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See detailApplication of wavelet transforms to geosciences: Extraction of functional and frequential information
Deliège, Adrien ULg

Doctoral thesis (2017)

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function ... [more ▼]

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function can be characterized by its Hölder exponent at each point. For the sake of practicability, it is more appropriate to determine the “size” of the sets of points sharing a same exponent, through their Hausdorff measure. By doing so, one gets the multifractal spectrum of a function, which characterizes in particular its monofractal or multifractal nature. The first part of this work is based on the so-called “wavelet leaders method” (WLM), recently developed in the context of multifractal analysis, and aims at its application to concrete situations in geosciences. First, we present the WLM and we insist particularly on the major differences between theory and practice in its use and in the interpretation of the results. Then, we show that the WLM turns out to be an efficient tool for the analysis of Mars topography from a unidimensional and bidimensional point of view; the first approach allowing to recover information consistent with previous works, the second being new and highlighting some areas of interest on Mars. Then, we study the regularity of temperature signals related to various climate stations spread across Europe. In a first phase, we show that the WLM allows to detect a strong correlation with pressure anomalies. Then we show that the Hölder exponents obtained are directly linked to the underlying climate and we establish criteria that compare them with their climate characteristics as defined by the Köppen-Geiger classification. On the other hand, the continuous version of the wavelet transform (CWT), developed in the context of time-frequency analysis, is also studied in this work. The objective here is the determination of dominant periods and the extraction of the associated oscillating components that constitute a given signal. The CWT allows, unlike the Fourier transform, to obtain a representation in time and in frequency of the considered signal, which thus opens new research perspectives. Moreover, with a Morlet-like wavelet, a simple reconstruction formula can be used to extract components. Therefore, the second part of the manuscript presents the CWT and focuses mainly on the border effects inherent to this technique. We illustrate the advantages of the zero-padding and introduce an iterative method allowing to alleviate significantly reconstruction errors at the borders of the signals. Then, we study in detail the El Niño Southern Oscillation (ENSO) signal related to temperature anomalies in the Pacific Ocean and responsible for extreme climate events called El Niño (EN) and La Niña (LN). Through the CWT, we distinguish its main periods and we extract its dominant components, which reflect well-known geophysical mechanisms. A meticulous study of these components allows us to elaborate a forecasting algorithm for EN and LN events with lead times larger than one year, which is a much better performance than current models. After, we generalize the method used to extract components by developing a procedure that detects ridges in the CWT. The algorithm, called WIME (Wavelet-Induced Mode Extraction), is illustrated on several highly non-stationary examples. Its ability to recover target components from a given signal is tested and compared with the Empirical Mode Decomposition. It appears that WIME has a better adaptability in various situations. Finally, we show that WIME can be used in real-life cases such as an electrocardiogram and the ENSO signal. [less ▲]

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See detailLes constructions relatives du néo-égyptien. Une approche fonctionnelle
Sojic, Nathalie ULg

Doctoral thesis (2017)

Cette dissertation doctorale se propose d’étudier les constructions relatives du néo-égyptien suivant une approche fonctionnelle. Elle offre une première étude large de la relativisation pour cet état de ... [more ▼]

Cette dissertation doctorale se propose d’étudier les constructions relatives du néo-égyptien suivant une approche fonctionnelle. Elle offre une première étude large de la relativisation pour cet état de langue sous l’angle de la variation linguistique. Elle comprend deux grandes parties : les chapitres 1 à 4 sont théoriques, les chapitres 5 à 9 constituent la recherche à proprement parler. Le chapitre 10 conclut l’ensemble. Le premier chapitre (Ch. 1) propose un état de la question des études relatives aux constructions relatives en égyptien ancien et met en avant le manque criant de vision d’ensemble des descriptions et des études proposées jusqu’à présent, tous états de langue confondus. Le chapitre suivant (Ch. 2) définit le cadre théorique dans lequel s’inscrit l’étude, à savoir les bases conceptuelles et terminologiques issues du fonctionnalisme en linguistique. J’y fais également le point sur le recours, en égyptologie, à ces théories. Le troisième chapitre (Ch. 3) est consacré à la délimitation et à la description du corpus, l’accent étant mis sur la variation linguistique (en diachronie et en synchronie dynamique). Je propose ensuite (Ch. 4) un préambule ou un excursus relatif à la définition des « parties du discours », catégories d’après lesquelles sont classées les unités qui composent la phrase. La plupart des études fonctionnelles, dont la présente, ont pour objet l’une de ces catégories. Le cinquième chapitre (Ch. 5) offre une vue d’ensemble des constructions relatives et constructions apparentées en égyptien ancien (ancien, moyen et néo). La description, très générale, vise à rendre compte de leurs principales caractéristiques typologiques et des particularités de la langue étudiée. Le chapitre suivant (Ch. 6) est consacré à l’histoire du système : il en présente les grandes tendances distributionnelles aux stades de la langue antérieurs au néo-égyptien. Cette synthèse montre l’existence de jeux d’oppositions à l’œuvre à une époque donnée et permet d’en constater l’évolution au stade concerné. Dans un autre chapitre, (Ch. 7) j’examine en détail l’expression de la négation dans les relatives. Après y avoir exposé les facteurs de variation spécifique à l’évolution de la négation, je propose une taxonomie fonctionnelle des constructions relatives négatives en néo-égyptien. Plus loin (Ch. 8), je me penche sur l’épineuse question de la valeur sémantique des relatives introduites par nty (« vraies » relatives) et de celles introduites par iw (relatives « virtuelles », c’est-à-dire des circonstancielles fonctionnant comme des relatives). Ma démarche, issue d’une réflexion critique à partir des études menées sur les différents types de relatives dans d’autres langues, m’amène à suggérer que, contrairement à ce qui a été dit pour l’égyptien ancien, leur distribution ne dépend pas uniquement de la définition de l’antécédent ou de la nature du relateur, mais que la valeur sémantique – contingente ou non – de la construction relativisée joue un rôle tout aussi important. Cette nouvelle façon d’aborder le problème permet d’apporter une explication quant à la grammaticalisation observée dans la distribution de ces constructions. L’avant dernier chapitre (Ch. 9) propose une étude approfondie de l’omission du pronom de rappel de l’antécédent dans les relatives du néo-égyptien. J’y recours aux concepts d’échelle d’accessibilité à la relativisation élaborée par Keenan & Comrie (1977), d’échelle d’accessibilité cognitive d’Ariel (1990) et aux travaux d’Hawkins (1999, 2004) relatifs à la structure informationnelle de la phrase complexe. Ce faisant, je définis des contextes particulièrement favorables à une omission, et démontre aussi que ces omissions sont en partie motivées par des facteurs extralinguistiques. Le dernier chapitre (Ch. 10) fait office de conclusion générale. Il fait le point sur l’apport des chapitres précédents et sur les différents types de variations mis en évidence dans cette étude. [less ▲]

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See detailClimate change and insect pests: Impact on carbon dioxide increase on aphid behavior and semiochemistry
Boullis, Antoine ULg

Doctoral thesis (2017)

There is no longer any doubt on the incidence of rising carbon dioxide (CO2) concentration on global change. Climate modifications are responsible of perturbations in interactions between living organisms ... [more ▼]

There is no longer any doubt on the incidence of rising carbon dioxide (CO2) concentration on global change. Climate modifications are responsible of perturbations in interactions between living organisms. This research topic is in the light of scientists since several decades and is considered to be of major interest in the understanding of future ecosystems’ functioning. In this prospect, interactions between insect herbivores and their natural enemies have received little attention under a climate change scope, while they are of paramount importance in the proper equilibrium of agro-ecosystems. As the efficacy of natural enemies is governed largely by behavioral mechanisms, changes in the predators’ behaviors but also in those related to prey defenses can change the dynamics of insect populations. As aphids are considered as one of the main crop pests in temperate regions, relative literature on impact of increases in atmospheric CO2 concentrations on aphid population dynamic now exists. However, few publications about their chemical ecology are reported. Aphids are using many chemical signals to communicate with each other or in their interactions with higher trophic levels. Here, I tempted to identify the impact of an increase in atmospheric CO2 concentration on the interactions between aphids and their natural enemies mediated by semiochemicals. Aspects of phytovirus transmission by aphids were also covered. After being involved in three literature reviews, I was interested in the aphid alarm signaling which strongly supports aphid-predators interactions. In the pea aphid Acyrthosiphon pisum (Harris), this signaling is mediated by a pheromone, namely the (E)-β-farnesene. For my experiments, I took into consideration the importance of all the steps that this molecule has to pass by, from its production into the emitter individual to the induced behavioral response of the receivers. The results obtained during these experiments highlighted an imbalance in aphid chemical communication for populations grown under elevated CO2 conditions, by modifications in several steps of the signal (decrease in pheromone production, emission and associated behavior). The results obtained here were supported by previous studies indicating that increases in CO2 concentration reduce the aphid escape behavior, which makes them potentially more susceptible to predation. We know that many plant pathogens are dependent on aphid dispersal to spread, so it is of major importance to predict how these insect vectors could be affected by forecasted climate. I thus carried my interest on the ability of aphids to transmit phytoviruses under changing atmosphere. Using another aphid model, the green peach aphid Myzus persicae (Sulzer), we have not observed any modifications in terms of virus and aphid spread in laboratory trials when tested under either actual or forecasted CO2 concentration. However, the viral transmission efficiency via aphids is increased under CO2-enriched atmosphere. Finally, the host searching behavior of an aphid predator was studied. The efficiency of natural enemies of insect pests is mainly driven by their ability to find food sources or oviposition sites in their environment. The conducted study highlighted the preference of the hoverfly Episyrphus balteatus De Geer towards aphid colonies grown under actual CO2 levels, suggesting modifications in chemical cues guiding hoverflies to a suitable oviposition site, due to increase of CO2. The results and knowledge obtained during these studies will add novel information on how a major component of climate change may impact tritrophic interactions and thus the efficiency of natural enemies of insect herbivores in biological control scope. [less ▲]

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See detailCaractérisation et élaboration d'un outil de surveillance des cuvettes oasiennes et de leurs alentours par télédétection et système d'information
Karimou Barké, Mahamadou Salifou ULg

Doctoral thesis (2017)

Situées en zone semi-aride, les cuvettes oasiennes du centre-est du Niger sont des agro-écosystèmes à hautes potentialités. C’est seulement à l’intérieur de ces dernières que l’agriculture est possible ... [more ▼]

Situées en zone semi-aride, les cuvettes oasiennes du centre-est du Niger sont des agro-écosystèmes à hautes potentialités. C’est seulement à l’intérieur de ces dernières que l’agriculture est possible durant toute l’année. Ces cuvettes oasiennes ont connu de nombreux investissements de la part de plusieurs ONGs et projets au cours des dernières années. Cependant, elles sont souvent peu connues par ces acteurs du développement du fait de leur grand nombre et de leur extrême diversité. Cette thèse cherche à réduire cette méconnaissance à travers les activités suivantes: • évaluer les performances de trois méthodes de classification d’images appliquées à la détection de ces cuvettes oasiennes dans le Département de Gouré. Ces méthodes sont l’analyse pixellaire, l’analyse texturale et l’analyse par objet. Elles sont appliquées à des images SPOT 5-THX de 2.5 m de résolution ; • caractériser la forme des cuvettes oasiennes avec deux indices morphologiques (l’indice de compacité de Gravelius et l’indice fractale de leurs contours) ainsi que leurs orientations en utilisant les secteurs de la rose de vent comme repères ; • évaluer les contraintes et potentialités liées aux unités de paysage des cuvettes et de leurs alentours pour l’ensemble des cuvettes oasiennes à partir des extensions de ces unités de paysage, élaborer des indicateurs spatiaux de caractérisation des cuvettes ; • analyser la dynamique de l’occupation des sols de cuvettes oasiennes et de leurs alentours en utilisant les images Landsat 5-TM de 1984, les images SPOT 3 de 1996 et les images SPOT 5-THX de 2013. • proposer un outil de monitoring et une esquisse de système expert orienté à partir des données récoltées par ce biais sur l’ensemble des cuvettes de la zone d’étude. L’évaluation des résultats montre que l’approche par objet (précision globale égale à 97.12%, coefficient Kappa égal à 0.97) est plus performante que celles utilisant la texture (précision globale égale à 89.61%, coefficient Kappa égal à 0,90) et l’analyse par pixel (précision globale égale à 80.58 %, coefficient Kappa égal à 0.80). Une première information originale, à savoir le nombre, la position et la surface de l’ensemble des cuvettes sur la zone d’étude est fournie. Le nombre total de cuvettes oasiennes dans le Département de Gouré est ainsi estimé à 10717. Cet inventaire de ces lieux stocks de ressources est une première étape obligatoire pour leur caractérisation morphologique et pour l’évaluation de leurs potentialités agricoles. L’indice de forme de Gravelius met en évidence une certaine diversité de leurs contours : des cuvettes circulaires (9%), ovales (47%), amiboïdes (11%), étirées (18%) et très étirées ou étirées-amiboïdes (16%). La dimension fractale permet de distinguer trois classes de cuvette selon le degré de lissage de ces contours : très lissées (39%), lissées (50%) et moyennement lissées (10%). Le lissage est interprété ici comme un indicateur d’éolisation des pourtours des cuvettes. Enfin la détermination de l’orientation des grands axes des cuvettes a permis d’identifier quatre secteurs majeurs : E-W (23%), N-S (21%), NE-SW (22%) et SE-NW (34%). Ces analyses morphologiques et d’orientation appliquées pour la première fois à l’ensemble des cuvettes oasiennes du Département de Gouré offrent des éléments permettant de comprendre les processus d’ensablement des cuvettes oasiennes dans cette zone. L’analyse des indicateurs des potentialités naturelles à la mise en valeur agricole montre que les cuvettes oasiennes sont des espaces multi-usages, avec des aptitudes en arboriculture, maraîchage, en natron et en foresterie selon les unités géomorphologiques. Le pourcentage des surfaces cultivables est faible pour 45.8% des cuvettes et fort à très fort pour seulement 3.9 %. Celui des surfaces boisées est très fort sur 61.6 % des cuvettes soit 51.4 % en superficie. Les cuvettes possédant un sol nu à natron et/ou une nappe d’eau affleurante représentent 17.6 % des cuvettes. Quant aux indicateurs de risque de dégradation, ils montrent que 3.3 % et 0.5 % des cuvettes ont respectivement une menace d’ensablement fort et très fort à moyen terme. Alors qu’à terme immédiat, c’est respectivement 3% et 0.8 % des cuvettes dont la menace d’ensablement est fort et très fort. Concernant l’évolution récente de ces milieux, les superficies des cuvettes oasiennes ont régressé de 46783 ha en 1984, à 40831 ha en 1996 et 34553 ha en 2013. Inversement, leur nombre a augmenté de 1984 (8911) à 2013 (10717). Ceci s’explique certes pour partie par les résolutions différentes des images satellitaires utilisées, mais surtout par la fragmentation de certaines cuvettes du fait de leur dégradation et la création de nouvelles cuvettes par l’érosion éolienne. Cette dynamique est accentuée par celle de l’occupation humaine des paysages. Les abords des cuvettes et des vallées sèches constitués souvent d’édifices dunaires sont de plus en plus occupés par les cultures pluviales qui les exposent davantage à l’érosion. En 1984, les édifices dunaires et vallées sèches à culture pluviale représentent 295697 ha alors, qu’en 1996 et 2013, elles occupent respectivement 368153 ha et 423876 ha. Les systèmes d’information à référence spatiale esquissés permettent d’observer et de suivre la totalité des cuvettes oasiennes. Ce système, conçu en utilisant le langage UML, a permis non seulement d’établir des relations entre les indicateurs de potentiel valorisable et de dégradation mais aussi des informations supplémentaires récoltées sur le terrain (village, marché, zone de fixation biologique et mécanique des dunes). Ils offrent un accès aisé à ces indicateurs grâce à une interface informatique. À travers des requêtes sur cette base de données, les cuvettes à menace très forte nécessitant une intervention urgente pour leur conservation ont été mises en évidence ainsi que les variables explicatives du niveau d’exploitation des cuvettes. [less ▲]

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See detailUtilisation du D-galactose et du D-tagatose chez Bacillus sp.: Etude des protéines GalM et PBP4a de B. subtilis et B. amyloliquefaciens et Etude de la voie catabolique PTS-dépendante du D-tagatose chez B. licheniformis.
Van der Heiden, Edwige ULg

Doctoral thesis (2017)

Cette thèse s’intéresse à la métabolisation de deux sources de carbones, le galactose et le tagatose, dans des souches du genre Bacillus. La première partie de la thèse vise à montrer le rôle de GalM, une ... [more ▼]

Cette thèse s’intéresse à la métabolisation de deux sources de carbones, le galactose et le tagatose, dans des souches du genre Bacillus. La première partie de la thèse vise à montrer le rôle de GalM, une galactose mutarotase, dans la métabolisation du galactose chez B. subtilis ATCC 21332 et B. amyloliquefaciens FZB42. Le gène galM est organisé en opéron avec le gène dacC qui code pour un PBP de faible poids moléculaire, le PBP4a. Des mutants ponctuels et de délétion ont été générés dans le but d’étudier l’implication des produits de cet opéron dans la formation de biofilms in vitro, dans le remodelage de la paroi bactérienne et dans la colonisation de racines de plantes (plants de tomate et Arabidopsis thaliana). Une différence significative de colonisation a été mise en évidence entre la souche sauvage de B. amyloliquefaciens FZB42 et son double mutant uniquement sur les racines de plants de tomate. Toutefois, il pourrait s’agir d’un effet indirect lié à la méthode. Après analyse des muropeptides composant le peptidoglycane isolé en phase végétative, aucun rôle in vivo n’a pu être attribué au PBP4a. Cependant, l’attachement de cette protéine à la membrane de la bactérie a pu être mis en évidence. Une couronne de charges positives en surface du domaine II du PBP4a est responsable de cette localisation. La seconde partie de la thèse présente la voie de métabolisation du tagatose découverte chez B. licheniformis. Cette source de carbone est transportée et phosphorylée par les composants du système phosphotransférase (PTS) : EIIAT AG (TagM) et EIIBCT AG (TagL). La fonctionnalité du cluster de gènes identifié dans le génome de la bactérie a été démontrée par des expériences de supplémentation dans deux souches initialement incapables de métaboliser cette source de carbone : B. subtilis et E. coli. Le tagatose est phosphorylé durant son transport au niveau du carbone C1. Le tagatose-1-phosphate, présent principalement sous la forme -pyranose, est ensuite phosphorylé par l’enzyme TagK, une tagatose-1-phosphate kinase. Les paramètres cinétiques de l’enzyme ont été déterminés et la spécificité en faveur du tagatose-1-phosphate a été démontrée. Le tagatose 1,6-bisphosphate généré par TagK est hydrolysé en DHAP et G3P par GatY, une tagatose 1,6-bisphosphate aldolase de classe II. [less ▲]

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See detailCattle grazing dynamics under contrasted pasture characteristics at temporal and spatial scales
Andriamandroso, Andriamasinoro ULg

Doctoral thesis (2017)

Grassland constitutes an important and a low-cost food source for grazing livestock. Optimal management should consider both forage resource productivity and animal needs. For cattle, grazing is a normal ... [more ▼]

Grassland constitutes an important and a low-cost food source for grazing livestock. Optimal management should consider both forage resource productivity and animal needs. For cattle, grazing is a normal behavior displayed in an attempt to eat the amount of forage to fulfill their nutritive requirements for maintenance and production. It is the most time-consumed activity of cows reared in pasture-based systems. With the increase of herd size, on one hand, farmers have been constrained to integrate innovative tools and techniques, such as milking robot, to improve the production system in particular to reduce the labor cost. On the other hand, such change might reduce time allocated for grazing on pasture. However pasture-based systems constitute a real pillar for sustainability as they are socially acceptable and environmentally profitable as they play an important role on ecosystem services and biodiversity provision. Studying grazing processes at individual level, which finally is the key point of animal-plant interactions, is a valuable research domain to enhance the knowledge about this mechanism and to feed decision support tools. This thesis aimed to link the changes in pasture characteristics to the grazing behavior of cattle in order to better understand the grazing strategy under different pasture characteristics and forage allowances. To allow an individual monitoring, sensor technology has integrated within farms and livestock researches to monitor many physical variables, inducing the emergence of precision livestock farming approach. Different types of sensors were designed, and already commercialized for some, primarily for physiological status detections such as heat, parturition or diseases. Grazing behaviors could be monitored using pressure, electromyography, acoustic or accelerometric sensors by classifying posture and movements of the animal into unitary behaviors (grazing, ruminating, resting, walking, etc.) and finer behavior such as chews and bites through jaw movements’ detection. When compared to real observation, detection accuracies of these behaviors were variable according to the type of sensor, its position on the animal during data acquisition on pasture, the data recording frequency, the time-window and the method dedicated to the post-recording data analysis. State-of-the-art analysis demonstrated a great performance of accelerometers for unitary behaviors and bites detection. An inertial measurement unit, integrating accelerometer, gyroscope and location sensors, was used for recording cattle movements during grazing at high sampling rate (100Hz). It allows a correct detection of grass intake and rumination behaviors with an average accuracy of 91% using 1-second time-window when calibrating and validating the detection algorithm. Deeper analysis of accelerometric signal allowed us to detect bites and chews performed during grazing and ruminating. Effects of pasture heights on grazing bites characteristics were differentiated by a higher frequency when pasture is at a lower height. Finally when combined to geographical information, a similar pattern was observed for cattle grazing on the same spot confirming their herd movement during grazing in terms of bites location. Differences were visible under different pasture heights but not significant. Such bites location, combined with continuous monitoring of cattle behaviors, through use of sensors, should be furtherly linked with more pasture characteristics, if possible with the same accuracy, and monitored on longer period in order to obtain a complete coverage of cattle grazing strategy and the effect of contrasted environment in order to purpose valuable tool for a better grazing management. [less ▲]

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See detailImprovement of genetic evaluation systems for maternally influenced traits and multi-breed livestock populations
Vanderick, Sylvie ULg

Doctoral thesis (2017)

Animal breeding programs are designed to genetically improve livestock populations over many generations to enhance farm sustainability and competitiveness. Genetic improvement is achieved by selecting ... [more ▼]

Animal breeding programs are designed to genetically improve livestock populations over many generations to enhance farm sustainability and competitiveness. Genetic improvement is achieved by selecting genetically superior animals, based on estimated breeding values, to be the parents of the next generation. These estimated breeding values are calculated by solving mixed model equations characterizing appropriate statistical genetic evaluation models. To guarantee effective genetic selection, genetic evaluation models must be tailored to the specific characteristics of the traits and population under evaluation. This PhD thesis focused on the development of genetic evaluation models suitable for categorical maternally influenced traits and for multi-breed populations. Appropriate genetic animal models were developed and assessed: (1) for two categorical maternally influenced traits based on calving ease scores from Walloon Holstein dairy cattle and on lamb survival data from a New Zealand sheep population; (2) for two multi-breed populations based on milk yield records of New Zealand purebred and crossbred dairy cattle, and on purebred and crossbred calving ease scores from Walloon Belgian Blue and Holstein cattle. Results showed that (1) fitting maternal effects was required to avoid biasing the estimated breeding values, and there was no clear advantage in using non-linear mixed models instead of linear mixed models for the genetic analysis of the two categorical maternal traits studied; (2) breed-dependent breeding values could be estimated using the proposed multi-breed models, and that combining purebred and crossbred data had a positive influence on the accuracy of the breeding values of purebred animals. Finally, part of the research presented in this thesis contributed to the development of the genetic evaluation systems currently used in Walloon Region of Belgium and in New Zealand. [less ▲]

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See detailGénération d’une librairie de mutants de Bacillus licheniformis 749/I par l’insertion aléatoire d’un transposon pour identifier les gènes impliqués dans l’induction de la β-lactamase BlaP
Lebrun, Sarah ULg

Doctoral thesis (2017)

La production de la b-lactamase BlaP chez Bacillus licheniformis 749/I est induite par la présence d’un antibiotique à noyau b-lactame (b-lactamine) dans le milieu extérieur. Le récepteur membranaire ... [more ▼]

La production de la b-lactamase BlaP chez Bacillus licheniformis 749/I est induite par la présence d’un antibiotique à noyau b-lactame (b-lactamine) dans le milieu extérieur. Le récepteur membranaire BlaR1 détecte la présence de la b-lactamine et transmet un signal vers le cytoplasme. La protéine BlaR1 est composée de deux domaines : le domaine C-terminal (BlaR-CTD) exposé à l’extérieur de la cellule qui détecte la présence de l’antibiotique et le domaine N-terminal membranaire (BlaR-NTD) agissant comme un transducteur et un amplificateur du signal perçu par le domaine senseur. En présence de b-lactamine, l’acylation de BlaR-CTD par l’antibiotique entraîne un changement conformationnel des segments transmembranaires menant à l’activation de la boucle L3 de BlaR-NTD. Le répresseur BlaI, qui réprime la transcription du gène blaP, est inactivé par liaison d’un coactivateur, le dipeptide D-Glu--mA2pm issu de la dégradation du peptidoglycane à l’extérieur de la cellule. La voie d’entrée de ce dipeptide n’est pas connue ainsi que le locus blaR2 impliqué dans l’induction de la b-lactamase. L’objectif principal de ce travail est l’identification du locus blaR2 par la construction d’une banque aléatoire de mutants par transposition. La première étape du travail était la mise au point de la transformation de Bacillus licheniformis 749/I par un plasmide possédant une origine thermosensible et porteur d’un transposon modifié. Un clone recombinant a été obtenu par la méthode de transformation de protoplastes avec de l’ADN sous forme concatémère. Une banque d’environ 11.300 clones a été générée et validée. Une méthode de criblage sur boite via un test iodométrique a mis en évidence cinq mutants sur l’entièreté de la banque présentant une différence d’induction par rapport à la souche sauvage. L’identification des insertions chromosomique du transposon a été réalisée par PCR inverse et par AP-PCR et a permis d’identifier trois clones insérés dans le gène blaR1 et deux dans le gène blaP. Ces mutants sont tous différents entre eux. Une seconde stratégie a été envisagée en vue d’identifier le locus blaR2 par complémentation du mutant chimique blaR2- par l’ADN génomique isssus des mutants de la souche sauvage générés à partir du transposon. La souche blaR2- a été transformée cependant, aucun événement de recombinaison n’a pu être observé. Sur base de ces expériences, la question de l’identification du locus blaR2 reste en suspens. Néanmoins, au cours de l’isolement des clones contenant le transposon, nous avons mis en évidence des clones présentant des colonies possédant un phénotype « luisant » par rapport à l’aspect mat de la souche sauvage. Un gène codant pour une estérase (Bl-EstA) a été ainsi identifié et le produit du gène étudié. Bl-EstA appartient à la famille des lipases « hormone-sensitive lipase like_1 » (Famille IV de la classification d’Arpigny et Jaeger (1999)) et possède toutes les caractéristiques des a/b hydrolases. Bl-EstA est sous la forme dimérique en solution et peut adopter différents comportements cinétiques en fonction des substrats qu’elle hydrolyse : une cinétique Michaélienne classique, allostérique ainsi qu’une inhibition par le substrat. Ces comportements impliquent, au moins, la présence d’un site régulateur. Enfin, l’inactivation de Bl-EstA par les alcools n’est pas favorable à son utilisation pour des réactions de transestérifications et dès lors pour des applications industrielles. [less ▲]

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See detailDevelopment of Mass Spectrometry based Analytical Tools for Animal Venoms Characterization
Echterbille, Julien ULg

Doctoral thesis (2017)

Animal venoms and toxins are now recognized as major sources of bioactive molecules that may be tomorrow’s new drug leads. Their complexity and their potential as drug sources have been demonstrated by ... [more ▼]

Animal venoms and toxins are now recognized as major sources of bioactive molecules that may be tomorrow’s new drug leads. Their complexity and their potential as drug sources have been demonstrated by application of modern analytical technologies, which have revealed venoms to be vast peptide combinatorial libraries. Structural as well as pharmacological diversity is immense, and mass spectrometry is now one of the major investigative tools for the structural investigation of venom components. The present work is dedicated to the development of new mass spectrometry-based methodologies for the study of animal venoms. The first methodology depicts an original approach to sequence snake toxins in a higher throughput way after an orthogonal separation of the crude venom. The second analytical development is devoted to decipher disulfide connectivity in cone snails’ toxins through a combination of partial reduction/oxidation followed by ion mobility separation of the semi-reduced/oxidized species and CID fragmentation. The last part of this work is focused on the capture of ligands of nAChRs in complex mixtures of peptides, especially in cone snail venoms. A new ligand has been discovered and fully characterized. [less ▲]

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See detailGovernance of plant health and management of crop diversity - the case of common bean health management among members of the association Croqueurs de Carottes
Klaedtke, Stephanie ULg

Doctoral thesis (2017)

All over the globe, networks of seed growers are cultivating crop diversity in fields and gardens. Their contribution to the maintenance of this diversity has been studied, but research has widely left ... [more ▼]

All over the globe, networks of seed growers are cultivating crop diversity in fields and gardens. Their contribution to the maintenance of this diversity has been studied, but research has widely left aside their management of plant health. The governance of bean health practiced by an association of artisanal seed companies, Croqueurs de Carottes, is approached as a case study in the objective of specifying how management of crop diversity and governance of plant health are articulated. Their concern for the governance of bean health is elucidated from an agroecological perspective, taking an interdisciplinary and transformative approach. Actor-network theory constitutes the backbone of the thesis, situated between agronomy and sociology and drawing upon a threefold research device: on-farm experiments, semi-directive interviews and participant observation. The Croqueurs' approach to bean health is described as in situ approach, in which plant populations are considered healthy if they are able to live with potential plant pathogens and adapt to their growing environments. Relying on ecological interactions, competences of plant health management are distributed throughout the production system. Both for plant health and crop diversity management, a seed lot is determined by a complex system of interactions. A clear boundary distinguishing plant populations from their growing environment cannot be drawn. This implies (i) that plant health must be judged upon in situ in the plants' growing environment and (ii) that the governance of plant health must be considered at the collective scale. [less ▲]

