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See detailFrom photons to biomass in green microalgae: fluorimetric and oxymetric studies on the regulation of photosynthetic electron transport
de Marchin, Thomas ULg

Doctoral thesis (2015)

Analyzing the photosynthetic performances of microalgae has become an important topic in view of the ecological importance of these microorganisms and of the growing field of their biotechnological ... [more ▼]

Analyzing the photosynthetic performances of microalgae has become an important topic in view of the ecological importance of these microorganisms and of the growing field of their biotechnological applications. In this thesis, we developed methods which allow effective use of fluorescence and oxygen experimental signals for a more complete analysis of the functioning of the photosynthetic apparatus of green microalgae under different conditions. We applied these methods to analyze the adaptations of the photosynthetic apparatus under selected conditions, especially regarding CO2 supply. In the first part of this work, we applied a fluorescence-based method for determining the PSII antenna size based on the kinetics of the fast chlorophyll a fluorescence transient in presence of DCMU (or DCMU Fluorescence Rise). We then performed a detailed analysis of the different phases of this transient which are associated with different types of PSII formerly described as PSIIalpha and PSIIbeta (PSII heterogeneity). Our results on PSII heterogeneity during a transition from state 2 to state 1 in Chlamydomonas reinhardtii showed for the first time in vivo that this transition correlates with a conversion of PSIIbeta to PSIIalpha. We also discuss the possible relationships between PSIIalpha and PSIIbeta and the PSII mega-, super- and core- complexes described by biochemical studies. In photoautotophic atmospheric conditions, microalgae often have to deal with limited CO2 availability. The unicellular green algae Chlamydomonas reinhardtii can adapt to low CO2 concentration with the inorganic carbon concentration mechanism (CCM). This has been extensively studied in the past. However, other functional adaptations of the photosynthetic apparatus to CO2 limitation have been much less studied. In the second part of this work, we used combined fluorescence-based electron transport and oxygen measurements to evaluate the responses to low and high CO2 in Chlamydomonas reinhardtii grown in photobioreactors at different light intensities. We developed a method to rationalize the relationship between the apparent quantum yields of oxygen evolution and of electron transport at PSII while taking into account the variations in the proportion of energy absorbed by PSII. We used this relationship as a tool to evidence a significant O2-dependent alternative electron transport in low CO2 acclimated cells. We showed that this alternative electron transport can represent up to 60% of the total electron transport in low CO2 cells even upon removal of the CO2 limitation by bicarbonate addition. In contrast, no significant alternative electron transport was detected in high CO2 cells. We suggest that the alternative electron transport to O2 observed in low CO2 cells represents an adaptation that could help to meet the higher ATP demand for the concentration of CO2 by the CCM. In contrast, in high CO2 conditions, the absence of the CCM would reduce the need for ATP and thus the need for electron transport to O2. Using mutants and inhibitors, we studied the involvement of known O2-dependent electron sinks such as the mitochondrial cytochrome and alternative oxidase pathways and also of chlororespiration in this light-dependent O2 uptake and we found no evidence for the involvement of any of these processes. The alternative electron transport was even higher in a mitochondrial mutant devoid of complexes I and III and we suggest that this alternative electron transport could compensate for the absence of mitochondrial ATP synthesis in this mutant. By elimination, our results suggest that the alternative electron transport to O2 evidenced here could be driven by a Mehler-type reaction although we did not find direct evidences for increased Mehler-type activity in low CO2 cells. Additionally from fluorescence measurements performed directly in the cultures, we concluded that low CO2 cells had a lowest PSII photosynthetic efficiency and developed strong qE NPQ. Our results indicate that Chlamydomonas reinhardtii is capable to induce an ample thermal dissipation of excitation energy and the extent of this process is influenced essentially by the CO2 availability. In contrast with results obtained in previous studies, low temperature fluorescence spectra showed that in high light, high CO2 cells were characterised by a higher proportion of light energy absorbed by PSI compared to low CO2 cells. This was accompanied by a decrease of PSII antenna size as shown by DCMU-FR measurements. These findings are discussed in relation with the conflicting theories concerning the role of state transitions in the regulation of the cyclic electron transport around PSI. Our results support the idea that CEF is regulated by the redox state of the chloroplast rather than by state transitions. Over the last decades, microalgae have been increasingly studied because of their potential applications in industry. Despite a growing interest in microalgae mass cultures, the majority of studies on microalgae have been carried out at a laboratory scale and only few studies have addressed the question of photosynthetic adaptations in mass cultures. It is well known that CO2 addition increases the growth rate of microalgae and for this reason, some mass microalgae cultures are CO2 supplemented. Among the studies on microalgae mass culture, as far as we know, none directly compared high CO2 (CO2 supplemented air) and low CO2 (air) conditions. In the last part of our work, two outdoor open thin-layer cascade systems operated as batch cultures with the alga Scenedesmus obliquus were used to compare the productivity and photosynthetic adaptations in control and CO2 supplemented cultures in relation with the outdoor light irradiance. We found that the culture productivity was limited by CO2 availability beyond a threshold of daily irradiance. In the CO2 supplemented culture, we obtained a productivity of up to 25 g dw.m-2.day-1 and found a photosynthetic efficiency of 2.6%. Fluorescence and oxygen evolution measurements showed that ETR and oxygen evolution light saturation curves, as well as alternative electron transport were similar in algal samples from both cultures when the CO2 limitation was removed. In contrast, we found that CO2 limitation conducted to a decreased PSII photochemical efficiency and an increased light-induced heat-dissipation in the control culture compared to the CO2 supplemented culture. These features may contribute to the lower productivity observed in absence of CO2 supplementation in outdoor mass cultures of Scenedesmus obliquus. [less ▲]

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See detailEtude sur la sexualité en milieu carcéral belge: De l'enfermement de la sexualité à la liberté d'adaptation des comportements sexuels.
Francois, Axelle ULg

Doctoral thesis (2015)

En Belgique, la question de la sexualité des personnes incarcérées a rarement fait l’objet de recherches de la part des chercheurs en sciences humaines, particulièrement des criminologues. A partir ... [more ▼]

En Belgique, la question de la sexualité des personnes incarcérées a rarement fait l’objet de recherches de la part des chercheurs en sciences humaines, particulièrement des criminologues. A partir d’informations obtenues auprès de 530 hommes incarcérés au sein de dix établissements pénitentiaires belges francophones, nous avons réalisé une étude de la sexualité en milieu carcéral perçue et vécue par les personnes détenues. S’appuyant ainsi sur le modèle de la privation tel que développé par Sykes (1958), notre recherche se fonde sur l’hypothèse principale suivante : « la privation de relations hétérosexuelles en prison engendre chez le détenu un sentiment de frustration et en réponse à ce sentiment, l’individu incarcéré cherche à s’adapter. Cette adaptation suit différentes trajectoires allant de pratiques sexuelles plus solitaires à des pratiques sexuelles de substitution impliquant un rapport à l’autre. Elle porte également sur les discours et les comportements des personnes dans un contexte carcéral particulier et est influencée non seulement par leurs perceptions mais aussi par leur vécu ». Considérant cette hypothèse générale, notre étude entendait ainsi dresser un portrait actualisé de la sexualité incarcérée qui dépasse les apparences et les discours officiels. Grâce à la mise en œuvre d’une méthodologie d’analyse quantitative, six objectifs plus spécifiques ont été investigués. Pour étudier les représentations et le vécu de la sexualité en milieu carcéral de notre échantillon, nous nous sommes d’abord appuyée sur les apports théoriques et scientifiques de la littérature spécifique. Ensuite, au moyen de traitements statistiques appliqués à notre base de données, nous avons cherché pour chaque axe des corrélations entre d’une part, les variables relatives aux représentations et vécus sexuels des détenus et d’autre part, des variables caractéristiques comme par exemple l’âge, la durée d’incarcération, l’existence d’un partenaire affectif extérieur, le bénéfice de visites en prison et la participation aux activités en détention,…. [less ▲]

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See detailImpact de la dynamique foncière dans la lutte contre l’insécurité foncière et la pauvreté des femmes dans la région de Tahoua au Niger
Moussa dit Kalamou, Mahamadou ULg

Doctoral thesis (2015)

In Niger Republic land issue is a concern to all parties acting in the rural area. The drought cycles of the last decades and the rapid increase of the population that doubles every ten years are ... [more ▼]

In Niger Republic land issue is a concern to all parties acting in the rural area. The drought cycles of the last decades and the rapid increase of the population that doubles every ten years are determinant factors of degradation of the agricultural land of culture with as consequence the land and food insecurity of the households in particular in the region of Tahoua. Despite efforts by the government and its partners through the village land management programs and natural regeneration, land access difficulties persist particularly for women households. The objective being to assess and analyze the impact of land dynamics induced by the recovery of land in order to find some solutions to the problems of land insecurity and access and control of natural resources by households, a survey was conducted in two phases. The first in 2010 for a sample of 420 households in twenty villages selected through a stratified sampling. The second in 2012 for a sample of 84 households with 42 female heads of household from the first sample being associated with a group of 42 male heads of households for a specific gender analysis. It appears from this study that men households have an average land area about twice as large as that of female households .It was also found that the land is usually concentrated in the hands of older householders over 60 years. It is noticed that the inheritance is also one of the most dominant modes of access to land. The fragmentation and the expansion of croplands favor the emergence of fields beyond the northern boundary of crops dedicated to breeding. Finally, the last three years, agricultural production has generally fallen. The results of the analysis also show that unlike men, women household heads have less inputs, on the one hand, and little income, on the other hand. These female households derive their main income from the sale of animal products. This proves that women are the poorest households with limited access to natural resources. To fight against tenure insecurity and poverty of households recommendations and perspectives have been identified for the establishment of good governance of land resources, intensification of anti-erosion works by households with substantial resources and initiation of other additional research for sustainable development of the region. [less ▲]

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See detailContribution à l’étude de la dynamique de l’élevage pastoral au Niger : cas de la région de Diffa
Laouali, Abdoulkadri ULg

Doctoral thesis (2015)

In the Sahelian countries where extensive pastoral breeding is practiced, livestock plays an essential role in the socio-economic and dietary balance of the households. However, throughout the literature ... [more ▼]

In the Sahelian countries where extensive pastoral breeding is practiced, livestock plays an essential role in the socio-economic and dietary balance of the households. However, throughout the literature, this activity was submitted to various controversies including its contribution to the degradation of the environment; greenhouse gas emissions; its weak economic performance; etc. But other studies have noted the importance and efficiency of pastoral practice in a precarious natural environment such as the Republic of Niger, great stockbreeding country in the heart of the Sahel, with a herd of over 37 million heads. Thus, this research has tried to reposition the debate by emphasizing the role and importance of pastoral breeding in the Sahelian countries in general, particularly in Niger and specifically in the region of Diffa. Located between the desert zone in the North and the Sahelian zone in the South, the Region of Diffa is a pastoral area par excellence in Niger. Breeding, with a highly diversified livestock, is the dominant economic activity in the region. It concerns 95% of the population and contributes annually to 55% of the regional gross domestic product. However, this activity is submitted to various constraints, particularly biophysical and anthropogenic. In order to understand the pastoral dynamics in this region, a research work was initiated starting in 2010 and following a systemic approach. The work was built around three poles: Man-Natural Resources-Animals. A survey of 300 households (150 households with a sedentary herd and 150 with a mobile herd) was conducted during the first semester of 2012. Investigations were made on the basis of the prior identification of three agro-ecological zones (pastoral bowls, Komadougou River, Lake Chad) based on 100 households for each zone. The research results revealed that pastoral breeding in the region of Diffa is mutating. Herds (sedentary and mobile) are relatively small sized and increasingly composed in majority by small ruminants. The reproduction is carried out by a core of female spawners more or less stable and dominated by younger ones. Data cross analysis highlights the occurrence of recurrent fodder deficits, attributable to a series of annual rainfall deficits as well as animal diseases as the main causes of changing pastoral breeding in the region of Diffa. To deal with these problems the pastoral and agro-pastoral populations have built and developed a set of adaptive strategies to resist shocks and to mitigate their effects and to ensure the survival of households and livestock. However, over the years and the recurrence of shocks, traditional strategies for managing risks and uncertainties are being weakened with socio-economic consequences in pastoral and agro-pastoral households. An Intervention of the State, NGOs and / or associations and other development partners, would boost these strategies and strengthen the capacity of households to manage risk in the long term. [less ▲]

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See detailQuantifying landscape anthropisation patterns: concepts, methods and limits
Vranken, Isabelle ULg

Doctoral thesis (2015)

Since human beings began to use and shape the land, their influence on their environment has kept on growing so that little or no ecosystem in the world is now considered as untouched. This induces ... [more ▼]

Since human beings began to use and shape the land, their influence on their environment has kept on growing so that little or no ecosystem in the world is now considered as untouched. This induces pressures on ecosystem health and land scarcity. Africa is of particular concern because it still presents broad undisturbed zones and key ecosystem services, despite being submitted to increasing anthropogenic pressures. Landscape ecology appears suitable for the study of such phenomena, thanks to its spacebased integrative nature and geographical level of focus. It studies the impact of spatial pattern transformation — especially heterogeneity and its components — on ecological processes and provides powerful analytical tools of landscape anthropisation. The main objective of this thesis is to organise the concepts and methods, from landscape ecology and related disciplines, into a consistent logic, to pinpoint missing analytical frameworks for response-oriented anthropisation assessment, and to apply them to African cases to explore the spatial patterns of anthropisation. In order to address landscape anthropisation, we assemble diverse disciplines into a logical network (DPSIR). The new theoretical framework is tested on Lubumbashi (DRC). In order to address spatial patterns, we first evaluate the thermodynamic connection of the term entropy in landscape ecology: spatial heterogeneity, unpredictability and scale influence. Then, based on 20 landscapes, we highlight the complex relationship between spatial heterogeneity and landscape anthropisation. We finally use the modelled relationships to test the anthropogenic origin of the spatial pattern of a land cover class in Lubumbashi. The main results of this research show that several concepts are used to describe different aspects of anthropisation and that its quantification strongly depends on the reference states. Data formats can be combined into a new assessment method ensuring more precision and comparability, but a good field knowledge is required. As for heterogeneity, the existing definitions of landscape entropy follow the logic of thermodynamics or information theory, that are not compatible. Only unpredictability could be properly interpreted in thermodynamic terms if energy transfer measurements were performed at the appropriate level. The anthropogenic effects on heterogeneity completely diverge depending on the amount of already anthropised surface, on the land cover type (natural or anthropogenic), and on the heterogeneity components. The aforementioned findings could be adapted to include functional aspects and better address the relationship between spatial pattern and ecological processes. Such integration would help designing response actions that can recommend human activities and spatial patterns that could optimise the use of land to ensure ecological functioning while supporting human development. [less ▲]

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See detailFermentation du kivuguto, lait traditionnel du Rwanda: mise au point d’un starter lactique
Karenzi, Eugène ULg

Doctoral thesis (2015)

Résumé Une recherche pour la production industrielle du kivuguto, lait caillé traditionnel du Rwanda a été entreprise par la sélection de micro-organismes responsables de la fermentation de ce lait ... [more ▼]

Résumé Une recherche pour la production industrielle du kivuguto, lait caillé traditionnel du Rwanda a été entreprise par la sélection de micro-organismes responsables de la fermentation de ce lait normalement produit artisanalement. Pour ce faire, il fallait une mise au point d’un starter lactique à partir des isolats issus des échantillons de lait artisanal kivuguto. Au terme de quatre échantillonnages, un dénombrement, un isolement et une purification ont abouti à conserver dans la Collection du CWBI 390 souches pures. Par des analyses phénotypiques (microscopiques, biochimiques), associées à des tests de résistance aux conditions extrêmes et à une analyse préliminaire des propriétés technologiques, 7 souches ont été pré-sélectionnées pour la poursuite du screening. Une caractérisation moléculaire par la méthode de 16S ADNr associé ou non à l’ITS 16S-23S ADNr a assimilé ces souches à deux Lactococcus lactis, deux Leuconostoc mesenteroides et trois Leuconostoc pseudomesenteroides. Des essais de formulation de laits fermentés par des mélanges de souches et leur conservation pendant 24 jours ont permis de formuler un lait fermenté semblable au lait artisanal kivuguto par l’association d’un Lactococcus lactis, d’un Leuconostoc mesenteroides et d’un Leuconostoc pseudomesenteroides. En effet, lors d’une analyse sensorielle discriminative, un jury de dégustation constitué de huit personnes est parvenu à identifier ce lait formulé parmi deux autres laits fermentés commercialisés aussi sur le marché à des différences significatives de p=0.05 dans une première série et p=0.01 dans une deuxième série. Des analyses technologiques proprement dites ont montré que ce lait formulé fermente après 14 heures avec une acidification de 73°D à pH4.6 et à 19°C, présente des caractéristiques d’un fluide visco-élastique. Son activité protéolytique est moyenne pour ne pas développer des peptides responsables de l’amertume en stockage. Son profil aromatique comporte cinq composés principaux 3-méthylbutan-1-ol, pentan-1-ol, acide acétique, furanméthan-2-ol et furan-2(5)H-one clairement identifiés par GC-MS. L’étude de la production et de la conservation de trois souches sélectionnées a montré une bonne stabilité sur trois mois à 4°C avec des viabilités cellulaires >90%, mais moins bonne à 20°C. [less ▲]

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See detailEntre national et local: Louis Jacquinot, archétype du notable modéré
Bour, Julie ULg

Doctoral thesis (2015)

Louis Jacquinot was born in Gondrecourt-le-Château, a common South Meuse in 1898 and died in 1993 in Paris. It remains an unknown figure in the political history. However, it exercises governmental ... [more ▼]

Louis Jacquinot was born in Gondrecourt-le-Château, a common South Meuse in 1898 and died in 1993 in Paris. It remains an unknown figure in the political history. However, it exercises governmental functions under the Third Republic and became a minister under the Fourth and the Fifth Republic. In total, Louis Jacquinot is minister almost twenty times, including Minister of Marine (1943-1945 and 1947), Veterans Affairs (1949-1951), or Overseas (from 1951 to 1954 and 1961 1966). In parallel, the local quarry is important: MP for Meuse from 1932 to 1973, conseiller général and président du Conseil général de la Meuse from 1945 to 1973. The career of this moderate is placed under the sign of longevity. This thesis traces his life, his career and his local and national career. But this biography is devoted to the study and analysis of the recommendation of the elected job. Indeed, the Meuse MP archives contain 17 000 letters of recommendations that support this work. A general analysis of the practice in the department for nearly a century is realized through other sources of archival Meuse elected, including its predecessors (Raymond Poincaré, Jules Develle, André Maginot) and his successors (Jean Bernard). [less ▲]

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See detailVolatile Organic Chemicals in the Rhizosphere of Barley, and their Role on the Foraging Behavior of Wireworms (Coleoptera: Elateridae)
Barsics, Fanny ULg

Doctoral thesis (2015)

Many species of wireworms, the larvae of click beetles (Coleoptera: Elateridae), are known as worldwide belowground pests of a large range of crops including cereals. Pesticide based agricultural ... [more ▼]

Many species of wireworms, the larvae of click beetles (Coleoptera: Elateridae), are known as worldwide belowground pests of a large range of crops including cereals. Pesticide based agricultural practices seem to have allowed significant population reduction in the past, but there is an increasing need for alternative control methods. In the first Chapter of this work, we review the current knowledge concerning 1) Integrated Pest Management (IPM) of wireworms and 2) their chemical ecology. These reviews shed light on promising approaches to develop new management strategies, as well as gaps of knowledge to be filled in that purpose. One of them is investigated here. The research aim of this PhD thesis (detailed in Chapter II) is the identification of the volatile organic compounds (VOC) released by the roots and used by wireworms to locate their food source. To achieve this goal, we defined three objectives: 1) developing a behavioral assay suitable for the study of wireworm orientation behavior under exposure to root-produced VOC; 2) profiling VOC released in the rhizosphere, according to different growth conditions; and 3) evaluating the role of the identified VOC on wireworm foraging behavior. Our experimental model involved Agriotes sordidus Illiger wireworms and Hordeum distichon L. (spring barley). In Chapter III, we report on the developmental steps of an adequate olfactometric method for wireworms. This includes an initial setup, the “Y-shaped” olfactometer, and dual-choice pipes gathering the necessary upgrades to efficiently observe the behavior of wireworms exposed to a VOC source. By resorting to live roots in a variety of features, we attempted to highlight appropriate abiotic and biotic experimental parameters, as well as the limits to the use of our olfactometric devices. The bioassays confirmed the attraction of wireworms towards VOC emitted by live roots. With a first sampling method on excised roots, Solid – Phase Micro – Extraction (SPME – semi-quantitative), coupled to Gas Chromatography – Mass Spectrometry (GC-MS), we detected a high number of molecules that might act as semiochemicals on wireworms, notably in our bioassays. In the fourth Chapter, the bioassays were performed with selected VOC, detected during the chemical profiling. Firstly, we assessed if wireworms were attracted towards 2 pentylfuran, the main VOC highlighted with SPME. The molecule was submitted to the larvae by encapsulation in alginate beads. An adequate formulation allowed reaching an emission rate matching quantification estimates. In the aim to improve the VOC profiling, we also used Dynamic Head-Space Sampling (DHS), on roots ground in liquid nitrogen. It highlighted four volatile aldehydes. Their biological activity on wireworms was evaluated thanks to glass wool/triacetin-based dispensers, inserted in the dual-choice pipes. Through this work, we show that VOC produced by barley roots carry information useable by foraging wireworms. The two sampling methods indicate two different modalities of root-VOC production and are encouraging for further understanding of belowground VOC production and emission. The developed olfactometric method and related results open new perspectives to increase knowledge on wireworm ecology. Combined to other developments in research on their management, they could lead to interesting, innovative and ecological management practices. [less ▲]

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See detailDevelopment of Hyphenated Methods for the Comprehensive Analysis of Complex Biological Samples
Brasseur, Catherine ULg

Doctoral thesis (2015)

The successful analysis of complex mixtures requires the combination of highly efficient separation techniques with advanced detection technologies to provide individual structural information. The ... [more ▼]

The successful analysis of complex mixtures requires the combination of highly efficient separation techniques with advanced detection technologies to provide individual structural information. The coupling of gas chromatography and mass spectrometry was one of the first steps in hyphenated method development. Nowadays, due to continuous hardware improvement, the term hyphenation has been extended to multidimensional separations and/or multiple detectors. The objective of the thesis is to develop hyphenated methods to extend the range of applications and propose solutions to improve the characterization of specifically selected complex samples. The main hyphenated technique that was used is comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS). Three thematic areas, presenting different levels and types of complexity were investigated: Forensic geotaphonomy with grave soil samples, lignocellulose biomass valorization with termite gut microbiota samples, and human monitoring for emerging organohalogen contaminants with blood samples. Data processing strategies were also developed in order to extract the relevant information from the large quantities of data produced. The different strategies included retention time alignment, comparative data processing, multivariate analysis using unsupervised learning algorithm such as principal component analysis (PCA), univariate analysis of variance (one-way ANOVA), and scripting for automated filtering of mass spectra. All developed methods allowed to successfully improve the characterization of samples originating from the different areas. For the first time, and because of the high level of specificity of GC×GC-TOFMS, the presence of methyl-branched alkane compounds was highlighted in grave soil samples, allowing to develop a screening method that has the capacity to differentiate between soils at proximity of buried decaying pig carcasses and control soils. This strategy could complement other approaches and contribute to aid forensic geotaphonomy investigators. In the biomass valorization area, more than 300 compounds were isolated and partly identified in the 1µL fluid volume available from the termite gut. A comparative study demonstrated that the adaptation of the termite system to non-optimal carbon sources is reflected in the metabolite profile. These results demonstrated the potential interest to investigate metabolite profiling with state-of-the-art separation science tools, to contribute to a better understanding of how termites efficiently degrades lignocellulose. In the human monitoring area, the analysis of serum samples using GC×GC-TOFMS and scripting allowed the efficient reduction of the data matrix from thousands of detected signals to a few important dozens, including the environmental contaminants of interest present in human blood plasma. Such an approach reduced data processing and reviewing time by several orders of magnitude while maintaining a high degree of identification power. This exploratory approach could result in the identification of emerging toxicants and help regulation bodies to gather better information before they rule on emerging issues. GC with high resolution mass spectrometry (HRMS) was also used, using a selective approach to evaluate human exposure to dechloranes, a family of emerging halogenated flame retardants recently reported as significantly present in the environment. A comprehensive approach was also developed using GC×GC coupled to high resolution TOFMS (HRTOFMS). The developed methodology will facilitate the monitoring of these emerging dechlorane contaminants and analogues in future exploratory studies. [less ▲]

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See detailGeräusch, Gerücht, Gerede. Formen und Funktionen der Fama in Erzähltexten Theodor Storms und Arthur Schnitzlers
Leyh, Valérie ULg

Doctoral thesis (2015)

Dans sa représentation allégorique de Fama, le poète latin Ovide évoque trois phénomènes précis : son aspect acoustique (le bruit), sa forme discursive (les racontars) et son lien au récit (la rumeur ... [more ▼]

Dans sa représentation allégorique de Fama, le poète latin Ovide évoque trois phénomènes précis : son aspect acoustique (le bruit), sa forme discursive (les racontars) et son lien au récit (la rumeur). Alors que ces phénomènes ont très souvent fait l'objet d’études sociologiques et anthropologiques, il s’agit ici de les étudier en tant qu’objets d’un processus d’esthétisation. La thèse vise ainsi à décrire une « poétique de Fama » par l’analyse d’un choix de textes narratifs des auteurs germanophones Theodor Storm (1817 – 1888) et Arthur Schnitzler (1862 – 1931). En effet, les recherches récentes sur l’anticipation de la psychologie et sur les questions de perception chez Storm soulignent l’importance de stratégies narratives au caractère indirect, voilé et mettant à mal la plausibilité ; elles révèlent la nécessité d’étudier la rumeur comme élément thématique mais aussi structurel et formel. Les nombreux aspects de Fama intimement liés aux processus narratifs (polyphonie, psychologisation, contournement de la censure) permettent ensuite de confronter les textes de Storm à ceux de Schnitzler et d'y préciser les interactions subtiles entre bruit, racontars et rumeur. Dans ce traitement littéraire de Fama, il s’avère en outre primordial de mettre en lumière ses multiples fonctions selon les différents niveaux textuels (personnages, narrateur, auteur) et d’accorder une place au lecteur qui, dans une approche interactionnelle du récit, prend souvent part à la communication rumorale. Ces distinctions permettent de mettre en exergue la dimension poétologique de Fama dans ses différentes formes : si celle-ci participe à la création d’effets paradoxaux et de structures équivoques au sein des textes, c’est parce que la rumeur, en tant que forme de narration à caractère ambivalent et protéiforme, est fortement autoréflexive. L’instabilité et la contingence, l’indétermination de seuils et de frontières sont autant de traits qui caractérisent non seulement la rumeur et les racontars mais aussi les textes d’une époque marquée par de grandes mutations et par la mise en doute de valeurs et données acquises jusque-là. [less ▲]

