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See detailContributions to Monte Carlo Search
Lupien St-Pierre, David ULg

Doctoral thesis (2013)

This research is motivated by improving decision making under uncertainty and in particular for games and symbolic regression. The present dissertation gathers research contributions in the field of Monte ... [more ▼]

This research is motivated by improving decision making under uncertainty and in particular for games and symbolic regression. The present dissertation gathers research contributions in the field of Monte Carlo Search. These contributions are focused around the selection, the simulation and the recommendation policies. Moreover, we develop a methodology to automatically generate an MCS algorithm for a given problem. For the selection policy, in most of the bandit literature, it is assumed that there is no structure or similarities between arms. Thus each arm is independent from one another. In several instances however, arms can be closely related. We show both theoretically and empirically, that a significant improvement over the state-of-the-art selection policies is possible. For the contribution on simulation policy, we focus on the symbolic regression problem and ponder on how to consistently generate different expressions by changing the probability to draw each symbol. We formalize the situation into an optimization problem and try different approaches. We show a clear improvement in the sampling process for any length. We further test the best approach by embedding it into a MCS algorithm and it still shows an improvement. For the contribution on recommendation policy, we study the most common in combination with selection policies. A good recommendation policy is a policy that works well with a given selection policy. We show that there is a trend that seems to favor a robust recommendation policy over a riskier one. We also present a contribution where we automatically generate several MCS algorithms from a list of core components upon which most MCS algorithms are built upon and compare them to generic algorithms. The results show that it often enables discovering new variants of MCS that significantly outperform generic MCS algorithms. [less ▲]

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See detailBody condition score and milk fatty acids as indicators of dairy cattle reproductive performances
Bastin, Catherine ULg

Doctoral thesis (2013)

Improving cow fertility by means of genetic selection has become increasingly important over the last years in order to overcome the decline in dairy cow fertility that has taken place over the past ... [more ▼]

Improving cow fertility by means of genetic selection has become increasingly important over the last years in order to overcome the decline in dairy cow fertility that has taken place over the past decades. However, fertility traits are difficult to measure and have low heritabilities. Consequently, indicator traits are of interest for breeding value estimation for fertility especially if these traits are easier to measure, have higher heritabilities and are well correlated with fertility. Therefore, the objective of this thesis was to investigate the opportunity of using either fatty acid contents (FA) in milk predicted by mid-infrared spectrometry or body condition score (BCS; i.e., a subjective measure of the amount of metabolizable energy stored in a live animal) as indicator traits of female fertility. Research conducted on BCS and fertility records from Canadian Ayrshire and Holstein cows indicated that BCS was heritable and showed a low to moderate favorable genetic correlation with fertility suggesting that higher BCS would be related to better fertility. Also, based on results obtained on Walloon data, selection for higher nadir BCS was suggested as useful to change BCS curve over the lactation and improve fertility. Furthermore, using records from Walloon Holstein cows, FA were demonstrated to be moderately heritable. Genetic correlations among FA and fertility were low to moderate and changed over the lactation. Overall, the pattern of genetic correlations of fertility with BCS and FA substantiated the known relationship between energy balance status and fertility. Body fat mobilization in early lactation induces BCS loss. Also, the release of long-chain FA in milk from the body fat mobilization inhibits de novo FA synthesis in the mammary gland, leading to a decrease of short- and medium- chain FA. To conclude, this research has shown that traits based on BCS and milk FA profile fulfill criteria to be considered as indicator traits to improve indirectly fertility of dairy cows. [less ▲]

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See detailEpigenetic regulation of angiogenesis
Shiva Shankar, Thammadihalli Veerasangaiah ULg

Doctoral thesis (2013)

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See detailAnalysis of solar air-conditioning systems and their integration in buildings
Thomas, Sébastien ULg

Doctoral thesis (2013)

Due to economical and environmental concerns, the energy e fficiency of buildings nowadays has proven to play an increasingly important role. To satisfy the occupants comfort, the cooling of buildings ... [more ▼]

Due to economical and environmental concerns, the energy e fficiency of buildings nowadays has proven to play an increasingly important role. To satisfy the occupants comfort, the cooling of buildings generally involves a considerable consumption of electricity. Solar radiation, which is a free and renewable resource, is linked to the cooling needs of buildings. This work consists in the evaluation, from an energy-saving and economical point of view, of a potential use of solar energy for air-conditioning in residential and o ffice buildings. It includes an integral approach of solar air-conditioning, involving the analysis of the buildings cooling needs, the cold production devices, the solar collector fields and climates. This analysis is supported by simulations and experimental setups. The study of solar air-conditioning systems already available on the market or in laboratories reveals their operational principles as well as their main performance indicators. Two main solar cooling paths are investigated: a thermal and a photovoltaic conversion of solar energy. Besides this, the performance of the entire air-conditioning system broadens the question of the energy performance to the interactions between the diff erent parts of the system. The building thermal loads (heating, cooling, domestic hot water) of some theoretical residential and o ffice buildings are computed in a part of this work dealing with the influence of the comfort model, the building energy performance level and the climate. What comes across through this analysis is that, the location of the buildings put aside, the cooling load is greatly influenced by the envelope thermal performance and the internal gains. The cooling systems involving absorption or adsorption or vapour compression chiller cooling machines are simulated for the previously defi ned building cases. The use of solar energy through thermal collectors for heating meets higher primary energy savings than for cooling. In all cases, the thermally driven system achieves a lower energy and economical performance than a vapour compression chiller partially supplied with a photovoltaic field. Some real scale testing of solar air-conditioning systems was carried out in Arlon (Belgium). A thermally driven adsorption chiller and a vapour compression chiller with a photovoltaic grid-connected fi eld were operated during the cooling season. The measurements made during this experiment and their analysis manage to discover every thermal and electrical energy flows of the systems leading to a new adsorption chiller model. Concerning the comparison with the simulations, the main point of interest is the consumption of electricity dedicated to thermally driven systems, which is two times higher in real scale conditions. The results obtained from the monitoring campaigns corroborate the simulation results about system comparison. [less ▲]

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See detailO2: Dr Jekyll and Mr Hyde in symbiotic dinoflagellates (Symbiodinium) from reef-building corals
Roberty, Stéphane ULg

Doctoral thesis (2013)

Coral reefs are among the most beautiful and complex of all ecosystems on Earth. Although they cover less than 1% of the world’s oceans area, this marine ecosystem harbors a huge biodiversity and is vital ... [more ▼]

Coral reefs are among the most beautiful and complex of all ecosystems on Earth. Although they cover less than 1% of the world’s oceans area, this marine ecosystem harbors a huge biodiversity and is vital to human society and industries. The foundation of coral reefs relies on the fragile mutualistic relationship between reef-building corals and their photosynthetic dinoflagellates of the genus Symbiodinium. However, this symbiosis is highly sensitive to environmental or anthropogenic disturbances and may be disrupted, thus leading to the coral bleaching phenomenon. It has been reported that the initial steps of this process are linked to photosynthesis and the antioxidant network in Symbiodinium. However the nature of the cellular mechanisms leading to the generation of reactive oxygen species and to the disruption of the symbiosis is not completely unraveled. Therefore, this study aimed to highlight the existence of photosynthetic alternative electron flows reducing molecular oxygen and the way by which they can induces an oxidative stress, in four Symbiodinium strains belonging to three different clades. Joint measurements of oxygen evolution, PSI and PSII activities by chlorophyll a fluorescence and spectrophotometric measurements allowed us to demonstrate that photoreduction of oxygen by the so-called Mehler reaction is the main electron sink at the onset of photosynthesis and during steady state photosynthesis. When Symbiodinium cells were exposed to high light conditions, the Mehler reaction and the ascorbate-glutathione cycle (water-water cycle) acted as a safety valve and drained up to 50% of the electrons from PSII, protecting it from photoinhibition and dissipating rapidly the excess photon energy by downregulation of PSII. As long as the WWC efficiency was maintained in the chloroplasts of Symbiodinium, ROS generated as a by-product of the Mehler reaction did not significantly damage target molecules and induced an acclimatory response through up-regulation of enzymes involved in the antioxidant response (superoxide dismutase, ascorbate peroxidase, glutathione reductase). Nevertheless, when cells were exposed to light stress and elevated temperature (33°C), the WWC supported 75% of the electrons coming from PSII. This increase generated twice more H2O2 than during the treatment at 26°C and resulted in the inactivation of target enzymes of the WWC. Therefore, this means that under these conditions the photoprotective functions of the WWC can no longer be maintained, thus opening the way to ROS accumulation and to the induction of coral bleaching.We found that the response to oxidative stress differed between and within Symbiodinium clades. Symbiodinium clade A was less sensitive to the chemical induced oxidative stress than the others investigated strains. These variations are most likely related to their geographic origin, their thermal history, as well as to their physiological adaptations to the local environment. They may contribute to the explanation of why coral colonies and coral species have been found to differ in their susceptibilities to bleach. However, although the antioxidant response differs to some extent, some common traits were conserved. Among them, Diatoxanthin, a xanthophyll pigment involved in the non-photochemical quenching process could also have an antioxidant function. In addition, it seems that the ubiquitin-proteasome pathway is involved in the antioxidant response by eliminating carbonylated protein. [less ▲]

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See detailOptimal design of a CO2 capture unit with assessment of solvent degradation
Léonard, Grégoire ULg

Doctoral thesis (2013)

CO2 capture in power plants by absorption in amine solvents is a technology aiming at the reduction of CO2 emissions while simultaneously addressing the growth of the global energy demand. However, the ... [more ▼]