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See detailInactivation of DNA damage repair provides additional efficacy to the treatment of thyroid cancer
Neelature Sriramareddy, Sathyanarayana ULg

Doctoral thesis (2017)

Incidence of thyroid cancer has increased steadily over the last several decades. This type of neoplasm accounts for the majority of deaths due to endocrine cancers. The most frequent form, well ... [more ▼]

Incidence of thyroid cancer has increased steadily over the last several decades. This type of neoplasm accounts for the majority of deaths due to endocrine cancers. The most frequent form, well-differentiated thyroid cancer, is characterized by disease persistence, recurrence and a lack of response to radioiodine-131. With survival rates of 9 weeks to 5 months, anaplastic thyroid cancer has very poor prognosis. To provide additional efficacy to the treatment of thyroid cancer, we investigated the mechanisms of DNA damage and repair. We found that thyroid cancer cells undergo mitosis in presence of unrepaired DNA damage. To proliferate and survive, these cells repair DNA lesions very efficiently using homologous recombination (HR) and non-homologous end joining (NHEJ). Pharmacological inhibition of these pathways significantly increases apoptosis of thyroid cancer cells. This thesis thus demonstrates that targeting DNA damage repair pathways might have therapeutic value in relapsing and advanced thyroid cancers. [less ▲]

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See detailMonitoring Lions (Panthera leo) using Digital 3D Models of their Tracks
Marchal, Antoine ULg

Doctoral thesis (2017)

As the Earth may be entering a new human-influenced geological time, the Anthropocene, the pressure on biodiversity due to increasing human populations and activities is unprecedented. Monitoring animal ... [more ▼]

As the Earth may be entering a new human-influenced geological time, the Anthropocene, the pressure on biodiversity due to increasing human populations and activities is unprecedented. Monitoring animal populations is essential to gain demographic data and assess their viability. Because of the difficulties linked to invasive methods that involve direct observation or handling, many researchers have explored alternative approaches such as using tracks. Tracks are the material by-product of the interaction between terrestrial animals and their physical environment due to gravity. The interpretation of tracks exists since the dawn of mankind and is a crucial factor for human evolution. As an integral part of hunting, the art of tracking involves cognitive thinking that may well be part of the origin of science. However, monitoring species through their tracks is controversial due to several reasons: unreliable recording techniques limited to two-dimensions, manipulator bias, substrate variation, misidentification of the foot from which each track originates, and subjective identification of the age, sex and/or individual. The aim of this thesis was to evaluate the possibility of monitoring lions Panthera leo through digital three-dimensional (3D) models of their tracks. The first step was to assess close-range digital photogrammetry as a low-cost, rapid, practical and reliable field technique for the digital 3D modelling of lion paws, tracks and trails. A trail, that is a continuous sequence of tracks made by the same individual, reflects the morphology and kinematics of that individual. The use of traditional morphometrics enabled the extraction of variables such as distances, angles and areas from the digital 3D trails originating from individuals of known age, sex and/or identity. When comparing adult lions walking at the same gait (i.e. same kinematics), the trail variables provided sufficient information to identify the sex and individual. The digital solution permitted the extraction of more variables than the usual pace, stride and straddle. These additional variables enabled a better discrimination between the sexes and individuals. As for the paw and track morphology, traditional morphometrics conveys limited information about the geometric structure, and fails to quantify the shape variations along curves and surfaces. To overcome these drawbacks, geometric morphometrics allowed the extraction of the form (i.e. size and shape) by means of superimposed fixed landmarks, and curve- and surface-slider semi-landmarks. Using fixed landmarks, the paws and tracks presented enough shape variation to identify their position along the anteroposterior (front or hind) and mediolateral (right or left) axes. We used fixed landmarks, with and without curve- and surface-sliders, on paws and tracks from lions of known age, sex and/or identity. The identification of the age and sex from the paws, and the age, sex and individual from the tracks achieved higher accuracies when using size and shape variables together rather than independently. The information from curves and surfaces offered an advantage for the identification from the tracks but not from the paws. Due to the variation in anatomy, paw morphology and individuality in walking, tracks and trails contain information about the individual lion that created them. Recent advances in digital close-range photogrammetry and geometric morphometrics allow the recording and extraction of that information, which can then provide data to help monitor lion populations using a non-invasive approach. [less ▲]

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See detailMusique et plaisanterie. Ethnographie de trois groupes sociaux (coolooji, ñeeñɓe et mbiruuji) à Djéwol (Mauritanie)
Sow, Aboubakry ULg

Doctoral thesis (2017)

The village of Djéwol (Mauritania) is located on the right bank of the Sénégal river and its' population is estimated to approximately 9000 inhabitants that are split to two communities, the Haalpulaar ... [more ▼]

The village of Djéwol (Mauritania) is located on the right bank of the Sénégal river and its' population is estimated to approximately 9000 inhabitants that are split to two communities, the Haalpulaar and the Soninké who are organinized into hierarchies. Straddling on both communities are the ñeeñɓe (social mediators) and the riimayɓe (servants), who are the main producers and actors of music. Although sometimes they declare themselves to be Haalpulaar, other times, they call themselves Soninké, mainly because of bilingualism and versatility of their music. For this reason, the ñeeñɓe and riimayɓe are conveyed to all manifestations and festivities that punctuate the life of the village. On such occasions, other genres of music are also played by coolooji (social protesters) and the mbiruuji (fighters), both of these being marginal subclasses who are constantly in conflict with the ñeeñɓe. Based on my position of researcher/musian/haalpulaar/dimo (noble) originating from this village and on my personal journey, while using a reflexive method, I will question the rôle and the place in the society of the three actors previously mentioned : The coolooji, the ñeeñɓe and the mbiruuji. Starting with an ethnological description and an anthropological analysis of the different operating modes of yano (pleasantry procedure) – which allow the denɗiraagal (similar to pleasantry) to be set into motion or not – in their articulation of music, it will be a matter of asking ourselves in which way the the coolooji, the ñeeñɓe and the mbiruuji define themselves and contribute to defining others through yano and music. Thus, the first part of this thesis suggests, beyond the presentation of the historical and social context of the community and Djéwol village, adopting a synoptic perspective on the Haalpulaar and Soninké music of the region near the Sénégal river. The second part, however, will focus on the origin of the different types of relations in jiidugal (kin) and of denɗiraagal (related of pleasantry) which proceed by using the yano, as well as the musical art associated with the later. Finally, the last part will be dedicated to analyzing the interactions, conflicting or not, as well as the absence of interactions between the coolooji, the ñeeñɓe and the mbiruuji while highlighting the similarities and the differences between these three significant figures. In conclusion, the situation will be analyzed in the light of the contemporary reconfigurations and of the evolution of the bounds tied between the denɗiraagal and the surrounding social networks. Le village de Djéwol (Mauritanie) se situe sur la rive droite du fleuve Sénégal et compte aujourd’hui 9000 habitants se répartissant en deux communautés, haalpulaar et soninké, fortement hiérarchisées en leur sein. À cheval sur les deux communautés, se trouvent les ñeeñɓe (médiateurs sociaux) et les riimayɓe (serviteurs) qui sont les principaux producteurs et acteurs de musique. Ceux-ci se déclarent tantôt haalpulaar tantôt soninké, notamment en raison de leur bilinguisme et de la polyvalence de leurs musiques. À ce titre, les ñeeñɓe et les riimayɓe sont conviés à toutes les manifestations et festivités qui rythment la vie du village. En ces occasions, d’autres genres de musiques sont également pratiqués par les coolooji (contestataires sociaux) et les mbiruuji (lutteurs), deux « sous-groupes marginaux » qui sont constamment en conflit avec les ñeeñɓe. En m’appuyant, de manière réflexive, sur ma position de chercheur/musicien/haalpulaar/dimo (noble) originaire du village et sur mon parcours, j’interrogerai le rôle et la place dans la société de trois des acteurs mentionnés : les coolooji, les ñeeñɓe et les mbiruuji. À partir de la description ethnographique et de l’analyse anthropologique des divers modes opératoires du yano (procédé de plaisanterie) – qui permettent d’activer ou de désactiver le denɗiraagal, parenté à plaisanterie – dans leur articulation avec la musique, il s’agira de se demander de quelle manière les coolooji, les ñeeñɓe et les mbiruuji se définissent et contribuent à définir autrui à travers le yano et la musique. Ainsi, la première partie de cette thèse proposera, au-delà de la présentation du contexte historique et social de la commune et du village de Djéwol, un regard synoptique sur les musiques haalpulaar et soninké de la région du fleuve Sénégal. La deuxième partie s’intéressera quant à elle à l’origine des différents types de parenté jiidugal (parenté) et de denɗiraagal (parenté à plaisanterie) procédant par le yano, ainsi qu’à l’art musical associé à ce dernier. Enfin, la dernière partie, consacrée à l’analyse des interactions, conflictuelles ou non, et de l’absence d’interactions entre les coolooji, les ñeeñɓe, et les mbiruuji, mettra en évidence les similitudes et les différences entre ces trois figures. La situation sera finalement analysée à la lumière des reconfigurations contemporaines et de l’évolution des liens de denɗiraagal sur les réseaux sociaux. [less ▲]

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See detailAssessing microbial diversity changes associated with different tillage and crop residue managements: study case in a loamy soil
Degrune, Florine ULg

Doctoral thesis (2017)

The major challenge of modern agriculture is to produce enough food for the growing population, and at the same time, minimize environmental harm. To meet this challenge, Agroecology aims to replace non ... [more ▼]

The major challenge of modern agriculture is to produce enough food for the growing population, and at the same time, minimize environmental harm. To meet this challenge, Agroecology aims to replace non-renewable external inputs with ecological processes to diversify the ecosystem services and attenuate the dis-services of agriculture. In this light, the ability to manage the soil microbiota, that has great effects on soil quality, is receiving attention. Plowing, the most widely used tillage practice in intensive agriculture has proven its efficiency in maximizing crop productivity, but its long term detrimental effects on soil quality, such as soil erosion and organic matter loss, have called for alternative tillage practices. However, the success of the implementation of these practices in Europe is still debated. In the upper part of Wallonia (Belgium), the soil is highly fertile and 80% of land is occupied mostly by intensive cropping systems. To date in Walloon cropping systems, few studies have explored the soil microbiota in association with different soil managements. Here, we used a meta-barcoding approach to explore differences in soil microbial community structure under two contrasting tillage regimes, conventional (CT) and reduced tillage (RT), either with or without crop residue retention. The effects of these soil treatments were explored at different depths and during the growing season of two crops. Our work demonstrated clear differences in microbial diversity between tillage regimes, but no clear differences between residue management practices. The observed differences appeared to be associated with differences in physical (e.g. structure and moisture) and chemical (nutrients) soil properties. Notably, the nutrient concentrations and moisture were higher under CT than under RT. Overall, soil under CT had higher or similar microbial diversity than under RT. Analysis of β-diversity revealed differences in the taxonomic structure of microbial communities. Certain microbial groups were more abundant under CT than under RT and vice versa. For example, mycorrhizal fungi, economically and ecologically important in agroecosystems, were more abundant under RT. Finally, the magnitude of tillage effects on the microbial diversity varied strongly with the sampling depth, whereas it varied moderately with the growing season. This work highlighted CT was not necessarily unfavourable in maintaining microbial diversity when compared to RT. However, the study raises new questions regarding the impacts of microbial diversity changes on soil functioning. We encourage researchers to undertake further investigations into the functional role of microbiota in order to improve our understanding of agroecosystem functioning and its sustainability. [less ▲]

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See detailOffline Policy-search in Bayesian Reinforcement Learning
Castronovo, Michaël ULg

Doctoral thesis (2017)

This thesis presents research contributions in the study field of Bayesian Reinforcement Learning — a subfield of Reinforcement Learning where, even though the dynamics of the system are un- known, the ... [more ▼]

This thesis presents research contributions in the study field of Bayesian Reinforcement Learning — a subfield of Reinforcement Learning where, even though the dynamics of the system are un- known, the existence of some prior knowledge is assumed in the form of a distribution over Markov decision processes. In this thesis, two algorithms are presented: OPPS (Offline Prior- based Policy Search) and ANN-BRL (Artificial Neural Networks for Bayesian Reinforcement Learning), whose philosophy consists to analyse and exploit the knowledge available beforehand prior to interacting with the system(s), and which differ by the nature of the model they make use of. The former makes use of formula-based agents introduced by Maes et al. in (Maes, Wehenkel, and Ernst, 2012), while the latter relies on Artificial Neural Networks built via SAMME (Stagewise Additive Modelling using a Multi-class Exponential loss function) — an AdaBoost algorithm developed by Zhu et al. in (Zhu et al., 2009). Moreover, we also describe a comprehensive benchmark which has been created to compare Bayesian Reinforcement Learning algo- rithms. In real life applications, the choice of the best agent to fulfil a given task depends not only on their performances, but also on the computation times required to deploy them. This benchmark has been designed to identify the best algorithms by taking both criteria into account, and resulted in the development of an open-source library: BBRL (Benchmarking tools for Bayesian Reinforcement Learning) (https://github.com/mcastron/BBRL/wiki). [less ▲]

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See detailLa participation et l’Appropriation à l’épreuve des pouvoirs dans les projets ruraux à Cobly (Atacora-Bénin). Une approche socio-historique
Gbénahou, Hervé Bonaventure Mêtonmassé ULg

Doctoral thesis (2017)

Generally, projects are analyzed when they still ongoing or just at the end. Similarly, the analysis of power issues is generally being focused, in projects cases, on the problems of coordination and ... [more ▼]

Generally, projects are analyzed when they still ongoing or just at the end. Similarly, the analysis of power issues is generally being focused, in projects cases, on the problems of coordination and conflicting relations and their foundations. This doctoral thesis goes a little at the antipodes of these studies. First, it questions closed projects. Afterwards, even if it integrates the conflicting vision of power because of the closed nature of the projects, it additionally uses an alternative approach of power based on "powers of action". Concretely, it takes interest in the projects that the Dutch and Belgian agencies have carried out in the municipality of Cobly in the North-West of Benin. To do so, it closely looks at the participation systems and the appropriation mechanisms designed and implemented in the constituted arenas. It also questions the intervention frameworks and the projects publicizing process. Plus, it seeks to know how the beneficiaries use, the supports that directly reach them or they "hijack", for their empowerment. In doing so, it has taken the option to refocus reflection on the causes of problems and the actors really concerned. The methodological approach used for this research is a mix of sociohistory and biographical approach. It clearly appears, from the results and analyzes made, that the forms of formalized partnerships, the use of participation and the otherness of introduced clustering models have led to "negative" organizational governance, approximate results and differential appropriation's. The various mediated powers and the feelings they have left at actors’ level, have played a great role in these objectified situations. Socio-historical literature requires that the stakes associated with the interactions made possible by the projects, the participation modalities and the fundamentals of POs governance been co-constructed. Similarly, it asks that the learning systems and the capacities of the beneficiaries be constantly put into perspective through oriented decision-making processes. This literature also reveals that the scales generally used to evaluate the impact of projects have always rendered elusive, not only their real effects on the "Powers to act" of the beneficiaries, but also and above all, the effects of the powers they reinforce, on the trajectories of life of beneficiaries. [less ▲]

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See detailStratégies linguistiques et identitaires en Belgique : Approche interdisciplinaire des catégorisations, discours et représentations des usages en interaction de francophones vivant en Flandre et de néerlandophones vivant en Wallonie
Dassargues, Alix ULg

Doctoral thesis (2017)

Depuis le XIXème siècle qui a vu s’épanouir le concept de « peuple » sur des critères ethniques et linguistiques, les langues et les identités collectives sont souvent associées. Ce principe s’actualise ... [more ▼]

Depuis le XIXème siècle qui a vu s’épanouir le concept de « peuple » sur des critères ethniques et linguistiques, les langues et les identités collectives sont souvent associées. Ce principe s’actualise notamment dans les identités régionales de Belgique. À l’heure où celles-ci prennent de plus en plus de poids dans une Belgique fédérale en voie de délitement, il convient de s’intéresser aux individus en situation d’allophonie au sein de ces régions unilingues. Ces individus, de plus en plus isolés par la définition dominante des identités subnationales belges, doivent presque nécessairement mettre en place des stratégies linguistiques et identitaires dans leurs interactions sociales. Afin d’étudier ces stratégies linguistiques et identitaires, notre thèse s’articule autour de deux questions de recherche contiguës. Tout d’abord, il s’agit d’expliciter comment des francophones vivant en Flandre et des néerlandophones vivant en Wallonie conceptualisent les/la langue(s) et les/ l’identité(s). Après avoir défini les modalités de conception et les différents contenus de ces concepts, l’analyse se concentre sur les stratégies linguistiques et identitaires que ces informateurs disent mettre en place en situation d’interaction. En convoquant la sociolinguistique, la linguistique cognitive, la psychologie sociale et la sociologie de l’identité, cette thèse se veut interdisciplinaire afin de mettre en lumière au mieux les liens entre langue(s) et identité(s) au sein du processus d’identification de l’individu. [less ▲]

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See detailTrees and shrubs influence the behaviour of grazing cattle and rumen fermentation
Vandermeulen, Sophie ULg

Doctoral thesis (2017)

Hedgerows and woody strips have been used to enclose fields but declined due to the loss of a direct economic value, abandonment of traditional management techniques and agricultural intensification ... [more ▼]

Hedgerows and woody strips have been used to enclose fields but declined due to the loss of a direct economic value, abandonment of traditional management techniques and agricultural intensification. Nowadays, shrubs and trees on pastures are promoted again through environment-friendly policies and the interest in using them as forage for ruminant increases in both temperate and tropical ecosystems. Woody plants on farmland could yield a wide range of ecosystem services and provide benefits for farmers and their animals such as forage supply to livestock, animal protection against severe weather and reduced parasitic infestation. Moreover, shifts in digestive physiology can be observed that will in turn affect the welfare and the performances of the animal and the production system as a whole. Therefore, in order to contribute to the development of sustainable systems using shrubs and trees as a feed component in its full right, the aim of this work was to investigate the influence of trees and shrubs on the behaviour of grazing cattle and their selectivity towards woody species, and to determine the changes induced by temperate and tropical shrub and tree species on rumen fermentation. Firstly, the behaviour of grazing dairy heifers was recorded during the whole grazing season as well as their selectivity towards temperate woody species in a hedge. It was concluded that having access to a hedge influenced the behaviour of grazing cattle, as the animals ingested woody plants in each season but mostly when the available pasture biomass was lower. The most selected species were Carpinus betulus, Corylus avellana, Cornus sanguinea and Crataegus monogyna. Secondly, the chemical composition, in vitro rumen fermentation profile and protein precipitation capacity (PPC) of the temperate shrub and tree species were measured. The analyses showed that Fraxinus excelsior presented the most interesting profile in terms of chemical composition and in vitro fermentation production. Among the preferred species, C. monogyna and C. avellana produced lower CH4 and the latest had the highest PPC. Thirdly, three newly-developed cultivars of the tropical Desmanthus genus were studied for their effects on in vitro rumen fermentation including potential to reduce CH4. Desmanthus leptophyllus and D. bicornutus had the highest anti-methanogenic potential, and D. bicornutus was more digestible. In conclusion, both temperate and tropical shrub and tree fodder are promising to supplement cattle with good quality forage. Cattle can browse woody species voluntarily, however, further investigations are needed to provide relevant practical recommendations on how to manage this resource adequately in order to balance intake by the animal and regrowth capacity of the plant. The impact of management strategies relying on cutting and preservation should also be assessed. Moreover, benefits of shrubs and trees on pastures beyond the animal feeding and nutrition are still poorly characterized while, in an agroecological perspective, they can contribute to a significant improvement of the sustainability of ruminant production systems. [less ▲]

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See detailExploiting random projections and sparsity with random forests and gradient boosting methods - Application to multi-label and multi-output learning, random forest model compression and leveraging input sparsity
Joly, Arnaud ULg

Doctoral thesis (2017)

Within machine learning, the supervised learning field aims at modeling the input-output relationship of a system, from past observations of its behavior. Decision trees characterize the input-output ... [more ▼]

Within machine learning, the supervised learning field aims at modeling the input-output relationship of a system, from past observations of its behavior. Decision trees characterize the input-output relationship through a series of nested ``if-then-else'' questions, the testing nodes, leading to a set of predictions, the leaf nodes. Several of such trees are often combined together for state-of-the-art performance: random forest ensembles average the predictions of randomized decision trees trained independently in parallel, while tree boosting ensembles train decision trees sequentially to refine the predictions made by the previous ones. The emergence of new applications requires scalable supervised learning algorithms in terms of computational power and memory space with respect to the number of inputs, outputs, and observations without sacrificing accuracy. In this thesis, we identify three main areas where decision tree methods could be improved for which we provide and evaluate original algorithmic solutions: (i) learning over high dimensional output spaces, (ii) learning with large sample datasets and stringent memory constraints at prediction time and (iii) learning over high dimensional sparse input spaces. A first approach to solve learning tasks with a high dimensional output space, called binary relevance or single target, is to train one decision tree ensemble per output. However, it completely neglects the potential correlations existing between the outputs. An alternative approach called multi-output decision trees fits a single decision tree ensemble targeting simultaneously all the outputs, assuming that all outputs are correlated. Nevertheless, both approaches have (i) exactly the same computational complexity and (ii) target extreme output correlation structures. In our first contribution, we show how to combine random projection of the output space, a dimensionality reduction method, with the random forest algorithm decreasing the learning time complexity. The accuracy is preserved, and may even be improved by reaching a different bias-variance tradeoff. In our second contribution, we first formally adapt the gradient boosting ensemble method to multi-output supervised learning tasks such as multi-output regression and multi-label classification. We then propose to combine single random projections of the output space with gradient boosting on such tasks to adapt automatically to the output correlation structure. The random forest algorithm often generates large ensembles of complex models thanks to the availability of a large number of observations. However, the space complexity of such models, proportional to their total number of nodes, is often prohibitive, and therefore these modes are not well suited under stringent memory constraints at prediction time. In our third contribution, we propose to compress these ensembles by solving a L1-based regularization problem over the set of indicator functions defined by all their nodes. Some supervised learning tasks have a high dimensional but sparse input space, where each observation has only a few of the input variables that have non zero values. Standard decision tree implementations are not well adapted to treat sparse input spaces, unlike other supervised learning techniques such as support vector machines or linear models. In our fourth contribution, we show how to exploit algorithmically the input space sparsity within decision tree methods. Our implementation yields a significant speed up both on synthetic and real datasets, while leading to exactly the same model. It also reduces the required memory to grow such models by exploiting sparse instead of dense memory storage for the input matrix. [less ▲]

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See detailComment le changement climatique influence-t-il la croissance du hêtre (Fagus sylvatica L.) le long du gradient bioclimatique de la Belgique ? Une approche dendroécologique.
Latte, Nicolas ULg

Doctoral thesis (2017)

Health anomalies (e.g., worsening crown conditions) on beech (Fagus sylvatica L.) observed throughout Europe since the 1990s have raised growing concerns among foresters, particularly about the future ... [more ▼]

Health anomalies (e.g., worsening crown conditions) on beech (Fagus sylvatica L.) observed throughout Europe since the 1990s have raised growing concerns among foresters, particularly about the future behavior of the species in the face of climate change. This PhD research examined the relationship between beech and its environment in the context of global changes using dendroecology, combination of dendrochronology and forest ecology. The radial growth was used to evaluate the effects of global changes, particularly climate change, on beech development and vitality over time along a bioclimatic gradient in Belgium. Various analyses were carried out using dendrochronological tools (pointer years, mean sensitivity, growth-climate correlation, etc.) and modeling approaches (linear and non-linear mixed models, partial least squares regression, etc.) considering several scales: tree, stand and region. Results show that climate predominantly influenced beech growth since the mid-20th century and did so rather uniformly across Belgium. Beech mean sensitivity increased mainly in response to the higher frequency and intensity of summer heat waves and spring droughts. Isolated but pronounced annual growth reductions induced a gradual diminution of mean growth. The increasing influence of climate progressively concealed the effect of local site growing conditions inducing strong between-sites synchronization along the bioclimatic gradient. Increasing mean sensitivity and decreasing mean growth were more pronounced in lowlands than in uplands, and for a given site, older trees are more affected than younger ones. Although mean sensitivity increases and mean growth decreases naturally with age, the climate change effect was much more important than the age effect. Furthermore, within a tree, along the main stem, climate sensitivity slightly decreased from breast height to crown base and strongly increased from crown base to tree top. These results were interpreted based on ecophysiological knowledge of beech. The influences of silviculture, soil compaction and nitrogen deposition (as part of atmospheric pollution) as well as the consequences of the past and future climate change on beech were discussed. Comparisons with other studies in Europe highlighted that beech is affected on a large part of its natural distribution range (except in high altitude and high latitude). Contrary to what one might think, beech is not only affected in the southern limit (Mediterranean). Although growing conditions are more favorable in Belgium, beech has also more to lose. Beech has coped with global change up to now. Although its climate sensitivity increased and its mean growth decreased, diebacks observed these last years in Belgium were scarce and generally scattered. However, considering the upcoming climate change, the phytosanitary risk will undeniable increased. Forest policy should now integrate that risk and prepare managers to anticipate and prevent it. [less ▲]

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See detailContribution à la mise en place d’une plateforme de transgénèse chez la volaille domestique: culture, cryopréservation et ingénierie génétique de cellules germinales primordiales.
Tonus, Céline ULg

Doctoral thesis (2017)

Primordial germ cells (PGCs) are the intermediate of choice for domestic fowl transgenesis and genome editing. These can support large transgenes insertions and, as precursors of the germline, can ... [more ▼]

Primordial germ cells (PGCs) are the intermediate of choice for domestic fowl transgenesis and genome editing. These can support large transgenes insertions and, as precursors of the germline, can transmit a genetic modification to the next generation. Moreover, given the difficulties for cryopreserving avian gametes (spermatozoa and, above all, oocytes), PGCs represent the material of choice for germplasm preservation in these species. Despite the obvious advantages of PGCs use, recently described related technologies appear generally as more difficult to pursue, and as less effective than expected. In this context, we have developed and optimized some of them which appear as essential for carrying complex chicken genome engineering projects. We first focused on improving the effectiveness of culture and cryopreservation of PGCs. By developing a culture method in inserts, ending up with an efficiency close to 40 %, we were able to isolate and long-term cultivate chickens PGCs from 3 commercial breeds and 2 Belgian endangered local breeds. The cells showed all the characteristics of the PGCs in terms of morphology, markers' expression and gonadal migration. We also applied a cryopreservative vitrification method, which showed results superior to those obtained by conventional slow freezing. During the last part of this work, we genetically engineered PGCs to obtain stable transfectants expressing GFP. These transfectants allowed us to examine long-term gonadal colonization and germline transgene transmission. We also tested a Cre recombinase-mediated site-specific cassette exchange method. As a final result, we have developed the methods and know-how mandatory to allow efficient harvesting, expansion, genetic engineering, reimplantation and cryopreservation of chicken PGCs, and we have shown the possibility of germline transmission of a long term cultured and genetically modified PGCs line. [less ▲]

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See detailDevelopment and implementation of a methodology for hybrid fire testing applied to concrete structures with elastic boundary conditions
Sauca, Ana ULg

Doctoral thesis (2017)

Fire tests remain a precious tool to comprehend the behavior of structures under accidental fire conditions. The common practice in fire testing is to isolate the tested element in a furnace in which the ... [more ▼]

Fire tests remain a precious tool to comprehend the behavior of structures under accidental fire conditions. The common practice in fire testing is to isolate the tested element in a furnace in which the mechanical support conditions are maintained constant throughout the test. However, such tests fail to capture the effect of the structure surrounding the element of interest when this effect cannot be realistically modeled by a free or fixed support condition. It has been observed in large-scale tests that the behavior of entire structures under fire is different compared with the behavior observed in traditional tests on isolated elements. This indicates the importance of capturing accurately the boundary conditions between the element and the remainder of the structure when characterizing the behavior of this element in fire. The literature describes a few attempts at performing fire tests under realistic boundary conditions. In the latter, the tests were still performed on isolated elements but the boundary conditions were updated during the test taking into account the characteristics of the remainder structure. This technique, called hybrid testing, represents an appealing solution to test structural elements under realistic boundary conditions. Hybrid testing is a methodology which offers the advantage of testing singular structural elements (or a group of structural elements) named physical substructure PS while at the same time considering the characteristics of the remainder substructure named numerical NS, thus allowing to model realistic boundary conditions. Pioneering work has been done in the seismic field where this technique is now well described, but the implementation of this methodology for structural fire testing raises important challenges due to the specificities of the field. A few hybrid fire tests have been performed in the past on columns and slabs. Their analysis shows that they all use a similar methodology, which is referred to as the first generation method in this work. The objective of the thesis was to develop and implement a hybrid fire testing methodology on a reinforced concrete beam extracted from a moment resisting frame. Initially, it was intended to build on the first generation method, but after its detailed analysis in the development stage it has been observed that the process can be unstable. The value of the stiffness ratio between the numerical substructure and the physical substructures has been identified as critical in governing the stability of the test, dictating whether the hybrid test needs to be applied in displacement control or force control. This is a severe drawback of the first generation method, as the stiffness ratio is unknown and changing during the test; besides different degrees-of-freedom can require different procedures during the test. Therefore, it has been shown that the first generation method should not be applied as it can lead to instability prematurely during the tests. To overcome the drawbacks of the first generation method, the objective was to develop a new technique that leads to interface equilibrium and compatibility while at the same time is unconditionally stable (i.e. independently of the stiffness ratio). Thus a novel methodology was developed and applied to the case of a concrete beam (PS) being part of a concrete moment resisting frame (NS). The novel method makes use of the PS’s stiffness in addition to the NS’s stiffness as it was the case in the first generation method. The stiffness matrix of the PS is unknown during the test therefore the initial tangent stiffness matrix is considered during the calculations. The latter choice influences the value of the time step to be adopted during the test. Every time step the boundary conditions are updated and it will be discussed how the chosen value can influence the results. A predetermined matrix is used to describe the behavior of the NS during the hybrid fire tests. This approach does not capture the nonlinearity of the remainder but at the same time the implementation is relative simple and the negative effect of the time calculation is eliminated. The procedure to compute the predetermined matrix of the NS is presented in this thesis. One possible direction in the future development of hybrid fire testing is to model the NS in the finite element model. The algorithm of the proposed method is developed and implemented in nonlinear finite element software SAFIR in order to perform virtual hybrid fire tests. The same algorithm is translated in order to be implemented by the company in charge of the control system at the CERIB furnace facility. The thesis also presents a traditional fire test that has been performed on the beam, in order to highlight the differences when testing structural element without and with the real boundary conditions. For the hybrid test, three degrees-of-freedom are controlled at the interface. The furnace facility has an important role to perform successful test where the equilibrium and compatibility are ensured and no instability occurs during the test. The impediments encountered during the tests will be discussed along with the recommendation for a successful hybrid fire test. [less ▲]