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See detailSimplified analytical methods for the crashworthiness and the seismic design of lock gates
Buldgen, Loïc ULg

Doctoral thesis (2015)

The PhD dissertation aims to provide simplified tools based on analytical formulations in order to ease the pre-design of lock gates. The first part of the thesis is devoted to ship collisions. The ... [more ▼]

The PhD dissertation aims to provide simplified tools based on analytical formulations in order to ease the pre-design of lock gates. The first part of the thesis is devoted to ship collisions. The resistance of the impacted gate is evaluated by combining global and local deforming modes. In the second part of the dissertation, an analytical solution is proposed to estimate the total hydrodynamic pressure acting on a lock gate during a seism, with due consideration for the fluid-structure coupling. Numerical validations are proposed for both ship collisions and earthquakes. [less ▲]

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See detailGESTION TECHNIQUE DE L'ENVIRONNEMENT D'UNE VILLE (BEMBEREKE AU BENIN): Caractérisation et quantification des déchets solides émis; connaissance des ressources en eau et approche technique
Ngahane, Emilienne Laure ULg

Doctoral thesis (2015)

La sauvegarde de l’environnement, l’un des piliers du développement durable, ne s’intègre que timidement dans les plans de développement communaux en Afrique. A Bembéréké, comme dans la plupart des ... [more ▼]

La sauvegarde de l’environnement, l’un des piliers du développement durable, ne s’intègre que timidement dans les plans de développement communaux en Afrique. A Bembéréké, comme dans la plupart des communes en Afrique subtropicale, on note parmi les problématiques environnementales majeures : un amenuisement des facteurs de production en milieu rural et une insalubrité alarmante en milieu urbain. En effet, le centre urbain de Bembéréké s’est avéré insalubre au terme de deux études (DCAM, 2005 et Ngahane, 2010) ; le paludisme, les infections respiratoires, les anémies, etc. sont le quotidien des populations. Le projet « Gestion des Déchets solides » veut résorber cet épineux problème et pour ce faire, nous avons mis sur pied une méthode de caractérisation rapide, simple, peu coûteuse et flexible permettant de disposer, au préalable, de données de base fiables. Ainsi, à Bembéréké, en 2011, la production moyenne des ordures ménagères est de 0,94 +/- 0,10 kg/j.hab, soit 1,9 +/- 0,3 l/j.hab ; cette production est dominée par les gravats/fines et la matière organique biodégradable. Alors que, la production des ordures ménagères n’y est significativement liée ni aux saisons, ni aux quartiers et ni aux standings ; leur composition présente des variations très significatives entre et au sein même des saisons, des quartiers et des standings. Donc, gérer les déchets solides à Bembéréké, c’est gérer à 99 % les ordures ménagères ; soit 6 050 T (12 107 m3) pour 2011 : 55 % d’Inertes, 40 % de fermentescibles, 6 % de combustibles et 1% de déchets dangereux. Parce qu’elle est performante, l’alternative D1 « 75% Prévention-25% Elimination » a été retenue pour la gestion de ces déchets ; toutefois, sa mise en œuvre doit être progressive. A Bembéréké l’agriculture et l’élevage sont le moteur économique. Jadis complémentaires, ces deux activités ont connu des ajustements/adaptations après la période de grande sécheresse (1970-1980) : l’agro-pastoralisme naît, les moyens et les systèmes de production convergent, une concurrence s’établit dès lors sur les ressources désormais communes que sont la terre et l’eau. Cette concurrence est accrue dans les bas-fonds offrant encore simultanément ces ressources en saison sèche. Les rares retenues d’eau, mais vitales, de plus en plus convoitées, doivent subvenir aux besoins que sont l’abreuvage bovin (40 l/j.tête) et le maraîchage (100 m3/j.ha), essentiellement. Par ailleurs, pour le développement socio-économique de Bembéréké comme du Bénin en général, les ressources en eau ne constituent pas un facteur limitant. Pour le site de Guessou-Sud dont le réservoir a une capacité actuelle d’environ 13 000 m3, l’ensemble des besoins considérés a été estimé à 40 000 m3/an ; tandis que, le site recevrait du bassin versant en moyenne 8 000 000 m3/an. En plus de l’urgence d’un triplement de la capacité de stockage de la cuvette de la retenue de Guessou-Sud, l’état de dégradation avancée du site suggère une restauration, une préservation voire un rehaussement de son potentiel et de ses richesses floristiques et faunistiques afin, de sécuriser ses conditions hydriques. La pérennisation de cette ressource et la réplication de cette expérience sur d’autres sites donneraient une dynamique nouvelle dans ce contexte très local, mais traduisant une réalité régionale, qu’est la commune de Bembéréké. [less ▲]

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See detailLattice dynamics and magnetic properties in selected functional iron compounds
Herlitschke, Marcus ULg

Doctoral thesis (2015)

The presented thesis reports about to the investigation of four different materials with respect to their magnetic properties and their lattice dynamics. The carbodiimide FeNCN, which was recently ... [more ▼]

The presented thesis reports about to the investigation of four different materials with respect to their magnetic properties and their lattice dynamics. The carbodiimide FeNCN, which was recently synthesized for the first time and can be considered as an non-oxidic analogue to FeO, is discussed in chapter 2. The NCN 2− group bridges two iron and exhibits a double negative charge, similar to the oxygen in FeO. This material exhibits an increased magnetic order temperature as compared to FeO. FeNCN was investigated with magnetometry, Mössbauer spectroscopy and nuclear inelastic scattering, revealing an unusual behaviour of the hyperfine parameters below the ordering temperature. This observation is discussed with respect to the crystal field and the d-orbital level population with temperature. The investigation of the magnetocaloric material Mn5−x FexSi3 is reported in chapter 3 with focus on the interaction of magnetism and lattice dynamics. Among the Mn5−xFe x Si3 compounds, MnFe4 Si3 is the most interesting one due to the possible application as a room temperature refrigeration material. The investigation reveals that a direct measurement of the influence of the magnetocaloric effect on the density of iron phonon states is not possible, however, the elasticity was observed to be strongly influenced by this effect. The studies on the spin orientation in nanospheres and a NANOPERM alloy are discussed in chap ter 4 and chapter 5. Two approaches were followed in order to investigated the spin orientation, nuclear forward scattering and nuclear resonant small-angle X-ray scattering. In the first part, maghemite nanospheres are analysed with in-field nuclear forward scattering, revealing that the spins orient only partially along the direction of the applied magnetic field. A modeled magnetization calculated from the observed degree of spin orientation matches excellently the macroscopic magnetometry data and literature values. Though revealing the amount of oriented spins, nuclear forward scattering is not sensitive to their position in the nanoparticles. Thus, the nuclear forward scattering was combined with small-angle X-ray scattering, leading to small-angle patterns in dependence of the local spin orientation in the aforementioned samples. [less ▲]

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See detailRaymond M. Lemaire (1921-1997) et la conservation de la ville ancienne. Approche historique et critique de ses projets belges dans une perspective internationale
Houbart, Claudine ULg

Doctoral thesis (2015)

The specialised centre for conservation of the KU Leuven wears his name. Raymond M. Lemaire (1921-1997), art historian, is unanimously and internationally considered as one of the key figures of heritage ... [more ▼]

The specialised centre for conservation of the KU Leuven wears his name. Raymond M. Lemaire (1921-1997), art historian, is unanimously and internationally considered as one of the key figures of heritage conservation in the second half of the twentieth century. His name is immediately associated to the writing of the Venice charter, the foundation of ICOMOS or Unesco missions such as the restoration of the Acropolis or the Borobudur temples. But his work in Belgium, in the field of urban renovation is to a great extend ignored, with the exception of the Great beguinage of Leuven. Starting from Lemaire's personal archives, handed over to the KU Leuven after be became professor emeritus in 1991, our study aims at revealing his vision of urban rehabilitation, on the basis of microhistorical case-studies mostly situated in Brussels and of his contributions to the elaboration of an appropriate doctrine for the renovation of city centres. Considering this vision in relation with his practice in the field of urbanism, well illustrated by the planning of Louvain-la-Neuve, has lead us to see in Raymond M. Lemaire an updating of the "integral architect", an essential concept formulated by Gustavo Giovannoni at the beginning of the twentieth century. [less ▲]

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See detailImproving the performance of μ-ORC systems
Declaye, Sébastien ULg

Doctoral thesis (2015)

This thesis contributes to the knowledge and the characterization of micro Organic Rankine Cycles (ORC). It is based on experimental data and simulation models. An oil-free scroll expander is tested in a ... [more ▼]

This thesis contributes to the knowledge and the characterization of micro Organic Rankine Cycles (ORC). It is based on experimental data and simulation models. An oil-free scroll expander is tested in a wide range of operating conditions in order to better characterize its performance. Particular attention is paid to the tightness of the machine which is obtained using a magnetic coupling. The measured isentropic efficiency reaches 75% which is higher than typical values reported in the literature. From the experimental results, a performance map of the expander is generated. This performance map can be used to provide fast and accurate calculation of the volumetric and isentropic performance of the expander in a wide range of operating conditions. Five displacement pumps adapted to μ-ORC systems are also tested. These pumps are diaphragm, piston, plunger and gear types. The measured values include the overall efficiency, the volumetric efficiency and the NPSH. A deep analysis of the performance is performed to quantify the losses of each pump, of their electric motor and of their frequency drive. This analysis shows that the weakness of the overall effectiveness (max. 46%) of the pumps tested is mainly due to the low efficiency of the electric motor. A semi-empirical model of the diaphragm pump is proposed and validated based on manufacturer data. This model can predict the mechanical power of the pump and the flow delivered with a good accuracy. The simulation models developed for the expander and the pump are used to simulate a configuration including the pump, the generator and the expander on a single shaft. This configuration aims to avoid the use of a motor and a frequency drive whose performance is poor in the range of power consumed by the pump of a μ-ORC system. The results show a significant increase in the net power produced using the integrated configuration Finally, performance of a prototype of μ-ORC suitable for recovering heat from a two-stage screw compressor are measured and analyzed. The prototype allows generating maximum 3.9% of the electrical power consumed by the compressor. Several optimization options of the prototype are evaluated numerically, showing that the power generation could be increased up to 5.4% of the compressor consumption. These options include using the integrated configuration and optimizing the intercooler boiler design. [less ▲]

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See detailManaging the carnivore comeback: assessing the adaptive capacity of the Eurasian lynx (Lynx lynx) to cohabit with humans in shared landscapes
Bouyer, Yaëlle ULg

Doctoral thesis (2015)

Conflicts between humans and large carnivores are one of the most visible examples of the challenges that arise when seeking to achieve coexistence between humans and wildlife. With their large spatial ... [more ▼]

Conflicts between humans and large carnivores are one of the most visible examples of the challenges that arise when seeking to achieve coexistence between humans and wildlife. With their large spatial requirements and predatory behavior, large carnivores are among the most difficult species to preserve in our modern day landscapes. Although large carnivores are usually considered as the epitomes of wilderness, because of human population growth and habitat fragmentation they are inexorably and increasingly faced with the need to live in human-modified landscapes. As a direct consequence, conflicts over depredation on livestock, competition for game species and sometimes over human injury or death will only increase if clear management measures are not taken. This is particularly true in Europe, where, after many decades of absence, large carnivores are recolonizing areas where millions of people are present and where landscapes have been drastically modified. Two approaches to integrating wildlife into a human-dominated world have been proposed at an international scale. The first solution is called land sparing, in which wildlife lives exclusively in protected or wilderness areas where contact between animals and humans will be reduced to the minimum. The second solution, called land sharing, proposes to integrate human activities and wildlife in the same landscapes in non-protected interface zones in what is often called a coexistence approach. In a context of scarce true wilderness areas and a continuum of human-modified habitats, land sharing (i.e. the coexistence approach) is seen as the only possible approach valid for Europe. While a coexistence approach can be readily implemented with smaller species, it can represent a major challenge for species with large space requirements and with predatory behavior. To help manage these species in a long-term conservation vision and to predict where potential conflicts could arise between humans and carnivores, information on large carnivores and their habitat use in anthropogenic landscapes is a pre-requisite. With the return of Eurasian lynx Lynx lynx in Western Europe, the most densely populated areas of the continent_ information on the species tolerance to human land use will help predict where it is likely to occur in anthropogenic landscapes. Data collected in Scandinavia over 15 years were used to assess the use of landscape by lynx. In this study, we explored the effect of anthropogenic and environmental factors on Eurasian lynx habitat use in Scandinavia. The work was developed along two main axes. The first axis aims to explore large scale potential patterns of lynx distribution through transferability of results obtained from habitat modelling to geographically different areas. Transferability of results was tested in two steps. Firstly, transferability success (i.e. predictive ability of the map) was tested at a regional scale using data on roe-deer, the main prey of lynx, to create a map of relative distribution and abundance of prey in southeastern Norway (Chapter 1). Secondly, transferability success was assessed at a larger extent and using data obtained from different sampling method (Chapter 2). A habitat suitability map for Eurasian lynx was produced to be used in management planning in geographically differentiated lynx management zones in Scandinavia. The results indicated that transferability of results from one region to an ecologically different region must be taken with caution. Nevertheless, the habitat suitability maps we constructed on the basis of extrapolation are a valuable asset to help management of the Scandinavian lynx population. The second axis deals with lynx habitat use in relation to anthropogenic and environmental predictors. Lynx tolerance to human presence was first explored by looking at the orientation of home range in the landscape, taking into account proxies of human presence (Chapter 3). Values of these proxies were compared both inside home ranges and within a buffer surrounding the home ranges for several lynx inhabiting an anthropogenic gradient going from near-wilderness to urban periphery. Results showed a high diversity in the extent to which individual lynx are exposed to human influence, indicating that lynx are highly adaptable in terms of living space. Lynx seemed to be able to orientate their home range in order to avoid highest human impacts and select for areas of medium human impacts. Building on these results, finer scale information on lynx habitat use in an anthropogenic landscape were obtained taking into consideration different types of behavior (day-beds, moving and killing) displayed by adult lynx, as well as the effect of cumulative anthropogenic pressures on habitat selection (Chapter 4). Our results showed that lynx select for areas with medium levels of human modification, avoiding both the areas with highest and least modification. Females in general appear to be less tolerant to human modification than males, especially for day-beds. Our study shows that Eurasian lynx can be considered as a species that is adaptable to human- induced changes in landscape even if its motivation to tolerate human presence is clearly linked to the presence and density level of its main prey, the roe deer. Our work shows that, contrary to much of the public and many conservation professionals’ opinions, land sharing with large carnivores in Europe may be possible – even in the immediate proximity to urban centers. However, it is important to bear in mind that these results were obtained from countries with a relatively low human population density; even though some individuals observed lived in the periphery of large cities, the level of habitat fragmentation is less severe than in most of Western Europe. In order to properly assess the capacity of Eurasian lynx to live in highly populated areas, such as the Benelux, more detailed information on lynx distribution from continental European will be needed. However, our results underline the value of combining both correlational and mechanistic studies, and the need for caution in extrapolating data too far from its original context. As large carnivore recovery continues to progress in Europe we may not yet have seen the limits of these species' abilities to adapt. [less ▲]

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See detailContributions to combinatorics on words in an abelian context and covering problems in graphs
Vandomme, Elise ULg

Doctoral thesis (2015)

This thesis dissertation is divided into two (distinct but connected) parts that reflect the joint PhD. We study and we solve several questions regarding on the one hand combinatorics on words in an ... [more ▼]

This thesis dissertation is divided into two (distinct but connected) parts that reflect the joint PhD. We study and we solve several questions regarding on the one hand combinatorics on words in an abelian context and on the other hand covering problems in graphs. Each particular problem is the topic of a chapter. In combinatorics on words, the first problem considered focuses on the 2-regularity of sequences in the sense of Allouche and Shallit. We prove that a sequence satisfying a certain symmetry property is 2-regular. Then we apply this theorem to show that the 2-abelian complexity functions of the Thue--Morse word and the period-doubling word are 2-regular. The computation and arguments leading to these results fit into a quite general scheme that we hope can be used again to prove additional regularity results. The second question concerns the notion of return words up to abelian equivalence, introduced by Puzynina and Zamboni. We obtain a characterization of Sturmian words with non-zero intercept in terms of the finiteness of the set of abelian return words to all prefixes. We describe this set of abelian returns for the Fibonacci word but also for the Thue--Morse word (which is not Sturmian). We investigate the relationship existing between the abelian complexity and the finiteness of this set. In graph theory, the first problem considered deals with identifying codes in graphs. These codes were introduced by Karpovsky, Chakrabarty and Levitin to model fault-diagnosis in multiprocessor systems. The ratio between the optimal size of an identifying code and the optimal size of a fractional relaxation of an identifying code is between 1 and 2 ln(|V|)+1 where V is the vertex set of the graph. We focus on vertex-transitive graphs, since we can compute the exact fractional solution for them. We exhibit infinite families, called generalized quadrangles, of vertex-transitive graphs with integer and fractional identifying codes of order |V|^a with a in {1/4,1/3,2/5}. The second problem concerns (r,a,b)-covering codes of the infinite grid already studied by Axenovich and Puzynina. We introduce the notion of constant 2-labellings of weighted graphs and study them in four particular weighted cycles. We present a method to link these labellings with covering codes. Finally, we determine the precise values of the constants a and b of any (r,a,b)-covering code of the infinite grid with |a-b|>4. This is an extension of a theorem of Axenovich. [less ▲]

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See detailIchtyofaune du bassin du fleuve Mono (Bénin et Togo): diversité, écologie et impacts anthropiques
Lederoun, Djiman ULg

Doctoral thesis (2015)

This study has three main objectives: (1) to obtain an inventory of the ichthyofauna of the Mono River that is as complete as possible; (2) to study the ecology of this ichthyofauna; and (3) to document ... [more ▼]

This study has three main objectives: (1) to obtain an inventory of the ichthyofauna of the Mono River that is as complete as possible; (2) to study the ecology of this ichthyofauna; and (3) to document the impact of fishing on the exploited stocks based on two targeted species. The inventory was made by compiling the literature, by studying collections of museums and of other institutions and by several sampling campaigns, conducted between February 2011 and March 2014. This resulted in an inventory of 91 fish species belonging to 67 genera, 42 families and 14 orders. The Perciformes (31 species), Siluriformes (18), Osteoglossiformes (10), Cypriniformes (9) and Characiformes (9) are the most diverse families in the Mono River Basin. The most species-rich families are the Cichlidae (9 espèces), Cyprinidae (9), Mormyridae (7), Clariidae (7) and Alestidae (6). Twenty-nine species, of which 7 of freshwater and 22 of marine or estuarine origin have been added to the ichtyofauna as known before this study. Nine species present in museum collections and three species only known from the literature have not been collected again. Several taxonomic problems have been encountered. Two of these cases were studied in depth. Foremost, the taxonomic status of Brycinus leuciscus and B. luteus (Alestiidae, Characiformes) was revised based on specimens originating from the complete distribution range of the two nominal species. This allowed us to synonymise the two species, with Brycinus leuciscus as senior synonym. The latter has been erroneously mentioned from the Mono River. Our results, however, confirmed the presence of two phenotypes, i.e. one with and one without a pre-dorsal hump, which was mentioned in the literature as intra-specific variation in B. leuciscus. A comparative study comparing specimens belonging to 'Barbus' nigeriensis (Cyprinidae, Cypriniformes) of the Mono Basin with those originating from the basins of the Volta, the Ogun et the Niger revealed the presence of a new species, described as Barbus "Vandewalle", a Volta Basin endemic. An indentification key of the different families, genera and species from the Mono Basin is presented. For the ecological study, two seasonal sampling campaigns were performed (from December to mid-March and from mid-July to mid-September) in 2012 and 2013 using gill nets of different mesh-size (10, 12, 17, 20 et 22 mm knot to knot). Sampling was performed at 10 sampling sites that were located upstream and downstream of the Adjarala Falls (the site of a planned hydroelectric plant, 100 km upstream of that of Nangbéto) and upstream and downstream of the dam at Nangbéto. Seventeen physico-chemical and environmental variables were taken at these sites. The ordination of the sampling sites in relation to their values for the physico-chemical, environmental variables and to their fish assemblages was studied using a non-linear method: the self organising map (SOM). The samples were scattered in four groups in function of their physico-chemical and environmental variables. The distance to the source, height of the canopy, rocks, coverage of the canopy, altitude, gravel, mud, sand, water velocity and dissolved oxygen were the most discriminating factors for the obtained groups. The zone of the Adjarala, where a new dam will be constructed, differs by its rocky substrate, the velocity of the water and the relatively high amount of dissolved oxygen. For the ichthyofauna, the SOM suggest a structuring in three groups. Our results oppose the tendency to homogeny in the middle course of rivers, which is probably due to the presence of the dam at Nangbéto. A significant correlation was found between the distribution of the species and the physico-chemical and environmental parameters. The distance to the source, altitude, forested river banks, height of the canopy, velocity of the water, conductivity, transparency and pH were the parameters that explained the distribution of the fish community best. The level of disturbance of the ecosystem, which was studied using the Abundance Biomass Comparison (ABC) showed that the zones at and near the dam at Nangbéto were the most stressed. A length-weight and length-length key was designed for the first time for the 37 species that were the most abundant in the catches. This was done in order to improve the quality of the fisheries statistics collected by fisheries officers on the scale of the basin. The analysis of the allometric coefficient b of the length-weight relation showed that the majority of the fishes had an allometric growth. The condition factor calculated in order to estimate the amount of flesh on the fish showed that the environment was heavily disturbed. To conclude, from the results of the study on the impact of the fisheries on targeted species, it became clear that the population of Sarotherodon melanotheron melanotheron is over-exploited at Lake Toho. At Lakes Doukon and Togbadji, on the other hand, an under-exploitation of the population of S. galilaeus galilaeus was observed. The latter illustrates the possibility of sustainable management even in the presence of intensive fishing pressure. As, in this thesis, several cases of anthropogenic impacts were identified, a regular surveillance programme will be paramount in order to preserve the ichthyological diversity of the Mono River Basin. [less ▲]

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See detailSupervised inference of biological networks with trees : Application to genetic interactions in yeast
Schrynemackers, Marie ULg

Doctoral thesis (2015)

Networks or graphs provide a natural representation of molecular biology knowledge, in particular to model relationships between biological entities such as genes, proteins, drugs, or diseases. Because of ... [more ▼]

Networks or graphs provide a natural representation of molecular biology knowledge, in particular to model relationships between biological entities such as genes, proteins, drugs, or diseases. Because of the effort, the cost, or the lack of the experiments necessary to the elucidation of these networks, computational approaches for network inference have been frequently investigated in the literature. In this thesis, we focus on supervised network inference methods. These methods exploit supervised machine learning algorithms to train a model for identifying new interacting pairs of nodes from a training sample of known interacting and possibly non-interacting pairs and additional measurement data about the network nodes. Our contributions in this area are divided into three parts. First, the thesis examines the problem of the assessment of supervised network inference methods. Indeed, their reliable validation (in silico) poses a number of new challenges with respect to standard classification problems, related to the fact that pairs of objects are to be classified and to the specificities of biological networks. We perform a critical review and assessment of protocols and measures proposed in the literature. Through theoretical considerations and in silico experiments, we analyze in depth how important factors influence the outcome of performance estimation. These factors include the amount of information available for the interacting entities, the sparsity and topology of biological networks, and the lack of experimentally verified non-interacting pairs. From this analysis, we derived specific guidelines so as to how best exploit and evaluate machine learning techniques for network inference. Second, we systematically investigate, theoretically and empirically, the exploitation of tree- based methods for network inference. We consider these methods in the context of the two main generic classification-based approaches for network inference: the local approach, which trains a separate model for each network node, and the global approach, which trains a single model over pairs of nodes. We present and formalize these two approaches, extending the former for the prediction of interactions between two unseen network nodes, and discuss their specializations to tree-based methods, highlighting their interpretability and drawing links with clustering techniques. Extensive experiments are carried out with these methods on various biological networks that clearly highlight that these methods are competitive with existing methods. The interpretability of the resulting method family is illustrated on a drug-protein interaction network. In the last part of the thesis, we built on the experience gained in the two previous parts to try to predict at best the genetic interaction network in yeast S.cerevisiae. For that purpose, we collected a large dataset, assembling 4 millions gene pairs that were experimentally tested in the context of 11 different studies and 23 sets of measurements to use as gene input features for the inference. Through several cross-validation experiments on the resulting dataset, we showed that predicting genetic interactions is indeed possible to some useful extent and that actually in some settings, the accuracy of computational methods is not very far from that of experimental techniques. [less ▲]

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See detailCondições Semióticas da Repetição
Lindenberg Lemos, Carolina ULg

Doctoral thesis (2015)

Emanating from different areas of the human sciences, repetition was given a central role in this thesis of semiotic inclination. It is a widespread phenomenon in all fields of human activity and ... [more ▼]

Emanating from different areas of the human sciences, repetition was given a central role in this thesis of semiotic inclination. It is a widespread phenomenon in all fields of human activity and, particularly, in texts. The optional character of certain repetitions in texts brings about the problem of its function, since, in certain cases, it seems to act directly on the rhythm of the content and the flow of entrances and exits of the phenomenal field. This regulation of the rhythm divides the research into two fronts. On the one hand, the rhythmic effect points to an underlying structure. In that sense, one can ask: what is the configuration of such structure? In what way is repetition part of it? Or even, what is its place in the semiotic model? On the other hand, repetition seems to involve a certain degree of contradiction: in what way can a phenomenon that brings no novelty, only the resumption of the same, sometimes create an effect of tension or surprise? In order to answer these questions, we undertake the revision of the role of repetition in neighboring fields: rhetoric and a specific trend in linguistics. This discussion has allowed us to detect a few insufficiencies in these approaches that may be answered by semiotics. From the semiotic perspective, we have explored the place occupied by repetition, by opposing it to concepts such as identification, text, language and to the notion of semiotics itself. Once the position of repetition in the text is established, we move on to note and discuss the textual conditions necessary to the occurrence of relevant repetitions. In addition to identification, the notion of salience, based on the opposition between figure and ground, revealed itself to be central to the explanation of the phenomenon. Finally, linearity has also proven relevant, which allowed us to re-discuss its theoretical status as one possible manifestation of the underlying syntagmatic structure. Having outlined the conditions for repetition, we have started an investigation into the somewhat contradictory effects we had observed in repetitive incidents. We saw that repetition belongs to the order of extent – it is counted, not measured – and, in being so, it is a tool for the manifestation of the rhythm of the content that is presupposed by it. In these terms, repetition is subordinated to the intensive sub-dimensions: tempo and tonicity. To ensure the relevance of our arguments, we studied repetition within some selected objects, where it is made to serve of the text. Finally, the analysis of these objects shed light on the relations between repetition and the concept of aspect, and three styles of textual progression related to repetition were confirmed: circular, linear and spiraling. This path of investigation has shown us the terms which repetition is tied to and the way in which it manifests an underlying structure. It has also revealed that such structure not only explains but also generates the variations in rhythm and tempo that are felt through repetition. The apparent contradictions of the effects of repetition are explained by the very epistemological bases of the field. The analytical and relational aspects of semiotics are the basis for repetitive construction, which, without adding any new information, may lead the enunciatee to tension, climax and surprise. [less ▲]

