good explanation of the meaning of the dialogues in connection with the actions depicted. In this manner, new technical terms (totally or partially unknown) could be identified, false translations could be corrected and even new suggestions for translations could be made. Furthermore, it is shown that workers’ speeches are found in only 9 iconographic contexts: agriculture, butchery, cattle breeding, crafts, dance & music, hunting & fishing, kitchen scenes, wrestling and offering bearers. Within these contexts, it is observed that the workers’ speeches had a range of 7 themes: carelessness, complaint, curse, injunction scenes, mockery and/or irony, self-glorification and zeal. The study underscores recurrent phraseology within the same iconographic context or over several contexts, which provides evidence to suggest a tradition in the discourses. The conclusion of the thesis touches on the idea that workers’ speeches form a text type of their own, following specific rules. [less ▲]

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See detailEvaluation expérimentale de l'impact thoracique des projectiles non-létaux
Robbe, Cyril ULg

Doctoral thesis (2013)

On constate depuis une vingtaine d'années une augmentation significative de l'emploi d'armes non-létales, aussi bien au sein des forces de l'ordre que du côté militaire. L'idée est effectivement ... [more ▼]

On constate depuis une vingtaine d'années une augmentation significative de l'emploi d'armes non-létales, aussi bien au sein des forces de l'ordre que du côté militaire. L'idée est effectivement séduisante: pouvoir stopper ou neutraliser la cible, sans lui occasionner de blessures graves, ou de lésions permanentes, voire létales. La technologie actuellement prépondérante consiste en le tir d'un projectile, généralement très déformable, à l'aide d'un lanceur pneumatique ou d'une arme à feu classique, à des vitesses de l'ordre de 100 m/s. L'impact provoque une douleur, qui amène à la neutralisation ou à l'obtempération de la cible. En pratique, on constate que ces armes provoquent néanmoins des blessures graves et même létales, d'où la nécessité de mettre au point des méthodes d'évaluation avant leur mise sur le marché. Les impacts au niveau du thorax, zone d'impact prépondérante, sont caractérisés par des lésions plus importantes que pour d'autres parties du corps, à l'exception de la tête qui n'est jamais visée. Les lésions observées consistent en des blessures provoquées par un impact non-pénétrant, ou en la pénétration du projectile dans l'organisme. Une étude de la littérature sur le sujet oriente cette recherche vers les résultats obtenus à l'Université de Wayne State, par le professeur C. Bir. Ainsi, le critère lésionnel de l'impact non-pénétrant étudié dans cette thèse sera le (VC)max, même si la méthode mise en place est adaptable à tout autre critère. Par ailleurs, l'étude de la pénétration de la peau s'inspirera d'un modèle anthropomorphique ou "surrogate", également développé par C. Bir. La méthode d'évaluation proposée dans ce travail combine des mesures expérimentales et des simulations numériques. La présente thèse s'intéresse exclusivement à l'aspect expérimental, l'aspect numérique faisant l'objet d'une autre thèse développée au département ABAL (Systèmes d'Armes et Balistique) de l'Ecole Royale Militaire. Les deux tests expérimentaux mis au point consistent en des tirs de projectiles non-létaux respectivement sur une cible supposée infiniment rigide, équipée d'un capteur de force, et sur le "surrogate" susmentionné. Ces deux tests nécessitent l'emploi d'un lanceur pneumatique, développé pour l'occasion, qui permet de tirer l'intégralité des projectiles aux vitesses voulues. Ses caractéristiques inédites apportent entière satisfaction tout au long de l'étude. L'emploi du "surrogate" ne nécessite qu'une mesure de vitesse avant l'impact, tandis que les mesures réalisées lors du tir sur le mur rigide consistent en une mesure de vitesse avant l'impact, ainsi que de force et de déplacement du projectile pendant l'impact. La mesure de force est effectuée à l'aide d'un capteur piézoélectrique, les deux autres sont réalisées à l'aide d'une caméra haute-vitesse. L'emploi de celle-ci nécessite le développement d'un logiciel de poursuite dédié à l'application de mesures dynamiques d'impacts de projectiles non-létaux. Ce logiciel apporte une flexibilité, une précision et quantité d'information jusque là jamais atteintes. Les résultats consistent alors en la prise de ces mesures pour six projectiles commerciaux et un projectile en développement. Un énorme effort est fourni pour quantifier les incertitudes de mesure. celles-ci sont calculées grâce à l'emploi du logiciel de poursuite dédié et constituent une originalité supplémentaire de cette thèse. Finalement l'ensemble des résultats expérimentaux sont collationnés et intégrés dans l'approche hybride expérimentale et numérique pour évaluer le potentiel lésionnel de l'impact non-pénétrant et de l'impact pénétrant, à différentes vitesses d'impact, pour le projectile Spartan LE 40 mm de Nobel Sport et le FN303. Les données obtenues pour ces deux projectiles sont ensuite reliés à des distances de tirs. Trois systèmes d'armes sont alors étudiés: le F2000 pour le projectile 40 mm, et le FN303 et FN303p pour le projectile FN303. Grâce à une étude de dispersion et d'efficacité supplémentaire, les résultats définitifs permettent de dimensionner des distances minimum et maximum d'engagement, qui garantissent un tir sûr et efficace. [less ▲]

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See detailQuasi-One-Dimensional Numerical Simulations of Post-Stall Compression Systems
Du, Wenhai ULg

Doctoral thesis (2013)

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See detailLe potentiel du saule pour la phytostabilisation des sols pollués par les éléments-traces métalliques
Evlard, Aricia ULg

Doctoral thesis (2013)

Since the ‘80s, when the concept of phytoremediation first appeared, a lot of research has been put into studying the efficiency of woody plants in metal extraction. Willows, as fast growing plants and ... [more ▼]

Since the ‘80s, when the concept of phytoremediation first appeared, a lot of research has been put into studying the efficiency of woody plants in metal extraction. Willows, as fast growing plants and because of their tolerance to difficult edaphic conditions, have been particularly well investigated. In this investigation, the essays were done on Salix clones, which come from a Walloon collection provided by ECOLIRI and ECOLIRIMED projects. The first objective was to study the potential of these local clones by considering not only their ability to extract their pollutants, but also by adding their biomass production to this parameter. We have called the study of these criteria the phenotypic approach to the tolerance of Salix clones to metals. The second added value of this investigation lies in the second objective which aims to complete these phenotypic criteria with physiological and proteomic criteria. These last criteria are often used to study the metal tolerance of plant species, but rarely for willows. The combination of these different approaches gives a expand view of metal tolerance in Salix clones studied in this investigation. As the phenotypical parameters help to answer the extraction ability challenge, the physiological and proteomic approaches give answers linked to the “health” of the willow trees when they grow in the presence of metals. Our results indicate that the clones that produced more biomass were the ones that showed the highest metal concentrations. The clones with lower biomass production showed the same tolerance as the highest producers and our results revealed that growth reduction indicates metal tolerance. Finally, after comparing our results of the metal concentrations obtained in the twigs, to results obtained during the last two decades of research papers, we have concluded that we should reconsider the use of Salix potential in phytoextraction. The first chapter of this investigation was about Salix clones exposed to metals, but, in natural conditions, their roots are colonized by fungi. Thus, their rhizosphere constitutes a separate ecosystem, which is interesting to investigate. The rhizospheric fungi, the first interface between roots and soil pollutants, play an important role in metal tolerance in woody plants. For this reason, the second chapter of this thesis aimed to test the in vitro growth of rhizospheric fungi collected on woody plant roots in the presence of cadmium. The outcome of these essays is that fungal strains have been identified and classified as tolerant to this metal. This chapter thus constitutes a first step in a future study aiming to analyze these strains in association with woody plant roots in the presence of metals. [less ▲]

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See detailContributions to Recognizability: Self-generating Sets, Decidability, Automaticity and Multidimensional Sets
Lacroix, Anne ULg

Doctoral thesis (2013)

In this thesis, we study and answer several questions concerning recognizability of integer sets by finite automata. Each particular problem is the focus of a chapter. First, we study the recognizability ... [more ▼]

In this thesis, we study and answer several questions concerning recognizability of integer sets by finite automata. Each particular problem is the focus of a chapter. First, we study the recognizability of the so-called self-generating sets, initially introduced by C. Kimberling. In the second part, we study the syntactic complexity of any ultimately periodic set and we use our results to give an alternative decision procedure for a well-known decidability problem. Next, we give bounds on the automaticity of three different languages: the language of primitive words over a finite alphabet, the language of unbordered words over a finite alphabet and the language of representations of monic irreducible polynomials over a finite fields. Finally, we characterize the multidimensional sets that are recognizable in all abstract numeration systems. [less ▲]

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See detailLiquidité des titres, communication financière et gouvernance d’entreprise
Ajina, Aymen ULg

Doctoral thesis (2013)

A travers ce travail doctoral, nous cherchons à étudier l’influence des mécanismes de gouvernance d’entreprise sur la liquidité des titres. Nous nous focalisons aussi sur l’efficacité et la qualité du ... [more ▼]

A travers ce travail doctoral, nous cherchons à étudier l’influence des mécanismes de gouvernance d’entreprise sur la liquidité des titres. Nous nous focalisons aussi sur l’efficacité et la qualité du système de gouvernance en passant d’une étude fragmentée des mécanismes de contrôle à une étude systémique de la gouvernance d’entreprise. Les résultats défendent une orientation législative française envers l’adoption de certaines normes pour la bonne conduite de la gouvernance d’entreprise. L’étendue des informations publiées dans les rapports annuels augmente la visibilité d’une entreprise, réduit éventuellement l’asymétrie d’informations et augmente la liquidité des titres. Ces effets sont d’autant plus prononcés par l’application des normes IFRS rendues obligatoires à partir de 2005. Par ailleurs, nous montrons que le développement de la demande d’actionnariat institutionnel est une nécessité pour le marché parisien, afin de favoriser sa croissance de façon générale et soutenir sa liquidité. Nous mettons en évidence également un impact positif de la taille du conseil d’administration, de l’indépendance et de l’expertise financière des administrateurs, et du nombre des réunions du conseil sur la liquidité des titres. De même, le comité d’audit offre un support indispensable pour prévenir le risque « d’illiquidité ». [less ▲]

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See detailVariabilité de la respiration hétérotrophe du sol dans des écosystèmes agricoles: Analyse à différentes échelles spatiales et temporelles.
Buysse, Pauline ULg

Doctoral thesis (2013)

Soil heterotrophic respiration (HR) was studied at different spatial and temporal scales in agricultural ecosystems in Belgium (loamy region). Results from both laboratory and field experiments conducted ... [more ▼]

Soil heterotrophic respiration (HR) was studied at different spatial and temporal scales in agricultural ecosystems in Belgium (loamy region). Results from both laboratory and field experiments conducted at short and long timescales were analysed with the aim to better understand the influence of driving variables such as temperature, substrate input quantity and quality on HR. Both empirical and semi-mechanistic models were used in order to help interpret experimental results. Our observations showed that temperature is an important HR driving variable in agricultural ecosystems in temperate regions. HR sensitivity to temperature, characterized by a Q10 differing from 2 in our experiments, was very likely influenced by substrate availability and quality. The impact of these last two factors was however never observed through our measurements. Good agreement between modelled and observed CO2 fluxes in the incubation experiment, where carbon substrate was limited, suggested that temperature played a role both directly (enzymatic response) and indirectly (labile carbon stock depletion) at a relatively short term, and confirmed the hypothesis of occurrence of abiotic fluxes linked to the presence of carbonates in the samples taken from a limed agricultural field. Crop residue management (in both quantity and quality), as characterized by relatively low input levels in our experiment, influenced soil carbon stocks in the long term. However, HR, microbial biomass, labile carbon and metabolic diversity were not affected by the investigated treatments. Besides, results from both soil carbon budgets and short term HR measurements showed that supposedly large differences were likely to be reduced due to the relatively large proportion of root residues, weeds and residues unexported at harvest. [less ▲]

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See detailLa Bibliothèque miroir : Gabriel Naudé et le libertinage érudit
Decoster, Sara ULg

Doctoral thesis (2013)

Cette thèse est centrée sur la figure de Gabriel Naudé, l’auteur d’un Avis pour dresser une bibliothèque (1627, 1644). Comme ce traité reflète tant la doctrine politique de l’auteur que sa vision sur le ... [more ▼]

Cette thèse est centrée sur la figure de Gabriel Naudé, l’auteur d’un Avis pour dresser une bibliothèque (1627, 1644). Comme ce traité reflète tant la doctrine politique de l’auteur que sa vision sur le savoir, le texte constitue le point de départ pour une analyse détaillée de l’œuvre de l’auteur. Il importe en effet de resituer la pensée de Naudé dans le courant très complexe du libertinage érudit. En soi, les idées de Naudé concernant la bibliothèque ne sont effectivement pas novatrices. Ce constat s’impose comme une évidence lorsque l’opuscule est réinséré dans son contexte. Il s’avère que le bibliothécaire expose d’une manière concise des idées largement répandues, qui rejoignent les préoccupations de la République des lettres. La bibliothèque naudéenne épouse l’irénisme de la communauté intellectuelle et se veut accessible au public. Cette conception très ouverte pose de front le problème de la relation des libertins avec le pouvoir. Dans une France rongée par les guerres de religion et d’incessantes révoltes populaires, Naudé a lié son sort au régime absolutiste, qui était seul à pouvoir garantir la stabilité nécessaire au bonheur commun. Pourtant, Naudé démystifie impitoyablement les mécanismes d’un état qui utilise la religion pour mieux gouverner les âmes. Son œuvre possède donc un potentiel subversif important, qui s’explique par des motifs sociologiques. C’est que Naudé revendique sa place dans la société en tant qu’intellectuel, comme la théorie du jeu permet de le démontrer. En ce qui concerne le contenu de la bibliothèque, il s’agit clairement d’une bibliothèque docte, qui embrasse tous les domaines du savoir. Si Naudé accueillit les hypothèses non prouvées, il reste très attaché aux bases solides de la tradition. Toutefois, pour lui, l’érudition doit être éclairée par les lumières de la raison, ce qui implique que le savoir est soumis à l’exigence de l’efficacité. La vraie connaissance ne s’embarrasse pas de détails inutiles. Le lettré se concentre sur les aspects réellement porteurs de progrès, au lieu de verser dans un esthétisme inutile. D’ailleurs, le véritable savoir ne s’enferme pas dans une tour d’ivoire, mais s’intègre dans la vie civile. La méthode d’analyse de Naudé est philologique. Le libertin préfère la profondeur érudite à l’empirie, comme le montre clairement sa manière d’appréhender la médecine. Pourtant, il ne s’intéresse pas davantage à l’analyse de textes qu’aux sciences naturelles. En réalité, la pensée de Naudé est une pensée métaréflexive, définissant les caractéristiques de l’esprit fort. Le bibliothécaire crée les conditions de possibilité pour l’avancement du savoir, mais s’abstient de produire des travaux d’envergure lui-même. C’est cette conception qui préside à la bibliothèque naudéenne : il s’agit d’un lieu de développement du savoir, dont tous les aspects sont soumis au paradigme de l’utilité. Cette logique s’applique à toutes les composantes de la collection. De fait, les objets non livresques que Naudé intègre dans sa bibliothèque s’avèrent très fonctionnels. [less ▲]

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See detailLa structuration du monde paysan au Rwanda : cas des coopératives et des stations de lavage de café de Maraba et de Karaba, District de Huye
Gisaro Ca-Madeberi, Ya-Bititi ULg

Doctoral thesis (2013)

The agricultural sector is the main economic activity of Rwanda, which occupies approximately 90% of the active population in rural areas. It contributes more than 36% to the GDP. Coffee is the main cash ... [more ▼]

The agricultural sector is the main economic activity of Rwanda, which occupies approximately 90% of the active population in rural areas. It contributes more than 36% to the GDP. Coffee is the main cash crop and source of income for farmers, and provides major currencies for the national economy. Although it covers only 6.3% of cultivated areas, coffee is produced by 500,000 households in Rwanda. Since its introduction in the country in 1904, coffee has always been operated by individual producers. After the liberalization of the coffee sector in Rwanda in 1998, the quantity and quality produced are steadily decreasing which affects the price and the income of coffee growers. In the search for a solution to this problem, the Rwandan government has focused on the consolidation of producers cooperatives, and on the building of coffee washing stations (CWS) in all coffee growing areas at national level. The goal is to produce a fully washed coffee, exportable and better valued on the international market, which can provide better income for peasant producers. Washing stations are then seen as tools to produce quality coffee and are mainly run by cooperatives, which are structural elements in the rural world. Survey work on a sample of 80 farms for the three seasons (2008, 2009, 2010) as well as interviews with various key agents involved in the coffee sector have been conducted to understand and analyze the effects of CWS and cooperatives on coffee growers. This original dissertation is devoted to analyze the impact resulting from the structure action of the peasant world through cooperatives and coffee washing stations of Maraba and Karaba in southern Rwanda, on the socio-economic development of farmers who are members of a cooperative and the surrounding world by comparing to non-members of cooperatives. Through these facilities and structures put in place, jobs are created for producers, farmers are motivated due to income increases, the market is guaranteed, the prices are higher for members and loans are given, thereby improving the socio-economic and technical assistance to growers, which reduces the poverty among coffee growers’ households. [less ▲]