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See detailReforming of toluene formed during the gasification of biomass with alumina based catalysts prepared by aqueous sol-gel processes
Claude, Vincent ULg

Doctoral thesis (2017)

Summary in english: The gasification of biomass into bio-syngas (CO+H2) usually goes along with the formation of tars (toluene, naphthalene) which can cause technical problems at the outlet of the reactor ... [more ▼]

Summary in english: The gasification of biomass into bio-syngas (CO+H2) usually goes along with the formation of tars (toluene, naphthalene) which can cause technical problems at the outlet of the reactor. The reforming of these tars via primary catalysts (inside the reactor) or secondary catalysts (outside the reactor) currently appears as the most interesting way from practical and economical point of views. The use of catalysts made of metallic nanoparticles deposited on y-Al2O3 is an efficient combination for tar reforming applications. During this project, an aqueous sol-gel method for the synthesis of y-Al2O3 supports is developed. In the aim of developing catalysts with metallic nanoparticles finely dispersed, supports of y-Al2O3 are modified with a functionalized silicon precursor (3-(2-aminoethylamino)propyltrimethoxysilane, EDAS). The addition of EDAS modifies the properties of y-Al2O3. Samples prepared with other silicon precursors (non-functionalized or functionalized with other chains than the ones of EDAS) highlight that the reactivity of the precursor influences the crystallinity of the support. The presence of a functionalized chain modifies the shape of the crystallites, which leads to a narrower pore size distribution centered on 4 nm and to a higher specific surface area of the support. In order to orientate the project towards the development of either primary or secondary catalysts, catalytic tests are performed with 8000 ppmv of toluene under primary conditions (T = 750-850 °C) with either y-Al2O3 or olivine supports, doped with either 2 wt. % Ni or 10 wt. % Fe. The olivine, known as primary catalyst of reference, shows better performances. In the case of y-Al2O3, the low loading of Ni leads to the formation of a spinel of NiAl2O4 which shows low reducibility, and the doping with Fe favors the y-Al2O3 to a-Al2O3 phase transition of the support. Therefore, the next studies focuse on the development of 10 wt. % Ni/y-Al2O3 catalysts tested in secondary conditions. The reduction of catalysts entirely composed of NiAl2O4 only starts at T = 680 °C during H2- TPR measurements. However, these samples are reduced during the catalytic reforming of 24.000 ppmv of toluene at T = 650 °C. It is demonstrated that under these conditions, toluene is a better reducing agent than H2 or CO, and that the reduction of NiAl2O4 oxide with toluene enables its conversion with a very little formation of coke. For bulk NiO, reduced at low temperatures (T ~ 450 °C), the catalyst does not take advantage of the anti-coking effect brought by the phenomenon of special reduction by toluene, which leads to a quick deactivation of the catalyst by formation of carbon deposit. The addition of a surfactant (stearic acid) during the aqueous sol-gel synthesis efficiently modifies the morphology (mesopores, macropores) of Ni/y-Al2O3 catalysts. Despite a much higher catalytic activity, attributed to a better diffusion of the gaseous reagents, the sample shows a much higher sensibility towards deactivation by coking. It is hypothesized that this weakness is the consequence of the combination of several facts: loss of balance between the reaction rates of toluene cracking and the rates of dissociation-migration of the HO* and O* species + better reducibility of the catalyst, which avoids the phenomenon of special reduction by toluene + presence of large pores, which do not prevent the growth of filamentous carbon. A vast screening of catalysts composed of 10 % Ni/y-Al2O3 and doped with metals (Cu, Mn, Fe, Mo or Mn) or oxides (CaO, K2O, MgO or CeO2) is performed. The samples doped with Mn, Mo, Ca ou K show the most interesting catalytic activities and resistances against coking. It is to notice that, for an identical amount, the samples doped with two different elements (Co+Mo, Mn+Mo, Ca+K or Ce+K) show better catalytic performances compared to those doped with only one type of dopant. The tests of the best catalysts in long-term conditions (30 h) or in presence of H2S are promising. Hence, these catalysts might be adequate for industrial applications. Résumé français: La gazéification de biomasse en bio-syngas (CO+H2) s’accompagne généralement de formation de goudrons (toluène, naphtalène) qui peuvent causer des problèmes techniques en aval du réacteur. Le reformage de ces goudrons via un catalyseur primaire (à l’intérieur du réacteur) ou secondaire (en sortie du réacteur) apparaît actuellement comme la méthode la plus intéressante d’un point de vue pratique et économique. L’utilisation de catalyseurs constitués de nanoparticules métalliques supportées sur y-Al2O3 est une association efficace pour le reformage catalytique de goudrons. Une méthode de synthèse de support y-Al2O3 par voie sol-gel aqueuse est mise au point durant ce projet. Dans l’optique de synthétiser des catalyseurs composés de nanoparticules métalliques finement dispersées, des supports en y-Al2O3 sont modifiés avec un précurseur de silice fonctionnalisé : l’EDAS (3-(2-aminoéthylamino)propyltriméthoxysilane). L’addition d’EDAS modifie les propriétés texturales du support y-Al2O3. Des échantillons préparés avec d’autres types de précurseurs de silice (non-fonctionnalisés ou fonctionnalisés avec d’autres chaînes que celle présente dans l’EDAS) mettent en évidence le fait que la réactivité du précurseur de silice influence la cristallinité du support. La présence d’une chaîne fonctionnalisée modifie quant à elle la forme des cristallites d’alumine, menant ainsi à une distribution de taille de mésopores plus étroite et centrée à 4 nm et une plus grande surface spécifique du support. Afin de déterminer quel type de catalyseurs synthétiser (primaires ou secondaires), le reformage catalytique de 8000 ppmv de toluène en conditions primaires (T = 750-850 °C) est effectué avec des supports constitués de γ-Al2O3 ou d’olivine, dopés avec 2 % Ni ou 10 % Fe. L’olivine, catalyseur primaire de référence, présente de meilleurs résultats pour le reformage du toluène. Dans le cas de y-Al2O3, le faible dopage en Ni conduit à la formation d’un spinelle NiAl2O4 difficile à réduire, et le dopage avec Fe favorise la transition de phase de y-Al2O3 vers a-Al2O3. Les travaux suivants sont donc axés sur le développement de catalyseurs de type 10 % Ni/y-Al2O3 testés en conditions secondaires. La réduction de catalyseurs constitués d’une unique phase de NiAl2O4 ne s’initie qu’à partir de T = 680 °C lors de mesures en température programmée sous H2 (TPR). Cependant, ceux-ci sont réduits lors du reformage catalytique de 24.000 ppmv de toluène à T = 650 °C. Il est démontré que dans ces conditions, le toluène est un meilleur agent réducteur que H2 ou CO, et que la réduction des espèces NiAl2O4 par le toluène permet de convertir celui-ci en syngas tout en prévenant la formation de coke. Lors de la présence de NiO réduit à plus basse température (T ~ 450 °C), le catalyseur ne tire pas avantage du phénomène de réduction spécial des oxydes métalliques par le toluène, ce qui entraîne ainsi la désactivation rapide du catalyseur par cokage. L’ajout d’un surfactant (acide stéarique) lors de la préparation par voie sol-gel aqueuse s’avère efficace afin de modifier la morphologie (mésopores, macropores) de catalyseurs Ni/y-Al2O3. Malgré une activité catalytique nettement plus élevée, attribuée à une meilleure diffusion des réactifs, l’échantillon montre des tendances beaucoup plus importantes à se désactiver par cokage. On émet l’hypothèse que cette faiblesse est due à une combinaison de plusieurs faits: déséquilibre entre la réaction de cracking du toluène et les réactions de dissociation-migration des espèces HO* et O* + meilleure réductibilité empêchant de tirer avantage du phénomène de réduction spécial par le toluène + présence de larges pores ne restreignant pas la croissance de carbone filamentaire. Un large screening de catalyseurs 10 % Ni/y-Al2O3 dopés avec des métaux (Cu, Mn, Fe, Mo ou Mn) ou des oxydes (CaO, K2O, MgO ou CeO2) est effectué. Les échantillons contenant les éléments Mn, Mo, Ca ou K s’avèrent les plus intéressants de par leur activité catalytique et leur résistance au cokage. Pour une même quantité massique ajoutée, les échantillons constitués d’associations de dopants (Co+Mo, Mn+Mo, Ca+K ou Ce+K) affichent de meilleures performances catalytiques que ceux effectués avec un seul dopant. Les résultats obtenus avec les meilleurs catalyseurs lors de tests catalytiques de longue durée (30 h) ou en présence de H2S sont prometteurs. Ceci porte à croire que ces catalyseurs pourraient convenir à une application industrielle. [less ▲]

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See detailThe interplay of regional systems of innovation, strategic alliances and open innovation
Segers, Jean ULg

Doctoral thesis (2017)

Modern biotechnology is a driving force and a full grown industry in the international economy with ongoing and rapid innovations. The emphasis of this dissertation is on the valorization of red biotech ... [more ▼]

Modern biotechnology is a driving force and a full grown industry in the international economy with ongoing and rapid innovations. The emphasis of this dissertation is on the valorization of red biotech, i.e. pharmaceutical and healthcare applications. Belgium has firmly established itself as an international red biotechnology country, with a world class biotechnology industry in the Flanders and Wallonia bioRegions. Developing a domestic biotechnology industry - and hence new biotechnology firms - can be influenced by regional policy. The pharmaceutical-biotechnology regional and sectoral innovation system is characterized as an international and dynamic network architecture involving numerous players engaged in drug discovery. Regional governments and dedicated public and private network organizations have supported emerging new biotechnology firms by providing critical resources and by promoting an institutional environment that has enabled partnerships between universities, highly specialized research centers, small science based academic spin-offs and corporate spin-outs and large global pharmaceutical companies. Both policy and big firms look at the new biotechnology firms from a strategic point of view. The policy objective is the emergence of new and sustainable firms in the region; the big firms objective is the filling or renewal of the pipelines of products. New biotechnology firms are both beneficiaries and targets of strategic partnering alliances with large and global (bio)pharmaceutical companies. A number of the Belgian new biotechnology firms hold a nodal position as “ most preferred partner ” with multiple alliances in dynamic R&D networks. They have a high degree of integration into global technological networks through strategic alliances. Strategic alliances and open innovation are commonly leveraged. Despite their small size and relative immaturity, some of the new biotechnology firms are able to adopt innovative business models by providing R&D and services to large biopharmaceutical companies and by cooperating with them through open innovation. [less ▲]

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See detailThree Essays on Conditional Accounting Conservatism
Boussaid, Nabila ULg

Doctoral thesis (2017)

Accounting conservatism is one of the oldest concepts in accounting, yet it is one of the most controversial topics nowadays. While there is little debate on the existence of accounting conservatism ... [more ▼]

Accounting conservatism is one of the oldest concepts in accounting, yet it is one of the most controversial topics nowadays. While there is little debate on the existence of accounting conservatism practices, the drivers and the implications of these accounting practices show considerable divergence between accounting researchers and standard setters (such as FASB/IASB). In their 2010 conceptual frameworks, the FASB and IASB removed conservatism from the qualitative characteristics of financial reporting. This decision has been the subject of considerable criticism from accounting researchers and has sparked a new debate on the mechanisms driving accounting conservatism as well as its benefits to market participants. This dissertation contributes to this new debate by providing three empirical essays on accounting conservatism. The first essay (Chapter 2) is part of the literature investigating the relation between accounting conservatism and corporate governance mechanisms. It documents that board attributes are important determinants of conservatism in financial reporting of French firms. The second essay (Chapter 3) extends the previous study and examines how the relation between board attributes and accounting conservatism varies across three European countries, namely, France, Germany and the UK. This essay emphasizes that the relationship between board characteristics and accounting conservatism is country dependent. Taken together, these two essays expand our understanding of how corporate governance mechanisms influence accounting quality. The third essay (Chapter 4) focuses rather on the informational benefits of accounting conservatism to financial market participants. This essay shows, in particular, that accounting conservatism improves the performance of analysts’ forecasts as well as the stock market liquidity. Overall, the main message to take away from this research is that accounting conservatism is closely related to corporate governance mechanisms and offers a powerful tool to provide verifiable information. [less ▲]

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See detailEmergence du sujet-entrepreneur au Cameroun. L'engagement entrepreneurial saisi par la réappropriation subjective d'expériences socio-biographiques
Amougou, Gérard ULg

Doctoral thesis (2017)

Cette recherche traite de la dynamique de subjectivation portée par la figure du sujet-entrepreneur, évoluant en dehors du sérail étatique au Cameroun. Son expérience biographique laisse percevoir un ... [more ▼]

Cette recherche traite de la dynamique de subjectivation portée par la figure du sujet-entrepreneur, évoluant en dehors du sérail étatique au Cameroun. Son expérience biographique laisse percevoir un modèle d’engagement dit entrepreneurial qui l’inscrit au cœur de l’histoire sociale et politique en cours. Le récit de vie laisse percevoir un souci pressant de réalisation de soi qui le pousse à relativiser les supports institutionnels classiques, et non moins contraignantes, de socialisation. Durant son parcours, la démarcation de ces dernières conduit à la répugnance d’une carrière administrative « tranquille » et est assortie d’un discours critique sur la politique du ventre. Cette démarcation serait en outre au cœur d’une rupture biographique qui l’astreint à s’engager, de manière individualisée, à la promotion d’une société utopique à partir de son champ professionnel. Son engagement présente une variété de typologies d’action liées à la sensibilité et aux convictions personnelles, à l’expérience acquise au cours de la trajectoire biographique, et à l’orientation donnée à l’activité. Cette variété d’actions trouve un lieu commun dans le besoin de subvertir l’ordre sociopolitique dominant en vue de promouvoir l’avènement d’une cité alternative. En cela, les logiques d’action du sujet-entrepreneur s’inscrivent dans une dynamique historique de subjectivation qui informe les processus d’individualisation. [less ▲]

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See detailLe moment de l'illusion dans la déhiscence du sujet et de son monde. Perspectives anthropo-téléologiques depuis Kant et Winnicott.
Notturni, Loris ULg

Doctoral thesis (2017)

Quelle pourrait être la raison pour laquelle les philosophes, d'habitude si labiles et si doctes sur tous les sujets, sont si peu enclins à se pencher sur un berceau ? Pourquoi, la plupart du temps, les ... [more ▼]

Quelle pourrait être la raison pour laquelle les philosophes, d'habitude si labiles et si doctes sur tous les sujets, sont si peu enclins à se pencher sur un berceau ? Pourquoi, la plupart du temps, les philosophes éludent-ils dans leur discours sur la subjectivité humaine ses débuts et sa fin, c'est-à-dire son histoire réelle ? Le présent travail n'a pas l'ambition de répondre à ces questions mais de pallier ce manque : élucider de manière originale l'histoire de la subjectivité humaine vivante et fournir les moyens pour en rendre compte de manière consistante. En philosophie contemporaine, et plus particulièrement en phénoménologie, tout se passe souvent comme si la notion de subjectivité constituait, à l'instar de l'objectivité, autant une évidence souveraine qu'un simple concept opératoire. Mais, paradoxalement, lorsque le philosophe prononce le mot : « subjectivité », il ne nous met rien sous les yeux, et l'on pourrait aller jusqu'à se demander si la réalité de ce concept a d'autres conditions formelles et matérielles que sa propre énonciation. Pour notre part, nous suspecterions bien plutôt que l'opérativité technique et la « souveraineté » ontologique de cette notion de subjectivité s'appuient toutes deux et en secret sur un réalisme métaphysique implicite du sujet, caractéristique de la Modernité et dont nous sommes toujours tributaires, réalisme alimenté en sous-main par d'incessants réaménagements sémantiques et d'innombrables effets de polysémie. Lorsque l'on emploie le mot « subjectivité », de quoi parle-t-on exactement ? Nous tenterons de clarifier cette question afin de pouvoir y répondre. Notre travail de recherche vise à réinterroger ce réalisme chronique de la subjectivité humaine en redéfinissant cette notion à la lumière de sa propre histoire. En ce qui nous concerne, le ressort initial de ce projet philosophique fut la coïncidence heureuse entre, d'une part, les interrogations cliniques issues de l'observation empirique des débuts de l'invidualité subjective humaine par un pédiatre anglais, Donald Woods Winnicott (1896-1971) et, d'autre part, la redéfinition radicale que la pensée critique d'Emmanuel Kant (1724-1804) a infligée à cette notion de subjectivité. Cette simple coïncidence thématique ne justifie pas à elle seule une recherche doctorale. Le motif essentiel légitimant la convocation d'auteurs aussi étrangers l'un à l'autre tient, avant toute chose, dans la nécessité des problèmes qu'ils ont dégagés dans leurs champs disciplinaires respectifs à propos de la subjectivité humaine. Pour résumer de manière générale, nous dirions à ce stade que la nécessité problématique principale qui, selon nous, croise les trajectoires intellectuelles kantienne et winnicottienne est la redéfinition de la notion de subjectivité à partir d'une autre notion, elle-même redéfinie : celle d'illusion. Selon nous, cette révision se diffracte sur trois plans épistémologiques différents, de complexité différente et non réductibles l'un à l'autre : premièrement, la subjectivité entendue comme objet possible d'une science pure a priori serait une illusion ; deuxièmement, l'illusion serait un mode constitutif de l'esprit subjectif dans ses rapports à certains objets, la subjectivité se définissant ici par son activité judicatoire ; troisièmement, l'illusion serait constituante du rapport de la subjectivité à elle-même et à son monde, entendue comme subjectivité humaine vivante. Ces trois « thèses » ne sont recevables qu'à la condition de bien entendre que les notions de subjectivité et d'illusion ont, à chaque niveau, des acceptions différentes. Notre étude visera à redéfinir ces deux notions et rendre manifeste leur intimité épistémologique, phénoménologique et génétique. Enfin, notre contribution personnelle permettra de montrer, preuves à l'appui, qu'il y a une filiation méthodologique, implicite et souterraine, jusqu'ici passée totalement inaperçue, entre Kant et Winnicott. En bref, nous affirmons que la pensée clinique de Winnicott et, plus particulièrement, son approche clinique de la genèse empirique de l'individualité subjective humaine dans le temps, se présente comme une réactualisation inaperçue et originale (à l'insu de l'auteur lui-même) des opérateurs épistémologiques et phénoménologiques et, d'une manière générale, du mode de pensée que Kant déploie dans la Critique de la faculté de juger. Enfin, nous montrerons que le concept d'illusion chez Winnicott, dont l'opérativité épistémologique et phénoménologique s'inscrit dans le droit fil de la pensée critique kantienne et de l'anthropologie hégélienne, réverbère un mode légitime d'appréciation de la subjectivité humaine vivante qui pourrait être d'une utilité précieuse pour l'anthropologie philosophique. En résumé, notre travail personnel s'est développé à partir de deux sources principales : la pensée clinique winnicottienne, entendue comme structure élective de phénomènes et de problèmes nécessaires, et la pensée critique kantienne, entendue comme garant épistémologique mettant à notre disposition une méthodologie fiable et puissante. Il ne s'agit ni d'une thèse « sur » Kant, ni d'une thèse « sur » Winnicott, mais d'un travail philosophique personnel réalisé à partir de l'intérêt suscité par ces auteurs et leurs démarches respectives. La première partie consistera en un préambule historique, guidé par une question capitale : par quels processus historiques et idéologiques la notion d'illusion, lourdement marquée par son passé métaphysique et diverses acceptions péjoratives remontant à l'Antiquité, en est-elle arrivée à être assumée au dix-huitième siècle chez Kant comme un opérateur épistémologique de premier plan, à savoir une disposition transcendantale de notre esprit (entendu comme faculté de connaissance) ? Dans la deuxième partie, nous développerons deux questions. La première, d'ordre épistémologique, pourrait être résumée comme suit : à quelle consistance épistémologique peut prétendre une description de la subjectivité humaine vivante ? La seconde question, dont la teneur sera essentiellement phénoménologique, sera la suivante : à partir de quand, comment et à quelles occasions la subjectivité humaine en vient-elle à prendre conscience d'elle-même en tant que subjectivité vivante et singulière dans les relations qu'elle entretient avec le monde, d'une part, auquel elle appartient et, d'autre part, duquel elle se différencie ? Une fois le cadre posé dans les termes de la méthodologie kantienne de la Critique de la faculté de juger, nous réactualiserons notre interrogation de la subjectivité humaine vivante et de son histoire à partir de la pensée clinique de Winnicott, tout en prenant la mesure de la consistance de son propos, grâce et par-delà Kant. La double question qui guidera la troisième partie se présentera comme suit : d'une part, quelles sont les questions épistémologiques qui émergent de la pratique pédopsychanalytique de Winnicott et, d'autre part, à quel point cette pratique, co-extensive à un champ disciplinaire spécifique, permet-elle de renouveler en profondeur, par son approche théorico-expérimentale et les questions nécessaires qui en émergent, la réflexion philosophique sur la subjectivité, son émergence et sa réalité ? [less ▲]

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See detailAERODYNAMIC AND AEROELASTIC MODELING OF HORIZONTAL AXIS WIND TURBINES USING PANEL METHODS
Prasad, Chandra Shekhar ULg

Doctoral thesis (2017)

Wind energy is one of the most reliable renewable energy sources and constitutes a viable alternative to fossil and nuclear fuels for the generation of electricity. Over the last couple of decades the ... [more ▼]

Wind energy is one of the most reliable renewable energy sources and constitutes a viable alternative to fossil and nuclear fuels for the generation of electricity. Over the last couple of decades the increasing demand for wind energy has resulted in increasingly large and sophisticated wind turbines. Accurate but efficient aerodynamic and aeroelastic modelling at the design stage has become a key issue. The surface panel and vortex lattice methods are efficient aerodynamic modelling tools that are routinely employed in design calculations by the aerospace industry. They constitute a good compromise between fidelity and computational cost in the preliminary design and optimization phase. However, these approaches have not been widely adopted for wind turbine modelling due to their inability to represent separated flow. The main objective of this thesis is the development of a 3D unsteady viscous-inviscid interaction technique that couples panel methods to a boundary layer solution and can be used to model separated flow over the blades of a wind turbine rotor. The technique is based on a quasi-3D, quasi-steady integral boundary layer solution, coupled to a 3D unsteady surface panel method by means of a two-way interaction scheme. The boundary layer solution results in an estimate of the separation line on the suction surface of the blade. A separated shear layer made up of doublet panels is shed from this line and allowed to propagate freely at the local flow velocity, exactly like the wake shed at the trailing edge. Aerodynamic pressure and load predictions obtained from this method are validated through comparison to experimental measurements from the NREL phase VI wind turbine. The thesis also describes the development of a complete methodology for the unsteady aeroelastic and aeroservoelastic modeling of horizontal axis wind turbines at the design stage. The methodology is based on the implementation of unsteady aerodynamic modeling, advanced control strategies and nonlinear finite element calculations in the Siemens LMS Samcef for Wind Turbines design package. The aerodynamic modelling is carried out by means of the unsteady Vortex Lattice Method. The complete methodology is used to perform full aeroservoelastic simulations of a 2MW prototype wind turbine model. [less ▲]

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See detailDEVELOPMENT OF FUNCTIONAL MICELLES FROM BIODEGRADABLE AMPHIPHILIC BLOCK COPOLYMERS FOR DRUG DELIVERY AND TUMOUR THERAPY
Gulfam, Muhammad ULg

Doctoral thesis (2017)

Drug delivery systems in the size range of ~ 10-250 nm are enabling tools for the site-specific targeting and controlled release applications. To take advantage of these capabilities, various nanocarriers ... [more ▼]

Drug delivery systems in the size range of ~ 10-250 nm are enabling tools for the site-specific targeting and controlled release applications. To take advantage of these capabilities, various nanocarriers e.g., micelles, dendrimers, liposomes, nanoparticles, nanocapsules, nanotubes, and nanogels have been designed for drug delivery. Specifically, micelle-based drug carrier systems have emerged as promising tools for site-specific delivery and controlled release applications. Despite several advantages over conventional drugs, some limitations of micelle-based drug delivery have also been reported. These drawbacks include low stability in vivo, poor penetration, modest accumulation in tumor tissues, and inadequate control over drug release. To overcome these limitations, stimuli-responsive or smart polymeric nanocarriers have been developed for drug delivery and tumour therapy, previously. The most well-known internal stimuli in cancerous regions include higher acidity associated with dysregulated metabolism in tumour tissues, elevated levels of glutathione in the cytosol and nucleus of cancer cells, and altered degradative enzymes in the lysosomes, and reactive oxygen species in the mitochondria. These intrinsic microenvironments can be exploited as internal stimuli to attain active drug release in the tumor tissues or cancer cells. Particularly, the reducing potential inside the cancer cells is considerably higher than found in the extracellular environment and bloodstream. Therefore, such varying redox potential can be exploited for tumor specific drug delivery and controlled release applications. Various types of redox-responsive micelles have been developed previously. Generally, redox responsive micelles have disulfide linkages that undergo rapid cleavage in the presence of reducing agents in the intracellular components, however, are stable at oxidizing extracellular environment. The redox-responsive disulfide bridges can be incorporated into nanocarriers by placing multiple disulfide bonds in the hydrophobic backbone or by conjugating therapeutic agents to the side chain of the polymer via a disulfide linker. Another strategy to construct redox-responsive linkages is to crosslink the polymeric nanocarriers with a disulfide crosslinker. It has been studied that polymeric micelles can dissociate, especially upon administration when they are diluted below their critical micelle concentration. The stability of polymeric micelles can be enhanced by chemical crosslinking. Various types of crosslinked micelles can be prepared subjected to the localisation of the crosslinking, e.g. shell crosslinked micelles, and core crosslinked micelles. Introducing redox-responsive bridges by disulfide crosslinker may not only provide stability to nanocarriers against dilutions during circulation, but also render them responsive to reduction conditions. Specifically, redox-responsive core-crosslinked micelles have demonstrated good stability and better ‘stealth’ properties, however, the hydrophobic cores of most of the existing core-crosslinked micelles have been based on non-degradable polymers such as polyacrylamide or polyacrylate. The non-degradable constituent of the block copolymer may cause complications in clinical applications. Therefore, reduction-responsive core-crosslinked micelles comprising entirely of biologically inert or biocompatible and biodegradable polymers would be better candidates for drug delivery and controlled release application. To overcome these limitations, micelles based on polyesters (a class of aliphatic biodegradable polymers) can used for drug delivery application. In the last few decades, various FDA approved aliphatic polyesters e.g. poly(lactic-co-glycolic acid) (PLGA), poly(ε-caprolactone), and poly(lactic acid), have been intensively studied to exploit their potential in drug, gene and protein delivery and controlled release applications. However, most of these polyesters lack functional groups which make it difficult to incorporate redox-responsive linkages to core-crosslink their micelles. To address these issues, we have synthesized functional biodegradable and biocompatible block copolymers based on mPEG-b-poly(εCL-co-αClεCL). The pendent chloro groups of the block copolymer were converted into azides using nucleophilic substitution reaction to produce mPEG-b-poly(εCL-co-αN3CL) block copolymer as a precursor of reactive polymeric micelles. The synthesized polymers were characterized by NMR, FT-IR and size exclusion chromatography (SEC). Micelles were prepared using dialysis method and methotrexate (an anticancer drug) was loaded into the hydrophobic core of the reactive micelles. Micelles were subsequently crosslinked by a redox-responsive bis-alkyne ethyl disulfide crosslinker. The size distributions and morphology of core-crosslinked micelles were assessed using dynamic light scattering (DLS) and transmission electron microscopy. The drug release studies were performed under simulated non-reducing and reducing conditions. Cellular uptake studies in human breast cancer cells (MCF7 cells) were performed using Oregon-green loaded core-crosslinked micelles. The MTX-loaded core-crosslinked micelles were assessed for their cytotoxicity in human breast cancer cells by MTT assays. The apoptosis inducing potential of MTX-loaded core-crosslinked micelles was analysed using Hoechst/PI assays and was further probed by annexin-V/PI assays. The data from these studies indicate that drug release from these cross-linked micelles can be controlled and that the redox-responsive micelles are more effective carriers for MTX than non-cross-linked analogues in the cell-lines tested. In another strategy, a multifunctional amphiphilic block copolymer based on α-amine-PEG-b-poly(εCL-co-αN3εCL) was synthesized and subsequently was used to conjugate methotrexate on the hydrophilic block for receptor mediated targeting of breast cancer cells. Cellular uptake studies revealed 2.3-fold higher uptake of MTX-conjugated micelles as compared with un-conjugated micelles. The blank micelles showed low cytotoxicities in breast cancer cells, however, MTX-conjugated micelles exhibited greater antitumor activities in contrast to free-MTX. We hypothesize that these functional micelles could be potentially powerful nanocarriers for stimuli-responsive controlled release, active tumour targeting and therapy. [less ▲]