CO2 capture in power plants by absorption in amine solvents is a technology aiming at the reduction of CO2 emissions while simultaneously addressing the growth of the global energy demand. However, the energy impact of this technology on the power plant efficiency is high and amine solvent degradation induces a non-negligible environmental impact. The main innovation of this thesis is to combine both aspects within a process model based on experimental data of solvent degradation. This model leads to the identification of optimal operating conditions for the CO2 capture process, from an energetic as well as environmental point of view. [less ▲]

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See detailPrediction of DP steel fracture by FEM simulations using an advanced Gurson model
Fansi Tchonko, Joseph ULg

Doctoral thesis (2013)

This numerical investigation of an advanced Gurson–Tvergaard–Needleman (GTN) model is an extension of the original work of Ben Bettaieb et al. (2011). The model has been implemented as a user-defined ... [more ▼]

This numerical investigation of an advanced Gurson–Tvergaard–Needleman (GTN) model is an extension of the original work of Ben Bettaieb et al. (2011). The model has been implemented as a user-defined material model subroutine (VUMAT) in the Abaqus/explicit FE code. The current damage model extends the previous version by integrating the three damage mechanisms: nucleation, growth and coalescence of voids. Physically based void nucleation and growth laws are considered, including an effect of the kinematic hardening. These new contributions are based and validated on experimental results provided by high-resolution X-ray absorption tomography measurements. Also, the numerical implementation of the kinematic hardening in this damage extension has obliged to readapt the classical triaxiality definition. Besides, a secondary fracture initiation criterion based on the ultimate average inter-cavities distance has been integrated to localize and quantify with good accuracy the strain distribution just before the material fails apart. The current damage model is applied in industrial conditions to predict the damage evolution, the stress state and the fracture initiation in various tensile thin flat sheet geometries and the cross-die drawing tests. [less ▲]

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See detailOptimalisation de la radiosynthèse et production au niveau de la curie d'acides aminés aromatiques marqués au fluor-18
Libert, Lionel ULg

Doctoral thesis (2013)

6-[18F]fluoro-L-dopa (FDOPA) and 2-[18F]fluoro-L-tyrosine (FTYR) are useful radiopharmaceuticals for evaluation by positron emission tomography (PET) of the dopaminergic function and oncological studies ... [more ▼]

6-[18F]fluoro-L-dopa (FDOPA) and 2-[18F]fluoro-L-tyrosine (FTYR) are useful radiopharmaceuticals for evaluation by positron emission tomography (PET) of the dopaminergic function and oncological studies, respectively. In comparison to electrophilic synthesis, the no-carrier-added (nca) nucleophilic preparation of these 2 radiopharmaceuticals, described in 2004 by Lemaire et al, has several advantages such a high batch yield and high specific activity. However, this nca enantioselective synthesis using a chiral phase-transfer catalyst requires some chemicals (i.e. corrosive HBr gas) arduous to handle and store and reactions at low and high temperature (0°C, 200°C) difficult to implement into a commercially available synthesizer. Important chemical improvements, realized during this PhD thesis, having resulted in straightforward automation of FDOPA and FTYR synthesis, in a commercially available FASTLab module (GE healthcare) are presented. The first significant improvement to the synthesis has consisted in the development of a fast and reliable method suitable for the preparation of (substituted) [18F]fluorobenzyl halides from several [18F]fluorobenzaldehydes. Aromatic nucleophilic substitution of trimethylammonium benzaldehyde triflate and nitro precursors were realized with nca [18F]fluoride. After labeling, [18F]fluorobenzaldehydes were trapped on a Solid Phase Extraction (SPE) cartridge and the subsequent conversion (reduction and halogenation) into benzyl halides was directly realized, on-line, on the support. Reduction of the aldehydes and the following halogenation step were performed with an aqueous solution of NaBH4 and aqueous solutions of concentrated acid (HI, HBr, HCl), respectively. These two near-quantitative reactions proceed at room temperature within 2 minutes at high yields. The second improvement of the nca synthesis of FDOPA and FTYR has consisted in the enantioselective formation of a new carbon-carbon bond by phase-transfer catalysis in presence of a chiral phase-transfer catalyst (PTC) at RT rather than at 0°C. Seven chiral phase-transfer catalysts with a potential high enantioselectivity, at room temperature, for the asymmetric alkylation of a N-(diphenylmethylene)glycine tert-butyl ester have been prepared. Two of these catalysts affords high enantiomeric excess in FDOPA and FTYR (e.e. ≥ 95%) at room temperature and even at 75°C (e.e. ≥ 90%). One is readily available from a cinchona alkaloid and the other one from a biphenyl substrate. The third improvement concerned the hydrolysis step (200°C, 20 min). Different starting precursors with more labile protective groups than the methoxy were synthesized and evaluated. Among these compounds, the isopropyl ether protective group seems the more advantageous. By exploiting the advantages of the improvements to the chemistry described in this work and the potential of the nca approach, the synthesis of FDOPA and FTYR was automated in a FASTlab module with GMP single use cassettes. After 100 min of bombardment (167 GBq) and 63 min of synthesis, more than 50 GBq (1,35 Ci) of 6-[18F]fluoro-L-dopa (e.e. ≥ 96,3%) with a specific activity in excess of 0.75 TBq/µmol are routinely produced. For FTYR, slightly higher yield was obtained. With such reliable production, 6-[18F]fluoro-L-dopa and 2-[18F]fluoro-L-tyrosine are now available for clinical investigation. [less ▲]

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See detailStratégies et représentations de l'apprentissage du français langue étrangère chez des lycéens vietnamiens : description et étude de leur rapport avec les compétences linguistiques
Nguyen, Huu Binh ULg

Doctoral thesis (2013)

Strategies that language learners use and their beliefs about language learning are fields that have interested many researchers in recent years. So, what are language learning strategies used by ... [more ▼]

Strategies that language learners use and their beliefs about language learning are fields that have interested many researchers in recent years. So, what are language learning strategies used by Vietnamese learners of French as foreign language? What are their beliefs concerning language learning? Is there any relationship between these elements and proficiency? This is what we propose to study in this doctoral work using quantitative approach with three main research tools: the Strategy Inventory for Language Learning (Oxford, 1990), the Beliefs About Language Learning Inventory (Horwitz, 1988) and a linguistic test. We start this research by meeting the important requirement of the cross-cultural validation of the adopted questionnaires. Then, statistical analysis (descriptive and inferential) will allow us to answer to research questions. The results show that Vietnamese learners have limited and varied strategy use and they have different beliefs about the learning of French as a foreign language. Furthermore, the relationship between strategy use and representations, on the one hand, and between these elements and proficiency, on the other hand, is statistically significant. However, it is fairly complex. To conclude this thesis, we will try to provide possible explanations and point out implications. This discussion will lead to some recommendations aimed at different players involved in the teaching/learning of French in Vietnam. [less ▲]

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See detailProtein Identification and Quantification in Mixtures of highly-modified Proteins
Dobson, Rowan ULg

Doctoral thesis (2013)

The identification and quantification of proteins in highly-modified mixtures using proteomics has been performed. Two research projects have been undertaken which fulfil this aim. The first comprised the ... [more ▼]

The identification and quantification of proteins in highly-modified mixtures using proteomics has been performed. Two research projects have been undertaken which fulfil this aim. The first comprised the development of quantitative methods to detect trace amounts of hazelnut and soy in complex mixtures. A method for the detection and absolute quantification of Cor a 9, a major hazelnut (Corylus avellana) allergen was developed based on mass spectrometry. One hundred and ten hazelnut proteins were detected, five of which were allergens. The peptide chosen for quantification was from Cor a 9 (11S globulin-like protein). Two specific fragmentation reactions were chosen in multiplexed Selected Reaction Monitoring (SRM). Forty three hazelnut food processing imitation samples, varying a range of factors, such as the temperature and incubation time were analysed. A calibration curve was made for cookies. The developed method was for home-made cookies, shop-bought cookies and chocolate. The quantities of Cor a 9 in each sample were determined from the quantification of the target peptide using isotopic dilution with a heavy isotopically labelled peptide. A second peptide with two transitions was also proven to be a possible alternative as a detection method for hazelnut. The presence of soybean allergens in processed food can be detected using the mass spectrometric identification of a soybean peptide which is resistant to the heating and chemical reactions associated with food processing. The proteomic analysis of soybeans allowed the identification of 11 allergens. A method using a peptide (VFDGELQEGR) from glycinin G1 (Gly m 6.0101) was developed for the detection and semi-quantification of the allergen in food samples. Two specific fragmentation pathways were chosen in selected reaction monitoring for unambiguous identification of glycinin G1 and were: 575.3 903.4 Da and 575.3 788.4 Da. Sixteen imitation samples of processed food spiked with soybean were analyzed, where factors such as temperature and incubation time were varied, and the chosen transitions were detected. The developed method was specific for home-made cookies and a shop-bought biscuit. Semi-quantification from both cooked and uncooked cookies was demonstrated. The second comprised the identification and quantification of conotoxins in the venom of Conus textile by the use of isotope coded affinity tagging (ICAT) and label-free quantification. The extreme variety and complexity of the conotoxins has been insufficiently documented and this research demonstrates the varied nature of conotoxins found in different parts of the venom duct and their patterns of expression. Fifteen conotoxins, several with different post-translational modifications (PTMs), were identified and quantified. Distinctive patterns emerged, with the largest group of conotoxins increasing, then peaking in the central6 proximal part, before decreasing; whilst the second largest group peaked in the distal region, generally displaying nothing in the first parts. A new conotoxin, PCCSKLHDNSCCGL*, was sequenced. [less ▲]

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See detailTesting candidate effectors contributing to resistance to pneumoviruses
Dermine, Martin ULg

Doctoral thesis (2013)

Pneumoviruses are members of the Paramyxoviridae family, negative sense single stranded RNA viruses. The 3 major members of the pneumovirus genus are human respiratory syncytial virus (huRSV), bovine ... [more ▼]