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See detailLes contraintes à la valorisation écotouristique du Parc National des ïles Ehotilé (Littoral sud est de la Côte d'Ivoire)
Kouakou, Guy Eric Anicet Quassy ULg

Doctoral thesis (2013)

Under the pressure of the environmental financiers and within the framework of the reform of its conservation policy of the protected areas, the Côte d’Ivoire State decided to preserve, to valorize spaces ... [more ▼]

Under the pressure of the environmental financiers and within the framework of the reform of its conservation policy of the protected areas, the Côte d’Ivoire State decided to preserve, to valorize spaces protected by the ecotourist approach. The first field of experiment of this approach was the National Park of Islands Ehotilé. But decade after the implementation of this policy, this initiative has difficulty in being set up. The question is to know what are the determining factors of failure of the process of ecotourist exploitation in the PNIE? To answer this question, this research, approached according to a multidisciplinary approach, suggests studying the progress of two experiences of ecotourism in the PNIE (A project introduced by the WWF and financed by the English cooperation, and an other, set up by a local NGO financed by the Global Environment Facility), to identify and analyze the factors of inhibition of the ecotourist process in this park. Analyses (quantitative and qualitative) were made from the data collected in ten waterside villages of the PNIE, through structured or semi-structured interview. These conversations also concerned the state departments (in charge of the preservation and of the tourism), the local authorities, the local administrators, the initiators of projects. We also proceeded to the consultation of several sources of documentation. The obtained results show that the material, legal and institutional conditions were not performed at the time of the political decision-making of implementation of the approach of preservation by the ecotourism. In a general way, the hotel, road infrastructures, the socio-sanitary equipments inside and outside are of inferior quality even non-existent. The tourist development (no observation, runways, landing stage) inside the park has been lacking. It was revealed also no promotional support (advertising, web site, etc.) exists to sell the PNIE. At the legal and institutional level, the legal and institutional requirements are on straddle between those mobilized by the actors of the tourism and those used by the actors of the preservation without synergy between these two groups of participants. The results also allowed to highlight the existence of a multitude of participants in interaction in and the periphery of the PNIE, characterized by differences of interests and logics of action as much at the level of the priorities of actions as means of carrying out the ecotourist exploitation of the PNIE. What was lacking in the attempt of putting in ecotourism of this park, it is the capacity to make compatible these differences of interests and logics of action, and the possibility of coordinating them. Our study also revealed differences of vision and representations towards the resources of the PNIE in the attempt of putting in ecotourism of this park. These differences concern the ancestral dimension, as well as the use values of this protected space. These conflicts are indicator of an elaboration and an inadequate management of the mechanism of ecotourist production in connection with the non-inclusion of the diverse social representations mobilized by the various actors of the projects. Besides, the convergences of representations mentioned with the actors concern "myths". The myth of the “ancestralité” bases itself on the ancestral link of the local residents with the islands of the park and appears for the promoters of the projects of ecotourist development as the element which has to justify the membership of the local populations. There is also a mythical version of the natural potentialities of the park which bases itself on the presence of exceptional species that " we do not find somewhere else ". The myth of the tourism as the vector of protection and development was also indicated. The problem is that, in the process of ecotourist valuation, the participants do not question any more these mythical versions mobilized around the PNIE. The latter appear for these participants as an obvious fact; not arousing question, they are not really worked to become resources. Finally, the results showed that the attempt of development of the ecotourism in the PNIE is marked by a governance, - in terms of piloting of the projects -, characterized by a series of uninsured coordinations or which are failing. The ecotourist projects tended to push aside or to make a weak place to the actors responsible for the park, to the actors of the territorial administration and to the actors of the tourism. In political terms, it was missing a space of coordination and piloting of this coordination. After all, recommendations are made to revitalize and strengthen the conditions of implementation and management of experiences of ecotourism in the PNIE and generally in the parks of Côte d’Ivoire. These recommendations would aim at improving the questions connected to the organizational, regulatory aspects and of planning. [less ▲]

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See detailThe International Liquid Mirror Telescope project: optical quality tests and prospective detection of multiply imaged quasars
Finet, François ULg

Doctoral thesis (2013)

The International Liquid Mirror Telescope (ILMT) project is a joint collaboration between different universities and research institutes in Belgium, Canada, India and Poland, for the design, construction ... [more ▼]

The International Liquid Mirror Telescope (ILMT) project is a joint collaboration between different universities and research institutes in Belgium, Canada, India and Poland, for the design, construction and operation of a 4 meter liquid mirror telescope at the Devasthal Observatory (India). In the framework of the present thesis, we have contributed to the development of the ILMT. We have namely designed and manufactured an innovative instru- ment capable of measuring the optical quality of the primary mirror that may be affected by the propagation of wavelets on the mercury layer. The instrument is composed of a laser source, emitting a beam whose reflection on the mirror is modulated by slope variations induced by the wavelets. Preliminary tests were carried out showing the validity of the method for on site testing of the mirror. The ILMT has been designed to perform a photometric variability survey of a narrow strip of sky, making it very suitable for the detection and follow-up of photometrically variable sources such as supernovae and quasars. In the second part of this thesis, we present an estimate of the number of QSOs to be detected within the ILMT survey, and of the expected number of multiply imaged sources among these caused by the presence of a deflector near the lines-of- sight. We have studied the impact of various parameters on the expected number of detected gravitational lens systems, such as the instrumental resolution of the telescope, the galaxy population type(s) and corresponding lensing model(s), and the cosmological parameters. The statistical sample of multiply imaged QSOs is intended to be used as a cosmological probe. In order to make a sensitivity comparison between vari- ous modelling approaches, we introduce a new formalism to estimate the lensing probabilities, based on the joined probability density of the observed QSOs. This new formalism allows to calculate three probability densities: that asso- ciated with the optical depth distribution, as well as those related to the deflector and the lensed source redshift distributions. For the case of FLRW universes, we compare the sensitivity of these distributions as a function of the cosmological mass density. [less ▲]

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See detailINFLUENCE DE L'ENCLAVEMENT SUR LE DEVELOPPEMENT RURAL (Cas du territoire d'OPALA, District de la Tshopo, R. D. Congo)
Bolakonga Ilye, Antoine Bily ULg

Doctoral thesis (2013)

Opala municipality is known for isolation and the precarious conditions of survival for the population. Natural factors such as climate, forest environment, soil erosion and socio-cultural factors ... [more ▼]

Opala municipality is known for isolation and the precarious conditions of survival for the population. Natural factors such as climate, forest environment, soil erosion and socio-cultural factors contribute to its isolation. Since Independence, wars and unrests were added to these factors. After a theoretical approach that analyzes the spatial and territorial issues, the general framework of economic policies and institutional contexts are specified in the thesis. A focus is placed on the poor infrastructures that resulted in isolation of a large part of the Congolese territory. In Opala, a code of community life, the Lilwa, relatively coercive or restrictive regulates social relationships. It contributes to the cognitive confinement of the Mbole, majority ethnic in Opala, making them suspicious and less receptive to new technical innovations. However, it is, at the same time, a solid foundation of social cohesion, based on which should be based any strategy for integral development of the municipality. The thesis includes an empirical research based on a sample of 120 farming households spread over four geographic areas selected according to the distance from Kisangani. The analysis of the main variables used in this research highlights an adaptation of farming systems in relation to isolation. Furthermore, it is important to emphasize the multidimensional nature of poverty, affected by low agronomic performance and lack of infrastructure. The thesis concludes with recommendations for a revival of economic activities in Opala. [less ▲]

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See detailDevelopment of a high-order interior penalty discontinuous Galerkin method for compressible turbulent flows. Application to Reynolds-averaged Navier-Stokes and large eddy simulations
Drosson, Marcus ULg

Doctoral thesis (2013)

Over the last decade several studies and workgroups came to the conclusion that high-order discretisation schemes are the most suited to overcome the limitations of today’s flow solvers. The latter are at ... [more ▼]

Over the last decade several studies and workgroups came to the conclusion that high-order discretisation schemes are the most suited to overcome the limitations of today’s flow solvers. The latter are at most second-order accurate and therefore often deliver poor results on currently used meshes. Within this context, discontinuous Galerkin (DG) methods have recently been identified as having the biggest potential for future flow solvers. Further research is however needed to improve the computational efficiency and the robustness of these schemes. Both issues are faced in the subsequent chapters of the thesis. The first part of the thesis is devoted to the solution of the Reynolds-averaged Navier-Stokes (RANS) equations using an interior penalty (IP) formulation. Whereas the intention is not to develop new turbulence models, the focus lies on the adaptation of existing models to the particular features of high-order discretisation schemes. In contrast to classical low-order methods, high-order schemes are prone to Gibbs oscillations which – if no care is taken – can lead to the breakdown of the algorithm. Given the stability issues caused by negative values of the eddy viscosity, different changes of the one-equation Spalart-Allmaras (S-A) model are discussed. Whilst having identical sparsity patterns as the popular second Bassi-Rebay scheme (BR2), the simpler IP formulation is up to 30% less time-consuming. Unfortunately, its stability strongly depends on a seemingly more or less arbitrary penalty parameter. As this parameter also effects the conditioning of the resulting system of discretised equations, its choice is of utmost importance. This might explain why the IP formulation has received only little attention over the past decades. The thesis analyses for the first time the use of the interior penalty discretisation to solve a system of RANS equations. One of the principal contributions of this work is the generalisation of the penalty parameter to anisotropic meshes and a highly variable viscosity. Several numerical examples are presented to illustrate the effect of the newly proposed definition of the penalty parameter. The focus of the second part lies on turbulent boundary layer resolution. Based on detailed grid convergence analyses as a function of interpolation order, element type and grid size, clear guidelines for the choice of boundary layer meshes for practical applications are provided. Besides straight boundaries, the effect of boundary curvature or a hybrid discretisation are investigated. Moreover, the concept of “quasi-straight” elements is introduced. Following this innovative approach, the accuracy of the calculated shear friction can further be improved by a proper choice of the position of the inner-element nodes, without increasing the total number of unknowns. Finally, several numerical applications clearly demonstrate the potential of the method to solve industrial problems. In the last part, large eddy simulations of the Taylor-Green vortex and the decay of homogeneous isotropic turbulence are presented. This last chapter constitutes a first step towards the use of discontinuous Galerkin methods for large eddy simulations. Besides a validation study for the Smagorinsky and the WALE subgrid scale model, the resolution requirements of resolved LES are determined. Furthermore different subgrid filters are compared and the choice of the Smagorinsky constant in the case of filtered LES is briefly examined. [less ▲]

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See detailLarge-scale alignments of quasar polarisations: a detailed study of the spinless-particle scenario
Payez, Alexandre ULg

Doctoral thesis (2013)

The main motivation for our work has been a puzzling observation concerning quasars. No one expected the existence of correlations in the polarisation of visible light coming from objects separated by ... [more ▼]

The main motivation for our work has been a puzzling observation concerning quasars. No one expected the existence of correlations in the polarisation of visible light coming from objects separated by gigaparsecs, until they were first reported in the form of a redshift-dependent effect that has become more and more significant with the growth of the data sample. In close connexion with the observational group, we have studied in detail the most widely considered scenario, involving axion-photon mixing in extragalactic magnetic fields. After a systematic investigation, we conclude that it is very unlikely that these observations can be accounted for by axion-like particles, given current data and constraints. We also derive new limits on the parameters describing these particles. This thesis gives in particular a detailed account of the consequences of axion-photon mixing on polarisation, studies the influence of averages over the frequency (including a wave-packet treatment of the mixing), and discusses the consequences of different magnetic-field morphologies. [less ▲]

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See detailLa charge vocale : De sa quantification à l’étude de son impact sur la fonction phonatoire et sur la qualité vocale
Remacle, Angélique ULg

Doctoral thesis (2013)

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge ... [more ▼]

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge vocale que sont la durée de phonation, le niveau de pression sonore, et la fréquence vocale. Ces facteurs sont associés à des contraintes mécaniques appliquées aux plis vocaux lors de la vibration, potentiellement responsables de microtraumatismes du tissu, et participant au développement de lésions bénignes. Notre contribution intervient à deux niveaux d’étude de la charge vocale. Dans un premier temps, nous l’avons quantifiée en situation écologique dans une population d’enseignantes, en comparant deux niveaux de l’enseignement ordinaire belge : le maternel et le primaire. A cette fin, le comportement vocal de 12 enseignantes du maternel et de 20 enseignantes du primaire a été enregistré durant une semaine de travail, à l’aide d’un système de dosimétrie. Les objectifs étaient, d’une part, de déterminer les différences d’utilisation vocale selon le niveau d’enseignement, et d’autre part, de comparer l’utilisation vocale professionnelle et extra-professionnelle des enseignantes. Globalement, nos résultats montrent une charge vocale plus élevée en situation professionnelle qu’en situation extra-professionnelle. Par ailleurs, les enseignantes du maternel présentent une charge vocale plus élevée que celles du primaire, en termes de nombre de cycles vibratoires et de distance parcourue par les plis vocaux. Dans un deuxième temps, nous avons étudié l’impact de la charge vocale sur la fonction phonatoire et sur la qualité vocale en condition de laboratoire. Une première condition expérimentale avait pour but d’améliorer la compréhension des facteurs de durée et d’intensité de la charge vocale, en soumettant 50 femmes normophoniques à 2 heures de charge, réalisées à deux reprises en variant le niveau d’intensité. Une seconde condition expérimentale avait pour but de comparer les effets de 2 heures de charge chez 16 enseignantes normophoniques et 16 enseignantes dysphoniques. Les effets de la charge vocale ont été évalués à l’aide de mesures objectives et subjectives. Les principaux résultats montrent plus d’impact de la durée que de l’intensité de la charge sur les paramètres observés. Par ailleurs, peu de différences sont observées entre les deux groupes d’enseignantes au cours de la tâche de charge, suggérant que les enseignantes dysphoniques présentent une bonne résistance durant la charge. [less ▲]

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See detailContribution à l'étude des amylases du sorgho et leurs utilisations dans la transformation des produits amylacés
Ba, Khady ULg

Doctoral thesis (2013)

Les amylases sont des enzymes largement utilisées dans le secteur industriel. Elles occupent d'ailleurs une place primordiale dans le marché mondial des enzymes. Les travaux présentés dans ce manuscrit se ... [more ▼]

Les amylases sont des enzymes largement utilisées dans le secteur industriel. Elles occupent d'ailleurs une place primordiale dans le marché mondial des enzymes. Les travaux présentés dans ce manuscrit se sont intéressés à la production d’amylases à partir d’une source végétale peu coûteuse et disponible, le sorgho et aux possibilités de les utiliser dans la transformation des produits amylacés. Dans la première partie de l’étude, après avoir caractérisé et malté sept variétés de sorgho blanc sélectionné à l’ISRA de Bambey (Sénégal), la meilleure variété, la F-2-20 (sans tanins, faible teneur en composés phénoliques et bonnes activités amylasiques) a été retenue pour la suite de l’étude. Dans la deuxième partie des travaux, les paramètres physico-chimiques tels que le pH optimum, la température optimale et la thermostabilité des amylases (α et β) du malt ont été caractérisés. Les deux amylases ont le même pH optimal 5,5 et la température optimale est de 65 °C pour l’α-amylase et 55 °C pour la β amylase. Par ailleurs, le gène de la β-amylase a été aussi étudié. Les résultats de la troisième partie des travaux ont montré la capacité des amylases du malt de sorgho à être utilisées dans des processus d’hydrolyse d’amidon (maïs et blé) et farines (blé et manioc). L’ajout d’ions calcium n’améliore pas significativement les rendements d’hydrolyse. Enfin, suite aux résultats obtenus, l’hydrolyse a été réalisée à plus grande échelle afin de produire des dextrines de différents DE. Les dextrines ont été analysées chimiquement et physicochimiquement pour déterminer leur composition en oligosaccharides et leurs propriétés physiques en vue de leur application dans les secteurs agroalimentaires. [less ▲]

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See detailLe vagabondage de l'esprit : aspects cognitifs, affectifs et neuronaux des pensées découplées des situations et tâches en cours
Stawarczyk, David ULg