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See detailTHE IMPACT OF SURFACTANTS ON VEGETBLE WHIPPED CREAM PROPERTIES IN RELATION WITH THE EMPLOYED FAT
Petrut, Raul Flaviu ULg

Doctoral thesis (2017)

Vegetable whipped creams are nowadays a popular alternative to the traditional dairy whipped creams. The emulsions standing at the base of vegetable whipped creams are classified as O/W emulsions. During ... [more ▼]

Vegetable whipped creams are nowadays a popular alternative to the traditional dairy whipped creams. The emulsions standing at the base of vegetable whipped creams are classified as O/W emulsions. During whipping air is incorporated and entrapped by a fat crystallize network. This is achieved by the fat droplets interaction through the partial coalescence mechanism. Hence the presence of a crystalline fat phase is imperative within the formulation of the whipped cream. In order to control the partial coalescence and stabilize both the emulsion and the whipped cream, emulsifiers are required. Therefore in such systems, proteins and LMW surfactants coexists and dictate the degree and rate of partial coalesce. This allows the tailoring of the sensorial attributes and physico-chemical properties of the whipped cream (e.g. stability, overrun, texture). Nevertheless the impact of the components on the whipped cream properties has to be understood as a whole and not as individual effects of fats, proteins and LMW surfactants. [less ▲]

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See detailDépolution des sédiments d’une mangrove de l’estuaire du Wouri : évaluation du potentiel de microflores.
Semboung Lang, Firmin ULg

Doctoral thesis (2017)

L’importance des écosystèmes de mangroves n’est plus à démontrer dans l’équilibre naturel des côtes des régions tropicales. Elles constituent un écosystème particulier et jouent un rôle important dans la ... [more ▼]

L’importance des écosystèmes de mangroves n’est plus à démontrer dans l’équilibre naturel des côtes des régions tropicales. Elles constituent un écosystème particulier et jouent un rôle important dans la production de la biomasse. Mais l’exploitation excessive du bois des palétuviers, les pollutions diverses suite à l’exploitation pétrolière et gazière, sont autant de facteurs qui contribuent à la dégradation des forêts de mangroves. Ainsi, entre 1980 et 2000, environ 35% de la superficie mondiale des mangroves a disparu. La pollution a entraîné une dégradation considérable des mangroves. Une quantité grandissante de déchets résultant des activités urbaines, industrielles et agricoles et de l’exploitation en mer du pétrole et du gaz est rejetée sans aucun traitement dans la mer et se retrouve au niveau des mangroves. Les déversements accidentels d’hydrocarbures en mer entraînent une grave pollution des mangroves et la pollution marine provenant des navires est une menace qui va sans doute s’accroître avec le développement de l’exploitation pétrolière. L’objectif de cette thèse était de mettre au point une méthode de dépollution par voie biologique des sédiments de mangroves pollués par les hydrocarbures. Il s’agissait plus précisément d’évaluer les capacités intrinsèques de dégradation de la microflore spécifique endogène, de comparer le potentiel de dégradation de cette microflore avec d’autres souches pures connues pour leur capacité à dégrader les hydrocarbures et enfin d’évaluer les différentes techniques de biodégradation adaptées pour l’élimination des hydrocarbures dans les sédiments de mangroves. Des procédés biologiques adaptés ont été mis en œuvre au cours de ce travail pour restaurer les écosystèmes de mangroves. Différentes techniques de traitements biologiques impliquant la microflore spécifique endogène ont été mises en œuvre. L’évaluation du potentiel de dégradation de cette microflore a été réalisée par rapport à trois souches pures exogènes. Les résultats obtenus ont montré que le potentiel de dégradation de la microflore spécifique est comparable à celui de Rhodococcus erythropolis lorsqu’on augmente sa concentration dans les sédiments (107 CFU.g-1 de matière sèche). La croissance de cette microflore est accélérée avec la présence des nutriments tels l’azote et le phosphore. Ce qui relève davantage le taux de dégradation des hydrocarbures. Le taux de dégradation obtenu en combinant les traitements par bioaugmentation de la microflore spécifique endogène et biostimulation (86%) nous ont amené à proposer cette méthode pour dépolluer les sédiments de mangroves. L’utilisation de la microflore spécifique endogène évite de travailler avec des souches exogènes qui nous exposent aux problèmes écologiques et éthiques liés à leur utilisation. [less ▲]

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See detailLe travail de la décision. Les processus de l'application des peines en Belgique francophone
Bastard, Joséphine ULg

Doctoral thesis (2017)

Cette recherche porte sur la prise de décision des tribunaux de l’application des peines (TAP), considérée au sein de la série d’actions qui la rend possible. Les décisions de libération anticipée de ... [more ▼]

Cette recherche porte sur la prise de décision des tribunaux de l’application des peines (TAP), considérée au sein de la série d’actions qui la rend possible. Les décisions de libération anticipée de prison se construisent en effet dans des processus longs, en interdépendance avec les acteurs institutionnels dans les établissements pénitentiaires, l’administration centrale en charge des « petites sorties » qui servent à préparer les projets de réinsertion, et les TAP qui finalement valident ou informent ces processus par leur décision motivée. La thèse rend compte de la complexité de la décision collective, en suivant le passage du droit de l’application des peines dans ses trois organisations, la prison, l’administration centrale et le TAP, le long des situations de travail des acteurs. La méthode est inductive, et l’enquête qualitative, constituée d’entretiens semi-directifs, d’observations des acteurs au travail, de lectures approfondies des dossiers et d’observations d’audiences des TAP. L’ensemble de ces matériaux permettent de suivre tous les agents, supports ou lieux de la décision et de reconstituer la trajectoire des cas de l’application des peines, en portant attention aux documents, aux pratiques et finalement au partage de sens entre les acteurs. La thèse vise ainsi à montrer que la décision ne se réduit pas à une situation ou un moment, mais qu’elle est le produit d’un processus, organisationnel, de partage de pratique et de sens, créant les routines de l’action collective. La multiplicité des acteurs sont autant d’épreuves à franchir pour les cas, produisant des jugements multiples sur l’individu et permettant notamment la justification de la décision. La juridictionnalisation, seulement partielle de l’application des peines, introduite en 2006, montre ainsi en pratique un traitement administratif et centralisé des demandes, un système de décision complexifié, qui crée des verrous supplémentaires sans désactiver ceux qui lui préexistaient. [less ▲]

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See detailDevelopment of molecular tools for rapid detection and quantification of indoor airborne molds to assess their impact on public health
Libert, Xavier ULg

Doctoral thesis (2017)

Currently, contamination of the indoor environment by fungi is suggested to be a public health problem, although scientific evidence on the causal link is still limited. The monitoring of indoor airborne ... [more ▼]

Currently, contamination of the indoor environment by fungi is suggested to be a public health problem, although scientific evidence on the causal link is still limited. The monitoring of indoor airborne fungal contamination is a common tool to help understanding the link between fungi in houses and respiratory problems. Classical monitoring methods, based on cultivation and microscopic identification, have some limitations. For example, uncultivable or dead fungi (“unknown” fraction) cannot be identified, although they could have an impact on human health. In this context, molecular tools seem to be a valuable alternative. In this PhD work, different molecular tools were developed, from simplex to multiplex, to detect and identify indoor airborne fungi. The goal was to improve the detection of fungal contaminants, including the “unknown” fraction, as compared to the currently used classical monitoring methods. The necessary air sampling and DNA extraction protocols, adapted to the downstream molecular monitoring methods have also been developed. Through the application of the developed tools to specific case studies, we aimed to improve the current knowledge on fungal contamination. At first, we developed a specific ITS-based SYBR®green real-time PCR (qPCR) assay for Aspergillus versicolor, a species frequently observed in indoor air and known to be allergenic. Additionally, an ITS-based qPCR assay was developed for the specific detection of Exophiala jeanselmei, a pathogenic yeast suspected to be a part of the “unknown fraction”. The performance of these qPCR methods was assessed. This comparison demonstrated that SYBR®green qPCR assays can be used as a molecular alternative for monitoring of contaminated samples while eliminating the need for culturing and thereby considerably decreasing the required analysis time. However, qPCR has some limitations especially concerning the discrimination of genetically close species and multiplexing. The first issue was addressed through the use of post-qPCR high resolution melting (HRM) analysis, providing a proof-of-concept for this approach, using 3 closely related Aspergillus, i.e., A. versicolor, Aspergillus creber and Aspergillus sydowii. This HRM tool will allow a more accurate monitoring of these closely related indoor air contaminants, thereby contributing to an improved insight in the causal link between the specific presence of these species and health issues. The multiplexing issue was overcome through a Luminex xMAP® assay, developed for the simultaneous detection of the 10 most frequently in indoor air found fungi. All the species identified with the classical method were also detected with the xMAP® assay, however in a shorter time frame, and using less sample material. This assay will improve the communication with the involved medical team and the patient. To provide scientific evidence for the causal link between indoor airborne fungi and health problems, the full diversity needs however to be identified. This cannot be achieved by using a targeted assay. Therefore, next generation sequencing (NGS) could offer a valuable alternative as an open approach multiplex monitoring method. An NGS-based metagenomics approach was used to investigate the “unknown” agents in air samples of offices in contact with air-conditioning reservoirs and showed the first detection of E. jeanselmei in indoor air. Finally, a metagenomics analysis was performed to investigate the indoor airborne fungal diversity in contaminated residences in Brussels where people with health problems were living. This demonstrated that NGS could contribute to improved data concerning the indoor airborne fungal diversity, as compared to the currently used classical methods. The methods developed in this PhD work and the insights obtained are a first step for a better understanding of the causal link between indoor airborne fungi and public health. [less ▲]

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See detailÉtude du cytosquelette de microtubules et implication de la vimentine dans le développement postnatal de la cochlée chez les rongeurs
Renauld, Justine ULg

Doctoral thesis (2017)

According to the World Health Organization, nearly 5% of the population suffers from hearing impairments. These can lead to social isolation, depression, or a reduction in professional abilities. There ... [more ▼]

According to the World Health Organization, nearly 5% of the population suffers from hearing impairments. These can lead to social isolation, depression, or a reduction in professional abilities. There are two types of hearing impairments : conductive hearing impairment and sensorineural hearing impairment. The first results from a defect in sound conduction at the level of the outer or middle ear, the latter results from defects in the cochlea or auditory nerve. In recent years, most studies on the organ of hearing have focused on sensory cells, which are actual receptors of auditory information, whereas supporting cells have been little explored. However, the latter, surrounding the sensory cells, contain a highly developed cytoskeleton, essential to the architecture of the mature organ of Corti. During this thesis work, we first observed the setting up of microtubules within the supporting cells of the organ of Corti. Our morphological data revealed important changes in microtubular cytoskeleton of these cells during the first week of life. We identified an arrangement of microtubules into two distinct bundles. We then demonstrated a modification in the morphology of these microtubules, revealing an increase in the diameter and the number of protofilaments of these cells. We finally demonstrated that tubulin βV has a more specific spatiotemporal distribution than the other tubulins. This characteristic suggests that tubulin βV plays an important role in the maturation of the Corti organ. In the second part of this thesis, we analyzed the involvement of vimentin in cochlear development, and more particularly in the opening of the intercellular spaces and in the myelination of the spiral ganglion, which is the first relay of the auditory pathway. In order to study the role of vimentin in the development of the inner ear, we examined the cochlear morphology and auditory capacities of vimentin deficient mice. Our results indicated that the absence of vimentin does not seem to affect the architecture of the organ of Corti. We then showed a slight morphological difference in the nerve fibers between wildtype and vimentin-knockout mice. We finally checked the hearing physiology of these mice and concluded that vimentin does not play a major role in hearing. [less ▲]

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See detailLeidenfrost effect at its limits
Maquet, Laurent ULg

Doctoral thesis (2017)

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See detailFlexible Bayesian Models for Interval-Censored Survival Data
Cetinyürek, Aysun ULg

Doctoral thesis (2017)

Interval-censored time-to-event data arise frequently in clinical trials and longitudinal studies, where the event of interest is only known to have occurred between the two consecutive visits. Interval ... [more ▼]

Interval-censored time-to-event data arise frequently in clinical trials and longitudinal studies, where the event of interest is only known to have occurred between the two consecutive visits. Interval-censoring is a natural generalization of right censored time-to-event data. For right-censored data, extensive number of statistical techniques are available to tackle most research questions under a variety of assumptions. However, for interval-censored data, less well developed procedures are available. A sparse offer in statistical softwares to handle this type of censoring has driven many researchers to use imputation techniques, especially right-point or mid-point imputation. However such imputation strategies can lead to misleading inferences. Our thesis proposes and studies the properties of innovative methods to analyze such data. In the first part of the text, we have extended a Bayesian density estimation procedure for grouped data to estimate hazard ratios and survival functions from interval-censored data. If one further assumes proportionality of the hazards, the proposed strategy also provides estimates of global covariate effects. Clearly, the proposed method provides very good estimates for the regression coefficients and successfully approximates the baseline survival function when the mean interval width is smaller than some threshold defined from the data standard deviation. In a Cox proportional hazards model, the observations are assumed to be independent. However, this may not be true in certain situations where the observed units are clustered or subject to multiple measurements. A number of approaches generalizing Cox's PH model to handle correlated interval-censored data have been proposed in the literature. The shared frailty model is a popular tool to analyze correlated right-censored time-to-event data. Frailty models have also been adapted to handle interval-censored data. In the case of interval-censored time-to-event data, the inclusion of frailties results in complicated intractable likelihoods. In the second part of this thesis, we propose flexible frailty models for analyzing such data by assuming a smooth flexible form for the conditional time-to-event distribution and a parametric or a flexible form for the frailty distribution. It has been indicated in the literature in different contexts that the misspecification of the random effect distribution can influence the estimation of quantities of primary interest, like the fixed effects. To circumvent such misspecification, we have suggested modeling the distribution of the frailty in a flexible way using P-splines or a gamma shape mixture (GSM) distribution. The biggest advantage of using a flexible specification for the density of frailty arises when its shape is of specific interest. If it is considered as a nuisance, assuming a simpler lognormal or gamma frailty would be an adequate solution to draw conclusions related to other model parameters, such as regression coefficients and variance of frailties. Indeed, it was shown in the simulation study that the regression parameter estimates in a shared frailty PH model are robust to the misspecification of the frailty density. Moreover the use of a flexible form for the frailty does not cause any loss of precision in the estimation of regression parameters when compared to the simpler parametric frailty model. Both models provide the possibility to visualize the baseline density and survival functions. Given sufficiently large sample sizes, the flexible approach produces smooth and accurate posterior estimates for the baseline survival function and for the frailty density, and can correctly detect and identify unusual frailty density forms. [less ▲]

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See detailRôles et fonctions des intermédiaires du marché du travail sécurisant les transitions professionnelles
Lorquet, Nadège ULg

Doctoral thesis (2017)

Dans un marché du travail en constante évolution, la flexibilité des emplois et les trajectoires des travailleurs semblent être des sujets incontournables lors de l’étude des organisations. Simultanément ... [more ▼]

Dans un marché du travail en constante évolution, la flexibilité des emplois et les trajectoires des travailleurs semblent être des sujets incontournables lors de l’étude des organisations. Simultanément, de plus en plus de travaux s’intéressent aux rôles des intermédiaires du marché du travail et aux fonctions jouées par ceux-ci à l’intersection entre marché et organisations et entre organisations et travailleurs. Peu de travaux cependant ont cherché explicitement à rapprocher ces deux sujets de recherche, c’est-à-dire à étudier spécifiquement les rôles des intermédiaires du marché du travail sécurisant les trajectoires professionnelles. La présente thèse propose de s’y consacrer. Pour ce faire, douze dispositifs ont été sélectionnés pour leur qualité d’intermédiaire visant à sécuriser les transitions des travailleurs sur le marché du travail. Chacun a fait l’objet d’une étude de cas approfondie, menant à l’élaboration d’une grille d’analyse multidimensionnelle et originale capable de comparer ces dispositifs entre eux. Construite sur base de six critères de différenciation, chacun divisé en trois modalités, la matrice permet de distinguer deux types-idéaux, le « quasi-salarié » et le « quasi-indépendant », caractérisant deux modèles d’intermédiation distincts dont peuvent bénéficier les travailleurs accompagnés lors de leurs transitions. Emergeant d’un processus abductif important, la grille d’analyse multidimensionnelle mobilise de nombreuses références théoriques provenant de diverses disciplines (gestion, droit, économie, sociologie, etc.). Cette thèse s’inscrivant néanmoins en gestion, elle commence par démontrer les principales mutations du marché du travail liées aux organisations, aux carrières et à l’emploi avant d’étudier divers concepts relatifs aux marchés transitionnels du travail et aux intermédiaires également repris sous l’appellation de « Labour Market Intermediaries, LMIs ». [less ▲]

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See detailSédimentologie et contrôle eustatique: cas du Miocène, Tunisie centre Nord
Belghithi, Hanen ULg

Doctoral thesis (2017)

En Afrique du Nord, au Néogène, la compression qui affecte le domaine atlasique témoigne de la convergence Afrique-Europe, et se marque par des dépôts de séries silicoclastiques du Miocène pauvres en ... [more ▼]

En Afrique du Nord, au Néogène, la compression qui affecte le domaine atlasique témoigne de la convergence Afrique-Europe, et se marque par des dépôts de séries silicoclastiques du Miocène pauvres en faune. Le présent projet s’intéresse à caractériser les variations spatiotemporelles des faciès, les variations eustatiques et les corrélations de ces séries miocènes. Pour ce faire, nous observons et analysons les différents mécanismes sédimentaires, afin d’identifier des surfaces remarquables corrélables et se baser sur l’analyse séquentielle et les variations de susceptibilité magnétique. Sur la base des données obtenues, l’objectif est de proposer un modèle sédimentologique, étudier les variations eustatiques à l’échelle régionale, établir des corrélations et élaborer un modèle paléogéographique des séries du Miocène en Tunisie. [less ▲]

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See detailLandscape ecological consequences of the (sub)urbanization process in an African city: Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg

Doctoral thesis (2017)

If anthropogenic effect is a general term accounting for the influence of human activities on environment, it may also designate specific influences that may be inter- and intralinked. Thus, urbanization ... [more ▼]

If anthropogenic effect is a general term accounting for the influence of human activities on environment, it may also designate specific influences that may be inter- and intralinked. Thus, urbanization and suburbanization are anthropogenic processes contributing to the broad anthropogenic effect. They hide in turn other subprocesses of land transformation that will be called here the secondary spatial impacts. However, although the growing influence of the latter processes, they are still not defined consensually nor exist a comprehensive and applied-oriented methodology to delimit them. The general objective of this thesis is to develop a spatially explicit methodology to evaluate the landscape ecological consequences of the urbanization and suburbanization processes, taking a representative city of Sub-Saharan Africa as a case study: Lubumbashi (Democratic Republic of Congo), and the last decade as the period of study. That general objective is addressed through two themes, to which correspond specific objectives. The first theme concerns the evaluation of the anthropogenic land use and land cover dynamics and the second one proposes a methodology to evaluate the expansion of urban and suburban areas, in relation with consistent definitions of the areas in the urban-rural gradient. For both themes, the propositions are based on remote sensing techniques and landscape ecology metrics. Results show that the region of Lubumbashi underwent a global anthropisation increase mostly constituted of minor rises of anthropisation levels but impacting mainly the most natural landscape classes. Urban and suburban areas were located through the use of the proportion of built-up metric, the secondary spatial impact area through the use of adjacencies of the less natural landscape patches. The growth shape of the urban and suburban areas is concentric, except in the south-western part of the city where an affluent of the river Kafubu and its adjacent wetlands slow the urban expansion. The secondary spatial impact area dynamics seems determined, in the north-west, by the relief and, in the north-east, by a transportation axis. It is the latter dynamics that is dominant for the period. It corresponds to the so-called savanisation process, probably due to wood fuel and charcoal production. The methodologies developed here could be improved by taking connectedness into account, by using an additional configuration metric for the definition of urban areas or by taking advantage of spatially explicit socio-economic data. They could also be tested on mining sites, other cities and/or using images of different spatial resolution. [less ▲]

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See detailGeophysical characterization and monitoring of a municipal solid waste landfill
Dumont, Gaël ULg

Doctoral thesis (2017)

During this thesis, we aimed at demonstrating the value of geophysical methods for a waste deposit characterization in the context of landfill mining, both for energy and raw materials valorization. Our ... [more ▼]

During this thesis, we aimed at demonstrating the value of geophysical methods for a waste deposit characterization in the context of landfill mining, both for energy and raw materials valorization. Our preliminary analysis of the literature revealed that a multi-scale and multi-method investigation strategy was required. We also noticed an increasing interest in geoelectrical methods for the waste water content estimation, and for the monitoring of water content changes due to infiltration through the cover layer and water recirculation operation in bioreactor landfills. Firstly, we used the electromagnetic (EM) and magnetic mapping methods, quick and cost effective, to determine the site horizontal boundaries of our test-landfill. We combined the Horizontal to Vertical Noise Spectral Ratio (HVNSR) and the Multichannel Analysis of Surface Waves (MASW) seismic methods to estimate the thickness of this particularly deep deposit site. We also used the electrical resistivity tomography (ERT) to estimate the depth to water table and characterize the humidity of the unsaturated zone. Secondly, we investigated the suitability of geoelectrical methods (ERT, and borehole EM) to obtain spatially distributed information over the waste water content. For this purpose, petrophysical laws (established with laboratory experiments on waste samples) controlling the effects of water content, density and temperature on the bulk electrical resistivity of humid waste were established. Thirdly, we used numerical simulations to highlight several pitfalls occurring during the ERT monitoring of fresh water infiltration through a landfill cover layer. The effects on the interpretation of electrical resistivity changes of the ERT resolution, the background condition heterogeneity, the uncertainty on water content computation, and the often neglected dilution, were considered to extract the maximum information from the data and avoid over-interpretation. Lastly, we combined the ERT and the distributed temperature monitoring methods to evaluate the efficiency of horizontal drains, which are commonly used to regulate water content in a bioreactor. This tools provided us with valuable insight on the drain design suitability (diameter, depth, length, injected volume, etc.), the injected water flow behavior (waste anisotropy, heterogeneity, and the effect of vertical gas wells), and the humidification of the dry waste material efficiency. Taken together, our results have shown that geophysics represents a valuable approach for landfill investigation, provided that a special care is given to the data analysis. We thus finally discussed several interpretations limitation and proposed some insights to overcome them. [less ▲]

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See detailUn « Laboratoire belge » du droit international (1869-1940) ? Réseaux internationaux, expériences et mémoires de guerre des juristes belges
Genin, Vincent ULg

Doctoral thesis (2017)

Circonscrire une problématique implique de dégager plusieurs hypothèses de travail. La Première Guerre mondiale représente le pivot autour duquel ces hypothèses s’articuleront et seront mises à l’épreuve ... [more ▼]

Circonscrire une problématique implique de dégager plusieurs hypothèses de travail. La Première Guerre mondiale représente le pivot autour duquel ces hypothèses s’articuleront et seront mises à l’épreuve. Celle-ci étant destinée à les « mettre à l’épreuve ». À l’issue de ce travail, nous espérons que la confrontation de ces hypothèses à l’analyse historique permettra la décantation de conclusions générales dont émanera une thèse définie. La Guerre de 1914-1918, par son caractère global, ses « innovations » technologiques, son degré de violence, marque une étape significative de l’histoire contemporaine. La Belgique, premier pays du front Ouest à être envahi, se situe aux premières loges de cette nouvelle phase historique. Territoire dont la neutralité « perpétuelle, permanente et garantie » est violée, en transgression du droit international public, ce point d’ancrage semble propice à l’étude d’un milieu ayant peu attiré l’attention des historiens : les juristes belges de droit international. Nous estimons que cette étude est à même de mieux nous informer sur les caractéristiques de ce milieu professionnel en soi, concerné au premier chef par l’acte inaugural de la guerre, sur ses pratiques, ses codes, ses réseaux internationaux, la positionnalité des juristes, mais aussi, en négatif, de nous renseigner sur un aspect méconnu de l’image de la Belgique et de sa position dans la hiérarchie internationale, à savoir sa contribution au droit international. L’évolution de ce milieu et de ce qu’il représente, à l’aune de la Guerre de 1914-1918, reconnue pour avoir acceléré la juridicisation des relations internationales, constitue l’essentiel de l’angle d’approche adopté par notre recherche. Toutefois, il est permis de dégager plusieurs hypothèses, dont chacune recouvre un critère de cette approche plus générale : En effet, le conflit modifie-t-il le degré de légitimité de cette catégorie de juristes dans le champ scientifique belge et exerce-t-il une influence similaire dans le champ académique ? Dans quelle mesure les internationalistes belges jouent-ils un nouveau rôle, après 1918, dans le cadre de la politique étrangère officielle du pays ? Par extension, nous nous intéresserons à leur rapport au milieu des diplomates. Nous tenterons également d’évaluer dans quelle mesure ces juristes sont les acteurs d’un phénomène transnational ou, au contraire, s’ils poursuivent des objectifs dont les intérêts sont « nationaux ». Par ailleurs, ces juristes peuvent-ils être considérés comme des indicateurs, des pierres de touche, de l’évolution de la position de la Belgique dans le « Concert des nations » ? Le cas échéant, nous tenterons de comprendre dans quelle mesure cette « condition » d’indicateur évolue entre l’avant-1914 et l’après-1918. Ces juristes contribuent-ils à la défense d’enjeux idéologiques et/ou politiques et comment se positionnent-ils par rapport aux conceptions jusnaturalistes et juspositivistes ? À l’aune des réflexions précédentes, il est possible d’envisager une problématique générale, que l’on peut énoncer comme suit : Dans quelle mesure les juristes belges de droit international public, de la fin du XIXème siècle au milieu du XXème siècle, ont tissé des réseaux internationaux, été des indicateurs de l’évolution de la Belgique dans la hiérarchie internationale et, surtout, ont été influencés par l’expérience de la Guerre de 1914-1918, en tant que génératrice d’une mémoire influant sur les modes d’expressions et de représentations de ce groupe social, jusqu’en 1940. [less ▲]

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See detailDEVELOPMENT OF ANALYTICAL TOOLS FOR THE DETERMINATION OF MARKERS OF LIPID ALTERATION IN FOOD
Douny, Caroline ULg

Doctoral thesis (2017)

It is now well-known that n-3 polyunsaturated fatty acids (omega-3 PUFA) have beneficial effects on health but are also rapidly oxidized in potentially toxic compounds, which means that healthy food ... [more ▼]

It is now well-known that n-3 polyunsaturated fatty acids (omega-3 PUFA) have beneficial effects on health but are also rapidly oxidized in potentially toxic compounds, which means that healthy food products, rich in n-3 PUFA, can become toxic for the consumer if not stored or processed appropriately. The main objective of this work was to develop new analytical tools to study markers of lipids alteration in food, in order to allow an adequate monitoring of possible toxic compounds in n-3 PUFA rich food products. The first chapter of this PhD thesis is a literature review about fatty acids, their oxidation and the different oxidation products generated. The different analytical techniques used to study the oxidative stability of polyunsaturated fatty acids and their degradation products in food are also described. Chapter 2 describes the development of a gas chromatography coupled to mass spectrometry (GC-MS) method to analyze the fatty acids in food. The method was applied to eggs and pork (both standard and n-3 enriched) submitted to various cooking processes and storage conditions. This study confirmed that the fat of standard eggs or pork from the Belgian market cannot be considered as a source ofn-3 PUFA.. Indeed, in this work, we measured no n-3 PUFA in meat or only around 2 % for eggs, while the fat of both enriched eggs and pork contained about 10 % of n-3 fatty acids. After storage or cooking without culinary fat no change of the fatty acid profile was observed, in standard eggs or pork. We made the same observation for n-3 enriched products, except for some cooking processes (pan-frying and oven cooking), which induced a slight but significant loss of n-3 fatty acids in n-3 enriched eggs or pork. The fairly stable behavior of the fatty acids after various cooking and storage experiments indicates that the fatty acid profile is not a good marker of lipid alteration. As a consequence, this work was oriented to the development of analytical tools to evaluate the presence of toxic aldehydes in food and feed as secondary oxidation products coming from polyunsaturated fatty acids. Chapter 3 is dedicated to the study of the oxidative stability of linseed oil, an oil rich in n-3 fatty acids. Section 3.1 describes the development of a liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method to evaluate the aldehyde content in linseed oil. After optimisation of the extraction, derivation, detection and quantification steps, the method was validated according to guidelines from the European legislation as well as the recommendations of the AFNOR protocol NF V 03-110 (AFNOR, 2010). The evaluated parameters included specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, determined using the concept of accuracy profiles. When the method was applied to first pressure linseed oil stored for several days at 60 °C according to the Schaal oven test, it was shown that 4-hydroxy-2E-hexenal (4-HHE) was the most produced aldehyde. In Section 3.2, the different patterns of oxidation of linseed oil in real-time and accelerated aging assays were investigated, in order to verify the hypothesis commonly accepted for vegetal oil that one day aging at 60 °C is equivalent to one month real time aging at room temperature. Oxidation was evaluated with the peroxide value and para-anisidine value, as well as the content in conjugated dienes and aldehydes. All four indicators of oxidation showed very different kinetic behaviours at 20 and 60 °C, showing that the hypothesis (1 day at 60 °C = 1 month at 20 °C) is not valid for linseed oil. Chapter 4 describes the adaptation and the validation of a LC-MS/MS method to determine aldehydes in animal feed samples. Indeed, as animal feed is often enriched with linseed to increase the human intake of n-3 fatty acids through the consumption of food from animal origin, the study of the oxidative stability of n-3 enriched animal feed is also of interest. To achieve that goal, the LC-MS/MS method previously developed for linseed oil was adapted to include more aldehydes and was validated using the same guidelines as in section 3.1. Finally, chapter 5 presents the discussion and conclusions about the developed methods and the results obtained as well as their comparison with literature. Future prospects to improve the evaluation of and the exposure to the markers of lipid alteration in food are proposed. [less ▲]