Pneumoviruses are members of the Paramyxoviridae family, negative sense single stranded RNA viruses. The 3 major members of the pneumovirus genus are human respiratory syncytial virus (huRSV), bovine respiratory syncytial virus (boRSV) and their murine counterpart, pneumonia virus of mice (PVM). In humans, huRSV mainly infects young children and can lead, in the worst cases, to infantile bronchiolitis, which is the first cause of children hospitalization and concerns 2.3% of children under the age of one. Many laboratories are studying this disease in order to better understand the role played by the immune system on its pathogenesis and to create an efficient and safe vaccine that does not exist for now. In bovine, boRSV generates stable epidemics in calves under 6 months of age and causes important economic losses in terms of veterinary costs and loss of productivity. These viruses infect the respiratory tract and generate a disease that importantly depends on the genetic background of the host. The quality of the immune response plays a considerable role in the expression as well as in the outcome of the disease, especially during its first instants. The study of pneumoviruses diseases has been widely developed using murine models of infection by heterologous huRSV. It is now assumed that this model, although providing interesting information, only weakly reproduces human disease on the contrary to infection of mice with their homologous pneumovirus: PVM. This model has been broadly developed in our laboratory, by highlighting the similarities between murine, human and bovine diseases, i.e. an important morbidity, intra-pulmonary granulocytic influx, viral amplification and evolution toward acute respiratory distress syndrome. The present work consisted in studying potential effectors of the resistance of mice against PVM infection: two proteic and two cellular effectors. A first working hypothesis was to evaluate the role of Carcinoembryonic antigen-related cell adhesion molecule 1 (Ceacam1) as a potential receptor for PVM. This membrane protein present at the surface of respiratory epithelial cells is known to be mutated in SJL/J mice, the most resistant strain to PVM infection. We have thus infected highly PVM-susceptible 129/Sv mice and compared their susceptibility to Ceacam1a knock-out 129/Sv mice. Our results have permitted to discard Ceacam1a as a receptor to PVM. The second tested protein is bovine Mx1 (boMx1) GTPase. We wished to assess if its expression could lead, as it is the case for numerous negative sense single stranded RNA viruses, to a resistance to PVM. Transgenic mice producing boMx1, engineerd in our laboratory in an FVB/J background, have been infected and their susceptibility has been compared to wild-type FVB/J mice. We could evidently demonstrated that boMx1 induces resistance to PVM. We have thus, for the first time, demonstrated that an Mx protein induces resistance to a pneumovirus. We have then compared 2 inbred mice strains presenting opposite phenotypes concerning their susceptibility to PVM: SJL/J (resistant) and 129/Sv (susceptible). Our goal was to evaluate if the difference in resistance is present during the first moments of infection. Therefore, we have focussed on both cell types that first interact with the virus: respiratory epithelial cells and alveolar macrophages. Virus tropism and respiratory epithelial permissivity to viral amplification were compared between both strains. In the same way, alveolar macrophages’ phenotypes (phagocytosis, susceptibility to viral infection, cytokine production) were compared between SJL/J and 129/Sv. Our results could not demonstrate any difference concerning respiratory epithelium. On the other hand, a pivotal role could be attributed to alveolar macrophages in the first instants of the infection. SJL/J alveolar macrophages presented greater phagocytic capacity, increased resistance to virus replication and earlier and higher cytokine production. Our results concerning the role of alveolar macrophages as a key effector of the immune response during the infection of mice by PVM raises new interrogations. Differences observed between SJL/J and 129/Sv alveolar macrophages regarding their resistance to viral infection, their greater phagocytic capacity and their cytokine secretion will have to be further investigated in order to understand the relative importance of these three characteristics in the resistance process of SJL/J to PVM infection. A particular attention will have to be given to the candidate cytokines in order to determine if one of them plays a particular role in the disease outcome. Moreover, the anti-PVM property of boMx1 raises the question of why boMx1 possesses an anti-PVM property but no anti-boRSV effect. Comparison of the interaction of boMx1 with PVM or boRSV could help understanding this anti-PVM effect. [less ▲]

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See detailLa réforme du Conseil de sécurité et les relations internationales. Processus, Acteurs et Enjeux
Mputu-Jngole, Jean-Claude ULg

Doctoral thesis (2013)

The UN has committed in recent years in a long process of reform to adapt to the changing world. If several reforms have emerged, Member States are unable to agree on the content of the reform of the ... [more ▼]

The UN has committed in recent years in a long process of reform to adapt to the changing world. If several reforms have emerged, Member States are unable to agree on the content of the reform of the Security Council. The present thesis analyzes this process through the positions of the players to highlight the issues of the reform in international relations from the perspective of power. [less ▲]

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See detailContribution to the Inverse Dynamics of Flexible Manipulators
Guimaraes Bastos Junior, Guaraci ULg

Doctoral thesis (2013)

This thesis studies innovative, stable but non-causal inverse dynamics algorithms for flexible manipulators. Robust direct optimal control methods are proposed. The nonlinear finite element method is used ... [more ▼]

This thesis studies innovative, stable but non-causal inverse dynamics algorithms for flexible manipulators. Robust direct optimal control methods are proposed. The nonlinear finite element method is used to derive the mechanical model of the multibody system and the time discretization is performed using the generalized-alpha method. The sparse gradients of the optimization constraints are computed using a semi-analytical method. The inverse dynamics of both serial and parallel kinematic manipulators with flexible links and joints is successfully studied using the proposed method. Finally, the possible extension of the method for the integrated control/structure optimization of mechatronic systems is investigated. [less ▲]

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See detailCost monitoring in dairy farms to promote the value chain of fresh milk in North Vietnam
Bui, Thi Nga ULg

Doctoral thesis (2013)

In Vietnam, the consumption of dairy products has increased dramatically in recent years due to rising incomes. To meet this growing demand, and reduce imports, the Vietnamese Government has encouraged ... [more ▼]

In Vietnam, the consumption of dairy products has increased dramatically in recent years due to rising incomes. To meet this growing demand, and reduce imports, the Vietnamese Government has encouraged milk production. In this context, our research is primarily interested in the distribution of value added among the actors within the fresh milk chain observed in the province of Son La. Our study demonstrates that value added within the fresh milk chain was unequally distributed among actors in the chain in the bias orientation to the non-farmers (nonproducer). The key feature in the chain was the dairy farmers, but they were also the most vulnerable actors of the chain. Given the balance of power among the actors, the most appropriate method to promote the added value for dairy producers is to help a better control on their production costs by improving the management at the dairy farm. In the second part of the work, we are inspired from foreign experience in this field to define an accounting system for technical-economic monitoring of dairy cattle adapted for the situation of Vietnamese farmers. This system has been tested in Moc Chau in an experimental dairy farm to provide data regarding the efficiency and profitability of operations. Dairy farmers were interested in the proposed monitoring system because it allows them to know the level of performance and to compare it to the others. They were interested in revenue generated from costs control. The major constraints in the application of this monitoring in selected farms were the lack of capacity and knowledge from producers. In conclusion, our study provides an appropriate model for the establishment of a management system of milk production. The most suitable model is to set up an independent agency. The cost of this monitoring was estimated, and scenarios for sustainability have been proposed. Contributing to lower costs through a better understanding of technical and economic performance of farmers, the service management operations will improve the competitiveness of locally produced milk with imported products. [less ▲]

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See detailEstimation des débits d'étiage pour des sites non jaugés. Application en Région wallonne.
Gailliez, Sébastien ULg

Doctoral thesis (2013)

La mise en oeuvre de la Directive sur l’Eau, l’attribution des permis d’environnement et le contexte de l’hydro-électricité, demandent régulièrement la connaissance des débits caractérisant l’étiage d’un ... [more ▼]

La mise en oeuvre de la Directive sur l’Eau, l’attribution des permis d’environnement et le contexte de l’hydro-électricité, demandent régulièrement la connaissance des débits caractérisant l’étiage d’un cours d’eau. L’objectif de cette thèse est de développer un modèle permettant de définir ce débit en n’importe quel point d’un linéaire de cours d’eau non jaugé, et ce, pour n’importe quelle période de retour, ainsi que l’incertitude sur la valeur calculée. Les variables hydrologiques choisies sont le percentile95 (débit atteint ou dépassé 95 pourcents de l’année, Q95) et le MAM7 (plus faible valeur de la moyenne mobile des débits atteints pendant 7 jours consécutifs de l’année). Après avoir sélectionné les stations de mesures situées sur le territoire wallon sur base d’un certain nombre de critères (taille de l’historique, extrapolation de la courbe de tarage, présence d’algues durant la période estivale, homogénéité des données, …), une analyse fréquentielle est réalisée sur les débits caractéristiques d’étiage (Q95 et MAM7). L’extraction de paramètres physiques et climatiques des bassins versants (pente, occupation du sol, superficie du bassin versant, pédologie, hydrogéologie, précipitations, …), permet de régionaliser la zone étudiée par classification numérique. Les bassins versants des 59 stations de mesures retenues sont regroupés en quatre zones homogènes qui sont ensuite différenciées à l’aide d’une analyse en composantes principales. Suite à une analyse de la variance et considérant le nombre peu élevé de stations de mesures retenues dans certains groupes homogènes, un modèle de régression linéaire est défini pour l’ensemble de la Wallonie à partir de 24 paramètres physiques et de la méthode ‘Stepwise’, pour les périodes de retour de 2, 5, 10, 20 et 50 ans. Les modèles obtenus permettent la détermination d’une valeur de débit d’étiage en n’importe quel point d’un petit bassin versant non jaugé et l’estimation de l’incertitude sur base des intervalles de confiance. Les deux paramètres retenus dans les modèles de régression sont le coefficient de tarissement et la percolation. En imposant la forme du modèle pour chaque période de retour et en analysant la relation entre les coefficients des paramètres explicatifs et les périodes de retour, on met en évidence la possibilité d’interpoler entre les périodes de retour. Ainsi, un modèle global permettant le calcul d’un débit caractérisant l’étiage pour n’importe quelle période de retour (entre 2 et 50 ans) est déduit. Les modèles de régression sont ensuite validés et une mise en oeuvre simple de ces derniers est proposée. L’identification des régions homogènes devra conduire à la construction de modèles dédiés à chaque région selon la même méthodologie, lorsque le nombre de stations disposant d’une chronique suffisante et répondant aux critères de qualité, sera suffisant dans chacune d’elles. [less ▲]