Doctoral thesis (2013)

Dans ce travail de thèse, nous avons défini et validé une conceptualisation plus précise du vagabondage de l’esprit en tant que pensées à la fois stimulus-indépendantes et non-liées à la tâche en cours en ... [more ▼]

Dans ce travail de thèse, nous avons défini et validé une conceptualisation plus précise du vagabondage de l’esprit en tant que pensées à la fois stimulus-indépendantes et non-liées à la tâche en cours en distinguant clairement celles-ci des pensées interférentes liées à la tâche et des distractions externes. À l’aide de cette conceptualisation, nous avons exploré quatre aspects peu étudiés ou sujets à débats du vagabondage de l’esprit que sont les fonctions possibles de ce phénomène, ses soubassements cérébraux, le lien qu’il entretient avec les capacités de contrôle de l’attention, ainsi que la nature de la relation entre le vagabondage de l’esprit et les affects négatifs. Les résultats des études réalisées au sein de ce travail suggèrent qu’une fonction importante du vagabondage de l’esprit concerne la planification et la préparation des évènements futurs en lien avec nos buts et projets personnels. Notre travail démontre par ailleurs que le vagabondage de l’esprit est sous-tendu par un ensemble spécifique de régions cérébrales (généralement référenciées sous le terme de réseau du mode par défaut) et que ce phénomène représente plus que des échecs au niveau des processus de contrôle de l’attention en impliquant notamment un état d’attention découplée de l’environnement présent. Nous avons également montré que le vagabondage de l’esprit peut résulter d’une augmentation des affects négatifs et que sa présence est associée au maintien de ces affects dans le temps. Le fait que les individus qui vagabondent le plus en pensées font l’expérience d’un plus haut taux d’affects négatifs pourrait être expliqué par une moindre conscience et attention portées au moment présent. Sur base de ces résultats, nous avons proposé une perspective intégrative du vagabondage de l’esprit qui suppose que ce phénomène représente l’accès à la conscience, à travers un espace de travail global limité, des processus de mise à jour des scripts, schémas et plans stockés en mémoire à long terme et sous-tendus par le réseau du mode par défaut. La fonction de ces scripts, schémas et plans serait de guider les comportements des individus en formant une plate-forme cognitive impliquée dans la génération de prédictions relatives au futur. Nous avons dès lors proposé que le vagabondage de l’esprit peut représenter un phénomène adaptatif mais uniquement lorsque les bénéfices de ces pensées en termes de préparation et de planification du futur dépassent leurs conséquences délétères sur la qualité de l’attention portée à la tâche en cours et au moment présent. [less ▲]

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See detailThe transcription factor Egr1 in zebrafish cartilage development
Dalcq, Julia ULg

Doctoral thesis (2013)

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions ... [more ▼]

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions between neural crest cells and surrounding endodermal, ectodermal and mesodermal tissues. In this study, we show that the endodermal factors Runx3 and Sox9b form a regulatory cascade with Egr1 resulting in transcriptional repression of the fsta gene, encoding a BMP antagonist, in pharyngeal endoderm. Using a transgenic line expressing a dominant negative BMP receptor or a specific BMP inhibitor (dorsomorphin), we show that BMP signaling is indeed required around 30 hpf in the neural crest cells to allow cell differentiation and proper pharyngeal cartilage formation. Runx3, Egr1, Sox9b and BMP signaling are required for expression of runx2b, one of the key regulators of cranial cartilage maturation and bone formation. Finally, we show that egr1 depletion leads to increased expression of fsta and inhibition of BMP signaling in the pharyngeal region. In conclusion, we show that the successive induction of the transcription factors Runx3, Egr1 and Sox9b constitutes a regulatory cascade that controls expression of Follistatin A in pharyngeal endoderm, the latter modulating BMP signaling in developing cranial cartilage in zebrafish. [less ▲]

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See detailMécanismes de l'anosognosie: une étude sémiologique et par imagerie fonctionnelle.
Jedidi, Haroun ULg

Doctoral thesis (2013)

La maladie d’Alzheimer constitue une affection fréquente et très invalidante tant sur le plan individuel que social ou affectif. Elle s’inscrit comme un objectif majeur de recherche dans la mesure où elle ... [more ▼]

La maladie d’Alzheimer constitue une affection fréquente et très invalidante tant sur le plan individuel que social ou affectif. Elle s’inscrit comme un objectif majeur de recherche dans la mesure où elle constitue de par sa fréquence, les complications qu'elle entraîne et les soins multidisciplinaires lourds et coûteux qu'elle nécessite, un enjeu majeur pour l'économie de la santé des pays industrialisés. L’anosognosie qui complique souvent le décours de la maladie est un symptôme complexe, variable dans sa présentation tant au fil de l’évolution de la maladie que d’un patient à l’autre. La présence de l’anosognosie peut notamment compliquer le diagnostic ou la prise en charge voire mettre en jeu la sécurité du patient ou de ses proches. Elle peut, virtuellement, intéresser tous les domaines de la cognition. Tant sa prévalence que les mécanismes qui la sous-tendent au niveau anatomique ou fonctionnel demeurent méconnus et largement débattus dans la littérature. Dans cette optique, les corrélats neuraux de l’anosognosie doivent être mieux précisés et intégrés dans un modèle de fonctionnement global de la conscience de soi. Le domaine de l’anosognosie et en particulier celui de l’anosognosie portant sur les traits de la personnalité demeure donc un champ de recherche ouvert ou de nombreux travaux doivent encore être réalisés. C’est dans cette optique que nous avons choisi de mener notre étude. Le propos de notre ouvrage est donc l’étude des mécanismes de l’anosognosie par une approche tant comportementale que par le biais de la neuroimagerie fonctionnelle (IRMf et TEP). Au vu de l’étendue et de la complexité du sujet abordé, nous avons centré notre travail sur l’anosognosie portant sur les traits de personnalité. Au niveau cérébral, nous avons tout particulièrement étudié l’implication des régions préfrontales médiales dans ces processus de représentation de soi et dans la genèse de l’anosognosie portant sur les traits de personnalité. Notre première étude avait pour objectif d’étudier l’activité et la spécialisation fonctionnelle des régions préfrontales médiales au cours de la réflexion sur soi. Pour ce faire nous avons présenté à des volontaires jeunes une série d’adjectifs descriptifs. Durant l’acquisition en IRMf les sujets devaient juger à quel point ces adjectifs les décrivaient ou non. Juste après l’acquisition fonctionnelle, les sujets devaient à nouveau juger à quel point les mêmes adjectifs les décrivaient et de surcroît, ils devaient préciser à quel point ils avaient la certitude de posséder ou non ce trait de caractère et à quel point il était important pour eux de le posséder ou non. Les analyses de régression réalisées à partir de ces données ont démontré que l’activité au sein du cortex préfrontal dorsomédial étant corrélée à une évaluation de nature cognitive (certitude de posséder un trait de personnalité) et l’activité du cortex préfrontal ventromédial paraissant associée à des processus de nature émotionnelle (importance de posséder un trait de personnalité). Notre seconde étude avait comme objectif d’explorer les corrélats neuraux de l’anosognosie portant sur les traits de personnalité dans la maladie d’Alzheimer. Nous avons donc étudié une population de sujets présentant une maladie d’Alzheimer débutante et une population de sujets âgés sains auxquelles nous avons présenté divers questionnaires de jugement de personnalité. Nous avons également acquis une image du métabolisme cérébral de repos à l’aide de la TEP au 18 FDG chez ces patients et ces contrôles. Les résultats de cette étude suggèrent que l’anosognosie portant sur les traits de personnalité ne repose probablement pas entièrement sur un déficit de réactualisation des informations autobiographiques et du Self mais peut également être le fruit d’un déficit au niveau des capacités de prise de perspective à la troisième personne. Cette étude suggère également que le cortex préfrontal dorsomédial joue probablement un rôle dans ces mécanismes de prise de perspective. Notre troisième étude avait pour but d’évaluer le modèle dit « à deux voies » du syndrome de Capgras (Ellis et Young, 1997) qui constitue le modèle dominant de ce trouble dans la littérature et d’étudier l’implication des régions préfrontales médiales dans les processus de récupération des informations liées à un visage, de prise de perspective et de référence à autrui ou à soi-même. Pour ce faire nous avons acquis une image structurelle (en IRM) et une image fonctionnelle au repos (à l’aide de la TEP) du cerveau de notre patiente et nous avons comparé ces images à celles d’un groupe de sujets sains et de sujets présentant une maladie d’Alzheimer débutante. Les résultats de cette étude remettent quelque peu en question les corrélats anatomiques du modèle à deux voies du syndrome de Capgras et compte tenu des mécanismes actuellement connus de la reconnaissance des visages, semblent apporter de nouveaux arguments à l’hypothèse d’un rôle de centre d’intégration des informations liées à un visage et de la représentation d’autrui pour le cortex dorsomédial préfrontal. L’ensemble des résultats de ce travail démontre encore une fois combien les mécanismes de l’anosognosie et ceux de la conscience de soi sont complexes, intriqués et encore largement méconnus. Nous avons pu souligner l’importance du cortex préfrontal médial dans les processus de réflexion sur soi et d’évaluation du Self et en préciser la sous spécialisation fonctionnelle, l’activité au sein du cortex préfrontal dorsomédial étant corrélée à une évaluation de nature cognitive et l’activité du cortex préfrontal ventromédial paraissant associée à des processus de nature émotionnelle. Nous avons également pu démontrer que l’anosognosie portant sur les traits de personnalité actuelle semble davantage liée à une altération des capacités de prise de perspective tierce qu’à un déficit de réactualisation des informations autobiographiques (petrified Self). Ce dysfonctionnement des capacités de prise de perspective a également pu être corrélé à un dysfonctionnement (hypométabolisme) des régions préfrontales dorsomédiales. La dernière partie de notre travail nous permet en outre d’envisager et de mieux comprendre la complexité du rôle de ces structures préfrontales médiales et en particulier du cortex préfrontal dorsomédial, qui semble constituer, comme l’ont déjà suggéré plusieurs auteurs, un carrefour d’intégration important pour un ensemble complexe de processus cognitifs impliqués dans la représentation d’autrui, des ses intentions et de ses états mentaux, constituant ainsi une partie prenante du réseau cérébral ayant souvent été désigné par le terme de cerveau social (social brain). [less ▲]

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See detailModified TiO2-based Photocatalytic Films and Powders produced by Aqueous and Non-Aqueous Sol-Gel Processes for Water Purification
Malengreaux, Charline ULg

Doctoral thesis (2013)

Summary Two major research goals have been proposed for this thesis. The first goal concerns the development of photocatalysts in the shape of thin films coated on glass substrates which includes (i) the ... [more ▼]

Summary Two major research goals have been proposed for this thesis. The first goal concerns the development of photocatalysts in the shape of thin films coated on glass substrates which includes (i) the development of a sol-gel chemistry suitable for the production of stable colloidal suspensions of TiO2 particles, (ii) the optimization of the deposition method and (iii) the development of an experimental device to measure the photocatalytic activity of the films. The second objective is the development of innovative non-aqueous and aqueous sol-gel routes, including the development of new methods for the introduction of dopants as well as the photocatalytic testing of the resulting materials. Two original non-aqueous sol-gel processes involving respectively, an in situ production of water and the controlled addition of a small amount of water, have been developed to produce a series of stable colloidal suspensions of TiO2 particles (sols). From those sols, transparent, adherent, homogeneous thin films have been produced using an optimized dip-coating deposition method and have been proven to be photocatalytically active for the degradation of an organic pollutant in aqueous solution. The photocatalytic activity of the films has been improved through an increase of their roughness thanks to the addition of an organic additive into the sol, leading to an increased active surface involved into the photocatalytic reaction. A mathematical model allowing the rigorous evaluation of the kinetic parameters of the photocatalytic reaction taking into account the influence of the variation of the volume inside the batch photoreactor has been developed. The equations have been established in the case of a photocatalytic powder homogeneously dispersed in the pollutant solution, and in the case of a photocatalytic thin film placed at the bottom of the reactor. The particular case of a first order reaction has been treated and the error on the reaction rate constant induced by neglecting the volume variation has been quantified. An environmentally-friendly aqueous sol-gel process for producing undoped and Cu2+, Ni2+, Zn2+, Pb2+, Fe3+, Cr3+, La3+ or Eu3+ single-doped as well as La3+- Fe3+ and Eu3+- Fe3+ co-doped TiO2 bulk photocatalysts composed of nanocrystallites of anatase and exhibiting a remarkably high photocatalytic activity without requiring any calcination step has been developed. Different effects of the metal ion dopant on the photocatalytic activity have been observed and discussed according to the dopant nature and content. A kinetic study of the photocatalytic degradation of a model pollutant (4-nitrophenol) in aqueous solution under UV-Visible light (330 nm < λ < 800 nm) has been performed over a promising TiO2-Zn2+ doped catalyst. Statistical validations have confirmed the suitability of the phenomenological reaction rate model developed to represent the 4-nitrophenol photocatalytic degradation over time. [less ▲]

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See detailLa neuroinvasion dans les maladies à prions: étude de l'interface neuroimmune FDC - système nerveux sympathique
Demonceau, Caroline ULg

Doctoral thesis (2013)

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular ... [more ▼]

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular prion protein. The process through which the prion infectious agent is transferred to the CNS, the neuroinvasion, is still unknown, but secondary lymphoid organs seem to play an important role in prion amplification prior the invasion of the associated peripheral nervous system (PNS). In particular, modifications of follicular dendritic cells (FDC) and sympathetic nervous system (SNS) of lymphoid organs could influence the speed of neuroinvasion, and thus the length of the disease incubation period. It was shown that the lack of mature FDC prevents the replication of the infectious agent in secondary lymphoid organs. Likewise, sympathectomy delays the onset of the disease, and enhances sympathetic innervation reduces the incubation period. In mice, the relative positioning of FDC and sympathetic neural fibres plays a role in the incubation period following scrapie inoculation. This study thus focuses on the neuroimmune interface between FDC and sympathetic neural fibres. First, the number of close interactions between FDC and sympathetic neural fibres of five mouse strains with the same Prnpa genotype was estimated to check if it could explain the different incubation period observed after inoculation of primary bovine spongiform encephalopathy (BSE) infected-brain. Then we checked if scrapie infection, by oral or intraperitoneal route, could influence this neuroimmune interface between FDC and sympathetic neural fibres within Peyer’s patches (PP) and spleen of the C57BL/6 mouse strain. In the first part of this work, co-localizations between FDC and sympathetic neural fibres were observed in vivo within germinal centers (GC) of mouse spleen. Among the five mouse strains exhibiting the same Prnpa genotype, three strains (RIII-1, RIII-2 and 129/Ola) showed an incubation period about 100 days shorter than those of C57BL and C57BL/6 mouse strains when inoculated with primary BSE. Moreover, amplification by FDC seems an obligatory process before subsequent neuroinvasion as an intracerebral inoculation doesn’t reduce the incubation period observed with an intraperitoneal inoculation. A meticulous analysis revealed that the density of close interactions between FDC and sympathetic neural fibres is not higher for the three mouse strains with a shorter incubation period. However, these three mouse strains with a shorter incubation period after primary BSE inoculation have a higher proportion of FDC networks with close interactions than the mouse strains with a longer incubation period. These results suggest that it is not the quantity of sympathetic neural fibres close to FDC, but rather the percentage of FDC with close sympathetic neural endings that could influence the incubation period of prions diseases. In the second part of this work, it came out that prion infection did not result in neuronal loss within the PNS like observed in the CNS, and also did not modify the FDC-SNS neuroimmune interface of secondary lymphoid organs where PrPd deposits are observed within germinal centers. For a single mouse strain orally infected with scrapie, neither FDC networks hypertrophy nor sympathetic neural fibres closer than 10 μm from a FDC network were observed within GC of PP. Moreover, in our conditions, the prion strain did not seem to alter the neuroimmune interface between FDC and SNS in PP that could explain the different incubation periods observed with the 139A and ME7 scrapie strains. To check if prion infection does not modify the FDC-SNS neuroimmune interface, close interactions between FDC and sympathetic neural fibres already shown in the spleen were analyzed in the same mouse strain intraperitoneally infected with the 139A scrapie strain. In that case as well, no differences were observed in FDC network hypertrophy, in the in vivo density of sympathetic neural fibres closer than 10 μm from a FDC network, or in the proportion of well innervated FDC networks, compared to control mice. An in vitro model of coculture of splenic FDC from the same C57BL/6 mouse strain with nerve cells from dorsal root ganglia (DRG) also yielded similar results. FDC isolated from scrapie 139A infected mice exhibited the same neuritogenic or neurotrophic effects than FDC isolated from control mice. During these experiments, it was also noted that young-adult or middle-age mice showed both the same mean density of close interactions between FDC and SNS. However, with age, even if the splenic volume occupied by FDC networks halved, the proportion of FDC networks with close interactions almost doubled. It would be very interesting to check this last parameter in old mice that show some delay in neuroinvasion of prion disease but also to evaluate if this percentage of well innervated FDC network contributes to the prion pathogenesis within the spleen. In conclusion, scrapie 139A and ME7 strains don’t modify FDC-SNS neuroimmune interface of secondary lymphoid organs, not allowing explaining the different incubation period observed with equivalent infectious doses. Moreover, following an oral inoculation of prion, neuroinvasion within PP would not involve direct contact between FDC and sympathetic nerves, but rather another process still to be determined or implying other nerve fibres and/or mobile cells such as macrophages or dendritic cells. However, in the spleen, the percentage of FDC networks with close sympathetic neural fibres – rather than the number of sympathetic neural fibres close to the FDC network – observed for a given age, species and Prnp genotype at the time of inoculation could play a role in the different incubation periods observed for the same prion strain. The cellular compounds involved in the specific FDC microenvironment still have to be determined for each cell implied in the neuroinvasion process. [less ▲]