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See detailDécider les politiques culturelles en démocraties : les politiques du théâtre de la Communauté française de Belgique.
Lowies, Jean-Gilles ULg

Doctoral thesis (2017)

Depuis que la Belgique existe, l’État intervient dans le secteur de la culture, il mène des politiques culturelles dont un aspect majeur consiste à octroyer des financements. Qui décide l’octroi des ... [more ▼]

Depuis que la Belgique existe, l’État intervient dans le secteur de la culture, il mène des politiques culturelles dont un aspect majeur consiste à octroyer des financements. Qui décide l’octroi des subventions ? Comment ces attributions sont-elles décidées ? Quels sont les critères de choix ? L’autonomie artistique des théâtres est elle préservée ? Quelle est la place d’un pouvoir politique démocratique dans des choix artistiques subjectifs ? Voilà quelques questions qui seront abordées au cours de cet ouvrage. Parmi nombre d’enjeux sociaux, économiques et artistiques émaillant la thématique, nous aborderons spécifiquement les liens entre culture et politique, entre l’art et l’exercice du pouvoir, c’est à dire la décision. À cette fin, la recherche se concentre sur l’analyse du processus décisionnel des politiques publiques de la Communauté française dans le domaine du théâtre, concernant principalement la période s’étalant de 2003 à 2016. Comment un État démocratique peut-il décider une action publique en matière culturelle sans prétendre au monopole de la culture légitime ? Décider les politiques culturelles en régime démocratique ne relève pas d’une évidence partagée. Il existe un paradoxe constitutif à leur existence : l’État est sommé d’ « agir sans agir » et d’être « neutre », il est appelé à œuvrer de manière impartiale dans l’intérêt des gouvernés tout en ne s’immisçant pas sur le territoire de l’autonomie artistique. À vrai dire, aucun pays ne semble avoir trouvé de système décisionnel qui paraisse satisfaire pleinement l’idéal démocratique ni, plus prosaïquement, les intérêts de toutes les parties prenantes. Chaque pays conjugue les impératifs démocratiques avec les contraintes du contexte historique, sociopolitique et culturel pour établir des institutions, des procédures et des discours aptes à asseoir et légitimer les décisions. Comment la Communauté française de Belgique tend elle à résoudre cette délicate équation dans le secteur du théâtre ? La plupart des typologies de politiques culturelles prennent en considération le degré d'indépendance entre le politique et les arts. Les politiques culturelles belges – et celles de la Communauté française de Belgique – sont généralement situées entre l’idéaltype britannique et l'idéaltype français. Pour le premier, le financement des arts est décidé par des organismes non gouvernementaux et suit le principe du arm's length, principe de non-interférence. Pour le deuxième, les décisions sont centralisées et elles sont opérées directement par l’État. La Belgique aurait développé un modèle hybride, à mi-chemin entre les grandes nations précitées. A contrario, cet ouvrage développera l’hypothèse que le système décisionnel des politiques culturelles de la Communauté française est ancré dans un régime de consociativisme, mêlant les éléments d’une société pilarisée, d’une particratie et d’institutions empreintes du principe de pluralisme idéologique et philosophique tel que consacré par le Pacte culturel de 1973. [less ▲]

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See detailEtude du ligament suspenseur du boulet sain et pathologique chez le cheval : d'une approche biochimique à la cellule souche isolée en post-mortem
Shikh Al Sook, Mohamad Khir ULg

Doctoral thesis (2017)

Tendon and ligament lesions are the subject of much debate in both veterinary and human medicine. These lesions are multifactorial in origin, but the aetiology is still not fully understood. Generally ... [more ▼]

Tendon and ligament lesions are the subject of much debate in both veterinary and human medicine. These lesions are multifactorial in origin, but the aetiology is still not fully understood. Generally, healing occurs slowly with low quality repair tissue. Indeed, the repaired tissue exhibits a lower strength compared to healthy one and is prone to re-injury. In horses, these injuries can result in severe lameness, and have often a poor prognosis. Therefore, the presence of such lesions can be career-ending in sport horses, causing considerable economic losses. More precisely, suspensory ligament (SL) lesions are frequently encountered in horses. The SL is a heterogeneous structure which consists of dense collagenous connective and adipose tissues surrounding muscle bundles. To evaluate the alterations in collagen fibrils after SL injury, we opted for an ultrastructural approach by transmission electron microscope (TEM) coupled with a quantitative biochemical analysis. Ultrastructurally, the injured tissue appeared as a disorganized network of small diameter collagen fibrils (<80 nm) corresponding to type III and type V fibrils replacing the ones of large diameter (100–180 nm), predominant in normal tissue. The biochemical approach aiming at quantifying the relative proportion of various collagen types revealed that types III and V were significantly higher within the injured tissues. On the other hand, a significant decrease in the proportion of collagen I was recorded. This modified composition of the scar tissue confirms that the healing is far from perfect, even several months after an injury. Many therapeutic strategies have been proposed to improve the healing process. However, conventional therapeutic approaches that include surgery and/or conservative approaches have not given satisfactory results. As a consequence, researchers are redirecting their efforts towards cell-based therapeutic approaches, especially making use of mesenchymal stem cells (MSCs). Clinically, both autologous and allogeneic MSCs appear particularly promising in this regard. From this perspective, the MSCs isolated from the same tissue to regenerate should be more prone to improve ligament and tendon healing after injury. However, this approach is limited by the availability of these cells. In this context, we focused on the search for a new and more advantageous source of MSCs. Harvesting stem cell from cadaveric material presents an alternative strategy that could provide a source unexploited until now. Remarkably, our findings have shown that the tissues harvested from equine ligaments within 48-72 hours post-mortem constitute an available reservoir of stem cells. The isolated cells exhibited fibroblast-like morphology and were maintained for more than 20 passages with high cell viability and proliferation. These cells were subjected to freezing and thawing processes without change in their viability, growth ability, and differentiation potential. Flow cytometric analysis demonstrated the expression of mesenchymal cell markers CD73, CD90 and CD105 and the absence of the leukocyte common antigen CD45 and HLA-DR major histocompatibility complex class II(MHC II). Their stemness was also confirmed by analysis of their expression for octamer-binding transcription factor 4 (OCT-4) and stage-specific embryonic antigen 1 (SSEA-1). Moreover, their multipotent potential has been proven by the ability to differentiate towards osteoblast, adipocyte and chondrocyte. To conclude, this thesis contributes to a better understanding of the intimate mechanisms of SL repair at the histological and molecular levels. Moreover, the results achieved during this thesis raise the prospect that the tissues harvested from cadaveric ligaments could represent an easy and unlimited reservoir of stem cells. These cells could represent a promising material for tendon and ligament repair, opening up new perspectives in field of cell therapy and tissue engineering. [less ▲]

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See detailAssessment of landslide hazard in the environmental hotspot areas of the Kyrgyz Tien-Shan: Spatial analysis and Numeric modelling
Torgoev, Almazbek ULg

Doctoral thesis (2017)

This PhD research was initiated in parallel with the Nato Science for Peace project “Prevention of Landslide Dam Disasters in the Tien Shan, Kyrgyz Republic”. During this project a large amount of ... [more ▼]

This PhD research was initiated in parallel with the Nato Science for Peace project “Prevention of Landslide Dam Disasters in the Tien Shan, Kyrgyz Republic”. During this project a large amount of thematic data on slope instabilities and landslide dams in the Kyrgyz Tien-Shan was collected. The thesis uses this information to investigate applied and fundamental aspects of the regional mapping of the landslide susceptibility, hazard and, partially, risk. The target areas selected for the PhD research are the Mailuu-Suu River Valley (southern Kyrgyzstan) and the surroundings of the Minkush settlement (central Kyrgyzstan). They represent the areas of former uranium mining hosting numerous storage sites of tailing material and waste rock. Additionally, these areas are characterised by a high level of landslide activity induced by the human and environmental impacts. The landslides in those areas present a high risk to the society and infrastructure, potentially triggering serious environmental consequences. Structurally, the thesis is composed of two parts: Part A and Part B. These parts are different both with respect to the research methodology and the scientific targets. The common goal of both parts is the development effective techniques to regionally assess landslide hazard in mountainous areas marked by complex geomorphological, tectonic and geological settings. Due to the remote access, such areas are often lacking background information and in-situ data that are required for the precise prediction of landslide occurrence and impacts. In such cases the spatial analysis often helps to better characterise regional and, partly, local landslide susceptibility. The regional studies allow us to outline the basic relationships between affecting factors and landslide occurrence. Such results also become the basis for effective planning of in-situ investigations and localised measurements. Part A of thesis is focused on the applied aspects of spatial analysis. This part assembles a set of the well-established approaches and methods to model landslide susceptibility, hazard and risk. The studies start with the compilation of database spatially combining various thematic information. The first type of such thematic data is represented by the multi-temporal landslide inventories. These inventories are extracted applying different sources of remote sensing data, including the satellite and aerial imagery. The second type of thematic data describes the spatial distribution of factors affecting the level of landslide activity. The mapping of affecting factors is performed by applying conventional remote sensing techniques and spatial analysis tools. The collected thematic data are then used to extract the landslide susceptibility, hazard and risk maps. In total, four conceptually different approaches are applied to map the landslide susceptibility, both on a qualitative and quantitative basis. The results of the quantitative susceptibility mapping and thematic data are further used to calculate the landslide hazard for each part of the studied area. The calculated landslide hazard is characterized both by spatial and temporal components. The results of the landslide hazard assessment are finally used to estimate the risk of the direct impacts of landslides on selected exposed elements, including the uranium tailings sites. One of the well-established approaches used in Part A is the Newmark method. It maps the seismically triggered landslide susceptibility based on the computed co-seismic displacements. The simplicity of this method is attractive to many researches around the world studying seismically-triggered landslide hazards. Nevertheless, the simplifications adopted in this method strongly limit the reliability of the final predictions. In the second part of thesis we provide a critical overview of the Newmark method and attempt to propose conceptual improvements of the existing mapping practice. To reach the targeted challenges we combine the spatial analysis with the dynamic simulations in the 2D and 3D domains. The studied models represent the actual topographic and geologic settings of the landslide-prone slopes. The simulations provide acceleration time histories that are recorded in different parts of the model surface. The analyses of these records allow us to outline the amplification impacts related to the topographic and geological site effects. The modelled amplification factors are analysed with respect to their link to the local geological and topographic settings. Thus, we study how the structural or material settings of the model can impact the recorded geological amplification. Such impacting parameters can be represented by the layer thickness, inclination of the underground contacts or the contrast of the shear wave velocity (Vs) values. The 2D topographic modelling investigates the way how the pure topographic amplification factors can be predicted based on the surface morphology. The studies show that the surface curvature can be considered as a key parameter to predict the amplification factors. This idea is further investigated in the 3D modelling studies applying different input signals and the materials of varying Vs. The results of this modelling are integrated into a single database which is subjected to spatial analysis. This finally allows us to develop a simple proxy which maps the impacts of the topographic site effects based on morphological parameters extracted from the Digital Elevation Model of the target area. Additionally, the subset of the 2D dynamic tests analyses the shear displacements triggered by the seismic shaking. Those displacements are recorded in the models with simplified geometry, as well as in the ones presenting the real topographic settings. The recorded displacements are cross-correlated with parameters characterising the seismic impacts. The results of analyses allow us to develop a new law which can easily be used in the GIS-based studies. The proposed law applies a set of the conventional parameters as well as a novel predictor which has never been used by any regional law before.The conceptual improvements proposed in Part B are finally tested by applying them to the geodatabase compiled in the first part of thesis. Related results are then compared with those that were produced by using the conventional Newmark method. The validation tests should assess performance of the developed proxies to improve the predictions of seismically-triggered landslides. [less ▲]

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See detailLa pluralité familiale en droit interne à l'épreuve de la diversité des institutions familiales étrangères
Englert, Hélène ULg

Doctoral thesis (2017)

L'étude est consacrée au traitement juridique d'une double diversité : la pluralité des situations familiales internes et la diversité des institutions familiales étrangères. Elle repose, dans un premier ... [more ▼]

L'étude est consacrée au traitement juridique d'une double diversité : la pluralité des situations familiales internes et la diversité des institutions familiales étrangères. Elle repose, dans un premier temps, sur une analyse du droit familial interne pour en dégager les principes qui sous-tendent le droit belge de la famille. Dans un deuxième temps, des critères d’accueil des institutions familiales étrangères sont déterminés par une analyse de la tolérance de l’ordre juridique belge au droit étranger. La question posée, dans un troisième temps, étant, par une confrontation de la manière dont le droit traite ces deux familles "interne" et "internationale" de déterminer si le traitement juridique est identique ou à tout le moins cohérent, c’est-à-dire si les mêmes logiques juridiques sont à l’œuvre à l’égard des familles internes et des familles internationales. [less ▲]

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See detailThe lure of pedogenesis. An anthropological foray into making urban soils in contemporary France
Meulemans, Germain ULg

Doctoral thesis (2017)

This thesis is an anthropological inquiry into the emergence of urban soils as matters of concern in the worlds of soil scientists and other fields more traditionally involved with cities. City soils have ... [more ▼]

This thesis is an anthropological inquiry into the emergence of urban soils as matters of concern in the worlds of soil scientists and other fields more traditionally involved with cities. City soils have typically been neglected in modern thinking about nature and urbanism. They have long been framed solely as a technical question which seemed to require no further pondering until – in the last two decades – they entered the scope of the soil sciences. This thesis draws on over 13 months of multi-locale fieldwork conducted in Paris and Lorraine with soil scientists, gardeners and foundation builders. Through the lens of soil-making practices, it seeks to elucidate the specificity of new forms of urban pedogenesis, including the growth of soils and the lives of the humans associated with them. Building on scholarship in anthropology, the soil sciences, science studies, and speculative philosophy, it follows how these actors learn to be affected in the material performance of different relations between people and soils. Occasionally turning to narrative to complement analysis and more traditional ethnography, each chapter pulls a different diffractive string from the mesh of urban soil matters, and follows where it leads in what Deleuze and Guattari call an ‘itinerant’ mode of research. As ways of knowing that emerge from soil construction are described, the question of what making soils does to knowing them becomes a central thread of the thesis. In this, it looks at how soils participate in apparatuses where they become ‘lures for feelings’ – affective interweavings in which worlds are experienced. The introduction sets the stage for the thesis, and explains how the fieldwork was conducted. It sets pointers for the rest of the work by explaining the attentive, yet critical posture it adopts towards scientific theories of soils. The thesis is then divided into two parts: the first part (chapters 1-4) presents a detailed consideration of the world being newly explored by urban soil scientists, and showcases key points of encounter between pedology, the environmental sciences and themes such as urban sprawl, ‘peak soil’, and ‘the Anthropocene’. It starts by problematizing the movement by which, in the 19th century, urban soils became ‘blackboxed’ when their hard sealing initiated a long standing separation between earth and sky. This is followed by an examination of the renewed interest towards urban soils in realms as diverse as city planning, waste management and hydraulics. The thesis then turns to exploring more specifically the impact of urban soils on soil science research in France. It describes how the new urban soil sciences invoke non-linear ecological dynamics, and how they question distinctions such as those between the living and the non-living, and between the human and the natural. In the face of this questioning, scientists started to experiment with urban soils by engaging directly in their construction through their ‘ecological engineering’. Rejecting separations between making and theory, these practices are understood by attending to soil scientist’s digging practices, described as ways of learning to be affected by soils and their liveliness. This part concludes with a study of the multispecies interactions entailed in soil ecologists’ attempts to ‘collaborate’ with earthworms and other soil organisms. An analysis of the modes of joint becoming of soils and humans at play in soil construction is developed by way of a reinterpretation of the soil sciences’ concept of pedogenesis. These ideas are developed in the second part of the thesis (chapters 5-7), which addresses practices of urban soil construction in the fields of urban gardening and foundation building, and introduces an art and anthropology experiment. It first presents the work of urban gardeners who develop their own understanding of city soils and botany, and attempt to grow knowledge, soils and community by adapting ancient rural practices of earth working to the reclamation of city interstices. It then introduces the work of foundation builders, and shows that far from entailing soils as inert matter that would be malleable at will, their work can be characterised as a play on equilibrium across interfaces of exchange. The thesis concludes with the presentation of an art, anthropology and soil science experiment in which the author participated. In this experiment fieldwork was re-interrogated by means of narrative speculation and installation making. This finally provides the grounds from which to draw methodological conclusions for an experimental anthropology, premised on the interweaving of imagination and practice. [less ▲]

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See detailCartographie et propriétés physico-chimiques des argiles de Foumban (Ouest-Cameroun)
Nkalih Mefire, Abiba ULg

Doctoral thesis (2016)

La stratégie nationale de promotion des matériaux locaux pour le développement des infrastructures et de l'habitat nécessite l’acquisition des connaissances scientifiques sur lesdits matériaux. Dans ce ... [more ▼]

La stratégie nationale de promotion des matériaux locaux pour le développement des infrastructures et de l'habitat nécessite l’acquisition des connaissances scientifiques sur lesdits matériaux. Dans ce contexte, les argiles de Foumban et ses environs (Ouest-Cameroun) ont été répertoriées sur le terrain, échantillonnées et étudiées en laboratoire afin d’évaluer leur aptitude dans la fabrication des produits de terre cuite (brique cuite, et tuiles). Les travaux de terrain ont permis dans un premier temps de localiser et de caractériser morphologiquement les formations argileuses de type latéritiques ou hydromorphes dans un rayon de 50 kilomètres autour de Foumban, dans les localités de Koutaba, Bangourain, Marom, NJindare et Njimom. Par la suite, le gisement d’argile hydromorphe de Koutaba a été choisi sur base de son extension latérale et verticale pour une évaluation des ressources. L’estimation quantitative de ce gisement sur un rayon de 2 km avec des pas de 200 m donne un tonnage de l’ordre de 18 216 000. La caractérisation minéralogique à partir des analyses minéralogiques (DRX, FTIR, ATG/DTG et MEB) indique que la kaolinite est le minéral argileux dominant, il est associé au quartz et aux feldspaths. On trouve des proportions variables d’illite, de smectite et aussi de chlorite. Les oxyhydroxydes de fer, d’alumine et de titane sont en trace. L’absence de souffre et de pyrite constituent un avantage sur le plan environnemental. L’étude géochimique montre que la silice, l’alumine et l’oxyde de fer sont dominants. La caractérisation physique donne quatre classes granulométriques avec des proportions variables d’un site à l’autre. L’indice de plasticité faible à élevé révèle le caractère moyennement plastique, plastique à très plastique des argiles étudiées. Ces résultats indiquent que les argiles étudiées sont aptes pour la fabrication des produits de terre cuite. Cependant, les argiles riches en smectite ne pourront être utilisées qu’après traitement par ajout de certains additifs. De même, celles qui sont plus ou moins plastiques pourront être dégraissées ou amendées. Les essais céramiques élaborés par voie sèche sur des cylindres cuits à des températures comprises entre 900-1200°C indiquent que les échantillons de Marom et certains échantillons de Koutaba peuvent être utilisés à l’état brut dans la fabrication des briques cuites pleines et des tuiles. Les argiles riches en quartz et pauvres en éléments fusibles, doivent par contre être amendées pour l'obtention d'un produit fini de bonne qualité à des températures inférieures à 1100°C. [less ▲]

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See detailLe marché, le politique et le réseau : les intermédiaires privés du marché du travail à l’épreuve de l’action publique
Gérard, Julie ULg

Doctoral thesis (2016)

Ce travail de thèse porte sur les enjeux de l’activation en Belgique francophone au sein du segment des intermédiaires privés du marché du travail. Il prend pour objet une mesure d’activation ... [more ▼]

Ce travail de thèse porte sur les enjeux de l’activation en Belgique francophone au sein du segment des intermédiaires privés du marché du travail. Il prend pour objet une mesure d’activation : l’accompagnement des demandeurs d’emploi. Cette mesure vise la réinsertion socioprofessionnelle des demandeurs d’emploi par une lutte contre l’exclusion et un retour à l’emploi. L’analyse de cette mesure d’activation repose sur l’étude approfondie de neuf dispositifs d’intermédiation privée, regroupés en trois catégories heuristiques : les intermédiaires de l’accompagnement vers, dans et après l’emploi. Ces catégories incarnent trois types d’accompagnement mis en oeuvre par les intermédiaires privés. Elles sont étudiées à partir d’une démarche empirique qualitative constituée d’observations (N=368), d’analyses documentaires et d’entretiens semi-directifs (N=95) ainsi que d’un cadre d’analyse général constitué d’une sociologie de l’action publique articulant trois perspectives théoriques : l’analyse des politiques publiques d’emploi ; la sociologie de l’action organisée et la sociologie des marchés. L’analyse montre que l’action de ces intermédiaires se concrétise par l’articulation de trois logiques d’action et de trois effets de trappe provoqués par l’influence de pressions institutionnelles exercées par le contexte social et par l’environnement à l’intérieur duquel la prise en charge des demandeurs d’emploi se réalise. Cette thèse entend ainsi démontrer qu’au-delà des contingences organisationnelles de chaque dispositif et de la marge de discrétion des acteurs en présence, l’action des intermédiaires privés du marché du travail s’inscrit dans un mouvement d’homogénéisation de l’action publique. Cette homogénéisation se traduit en une activité de profilage des demandeurs d’emploi fondée sur de multiples formes d’isomorphisme institutionnel. [less ▲]

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See detailCaractérisation des anomalies fluorées des eaux souterraines du socle Précambrien du Bénin central (Afrique de l’Ouest). Apport des outils hydrogéochimiques, pétrographiques et minéralogiques
Tossou, Yao ULg

Doctoral thesis (2016)

In Benin, groundwater is widely used for drinking-water supply for the populations. In the central part of the country (Département des Collines) characterized by hard Precambrian rocks, aquifers are ... [more ▼]

In Benin, groundwater is widely used for drinking-water supply for the populations. In the central part of the country (Département des Collines) characterized by hard Precambrian rocks, aquifers are unproductive and the water quality is affected by contamination. Groundwater quality problems concern particularly high fluoride concentration (up to 7 m/L) and nitrate concentration (up to 350 mg/L). Dental fluorosis is also endemic in the area. This work aims to explain the hydrogeochemical processes which govern mineralization of groundwater and the origin of high fluoride concentration. It will finally help for a better management and control of this environmental issue. The investigations were essentially based on two complementary approaches: hydrochemistry in one hand and in other hand, petrography, mineralogy and geochemistry study of the crystalline aquifer rock materials. Results show that the water mineralization is dominated by water-rock interaction, including the hydrolysis of silicate minerals. However, external inputs also greatly influence the concentration of certain chemichal elements such as nitrate and chloride. Fluoride concentrations seem to be mainly due to hydrolysis of ferromagnesian minerals like biotite. Ion exchanges (〖OH〗^-/F^-) between groundwater and the rock matrix also contribute to increase fluoride concentrations in groundwater. Geochemical investigations show that in the crystalline rocks constitutive minerals, fluorine concentrations are in the range of 60 - 2900 ppm with an average of 1170 ppm. Similar values were obtained in similar worldwide geological formations characterized by high concentrations of fluoride in groundwater. Several fluorine bearing minerals have been identified, such as fluorite, biotite, muscovite, apatite, amphibole, sphene, allanite were identified the basement rocks. Despite the fact that fluorite and apatite are the fluorine most concentrating minerals, biotite seems to be the most contributing mineral to fluorine content of the crystalline rocks. Furthermore, groundwater samples with high fluoride concentration are located in area which basement rocks have important F concentration and higher alterability index. From a geostatistical modeling of the collected data, decision support tools are proposed. Those tools are maps of spatial estimation of fluoride concentrations and probabilities to exceed the guideline value in the groundwater in Collines Department. [less ▲]

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See detail"'Unreadable' Texts: From the Metaphysical Detective Story to the Metacognitive Mystery Tale"
Dechene, Antoine ULg

Doctoral thesis (2016)

This dissertation aims at establishing the genealogy of a literary genre called the metacognitive mystery tale. Its main goal is to delineate a corpus of texts presenting "unreadable" mysteries which ... [more ▼]

This dissertation aims at establishing the genealogy of a literary genre called the metacognitive mystery tale. Its main goal is to delineate a corpus of texts presenting "unreadable" mysteries which, under the deceptively monolithic appearance of subverting "traditional" detective story conventions, offer a multiplicity of motifs – the overwhelming presence of chance, the unfulfilled quest for knowledge, the urban stroller lost in a labyrinthine text – that generate a vast array of epistemological and ontological uncertainties explored by the genre. The selected corpus, composed of some of the genre's most emblematic avatars as well as of less usual suspects, accounts for the specificity and heterogeneity of authors who, in different but related ways, have addressed a certain number of issues underlying the acquisition of knowledge. Following three major intertextual matrices based on the concepts of the "unreadable" city, the "dark" grotesque and the sublime, respectively, this project brings together texts by writers as diverse as Percy Bysshe Shelley, Edgar Allan Poe, Nathaniel Hawthorne, Herman Melville, Henry James, Horacio Quiroga, Jorge Luis Borges, Franz Kafka, Samuel Beckett, Paul Auster, Iain Sinclair and Roberto Bolaño under the banner of the metacognitive mystery tale. This approach represents an opportunity to gather canonical and barely academically studied works and provide new perspectives on stories dealing with the darker, more anxious aspects of investigations led by defective sleuths. [less ▲]

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See detailApplication des techniques de photogrammétrie par drone à la caractérisation des ressources forestières
Lisein, Jonathan ULg

Doctoral thesis (2016)

Une gestion raisonnée et multifonctionnelle des forêts n’est possible qu’avec une description à jour de l’état de la ressource naturelle. Les inventaires forestiers traditionnels, réalisés sur le terrain ... [more ▼]

Une gestion raisonnée et multifonctionnelle des forêts n’est possible qu’avec une description à jour de l’état de la ressource naturelle. Les inventaires forestiers traditionnels, réalisés sur le terrain, sont couteux et ne couvrent qu’un échantillonnage de la surface boisée. L’essor des drones civils pour la cartographie a initié une révolution dans le domaine de la télédétection environnementale. La polyvalence et la diversité des systèmes drones sont une aubaine pour la foresterie de précision. Ceux-ci sont utilisés pour la réalisation de cartographie très fine des habitats naturels avec une résolution temporelle et spatiale sans précédent. Nous explorons les possibilités d’utilisation de mini-drones pour la caractérisation quantitative et qualitative de la ressource forestière. Nous nous intéressons en particulier à l’estimation de la hauteur des arbres et à la caractérisation de la composition spécifique au sein de peuplements forestiers. La hauteur de la canopée est une variable dendrométrique de première importance : elle est un bon indicateur du stade de développement des peuplements et intervient notamment dans les estimations de biomasse ou de niveau de productivité. La composition spécifique est une information essentielle en regard des principales fonctions que remplit la forêt (conservation, production, récréation, etc). Nous avons comparé l’estimation de la hauteur des peuplements à partir de mesures LiDAR et celle obtenue par photogrammétrie. Bien que permettant une mesure de hauteur individuelle avec une incertitude de l’ordre de 1.04 m (RMSE) en feuillus, la photogrammétrie par drone sur des zones forestières est systématiquement moins précise que les mesures par LiDAR (RMSE de 0.83 m). Ces résultats sont cependant prometteurs, étant donné que la mesure sur terrain de la hauteur totale des arbres est également sujette à une importante imprécision. De plus, la grande flexibilité que confère les petits drones permet d’acquérir, au moment propice du stade de végétation, et l’information de relief de la canopée, et l’information spectrale. La période de fin de feuillaison, au début du mois de juin, s’est avérée le moment le plus propice à une discrimination automatique de cinq groupes d’essences feuillues (le chênes pédonculé, les bouleaux, l’érable sycomore, le frêne commun et les peupliers). Une erreur globale de classification des houppiers de 16% est obtenue avec des acquisitions monotemporelles, alors que l’utilisation d’images acquises à différentes dates permet encore d’améliorer cette classification (erreur globale de classification de 9% pour la meilleure combinaison de 3 dates). Les contraintes de la législation régissant l’utilisation des aéronefs sans pilote à bord restreignent le champs d’action des drones civils. Ainsi, afin d’assurer une sécurité pour tous les usagers de l’espace aérien, les opérations avec un drone sont limitées sous un seuil d’altitude et à une distance maximale du télépilote, ce qui ne permet pas une utilisation optimale de cette technologie pour la couverture de grands domaines forestiers (plusieurs milliers d’hectares). De plus, d’autres outils de télédétection utilisés en foresterie, tels que le LiDAR et l’imagerie satellite et aéroportée, sont plus compétitifs que les drones dès qu’il s’agit de couvrir de grandes surfaces (plusieurs milliers d’hectacre). C’est pourquoi nous pensons que les drones resterons un outils d’analyse de petites surfaces (dizaines voire centaines d’hectares), plus utiles à des fins de recherches scientifiques qu’à une utilisation en gestion forestière. [less ▲]