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See detailCaractères génétiques et zootechniques du porc Piétrain stress négatif en croisement avec les truies exotiques et locales au Nord du Vietnam
Do Duc, Luc ULg

Doctoral thesis (2013)

This study is concerned negative stress Piétrain pigs (Piétrain RéHal) and its use under households and farming intensive conditions in northern Vietnam to improve the lean meat percentage of fattening ... [more ▼]

This study is concerned negative stress Piétrain pigs (Piétrain RéHal) and its use under households and farming intensive conditions in northern Vietnam to improve the lean meat percentage of fattening pigs. At the beginning, the imported purebred nucleus of Piétrain from Belgium was studied. Later, Piétrain pigs were used as the terminal boars under household and farming intensive conditions. Finally, hybrid terminal boars between Piétrain and Duroc were studied. Performance of purebred nucleus of stress negative Piétrain In 2007, a total of 19 pigs of purebred Piétrain RéHal (6 males and 13 females) aged approximately 2 months was imported into North Vietnam from the Experimental farm of the Faculty of Veterinary Medicine of the University of Liège. At the first time, the production performance of the first imported pigs was studied since their arrival to 8.5 months of age. The average body weights of this nucleus at the age of 2, 4, 5.5 and 8.5 months were 19.05, 51.05, 85.82 and 119.47 kg respectively. The average daily gain and the lean meat percentage of these animals are 528.56 g/d and 64.08% respectively. The males (546.48 g/d) grew faster than females (520.29 g/d); however this difference was not significant (P> 0.05). The same trend was present in both sexes for the percentage of lean meat (65.26 vs. 63.44%). The feed conversion ratio was 2.69 kg. Stress negative Piétrain pig could develop well on farm conditions in Hai Phong province, Vietnam. In the second time, the initial nucleus was multiplied. Reproduction and production performances and the semen quality of purebred nucleus were studied. No significant differences were observed between the halothane genotypes (CC and CT) of sows for reproduction traits (P>0.0578). At the age of 7.5 months, body weight, backfat thickness and longissimus depth of CC pigs were higher than those of CT (P <0.05). Compared to sows born in Belgium, sows born in Vietnam had a longer gestation (117.42 vs. 116.38 days), more piglets born alive (8.73 vs. 6.99) and heavier average litter weight (12.37 vs. 10.04) at birth (P <0.01). Gilts had more lean meat (P<0.01) than intact boars (65.00 vs. 64.03%). The total number of spermatozoa per ejaculat of boars born in Vietnam was higher (P<0.001) than that those of boars born in Belgium (114.54x109 vs. 80.47x109). This value of CC boars was higher than those of CT (P<0.05). Compared with observations made in temperate countries, the reproduction and production performances, sperm concentration and total number of spermatozoa of Piétrain pigs were reduced, whereas lean meat percentage was not affected. The results support the interest of the use of this new Piétrain line in tropical countries with ecological and climatic conditions similar to Vietnam. Utilization of stress negative Piétrain pigs under household conditions In the next step, Piétrain pigs were used as terminal boars under household conditions for the production of fattening pigs. The hybrid sows between Large White and Mong Cai (F1) mated to Duroc (DU) or Piétrain (PI) boars to the production of the two types of fattening pigs as following: 1) DuxF1 and 2) PIxF1. Reproduction and production performances, carcass characteristics as well as meat quality were evaluated. The results show that household affected production performances, carcass, and meat quality traits (P<0.05) as well as reproduction (weights at birth and weaning, P<0.01). Inversely, boar breeds did not influence (P>0.06) on reproduction traits (except individual weight of born alive pigs and weaned pigs, P<0.01), production traits, meat chemical composition and meat quality (except pH at 4 days post mortem, P<0.05) while lean meat percentage of Piétrain-sired pigs was higher than those of Duroc-sired pigs (P<0.05). The utilization of Piétrain boars does not affect reproduction performances, growth rate and meat quality while improving lean meat percentage in comparison to Duroc boars. This suggests that the use of stress-negative Piétrain boars as terminal sires would improve lean meat percentage under household conditions in North Vietnam. Utilization of stress negative Piétrain pigs in the farming intensive conditions In the farming intensive conditions, Piétrain pigs are also used as the terminal boars to the production of 3-ways fattening pigs and as the genetic resource to the production of hybrid terminal boars with Duroc. Production performance, carcass traits and meat quality of 3-ways fattening pigs [Px(LxY)] between Piétrain boars (P) and Landrace x Large White sows (LxY) had been studied. Barrows grew faster (P=0.0171) than gilts (670 vs. 631 g/d) but had less (P=0.0015) lean meat percentage (58.6 vs. 60.4%). However, sex did not affect carcass and meat quality traits (P>0.0656). The pH values of longissimus dorsi muscle of barrows and gilts at 45 minutes (6.38 and 6.43) and 24 hours (5.46 and 5.49) post mortem were similar (P>0.312). This pH value corresponds to a normal meat. Crossbred fattening pigs from stress negative Piétrain sires mated to Landrace x Large White sows under intensive production system presented normal growth rate, high lean meat percentage and satisfactory meat quality. This suggests that the use of stress negative Piétrain boar under farming intensive conditions in northern Vietnam could improve lean meat percentage while not affecting growth rate and meat quality. The Piétrain pig is not only used as a terminal sire, but also as a genetic resource to the production of hybrid terminal boars according different component of Piétrain and Duroc. Five genetic groups PiDu25, PiDu50, PiDu75, PiCC and PiCT were hybrid boars with 25, 50 and 75% of Piétrain origin and purebred Piétrain with halothane genotypes CC and CT respectively. The results showed that genetic group has a significant effect on growth performance and semen quality (P<0.05). The hybrid boars had better growth rate (577.48 to 635.07 g/d) than purebred stress-negative Piétrain (516.00 to 552.93 g/d), but lean meat percentage was lower (59.02 to 63.57 for hybrids vs. 63.87 to 65.11 % for purebred Piétrain). The increased proportion of Piétrain in hybrids boars did not affect the growth rate (P> 0.05), while it has a significant effect on the lean meat percentage (P <0.05). The total number of spermatozoa of PiDu75 (53.78x109) and PiCT (49.83x109 spermatozoa) is lower than those of other genetic groups (92.27x109 to 93.99 x109 spermatozoa). The total number of spermatozoa was affected by the seasons of the year (P<0.01). This value was lower during the hot period (summer and autumn) and higher during the cold period (winter and spring). The Piétrain x Duroc hybrid boars, especially PiDu75 seem to be promising as terminal boars to improve growth rate of fattening pigs while still maintaining high lean meat percentage. Cette étude aborde les porcs de Piétrain stress négatif (Piétrain RéHal) et son utilisation dans les conditions d’élevage familial et intensif au nord du Vietnam pour améliorer le pourcentage de viande maigre des porcs d’engraissement. Le noyau de Piétrain pur importé de la Belgique a d’abord été étudié. Ensuite, les porcs de Piétrain ont été utilisés comme verrats terminaux dans les conditions d’élevage familial et intensif. Enfin, des verrats hybrides terminaux Piétrain x Duroc ont été étudiés. Performances du noyau pur de porc Piétrain stress négatif En 2007, Un total de 19 porcs de Piétrain pur RéHal (6 mâles et 13 femelles) âgés d’environ 2 mois, a été importé au nord du Vietnam au départ de la ferme expérimentale de la Faculté de Médecine Vétérinaire de l’Université de Liège. Dans un premier temps, les performances de production de ces premiers porcs ont été étudiées depuis leur arrivée jusqu’à 8,5 mois d’âge. Le poids vif moyen de ce noyau à l’âge de 2 ; 4; 5,5 et 8,5 mois était respectivement de 19,05 ; 51,05 ; 85,82 et 119,47 kg. Le gain quotidien moyen et le pourcentage de viande maigre de ces animaux sont respectivement 528,56 g/j et 64,08 %. Le gain quotidien moyen était plus important chez les mâles (546,48g) que chez les femelles (520,29 g) cependant cette différence n’est pas significative (P>0,05). La même tendance existait entre les deux sexes pour le pourcentage de la viande maigre (65,26 vs 63,44 %). L’indice de conversion alimentaire était de 2,69 kg. Le porc Piétrain stress négatif pourrait bien se développer dans les conditions de la ferme à Hai Phong, au Vietnam. Dans un deuxième temps, le noyau de départ fut multiplié. Les performances de reproduction et de production et qualité du sperme des animaux issus de ce noyau pur ont été étudiées. Aucune différence n’a été observée entre les génotypes CC et CT chez les truies pour ce qui concerne les caractères de reproduction (P> 0,0578). À l'âge de 7,5 mois, le poids vif, l’épaisseur du lard dorsal et l’épaisseur du carré de porcs CC étaient plus élevées que ceux de CT (P<0,05). Par rapport aux truies nées en Belgique, les truies nées au Vietnam avaient une plus longue durée de gestation (117,42 vs 116,38 jours), plus de porcelets nés vivants (8,73 vs 6,99) et le poids moyen d’une portée à la naissance plus lourd (12,37 vs 10,04, P<0,01). La teneur en viande maigre chez les femelles (65,00 %) était supérieur (P<0,01) à celle chez les mâles intacts (64,03 %). Le nombre de spermatozoïdes par éjaculat de verrats nés au Vietnam était supérieur (P<0,001) que celui de verrats nés en Belgique (114,54x109 vs 80,47x109). Cette valeur de verrats CC était supérieure à celle de CT (P<0,05). En comparaison avec les observations faites dans les pays tempérés, les performances de reproduction et de production, la concentration du sperme et le nombre total de spermatozoïdes de porcs Piétrain ont été diminués, néanmoins le pourcentage de viande maigre n'a pas été affecté. L’implication possible de ce résultat pour la production porcine dans les pays tropicaux ayant des conditions écologiques et climatiques comme celles du Vietnam. Utilisation de porc Piétrain stress négatif dans les conditions d’élevage familial Dans l’étape suivant, les porcs Piétrain sont utilisés comme les verrats terminaux dans les conditions d’élevage familial pour produire les porcs d’engraissement. Les truies hybrides entre Large White et Mong Cai (F1) croisent soit avec les verrats Duroc (DU), soit avec Piétrain (PI) pour produire 2 types des animaux d’engraissement à savoir : 1) DuxF1 et 2) PIxF1. Les performances de reproduction, production, caractères de carcasse et la qualité de la viande ont été évalués. Les familles-éleveurs ont affecté les caractères production, de carcasse, et de qualité de la viande (P <0,05) ainsi sur reproduction (les poids de porcelets à la naissance et au sevrage, P <0,01). A l'inverse, les types de verrats n’ont pas influencé (P>0,06) sur les caractères de reproduction (à l'exception du poids individuel des porcs nés vivants et des porcs sevrés, P <0,01), de production, la qualité de la viande (sauf le pH obtenu à 4 jours post mortem, P <0,05). Cependant la teneur en viande maigre des porcs PIxF1 était plus élevé que cela de DUxF1 (P<0,05). Ces résultats ont montré que le pourcentage de viande maigre des porcs d’engraissement dans les conditions d’élevage familial au nord du Vietnam peut être amélioré en utilisant le verrat Piétrain dans le croisement terminal à la place du verrat Duroc sans affecter le gain quotidien moyen. Utilisation de porc Piétrain stress négatif dans les conditions d’élevage intensif Dans les conditions d’élevage intensif, les porcs de Piétrain sont également utilisés comme les verrats terminaux pour produire les porcs d’engraissement à 3 voies ainsi que comme la source génétique pour produire les verrats terminaux hybrides avec Duroc. Les performances de productions, carcasse et qualité de la viande des porcs d’engraissement à trois voies [Px(LxY)] entre les verrats Piétrain (P) et les truies Landrace x Large White (LxY) ont été étudiées. Les mâles castrés présentaient une vitesse de croissance plus rapide (P=0,0171) que les femelles (670 vs 631 g/j), cependant le pourcentage de viande maigre avait présenté une tendance inversée (58,6 vs 60,4%, P=0,0015). Le sexe n’a pas affecté les caractères de la carcasse et la qualité de viande (P>0.0656). Le pH du carré chez les mâles castrat et femelles à 45 minutes (6,38 et 6,43) et à 24 heures (5,46 and 5,49) post mortem était similaire (P>0,312). Cette valeur de pH correspond à une viande normale. Les porcs d’engraissement issus du croisement entre le père Piétrain et la mère Landrace x Large White dans les conditions d’élevage intensif ont présenté une vitesse de croissance normale, une teneur en viande maigre élevé et une viande de qualité satisfaisante. Ceci suggère que l'utilisation de stress négatif sanglier Piétrain dans les conditions d'élevage intensif au nord du Vietnam pourrait améliorer la teneur en viande maigre en n'affectant pas le gain quotidien moyen et la qualité de la viande. Le porc Piétrain n’est pas seulement utilisé comme un verrat terminal, mais encore comme une source génétique pour produire des verrats terminaux hybrides en fonction de taux différent de Piétrain et Duroc. Cinq groupes génétiques PiDu25, PiDu50 et PiDu75, PiCC et PiCT étaient les verrats avec respectivement 25, 50 et 75% d’origine Piétrain et Piétrain pur avec les génotypes CC et CT. Les résultats ont montré que le groupe génétique avait un effet sur les performances de production et qualité du sperme (P<0,05). Les verrats hybrides présentent généralement une vitesse de croissance (577,48 à 635,07 g/j) supérieure que ceux de Piétrain pur (516,00 à 552,93 g/j), mais avec une teneur en viande maigre est inférieure (59,02 à 63,57 vs 63,87 à 65,11 %). L’augmentation de proportion de Piétrain chez les verrats hybrides n’a pas affecté sur la vitesse de croissance (P>0,05) alors qu’elle exerce un effet significatif sur le pourcentage de viande maigre (P<0,05). Le nombre total de spermatozoïdes des verrats PiDu75 (53,78x109) et PiCT (49,83x109) est inférieur à celui des autres groupes (92,27x109 à 93,99x109). Le nombre total de spermatozoïdes a été affecté par les saisons de l’année (P<0,01). Il était inférieur pendant la période chaude (été et automne) et supérieur en période froide (hiver et le printemps). Ces résultats montrent que les hybrides entre Piétrain et Duroc, en particulier PiDu75 semblent être prometteurs comme les verrats terminaux pour améliorer la vitesse de croissance chez les porcs d'engraissement tout en gardant le pourcentage élevé de viande maigre. [less ▲]