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See detailContribution à l'étude des mécanismes transcriptionnels du facteur de transcription SIP1/ZEB2
Koopmansch, Benjamin ULg

Doctoral thesis (2013)

Lors de la conversion métastatique des tumeurs épithéliales, certaines cellules tumorales acquièrent la capacité d’envahir le tissu sous-jacent et de former des métastases à distance. De nombreuses ... [more ▼]

Lors de la conversion métastatique des tumeurs épithéliales, certaines cellules tumorales acquièrent la capacité d’envahir le tissu sous-jacent et de former des métastases à distance. De nombreuses données de la littérature montrent que l’acquisition de ces propriétés est accompagnée d’un phénomène de transdifférenciation appelé « transition épithéliomésenchymateuse » (TEM), impliquant la perte de caractéristiques de cellules épithéliales au profit de caractéristiques de cellules mésenchymateuses. Parmi les modifications moléculaires caractéristiques de la TEM, on observe une diminution de l’expression de cadhérine E ainsi et l’expression de novo de filaments de vimentine. L’expression accrue de différents facteurs de transcription inducteurs de la TEM est aussi rapportée. SIP1 est un des facteurs de transcription impliqués dans les phénomènes de TEM tumorale. Il a été clairement montré que SIP1 réprime l’expression de la cadhérine E en liant son promoteur. Le mécanisme de répression n’est pas précisément connu, mais il n’implique pas le co-répresseur CtBP. Un modèle de répression suggère que SIP1 empêche l’accès de facteurs activateurs aux promoteurs des gènes réprimés. Les données obtenues au cours de ce travail nous permettent d’appuyer cette hypothèse et impliquent KLF4, un facteur de transcription activateur liant le promoteur de la cadhérine E, dans ce modèle. Nos résultats révèlent en effet une compétition entre SIP1 et KLF4 pour la liaison sur le promoteur de la cadhérine E. Nous montrons aussi que les deux facteurs ont des effets opposés sur l’activité du promoteur de la cadhérine E et que KLF4 n’active celui-ci que lorsque SIP1 ne peut s’y lier. Enfin, nos données nous ont permis de localiser plus précisément la région du promoteur de la cadhérine E liée par KLF4. Cette région chevauche un des sites liés par SIP1. SIP1 est considéré comme répresseur de la transcription, mais les données s’accumulent montrant l’induction rapide de gènes cibles de la TEM, dont la vimentine, suite à une surexpression de SIP1. Nous avons entrepris de mieux comprendre l’activation de la transcription par SIP1 en utilisant le promoteur de la vimentine comme modèle, et par une approche globale à l’aide de la technique de ChIPSeq. Cette partie n’a malheureusement pas atteint ses objectifs. [less ▲]

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See detailAutomatic target recognition using passive bistatic radar signals
Pisane, Jonathan ULg

Doctoral thesis (2013)

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e ... [more ▼]

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e. airplanes that do not provide information when interrogated, in the framework of passive bistatic radar systems. Passive bistatic radar systems use one or more illuminators of opportunity (already present in the field), with frequencies up to 1 GHz for the transmitter part of the systems considered here, and one or more receivers, deployed by the persons managing the system, and not co-located with the transmitters. The sole source of information are the signal scattered on the airplane and the direct-path signal that are collected by the receiver, some basic knowledge about the transmitter, and the geometrical bistatic radar configuration. The three distinct ATR systems that we built respectively use the radar images, the bistatic complex radar cross-section (BS-RCS), and the bistatic radar cross-section (BS- RCS) of the targets. We use data acquired either on scale models of airplanes placed in an anechoic, electromagnetic chamber or on real-size airplanes using a bistatic testbed consisting of a VOR transmitter and a software-defined radio (SDR) receiver, located near Orly airport, France. We describe the radar phenomenology pertinent for the problem at hand, as well as the mathematical underpinnings of the derivation of the bistatic RCS values and of the construction of the radar images. For the classification of the observed targets into pre-defined classes, we use either extremely randomized trees or subspace methods. A key feature of our approach is that we break the recognition problem into a set of sub-problems by decomposing the parameter space, which consists of the frequency, the polarization, the aspect angle, and the bistatic angle, into regions. We build one recognizer for each region. We first validate the extra-trees method on the radar images of the MSTAR dataset, featuring ground vehicles. We then test the method on the images of the airplanes constructed from data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.99. We test the subspace methods on the BS-CRCS and on the BS-RCS of the airplanes extracted from the data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.98, with variations according to the frequency band, the polarization, the sector of aspect angle, the sector of bistatic angle, and the number of (Tx,Rx) pairs used. The ATR system deployed in the field gives a probability of correct recognition of 0.82, with variations according to the sector of aspect angle and the sector of bistatic angle. [less ▲]

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See detailIdentification et caractérisation des sous-unités ELP5 et ELP6 du complexe Elongator humain
Gillard, Magali ULg

Doctoral thesis (2013)

Familial Dysautonomia is a neurodegenerative disorder that affects the autonomic and sensory nervous systems. This disease results from loss-of-function mutations of the ELP1-encoding gene. ELP1 is ... [more ▼]

Familial Dysautonomia is a neurodegenerative disorder that affects the autonomic and sensory nervous systems. This disease results from loss-of-function mutations of the ELP1-encoding gene. ELP1 is required for the integrity of the so-called Elongator complex, which is composed of two sub-proteins complexes, namely the core-Elongator (ELP1 to ELP3) and HAP (ELP4 to ELP6). While ELP3 is acting as an acetyltransferase that target multiple substrates such as nuclear histones and cytoplasmic α-tubulin, the ELP4-6 has been recently described as an ATPase. This complex has been initially identified as a component of a hyperphosphorylated RNA polymerase II holoenzyme. As a result, Elongator is involved in transcriptional elongation. Since, other roles have been assigned. Elongator is indeed also required for some tRNA modifications in the cytoplasm and consequently controls translation fidelity. Those molecular functions underlie the capacity of Elongator to regulate cell division, DNA-damage response and cell motility. It is likely that a better understanding of the molecular functions of Elongator will clarify its role in these cellular processes and probably highlight new features. The identity of human ELP1 through ELP4 has been reported but human ELP5 and ELP6 have remained uncharacterized. We therefore initiated a study dedicated to the identification and characterization of both proteins. A biochemical purification of ELP4 was conducted to isolate all associated proteins. Such experimental approach led to the identification of DERP6 and C3ORF75 as human ELP5 and ELP6 subunits of the Elongator complex, respectively. We further investigated the cellular functions of both subunits by combining biochemical analysis and cellular assays. Our results show that DERP6/Elp5 is required for the integrity and the fucntion of Elongator and directly connects ELP3 to ELP4. Our laboratory has previously demonstrated the key role of Elongator in cell migration. As cell motility is required for cell invasion and metastasis, we therefore investigated to which extent Elongator is involved in those processes. The migration and tumorigenicity of melanoma-derived cells are significantly decreased upon Elongator invalidation through Elp1 or Elp3 depletion. Strikingly, DERP6/Elp5 and C3ORF75/Elp6-depleted melanoma cells have similar defects, further supporting the idea that DERP6/Elp5 and C3ORF75/Elp6 are essential for Elongator function. Together, our data identify DERP6/ELP5 and C3ORF75/ELP6 as key players for migration, invasion and tumorigenicity of melanoma cells, as integral subunits of Elongator. [less ▲]

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See detailTemplated TiO2 mesoporous films used as highly efficient photoelectrode in Dye-Sensitized Solar Cells
Dewalque, Jennifer ULg

Doctoral thesis (2013)

The present thesis is dedicated to the synthesis and characterization of the TiO2 semiconductor layer used as photoelectrode in dye-sensitized solar cells (DSSCs), with the aim to improve their ... [more ▼]

The present thesis is dedicated to the synthesis and characterization of the TiO2 semiconductor layer used as photoelectrode in dye-sensitized solar cells (DSSCs), with the aim to improve their photovoltaic efficiencies. DSSCs have been reported by O’Regan and Grätzel in the early nineties as a very promising alternative to conventional silicon devices. Main benefits of these cells are their low cost and their mild manufacturing process. In most of the specific literature, DSSCs are made of TiO2 films prepared by doctor-blade or screen-printing of anatase nanoparticles paste. However due to the random organization of the nanoparticles, pore accessibility by the dye and electrolyte could be incomplete and some anatase crystallites could be not connected impeding electron transfer. The strategy adopted to improve the films properties and thus PV efficiencies involves a surfactant-assisted process allowing the preparation of highly porous layers with well-ordered and accessibles pores as well as improved crystallites connectivity. The main goal of this work is to increase the film surface area and perfectly control the mesostructure in terms of thickness, pore size, pore organization and pore accessibility in order to maximize the adsorption of active dye and the electrolyte infiltration inside the porous network. Special attention was paid to the tuning of the experimental settings such as the relative humidity conditions, the withdrawal speed and the choices of substrate and surfactant. Moreover, for DSSCs applications, TiO2 film has to be crystallized in form of anatase. Perfect balance between high crystallinity and mesostructure preservation was studied in order to enhance the cells efficiencies. Besides, templated films challenge is to obtain thick layers. Indeed, monolayer films are only a few hundred nanometers thick. To increase the film thickness and thus the quantity of active material, a multilayer process was tuned. Special effort was paid to overcome the surface area limitation induced by the repeated thermal treatments applied during multilayer process. We propose an alternative thermal treatment in order to limit the mesostructure degradation. We also define the maximum crystal size compatible with the preservation of the mesoarchitecture initially induced by templating. Thick films up to 4 µm were prepared from this multilayer process and show excellent efficiency in combination with N-719 dye (6.1%) when compared to values reported in the literature. Such mesostructured templated films were compared in terms of photovoltaic performances with TiO2 nanoparticles films, generally used in DSSCs. In a second part, as the goal of this thesis is to improve the current nanoparticles-based DSSCs and prove the viability of the templating alternative, a comparison of the long-term stability of both technologies was performed. To our knowledge, long-term stability of templated DSSCs has never been reported at this time. However, in case of templated films, the surface area is highly improved and the negative effects of thermal stress, light soaking and UV exposure could be heightened. Due to their higher active interface, templated films are more sensitive than nanoparticles samples to UV illumination, what can be easily solved by the use of a UV filter. However, they are as stable as nanoparticles samples under visible light soaking (UV filtered) and under thermal stress. In addition, cells were characterized by electrochemical impedance spectroscopy (EIS). Templated cells show lower transfer resistance, as well as longer electron lifetime compared to nanoparticles DSSCs. Using templated films in DSSCs is therefore really promising because higher conversion efficiencies are reached without any increase in cells degradation. Finally, stability limitation encountered by DSSCs are mostly related to the use of liquid electrolytes, which can leak out the cell. Solid-state hole transporting materials are investigated in order to overcome this issue. However, in solid-state DSSCs, TiO2 films thickness is limited to a few microns allowing the adsorption of a limited amount of photoactive dye and thus leading to a poor light harvesting. Moreover, solid-state DSSCs are characterized by incomplete electrolyte filling, impeding the dye regeneration. Both limitations further lead to low photovoltaic efficiencies. Due to the surface area improvement as well as the perfect control of the pore organization and the pore size, the templating strategy was investigated to overcome light harvesting and pore filling limitations. Templated films were prepared from different structuring agents. They show an efficient electrolyte infiltration and a two times higher dye loading compared to nanoparticles layers. Corresponding photovoltaic performances in liquid-state and solid-state DSSCs have also been evaluated. While templating allows improving the liquid-state cells efficiencies, we cannot conclude for solid-state DSSCs due to device assembly issue and/or bad contacts between the electrodes and the sample holder during the I-V measurements. We hope that the achievements of this thesis brought a significant contribution to the field of DSSCs. Indeed, the templating strategy is proved to improve the liquid-sate cells efficiency. However, the assembly of solid-state devices and subsequent I-V tests have to be investigated further. Besides, new pathways are envisaged for interesting future work in both fundamental and applied research fields, such as the synthesis of templated films with hierarchical porosity or scale-up and industrialization of the templated devices. [less ▲]

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See detailMéthode d'intégration de modèles adaptée aux systèmes hydrologiques multicompartimentés
Deliège, Jean-François ULg

Doctoral thesis (2013)

The water resource management often results from a compartmented view coming from conceptual clippings and administrative apportionments, involving a great specific vertical expertise, confined to a ... [more ▼]

The water resource management often results from a compartmented view coming from conceptual clippings and administrative apportionments, involving a great specific vertical expertise, confined to a unique expertise field. The computer science era immediately participated to the numerical transcription of this order. Numerous compartmented models coexist separately and - if other multi-sectorial are available - the required multidisciplinary expertise that consolidates them is not always ensured in all represented knowledge fields. However, the stakes of the integrated water resource management require a multidisciplinary approach which leads to the emerging of new adapted organizations (water agencies, multidisciplinary centers, international commissions, networks …). Also, since the 70’s, the European Union concern for water policy was leading to a sectorial way of management driven by about thirty water related directives. The 23rd of October 2000, the European Parliament has adopted the Water Framework Directive, establishing a common policy in water domain (European Parliament, 2000). The common approach introduced (watershed level management, objectives by water body, measurement program and agenda, economic analysis of water use…) aimed at harmonizing the water resource management by - among others -integrating available tools (including the former directives). Similarly, at the end of the 90’s, new numerical solutions appeared, allowing to follow this evolution by authorizing the coupling of compartmented models while ensuring the self-preservation of each proper module expertise. More recently, the concept of standard interface dedicated to integrated modeling appeared, sometimes instigating the (wrong) idea, nevertheless desirable, of evolving towards more simplicity. However, the development of such integrated models is still demanding, and requires to strictly follow a modus operandi that guarantees the viability, the consistence and the durability of these new tools. Indeed, the complexity of the modeled systems is reflected in the computer architecture’s tangle allowing couplings, considering numerical and hardware constraints and the pertinence of the represented processes as well as the physical consistency of the integrated model. This kind of tools can also need to satisfy constraints that go beyond the field of expertise of developers as well as the scientific community (usability, autonomous management of scenarios and interoperability of results), to make them operational for an eventual external end-user.   The investigation field covered by the present work aims to structure the integrating expertise acquired for several years at the University of Liege, through numerous concrete developed applications. In that way, we propose an original and operational methodology for internal coupling of compartmented models, primarily applicable to the transversal water resource management (environmental modeling, hydrology in a general way), but also applicable to other related expertise (quality, economy, sociology, …), while considering the boundaries of the field of application of the models and the strong constraints linked to their use. The MOHISE project, dedicated to the integrated hydrological simulation of the water cycle in the scope of studying the effect of potential climatic changes on the state of the water resources, is used as a reference application. In parallel, concrete applications are deployed to illustrate the following topics: • Numerical coupling issues (problems and solutions) ; • Conceptual and processing architectures (interfaces, supervisor, synchronization, …) and the fixation of validity range of the integrated models in the scope of their physical and numerical consistencies ; • Preliminary operations required to implement integrated tools ; • The constrains linked to the methodological choices ; • The management of the simulations themselves (calibration-validation, stability, sensitivity…) ; • Creation of scenarios within the validity range of the model. The subjects are not only addressed on the basis of their strict computer science or compartmented modeling implications but also through an original and sideway lighting to emphasize the essential coupling constraints and the global coherence of the integrated system. [less ▲]

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See detailHas the fight against international terrorism undermined European data protection standards? A special regard to the perspectives of the transatlantic relationship
Berardo, Fiammetta ULg

Doctoral thesis (2013)