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See detailSapphire Ultraoptics for Sub-meV 121Sb and 125Te Phonon Spectroscopy
Jafari, Atefeh ULg

Doctoral thesis (2016)

Nuclear resonance scattering of synchrotron radiation enables probing hyperfine interactions and element specific vibrational modes of nuclei that exhibit a Mössbauer transition. A prerequisite for this ... [more ▼]

Nuclear resonance scattering of synchrotron radiation enables probing hyperfine interactions and element specific vibrational modes of nuclei that exhibit a Mössbauer transition. A prerequisite for this method is a monochromator with narrow bandwidth. Silicon, as the most commonly used crystal in monochromators, is not suitable for experiments above 30 keV photon energy. Using a sapphire single crystal in backscattering geometry is an alternative. An x-ray beam with narrow bandwidth can be obtained from a back-reflection with a Bragg angle of a few arcsec to a few arcmin smaller than =2. The development of a sapphire backscattering monochromator with high energy resolution, better than 1 meV, would permit detailed lattice dynamics characterization of novel functional materials. Sapphire is a very rigid material with desirable optical properties, high chemical resistance, and high heat conduction. Crystals of large size with high quality are of interest for many industrial applications, and suited for optics and optoelectronics operating under ambient condition or extreme conditions. The purpose of the work in this dissertation is twofold. First, study the quality of sapphire single crystals by modern high-resolution characterization techniques in order to acquire microstructural information and thereby a better understanding of the origin of lattice defects. The second goal is the study of the lattice dynamics in materials based on tellurium and antimony with Mössbauer energies of 35.49 keV and 37.13 keV using nuclear resonance scattering with energy resolution given by one of the highest quality sapphires. White beam topography of more than thirty crystals, grown at the Shubnikov Institute of Crystallography in Moscow, revealed qualitative information about the distribution of lattice defects of which linear defects, i.e. dislocations, are the majority type. The lowest dislocation density of 10^2 -10^5 cm^-2 was found in C-plane crystals grown by the Kyropoulos and Bridgman techniques. We carried out rocking curve imaging in backscattering geometry to estimate the lattice parameter variation and energy resolution from back-reflections. Minimum variations of the lattice parameters on the order of 10^-8 were observed from spots with an edge length of 0.2-0.5 mm. There are a few spots with such a quality in one crystal which makes it suitable as backscattering monochromator in nuclear resonance scattering or as analyzer in resonant inelastic x-ray scattering. The use of very high energy resolution nuclear inelastic scattering with 0.7 meV at the energy of the nuclear transition in 121Sb and 125Te enables valuable insight into the phonon scattering of thermoelectric materials, that convert heat to prvide electricity and vice versa, composed of Sb and Te. A careful study is done on heat carrying acoustic modes in the partial density of states of (PbTe)mAgSbTe2, so called LAST-m alloys. An impressive mismatch in the phonon group velocities in the 2-5 meV range and di erence in the force constants for the Sb and Te density of phonon states is observed, a phonon mismatch predicted to be responsible for low lattice thermal conductivity in LAST-m. An in-depth understanding of the element-specific dynamic properties of cubic and orthorhombic antimony trioxides was achieved using nuclear resonance scattering with an energy resolution of 1 meV at the nuclear transition energy of 121Sb. A softening of the Sb bonds upon transformation from cubic molecular structured in alpha-Sb2O3 to chain structured orthorhombic in beta-Sb2O3 is observed. Furthermore, results on the lattice dynamics on alpha-TeO2, with quasi molecular structure, demonstrate strong interatomic Te bonds, comparable with the strong bonds in molecular structured alpha-Sb2O3. The nuclear resonance data is complemented with inelastic neutron scattering data that reveals the oxygen vibrational modes. In addition, the experimental results validate the calculations of the vibrational modes in these types of materials and serve as benchmark for the calculation. [less ▲]

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See detailDEVELOPMENT OF A DISCRETE EVENT SIMULATION BASED TOOL FOR OFFSHORE LOGISTICS IN WIND FARM INSTALLATION
Muhabie, Yohannes Tekle ULg

Doctoral thesis (2016)

The o shore wind energy development has shown a progress in the last ten years. Distance from the coast and the depth of the water are increasing continuously. The transport and installation of o -shore ... [more ▼]

The o shore wind energy development has shown a progress in the last ten years. Distance from the coast and the depth of the water are increasing continuously. The transport and installation of o -shore wind turbines is highly dependent on weather condition at sea. Delaying an activity in the logistics chain could have a signi cant impact on overall project completion. Hence there is a need to have a well-organized and thoroughly analyzed planning of the overall processes starting from the producers sites until the o shore site where the turbines will be installed. The weather conditions and the installation strategies are the major limit factors in uencing the o shore wind farm installations. In this thesis a Discrete Event Simulation (DES) based tool has been developed for o shore logistics in wind farm installation. It takes into account the weather restriction limits (wind speed and wave height), distance matrix, vessel characteristics and installation strategies. The logistics model maps out the activities of the o shore wind farm installations. Both historical and probabilistic weather data approaches have been implemented, analyzed and compared. The results indicated that the probabilistic approach is highly a ected by the random seed numbers used to set up the stochastic behavior of the input variable. Application of the developed tools to real O shore Wind Farm (OWF) con guration illustrated that there is a good agreement between the results obtained from the two approaches. However, it has been identi ed that the probabilistic approach may slightly underestimate the project lead time compared to the results obtained using historical data. Furthermore, weather downtime and sensitivity analysis have been carried out for di erent weather scenarios in order to identify the parameters that a ect the logistic chain signi cantly during the o shore wind farm installation. In this context, it is indicated that the lifting operation (limited by wind speed) causes the highest down time compared to other activities and improving the lifting operations could result in a signi cant reduction (10-15 %) in the overall project completion time. In conclusion, overall analysis indicated that the application of a DES tool improves the decision support system including the planning and control of the logistics processes of the o shore wind farm installation, reducing the associated risks. [less ▲]

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See detailValorisation des variétés de dattes secondaires tunisiennes par l’application de traitement hydrothermique
Mrabet, Abdessalem ULg

Doctoral thesis (2016)

The fruit of the date palm (Phoenix dactylifera L.) is one of the most abundant fruits in the world. Nearly 2,000 cultivars of date palm are known, but only some of them are evaluated for their ... [more ▼]

The fruit of the date palm (Phoenix dactylifera L.) is one of the most abundant fruits in the world. Nearly 2,000 cultivars of date palm are known, but only some of them are evaluated for their performance and their fruit quality. This work is a contribution to give value addition to date palm fruit (flesh and seed), from Tunisian secondary varieties, by studying physico-chemical and techno-functional properties of their heir solid fraction rich in fiber and their fraction liquid and rich in phenol and sugar, obtained after pretreatment. Date fleshes contained essentially 60 % total carbohydrates, 23-27 % lignin and 5-4 % dietary fibers. The rest of the components were lower than 4%, with remarkably low amounts of fat (0.3-0.5%) and phenols (0.04-0.07%). In contrast, the percentage of fat (13-17%) and phenols (1-5%) present in date seeds were of great interest. Due to these amounts of phenols, the antiradical activity of seeds was much higher (131-400 mmol TE/Kg dry weight) than that of the flesh (32-47 mmol TE/Kg dry weight). A pretreatment was tested for the total utilization of these dates. After applying several steam treatments condition, valuable dietary fiber concentrates have been obtained. Their recoveries were very similar for the different assays. Only its granulometry showed differences, increasing the fraction with size lower than 4 mm in more intense treatments. DFC had also a good nutritional quality, with high phenol (4-8%), cellulose (12-20%), hemicellulose (5-22%), protein (9-14%), fat (5-11%) and lignin (44-71%). Treatment conditions had higher influence than date variety in the chemical composition. Study of functional properties of these DFC revealed good water and oil retention capacities (5,37-8.50 g water/g DFC and 7,03-8.74 g oil/g DFC, respectively). Furthermore, DFC had also very high antiradical activity (230-580 mmols Trolox/ Kg FC). Thus, these DFC could be considered as a valuable source of antioxidant dietary fiber. The study of physicochemical characteristics showed that DFC had the highest potential to be used as a food ingredient. As an application, the DFC were incorporated in muffin formulations at levels of 2,5 and 5 %. The addition of DFC slightly influenced the technological characteristics of dough and increased their antioxidant properties compared to control. Study of sensory characteristics revealed that there are no significant differences between control and the muffin with DFC. The only concern about the use of this DFC is that its ratio between insoluble and soluble fiber (IF/SF) is very high, around 19, but the best physiological effects are obtained with ratios 1-2.3. For this reason an enzymatic digestion has been assayed in order to decrease this ratio. The different results have shown that, the amount of SF increased from 1.8% to 6.3%, and the ratio IF/SF changed from 19 to 2-3. Moreover, in addition to an increase in the antiradical activity the SF, gluco-, manno-, and xylo-oligosaccharides were identified, oligosaccharides which has been postulated as prebiotics. The study of the liquid phase, rich in soluble antioxidant (phenols), and sugars, was also necessary for the total utilization of the thermally treated dates. The obtained liquid fractions were characterized and their antioxidant capacity determined. The concentration of total phenols increased, by treatments up to 5311 mg/kg of fresh dates, and their antioxidant activity up to 62.5 mmol Trolox/kg of fresh date. Different phenolic extracts have been obtained from the liquid phase in order to used as a antioxidant in food or nutraceutical formulation. The date phenolic extract were fractionated chromatographically using adsorbent or ionic resins to determine the most active fractions. The phenolic profiles were determined for each fraction, yielding fractions with interesting antioxidant activities with EC50 values of up to 0.08 mg/L or values of TEAC of 0.67 mmol Trolox®/g of extract. In addition, the antioxidant properties on lipophilic matrix of the organic extracts of date were also determined, using vegetable and fish oils, as well as the antimicrobial activity. The result showed a remarkable protection against lipid oxidation in oils, increasing the stability of sunflower oil by Rancimat method by four-fold. In addition, some extracts with interesting antimicrobial effects. [less ▲]

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See detailUnreinforced clay masonry structures: advanced characterisation of the seismic behaviour including acoustic issues
Mordant, Christophe ULg

Doctoral thesis (2016)

Unreinforced masonry (URM) is traditionally used in North-Western Europe as load- bearing solution for low- to mid-rise buildings. These regions are characterised by a low- to-moderate seismicity. Hence ... [more ▼]

Unreinforced masonry (URM) is traditionally used in North-Western Europe as load- bearing solution for low- to mid-rise buildings. These regions are characterised by a low- to-moderate seismicity. Hence, the earthquake action has to be considered in the structural design. An adequate consideration of the seismic action requires to properly understand how the URM structures behave under this speci c dynamic action and investigations are still needed in that eld. The in uence of openings and walls perpendicular to the seismic action are two main issues. Moreover, the seismic response of these structures is a ected by technical solutions developed to face the demand in terms of building physics performances. Even though, these solutions are not yet integrated in current standards. This thesis aims at improving the understanding of the seismic behaviour of URM struc- tures using a particular type of masonry bonding, for constructional e ciency purposes. Hollow clay blocks are assembled by thin-bed layered glue-mortar joints and a tongue-and- groove system for the head joints. The consequences of speci c details such as an opening, a perpendicular wall or soundproo ng rubber layers are also studied. Four experimental campaigns are presented. Fourteen URM sub-structures including speci c details are tested in static-cyclic and dynamic conditions. Details of the set-up, instrumentation layout and testing procedures are given. Processing of the data is then performed and conclusions are drawn. Regarding the shake table tests, a general rocking be- haviour strongly dependent on the length of the wall and the presence of rubber, is observed. Recommendations for the consideration of soundproo ng devices and for the openings are proposed. The contribution to the strength of perpendicular walls is also highlighted. Based on the dynamic characterisation of the specimens, equivalent mechanical properties are calibrated thanks to the frequency equation, derived from the Timoshenko beam theory. Two sets of boundary conditions are de ned to t the testing con gurations. The relevance of this theory is assessed and the importance of each term of the equation is discussed. In order to extend the results to complete buildings, the tested specimens are modelled in a software implementing an equivalent frame at the macro-scale. A multi-linear material law is calibrated based on a single specimen chosen as reference, in order to reproduce the experimental force-displacement curve. This law is then used for all specimens built in the same masonry type, independently of their geometry. A good approximation is obtained, even if the consideration of perpendicular walls could be improved. The shear capacity of non-rectangular URM walls depends on the compressive length. Its exact expression is thus developed with due consideration of the perpendicular section. Non linearities are observed due to the presence of the perpendicular section and simpli - cations are made for hand calculations. Both the use of the exact and simpli ed expressions in the assessment of the shear resistance provide results similar to the experiments. Finally, the modelling of the rocking motion is investigated. The walls without sound- proo ng devices are modelled following di erent existing models and their predictions are compared with experimental measurements, showing that masonry cannot be assumed as rigid. A main issue is the handling of the transition with impacts. A new model including two rigid blocks and exible and viscous layers is developed to reproduce the rocking behaviour of walls including rubber layers. In presence of rubber, the URM wall can be considered as rigid and model predictions satisfactorily corroborate the experimental measurements. [less ▲]

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See detailLa faisabilité et l'efficacité du traitement assisté par diacétylmorphine en Belgique
Demaret, Isabelle ULg

Doctoral thesis (2016)

Objective The aim of our research was to assess the feasibility and efficacy of a treatment assisted by diacetylmorphine in Liège. This treatment is offered to persons dependent on heroin who pursue ... [more ▼]

Objective The aim of our research was to assess the feasibility and efficacy of a treatment assisted by diacetylmorphine in Liège. This treatment is offered to persons dependent on heroin who pursue street heroin use despite existing treatments. Methods Data were collected in a pilot project of Treatment Assisted by Diacetylmorphine (TADAM), which took place in Liège from 2007 to 2013. The heart of this project is a randomised controlled trial comparing a diacetylmorphine treatment – limited to 12 months – with existing methadone treatments. A participant was responder if he/she showed improvement on the level of street heroin use, health or criminal involvement. Other researches (mainly based on interviews) were added in order to understand interactions between the trial and its actors: heroin users (included or not-included), neighbours of the DAM centre, the staff of the DAM centre and staff of other institutions who worked with our target group in Liège. Results With the help of the centres, partners of the trial, 74 participants (of the 200 planned) were included and randomised: 36 in the experimental group and 38 in the control group. These participants were dependent on heroin for 20 years on average and had already tried 9 treatments for their addiction(s). At the end of the trial, the number of responders in the experimental group was greater but not significantly than in the control group (p=0.35). However, participants in the experimental group showed greater improvement than in the control group, on the level of street heroin use (p=0.0011) and physical (p=0.043) or mental (p=0.035) health. During the follow-up study, three months after the end of the 12 months of treatment, street heroin use in the experimental group had significantly increased (p=0.0052) and the difference with the control group was no longer significant (p=0.55). Discussion Participants included in the trial were, as expected, persons severely dependent on street heroin, who could not find a solution to their addiction with the existing treatments. Participants in the experimental group decreased significantly their street heroin use. However, in our follow-up study, street heroin use increased significantly in the experimental group 3 months after the end of the diacetylmorphine treatment. In the foreign studies, diacetylmorphine treatment showed greater efficacy compared to methadone treatment for this target group and the improvement was sustained after the trial even when the treatment was stopped, but not when the end of treatment was forced against the will of the patient. Nevertheless, our research showed the feasibility of a diacetylmorphine treatment in Liège and its acceptance by the actors involved in the trial. Conclusion Diacetylmorphine treatment is feasible in Belgium. In foreign studies, it showed more efficacy than methadone treatment and benefits gained with this approach were maintained during years. But these benefits disappear when the end of treatment is forced, against the will of the patient. [less ▲]

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See detailReprésenter la connaissance en linguistique. Observations sur l’édition de matériaux et sur l’analyse syntaxique
Mazziotta, Nicolas ULg

Post doctoral thesis (2016)

In the field of linguistics, knowledge is often represented by the means of edited data (textual editions or structured databases) and diagrams. These representations can be called inscriptions of ... [more ▼]

In the field of linguistics, knowledge is often represented by the means of edited data (textual editions or structured databases) and diagrams. These representations can be called inscriptions of knowledge. They suggest three core questions. First of all, how to read them? The first chapter investigates the conventions at use to represent and organize information in edited data and syntactic diagrams. Secondly, how to choose what has to be inscribed? This chapter focuses on how only a part of data and analyses is represented in the inscriptions. An operation of reduction is always necessary and it accompanies the choices about what has to be represented. The choice of the formal structure used for encoding the inscription acts as a major constraint on what can and what cannot be inscribed. Thirdly, how do inscriptions allow us to discover more? This chapter is centered on the use of diagrams to unveil new knowledge about the facts and the theory. It is also shown that diagrams make it possible to investigate the relationships between formal structures themselves. A fourth chapter investigates digital inscriptions, showing how the use of the computer allows us to reevaluate the answers to all the aforementioned questions. [less ▲]

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See detailInitiatives populaires de solidarité internationale, des « bonnes intentions » au « professionnalisme » ? Sociologie d’un groupe professionnel à l’aune du sentiment de légitimité, dans une perspective comparative Belgique / France
Godin, Julie ULg

Doctoral thesis (2016)

Alongside established, high-profile non-governmental organisations (NGOs), many individuals decide that they need to “do something” to improve the lives of the people they have met (while travelling ... [more ▼]

Alongside established, high-profile non-governmental organisations (NGOs), many individuals decide that they need to “do something” to improve the lives of the people they have met (while travelling, living in another country or adopting a child, etc.). These people join forces with a small group of friends to set up their own development organisations (referred to hereafter as “popular development initiatives”, or PDIs). At present, one of the major concerns in international development cooperation is to make development workers more professional in the interest of better aid effectiveness. This thesis therefore looks at the discourses and practices of these “ordinary” citizens, in order to highlight their role and to identify key issues for this sector. More specifically, we study the dialectic process by which NGO staff and PDI volunteers build and define their professional and amateur legitimacy as development actors, through the prism of the interactionist perspective of the sociology of professional groups. We also draw on the sociology of public action to consider how public authorities, through their policy tools, influence the responsibility and legitimacy of these actors, the interactions between them, and their mutual recognition. The need for professionalism also stems from demands by local partners in the developing world, so we have taken an interest in their perceptions in the case of Senegal. [less ▲]

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See detailMineralogy and crystal chemistry of natural and synthetic uranyl oxysalts
Dal Bo, Fabrice ULg

Doctoral thesis (2016)

Since 1960, the number of described uranyl mineral species has been multiplied by three. To date more than 200 mineral species containing uranium as a main structural element are reported in Nature, and ... [more ▼]

Since 1960, the number of described uranyl mineral species has been multiplied by three. To date more than 200 mineral species containing uranium as a main structural element are reported in Nature, and the crystal structures have been determined and refined for only one third of them. Furthermore, many new uranyl minerals are still reported to data, showing sometimes novel chemical compositions and structural arrangements. The uranium mineralogy is a fascinating subject, and an essential field of research as it contributes to the improvement of the management techniques of nuclear waste. The first part of this work was dedicated to the mineralogical characterisation of uranyl minerals, and especially of the autunite-type minerals, occurring in the Rabejac deposit. Indeed, the identification analyses have shown that many samples contain uranyl arsenates of the autunite and meta-autunite groups. Electron-microprobe chemical analyses performed on these minerals species indicate that the P content in (meta-)zeunerite and (meta-)uranospinite is significant in several samples, confirming the solid-solution series between uranyl arsenates and phosphates. Also, cationic substitutions occurring on the A site were observed, especially in uranospinite samples, in which significant amount of Ca is substituted for Mg. Single-crystal X-ray diffraction experiments have been performed on many members of the (meta-)zeunerite-(meta-)torbernite series, and the crystallographic parameters were put into correlation with the variation of the chemical composition. The crystal structure of arsenuranospathite, the Asanalogue of the Al-bearing uranyl phosphate uranospathite, was solved for the first time, indicating that these two minerals are isostructural (Dal Bo et al., 2015). Also, a structure model is proposed for metauranocircite-I, one of the Ba-bearing uranyl phosphate of the meta-autunite group. Investigations of uranyl mineral samples from other localities have allowed to discover single-crystals of bassetite, one of the Fe end-members of the autunite group. The crystal structure of bassetite was also solved for the first time, and these new structural data were presented in parallel to those obtained on saléeite, the Mg-analogue of bassetite (Dal Bo et al., 2016). Thanks to these new data, a discussion about the mineral hierarchy of the (meta-)autunite group is proposed. In addition, the crystal structure of the rare Al-bearing uranyl phosphate furongite from the Kobokobo pegmatite was determined, showing that this mineral species has unique and novel structural features. This specific study, as well as the redefinition of the structural formula of phuralumite, was the occasion to provide a review about the formation of Al polyhedra clusters in uranyl minerals, and to try to elucidate their physicochemical conditions of crystallisation. Many new crystallographic data were also collected on uranyl minerals for which the crystal structure was already reported in the literature. Therefore, it was possible to confirm the previous studies, or to highlight important discrepancies, especially in the case of the Al-bearing uranyl phosphate phuralumite. The H-bonds networks, which are essential for the stability of the structure, have been established in the structure of the uranyl carbonate liebigite, and in the structure of the uranyl silicates cuprosklodowskite, kasolite and soddyite. The second part of this work was devoted to the hydrothermal synthesis of uranyl oxysalts. The experimental conditions, as well as the chemical systems, were chosen in agreement with the conditions occurring in natural uranium deposits, or in geological repositories. A new compound, Be[(UO2)(PO4)]2(H2O)2.5, has been synthesized at low temperature. This is the third Be-bearing uranyl phosphate reported to date, and its crystal structure is based upon sheets showing the uranophane anion topology, typical of uranyl silicates occurring in the oxidation zone of the uranium deposits. The well-known Ba[(UO2)3(MoO4)4(H2O)](H2O)3 and (NH4)2[(UO2)(MoO4)2](H2O) compounds have been synthesized, and new crystallographic data were collected on them. In addition, it was possible to determine the hydrogen-bonds networks for the first compound, and to redefine the Mo6+ coordination polyhedra in the second one. [less ▲]

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See detailDynamic Modeling of Organic Rankine Cycle Power Systems
Desideri, Adriano ULg

Doctoral thesis (2016)

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See detailL'Afrique centrale: entre traditions et transitions. La mutation des socio-écosystèmes en Afrique centrale
Gillet, Pauline ULg

Doctoral thesis (2016)

The forests of the Congo Basin are among the best preserved areas on Earth. Nevertheless, the factors causing deforestation around the world are also present in this subregion. The forest transition ... [more ▼]

The forests of the Congo Basin are among the best preserved areas on Earth. Nevertheless, the factors causing deforestation around the world are also present in this subregion. The forest transition theory describes how the trend of forest areas decline at national level may precede an increase in these areas. If the effects of the forest transition are well known in terms of forest cover degradation, little is known about the effects of forest transition on socio-ecosystems (SES) (understood as a group of actors with impacts on a group of resources and subject to specific institutions). The general objective of this thesis is to characterize the mutation of socio-ecosystems in the Congo Basin in order to identify dynamic of change of Congo Basin forested SES and their possible futures. The collection of socioeconomic data, focusing on the description of the population, the description of the different activities and incomes, the description of food intake and the access to land and resources, were conducted in three SES with a forest cover gradient, located in Cameroon and Gabon. The results show that the cost price of meals is globally increasing with the loss of forest cover. The share of food intake related to the exploitation of natural resources such as hunting, fishing and gathering decreases in favor of proteins from livestock and agricultural products. This leads to the translocation of demand but also to pressures on other anthropogenic ecosystems. The effects of deforestation are then visible at the local level but also on neighboring areas. The diversity of the game and prey decreases moving towards smaller species with the progression of the forest transition. Consequently, there is a reduction in the proportion of these products in both the food intake and household incomes. This analysis shows a decline in the importance of NTFPs in the production and villagers livelihoods. Slash and burn agriculture is practiced in three SES. If the ratio between fallow period and cultivation period decreases with the forest transition, there is an increase in crop diversification leading to a diversification of the diet. Access to forest resources, agricultural land, markets and an external source of employment condition the village activities. The land potential is made to report levels of ownership and co-management of customary space (Le Roy et al., 1996). During the progression of the forest transition curve, the land potential evolves from relatively loose to privatization and the ability to alienate resources. These important modifications of traditional control systems of the relations between man and resources lead to a more adequate management of some commercial resources value (such as agricultural products or mining resources). But, this process is incompatible with the maintenance of certain ecosystem services like large populations of wildlife preservation. If these results fit rather well with the forest transition curve, this is not the case of all SES in Central Africa. Therefore, we propose to combine some results to reflect significant changes of the qualities of a socio-ecosystem, regardless of forest cover rate. The priority would be to establish a standardized data collection protocol to test sites with different forest cover and located on different trajectories. The use of a socio-economic index would make it possible to predict the evolution of SES under different scenarios, whether linked to global or regional pressures (such as the emergence plans enacted by the Central African States) or in contexts of economic crisis or the introduction of new legislation. [less ▲]

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See detailEvaluation des impacts des projets de développement sur les exploitations agricoles familiales et les ménages de l’ATACORA (Nord-Ouest du Benin)
Tohinlo, Yecy ULg

Doctoral thesis (2016)

This doctoral research aims to contribute to a better understanding of the effects of development projects on the improvement of living conditions and livelihoods of rural households in Benin. It begins ... [more ▼]

This doctoral research aims to contribute to a better understanding of the effects of development projects on the improvement of living conditions and livelihoods of rural households in Benin. It begins with the analysis of development trends in Atacora known about the last three decades. It is focused on matching between the dynamics promoted by intervention devices and those endogenous or emerging to lead a part in the consideration of the productive trajectories and performance of family farms and also in the analysis of effects of development projects on food security, living standards and poverty of rural households. The post-development theories and the various conceptions of poverty have served as a guideline for research work. The intervention mechanisms conducted in Atacora (north-western Benin) by the various cooperations (bilateral and multilateral) between 1990 and 2010 constituted the research object of this thesis. The empirical phase took place in the communes of Cobly (West) and Péhunco (East). These communes were selected from their contrasting agro-ecological and socio-economic situations and socio-economic indicators on the one hand and on the other on a typology of the concentration of development projects and the perception of their effects by local people. A stratified sample of 344 households (respectively 214 in Cobly and 130 in Péunco) was formed for the characterization survey. Later, a thorough investigation on living conditions and livelihood of households followed and involved 208 households (129 Cobly; 79 Péhunco). Finally 16 case studies (8 per commune) were conducted on the trajectories of evolution and accumulation of property and wealth of households and farms. Due to the empirical research, special attention was given to primary data collection which lasted more than three (3) years. Qualitative and quantitative tools (including PSM) were combined for the analysis of collected data through individual and group interviews. Results show that the development interventions do not always promote the endogenous dynamics but they generate and maintain, in rural areas, pathways that allow the integration and participation of producers in the world market for agricultural products. And to benefit from various promotional activities, producers adopt supported crops, this have some positive and negative consequences. The integration and participation of rural producers of Atacora to international trade, promote the increase of production and crop yields while further increasing their dependence on the world prices of agricultural products. So while the income of producers is increasing their vulnerability to food insecurity is also increasing because many of the food crops, already insufficient (because of the share of the cotton planted and the cotton production quotas established by the government) to cover food needs, are substracted from consumption to be sold on the market to meet urgent liquidity needs. Thereby, Atacora's rural households, despite the increase of their food production, suffered a rupture of food stocks resulting to annual food crises of at least 4 months (16 weeks) which strikes indiscriminately both recipient households than non-project beneficiaries. However with the increase of sources and income level of recipient households (36% of households of the study sites), those beneficiaries improve their homes and food consumption and invest more in the education of their children. This marks a significant difference between beneficiaries and non-beneficiaries of development projects. Indeed, installed with the same resources, we counted, in 2014, twice more prosperous households and fewer poor among beneficiaries than non-beneficiaries. Furthermore farms and households beneficiaries of assistance have accumulated and hold more productive assets (land, farm equipment, livestock rearing), economic assets and holdines (transportation measures, housing, plots and houses to rent, etc.) than non-beneficiaries with a highly significant difference at 1%. However the level of improvements and living conditions induced by development interventions are still inadequate and insecure, as reduced to the equivalent adult,income as well as capital show no significant difference between beneficiaries and non-beneficiaries. Thus, households (even beneficiaries) remain vulnerable to crises so that any natural disaster (flood, drought, pest invasion, etc.), illness, injury and death of a member of the household, provokes the rapid degradation of living standards and the fall into poverty. This is compounded by the fact that farms owners’ don’t invest really in the restoration and enhancement of the capital '' land fertility ''; mainly in Cobly where the soil fertility level experienced a drastic decline with a consequent increasing use of chemical fertilizers that degrade the soil structure furthermore. It follows that any action aimed at poverty reduction should allow a sustainable improvement in conditions and livelihoods of rural producers by the preservation and restoration of soil fertility on the one hand and the increased resilience to crises on the other hand. Actions to identify specific needs with measures and solutions adapted to each category of producers and households with mainly particular mechanisms of management and restoration of the fertility of agricultural land shall be considered and implemented. [less ▲]

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See detailDevelopment and analysis of low-order models of frame structures under blast loads
Hamra, Lotfi ULg

Doctoral thesis (2016)

The main aim of this thesis is to propose an easy-to-apply tool to assess the level of damage of a structure in which one compartment is subjected to blast loading. This compartment is extracted from the ... [more ▼]