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See detailExploitation optimale des lignes électriques aériennes à haute tension par évaluation en temps réel de la flèche des conducteurs et du vent agissant sur la portée
Godard, Bertrand ULg

Doctoral thesis (2015)

[Abstract] The primary concern with the electrical loading of high-voltage overhead lines is ground clearance, which depends on several factors, including constantly varying weather parameters. Sagging of ... [more ▼]

[Abstract] The primary concern with the electrical loading of high-voltage overhead lines is ground clearance, which depends on several factors, including constantly varying weather parameters. Sagging of the conductor, the main safety criteria, is due to (thermal) expansion of the line, a complex function of air temperature, solar radiation, local wind and actual current. A patented (patent US 8184015B2) method (based on a smart sensor named AmpacimonTM attached directly to an overhead line conductor) to directly measure the sag of overhead transmission line conductors is described. The main advantage of the concept is the real time direct measurement of the sag needed for the operation of the transmission or distribution system without the need for any additional and intermediate data, such as for example load, topological data, conductor tension, conductor temperature, and ambient weather conditions. The sag is determined by analyzing the conductor's vibrations, detecting the span's frequencies of vibrations. The fundamental frequencies form the exact signature of the span. Exterior conditions such as load, weather, topology, suspension movement, creep and the presence of snow and ice affect the sag, and, therefore, are automatically incorporated into the frequency of vibrations. Thus, this method is a direct sag evaluator compared to other methods that determine the sag based on conductor temperature or conductor tension measurements and inferences about other parameters (mass of conductor, span length,…). Moreover, sensor and method does not need to be calibrated, as the sag is deduced from the detected frequencies and not from signal amplitude. Completed field tests have confirmed that the method (and sensor) gives appropriate and highly accurate sag measurements (less than a 20 [cm] margin of error). The wind speed has a dramatic impact on power line ampacity as it is the main variable responsible for cooling down the conductor, and hence for the sag value. However, a single-spot measurement does not allow knowing the global effect of the wind over the whole span, in particular for low wind speeds (typically for wind speeds whose component perpendicularly to the conductor axis lower than 2-3 [m/s]) which are dramatic for ampacity (ampere capacity) determination. A patented (patent WO 2014090416 A1) direct method (based on a smart sensor named AmpacimonTM attached directly to an overhead line conductor) for measuring a perpendicular wind speed component with respect to a suspended cable span is presented. Appropriate data analysis coupling conductor's motion frequency detection, Strouhal equation and swing angle measurement gives a full picture of any wind speed. As the cable moves as a whole, the presented method provides a value which is representative of the mean perpendicular wind speed effect along the entire suspended cable span. In the past, the difficulty of predicting weather parameters and sag has resulted in conservative assumptions to ensure public safety and power-system security. If transmission system operators are to increase the use of the overhead line circuits' load-transfer capacity while ensuring the regulatory clearances above ground are maintained, they need a system that determines the available real-time load-transfer capacity, conductor sag (and perpendicular wind speed) by direct measurement, without the need to factor in unreliable parameters. The methods and system presented in this work will open new insights to power system network management in many aspects, from congestion management to preventive maintenance. [less ▲]

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See detailETAT DE LIEU DE LA FILIERE APICOLE EN REPUBLIQUE DEMOCRATIQUE DU CONGO ET EVALUATION DES CAPACITES POLLINISATRICES DES ABEILLES DOMESTIQUES (Apis mellifera adansonii, L.) SUR LA CULTURE DE MELON AFRICAIN (Cucumeropsis mannii Naudin) A KISANGANI.
Posho Ndola, Boniface ULg

Doctoral thesis (2014)

La présente étude s’inscrit dans le cadre de la recherche d’une meilleure compréhension de la filière apicole en RDC, de l’influence de l’environnement sur la qualité de pains d'abeille et de miel pour la ... [more ▼]

La présente étude s’inscrit dans le cadre de la recherche d’une meilleure compréhension de la filière apicole en RDC, de l’influence de l’environnement sur la qualité de pains d'abeille et de miel pour la survie d’Apis mellifera adansonii, L. 1758 en RDC et de l’impact de la pollinisation des abeilles introduites (A. mellifera adansonii, L. 1758) sur la production de Cucumeropsis mannii (Naudin) à Kisangani. Trois approches ont été adoptées pour faire l’état de lieu de la filière apicole en RDC, dont (1) la distribution des questionnaires structurés aux apiculteurs, (2) des visites de ruchers et (3) des recherches documentaires. Dans le cadre de l’évaluation de la qualité de miels et pains d’abeilles, les échantillons de miels et de pollens ont été collectés dans trois sites écologiquement différents de la RDC. Les échantillons de miels ont été évalués suivant les critères et les protocoles établis par Codex Alimentarius; tandis que les pollens ont été évalués suivant les critères de teneur en protéines et en acides aminés essentiels. Les teneurs en protéines et en acides aminés essentiels de pains d’abeilles collectés ont été déterminées respectivement par la méthode Kjeldahl et par les hydrolyses acides et basiques. Les essais comparatifs de la pollinisation des abeilles domestiques ont été également conduits dans deux sites expérimentaux à Kisangani. Sur chaque site, deux champs d'un hectare séparés de 3 kilomètres ont été installés. Deux colonies d'abeilles ont été installées au milieu du champ expérimental de chaque site pendant la floraison (quand 10 % des plantes ont fleuri). Le second champ expérimental, sans colonies d’abeilles, a été considéré comme témoin. Les résultats obtenus après l’étude exploratoire sur l’apiculture en RDC montrent que l’apiculture congolaise reste encore semi traditionnelle; 54 % des apiculteurs congolais travaillent en coopérative; 100 % du cheptel apicole congolais est constitué d’A. mellifera adansonii, L. ; 96 % des apiculteurs utilisent les ruches Kenyanes; le nombre de ruches utilisé par un apiculteur congolais varie entre 2 et 120; la production d’une colonie par récolte oscille entre 1 et 25 litres de miel; la production annuelle par apiculteur est évaluée entre 10 et 900 litres de miel, le nombre de récoltes de miel effectué par an varie de 1 à 2. Cette étude a révélé que la teneur moyenne en protéines de pollens recueillies en RDC était 14,11 ± 5,27 %. Cette teneur en protéines était faible comparativement aux besoins alimentaires des abeilles en Europe. Tous les échantillons de pollen étaient constitués de dix acides aminés essentiels et leurs concentrations étaient dans la fourchette optimale des exigences alimentaires des abeilles en Europe. Les analyses des échantillons de miels ont révélé que la teneur en sucres réducteurs des échantillons de miel recueillies variait de 63,40 à 73,80 %, la teneur en saccharose était comprise entre 0,30 et 1,90 %, la teneur en eau oscillait entre 16,80 et 22,00 %, le pH des échantillons de miel analysés variait de 4,22 à 4,53, la moyenne de la conductivité électrique de miels récoltés a été ( 47,74 ± 13,93 ) S/cm et la concentration de HMF varié de 1,75 à 31,38 mg / kg de HMF miel. Les miels et les pollens collectés dans la forêt tropicale de Kisangani étaient moyennement plus nutritifs pour les abeilles que ceux de la savane de Kavwaya. Après les observations des essais comparatifs de pollinisation, il a révélé que la pollinisation des abeilles introduites a amélioré significativement le nombre de graines par fruit de 83,78 %, tandis que le nombre de fruits par plante et le poids de graines par fruit ont été améliorés respectivement de 422,89 % et 185,61 % par rapport au témoin. La taille de graine a été positivement influencée par la présence de colonie d’abeille dans le champ de C. mannii (Naudin). Dans cette étude, la distance par rapport aux ruches et l’orientation de vol des ouvrières n'ont pas influencé significativement le rendement et la taille des graines de C. mannii (Naudin) [less ▲]

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See detailToward a Consistent Application of International Financial Reporting Standards (IFRSs) across Companies and Countries
Yammine, Mira ULg

Doctoral thesis (2014)

International Financial Reporting Standards (IFRSs) were developed to be a single set of high-quality globally accepted accounting standards. They are meant to allow uniformity in financial reporting ... [more ▼]

International Financial Reporting Standards (IFRSs) were developed to be a single set of high-quality globally accepted accounting standards. They are meant to allow uniformity in financial reporting, enhance comparability of financial statements in the midst of economical globalization, and allow companies with international subsidiaries to prepare their financial statements using similar global standards. The objective of the dissertation is to study whether the application of IFRSs is consistent across companies and countries; in particular we tackle the following two questions: -Does the application of IFRSs in the preparation of financial statements lead to consistency? -Does the public enforcement of accounting standards impact the consistent application of IFRSs? To answer the first question we have addressed standard IAS 36 that was developed by the International Accounting Standards Board (IASB) and covering impairment of assets. We found that managers’ opportunism still has an impact on the impairment of assets recognition and magnitude when taking impairment decisions. To address the second question, a survey covering enforcement of accounting standards activities was prepared and sent to public enforcement bodies in a number of countries mandating the adoption of IFRSs. The survey allowed us to construct an index that represents the activities of the public enforcement bodies. We studied the impact of public enforcement on specific applications of the standards, the results show a decrease in earnings management in countries with effective public enforcement. [less ▲]

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See detailGathering and Handling of Granular Materials under Microgravity Conditions
Opsomer, Eric ULg

Doctoral thesis (2014)

When a granular material is driven in microgravity environment, one can assist to the formation of dense and slow regions in the system. Indeed, given the dissipative character of the collisions in the ... [more ▼]

When a granular material is driven in microgravity environment, one can assist to the formation of dense and slow regions in the system. Indeed, given the dissipative character of the collisions in the media, energy is lost at each particle interaction and the grains begin to clump locally. The phenomenon has been observed for the first time in the late nineties during sounding rocket experimentation by Falcon and his coworkers and has attracted the interest of many scientists since then. However, precise laws describing the formation and the dynamics of such clusters are still lacking. In order to allow an intensive study of the phenomenon, the European Space Agency set up the SpaceGrains project. Small bronze spheres are enclosed in a rectangular cell and vertically driven by to pistons oscillating in phase opposition. Our work consists in the preparation of the SpaceGrains experiment via molecular dynamics simulations and the elaboration of models predicting the behaviour of the system. Before we started our study concerning SpaceGrains, we reproduced and extended Falcon’s sounding rocket experiments. We showed that, in addition to the granular gas and the cluster, another dynamical regime can be observed in the system. Indeed, for higher filling fractions, the entire granular media behaves like one single completely dissipative particle called the bouncing aggregate. Bouncing modes are observed and can be explained considering the bouncing ball paradigm. Moreover, we highlighted the role of the packing fraction φ as well as the size of the particles R on the different observed dynamics. Within the frame of the SpaceGrains device, we studied the impact of all tunable parameters of the experiment on the dynamics of the system. Thanks to an appropriate scaling all transition points that we obtained by varying the driving amplitude A, the packing fraction and the dimen- sions of the cell L fall along a same theoretical curve. The latter is explained regarding the energy transfer from the piston towards the center of the cell. Once the clustering was controlled, we investigated the handling of the agglomerate. By compartmentalizing the container, local trapping can be achieved and a granular pendant of Maxwell’s demon can be observed in microgravity. Based on the measured particle flux between the compartments, we realized a theoretical model predicting the asymptotic steady state of the system depending on the total number N of particles. In a clustered system, we investigated the impact of asymmetrical driving on the system’s dy- namics. We showed that the mean position of the cluster can be fully controlled via the amplitude ratio a. Moreover, the natural fluctuations of the agglomerate around its equilibrium position are dictated by the driving frequency f and the mass of the cluster. Finally, we realized simulations of driven bi-disperse gases and investigated the segregation phenomena in the system. We showed that clustering and segregation are strongly linked and that the size and the mass of the particles impact the segregation dynamics in different ways. [less ▲]

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See detailEtude de l'assainissement non collectif en Afrique Subsaharienne : Application à la ville de Bujumbura
Bigumandondera, Patrice ULg

Doctoral thesis (2014)

Summary On-site sanitation sector in sub-Saharan African is a complex area that requires the involvement of a multidimensional approach mobilizing various actors and competencies. The main purpose of this ... [more ▼]

Summary On-site sanitation sector in sub-Saharan African is a complex area that requires the involvement of a multidimensional approach mobilizing various actors and competencies. The main purpose of this thesis is to conduct a study integrating the three links in the sanitation chain that compose the on-site sanitation sector, namely the upstream links regarding sanitation facilities installed at private homes, the intermediate link for evacuation of sludge and transport to a treatment site and the downstream link for disposal and treatment sludge. A sociological approach mobilizing both survey techniques and on-site observation has allowed understanding the on-site sanitation practices in the field of developing countries. Methodologies to initiate corrective action with respect to what is done so far are utilized. Such as a method for evaluating on-site sanitation using an indicator that is a combination of indicators developed taking into account the entire sanitation sector. At the same time, a procedure to select sanitation technologies based on a number of criteria was adopted. The proposed technologies as well as criteria used for their implementation follow the same logic as previously, i.e. that consisting of taking into account the entire sanitation sector. This study also examined the design procedure of the septic tank and of evaluated its performance on site given that it is used in many sanitation systems. Settling column tests were carried out show that the effluent who enters in the septic tank settles well but settable solids remain in the effluent leaving the septic tank remaining, parameter that needs to be taken into account in the establishment of the infiltration bed after the septic tank. Quantification of sludge accumulation rates in the septic tank shows that for a pump out period every 4 years, the design can be based on an average sludge accumulation rate of 0.22L/person/day. These values (as expressed in g COD/person/day) are useful both to assess withdrawal, but also to design sludge's disposal site. Analyses of these sludges reveal a poorly biodegradable product with a non-biodegradable COD fraction reaching 47.5%, thus as a product with a low methanogenic potential, limiting the interest of its application in anaerobic digestion as a substrate. But, their co-treatment with organic solids waste in a partial anaerobic co-digestion process followed by composting. In this case sludges are considered as digestion inoculums. Preliminary results are encouraging, particularly in terms of total time needed for the entire process. Among other advantages, this process reduces handling of the waste being processed and provides two end products directly recoverable: compost and methane. So we hope that this research will contribute to the establishment in African countries for more efficient on-site sanitation, able to meet the targets set by international organizations. [less ▲]

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See detailEtude et Modélisation de la contribution des macrophytes flottants (Lemna minor) dans le fonctionnement des lagunes naturellles
Tangou Tabou, Thierry ULg

Doctoral thesis (2014)

Waste stabilization ponds (WSP) are widely used in the treatment of domestic and industrial wastewaters in industrialized countries and in developing countries including the Democratic Republic of Congo ... [more ▼]

Waste stabilization ponds (WSP) are widely used in the treatment of domestic and industrial wastewaters in industrialized countries and in developing countries including the Democratic Republic of Congo. Several organisms (e.g., bacteria, algae, protozoa, and aquatic plants) are involved in the treatment process occurring in the WSP. Therefore, the performance of such systems strongly depends upon the management of the existing macrophytes (or at least the management of the most dominant species). Indeed, large biomass coverage of floating macrophytes can induce several dysfunctions within the ponds (e.g., second pollution due to the death and the settling of the macrophytes, difficulties in harvesting valuable biomass for animal feeding or pharmaceutical purposes, etc.) and can threaten the surrounding ecosystems (i.e., fauna and flora) through the releases of partially or unpurified waters. This study aimed at investigating the contribution of floating macrophytes, namely that of duckweed (Lemna minor), which are the most common species, in the functioning of natural WSP. Specifically, the objectives were: (i) the modeling of the growth kinetics of Lemna minor based on the key environmental influencing factors (nutrients concentrations, light intensity, pH, temperature); (ii) the characterizations of the stoichiometry of the growth of Lemna minor and the gas/liquid transfers in the ponds; and (iii) the set-up of a mathematical model, i.e. the MLLE (Modèle de Lagunage par Lentilles d'eau) through the mass balances approach based on the Petersen’s matrix. The study of the growth kinetics of L. minor was carried out in a growth chamber (phytotron) using a pilot involving initial fresh L. minor biomass and different set of concentrations in nutrient nitrogen (N) and phosphorus (P), light intensity, pH, and temperature. The growth was monitored using the gravimetric methods and digital images processing. The results showed that the growth of L. Minor was optimum for concentrations of N and P of circa 10 mg N-NH4+.L-1 and 1 mg P-PO43-.L-1, respectively, with a maximum growth rate of approximately 0.09 j-1. However, the growth decreased progressively when the respective concentrations of N and P reached approximately 16 mg N-NH4+L-1 and 6 mg P-PO43-.L-1. A possible inhibition due to the excess of substrates might be the cause of such decrease. Moreover, a light intensity greater than 450 μmol.m-².s-1 was potentially harmful for L. minor surviving (growth rate dropped by 60%), though the mortality rate was low (< 0.05 j-1). Characterizing the stoichiometry of L. minor resulted in the formulation of the plant biomol (C88H163O70N10P) and the description of biochemical processes occurring within the ponds, as well as the determination of the conversion rates substrate-biomass in each of these processes. The Lavoisier's principle (conservation of the matter) also was confirmed for the stoichiometric relationship developed for chemical oxygen demands through our experiments. Furthermore, the aeration test assays revealed the influence of the biomass coverage on the gaz/liquid transfers parameters. An exponential decrease of the transfer coefficients, the oxygenation capacity and hourly inputs was associated with increasing coverage rates in both absence and presence of plants. The hypothesis of a main release (about 80%) of oxygen (consumption of carbon dioxide) toward the atmosphere was also confirmed. The third fold of our study was then undertaken based on our findings on the biochemical processes (kinetics and stoichiometry of growth and mortality of plants) and findings on physical processes (gas/liquid transfer) occurring in WSP. A mathematical model, the MLLE, was thus developed and its validity assessed through the equilibrium of the Petersen's matrix. The impact of key nutrients (i.e., nitrogen and phosphorus) on the growth of duckweed, along with the influence of the release of oxygen (consumption carbon dioxide) by the floating macrophytes (L. minor) can be, therefore, thoroughly assessed based on the state variables of the model. Additional simulations using the West® (World Wide Engine for Simulation, Training and Automation) software could help in further calibrating and/or validating the MLLE, and guide in its implementation for industrial purposes. Keywords: Lemna minor, biomass, image processing, nutrient, biomole, gas/liquid transfer, model [less ▲]

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See detailContribution to the epidemiology of bovine brucellosis in Ivory Coast
Sanogo, Moussa ULg

Doctoral thesis (2014)

Bovine brucellosis is an endemic infectious disease which can negatively impact on cattle productivity and welfare as well as on human health. In many developing countries such as Ivory Coast, there is a ... [more ▼]

Bovine brucellosis is an endemic infectious disease which can negatively impact on cattle productivity and welfare as well as on human health. In many developing countries such as Ivory Coast, there is a need for knowledge on the distribution and the frequency of the disease (or evidence of its presence) within the animal population and the possible factors associated with the disease. Information is also needed on species and biovars of Brucella at national and regional scales, on the performance of commonly used diagnostic tests for accurate estimation of the true disease prevalence, and on determination of risk factors associated with the disease. These informations are of key importance to set up and implement appropriate and efficient prevention and control measures against brucellosis. For these reasons, the research presented in this thesis aimed to contribute to a better understanding of the epidemiology of bovine brucellosis in Ivory Coast. The thesis is structured into three main parts. The introduction part includes three chapters. The first chapter presents an overview of the literature on the pathogen causing brucellosis, their characteristics and distribution. The impact and the existing strategies for preventing and controlling brucellosis are discussed with a particular reference to the situation of bovine brucellosis in Ivory Coast. The presence and the importance of the disease were confirmed in the country but the disease is still uncontrolled. In the second chapter (Chapter 2), an insight on statistical, epidemiological principles and concepts applied to achieve the different objectives (Chapter 3) is given, including a discussion on available approaches to estimate diagnostic test characteristics and the true prevalence of a disease. The second part of the thesis includes research on different aspects of the epidemiology of bovine brucellosis in Ivory Coast and West Africa (Chapter 4, 5, 6 and 7). Chapter 4 specifically provides a state-of–the-art knowledge on species and biovars of Brucella reported in cattle from Ivory Coast and all other countries of West Africa, through a review of available literature. From the synthesized literature, Brucella abortus was demonstrated to be the most prevalent species in cattle in West Africa, in line with the known host preference for Brucellae. So far, biovars 3 appeared to be commonly the most isolated in West Africa and was also recently identified in Ivory Coast. However, the presence of B. melitensis and/or B. suis was not reported yet in cattle in this part of Africa. Results on prevailing strains of Brucella in cattle were related with commonly used serological diagnostic tools. Thus, chapter 5 was dedicated to verify their appropriateness and to assess the performance of two serological tests, Rose Bengal Test (RBT) and indirect Enzyme-linked Immunosorbent assay (iELISA). Using a Bayesian approach, the correlation-adjusted sensitivity of iELISA was estimated at 96.1 % (Credibility Interval (CrI): 92.7-99.8) whereas that of RBT was 54.9 % (CrI: 23.5-95.1). High correlation-adjusted specificities were found for both tests, 95.0 % (CrI: 91.1-99.6) for iELISA and 97.7 % (CrI: 95.3-99.4) for RBT, respectively. The true prevalence of brucellosis was also estimated using the 1228 tested serum samples to be 4.6 with a 95% credibility interval ranging from 0.6 to 9.5% (Chapter 5 and 6). These results also revealed a good performance for the iELISA, which might consequently be a valuable screening assay under the epidemiological conditions prevailing in Ivory Coast. In Chapter 7, risk factors associated with bovine brucellosis seropositivity were investigated using serological results obtained from 907 serum samples collected from unvaccinated cattle of at least 6 months of age in the savannah-forest region of Ivory Coast. Serum samples were tested using the Rose Bengal test (RBT) and indirect enzyme linked immunosorbent assay (iELISA). The logistic regression analysis indicated that brucellosis seropositivity was associated with age and herd size. Cattle above 5 years of age were found to be more likely seropositive (Odd Ratio (OR) =2.8; 95% Confidence Interval (CI): 1.3, 6.4) compared to cattle under 3 years of age. Similarly, the odds of brucellosis seropositivity for herds with more than 100 cattle was 3.3 (95% CI: 1.2, 8.9) times higher compared to those with less than 50 cattle. The third part presents a general discussion on the overall contribution of the current research (Chapter 8), by highlighting the main results and pointing out their significance. The need for more investigations on the epidemiology of brucellosis, in Ivory Coast and at West African scale, is highlighted. It is neccessary to provide additional knowledge on prevailing field strains of Brucella, on the distribution of the disease and on associated risk factors to implement preventive and control measures. Finally, for more cost-effectiveness and efficiency, the need to strengthen the capabilities of the veterinary services and national laboratories and to consider the control of brucellosis and other zoonotic diseases through a regional, integrated and collaborative perspective is also highlighted. [less ▲]

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See detailDiagnosis and clinical interest of asthma inflammatory phenotypes
SCHLEICH, FLorence ULg

Doctoral thesis (2014)

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See detailGenetic improvement of pig sire lines for production performances in crossbreeding
Dufrasne, Marie ULg

Doctoral thesis (2014)

Crossbreeding is widely used in pig breeding to benefit from advantages of heterosis effects and breed complementarity. Breeding programs are specialized between sire and dam lines, with different ... [more ▼]

Crossbreeding is widely used in pig breeding to benefit from advantages of heterosis effects and breed complementarity. Breeding programs are specialized between sire and dam lines, with different selection objectives. Sire lines are mainly selected for production traits (e.g., growth, carcass quality, feed efficiency). Moreover, selection is often in purebred lines while the goal of selection is to improve crossbred performances. Hence, genetic selection of purebred parents involved in crossbreeding requires models accounting for crossbreeding effects, and able to combine data from different genetic types (purebreds and crossbreds) and different environmental conditions. Therefore, the objective of this thesis was to develop genetic models to estimate genetic parameters and breeding values for production traits in crossbred populations of pigs. A genetic model was developed to estimate the genetic potential of Walloon purebred Piétrain boars for growth performances in crossbreeding based on test station and on-farm data from purebred and crossbred pigs. Weight records from both systems were considered as different traits. Results showed that weights recorded in test station and on-farm were different traits but genetically correlated. Moreover, combining both sources of data allowed to increase reliability of estimated breeding values and Genotype x Environment interactions were detected for growth in the Walloon breeding program. The introduction of dominance effects, linked to crossbreeding, into the genetic model for growth in the crossbred population showed that dominance effects existed on growth of crossbred pigs. Moreover, the total and the additive genetic merits were better estimated than with a strictly additive model. Research conducted on commercial crossbred data from US Duroc sires displayed that the sire genetic effects were not negligible on traits like piglet birth weight, preweaning mortality, mortality at different stages of the grow-finishing period and hot carcass weight. Furthermore, sire genetic effects increased with age. Genetic studies of mortality in the population from US Duroc sires showed that mortality traits had a low heritability, increasing with age and that mortality was not antagonistic with market weight. Besides, genetic parameters estimated for birth weight and its relation with other production traits in crossbred populations from Piétrain and Duroc sires showed that birth weight could be used as an early indicator trait to improve latter performances. Finally, production traits were genetically correlated and should be selected simultaneously to reach the breeding goal. [less ▲]

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See detailImpact of abiotic and biotic factors on VOC emissions and protein expression in Arabidopsis thaliana (L.) Heynh
Hien, Truong Thi Dieu ULg

Doctoral thesis (2014)

The interaction of Arabidopsis and environmental factors is a model system used to study stress response in plants, in particular the analysis of the emission of volatile organic compounds (VOCs) and the ... [more ▼]