Il s’agit d'une analyse des accords PNR (Passenger Name Records) entre l’Union Européenne et les Etats Unis et plus en général des changements aux lois de protection de la vie privée qui sont intervenus ... [more ▼]

Il s’agit d'une analyse des accords PNR (Passenger Name Records) entre l’Union Européenne et les Etats Unis et plus en général des changements aux lois de protection de la vie privée qui sont intervenus dans les dernières années, surtout à la suite des événements du onze septembre 2001. La réflexion porte donc sur l’évolution du concept de protection des données personnelles vis à vis des nouveaux instruments de collecte d’informations et d’enquête. [less ▲]

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See detailObservation de l’atmosphère de Vénus par le spectromètre imageur VIRTIS-M de Venus-Express : analyse des émissions nocturnes de O2 et OH
Soret, Lauriane ULg

Doctoral thesis (2013)

Venus, the second planet of the solar system, has a very dense CO2-dominated atmosphere. Above 50 km, its dynamics is usually decomposed into two main circulation patterns. The first one, the Retrograde ... [more ▼]

Venus, the second planet of the solar system, has a very dense CO2-dominated atmosphere. Above 50 km, its dynamics is usually decomposed into two main circulation patterns. The first one, the Retrograde Superrotating Zonal (RSZ) circulation, controls atmospheric layers below 65 km of altitude. This motion is related to the retrograde rotation of the planet. The second circulation operates above 120 km. This Subsolar-Antisolar (SS-AS) circulation generates a flux from the dayside to the nightside of Venus. It originates from the strong temperature gradients at the top of the atmospheric layer. Between 65 and 120km, the circulation is more complex and no in situ measurement has been performed to study this region of the atmosphere. However, it is possible to use minor atmospheric constituents and their spectral signatures as dynamic tracers to better understand this region. For example, oxygen atoms are produced by photodissociation of CO2 molecules which dominate the Venusian atmosphere. They are then carried by the SS-AS circulation to the planet nightside, where they recombine into O2 molecules in several metastable excited states. Their de-excitation produces measurable emissions, named nightglow which may be qualitatively investigated. This thesis focuses on the study of these emission phenomena. Data have been acquired by the Venus Express spacecraft, in a quasi-polar elliptical orbit around Venus since April 2006. More specifically, observations have been made with the VIRTIS-M instrument, a multispectral imager. As VIRTIS observes in the visible and near infrared domains, some molecular oxygen and hydroxyl transitions can be detected in the data. The main goal of this study has been to extract quantitative information from these observations and to analyze both the density of constituents (such as excited molecular oxygen, atomic oxygen and ozone) and the dynamical processes involved in this region of the Venusian atmosphere. In a first part, data acquired at 1.27 µm in nadir mode have been processed and analyzed in order to study the O2(a1Δg→X3Σg-) infrared atmospheric transition. Data processing consists in correcting the geometrical effects associated with the view angle, the cloud reflection and the thermal contribution. Data analysis following emission patches in individual data sets points out a large variability of the phenomenon, both in terms of brightness and localization. Emission peaks vary from 0.5 to 6 MegaRayleighs (MR) and may be observed over the entire southern hemisphere of the planet, which is the observable part in nadir mode. However, once the individual data are grouped together to generate a statistical map, our analysis shows that the emission at 1.27 µm is located around the antisolar point, which confirms the SS-AS circulation predominance. This map is improved in the northern hemisphere by adding vertical intensity profiles derived from limb images. These profiles are deconvolved to take into account VIRTIS-M spatial resolution and transformed by the Abel inversion to get a local profile of the volume emission rate. A vertical integration of these profiles simulates a nadir observation and completes the bidimensional statistical map of the O2(a1Δg) emission. The intensity reaches 1.6 MR at the antisolar point and the mean nightside value is 0.5 MR. This map, combined with limb profiles, allows to generate a tridimensional distribution of the emission. It shows that the emitting layer is located at ~96.5 km. These results, combined with a tridimensional distribution of the CO2 density (generated with the VTS3 model or measurements from the SPICAV spectrometer on board Venus Express) allows to generate a 3-D map of the atomic oxygen density. The mean nightside density value is 2.0x1011 cm-3 at 103.4 km. This empirical map validates the VTGCM model, as no measurements of the atomic oxygen density had ever been performed in this region of the Venus atmosphere. Other oxygen transitions have been detected in the visible domain (Migliorini et al., 2012): the Herzberg II (c1Σu-→X3Σg-) and Chamberlain (A’3Δu→a1Δg) transitions. Using CO2 and O density profiles derived from our previous study, these transitions have been modeled. Some reaction parameters, whose laboratory measurements are insufficient or inexistent, have thus been estimated. The distribution of the Herzberg I (A3Σu→X3Σg-) transition has also been simulated. Other emission limb profiles have also been extracted from the VIRTIS-M database: the OH(Δv=1) and OH(Δv=2) Meinel emission bands of the hydroxyl molecule. First, these profiles have been processed to subtract a stray signal. The simultaneous statistical study shows that IOH(Δv=1)= 0.60 MR and IOH(Δv=2)=0.23 MR at ~97 km and that their intensity are correlated. The spectral analysis with synthetic spectra demonstrates that only v’≤4 vibrational levels are populated. These emissions have been modeled taking into account excited OH production, deactivation by collisions and reaction and spontaneous emission loss. The CO2 and O density profiles derived from the oxygen study have been used. The quenching coefficients have been adjusted to consider the temperature of the emitting layer and two quenching mechanisms by CO2 have been implemented. This model showed that collisional quenching by single quantum jump (Δv=1) best reproduces the observations. Likewise, an ozone density of 5.8x106 cm-3 at 96.5 km (for the best case) is in good agreement with the recent SPICAV O3 detection. Finally, the study of simultaneous OH(Δv=1) and O2(a1Δg) limb profiles showed a very high spatial correlation of these two emissions. This result has been explained by the role of atomic oxygen as a common precursor for the formation of both molecular oxygen and hydroxyl. [less ▲]

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See detailCharacterization of ionospheric irregularities and their influence on high-accuracy positioning with GPS over mid-latitudes
Wautelet, Gilles ULg

Doctoral thesis (2013)

Over the last decade came major breakthroughs in satellite navigation and positioning, due to the development of precise positioning techniques based on Global Positioning System (GPS) signals. Modern ... [more ▼]

Over the last decade came major breakthroughs in satellite navigation and positioning, due to the development of precise positioning techniques based on Global Positioning System (GPS) signals. Modern processing methods, such as the Real-Time Kinematics (RTK), allow the GPS user to determine its position in real-time with an accuracy of a few centimeters. The success of these algorithms relies on the cancellation and/or the mitigation of the various errors affecting signal propagation. Among these errors is the delay due to the ionospheric refraction. More particularly, the presence of irregularities in the ionospheric plasma is responsible for positioning errors reaching several (deci)meters. As a result, there is a growing demand from GPS user communities (such as land surveyors or civil engineers) to be informed, if possible in advance, of the occurrence of irregularities that might impact on their positioning solution. Based on a ten years GPS dataset collected over Belgium, this thesis aims at assessing, understanding and modeling the occurrence of ionospheric irregularities as well as estimating their effects in terms of positioning accuracy. Firstly, we carry out a climatological study of irregularities to identify and characterize the most recurrent features. We can distinguish two main irregularity types: those due to space weather events (such as Coronal Mass Ejections – CMEs – or solar flares) and the others, constituting the bulk of irregularities observed at a single station and referred to as “quiet-time” irregularities, as they occur during quiet geomagnetic conditions. These latter are then divided into two groups: the first is made up of Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) which occur during autumn/winter daytime. In the second group are the summer nighttime irregularities, which are rapid fluctuations of the Total Electron Content (TEC) probably associated with spread-F phenomenon. Next, we develop a model of quiet-time irregularity occurrence, based on a statistical analysis of the aforementioned dataset. Computations rely on several mathematical modeling tools, such as the Principal Component Analysis (PCA), the Generalized Least-Squares (GLS) algorithm and the AutoRegressive and Moving Average (ARMA) method. The resulting climatological model is made up of two components reproducing daily profile as well as secular variations of the ionospheric variability for a typical GPS station in Belgium. The last part of this work deals with the impact of irregularities on relative positioning. This technique allows the measurement of the vector (called baseline) joining the receiver (user station) to a reference station whose position is accurately known. More precisely, we assess the effect of baseline length and orientation during the occurrence of MSTIDs and geomagnetic storms through the processing of the Belgian Dense Network, made up of 66 dual-frequency GPS stations. Finally, the relationship between positioning error and the presence of ionospheric irregularities detected at a single station is investigated, filling the gap between the scientific and the GPS-user communities. [less ▲]

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See detailPerception et confort acoustiques des Systèmes de Traitement d'Air
Minard, Antoine ULg

Doctoral thesis (2013)

This thesis addresses the perceived acoustic comfort of Air-Treatment Systems (ATS), such as air-conditioners installed in offices, by taking into account the environmental factors related to the specific ... [more ▼]

This thesis addresses the perceived acoustic comfort of Air-Treatment Systems (ATS), such as air-conditioners installed in offices, by taking into account the environmental factors related to the specific context of ATS usage. The only existing standard to evaluate the sounds emitted by ATS, which is the emitted sound level in dBA, is only loosely related to perception. Therefore, the need of manufacturers for a more reliable standard arises. This implies a thorough study of the perception of the sound of ATS as it is emitted. A precise methodology was then followed: it includes first collecting a high number of ATS sound recordings, up to finally developing a robust metrics to predict the perceived sound quality. For that purpose, different perceptual categories were first identified to constitute the recording database of ATS sounds. A corpus considered as fully representative of the different types of emitted sounds was then extracted from the recording database. Current principles of musical timbre description have already proved to be adequate to other types of environmental sounds; by applying these principles, the relevant auditive attributes for the corpus perceptual description were identified. In order to develop an efficient sound quality predictor through audio features calculation, prominent features based on these auditive attributes were identified that explain the listeners' preferences among ATS sounds. The ecological context of ATS was examined in a second step. Two environmental factors were addressed in the context of ATS sound quality evaluation to ponder their importance in the listeners' perception. As the ATS under study are exclusively indoor systems designed for offices, the effect of reverberation on sound quality evaluation was first studied; for that purpose, an auralization tool was used to simulate room acoustic response. The influence of listeners' attention context on perceived sound quality was then evaluated through a comparative study of various listening conditions. As a matter of fact, the sound emitted by ATS in real conditions is perceived as a perturbation of current activities. It is therefore relevant to evaluate how deeply the degree of attention related to the sound affects listeners as regards their perception of acoustic quality. Eventually, the relevance of the proposed sound quality predictor to comfort perception was assessed in conditions more ecologically representative than usual laboratory environment. [less ▲]

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See detailLe musée de ville, une nouvelle catégorie muséale ?
Postula, Jean-Louis ULg

Doctoral thesis (2013)

La question générale qui sous-tend notre thèse est celle du fonctionnement et de la raison d’être des catégories muséales, à travers l’exemple de l’institutionnalisation récente de l’une d’entre elles – ... [more ▼]

La question générale qui sous-tend notre thèse est celle du fonctionnement et de la raison d’être des catégories muséales, à travers l’exemple de l’institutionnalisation récente de l’une d’entre elles – le musée de ville –, représentée depuis 2005 par un comité international de l’ICOM (Conseil international des Musées). La particularité de ce groupe de musées est de relever d’une thématique commune, plutôt que d’une discipline académique : tous sont en effet consacrés aux villes dans lesquelles ils sont situés, qu’ils exposent le plus souvent, mais sans systématisme, selon une perspective historique. Bien que de tels établissements existent depuis un siècle et demi, le traitement muséal du thème de la ville et de son histoire n’avait jusqu’alors pas fait l’objet de travaux de recherche visant à présenter une synthèse globale de son évolution, depuis les premières manifestations jusqu’aux réalisations les plus récentes. L’objectif de la première partie de la thèse est dès lors de combler cette lacune, à l’intérieur d’un espace géographique très large, assimilé aux régions de culture occidentale. Nous souhaitons, à partir de quelques exemples considérés comme des jalons importants, mettre en exergue les caractéristiques essentielles des musées, à différents moments d’une histoire marquée par la succession, voire l’empilement, de traditions et de philosophies muséales propres à chaque époque. Dans cette optique, notre point de vue privilégié est celui du « projet muséal » des institutions, notion dont l’étude a été amorcée par François Mairesse. À sa suite, le projet muséal est désigné par André Gob et Noémie Drouguet comme « l’ensemble des idées, des concepts, des intentions, qui sous-tendent une institution muséale, sa création, son fonctionnement, ses activités, son évolution ». L’accent est donc mis principalement sur le contexte et les raisons, notamment politiques, de création des musées, en ne négligeant cependant pas d’autres aspects tels la nature des collections et du discours, ou encore la muséographie, lorsque ceux-ci se révèlent pertinents. Trois chapitres composent cette partie diachronique de la thèse. Le premier décrit les origines du musée d’histoire de ville et l’environnement au sein duquel apparaissent les plus précoces d’entre eux. Le deuxième chapitre s’ouvre au cours des années 1860, avec la création du Musée Carnavalet de Paris qui occupe une large place dans nos réflexions. Nous le considérons en effet comme la figure archétypale d’un modèle muséographique, dit « classique », qui prédomine durant près d’un siècle et dont nous examinerons la diffusion et les adaptations successives à la fois dans le temps et dans l’espace. Le troisième chapitre voit quant à lui l’émergence, à partir de la décennie 1970 et jusqu’à l’heure actuelle, d’autres façons d’exposer la ville, dans le sillage des conceptions de la nouvelle muséologie sur le rôle social de l’institution muséale. La seconde partie de la thèse, elle aussi structurée en trois chapitres, est consacrée à l’étude du syntagme « musée de ville » dans la littérature muséologique. Le chapitre quatre retrace l’évolution de cette expression, entre le moment de son apparition en 1993, à l’occasion de la fondation à Londres d’un premier réseau d’institutions muséales « dédiées à l’étude des villes », et 2008. Y sont décrits et contextualisés dix-sept événements qui se sont explicitement appropriés la notion (rencontres entre professionnels, colloques scientifiques, publications). Nous procédons ensuite, dans les deux derniers chapitres, à une analyse des discours sur le musée de ville produits au cours de cette période. Le chapitre cinq propose une synthèse des informations délivrées précédemment et présente successivement deux corpus textuels : le premier est constitué de l’ensemble des communications publiées dans les actes de colloques et les recueils d’articles relatifs au musée de ville, et le second d’environ deux-cents énoncés qui font référence au musée de ville comme à une catégorie muséale, extraits de ces mêmes communications. Le chapitre six constitue l’analyse proprement dite de la notion. À travers le concept de formule, théorisé en sciences du langage, nous y développons d’abord l’hypothèse selon laquelle les discours portés sur l’objet « musée de ville » contribuent non seulement à sa description, mais dans le même temps à la construction de cet objet. Nous nous attachons enfin à l’interprétation des définitions de l’expression soumises par ses locuteurs et scripteurs. [less ▲]

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See detailLa production d'hydrogène par fermentation anaérobie: Voies d'optimalisation et d'application du bioprocédé
Beckers, Laurent ULg

Doctoral thesis (2013)

The emergence of environmental and societal issues caused by the fossil fuels consumption and the simultaneous increase of the energetic needs will lead the society to evolve into a new energetic system ... [more ▼]