The main aim of this thesis is to propose an easy-to-apply tool to assess the level of damage of a structure in which one compartment is subjected to blast loading. This compartment is extracted from the structure accounting for the interaction with the part of the structure surrounding the loaded compartment, which is assumed to be elastic. Before studying the whole frame structure, the structural elements (i.e. the beam and its adjacent columns) are firstly studied separately taking into account the lateral restraint and mass offered by the indirectly affected part (IAP) of the structure. Secondly, the dynamic behaviour of a simple compartment made of pinned members and laterally braced is investigated. The material laws are assumed to be elastic-perfectly plastic, neglecting the effect of strain rate on the yield strength. The out-of-plane instabilities of the structural members are disregarded. • To explain the context of this study + final aim of this research Two analytical models are developed to predict the dynamic response of the frame beam subjected to blast loading, including the elastic lateral restraint and inertia offered by the IAP of the structure, the development of nonlinear membrane action (P-\delta effect) and also, the interaction between bending moment and axial force in the plastic hinges. The first model is based on a single degree of freedom (SDOF model) which is the transverse mid-span deflection of the beam while the second model is a two-degree-of-freedom (2-DOF) model which also includes the axial elongation of the beam. The accuracy of these two low-order models is assessed with finite element simulations. This validation stage shows that the proposed low-order models capture the physics of the problem in most cases of practical interest. A dimensional analysis of the problem reveals that, under the considered assumptions, four dimensionless parameters mainly influence the required ductility of the beam. Two of them are related to the behavior of the indirectly affected part (the lateral restraint and mass). Another one is related to the mechanical properties of the investigated beam (i.e. the ratio of the bending to axial resistance). The last parameter incorporates scales of the geometry and of the deformed configuration at the onset of the plastic mechanism. Concerning the columns, an analytical model is proposed to assess its dynamic response under constant axial compressive load and lateral blast loading. It accounts for large displacement (P-\delta effect), bending moment-axial force (M-N) plastic interaction as well as its interaction with the indirectly affected part (IAP) of the structure. This model is non-smooth piecewise linear and involves two degrees of freedoms (2 DOFs) in each regime of the motion of the column (related to the possibilities of development of plastic hinges). The dimensional analysis of the problem reveals that, under the considered assumptions, four dimensionless parameters mainly influence the dynamic stability of the beam-column. Two of them are related to the behavior of the indirectly affected part (the lateral restraint and mass). Another one is related to the critical load multiplier (i.e. the ratio of the axial compressive load to Euler elastic buckling resistance). The last parameter is the reduced slenderness of the beam-column. Subsequent to a parametric study, it is demonstrated that a good correlation is found between the results provided by the analytical model and a richer FEM model, despite some little discrepancies observed for some intermediate values of stiffness of the lateral restraint and lateral mass. As a possible improvement, adjustments to the analytical model are suggested. Finally, the dynamic behaviour of a simple frame under constant compressive loads and lateral blast loading is studied with a last 2-DOF analytical model. A multi-layer model of the cross-section of the beam is used to derive the bending moment-axial force (M-N) plastic interaction instead of the Lescouarc'h formula and normality rule. The coupling between the beam and the adjacent columns is ensured through appropriate boundary conditions. For the studied frame, two blast scenarios are contemplated, the first one corresponds to a quasi-static blast loading while the second one refers to a dynamic blast loading. The first case study shows that a very good agreement is achieved between the deflections predicted by the analytical and numerical models although a discrepancy is observed in the assessment of the axial force in the column due to the shape of the inertial force distribution of the beam assumed in the model. The second case study illustrates that, in both analytical and numerical models, the columns are predicted to fail by buckling due to the P-\delta effect although the axial force in the column is again inaccurately captured by the analytical model for the same reason. [less ▲]

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See detailCooperative spontaneous emission with quantized atomic motion
Damanet, François ULg

Doctoral thesis (2016)

In this thesis, we present investigations on the cooperative dynamics of (ultra)cold atoms coupled to the electromagnetic field in vacuum. The main objective is to identify the consequences of the ... [more ▼]

In this thesis, we present investigations on the cooperative dynamics of (ultra)cold atoms coupled to the electromagnetic field in vacuum. The main objective is to identify the consequences of the quantization of the atomic center-of-mass motion on the atoms-field dynamics, more particularly the atomic \emph{internal} dynamics including dipole-dipole interactions and cooperative spontaneous emission processes. For this purpose, we derive a Markovian master equation for the internal state of a collection of two-level atoms coupled to vacuum accounting for all effects related to the quantization of their motion. These effects depend on three characteristic lengths that can be tuned experimentally: the interatomic distance $r$, the wavelength $\lambda$ of the emitted radiation, and the typical size $\ell$ of the atomic wave packets. This leads to a rich panel of phenomena depending on the hierarchy between these characteristic lengths. Our master equation provides a unifying picture of the consequences of recoil and quantum statistics (bosonic or fermionic) on both the internal dissipative and conservative dynamics, and applies equally well to distinguishable and indistinguishable atoms. It is valid even beyond the Lamb-Dicke regime, i.e.\ for large recoil effects. We give general expressions for the decay rates and the dipole-dipole shifts entering the master equation for arbitrary motional states, and we find closed-form formulas for a number of relevant states (Gaussian states, harmonic oscillator eigenstates, Bose-Einstein condensates motional states). In particular, we show they can be strongly influenced by the motional state of the atoms, which suggests the possibility to quantum program their internal dynamics through motional state engineering. Based on the derived master equation, we investigate in full detail the super- and subradiance phenomena arising from a collection of indistinguishable atoms. Due to the symmetry (for bosons) or antisymmetry (for fermions) of the global state under exchange of atoms, the internal dynamics is restricted to the permutation invariant subspace whose dimension grows as $N^2$ with $N$ the number of atoms. In this particular case, the master equation involves only three rates: a single-atom decay rate $\gamma_0$, a cooperative decay rate $\gamma$ and a collective dipole-dipole shift $\Delta_\mathrm{dd}$. We solve the dynamics exactly for $2$ atoms, numerically for up to $30$ atoms, and obtain the large-$N$ limit by a mean-field approach. We show that a superradiant enhancement of the radiated intensity is always observed for a sufficiently large number of atoms. As regards subradiance, we show that exact decoherence free subspaces that protect against spontaneous emission through destructive interference of individual spontaneous emission amplitudes exist only in the limit of classically localized atoms, i.e.\ for atoms in infinitely steep traps. We assess the validity of our master equation in the optical domain through the study of the exact atoms-field dynamics. Among others, this complementary approach gives access to the vibrational state populations of the atoms after a photon emission and to the angular dependence of the emission spectrum. It also highlights the complex interplay between the atomic internal and motional states, such as the entanglement transfer that can occur during the collective decay of the atoms. Moreover, it opens the door for the study of the non-Markovianity of the internal dynamics. In conclusion, our thesis provides a comprehensive picture of the consequences of the quantization of the atomic motion on cooperative spontaneous emission processes and contributes to the development of theoretical tools for the study of the internal dynamics of (ultra)cold atoms. [less ▲]

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See detailSpace Thermal Analysis through Reduced Finite Element Modelling
Jacques, Lionel ULg

Doctoral thesis (2016)

The finite element method (FEM) is widely used in mechanical engineering, in particular for structure design. However, it is not often exploited for the thermal analysis of space structures for which the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, in particular for structure design. However, it is not often exploited for the thermal analysis of space structures for which the use of the lumped parameter method is still commonplace. To alleviate the computational burden of the FEM for thermal analyses involving conduction and radiation, an innovative global conductive-radiative reduction scheme based on the clustering of the finite element mesh is presented. The proposed method leads to a significant reduction of the number of radiative exchange factors (REFs) to compute and size of the corresponding matrix. It further keeps accurate conduction information by introducing the concept of physically meaningful super nodes associated to the clusters from which are derived the reduced conductive couplings. To complement the reduction of the number of faces, an improved Monte Carlo ray tracing algorithm is developed. It provides better accuracy and convergence rate than the classic Monte Carlo method. The algorithm is adapted to the partitioned FE mesh and includes quadrics fitting for accurate normal representation. The resulting conductive-radiative reduced model is solved using standard iterative techniques and the detailed mesh temperatures, recovered from the super nodes temperatures, can be directly exploited for thermo-mechanical analysis. The proposed global reduction method is validated on several space structures and is benchmarked against ESATAN-TMS, the standard thermal analysis software used in the European aerospace industry. [less ▲]

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See detailL'art de gouverner les déchets hautement radioactifs. Analyse comparée de la Belgique, la France et le Canada
Parotte, Céline ULg

Doctoral thesis (2016)

Comment l'art de gouverner les déchets hautement radioactifs, tel qu'il a évolué au cours des deux dernières décennies, a-t-il redéfini les enjeux sociotechniques du programme de gestion des déchets ... [more ▼]

Comment l'art de gouverner les déchets hautement radioactifs, tel qu'il a évolué au cours des deux dernières décennies, a-t-il redéfini les enjeux sociotechniques du programme de gestion des déchets hautement radioactifs et réciproquement? Telle est la question qui traverse cette thèse. Combinant l'analytique de gouvernement (Dean 2010) à une approche co-productionniste forte (Joly 2015), trois régimes de pratiques de gouvernement, en France, en Belgique et au Canada sont scrutés et comparés. Cet écrit propose de suivre l'objet, en cinq chapitres, depuis sa définition (au travers des systèmes de classification), en passant par l’élaboration, la mise en oeuvre territoriale et l'évaluation régulière de son programme de gestion. Chemin faisant, nous cherchons à comprendre comment le dépôt géologique est resté l’option de référence clef pour la catégorie "déchet hautement radioactif". Différentes co-productions seront mises à jour révélant l'asymétrie de pouvoir entre les acteurs, la trajectoire (dis)continue du programme et le caractère expérimental de l’art de gouverner les déchets hautement radioactifs. Un art expérimental, dont nous soutenons que les formes peuvent varier, entre autres, selon l'attitude des expérimentateurs. [less ▲]

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See detailApplication des biotechnologies post-récolte pour la valorisation des produits de terroirs marocains par des microorganismes sélectionnés impliqués dans la fermentation de fruits : cas du vinaigre
Mounir, Majid ULg

Doctoral thesis (2016)

Dans cette étude, de nouvelles souches microbiennes (levures et bactéries acétiques) ont été isolées, sélectionnées, identifiées et caractérisées pour évaluer leur usage comme starters pour la production ... [more ▼]

Dans cette étude, de nouvelles souches microbiennes (levures et bactéries acétiques) ont été isolées, sélectionnées, identifiées et caractérisées pour évaluer leur usage comme starters pour la production industrielle de vinaigre de fruits. Dans un premier temps, la levure Saccharomyces cerevisiae YS-DN1 a été isolée à partir de dattes locales et étudiée pour ces pouvoirs de fermentation des sucres et de résistance aux différents facteurs de stress (éthanolique, thermique et osmotique). Cette souche s’est distinguée comme étant la plus performante dans la production d’éthanol en comparaison à deux autres souches industrielles de référence. En effet, YS-DN1 était la seule souche capable de se développer à une température entre 35 et 40°C en présence d’un taux alcoolique élevé (>8% éthanol) et une pression osmotique agressive (>18 °Brix). Dans un deuxième temps, deux souches de bactéries acétiques CV01 et AF01, identifiées par des techniques moléculaires comme étant affiliées à l’espèce Acetobacter pasteurianus, ont été isolées respectivement de cactus et de pommes. A l’issue des caractérisations physiologiques et des cinétiques de fermentation réalisées en erlens et en bioréacteurs (6 L, 20 L et 500 L), ces deux souches ont montré des pouvoirs de thermotolérance et d’acétification notables. L’étude enzymatique réalisée sur les enzymes membranaires ADH et ALDH formant le complexe enzymatique impliqué dans le processus d’oxydation de l’éthanol a révélé que, contrairement aux souches de référence, ces enzymes maintiennent une activité normale à haute température (38°C). L’étude cinétique en bioréacteur 20 L a montré que la souche CV01 était moins sensible à la variation de la composition du milieu de fermentation et a pu produire plus d’acide acétique (10 g/L) que la souche AF01. Durant le même cycle de fermentation, la souche CV01 était notablement la seule souche capable d’orienter son mécanisme métabolique pour la production de l’acide gluconique simultanément avec l’acide acétique. Par ailleurs, la méthode des surfaces de réponse (RSM) a été utilisée pour l’optimisation de la production en biomasse de la souche CV01. Les valeurs optimales des facteurs influents, à savoir l’éthanol, l’acide acétique, le glucose et le pH, permettant d’obtenir le maximum de biomasse cellulaire (2.21 g/L) étaient de 28.18 g/L, 10.12 g/L, 15.15 g/L et 5.33, respectivement. Dans une troisième partie, la souche A. pasteurianus CV01 a été évaluée pour sa capacité à résister aux conditions de stress thermique en bioréacteur. Les résultats obtenus montrent une habilité de cette souche à contrecarrer l’augmentation excessive de température (>35°C) au cours d’un cycle de fermentation sans refroidissement. En outre, un protocole de démarrage de fermentation en mode semi-continu a été proposé et adopté pour la production de vinaigre de fruits en bioréacteur 500 L. La caractérisation aromatique du vinaigre de pomme produit à l’échelle pilote moyennant la technique de l’espace de tête – microextraction en phase solide (HS-SPME) – a permis d’identifier dans la composition de son arôme des molécules associées à des descripteurs généralement appréciés . Ces souches, caractérisées pour leur thermotolérance notable, pourront être utilisées comme starters pour la production à grande échelle de vinaigre de fruits. [less ▲]

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See detailActive Network Management for Electrical Distribution Systems
Gemine, Quentin ULg

Doctoral thesis (2016)

With the increasing share of renewable and distributed generation in electrical distribution systems, Active Network Management (ANM) has become a valuable option for a distribution system operator to ... [more ▼]

With the increasing share of renewable and distributed generation in electrical distribution systems, Active Network Management (ANM) has become a valuable option for a distribution system operator to operate his system in a secure and cost-effective way without relying solely on network reinforcement. ANM strategies are short-term policies that control the power injected by generators and/or taken off by loads in order to avoid congestion or voltage issues. While simple ANM strategies consist of curtailing temporary excess generation, more advanced strategies instead attempt to move the consumption of loads to anticipated periods of high renewable generation. Such advanced strategies mean that the system operator has to solve large-scale optimal sequential decision-making problems under uncertainty. The problems are sequential for several reasons. For example, decisions taken at a given moment constrain the future decisions that can be taken, and decisions should be communicated to the system’s actors sufficiently in advance to give them enough time for implementation. Uncertainty must be explicitly accounted for because neither demand nor generation can be accurately forecasted. This dissertation presents various research contributions about ANM for distribution systems. These contributions range from the motivation of using a framework of sequential decision-making under uncertainty to the study of computational methods that implement ANM strategies. A particular emphasis is placed on the formulation of the problem, which ultimately falls within the class of Markov decision processes. The modeling of stochasticity is explored and a novel approach that relies on a Gaussian Mixture Model is presented. Computational methods including several relaxations and approximations of multi-period and multi-scenario extensions of the optimal power flow problem with discrete decision variables were considered. [less ▲]

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See detailEtude de la régulation de l'expression de l'opéron ftsW-psr-pbp5 chez Enterococcus hirae
Maréchal, Maxime ULg

Doctoral thesis (2016)

Les entérocoques sont des microorganismes commensaux du tractus digestif de la plupart des animaux mais sont également des pathogènes opportunistes. Lorsque les entérocoques sont associés à une infection ... [more ▼]

Les entérocoques sont des microorganismes commensaux du tractus digestif de la plupart des animaux mais sont également des pathogènes opportunistes. Lorsque les entérocoques sont associés à une infection, la sélection d’un traitement antibiotique adéquat peut s’avérer difficile. Cela est dû à la résistance, intrinsèque ou acquise, des entérocoques à de nombreux antibiotiques. Dans ce travail, nous nous sommes intéressés à leur résistance intrinsèque aux β-lactamines. Un des mécanismes de résistance envers ces antibiotiques est la production d’un PBP de faible affinité. Cependant, le facteur responsable de la surproduction de cette protéine chez les souches présentant un niveau de résistance plus élevé n’est pas encore connu. Ce travail avait pour objectif principal de contribuer à une meilleure compréhension du mécanisme moléculaire responsable de la résistance aux β-lactamines et d’établir le rôle de l’opéron ftsWpsr-pbp5 chez Enterococcus hirae. La première partie de ce travail a été focalisée sur les protéines codées par les gènes ftsW, psr et pbp5. La publication du premier génome d’E. hirae ATCC9790 nous a permis d’identifier et situer dans le génome d’autres gènes codant pour des protéines de la même famille (SEDS pour FtsW, LCP pour Psr, et les autres PBPs pour PBP5). Nous avons produit et purifié ces différentes protéines avec pour visée principale la possibilité d’obtenir des anticorps spécifiques pouvant servir à localiser les protéines au sein de la cellule d’E. hirae. Nous avons établi que la protéine Psr lie le peptidoglycane, se localise avec PBP5 au niveau du site de division et possède des caractéristiques en accord avec une fonction similaire à celle proposée pour d’autres protéines LCP. La seconde partie du travail était axée sur la sélection et l’étude de nouveaux mutants hyperrésistants aux β-lactamines. L’analyse de leur physiologie, de l’expression du PBP5 et de l’environnement génétique du gène pbp5 chez chacun d’eux a été réalisée. Le séquençage du génome de deux mutants a été effectué afin de pouvoir identifier les mutations présentes permettant leur résistance. Des analyses de la force promotrice des séquences en amont de chaque gène de l’opéron ftsW-psr-pbp5 d’E. hirae ont été menées en utilisant le gène rapporteur de la luciférase de luciole. Ces expériences et les mutations observées chez les mutants, nous ont permis d’identifier des éléments régulateurs qui ont une influence sur l’expression de l’opéron ftsW-psr-pbp5. [less ▲]

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See detailDevelopment of a new design method to define the rotation capacity of steel hollow sections
Saloumi, Elsy ULg

Doctoral thesis (2016)

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by ... [more ▼]

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by defining a new and accurate proposition to characterise the rotation capacity Rcap of sections, which could be associated with the rotation demand of a structure Rdem. Therefore, the purpose of this thesis is to establish a direct dependence of the rotation capacity Rcap with a newly defined cross-section slenderness CS. Hence, current design standards disregard the rotation demand of the structure and allow plastic analysis based on a plate slenderness limit. To achieve this purpose, an experimental campaign was performed consisting in 23 bending tests on square and rectangular hollow sections tested in bending, in addition to 8 stub columns. Then, a numerical model based on the finite element software FINELg was calibrated to well represent these experimental tests, as well as cold-formed bending tests from literature. Based on these results, a good agreement between experimental and numerical results was shown and the numerical software was therefore validated. Accordingly, since the numerical software was proved to well represent the bending behaviour of hollow beams, around 8000 finite element simulations were performed while varying sections dimensions, material properties and loading configuration. These results reported that actual standards limitations were inappropriate, and stricter values were proposed. Moreover, based on the numerical computations, a continuous curve capable of describing the rotation capacity of sections as a function of the cross-section slenderness was proposed. The production route, loading application and yield strength were identified as key parameters having a major impact on the rotation capacity of sections. Consequently, different curves were proposed for each parameter; based on these curves, the rotation capacity of the section could be compared to the rotation demand of a structure in order to obtain a practical, safe, and reliable design calculation. [less ▲]

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See detailDevelopment of a new design method for steel hollow section members resistance
Hayeck, Marielle ULg

Doctoral thesis (2016)

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the ... [more ▼]

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the “Overall Interaction Concept” (O.I.C.). The proposed approach makes use of the interaction between the two ideal behaviours of structural members (resistance and instability) and includes the influence of initial imperfections (out-of straightness, residual stresses, non-homogenous material), to calculate the resistance of a structure through a single parameter: “relative slenderness”. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to determine the experimental behaviour of beam-columns loaded by bi-axial bending with axial force. Twelve buckling tests, consisting of hot-rolled and cold-formed rectangular and circular hollow section members were conducted. These tests were accompanied by preliminary measurements of cross-section geometry, material properties, geometrical imperfections, residual stresses as well as stub column tests. Besides, a finite element model was calibrated on the basis of these tests. For both the present test series and another one from the literature, it was shown that the FE models were capable of replicating accurately the response and resistance of the experiments. Accordingly, the validated FE models have been further used in extensive numerical studies, and a database comprising more than seventy thousand results was built consecutively. Based on these computations, design proposals were made, by considering identified governing parameters, within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a safely evaluation was completed to check the proposed formulae against the results of current Eurocode 3 rules. [less ▲]

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See detailContribution to the study of the effect of drying on the nutritive value of corn grain (Zea mays L.) for poultry and pigs feeding
Odjo, Djosse Psijus Sylvanus ULg

Doctoral thesis (2016)

Corn grain (Zea mays L.) is widely produced all over the world and is intensively used in poultry and pigs feeding. Drying with hot air is usually utilized to preserve corn after harvest by decreasing the ... [more ▼]

Corn grain (Zea mays L.) is widely produced all over the world and is intensively used in poultry and pigs feeding. Drying with hot air is usually utilized to preserve corn after harvest by decreasing the water content. During high temperature drying, major components (starch and proteins) of corn grain undergo some structural changes with possible nutritional implication. This thesis aimed at increasing knowledge regarding the effect of the drying process on the feeding value of the corn grain for broilers and pigs feeding. After the general introduction and a review which attempts to summarize the major findings of previous studies carried out on the effects of drying on the nutritive value of corn for broilers feeding, the first in vitro experiment performed aimed to assess the effect of fluidized-bed drying on the digestibility of dry matter, starch and protein using a sequential pepsin-pancreatin protocol. It appeared that when corn grains harvested at similar moisture content are dried at different temperatures, the digestibility of starch and that of crude proteins are not affected in a similar way. Higher drying temperatures increased the final digestibility of starch while the digestibility of crude proteins decreased mainly during the pepsin step of digestion. Differences in the kinetics of starch digestion according to the corn grain temperature were attributed to the structural modifications induced within starch granules and proteins in response to the drying conditions. As the digestion of starch involves the breakdown of glycosidic bonds and results in the production of various oligosaccharides, a second experiment was performed in order to get more insight into the nature of saccharides released after the in vitro digestion of corn grains. Three methods were thus compared in their ability to provide relevant information about sugar saccharides released during an in vitro digestion procedure that mimics the pig digestive model. High Performance Anion Exchange Chromatography coupled with a Pulsed Amperometric Detector was revealed to give the most effective qualitative and quantitative information regarding the digestion of starch. Five major saccharides were found as the result of in vitro pepsin-pancreatin digestion of corn grain: glucose, isomaltose, maltose, maltotriose and glucosyl-maltotriose. The relative concentration of these saccharides varied according to the temperature applied during the corn drying, suggesting that structural changes occurring within starch granules (partial gelatinization) would lead to different digestion profiles in the small intestine and may therefore affect the nutritional physiology in pig intestinal tract. Protein is also affected by the high drying temperature. Among corn protein subgroups, salt-soluble proteins are the most sensitive to heat and their solubility decreases when the drying temperature increases. In a third experiment, the denaturation of salt-soluble proteins during corn drying and hydrothermal treatment was monitored and modelled. The impairment of corn protein solubility in saline buffer was revealed to depend mainly on temperature, time of processing and moisture content of materials treated. The evolution of extractible salt-soluble proteins content of corn kernels during drying at high temperature was more correctly described using the second order kinetic reaction than with the first order kinetic reaction when classical kinetic models were compared. In a forth study the relationship between the in vitro digestibility of dry matter and the salt-soluble protein index was assessed. It was found that the use of salt-soluble protein index as an indicator of the may lead to doubtful conclusion due to confounding factors (temperature and moisture content). Although this study has achieved some progress in understanding the possible link between corn drying parameters and their effects on the performance of poultry and pigs feeding using corn-based diets, as well as on methodologies that may be used to assess the nutritive value of dried corn grains, complementary studies aiming to determine the effectiveness of these effects on livestock and pigs have to be done. [less ▲]

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See detailCarbon dioxide and vegetable oil for the synthesis of biobased polymer precursors
Alves, Margot ULg

Doctoral thesis (2016)

Although it is a thermodynamically and kinetically stable molecule, carbon dioxide can be converted into five- and six-membered cyclic carbonates by coupling with epoxides or oxetanes, respectively, using ... [more ▼]

Although it is a thermodynamically and kinetically stable molecule, carbon dioxide can be converted into five- and six-membered cyclic carbonates by coupling with epoxides or oxetanes, respectively, using appropriate catalysts. Cyclic carbonates are used as green solvents, electrolytes for Li-ion batteries or intermediates for the synthesis of polymers. However, the catalytic performance must be further enhanced in particular for the coupling of CO2 with epoxidized vegetable oils or oxetanes. In this context, we developed a new highly efficient bicomponent homogeneous organocatalyst composed of an ammonium salt as the catalyst and fluorinated single or double hydrogen bond donors as co-catalysts. First, a screening of onium-based catalysts and hydrogen-bond donors was performed. Performances of the catalysts and optimization of the reaction was realized through detailed kinetics studies using in-situ FTIR/Raman spectroscopy under pressure. We demonstrated that fluorinated alcohols showed unexpected co-catalytic activity due to synergisms between the onium salt and fluorinated co-catalysts enabling the fast and selective addition of CO2 onto model epoxides and epoxidized vegetable oils under solvent-free and mild experimental conditions. The use of this powerful dual catalyst was then extended to the first organocatalytic coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonates that were used as precursor of CO2-based polyurethanes by chain-extension with a diisocyanate. In addition, a fine comprehension of the mechanisms was investigated by DFT calculations highlighting that the co-catalytic performance of the onium salt/fluorinated alcohol binary catalyst arose from the strong stabilization of the intermediates and transitions states by hydrogen-bonding. To date, through comparative studies, we evidenced that this new catalyst is one of the most performing and versatile system enabling the coupling of CO2 both with epoxides or oxetanes. [less ▲]

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See detailLe théorème fondamental comme pierre de touche de l'enseignement et de l'apprentissage de l'analyse au secondaire
Balhan, Kevin ULg

Doctoral thesis (2016)

Using the Anthropological Theory of Didactics and the Theory of Didactic Situations, this thesis brings an answer to several questions of learning the fundamental theorem of the analysis and shows that ... [more ▼]

Using the Anthropological Theory of Didactics and the Theory of Didactic Situations, this thesis brings an answer to several questions of learning the fundamental theorem of the analysis and shows that what prevents to understand it is significant of dysfunctions of the teaching of the analysis at the secondary level in French-speaking Belgium. [less ▲]

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See detailStudying the genetics of Mendelian and complex traits with high-throughput genotyping and sequencing in cattle
Li, Wanbo ULg

Doctoral thesis (2016)

Background For decades, identifying genes and mutations underlying inherited diseases and economically import traits has been at the core of genetic studies in domestic animals. The initial arduous task ... [more ▼]

Background For decades, identifying genes and mutations underlying inherited diseases and economically import traits has been at the core of genetic studies in domestic animals. The initial arduous task of gene mapping with microsatellites or low-density SNP panels was then followed by a often fruitless and tedious attempt to isolate the causative mutations for both monogenic and polygenic traits. The availability of high-density SNP arrays considerably accelerated the gene mapping process. More recently, advances in second-generation high-throughput sequencing (HTS) including whole genome, exome, and RNA sequencing have brought tremendous efficiency into dissecting the genetic underpinnings of phenotypes of interest. In this thesis, we describe the use of these new technologies to decipher the genetic basis of several monogenic and polygenic traits, in both forward and reverse genetic settings. Results We first describe the use of medium-density SNP arrays to dissect genetic basis of a monogenic disease (Crooked Tail Syndrome, CTS), as well as of complex phenotypes related to meiotic recombination in cattle. With regards to CTS, we first demonstrate that a common 2bp-deletion in the MRC2 gene causes the condition in Belgian Blue cattle (BBC), and that the frequency of the condition is due to a pleiotropic effect of the mutation on muscle mass. We discover a second loss-of-function mutation in the same gene MRC2, supporting the hypothesis of pleiotropy and balancing selection. With regards to recombination, we report that genetic variants in REC8 and RNF212 affect the genome-wide recombination rate in cattle. The RNF212 gene has also been shown to be associated with genome-wide recombination rate in humans, however REC8 is not supported as a candidate gene by newer data. We also demonstrated that several variants in the zinc-finger domain of a gonosomal PRDM9 paralogue influence hotspot usage in cattle, reminiscent of previous findings in human and mice. The subsequent application of HTS technology in forward genetic analyses, allowed us to identify: i) an intronic mutation in the PIGH gene that causes the skipping of exon 2, and is the cause of arthrogryposis in BBC, ii) a 3.3 kb deletion removing exons 25-27 of the FANCI gene, that causes brachyspina in Holstein-Friesian cattle. We finally used a reverse genetic approach to identify embryonic lethal (EL) mutations compromising fertility in beef (BBC) and dairy cattle (Holstein-Friesian and Jersey). We mined whole genome and exome sequence data from more than 500 animals for candidate embryonic lethal variants corresponding to loss-of-function (stop gain, frameshift and splice site variants) and disruptive missense variants. By doing so we demonstrate that against expectations domestic Bos taurus cattle are genetically more variable than humans including Africans, however, that their burden of disruptive variants is similar, amounting to ∼100 such variants per individual. We interpret this as resulting from more effective purifying selection in recent times as a result of increased inbreeding. We have genotyped thousands of animals for thousands of EL candidates, and estimate – from the observed depletion in homozygotes - that no more ∼15% of those are developmentally essential. We do not find evidence for synthetic epistasis between candidate EL mutations. By evaluating the departure from Mendelian expectations in matings between carrier sires and dams, we unambiguously demonstrate the embryonic lethal nature of nine relatively common candidate EL variants. All of them affect genes that are involved in basic cellular processes. We demonstrate that only one of these would have been detected using the haplotype-based approach that were applied thus far. The established list of loss-of-function variants is being mined for putative non-lethal, yet major phenotypic effects of medical relevance. Among these, we uncovered a 10-bp deletion in the MLPH gene, which results a premature stop codon, that causes diluted color – ‘cool gray’ – in BBC. Conclusions and Perspectives Due to the intensive use of some elite sires by means of artificial insemination in cattle, several outbursts of genetic defects have been observed in recent years. We herein demonstrate that uncovering the genetic basis of such Mendelian disorders can be very effective when integrating high-throughput genotyping and sequencing technology. Fertility in cattle and other domestic animals has declined over the last decades. Our discovery of a number of embryonic lethal variants segregating in cattle provide a complementary explanation for the decline in fertility, in addition to the theory of negative energy balance of high producing cows. The reverse genetic approach we developed for screening EL variants has at least two advantages. First, our approach also works in small sized populations. Second, our approach has higher sensitivity than the haplotype-based approach. It has been suspected for some time that most of the variants underlying complex traits map to noncoding regions. Deciphering the functional consequence of these regulatory variants has proven challenging. The ENCODE projects in human and mice provide good examples of how high-throughput functional assays based on NGS technology may enhance our knowledge of the non-coding regions of the genome. It is reasonable to anticipate that the release of ENCODE-like data in the animal research field will assist in the discovery of the genetic basis of complex traits at an unprecedented pace. [less ▲]