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See detailORF9p: a new player in the Varicella-Zoster Virus egress
Riva, Laura ULg

Doctoral thesis (2013)

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See detailExoplanet imaging with mid-infrared vector vortex coronagraphs: design, manufacture, validation and first light of the annular groove phase mask
Delacroix, Christian ULg

Doctoral thesis (2013)

During the past twenty years, detections of extrasolar planets have flourished and grown expo- nentially, reaching almost 900 confirmed exoplanets so far. This number is doubling every two or three years ... [more ▼]

During the past twenty years, detections of extrasolar planets have flourished and grown expo- nentially, reaching almost 900 confirmed exoplanets so far. This number is doubling every two or three years. The most recent discoveries made by the Kepler mission have revealed two Earth- size exoplanets orbiting the same star, and fulfilling all the required conditions to be habitable. Imaging techniques have also come a long way. Since the first direct detection in 2004, some stunning exoplanet pictures have been captured at the telescope under special circumstances of moderate contrast and/or angular separation, thanks to the advent and continuous improvement of adaptive optics systems and data reduction methods. In this broad context, the need for high contrast imaging techniques with very small inner working angles has never been so strong. Coro- nagraphy has a key role to play in order to provide the means necessary for imaging Earth-size planets, and try to answer the recurring question of the possible presence of life outside the solar system. The present thesis is dedicated to the development of the annular groove phase mask (AGPM), a specific type of broadband vector vortex coronagraph based on subwavelength gratings. Consid- ered for several years as one of the best solutions for building high-performance mid-infrared coron- agraphs with small inner working angles, the AGPM has never been validated up to now. Although various fabrication processes are available, depending on the substrates and micro-lithography techniques considered, they often face extremely challenging constraints. In the present work, we explored the feasibility of achromatic micro-components made out of subwavelength gratings, for which two technological solutions are followed: quartz and diamond. As we focussed on the diamond option, its unique material properties making it a prime candidate for mid-infrared ap- plications, we managed to develop mid-infrared broadband half-wave plates, ideally optimized to enable the manufacturing of charge-2 vortices. Following this success, we continued our devel- opments leading to the fabrication of several AGPMs for two astronomic windows, the L and N bands, and we successfully validated several L-band AGPMs on a coronagraphic test bench at the Observatoire de Paris. In the last chapter, we expose the recent installation of our components on three world-class infrared cameras, VISIR and NACO at the Very Large Telescope in Chile, and LMIRCam at the Large Binocular Telescope in Arizona. We conclude with the very first on-sky results of both N-band and L-band AGPMs, and the discovery and successful imaging of a faint stellar companion at two beamwidths from an F-type star. [less ▲]

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See detailAnalyse de la régularité hölderienne : De la théorie à l'application à des séries temporelles de températures
Deliège, Adrien ULg

Master's dissertation (2013)

Part 1 is divided in 3 chapters. Chapter 1 is devoted to the definition of the notion of Hölder exponent and its properties. Chapter 2 introduces the Hausdorff measure and dimension and their properties ... [more ▼]

Part 1 is divided in 3 chapters. Chapter 1 is devoted to the definition of the notion of Hölder exponent and its properties. Chapter 2 introduces the Hausdorff measure and dimension and their properties. Chapter 3 is about multiresolution analysis and the wavelet leaders method, the multifractal formalism used in Part 2. Part 2 consists of applications of the wavelet leaders method to analyze the Hölder regularity of some well-known functions (Chapter 4) and of surface air temperature time series (Chapter 5). [less ▲]

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See detailVisualisation magnétique de vortex dans les films minces supraconducteurs
Brisbois, Jérémy ULg

Master's dissertation (2013)

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See detailIntegration of Photovoltaic Panels Into Low-voltage Distribution Networks
Olivier, Frédéric ULg

Master's dissertation (2013)

We address in this thesis the problem of overvoltages caused by photovoltaic (PV) panels in low-voltage networks. As a solution to this problem, we propose new active network management schemes. They work ... [more ▼]