The emergence of environmental and societal issues caused by the fossil fuels consumption and the simultaneous increase of the energetic needs will lead the society to evolve into a new energetic system. The creation of the hydrogen society could bring a suitable and sustainable solution since the production and use of hydrogen could be operated at higher yields than the fossil fuels economy and produce energy while generating only water vapour as co product. However, in order to get rid of the fossil fuels consumption, there is a need to diversify the hydrogen production processes and technology, currently still based on CO2—emitting technologies. The so-called “dark fermentation” process is based on strict of facultative anaerobic bacteria producing biohydrogen and soluble metabolites as a fermentation co product. These microorganisms consume organic substrates such as in wastewater to achieve their growth. The biohydrogen technology has been studied during several years in laboratory but still is not mature to be brought at an industrial scale. Indeed, there is first a need to improve the performances (such as the H2 yields and production rates) to achieve the technical and economical requirements. This thesis investigates and discusses various possibilities in order to bring the biohydrogen production process to a larger scale. The strain investigated in this work, Clostridium butyricum, can achieve high performances (in terms of hydrogen yields, about 1.9 to 2.2 molH2·molglucose -1 and production rates, about 50 to 110 mLH2·L-1·h-1 in batch or sequencing-batch cultures) and is able to consume simple and more complex substrates. However, being a strict anaerobic strain, its uses in pure culture requires the achievement of strong anaerobic conditions using artificial and costly means. Moreover, even if the work in pure culture has some advantages at the laboratory scale, it is inappropriate to larger volumes of bioreactor. Therefore, mixed cultures were investigated in batch and sequencing-batch bioreactors, resulting in a decrease by about 30 to 50% of the yields (down to 1.2 to 1.7 molH2·molglucose -1). The mixed cultures reached however comparable or higher performances than the scientific literature confirming the interest of the approach suggested in this work. However, the performances need to be further enhanced in order to make the process economically possible. Therefore, improvements of the yields and the rates were proposed. On the one hand, the yields were increased by 55 to 100% (up to 3.1 molH2·molglucose -1) by improving the mass transfer conditions and, by the way, decreasing the dissolved hydrogen concentration in the liquid media. These considerations led to the design of a novel biodisc bioreactor working continuously and allowing the efficient hydrogen mass transfer. In mixed culture, the biodisc bioreactor reached high performances (H2 yields of 2.4 molH2·molglucose -1 and H2 rates of 600 mLH2·L-1·h-1), showing the interest of the original design and of the “mass transfer” approach achieved in this work. On the other hand, the addition in the culture medium of small quantities of metallic nanoparticles showed a catalytic-like effect by enhancing the hydrogen production rate by about 40 to 100%. Ending this work, the general discussion evidences the advantages of the different techniques suggested in the work and compares them to the recent scientific literature. Furthermore, perspectives are given in terms of scientific outlooks, considering the economical, environmental and technical aspects, in order to bring the hydrogen production process at a large scale. [less ▲]

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See detailPattern Recognition in NeuroImaging: What can machine learning classifiers bring to the analysis of functional brain imaging?
Schrouff, Jessica ULg

Doctoral thesis (2013)

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging ... [more ▼]

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging. During the last decades, various techniques have been developed to analyse neuroimaging data. These techniques brought valuable insight on neuroscientific questions, but encounter limitations which make them unsuitable to tackle more complex problems. More recently, machine learning based models, coming from the field of pattern recognition, have been promisingly applied to neuroimaging data. In this work, the assets and limitations of machine learning based models were investigated and compared to previously developed techniques. To this end, two applications involving challenging datasets were defined and the results from widespread methods were compared to the results obtained using machine learning based modelling. More specifically, the first application addressed a research question: Is it possible to detect and characterize mnemonic traces? The fMRI experiment comprised a learning and a control tasks, both flanked by rest sessions. From previous studies, patterns of brain activity generated during the learning task should be spontaneously repeated during the following rest session, while no difference should be observed between the pre- and post-task rest session in the control condition. Using univariate and multivariate feature selection steps before a Gaussian Processes classification, mnemonic traces could be detected and their spatio-temporal evolution characterized. On the contrary, an analysis of the rest sessions based on the detection of independent networks did not provide any results supporting the theory of memory consolidation. The second application tackled a clinical issue: Can a pattern of brain activation characteristic to idiopathic Parkinson’s disease be detected and localized? The dataset considered to address this question comprised the fMRI images of aged healthy subjects and Parkinsonian patients while they were performing a task of mental imagery of gait at three different paces. The signal comprised in a priori selected regions of interest allowed for the support vector machines classification of healthy and diseased volunteers with an accuracy of 86%. To localize the discriminating pattern, a methodology based on the weight in labelled regions (e.g. from the anatomical automatic labelling or Brodmann atlases) was developed, which enabled the comparison between univariate and multivariate results and showed a nice overlap between them. Furthermore, models could then be compared quantitatively in terms of pattern localization, using a specifically defined measure of distance. This measure could then be used to compare the patterns generated from different folds of a same model, from different feature sets, or from different modelling techniques. The present study concluded that machine learning models can clearly and fruitfully complement other analysis techniques to tackle challenging questions in neuroscience. On the other hand, more work is needed in order to render the methodology fully accessible to the neuroscientific community. [less ▲]

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See detail"Restorative Justice behind Bars": Prisoners' Perceptions on Restorative Justice in Custodial Settings
Stamatakis, Nikolaos ULg

Doctoral thesis (2013)

There is little written on Restorative Justice in custodial settings. The present research constitutes a compilation of articles that aim to explore the applicability of restorative justice in prisons ... [more ▼]

There is little written on Restorative Justice in custodial settings. The present research constitutes a compilation of articles that aim to explore the applicability of restorative justice in prisons, and therefore fill the conceptual gap between the notion of imprisonment and that of restoration. Initially, this study creates a conceptual framework for restorative justice employing both historical and religious sources. More specifically, it seeks to (re)discover the historical roots of restorative justice as an attempt to settle long-lived disputations concerning its origin. Bearing in mind the results derived from the historical review, criticisms are raised based on conceptual and operational barriers prior to envisaging and providing suggestions for the construction of a ‘restorative prison’. In parallel, it is explained how and why some of the core elements of restorative justice (such as forgiveness, reintegration, and reconciliation) are compatible with religion (in our case, with Christianity) revealing the contribution of religion to the promotion of restorative justice. This part of our research reports findings from qualitative inquiries (interviews and participatory observation) referring to the restorative justice programmes developed by faith-based organizations in penitentiaries in New Zealand and in South Africa. On a theoretical level, the present thesis discusses the compatibility, as well as the barriers, between imprisonment and restorative justice focusing on how the latter could be overcome. Ultimately, the answers given here serve as a stepping-stone for measuring the capacity of a prison to progress in restorative justice matters. The methodological part is consisted of quantitative tools (questionnaires) addressed to prisoners held in several prisons across Belgium, evaluating their perceptions on the impact of crime on their victims, their possible openness or willingness to engaging in restorative activities, their relationships with the victim and the community, and the possible impact of religion on the implementation of restorative justice programmes. [less ▲]

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See detailLattice Dynamics of Nanostructured Thermoelectric Materials
Claudio Weber, Tania ULg

Doctoral thesis (2013)

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See detailNew pro-death function of NIK downstream of TNFR1
Boutaffala, Layla ULg

Doctoral thesis (2013)

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See detailCreative Spatializations: New Cartographies in Contemporary Black Canadian Fiction
Mergeai, Mathilde ULg

Doctoral thesis (2013)

My dissertation explores the ways in which contemporary black Canadian novels rewrite national space by integrating into it what might be called past and present black spatialities. Regardless of its ... [more ▼]

My dissertation explores the ways in which contemporary black Canadian novels rewrite national space by integrating into it what might be called past and present black spatialities. Regardless of its official policy of multiculturalism, Canada appears unable to reflect the diversity of its population, one of the most multi-ethnic in the world, which results in the social and spatial exclusion of minorities—whose presence is perpetually construed as ‘recent’—from the dominant national narratives. Starting from Henri Lefebvre’s assertion that “[a] social transformation, to be truly revolutionary in character, must manifest a creative capacity in its effects on daily life, on language and on space” (54), and from the conceptualization of fictional literature as both a product and a producer of geographical creativities, this work considers the literary respatializations of black Canada in five recent novels, At the Full and Change of the Moon (1999) and What We All Long For (2005) by Dionne Brand, Any Known Blood (1997) and The Book of Negroes (2007) by Lawrence Hill, and Soucouyant (2007) by David Chariandy. I specifically examine four topographies through which these writers relate ‘blackness’ to ‘Canadianness,’ namely, the ocean, the city, the rural suburb, and the home space. More specifically, this dissertation illuminates how these literary representations of Canadian space locate this nation within the paradigmatic locations of black history but also show how the country’s social and geographical landscape is marked by the black history that took place in the country itself. Through a multidisciplinary approach which looks at theorizations of space emanating from literary, geographical, and sociological fields of study, I examine how these writers shift the terms of Canadian identity by disrupting the founding narratives of the nation which rely on the country’s wild landscapes and construct Canada as a white-only space. Finally, this dissertation engages with racialized bodies whose interconnectedness with both physical and imaginary spaces allow for a multiplicity of creative spatializations to emerge. [less ▲]

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See detailTrimming the complexity of Ranking by Pairwise Comparison
Hiard, Samuel ULg

Doctoral thesis (2013)

In computer science research, and more specifically in bioinformatics, the size of databases never stops to increase. This can be an issue when trying to answer questions that imply algorithms in ... [more ▼]

In computer science research, and more specifically in bioinformatics, the size of databases never stops to increase. This can be an issue when trying to answer questions that imply algorithms in nonlinear polynomial time with regards to the number of objects in the database, the number of attributes or the number of associated labels per objects. This is the case of the Ranking by Pairwise Comparison (RPC) algorithm. This algorithm builds a model which is able to predict the label preference for a given object, but the computation needs to be performed in an order of N*(N-1)/2 in terms of the number N of labels. Indeed, a pairwise comparator model is needed for each possible pair of labels. Our hypothesis is that a significant part of the set of comparators often contains redundancy and/or noise, so that trimming the set could be beneficiary. We implemented several methods, starting from the simplest one, which merely chooses a set of T comparators (T < N*(N-1)/2) at random, to a more complex approach based on partially randomized greedy search. This thesis will provide a detailed overview of the context we are working in, provide the reader with required background, describe existing preference learning algorithms including RPC, investigate on possible trimming methods and their accuracy, then will conclude on the relevance and robustness of the trimming approximation. After implementing and executing the procedure, we could see that using between N/2 and 2N comparators was sufficient to keep up with the original RPC algorithm, as long as a smart trimming method is used, and sometimes even outperforms it on noisy datasets. Also, comparing the use of base models in regression mode vs. classification mode showed that models built in regression mode may be more robust when using the original RPC. We thus empirically show that, in the particular case of RPC, reducing the complexity of the method gives similar or better results, which means that problems that could not be addressed by this algorithm, or at least not in an acceptable period of time, now can be. We also found that the regression mode yields RPC to be often more robust regarding its base learner parameters, meaning that the quest of optimality, which can also be time-consuming, is less difficult. Yet research on this topic is not over, and we could think of different means to further improve the RPC algorithm or investigate other innovative approaches, which will be discussed in the future work section. Also, the trimming method is not limited to RPC and could be applied to other algorithms which aggregate information provided by a set of models, e.g. the whole multitude of ensemble models used in machine learning. [less ▲]

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See detailStudy of the induced systemic resistance of plants: molecular aspects of the interaction between plant cells and amphiphilic elicitors produced by non-pathogenic rhizobacteria
Henry, Guillaume ULg

Doctoral thesis (2013)

Some non pathogenic rhizobacteria could locally interact with plants, leading to the stimulation of a primed protection state in the host plant. Upon subsequent pathogen attack, this priming state allows ... [more ▼]

Some non pathogenic rhizobacteria could locally interact with plants, leading to the stimulation of a primed protection state in the host plant. Upon subsequent pathogen attack, this priming state allows an accelerated activation of defense responses extending to all organs of the plant. Fundamental as well as applied research about this induced systemic resistance (ISR) has been tremendously boosted in the past decades, driven by its evident potential for biological control of plant diseases in agriculture. However very little information is available about molecular mechanisms governing the recognition by plant cells of ISR-specific elicitors. Various compounds retaining the ability to elicit ISR have been isolated, among which the recently emerged class of biosurfactants. We conducted the present thesis work with the scope to highlight how such amphiphilic compounds are perceived at the plant cell surface to stimulate the systemic plant immune system. In the first part, the strain B. amyloliquefaciens was selected out of other isolates for its technological traits and previously characterized ISR activity. We demonstrated that surfactin is the most competent cyclic lipopeptide (cLP) family produced by this strain to confer ISR on the selected plant model, tobacco. In order to improve our knowledge about the mechanism governing the perception of this biosurfactant at the plant cell surface, we have combined various approaches such as structure/activity (stimulation of the defense-related oxidative burst) relationship, insertion kinetics within membranes of tobacco cultured cells and thermodynamic determination of binding parameters on various model membranes via isothermal titration calorimetry. Our data indicate that surfactin perception relies on a lipid-driven process which is quite uncommon regarding the typical proteic receptor-mediated recognition of molecular patterns governing the plant basal immunity. We then demonstrate that cLPs induce some enrichment or depletion into specific lipid platforms of different proteins. We hypothesize that it may be: (1) the direct consequence of the generation of insertion sites for some proteins in the entire plasma membrane due to specific cLP segregation at lipid phase interfaces; or (2) result from the indirect adjustment of lipid-modifying enzymes activities through an induced rearrangement of the plasma membrane lipid organization. It reinforces the current hypothesis of a role for lipid microdomains-driven lateral compartmentalization in plant cell signaling. The lipid bilayer of target cells could now be considered as the focal point of cLPs perception from where start cellular responses. As they display an original mechanism of action, the class of amphiphilic ISR elicitors to which they belong become more attractive than ever for further development of innovative biopesticides. [less ▲]

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See detailRôle de TGF alpha dans la thérapie du mésothéliome
Costa, Chrisostome ULg

Doctoral thesis (2013)

Background. Malignant mesothelioma (MM) is a cancer of the pleura caused mainly by the inhalation of asbestos fibers. The impact of chemotherapy on the outcome of patients with MM is still unclear. We ... [more ▼]

Background. Malignant mesothelioma (MM) is a cancer of the pleura caused mainly by the inhalation of asbestos fibers. The impact of chemotherapy on the outcome of patients with MM is still unclear. We hypothesized that unresponsiveness to chemotherapy is due to inadequate gene expression in tumor cells. We have previously shown that inhibitors of histones deacetylases (such as valproate, VPA) significantly increases the efficacy of compounds used in chemotherapy. A recent clinical trial on relapsing MM patients has shown that VPA in combination with doxorubicin improves response rates and quality of life. Methods. Using Agilent microarrays, we compared the transcriptome of two types of cell lines (M14K and H28). Bioinformatic analyzes (Ingenuity) identified the most relevant candidate genes. Expression of transforming growth factor-alpha (TGFα) was validated by RT-qPCR and ELISA. TGFα expression level was modulated negatively by RNA interference and positively by transfection of a cDNA vector. TGFα signaling was reduced with EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Apoptosis was evaluated by different techniques assessing DNA fragmentation, phosphatidylserine externalization and caspase activity. Combination chemotherapy was investigated in two mouse models (ZL34 in SCID and AB12 in Balb/c). Results. To study the mechanisms associated with the response to chemotherapy, we compared two types of cell lines (M14K and H28) characterized by a difference in sensitivity to doxorubicin+VPA. We observed that the basal expression level of TGFα was higher in "resistant" H28 compared to "sensitive" M14K cells. To evaluate the functional relevance of TGFα, we modulated its expression either by RNA interference or by transfection of a cDNA vector. A decrease of TGFα expression correlated with induction of apoptosis. Inversely, an inhibition of apoptosis occurred when TGFα was over-expressed. As TGFα is the ligand of EGFR, we tested the effect of gefitinib and erlotinib in combination with VPA+doxorubicin. Both EGFR inhibitors increased apoptosis induced by VPA+doxorubicin in H28 chemoresistant cells. Finally, the VPA+doxorubicin+erlotinib regimen prevented tumor growth in mice. Conclusions. Our data demonstrates that TGFα is involved in the chemoresistance to VPA+doxorubicin, a second-line regimen for MM. Although inefficient alone, tyrosine kinase inhibitors synergize to induce apoptosis in chemoresistant cells and prevent tumor growth in mouse models. [less ▲]

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See detailEtude des interactions entre l'entomofaune et un cadavre: approches biologique, comportementale et chémo-écologique du coléoptère nécrophage, Thanatophilus sinuatus Fabricius (Col., Silphidae)
Dekeirsschieter, Jessica ULg

Doctoral thesis (2013)

La décomposition d’un corps entraîne des changements physiques et biochimiques importants, le cadavre va émettre des odeurs attractives pour certaines espèces et d’autres moins attractives. Au sein des ... [more ▼]