The interaction of Arabidopsis and environmental factors is a model system used to study stress response in plants, in particular the analysis of the emission of volatile organic compounds (VOCs) and the proteomic expression. In the present thesis, VOC emissions and expression of proteins were studied in the response of Arabidopsis thaliana (L.) Heynh to the interaction of abiotic (temperature or water stress) and biotic (adults Myzus persicae (Sulzer) or Plutella xylostella (L.) larvae) factors. To achieve these objectives, the volatile profiles emission of Arabidopsis was previously evaluated by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The experimental conditions were maintained for different periods, and the emission profile for each period was determined. Our main findings were as follows: (1) the combined aphids (M. persicae) and temperature stress treatments induced more complex plant volatile profiles than did single stress. Rising in temperatures (17, 22, and 27 °C) led to significant increases of isothiocyanate (ITC), nitrile, and sulfide proportions in aphid-infested Arabidopsis plants; (2) aphid-infested water-stressed Arabidopsis exhibited significant changes in their VOC emission blends with modification of sulfide, ITC, ketones, aldehyde, and terpenes; and (3) the molecule profiles from P. xylostella-infested plants also varied with infestation time and temperature treatment. The larvae-infested Arabidopsis at 22 °C emitted sulfides and nitrile instead of ITCs as it is the case at 17 and 27 °C. Additionally, a proteomic approach using two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry was performed to examine the protein changes in Arabidopsis responses to herbivorous insects under controlled conditions. A total of 574 and 454 protein spots were reproducibly detected by bidimensional electrophoresis. After M. persicae and P. xylostella infestations 31 and 18 protein spots were differently expressed in their relative abundance, respectively. Sixteen proteins were successfully identified by MALDI-TOF MS and LC-ESI-MS/MS. Functional analysis of identified proteins showed that they were associated with a large number of biological processes, namely carbohydrate, amino acid, lipid and energy metabolism, photosynthesis, defense and translation process. The expression of such proteins in A. thaliana leaves was either up-regulated or down-regulated according to insect feeding stresses. Taken together, the original reported results provide evidences that the interaction between abiotic and biotic stress factors has great ability to alter the profile of VOCs as well as proteins in A. thaliana plants. It provides valuable new insights to explore the complex response of plants to multiple simultaneous factors. [less ▲]

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See detailPRODUCTION DES CLADOCERES DANS LES BASSINS DE LAGUNAGE: MODELISATION ET ANALYSE DE RENTABILITE DE LEUR VALORISATION
Liady, Mouhamadou Nourou Dine ULg

Doctoral thesis (2014)

Face à l’urgence exprimée par la communauté internationale de trouver des solutions efficaces et durables à la crise sanitaire, due au manque d’accès à l’assainissement dans les pays du sud, la présente ... [more ▼]

Face à l’urgence exprimée par la communauté internationale de trouver des solutions efficaces et durables à la crise sanitaire, due au manque d’accès à l’assainissement dans les pays du sud, la présente thèse s’est intéressée à l’étude de la possibilité de promouvoir ce secteur à travers l’intégration, dans les projets d’assainissement, d’incitants financiers tels que la valorisation des cladocères qui se développent dans les bassins de lagunage. Pour ce faire, une approche méthodologique basée sur la modélisation (qui permet d’intégrer tous les processus et les variables qui concourent au fonctionnement des bassins de lagunage) a été adoptée pour non seulement améliorer les connaissances sur le fonctionnement de ces bassins, mais aussi estimer les productions des cladocères et leurs impacts sur l’épuration des eaux dans ces bassins. Ensuite, la rentabilité d’un avant-projet de valorisation des cladocères a été étudiée dans le contexte socio-économique du Bénin. Le travail a débuté par une revue de la littérature, s’est poursuivi par les calibrations des techniques utilisées pour estimer les biomasses de Daphnia pulex et des différents substrats utilisés. Les études de cinétiques et de stœchiométries des différents processus de conversion biochimique impliquant les cladocères, ainsi que l’étude de rentabilité de deux variantes de valorisation des cladocères, ont complété le travail. La stœchiométrie de chacun des différents processus de conversion biochimique a été décrite en commençant par démontrer que les biomoles appliquées dans le modèle "ModLag" et dans le RWQM1 sont bien applicables aux organismes étudiés dans la présente thèse puis, à défaut des équipements requis pour mesurer les paramètres stœchiométriques, en utilisant les valeurs proposées dans le RWQM1. Toutefois, des commentaires importants sur les mesures de ces paramètres, ont été effectués aux regards non seulement des pratiques en vigueurs en hydrobiologie d’une part et en biotechnologies (sur les cultures en continue sur chémostat notamment) d’autre part, vis-à-vis des besoins pour la modélisation. Des démarches méthodologiques ont été proposées. Les résultats obtenus des études cinétiques montrent que : - la cinétique de la croissance des cladocères sur les bactéries est décrite par un modèle de type Monod qui traduit une augmentation du taux de croissance en fonction des teneurs en bactéries, jusqu’à une certaine teneur en bactéries à partir de laquelle on observe une saturation de la croissance, - la cinétique de leur croissance sur les algues est décrite par un modèle qui traduit une inhibition de la croissance par de fortes teneurs en algues, - la cinétique globale de la croissance de D. pulex simultanément sur Scenedesmus sp. et E. coli est mieux décrite par le modèle de cinétique avec paramètre d’interaction, que par le modèle sans interaction. - les teneurs en cyanobactéries influencent la cinétique de la mortalité des cladocères. Ce travail est le premier, à notre connaissance à prendre en compte, en modélisation, la mortalité des cladocères du fait de la toxicité des cyanobactéries. Les résultats des analyses de stœchiométrie révèlent que : - Pour produire 1 g d’équivalent DCO de D. pulex, 5 g d’équivalent DCO de Scenedesmus sp., (ou d’E. coli) sont oxydés dont 0,77 sont convertis en matières organiques particulaires et, le reste (soit 3,23 équivalent DCO ou 65%) est oxydé (pour la production de l’énergie nécessaire au métabolisme) sous forme de CO2. - En conditions de respiration endogène (observée dans les bassins de lagunage, en période de surpopulation de cladocères par rapport aux ressources alimentaires disponibles), on assiste à un abattement de la DCO des daphnies exclusivement au profit de la production d’énergie pour le catabolisme. - Lorsque l’équivalent en DCO de 1 g de D. pulex meurt, 1,2 g de DCO de matières organiques particulaires sont produites dont 79% sont biodégradable. L’impact des cladocères sur l’épuration des eaux dans les bassins de lagunage peut ainsi être analysé de manière approfondie, à la fois au plan cinétique et stœchiométrique, à l’aide de la modélisation globale du système "bassin de lagunage" en complétant le "sous-modèle cladocère" proposé dans la présente thèse, au modèle de lagunage "ModLag" de l’unité "Assainissement et Environnement" et, en réalisant des simulations à l’aide du logiciel "WEST". L’essentiel du travail nécessaire pour la réalisation des simulations a été effectué et présenté dans le chapitre VIII; par contre, les simulations n’ont pas pu être finalisées avant le dépôt de la présente thèse dans les délais exigés, en raison d’un problème survenu sur "WEST". Elles le seront avant la défense publique de cette thèse et, les résultats pourront alors être présentés. En attendant, les analyses de cinétiques et de stœchiométries montrent que dans des conditions non limitantes en substrats et en absence de cyanobactéries, la vitesse de croissance des cladocères étant supérieure à la somme des vitesses de leur respiration et de leur mortalité, on assisterait plus à un abattement de la DCO essentiellement algale et bactérienne. Cela révèle que s’il est bien géré avec des récoltes périodiques, un étage trophique constitué de cladocères peut contribuer à accroître le rendement épuratoire en réduisant les biomasses d’algues et de bactéries en fin de traitement. Ces récoltes périodiques de biomasses de cladocères, permettront de maintenir un bon état de fonctionnement du système en évitant de trop réduire les biomasses d’algues et de bactéries qui assurent respectivement, l’oxygénation de l’eau et la minéralisation de la pollution organique dissoute avec un effet détoxifiant notamment à travers la nitrification de l’ammoniac. L’étude de rentabilité de l’avant-projet de valorisation des cladocères produits dans les bassins de lagunage révèle que, dans le contexte socio-économique du Bénin, avec une production journalière estimée à 1,19 g poids sec/m3.j : - la variante 1 consistant en une vente des récoltes de cladocères sous la forme de surgelés (ou de produits secs) est rentable et permet de réaliser un bénéfice annuel de l’ordre de 15.000 €/ha.an (si l’on considère la surface totale de l’exploitation), même en prenant en compte le remboursement sur une durée de dix ans des investissements dédiés à l’achat de terrains et à l’aménagement de la station d’épuration. - la variante 2 consistant en une valorisation sur place de la biomasse de cladocères, dans la production de poissons est également rentable mais seulement si les investissements pour l’achat de terres et les aménagements, n’étaient pas remboursés. Dans ces conditions, elle permettrait de réaliser un bénéfice annuel de 1629 €/ha.an (si l’on considère la surface totale de l’exploitation) ou 6803 €/ha.an (si l’on considère uniquement la surface du bassin de production). Cette étude a permis de : - mettre en exergue les insuffisances des modèles de la littérature, pour décrire la croissance des cladocères dans les bassins de lagunage, - bien cerner les substrats (algues et bactéries) qui contribuent à la croissance des cladocères ainsi que l’influence des teneurs de ces substrats sur la cinétique de leur croissance; - prendre en compte l’influence des cyanobactéries sur la cinétique de la mortalité des cladocères ; - apporter une importante contribution à la modélisation du fonctionnement des bassins de lagunage, en spécifiant clairement les modèles qui décrivent les cinétiques de croissance des cladocères sur les algues et les bactéries, et la cinétique de la mortalité des cladocères, en présence des cyanobactéries ; - proposer un sous-modèle qui traduit les processus de conversion biochimiques impliquant les cladocères ; - montrer que les récoltes raisonnables de cladocères contribuent à optimiser l’équilibre du système et ses performances épuratoires ; leur valorisation est financièrement rentable pour la gestion d’une station d’épuration, voire du secteur de l’assainissement. - montrer qu’il est possible de réaliser des marges bénéficiaires importantes à travers la valorisation des cladocères, et par conséquent, d’intégrer dans la conception des projets d’assainissements destinés aux pays du sud, des incitants financiers. Cela pourrait motiver les investisseurs à promouvoir ce secteur, et, accroître l’accès des populations à l’assainissement. [less ▲]

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See detailInnovative algorithms to combine phenotypic, genealogical and genomic information originating from diverse sources
Vandenplas, Jérémie ULg

Doctoral thesis (2014)

Along with technical developments, international exchanges of genetic material (e.g., frozen semen, embryos) have increased since the 1970s. However, genetic evaluations are traditionally based on ... [more ▼]

Along with technical developments, international exchanges of genetic material (e.g., frozen semen, embryos) have increased since the 1970s. However, genetic evaluations are traditionally based on phenotypic and genealogical data which are internally recorded, i.e., within well defined borders. Because imported (i.e., external) genetic material is usually strongly selected in their respective populations, internal genetic evaluations for external animals could be biased and less accurate if external data used for their selection is ignored. Moreover, comparison of internal and external animals based on their internal and external estimates of genetic merit is needed to select and potentially import the most suitable ones according to the internal breeding goal. However, such comparison is usually not possible among internal and external genetic evaluations due, e.g., to differences among units of measurement. Thereby, several approaches and algorithms have been developed to render internal and external genetic evaluations comparable, and to combine or blend phenotypic and genealogical data and external information, i.e., estimates of genetic merit and associated reliabilities. Furthermore, the recent development of genomic selection also increased needs for combining phenotypic, genealogical and genomic data and information. Therefore, the aim of this thesis was first to develop innovative algorithms to combine diverse sources of phenotypic, genealogical and genomic data and information, and second to test them on simulated and real data in order to check their correctness. Based on a Bayesian view of the linear mixed models and addressing several issues highlighted by previous studies, systems of equations combining simultaneously diverse sources of data and external information were developed for (multivariate) genetic and single-step genomic evaluations. Double counting of contributions due to relationships and due to records were considered as well as computational burden. The performances of the developed systems of equations were evaluated using simulated datasets and real datasets originating from genetic (genomic) evaluations for Holstein cattle and for show jumping horses. The different results showed that the developed equations integrated and blended several sources of information in a proper way into a genetic or a single-step genomic evaluation.It was also observed that double counting of contributions due to relationships and due to records was (almost) avoided. Furthermore, more reliable estimates of genetic merit were also obtained for external animals and for their relatives after integration of external information. Also, the developed equations can be easily adapted to complex models, such as multivariate mixed models. Indeed, it was shown that external information correlated to the internal phenotypic traits was properly integrated using the developed equations. Finally, research of this thesis led to the development of a genomic evaluation system for Holstein cattle in the Walloon Region of Belgium for production traits, as well as for other traits, like somatic cell score. Based on the research of this thesis, future research topics, e.g., concerning integration of correlated external information and of genomic information, were finally presented. [less ▲]

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See detailModélisation des processus physiques et biologiques dans des fosses septiques et voies de valorisation des boues de vidange:Application à Bujumbura-Burundi
Nsavyimana, Gaston ULg

Doctoral thesis (2014)

Dans les pays en développement (PED) en général et au Burundi en particulier, la problématique de gestion des eaux usées et des déchets solides constitue un enjeu majeur pour les spécialistes et les ... [more ▼]

Dans les pays en développement (PED) en général et au Burundi en particulier, la problématique de gestion des eaux usées et des déchets solides constitue un enjeu majeur pour les spécialistes et les autorités locales. En effet, suite à un manque des stations d'épuration collectives au Burundi, les fosses septiques sont les plus utilisées pour gérer les eaux usées produites. Cependant, les processus qui s'y déroulent ne sont pas encore maîtrisés et la gestion des boues de vidange lorsque ces installations sont remplies, constitue une problématique qui mérite d'être abordée afin de trouver des solutions adaptées, à court et à long terme. Et, suite à une absence des technologies appropriées en matière de gestion des déchets solides, ils sont jetés de manière inadmissible (dans les caniveaux, rivières, places publiques, etc.), et cela peut engendrer à court ou à long terme des nuisances graves, tant pour la santé et l'hygiène publique que pour l'environnement. C’est dans l’optique de contribuer: (i) à l'amélioration de la qualité environnementale; (ii) et à la réduction des risques sanitaires associés à la gestion des déchets liquides et solides à Bujumbura (Burundi), que s’inscrit ce travail de recherche qui porte sur la "Modélisation des processus physiques et biologiques dans des fosses septiques et voies de valorisation des boues de vidange: Application à Bujumbura-Burundi". Différents axes ont ainsi été abordés pour répondre a cet objectif général : (1) la quantification des processus physico-chimiques dans des fosses septiques; (2) la modélisation stœchiométrique, cinétique et mathématique des processus biochimiques; et (3) l'étude des voies de valorisation énergétique des boues de vidange, soit seules (en digestion anaérobie) ou combinées avec des déchets solides fermentescibles (en co-digestion anaérobie). L'étude de quantification des processus physico-chimiques, matérialisables par le phénomène de décantation des particules solides a permis de dégager deux résultats principaux: (i) les effluents d'entrée dans les fosses septiques présentent une bonne décantabilité; (ii) les effluents de sortie de ces ouvrages (107 mg MES/L) ne respectent pas les normes de rejets (30 mg MES/L: cas de la norme Belge). Des dispositifs appropriés pour le traitement des effluents de sortie des fosses septiques (lit filtrant drainé/ou non à flux vertical sur un massif de sable, lit filtrant drainé/ou non à flux vertical sur un massif de zéolithe, lit filtrant horizontal drainé, tertre d’infiltration, tranchée d'épandage ou lit bactérien percolateur) ont été proposés pour palier les insuffisances des puits perdants couramment utilisés au Burundi. L'étude de caractérisation des flux entrant dans des fosses septiques était indispensable pour les modélisations ultérieures (stœchiométrique, cinétique et mathématique) des processus biochimiques et a permis de quantifier, de manière revisitée, la notion d' un équivalent habitant. Ainsi, un équivalent habitant (EH) a été déterminé pour la Belgique et le Burundi en termes de la demande chimique en oxygène (DCO), soit 138,75 ± 20,09 gDCO/EH/j et 117,08 ± 10,09 gDCO/EH/j respectivement. De plus, cette étude a permis de caractériser, par rapport à un équivalent habitant, différents composés chimiques importants contenus dans les flux entrant dans les fosses septiques. Les résultats variaient entre 0,37 ± 0,18 g/EH/j (pour les acides aminés urinaires ) et 43,44 ± 4,35 g/EH/j ( pour glucides), avec des valeurs de 5,00 ± 0,3; 10,15 ± 1,96; 10,6 ± 3,27; 14,7 ± 0,4 et 14,99 ± 1,57 g/EH/j respectivement pour les savons de bain/douche, lipides, azote total, détergent pour lave-linge et protéines. Ces résultats ont contribué à l'élaboration d'une formule "de biomole de substrat complexe" (C23 H49O9N) représentant les eaux usées, utile pour simplifier la modélisation mathématique de fonctionnement des fosses septiques en réduisant le nombre de processus, de variables d’état, d’équations cinétiques associées et des paramètres qui en découlent. La modélisation stœchiométrique des processus biochimiques qui se déroulent dans les fosses septiques, après avoir vérifié que le métabolisme est bien anaérobie, même si des eaux usées éventuellement saturées en O2 entrent quotidiennement dans ce type de dispositifs, a permis de mettre en place un système d’équations qui décrit la stœchiométrie de fonctionnement des fosses septiques. Par ailleurs, dans les pays en développement comme le Burundi, les laboratoires sont moins équipés et ont un accès très limité aux équipements modernes d'analyse usuels (ex., GC ou HPLC ), pour le dosage des acides gras volatils (AGV). A cet effet, nous avons développé et vérifié une nouvelle méthode de dosage des AGV par titrage, efficace et proche de la méthode chromatographique en phase gazeuse. A 99% d'intervalle de confiance, les résultats obtenus à l'aide de cette nouvelle méthode, sont comparables à ceux de la chromatographie en phase gazeuse. La modélisation cinétique a permis de mettre en exergue un modèle de dégradation de la biomole du substrat complexe, qui s'est révélé comparable au modèle cinétique de Monod. Les constantes cinétiques découlant du traitement des données sont dans le cas présent: (i) le taux maximum de croissance spécifique (µmax) égal à 0,0065 j-1; (ii) la constante de demi-saturation de ce substrat combiné synthétique égale à 9,18 g DCO/l ou 4,26 g/l; et (iii) le taux de mortalité égal à 0,0001 j-1. Ces données sont très utiles pour les simulations de fonctionnement des fosses septiques à l'aide d'un logiciel de gestion des ouvrages de traitement des eaux usées (WEST®). Ce travail a également permis de développer un modèle global de fonctionnement des fosses septiques (MFS/DDA ), qui par ailleurs a été présenté suivant le formalisme matriciel de Petersen. Une étude préliminaire de caractérisation détaillée des boues de vidange a montré qu'elles sont presque stabilisées, du point de vue valorisation énergétique. Lorsqu'elles sont digérées seules, elles présentent un faible potentiel méthanogène, soit 2,09 m3 biogaz/m3 de boues fraîches (après deux mois de digestion). Ce biogaz est composé de 71% de CH4 contre 29% de CO2. Ce travail a montré un intérêt de co-digestion anaérobie des boues de vidange avec les déchets solides fermentescibles. A cet effet, un rapport MVSFS/MOVdéchets égal à 0,3 (MOVdéchets étant exprimées en poids sec de déchets et MVSFS en poids sec des boues de vidange) s’est révélé optimal , pour leur meilleure valorisation énergétique, avec une production cumulée maximale de biogaz égal à 12,14 m3biogaz/m3 de mélange gadoues-déchets. La composition moyenne de ce biogaz était de 65,6% en CH4 contre 34,4% en CO2. Mots Clés: Burundi; Assainissement; Fosses septiques; Eaux noires; Eaux grises; Equivalent habitant; Décantation; Digestion anaérobie; Substrat combiné; Acides gras volatils; Modèle stœchiométrique; Modèle cinétique; Matrice de Petersen; Simulations avec WEST®; Boues de vidange; Potentiel méthanogène; Co-digestion anaérobie; Déchets solides fermentescibles. [less ▲]

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See detailParticulate soils adherence and surface cleanability: influence of biomacromolecules at interfaces and of substrate hydrophobicity
Toure, Yetioman ULg

Doctoral thesis (2014)

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The ... [more ▼]

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The combination of particles and macromolecules substances appears in many processes. Adsorbed compounds from these mixtures may influence interactions at interfaces and thus fouling and cleaning. This thesis deals with a deeper understanding of the physico-chemical mechanisms affecting soiling and cleanability of open substrates in the presence of biomacromolecules (dextran, bovine serum albumin – BSA, beta-lactoglobulin – β-LGB). Model substrates were chosen according to their hydrophobicity. The influence of macromolecules was examined by introducing them in the quartz suspension taken as a model of hard hydrophilic soil used for soiling, or by conditioning the substrate prior to soiling. The substrates were pretreated with ethanol (-Eth.), piranha or UV-Ozone (-UVO); soiled by spraying the quartz suspensions, then dried, before cleaning assessment. The removal of the soiling particles was evaluated after exposure to water in a radial flow chamber (RFC). Auxiliary characterizations were surface tension and contact angle measurements, surface analysis of the substrate by X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM). The interpretation of XPS data allowed the complexity due to the ubiquitous presence of organic contaminants to be coped with, and the surface composition to be expressed in terms of both the amount of adlayer and the mass concentration of adlayer constituents. The contact of substrates with proteins led to their adsorption, which dominated the composition of the organic layer with respect to contaminants initially present, and was not markedly desorbed upon rinsing. Dextran was easily removed in presence of water, independently on the substrate nature. Surface hydrophobicity was shown to influence the morphology of the aggregates resulting from drying. The rounder aggregates formed on polystyrene when soiling was performed with suspension in pure water are more sensitive to wall shear stress than flatter ones formed on more hydrophilic substrate. This is the result of the competing processes of droplet rolling and coalescing, on the one hand, and droplet spreading, on the other hand. It affects the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning and finally, the adherence of soiling particles. The presence of proteins (either native or denatured) at the interface improved strongly the cleanability of more hydrophilic substrate (glass, StSteel-UVO). This is attributed to the lower surface tension. The dependence of cleanability on capillary forces, and in particular on the liquid surface tension, is predominant as compared with its dependence on the size and shape of the soiling aggregates, which influence the efficiency of shear forces exerted by the flowing water upon cleaning. The cleanability of less hydrophilic substrate (stainless steel only pre-cleaned with ethanol) did not change markedly in the presence of proteins; this may be due to a more complex interaction between surface tension and contact angle, on one hand, and a more complex interaction between proteins and contaminants, on the other hand. The presence of dextran did not affect the cleanability, as neither the liquid surface tension nor the contact angle was appreciably affected. [less ▲]

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See detailMise au point d'une forme stable de l'allergène Der p 3 de Dermatophagoides pteronyssinus pour le diagnostic rapide et le développement de nouvelles approches d'immunothérapie de l'allergie aux acariens
Bouaziz, Ahlem ULg

Doctoral thesis (2014)

L’allergie aux acariens touche 20 à 30 % de la population occidentale. L’allergène Der p 3 de l’acarien Dermatophagoides pteronyssinus est une protéase à serine active appartenant à la famille de la ... [more ▼]

L’allergie aux acariens touche 20 à 30 % de la population occidentale. L’allergène Der p 3 de l’acarien Dermatophagoides pteronyssinus est une protéase à serine active appartenant à la famille de la trypsine. Son activité protéolytique pourrait être un facteur adjuvant impliqué dans le développement et la chronicité de l’allergie. A l’heure actuelle, l’implication de Der p 3 dans l’allergie est peu connue et son taux de fixation des IgE provenant de patients allergiques est controversé. Cependant, ces différentes études ont été réalisées au moyen d’un allergène naturel très sujet à l’autolyse et pouvant être contaminé par d’autres protéase. Durant la première partie de cette étude, nous avons pu montrer que rDer p 3 produit en P.Pastoris présente les mêmes propriétés allergéniques que nDer p 3. En effet, les résultats obtenus par test ELISA, inhibition compétitive montrent que rDer p 3 est correctement replié et présente les mêmes épitopes B conformationnels que l’allergène naturel. Dans la deuxième partie de cette thèse, nous avons pu mettre en évidence que l’autolyse de Der p 3 durant le test ELISA a un effet sur la reconnaissance des IgE. En effet, le taux mesuré avec la forme inactive est deux fois supérieur par rapport à la forme active. Der p 3S196A pourrait être donc un meilleur outil de diagnostic pour l’allergie à Der p 3. Dans la troisième partie de cette thèse, nous avons pu montrer que le propeptide de proDer p 3 affecte l’allergénicité de Der p 3. Par une étude in vitro, nous avons prouvé par ELISA, par les tests de dégranulation des basophiles de rat humanisés et d’activation des basophiles humains, que proDer p 3 est moins bien reconnu par les IgE de patients allergiques que la forme mature Der p 3. Ensuite, nous avons montré que les souris sensibilisées par les formes mature et zymogène de l’allergène Der p 3 ont développé une réponse immune de type TH2 et TH1 respectivement. ProDer p 3 pourrait donc être considéré comme une forme hypoallergénique de l’allergène Der p 3. Dans la dernière partie, nous avons construit un modèle tridimensionnel de l’allergène Der p 3 afin de prédire les épitopes B conformationnels par approche bioinformatique. En effet, 3 épitopes B ont été prédits ainsi que les acides aminés impliqués dans la reconnaissance et la fixation des IgE au sein de chaque épitope. Enfin, au moyen de la technique du peptide array, nous avons pu mettre en évidence un épitope B linéaire de l’allergène Der p 3. [less ▲]

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See detailLa promotion de l’activité physique chez les seniors : approche au sein d’une communauté locale
Mouton, Alexandre ULg

Doctoral thesis (2014)

In our contemporary society, get moving is rarely necessary to perform our daily routine. Consequently, physical inactivity is currently considered as the fourth cause of premature death worldwide. Faced ... [more ▼]