We address in this thesis the problem of overvoltages caused by photovoltaic (PV) panels in low-voltage networks. As a solution to this problem, we propose new active network management schemes. They work by modulating in an ad-hoc way the power injected by the PV inverters into the low-voltage network. Two types of control schemes are studied: centralized ones and distributed ones. The centralized schemes compute the modulation orders by exploiting an optimal power flow formulation of the problem. The distributed schemes are based on simple control logics implemented in the inverters and using only local information. Henceforth, they are less expensive to build than centralized ones. Both types of schemes are tested on a simple test network. The simulation results show that they are indeed able to control the voltages so that they stay within their limits. Moreover, the distributed schemes are shown to perform almost as well as the centralized ones, when using as performance metric the amount of energy curtailed on the PV installations. [less ▲]

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See detailDévoiler les secrets des étoiles au coeur du Cygne grâce aux rayons X
Cazorla, Constantin ULg

Master's dissertation (2013)

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See detailCharacterization of variable importance measures derived from decision trees
Sutera, Antonio ULg

Master's dissertation (2013)

In the context of machine learning, tree-based ensemble methods are common techniques used for prediction and explanation purposes in many research fields such as genetics for instance. These methods ... [more ▼]

In the context of machine learning, tree-based ensemble methods are common techniques used for prediction and explanation purposes in many research fields such as genetics for instance. These methods consist in building, by randomization, several decision trees and then aggregating their predictions. From an ensemble of trees, one can derive an importance score for each variable of the problem that assesses its relevance for predicting the output. Although these importance scores have been successfully exploited in many applications, they are not well understood and in particular, they lack a theoretical characterization. In this context, this work is a first step towards providing a better understanding of these measures from a theoretical and an empirical point of view. First, we derive, and verify empirically, an analytical formulation of the importance scores obtained from an ensemble of totally randomized trees in asymptotic conditions (i.e, infinite number of trees and infinite sample size). We then study empirically importance score distributions derived from totally randomized tree ensembles in non asymptotic conditions for several simple input-output models. In particular, we show theoretically and empirically the insensitivity of importance scores with respect to the introduction of irrelevant variables for these simple models. We then evaluate the effect of a reduction of the randomization on importance scores and their distribution. Finally, tree-based importance measures are illustrated on a digit recognition problem. [less ▲]

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See detailImpacts and mechanisms of action of endocrine disrupting chemicals on the hermaphroditic freshwater gastropod Lymnaea stagnalis (Linnaeus, 1758)
Giusti, Arnaud ULg

Doctoral thesis (2013)

Adverse impacts exerted by molecules called endocrine disruptors on reproduction have been extensively described in vertebrates. However, endocrine-disrupting chemicals might alter reproduction of ... [more ▼]

Adverse impacts exerted by molecules called endocrine disruptors on reproduction have been extensively described in vertebrates. However, endocrine-disrupting chemicals might alter reproduction of invertebrate species, at lower concentrations or through different modes of action, with consequences on population growth and stability. Among invertebrates, molluscs have been shown to be very sensitive to endocrine disruptors and were therefore proposed as model species for the development of OECD guideline for the testing and the assessment of reprotoxic effect of chemicals, including EDCs. The hermaphrodite gastropod species Lymnaea stagnalis is a candidate species for the development of such guidelines. In this context, the aim of this thesis is to provide a better understanding of the impacts and the mechanisms of action of endocrine disrupting chemicals on the reproduction of L. stagnalis. The chemicals tested in the present work were chosen based on their interactions with the endocrine system of vertebrates. Testosterone is the natural ligand of the androgen receptor in vertebrates. Three different molecules were selected for their antagonism of the androgen receptor in vertebrates: the synthetic steroid cyproterone acetate, the dicarbamide fungicide vinclozolin and the organophosphate insecticide fenitrothion. Chlordecone is an organochlorinated pesticide, which binds oestrogen receptors in vertebrates. Finally, two organotin compounds, triphenyltin and tributyltin, are able to induce the development of imposex, imposition of male sex organs in females, in gonochoric gastropod molluscs. Results of the present work are divided into two main sections. Firstly, we investigated the impacts of the selected chemicals on the reproduction of L. stagnalis. Our results displayed that TBT, TPT, and chlordecone are able to induce adverse impacts on the reproduction of L. stagnalis through a reduction of the cumulative number of eggs and clutches produced per individual. The assessment of the quality of eggs produced showed that exposure to the chemicals, except TPT, increases the frequency of abnormal eggs laid. The impacts on egg quality were observed at lower concentrations than those affecting the classical reproductive endpoints assessed in reprotoxicity tests in this species. Our results highlight that the implementation of egg quality as an endpoint should increase the sensitivity of the reprotoxicity test with L. stagnalis. The second section of results aims at providing new insights on the mechanisms of action of putative endocrine disruptors in L. stagnalis. Results from chapter 3 and 4 allowed us to select chemical treatments (testosterone, tributyltin, cyproterone acetate, and chlordecone) that induced adverse effects, by interacting with the endocrine system, on the reproduction of L. stagnalis. In Chapter 5, we analysed endogenous concentrations of testosterone, in its free and esterified forms, in the reproductive organs of L. stagnalis. Exposure to waterborne testosterone has confirmed that molluscs can take up this steroid from environmental media and that a homeostatic regulation of endogenous concentrations occurs through the esterification of steroids to fatty acid esters. Moreover, our results support that testosterone is endogenously synthesised in L. stagnalis, as it has been suggested in other mollusc species. However, the impacts on the reproduction and the modifications of endogenous concentrations of testosterone reported in this thesis could not be associated. In chapter 6, proteomic experiments were used to identify proteins differently expressed in reproductive organs of L. stagnalis exposed to testosterone, tributyltin, cyproterone acetate, and chlordecone. Modifications in the expression of three proteins involved in L. stagnalis reproduction (i.e., ovipostatin, yolk ferritin and PIWI) could be associated with the alterations of reproductive endpoints reported in chapters 3 and 4, therefore suggesting possible endocrine disruption mechanisms. Altogether, the results obtained in the present work provide evidences of interactions between chemicals and the endocrine system of this hermaphrodite species. Moreover, the additional sensitive reproductive endpoints described in this thesis (i.e., egg quality) as well as the identification of particular proteins (i.e., ovipostatin, yolk ferritin and PIWI) and their differential expression patterns following chemical exposure, provide reliable tools to screen potency of toxicants to be endocrine disruptors in a partial life cycle test on the freshwater gastropod Lymnaea stagnalis. [less ▲]

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See detailMinéralogie et propriétés physico-chimiques des smectites de Bana et Sabga (Cameroun). Utilisation dans la décoloration d'une huile végétale alimentaire
Mache, Jacques Richard ULg

Doctoral thesis (2013)

In this study, clay samples were collected in the localities of Bana and Sabga, in the regions of the west and north-west Cameroon, respectively. The purpose of this study was to determine their ... [more ▼]

In this study, clay samples were collected in the localities of Bana and Sabga, in the regions of the west and north-west Cameroon, respectively. The purpose of this study was to determine their mineralogical composition, their physico-chemical properties and to assess their potential use in the bleaching process of palm oil, which is the main edible vegetable oil produced and refined in Cameroon. <br /> The results obtained from the analyses (XRD, FTIR, DTA / TGA and SEM) revealed that montmorillonite is the main clay mineral in these materials. It is associated with kaolinite and mica. Non-clay minerals such as quartz, anatase, cristobalite, K-feldspar and heulandite are also identified in variable quantities. Chemical analyses of the major elements show that the clays from Bana and Sabga consist mainly of the follow oxides such as SiO2, Al2O3 and Fe2O3. Bana clays have a cation exchange capacity (CEC) between 50 and 60 meq/100 g and a specific surface area between 50 and 60 m2/ g. Sabga clays have a lower capacity cation exchange (38- 46 meq/100 g) and a wider range of specific surface area (33-90 m2 / g). The characterization of the natural clays allowed to select of one sample by locality for sulfuric acid treatment. <br />The acid treatment of these materials led to structural, morphological and textural changes. Analysis by X-ray diffraction showed a progressive decrease in the intensity of the (001) reflection of montmorillonite and a shift of its basal d001-value. Treatment with more acid concentration causes an increase in the surface area of the obtained products and a decrease in cation exchange capacity. <br />The assessment of the bleaching power of natural and acid-activated Bana clay in palm oil decolorization shows that the activated clay has a high bleaching capacity (~ 87%) compared to the natural clay (~ 55%). palm oil Bleaching by these clay materials does not deteriorate the bleached oil. These materials can thus be used as bleaching earths in the refining oil process. [less ▲]

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See detailRecherche de compagnons sub-stellaires par interférométrie de nulling
Marion, Lindsay ULg

Master's dissertation (2013)

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See detailImplémentation d'un Système de Contrôle Domotique
Barbette, Tom ULg

Master's dissertation (2013)

This paper presents the realization, the context, and the prospects of an automa- tion control interface. The interface is flexible, capable of adapt to all energy and all types of meters. It has been ... [more ▼]

This paper presents the realization, the context, and the prospects of an automa- tion control interface. The interface is flexible, capable of adapt to all energy and all types of meters. It has been designed for easy use, guiding the user by steps in the configuration of the interface, while allowing a relatively precise definition of the energy envelope of the house. It also responds to performance issues, allowing it to be used on computers but also smartphones and tablets. By combining these characteristics, the interface differs from what is currently being done in this area. This work is also considering some research perspectives related to the interface, such as the use of information provided by the various smart devices in the house to compute approximated consumption data, rather than using real meters, which are often expensive. [less ▲]

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See detailModeling of Electromagnetic Systems by Coupling of Subproblems – Application to Thin Shell Finite Element Magnetic Models
Dang, Quoc Vuong ULg

Doctoral thesis (2013)

The direct application of the finite element method to realistic electromagnetic problems is challenging, especially when modeling structures with thin conductive and/or magnetic parts. This work presents ... [more ▼]