La décomposition d’un corps entraîne des changements physiques et biochimiques importants, le cadavre va émettre des odeurs attractives pour certaines espèces et d’autres moins attractives. Au sein des écosystèmes terrestres tempérés, les insectes sont généralement les principaux organismes qui colonisent un corps selon une séquence plus ou moins prédictive. Ces insectes nécrophages et/ou nécrophiles, principalement des Diptères et des Coléoptères, utilisent le micro-habitat créé par le cadavre comme un substrat nourricier, un site de reproduction, un refuge ou encore comme un territoire de chasse. L’objectif principal de cette thèse était de mieux connaitre l’écosystème cadavre et plus précisément les interactions cadavre-entomofaune sous l’angle novateur de l’écologie chimique. Cette approche pluridisciplinaire combine des études biologiques, électrophysiologiques (EAG), comportementales (olfactométrie) ainsi que des analyses de composés volatils par diverses méthodes analytiques ((TDS)-GC-MS, GCxGC-TOF-MS). Le cochon domestique, substitut couramment utilisé pour modéliser la décomposition humaine, a servi de modèle animal pour les études faunistiques de suivis postmortem et les études visant à caractériser la signature olfactive d’un cadavre au cours du processus de décomposition. L’«odeur de la mort» est constituée par un mélange de centaines de composés organiques volatils cadavériques (COVs) dont le profil qualitatif et quantitatif évoluent au cours du processus de décomposition. Les Coléoptères, acteurs importants de l’écosystème-cadavre, étaient jusqu’à présent délaissés par les entomologistes forensiques au profit des Diptères. Ce travail de recherche s’est intéressé à deux familles de Staphylinoidea: les Staphylinidae et les Silphidae. 62 espèces de Staphylinidae ont été recensées au sein de l’écosystème-cadavre. Une espèce de staphylin ressort nettement de ces études in situ: Creophilus maxillosus. Concernant les Silphidae, 9 espèces de Nicrophorinae et de Silphinae ont été recensées sur les carcasses de porc avec une nette prépondérance des Silphinae. Néanmoins, seul le taxon des Silphinae semble avoir un intérêt potentiel en entomologie forensique et plus particulièrement les Thanatophilus spp. et Necrodes littoralis. T. sinuatus a été choisi comme insecte modèle, son cycle de développement ainsi que celui de N. littoralis ont été étudiés en conditions contrôlées à deux températures constantes. Une approche chémo-écologique, combinant des études EAG et olfactométriques, a été réalisée sur T. sinuatus avec une sélection de molécules cadavériques. Ces essais ont mis en avant le rôle attractif du diméthyldisulfure (DMDS) sur T. sinuatus. Ce composé semble être un marqueur clé dans les processus de décomposition animale. Le p-crésol était quant à lui uniquement attractif pour les mâles de T. sinuatus. Ces découvertes améliorent notre compréhension de l’écosystème cadavre et plus particulièrement la communication chimique entre une espèce de Silphinae et un corps en décomposition. Cette recherche a également permis de mieux connaitre les populations de staphylins et de silphes que l’on retrouve au sein de l’écosystème cadavre. [less ▲]

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See detailL'Institutionnalisation de la Pan-Amazonie
Faria Nunes, Paulo Henrique ULg

Doctoral thesis (2013)

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See detailLes cultes isiaques dans la péninsule Ibérique. Contribution à l'étude du phénomène isiaque dans l'Occident méditerranéen
Puccio, Laetizia ULg

Doctoral thesis (2013)

En 1967, dans son ouvrage plus largement consacré aux religions orientales dans l'Espagne romaine, Antonio García y Bellido offrait une synthèse des cultes isiaques dans la péninsule Ibérique. Après lui ... [more ▼]

En 1967, dans son ouvrage plus largement consacré aux religions orientales dans l'Espagne romaine, Antonio García y Bellido offrait une synthèse des cultes isiaques dans la péninsule Ibérique. Après lui, quelques savants ont tenté d'actualiser son catalogue, d'autres ont posé à la documentation de nouvelles questions. Depuis les années quatre-vingt-dix, Jaime Alvar a écrit une série d'articles sur le sujet, sans jamais les coordonner dans un seul et même volume. Après plusieurs mois de recherches, grâce au matériel déjà connu, il apparaît que l'absence d'une histoire des cultes isiaques dans la péninsule Ibérique peut et mérite d'être comblée. Le développement des études isiaques permet aux chercheurs de poser à la documentation de nouvelles questions, d'autant que les découvertes d'isiaca, aussi ponctuelles soient elles, ont étoffé peu à peu le catalogue des sources. L'apparition de ces documents présume une nouvelle interprétation du phénomène isiaque dans la péninsule Ibérique. A première vue, on sera conduit à enregistrer une évolution, mais il semble qu'elle sera d'abord d'ordre quantitatif. Elle confirmera surtout l'importance de l'étendue des cultes isiaques dans la Péninsule, le principal obstacle restant l'absence de nouvelles données transmises par ces documents. Néanmoins, ces découvertes, considérées dans une perspective plus large, contribueront à améliorer notre vision du phénomène religieux dans un espace géographique dont les spécificités ne manquent pas et actualiseront une recherche en sommeil depuis quarante ans. [less ▲]

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See detailFormes & forces. Lecture conceptuelle d’architectures au travers de champs disciplinaires connexes.
Prégardien, Michel ULg

Doctoral thesis (2013)

This research starts from a lack of conceptualisation, in the architectural field, around the notion of non-figuration. Postmodern Movement’s ideological opposition to Modern Architecture and its ascetic ... [more ▼]

This research starts from a lack of conceptualisation, in the architectural field, around the notion of non-figuration. Postmodern Movement’s ideological opposition to Modern Architecture and its ascetic aesthetic led to the promotion of signs and images. This prevents a reading of Modern Architecture around notions such as openness, opacity linked to non-figuration as defined by Umberto Eco in his essay Opera Operta. U. Eco’s literary analysis finds a relevant synthesis in G. Deleuze’s work who develops three approaches of non-figuration in pictural art : abstract art (P. Mondrian), figural art (F. Bacon) and informal art (J. Pollock). These categories represent a specific way of exceeding figuration and forms in favour of the forces on the canvas. The thesis aims at evaluating the applicability of these categories to Modern Architecture. The study of three architectural theorists - R. Venturi, C. Norberg-Schulz and C. Rowe - allows us to clarify non-figuration in architecture. This leads to point two specific constraints: functionality and presence that involve architecture in a figurative field. The thesis than articulates architecture’s specific restrictions to non-figuration with G. Deleuze’s aesthetic and philosophy. The analysis of P. Eisenman, L.I. Kahn, Le Corbusier and Mies van der Rohe’s buildings show progressively the necessity to enrich architecture with irrationality, a way of exceeding figurative content. Finally, the thesis discusses the theoretical issues of this approach and examines the possibility to analyse architectural history with non-figurative concepts developed in this research. These kinds of processes, freed of their stylistic content, allow, for example, Modern Architecture and Baroque to get closer. This work also establishes the possibility to develop similar processes of analysis between the different artistic fields (painting, literature, architecture) with same results. [less ▲]

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See detailGestion intégrée des ravageurs de céréales et de légumineuses stockées au Sénégal par l’utilisation de substances issues de plantes
Gueye, Momar Talla ULg

Doctoral thesis (2013)

This thesis used an integrated approach to develop options for the control of cereal and legumes insect pests in Senegal combining laboratory and field tests. A diagnostic survey was conducted to fully ... [more ▼]

This thesis used an integrated approach to develop options for the control of cereal and legumes insect pests in Senegal combining laboratory and field tests. A diagnostic survey was conducted to fully understand current storage practices and control methods in foods and seeds. The study focused on traditional practices from the eastern parts of Senegal to develop options in harmony with the populations concerns. Boscia senegalensis is a plant known for its medicinal properties and its food use was the first plant to be tested for the control of Caryedon serratus, the groundnut weevil. We observed that fruits (3% w/w) and crushed leaves (6% w/w) of this species protected groundnuts. B. senegalensis was subsequently used for protection of cowpea, millet and maize against Callosobruchus maculatus, Tribolium castaneum, Sitophilus zeamais and Prostephanus truncatus. Only T. castaneum was insensitive to this plant at low concentrations. Methylisothiocyanate (MITC) is the main active ingredient of this plant liberated from glucocapparin. This molecule can reach C. maculatus and C. serratus larvae and eggs which develop inside grains but concentrations need to be two to four times higher than adults. Ripe fruits still proved to be effective but immature fruits had a higher efficacy. Residues of MITC were detected in the stored grains after treatment, but the treatment had no effect on germination of stored grains. During the study a reliable and effective method to analyze glucocapparin in leaves and fruits of B. senegalensis was developed, during two years in four localities showing an apparently very marked “soil effect”. Highest glucocapparin concentrations were recorded in January at the beginning of dry season and the lowest during the rainy season from August to November, independent of locality. Powdered maize cobs were effective in maintaining maize grain quality in laboratory studies. Observed damage and losses were respectively 5 and 1% at 2.4% (w/w). At higher doses, mixing of powdered maize cobs with grains offered equal protection as Actellic (pyrimiphos-methyl). The efficacy of this control method was tested during two years in farmer’s granaries confirmed the validity of the laboratory tests. The traditional practice of incorporating insecticidal plants within the storage structure did not impact development of pests already established in the granaries. By contrast, storage of maize cobs using a sandwich method with Hyptis spicigera proved to be effective against storage pests. In addition, the storage of non-winnowed maize grains offered a substantial degree of protection against insect infestations. Their composition was carried out by GC-MS/GC-FID analyses. [less ▲]

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See detailMéthodologie d'évaluation énergétique des quartiers périurbains. Perspectives pour le renouvellement périurbain wallon.
Marique, Anne-Françoise ULg

Doctoral thesis (2013)

The process of urban sprawl, which commonly describes physically expanding urban areas, is a major issue for sustainable development. Urban sprawl is known to represent a significant contribution to the ... [more ▼]

The process of urban sprawl, which commonly describes physically expanding urban areas, is a major issue for sustainable development. Urban sprawl is known to represent a significant contribution to the overall energy consumption of a territory for energy needs in buildings and for transportation. In this context, the thesis focuses on the energy assessment of existing suburban neighborhoods. The assessment includes two parts: (1) a computational approach combining dynamic simulation tools and a database of building typologies to determine the energy consumed in heating and (2) an empirical approach to assess the energy consumed by transportation systems (home-to-work and home-to-school journeys). The links between the spatial structure of the territory and energy use for commuting are highlighted. Several renewal strategies are proposed to improve energy efficiency in existing suburban neighborhoods. There investigate the thermal retrofitting of existing neighborhoods, the built density and demolition/reconstruction processes together with the location of the neighborhoods. Urban structure acts upon travel energy consumption for commuting. A good mix between work, schools and dwellings at the local scale, which allows reduced travel distances, is a good strategy to reduce transport energy consumption, whereas means of transport used is only of little impact. Student travel behaviors are specific to the level of education and the type of neighborhood. Finally, the thesis discusses the practical implications of the research to operationalize a suburban renewal that articulates energy efficiency of buildings and neighborhoods but also energy efficiency of the urban structure. [less ▲]

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See detailLearning to Predict End-to-End Network Performance
Liao, Yongjun ULg

Doctoral thesis (2013)

The knowledge of end-to-end network performance is essential to many Internet applications and systems including traffic engineering, content distribution networks, overlay routing, application-level ... [more ▼]

The knowledge of end-to-end network performance is essential to many Internet applications and systems including traffic engineering, content distribution networks, overlay routing, application-level multicast, and peer-to-peer applications. On the one hand, such knowledge allows service providers to adjust their services according to the dynamic network conditions. On the other hand, as many systems are flexible in choosing their communication paths and targets, knowing network performance enables to optimize services by e.g. intelligent path selection. In the networking field, end-to-end network performance refers to some property of a network path measured by various metrics such as round-trip time (RTT), available bandwidth (ABW) and packet loss rate (PLR). While much progress has been made in network measurement, a main challenge in the acquisition of network performance on large-scale networks is the quadratical growth of the measurement overheads with respect to the number of network nodes, which renders the active probing of all paths infeasible. Thus, a natural idea is to measure a small set of paths and then predict the others where there are no direct measurements. This understanding has motivated numerous research on approaches to network performance prediction. Commonly, the success of a prediction system is built on its scalability, efficiency, accuracy and practicability. For network performance prediction, two specific requirements have to be met. First, the prediction system should have a decentralized architecture which allows the natural deployment of the system within a networked application. Second, as different performance metrics are useful for different applications, the prediction system should be general and flexible to deal with various metrics in a unified framework. This thesis presents practical approaches to network performance prediction. There are three main contributions. First, the problem of network performance prediction is formulated as a matrix completion problem where the matrix contains performance measures between network nodes with some of them known and the others unknown and thus to be filled. This new formulation is advantageous in that it is flexible to deal with various metrics in a unified framework, despite their diverse nature. The only requirement is that the matrix to be completed has a low-rank characteristic, which has long been observed in performance matrices constructed from various networks and in various metrics. Second, the matrix completion problem is solved by a novel approach called Decentralized Matrix Factorization by Stochastic Gradient Descent (DMFSGD). The approach requires neither explicit constructions of matrices nor special nodes such as landmarks and central servers. Instead, by letting network nodes exchange messages with each other, matrix factorization is collaboratively and iteratively achieved at all nodes, with each node equally retrieving a number of measurements. The approach is practical in that it is simple, with no infrastructure, and is computationally lightweight, containing only vector operations. Third, instead of the conventional representation of exact metric values, this thesis also investigates coarse performance representations including binary classes (The performance is classified into binary classes of either ``good'' or ``bad''.) and ordinal ratings (The performance is quantized from 1 star to 5 stars.). Such more qualitative than quantitative measures not only fulfill the requirements of many Internet applications, but also reduce the measurement cost and enable a unified treatment of various metrics. In addition, as both class and rating measures can be nicely integrated in the matrix completion framework, the same DMFSGD approach is applicable for their prediction, with little modification required. The resulting prediction system has been extensively evaluated on various publicly-available datasets of two kinds of metrics, namely RTT and ABW. These experiments demonstrate not only the scalability and the accuracy of the DMFSGD approach but also its usability in real Internet applications. In addition, the benefits of predicting performance classes and ratings, rather than their actual values, are demonstrated by a case study on peer selection, a function that is commonly required in a number of network applications. [less ▲]

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See detailEtude de grains et de matière granulaire sous champs électriques
Mersch, Eric ULg

Doctoral thesis (2013)

Electric fields have been used to modify properties of dilute and dense granular materials. For the dilute case, we showed that electric fields can be used to inject kinetic energy on the material. We ... [more ▼]

Electric fields have been used to modify properties of dilute and dense granular materials. For the dilute case, we showed that electric fields can be used to inject kinetic energy on the material. We studied the dynamics of a single bead, two beads and three beads systems. The dynamics is described by a mathematical model which is in quantitative agreement with experiments. A synchronization effect is observed and it is described by a phase coupled oscillators model. We also show that electric fields can be used to tune the cohesion of dense granular media. A transition of the geometry of the flow is observed. Intermittences are induced by the electric field. [less ▲]

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See detailEssays in Portfolio Performance Analysis
Cogneau, Philippe ULg

Doctoral thesis (2013)

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See detailPlan de Cohésion Sociale en Région wallonne : Enjeux du système d’évaluation au niveau local et critères pertinents pour l’évaluation de la qualité d’un partenariat local.
Parotte, Céline ULg

Master's dissertation (2013)

En novembre 2008, la Région wallonne adoptait le Décret du 6 novembre 2008 intitulé « Plan de cohésion sociale des villes et communes de Wallonie».(Région wallonne (2008), Décret du 6 novembre 2008 ... [more ▼]

En novembre 2008, la Région wallonne adoptait le Décret du 6 novembre 2008 intitulé « Plan de cohésion sociale des villes et communes de Wallonie».(Région wallonne (2008), Décret du 6 novembre 2008 relatif au plan de cohésion sociale dans les villes et les communes de Wallonie) Prolongement du Plan de Prévention de Proximité (PPP) adopté en 2003, le plan de cohésion sociale est une application du concept européen du même nom au contexte wallon. Il tend à promouvoir l’accès de tous aux droits fondamentaux dont les actions se coordonnent autour de quatre axes : l’insertion socioprofessionnelle (1), l’accès à un logement décent (2), l’accès à la santé et le traitement des assuétudes (3), le retissage des liens sociaux, intergénérationnels et interculturels (4). Localement, la mise en œuvre de ces plans d’actions doit répondre à plusieurs contraintes dont celle d’être soumise annuellement à un processus d’évaluation adapté et participatif qui implique les partenaires locaux. Aussi, chaque année depuis 2009, un rapport d’activités et un rapport financier sont élaborés et les deux dernières années de mise en œuvre du plan, le Décret prévoit un rapport d’évaluation intermédiaire (troisième année) et un rapport d’évaluation final (dernière année) eux aussi, rédigés par les acteurs locaux. Ce rapport d’évaluation au niveau local est rédigé sur base de deux évaluations menées par le chef de projet de la Commune et un partenaire impliqué ; une évaluation d’impact avec les bénéficiaires du Plan local et une évaluation d’impact avec les partenaires locaux. (DiCS, 2012b) L’ensemble de l’évaluation local des Plans de Cohésion Sociale s’est déroulée sous l’encadrement de la Direction interdépartementale de la cohésion sociale (DiCS) en collaboration avec l’IWEPS d’une part et l’Université de Liège d’autre part. Dans le cadre de ce travail de fin de formation, nous tâcherons de répondre à deux questions. Par conséquent, ce travail se divise en deux parties pratiquement indépendantes l’une de l’autre. Premièrement, comment les partenaires participent à l’évaluation locale ? Deuxièmement, comment évaluer la qualité des partenariats locaux ? [less ▲]