In our contemporary society, get moving is rarely necessary to perform our daily routine. Consequently, physical inactivity is currently considered as the fourth cause of premature death worldwide. Faced with an aging population, involving a doubling of the people aged 60 years and over in 2050, physical activity promotion could contribute to preserve individual health in supporting people to adopt an active lifestyle. Our personal contribution aimed at developing an appropriate physical activity promotion intervention at a local level. The Introduction chapter theoretically legitimate the need to implement new interventions, especially at a local level. In this thesis, we focused our attention on a particular Belgian French-speaking municipality, Esneux, in order to develop a structured and evidence-based physical activity promotion process. The Planned Health Promotion model guided this local approach. The Chapter 1 of our contribution aimed at analysing the local context in terms of physical activity behaviours in the population and opportunities to be physically active in the municipality environment. As observed on a larger scale, the results of this survey exposed that the majority of the participants did not respect the official recommendations for physical activity. Because participants aged 50 years and over were on average less active than younger participants, we developed a local intervention dedicated to seniors in Chapter 2. The purpose of this chapter was to assess the relevance of an original web-based physical activity promotion intervention addressed to older adults. The presented literature review and pilot study highlighted the suitability of such an approach for seniors, on condition that it includes a local perspective and a sufficient social support. The aim of the study presented in Chapter 3 was to compare the long-term effects of three different physical activity promotion interventions’ conditions implemented at the municipality level on physical activity behaviour and knowledge of older adults. Participants took part in a web-based intervention, a group-based intervention or a combined intervention during three months. Leading to significant improvements of the physical activity behaviour, but also of the knowledge about physical activity in general and regarding to the local opportunities, the combined approach could be considered as the most appropriate for a local level dissemination. The study presented in Chapter 4 specified the interest of a local environment-centered approach for physical activity promotion among older adults. This study underlined the mediating role of the perception of the local opportunities to be physically active and of the perception about the quality of the environment for physical activity on the intention-behaviour relationship. In the General discussion, we provide a critical look to each step of our local physical activity promotion approach and suggest potential avenues for future research in the field. [less ▲]

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See detailOrigines développementales des anomalies de l'homéostasie glucidique, de la croissance osseuse et prédisposition à l'ostéochondrose chez le poulain
Peugnet, Pauline ULg

Doctoral thesis (2014)

Fetal adaptations to intra-uterine stimuli have immediate and long term effects on the offspring’s health after birth. In equids, this concept known as the DOHaD (Developmental Origins of Health and ... [more ▼]

Fetal adaptations to intra-uterine stimuli have immediate and long term effects on the offspring’s health after birth. In equids, this concept known as the DOHaD (Developmental Origins of Health and Disease) was validated using crossbreeding: the mare’s size which affects the fetal environment throughout gestation and then lactation, has a critical impact on the foal’s post-natal growth, as well as on the neonate’s sensitivity to insulin. Osteochondrosis, a pathology of the growing horse, induces heavy financial losses in the equine industry. It has been associated to abnormalities in glucose homeostasis and its antenatal origin is highly suspected. The present research aimed to evaluate the impact of experimental disturbances during fetal development on growth, glucose homeostasis and predisposition to osteochondrosis in the foal until age 1½ year. Increased versus restricted fetal growth was obtained using between-breed embryo transfers (“ponies in draft horses” versus “saddlebreds in ponies”, respectively). The lush environment of the draft mare versus the restricted environment of the pony mare turned out to be critical in the regulation of bone growth, thyroid hormones secretion, β-cells function, insulin sensitivity and the osteoarticular status of the foal from birth to 1½ year of age. This validates the concept of the DOHaD in equids and shows that recipient mares should be carefully selected in embryo transfer practice. By demonstrating the scope of post-natal effects which were programmed in utero and throughout the lactating period, it also alerts the breeder about the importance of broodmare management and its long term impacts. Thus, the second model was developed to address breeders' practices. A disturbance of the nutritional environment of the fetus was induced by supplementing mares in late pregnancy with concentrated feed (barley). So far, only the neonatal foal's glucose homeostasis was affected, whereas all other studied parameters, including growth, were not affected. The foal’s predisposition to osteochondrosis, however, was increased at 6 months of age, which does not preclude that it will affect the animals afterwards since the osteoarticular status of the 6-month-old foal will evolve beyond weaning time. This research could help adjust nutritional recommendations to broodmares. [less ▲]

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See detailIntraocular lenses with functionalized surfaces by biomolecules in relation with lens epithelial cell adhesion
Huang, Yi-Shiang ULg

Doctoral thesis (2014)

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial ... [more ▼]

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial-Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including patient’s age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs show the former has more severe PCO after EMT transition. Additionally, the LEC adhesion is favored onto the hydrophobic materials compared to the hydrophilic ones. A biomimetic strategy to promote LEC adhesion without de-differentiation to reduce PCO development risk is proposed. RGD peptides, as well as their grafting and quantification methods on a hydrophilic acrylic polymer were investigated. The surface functionalized IOL promoting LEC adhesion via integrin receptors can be used to reconstitute the capsule-LEC-IOL sandwich structure, which is considered to prevent PCO formation in literature. The results show the innovative biomaterial improves LEC adhesion, and also exhibits similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties comparing to the starting material. In addition, comparing to the hydrophobic IOL material, this bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression. The in vitro assays suggest this biomaterial has the potential to reduce some risk factors of PCO development. [less ▲]

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See detailPhysical properties/texture relationship in industrial melt-cast processed Bi-2212 bulk superconductors using quantitative texture analysis
Dellicour, Aline ULg

Doctoral thesis (2014)

Superconducting Bi2Sr2CaCu2O8+δ tubes and rods manufactured at Nexans SuperConductors gmbh are known to achieve excellent performances despite apparently weak texture. A full texture characterization of ... [more ▼]

Superconducting Bi2Sr2CaCu2O8+δ tubes and rods manufactured at Nexans SuperConductors gmbh are known to achieve excellent performances despite apparently weak texture. A full texture characterization of the bulks has been performed at different scales, using X-ray diffraction and neutron diffraction. The texture experiments confirm that samples exhibit weak textures and reveal some differences between local and macroscopic texture. When investigating how the physical properties might be affected by texture, it was observed that the critical current density Jc is not much influenced by the direction of measurement, while the normal state electrical resistivity displays a ratio of 2.3 between the resistivity along the sample axis and the resistivity along the radial direction. These observations are qualitatively consistent with the texture results. A quantitative study based on the geometric mean of the resistivity tensor compares the experimental data with values calculated from the measured orientation distribution and literature single crystal data. It turns out that, despite the weak texture, a large fraction of the observed resistivity anisotropy is explained by texture effects, because of the very strong anisotropy between the resistivity along the c-axis and the resistivity in the ab-planes. Lastly, the influence of sample oxygenation on Tc and Jc has been studied. In these bulks, Tc as a function of oxygen content follows a bell-shaped curve, confirming literature results for other superconducting samples. Jc is also influenced by the oxygen content; interestingly, the maximum Jc is not obtained for the same oxygen content as the maximum Tc. [less ▲]

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See detailMujeres, circuitos y fronteras en el sur del Ecuador.
Ramos Ordonez, Maria ULg

Doctoral thesis (2014)

La recherche doctorale de Patricia Ramos porte sur la thématique des femmes et circuits migratoires dans le Sud de l’Equateur. Plus précisément, elle va s’intéresser à l’agence (agency) et aux dynamiques ... [more ▼]

La recherche doctorale de Patricia Ramos porte sur la thématique des femmes et circuits migratoires dans le Sud de l’Equateur. Plus précisément, elle va s’intéresser à l’agence (agency) et aux dynamiques de pouvoir auxquelles sont confrontées les femmes étrangères et équatoriennes au niveau local dans une partie de l’Equateur caractérisée par une très forte mobilité des populations. [less ▲]

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See detailMulti-Domain Approaches for the Solution of High-Frequency Time-Harmonic Propagation Problems
Vion, Alexandre ULg

Doctoral thesis (2014)

The numerical solution of high-frequency time-harmonic propagation problems by volumic discretization methods is a challenging task, most notably because of the very large size of the resulting linear ... [more ▼]

The numerical solution of high-frequency time-harmonic propagation problems by volumic discretization methods is a challenging task, most notably because of the very large size of the resulting linear systems. We present a framework for a class of iterative methods that distribute the work between several CPUs and exchange information between physical or artificial interfaces. The goal is to define subproblems of manageable sizes, and to exploit the power of parallel supercomputers. [less ▲]

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See detailLe coût en droit européen de la concurrence, essai sur la réception d'une notion économique
Provost, Elise

Doctoral thesis (2014)

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See detailVers une "dématérialisation" des droits fondamentaux? Convergence des droits fondamentaux dans une protection fragmentée, à la lumière du raisonnement du juge constitutionnel belge
Rosoux, Géraldine ULg

Doctoral thesis (2014)

Le thèse examine l'articulation tant "procédurale" que "substantielle" des droits fondamentaux, garantis par des dispositions tant constitutionnelles que conventionnelles, et protégés par de multiples ... [more ▼]

Le thèse examine l'articulation tant "procédurale" que "substantielle" des droits fondamentaux, garantis par des dispositions tant constitutionnelles que conventionnelles, et protégés par de multiples juges, tant nationaux qu'européens. Au travers d'une analyse empirique de la jurisprudence, est examinée la question de savoir si le juge des droits fondamentaux ne développe pas un raisonnement portant sur les droits fondamentaux comme tels, indépendamment de leur ancrage textuel dans une Constitution nationale ou une convention européenne. [less ▲]

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See detailLa stratégie de construction de puissance de la Chine sur la scène internationale : le cas de la pénétration chinoise en Amérique latine
Wintgens, Sophie ULg

Doctoral thesis (2014)

Dans le contexte de la globalisation post-Guerre froide, l’affirmation de « nouvelles puissances » et l’avènement concomitant de clubs interétatiques tels que les BRICS (Brésil, Russie, Inde, Chine et ... [more ▼]

Dans le contexte de la globalisation post-Guerre froide, l’affirmation de « nouvelles puissances » et l’avènement concomitant de clubs interétatiques tels que les BRICS (Brésil, Russie, Inde, Chine et Afrique du Sud), dans un système international au demeurant dominé par les États-Unis, alimentent les réflexions contemporaines sur la puissance et sa distribution mondiale. Eu égard au rôle international et aux potentialités conférés par sa dimension géopolitique d’État-continent, le seul développement économique de la Chine en fait aujourd’hui un acteur international incontournable (force), alors même que le syncrétisme de son modèle de développement présenté comme un « socialisme aux caractéristiques chinoises », alliant en ce sens des mécanismes de l’économie de marché à des éléments hérités du marxisme-léninisme, lui confère une certaine forme de vulnérabilité constitutive (faiblesse). Si bien que l’énigme de sa puissance (nature) et l’ambivalence de sa réponse à la domination américaine (exercice) enjoignent au double dépassement théorique. La présente thèse, dans son objectif d’analyser la stratégie de construction de puissance de la Chine sur la scène internationale à travers le cas de sa pénétration en Amérique latine, repose dès lors sur un double postulat théorique : la puissance chinoise se définit comme une entreprise de reconnaissance mondiale toujours en redéfinition et au résultat incertain, qui s’opère dans un monde multipolaire en gestation au sein duquel les puissances émergentes rivalisent avec les États-Unis et l’Union européenne (UE) pour la domination. Mesurer l’influence de la Chine sur la scène mondiale, à travers sa capacité à se faire reconnaître comme un acteur international de référence par les autres puissances émergentes et plus encore par les puissances occidentales, procède dès lors également d’une méthodologie ad hoc : seul l’examen corrélé des pratiques des acteurs, étatiques ou autres, (réalité) et du sens qu’ils confèrent à leurs actions (discours) permet de mesurer pleinement l’impact de la représentation que la Chine a du monde, d’elle-même et de sa place dans ce monde, sur les préférences et comportements des autres acteurs du système international. Dans ce cadre, le raisonnement au cœur de la présente thèse s’appuie sur deux parties ou questions centrales. La première interroge la stratégie de construction de puissance de la Chine sur la scène internationale post-Guerre froide. Elle met au jour le poids de trois enjeux fondamentaux en interne dans la construction de son statut d’acteur mondial incontournable, à savoir le poids de l’identité nationale façonnée par l’histoire et l’idéologie, le poids du régime mû par une quête de légitimité structurelle et le poids des intérêts nationaux guidant nécessairement sa diplomatie. La seconde partie questionne ensuite empiriquement la façon dont la Chine construit sa puissance vis-à-vis de l’Amérique latine, région porteuse d’un projet politico-économique sur lequel influent historiquement les stratégies respectives des États-Unis et de l’UE. Elle met au jour le déploiement par la Chine d’une stratégie nécessairement duale de coopération et d’hégémonie visant à consolider sa puissance sans atrophier son ascension (représentation), à même de séduire les États latino-américains (perception), et par conséquent de concurrencer les stratégies américaine et européenne influant sur le sous-continent (reconnaissance). [less ▲]

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See detailHigh-throughput synthesis of functional oxide films
Dhanapal, Pravarthana ULg

Doctoral thesis (2014)

Epitaxy of metal oxides is of great interest since it provides a way to obtain desired novel properties for the applications such as electronics and energy. However, earlier epitaxy research's have been ... [more ▼]

Epitaxy of metal oxides is of great interest since it provides a way to obtain desired novel properties for the applications such as electronics and energy. However, earlier epitaxy research's have been restricted because of the limited range of compositions and low-index of commercially available single crystal substrates. Consequently, novel epitaxy synthesis methods need to be developed in order to go beyond the present demands of of single crystal substrates in terms of phase, composition, size, orientation and symmetry. In this research work, we have developed a high-throughput synthesis process, called combinatorial substrate epitaxy (CSE), where an oxide film is grown epitaxially on a polycrystalline substrate. As a proof-of-concept, we firstly fabricated Ca3Co4O9 films on Al2O3 ceramics. Films have a good local epitaxial registry, and the Seebeck coefficient is about 170 µV/K at 300 K. High quality BiFeO3/La0.7Sr0.3MnO3 thin film heterostructures were secondly deposited on dense LaAlO3 ceramics prepared by spark plasma sintering. Piezoforce microscopy was used to confirm the local ferroelectric properties. Thirdly, we investigate the growth of of metastable monoclinic Dy2Ti2O7 epitaxial films on polycrystalline La2Ti2O7 substrates. We conclude that CSE approach opens the way towards unexpected electronic properties in oxide films. [less ▲]

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See detailStudy of supernovae and massive stars and prospects with the 4m International Liquid Mirror Telescope
Kumar, Brajesh ULg

Doctoral thesis (2014)

Massive stars are the progenitors of the most energetic explosions in the Universe such as core-collapse supernovae (CCSNe) and gamma ray bursts. During their life time they follow various evolutionary ... [more ▼]

Massive stars are the progenitors of the most energetic explosions in the Universe such as core-collapse supernovae (CCSNe) and gamma ray bursts. During their life time they follow various evolutionary phases (e.g. supergiant, luminous blue variable and Wolf-Rayet). They strongly influence their environments through their energetic ionization radiation and powerful stellar winds. Furthermore, the formation of low- and intermediate-mass stars are also being regulated by them. The Carina nebula region, which hosts a large population of massive stars and several young star clusters, provides an ideal target for studying the feedback of massive stars. In this thesis, we investigated a wide field (32′ × 31′ ) region located in the west of the Carina nebula and centered on the massive binary WR 22. For our study, we used new optical photometry (UBVRI Hα), along with some low resolution spectroscopy, archival near infra-red (2MASS), and X-ray (Chandra, XMM-Newton) data. We estimated several parameters such as reddening, reddening law, etc. and also identified young stellar objects located in the region under study (Kumar et al., 2014b). Among the various types of CCSNe, Type IIb are recognized with their typical observational properties. Some of them show clear indication of double peaks in their light curves. The spectral features of these SNe show a transition between Type II and Type Ib/c events at early and later epochs, respectively. It has been noticed that the occurrence of these events is not common in volume limited surveys. In this thesis we have studied the properties of the light curve and spectral evolution of the Type IIb supernova 2011fu. The observational properties of this object show resemblance to those of SN 1993J with a possible signature of the adiabatic cooling phase (Kumar et al., 2013). When light passes through the expanding ejecta of the SNe, it retains information about the orientation of the ejected layers. In general, CCSNe exhibit a significant level of polarization during various phases of their evolution at different wavelengths. We have investigated the broad band polarimetric properties of a Type II plateau SN 2012aw and compared it with other well-studied CCSNe of similar kinds (Kumar et al., 2014a). In the framework of the present thesis, we have also contributed to the development of the 4m International Liquid Mirror Telescope (ILMT) project which is a joint collaborative effort among different universities and research institutes in Belgium, India, Canada and Poland. We performed various experiments including the spin casting of the primary mirror, optical quality tests of the mercury surface, mylar film experiments, etc. The possible scientific capabilities and future contri- butions of this telescope are also discussed. We propose our plans to identify the transients (specially supernovae) with the ILMT and their further follow-up scheme. The installation of the ILMT will start very soon at the Devasthal observatory, ARIES Nainital, India. [less ▲]

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See detailEtude des produits de dissociation de H2O dans un échantillon de comètes d'origines variées
Decock, Alice ULg

Doctoral thesis (2014)

Les comètes sont connues pour contenir de grandes quantités d’eau et des molécules organiques en tout genre. Formées lors de la naissance de notre Système Solaire, il y a 4.6 milliards d’années, elles ... [more ▼]

Les comètes sont connues pour contenir de grandes quantités d’eau et des molécules organiques en tout genre. Formées lors de la naissance de notre Système Solaire, il y a 4.6 milliards d’années, elles n’ont ensuite pas beaucoup évolué, ce qui les rend témoins potentiels des processus physico-chimiques présents à cette période. L’étude des comètes permet donc d’en apprendre davantage sur leur propre nature encore potentiellement énigmatique, mais également sur notre Système Solaire lui-même, et tout particulièrement sa genèse. La mission européenne Rosetta, en orbite autour de la comète 67P/Churyumov-Gerasimenko témoigne de l’intérêt porté à ces petits corps gelés du Système Solaire. Cette mission est unique puisqu’elle va permettre pour la première fois de mesurer la composition chimique précise d’un noyau cométaire. Ce type de mission est par contre très coûteux et ne concerne qu’une comète en particulier. Avec des télescopes au sol, il est possible d’étudier un nombre plus important de comètes. Certes, le noyau n’est dans ce cas pas directement atteignable, mais la spectroscopie permet d’analyser l’atmosphère de la comète. Formée par la sublimation des glaces du noyau et la dissociation des molécules qui s’en échappent, la coma contient de nombreuses informations nous permettant d’accroître nos connaissances sur la composition chimique du noyau. L’objectif de cette thèse est l’étude des molécules liées à l’eau dans les comètes. Les glaces cométaires renferment en effet 80% d’eau. Etudier cette molécule est donc crucial pour définir la nature des comètes et comprendre les conditions physiques et chimiques régnant dans la coma. Toutefois, H2O n’est pas détectable dans le domaine de longueur d’onde visible. Sur base d’un ensemble de données spectroscopiques visibles acquises depuis le sol, nous proposons dans cette thèse l’analyse de deux produits de dissociation de la molécule d’eau observables dans l’atmosphère de la comète, l’oxygène atomique et le radical OH. Le premier volet de ce travail se concentre sur les trois raies interdites de l’oxygène localisées à 5577.339 Å pour la raie verte (O(1S)) et à 6300.304 Å et 6363.776 Å (O(1D)) pour les raies du doublet rouge en vue de déterminer la ou les molécules parentes à l’origine de ces atomes. Dans cette optique, nous avons créé un spectre synthétique de la molécule de C2 afin de décontaminer la raie verte des raies dues au C2. Ensuite, nous avons mesuré les rapports d’intensité et les largeurs intrinsèques des trois raies d’oxygène pour des comètes situées à différentes distances héliocentriques. La comparaison du rapport de l’intensité de la raie verte sur la somme des intensités des raies rouges (rapport G/R) avec les taux d’excitation fournis par la théorie montre que H2O est la molécule parente principale des atomes d’oxygène lorsque la comète est observée à r ∼ 1 ua. Par contre, lorsque la comète est loin du Soleil (>2.5 ua), les molécules de CO2 contribuent également à la production d’oxygène. La mesure des largeurs intrinsèques des raies montre que la raie verte est plus large que les raies rouges alors que la théorie prédit l’inverse. Découle de cette observation que la raie verte pourrait principalement provenir de la photodissociation du CO2 alors que les raies rouges seraient uniquement formées via H2O. En étudiant les raies d’oxygène à différentes distances du noyau cométaire, nous réalisons que la molécule parente de l’oxygène varie : le CO2 est le contributeur premier des atomes d’oxygène en deçà de ∼1000 km du noyau et laisse ensuite la place à H2O. Qui plus est, nous notons l’importance du quenching collisionnel produit par H2O dans la coma interne qui joue un rôle significatif dans la perte des atomes de O(1S) et O(1D). Un modèle d’émission est réalisé pour reproduire nos données observationnelles. En se penchant sur le comportement adopté par les raies d’oxygène près du noyau et sur l’ajustement fourni par le modèle, une estimation de l’abondance relative du CO2 est déterminée. Des lors, cette thèse présente une nouvelle méthode pour déterminer l’abon- dance CO2/H2O dans les comètes à partir de données obtenues depuis le sol alors qu’une mesure directe de la molécule de CO2 n’est jusqu’à ce jour possible que depuis l’Espace. La seconde partie de notre travail porte sur l’analyse des rapports isotopiques 16O/18O et D/H à partir des isotopes du radical OH. La connaissance des rapports isotopiques dans des comètes d’origines variées est importante car cela peut nous renseigner sur les conditions physiques et chimiques existantes lorsque la comète s’est formée. De plus, la mesure du D/H s’inscrit dans le débat actuel de l’origine des océans terrestres. Dans ce contexte, des spectres synthétiques de 16OH, 18OH et OD sont créés sur base d’un modèle de fluorescence. Le rapport 16O/18O est déduit pour la première fois par ce modèle pour la comète C/2012 F6 (Lemmon) et il établit le point de départ d’une longue série de mesures portées sur des comètes brillantes à venir. [less ▲]

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See detailLa naissance du livre de cuisine : Etude discursive des ouvrages culinaires d'Ancien Régime (1651-1799)
Colson, Maryse ULg

Doctoral thesis (2014)

Entre 1651 et 1799, l'édition culinaire de langue française connaît une efflorescence sans précédent ; conjointement, au coeur du 18e s., naît la Nouvelle Cuisine, mode culinaire qui se veut être l ... [more ▼]

Entre 1651 et 1799, l'édition culinaire de langue française connaît une efflorescence sans précédent ; conjointement, au coeur du 18e s., naît la Nouvelle Cuisine, mode culinaire qui se veut être l'adaptation bourgeoise des moeurs aristocratiques. Partant de ces deux prérequis, cette étude cherche à comprendre comment ces deux phénomènes ont participé à la structuration progressive de l'ouvrage culinaire, capitale dans son histoire et instigatrice du livre de cuisine contemporain. S'inspirant de concepts hérités de la narratologie, l'analyse se concentre sur deux aspects cruciaux des ouvrages culinaires - la situation d'énonciation et le péritexte - pour aboutir à une typologie. Nous distinguons ainsi le recueil de recettes, le manuel de cuisine, le livre de cuisine et l'avatar, ou dérivé culinaire. Cette étude met aussi en exergue le commentaire : portion discursive prise en charge par l'énonciateur et qui fait partie intégrante de l'appareil péritextuel des ouvrages culinaires. [less ▲]

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See detailL’émergence d’une politique foncière régionale en Bretagne : de l’identification des enjeux à la création d’un Etablissement public foncier d’Etat
Dupont, Josselin ULg

Doctoral thesis (2014)

During the last decades, we have experienced a general rise of real estate prices as well as the reinforcement of sustainable development issues. This resulted in a "renewal" of land policy in France ... [more ▼]

During the last decades, we have experienced a general rise of real estate prices as well as the reinforcement of sustainable development issues. This resulted in a "renewal" of land policy in France, with the development of “Etablissements publics fonciers” (EPF). At the same time, there is a withdrawal from the public sphere against a dominant financial logic. In this context, our thesis questions the need to develop land policy at the regional scale. To do so, we have examined the situation of Brittany on the basis of several partnerships (Regional Council, DREAL and EPF of Brittany, ADEF, COST and joint supervision with the University of Liege), with research materials gathered from three distinct research terrains (in Brittany, in France and in Europe). This leaded to a PhD structured in two main parts: on the one hand, a regional diagnostic on land issues for Brittany with a list of mobilized land data and, on the second hand, an original analysis of the EPF tool. Our results show that Brittany is facing fundamental land issues (fast land artificialization due to specific modes of living and demographic dynamics) that impact in different ways the regional territory (rural-urban and Armor-Argoat disparities). Our results also show that the choice of a regional land policy embodied in the creation of an EPF is at the same time very common from a French perspective and very original from a European perspective. In conclusion, we note that the effectiveness of EPF is not yet actually demonstrated and we propose recommendations to Brittany’s decision-makers. [less ▲]

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See detailSupercritical Carbon Dioxide Assisted Impregnation to Prepare Drug-eluting Polymer Implants
Champeau, Mathilde ULg

Doctoral thesis (2014)

The scCO2 impregnation process is a promising alternative to other manufacturing process to prepare drug-eluting polymer implants. This work enabled to rationalize the influence of the key parameters ... [more ▼]

The scCO2 impregnation process is a promising alternative to other manufacturing process to prepare drug-eluting polymer implants. This work enabled to rationalize the influence of the key parameters governing this process and to determine in which extent this process can be used to prepare drug-eluting implants. We have combined the information obtained with traditional polymer characterization techniques and a newly characterization set-up we have developed that is based on in situ FTIR micro-spectroscopy. We have worked on the impregnation of sutures made of PLLA, PP and PET with two anti-inflammatory drugs namely ketoprofen and aspirin. Firstly, the thermodynamic behaviors of the systems drug/CO2 (solubility and speciation of the drug) and polymer/CO2 (CO2 sorption, polymer swelling, evolution of the polymer microstructure and of the tensile properties) were studied as a function of pressure and temperature. Then, the scCO2 impregnation process was investigated. The impact of the operational conditions on the drug loading (contact time, pressure, temperature and depressurization conditions) was explored and accounted regarding to the CO2 sorption, the swelling, the drug solubility as well as the changes in the polymer microstructure with the experimental conditions and the presence of the drug. The drug/polymer affinity was also explored. The tensile properties of the impregnated fibers were also evaluated. PLLA was more impregnated (up to 32%) than PP and PET (up to 5%) in the investigated conditions. Finally, we have shown that the drug release can be tuned from 3 days to 3 months by varying the impregnation and depressurization conditions on the system PLLA/Ketoprofen. [less ▲]

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See detailcaractérisation physico-chimique et minéralogique de matériaux calcaro-dolomitiques en vue de la production de liants et produits dérivés
Matamba Jibikila, Raphaël ULg

Doctoral thesis (2014)

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial ... [more ▼]