The direct application of the finite element method to realistic electromagnetic problems is challenging, especially when modeling structures with thin conductive and/or magnetic parts. This work presents a subproblem method for correcting the inaccuracies inherent to classical thin shell models, and to efficiently handle geometrical and material variations in parametric studies. [less ▲]

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See detailLe Munkoyo : une source d'amylases végétales pour une boisson fermentée traditionnelle
Foma Kibwega, Roland ULg

Doctoral thesis (2013)

In Africa, several sources of amylases are not well documented. Munkoyo roots are used as the source of amylases during the traditional preparation of a fermented beverage called munkoyo. These roots are ... [more ▼]

In Africa, several sources of amylases are not well documented. Munkoyo roots are used as the source of amylases during the traditional preparation of a fermented beverage called munkoyo. These roots are unique as the synthesis and accumulation of amylases activities do not require germination. Despite this advantage, munkoyo roots are not well known as sources of amylases and they have not yet been introduced into industrial processes. Thus, the aim of this PhD project was to (1) promote munkoyo roots as sources of α- and β-amylases and to (2) propose pathways of optimization and industrialization of manufacturing munkoyo beverage. In the first part, purification, characterization and identification of α- and β-amylases from munkoyo roots was achieved. Amylases from roots of Eminia holubii, Eminia harmsiana, Rhynchosia insignis insignis and Rhynchosia insignis affinis were retained in our study. Compared to malted cereals, α- and β-amylases from munkoyo roots are more thermostable and their activities are optimal at high temperatures. However, these properties are closer to those of germinated cotyledons belonging to some Fabaceae family plants. Using LC-ESI MSMS analysis, this study showed significant matching of α- and β-amylases from munkoyo roots to germinated leguminous seeds. In the second part, the traditional production of munkoyo beverage was studied. The evolution of physicochemical parameters and ferments involved in spontaneous fermentation was investigated. Acidification is promoted by thermophilic and heterofermentative lactic acid bacteria. Alcohol production in munkoyo is due mainly to Saccharomyces cerevisiae. The study shows that knowledge of amylase properties and the use of an appropriate microbial starter will optimize the manufacturing process and the quality of munkoyo beverage. [less ▲]

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See detailThe role of glycine receptors during cerebral cortical development
Avila Macaya, Ariel Salvatore ULg

Doctoral thesis (2013)

This study focuses on glycine receptors (GlyR) and explores their possible physiological functions on the control of the migration of cortical interneurons and the generation of projection neurons during ... [more ▼]

This study focuses on glycine receptors (GlyR) and explores their possible physiological functions on the control of the migration of cortical interneurons and the generation of projection neurons during brain development. Chapter one is the introduction and exposes the context for the experimental work presented in the subsequent chapters. This chapter begins with a description of the characteristics of the brain in terms of its anatomy, morphology, cellular structure and functionality. Then, it focuses on general events that occur during brain development and explains, in general terms, how the main characteristics of the brain emerge starting from cycling progenitors to functional neurons. Subsequently, it separately explains the development of the two major types of neurons present in the cortex, the projection neurons and the interneurons. Following that, there is an introduction to GlyR by describing their properties and physiological roles in the functioning of the central and peripheral nervous system. Finally, the most important studies that link GlyR to a possible role on the brain development are presented and discussed. Chapter two describes the materials and methods that were used during the experimental work. Chapter three presents the results of the study in relation to the effect of GlyR and interneuron development. Based on the literature we hypothesized that activation of GlyR expressed by interneurons can trigger a sequence of molecular events that ultimately contribute to their tangential migration in the forebrain. To test this hypothesis, we performed patch-clamp recordings on interneurons migrating in brain slice culture and demonstrated the functional expression of alpha two homomeric GlyR. Complementary electrophoretic analyses (western blot) and immunolabelings were performed to: 1) confirm the results and unravel the possible dynamic changes that occurred during development; 2) get an insight in the cellular distribution of the receptors. We further explored the possible effects of GlyR activation on cell migration by using time lapse experiments in slices or explant cultures in combination with ex-vivo electroporation. These experiments demonstrated that GlyR activation can change the speed of cell migration by affecting nucleokinesis (translocation of the nucleus towards the centrosome). Therefore, we assessed the effect of GlyR activation on two processes that have been associated with the regulation of nuclear translocation, the spontaneous calcium activity and the phosphorylation of myosin II. Altogether, our results support a mechanism by which GlyR activation depolarizes cell membrane activating voltage gated calcium channels that further contribute to increase intracellular calcium concentration. This increase in intracellular calcium contributes to myosin contraction at the rear of the cell which ultimately controls the frequency of nuclear translocations. VII Chapter four presents experimental results obtained during the study of dorsal progenitors and radially migrating projection neurons. Electrophysiological experiments were carried out to identify and characterize GlyR expressed by progenitors and radially migrating neurons at embryonic day 13 (E13). In addition, calcium imaging was performed to get some insight into the cellular and molecular mechanisms downstream GlyR activation. To understand the physiological relevance of GlyR on these cells, we assessed cell proliferation using pharmacological tools and shRNA-mediated knockdown. Finally, the last two chapters are devoted to a general discussion, the conclusions of the study, and perspectives. [less ▲]

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See detailEtude de la sphéroïdisation de la perlite et de la recristallisation de la ferrite sous champ magnétique
Nutal, Nicolas ULg

Doctoral thesis (2013)

The steel industry is constantly looking for innovations and solutions to improve production processes as well as product properties. However, current technologies result from decades of development and ... [more ▼]

The steel industry is constantly looking for innovations and solutions to improve production processes as well as product properties. However, current technologies result from decades of development and thus have already reached maturity. Therefore, bright innovations have to arise from technological breakthroughs. The objective of those novelties is to induce drastic changes in terms of process or product. Magnetic heat treatment might be a solution to reach both objectives. Indeed, recent researches have shown that magnetic fields can significantly modify the transformation kinetics in steels. This can turn into very positive impacts on the metallurgical processes. However, researches on this topic are in the early stage and a lot of fields have not been studied yet. This work has been carried out in this challenging context. The main objective is to study the effect of magnetic fields on cementite spheroidization and ferrite recrystallization. So far, these two transformations involve long thermal treatments at high temperatures. Thus, a reduction of the processing time or an improvement of the mechanical properties of the steels by using magnetic field processing would be a significant improvement for this kind of thermal treatment. The transformations that are studied imply large microstructure modifications: lamellae breaks into spheroids while ferrite recrystallizes. As a consequence, the developments of dedicated microstructure characterization techniques are concomitant objectives. As it will be shown latter, we decided to develop and optimize image analysis tools. Practically, the completion of this work has required the pursuit of four objectives: Objective 1: develop an image analysis tool dedicated to pearlite spheroidization study, Objective 2: study the effect of magnetic field on cementite spheroidization, Objective 3: develop an image analysis tool dedicated to ferrite recrystallization study, Objective 4: study the effect of magnetic field on ferrite recrystallization. This work is divided in four parts described below. A general introduction constitutes the first part. It contains two chapters. Chapter I focuses on a literature review of the effect of magnetic fields on steels. The first section of this chapter deals with the basics of metallurgy and magnetism required to understand this work. Then, the reader will find a literature review about the effects of homogeneous magnetic fields on steel transformations. As it has been said before, the specificity of this work lies in the fact that the transformations studied were analysed and characterized using image analysis. The Chapter II is dedicated to this technique. The basics of image analysis are summarized in the first section of this chapter. Then, specific sections are dedicated to each step of image analysis: pre-treatment, image segmentation and characterizations. The limits of this technique, as well as its applications are described in the two last sections of this chapter. The second part of this work is divided in three chapters and deals with cementite spheroidization under magnetic field. Chapter III provides a detailed introduction to cementite spheroidization. The first section of this chapter introduces the pearlite as well as its microstructure. Using these concepts, the mechanisms and the kinetic of cementite spheroidization and cementite ripening will be introduced. Finally, the last section of this chapter will focus literature results which indicate that a potential effect of magnetic field on cementite spheroidization might be expected. After this detailed introduction, the tools used to study the cementite spheroidization under magnetic field will be described in Chapter IV. The first section deals with the characterization techniques used to study pearlite spheroidization. Then, the furnace and the heat treatments that have been performed will be described. With these tools, we will describe, in Chapter V, the results that have been achieved about cementite spheroidization under magnetic field. First, we will deeply analyse the effect of temperature and heat treatment duration on cementite spheroidization. This will be the opportunity to study in details the mechanism of cementite spheroidization and spheroids ripening. Microstructure evolutions induced by these two transformations will also be analysed. The effects of magnetic field on cementite spheroidization are described in the last section of this chapter. The analysis of the effect of magnetic field on ferrite recrystallization constitutes the third part of this work. It is divided in three chapters. Chapter VI provides a detailed introduction to ferrite recrystallization. The first section of this chapter deals with the crystalline structure defects induced by the steel forming. The detailed description of the mechanisms and the kinetics of defects elimination by the recovery, primary recrystallization and secondary recrystallization constitute the three next sections of this chapter. The last section of this chapter summarizes the results of different relevant studies on the effects of magnetic fields on these three processes. The chapter VI is followed by a detailed description of the characterization techniques as well as the heat treatment performed to study ferrite recrystallization (Chapter VII). Chapter VIII describes the results that have been obtained about ferrite recrystallization under magnetic field. We will study the effect of temperature and heat treatment duration on ferrite recrystallization. The involved transformations will be studied in detail. Finally, the effect of magnetic field on ferrite recrystallization will be discussed in the last section of this chapter. The general conclusions as well as the prospects of this work will be addressed in the fourth part of this work, respectively in Chapters IX and X. [less ▲]

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See detailCopper phthalocyanine blue pigments in conservation
Defeyt, Catherine ULg