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See detailConsommation de pornographie à l'adolescence : entre recherche de sensations et solitude...
Puglia, Rosa ULg

Master's dissertation (2013)

L’adolescence est une période tumultueuse durant laquelle l’individu fait l’expérience de nombreux changements, ce qui le rend sensible à diverses influences. Ainsi, à cette étape de leur vie, les jeunes ... [more ▼]

L’adolescence est une période tumultueuse durant laquelle l’individu fait l’expérience de nombreux changements, ce qui le rend sensible à diverses influences. Ainsi, à cette étape de leur vie, les jeunes vont, d’une part, surinvestir la sphère sociale et, d’autre part, développer un attrait pour la sensation, la sexualité et d’autres facteurs que nous allons tenter de mettre en lien avec l’exposition aux médias sexuellement explicites. Ce mémoire, réalisé sur une population de 319 adolescents issus de divers enseignements de la région liégeoise, présente deux objectifs principaux. Le premier est d’analyser, d’une part, les liens entre la consommation de pornographie et d’autres variables comme les conduites sexuelles, la recherche de sensation, la délinquance auto-révélée, la popularité et la solitude ; et d’autre part, d’examiner les liens entre la recherche de sensations et les conduites sexuelles à l’adolescence. Le second est d’établir le profil des adolescents consommateurs de pornographie et de déterminer d’éventuelles caractéristiques qui les différencient de leurs pairs non-consommateurs. Nos résultats indiquent la présence de corrélations significatives entre la consommation de pornographie et la plupart des variables étudiées ; seuls la sexualité et la solitude n’apparaissent pas liées à l’exposition à la pornographie. De plus, cette étude a permis de mettre en évidence des caractéristiques particulières chez les jeunes consommateurs, que l’on ne retrouvent pas chez leurs pairs non-consommateurs. Néanmoins, même si cette recherche nous a amené à conclure que les pratiques sexuelles des consommateurs sont plus diversifiées et permissives que celles des non-consommateurs, celles-ci ne sont pas liées à l’exposition à la pornographie. En revanche, ce média sexuellement explicite semble corrélé à la recherche de sensations, aux conduites déviantes et à la popularité ; ce qui peut nous laisser penser qu’il serait une expérience qui s’insère dans l’exploration et la tendance à repousser les limites inhérentes à l’adolescence. [less ▲]

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See detailCARACTERISATION ET AMELIORATION DE LA QUALITE DE LA BIERE TRADITIONNELLE RWANDAISE « IKIGAGE » FABRIQUEE A BASE DE SORGHO
Lyumugabe Loshima, François ULg

Doctoral thesis (2013)

Ikigage is a Rwandese traditional beer made from sorghum malt and local plants, mainly Vernonia amygdalina “umubirizi”. However, this beer remains less attractive than Western beers of pils type because ... [more ▼]

Ikigage is a Rwandese traditional beer made from sorghum malt and local plants, mainly Vernonia amygdalina “umubirizi”. However, this beer remains less attractive than Western beers of pils type because of poor hygienic quality, variations of organoleptic quality and limited shelf life. The aim of this work is to characterize ikigage beer in order to improve its hygienic quality and to reduce the organoleptic variations using the local raw materials. The first part of our study shows that ikigage beer marketed in Rwanda is characterized by the presence of Stapylococcus aureus and many micro-organisms of fecal origin (Escherichia coli and fecal streptococci), by the low ethanol content, high total acidity and an important amounts of proteins. The yeasts (Saccharomyces cerevisiae and Issatckenkia orientalis), followed by the lactic acid bacteria (Lactobacillus fermentum and Lactobacillus buchneri), are the predominant microorganisms involved in fermentation of ikigage beer fermentation. Besides, one of the major problems in sorghum beer brewing is the efficient conversion of the starch extracts into fermentable sugars due to the weak activity of β-amylase in sorghum malt. The use of Eleusine coracana “uburo” (Musama variety) malt (30%), associated with mashing decantation procedure, increases the content of sugar fermentable, maltose particularly, in sorghum wort, and consequently ethanol content in the beer. The second part of our study shows that V. amygdalina, known for its antibacterial properties and its bitterness similar to hops, contributes to the production of methyl salycilate, beta-damascenone and many terpenes compounds (δ-3-carene, β-farnesene, farnesol, β-citronellol and linalool), in the sorghum beer “ikigage”. This work reveals also the presence of 14 polyfunctional thiols in beers brewed with ‘non-Western’ raw materials. Among them, the well-known hop constituent 3-methyl-2-buten-1-thiol emerged as a key flavour in the unhopped beers containing V. amygdalina. V. amygdalina also contributes to the production of 1-butanethiol and 4-sulfanyl-4-methyl-2-pentanone in sorghum beer. However, contrary to hops, V. amygdalina addition during boiling also appears to strongly inhibit the production of 2-sulfanylethyl acetate. The third part of our study shows that the use of S. cerevisiae in combination with I. orientalis and L. fermentum as starter allows producing ikigage beer having the GRAS (generally recognized as safe) statute while preserving the organoleptic characteristics similar to those of local traditional beer “ikigage” produced by peasants. [less ▲]

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See detailOrigin, biodiversity, and extinction of Cretaceous ichthyosaurs
Fischer, Valentin ULg

Doctoral thesis (2013)

Ichthyosauria is a group of reptiles that colonized numerous niches in Mesozoic marine ecosystems. Their Cretaceous representatives were however regarded as undiversified, especially compared to their ... [more ▼]

Ichthyosauria is a group of reptiles that colonized numerous niches in Mesozoic marine ecosystems. Their Cretaceous representatives were however regarded as undiversified, especially compared to their Triassic and Jurassic ancestors, because only a few species are regarded as valid in the Cretaceous. Besides, most of them belong to a single genus, Platypterygius, whose taxonomy and phylogeny are problematic. Therefore, Cretaceous ichthyosaurs have been widely considered as the last members of a group on the decline, although the timing, the cause and the magnitude of their extinction phases greatly vary among authors. Yet, a great part of the Cretaceous ichthyosaur record, the Eurasian material, has been neglected from more than 100 years; theories explaining the evolution of the last ichthyosaurs therefore miss the biggest part of the picture. Notably, how ichthyosaurs diversified and went extinct during the Cretaceous is basically unknown. To tackle these topics, I assess the taxonomy of Cretaceous ichthyosaurs from Eurasia, test their phylogenetic position within a global analysis of post-Triassic ichthyosaurs, evaluate their ecological diversity and analyse their phases of radiation and extinction. Assessment of the Eurasian material led to the discovery of seven new taxa (“Iraq animal”, Acamptonectes densus, “Lenin Form”, Sveltonectes insolitus, Sveltonectes “Ebbo Form”, “Sisteron Form”, “Colossal Form”) and the re-installation of several other taxa as valid (Simbirskiasaurus birjukovi, P. bannovkensis, Cetarthrosaurus walkeri, P. hercynicus). Morphological and phylogenetic evidence suggest Platypterygius hides a very large generic diversity and should be limited to its type species P. platydactylus; however, the interrelationships of the large platypterygiine ichthyosaurs from the Aptian–Cenomanian interval are poorly constrained. Phylogenetic analyses provide robust evidence for disparate origins of Cretaceous ichthyosaurs; these animals actually belonged to three distinct clades that diverged several tens of million years before the Cretaceous. These three clades had contrasted evolutionary histories and colonized disctinct ecological niches during the Cretaceous. Survival and extinction rates demonstrate ichthyosaurs suffered no extinction event at the Jurassic–Cretaceous boundary. They were therefore highly diverse during the Cretaceous, although the sampling of some stages remains inadequate. Notably, up to eight genera were present during the late Albian, a few million years before their final extinction. This extinction appears staggered over four phases that span the entire Cenomanian stage; it also forms one of the facets of a much wider event that affected most levels of marine trophic chains during the Cenomanian. Compilation of published data and collaborations with other specialists show that the radiation of snakes, mosasaurs, and numerous lineages of modern fishes, the severe extinctions among cephalopods and rudist bivalves and the complete extinction of ichthyosaurs likely belong to the same global turnover event. The magnitude, diversity and simultaneity of the biotic responses strongly suggest that global physico-chemical factors triggered this profound reorganization of the marine ecosystems, notably the conjunction of a rather brutal onset of extremely high temperatures and sea level, intense marine volcanism and phases of worldwide ocean anoxia. [less ▲]

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See detailEvaluation of Electronic Nose Technology for Early-warning of Bio-methanation Process Disturbance
Adam, Gilles ULg

Doctoral thesis (2013)

An electronic nose (e-nose) is an instrument composed of an array of non specific gas sensors inspired by the biological olfactory system for the detection and recognition of odours. In this work, this ... [more ▼]

An electronic nose (e-nose) is an instrument composed of an array of non specific gas sensors inspired by the biological olfactory system for the detection and recognition of odours. In this work, this technology is evaluated to predict process disorders in agricultural anaerobic digestion reactors. Response of the sensor array is used to recognize a gas mixture by the use of multivariate data analysis techniques. In our case, an e-nose developed in our laboratory and composed of metal oxide semi-conductor gas sensors was equipped with a biogas dilution system to realize the measurements. When employed on small-scale digesters fed with simple feeding substrates (sucrose, lipids, mixture lipids and sucrose), the e-nose presented enthusiastic results for the detection of organic overload disorders. Multivariate process control charts were employed with the e-nose data to obtain a simple state indicator represented by the Hotelling's T² statistics. This indicator resumes the general state of the digesters when its value exceeds statistically defined control limit. Instability periods and recovery of the anaerobic digestion process when exposed to organic overfeeding could be thus precisely assessed. In addition, the use of a variety of substrates had no significant effect on the performance of the e-nose monitoring. Variations of methane content in biogas, as a result of use of substrates of different compositions, had neither any influence on the e-nose monitoring quality. Thereafter, an e-nose was placed online on continuously stirred tank reactor of 100 L over a period of 300 days. A multivariate monitoring method using recursive and adaptive principal component analysis (PCA) was applied to the e-nose data. This enabled to very efficiently compensate system drift and notably sensor drift. Moreover, adaptive PCA model could also adapt to environmental variations and to reactor slow shifts. T² statistics and its squared prediction error (SPE) obtained from the PCA model are very competitive state indicators compared to pH, alkalinity, gas production rate and methane and carbon dioxide content. Two electronic noses were also evaluated in real-scale agricultural anaerobic digestion plants. The low process state monitoring in both plants does not enable to conclude to the relevance of disorders observed by the e-nose apparatus and demonstrates the real need for online anaerobic digestion process state monitoring and its subsequent optimization in agricultural biogas plants. Even though, the performance of the recursive PCA monitoring is much superior to that of static PCA. Adaptive PCA proves to be a potential automatic drift and environmental variations correction method for online and real-time e-nose measures, notably for field applications. In conclusion, it was demonstrated in this work that e-nose technology has a real potential as an application of online monitoring of anaerobic digester state. Moreover, this research demonstrated that it was possible to realize a monitoring of the state of anaerobic digesters using only gas phase measurements. Another contribution is the use of multivariate process control techniques on e-nose data to obtain a simple state indicator as well as the use of adaptive PCA to automatically compensate drift and environmental effects on e-nose measurements. [less ▲]

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See detailInvolvement of the lipoxygenase pathway in the systemic resistance induced by Plant Growth-Promoting Rhizobacteria in tomato
Mariutto, Martin ULg

Doctoral thesis (2013)

The treatment of plant roots with some Plant Growth Promoting Rhizobacteria (PGPR) results in the enhancement of the immune capacity of the host against phytopathogens. This phenomenon called Induced ... [more ▼]

The treatment of plant roots with some Plant Growth Promoting Rhizobacteria (PGPR) results in the enhancement of the immune capacity of the host against phytopathogens. This phenomenon called Induced Systemic Resistance (ISR) is observed in the whole plant and is effective against a broad spectrum of diseases. Many previous studies showed that this resistance is associated, in some pathosystems, with the stimulation of the key enzyme of the lipoxygenase (LOX) pathway. This defense pathway synthesizes antibiotic and signal compounds called oxylipins from poly unsaturated fatty acids. The main goal of our work was to analyse the involvement of the LOX pathway during the ISR in tomato plants The different steps of the pathway were analyzed at the transcriptional, enzymatic and metabolic levels in leaves of tomato plants elicited with the PGPR Pseudomonas putida BTP1, before and after infection by the fungal pathogen Botrytis cinerea. Our study showed that the bacterial treatment reprogrammed the LOX pathway. Before infection, the activity of the key enzyme of the pathway, the LOX, was higher in P. putida BTP1-treated plants compared to control plants. This stimulation resulted in the accumulation 13-hydroperoxy fatty acids and 13-hydroxyfatty acids conjugated to phospholipids and galactolipids. These products could constitute a pool of antifungal compounds that can be used during the pathogen attack. During the first days after B. cinerea inoculation, the LOX activity, the accumulation of one of its substrate (linolenic acid) and of its products were stimulated in treated plants as compared to control plants. The increase of LOX activity was caused by the induction of the expression level of two Lox genes: TomLoxD and TomLoxF. We observed a decrease of the pool of conjugated oxylipins and a concomitant increase of non conjugated oxylipins, associated with the stimulation of the phospholipase A2 activity. The branches of the pathway which can use the products of the LOX as substrate were differentially regulated resulting in the accumulation of fungitoxic oxylipins against B. cinerea. In order to determine if the induction of the LOX pathway is a general feature of the ISR in tomato, the effect of other PGPR and resistance elicitors produced by PGPR was analysed. Three pure bacterial elicitors sharing common biosurfactant features (the n-alkylated benzylamine derivative (NABD) produced by P. putida BTP1, the surfactin synthesized by many Bacillus strains and rhamnolipids purified from P. aeruginosa) and six Bacillus strains including strong, medium and non producers of surfactin were applied onto tomato roots. The analysis of the key points of the modulation of the LOX pathway showed that the plant molecular response depended on the studied organ (root / leaf), the nature of the elicitor and the amount of elicitor produced by the PGPR. In addition to our study on the involvement of the LOX pathway, we searched other mechanisms potentially induced in ISR-expressing plants. The combination of histological staining, quantification of enzymatic activities and analysis of the genome expression by hybridization on DNA gene chips showed additional defense genes and pathways involved in the resistance in tomato. In conclusion, our work showed that the LOX pathway is one of the defense mechanisms which can be involved in ISR in tomato. The elicitation of the resistance allows the plant to prepare to a future infection, and to respond faster and in a more effective way to a subsequent pathogen invasion. [less ▲]

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See detailDéveloppement et Construction d'un Drone - Etude Aérodynamique et Système de Commandes
Vanden Branden, Nicolas ULg

Master's dissertation (2013)

This work is the continuation of a longstanding project which aims at developping a fixed-wing unmanned air vehicule. This UAV has a high-mounted wing, a pushing propeller and its designated payload is a ... [more ▼]

This work is the continuation of a longstanding project which aims at developping a fixed-wing unmanned air vehicule. This UAV has a high-mounted wing, a pushing propeller and its designated payload is a stereoscopic camera fixed on the front of the fuselage, surrounded by a fixed plexiglas globe. Based on the four previous years of developpement, two colleagues and I have modified and developped the design further. This year, a real-scale wing was manufacturerd in order to conduct mechanical tests on it. Furthermore, a new, aerodynamic-efficient half-scale fuselage was developped to study the aerodynamics of the new design in the wind tunnel of the University of Liège. This report is articulated about four main chapters. The first develops the changes applied to the \textbf{modified fuselage}, the constraints we faced in conceiving it and experimental data gathered from the wind tunnel. Second, an \textbf{aerodynamic study} is conducted on the whole half-scale model, that is including a wing and an empennage. Alas, due to a technical problem with a 6-axes sensor of the wind tunnel, no equilibrium study has been conducted; only 3-axes mesures were available. Third, an in-depth study is conducted on the \textbf{propulsive system}. The motor was also tested in the wind tunnel in order to obtain the quadratic thrust curve, and hence the performances at take off and in flight. A design change to a twin-engine configuration is also introduced. Last, the \textbf{flight control surfaces} are sized following given flight constraints, and the servomotors acting on those surfaces are selected based on the couple computed at the hinge of the mobile surface. As such, this work tries to address some hurdles raised in the previous reports, particularly on the aerodynamic and performance side. [less ▲]

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

Detailed reference viewed: 49 (10 ULg)
See detailThe role of galectins in the vasculature
Heusschen, Roy ULg

Doctoral thesis (2013)

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

Master's dissertation (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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