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial sectors. Moreover, regardless of the scope of these materials, they must meet specific mineralogical and mechanical or physico-chemical properties, depending on the sector. Environmental requirements and sustainable management of mineral resources, have forced companies to reduce the value of naturally occurring materials, focusing oriented processing of waste materials or alternative approach. Moreover, technological developments have led to new applications requiring maximum purity of the material also led farmers to manage natural resources in a more rational manner. Mbuji-Mayi Region in the Democratic Republic of Congo, has huge limestone and dolomitic deposit; located in the " Mbuji-Mayi Supergroup". Nevertheless, the city suffers from a serious lack of sustainable infrastructure to consolidate its development and remains dependent on the supply of construction and building materials from other regions, located sometimes more than 1000 km from the Mbuji-Mayi site. The aim of this thesis is to investigate the potential use of Mbuji-Mayi supergroup materials to produce binder or derivated products in a sustainable management of mineral resources way. Thus, dolomitic samples were taken from Kanshi S13B and S70 Lubi drill cores, while limestone facies are from artisanal quarries in the region. They were then prepared and characterized. Techniques used are: X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), thermogravimetric analysis and the differential scanning calorimetry (TG-DSC), optical microscopy (OM) and scanning electron microscopy combined with chemical microanalysis (SEM / EDX). The results obtained after raw materials characterization showed that the Mbuji-Mayi Supergroup contains pure dolomite (respective mean CaO and MgO contents of 20.5 and 30%), impure dolomites and impure limestones. uniaxial compressive strength test, water absorption coefficient, and porosity were measured. Results were satisfactory in terms of the use of materials such as rubbles or building stones. Thermal and microscopic analyzes of pure dolomite, showed that these materials have high added value in the areas of refractory, glass manufacture or dolomitic lime production. Finally, a binder (CS1c) prepared from impure limestone, posted quite sufficient characteristics for applications with low mechanical stress. Metakaolin prepared from local raw material, was used to improve the characteristics of the binder CS1c. The analysis of the properties of the mixture CS1c-metakaolin, helped us to understand the role of some mineral phases, in contributing to the development of mechanical strength of such binders.   [less ▲]

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See detailEngineering of poly(2-oxazoline)s for a potential use in biomedical applications
Legros, Camille ULg

Doctoral thesis (2014)

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in ... [more ▼]

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in dilute media and in inverse emulsion based on a statistical copolymer made of 2-ethyl-2-oxazoline and ethylene imine units. These stimuli-responsive nanogels were swelling in acidic media and were cleaved in reductive environment. They proved to be non-cytotoxic and act as protein repellent. Second, a reactive platform based on a statistical POx polymer bearing aldehyde functionalities was engineered, enabling the synthesis of graft and cross-linked POx. Last, a block copolymer made of 2-methyl- and 2-isopropyl-2- oxazoline units, proved to self-assemble into micelles when heated above its LCST, for a short period of time (< 1h30). When annealed for a longer time (> 1h30), crystallization-driven self-assembly led to the formation of different morphologies (fiber rods and cross-linked micelles). [less ▲]

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See detailThe physical and biological controls on the distribution of gases and solutes in sea ice from ice growth to ice decay
Zhou, Jiayun ULg

Doctoral thesis (2014)

Les changements dans l’extension et les propriétés de la glace de la mer, liés au réchauffement climatique, affectent l’écosystème polaire, ainsi que les interactions entre l’atmosphère, la glace de mer ... [more ▼]

Les changements dans l’extension et les propriétés de la glace de la mer, liés au réchauffement climatique, affectent l’écosystème polaire, ainsi que les interactions entre l’atmosphère, la glace de mer et l’eau sous-jacente. Cependant, des incertitudes subsistent quant aux changements potentiels qui affecteront la biogéochimie de la glace de mer dans un futur proche. Afin de mieux comprendre les changements potentiels qui affecteront la biogéochimie de la glace de mer, nous avons étudié les facteurs qui influencent la distribution de certains composés dissouts (e.g., nutriments, matière organique dissoute (DOM)) et gazeux (e.g., Ar, O2, N2, CH4) au sein de la glace de mer, depuis la croissance de la glace, jusqu’à sa fonte. Les résultats ont été obtenus à partir d’une expérience de 19 jours dans un bassin expérimental à Hambourg (Allemagne) et une étude de terrain de 5 mois à Barrow (Alaska). Ils ont été ensuite comparés aux propriétés physiques de la glace (température, salinité et autres paramètres dérivés) et à des paramètres biologiques (activité bactérienne, abondance bactérienne, chlorophylle-a et phaeopigments). Nos travaux ont montré que les propriétés physiques de la glace exercent une forte influence sur la répartition des composes biogéochimiques dans la glace de mer, à travers leur impact sur la dynamique des saumures, la formation de bulles de gaz et la perméabilité de la glace. Nous avons décrit 4 stades dans la dynamique des saumures qui influencent la distribution des composés dissouts (e.g., silice et DOM) dans la glace. Cependant, le gaz inerte étudié (Ar) montre une dynamique différente de celle des composés dissouts, indiquant un mécanisme de transport différent. Nous suggérons que la formation de bulles de gaz dans la glace de mer est le mécanisme responsable de cette différence, parce que les bulles de gaz devraient migrer vers le haut, à cause de leur différence de densité par rapport aux saumures, alors que les saumures sont drainées vers le bas à cause de la gravité. Nos observations montrent également que le seuil critique de perméabilité pour l’ascension des bulles de gaz devrait se trouver entre 7.5 et 10 % de volume relatif en saumure ; seuil qui est plus élevé que les 5 % suggérés pour le transport de saumure vers le bas. L’augmentation de la perméabilité de la glace et les échanges de gaz prolongés tendent à amener les concentrations de gaz vers leur valeur de solubilité, sauf lorsque l’eau sous-jacente présente une sursaturation par rapport à l’atmosphère (e.g., CH4), ou lorsque une production in-situ se produit au sein de la glace (e.g., O2). Etant donné que l’ammonium et O2 s’accumulent clairement dans les couches de glace où la convection est limitée, nous suggérons que les variations de ces composés biogéochimiques dans la glace dépendent de la balance entre le transport physique et l’activité biologique ; l’impact de cette dernière sur les composés biogéochimiques est particulièrement visible lorsque le taux de production biologique du composé excède largement la vitesse d’élimination du composé par le transport physique. Nous avons ensuite discuté du potentiel d’utiliser Ar et N2 comme traceurs inertes pour corriger l’impact des processus physiques sur les variations de O2, afin de déterminer la production communautaire nette dans la glace de mer. Les propriétés chimiques de certains composés biogéochimiques (e.g., nitrate, ammonium, DOM) pourraient également influencer leur répartition au sein de la glace de mer, en plus des processus physiques et biologiques. Cependant, il est nécessaire d’avoir plus d’études à ce sujet pour confirmer cela. Enfin, sur base de nos résultats, nous présentons une mise à jour des processus qui régulent la répartition des gaz dans la glace de mer, avec des références à des observations récentes qui illustrent chacun des processus. Nous donnons également un aperçu des changements qui pourraient affecter la biogéochimie de la glace de mer à l’avenir, et des pistes de recherches pour une quantification précise de ces changements. [less ▲]

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See detailSynthesis of functionalized polyamide 6 by anionic ring-opening polymerization
Tunc, Deniz ULg

Doctoral thesis (2014)

The studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening ... [more ▼]

The studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening polymerization. By using this strategy, we describe: (i) the synthesis of thermally more stable fluorinated polyamide 6 having a hydrophobic surface; (ii) the synthesis of polyamides 6 bearing pendant cinnamoyl groups, which are thermo- and photoresponsivechromophore groups, and demonstrating their reversible crosslinking as well as improved thermo-mechanical properties; (iii) the copolymerization ofCL with a crosslinker (N-functionalized α-amino-ԑ-caprolactambis-monomers) into crosslinked polyamides 6.As part of our continuing interest in polyamide 6 chemistry, we developed the combination of anionic ring-opening polymerization of CL and chain-growth condensation polymerization of ethyl 4-butylaminobenzoate in order to obtain aliphatic/aromatic polyamides in one-step. [less ▲]

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See detailSilver Nanowire Networks: Effects of percolation and thermal annealing on physical properties
Langley, Daniel ULg

Doctoral thesis (2014)

The use of transparent conductive materials (TCMs) has rapidly increased in the last two decades as a result of the increasing demand for personal electronic devices and the development of thin film based ... [more ▼]

The use of transparent conductive materials (TCMs) has rapidly increased in the last two decades as a result of the increasing demand for personal electronic devices and the development of thin film based solar cells. To date, the most commonly used TCM is indium tin oxide (ITO). However indium is a rare earth metal with a complex geopolitical environment surrounding its supply and production. Furthermore, the oxide family suffers from poor mechanical properties such as brittleness and generally requires either high temperature synthesis (>400°C) or vacuum processes for their deposition. For these reasons, research in recent years has focused on the discovery or the design of a TCM to replace ITO. This thesis applies a dual approach combining simulations and experiments to explore the fabrication and optimisation of silver nanowire networks for use as a TCM and to improve the understanding of their physical properties. The simulation contribution focuses on the application of percolation modelling to 2D nanowire networks while the experimental part explores the electrical and optical properties of silver nanowire networks and their electrical behaviour under thermal annealing. We present in this work the modelling of 2D stick percolation systems initially composed of perfect idealised sticks, and then, investigate the influence of parameters such as length distributions, angular distributions or shape (curved nanowires). We address the divergence of the critical density for the onset of percolation observed for small system sizes and introduce some preliminary work on simulating the collection (or injection) efficiency of charges by a nanowire network. The experimental component provides a discussion of the impact of wire length, wire diameter, network density and fabrication technique on the optical and electrical properties of silver nanowire networks. An in-depth study of the effect of thermal annealing on the networks properties was undertaken, which revealed several mechanisms responsible for the initial reduction of resistance and the observed final loss of conductivity. An original observation enables the revelation of geometrical quantized percolation for rather sparse networks. Finally we conclude that silver nanowire networks are an excellent prospect as a TCM to replace ITO: these materials have superior mechanical properties and enable comparable and even superior electro-optical properties. [less ▲]

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See detailModelling serial offenders’ spatial behaviours: new assumptions for geographic profiling
Trotta, Marie ULg

Doctoral thesis (2014)

The geographic profiling is amethodology of investigation which uses the crime sites of a criminal series in order to delineate prior areas for searching the offender. Its implementation is currently ... [more ▼]

The geographic profiling is amethodology of investigation which uses the crime sites of a criminal series in order to delineate prior areas for searching the offender. Its implementation is currently limited by too simplistic assumptions that are difficult to assess during an investigation or even not corroborated at an individual level of observation. This thesis studies the predictive capacities of geographic profiling in the context of Belgium, a dense country where the road network is not suitable for classical algorithmimplemented with Euclidean or Manhattan distances. More precisely, the thesis has for first objective to integrate space anisotropy with two improvements: (1) the integration of the road network in the journey-to-crime and (2) the integration of the structure of opportunities for series of sexual offences. Beyond this objective, the thesis questions a hypothesis underlying this type of research methodology: the kind of spatial relationship between the offender’s residence and the crime sites. An alternative to the distance decay effect is developed, minimising the variance in travelled distances between the offender anchor point and the initial contact sites of the offences (MOV hypothesis). The sensitivity of this methodology is measured and its effectiveness is compared to the one of the distance decay effect. A major result of the thesis is that the share of behaviours than can be modelled by this new hypothesis is similar to the one of the distance decay effect. However, a large number of series did not meet the required conditions to implement an efficientmethodology given the multiplicity of offender’s residences or the scarcity of sites composing the series; those applicability criteria are analysed in this work. Nevertheless, theMOV hypothesis is particularly valuable for long series of offences. Then, the thesis analyses the impact of the geometry of crime series locations on the effectiveness of the chosen spatial assumption (distance decay effect orMOV) with graph theory. It highlights the superiority of the MOV hypothesis for offenders travelling in some preferred direction. The analysis also shows that both hypotheses are not mutually exclusive but can be combined to build offender geographic profiles. Finally, this thesis focuses on the modelling of neutral areas in terms of criminal attractiveness on the Belgian territory. The work presents the originality of analysing data on a whole country, integrating both urban and non-urban areas. The objective of the modelling is the integration of the opportunity structure of sexual offences in the geographic profile and the estimation of the perturbing effect of a differentiated attractiveness. In order to assess this perturbation, we propose a two-steps process. Firstly, a regression model combining factors fromthe crime pattern and social disorganisation theories models the spatial distribution of crimes. The regression model identifies a centre-periphery relationship in the spatial distribution of crime locations. Still, the model underestimates the number of positive sectors, omitting some attractors. Then, the impact of attractive location (i.e. presenting the favourable factors for crime concentration)is evaluated for the series of sexual offences. In fine, the two spatial hypotheses do not seem affected by the attractors identified by the modelling except when the contact sites are clustered in attractive areas. In addition, the share of serial offenders committing their offences in the most attractive locations is smaller than that of single offenders. This observation strengthens the need for working on spatial distribution models instead of calibrated functions with solved cases. [less ▲]

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See detailTraining alters the innate immune response in the lower airway of horses
Frellstedt, Linda ULg

Doctoral thesis (2014)

Many human and animal studies have examined various markers of the innate and/or adaptive immunity in association with exercise and have come to the general conclusion that exercise, either acute or ... [more ▼]

Many human and animal studies have examined various markers of the innate and/or adaptive immunity in association with exercise and have come to the general conclusion that exercise, either acute or chronic, modifies the immune response. Regular moderate exercise has beneficial and protective effects on immunity because it results in a balance of pro- and anti-inflammatory effects. This balance may be disturbed during exhaustive exercise, such as that experienced during competition and overtraining, resulting in immunosuppression. Humans frequently suffer from upper respiratory tract infections after prolonged intense exercise, whereas horses suffer primarily from lower airway inflammation and/or infection. The underlying mechanism for this difference remains unknown at this time. The sampling of different cell types is limited in humans and therefore, these studies focus on the evaluation of cells in peripheral blood or markers in saliva. Two groups of researchers in human sports medicine have compared populations of sedentary and regularly exercising people. The expression of Toll-like receptors (TLRs) 1, 2, 3 and 4 was decreased in peripheral blood monocytes in exercising subjects. This altered expression of TLRs was also associated with a lower production of pro-inflammatory cytokines (IL-6, IL-1α, TNF-α). Regular exercise induced circulating anti-inflammatory cytokines (IL-10, IL-6) and, therefore, limited the effects of pro-inflammatory cytokines. The first line of defense in the airways is provided by pulmonary alveolar macrophages and bronchial epithelial cells. Strenuous exercise impairs the viability of bronchial epithelial cells, reduces the viral defense mechanisms, and decreases oxidative burst activity of pulmonary alveolar macrophages. The altered immune response in association with exercise/training does not only lead to an increased risk for infection but may also cause the development of allergies and chronic inflammation in the lower airway. This may explain why young equine athletes frequently suffer from Inflammatory Airway Disease (IAD). The etiology of IAD remains unknown but an association with subclinical viral infections as well as inflammatory stimuli from the environment has been suspected. The objective of this work was to increase our knowledge of immune mechanisms in young equine athletes by evaluating the effect of acute exercise and training on the innate immune responses of pulmonary alveolar macrophages (PAM), bronchial epithelial cells (BEC) and monocytes. The hypothesis was that exercise and training modify the TLR mRNA expression as well as the production of pro-inflammatory cytokines and interferons in these three cell types. Eight Standardbred horses were studied over a period of 9 months during which they were acclimatized, trained and deconditioned. Standardized exercise tests were performed regularly and biological samples (blood, bronchoalveolar lavages, and biopsies of the bronchial epithelium) were taken at defined intervals in order to allow a longitudinal evaluation of the different parameters. Monocytes, PAM and BEC were harvested and analyzed. The expression of TLR3 was decreased in equine PAM and monocytes after a period of training, but not after a single strenuous exercise session. In addition, the expression of TLR4 was increased in equine monocytes after training. The production of TNF-α and IFN-β was also examined in PAM and monocytes ex vivo after the stimulation with different TLR ligands. The production of these cytokines was reduced in PAM after a defined period of training and remained decreased for three months thereafter. In contrast, the synthesis of TNF-α was increased after a period of training in equine monocytes and remained increased thereafter. In a second study, a model for the culture of equine bronchial epithelial cells (EBEC) was developed which allowed us to evaluate the effect of exercise and training on the innate immune response of these cells. Acute exercise or training did not alter the TLR mRNA expression in EBEC. The production of IFN-β was increased in EBEC from trained horses after stimulation with a TLR3 ligand. Concurrently, the secretion of TNF-α and IL-6 was impaired in EBEC from trained horses after the stimulation with TLR2 and TLR3 ligands. This study focused on a single aspect of the innate immunity in horses, gaining knowledge of the TLR expression in three cell types and their response to specific TLR agonists. These results have to be considered in the global context of the innate immunity remembering that they represent only a small part of the complex immune system. Only one type of training (Standardbred race training) and one model of acute exercise (standardized exercise test on a treadmill) were evaluated in this study. This should be considered when drawing conclusions, because it is currently understood that the effects on immune responses vary with different types, intensity and duration of exercise and/or training. Nonetheless, this work has established that a local immunosuppression develops within the lungs in trained horses, and may explain the increased susceptibility of exercising horses to pulmonary viral infections. This local immunosuppression is associated with an increased potential of monocytes to produce pro-inflammatory cytokines when challenged with pathogens. The effects of exercise on innate immunity are complex and further studies are needed to continue the work in this field. In addition to the response to training in young sport horses, a number of environmental factors associated with their nutrition and housing may play important roles in the development of pulmonary infections and inflammation (e.g. IAD). To confirm the significance of the presented results, it would be interesting to investigate the innate immune response in trained horses when challenged with equine pathogens, such as equine influenza and equine herpesviruses. The ultimate goal of this work and other studies in the future is to develop immuno-modulating molecules that could be used for the prevention and treatment of equine respiratory diseases. [less ▲]

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See detailManaging understory light to maintain the coexistence of forest tree species with different shade tolerances
Ligot, Gauthier ULg

Doctoral thesis (2014)

Similar to the management of the other environmental resources, forest management has been questioned and more sustainable practices of forest management are being sought. New close-to-nature practices ... [more ▼]

Similar to the management of the other environmental resources, forest management has been questioned and more sustainable practices of forest management are being sought. New close-to-nature practices aim to favor natural processes over human interventions. Particularly, continuous-cover forestry has the goal of relying on natural regeneration, and maintaining irregular stand structure and tree species mixture. However, maintaining mixture of species with different shade tolerances appears arduous with such a silvicultural system. Successfully managing irregular and mixed forests, relying on natural processes, requires a strong knowledge of the ecology of natural regeneration. In particular, strong knowledge is required to predict the result of the interspecific competition in the understory depending upon light availability. The amount of radiation transmitted to the understory is indeed a critical factor determining regeneration dynamics. It determines, at least in part, regeneration composition because of interspecific differences of growth and survival under shade. Moreover, our quantitative understanding of understory light in uneven-aged and mixed stands remains incomplete. A better quantitative understanding of understory light is needed to provide quantitative guidelines for the management of understory light in uneven-aged and mixed stands and, hence, for the management of natural regeneration. The purpose of this thesis is to determine how close-to-nature forest management can maintain mixtures of species with contrasting shade tolerances. I consider ecological conditions with good water and nutrient supplies. In these conditions, partially closed canopy limits the amount of light that reaches the understory, and light is the major factor driving regeneration composition. Consequently, I study the dynamics of natural regeneration with regards to light availability as well as the interception of light by the canopy of heterogeneous stands. Studying the regeneration ecology of two species with contrasting shade tolerances (Fagus sylvatica L. and Quercus petraea (Matt.) Liebl.), I find that the shade-tolerant species outgrow the less shade-tolerant species in all light conditions. Even though the control of understory light with continuous-cover silviculture is required to sustain the growth of less shade-tolerant regenerations, it might not be sufficient to maintain the coexistence of species with contrasting shade tolerances. In order to examine the effects of canopy structure and composition on understory light availability, I use a model of light interception by heterogeneous canopies after synthesizing and discussing the approaches reported in the literature. The model predicts satisfactorily measures of transmitted light even though it is a relatively simple radiative transfer model. I next explore how various silvicultural treatments can be manipulated to provide favorable understory light conditions for natural regeneration. These silvicultural strategies correspond to selective thinnings of five different types, e.g., harvesting preferentially small trees, large trees, or trees of shade-tolerant species or creating circular gaps. The results underline that creating favorable understory light conditions for natural regeneration can be achieved with various regeneration treatments. However, the adequate reduction of stand density depends upon the chosen silvicultural strategies. In particular, creating gaps of about 500 m2 provides adequate light for small regeneration clumps. Harvesting preferentially small and trees of shade-tolerant species are also appropriate but required higher harvest intensity. Harvesting preferentially large trees slightly increases understory light and promotes more shade-tolerant species than less shade-tolerant species. In order to maintain the coexistence of species with contrasting shade tolerances, forest manager must control understory light and manually suppress the regeneration of the shade-tolerant species. The outcome of this study provides foresters with the necessary tools to evaluate how silvicultural treatments can be manipulated to create or maintain favorable light conditions for the regeneration of species of different shade tolerances. Guidelines are additionally proposed for forest managers wanting to maintain the coexistence of species with contrasting shade tolerances. [less ▲]

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See detailRegularity of functions: Genericity and multifractal analysis
Esser, Céline ULg

Doctoral thesis (2014)

As surprising as it may seem, there exist functions of C∞(R) which are nowhere analytic. When such an unexpected object is found, a natural question is to ask whether many similar ones may exist. A ... [more ▼]

As surprising as it may seem, there exist functions of C∞(R) which are nowhere analytic. When such an unexpected object is found, a natural question is to ask whether many similar ones may exist. A classical technique is to use the Baire category theorem and the notion of residuality. This notion is purely topological and does not give any information about the measure of the set of objects satisfying such a property. In this purpose, the notion of prevalence has been introduced. Moreover, one could also wonder whether large algebraic structures of such objects can be constructed. This question is formalized by the notion of lineability. The first objective of the thesis is to go further into the study of nowhere analytic functions. It is known that the set of nowhere analytic functions is residual and lineable in C∞([0, 1]). We prove that the set of nowhere analytic functions is also prevalent in C∞([0, 1]). Those results of genericity are then generalized using Gevrey classes, which can be seen as intermediate between the space of analytic functions and the space of infinitely differentiable functions. We also study how far such results of genericity could be extended to spaces of ultradifferentiable functions, defined using weight sequences or using weight functions. The second main objective is to study the pointwise regularity of functions via their multifractal spectrum. Computing the multifractal spectrum of a function using directly its definition is an unattainable goal in most of the practical cases, but there exist heuristic methods, called multifractal formalisms, which allow to estimate this spectrum and which give satisfactory results in many situations. The Frisch-Parisi conjecture, classically used and based on Besov spaces, presents two disadvantages: it can only hold for spectra that are concave and it can only yield the increasing part of spectra. Concerning the first problem, the use of Snu spaces allows to deal with non-concave increasing spectra. Concerning the second problem, a generalization of the Frisch-Parisi conjecture obtained by replacing the role played by wavelet coefficients by wavelet leaders allows to recover the decreasing part of concave spectra. Our purpose in this thesis is to combine both approaches and define a new formalism derived from large deviations based on statistics of wavelet leaders. As expected, we show that this method yields non-concave spectra and is not limited to their increasing part. From the theoretical point of view, we prove that this formalism is more efficient than the previous wavelet-based multifractal formalisms. We present the underlying function space and endow it with a topology. [less ▲]

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See detailA Riemannian approach to large-scale constrained least-squares with symmetries
Mishra, Bamdev ULg

Doctoral thesis (2014)

This thesis deals with least-squares optimization on a manifold of equivalence relations, e.g., in the presence of symmetries which arise frequently in many applications. While least-squares cost ... [more ▼]

This thesis deals with least-squares optimization on a manifold of equivalence relations, e.g., in the presence of symmetries which arise frequently in many applications. While least-squares cost functions remain a popular way to model large-scale problems, the additional symmetry constraint should be interpreted as a way to make the modeling robust. Two fundamental examples are the matrix completion problem, a least-squares problem with rank constraints and the generalized eigenvalue problem, a least-squares problem with orthogonality constraints. The possible large-scale nature of these problems demands to exploit the problem structure as much as possible in order to design numerically efficient algorithms. The constrained least-squares problems are tackled in the framework of Riemannian optimization that has gained much popularity in recent years because of the special nature of orthogonality and rank constraints that have particular symmetries. Previous work on Riemannian optimization has mostly focused on the search space, exploiting the differential geometry of the constraint but disregarding the role of the cost function. We, on the other hand, propose to take both cost and constraints into account to propose a tailored Riemannian geometry. This is achieved by proposing novel Riemannian metrics. To this end, we show a basic connection between sequential quadratic programming and Riemannian gradient optimization and address the general question of selecting a metric in Riemannian optimization. We revisit quadratic optimization problems with orthogonality and rank constraints by generalizing various existing methods, like power, inverse and Rayleigh quotient iterations, and proposing novel ones that empirically compete with state-of-the-art algorithms. Overall, this thesis deals with exploiting two fundamental structures, least-squares and symmetry, in nonlinear optimization. [less ▲]

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See detailEtude et justification des courants de contact induits par les lignes à haute tension dans le parc résidentiel belge et leurs incidences sur la population.
Barbier, Pierre-Paul ULg

Doctoral thesis (2014)

Depuis les années septante, des recherches ont mis en avant une possible corrélation entre la leucémie infantile et les champs électriques et magnétiques générés par les lignes haute tension. Cette thèse ... [more ▼]

Depuis les années septante, des recherches ont mis en avant une possible corrélation entre la leucémie infantile et les champs électriques et magnétiques générés par les lignes haute tension. Cette thèse a pour vocation de mettre en avant un autre mécanisme indirect pouvant être un lien possible de cause à effet, les courants de contact. Le document explore différentes pistes (simulations, modèles) pouvant justifier l’apparition de ces courants. [less ▲]

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See detailContribution à l’étude du Plasma Riche en Plaquettes (PRP) dans le traitement des lésions tendineuses
Kaux, Jean-François ULg

Doctoral thesis (2014)

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and ... [more ▼]