Doctoral thesis (2013)

The phthalocyanine family, and more specifically the copper phthalocyanines (CuPcs) are the most important blue and green artists’ pigments from the end of the 20th century. This thesis focuses on the ... [more ▼]

The phthalocyanine family, and more specifically the copper phthalocyanines (CuPcs) are the most important blue and green artists’ pigments from the end of the 20th century. This thesis focuses on the CuPc blue pigments used in the artists’ paint formulations. CuPc blue extensive use as modern artists’ pigment and its implications in conservation science are pointed out. Their discovery, chemical composition, molecular structure and general properties are also reviewed. Additionally, the polymorphism and the influence of the crystal form on the final properties of the phthalo blue pigments are discussed. A methodology using non-destructive techniques and statistical analysis is then presented. This new procedure allows the identification of the CuPc crystal form in paint layers and is suitable for artwork analysis. Some CuPc polymorphs are prone to crystallization defects in presence of aromatic solvents, leading to a reduction of color strength and a shift in hue. Crystallization resistance of the CuPc polymorphs has then been assessed by means of crystallization tests performed on dry pigments and on paint films. Case studies are then presented. La famille Soler by Picasso has been studied by imaging and non-invasive analytical techniques. The successive underlying compositions have been revealed and the pigments used for the different compositions have been characterized. Then micro-samples taken from Delvaux’s paintings and Francis and Lichtenstein’s studio paints have been analyzed to characterize the blue pigments preferred by these artists. The crystal form of the phthalo blue pigments identified from four micro-samples taken from two Léger and Pechstein fake paintings have been investigated as well. Finally, the historic phthalo blue samples from the Getty Conservation Institute Reference Collection have been studied. [less ▲]

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See detail"Rends excellente ta place de l'Occident". Pour une approche intégrée de la décoration des tombes thébaines sous le règne d'Amenhotep II
Gathy, Maruschka ULg

Doctoral thesis (2013)

Sur l’ensemble des règnes de la XVIIIème dynastie égyptienne, il apparaît, jusqu’assez récemment, que celui d’Amenhotep II a suscité un intérêt moindre de la part des chercheurs, ces derniers lui ayant ... [more ▼]

Sur l’ensemble des règnes de la XVIIIème dynastie égyptienne, il apparaît, jusqu’assez récemment, que celui d’Amenhotep II a suscité un intérêt moindre de la part des chercheurs, ces derniers lui ayant préféré, de manière générale, ceux plus longs ou historiquement plus déterminants de Thoutmosis III, d’Amenhotep III ou encore d’Amenhotep IV – Akhenaton, et ce bien que plusieurs travaux fondamentaux aient déjà permis de mettre en évidence une série de traits spécifiques à cette période. Le règne d’Amenhotep II se caractérise en effet par une nouvelle gestion du gouvernement, où le phénomène d’hérédité qui s’installait progressivement dans certaines fonctions est endigué mais où, dans le même temps, les membres de quelques familles puissantes et particulièrement proches du roi se voient confier les plus hautes charges de l’administration. Aussi, pour la réalisation de leurs « demeures d’éternité », véritables cartes de visite de leurs propriétaires et témoins privilégiés des grandes orientations de l’époque, les principaux officiels du règne d’Amenhotep II ont pour la plupart porté leur choix sur la partie supérieure de la colline de Sheikh Abd el-Gourna, site particulièrement prisé pour sa position surélevée comme pour la proximité qu’il entretient avec les temples funéraires royaux. Les tombes de ces dignitaires se distinguent néanmoins de celles de leurs prédécesseurs, par des dimensions colossales, par l’étendue et la complexité des dispositifs intérieurs ainsi que par le choix de représentations et d’inscriptions qui, placées à des endroits stratégiques, soulignent les relations étroites qu’entretenait le propriétaire avec Pharaon. En outre, le traitement même des scènes figurées est également, à ce moment précis, l’objet de modifications considérables ; l’art pictural, qui se voulait depuis ses origines purement conceptuel et d’apparence hiéroglyphique, s’assouplit à divers égards pour prendre une apparence plus « sensuelle », plus « perceptuelle ». Ces transformations, qui s’amplifieront encore durant les règnes suivants, jettent déjà, en quelque sorte, les bases de ce qui deviendra la « révolution » du règne d’Akhenaton. Dans ce contexte, la présente thèse vise, au moyen d’une analyse pluridisciplinaire et « intégrée » de la décoration des chapelles du règne d’Amenhotep II, à caractériser dans une perspective socioculturelle les changements iconographiques et stylistiques qui affectent cette production artistique en pleine mutation. [less ▲]

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See detailEtude des potentialités hydrogéologiques d’une plaine alluviale en relation avec les eaux souterraines et de surface dans un contexte d’agriculture irriguée (Burkina Faso)
Sauret, Elie ULg

Doctoral thesis (2013)

The Kou river, located in the south-west of Burkina Faso, is intensively exploited for crop irrigation. However, groundwater of the alluvial plain of the Kou river could constitute an alternative to ... [more ▼]

The Kou river, located in the south-west of Burkina Faso, is intensively exploited for crop irrigation. However, groundwater of the alluvial plain of the Kou river could constitute an alternative to surface water for crop irrigation during the dry season. The objective of the present thesis is to study the alluvial aquifer of the Kou river using a approach for (i) characterizing the physical and the hydrodynamic properties of the alluvial plain, (ii) quantifying inflow and outflow in the alluvial plain, (iii) quantifying exchanged fluxes between the alluvial plain and the other reservoirs such as the Kou river and the sedimentary bedrock aquifer, and finally, (iv) calculating a groundwater balance for the alluvial plain for evaluating the volume of water available for crop irrigation. The study of the map showing the lateral and vertical heterogeneity of the alluvial plain indicates that its width is about 300 to 500 m on each side of the Kou river downstream of the Nasso/Guinguette springs. While in the centre of the catchment, the alluvial plain is constituted of clay and sand with a maximum thickness of 15 m, downstream of the catchment, the alluvial plain is constituted of clay, laterite, and weathered bedrock with a thickness of 15 to 45 m. The clayey-sandy sediments in the centre of the catchment constitute a low permeable aquifer (K=10-5 m/s) drained by the Kou river all over the year (gaining section of the river). Conversely, the sediments downstream of the catchment constitute a shallow relatively permeable aquifer (K=10-4 m/s) that drains the Kou river all over the year (losing section of the river). Water exchange between the alluvial plain and the Kou river has been quantified by water balances performed for several sections of the Kou river. Additionally, gaining and losing sections of the Kou river have been determined by direct measurements performed with seepage meters. The hydrochemical analyses performed on samples from tke Kou river, the bedrock, and the springs have shown that (i) groundwater is exchanged between the alluvial plain and the bedrock, and that (ii) Kou river is directly fed by the bedrock or indirectly through springs and alluvial plain, this power supply is facilitated by the system of fractures. The alluvial plain of the Kou river is a groundwater reservoir with a storage-drainage function. During the dry season, the alluvial plain stores groundwater coming from the bedrock and discharges it into the Kou river. Conversely, downstream of the catchment, the Kou river is drained by the alluvial plain that stores of important water resources intensively exploited for crop irrigation. [less ▲]

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See detailProjectively Invariant Quantization in Super Geometry
Leuther, Thomas ULg

Doctoral thesis (2013)

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See detailSustainable housing in Vietnam: Climate responsive design strategies to optimize thermal comfort
Nguyen, Anh Tuan ULg

Doctoral thesis (2013)

Housing issue in Vietnam is still a big concern as in 2008, 72.2% of the existing housing was semi-permanent or temporary and 89.2% of the poor did not have a permanent shelter. As a response to ... [more ▼]

Housing issue in Vietnam is still a big concern as in 2008, 72.2% of the existing housing was semi-permanent or temporary and 89.2% of the poor did not have a permanent shelter. As a response to sustainability, the global aim of this thesis is to develop design strategies toward comfortable, energy-efficient housing with acceptable building cost. Occupants’ thermal comfort is the key assessment criterion throughout the research. <br />First of all, the thesis develops a thermal comfort model for Vietnamese people living in naturally ventilated buildings through the data from field surveys around South-East Asia. This comfort model is then validated by survey data in Vietnam in 2012. <br />A new simple climate analysis tool is developed, used to analyze the climate of 3 regions in question and to draw preliminary design guidelines. A comprehensive study on climate responsive design strategies of vernacular housing in Vietnam is also carried out. The results to some extend reveal the remaining values of vernacular architecture and provide valuable lessons for modern applications. <br />Three most common housing prototypes in Vietnam are selected. Afterward a comprehensive framework is implemented to derive thermal performances of 3 typical housing types. Various techniques (in situ monitoring, building thermal simulation, CFD and airflow network model, numerical model calibration, parametric simulation method) are employed to improve the thermal performances and natural ventilation of these houses. <br />The sensitivity of building performance to the design variables is outlined by Monte Carlo-based sensitivity analysis. The thermal performances of the reference cases are optimized using the simulation-based optimization method and the most influential design variables. Optimization results show the best combinations of design strategies for each climatic region. The performances of the optimal solutions are compared with the references, providing an insight of the efficiency of this approach in building design. <br />Finally, the different objectives yielded in this thesis are summarized. The possible future extensions of this research are outlined. [less ▲]

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

Doctoral thesis (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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See detailDevelopment of a didactic SPH model
Goffin, Louis ULg

Master's dissertation (2013)

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

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

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See detailEvolution conformationnelle de peptides suite à la rupture de ponts disulfure
Hanozin, Emeline ULg

Master's dissertation (2013)

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

Doctoral thesis (2013)

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

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

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

Master of advanced studies dissertation (2013)

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

Master's dissertation (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Master's dissertation (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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