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See detailEtude des intermattes des herbiers à Posidonia oceanica
Abadie, Arnaud ULg

Doctoral thesis (2016)

Among Mediterranean marine ecosystems, Posidonia oceanica (L.) Delile seagrass meadows form a habitat playing an important ecological and economical role. They form heterogeneous seascapes influenced by ... [more ▼]

Among Mediterranean marine ecosystems, Posidonia oceanica (L.) Delile seagrass meadows form a habitat playing an important ecological and economical role. They form heterogeneous seascapes influenced by the impact of natural and anthropogenic phenomenon (of which the anchoring of leisure ships). These impacts lead to the formation of sand and bare mat patches called ‘intermattes’. By describing and using intermatte characteristics observed in Calvi Bay and more widely around Corsica, these PhD works precisely described intermatte and P. oceanica seascape dynamics in order to develop new methods of analysis. On the one hand, natural sandy intermattes formed by bottom currents show two types of border. Each has its own characteristics at the level of the sediments biogeochemistry. On the other hand, anthropogenic intermattes generated by anchoring (bare mat) present different sizes and shapes resulting from specific dynamics. They are not recolonized when the anchoring pressure remains high. A depletion of the substrate chemical quality occurs after the mechanical destruction. A new cartographic seascape index, the Patchiness Source Index, was created using the size and the nature of intermattes at large spatial scale. After a comparison of methods used for the study of intermattes, two new indices (Map Anchoring Index and Anchoring Index) for managers of coastal areas were developed to evaluate the impact of anchoring within P. oceanica meadows. [less ▲]

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See detailSleep and Electroencephalography, Preprocessing and analyses of a specific sleep EEG pattern
Coppieters't Wallant, Dorothe ULg

Doctoral thesis (2016)

Preprocessing and analyses of a specific sleep EEG pattern. Automatic detection methods, self-adjustable to individuals characteristics, were developed in order to remove artefacts from EEG sleep ... [more ▼]

Preprocessing and analyses of a specific sleep EEG pattern. Automatic detection methods, self-adjustable to individuals characteristics, were developed in order to remove artefacts from EEG sleep recordings, detect sleep spindles and analyse NREM power spectrum. Methods are described, assessed and discussed. [less ▲]

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See detailProcessus écologiques et évolutifs impliqués dans le succès de l’introduction de Quercus rubra L. en Europe
Merceron, Nastasia ULg

Doctoral thesis (2016)

Le chêne rouge d’Amérique (Quercus rubra L.) est un arbre originaire d’Amérique du Nord et introduit en Europe à partir de la fin du XVIIème siècle pour l’ornementation et le commerce du bois. Le but de ... [more ▼]

Le chêne rouge d’Amérique (Quercus rubra L.) est un arbre originaire d’Amérique du Nord et introduit en Europe à partir de la fin du XVIIème siècle pour l’ornementation et le commerce du bois. Le but de cette thèse est de comprendre les mécanismes écologiques et évolutifs qui contribuent à la dynamique et au succès de l’introduction de Q. rubra en Europe. Nous avons montré que cette espèce naturalisée et plantée dans certains pays européens parvient aisément à se développer de façon naturelle dans les forêts de feuillus et de conifères. La dispersion de ses glands est notamment rendue possible par des animaux fouisseurs-disperseurs, tels que les écureuils et les mulots, qui cependant préfèrent les glands du chêne natif Q. robur. Lors de l’introduction d’une espèce dans un nouvel environnement, des processus évolutifs sont susceptibles de se produire et d’engendrer des modifications phénotypiques et génétiques au sein des populations introduites. Une analyse comparative de la structure et de la diversité génétique des populations natives et introduites de Q. rubra a démontré que seulement deux des trois groupes génétiques de l’aire américaine sont actuellement présents en Europe. Aucun goulot d’étranglement fort n’a été détecté lors de l’introduction des populations en Europe laissant supposer que des introductions multiples ont pu maintenir la diversité génétique dans les populations introduites. Une analyse comparative des traits phénotypiques a permis de montrer que les populations introduites de Q. rubra présentent une croissance supérieure par rapport aux populations natives. Une différenciation génétique au sein des populations introduites est en cours pour le trait de débourrement foliaire suggérant une possible évolution adaptative rapide depuis l’introduction. [less ▲]

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See detailContribution to the Characterization of Piston Expanders for Their Use in Small-scale Power Production Systems
Oudkerk, Jean-François ULg

Doctoral thesis (2016)

Piston expanders are well suited for small scale power generation (<50kW) using heat engines such as Ericsson engine or Organic Rankine Cycle (ORC) system. Both systems offer the possibility to use ... [more ▼]

Piston expanders are well suited for small scale power generation (<50kW) using heat engines such as Ericsson engine or Organic Rankine Cycle (ORC) system. Both systems offer the possibility to use renewable energy sources and are increasingly considered in light of the economic and environmental context. This thesis aims at contributing to the knowledge and the development of piston expanders by presenting modeling, simulation and experimental investigations. Two types of piston engine models are proposed. The first type (denoted as “detailed”) describes the shaft angle (or time) evolution of the state of the fluid in the control volume limited by the cylinder wall and the piston. The second type of model (denoted as “semi-empirical”) is based on theoretical indicator diagram. A calibration process is proposed and applied with the measurement collected on two different expanders. The detailed model is first used to simulate an Ericsson engine. The simulations allow for the optimization of the pressure ratio, the determination of the ratio between the swept volumes of the expander and the compressor, the computation of the valve timing and the evaluation of the potential performances. The main modifications made to turn an available Internal Combustion Engine (ICE) into an Ericsson engine are described. This prototype is then tested but did not run as expected. The identified reasons are a too high leakage rate, a too large cut-off ratio and a too low expander supply temperature. These three features led to insufficient pressure. Nevertheless, a compressor is used to rise the pressure up to 7 bar in order to test the expander part. This expander shows a maximal isentropic efficiency of 59% at 600 RPM with a pressure ratio of 5. A swash-plate expander integrated into an ORC using R245fa is also investigated in a wide range of operating conditions. Performance maps in terms of pressure ratio and rotational speed are given. Maximal reached isentropic efficiency is 54% at 2500 RPM for a pressure ratio of 10.5. Experimental results obtained on both expanders are analyzed with the same methodology to assess the importance of each source of losses. This methodology is based on the disaggregation of the isentropic efficiency into different factors. Each of these factors represents one source of losses. In-cylinder pressure measurements are performed in order to measure mechanical losses. Leakage effects are simulated with the detailed model. Finally, an Ericsson engine-based m-CHP unit and an ORC-based m-CHP unit using the swash-plate expander are simulated with the validated semi-empirical model. Ericsson engine system shows a 6.5% electrical efficiency while the ORC system shows en efficiency of 8.2%. For both systems, possible improvements are simulated. It is shown, among other things, that the benefit of an increase of the built-in volume is limited by the decrease of the mechanical efficiency. [less ▲]

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See detailAssessment of fodder biomass in Senegalese rangelands using earth observation and field data
Diouf, Abdoul Aziz ULg

Doctoral thesis (2016)

Senegalese livestock size has largely increased during the last three decades in relation to the population growth. The fodder biomass stock available at the end of the growing season, therefore, becomes ... [more ▼]

Senegalese livestock size has largely increased during the last three decades in relation to the population growth. The fodder biomass stock available at the end of the growing season, therefore, becomes increasingly limited to meet feeding needs of pastoral livestock which provides third of the national agricultural wealth. With the reduction of natural grazing lands mostly generated by the expansion of croplands, and the reduction of fodder biomass production due to drought effects, the increase of the livestock size leads to the rangelands overload whose persistence can lead in turn to their degradation. A technique based on a simple linear relationship between the temporal integration of the Normalized Difference Vegetation Index (NDVI) and the ground biomass data, developed in the 1980s, has been operationally applied by the Centre de Suivi Ecologique (CSE) of Dakar (Senegal) to assess the fodder biomass available in rangelands at the end of the growing season. The derived map of total biomass production enables to help pastoral livestock managers as well as national stakeholders against food insecurity and natural resources degradation. Carried out annually, this approach comprises unfortunately some uncertainties as: (1) the saturation drawback of NDVI in areas with high biomass productivity, (2) the temporal scale which is restricted to biomass data of the ongoing year not being used again in the following year, (3) the low predictive ability due to the large time gap between data collection and published results, and (4) the high costs for annual data collection. In addition, although the earth observation (EO) data have largely progressed during the last three decades, this technique has not changed over this period and consequently is not state-of-the-art. To tackle these limitations and advance the traditional method, new statistical models that include new earth observations datasets and historical in situ plant biomass data were developed for estimating and / or predicting the forage availability at the end of the growing season in Senegalese semi-arid rangelands. A backward analysis of the linear regression approach currently applied in Senegal provided evidence that nonlinear regression functions such as Exponential and Power are more suited to estimate the end-of-season total biomass in this region using annual data solely. A completely new methodology using multiple-linear models which include various phenological metrics from the time series of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and 14 years of in situ total biomass samples was developed. The proposed approach provided more reliable and accurate estimates as compared to the current CSE biomass product. Multiple-linear models developed with specific metrics adapted to ecosystem properties increased the overall accuracy of the fodder biomass estimates and mitigated the saturation of FAPAR obtained with models run across the whole study area. With this new approach, timely information about possible deficits/surplus of total fodder biomass can be provided to stakeholders using phenological metrics that are available relatively early in the growing season. Another new approach based on a machine learning algorithm (i.e., Cubist) was developed, as never done before, to assess herbaceous biomass in Senegalese Sahel. Three Cubist models using FAPAR seasonal metrics and/or agrometeorological variables (i.e., soil water status indicators) were established and compared. The Cubist model including both FAPAR and agrometeorological variables provided the best estimation performance. This model enabled to mitigate the saturation affecting optical remotely sensed vegetation data in areas of high plant productivity as well as the discrepancy between herbaceous biomass and greenness, and corrected therefore for herbaceous biomass underestimations observed with the sole FAPAR based model, particularly in sparsely vegetated areas. In contrast to the date of the growing season onset retrieved from FAPAR seasonal dynamics, the rainy season onset was significantly related to the herbaceous biomass and its inclusion in models could constitute a significant improvement in forecasting risks of fodder biomass deficit. The methods developed in this research provide tools to assess Senegalese forage resources at two levels: herbaceous and total fodder biomass (Herbaceous + woody leaf biomass). They require limited data and free available software and therefore can be easily replicated in other countries of the West African Sahel. [less ▲]

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See detailDECONSTRUCTING LANDSCAPE IN THE MIND OF PEOPLE: AN EXPLORATION OF EVERYDAY AND WIND ENERGY LANDSCAPES
Vanderheyden, Vincent ULg

Doctoral thesis (2016)

In the 19th century, geography was defining itself as the science of landscape, led by German and French schools. Other disciplines were also interested in landscape, each one with its own definition(s ... [more ▼]

In the 19th century, geography was defining itself as the science of landscape, led by German and French schools. Other disciplines were also interested in landscape, each one with its own definition(s). In public policy, landscape has remained, for a long time, a heritage object to be protected (e.g. cultural landscapes of UNESCO). In 2000, the European Landscape Convention, which aims to safeguard the European landscape diversity, proposed a common definition. This includes the idea of areas perceived by people. One of the recommendations of the Convention is the call to focus on other landscapes that only heritage landscapes, such as everyday landscapes and degraded landscapes. The convention also calls for better management and planning practices towards landscape changes. Today, landscape is often invoked as arbitrator in territorial disputes. This is the case in discussions for the installation of wind farms. Newcomers and farmers ‘visions on landscape are often opposed: idyllic landscape for living and recreation for the firsts, working environment for the seconds. Despite the European Landscape Convention, many grey areas remain about how to achieve its goals. Long before it, leading researchers called for a better interest in everyday landscapes. Yet they remain the poor relation in landscape research, to the benefit of natural, wild landscapes. Many uncertainties also remain on how non-specialists perceive their ordinary landscapes and how they have appropriated the landscape concept. The research helps to fill this double gap, deconstructing the concept through the lens of ordinary landscape. With several research questions, I plan to explore what is the landscape in people’s mind, how they conceptualize it, how they think it and how they question their own views on landscape. I will show how these conceptualizations and thoughts are shaped by the living environment, which often provides the tools necessary to the apprehension of the landscape. I will analyse how new elements such as wind farm can disrupt these patterns. The first part of the research is dedicated to the overall perception of their ordinary landscapes by Belgians, especially facing the issue of wind energy. Using a photo-questionnaire survey, we surveyed a representative sample of the Belgian population (n = 1542). Based on this investigation a model was developed. It highlights the positive influence of forest cover and the lack of anthropogenic elements, but also the negative influence of its urbanization and too flat relief on landscape attractiveness. The influence of wind turbines has to be qualified according to the landscape in which they are implanted. In landscapes strongly marked by the human footprint, they seem perceived as increasing the landscape attractiveness. In unspoilt landscapes, they seem rather to contribute to their degradation. These global findings are nuanced in further research. Deeper analysis shows that Flemish people have a more positive view of the landscape than Walloons. I hypothesize a decisive influence of the local context. Indeed, Flemish landscapes are generally more urbanized and marked by man than most of the Walloon landscapes. The building of wind farms seems to change or even reverse the situation. The analysis also shows significant influences related to educational level and gender. Anthropogenic landscapes are less disregarded by low educated people. Women seem to attach importance to stewardship and landscape maintenance. In contrast, although suspected, age influence has not been formally demonstrated. The second part of this dissertation, the cornerstone of this doctoral research, aims at deconstructing the landscape concept in the mind of people. In this part, wind farms are no longer considered as a case study, but as a leitmotif. I deeper surveyed smaller groups (n = 54) in three areas of Wallonia (Walloon Picardy, between the Sambre and Meuse rivers, and Ardennes) with qualitative techniques. This survey was conducted five years after the first. The analysis of the vocabulary used by the regional sub-groups shows that people are not equipped the same way for analysing landscapes. The experience of living environment seems to be crucial in providing analytical keys. Thus Ardennes people seem better equipped to talk about the forest, marking their landscapes, while the Picards seem more loquacious about their iconic cultivated landscapes. The research also highlighted different landscape analysis patterns. Some people ordered landscapes according to their degree of naturalness, the less spoiled landscapes being the most attractive. On the contrary, fewer attach importance to landscapes where human footprint is clearly visible. Some respondents remain in a purely aesthetic landscape analysis, while others project themselves into the landscape, imagining they are performing different actions. Depending on their interests, these actions influence the perception of one same landscape. Research shows that this overall pattern analysis is disturbed by various factors. The recognition of certain places transformed landscape analysis in an analysis of the place, with the emotional changes that this entails. The position of the participants facing wind energy projects also appears sharper. In the time between the two parts of the research, Wallonia has experienced unprecedented wind development; opinions have therefore had time to form. This was not yet totally the case during the first survey. Beyond these major disruptions, the research also shows clear influences of the ordered character of landscapes, their living character and variety of land uses. The research also highlights the influence of non-visual criteria such as noise or odours detectable in the landscape. In conclusion, the research shows that respondents often show a sense of landscape, weaker than sense of place and stronger than aesthetic. [less ▲]

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See detailThe dynamics of market, credit and liquidity risk in the US corporate bond market
Heck, Stéphanie ULg

Doctoral thesis (2016)

Market, credit and liquidity constitute important risk factors in financial markets. Investors looking for optimal combinations of risk and return have to monitor their portfolios with regard to each of ... [more ▼]

Market, credit and liquidity constitute important risk factors in financial markets. Investors looking for optimal combinations of risk and return have to monitor their portfolios with regard to each of those factors. This work brings answers to some of the challenges presented by these three risk factors in the US corporate bond market. Market risk is the earliest and most widely acknowledged risk factor, affecting all financial securities. The risk that the issuer of the bond might go bankrupt introduces credit risk for corporate bonds. Finally, these securities are also characterized by a low trading frequency. Liquidity in this market has been severely affected by the recent global financial crisis as well as by the regulatory changes that followed the crisis. The first part of this dissertation studies the return premium investors require in compensation for undertaking credit risk. It is shown that distributional characteristics of individual assets and in particular the contribution of an asset’s return to the market portfolio’s skewness and kurtosis are important determinants of these premiums. The second part explores commonality in individual bond liquidity levels. It is shown that the pricing of liquidity in yield spreads is essentially due to this commonality. The final part of this dissertation designs a corporate bond market index based on the repeat-sales technique. The index adequately captures aggregate market dynamics and contributes to the explanation of the cross-section of individual corporate bond returns. [less ▲]

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See detailPlace de l'élevage bovin dans l'économie rurale des Peuls du Nord Bénin
Chabi Toko, Roukayath ULg

Doctoral thesis (2016)

Fulani belong to a socio-cultural group mainly encountered in West Africa and usually raises cattle. In Benin, Fulani are predominantly met in the two eastern departments of the North where they lead an ... [more ▼]

Fulani belong to a socio-cultural group mainly encountered in West Africa and usually raises cattle. In Benin, Fulani are predominantly met in the two eastern departments of the North where they lead an agro-pastoral way of life. In addition to livestock farming, they cultivate food and cash crops such as cotton. However, they hold majority of the country’s cattle population. The present study was initiated to understand to what extend cattle contributes to their rural economy. A stratified random sample of 150 heads of Fulani households, cattle farmers have been identified in Malanville, Banikoara and Kalalé districts in Borgou and Alibori departments. The criteria considered were: the agro-ecological zone, cattle population and the importance of Fulani population. The first series of surveys enable to characterize Fulani’s cattle farming system and their family farms. Among the 50 heads of households of Kalalé district (which has the more important Fulani community), 16 were selected and it is within their households that the study continued. The households selected were that with a better milk production. Surveys were then carried out during two years, both in dry season and rainy season to describe the Fulani’s household’s economy. The cattle stock composition showed a gender imbalance, with a preponderance of female stock (76%). Cattle herds which average size were 66 animals are made of 86% of Borgou breed. The herds have low breeding performance characterized by a high rate of calf mortality (10%) and low reproductive parameters: calving and fertility rates were 64%. The purchase of fodder in dry season, which concerns 17% of farmers, is a practice encountered in agroecological zones that register light rainfall. Fulani’s large households enable them to have enough family labor to carry out both livestock and agriculture activities. The land is mostly inherited and the average size for a household is about 10.5 ha. All Fulani households are crops producers of which majority (80%) is consumed. A significant part (45%) of them grow an average of 3.3 ha of cotton. In Fulani family farms, cattle represent 52% of the household livestock size; there is also small ruminants and poultry. This cattle permit to majority (76%) of Fulani households to have milk for sale. But milk is managed to favor household consumption and ensure the herd's reproduction. The organization around milk involves male and female. The profits from milk and cheese are distributed among the women of the household at various levels. Although the low (7%) cattle market rate, it contributes significantly (68%) to the household’s monetary income in rainy season and represents the second source (27%) of revenue in dry season. The 20% of food products are mainly sold in dry season and thus contribute to the majority (64%) of income sources. However, when rains started late and the delayed payment of cotton fees, the majority of Fulani households’ cash income in the rainy season, came from cotton (64%) and food products (23%). The growing involvement of Fulani cattle herders of northern Benin on the foodstuffs market and in cotton will lead to two types of farms with opposed production targets (those that will favor livestock and others agriculture). Fulani are a target population that should receive a little more support from authorities because enable them to value their resources would ensure availability and accessibility of food and pastoral products and contribute to the improvement of country’s agricultural production. [less ▲]

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See detailInventory routing for perishable products
Rezaei Sadrabadi, Mahmood ULg

Doctoral thesis (2016)

We explore three problems in this thesis and develop solution methods for each problem. First, an inventory routing problem for a perishable product with stochastic demands is considered and different ... [more ▼]

We explore three problems in this thesis and develop solution methods for each problem. First, an inventory routing problem for a perishable product with stochastic demands is considered and different approximate solution methods are developed to solve. Based on computational experiments, the solution methods are compared in terms of average profit, service level, and actual freshness. The impact of relevant parameters on the performance of the solution methods is investigated. Managerial insights are drawn by analyzing the impact of shelf life and store capacity on the profit. The value of considering uncertainty and the value of accessing full information are measured. The computational results highlight that a simple ordering policy can often replace a more sophisticated solution method, while preserving the same efficacy. Second, we introduce a vehicle routing problem (VRP) where a set of stores places deterministic orders to a logistics service provider (LSP) for two successive periods. Deliveries requested in each period can be shifted by the LSP to the other period, possibly with modified quantities. The LSP incurs a penalty for any diversion from the initial delivery period. The data regarding shifted delivery quantities and penalties are provided by the stores. From the perspective of the LSP, diversions could be beneficial if savings in the routing costs outweigh the penalties. In this work, we introduce a new two-period VRP model where the LSP seeks to improve its total cost, compared to solving two independent VRPs with fixed delivery periods, by allowing deliveries to be shifted. We solve this model to optimality by an efficient branch-and-price algorithm implementing several cutting-edge techniques. We draw algorithmic and managerial insights based on our test instances. Third, a two-period VRP is considered where the orders placed by stores for each period can be partially shifted to the other period, given that the sum of the delivery quantities in two periods to each customer is fixed. A linear penalization of delivery shifts is assumed based on the quantity shifted. We represent two mixed integer linear programming (MILP) formulations for the problem. A column-row generation algorithm to solve the LP-relaxation of the first formulation is developed. To solve the LP-relaxation of the second formulation, we develop a column generation algorithm. Details of two label-setting algorithms to solve the pricing problems of the column-row generation and column generation algorithms are discussed. Numerical results can be compared with a similar model in which only full delivery shifts are allowed. [less ▲]

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See detailEvaluation de l'impact socio-économique en aval des aménagements hydroélectriques : exemple du barrage hydroélectrique de Nam Mang 3 au Laos
Kouangpalath, Phimthong ULg

Doctoral thesis (2016)

Since two decades, hydropower projects are multiplying in Laos. These projects are often criticized in the media and civil society organizations for their negative social and environmental impacts, which ... [more ▼]

Since two decades, hydropower projects are multiplying in Laos. These projects are often criticized in the media and civil society organizations for their negative social and environmental impacts, which can also generate regional geopolitical tensions in Southeast Asia. In this sensitive context, our interest has focused on rural populations downstream of hydropower dams; these populations are often ignored by compensation programs reserved for displaced populations from upstream. The objective of the research is to identify and assess the socio-economic effects in the Nam Nyam Valley (Vientiane Province, Lao PDR), downstream of the Nam Mang 3 hydropower dam. A current diagnostic-analysis of the agrarian system of the valley, together with a characterization of the recent evolution was conducted by household surveys in different villages. The diachronic study of agrarian dynamics and understanding the links of causality enabled us to model a counterfactual scenario to isolate, by difference with the current situation (scenario "with project"), the specific effects of the dam. In parallel, a similar approach was employed downstream of the Nam Lik 1-2 hydropower dam in the Meuang Feuang basin (Vientiane province, Lao PDR) in order to compare with the results of the Nam Nyam Valley, to better characterize the specific effects of hydropower infrastructure developments. As a result, the evolution of agrarian systems in the valleys downstream depends on the combination, variable over time, of several political, economic, demographic, environmental, technical, social, etc. factors. A hydropower dam, like the one of Nam Mang 3 is part of complex and continuous dynamics of transformation; its impact is not only the sole cause of changes affecting the communities. The socio-economic effects influence over time a much larger population downstream than upstream, even if the media attract the attention on punctual displacement of villages (and their compensation) to fill the reservoir. The hydropower dam project effects differ according to phases (construction, reservoir filling, operation) and social categories, depending on the investment capacities, adaptation and networks of each category. The socio-economic impact downstream is not assumed to be correlated with the size of hydropower dam, but its design and mode of water management are the key criteria of the importance of negative externalities. The massive investments in these projects have also positive effects for the local population, such as the development of local infrastructure, which open up villages and provide access to public services and markets. However, these positive externalities mainly concern well-off villagers disposing of capital and networks to benefit of new opportunities, while poor families are more vulnerable to changes in the political, environmental, technical and socio-economic context. Thus, hydropower dams contribute to increased socio-economic differentiation in villages downstream, with the poor left out of the profits from the energy export. [less ▲]

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See detailBelgian Heterosexuals’ Attitudes towards Gay and Lesbian Couples and Same-sex Parenting
Scali, Thérèse ULg

Doctoral thesis (2016)

The legal situation of Belgian gay men and lesbians may be perceived as one of the best in Europe. Indeed, the Belgian Parliament has legalized marriage and parenting for same-sex couples, has enacted ... [more ▼]

The legal situation of Belgian gay men and lesbians may be perceived as one of the best in Europe. Indeed, the Belgian Parliament has legalized marriage and parenting for same-sex couples, has enacted anti-discrimination laws, and has designed and funded several action plans to combat homophobia. Since the opening up of marriage to same-sex couples in 2003, around a thousand gay and a thousand lesbian marriages are celebrated each year in Belgium (Direction Générale Statistique et Information Économique, 2015). Moreover, since the legalization of parenthood for gay men and lesbians, more and more same-sex couples adopt children or resort to artificial insemination, and the total number of children growing up with same-sex parents is growing steadily. Thus, a new reality is emerging: the reality of same-sex headed families. However, in spite of the civil rights granted to gay men and lesbians, the issue of social acceptance of same-sex couples and their children still remains and Belgium continues to record increasing levels of violence against homosexual people. Therefore, the main objective of the present thesis was to explore Belgian heterosexuals’ attitudes towards same-sex marriage and same-sex parenting. The first goal was to investigate the social and personal factors that may be associated with positive and negative attitudes towards same-sex marriage and those towards same-sex parenting (Study 1). The results of self-report questionnaires (N = 1168) revealed that the general attitude towards gay men and lesbians, gender-role traditionalism, beliefs in the origin of homosexuality, representations about child well-being and contact are major predictors of attitudes towards gay and lesbian civil rights. Moreover, results revealed that attitudes differed according to participant’s gender (heterosexual men are less supportive of both same-sex marriage and same-sex parenting than heterosexual women). The respective role of several variables was also discussed (gender-role traditionalism, beliefs in the origin of homosexuality, general attitudes towards gay men and lesbians, representations of child well-being and contact). We demonstrated that increasing intergroup contact can help diminish the impact of some personal beliefs on attitudes towards same-sex parenting. Moreover, results revealed that the degree of support differed in regard to the different types of parenthood. Moreover, several authors in the field of social psychology highlighted the role of beliefs and social representations upon attitudes (Dardenne, 2006). Specifically, attitudes towards gay men and lesbians as parents seem to be somehow beliefs-based (Costa, 2013). Our next objectives were to explore the arguments in favour and against same-sex parenting, both in the general population through the comments posted on social networks (Study 2) and with health-care professionals working in family counselling centres (Study 3). Both studies highlighted positive and negative arguments, each linked to one of the following category: societal and legal context, religiosity, contact, representations of homosexuality, gender-role traditionalism, general attitudes towards gay men and lesbians and representations about child well-being. Moreover, a comparative analysis of the two samples allowed us to state that the arguments held by the social workers are quite similar to those held by the citizens in the general population. Thus, we concluded that health-care professionals’ attitudes are based on naïve knowledge rather than on scientific knowledge, and this lack of scientific knowledge on same-sex parenting has an impact not only on social workers’ attitudes but also on their interventions. To conclude, our work demonstrated that, in Belgium, the barriers to accepting rainbow couples and families are no longer legal, but social. Nearly ten years after the law on adoption for same-sex couples, the country remains relatively conservative and traditional in some regards. Therefore, by demystifying and deconstructing ill-conceived ideas, it will be possible to move towards greater acceptance. Thus, more positive attitudes may be reached when in-depth work has taken place on social perceptions, particularly around questions of gender-role traditionalism, the representations of homosexuality and same-sex lifestyle, and around the child’s well-being. In particular, it is important to deconstruct stereotypes about gay men and lesbians and open minds to other possible forms of families. To achieve those goals, the role of intergroup contact is very important. It is, consequently, also down to psycho-social trainers to create homophobia prevention programmes based on tailor-made training sessions, taking into account the specificities of each group and their beliefs. Finally, we recommend that future research focuses upon same-sex parent families, in order to enrich the scientific data available on these families and their experiences. [less ▲]

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