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and wound healing. We made an extended literature review of the use of PRP in chronic tendinopathies. Despite the proven efficacy of PRP on tissue regeneration in experimental studies, there is currently scanty tangible clinical evidence with respect to its efficacy in chronic tendon disorders. The few studies that have been performed appear unlikely to be comparable. Randomized controlled studies with appropriate placebo groups are needed to determine the real effectiveness of PRP for treating chronic musculoskeletal injuries. After, we made a study to compare the platelet concentrations using 5 techniques of preparation of PRP and observed that each provides a very different PRP, with variations in the platelet concentrations and of the amount (if any) of erythrocytes and leucocytes. White blood cells could adversely affect wound healing through the release of proinflammatory factors responsible for extracellular matrix degradation. In addition, erythrocyte lysis releases free radicals that harm tissue structures. We thus think that ideal PRP should not contain any erythrocytes or leucocytes, and that the quality of the PRP could perhaps partially explain the variable results observed in the literature. The aim of our next study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. We concluded that an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance. Vascular endothelial growth factor (VEGF) is a platelet growth factor known to regulate angiogenesis. VEGF-111, a biologically active and proteolysis-resistant splice variant of this family, was recently identified. We made a study with the aim of evaluating whether VEGF-111 could have a therapeutic interest in tendon pathologies with the same rat protocol as our previous study. The force necessary to induce tendon rupture was greater for tendons of the VEGF-111 group (but less than the results obtained with the PRP in our previous study), while the section areas of the tendons were similar. The mechanical stress was similar at 5 and 15 days in both groups but was improved for the VEGF-111 group at day 30. No differences were observed in the mRNA expression of collagen III, tenomodulin and MMP-9. Finally, we made a study, the aim of which was to evaluate the clinical status and the return to sports activities in patients with chronic upper patellar tendinopathies, up to one year after a single infiltration of PRP. Twenty patients with chronic upper patellar tendinopathy were enrolled. Assessments were made before infiltration of PRP, and 6 weeks, 3 months and 1 year after the infiltration, using a 10-point Visual Analogic Scale, clinical examinations with a pressure algometer, algofunctional scores (IKDC and VISA-P), functional assessments (isokinetic and optojump evaluations) and imagery (ultrasounds and MRI). The PRP was obtained with an apheresis system (COM.TEC, Fresenius). Six millilitres of PRP were injected without local anaesthetic. One week after infiltration, patients started a standardised sub-maximal eccentric reeducation. We observed that with time, during the 1-year follow-up, VAS dropped significantly and both IKDC and VISA-P scores improved also significantly. During functional evaluation, it decreased as well, but without significant functional improvement. No improvements in the imagery measurements were observed. Younger patients seemed to be more susceptible to have a relief of pain by the PRP infiltration. Seventy percent of the patients reported a favourable evolution with decrease of pain, 15% reported no improvement and 15% were treated surgically. Seventy percent returned to sports activities, 64,3% without any pain and 50% recovered the same sports level. Even if 1 infiltration seems to be efficient in the indication of patellar tendinopathies, most studies evaluated the effects of 3 successive infiltrations. However, the multiplication of infiltrations risks increasing complications, and this treatment can be expensive. It seemed relevant to evaluate if 2 infiltrations of PRP would be more effective than only 1.Twenty patients suffering from jumper’s knee for more than 3 months were enrolled and randomized in 2 groups (1 or 2 infiltrations of PRP). The follow-up was made as follows: VAS, IKDC and VISA-P scores, algometer, isokinetic and ultrasounds evaluations. The concentration of the PRP used for each infiltration was similar in both groups, without any red or white blood cells. Results for all the evaluations did not show any difference between the groups. The comparison of 1 or 2 infiltrations of PRP did not show any difference between the 2 groups after a follow-up of 3 months. A second close infiltration of PRP to treat upper patellar tendinopathies is not necessary to improve the efficacy of this treatment in the short term. However, these results must be evaluated at a longer term. [less ▲]

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See detailMultibody Modelling of Mechanical Transmission Systems in Vehicle Dynamics
Virlez, Geoffrey ULg

Doctoral thesis (2014)

This thesis addresses the dynamic modelling of automotive driveline components by means of the nonlinear finite element method for flexible multibody systems. Starting from a detailed study of an ... [more ▼]

This thesis addresses the dynamic modelling of automotive driveline components by means of the nonlinear finite element method for flexible multibody systems. Starting from a detailed study of an industrial application, the TORSEN differential, several contributions are proposed in the field of contact modelling. The contact between rigid bodies in several geometric configurations is investigated and the influence of the squeeze film of lubricating oil is studied. A contact formulation between flexible bodies modelled as superelements is also developed and applied to the modelling of 3D flexible gear pairs. [less ▲]

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See detailFunction of the chloroplastic hydrogenase in the microalga Chlamydomonas reinhardtii: A trvel from dark to light
Godaux, Damien ULg

Doctoral thesis (2014)

The decreasing availability of fossil energy stocks and the eventuality of tragic climate changes caused by greenhouse gases lead to search for alternative renewable energy sources. Biological hydrogen ... [more ▼]

The decreasing availability of fossil energy stocks and the eventuality of tragic climate changes caused by greenhouse gases lead to search for alternative renewable energy sources. Biological hydrogen might be one promising renewable energy carrier. A specific and restricted group of microalgae developed the ability to produce hydrogen based on an oxygen-sensitive hydrogenase enzyme coupled to the photosynthetic pathway, acting as a putative valve for excess electrons in conditions where other electron acceptors are scarce. The unicellular green alga Chlamydomonas reinhardtii is widely regarded as a model organism for various biological processes, especially for photosynthesis. Moreover, the capacity of Chlamydomonas hydrogenase is claimed as the highest recorded in literature. Less than twenty years ago, a group of American scientists designed a new approach for sustained photobiological production of hydrogen, based on a two-stage protocol that temporally separates photosynthetic O2 evolution from the H2 production phase (Melis et al., 2000). The transition occurs upon sulfur deprivation of the culture and leads to an operating continuous production for several days, opening new possibilities in the aim of an economically rentable bioproduction. For these reasons, hydrogen photoproduction in Chlamydomonas reinhardtii has been extensively examined in the last decade as extension of photosynthesis research entailing the understanding of hydrogen metabolism in microalgae (for reviews, see Hankamer et al., 2007; Ghirardi et al., 2009; Ghysels and Franck, 2010). Despite the attractive trait of generating a renewable fuel from nature’s most plentiful resources, i.e. light and water, the physiological significance of such oxygen-sensitive enzyme coupled to oxygenic photosynthesis has been poorly investigated with the exception of some old studies (Kessler, 1973; Schreiber and Vidaver, 1974). In this work, hydrogenase implication in photosynthetic reactivation from dark and anoxic environment is investigated. In the first part of the work, by analyzing several strains affected in hydrogen metabolism (e.g. nda2-RNAi (Jans et al., 2008), pfl1 (Philipps et al., 2011), dum11 (Dorthu et al., 1992)), we show that the PSII–dependent photosynthetic electron flow upon dark to light shift is linearly related to the activity of hydrogenase, both for short and long-terms adaptation (Publication I). In agreement with this conclusion, a hydrogenase-deficient strain for the HydEF maturation factor (hydef, Posewitz et al., 2004) shows peculiar chlorophyll fluorescence induction kinetics after adaptation to dark and anoxia. Based on these findings, a novel imaging screening method is developed, allowing rapid identification of strains impaired in hydrogen metabolism. Compared to existing screens (for review, see Hemschemeier et al., 2009), our protocol is remarkably fast, sensitive and non-invasive. At this stage, application of this new screening method allowed us to isolate several hydrogenase-deficient strains, among which one was impaired for the hydrogenase maturation protein HydG (hydg-2 mutant). Chlamydomonas reinhardtii might frequently encounter period of dark and anoxia in its natural habitat, especially during the night when the microbial community respires the available oxygen. In the second part of my work, the physiological importance of hydrogenase is investigated in the context of photosynthesis induction at the onset of light upon anoxia. In such conditions, the plastoquinone pool is known as being overreduced. This triggers the process of state transitions which is described as allowing the redistribution of light capture between both photosystems to manage the redox poise of the photosynthetic pathway (for review, see Lemeille and Rochaix, 2010). We therefore revisit the impact of both state transitions and hydrogenase activity on the reactivation of photosynthetic electron flow (Publication II). Here we show that, in presence of hydrogenase, photosynthesis reactivation is slightly faster in stt7 mutant locked in state 1 (Depege et al., 2003) compared to wild type which is in state 2. However, photosynthesis reactivation is delayed in hydef stt7-9 double mutant compared to hydef mutant. This indicates that, in a hydrogenase-deficient context, state 2 promotes photosynthesis reactivation. Considered for a long time as being tightly interconnected (Finazzi et al., 1999; Finazzi et al., 2002; Finazzi and Forti, 2004), state transitions and PSI-CEF have recently been revealed as unrelated to each other (Takahashi et al., 2013). Nonetheless, the increasing of PSI antenna size in state 2 could even though enhance the PSI-CEF rate, in an indirect way, by enhancing PSI energy capture (Cardol et al., 2009; Alric, 2014). This reasonably raises the question of a possible involvement of PSI-CEF in photosynthesis induction. This possibility is further studied in the third and last part of the work. Thanks to mutants devoid of PSI-CEF (i.e. pgrl1 mutant (Tolleter et al., 2011)) and hydrogenase activity (i.e. hydg-2 mutant (Publication I)), we investigate the role played by PSI-CEF along with hydrogenase during photosynthesis reactivation during a shift from dark anoxia to light (Publication III). Herein, we demonstrate that Calvin cycle reactivation is proton gradient-dependent, most likely due to ATP requirement for carbon dioxide fixation. By measuring the PSI/PSII efficiency ratio during the re- illumination period, we point out the physiological occurrence of PSI-CEF within the first minutes of ilumination. We therefore propose a schematic model that assesses the electron flow through hydrogenase, PSI-CEF and Calvin cycle in function of the illumination period in all studied strains. Although lack of PSI-CEF does not appear to be essential for cell survival, photosynthesis reactivation is delayed in pgrl1 mutants. We also isolate a pgrl1 hydg-2 double mutant and demonstrate that the combination of both defects prevents any photosynthetic activity and strongly impairs growth. This highlights the importance for algae to keep both pathways in the course of evolution, being critical for the survival of Chlamydomonas reinhardtii in its natural environment. [less ▲]

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See detailÉTUDE DU COMPLEXE ENZYMATIQUE DES SYMBIONTES DU TERMITE RETICULITERMES FLAVIPES (EX. SANTONENSIS)
Tarayre, Cédric ULg

Doctoral thesis (2014)

In the light of the economic, environmental and social context in which we live today, it has become obvious that the use of fossil fuels is not conceivable over the long term. Some alternatives have ... [more ▼]

In the light of the economic, environmental and social context in which we live today, it has become obvious that the use of fossil fuels is not conceivable over the long term. Some alternatives have therefore emerged in recent years. Second-generation biofuels are one of those alternatives and are based on the exploitation of vegetal biomass, also called lignocellulosic biomass. These materials require a hydrolysis step which can notably be achieved by enzymes. Some insects, such as termites, harbor complex microbial communities inside their digestive tracts. Those communities are able to produce enzymes which can be used in the field of the hydrolysis of vegetal biomass. This is what this thesis deals with. The main part of the work done focused on the research of enzyme-producing microorganisms (bacteria, mycetes and protists) responsible for the degradation of hemicelluloses and cellulose, the hydrolysis of which releases fermentable sugars. The insect which was used in this work was Reticulitermes flavipes (ex. santonensis), a lower termite, harboring a highly diversified internal microflora. This thesis describes the characterization of the microbial strains which were isolated and the enzymes they secrete. A complementary part of this research focussed on termites grown on artificial diets. The objective of this part was multiple : isolating enzyme-producing strains, not extractable according to the standard technique, and characterizing the microflora resulting from the applied artificial diets. This multidisciplinary approach was based on microscopy, proteomics, metagenomics and the assessment of metabolism applied to the different microbial consortia. [less ▲]

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See detailUnderstanding Random Forests: From Theory to Practice
Louppe, Gilles ULg

Doctoral thesis (2014)

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations ... [more ▼]

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations, unraveling underlying patterns in data and providing insights about the problem. Yet, caution should avoid using machine learning as a black-box tool, but rather consider it as a methodology, with a rational thought process that is entirely dependent on the problem under study. In particular, the use of algorithms should ideally require a reasonable understanding of their mechanisms, properties and limitations, in order to better apprehend and interpret their results. Accordingly, the goal of this thesis is to provide an in-depth analysis of random forests, consistently calling into question each and every part of the algorithm, in order to shed new light on its learning capabilities, inner workings and interpretability. The first part of this work studies the induction of decision trees and the construction of ensembles of randomized trees, motivating their design and purpose whenever possible. Our contributions follow with an original complexity analysis of random forests, showing their good computational performance and scalability, along with an in-depth discussion of their implementation details, as contributed within Scikit-Learn. In the second part of this work, we analyze and discuss the interpretability of random forests in the eyes of variable importance measures. The core of our contributions rests in the theoretical characterization of the Mean Decrease of Impurity variable importance measure, from which we prove and derive some of its properties in the case of multiway totally randomized trees and in asymptotic conditions. In consequence of this work, our analysis demonstrates that variable importances as computed from non-totally randomized trees (e.g., standard Random Forest) suffer from a combination of defects, due to masking effects, misestimations of node impurity or due to the binary structure of decision trees. Finally, the last part of this dissertation addresses limitations of random forests in the context of large datasets. Through extensive experiments, we show that subsampling both samples and features simultaneously provides on par performance while lowering at the same time the memory requirements. Overall this paradigm highlights an intriguing practical fact: there is often no need to build single models over immensely large datasets. Good performance can often be achieved by building models on (very) small random parts of the data and then combining them all in an ensemble, thereby avoiding all practical burdens of making large data fit into memory. [less ▲]

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See detailModelling the hygrothermal behaviour of crop-based construction materials
Dubois, Samuel ULg

Doctoral thesis (2014)

In the context of developing sustainable buildings, crop-based construction materials appear as valuable products given their intrinsic environmental and technical qualities. Their ability to exchange ... [more ▼]

In the context of developing sustainable buildings, crop-based construction materials appear as valuable products given their intrinsic environmental and technical qualities. Their ability to exchange moisture with the surrounding environment and damping humidity peaks in rooms, referred to as moisture buffering, is often presented as a way to improve occupants comfort and otentially reduce the operational energy of the building. It is understandable why modelling their hygrothermal behaviour and evaluating the impact on indoor air volumes is essential during the design phases. This thesis explores themodelling of the hygrothermal behaviour of crop-basedmaterials with a numerical tool. The latter is developed in a widespread general computational environment that brings both modularity and interoperability. Three challenges are addressed: the improvement of mathematical description of crop-based materials in non-standard operating conditions, the improvement of materials properties determination, and the assessment of their impact at room-scale. Several experimental facilities are developed in parallel to validate the proposed approaches, focusing on two materials expected to improve indoor conditions: straw bales and lime-hemp concrete. Results show that the developedmodel allows improving the understanding and the characterization of these green materials at various scales of study. [less ▲]

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See detailTheoretical studies of PbTiO3 and SrTiO3 under uniaxial mechanical constraints combining first-principles calculations and phenomenological Landau theory
Sharma, Henu ULg

Doctoral thesis (2014)

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory ... [more ▼]

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory. ABO$_3$ perovskites form a very important class of functional materials that can exhibit a broad range of properties (e.g., superconductivity, magnetism, ferroelectricity, multiferroism, metal-insulator transitions\ldots) within small distortions of the same simple prototype cubic structure. Though these compounds have been extensively studied both experimentally and computationally, there are still unresolved issues regarding the effect of pressure. In recent years, strain engineering has reported to be an original approach to tune the ferroelectric properties of perovskite ABO$_3$ compounds. While the effect of epitaxial biaxial strain and hydrostatic strain is rather well understood in this class of materials, very little is yet known regarding the effect of uniaxial mechanical constraints. Our study is motivated by the little existing understanding of the effect of uniaxial strain and stress, that has been up to now almost totally neglected. Two prototype compounds are studied in detail: PbTiO$_3$ and SrTiO$_3$. After a general introduction on ABO$_3$ compounds and calculations techniques (ab initio and phenomenological Landau model), we studied the effect of mechanical constraints in these compounds in our thesis. PbTiO$_3$ is a prototypical ferroelectric compound and also one of the parent components of the Pb(Zr,Ti)O$_3$ solid solution (PZT), which is the most widely used piezoelectrics. For PbTiO$_3$, we have shown that irrespectively of the uniaxial mechanical constraint applied, the system keeps a purely ferroelectric ground-state, with the polarization aligned either along the constraint direction ($FE_z$ phase) or along one of the pseudo-cubic axis perpendicular to it ($FE_x$ phase). This contrasts with the case of isotropic or biaxial mechanical constraints for which novel phases combining ferroelectric and antiferrodistortive motions have been previously reported. Under uniaxial strain, PbTiO$_3$ switches from a $FE_x$ ground state under compressive strain to $FE_z$ ground-state under tensile strain, beyond a critical strain $\eta_{zz}^c \approx +1$\%. Under uniaxial stress, PbTiO$_3$ exhibits either a $FE_x$ ground state under compression ($\sigma_{zz} < 0$) or a $FE_z$ ground state under tension ($\sigma_{zz} > 0$). Here, however, an abrupt jump of the structural parameters is also predicted under both compressive and tensile stresses at critical values $\sigma_{zz} \approx$ $+2$ GPa and $- 8$ GPa. This behavior appears similar to that predicted under negative isotropic pressure and might reveal practically useful to enhance the piezoelectric response in nanodevices. The second compound of interest is SrTiO$_3$. It has been widely studied in the past decades due to its unusual properties at low temperature. In this work, we have extended our previous investigations on PbTiO$_3$ by exploring theoretically the pressure effects on perovskite SrTiO$_3$ combining the first-principles calculations and a phenomenological Landau model. We have discussed the evolution of phonon frequencies of SrTiO$_3$ with the three isotropic, uniaxial and biaxial strains using first-principles calculations. We also reproduce the previous work done in SrTiO$_3$ with epitaxial strain and hydrostatic strain. Finally, we have calculated the phase diagram of SrTiO$_3$ under uniaxial strain, as obtained from Landau theory and discussed how it compares with the first-principles calculations. [less ▲]

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See detailEtude du rôle des sites de N-glycosylation dans la pathogenèse induite par le virus de la leucémie bovine
De Brogniez, Alix ULg

Doctoral thesis (2014)

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes ... [more ▼]

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes économiques importantes dans l’industrie laitière et viandeuse de nombreux pays dont notamment les Etats-Unis, l’Argentine et le Brésil. Ce rétrovirus infecte les lymphocytes B à l’aide de ses glycoprotéines virales SU et TM qui fusionnent avec la membrane cellulaire. Bien que de nombreuses études se soient penchées sur la caractérisation de la propagation virale, les composants cellulaires et viraux impliqués dans le contrôle de ce mécanisme ne sont toujours pas élucidés. Mon projet de thèse s’est donc attaché à la compréhension du rôle joué par les 8 sites potentiels de glycosylation présents sur la protéine SU du BLV. Chaque site du gène a été muté individuellement par mutagenèse dirigée. L’expression, la localisation, la capacité de fusion cellulaire et la stabilité protéique ont d’abord été étudiées en culture. Des provirus mutés ont ensuite été inoculés à des moutons afin d’évaluer leur potentiel infectieux et de suivre l’évolution de la pathogenèse induite. Nos études ont permis de mettre en évidence un mécanisme de glycosylation qui limite la réplication virale et ralentit la pathogenèse en faveur de la persistance virale. [less ▲]

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See detailBehavioral ecology and commensal long-tailed macaque (Macaca fascicularis) populations in Bali, Indonesia: impact of anthropic factors
Brotcorne, Fany ULg

Doctoral thesis (2014)

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges ... [more ▼]

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges for wildlife populations, another option relies on the sharing of space, i.e., tolerating wildlife living alongside human populations in non-protected interface zones. During the last century, massive human encroachment into wildlife natural habitat has led to an increasing number of worldwide interface zones and a consecutive intensification of the human-wildlife conflict which is likely to escalate further as human populations rapidly expand. However, conflict does not account for all the scenarios since diverse forms of interaction between humans and wildlife exist. The human-nonhuman primate commensalism is one of these possible interspecies associations. Commensal (or synanthropic) primates are free-ranging populations ecologically associated with humans in anthropogenic habitats and taking advantage of human food, waste or crops to supplement their diet. In Bali, Indonesia, humans and long-tailed macaques (Macaca fascicularis) already have a long history of coexistence. The forest-agricultural matrix landscape of the island and the numerous religious Hindu temples provide habitat patches for macaques sometimes living in very close proximity to humans. The opportunistic style of this species enables it to exploit numerous habitat types. However little is known about the ways anthropic factors impact its behavioral ecology. Our intention was to conduct a comparative study which would investigate whether anthropic factors were potential drivers of the behavioral ecology and population dynamics of Balinese macaques. During a two-year period in the field (between 2009 and 2013), using a protocol including three populations of Balinese macaques made of ten social groups, we documented variations in the activity, dietary, ranging and demographic patterns between populations. We systematically investigated the anthropogenic influences (i.e. human food provisioning degree and habitat anthropization level) on those variations, and we questioned the biological significance of the responses in terms of costs and benefits. While daily following each social group of macaques, we collected spatial, behavioral and botanical data, and we further conducted bi-annual demographic census in order to estimate the status and demographic trends of the study groups. Finally, our interest was to link our results with applied concerns regarding the management of these populations interacting with humans, while taking into account the implications of these interactions from the human point of view. We found a remarkable eco-behavioral diversity between our studied populations. Human food was a central component of their ecology, macaques preferentially exploiting this resource when available while retaining their abilities to forage on natural resources. The inclination for human food was optimal for macaques as it maximized their energy intake while minimizing the time expended for food acquisition. Therefore, they adjusted their activity budget according to the proportions of human food consumed. The free time available from relaxed foraging constraints was invested into resting and social activities. Macaques were flexible in their movements, making them successful in exploiting natural forest areas as well as highly anthropogenic habitats. However, increased social tension was a cost that stemmed from high-density situations induced by excessive anthropization of their habitat. We showed that, although predation risk partially influenced the selection of sleeping trees, proximity to human settlements appeared to be the most influential factor in the essential process of sleeping site choice by long-tailed macaques living at the edge of the forest and anthropogenic zones. Demographic data provide essential information to assess the status of a population and the long-term impacts of human pressures. Overall, our three studied populations displayed good reproductive performances and positive growth rates, probably due to the human food consumed. Indeed, we showed that the human food abundance in tourist sites may have diminished the density-dependence mechanism on macaques’ birth rates, to eventually inflate the size of populations. When combined with a high level of habitat anthropization, these effects have led to high local densities and even overcrowded situations with associated costs regarding within and between-group social tension and epidemic risks. In this framework, we documented the demographic and social impacts of a Streptococcus outbreak which occurred in the Ubud population in 2012. The pre- and post-epidemic study showed that macaques modified their social dynamics following a significant mortality in certain groups. This study emphasized the role of pathogens in regulating primate populations living in zones of interface with humans. Our research also contributed to identify solutions regarding management of these populations increasingly interacting with humans in Bali. We notably provided preliminary evidence that vasectomy, as sterilization technique to control for overpopulation, had no negative side-effects on social and sexual behaviors of male macaques. Finally, we assessed the effect of a ten-year management regime at the Ubud Monkey Forest, using an ethnoprimatological approach. We showed that the aggressiveness of macaques towards visitors had been effectively reduced and the high tolerance of local people towards macaques was determined by economic and cultural benefits deriving from the macaque presence. However, we also identified men and adult or subadult male macaques as the most exposed groups to a potential risk of cross-species pathogen transmission given the frequency of close physical contact interactions at this site. [less ▲]

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See detailModélisation et étude expérimentale du comportement de Saccharomyces cerevisiae (boulardii) lors de l'extrapolation du procédé à des bioréacteurs de volume industriel
Lejeune, Annick ULg

Doctoral thesis (2014)

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales ... [more ▼]

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales qui peuvent être dommageables pour les cellules se développant dans le réacteur. Il est donc important de prendre en compte le côté génie chimique pour comprendre quelles sont les conditions hydrodynamiques présentes dans le réacteur et ensuite s’attacher à étudier la réponse des cellules vis-à-vis de ces conditions. Ce travail se place dans le cas particulier de la production de biomasse de Saccharomyces cerevisiae (boulardii). Dans ce cas, le point critique est l’ajout de la solution concentrée de substrat dans le réacteur. L’utilisation de réacteurs scale-down a permis d’étudier différents cas de conditions hydrodynamiques défavorables, ainsi que leurs impacts sur différents paramètres. Dans un premier temps, l’étude des paramètres ségrégés (concentration en biomasse, en co-produits…) a montré, notamment, une diminution du rendement et une augmentation de la concentration en éthanol. Ensuite, l’étude s’est placée au niveau cellulaire avec l’utilisation de souches exprimant une protéine recombinante fluorescente et de marqueurs cellulaires fluorescents, couplée à la cytométrie en flux. Ces techniques ont permis de mettre en évidence la présence de différentes sous-populations cellulaires, ainsi que l’apparition du phénomène de résistance cellulaire aux stress lors de la production en réacteurs scale-down. L’importance du choix de la méthode de traitement des données cytométriques a également été débattue. Ce travail a abordé différents domaines pour tenter de mieux comprendre la réponse cellulaire aux fluctuations des conditions environnementales ressenties par Saccharomyces cerevisiae (boulardii) lors de productions en réacteurs mimant les conditions hydrodynamiques des réacteurs de grands volumes. [less ▲]

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See detailBilan de carbone d'une prairie pâturée en Région wallonne: effets du climat et de la gestion du pâturage
Jerome, Elisabeth ULg

Doctoral thesis (2014)

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – ... [more ▼]

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – CH4), this PhD investigates the C balance of an intensively managed grazed grassland in the temperate climate of southern Belgium. It analyses more particularly impact of climatic conditions and management practices on the C balance. The research site is a permanent grassland, covering 4.22 ha, intensively used for more than 50 years for Belgian Blue cattle grazing with the application of organic and inorganic fertilizers. Management practices but also climatic conditions are representative of livestock production systems developed in southern Belgium. Over a three years study period, soil C stock variations are determined indirectly by measuring the balance of C fluxes at the system boundaries. This approach not only takes into account CO2 and CH4 exchanged with the atmosphere but also organic C imports (manures, complementary feedings), exports (harvests, animal products) and C lost through leaching. CO2 fluxes are measured by eddy covariance while other C fluxes are estimated from data provided directly by the farmer, from punctual measurements and from aboveground herbage mass measurements. Considering only assimilation and respiration, the ecosystem behaves, on average, as a weak CO2 source, although the interannual variability is large. Interannual variability seems not to be significantly correlated with the main environmental drivers but rather influenced by fertilization management. Taking other C fluxes into account, the site appears as being at equilibrium. Management (organic fertilization), as well as climatic conditions that dictated them (complementary feeds), are the principal factors influencing the C balance. Finally, results show that management practices were the key control of the C flux variability at this grassland. Grazing impact on CO2 fluxes appears not explicitly at the seasonal and annual scale. It is therefore quantified by developing innovative eddy covariance data analyses and experiments. For that, indirect and direct grazing impacts are separated. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle modifying CO2 exchanges. To quantify it, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalised dark respiration (Rd,10) is analysed. On average, GPPmax decreases during grazing periods and increases during non-grazing periods. This could respectively be explained by aboveground biomass reduction and re-growth. In addition, GPPmax variations are negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 is found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. Direct impact results from livestock CO2 emissions through respiration that adds to the total ecosystem respiration. It is emphasized through specific designed livestock confinement experiments. Net CO2 exchange is compared on successive days with similar climatic conditions, livestock being confined (≈ 26 livestock units ha-1), or not, in the main wind direction area of the eddy covariance set-up. Results obtained are corroborated by independent estimates based on the C ingested by cattle during confinement. Finally, the C balance analysis of this particular grazed grassland in southern Belgium reveals that, taking into account the climatic conditions observed and the management practices developed over the three study years, the site is C neutral. This means that GHG emissions linked to fertilization (N2O) and grazing (CH4) are not partly mitigated by soil C sequestration. However, we conclude that, management practices being the main factor controlling the C balance, strategies to enhance soil C sequestration exist. If those kinds of management practices are studied, a global approach, taking into consideration both the C fluxes and other GHG fluxes, would be required to see if they do not induce supplementary N2O and CH4 emissions. [less ▲]

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See detailPotentialités et limites de la gestion participative des Aires Marines Protégées : Le cas de Joal-Fadiouth, Sénégal
Sene, Claude ULg

Doctoral thesis (2014)

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus ... [more ▼]

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus, this thesis aims to contribute to this emerging debate on MPA governance through reflections about the experience of a conservation project implemented by an international NGO (WWF WMPAO) in collaboration with the State and the local populations in Joal-Fadiouth, with a view to identify the catalysts social factors. The results show that the objectives of the MPA project are not purely local; they are strongly influenced by a global standard as well as regional and national dynamics. Thus, the MPA is much more seen as a conservation tool, whith sanctuarization as philosophical and conceptual basis. This logic of action has led to a real discrepancy between the original objectives and the outcomes in daily practice in the field. The victory of "sanctuarization" on local development, despite discourses based on a constructive approach of the integration paradigm, gave rise to tensions and multiple repulsive reactions and claims in relation to local territorial rights. And in this respect, MPA is a “reserve with reservation”: it refers, on the one hand to a "sanctuarized" space and, on the other, to an increasingly challenged social acceptance in relationship to local territorial dynamics. This thesis has shown, through three case studies, the real potential of co-management regimes, which main catalyst factors are, but not limited to, the setting in the core of the process of actors with real decision-making powers and responsibilities, of information and awareness raising, of financial incentives to overcome the limitations, of integration of scientific expertise to endogenous knowledge, of support of the State and its decentralized services, and of the strengthening of local capacities ... Those co-management experiences offer real additional strategic options to the MPA tool in a global approach to fisheries governance and territorialized development. However, the results of the thesis show also the limits of participatory management induced by the projects (obligation of results short time-frame) through the "formatting of local institutions of governance" especially a Management Committee, which is struggling to meet its "excessive" responsibilities in light of its very limited resources. This committee has become a "local brokerage arena" which captures and capitalizes on co-management resources and means; which tends to move the real power towards "intermediary actors" who serve as populations/State interface or even "exploit" the administration officials. This thesis has also highlighted the paradox of the State that justifies and provides legitimacy to local co-management processes through legal institutionalization, but does not mobilize the legal, financial, human and logistical resources required to guarantee and secure the implementation of the agreements reached between the different actors. It has more of a posture of an organizing State than that of a State guarantor of management agreements. [less ▲]

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See detailEtude de la fibrose pulmonaire idiopathique canine: analyse du transcriptome, investigation des voies du TGF beta 1 et recherche de biomarqueurs
Krafft, Emilie ULg

Doctoral thesis (2014)

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a ... [more ▼]

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a progressive deterioration until death from respiratory insufficiency. Clinical, tomodensitometric and histological characteristics of cIPF have been described recently. However, this disease remains largely unknown and the clinicians are dealing with two major challenges: confirmation of the diagnosis, which requires many complementary exams, and absence of effective treatment. Identification of a targeted therapy is difficult without having a good understanding of the mechanisms leading to pulmonary parenchyma fibrosis. A similar disease, the idiopathic pulmonary fibrosis (IPF) is recognized in humans and cIPF might be interesting as a spontaneous model. This project in dogs was undertaken to answer, at least partly, to these challenges. The aims were to elucidate some mechanisms involved in cIPF pathogenesis and to identify biomarkers that could be used in the diagnosis process. The hypotheses were first that analysis of the transcriptome through microarray experiment would identify altered biological functions in cIPF, highlight specific molecules with an altered expression and identify potential biomarkers. Another hypothesis was the transforming growth factor beta 1 (TGFB1) pathways, considered central in the pathogenesis of IPF, would also be modified in cIPF. Finally, ET1, a known biomarker in human IPF, might also be an interesting biomarker in dogs. Gene expression analysis through microarray analysis, combined with the use of IPA, a data analysis program, identified altered biological functions in cIPF: cellular growth and proliferation, developmental processes, cellular movement, cell to cell signaling and interaction and antigen presentation. Some genes highlighted in the microarray experiment were then analyzed individually. Quantitative RT-PCR analysis confirmed an upregulation of the expression of CCL2, CCL7, CXCL14, IL8 and FAP (fibroblast activation protein) as well as a downregulation of the expression of PLUNC (palate, lung and nasal epithelium associated). We then complete the gene expression analysis with a search for potential biomarkers. Thirty-four potential biomarkers were identified with 32 biomarkers potentially measurable in blood (including CCL2, serum amyloid 1, IL8) and 2 biomarkers measurable only in the bronchoalveolar lavage fluid (BALF) (PLUNC and mesothelin). This approach was validated by measurement in serum of one of this biomarker: CCL2. CCL2 serum concentration was higher in affected WHWT compared to healthy WHWT and also higher in dogs with cIPF compared to dogs with chronic bronchitis (CB) or eosinophilic bronchopneumopathy (EBP). Based on serum CCL2 determination, cIPF was diagnosed with a sensibility of 92% and a specificity of 80%. We then studied TGFB1 and part of its storage, activation and signaling pathways. TGFB1 gene expression was not significantly different in the pulmonary parenchyma between affected and control dogs. However, in affected dogs, increased TGFB1 protein levels were seen by immunohistochemistry in fibrotic areas. High expression of bothTGFB1 type I receptor and phosphorylated Smad2/3, markers of an active intracellular TGFB1 signal, were seen in epithelial cells. No difference in expression for the storage proteins LTBP1 and LTBP2 was seen while expression of LTBP4 was significantly decreased in dogs with cIPF. Concerning the proteins involved in TGFB1 activation, gene expression was decreased for integrin subunit β8, increased for thrombospondin-1 and not modified for integrin subunit β6. Expression of Smad 7, involved in intracellular TGFB1 signal inhibition, was not modified. No difference for TGFB1 serum concentration was seen between WHWT with cIPF and healthy WHWT. A multivariate analysis performed on healthy dogs showed no age effect but a significant breed effect with higher levels in predisposed breeds. We evaluated part of the serotonin pathway, as one of its receptor (5HTR2B) was highlighted during the gene expression analysis. Serotonin has also been involved in the pathogenesis of human IPF and described to be of potential use as a biomarker in degenerative mitral valve disease in dogs. Expression of 2 serotonin receptors (5HTR2A and 5HTR2B), evaluated by quantitative RT-PCR in pulmonary tissue, was not different between dogs with cIPF and control dogs while expression of the serotonin transporter (5HTT) was significantly lower in affected dogs. No difference in serotonin serum level was seen between affected and healthy WHWT or between dogs with cIPF, CB or EBP. ET1 was evaluated as a biomarker in serum and BALF. ET1 serum concentration was not different between healthy WHWT and Beagles. Covariance analysis did not reveal any significant age effect. Serum levels were significantly higher in dogs with cIPF compared to dogs with CB or EBP. ROC curve analysis was then used to evaluate its diagnostic performances. The area under the curve was 0,818 with a sensitivity of 91.7% and a specificity of 87.5%. ET1 was also measured in the BALF in a small number of dogs. Its concentration was measurable in all dogs with cIPF while it was below the detection limit in all other dogs tested (healthy and with CB). Even though cIPF and human IPF are not completely identical from clinical, tomodensitometric or histological points of view, these results show that both canine and human diseases share molecular pathways, supporting the idea that cIPF might have an interest as spontaneous model. This work allowed a better understanding of cIPF pathogenesis. Gene expression analysis in the pulmonary parenchyma of affected dogs first identified several altered biological functions that should be analyzed in details in further studies. A more targeted analysis of some genes confirmed an upregulated expression of CCL2, CCL7, CXCL14, IL8 and FAP. Such a positive regulation of the expression of various inflammatory cytokines tends to suggest that inflammation might have a role in cIPF pathogenesis. Some of these cytokines also have profibrotic properties. PLUNC was one of the top down-regulated genes. Roles of the protein are still largely unknown; it might have a role in the inflammatory response and in the innate immunity. Developmental pathways were also altered in cIPF and quantitative RT-PCR confirmed an upregulation of FAP, a protein normally expressed in areas of tissue remodeling during fetal development and also positively regulated in human IPF. This study has shown that there is an active TGFB1 signal in the lungs of dogs with cIPF, especially at the level of the pathological epithelium. TGFB1 storage and activation pathways also seemed to be altered. Elevated TGFB1 circulating levels were found in predisposed breeds, which might explain at least partly their susceptibility for cIPF. Because of these results and its well-known profibrotic properties, we can suggest that TGFB1 is probably involved in cIPF pathogenesis and that modulation of its storage, activation or intracellular signaling might offer potential therapeutic targets. Our preliminary results are not in favor of a significant modification of the serotonin pathways in cIPF, although a decreased expression of 5HTT was seen in affected dogs and might have an impact on the amount of serotonin present locally. However, other studies are needed to conclude. Finally, several potential biomarkers have been identified and some of them were evaluated in details. While serum measurements performed for TGFB1 and serotonin indicated that these molecules have no interest as diagnostic biomarkers, ET1 and CCL2 were identified as interesting candidates with good diagnostic performances. However these results need to be confirmed in an independent validation cohort and the interest of combining both biomarkers should be evaluated. [less ▲]

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See detailValorisation de l’information pédologique numérisée pour la modélisation de la percolation des pesticides vers les eaux souterraines
Bah, Boubacar Billo ULg

Doctoral thesis (2014)

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required ... [more ▼]

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required standard (0.1 µg L-1 by pesticide and 0.5 µg L-1 for all pesticides) for human drinking water is most often exceeded at some catchments. Tools such as mechanistic models are appropriate since they allow an a priori estimation of pesticide concentrations leached at the bottom of soil profile, which could reach the groundwater tables. However, simulations often lead to a degree of uncertainty due to the approximations noted in the models, or due to the reliability of available data. The main objective of this thesis was to improve the usefulness of the Digital Soil Map of Wallonia (DSMW) and the associated soil analysis database named “Aardewerk” in the framework of the evaluation of the groundwater table contamination by pesticides, in order to reduce approximations associated with the GeoPEARL model and its meta-model MetaPEARL in the area of Condroz. In order to cover the broad spectrum of pesticides used in agriculture in Wallonia, nine theoretical pesticides have been defined. The first research question is to measure the sensitivity of GeoPEARL to two soil data parameterization schemes at the regional scale, depending on whether we first aggregate soil data at a regional scale before application of the model (AC approach); or we first apply the model to soil profiles and aggregate simulated leached concentrations afterwards (CA approach). The results show a significant difference between the two approaches, compared on the basis of a spatial threshold (80th percentile) calculated by soil type. Moreover, this difference varies depending on pesticide type, and is more important when the simulated concentrations are very low. It is also clear from this analysis that only pesticides located in certain ranges of DT50 (30 and 67 days) and Kom (58 and 252 dm3 kg-1) give concentrations more often above water potability standard of 0.1 µg L-1. The second research question is to calibrate MetaPEARL metamodel (simplified model) based on GeoPEARL simulated concentrations, from which it was derived by considering only the most sensitive parameters of GeoPEARL. The objective by developing a metamodel is to provide a simple tool, usable for a first evaluation of pesticides leaching in order to identify the most risk-prone areas, but also readily transposable for a global decision support system. In contrast to the approach of MetaPEARL calibration used until now, taking into account soil morphology through soil horizons (layers) types explains about 80% of the spatial variability of pesticide concentrations obtained from the complete original GeoPEARL model. The third research question is to take into account the spatial variability of input variables within the same soil typological unit using stochastic simulations to assess the uncertainty associated with deterministic simulations (taking into account average values by soil type for the input variables at the regional scale) obtained from MetaPEARL. The random spread of soil characteristics variability leads to a very significant spreading of simulated pesticide concentrations. Moreover, we obtain values of 80th spatial probabilistic percentile higher than those obtained from the deterministic approach. Consequently, for a risk mapping designed to aid decision-making tools, the probabilistic approach should be used since it allows, by taking into account the spatial variability of the model input parameters, to obtain more realistic concentrations of leached pesticides. [less ▲]

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See detailMOLECULAR TOOLS APPLIED TO THE STUDY OF MICROCYSTIN-PRODUCING CYANOBACTERIA IN BELGIAN WATERBODIES
Lara, Yannick ULg

Doctoral thesis (2014)

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries ... [more ▼]

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries. These amenities are affected by recurrent mass proliferations of cyanobacteria. The latter are responsible for the production of a wide range of bioactive compounds, including potent toxins (cyanotoxins). These comprise neurotoxins, cytotoxins, inflammatory agents, and hepatotoxins. Microcystins (MCs), hepatotoxins and tumour promoters are the most documented of the cyanotoxins. The microcystin synthetase gene cluster (mcy) involved in MC biosynthesis consists of a succession of non-ribosomal peptide synthase (NRPS) and polyketide synthetase (PKS) genes. The main producers of MCs are Anabaena, Microcystis, and Planktothrix. However, it is not possible to distinguish a toxic from a non-toxic strain on the basis of their morphology. In the present study, molecular tools were used, optimized and developed to (i) characterize the 16S rRNA gene diversity of planktonic cyanobacteria, (ii) to detect the cyanobacteria responsible for the production of MCs, (iii) to identify the MCs producing taxa, and (iv) to determine the environmental factors that influence the dynamic of toxic and non-toxic genotypes in Belgian freshwaters. Eighty-nine strains were isolated and their 16S rRNA genes sequenced. The 16S rRNA gene diversity was studied in 32 samples by denaturing gradient gel electrophoresis (DGGE). In order to evaluate the contribution of this work to the study of the molecular diversity of cyanobacteria in Belgian waterbodies, 114 (strains and DGGE) sequences obtained during this PhD thesis were compared to Belgian sequences obtained by others. As a result, 14 previously undiscribed operational taxonomic units (OTUs) were found in the present study. For polymerase chain reaction (PCR) detection of the mcyA/B/E genes, the DNA from a total of 162 environmental samples was extracted. The three genes were found together in 64.2% of the samples, whereas the mcyB alone was detected in 95.1% of the samples. In order to identify the mcyE-carriers present in the freshwaters, a restriction fragment length polymorphism (RFLP) was performed on the mcyE gene. The presence of potentially toxic Microcystis was observed in most of the cases.To bypass the constraint of bacterial cultivation, a combination of whole genome amplification (WGA) and enzyme-linked immunoassay (ELISA) was tested on individual colonies of members of two cyanobacteria, Microcystis and Woronichinia, directly from the natural environment. Sequences of 3 different housekeeping genes (ftsZ, gltX, and recA), of 3 mcy genes, and the Internal Transcribed Spacer (ITS) were analyzed for 11 colonies of Microcystis. MCs were detected and quantified by ELISA in 7 of the 11 Microcystis colonies tested, in agreement with the detection of mcy genes. Sequence types (ST) based on the concatenated sequences of housekeeping genes from cyanobacterial colonies from Belgian water bodies appeared to be endemic when compared to those of strains described in the literature. One colony belonged to a yet undiscovered lineage. A similar protocol was used for 6 colonies of the genus Woronichinia, a taxon that is very difficult to cultivate in the laboratory. The 16S rRNA analysis confirmed the colony identification based on morphology. In addition, we obtained for the first time new genetic data for this genus, such as the rpoC1 gene sequences and the sequences and secondary structures of the ITS. The first discovery of NRPS and PKS DNA sequences in Woronichinia colonies highlights the need for further study of this widely occurring genus, to better assess its ability to produce MCs and/or related metabolites. For the first time, in this study, we were able to simultaneously monitor one toxic and one non-toxic genotype of M. aeruginosa using real time qPCR technology during a monitoring of 2 years. Both toxic and non-toxic genotypes dynamics appeared influenced by the photoperiod. In addition, the dynamic of the toxic genotype was influenced of light intensity. The results obtained during this PhD research show the need to characterize toxic cyanobacteria in freshwaters, as well as the conditions that influence MCs concentration dynamics. We showed that factors controlling the dynamics of toxic and non-toxic genotypes are complex. Nevertheless, detection tools can be developed to better understand these widely occurring phenomena. Therefore, efforts should go on in this field with collaborations between the scientists and the authorities. [less ▲]

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See detailBiologie de la reproduction et analyse du déterminisme et de la différenciation du sexe à des stades précoces chez le tilapia du Nil, Oreochromis niloticus
Gennotte, Vincent ULg

Doctoral thesis (2014)

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental ... [more ▼]

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental), ainsi que par une plasticité du contrôle génétique et endocrinien de la différenciation sexuelle incomparables parmi les autres vertébrés. Le tilapia du Nil (Oreochromis niloticus) est un cichlidé gonochorique possédant un système chromosomique de déterminisme sexuel à homogamétie femelle XX/XY, complété par un déterminisme environnemental, les hautes températures pouvant modifier le développement phénotypique du sexe. L’intérêt porté à cette espèce en aquaculture à conduit au développement de différentes techniques de contrôle du sexe (par traitement hormonal) permettant la production de poissons présentant différentes combinaisons de phénotype/génotype sexuels (mâles XX, XY, YY, femelles XX, XY et YY). Ces derniers constituent des outils majeurs de l’étude du déterminisme et de la différenciation du sexe et soulèvent de nombreuses questions concernant les interactions génotype/phénotype sexuels chez cette espèce. Au regard de ces considérations, nous nous sommes fixés 2 objectifs principaux : 1. Déterminer l’influence du génotype sexuel sur certains aspects liés à la biologie reproductive chez le tilapia du Nil tels que la qualité du sperme, les taux de stéroïdes sexuels (testostérone, T ; 17β-œstradiol, E2 ; 11-cétotestostérone, 11KT) et les comportements agressifs. Le génotype sexuel ne semble pas avoir d’influence sur la qualité gamétique des mâles, puisqu’aucune différence n’est observée entre les individus XX, XY et YY, alors que paradoxalement, les taux de 11KT sont plus élevés chez les mâles XX. De la même manière, les femelles présentent des taux croissants d’E2 chez les individus XX, XY et YY. Ces différences de taux de stéroïdes sexuels pourraient être liées aux taux d’agressivité (évalué par la quantification de huit comportements agonistiques dans des confrontations mâle-femelle) plus élevés des mâles XX et des femelles XY et YY et engendrer des perturbations des comportements reproducteurs. Des recherches complémentaires sont nécessaires d’une part, pour évaluer l’effet du génotype sur la qualité des gamètes des femelles et d’autre part, pour déterminer si les modifications phénotypiques observées sont liées à l’expression du génotype sexuel ou à des perturbations engendrées par les traitements hormonaux d’inversion sexuelle administrés durant la période de différenciation des gonades. 2. Explorer les mécanismes du déterminisme et de la différenciation à des stades précoces du développement. Grâce à la mise au point d’une technique d’inversion sexuelle ciblant les périodes embryonnaire et larvaire (avant 10 jpf) par des expositions courtes (4h) d’embryons âgés d’un jpf à des androgènes (11KT, 17α-méthyltestostérone), un inhibiteur de l’aromatase (Fadrozole) ou un œstrogène (17α-éthynylœstradiol), nous avons confirmé l’existence d’une période sensible de la différenciation sexuelle avant le développement des gonades. Les voies de différenciation phénotypique semblent être différentes en fonction du génotype, puisque la masculinisation des embryons XX est moins efficace (max 10%) que la féminisation d’embryons XY (max 91%). De la même manière, un probable effet chromosomique rend inefficace la féminisation d’embryons YY. La féminisation des individus XY est concomitante avec une augmentation des taux de T et d’E2 et d’expression de l’aromatase cérébrale à 4 jpf qui pourrait indiquer un rôle précoce du cerveau dans la différenciation sexuelle. Dans l’ensemble, nos résultats nous permettent de suggérer, d’une part, que les premiers événements moléculaires de la différenciation sexuelle du tilapia sont initiés avant la formation des gonades, et d’autre part, que chez les individus sexuellement inversés, des différences sexuelles peuvent apparaître dans le cerveau avant ou en même temps que le développement des gonades et induire des modifications comportementales à l’âge adulte. La question du rôle possible du cerveau dans la différenciation des gonades reste ouverte. [less ▲]

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See detailOrigin and properties of the two-dimensional electron gas at the LaAlO3/SrTiO3 interface: a first-principles hybrid functional study.
Fontaine, Denis ULg

Doctoral thesis (2014)

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations ... [more ▼]

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations are required, especially in oxide interfaces, where new and amazing phenomena can arise. A prototypical example is the LaAlO3-SrTiO3 interface that appear to be conducting, magnetic or even supra-conducting while these properties are not present in the LaAlO3 and SrTiO3 bulk insulator compounds. The conductivity arises from the formation of a highly localized electron gas at the interface which exhibits a different behavior than the one at semiconductor interfaces. Even nowadays, its exact origin, intrinsic versus extrinsic, is still intensively debated. The existence of an electric field in LaAlO3 used as a key feature of models based on an intrinsic origin is highly controversial. In these models, the closing of the band gap with increasing LaAlO3 film thicknesses finally results to a Zener breakdown and to the metal/insulator transition. In this Ph.D. thesis we aim to investigate the various consequences of the presence of an electric field in LaAlO3 through first-principles calculations in pristine LaAlO3-SrTiO3 interfaces. First, using both experimental and theoretical structural distortions in LaAlO3, we predicted a lattice expansion via an electrostrictive effect, supporting the existence of an electric field in LaAlO3. Second, the metal/insulator transition was tuned with regards to the intensity of the electric field in the film, which was controlled by the composition of a solid solution between LaAlO3 and SrTiO3. The theoretical results match the experimental one where, nevertheless, extrinsic origin mechanisms are allowed and defects are present. These two works are in favors of an intrinsic origin of the electronic gas observed in LaAlO3-SrTiO3 heterostructures. In addition, a relationship between the sheet carrier density and spatial extension of the gas was established and thus setting an intrinsic threshold to the sheet carrier concentration. At lower density the electrons are strictly localized close to the interface while above this value the carriers start to spill into the SrTiO3 substrate. [less ▲]

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See detailAnalyse de la variabilité naturelle du climat : application à l’aide des ondelettes
Mabille, Georges ULg

Doctoral thesis (2014)

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes ... [more ▼]

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes développé à l’Institut de Mathématique de l’Université de Liège, sont de l’ordre de quelques dizaines de mois. [less ▲]

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See detailMultiscale Finite Element Modeling of Nonlinear Quasistatic Electromagnetic Problems
Niyonzima, Innocent ULg

Doctoral thesis (2014)

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft ... [more ▼]

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft magnetic composites, used in the so-called magnetoquasistatic (low frequency) regime. Current homogenization models (e.g. the classical homogenization method, mean field homogenization, ...) fail to handle all the difficulties raised by the modeling of these materials, particularly taking into account the complexity of their microstructure and their nonlinear/hysteretic behaviour. In this thesis we develop a multiscale computational method which allows to effectively solve multiscale magnetoquasistatic problems. The technique is inspired by the HMM (heterogeneous multiscale method), which involves the resolution of two types of problems: a macroscale problem that captures slow variations of the overall solution, and many mesoscale problems that allow to determine the constitutive laws at the macroscale and to construct accurate local fields. Macroscale and mesoscale weak, b-conform and h-conform formulations, are derived starting from the two-scale convergence and the periodic unfolding methods. We also use the asymptotic homogenization method for deriving the homogenized linear material laws and, in the end, we derive scale transitions for bridging the scales. Numerical tests carried out in the two-dimensional case allow to validate the models. In the case of b-conform formulations, it is shown that the macroscale solution approximates well the average of the reference solution and that the resolution of the mesoscale problems allows to reconstruct accurate local fields and to compute accurate Joule losses and this, for materials with (non)linear and hysteretic behavior. Similar findings were obtained for the h-conform formulations. In both cases, the deterioration of the accuracy for mesoscale problems located near the boundary of the computational domain could be treated by defining suit- able mesoscale problems near such boundaries. The extension of the model to three-dimensional problems, to multiphysical problems and the inclusion of the mesoscale domains with a stochastic distribution of phases are also some of the possible prospects for improving this work. [less ▲]

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See detailDéveloppement de nouvelles méthodes de marquage au fluor-18 pour peptides et oligonucléotides en vue de leur études par tomographie par émission de positons
Flagothier, Jessica ULg

Doctoral thesis (2014)

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears ... [more ▼]

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears often as the radionuclide of choice for the preparation of short-lived positron-emitter radiotracers for PET studies. The fluorine-18 labelling reaction for biomolecules requires very mild conditions. The current method for highly efficient fluorine-18 labelling of biomolecules is the conjugation of a [18F]prosthetic group with a reactive function on the organic compound. During this thesis, two techniques were developed to label biomolecules via a [18F]prosthetic group: the first one to label tyrosine-containing peptides and the second one to label a siRNA. The first part of this work present the synthesis of the [18F]F-PTAD which is a agent for specific radiolabelling of tyrosine. [18F]F-PTAD was coupled with a tyrosine with a global radiochemical yield (synthesis, coupling, purification) of 20% (DC) and the synthesis lasts 2h30. During the second part of this work, two alkyne-bearing linkers were synthesized. These linkers were ligated with siRNA and then reacted with azide-bearing [18F]prosthetic group via a Huisgen cycloaddition reaction. The [18F]siRNA is then obtained with an global radiochemical yield of 12% (DC) and the synthesis lasts 2h00. In conclusion, two methods for labeling biomolecules have been developed. [less ▲]

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See detailFamily from afar: Moroccan migration, family practices and the transnational social space
Zickgraf, Caroline ULg

Doctoral thesis (2014)

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives ... [more ▼]

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives and analyzes their subsequent construction and reconstruction of familyhood across national borders. Through a multi-sited qualitative study into Moroccan family networks with residential nodes in Liège, Belgium and Oujda, Morocco, but also several other destinations, Caroline Zickgraf considers both the material and non-material functions of transnational family practices that together produce and inflate transnational social spaces. She treats both the social and physical geographies of these networks in order to understand how the circulation of people affects the circulation of care but also treats the tensions and asymmetries that characterize their multi-directional cross-border exchanges. [less ▲]

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